A nylon composition having excellent barrier properties and a method for producing the same

Abstract

This invention discloses a nylon composition with excellent barrier properties and its preparation method. The nylon composition with excellent barrier properties is prepared by weight of the following components: 80-100 parts of lactam monomer, 0.1-2 parts of catalyst, 0.1-2 parts of activator, 1-8 parts of fluorinated graphene, and 0.2-2 parts of antioxidant. The preparation method includes the following steps: (1) adding 1-8 parts of fluorinated graphene, 0.2-2 parts of antioxidant, 80-100 parts of lactam monomer, and 0.1-2 parts of catalyst to a reactor, heating to 125-150℃, and removing water under negative pressure (gauge pressure 0 to -0.1MPa) for 5-120 min; (2) maintaining the temperature, restoring normal pressure, adding 0.1-2 parts of activator, stirring evenly, and then casting into a mold at 150-190℃. After curing for 5-60 min, the product is obtained. An electric field with an electric field strength of 5-10 kV / m is set around the mold. The product of this invention can be widely used in applications where fuel tanks, fuel lines, and other applications require high fuel barrier performance.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, specifically relating to a nylon composition with excellent barrier properties and its preparation method. Background Technology

[0002] The fuel tank is a core component of the entire fuel system. Gasoline is a volatile gas; as the temperature rises, the pressure inside the fuel tank increases, requiring a valve to release the gasoline into the carbon canister. Conversely, when the temperature inside the fuel tank decreases, the gasoline vapor cools, creating a negative pressure inside the tank. The valve must then replenish the vapor to protect the fuel tank and fuel pump. Plastic has advantages such as low density, ease of molding, and corrosion resistance. Using plastic to manufacture fuel tanks allows for greater design flexibility, making full use of the vehicle's interior space and placing them in the safest location in the event of a collision. Furthermore, plastic fuel tanks are less prone to fire and explosion during friction and impact. In addition, plastic fuel tanks are cheaper to manufacture, and the equipment costs are lower than for metal fuel tanks.

[0003] Cast nylon is an engineering plastic formed through anionic polymerization under normal pressure by pouring molten caprolactam monomer and a catalyst into molds of various shapes. Cast nylon has a molecular weight of 70,000-100,000, three times that of ordinary nylon 6 and nylon 66, resulting in significantly better overall mechanical properties than other nylon materials. It possesses excellent physical and mechanical properties, including high strength, rigidity, and toughness, as well as good wear resistance and chemical stability. Furthermore, cast nylon has low water absorption, good dimensional stability, and is self-extinguishing and can withstand continuous heat up to 100°C. The production process of cast nylon is relatively simple, involving direct polymerization through molds, requiring minimal equipment investment and making it suitable for manufacturing large machine parts. This material performs exceptionally well in industrial applications, particularly those demanding high strength and wear resistance.

[0004] Although cast nylon has good barrier properties against gasoline, its barrier properties against gasoline need to be further enhanced if it is used as a fuel tank material. Summary of the Invention

[0005] In view of this, the present invention needs to provide a nylon composition with excellent barrier properties and a method for preparing the same. The preparation method is simple, the product has excellent barrier properties against gasoline, and good mechanical properties.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a nylon composition with excellent barrier properties, prepared from the following components in parts by weight: 80-100 parts lactam monomer, 0.1-2 parts catalyst, 0.1-2 parts activator, 1-8 parts fluorinated graphene, and 0.2-2 parts...

[0008] Antioxidants.

[0009] Preferably, the lactam monomer is selected from at least one of octyllactam, caprolactam, nonyllactam, heptanolactam, decanolactam, dodecalactam, and undecyllactam.

[0010] In this invention, the catalyst and activator can be conventionally selected in the art. They will not be described in detail here. In some exemplary embodiments of this invention, the catalyst is one of sodium caprolactam and sodium hydroxide; the activator is one of hexamethylene diisocyanate and 2,4-toluene diisocyanate (TDI).

[0011] In a further embodiment, the fluorinated graphene has a fluorine-to-carbon ratio of ≥1.0, a bulk density of ≥0.02 g / cm³, and a particle size D50 of 5-10 μm. Fluorinated graphene is a novel functional material with very low surface free energy, and its suitable particle size allows for good dispersion in molten lactam monomers.

