CN118027394A - Low-crosslinking polyamide and preparation method thereof - Google Patents
Low-crosslinking polyamide and preparation method thereof Download PDFInfo
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- CN118027394A CN118027394A CN202410224719.7A CN202410224719A CN118027394A CN 118027394 A CN118027394 A CN 118027394A CN 202410224719 A CN202410224719 A CN 202410224719A CN 118027394 A CN118027394 A CN 118027394A
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- 239000004952 Polyamide Substances 0.000 title claims abstract description 106
- 229920002647 polyamide Polymers 0.000 title claims abstract description 106
- 238000004132 cross linking Methods 0.000 title claims abstract description 30
- 238000002360 preparation method Methods 0.000 title claims abstract description 9
- 150000004985 diamines Chemical class 0.000 claims abstract description 43
- 238000006243 chemical reaction Methods 0.000 claims abstract description 34
- 239000003431 cross linking reagent Substances 0.000 claims abstract description 22
- 239000003054 catalyst Substances 0.000 claims abstract description 19
- -1 aliphatic diamine Chemical class 0.000 claims abstract description 13
- 239000000178 monomer Substances 0.000 claims abstract description 13
- KJOMYNHMBRNCNY-UHFFFAOYSA-N pentane-1,1-diamine Chemical group CCCCC(N)N KJOMYNHMBRNCNY-UHFFFAOYSA-N 0.000 claims abstract description 13
- 230000009471 action Effects 0.000 claims abstract description 7
- 125000001931 aliphatic group Chemical group 0.000 claims abstract description 6
- 125000003118 aryl group Chemical group 0.000 claims abstract description 6
- 239000002994 raw material Substances 0.000 claims abstract description 6
- 238000000034 method Methods 0.000 claims description 44
- VHRGRCVQAFMJIZ-UHFFFAOYSA-N cadaverine Chemical compound NCCCCCN VHRGRCVQAFMJIZ-UHFFFAOYSA-N 0.000 claims description 41
- NAQMVNRVTILPCV-UHFFFAOYSA-N hexane-1,6-diamine Chemical compound NCCCCCCN NAQMVNRVTILPCV-UHFFFAOYSA-N 0.000 claims description 41
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 claims description 33
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 31
- 239000000243 solution Substances 0.000 claims description 28
- 150000003839 salts Chemical class 0.000 claims description 27
- QQVIHTHCMHWDBS-UHFFFAOYSA-N isophthalic acid Chemical compound OC(=O)C1=CC=CC(C(O)=O)=C1 QQVIHTHCMHWDBS-UHFFFAOYSA-N 0.000 claims description 17
- 230000008569 process Effects 0.000 claims description 17
- WNLRTRBMVRJNCN-UHFFFAOYSA-N adipic acid Chemical compound OC(=O)CCCCC(O)=O WNLRTRBMVRJNCN-UHFFFAOYSA-N 0.000 claims description 15
- 239000002245 particle Substances 0.000 claims description 15
- 229920000642 polymer Polymers 0.000 claims description 15
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 14
- CXMXRPHRNRROMY-UHFFFAOYSA-N sebacic acid Chemical compound OC(=O)CCCCCCCCC(O)=O CXMXRPHRNRROMY-UHFFFAOYSA-N 0.000 claims description 13
- ACVYVLVWPXVTIT-UHFFFAOYSA-N phosphinic acid Chemical compound O[PH2]=O ACVYVLVWPXVTIT-UHFFFAOYSA-N 0.000 claims description 9
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 8
- 239000001361 adipic acid Substances 0.000 claims description 7
- 235000011037 adipic acid Nutrition 0.000 claims description 7
- 239000007864 aqueous solution Substances 0.000 claims description 7
- 229910052757 nitrogen Inorganic materials 0.000 claims description 7
- 238000006068 polycondensation reaction Methods 0.000 claims description 6
- 239000011261 inert gas Substances 0.000 claims description 5
- 238000003756 stirring Methods 0.000 claims description 5
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 4
- 239000000843 powder Substances 0.000 claims description 4
- 238000005507 spraying Methods 0.000 claims description 4
- KWSLGOVYXMQPPX-UHFFFAOYSA-N 5-[3-(trifluoromethyl)phenyl]-2h-tetrazole Chemical compound FC(F)(F)C1=CC=CC(C2=NNN=N2)=C1 KWSLGOVYXMQPPX-UHFFFAOYSA-N 0.000 claims description 3
- WAKZZMMCDILMEF-UHFFFAOYSA-H barium(2+);diphosphate Chemical compound [Ba+2].[Ba+2].[Ba+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O WAKZZMMCDILMEF-UHFFFAOYSA-H 0.000 claims description 3
- 239000001506 calcium phosphate Substances 0.000 claims description 3
- 229910000389 calcium phosphate Inorganic materials 0.000 claims description 3
- 235000011010 calcium phosphates Nutrition 0.000 claims description 3
- 230000001105 regulatory effect Effects 0.000 claims description 3
- 229910001379 sodium hypophosphite Inorganic materials 0.000 claims description 3
