Semi-aromatic polyamide composition as well as preparation method and application thereof

Abstract

The invention discloses a semi-aromatic polyamide composition which comprises the following components in parts by weight: 79-101 parts of semi-aromatic polyamide; 5 to 30 parts of a maleic anhydride grafted toughening agent; and 3-8 parts of an amine cooling liquid resistant modifier. Through the semi-aromatic polyamide resin with specific repetitive units, the maleic anhydride grafted toughening agent and the synergistic cooling liquid resistant modifier, the semi-aromatic polyamide composition has the advantage of good cooling liquid resistance, the melting point of the composition can be controlled at 170-200 DEG C, and the semi-aromatic polyamide composition is suitable for preparation of liquid cooling pipelines of new energy vehicles.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a semi-aromatic polyamide composition and a preparation method and application thereof. Background Art

[0002] The fundamental changes in the power systems of new energy vehicles, especially pure electric vehicles, are reshaping the thermal management system architecture of vehicles. Compared with traditional fuel vehicles, electric vehicles need to further improve thermal management efficiency. The cooling system of new energy vehicles can be divided into air cooling, liquid cooling and phase change materials according to the cooling medium. Liquid cooling is the main cooling method for new energy vehicles, including water cooling and oil cooling. As an important component of new energy vehicles, the coolant pipeline needs to meet multiple requirements such as hydrolysis resistance, oil resistance, high temperature resistance, and lightweight.

[0003] In the prior art, rubber hoses are rarely used due to their poor environmental adaptability or low cooling efficiency. For example, silicone hoses have low cooling efficiency, high weight, and are easy to age. Nylon tubes and other materials have gradually become the main materials used for coolant pipelines due to their light weight and simple processing technology. The nylons used in coolant pipelines mainly include aliphatic and aromatic nylons. Aliphatic nylons are represented by PA11, PA12, and PA612, and aromatic nylons are represented by PA9T and PA11T. Nylon plastic pipes can be used in the motor compartment, chassis, and battery pack. According to the different requirements of temperature, pressure, and assembly at different locations, select nylon materials and structural types with corresponding temperature resistance grades. However, these aliphatic nylons are not tolerant to coolants and often need to be prepared into multi-layer structures. For example, PA11 and PA12 materials need to be prepared into three-layer or five-layer pipes with barrier materials such as EVOH, ETFE, and EFEP to meet the requirements of long-term use. PA612 can only be used as a cost-reduction solution for PA11 and PA12 because of its poorer resistance to hydrolysis and alcoholysis, and is currently less used.

[0004] For the cooling pipes used in new energy electric vehicles, the material is required to have both the characteristics of low melting point and easy processing, and also have excellent tolerance to coolants to maintain long-term performance. Elongation at break is a key indicator of pipeline materials, and is closely related to the elongation test, burst test, and dynamic fatigue test performance of the pipeline after molding. It is generally believed in the industry that the elongation at break of the material > 150% can meet the requirements of the elongation test, burst test, and dynamic fatigue test of the pipeline and prepare qualified pipelines; and when the elongation at break of the material is < 20%, the service life of the material has reached its limit. Therefore, by testing the initial elongation at break and after coolant resistance, it can be shown whether the polyamide composition is suitable for pipelines.

[0005] Patent CN118063957A discloses a flexible hydrolysis-resistant extruded polyamide material, which mainly includes 20-52% polyamide resin, 20-50% polyphenylene ether resin, 3-7% compatibilizer, 8-14% toughening agent, 10-14% composite plasticizer, 0.3-0.6% antioxidant and 0.4-0.7% lubricant. The patent mainly uses aliphatic polyamide PA6, PA612 and other resin matrices, which have poor coolant resistance. Summary of the invention

[0006] The object of the present invention is to overcome the above technical defects and provide a semi-aromatic polyamide composition with good resistance to coolant and suitable processing temperature.

