Polyethylene fuel tank special resin with excellent barrier property and low-temperature toughness and preparation method thereof

Abstract

The invention 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 special resin for the polyethylene fuel tank is prepared from 100 parts of ethylene-hexene copolymerized polyethylene, 10 to 16 parts of a modifier, 5 to 11 parts of a flexibilizer, 2 to 6 parts of a grafting monomer, 1.2 to 1.5 parts of a second monomer, 0.08 to 0.2 part of an initiator, 0.2 to 0.3 part of an antioxidant and 0.12 to 0.18 part of a light stabilizer, and has excellent barrier property and low-temperature toughness; various performance requirements of the polyethylene fuel tank special material can be met, and the polyethylene fuel tank special material can be used for producing single-layer and multi-layer automobile fuel tanks; the preparation method is simple in process and convenient to operate.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer modification, and more particularly to a polyethylene fuel tank special resin having excellent barrier properties and low-temperature toughness and a preparation method thereof. Background Art

[0002] With the requirement of lightweight automobiles, plastics are increasingly used in automobiles, and the plasticization of fuel tanks is an important direction of modern automobile plasticization. Compared with metal fuel tanks, automobile plastic fuel tanks have greater freedom in shape design, lighter weight, and better corrosion resistance, especially in cold areas, which can prevent metal corrosion caused by ice and salt. In addition, the production process is simple, efficient, and can be mass-produced, with high economic benefits. China has become the world's second largest automobile market, and the processing technology of automobile plastic fuel tanks and the research on special resins are increasingly valued by the industry.

[0003] In the late 1980s, with the introduction of production technology in the automotive industry, my country introduced a number of single-layer plastic fuel tank production lines in order to provide supporting joint venture models such as Shanghai "Santana", Guangzhou "Peugeot", and FAW "Jetta". Since there was no special resin for automobile plastic fuel tanks in China at that time, the raw resin needed to be imported from abroad. The internationally well-known special resins for automobile fuel tanks are mainly: Lupolen 4261AG of Basell, GM7746 of IPQ, MS201B (N) of Tatol, HXM50100 of Pillips, HB111R of Japan JPE, etc. Among them, Lupolen 4261AG, GM7746, and MS201B (N) are commonly used in Europe, and HXM50100 is mainly used in North America. my country's imported special resins for automobile fuel tanks are mainly Lupolen 4261AG and MS201B (N).

[0004] At present, the development of special resins for automobile fuel tanks in China is still relatively backward. No special resins for automobile fuel tanks have been successfully developed directly on polymerization devices. The output relies heavily on imports, and some are small-batch blended products with no quality assurance. Based on this situation, major domestic petrochemical companies have invested a lot of manpower and material resources in the development of device products, and some experimental products have been launched. However, in the actual testing process, it is difficult to pass the low-temperature drop test. In addition, in order to ensure the fuel tank's resistance to fuel penetration, manufacturers often build in an EVOH layer when blow-molding the fuel tank, and at the same time test the continuity of the EVOH layer to prevent faults, which is a complicated operation.

[0005] At present, there are many introductions in patents and literatures on the development and application of special materials 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 nylon fuel tanks for automobiles and motorcycles provided by the patent includes the following steps: melt-mixing 10-49.9wt% of ε-caprolactam with a catalyst, a toughening agent, a defoamer, an antioxidant, a light stabilizer or other additives to form component A; melt-mixing the remaining ε-caprolactam with a catalyst to form component B; then mixing component A and component B into a fuel tank mold, and rotating reaction molding through a two-way rotary rotational molding machine to obtain a nylon fuel tank. The method of the present invention completes toughening modification and product molding in one step, has a simple process, low energy consumption, and excellent barrier properties of nylon materials. Nylon fuel tanks still have excellent impact resistance and other mechanical properties at -40℃ to 60℃.

[0006] Chinese patent CN102558640A discloses a plastic fuel tank and its preparation method. The raw materials of the plastic fuel tank provided by the invention include the following components and weight percentages: 50-90% high-density polyethylene resin, 50-10% barrier polymer fiber, and 0-10% compatibilizer. The continuous barrier polymer fiber is impregnated with the melt of the high-density polyethylene resin, and then the impregnated continuous barrier polymer fiber is cooled and cut into pellets of corresponding lengths. The pellets are fed into a hollow blow molding machine and blow-molded to obtain a plastic fuel tank. Compared with the prior art, the plastic fuel tank prepared by the present invention has the characteristics of good barrier properties, simple process, and low cost.

[0007] Chinese patent CN105419076A discloses a special blow molding material for automobile plastic fuel tanks resistant to environmental stress cracking, with an environmental stress cracking resistance of >8000h, mainly prepared from the following raw materials by weight: 99.5-99.8 parts of ethylene-hexene copolymer polyethylene resin, 0.05-0.35 parts of antioxidant, 0.03-0.15 parts of auxiliary antioxidant, and 0.02-0.06 parts of mold release agent. The automobile plastic fuel tank blow molding material has high melt strength, excellent environmental stress cracking resistance and creep resistance, and good chemical corrosion resistance, and is suitable for processing and molding of single-layer and multi-layer automobile plastic fuel tanks.

