Heat-resistant and hydrolysis-resistant automobile pipeline material and preparation method thereof

Abstract

The invention provides a heat-resistant and hydrolysis-resistant automobile pipeline material and a preparation method thereof. Comprising the following components in parts by weight: 45-83 parts of long carbon chain nylon; 5 to 15 parts of polypropylene; 0.5 to 3 parts of a compatilizer; 10 to 25 parts of a toughness modifier; 6-15 parts of a flexible modifier; and 0.1-2 parts of an antioxidant. The heat-resistant and hydrolysis-resistant automobile pipeline material provided by the invention keeps excellent toughness and processing flexibility, and also obtains excellent long-term aging resistance, and the notch impact strength retention rate can reach 70% or above at 150 DEG C / 500 h; the notched impact strength retention rate of the anti-freezing solution at 130 DEG C / 500 h can reach 80% or above. The composite material is suitable for preparing cooling pipelines with heat-resistant and hydrolysis-resistant requirements, is particularly suitable for being applied to parts such as automobile air pipes, oil pipes and cooling liquid pipelines, and has the advantage of high cost performance.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a heat-resistant and hydrolysis-resistant automobile pipeline material and a preparation method thereof. Background Art

[0002] Nylon is oil-resistant, pressure-resistant, corrosion-resistant, shock-resistant, cold-resistant, has good flexibility, and has a low fuel expansion coefficient. It is also very easy to process, so it is an ideal material for manufacturing automotive oil pipes. In addition, compared to rubber pipes, nylon has the advantages of being light, environmentally friendly, and recyclable.

[0003] Among them, long carbon chain nylon refers to nylon with a methylene length of more than 10 in the chain segment, including PA11, PA12, PA1012, PA1010, PA1212, PA612, PA610, PA513, PA515, etc. In the automotive field, in order to adapt to the limited interior layout space, the pipe bends need to have large bendability. If the material modulus is too high, it is easy to cause hard pressure damage. Long carbon chain nylon still has good toughness and softness under low temperature conditions. Therefore, in low temperature areas, long carbon chain nylon can be used to prepare soft products and cold-resistant parts.

[0004] Furthermore, as a polyamide composite material for automobile engine peripheral parts, it must not only have the toughness to be used in complex environments, and the softness to facilitate processing and assembly in narrow spaces, but also have good long-term heat aging resistance under harsh working conditions, especially the strength and toughness (tensile elongation at break and impact strength) must not decay too quickly, because the engine peripheral parts need to be exposed to high temperature environments during their service life, and are in a long-term vibration state during operation. If the strength and toughness decay too quickly, it will directly cause the parts to fail prematurely before the normal service life, posing huge safety hazards and economic risks. For this reason, the OEMs have successively increased the heat aging resistance standards for materials. Therefore, it is very necessary to research and develop polyamide composite materials that have both toughness, softness, heat aging resistance, and coolant resistance, which has great practical significance.

[0005] In developed countries, 60% to 70% of long-chain nylon is used to produce automotive hoses, such as brake pipes, oil pipes, clutch hoses, etc. 70% of automotive hoses in Europe are made of PA12, and half of automotive hoses in the United States are also made of PA12. However, the price of PA11 and PA12 resin raw materials is very high, which is more than 5 times that of ordinary nylon (PA66).

[0006] DOWSIL was the first to develop silicone polyamide elastomers, thermoplastic silicone elastomers formed by vulcanized silicone rubber particles on a polyamide substrate. After high-temperature aging at 150°C, they can still maintain high mechanical strength and can be used continuously at high temperatures of 140°C. They can be used in products in consumer electronics, cosmetics, food, and automobiles. However, their price is more than four times that of ordinary nylon (PA66), and their application in the field of automotive pipelines is obviously not economical.

[0007] In addition, the main components of automotive coolant (antifreeze) are ethylene glycol and water. Therefore, the pipe materials that come into contact with the coolant must be able to withstand long-term corrosion by the coolant at high temperatures and have excellent hydrolysis resistance and high temperature resistance.