[0012] The antioxidant of this invention is at least one of hindered amines, hindered phenols, thiolated antioxidants, and phosphite antioxidants;

[0013] Preferably, the antioxidant is at least one of antioxidant 1010, antioxidant 1098, antioxidant 1076, and antioxidant 168.

[0014] This invention also provides a method for preparing a nylon composition with excellent barrier properties, comprising the following steps:

[0015] (1) Add 1-8 parts of fluorinated graphene, 0.2-2 parts of antioxidant, 80-100 parts of lactam monomer and 0.1-2 parts of catalyst to the reactor, heat to 125-150℃, and remove water under negative pressure (gauge pressure 0 to -0.1MPa) for 5-120 minutes;

[0016] (2) Maintain the temperature, restore normal pressure, add 0.1-2 parts of activator, stir evenly, and then pour into a mold at 150-190℃. After curing for 5-60 minutes, the product is obtained. An electric field with an electric field strength of 5-10 kV / m is set around the mold.

[0017] Beneficial effects:

[0018] Through extensive experimentation, this invention unexpectedly discovered that the addition of fluorinated graphene to cast nylon significantly enhances its gasoline barrier properties. This is likely because, under the influence of an electric field, fluorinated graphene rapidly aligns itself with the field, allowing the curled portions to spread out to varying degrees within the plane. In three-dimensional space, fluorinated graphene can be layered, ultimately not only significantly improving the barrier properties of the nylon composition but also enhancing its mechanical properties.

[0019] The product of this invention can be widely used in applications where fuel tanks, fuel lines, and other applications require high fuel barrier performance. Detailed Implementation

[0020] Unless otherwise specified, all raw materials used in this invention are commercially available or prepared according to conventional methods in the art. Unless otherwise defined or stated, all technical and scientific terms used herein have the same meaning as are familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. Other aspects of this invention will be apparent to those skilled in the art from the disclosure herein. The invention is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0021] Unless otherwise specified, experimental methods in the following examples are generally performed according to national standards. If no corresponding national standard exists, general international standards, standard conditions, or conditions recommended by the manufacturer are followed. Unless otherwise stated, all parts are parts by weight, and all percentages are weight percentages.

[0022] It should be noted that those skilled in the art can make various changes and improvements without departing from the concept of this invention. These all fall within the scope of protection of this invention.

[0023] In the following examples and comparative examples, some raw material specifications and sources are described, but not limited to these materials:

[0024] Dodecyl lactam, caprolactam, industrial grade, BASF, Germany.

[0025] Sodium hydroxide, analytical grade, purity ≥98%, Yantai Shuangshuang Chemical Co., Ltd.

[0026] Sodium caprolactam, analytical grade, purity ≥98%, BASF, Germany.

[0027] Hexamethylene diisocyanate, analytical grade, purity ≥99%, purchased from Shandong Haoshun Chemical Co., Ltd.

[0028] 2,4-Toluene diisocyanate (TDI), analytical grade, purity ≥98%, Shandong Xiya Chemical Co., Ltd.

[0029] Fluorinated graphene, grade CF-X10; particle size D50: 1μm, 5μm, 10μm, 20μm, Cenfu (Shanghai) Fine Chemicals Co., Ltd.

[0030] The antioxidants used are all a mixture of antioxidant 1010 and antioxidant 168 in a 1:1 weight ratio, supplied by Cytec Chemicals, USA.

[0031] Example 1

[0032] (1) Add 2 parts of fluorinated graphene (particle size D50 is 5μm), 0.5 parts of antioxidant, 80 parts of dodecyl lactam monomer, and 0.1 parts of catalyst sodium hydroxide to the reactor, heat to 120℃, and remove water under negative pressure (gauge pressure -0.1MPa) for 60min;

[0033] (2) Maintain the temperature, restore normal pressure, add 0.1 parts of activator 2,4-toluene diisocyanate (TDI), stir evenly, and then pour into a mold at 160℃. After curing for 60 minutes, the product is obtained. An electric field with an electric field strength of 5 kV / m is set around the mold.