[0007] The present invention is achieved through the following technical solutions: A semi-aromatic polyamide composition, comprising the following components in parts by weight: 79-101 parts of semi-aromatic polyamide; 5-30 parts of maleic anhydride grafted toughening agent; 3-8 parts of amine coolant resistance modifier; The semi-aromatic polyamide is derived from the following units, measured in mole percentage: The diacid units are derived from terephthalic acid and other linear diacids, wherein terephthalic acid accounts for 10-30 mol% of the molar content of the diacid units, and the other linear diacids are selected from at least one of 1,10-decanedioic acid, 1,12-dodecanedioic acid, and 1,18-octadecandioic acid, wherein 1,10-decanedioic acid accounts for 40-100 mol% of the total molar percentage content of the other linear diacids; The diamine unit is derived from 1,10-decanediamine and 1,12-dodecanediamine, wherein 1,10-decanediamine accounts for 30-100 mol% of the total molar percentage content of the diamine unit; The amine coolant-resistant modifier is selected from at least one of N-ethyl p-toluenesulfonamide, dendritic polyamidoamine (PAMAM), 4,4'-methylenebis(3-chloro-2,6-diethylaniline), N,N'-di(2,6-diisopropylphenyl)carbodiimide, and diethyltoluenediamine.

[0008] Preferably, terephthalic acid accounts for 15-25 mol% of the diacid unit molar content, 1,10-decanedioic acid accounts for 80-100 mol% of the total molar content of other linear diacids, and 1,10-decanediamine accounts for 60-100 mol% of the total molar content of diamine units.

[0009] In the semi-aromatic polyamide composition of the present invention, the semi-aromatic polyamide accounts for no less than 60 wt % of the total weight.

[0010] Preferably, the content of the amine coolant resistance modifier is 4-6 parts.

[0011] Preferably, the amine coolant resistance modifier is selected from at least one of N-ethyl p-toluenesulfonamide and dendritic polyamidoamine; More preferably, the amine-based coolant resistance modifier is a dendritic polyamidoamine.

[0012] The melting point range of the semi-aromatic polyamide of the present invention is 170-200° C. The test is performed using a differential scanning calorimeter (DSC) in accordance with ISO 11357-3-2018.

[0013] The relative viscosity of the semi-aromatic polyamide of the present invention is in the range of 2.0-3.2. The test method is: refer to GB12006.1-89, polyamide viscosity determination method; the specific test method is: measure the relative viscosity ηr of the polyamide with a concentration of 0.25 g / dl in 98% concentrated sulfuric acid at 25±0.01°C.

[0014] The semi-aromatic polyamide of the present invention can be a commercially available product or can be obtained by self-production. The self-production method is as follows: adding reaction monomers, benzoic acid, sodium hypophosphite and deionized water into a pressure autoclave; the amount of benzoic acid substance is 1-3% of the total amount of diamine and diacid substances, the weight of sodium hypophosphite is 0.05-0.15% of the total weight of other materials except deionized water, and the weight of deionized water is 20-40% of the total weight of the materials; vacuuming and filling with high-purity nitrogen as a protective gas, heating to 190-210°C within 1.5-2.5 hours under stirring, stirring the reaction mixture at 190-210°C for 0.5-1.5 hours, and then raising the temperature of the reactants to 260-280°C under stirring; reacting at a temperature of 260-280°C and a constant pressure of 3.0-3.4 MPa for 1-3 hours, keeping the pressure constant by removing the formed water, and then gradually reducing the pressure to normal pressure, discharging the material after the reaction is completed to obtain a polyamide resin.

[0015] The maleic anhydride grafted toughening agent is selected from at least one of maleic anhydride grafted POE, maleic anhydride grafted SEBS, and maleic anhydride grafted EPDM; preferably maleic anhydride grafted POE.

[0016] In the maleic anhydride grafted toughening agent, the grafting rate of maleic anhydride is 1-5wt%, preferably 2-3wt%.

[0017] The maleic anhydride grafted toughening agent can be a commercially available product or obtained by self-production, and the self-production method includes but is not limited to: mixing the initiator (dicumyl peroxide, dibenzoyl peroxide), unmodified toughening agent, and maleic anhydride according to the designed proportion (the amount of initiator added is not more than 0.3wt% of the total amount of feed), and mixing in a mixer at 180-220°C to obtain the obtained product.

