A polydodecanoic acid material, its preparation method and application

Abstract

This invention provides a polydodecanoic acid (PCA) material, its preparation method, and its applications. The PCA material comprises PCA resin, sulfur, and phosphorus; the sum of the mass contents of sulfur and phosphorus in the PCA material is 10-120 ppm. This invention controls the total mass content of sulfur and phosphorus within a specific range, resulting in a low monomer content and narrow molecular weight distribution in the PCA material. The PCA material exhibits excellent thermal stability and is particularly suitable for manufacturing automotive coolant piping.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a polydodecanoic acid material, its preparation method, and its application. Background Technology

[0002] Driven by the global "carbon neutrality" strategy and the green transformation of the automotive industry, automotive technology is rapidly developing towards lightweighting, low emissions, and long lifespan. In recent years, with the booming development of the new energy vehicle market, the demand for automotive piping has continued to climb, and it is estimated that by 2026, its annual consumption will reach 50,000 tons, continuing to grow at a compound annual growth rate of 4% to 5.5%. Currently, high-end automotive piping commonly uses long-chain polyamide materials (such as PA11 and PA12), which dominate the market due to their excellent performance in flexibility, heat resistance, hydrolysis resistance, and resistance to ethylene glycol coolant corrosion.

[0003] PA12 is typically prepared using a hydrolytic polymerization process of lactam monomers. This involves using water as a ring-opening agent, under high temperature and pressure conditions to open the lactam ring and generate oligomers with a certain degree of polymerization. Further polymerization is then carried out under normal pressure or vacuum to increase the molecular weight, resulting in long-chain polylactams. Because the ring-opening reaction of dodecalactam is quite difficult, a catalyst is usually added to shorten the reaction time. For example, US5519097A discloses a continuous hydrolytic polymerization process for dodecalactam using a continuous tubular reactor, with 60 ppm hypophosphoric acid as a catalyst, which yields polydodecalactams with higher molecular weights. Currently, the PA12 market is dominated by products manufactured by Evonik Industries (Germany) and E.M. (Switzerland), which generally suffer from wide molecular weight distribution, high monomer residue (>0.3 wt%), and poor thermal stability, failing to meet the requirements of new energy vehicles. Therefore, there is an urgent need in this field to develop long-chain polylactams with low monomer residue, narrow molecular weight distribution, and good thermal stability to meet the performance requirements of new energy vehicle pipelines. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a polydodecanoic acid material, its preparation method, and its application. The polydodecanoic acid material contains specific amounts of sulfur and phosphorus elements, has a low content of dodecanoic acid monomers, a narrow molecular weight distribution, and excellent thermal stability, which can fully meet the performance requirements of coolant piping systems in new energy vehicles.

[0005] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a polydodecanoic acid material, the polydodecanoic acid material comprising polydodecanoic acid resin, sulfur and phosphorus; wherein the mass content of sulfur in the polydodecanoic acid material is ≥5 ppm, the mass content of phosphorus is ≥5 ppm, and the sum of the mass contents of sulfur and phosphorus is 10-120 ppm.

[0006] The polydodecanoic acid material provided by this invention contains sulfur and phosphorus elements naturally present in the polydodecanoic acid material itself, independent of additives. The total mass content of sulfur and phosphorus elements is controlled within a specific range, resulting in a low content and narrow molecular weight distribution of dodecanoic acid monomers. The polydodecanoic acid material exhibits good thermal stability and is particularly suitable for manufacturing automotive coolant piping.

[0007] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0008] The total mass content of sulfur and phosphorus in the polydodecanoic acid material is 10-120 ppm, for example, it can be 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm, 100 ppm or 110 ppm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but preferably 20-100 ppm.

[0009] In this invention, "ppm" represents parts per million, and 1 ppm represents one part per million.