- ISIJQEHRDSCQIU-UHFFFAOYSA-N tert-butyl 2,7-diazaspiro[4.5]decane-7-carboxylate Chemical compound C1N(C(=O)OC(C)(C)C)CCCC11CNCC1 ISIJQEHRDSCQIU-UHFFFAOYSA-N 0.000 claims description 3
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 claims description 3
- 230000001276 controlling effect Effects 0.000 claims description 2
- 239000008188 pellet Substances 0.000 claims description 2
- 239000007789 gas Substances 0.000 claims 1
- 238000001308 synthesis method Methods 0.000 abstract description 6
- 230000000052 comparative effect Effects 0.000 description 25
- 229920001778 nylon Polymers 0.000 description 23
- 239000004677 Nylon Substances 0.000 description 20
- 230000015572 biosynthetic process Effects 0.000 description 14
- 238000003786 synthesis reaction Methods 0.000 description 13
- 239000000047 product Substances 0.000 description 11
- 239000004953 Aliphatic polyamide Substances 0.000 description 10
- 229920003231 aliphatic polyamide Polymers 0.000 description 10
- 238000004458 analytical method Methods 0.000 description 8
- 238000001514 detection method Methods 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 8
- 238000006116 polymerization reaction Methods 0.000 description 7
- 125000002843 carboxylic acid group Chemical group 0.000 description 6
- 239000004033 plastic Substances 0.000 description 6
- 229920003023 plastic Polymers 0.000 description 6
- MRNZSTMRDWRNNR-UHFFFAOYSA-N bis(hexamethylene)triamine Chemical compound NCCCCCCNCCCCCCN MRNZSTMRDWRNNR-UHFFFAOYSA-N 0.000 description 5
- 239000003112 inhibitor Substances 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 125000003277 amino group Chemical group 0.000 description 4
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- 239000012266 salt solution Substances 0.000 description 3
- 239000007790 solid phase Substances 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 239000004760 aramid Substances 0.000 description 2
- 229920003235 aromatic polyamide Polymers 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000539 dimer Substances 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 125000002467 phosphate group Chemical group [H]OP(=O)(O[H])O[*] 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- 229920005830 Polyurethane Foam Polymers 0.000 description 1
- 125000002723 alicyclic group Chemical group 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000009435 amidation Effects 0.000 description 1
- 238000011938 amidation process Methods 0.000 description 1
- 238000007112 amidation reaction Methods 0.000 description 1
- 125000006615 aromatic heterocyclic group Chemical group 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 208000012839 conversion disease Diseases 0.000 description 1
- 239000011243 crosslinked material Substances 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 229920006351 engineering plastic Polymers 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- SYECJBOWSGTPLU-UHFFFAOYSA-N hexane-1,1-diamine Chemical compound CCCCCC(N)N SYECJBOWSGTPLU-UHFFFAOYSA-N 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
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- 230000001050 lubricating effect Effects 0.000 description 1
- 229920002521 macromolecule Polymers 0.000 description 1
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- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000000269 nucleophilic effect Effects 0.000 description 1
- 238000010915 one-step procedure Methods 0.000 description 1
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- 230000002000 scavenging effect Effects 0.000 description 1
- 229920006012 semi-aromatic polyamide Polymers 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
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- Polyamides (AREA)
Abstract
The application discloses a low-crosslinking polyamide and a preparation method thereof, wherein the polyamide is prepared by taking diamine and diacid as raw materials, adding an anti-crosslinking agent, and polycondensing under the action of a catalyst; the diacid comprises aromatic diacid monomers and aliphatic diacid monomers, and the diamine comprises only aliphatic diamine monomers; the anti-crosslinking agent is pentanediamine. The low-crosslinking polyamide and the preparation method thereof provided by the application adopt a high-efficiency synthesis method to synthesize the polyamide, so that the probability of crosslinking reaction is reduced.
Description
Technical Field
The invention relates to the technical field of polyamide synthesis, in particular to low-crosslinking polyamide and a preparation method thereof.