[0018] The test method for maleic anhydride content is: acid-base titration method. The specific operation method is: put the copolymer into xylene and heat it under reflux to dissolve, after cooling, add a certain amount of 0.05mol / L potassium hydroxide-ethanol solution, and then heat it under reflux for 8h, use 0.1% phenolphthalein solution as an indicator, and titrate to the end point with 0.05mol / L HCl-isopropanol solution while hot. The weight content G is calculated using the following formula: G = (N1 × Vl - N2 × V2) × M ÷ w ÷ 10 Where: N1: KOH-ethanol solution equivalent concentration, N; V1: volume of KOH-ethanol solution, ml; N2: HCl-isopropanol solution equivalent concentration, N; V2: volume of HCl-isopropanol solution, ml; M: equivalent mass of maleic anhydride, g; w: weight of the dried sample after extraction, g.

[0019] Those skilled in the art may choose whether to add 0-3 parts of an auxiliary agent according to actual needs, wherein the auxiliary agent is selected from at least one of a UV stabilizer, a heat stabilizer, and a pigment.

[0020] The preparation method of the semi-aromatic polyamide composition of the present invention comprises the following steps: mixing the components uniformly according to the proportion, and extruding and granulating the components through a twin-screw extruder to obtain the semi-aromatic polyamide composition.

[0021] The semi-aromatic polyamide composition of the present invention has an elongation at break greater than 180% and a coolant resistance retention rate greater than 25%, and is suitable for preparing liquid cooling pipelines.

[0022] The present invention has the following beneficial effects: The present invention introduces a benzene ring structure with a specific molar content into a long carbon chain structure and utilizes the chemical resistance and self-barrier properties of the benzene ring structure, so that the material not only has the excellent toughness of long carbon chain polyamide, but also can effectively prevent the coolant from penetrating into the interior of the material during a long contact with the coolant, and weakens the occurrence of alcoholysis and hydrolysis effects of the polyamide material, thereby significantly improving the performance of the material after aging.

[0023] The present invention unexpectedly discovered that by adding a maleic anhydride grafted toughening agent to the material, maleic anhydride is used to react with the carboxyl end groups in the polyamide to form a capping effect, so that when the material is in contact with the coolant, the attack effect of ethylene glycol / water and oxygen on the carboxyl end groups of the material is weakened, thereby effectively reducing the chain reaction caused by the breaking of the molecular chain to form active free radicals, reducing material degradation, and improving the performance of the material after aging.

[0024] Furthermore, in the present invention, by adding amine anti-coolant aging agents, while improving the activity of the polyamide molecular chain, it can combine with the active free radicals generated by molecular weight chain scission to prevent the free radicals from further attacking other chain segments and causing severe degradation of the material, thereby effectively improving the coolant aging resistance of the material.

[0025] In summary, in the present invention, the benzene ring structure with a specific molar content is used to weaken the penetration of the coolant into the material, the end-capping effect of the maleic anhydride toughening agent is used to improve the stability of the polyamide molecular chain, and the amine coolant-resistant aging agent is used to eliminate the free radicals formed by chain breaking. The three-in-one method effectively improves the coolant resistance of the material. DETAILED DESCRIPTION

