Long carbon chain polyamide material and method for producing the same

Abstract

The application discloses a long carbon chain polyamide material and a preparation method thereof. The long carbon chain polyamide material comprises the following components in mass fraction: 75.7-97.6 wt% of long carbon chain polyamide, 0.1-1.1 wt% of polycarbon lactam, 2-20 wt% of graft toughening agent, 0.2-1.2 wt% of antioxidant and 0-2 wt% of other processing aids. The long carbon chain polyamide can catalyze the ring-opening polymerization of polycarbon lactam under alkaline conditions during high-temperature processing, reduces the content of small molecular oligomers, obviously improves the precipitation resistance, has good continuous processing performance, and can be applied to air brake pipelines, cooling pipelines, fuel pipelines, oil and gas pipelines and lubricating oil pipelines and the like.

Description

Technical Field

[0001] This invention belongs to the field of polymer material synthesis and processing technology, and relates to a long carbon chain polyamide material with low processing precipitation and its preparation method. Background Technology

[0002] Polyamide materials occupy a crucial position in numerous industrial fields due to their excellent mechanical properties, good chemical corrosion resistance, and superior wear resistance. Long-chain polyamides, such as PA11 and PA12, are widely used in pipeline systems for transporting water, gas, chemical solvents, and fuels due to their unique advantages such as excellent weather resistance, oil resistance, and high flexibility at low temperatures. Especially in the automotive and energy storage fields, long-chain nylon tubing has become the mainstream application in the market and is continuously increasing in volume.

[0003] However, with the continuous expansion of applications and increasingly stringent usage conditions, long-chain polyamide pipes also face some challenges and problems. Most notably, during continuous processing or use, small molecules such as prepolymers and additives in the amorphous regions of the polyamide material precipitate out over time, leading to a decrease in product yield during processing or causing serious consequences such as blockage and contamination during use, thus limiting the further development of long-chain polyamide pipes.

[0004] To address the issue of long-chain polyamide pipelines prone to precipitation, current technologies primarily focus on modifying the pipeline component structure. For example, patent CN 208503672 U discloses a multi-layer automotive fuel delivery pipeline structure, where the long-chain polyamide layer and inner component are bonded together with a barrier material to reduce the precipitation of long-chain polyamide during long-term use. However, this method cannot address the problem of low molding yield caused by the precipitation of the outermost layer of long-chain polyamide on the mold during processing. Patent CN 207609882 U discloses a six-layer long-chain polyamide pipeline material, using TPE material as a protective layer in the innermost layer of the pipeline. The barrier and wear-resistant properties of TPE material ensure that the precipitation of long-chain nylon does not contaminate the delivery medium. However, this method also fails to solve the processing and outer wall precipitation problems of long-chain nylon. Patent CN 116410586 A discloses a polyamide material resistant to precipitation. By optimizing the selection of plasticizers, it partially solves the problem of liquid precipitation during long-term use, but does not improve the precipitation of low molecular weight solids during processing.

[0005] Therefore, how to develop a material that effectively improves the precipitation of long-chain polyamide during long-term processing, so that the pipelines made from it can meet the requirements of mass production and long-term transport of media such as pneumatic braking pipelines and cooling pipelines, has become an urgent problem to be solved in the industry. Summary of the Invention

[0006] The present invention addresses the shortcomings of the prior art by providing a long-chain polyamide material with improved processing and precipitation, and its preparation method. During long-term extrusion processing, the material exhibits low precipitation of small molecules in the extruder mandrel, sizing sleeve, and inner wall of the corrugated module. Pipelines made with this material show low precipitation and migration of small molecules during long-term transportation of media such as ethylene glycol, gasoline, and diesel.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a long-chain polyamide material comprising the following components by mass fraction:

[0009]

[0010] In this invention, the long carbon chain polyamide is a polyamide with an average number of carbon atoms in the main chain ≥ 8, and can be PA610, PA612, PA10, PA12, PA11, PA12, PA1212, etc.

[0011] Compared to short-chain polyamides, long-chain polyamides often employ uncapped or low-capped processes during the polymerization termination stage. Their small molecules have higher reactivity, which is beneficial for reacting with multi-carbon lactams under high-temperature and high-shear conditions, thereby reducing the content of monomers and prepolymers and effectively reducing precipitation.

[0012] Preferably, the long-chain polyamide has an Ubbelohde viscosity between 1.8 and 2.5, and a melt flow index (MVR) between 3 and 12 g / 10 min at 235°C and 2.16 kg.

[0013] Preferably, the end groups of the long-chain polyamide are amino and carboxyl groups, which can undergo polycondensation reactions with carboxyl and amino groups, respectively.