Background
Nylon is a synthetic thermoplastic linear polyamide (a macromolecule whose molecules are bound by a particular type of bond) produced for the first time in 1935 by the american chemist walish-caloses. Polyamides are useful in a variety of applications, including apparel, reinforcements for rubber materials (e.g., tires, etc.), ropes, and plastic parts for vehicles and machinery. The wear-resistant polyurethane foam has the advantages of excellent strength, relatively good wear resistance and hygroscopicity, long service life, chemical resistance, high elasticity and easy cleaning. Nylon is often used as a substitute for low strength metals. It is the plastic of choice for components in the engine compartment of a vehicle due to its good strength, heat resistance and chemical compatibility.
The polyamides currently produced are of a wide variety, and can be classified into aliphatic polyamides, semiaromatic polyamides, wholly aromatic polyamides, heterocyclic aromatic polyamides and alicyclic polyamides according to the main chain structure. The aliphatic polyamide in the market is one with highest mechanical strength, the tensile strength, the surface hardness and the rigidity are higher than those of other nylon plastics, and the aliphatic polyamide has a larger market, can be used as engineering plastics and can be used as mechanical accessories such as gears and lubricating bearings; the non-ferrous metal material can be replaced to be used as a machine shell, an automobile engine blade and the like; even other products requiring impact resistance and high strength.
In the production practice, the aliphatic polyamide is mainly prepared by two preparation methods, namely a one-step method and a two-step method in the industry. Wherein, the one-step method is to produce the aliphatic polyamide by the polycondensation of the aliphatic diacid and the aliphatic diamine under the action of the catalyst. However, during the polymerization, bis (hexamethylenediamine) triamine (BHMT) is generated between hexamethylenediamine and hexamethylenediamine, referring to the mechanism diagram of fig. 1, and thus the wall sticking condition occurs in the reaction kettle. To solve this problem, a two-step method is adopted, which requires the adhesion to be achieved by equipment such as a drum or a twin screw, and the removal of bis (hexamethylene) triamine (BHMT), but is time-consuming and labor-consuming, and is excessively resource-consuming.
Disclosure of Invention
The application provides a low-crosslinking polyamide and a preparation method thereof, wherein the polyamide is synthesized by adopting a high-efficiency synthesis method, so that the probability of crosslinking reaction is reduced.
The low-crosslinking polyamide provided by the application is prepared by taking diamine and diacid as raw materials, adding an anti-crosslinking agent, and performing polycondensation under the action of a catalyst; the diacid comprises aromatic diacid monomers and aliphatic diacid monomers, and the diamine comprises only aliphatic diamine monomers; the anti-crosslinking agent is pentanediamine.
By adopting the technical scheme, the polyamide is synthesized by adopting a high-efficiency synthesis method, so that the probability of cross-linking reaction is reduced. Since hexamethylenediamine does not readily form by-products like bis (hexamethylenetriamine) (BHMT), the cyclization reaction that hexamethylenediamine tends to self-ring in thermal degradation reactions is reduced. Therefore, the pentylene diamine can be used as an anti-crosslinking agent to well control the generation of crosslinking matters in the reaction process, reduce the generation of similar crosslinking points and reduce the crosslinking condition in the polymerization process. In conclusion, the production efficiency can be effectively improved by adding the pentanediamine, the self-cleaning effect is achieved in the production of the reaction kettle, and the wall sticking condition of the product in the polymerization process is effectively prevented.
Preferably, the aliphatic diamine monomer comprises one of hexamethylenediamine and pentamethylenediamine.
Preferably, the aromatic diacid monomer comprises one of terephthalic acid and isophthalic acid.
Preferably, the aliphatic diacid comprises adipic acid, sebacic acid.
Preferably, the catalyst comprises at least one of sodium hypophosphite, hypophosphorous acid, phosphorous acid, hypophosphorous acid, phosphoric acid, calcium phosphate or barium phosphate.
By adopting the technical scheme, the carboxylic acid group itself can catalyze amidation and tranamination reaction in the process of polyamide synthesis, but the reaction conversion rate is low, and a catalyst is often added. Wherein the reaction of carboxylic acid groups with amine groups is believed to form dimer complexes via hydrogen bonding. The application adopts the compound with the phosphate group as the catalyst, and accelerates the synthesis of the carboxylic acid group and the amine group through the polarization of the phosphate group and the carboxylic acid group to the electron delocalized reaction site. In the amidation process, especially in the case of aromatic carboxylic acids, the activated dimer complex of carboxylic acid groups in transition state with amine groups, and the complex of carboxylic acid groups with phosphoric acid having enhanced polarization ability, promote nucleophilic attack of amine groups, thereby improving and accelerating the formation of polyamide and improving the conversion rate of polyamide.