[0026] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0027] The sources of raw materials used in the present invention are as follows: The following polyamide resins were obtained by home-made methods: A-1 A-2 A-3 A-4 A-5 A-6 A-7 Terephthalic acid mol 1 1.5 1.9 2.5 3 0.5 3.5 1,10-Decanedioic acid mol 9 8.5 8.1 7.5 7 9.5 6.5 1,10-Decanediamine mol 10 10 10 10 10 10 10 Melting point, °C 175 178 180 185 192 166 206 Relative viscosity 2.6 2.6 2.6 2.6 2.6 2.6 2.6 B-1 B-2 B-3 B-4 B-5 B-6 B-7 B-8 Terephthalic acid mol 1.5 1.5 1.5 1.5 0.5 3.5 1.5 1.5 1,10-Decanedioic acid mol 3.4 3.4 6.8 6.8 7.6 5.2 1.7 1.7 1,12-Dodecanedioic acid mol 5.1 1.7 1.9 1.3 6.8 6.8 1,18-Octadecanedioic acid mol 5.1 1.7 1,10-Decanediamine mol 3 3 6 6 6 6 2 10 1,12-Dodecanediamine mol 7 7 4 4 4 4 8 Melting point, °C 173 172 174 172 163 203 171 172 Relative viscosity 2.6 2.6 2.6 2.6 2.6 2.6 2.6 2.6 N-ethyl-p-toluenesulfonamide: NEO / PTSA, Shouguang Nuomo Chemical Co., Ltd.; Dendritic polyamidoamine: CYD-120C, Weihai Chenyuan Molecular New Materials Co., Ltd.; 4,4'-Methylenebis(3-chloro-2,6-diethylaniline): MCDEA, Jinwotai Chemical Co., Ltd.; N,N'-bis(2,6-diisopropylphenyl)carbodiimide: BCM-011, Zhejiang Pukang Chemical Co., Ltd.; Diethyltoluenediamine: E-100, Shandong Tonglan Chemical Co., Ltd.; Maleic anhydride grafted POE-1: The maleic anhydride grafting rate is 1wt%, and it is made by mixing; Maleic anhydride grafted POE-2: The maleic anhydride grafting rate is 2wt%, and it is made by mixing; Maleic anhydride grafted POE-3: The maleic anhydride grafting rate is 3wt%, and it is made by mixing; Maleic anhydride grafted POE-4: The maleic anhydride grafting rate is 5wt%, which is made by mixing; The above maleic anhydride grafted POE is derived from POE DF640, Mitsui Chemicals, Singapore.

[0028] Maleic anhydride grafted SEBS: The maleic anhydride grafting rate is 2.5wt%, which is self-made by mixing. SEBS comes from Kraton G1652, Shell Company, USA; Maleic anhydride grafted EPDM: The maleic anhydride grafting rate is 2.5wt%. The maleic anhydride grafting rate is increased by mixing. The maleic anhydride grafted EPDM before further modification comes from FUSABOND N416, DuPont, USA; GMA grafted POE: POG-2821, Guangzhou Dongjin Plastic Technology Co., Ltd.; GMA grafted SEBS: KT-2511, Shenyang Ketong Company; POE: POE DF640, Mitsui Chemicals, Singapore.

[0029] Antioxidant: RIANOX 1098, Rianlon Corporation; Carbon black: M717, Cabot Corporation; Various test methods: (1) Coolant resistance: First test the initial elongation at break. Heat and melt the semi-aromatic polyamide composition at 220-260°C and injection mold it into tensile specimens A and B. Test specimen A for tensile properties according to international standard ISO 527-2019 to obtain the initial elongation at break. Place specimen B in an autoclave, mix ethylene glycol and deionized water in a volume ratio of 1:1, pour into the autoclave until the tensile specimen is completely immersed; then place the autoclave in a 135°C high-temperature oven for 2000 hours and take it out. Test the tensile properties of the aged tensile specimen according to international standard ISO 527-2019 to obtain the elongation at break after aging. The calculation method for the coolant resistance retention rate is elongation at break after coolant test / initial elongation at break × 100%.

[0030] Table 1: Contents of components and test results of semi-aromatic polyamide compositions of Examples 1-6 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Polyamide resin A-1 80 90 100 90 90 90 Maleic anhydride grafted POE-1 10 5 30 5 5 5 N-Ethyl p-toluenesulfonamide 3 4 8 3 6 8 Antioxidants 0.5 Carbon Black 0.5 Initial elongation at break % 210 203 225 198 209 218 Coolant resistance retention rate% 28 33 34 27 31 28 It can be seen from Examples 2 / 4 / 5 / 6 that the cooling liquid resistance retention rate is higher when the preferred N-butylbenzenesulfonamide content is used.