[0010] In this invention, the hypothetical mechanisms of action of sulfur and phosphorus are as follows: the presence of phosphorus promotes the ring-opening of dodecyl lactam but inhibits further polymerization of the ring-opening product; sulfur promotes further polymerization of the ring-opening product but also promotes the re-engagement of chain ends to form dodecyl lactam. This invention, by designing the total amount of phosphorus and sulfur within a specific range, can control the molecular weight distribution and monomer residue of polydodecyl lactam, obtaining polydodecyl lactam materials with low dodecyl lactam content and narrow molecular weight distribution, while simultaneously improving thermal stability. The applicant found that if the content of sulfur and phosphorus is too low, it leads to an increase in the content of monomers and low molecular weight substances in the polydodecyl lactam material, resulting in a wide molecular weight distribution, which also affects the thermal stability of polydodecyl lactam, causing a significant increase in the conductivity of the coolant upon contact. If the content of sulfur and phosphorus is too high, in addition to affecting the monomer content and molecular weight distribution, it also leads to a decrease in the thermal stability of the polydodecyl lactam material.

[0011] The applicant discovered that, in this invention, the presence of phosphorus and sulfur elements in limited quantities enables the polydodecanoic acid material to maintain the coolant's low conductivity even after prolonged contact with the coolant. This is presumably due to the reduced content and fraction of low-molecular-weight substances, thus preventing the precipitation of low-molecular-weight fractions and residual monomers during prolonged contact with the coolant. This further solves the technical problem of traditional polydodecanoic acid materials where low-molecular-weight substances and residual monomers inevitably enter the coolant, contaminating the coolant medium and causing a significant increase in coolant conductivity, decreased electrical insulation, and resulting safety risks. Therefore, the polydodecanoic acid material described in this invention is particularly suitable for manufacturing automotive coolant piping.

[0012] It should be noted that the sulfur and phosphorus elements are derived from the polydodecanoic acid material itself obtained by the polymerization of dodecanoic acid, and are naturally present in the polydodecanoic acid material itself, independent of additives. That is, the sulfur and phosphorus elements do not depend on additives selected by those skilled in the art based on various practical performance requirements.

[0013] In this invention, the mass content of sulfur in the polydodecanoic acid material itself, which does not depend on additives, is ≥5 ppm. As a preferred technical solution of this invention, the mass content of sulfur in the polydodecanoic acid material is 5-90 ppm, for example, it can be 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, 35 ppm, 40 ppm, 45 ppm, 50 ppm, 55 ppm, 60 ppm, 65 ppm, 70 ppm, 75 ppm, 80 ppm or 85 ppm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range, but preferably 10-60 ppm.

[0014] The phosphorus element is derived from the polydodecanoic acid material obtained by polymerizing dodecanoic acid itself, meaning that the phosphorus element does not depend on additives. In this invention, the phosphorus element content of the polydodecanoic acid material itself, which does not depend on additives, is ≥5 ppm by mass. As a preferred technical solution of this invention, the phosphorus element content in the polydodecanoic acid material is 5-100 ppm by mass, for example, it can be 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm or 95 ppm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range, but preferably 10-50 ppm.

[0015] In this invention, the mass content of sulfur and phosphorus can be obtained by the following method: the polydodecyl lactam material is digested to obtain a sample, and the sample is tested by inductively coupled plasma atomic emission spectrometry (ICP-OES) to obtain the mass content of sulfur and phosphorus respectively.

[0016] For example, the sample preparation method includes: weighing 0.2 g of polydodecanoic acid material, adding 7 mL of nitric acid, digesting in a high-pressure vessel at 200°C for 2.5 h, then cooling, filtering, and adding pure water to make up to 50 mL to obtain the sample.

[0017] Preferably, the mass ratio of phosphorus to sulfur in the polydodecanoic acid material is (0.05-12):1, for example, it can be 0.08:1, 0.1:1, 0.2:1, 0.5:1, 0.8:1, 1:1, 1.5:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1 or 11:1, etc., further preferably (0.5-2):1, more preferably (0.6-1.6):1.

[0018] As a preferred embodiment of the present invention, the sulfur element in the polydodecanoic acid material is derived from sulfur-containing substances, which include any one or a combination of at least two of elemental sulfur, sulfur oxides, sulfur-containing acids, and sulfur-containing acid salts.

[0019] Preferably, the sulfur oxides include sulfur dioxide and / or sulfur trioxide.

[0020] Preferably, the sulfur-containing acid includes sulfuric acid and / or sulfonic acid.

[0021] For example, the sulfonic acid includes benzenesulfonic acid and / or benzenedisulfonic acid.