[0034] Example 2

[0035] (1) Add 8 parts of fluorinated graphene (particle size D50 is 10μm), 2 parts of antioxidant, 100 parts of caprolactam monomer, and 2 parts of catalyst sodium caprolactam to the reactor, heat to 150℃, and remove water under negative pressure (gauge pressure -0.05MPa) for 8 minutes.

[0036] (2) Maintain the temperature, restore normal pressure, add 1.5 parts of activator hexamethylene diisocyanate, stir evenly, and then pour into a mold at 190℃. After curing for 5 minutes, the product is obtained. An electric field with an electric field strength of 10 kV / m is set around the mold.

[0037] Example 3

[0038] (1) Add 6 parts of fluorinated graphene (particle size D50 is 5μm), 1 part of antioxidant, 85 parts of caprolactam monomer, and 0.8 parts of catalyst sodium caprolactam to the reactor, heat to 140℃, and remove water under negative pressure (gauge pressure 0 to -0.1MPa) for 15min.

[0039] (2) Maintain the temperature, restore normal pressure, add 1 part of activator hexamethylene diisocyanate, stir evenly, and then pour into a mold at 180℃. After curing for 15 minutes, the product is obtained. An electric field with an electric field strength of 8 kV / m is set around the mold.

[0040] Example 4

[0041] (1) Add 4 parts of fluorinated graphene (particle size D50 is 5μm), 1 part of antioxidant, 87 parts of caprolactam monomer, and 0.8 parts of catalyst sodium caprolactam to the reactor, heat to 140℃, and remove water under negative pressure (gauge pressure 0 to -0.1MPa) for 15min;

[0042] (2) Maintain the temperature, restore normal pressure, add 1 part of activator hexamethylene diisocyanate, stir evenly, and then pour into a mold at 180℃. After curing for 15 minutes, the product is obtained. An electric field with an electric field strength of 8 kV / m is set around the mold.

[0043] Example 5

[0044] (1) Add 8 parts of fluorinated graphene (particle size D50 is 5μm), 1 part of antioxidant, 83 parts of caprolactam monomer, and 0.8 parts of catalyst sodium caprolactam to the reactor, heat to 140℃, and remove water under negative pressure (gauge pressure 0 to -0.1MPa) for 15min.

[0045] (2) Maintain the temperature, restore normal pressure, add 1 part of activator hexamethylene diisocyanate, stir evenly, and then pour into a mold at 180℃. After curing for 15 minutes, the product is obtained. An electric field with an electric field strength of 8 kV / m is set around the mold.

[0046] Example 6

[0047] (1) Add 6 parts of fluorinated graphene (particle size D50 is 5μm), 1 part of antioxidant, 85 parts of caprolactam monomer, and 0.8 parts of catalyst sodium caprolactam to the reactor, heat to 140℃, and remove water under negative pressure (gauge pressure 0 to -0.1MPa) for 15min.

[0048] (2) Maintain the temperature, restore normal pressure, add 1 part of activator hexamethylene diisocyanate, stir evenly, and then pour into a mold at 180℃. After curing for 15 minutes, the product is obtained. An electric field with an electric field strength of 6 kV / m is set around the mold.

[0049] Example 7

[0050] (1) Add 6 parts of fluorinated graphene (particle size D50 is 5μm), 1 part of antioxidant, 85 parts of caprolactam monomer, and 0.8 parts of catalyst sodium caprolactam to the reactor, heat to 140℃, and remove water under negative pressure (gauge pressure 0 to -0.1MPa) for 15min.

[0051] (2) Maintain the temperature, restore normal pressure, add 1 part of activator hexamethylene diisocyanate, stir evenly, and then pour into a mold at 180℃. After curing for 15 minutes, the product is obtained. An electric field with an electric field strength of 10 kV / m is set around the mold.

[0052] Comparative Example 1

[0053] (1) Add 6 parts of graphene oxide (particle size D50 is 5μm), 1 part of antioxidant, 85 parts of caprolactam monomer, and 0.8 parts of catalyst sodium caprolactam to the reactor, heat to 140℃, and remove water under negative pressure (gauge pressure 0 to -0.1MPa) for 15min.