[0031] Table 2: Contents of components and test results of semi-aromatic polyamide compositions of Examples 7-11 Example 7 Example 8 Example 9 Example 10 Embodiment 11 Polyamide resin A-1 90 90 90 90 90 Maleic anhydride grafted POE-2 5 Maleic anhydride grafted POE-3 5 Maleic anhydride grafted POE-4 5 Maleic Anhydride Grafted SEBS 5 Maleic Anhydride Grafted EPDM 5 N-Ethyl p-toluenesulfonamide 4 4 4 4 4 Initial elongation at break % 210 216 215 192 195 Coolant resistance retention rate% 35 36 30 32 31 It can be seen from Examples 2 / 7-11 that the cooling liquid resistance retention rate is higher when the maleic anhydride content is preferred.

[0032] Table 3: Contents of components and test results of semi-aromatic polyamide compositions of Examples 12-15 Example 12 Example 13 Embodiment 14 Embodiment 15 Polyamide resin A-1 90 90 90 90 Maleic anhydride grafted POE-1 5 5 5 5 Dendritic polyamidoamine 4 4,4'-Methylenebis(3-chloro-2,6-diethylaniline) 4 N,N'-Bis(2,6-diisopropylphenyl)carbodiimide 4 Diethyltoluenediamine 4 Initial elongation at break % 196 193 195 197 Coolant resistance retention rate% 35 28 30 29 It can be seen from Comparative Examples 2 / 12-15 that, in order to improve the coolant resistance retention rate, the amine coolant resistance modifier is preferably N-butylbenzenesulfonamide and resinous polyamide amine, and further preferably dendritic polyamide amine, the coolant resistance retention rate is higher.

[0033] Table 4: Content of each component and test results of the semi-aromatic polyamide composition of Examples 16-20 Example 16 Embodiment 17 Embodiment 18 Embodiment 19 Embodiment 20 Polyamide resin number A-2 A-3 A-4 A-5 B-1 Polyamide resin content 90 90 90 90 90 Maleic anhydride grafted POE-1 5 5 5 5 5 N-Ethyl p-toluenesulfonamide 4 4 4 4 4 Initial elongation at break % 200 196 192 176 212 Coolant resistance retention rate% 35 36 37 39 30 It can be seen from Examples 2 / 16-19 that when the molar content of terephthalic acid in the diacid unit is preferably 15-25 mol%, the initial elongation at break is higher, so that the elongation at break after the coolant resistance test is significantly higher.

[0034] Table 5: Content of each component and test results of the semi-aromatic polyamide composition of Examples 21-23 Embodiment 21 Embodiment 22 Embodiment 23 Polyamide resin number B-2 B-3 B-4 Polyamide resin content 90 90 90 Maleic anhydride grafted POE-1 5 5 5 N-Ethyl p-toluenesulfonamide 4 4 4 Initial elongation at break % 223 214 209 Coolant resistance retention rate% 29 33 34 It can be seen from Examples 20-23 that the preferred content of 1,10-decanediamine is 60-100 mol % of the total molar percentage content of diamine units.

[0035] Table 6: Contents of components and test results of semi-aromatic polyamide compositions of comparative examples 1-5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Polyamide resin number A-1 A-1 A-1 A-1 A-1 Polyamide resin content 90 90 90 90 90 Maleic anhydride grafted POE-1 5 5 GMA grafted POE 5 GMA Grafted SEBS 5 POE 5 N-Ethyl p-toluenesulfonamide 4 4 4 1 10 Initial elongation at break % 178 183 143 192 226 Coolant resistance retention rate% 16 17 13 18 20 It can be seen from Comparative Examples 1 / 2 / 3 that, although the GMA-grafted toughening agent can also react with the end groups of polyamide compared to the non-grafted toughening agent, the effect of improving the resistance to coolant is not significant enough.

[0036] It can be seen from Comparative Example 4 that if the content of N-ethyl-p-toluenesulfonamide is insufficient, the improvement in resistance to coolant is not significant enough.

[0037] It can be seen from Comparative Example 5 that if the content of N-ethyl-p-toluenesulfonamide is too high, the coolant resistance retention rate will decrease instead.

[0038] Table 7: Contents of components and test results of semi-aromatic polyamide compositions of Comparative Examples 6-11 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Polyamide resin number A-6 A-7 B-5 B-6 B-7 B-8 Polyamide resin content 90 90 90 90 90 90 Maleic anhydride grafted POE-1 5 5 5 5 5 5 N-Ethyl p-toluenesulfonamide 4 4 4 4 4 4 Initial elongation at break % 217 143 228 146 212 209 Coolant resistance retention rate% 15 40 13 36 21 22 It can be seen from Comparative Example 6 / 8 that if the content of terephthalic acid in the diacid is too low, the coolant resistance retention rate is low.