[0014] In this invention, the mass fraction of the polycarbolactam can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.8%, etc., preferably 0.1%-0.5%.

[0015] Preferably, the polycarbon lactam has ≥10 carbon atoms and can be one or more of decacarbon lactam, undecanolactam, and dodecacarbon lactam.

[0016] Preferably, the number of carbon atoms in the polycarbonyl lactam is ≤20.

[0017] In this invention, polycyclic lactams and long-chain polyamides are miscible in the molten state during processing. When heated at a pH between 4.5 and 6.5 or 7.5 and 9, they undergo ring-opening and polycondensation reactions with the monomers and low-molecular-weight prepolymers of the polyamide. The components with lower molecular weights have stronger mobility and higher reactivity in the polyamide melt. Therefore, the molecular weight distribution of long-chain polyamides can be narrowed, and small molecule components can be reduced, thereby reducing the precipitation during processing.

[0018] Furthermore, the long carbon chain polyamide molecular chains that undergo polymerization after extrusion processing still possess polymerization reactivity. During long-term media-resistant use after molding pipelines, the molecular weight length can still be increased, resisting molecular chain degradation caused by environmental media and effectively improving the problem of small molecule precipitation during long-term use.

[0019] The grafting toughening agent is a graft-modified polyolefin polymer, and its grafting groups are imine groups, maleic anhydride groups or glycidyl methacrylate groups, with a grafting rate of 0.5 to 1.2 wt%, such as 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 1.2 wt%, etc.

[0020] In this invention, examples of the grafting toughening agent include, but are not limited to, POE-MAH, POE-GMA, EPDM-MAH, EPDM-GMA, EMA-GMA, and EBA-GMA. The addition of the grafting toughening agent effectively increases the molecular weight of the long-chain nylon material, while its grafting groups can provide the acidic or alkaline environment required to initiate the ring-opening of polycarbolactams.

[0021] In this invention, the mass fraction of the grafting toughening agent can be 2%, 5%, 10%, 15%, 18%, 20%, etc.

[0022] In this invention, the antioxidant includes one or more of hindered phenols, hindered amines, phosphites, potassium iodide-copper iodide inorganic stabilizers, or aromatic amines; the mass fraction of the antioxidant can be 0.2%, 0.5%, 0.8%, 1.0%, 1.2%, etc.

[0023] In this invention, the mass fraction of other additives is preferably 0.1 to 2 wt%. Preferably, the other additives include any one or a combination of two or more of the following: lubricants, hydrolysis resistant agents, flame retardants, UV stabilizers, light stabilizers, pigments, masterbatches, and inorganic salts.

[0024] The present invention also provides a method for preparing the long carbon chain polyamide material, wherein long carbon chain polyamide, polylactam, graft toughening agent, antioxidant and optional other additives are mixed and then extruded and granulated using an extruder.

[0025] Preferably, a low-speed mixer is used for mixing at 100–200 rpm for 5–10 minutes.

[0026] Preferably, the extrusion temperature is 240–255°C.

[0027] Preferably, the screw speed is 500–700 rpm.

[0028] Preferably, the vacuum degree is -0.05 to -0.07 MPa.

[0029] The long-chain polyamide material of this invention, during the processing of corrugated pipes or smooth pipes, has a small molecule precipitate of ≤1g / 100Kg polyamide material collected continuously for 4 hours at the mandrel, sizing sleeve, vacuum box and corrugated block; after soaking in a gasoline, ethylene glycol / water mixture for 48 hours, the amount of soluble small molecules precipitated is ≤0.1%wt.

[0030] Compared with the prior art, the present invention has at least the following technical advantages:

[0031] (1) During the extrusion process of long carbon chain polyamide materials, by adding an appropriate amount of polyolamines to open the ring when heated, and reacting with the monomers and low molecular weight prepolymers of polyamide, the content of small molecule components is effectively reduced; at the extruder mandrel, sizing sleeve, vacuum box and corrugated block, the small molecule precipitates collected after 4 hours of continuous production are ≤1g / 100Kg of polyamide material, which effectively improves the precipitation problem of long carbon chain polyamide materials during processing.

[0032] (2) The long carbon chain polyamide molecular chain still has polymerization activity after the polymerization reaction occurs during extrusion processing. During long-term media resistance after molding pipeline, the molecular weight length can still be increased, resisting molecular chain degradation caused by environmental media. After soaking in gasoline and ethylene glycol / water mixture for 48 hours, the amount of soluble small molecules precipitated is ≤0.1%wt, which effectively improves the problem of small molecule precipitation during long-term use. Detailed Implementation

[0033] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be considered as specific limitations thereof.