[0022] Preferably, the sulfur-containing acid salt includes alkali metal sulfates and / or alkali metal sulfonates.

[0023] For example, the alkali metal sulfate includes sodium sulfate and / or potassium sulfate.

[0024] As a preferred embodiment of the present invention, the phosphorus element in the polydodecanoic acid material is derived from phosphorus-containing substances, which include any one or a combination of at least two of phosphorus oxides, phosphorus-containing acids, phosphorus-containing salts, and phosphorus-containing esters.

[0025] Preferably, the phosphorus oxide includes phosphorus pentoxide and / or phosphorus trioxide.

[0026] Preferably, the phosphorus-containing acid includes phosphoric acid and / or phosphorous acid.

[0027] Preferably, the phosphorus-containing acid salt includes any one or a combination of at least two of alkali metal phosphates, alkali metal acid phosphates, and alkali metal phosphites.

[0028] For example, the phosphorus-containing acid salt includes any one or a combination of at least two of potassium phosphate, potassium dihydrogen phosphate, potassium monohydrogen phosphate, and potassium phosphite.

[0029] Preferably, the phosphorus-containing ester includes any one or a combination of at least two of triphenyl phosphate, trimethyl phosphate, triethyl phosphate, and tributyl phosphate.

[0030] As a preferred embodiment of the present invention, the polydodecanoic acid material uses a dicarboxylic acid as a molecular weight regulator.

[0031] Preferably, the dicarboxylic acid is an aliphatic dicarboxylic acid, including C4-C14 aliphatic dicarboxylic acids, such as C4, C5, C6, C8, C10, C12, C13, etc., preferably C6-C14 aliphatic dicarboxylic acids, and more preferably any one or a combination of at least two of 1,6-adipic acid, 1,10-sebaceous acid, and 1,12-dodecyl diacid.

[0032] Preferably, it is any one or a combination of at least two of 1,6-adipic acid, 1,10-sebacic acid, and 1,12-dodecyl dicolic acid.

[0033] As a preferred embodiment of the present invention, the polydodecanoic acid material contains 0.08-0.22% dodecanoic acid by mass.

[0034] In this invention, the mass content of dodecyl lactam in the polydodecanamide material can be obtained by gas chromatography. Specifically, the polydodecanamide material is dissolved in a mixed solvent of trifluoroethanol / chloroform (trifluoroethanol:chloroform = 3:2) and subjected to gas chromatography. The content is then calculated based on the dodecyl lactam standard curve.

[0035] As a preferred embodiment of the present invention, the molecular weight distribution of the polydodecanoic acid material is ≤2.6, for example, it can be 1.8, 1.85, 1.9, 1.95, 2, 2.05, 2.1, 2.15, 2.2, 2.25, 2.3, 2.35, 2.4, 2.45, 2.5, 2.55 or 2.58, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but preferably 1.85-2.55.

[0036] In this invention, the molecular weight distribution (PDI) is the weight-average molecular weight. M w Number-average molecular weight Mn Weight-average molecular weight M w Number-average molecular weight M n The test was performed using gel permeation chromatography (GPC) with hexafluoroisopropanol as the mobile phase.

[0037] As a preferred embodiment of the present invention, the relative viscosity of the polydodecanoic acid material is 2-2.8, for example, it can be 2.05, 2.1, 2.15, 2.2, 2.25, 2.3, 2.35, 2.4, 2.45, 2.5, 2.55, 2.6, 2.65, 2.7 or 2.75, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0038] In this invention, the relative viscosity is measured using the method described in standard GB / T 12006.1-2009, in 98% concentrated sulfuric acid at 25±0.01℃, for a polydodecanoic acid material with a concentration of 1 g / dL. r .

[0039] As a preferred embodiment of the present invention, the 5% thermal decomposition temperature of the polydodecanoic acid material is ≥422°C, for example, it can be 425°C, 428°C, 430°C, 432°C, 435°C, 438°C, 440°C, 442°C or 445°C, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but 426-440°C is preferred.

[0040] In this invention, the 5% thermal decomposition temperature is obtained by thermogravimetric analysis (TGA). Under a nitrogen atmosphere, the temperature is raised from 50°C to 600°C at a rate of 10°C / min. The temperature at which the sample loses 5% of its weight is the 5% thermal decomposition temperature.