[0008] Among the above patents, CN1796457A discloses a fuel tank made of nylon, and its preparation method is a modification method for nylon materials. The processing temperature of nylon is relatively high, and downstream manufacturers generally do not choose it as the first choice, and its guiding significance to the market is relatively small. The method used in CN102558640A is a melt impregnation method, which is complicated to operate and has relatively harsh conditions, which is not conducive to industrial production. CN105419076A discloses a conventional polyethylene resin production method, which achieves the improvement of environmental stress cracking resistance and creep resistance through the control of process conditions. It does not create a special product through later modification, and still needs to improve the barrier performance through traditional processing methods during downstream processing. Summary of the invention

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

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

[0011] In the first aspect, the present invention provides a polyethylene fuel tank resin having 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 / cm 3 The melt index at 190°C 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 comprises POE.

[0016] According to some embodiments of the present invention, the grafting monomer is at least one of 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), vinyl silane, and unsaturated silane.

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

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

[0019] According to some embodiments of the present invention, the initiator is at least one of benzoyl peroxide (BPO), diisopropyl 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 isopropyl peroxide.

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

[0021] According to some embodiments of the present invention, the weight ratio of benzoyl peroxide to 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 auxiliary 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 according to the first aspect, comprising:

[0028] S1. The toughening agent is mixed with the grafting monomer, the initiator, and the second monomer, melt-extruded, cooled, dried, pelletized and sieved to obtain a modified pellet;

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

[0030] According to some embodiments of the present invention, the melt extrusion in step S1 adopts 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 is set to: 100-120°C, 120-130°C, 120-130°C, 130-140°C, 130-140°C, and the screw speed is 80-100r / min.

[0032] According to some embodiments of the present invention, the melt extrusion in step S2 uses 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 is set to: 165-175°C, 170-180°C, 180-185°C, 185-190°C, 190-195°C, 190-195°C, 185-190°C, 185-190°C, 185-190°C, 185-190°C, and the screw speed is 100-250r / min.

[0034] The beneficial effects of the present invention are at least:

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

[0036] The polyethylene fuel tank resin provided by the present invention has excellent barrier properties and low-temperature toughness, and has an environmental stress cracking resistance (F50) of ≥5000h, fuel permeability resistance of ≤10g / 24h, and a simply supported beam low-temperature impact strength (-40°C) of ≥14KJ / m 2 , molecular weight distribution width ≥ 20, tensile yield stress ≥ 21MPa, bending elastic modulus ≥ 1000MPa, which can meet the performance requirements of automobile fuel tanks. DETAILED DESCRIPTION

[0037] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain this patent in detail and do not limit the scope of protection of the present invention in any way.

[0038] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments and equipment used in the following examples, etc., can all be purchased on the market or can be obtained by existing methods; the reagent amounts, unless otherwise specified, are the reagent amounts used in conventional experimental operations; the experimental methods, unless otherwise specified, are all conventional methods.

[0039] In each embodiment and comparative example of the present invention, each performance data is tested according to the following test method:

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

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

[0042] Simply supported beam low temperature impact strength: GB / T 1043.1-2008.

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

[0044] Fuel penetration resistance: GB18296-2019.

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

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

[0047] Ethylene hexene copolymer polyethylene: density is 0.944~0.948g / cm 3 , the melt index is 5.5-6.5 g / 10 min (test conditions 190°C, 21.6 kg weight).

[0048] EVOH: DC3203F from Japan Synthetic Chemical.

[0049] POE: ExxonMobil POE 9061.

[0050] Hindered Amine Light Stabilizer: BASF Light Stabilizer 2020.

[0051] Example 1

[0052] (1) Place 14 parts 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 grafting monomer GMA, 0.08 parts of initiator DCP, 0.08 parts of initiator BPO, and 1.4 parts of second monomer styrene were mixed uniformly in a certain proportion, and melt grafted on a single-screw extruder. The temperature of the extruder from feeding to the die was set to: 110° C., 125° C., 125° C., 135° C., and 135° C. The screw speed was 90 r / min. The extruded strips were cooled, dried, pelletized, and screened to obtain modified pellets;

[0054] (3) The modified pellets 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, and melt blended through a twin-screw extruder. The processing conditions were: 170°C, 175°C, 183°C, 187°C, 193°C, 193°C, 188°C, 188°C, 188°C, 188°C, and a screw speed of 200 r / min. After extrusion, the specimens were cooled, dried, pelletized, and sieved to obtain polyethylene fuel tank special resin.

