A polyethylene fuel tank special resin with excellent barrier property and low temperature toughness and a preparation method thereof

Abstract

The present application relates to the technical field of polymer modification, and provides a polyethylene fuel tank special resin with excellent barrier property and low-temperature toughness and a preparation method thereof.The polyethylene fuel tank special resin is prepared from 100 parts of ethylene hexene copolymerized polyethylene, 10-16 parts of a modifier, 5-11 parts of a toughening agent, 2-6 parts of a grafting monomer, 1.2-1.5 parts of a second monomer, 0.08-0.2 parts of an initiator, 0.2-0.3 parts of an antioxidant and 0.12-0.18 parts of a light stabilizer, has excellent barrier property and low-temperature toughness, can meet various performance requirements of the polyethylene fuel tank special material, and can be used for producing single-layer and multi-layer automobile fuel tanks; the preparation method is simple in process and easy to operate.

Description

Technical Field

[0001] This invention relates to the field of polymer modification technology, and more specifically, to a polyethylene fuel tank resin with excellent barrier properties and low-temperature toughness, and its preparation method. Background Technology

[0002] With the increasing demand for lightweight vehicles, plastics are being used more and more extensively in automobiles, and the plasticization of fuel tanks is an important direction in modern automotive plastics development. Compared with metal fuel tanks, plastic fuel tanks offer greater freedom in shape design, are lighter, and have better corrosion resistance. Especially in cold regions, they can prevent metal corrosion caused by ice and salt. Moreover, the manufacturing process is simple, efficient, and can be mass-produced, resulting in higher economic benefits. China has become the world's second-largest automobile market, and the processing technology and research on specialized resins for automotive plastic fuel tanks are receiving increasing attention from the industry.

[0003] In the late 1980s, with the introduction of automotive production technology, my country successively imported multiple single-layer plastic fuel tank production lines to supply fuel for joint venture models such as the Shanghai Santana, Guangzhou Peugeot, and FAW Jetta. Since there was no domestically produced resin specifically for automotive plastic fuel tanks at the time, the raw material resin had to be imported. Internationally renowned brands of resin for automotive fuel tanks include: Basell's Lupolen 4261AG, IPQ's GM7746, Tatol's MS201B(N), Pillips' HXM50100, and JPE's HB111R. Among these, Lupolen 4261AG, GM7746, and MS201B(N) are commonly used in Europe, while HXM50100 is mainly used in North America. my country's imported automotive fuel tank resins were primarily Lupolen 4261AG and MS201B(N).

[0004] Currently, the development of specialized resins for automotive fuel tanks in China is relatively lagging. No resins specifically designed for automotive fuel tanks have yet been successfully developed directly on polymerization equipment, leading to a heavy reliance on imports for production. Some products are small-batch blends with inconsistent quality. In response, major domestic petrochemical companies have invested significant resources in developing equipment and products, and some experimental products have been launched. However, in actual testing, low-temperature drop tests are difficult to pass. Furthermore, to ensure the fuel tank's resistance to fuel penetration, manufacturers often incorporate an EVOH layer during blow molding, requiring continuous monitoring of the EVOH layer to prevent discontinuity, making the process complex.

[0005] Currently, there are numerous patents and documents describing the research and application of materials specifically for fuel tanks. For example, Chinese patent CN1796457A discloses a nylon fuel tank for automobiles and motorcycles and its preparation method. The preparation method of the nylon fuel tank for automobiles and motorcycles provided by this patent includes the following steps: 10–49.9 wt% of ε-caprolactam is melt-mixed with a catalyst, toughening agent, defoamer, antioxidant, light stabilizer, or other additives to form component A; the remaining ε-caprolactam is melt-mixed with a co-catalyst to form component B; then, component A and component B are mixed and injected into a fuel tank mold, and formed by rotational reaction using a bidirectional rotary molding machine to obtain the nylon fuel tank. The method of this invention completes toughening modification and product molding in one step, with a simple process, low energy consumption, and excellent barrier properties of the nylon material. The nylon fuel tank still exhibits excellent impact resistance and other mechanical properties at temperatures ranging from -40℃ to 60℃.