[0041] In a second aspect, the present invention provides a method for preparing a polydodecanoic acid material as described in the first aspect, the method comprising: The polydodecanoic acid material was obtained by ring-opening polymerization using dodecanoic acid, diacid, phosphorus-containing substances and sulfur-containing substances as raw materials. Based on the mass of the dodecanoic acid as 100%, the total mass of the phosphorus-containing and sulfur-containing substances is 0.01-0.1%.

[0042] In this invention, dodecyl lactam is used as a monomer, a diacid is used as a molecular weight regulator, and phosphorus-containing and sulfur-containing substances are used as catalysts to prepare polydodecyl lactam materials through ring-opening polymerization. Among them, the phosphorus-containing substances can promote the ring-opening of dodecyl lactam, and the sulfur-containing substances can promote the further polymerization of the ring-opening products. The two substances synergistically regulate the ring-opening polymerization reaction to obtain the polydodecyl lactam material with low monomer content, narrow molecular weight distribution, and excellent thermal stability.

[0043] In this invention, based on the mass of the dodecanoic acid as 100%, the total mass of the phosphorus-containing and sulfur-containing substances is 0.01-0.1%, for example, it can be 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, or 0.09%, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range.

[0044] As a preferred embodiment of the present invention, with the molar amount of the dodecanoic acid as 100%, the molar amount of the dicarboxylic acid is 0.005-1%, for example, it can be 0.01%, 0.02%, 0.05%, 0.08%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 0.95%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range, but preferably 0.01-0.2%.

[0045] As a preferred embodiment of the present invention, based on the total mass of the dodecanoic acid and the dicarboxylic acid as 100%, the mass of the phosphorus-containing substance is 0.005-0.5%, for example, it can be 0.01%, 0.02%, 0.04%, 0.05%, 0.06%, 0.08%, 0.1%, 0.2%, 0.3%, 0.4% or 0.45%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0046] As a preferred embodiment of the present invention, based on the total mass of the dodecyl lactam and dicarboxylic acid as 100%, the mass of the sulfur-containing substance is 0.005-0.5%, for example, it can be 0.01%, 0.02%, 0.04%, 0.05%, 0.06%, 0.08%, 0.1%, 0.2%, 0.3%, 0.4% or 0.45%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0047] It should be noted that in the polydodecanoic acid material of this invention, the phosphorus element comes from the phosphorus-containing substance during preparation. Since the ring-opening polymerization reaction of this invention is preferably carried out in the presence of water, the diacid, as a molecular weight regulator, also produces a small amount of water during the reaction. Water is drained during the reaction. Different phosphorus-containing substances have different binding forces with water, and a small amount of phosphorus-containing substances or their derivatives are discharged during the drainage process. Therefore, the phosphorus content in the products obtained from different phosphorus-containing substances under the same / similar formulations and processes will have certain differences. The phosphorus content in the products obtained from the same phosphorus-containing substance under different formulations and processes will also have certain differences. That is, the phosphorus content in the polydodecanoic acid material is affected by the type and amount of phosphorus-containing substance, the type and amount of diacid, the amount of water, and the process parameters. Furthermore, considering that the phosphorus content may be affected by contamination of raw materials during production, storage, and transportation, as well as contamination of the production equipment during the polymerization reaction, the theoretical phosphorus content and the actual detected phosphorus content will also differ to some extent. In this invention, the mass content of phosphorus in the polydodecanoic acid material refers to the actual detected phosphorus content in the polydodecanoic acid material.

[0048] Similarly, sulfur originates from sulfur-containing substances during preparation. Different sulfur-containing substances have varying binding forces with water, and a small amount of sulfur-containing substances or their derivatives will be discharged during drainage. Therefore, the sulfur content in products obtained from different sulfur-containing substances under the same / similar formulations and processes will vary, and the sulfur content in products obtained from the same sulfur-containing substance under different formulations and processes will also vary. That is, the sulfur content in polydodecanoic acid materials is affected by the type and amount of sulfur-containing substances, the type and amount of diacid, the amount of water, and process parameters. Furthermore, considering that the sulfur content may be affected by contamination of raw materials during production, storage, and transportation, as well as contamination of the production equipment during the polymerization reaction, the theoretical sulfur content and the actual detected sulfur content will also differ to some extent. In this invention, the mass content of sulfur in the polydodecanoic acid material refers to the actual detected sulfur content in the polydodecanoic acid material.