In another aspect, the application discloses a method for preparing an oligocrosslinked polyamide, comprising the steps of: s1, under the protection of inert gas, adding diacid and diamine into an autoclave according to the total molar ratio and a certain amount of water, adding an anti-crosslinking agent and a catalyst, stirring at a certain temperature for reaction to obtain a polyamide salt water solution system, regulating the PH of the polyamide salt water solution, controlling the concentration of the polyamide salt water solution, and adding the polyamide salt water solution into the autoclave; s2, slowly boosting the polyamide salt aqueous solution in the step S1 to a certain height in a reaction kettle, and then starting to exhaust and maintain pressure until reaching a certain temperature, and starting to reduce the pressure; when the pressure is reduced to a certain value, vacuumizing is started, and after the vacuum degree is maintained at a set value for a certain time, the polyamide polymer with a certain intrinsic viscosity is prepared; s3, performing two-step operation on the polyamide polymer in the step S2, spraying polymer powder under the action of pressure, tackifying by equipment such as a rotary drum or a double screw, and the like, and granulating into particles with a specific particle size under the pressure of nitrogen when the polymer with the corresponding viscosity is measured.
By adopting the technical scheme, the low-crosslinking polyamide is synthesized by adding the pentanediamine as the crosslinking inhibitor and adopting the two-step method, so that the reaction rate can be accelerated, the crosslinked material is ensured to be adhered in the reaction kettle, the conversion rate of the polyamide is increased, and the yield of the polyamide is improved.
Preferably, in the step of S3 reaction, the polyamide polymer in the step S2 is directly pelletized under nitrogen pressure into pellets of a specific particle size.
By adopting the technical scheme, the low-crosslinking polyamide is synthesized by adopting a one-step method, the reaction rate can be accelerated, meanwhile, due to the addition of the pentanediamine, the generation of bis (hexamethylenetriamine) (BHMT) is radically reduced, two-step operation is not needed, the conversion rate of the polyamide is increased, the yield of the polyamide is improved, the energy loss in the synthesis process of the polyamide is reduced,
Preferably, in the step S1, the diacid and the diamine are present in a total molar ratio of 1:1-1:1.2.
Preferably, diacid, diamine and water are added into an autoclave, an anti-crosslinking agent and a catalyst are added, the mixture is stirred and reacted at the temperature of 50-150 ℃ to obtain a polyamide salt water solution system, the PH of the polyamide salt water solution is regulated to be 6.5-9.5, the concentration of the polyamide salt water solution is controlled to be 30-70%, and the polyamide salt water solution is added into the autoclave.
Preferably, the aqueous solution of the polyamide salt is slowly pressurized to 2-3Mpa in a reaction kettle, and the pressure is maintained by exhausting until 280-320 ℃, and then the pressure is reduced; when the pressure is reduced to normal pressure, vacuumizing is started, and the vacuum degree is maintained at-0.08-0 Mpa for a certain time, so that the polyamide polymer with a certain intrinsic viscosity is prepared.
One or more technical schemes provided by the application have at least the following technical effects or advantages:
1. the application synthesizes polyamide by adopting a high-efficiency synthesis method, and reduces the probability of cross-linking reaction. The pentylene diamine is used as an anti-crosslinking agent, so that the generation of crosslinking matters in the reaction process can be well controlled, the production efficiency is effectively improved, the self-cleaning effect is realized in the production of a reaction kettle, and the wall sticking condition of products in the polymerization process is effectively prevented.
2. The application adopts a one-step method to synthesize the low-crosslinking polyamide, which can accelerate the reaction rate and reduce the energy loss in the polyamide synthesis process; by adding the pentanediamine as the crosslinking inhibitor, the mutual reaction between the hexanediamine can be reduced, the generation of bis (hexamethylenetriamine) (BHMT) is further reduced, the phenomenon that the bis (hexamethylenetriamine) adheres to the wall is prevented, the conversion rate of polyamide is further increased, and the yield of the polyamide is improved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a diagram showing the mechanism of the generation of bis (hexamethylene) triamine (BHMT) between hexamethylenediamine and hexamethylenediamine in the prior art.
Detailed Description
The application provides a low-crosslinking polyamide and a preparation method thereof, wherein the polyamide is synthesized by adopting a high-efficiency synthesis method, so that the probability of crosslinking reaction is reduced.
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present application and the above-described drawings are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the application described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or server that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or modules not expressly listed or inherent to such process, method, article, or apparatus.