[0006] Chinese patent CN102558640A discloses a plastic fuel tank and its preparation method. The raw materials for the plastic fuel tank provided by this invention include the following components and weight percentages: 50-90 parts high-density polyethylene resin, 50-10 parts barrier polymer fiber, and 0-10 parts compatibilizer. Continuous barrier polymer fiber is impregnated with melt high-density polyethylene resin. After cooling, the impregnated continuous barrier polymer fiber is cut into granules of appropriate length. The granules are then fed into a blow molding machine for blow molding to obtain the plastic fuel tank. Compared with the prior art, the plastic fuel tank prepared by this invention has the advantages of good barrier properties, simple process, and low cost.

[0007] Chinese patent CN105419076A discloses a blow molding material for automotive plastic fuel tanks with environmental stress cracking resistance >8000h. It is mainly composed of the following raw materials in parts by weight: 99.5-99.8 parts ethylene-hexene copolymer polyethylene resin, 0.05-0.35 parts antioxidant, 0.03-0.15 parts auxiliary antioxidant, and 0.02-0.06 parts release agent. This blow molding material for automotive plastic fuel tanks exhibits high melt strength, excellent environmental stress cracking resistance and creep resistance, as well as good chemical corrosion resistance, making it suitable for processing and molding single-layer and multi-layer automotive plastic fuel tanks.

[0008] Of the aforementioned patents, CN1796457A discloses a fuel tank made of nylon, and its preparation method is a modification method for nylon material. Nylon requires high processing temperatures, so downstream manufacturers generally do not choose it as their first choice, thus offering little guidance for the market. CN102558640A uses a melt impregnation method, which is complex and requires stringent conditions, making it unsuitable for industrial production. CN105419076A discloses a production method for conventional polyethylene resin, achieving improved resistance to environmental stress cracking and creep resistance through process condition control. However, it does not involve post-processing modification to create a specialized product, and downstream processing still requires traditional processing methods to improve barrier properties. Summary of the Invention

[0009] The purpose of this invention is to provide a polyethylene fuel tank-specific resin with excellent barrier properties and low-temperature toughness, and its preparation method, so as to solve the technical problems in the prior art where polyethylene resin used to prepare fuel tanks is difficult to meet the requirements of low-temperature drop test and requires an internal EVOH layer to ensure the fuel tank's resistance to fuel penetration.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] In a first aspect, the present invention provides a polyethylene fuel tank resin with excellent barrier properties and low-temperature toughness, which is prepared from the following components in parts by weight:

[0012]

[0013] According to some embodiments of the present invention, the density of the ethylene-hexene copolymer polyethylene is 0.944–0.948 g / cm³. 3 The melt index at 190℃ and 21.6kg is 5.5~6.5g / 10min.

[0014] According to some embodiments of the present invention, the modifier includes ethylene-vinyl alcohol copolymer (EVOH).

[0015] According to some embodiments of the present invention, the toughening agent includes POE.

[0016] According to some embodiments of the present invention, the grafting monomer is at least one selected from maleic anhydride (MAH) and its derivatives, acrylic acid and (AA) and its derivatives, methacrylic acid (MMA), unsaturated fatty acids, methylene succinic acid, glycidyl methacrylate (GMA), oleic acid (OA), vinyl acetate (VAC), butyl acrylate (BA), ethyl acrylate (EA), vinylsilane, and unsaturated silane.

[0017] According to some embodiments of the present invention, the second monomer is at least one selected from styrene, acrylamide, vinyl acetate, and acrylate.

[0018] According to some embodiments of the present invention, the second monomer is acrylamide.

[0019] According to some embodiments of the present invention, the initiator is at least one selected from benzoyl peroxide (BPO), dicumyl peroxide (DCP), 2,3-dimethyl-2,3-diphenylbutane (DMDPB), 2,5-di-tert-butylperoxide-2,5-dimethyl-3-acetylene (LPO), and 1,3-di-tert-butylperoxide.