[0049] As a preferred embodiment of the present invention, the raw materials further include antioxidants.

[0050] As a preferred embodiment of the present invention, the antioxidant includes any one or a combination of at least two of the following: hindered amine antioxidants, hindered phenolic antioxidants, phosphite antioxidants, thioester antioxidants, and phosphite antioxidants.

[0051] Preferably, the antioxidant includes N,N'-Bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine (antioxidant 1098), pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (antioxidant 1010), octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076), tris(2,4-di-tert-butylphenyl)phosphite (antioxidant 168), and antioxidant H10, or a combination of at least two of these.

[0052] As a preferred embodiment of the present invention, based on the total mass of the raw materials as 100%, the mass of the antioxidant is 0.01-0.2%, for example, it can be 0.02%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15% or 0.18%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0053] In this invention, "total mass of raw materials" refers to the total mass of dodecyl lactam, dicarboxylic acid, phosphorus-containing substances, sulfur-containing substances, and antioxidants (if any), that is, the total mass of all non-aqueous raw materials.

[0054] As a preferred embodiment of the present invention, the ring-opening polymerization reaction is carried out in the presence of water.

[0055] As a preferred embodiment of the present invention, with the total mass of the reaction system being 100%, the mass of the water is 5-40%, for example, it can be 6%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, or 38%, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0056] In this invention, "total mass of the reaction system" refers to the total mass of dodecyl lactam, dicarboxylic acid, phosphorus-containing and sulfur-containing substances, water, and antioxidants (if any).

[0057] As a preferred embodiment of the present invention, the preparation method includes the following steps: Dodecyl lactam, diacid, phosphorus-containing substances, sulfur-containing substances, water, and optionally antioxidants are added to a reaction apparatus for a first-stage polymerization reaction. Then, water is drained and the temperature is lowered, followed by a second-stage polymerization reaction under vacuum conditions to obtain the polydodecyl lactam material.

[0058] Preferably, the first polymerization reaction is carried out in a protective atmosphere.

[0059] Preferably, the protective atmosphere includes any one or a combination of at least two of nitrogen, argon, and helium atmospheres.

[0060] As a preferred embodiment of the present invention, the temperature of the first polymerization reaction is 270-290℃, for example, it can be 272℃, 275℃, 278℃, 280℃, 282℃, 285℃ or 288℃, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0061] Preferably, the time taken to raise the temperature to the temperature of the first polymerization reaction is 0.5-3 h, for example, it can be 0.8 h, 1 h, 1.2 h, 1.5 h, 1.6 h, 1.8 h, 2 h, 2.2 h, 2.5 h or 2.8 h, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0062] As a preferred embodiment of the present invention, the time of the first polymerization reaction is 3-6 h, for example, it can be 3.2 h, 3.5 h, 3.8 h, 4 h, 4.2 h, 4.5 h, 4.8 h, 5 h, 5.2 h, 5.5 h or 5.8 h, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0063] As a preferred embodiment of the present invention, the temperature of the second polymerization reaction is 260-270°C, for example, it can be 261°C, 262°C, 263°C, 264°C, 265°C, 266°C, 267°C, 268°C or 269°C, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0064] As a preferred embodiment of the present invention, the time of the second polymerization reaction is 1-3 h, for example, it can be 1.2 h, 1.5 h, 1.8 h, 2 h, 2.2 h, 2.4 h, 2.5 h, 2.6 h or 2.8 h, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0065] As a preferred embodiment of the present invention, the preparation method includes: adding dodecyl lactam, diacid, phosphorus-containing substances, sulfur-containing substances, water, and optionally an antioxidant into a reaction apparatus; heating to 270-290°C within 0.5-3 h and holding the temperature for 3-6 h under a protective atmosphere and stirring conditions; then draining water and cooling to 260-270°C under stirring conditions; evacuating the vacuum at this temperature and holding the temperature at 260-270°C for 1-3 h to obtain the polydodecyl lactam material.