[0039] It can be seen from Comparative Examples 7 / 9 that if the terephthalic acid content is too high, although the coolant resistance retention rate is high, the initial elongation at break cannot meet the initial elongation at break requirement in the industry.

[0040] It can be seen from Comparative Example 10 that even if the content of terephthalic acid in the diacid is within the range of the present invention, if the content of 1,10-decanediamine in the diamine is too low, the coolant resistance retention rate is low.

[0041] It can be seen from Comparative Example 11 that even if the content of terephthalic acid in the diacids is within the range of the present invention, if the content of 1,10-sebacic acid in the other diacids is too low, the coolant resistance retention rate is low.

Claims

1. A semi-aromatic polyamide composition, characterized in that By weight, it includes the following components: 79-101 parts of semi-aromatic polyamide; 5-30 parts of maleic anhydride grafted toughening agent; 3-8 parts of amine coolant resistance modifier; The semi-aromatic polyamide is derived from the following units, measured in mole percentage: The diacid units are derived from terephthalic acid and other linear diacids, wherein terephthalic acid accounts for 10-30 mol% of the molar content of the diacid units, and the other linear diacids are selected from at least one of 1,10-decanedioic acid, 1,12-dodecanedioic acid, and 1,18-octadecandioic acid, wherein 1,10-decanedioic acid accounts for 40-100 mol% of the total molar percentage content of the other linear diacids; The diamine unit is derived from 1,10-decanediamine and 1,12-dodecanediamine, wherein 1,10-decanediamine accounts for 30-100 mol% of the total molar percentage content of the diamine unit; The amine coolant-resistant modifier is selected from at least one of N-ethyl-p-toluenesulfonamide, dendritic polyamidoamine, 4,4'-methylenebis(3-chloro-2,6-diethylaniline), N,N'-di(2,6-diisopropylphenyl)carbodiimide and diethyltoluenediamine.

2. The semi-aromatic polyamide composition according to claim 1, characterized in that The molar content of terephthalic acid in the diacid unit is 15-25 mol%, 1,10-decanedioic acid accounts for 80-100 mol% of the total molar content of other linear diacids, and 1,10-decanediamine accounts for 60-100 mol% of the total molar content of diamine units.

3. The semi-aromatic polyamide composition according to claim 1, characterized in that The content of the amine coolant resistance modifier is 4-6 parts.

4. The semi-aromatic polyamide composition according to claim 1, characterized in that The amine coolant resistance modifier is selected from at least one of N-ethyl p-toluenesulfonamide and dendritic polyamide amine; preferably, the dendritic polyamide amine.

5. The semi-aromatic polyamide composition according to claim 1, characterized in that The melting point of the semi-aromatic polyamide is in the range of 170-200°C.

6. The semi-aromatic polyamide composition according to claim 1, characterized in that The maleic anhydride grafted toughening agent is selected from at least one of maleic anhydride grafted POE, maleic anhydride grafted SEBS, and maleic anhydride grafted EPDM; maleic anhydride grafted POE is preferred; in the maleic anhydride grafted toughening agent, the grafting rate of maleic anhydride is 1-5wt%, preferably 2-3wt%.

7. The semi-aromatic polyamide composition according to claim 1, characterized in that By weight, the invention further comprises 0-3 parts of auxiliary agents, wherein the auxiliary agents are selected from at least one of UV stabilizers, heat stabilizers and pigments.

8. The method for preparing the semi-aromatic polyamide composition according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: mixing the components uniformly according to the proportion, extruding and granulating through a twin-screw extruder to obtain a semi-aromatic polyamide composition.

9. Use of the semi-aromatic polyamide composition according to any one of claims 1 to 7, characterized in that: Used to prepare liquid cooling lines.

10. A pipe prepared using the semi-aromatic polyamide composition according to any one of claims 1 to 7.