[0020] According to some embodiments of the present invention, the initiator is benzoyl peroxide and dicumyl peroxide.

[0021] According to some embodiments of the present invention, the weight ratio of benzoyl peroxide and dicumyl peroxide is 1:0.8-1.2, for example, it can be 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, etc.

[0022] According to some embodiments of the present invention, the antioxidant includes a primary antioxidant and a secondary antioxidant.

[0023] According to some embodiments of the present invention, the primary antioxidant includes antioxidant 1010 and / or antioxidant 1076.

[0024] According to some embodiments of the present invention, the auxiliary antioxidant includes antioxidant 168 and / or antioxidant 626.

[0025] According to some embodiments of the present invention, the weight ratio of the primary antioxidant to the secondary antioxidant is 1:(1-2).

[0026] According to some embodiments of the present invention, the light stabilizer includes a polymeric high molecular weight hindered amine light stabilizer.

[0027] In a second aspect, the present invention provides a method for preparing the polyethylene fuel tank resin described in the first aspect, comprising:

[0028] S1. The toughening agent is mixed with the grafted monomer, initiator and second monomer, melt-extruded, cooled, dried and pelletized and screened to obtain modified granules;

[0029] S2. The modified granules, ethylene-hexene copolymer polyethylene, modifier, antioxidant, and light stabilizer are mixed, melt-extruded, cooled, dried, pelletized, and sieved to obtain the polyethylene fuel tank special resin.

[0030] According to some embodiments of the present invention, the melt extrusion in step S1 is performed using a single screw extruder.

[0031] According to some embodiments of the present invention, the temperature of the single screw extruder from feeding to the die head is set sequentially as follows: 100-120℃, 120-130℃, 120-130℃, 130-140℃, 130-140℃, and the screw speed is 80-100 r / min.

[0032] According to some embodiments of the present invention, the melt extrusion in step S2 is performed using a twin-screw extruder.

[0033] According to some embodiments of the present invention, the temperature of the twin-screw extruder from feeding to the die head is set sequentially as follows: 165-175℃, 170-180℃, 180-185℃, 185-190℃, 190-195℃, 190-195℃, 185-190℃, 185-190℃, 185-190℃, and the screw speed is 100-250 r / min.

[0034] The beneficial effects of this invention are at least as follows:

[0035] The polyethylene fuel tank resin provided by this invention has excellent barrier properties and low-temperature toughness, which can meet the various performance requirements of polyethylene fuel tank materials and can be used to produce single-layer and multi-layer automotive fuel tanks; the preparation method is simple and easy to operate.

[0036] The polyethylene fuel tank resin provided by this invention has excellent barrier properties and low-temperature toughness, with environmental stress cracking resistance (F50) ≥ 5000h, fuel permeability resistance ≤ 10g / 24h, and simply supported beam low-temperature impact strength (-40℃) ≥ 14KJ / m. 2 With a molecular weight distribution width ≥20, tensile yield stress ≥21MPa, and flexural modulus ≥1000MPa, it can meet the performance requirements of automotive fuel tanks. Detailed Implementation

[0037] To make the technical problem to be solved, the technical solution, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely for illustrating this patent and do not limit the scope of protection of this invention in any way.

[0038] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the reagents used in the following embodiments are conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments can all be obtained commercially or by existing methods; unless otherwise specified, the reagent dosages are those used in routine experimental operations; unless otherwise specified, the experimental methods are conventional methods.

[0039] In the various embodiments and comparative examples of the present invention, the performance data were tested according to the following test methods:

[0040] Tensile yield stress: GB / T 1040.2-2006.

[0041] Flexural modulus of elasticity: GB / T 9341-2008.

[0042] Low-temperature impact strength of simply supported beams: GB / T 1043.1-2008.

[0043] Environmental stress cracking resistance: GB / T 1842-2008.

[0044] Oil permeability resistance: GB18296-2019.