[0066] Thirdly, the present invention provides the application of a polydodecanoic acid material as described in the first aspect or a polydodecanoic acid material prepared by the preparation method described in the second aspect in automotive pipelines, electronic appliances or energy storage devices.

[0067] Preferably, the automotive piping includes automotive coolant piping.

[0068] Fourthly, the present invention provides a coolant piping material, the coolant piping material comprising the polydodecanoic acid material as described in the first aspect or the polydodecanoic acid material prepared by the preparation method described in the second aspect.

[0069] Compared with the prior art, the present invention has at least the following beneficial effects: The polydodecanoic acid material provided by this invention controls the total mass content of sulfur and phosphorus within a specific range, resulting in a low content of dodecanoic acid monomers and a narrow molecular weight distribution. This polydodecanoic acid material exhibits excellent thermal stability and is particularly suitable for manufacturing automotive coolant piping. Detailed Implementation

[0070] To facilitate understanding of the present invention, specific embodiments are provided to further illustrate the technical solution of the present invention. Those skilled in the art should understand that the embodiments are merely illustrative of the present invention and should not be considered as specific limitations thereof.

[0071] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not limited to those elements and may also include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0072] In the following specific embodiments, the testing methods for the parameters of polydodecanoic acid material are as follows: (1) Relative viscosity The relative viscosity η of a 1 g / dL polydodecanoic acid material was tested in 98% concentrated sulfuric acid at 25 ± 0.01℃ using the method described in standard GB / T 12006.1-2009. r .

[0073] (2) Content of sulfur and phosphorus elements Weigh 0.2 g of polydodecyl lactam material, add 7 mL of nitric acid, and digest in a high-pressure vessel at 200℃ for 2.5 h. After the digestion process is completed, cool, filter, and add pure water to make up to 50 mL to obtain the test sample. The test sample is tested using an inductively coupled plasma atomic emission spectrometer (ICP-OES) to obtain the contents of sulfur and phosphorus elements.

[0074] (3) Content of dodecanoic acid 5 mg of polydodecanoic acid material was dissolved in a mixed solvent of trifluoroethanol / chloroform (trifluoroethanol:chloroform = 3:2, volume ratio), and the volume was adjusted to 10 mL. Then, 1 μL of the liquid was taken for gas chromatography analysis. The content of dodecanoic acid was calculated based on the dodecanoic acid standard curve.

[0075] (4) Molecular weight distribution PDI The weight-average molecular weight was determined by gel permeation chromatography (GPC) with hexafluoroisopropanol as the mobile phase and a sample concentration of 1 mg / mL. M w Number-average molecular weight M n PDI= M w / M n .

[0076] (5) 5% thermal decomposition temperature T d -5% The test was conducted using a TGA 550 thermal analyzer from the USA. Under a nitrogen atmosphere, the temperature was raised from 50℃ to 600℃ at a heating rate of 10℃ / min, and the nitrogen purging rate was 60 mL / min. The temperature at which the sample lost 5% of its weight was recorded as T. d -5%.

[0077] (6) Coolant conductivity after contact The test was conducted using electric vehicle coolant (Huaqing Deep Blue HQ-EV3, freezing point -40℃, Hefei Huaqing High-Tech Surface Technology Co., Ltd.); Polydodecanoic acid material was made into a square plate with a thickness of 1 mm. 50 g of the square plate was placed in 1 kg of coolant and immersed at 80°C for 1064 h. The coolant was then cooled to 25°C and its conductivity was tested using a conductivity meter (Lei Ci, DDSJ-307A).

[0078] In the following specific embodiments of the present invention, the materials for which no preparation method is provided are all commercially available chemicals, and the specific information is as follows: The following will use several examples to describe in detail the polydodecanoic acid material and its preparation method according to the present invention, but the polydodecanoic acid material and its preparation method are not limited to these examples.