[0034] The raw material grades and supplier information used in the preparation examples and embodiments of this invention are as follows:

[0035] Table 1 Raw Material Grades and Supplier Information

[0036] Raw material grade Material type Raw material manufacturers L3001 Polyamide 12 Wanhua Chemical Group Co., Ltd. PA1012 Polyamide 1012 Shandong Xianglong New Materials Co., Ltd. Decylactam polycarbolactam Wanhua Chemical Group Co., Ltd. dodecyl lactam polycarbolactam Wanhua Chemical Group Co., Ltd. Butyrolactam Butyrolactam China Petroleum & Chemical Corporation Sebacic acid se ... Sebacic acid se ... Wanhua Chemical Group Co., Ltd. GR216 Graft toughening agent DowDuPont Inc. 1098 antioxidants BASF Corporation 168 antioxidants BASF Corporation Erucamide lubricant Heda Chemistry silicone lubricant Silike Technology Co., Ltd.

[0037] Example 1

[0038] Long-chain polyamide materials for improving processing precipitation were prepared from the following raw materials in the following weight percentages:

[0039]

[0040]

[0041] Among them, the long-chain polyamide is polyamide 12, and the grade used is L3001; the polycaprolactam is dodecanolactam, with a purity greater than 99%; the graft toughening agent is GR216; the antioxidants are 1098 (0.4%) and 168 (0.2%); other additives include lubricant (0.2%), UV stabilizer UV 329 (0.1%), light stabilizer 770 (0.1%), and color masterbatch (0.6%).

[0042] The material particles are prepared through the following steps:

[0043] Long-chain polyamide, polylactam, grafted toughening agent, antioxidant, and other additives are mixed uniformly in a low-speed mixer at 100 rpm for 10 minutes according to the specified ratio. The mixture is then extruded in a twin-screw extruder at 500 rpm. During the extrusion process, the processing temperature is 230°C in the feeding section, approximately 250°C in the plasticizing and homogenizing sections, and 230°C at the die head. The production capacity is 50 kg / h, and the vacuum degree is -0.05 MPa.

[0044] Example 2

[0045] The only difference between this embodiment and Example 1 is that the type of polycarbolactam is changed from dodecalactam to decalactam; all other conditions are the same as in Example 1.

[0046] Example 3

[0047] The only difference between this embodiment and Example 1 is that the amount of dodecanolactam is changed from 0.5% to 0.2%, and the amount of polyamide 12 resin is changed from 82.9% to 83.2%. All other conditions are the same as in Example 1.

[0048] Example 4

[0049] The only difference between this embodiment and Example 1 is that the amount of dodecanolactam is changed from 0.5% to 0.8%, and the amount of polyamide 12 resin is changed from 82.9% to 82.6%. All other conditions are the same as in Example 1.

[0050] Example 5

[0051] The only difference between this embodiment and Example 1 is that the type of long-chain polyamide is changed from polyamide 12 to polyamide 1012, with the grade PA1012, and the processing temperature in each temperature zone is increased by 10°C during the extrusion process. All other conditions are the same as in Example 1.

[0052] Comparative Example 1

[0053] The only difference between this comparative example and Example 1 is that the amount of dodecanolactam is changed from 0.5% to 0%, and the amount of nylon 12 resin is changed from 82.9% to 83.4%. All other conditions are the same as in Example 1.

[0054] Comparative Example 2

[0055] The only difference between this comparative example and Example 1 is that the amount of dodecanolactam is changed from 0.5% to 1.2%, and the amount of nylon 12 resin is changed from 82.9% to 82.2%. All other conditions are the same as in Example 1.

[0056] Comparative Example 3

[0057] The only difference between this comparative example and Example 1 is that the polycarbolactam (dodecanolactam) is replaced with butyrolactam; all other conditions are the same as in Example 1.

[0058] Comparative Example 4

[0059] The only difference between this comparative example and Example 1 is that the polycarbolactam (dodecanolactam) is replaced with sebacic acid ...

[0060] The materials of Examples 1-5 and Comparative Examples 1-4 were tested according to the following method:

[0061] (1) Melt Flow Index (MVR): Tested according to ISO 1133-1:2022 standard, test conditions are 5Kg + 275℃;

[0062] (2) Notched impact strength of simply supported beam (23℃ & -30℃): Tested according to ISO 178-2:2020 standard;

[0063] (3) pH value of the polymer: determined according to ISO 1148 standard;

[0064] (4) Processing precipitate (g / 100Kg): Samples were continuously tested using a Bellaform 50 single-layer extruder. The extrusion process was as follows: processing temperature 240-250℃, die: 16 / 12, linear speed 36m / min, extrusion of 8*1mm sample tubes. Before each sample change, the die, sizing sleeve, vacuum chamber and corrugated block were cleaned. After 4 hours of stable extrusion, the precipitate was collected at the previous position, dried at 60℃ for 4 hours and weighed. Processing precipitate = weight of precipitate / extrusion amount of 100Kg polyamide.