[0008] Patent CN117511197B uses high-viscosity polyamide resin and polyketone resin as base materials, and compound toughening agents, chain extenders and antioxidants to obtain a hydrolysis-resistant extrudable polyamide material. Patent CN116178945B uses different types of plasticizers, toughening agents and chain extenders to improve the hydrolysis resistance of long-chain nylon materials in automobile cooling pipes, reduce the melt index, and improve the stability of the extrusion process. Patent CN115785662B first prepares high-end amino-based long-chain polyamide resins, and then mixes chain extenders to obtain a composition of polyamide hoses for cooling pipes.

[0009] The effects of existing patents are still unsatisfactory, and all adopt the solution of introducing chain extenders from outside to increase the molecular weight of nylon to compensate for the chain breakage loss of molecular chains during hydrolysis and thermal aging. However, the presence of chain extenders can easily lead to sudden changes in melt strength due to changes in production rhythm, resulting in disadvantages such as rough surface and uneven wall thickness, and deteriorating the processing and molding stability of the product. Summary of the invention

[0010] In order to solve the above problems, the present invention provides a heat-resistant and hydrolysis-resistant automobile pipeline material, which maintains excellent toughness and processing softness, with an initial notched impact strength of more than 85KJ / m2 and an elongation at break of more than 250%; it also obtains excellent long-term aging performance, with a notched impact strength retention rate of more than 70% at 150°C / 500h and a notched impact strength retention rate of more than 80% at 130°C / 500h of antifreeze.

[0011] To achieve the above object, the present invention adopts the following technical solution:

[0012] A heat-resistant and hydrolysis-resistant automobile pipeline material comprises the following components in parts by weight:

[0013] 45-83 parts of long carbon chain nylon;

[0014] Polypropylene 5-15 parts;

[0015] Compatibilizer 0.5-3 parts;

[0016] 10-25 parts of toughness modifier;

[0017] 6-15 parts of flexibility modifier;

[0018] Antioxidant 0.1-2 parts.

[0019] The long carbon chain nylon is selected from one or more of PA610, PA612, PA510, PA513 and PA515, with a viscosity number (VN) ≥ 180 and a melting point of 190-230°C;

[0020] The polypropylene is a composition of polypropylene A and polypropylene B; the melting point is 150-190°C; the polypropylene A is a random copolymer polypropylene, and the melt flow rate is 0.2-3g / 10min at 230°C / 2.16KG; the polypropylene B is a homopolymer polypropylene, and the melt flow rate is 0.2-3g / 10min at 230°C / 2.16KG; the weight ratio of the polypropylene A to the polypropylene B is 10:1-3:1.

[0021] The polypropylene is a widely used general-purpose plastic because of its light weight, wide source and low price. It is currently known to be used in polyamide systems mainly as a lightweight and low-cost compound, and it is often also required to be used under the premise of a large performance margin. However, there is no report on using it to improve the heat aging resistance of polyamide systems. In addition, due to the compatibility problem between polypropylene and polyamide, those skilled in the art will exclude it at the first time when designing a formula for the purpose of improving the long-term heat aging resistance of the polyamide system. The inventors have unexpectedly found through a large number of experimental verifications that the introduction of suitable polypropylene into a flexible polyamide system can significantly improve the heat aging resistance of polyamide-based composite materials.

[0022] The compatibilizer is polyacrylamide. The polyacrylamide has good compatibility with both polypropylene and polyamide, and can play an excellent bridging role. Compared with the compatibilizers such as silane coupling agents in traditional tests, it gives the composite material better interface bonding and dispersed distribution. Further experimental verification found that the addition of polyacrylamide bridges polypropylene and polyamide, playing a role similar to that of a chain extender, reducing the possibility of being extracted by frozen liquid and improving the hydrolysis resistance of the composite material. It also avoids the disadvantages of chain extenders that easily cause sudden changes in melt strength and affect processing stability.