Raw materials:
adipic acid CAS No.: 124-04-9 molecular weight 146.141g/mol purity >99.0%
Sebacic acid CAS number: molecular weight 202.247g/mol purity of 111-20-6 >99.0%
Terephthalic acid CAS no: molecular weight 166.131g/mol purity of 100-21-0 >99.0%
Isophthalic acid CAS No.: 121-91-5 molecular weight 166.131g/mol purity >99.0%
Hexamethylenediamine CAS number: 124-09-4 molecular weight 116.205g/mol purity >99.0%
Pentanediamine CAS number: 462-94-2 molecular weight 102.178g/mol purity >99.0%
Hypophosphorous acid CAS number: 6303-21-5 molecular weight 63.98g/mol purity >99.0%;
Examples
Example 1 (two-step method)
S1, under the protection of inert gas, diacid and diamine are mixed according to the total mole ratio of 1:1.02 and a certain amount of water were added to the autoclave, and an anti-crosslinking agent and a catalyst were added. Stirring and reacting at 100 ℃ to obtain a nylon salt water solution system, wherein the pH value of the nylon salt water solution is 7.5, the concentration of the nylon salt water solution is 50%, and all the nylon salt water solution is added into a reaction kettle.
S2, slowly boosting the nylon salt water solution system in the step S1 to 2.7Mpa in a certain time; and when the pressure reaches 2.7Mpa, starting to exhaust and maintain the pressure until the temperature reaches normal pressure, starting to reduce the pressure, when the pressure is reduced to normal pressure, starting to vacuumize, maintaining the vacuum degree at the set value of-0.04 Mpa, and maintaining for 40min to obtain the nylon prepolymer with the set intrinsic viscosity.
S3, performing a second step of operation on the high-temperature nylon polymer of the S2, spraying polymer powder with lower molecular weight under pressure, and using equipment such as a rotary drum or a double screw to carry out tackifying, so that the molecular weight is increased and the standard viscosity is achieved. Finally, the mixture is granulated into particles with specific particle size under the pressure of nitrogen. And solid phase polycondensation is carried out on the prepared particles according to requirements to further improve the polymerization degree.
Wherein the diacid comprises adipic acid and terephthalic acid; diamines include hexamethylenediamine and pentamethylenediamine (wherein the pentamethylenediamine is present in the diamine as an anti-crosslinking agent). Specifically, the molar ratio of diamine to diacid is 1.03:1: in the addition ratio of diacid, the mole ratio of adipic acid to terephthalic acid is 0.7:1; in the diamine addition ratio, the molar ratio of hexamethylenediamine to pentamethylenediamine was 1:0.2. The above proportions are molar ratios.
In the present application, one of sodium hypophosphite, hypophosphorous acid, phosphorous acid, hypophosphorous acid, phosphoric acid, calcium phosphate, and barium phosphate is used for the selection of the catalyst. The addition amount of the catalyst is 0.05 to 0.15 percent of the total mass of the aliphatic diamine and the aromatic diacid, and the catalyst can reach the optimal concentration range.
In this example, the catalyst was used as the optimum hypophosphorous acid, and the catalyst was added in an amount of 0.10% of the total mass of diacid and diamine.
Examples 2 to 3 (two-stage method)
Examples 2 to 3 differ from example 1 in the type of polyamide synthesized, such as polyamide 6T66 synthesized in example 1. In example 2, the diacid is terephthalic acid and isophthalic acid; the diamines are hexamethylenediamine and pentamethylenediamine (wherein the pentamethylenediamine exists in the form of diamine as an anti-crosslinking agent), and the addition ratio is as follows: the molar ratio of diamine to diacid is 1.03:1: in the addition ratio of the diacid, the molar ratio of the terephthalic acid to the isophthalic acid is 0.7:1; in the addition ratio of diamine, the molar ratio of hexamethylenediamine to pentanediamine is 1:0.2; the synthesis is polyamide 6T6I.
In example 3, the diacids are terephthalic acid and decanedicarboxylic acid; the diamines are hexamethylenediamine and pentamethylenediamine (wherein the pentamethylenediamine exists in the form of diamine as an anti-crosslinking agent), and the addition ratio is as follows: the molar ratio of diamine to diacid is 1.03:1: in the addition ratio of the diacid, the mol ratio of the terephthalic acid to the decanedicarboxylic acid is 0.7:1; in the diamine addition ratio, the molar ratio of hexamethylenediamine to pentamethylenediamine is 1:0.2, and polyamide 6T610 is synthesized.