[0065] (5) 48h soaking precipitation rate of 98# gasoline and 48h soaking precipitation rate of ethylene glycol / water: Take 10g of sample tubes with qualified size in (4), weigh them and soak them in 300mL of 98# gasoline and ethylene glycol / water mixture. The soaking conditions are 50℃ for 48h. After soaking, take all the liquid and transfer it to a rotary evaporator to evaporate to constant weight. Weigh the remaining powder material. The soaking precipitation rate = the remaining powder material mass / 10g.

[0066] Table 2. Test results of examples and comparative examples.

[0067]

[0068] As shown in Tables 1 and 2, the long-chain polyamide materials with improved processing and precipitation prepared in Examples 1-6 of this invention have melt flow indexes that match the pipeline extrusion process, MVRs between 10-25 ml / min, and polymer pH values ​​between 4.5-6.5 or 7.5-9, suitable for the ring-opening polymerization conditions of multi-carbon lactams. During continuous pipeline processing for 4 hours, the amount of processing and precipitation is ≤1 g / 100 kg. After soaking in a gasoline / ethylene glycol / water mixture for 48 hours, the amount of soluble small molecules precipitated is ≤0.1% wt, greatly improving the processing and long-term use conditions of long-chain polyamides and addressing the small molecule precipitation problem. Comparison with comparative examples shows that the addition of an appropriate amount of multi-carbon lactams effectively triggers the re-reaction of low molecular weight molecules, reducing precipitation. However, low-carbon lactams such as butyrolactam, due to their low melting and boiling points and higher difficulty in ring-opening, cannot achieve the same improvement effect.

[0069] This invention illustrates a long-chain polyamide material with improved processing and precipitation, and its preparation method, through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

Claims

1. A long-chain polyamide material, characterized in that, The components include the following mass fractions:

2. The long-chain polyamide material according to claim 1, characterized in that, The long-chain polyamide is a polyamide with an average number of carbon atoms in the main chain ≥ 8; Preferably, the long-chain polyamide is selected from one or more of PA610, PA612, PA10, PA12, PA11, PA12, and PA1212; Preferably, the long-chain polyamide has an Ubbelohde viscosity between 1.8 and 2.5, and a melt flow index (MVR) at 235°C and 2.16 kg between 3 and 12 g / 10 min. Preferably, the end groups of the long-chain polyamide are amino and carboxyl groups.

3. The long-chain polyamide material according to claim 1 or 2, characterized in that, Polycarbolactams have ≥10 carbon atoms; Preferably, the number of carbon atoms in the polycarbon lactam is ≤20; Preferably, the polycarbon lactam is selected from one or more of decacarbon lactam, undecanolactam, and dodecacarbon lactam; Preferably, the mass fraction of the polycarbolactam is 0.1%-0.5%.

4. The long-chain polyamide material according to any one of claims 1-3, characterized in that, The grafting toughening agent is a grafted modified polyolefin polymer, and its grafting groups are imine groups, maleic anhydride groups or glycidyl methacrylate groups, with a grafting rate of 0.5 to 1.2 wt%.

5. The long-chain polyamide material according to any one of claims 1-4, characterized in that, The grafting toughening agents include, but are not limited to, POE-MAH, POE-GMA, EPDM-MAH, EPDM-GMA, EMA-GMA, and EBA-GMA; Preferably, the antioxidant includes one or more of hindered phenols, hindered amines, phosphites, potassium iodide-copper iodide inorganic stabilizers, or aromatic amines; Preferably, the mass fraction of other additives is 0.1–2 wt%. Preferably, the other additives include any one or a combination of two or more of the following: lubricants, hydrolysis resistant agents, flame retardants, UV stabilizers, light stabilizers, pigments, masterbatches, and inorganic salts.

6. The method for preparing the long-chain polyamide material according to any one of claims 1-5, characterized in that, Long-chain polyamide, polylactam, graft toughening agent, antioxidant, and optionally other additives are mixed and then extruded and granulated using an extruder.

7. The preparation method according to claim 6, characterized in that, During mixing, a low-speed mixer should be used at a speed of 100–200 rpm for a mixing time of 5–10 minutes. Preferably, the extrusion temperature is 240–255°C. Preferably, the screw speed is 500–700 rpm. Preferably, the vacuum degree is -0.05 to -0.07 MPa.

8. The application of the long-chain carbon polyamide according to any one of claims 1-5 or the long-chain carbon polyamide prepared by the preparation method according to claim 6 or 7, which can be used to prepare air brake lines, cooling lines, fuel lines, lubricating oil lines and oil-gas lines.

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