[0023] The toughness modifier is any one of maleic anhydride grafted octene ethylene copolymer, maleic anhydride grafted polypropylene, and maleic anhydride grafted polyethylene, or a combination of two or more thereof.

[0024] The flexibility modifier is any one of N-butylbenzenesulfonamide, dioctyl phthalate, dibutyl phthalate, bisphenol A bis(diphenyl phosphate)\resorcinol bis(diphenyl phosphate) or a combination of two or more thereof.

[0025] The antioxidant is one or more of the following: copper salt antioxidant, phosphate antioxidant, amine antioxidant, phenol antioxidant, and ester antioxidant.

[0026] The preparation method of the above-mentioned heat-resistant and hydrolysis-resistant automobile pipeline material comprises the following steps: (1) weighing raw materials respectively according to the formula; (2) putting all components except the liquid flexibility modifier into a high-speed mixer and mixing them until they are uniform to obtain a premix; (3) then putting the obtained premix into a twin-screw extruder for melt mixing, and the flexibility modifier adopts a liquid pump side feeding process for extrusion granulation; wherein the extrusion temperature is 200-250°C, and the screw speed is set to 250-500rpm.

[0027] The inventors adopted more economical (price is about 2 times of ordinary nylon PA66) resins such as PA612 and PA515 for compounding and modification. Although the obtained composite material meets the requirements of toughness and softness, its heat aging resistance and hydrolysis aging resistance are not ideal. After a large number of experiments and verifications, it was surprisingly found that the use of the recognized technical means in the field to improve the aging resistance of polyamides - adding antioxidants such as copper salts, phosphates, amines, phenols, etc., the aging resistance of polyamide pipeline composite materials is not satisfactory, especially the toughness decays too fast, specifically, the notched impact strength retention rate after 150℃ / 500h heat aging drops to less than 40%, and the notched impact strength retention rate after 130℃ / 500h coolant aging drops to less than 30%.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention introduces appropriate polypropylene into the long carbon chain nylon system, giving the long carbon chain nylon composite material excellent long-term aging resistance. At 150℃ / 500h, the notched impact strength retention rate can reach more than 70%; at 130℃ / 500h, the notched impact strength retention rate can reach more than 80%. It is particularly suitable for preparing cooling pipes with heat resistance and hydrolysis resistance requirements.

[0030] 2. The use of long carbon chain nylon and polypropylene, two different melting point matrix resins, broadens the melt processing window and gives the material suitable melt strength at different temperatures and shear gradients, avoiding the disadvantages of conventional use of tackifiers, cross-linking agents, chain extenders, etc., which are prone to sudden changes in melt strength due to changes in production rhythm, and ensures the stability of product processing and molding.

[0031] 3. The synergistic combination of acrylamide compatibilizer enables the flexible long-chain polyamide material to maintain excellent initial flexibility, with an initial notched impact strength of more than 85KJ / m2 and an elongation at break of more than 250%. It also reduces the possibility of being extracted by freezing liquid and improves the hydrolysis resistance of the composite material.

[0032] 4. Compared with the pipeline materials with the same specifications and performance as PA12, the price of the pipeline materials of the present invention has dropped by more than half. Under the situation of the rapid development of new energy vehicles and energy storage industries in my country, it is very suitable for the cost-effectiveness priority strategy.

[0033] 5. Excellent long-term aging resistance makes bio-based PA610, PA515 and other resin raw materials that were originally not suitable for coolant environments due to their high water absorption rate also meet the use requirements, expanding the application range of bio-based resins. DETAILED DESCRIPTION

[0034] In order to make the technical solution of the present invention clearer and more specific, the present invention is further described below. Any equivalent replacement of the technical features of the technical solution of the present invention and any solution derived by conventional reasoning shall fall within the protection scope of the present invention.