[0055] Example 2

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

[0057] (2) 6 parts of POE, 4 parts of grafting monomer MAH, 0.04 parts of initiator DCP, 0.04 parts of initiator BPO, and 1.2 parts of second monomer styrene are mixed uniformly in a certain proportion, and melt grafted on a single-screw extruder. The temperature of the extruder from feeding to the die is set to: 100° C., 120° C., 120° C., 130° C., 130° C., and the screw speed is 100 r / min. The extruded strips are cooled, dried, pelletized, and screened to obtain modified pellets;

[0058] (3) The modified pellets were 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, and melt blended through a twin-screw extruder. The processing conditions were: 165°C, 170°C, 180°C, 185°C, 190°C, 190°C, 185°C, 185°C, 185°C, 185°C, and a screw speed of 150 r / min. After extrusion of the specimen, the specimen was cooled, dried, pelletized, and sieved to obtain a polyethylene fuel tank special resin.

[0059] Example 3

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

[0061] (2) 10 parts of POE, 2 parts of grafting monomer MMA, 0.1 parts of initiator DCP, 0.1 parts of initiator BPO, and 1.5 parts of second monomer styrene are mixed uniformly in a certain proportion, and melt grafted on a single-screw extruder. The temperature of the extruder from feeding to the die is set to: 120° C., 130° C., 130° C., 140° C., 140° C., and the screw speed is 80 r / min. The extruded strips are cooled, dried, pelletized, and screened to obtain modified pellets;

[0062] (3) The modified pellets were 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, and melt blended through a twin-screw extruder. The processing conditions were: 175°C, 180°C, 185°C, 190°C, 195°C, 195°C, 190°C, 190°C, 190°C, 190°C, and a screw speed of 250 r / min. After extrusion of the specimen, the specimen was cooled, dried, pelletized, and sieved to obtain a special polyethylene fuel tank resin.

[0063] Example 4

[0064] The preparation method of the polyethylene fuel tank special resin is similar to that of Example 1, except that the second monomer is replaced by vinyl acetate instead of styrene.

[0065] Example 5

[0066] The preparation method of the polyethylene fuel tank resin is similar to that of 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 similar to that of Example 1, except that 0.08 parts of initiator DCP and 0.08 parts of initiator BPO are replaced by 0.16 parts of initiator DCP.

[0069] Example 7

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

[0071] Example 8

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

[0073] Example 9

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

[0077] Comparative Example 1

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

[0079] (2) 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 are mixed uniformly, and melt blended through a twin-screw extruder. The processing conditions are: 170°C, 175°C, 183°C, 187°C, 193°C, 193°C, 188°C, 188°C, 188°C, 188°C, and 188°C. The screw speed is 200 r / min. After extrusion, the specimen is cooled, dried, pelletized, and sieved to obtain a polyethylene fuel tank special resin.

[0080] Comparative Example 2

[0081] The preparation method of the polyethylene fuel tank special resin is similar to that of Example 1, except that EVOH is not added.

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

[0083]

[0084] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to 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 words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

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:

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

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

4. The polyethylene fuel tank special resin according to any one of claims 1 to 3, characterized in that: The toughening agent includes POE.

5. The polyethylene fuel tank special resin according to any one of claims 1 to 4, characterized in that: 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, vinyl silane, and unsaturated silane.

6. The polyethylene fuel tank special resin according to any one of claims 1 to 5, characterized in that: The second monomer is at least one of styrene, acrylamide, vinyl acetate and acrylate, preferably acrylamide.

7. The polyethylene resin for fuel tank according to any one of claims 1 to 6, characterized in that: The initiator is at least one of benzoyl peroxide, diisopropylbenzene peroxide, 2,3-dimethyl 2,3-diphenylbutane, 2,5-di-tert-butylperoxide-2,5-dimethyl 3-acetylene, and 1,3-di-tert-butylperoxide isopropylbenzene; Preferably, the initiator is benzoyl peroxide and dicumyl peroxide; More preferably, the weight ratio of the benzoyl peroxide to dicumyl peroxide is 1:0.8-1.

2.

8. The polyethylene fuel tank resin according to any one of claims 1 to 7, characterized in that: The antioxidant includes a primary antioxidant and an auxiliary antioxidant; preferably, the primary antioxidant includes antioxidant 1010 and / or antioxidant 1076, and / or the auxiliary antioxidant includes antioxidant 168 and / or antioxidant 626, and / or the weight ratio of the primary antioxidant to the auxiliary antioxidant is 1:(1-2); And / or, the light stabilizer includes a polymeric high molecular weight hindered amine light stabilizer.

9. The method for preparing the polyethylene fuel tank special resin according to any one of claims 1 to 8, characterized in that: include: S1. The toughening agent is mixed with the grafting monomer, the initiator, and the second monomer, melt-extruded, cooled, dried, pelletized and sieved to obtain a modified pellet; S2. The modified pellets, ethylene-hexene copolymer polyethylene, modifier, antioxidant and light stabilizer are mixed, melt-extruded, cooled, dried, pelletized and screened 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 adopts a single screw extruder; preferably, the temperature of the single screw extruder from feeding to the die is set to: 100-120°C, 120-130°C, 120-130°C, 130-140°C, 130-140°C, and the screw speed is 80-100r / min; And / or, the melt extrusion in step S2 adopts a twin-screw extruder; preferably, the temperature of the twin-screw extruder from feeding to the head is set to: 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 100-250r / min.

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