[0045] Molecular weight distribution width: The measurement system was a PL-GPC 220 high-performance liquid chromatograph manufactured by Polymer Laboratories, UK. The chromatographic column was three tandem Plgel 10μm MIXED-B columns. The solvent and mobile phase were both 1,2,4-trichlorobenzene (containing 0.025% antioxidant 2,6-dibutyl-p-cresol). The column temperature was 150℃, the flow rate was 1.0 ml / min, and a narrow-distribution polystyrene standard was used for universal calibration.

[0046] The materials used in the various embodiments and comparative examples of the present invention are as follows:

[0047] Ethylene-hexene copolymerized polyethylene: density 0.944–0.948 g / cm³ 3 The melt flow index is 5.5–6.5 g / 10 min (test conditions: 190℃, 21.6 kg weight).

[0048] EVOH: Japan Synthetic Chemicals DC3203F.

[0049] POE: ExxonMobil POE 9061.

[0050] Hindered amine light stabilizers: BASF Light Stabilizer 2020.

[0051] Example 1

[0052] (1) Place 14 portions of EVOH in a forced-air drying oven and dry at 80°C for 12 hours before use;

[0053] (2) 9 parts of POE, 6 parts of grafted monomer GMA, 0.08 parts of initiator DCP, 0.08 parts of initiator BPO, and 1.4 parts of second monomer styrene were mixed evenly in a certain proportion and melt-grafted on a single screw extruder. The temperature of the extruder from feeding to the die head was set to 110℃, 125℃, 125℃, 135℃, and 135℃. The screw speed was 90r / min. After the extruded sample was cooled, dried, granulated and screened, modified granules were obtained.

[0054] (3) The modified granules were mixed evenly with 100 parts of ethylene-hexene copolymer polyethylene, dried EVOH, 0.04 parts of primary antioxidant 1010, 0.08 parts of primary antioxidant 1076, 0.08 parts of auxiliary antioxidant 168, 0.04 parts of auxiliary antioxidant 626, and 0.16 parts of hindered amine light stabilizer. The mixture was then melt-blended using a twin-screw extruder under the following processing conditions: 170℃, 175℃, 183℃, 187℃, 193℃, 193℃, 188℃, 188℃, 188℃, and 188℃. The screw speed was 200 r / min. After extruding the sample, the sample was cooled, dried, granulated, and sieved to obtain the special resin for polyethylene fuel tanks.

[0055] Example 2

[0056] (1) Place 10 portions of EVOH in a forced-air drying oven and dry at 80°C for 12 hours before use;

[0057] (2) Mix 6 parts of POE with 4 parts of grafted monomer MAH, 0.04 parts of initiator DCP, 0.04 parts of initiator BPO and 1.2 parts of second monomer styrene in a certain proportion, and perform melt grafting on a single screw extruder. The temperature of the extruder from feeding to the die head is set to 100℃, 120℃, 120℃, 130℃, 130℃, and the screw speed is 100r / min. After the extruded sample is cooled, dried, granulated and screened, modified granules are obtained.

[0058] (3) The modified granules are mixed evenly with 100 parts of ethylene-hexene copolymer polyethylene, dried EVOH, 0.04 parts of primary antioxidant 1010, 0.04 parts of primary antioxidant 1076, 0.08 parts of auxiliary antioxidant 168, 0.04 parts of auxiliary antioxidant 626, and 0.12 parts of hindered amine light stabilizer. The mixture is then melt-blended using a twin-screw extruder under the following processing conditions: 165℃, 170℃, 180℃, 185℃, 190℃, 190℃, 185℃, 185℃, 185℃, 185℃, and screw speed of 150 r / min. After extruding the sample, the sample is cooled, dried, granulated, and sieved to obtain the special resin for polyethylene fuel tanks.