[0035] The materials used in the present invention are as follows:

[0036] Long carbon chain nylon: PA612, Shandong Dongchen Engineering Plastics

[0037] Long carbon chain nylon: PA610, Shandong Dongchen Engineering Plastics

[0038] Long carbon chain nylon: PA515, Cathay Bio

[0039] Polypropylene 1: Random copolymer polypropylene, MFR 0.3g / 10min, ExxonMobil

[0040] Polypropylene 2: Random copolymer polypropylene, MFR 2.5g / 10min, ExxonMobil

[0041] Polypropylene 3: Random copolymer polypropylene, MFR 60g / 10min, ExxonMobil

[0042] Polypropylene 4: Homopolymer polypropylene, MFR 0.5g / 10min, Sinopec

[0043] Polypropylene 5: Homopolymer polypropylene, MFR 30g / 10min, Sinopec

[0044] Compatibilizer 1: polyacrylamide, commercially available

[0045] Compatibilizer 2: Silane, KH560, commercially available

[0046] Toughness modifier: N413A, commercially available

[0047] Flexibility modifier: Proviplast 024, commercially available

[0048] Antioxidant 1: Copper salt, H3386, commercially available

[0049] Antioxidant 2: phenol, 1098, commercially available

[0050] Colorant: Commercially available

[0051] The material preparation method is as follows:

[0052] According to the specific embodiment described in Table 1 and the formula dosage (weight parts) of the comparative example in Table 2, the raw materials are weighed respectively, and the components except the liquid flexibility modifier are put into a high-speed mixer for mixing until uniformity to obtain a premix; then the obtained premix is ​​put into a twin-screw extruder for melt mixing, and the flexibility modifier adopts a liquid pump side feeding process for extrusion granulation. The extrusion temperature is 200-250°C, and the screw speed is set to 250-500rpm.

[0053] Product performance test method:

[0054] The particles obtained in the examples and comparative examples were dried in an oven at 100-110°C for 2-4 hours and then injection molded at 220-250°C. The mold temperature was controlled at 60-90°C. The relevant performance tests were carried out according to the following test methods. The test results are detailed in Tables 1 and 2.

[0055] (1) Tensile modulus: according to ISO 527 method, sample size 170*10*4mm, test speed 1mm / min;

[0056] (2) Tensile elongation at break: according to ISO 527 method, specimen size 170*10*4mm, test speed 50mm / min;

[0057] (3) Notched impact strength: according to ISO 179 / 1eA method, specimen size 80*10*4mm;

[0058] (4) Low-temperature notched impact strength: The specimen size is 80*10*4 mm. The specimen is placed in a -30°C freezer for 24 hours, then taken out immediately and tested according to ISO 179 / 1eA standard method. The test of a single specimen must be completed within 10 seconds.

[0059] (5) Heat aging resistance: 1) The performance (strength or elongation) of the injection molded specimens after conditioning in a laboratory environment is recorded as the pre-aging performance according to the standard test method; 2) After the standard test specimens are placed in a 150°C oven for 500 hours, they are conditioned in a laboratory environment (23°C, 50% RH) for 24 hours and tested by the standard method and recorded as the post-aging performance; 3) Performance retention rate = post-aging performance / pre-aging performance * 100%.

[0060] (6) Hydrolysis aging resistance: 1) The performance (strength or elongation) of the injection molded specimens after conditioning in a laboratory environment is recorded as the pre-aging performance according to the standard test; 2) After the standard test specimens are placed in a 130°C coolant (ethylene glycol / water solution with a volume ratio of 1:1) for 500 hours, they are conditioned in a laboratory environment (23°C, 50% RH) for 24 hours and tested by the standard method and recorded as the post-aging performance; 3) Performance retention rate = post-aging performance / pre-aging performance * 100%.