Examples 4 to 6 (one-step method)
Examples 4-6 differ from examples 1-3 in that the synthesis was performed in a one-step process. The method comprises the following specific steps:
s1, under the protection of inert gas, diacid and diamine are mixed according to the total mole ratio of 1:1.02 and a certain amount of water were added to the autoclave, and an anti-crosslinking agent and a catalyst were added. Stirring and reacting at 100 ℃ to obtain a nylon salt water solution system, wherein the pH value of the nylon salt water solution is 7.5, the concentration of the nylon salt water solution is 50%, and all the nylon salt water solution is added into a reaction kettle.
S2, slowly boosting the nylon salt water solution system in the step S1 to 2.7Mpa in a certain time; and when the pressure reaches 2.7Mpa, starting to exhaust and maintain the pressure until the temperature reaches normal pressure, starting to reduce the pressure, when the pressure is reduced to normal pressure, starting to vacuumize, maintaining the vacuum degree at the set value of-0.04 Mpa, and maintaining for 40min to obtain the nylon prepolymer with the set intrinsic viscosity.
S3, granulating the high-temperature nylon polymer of S2 into particles with specific particle size under nitrogen pressure without performing a second step operation. And solid phase polycondensation is carried out on the prepared particles according to requirements to further improve the polymerization degree.
Wherein the addition proportion of example 4 is identical to that of example 1, polyamide 6T66 is synthesized; wherein the addition proportion of example 5 is identical to that of example 2, and polyamide 6T6I is synthesized; the proportion of example 6 was the same as that of example 3, and polyamide 6T610 was synthesized.
Examples 7 to 9 (one-step method)
Examples 7 to 9 differ in that polyamide 5T56, 5T5I and polyamide 5T510 themselves have pentylene diamine in the synthesis and no additional pentylene diamine is added. The one-step procedure was as in examples 4-6.
Wherein, in example 7, the diacid is terephthalic acid and adipic acid; the diamine is only pentanediamine, wherein the addition ratio is as follows: the molar ratio of diamine to diacid is 1.03:1: in the addition ratio of the diacid, the molar ratio of the terephthalic acid to the adipic acid is 0.7:1; in the diamine addition ratio, polyamide 5T56 was synthesized.
In example 8, the diacids are terephthalic acid and isophthalic acid; the diamine is only pentanediamine, wherein the addition ratio is as follows: the molar ratio of diamine to diacid is 1.03:1: in the addition ratio of the diacid, the molar ratio of the terephthalic acid to the isophthalic acid is 0.7:1; in the diamine addition ratio, polyamide 5T5I was synthesized.
In example 9, the diacids are terephthalic acid and sebacic acid; the diamine is only pentanediamine, wherein the addition ratio is as follows: the molar ratio of diamine to diacid is 1.03:1: in the addition ratio of the diacid, the mol ratio of the terephthalic acid to the sebacic acid is 0.7:1; in the diamine addition ratio, polyamide 5T5I was synthesized.
Examples 1-9 are organized to give the following table.
TABLE 1 Table of the ingredients of the raw materials of the polyamides in examples 1 to 9
Comparative example
Comparative example 1
Comparative example 1 differs from example 1 in that the synthesis of the polyamide was carried out in a two-stage process and in that the anti-crosslinking agent pentamethylene diamine was not added.
Wherein the synthesis procedure of the polyamide is identical to the examples and is as follows,
S1, under the protection of inert gas, diacid and diamine are mixed according to the total mole ratio of 1:1.02 and a certain amount of water are added into an autoclave, and the mixture is stirred and reacted at the temperature of 100 ℃ to obtain a high-temperature nylon salt water solution system, wherein the PH value of the high-temperature nylon salt solution is 7.5, and the concentration of the high-temperature nylon salt solution is 50 percent. And adding all nylon salt solution into the reaction kettle.
S2, slowly boosting the nylon salt water solution system to 2.7Mpa in a certain time; when the pressure reaches 2.7Mpa, the air exhaust and pressure maintaining are started until the temperature reaches 240 ℃, and the air is sprayed under pressure.
S3, performing a second step of operation on the high-temperature nylon polymer of the S2, spraying polymer powder with lower molecular weight under pressure, and using equipment such as a rotary drum or a double screw to carry out tackifying, so that the molecular weight is increased and the standard viscosity is achieved. Finally, the mixture is granulated into particles with specific particle size under the pressure of nitrogen. And solid phase polycondensation is carried out on the prepared particles according to requirements to further improve the polymerization degree. The polyamide 6T66 was synthesized in comparative example 1.