[0079] Examples 1-11, Comparative Examples 1-6 A polydodecanoic acid material is prepared by the following method: Dodecyl lactam, diacid, phosphorus-containing substances, sulfur-containing substances, and deionized water were added to a pressure vessel equipped with a magnetically coupled stirrer, condenser, gas inlet, feed inlet, and pressure explosion-proof port according to the proportions shown in Tables 1 and 2. Optional antioxidant 1098 was then added, with the mass of antioxidant 1098 being 0.1% of the total mass of the raw materials (excluding water), and the mass of deionized water being 30% of the total mass of the system. After evacuation, high-purity nitrogen was introduced as a protective gas. The temperature was raised to 280°C within 2 hours under stirring and maintained for 4 hours. Then, water was drained under stirring, and the temperature of the reactants was lowered to 270°C. Vacuum was then applied, and the reaction was maintained at 270°C. After the reaction was completed, the material was discharged to obtain the polydodecyl lactam material, the specific data of which are shown in Tables 1 and 2.

[0080] In the preparation methods of Examples 1-11 and Comparative Examples 2-6, the isothermal reaction time at 270°C was 2 h. In Comparative Example 1, no phosphorus or sulfur-containing substances were added, and the isothermal reaction time at 270°C was extended to 3 h, resulting in a polydodecanoic acid material with a relative viscosity of 2.15.

[0081] In Tables 1 and 2, the amounts of phosphorus-containing and sulfur-containing substances are expressed as mass content (%), that is, the relative mass of phosphorus-containing and sulfur-containing substances based on the total mass of dodecyl lactam and dicarboxylic acid as 100%.

[0082] Table 1 Table 2 As can be seen from the examples in Tables 1 and 2, the polydodecanoic acid material provided by the present invention, by controlling the mass content of sulfur and phosphorus elements within a specific range, results in a low content of dodecanoic acid monomers, a narrow molecular weight distribution, PDI≤2.5, good thermal stability, and a 5% thermal decomposition temperature≥426℃. After contact with coolant, it has a very low impact on the conductivity of coolant. Even after long-term high-temperature (80℃, 1064 h) contact, the conductivity of coolant is still <250 μS / cm, which meets the performance requirements for electric vehicle coolant in the new national standard GB / T29743.2-2025.

[0083] The polydodecanoic acid material in Comparative Example 1 lacks sulfur and phosphorus elements, resulting in a high residual amount of dodecanoic acid monomers, a wide molecular weight distribution, and a significant amount of low molecular weight substances. Since the coolant contains ethylene glycol, the residual dodecanoic acid monomers easily enter the coolant. Low molecular weight substances also have good solubility in the coolant. The entry of residual monomers and low molecular weight substances into the coolant leads to a substantial increase in the coolant's conductivity.

[0084] In Comparative Example 2, the total content of sulfur and phosphorus in the polydodecanoic acid material was >120 ppm, the monomer residue was high, the 5% thermal decomposition temperature was reduced, resulting in an increase in the conductivity of the coolant.

[0085] Comparative Examples 3 and 4 contain one of sulfur and phosphorus elements, respectively, resulting in a high monomer content, wide molecular weight distribution, and reduced thermal stability in the polydodecanoic acid material. When in contact with the coolant, the conductivity of the coolant increases significantly.

[0086] In Comparative Example 5, the total content of sulfur and phosphorus was too low, while the content of dodecyl lactam monomer was high. In Comparative Example 6, the residual amount of dodecyl lactam monomer was large, which led to a significant impact on the conductivity of the coolant after the material came into contact with the coolant.

[0087] The present invention has been illustrated through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A polydodecanoic acid material, characterized in that, The polydodecanoic acid material includes polydodecanoic acid resin, sulfur, and phosphorus. The polydodecanoic acid material contains sulfur at a mass content of ≥5 ppm and phosphorus at a mass content of ≥5 ppm, and the sum of the mass contents of sulfur and phosphorus is 10-120 ppm.

2. The polydodecanoic acid material according to claim 1, characterized in that, The sulfur content in the polydodecanoic acid material is 5-90 ppm, preferably 10-60 ppm.

3. The polydodecanoic acid material according to claim 1, characterized in that, The phosphorus content in the polydodecanoic acid material is 5-100 ppm, preferably 10-50 ppm; Preferably, the polydodecanoic acid material contains 0.08-0.22% dodecanoic acid by mass.