[0061] Table 1 Example composition ratio (weight parts) and performance test results

[0062]

[0063]

[0064] Table 2 Comparative Example Group Distribution Ratio (Parts by Weight) and Performance Test Results

[0065]

[0066] From the performance test results of Examples 1 to 8 in Table 1 and Comparative Examples 1 to 9 in Table 2, it can be clearly seen that the present invention, by introducing polypropylene into the long carbon chain nylon system, endows the long carbon chain nylon composite material with excellent long-term aging resistance, 150℃ / 500h, the notched impact strength retention rate can reach more than 70%; antifreeze 130℃ / 500h, the notched impact strength retention rate can reach more than 80%, and the technical effect is remarkable. However, the notched impact strength retention rate of the system with only antioxidant added (Comparative Example 1) after 150℃ / 500h heat aging drops to less than 40%, and the notched impact strength retention rate after 130℃ / 500h coolant aging drops to less than 30%. In addition, polypropylene is only helpful for improving the heat aging resistance of the flexible polyamide system, and has almost no effect on improving the heat aging resistance of the non-flexible system (Comparative Example 9).

[0067] Compared with the silane coupling agent used in traditional modification (Comparative Examples 3 and 4), the synergistic combination of acrylamide compatibilizers makes the flexible long-chain polyamide material mixed and dispersed evenly, tightly combined, maintains excellent initial toughness and processing softness, and obtains excellent long-term heat aging resistance.

[0068] Although the above embodiments provide a relatively detailed textual description of the design ideas of the present invention, these textual descriptions are only simple textual descriptions of the design ideas of the present invention, rather than limitations on the design ideas of the present invention. Any combination, addition or modification that does not exceed the design ideas of the present invention shall fall within the protection scope of the present invention.

Claims

1. A heat-resistant and hydrolysis-resistant automobile piping material, characterized in that: The composition comprises the following components in parts by weight:

2. The heat-resistant and hydrolysis-resistant automobile piping material according to claim 1, characterized in that: The long carbon chain nylon is selected from one or more of PA610, PA612, PA510, PA513 and PA515, with a viscosity number (VN) ≥ 180 and a melting point of 190-230°C.

3. The heat-resistant and hydrolysis-resistant automobile piping material according to claim 1, characterized in that: The polypropylene is a composition of polypropylene A and polypropylene B; the melting point is 150-190°C; the polypropylene A is a random copolymer polypropylene, and the melt flow rate is 0.2-3g / 10min at 230°C / 2.16KG; the polypropylene B is a homopolymer polypropylene, and the melt flow rate is 0.2-3g / 10min at 230°C / 2.16KG.

4. The heat-resistant and hydrolysis-resistant automobile piping material according to claim 3, characterized in that: The weight ratio of the polypropylene A to the polypropylene B is 10:1-3:

1.

5. The heat-resistant and hydrolysis-resistant automobile piping material according to claim 1, characterized in that: The compatibilizer is polyacrylamide.

6. The heat-resistant and hydrolysis-resistant automobile piping material according to claim 1, characterized in that: The toughness modifier is any one of maleic anhydride grafted octene ethylene copolymer, maleic anhydride grafted polypropylene, and maleic anhydride grafted polyethylene, or a combination of two or more thereof.

7. The heat-resistant and hydrolysis-resistant automobile piping material according to claim 1, characterized in that: The flexibility modifier is any one of N-butylbenzenesulfonamide, dioctyl phthalate, dibutyl phthalate, bisphenol A bis(diphenyl phosphate)\resorcinol bis(diphenyl phosphate) or a combination of two or more thereof.

8. The heat-resistant and hydrolysis-resistant automobile piping material according to claim 1, characterized in that: The antioxidant is one or more of the following: copper salt antioxidant, phosphate antioxidant, amine antioxidant, phenol antioxidant, and ester antioxidant.

9. The method for preparing the heat-resistant and hydrolysis-resistant automobile piping material according to any one of claims 1 to 8, characterized in that: The steps are as follows: (1) weighing raw materials respectively according to the formula; (2) putting all components except the liquid flexibility modifier into a high-speed mixer and mixing them until they are uniform to obtain a premix; (3) then putting the obtained premix into a twin-screw extruder for melt mixing, and the flexibility modifier adopts a liquid pump side feeding process to perform extrusion granulation.

10. The method for preparing the heat-resistant and hydrolysis-resistant automobile piping material according to claim 9, characterized in that: In step (3), the extrusion temperature is 200-250°C, and the screw speed is set to 250-500rpm.

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