[0059] Example 3

[0060] (1) Place 16 portions of EVOH in a forced-air drying oven and dry at 80°C for 12 hours before use;

[0061] (2) Mix 10 parts of POE with 2 parts of grafted monomer MMA, 0.1 parts of initiator DCP, 0.1 parts of initiator BPO and 1.5 parts of second monomer styrene in a certain proportion, and perform melt grafting on a single screw extruder. The temperature of the extruder from feeding to the die head is set to 120℃, 130℃, 130℃, 140℃, and 140℃. The screw speed is 80 r / min. After the extruded sample is cooled, dried, granulated and screened, modified granules are obtained.

[0062] (3) The modified granules are mixed evenly with 100 parts of ethylene-hexene copolymer polyethylene, dried EVOH, 0.04 parts of primary antioxidant 1010, 0.04 parts of primary antioxidant 1076, 0.08 parts of auxiliary antioxidant 168, 0.08 parts of auxiliary antioxidant 626, and 0.18 parts of hindered amine light stabilizer. The mixture is then melt-blended using a twin-screw extruder under the following processing conditions: 175℃, 180℃, 185℃, 190℃, 195℃, 195℃, 190℃, 190℃, 190℃, and 190℃. The screw speed is 250 r / min. After extruding the sample, the sample is cooled, dried, granulated, and sieved to obtain the special resin for polyethylene fuel tanks.

[0063] Example 4

[0064] The preparation method of the special resin for polyethylene fuel tanks is the same as in Example 1, except that the second monomer is replaced by vinyl acetate instead of styrene.

[0065] Example 5

[0066] The preparation method of the special resin for polyethylene fuel tanks is the same as in Example 1, except that the second monomer is replaced by acrylamide instead of styrene.

[0067] Example 6

[0068] The preparation method of the special resin for polyethylene fuel tanks is the same as in Example 1, except that 0.08 parts of initiator DCP and 0.08 parts of initiator BPO are replaced with 0.16 parts of initiator DCP.

[0069] Example 7

[0070] The preparation method of the special resin for polyethylene fuel tanks is the same as in Example 1, except that 0.08 parts of initiator DCP and 0.08 parts of initiator BPO are replaced with 0.16 parts of initiator BPO.

[0071] Example 8

[0072] The preparation method of the special resin for polyethylene fuel tanks is the same as in Example 1, except that 0.08 parts of initiator DCP and 0.08 parts of initiator BPO are replaced with 0.16 parts of initiator DMDPB.

[0073] Example 9

[0074] The preparation method of the special resin for polyethylene fuel tanks is the same as in Example 1, except that 0.08 parts of initiator DCP and 0.08 parts of initiator BPO are replaced with 0.08 parts of initiator DCP and 0.08 parts of initiator DMDPB.

[0075] Example 10

[0076] The preparation method of the special resin for polyethylene fuel tanks is the same as in Example 1, except that 0.08 parts of initiator DCP and 0.08 parts of initiator BPO are replaced with 0.08 parts of initiator DMDPB and 0.08 parts of initiator BPO.

[0077] Comparative Example 1

[0078] (1) Place 14 portions of EVOH in a forced-air drying oven and dry at 80°C for 12 hours before use;

[0079] (2) Mix 100 parts of ethylene-hexene copolymer polyethylene, dried EVOH, 0.04 parts of primary antioxidant 1010, 0.08 parts of primary antioxidant 1076, 0.08 parts of secondary antioxidant 168, 0.04 parts of secondary antioxidant 626, and 0.16 parts of hindered amine light stabilizer evenly, and melt blend them through a twin-screw extruder. The processing conditions are: 170℃, 175℃, 183℃, 187℃, 193℃, 193℃, 188℃, 188℃, 188℃, 188℃, screw speed 200r / min. After extruding the sample, cool, dry, pelletize and screen to obtain polyethylene fuel tank special resin.

[0080] Comparative Example 2

[0081] The preparation method of the special resin for polyethylene fuel tanks is the same as in Example 1, except that EVOH is not added.