Comparative examples 2 to 3
Comparative examples 2-3 differ from examples 2-3 in that the synthesis of the polyamide was carried out in a two-stage process and that the anti-crosslinking agent pentamethylene diamine was not added. Wherein the comparative example 2 is synthesized as polyamide 6T6I; comparative example 3 was synthesized as polyamide 6T610.
Comparative examples 4 to 6
Comparative examples 4 to 6 differ from comparative examples 1 to 3 in that the synthesis of polyamide was carried out in a one-step process and that the crosslinking inhibitor pentamethylene diamine was not added.
Specifically, comparative example 4 was synthesized as polyamide 6T66; comparative example 5 was synthesized as polyamide 6T6I; comparative example 6 was synthesized as polyamide 6T610.
The following tables are integrated according to the raw materials for polyamide synthesis in comparative examples 1 to 6.
TABLE 2 Table of the components of the polyamides in comparative examples 1 to 6
Performance test
In order to further study the performance parameters of the low crosslinked polyamide, the present application further developed the following experimental verification.
1. BHMT crosslinked product residual detection
After hydrolyzing the polymer with concentrated hydrochloric acid, the upper layer solution was extracted and analyzed for the content of crosslinked product using GC.
2. Tensile strength test
The determination is carried out according to the International organization for standardization ISO, according to the tensile strength of plastics in ISO 527.
3. Impact strength detection
The determination is made according to the International organization for standardization ISO, according to the impact strength properties of plastics in ISO 527.
4. Flexural Strength detection
The determination is made according to the international organization for standardization ISO, according to the flexural strength properties of plastics in ISO 178.
Conclusion analysis
The results of the detection and analysis according to the above properties are shown in the following table:
TABLE 3 detection of residues of crosslinked products of examples 1-9 and comparative examples 1-6BHMT
According to the analysis between examples 1-3 and examples 4-6, after the addition of pentamethylenediamine as an anti-crosslinking agent, the aliphatic polyamide prepared by the one-step method showed little residual variation in the BHMT crosslinked product compared with the aliphatic polyamide obtained by the two-step method. Further, after the anti-crosslinking agent is adopted, the operation of a two-step method can be reduced, the polyamide is directly prepared by the one-step method, and the resource loss can be reduced.
Next, as can be seen from the analyses of examples 4 to 6 and examples 7 to 9, when the same one-step method was used, since hexamethylenediamine was not added, the components of the diamine were all pentamethylenediamine, and thus the production of BHMT crosslinked product could not be detected.
As can be obtained from comparative examples 1 to 3 and comparative examples 1 to 3, when aliphatic polyamides are also produced by the two-step process, the purity of the aliphatic polyamides is improved since the two-step process eliminates BHMT crosslinked products.
And combining comparative examples 4-6, when the two-step method is not adopted to remove the BHMT cross-linked product, the BHMT cross-linked product obtained by detection is greatly increased; further, the side surface is reflected, after the pentylene diamine is added as the crosslinking inhibitor in the one-step method, the operation of the two-step method can be reduced, the polyamide is directly prepared by the one-step method, and the resource loss can be reduced.
TABLE 4 tensile Strength test tables for examples 1-9 and comparative examples 1-6
TABLE 5 impact Strength detection tables for examples 1 to 9 and comparative examples 1 to 6
TABLE 6 flexural Strength detection tables for examples 1 to 9 and comparative examples 1 to 6
According to the analysis between examples 1-3 and examples 4-6, after adding pentamethylenediamine as the crosslinking inhibitor, the mechanical properties of the obtained aliphatic polyamide are not greatly different by adopting the one-step operation, but the two-step operation can be reduced, the polyamide can be directly prepared by the one-step method, the resource loss can be reduced, and the polyamide can be synthesized by the high-efficiency synthesis method.
In comparison with examples 7 to 9, since hexamethylenediamine is not added, the diamine components are all pentanediamine, and the chain length in the diamine components affects the mechanical properties of the polyamide.
As compared with the analysis of comparative examples 1-3, the two-step method in the prior art can remove bis (hexamethylene) triamine (BHMT) and can improve the mechanical properties; in contrast to the one-step analysis of comparative examples 4-6, the mechanical properties of the polyamide are affected by the absence of the scavenging of bis (hexamethylene) triamine (BHMT). Further, the side analysis shows that the production of bis (hexamethylene) triamine (BHMT) can be reduced by only performing one-step operation after adding pentamethylene diamine as an anti-crosslinking agent.