4. The polydodecanoic acid material according to claim 1, characterized in that, The sulfur element in the polydodecanoic acid material is derived from sulfur-containing substances, which include any one or a combination of at least two of elemental sulfur, sulfur oxides, sulfur-containing acids, and sulfur-containing acid salts. Preferably, the sulfur oxides include sulfur dioxide and / or sulfur trioxide; Preferably, the sulfur-containing acid includes sulfuric acid and / or sulfonic acid; Preferably, the sulfur-containing acid salt includes alkali metal sulfates and / or alkali metal sulfonates; Preferably, the phosphorus element in the polydodecanoic acid material is derived from a phosphorus-containing substance, which includes any one or a combination of at least two of phosphorus oxides, phosphorus-containing acids, phosphorus-containing salts, and phosphorus-containing esters. Preferably, the phosphorus oxide includes phosphorus pentoxide and / or phosphorus trioxide; Preferably, the phosphorus-containing acid includes phosphoric acid and / or phosphorous acid; Preferably, the phosphorus-containing acid salt includes any one or a combination of at least two of alkali metal phosphates, alkali metal acid phosphates, and alkali metal phosphites; Preferably, the phosphorus-containing ester includes any one or a combination of at least two of triphenyl phosphate, trimethyl phosphate, triethyl phosphate, and tributyl phosphate; Preferably, the polydodecanoic acid material uses a diacid as a molecular weight regulator. Preferably, the dicarboxylic acid includes C4-C14 aliphatic dicarboxylic acids, and more preferably any one or a combination of at least two of 1,6-adipic acid, 1,10-sebaceous acid, and 1,12-dodecyl diacid.

5. The polydodecanoic acid material according to claim 1, characterized in that, The molecular weight distribution of the polydodecanoic acid material is ≤2.6, preferably 1.85-2.55; And / or, the relative viscosity of the polydodecanoic acid material is 2-2.8; And / or, the 5% thermal decomposition temperature of the polydodecanoic acid material is ≥422°C.

6. A method for preparing a polydodecanoic acid material as described in any one of claims 1-5, characterized in that, The preparation method includes: The polydodecanoic acid material was obtained by ring-opening polymerization using dodecanoic acid, diacid, phosphorus-containing substances and sulfur-containing substances as raw materials. Based on the mass of the dodecanoic acid as 100%, the total mass of the phosphorus-containing and sulfur-containing substances is 0.01-0.1%.

7. The preparation method according to claim 6, characterized in that, With the dodecanoic acid comprising 100% molar amount, the dicarboxylic acid comprises 0.005-1% molar amount. And / or, based on the total mass of the dodecanoic acid and the dicarboxylic acid being 100%, the mass of the phosphorus-containing substance is 0.005-0.5%; And / or, based on the total mass of the dodecanoic acid and the dicarboxylic acid being 100%, the mass of the sulfur-containing substance is 0.005-0.5%.

8. The preparation method according to claim 6, characterized in that, The raw materials also include antioxidants; Preferably, the antioxidant includes any one or a combination of at least two of the following: hindered amine antioxidants, hindered phenolic antioxidants, phosphite antioxidants, thioester antioxidants, and phosphite antioxidants. Preferably, the antioxidant comprises 0.01-0.2% of the total mass of the raw materials (100%). Preferably, the ring-opening polymerization reaction is carried out in the presence of water; Preferably, the water comprises 5-40% of the total mass of the reaction system, which is 100% of the total mass. Preferably, the preparation method includes the following steps: Dodecyl lactam, diacid, phosphorus-containing substances, sulfur-containing substances, water, and optionally antioxidants are added to a reaction apparatus to carry out a first-stage polymerization reaction, followed by drainage and cooling, and then a second-stage polymerization reaction is carried out under vacuum conditions to obtain the polydodecyl lactam material. Preferably, the temperature of the first polymerization reaction is 270-290℃; Preferably, the polymerization reaction time for the first stage is 3-6 hours; Preferably, the temperature of the second polymerization reaction is 260-270℃; Preferably, the second polymerization reaction takes 1-3 hours.

9. The application of a polydodecanoic acid material as described in any one of claims 1-5 or a polydodecanoic acid material prepared by the preparation method as described in any one of claims 6-8 in automotive piping, electronic devices or energy storage devices.

10. A coolant piping material, characterized in that, The coolant piping material includes the polydodecanoic acid material as described in any one of claims 1-5 or the polydodecanoic acid material prepared by the preparation method described in any one of claims 6-8.

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