[0082] The properties of the polyethylene fuel tank resins provided in each embodiment and comparative example were tested, and the results are shown in the table below:

[0083]

[0084] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A polyethylene fuel tank resin with excellent barrier properties and low-temperature toughness, characterized in that, It is prepared from the following components in parts by weight: 100 parts of ethylene-hexene copolymerized polyethylene; 10-16 parts of modifier; 5-11 parts toughening agent; 2-6 parts of graft monomer; The second monomer is 1.2 to 1.5 parts; Initiator 0.08–0.2 parts; Antioxidant 0.2-0.3 parts; Light stabilizer 0.12–0.18 parts; The preparation method of the polyethylene fuel tank special resin includes: S1. The toughening agent is mixed with the grafted monomer, initiator and second monomer, melt extruded, cooled, dried and pelletized and screened to obtain modified granules; S2. The modified granules, ethylene-hexene copolymer polyethylene, modifier, antioxidant, and light stabilizer are mixed, melt-extruded, cooled, dried, pelletized, and sieved to obtain the polyethylene fuel tank special resin. The toughening agent includes POE; The grafting monomer is at least one of maleic anhydride and its derivatives, acrylic acid and its derivatives, methacrylic acid, unsaturated fatty acids, methylene succinic acid, glycidyl methacrylate, oleic acid, vinyl acetate, butyl acrylate, ethyl acrylate, vinylsilane, and unsaturated silane. The second monomer is acrylamide.

2. The polyethylene fuel tank resin according to claim 1, characterized in that, The density of the ethylene-hexene copolymer polyethylene is 0.944–0.948 g / cm³. 3 The melt index at 190℃ and 21.6kg is 5.5~6.5g / 10min.

3. The polyethylene fuel tank resin according to claim 1 or 2, characterized in that, The modifier includes an ethylene-vinyl alcohol copolymer.

4. The polyethylene fuel tank resin according to claim 1 or 2, characterized in that, The initiator is at least one of benzoyl peroxide, dicumyl peroxide, 2,3-dimethyl-2,3-diphenylbutane, 2,5-di-tert-butylperoxide-2,5-dimethyl-3-acetylene, and 1,3-di-tert-butylperoxide.

5. The polyethylene fuel tank resin according to claim 4, characterized in that, The initiator is benzoyl peroxide and dicumyl peroxide.

6. The polyethylene fuel tank resin according to claim 5, characterized in that, The weight ratio of benzoyl peroxide to dicumyl peroxide is 1:0.8-1.

2.

7. The polyethylene fuel tank resin according to claim 1 or 2, characterized in that, The antioxidants include primary antioxidants and secondary antioxidants; And / or, light stabilizers include polymeric high molecular weight hindered amine light stabilizers.

8. The polyethylene fuel tank resin according to claim 7, characterized in that, The primary antioxidants include antioxidant 1010 and / or antioxidant 1076. And / or the auxiliary antioxidants include antioxidant 168 and / or antioxidant 626, And / or the weight ratio of the primary antioxidant to the secondary antioxidant is 1:(1-2).

9. A method for preparing the polyethylene fuel tank resin according to any one of claims 1-8, characterized in that, include: S1. The toughening agent is mixed with the grafted monomer, initiator and second monomer, melt extruded, cooled, dried and pelletized and screened to obtain modified granules; S2. The modified granules, ethylene-hexene copolymer polyethylene, modifier, antioxidant, and light stabilizer are mixed, melt-extruded, cooled, dried, pelletized, and sieved to obtain the polyethylene fuel tank special resin.

10. The preparation method according to claim 9, characterized in that, The melt extrusion in step S1 is performed using a single-screw extruder; And / or, the melt extrusion in step S2 is performed using a twin-screw extruder.

11. The preparation method according to claim 10, characterized in that, The temperature of the single-screw extruder from feeding to the die head is set sequentially as follows: 100-120℃, 120-130℃, 120-130℃, 130-140℃, 130-140℃, and the screw speed is 80-100 r / min; And / or, the temperature of the twin-screw extruder from feeding to the die head is set sequentially as follows: 165-175℃, 170-180℃, 180-185℃, 185-190℃, 190-195℃, 190-195℃, 185-190℃, 185-190℃, 185-190℃, 185-190℃, and the screw speed is 100-250 r / min.

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