Example 5 of the present application is the most preferred embodiment of the present application when the diacid is terephthalic acid and isophthalic acid; the diamines are hexamethylenediamine and pentamethylenediamine (wherein the pentamethylenediamine exists in the form of diamine as an anti-crosslinking agent) which can bring about better mechanical performance. In practical production applications, the mechanical properties of polyamides can be better represented than in the examples by specifically optimizing the proportions of pentamethylene diamine and hexamethylene diamine in the diamine, which is described in the present application only as a reference in the formulation.
It should be noted that the sequence of the embodiments of the present application is only for description, and does not represent the advantages and disadvantages of the embodiments. And the foregoing description has been directed to specific embodiments of this specification. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims can be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.
The foregoing description of the preferred embodiments of the application is not intended to limit the application to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the application are intended to be included within the scope of the application.
The specification and figures are merely exemplary illustrations of the present application and are considered to cover any and all modifications, variations, combinations, or equivalents that fall within the scope of the application. It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the scope of the application. Thus, the present application is intended to include such modifications and alterations insofar as they come within the scope of the application or the equivalents thereof.
Claims (10)
1. The low-crosslinking polyamide is characterized in that the polyamide is prepared by polycondensation of diamine and diacid serving as raw materials, and an anti-crosslinking agent under the action of a catalyst; the diacid comprises aromatic diacid monomers and aliphatic diacid monomers, and the diamine comprises only aliphatic diamine monomers; the anti-crosslinking agent is pentanediamine.
2. The low crosslinking polyamide of claim 1, wherein said aliphatic diamine monomer comprises one of hexamethylenediamine and pentamethylenediamine.
3. The low crosslinking polyamide of claim 1, wherein the aromatic diacid monomer comprises one of terephthalic acid and isophthalic acid.
4. The low crosslinking polyamide of claim 1, wherein the aliphatic diacid comprises adipic acid, sebacic acid.
5. The low crosslinking polyamide of claim 1, wherein the catalyst comprises at least one of sodium hypophosphite, hypophosphorous acid, phosphorous acid, hypophosphorous acid, phosphoric acid, calcium phosphate, or barium phosphate.
6. A process for the preparation of an oligocrosslinked polyamide according to any one of claims 1 to 5, characterized in that it comprises the following steps:
S1, under the protection of inert gas, adding diacid and diamine into an autoclave according to a total molar ratio and a certain amount of water, adding an anti-crosslinking agent and a catalyst, stirring at a certain temperature for reaction to obtain a polyamide salt water solution system, regulating the PH of the polyamide salt water solution, controlling the concentration of the polyamide salt water solution, and adding the polyamide salt water solution into the autoclave;
S2, slowly boosting the polyamide salt aqueous solution in the step S1 to a certain height in a reaction kettle, and then starting to exhaust and maintain pressure until reaching a certain temperature, and starting to reduce the pressure; when the pressure is reduced to a certain value, vacuumizing is started, and after the vacuum degree is maintained at a set value for a certain time, the polyamide polymer with a certain intrinsic viscosity is prepared;
S3, performing two-step operation on the polyamide polymer in the step S2, spraying polymer powder under the action of pressure, tackifying by equipment such as a rotary drum or a double screw, and the like, and granulating into particles with a specific particle size under the pressure of nitrogen when the polymer with the corresponding viscosity is measured.
7. The process for producing an oligocrosslinked polyamide according to claim 6, wherein in the step S3, the polyamide polymer in the step S2 is directly pelletized under nitrogen pressure into pellets of a specific particle diameter size.
8. The process for producing an oligocrosslinked polyamide according to claim 7, wherein, in the S1 reaction step, the diacid and the diamine are present in a total molar ratio of 1:1-1:1.2.
9. The process for producing an oligocrosslinked polyamide according to claim 6, wherein a diacid, a diamine and water are added to an autoclave, an anticrosslinker and a catalyst are added, and the reaction is carried out with stirring at a temperature of 50 to 150℃to obtain a polyamide aqueous solution system, the pH of the polyamide aqueous solution is adjusted to 6.5 to 9.5, the concentration of the polyamide aqueous solution is controlled to 30 to 70%, and the polyamide aqueous solution is added to the autoclave.
10. The process for producing an oligocrosslinked polyamide according to claim 9, wherein the aqueous polyamide solution is slowly pressurized up to 2-3Mpa in a reaction vessel, and the pressure is maintained by exhausting the gas until 280-320 ℃ and then the pressure is reduced; when the pressure is reduced to normal pressure, vacuumizing is started, and the vacuum degree is maintained at-0.08-0 Mpa for a certain time, so that the polyamide polymer with a certain intrinsic viscosity is prepared.
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