[0054] (2) Maintain the temperature, restore normal pressure, add 1 part of activator hexamethylene diisocyanate, stir evenly, and then pour into a mold at 180℃. After curing for 15 minutes, the product is obtained. An electric field with an electric field strength of 8 kV / m is set around the mold.

[0055] Comparative Example 2

[0056] (1) Add 6 parts of fluorinated graphene (particle size D50 is 5μm), 1 part of antioxidant, 85 parts of caprolactam monomer, and 0.8 parts of catalyst sodium caprolactam to the reactor, heat to 140℃, and remove water under negative pressure (gauge pressure 0 to -0.1MPa) for 15min.

[0057] (2) Maintain the temperature, restore normal pressure, add 1 part of activator hexamethylene diisocyanate, stir evenly and then pour into a mold at 180°C. After curing for 15 minutes, the product is obtained.

[0058] Comparative Example 3

[0059] (1) Add 6 parts of fluorinated graphene (particle size D50 is 5μm), 1 part of antioxidant, 85 parts of caprolactam monomer, and 0.8 parts of catalyst sodium caprolactam to the reactor, heat to 140℃, and remove water under negative pressure (gauge pressure 0 to -0.1MPa) for 15min.

[0060] (2) Maintain the temperature, restore normal pressure, add 1 part of activator hexamethylene diisocyanate, stir evenly, and then pour into a mold at 180℃. After curing for 15 minutes, the product is obtained. An electric field with an electric field strength of 2kv / m is set around the mold.

[0061] Comparative Example 4

[0062] (1) Add 6 parts of fluorinated graphene (particle size D50 is 5μm), 1 part of antioxidant, 85 parts of caprolactam monomer, and 0.8 parts of catalyst sodium caprolactam to the reactor, heat to 140℃, and remove water under negative pressure (gauge pressure 0 to -0.1MPa) for 15min.

[0063] (2) Maintain the temperature, restore normal pressure, add 1 part of activator hexamethylene diisocyanate, stir evenly, and then pour into a mold at 180℃. After curing for 15 minutes, the product is obtained. An electric field with an electric field strength of 15kv / m is set around the mold.

[0064] Comparative Example 5

[0065] (1) Add 6 parts of fluorinated graphene (particle size D50 of 1 μm), 1 part of antioxidant, 85 parts of caprolactam monomer, and 0.8 parts of catalyst sodium caprolactam to the reactor, heat to 140℃, and remove water under negative pressure (gauge pressure 0 to -0.1 MPa) for 15 min; (2) Maintain the temperature, restore normal pressure, add 1 part of activator hexamethylene diisocyanate, stir evenly, and then cast into a mold at 180℃. After curing for 15 min, the product is obtained. An electric field with an electric field strength of 8 kV / m is set around the mold.

[0066] Comparative Example 6

[0067] (1) Add 6 parts of fluorinated graphene (particle size D50 of 20 μm), 1 part of antioxidant, 85 parts of caprolactam monomer, and 0.8 parts of catalyst sodium caprolactam to the reactor, heat to 140℃, and remove water under negative pressure (gauge pressure 0 to -0.1 MPa) for 15 min; (2) Maintain the temperature, restore normal pressure, add 1 part of activator hexamethylene diisocyanate, stir evenly, and then cast into a mold at 180℃. After curing for 15 min, the product is obtained. An electric field with an electric field strength of 8 kV / m is set around the mold.

[0068] The products obtained in each embodiment and comparative example were subjected to relevant performance tests, and the results are shown in Table 1.

[0069] Table 1 Performance Test Results

[0070]

[0071] Note: Table 1 shows the mechanical test strips made from nylon compositions with excellent barrier properties using ASTM standard injection molding. The dimensions of the strips (length × width × thickness) are as follows:

[0072] Tensile strength: The specimen (dumbbell shape) is 170mm×13mm×3.2mm, tested according to ASTM D 638 standard, with a tensile speed of 5mm / min;

[0073] Notched impact strength: The specimen is 127mm×13mm×3.2mm, with a V-notch and a notch depth of 1 / 5. The notched impact strength is tested according to ASTM D 6110-2018 standard.

[0074] Gasoline permeability coefficient: Tested according to GB / T 1038-2022 standard.

[0075] In this invention, a suitable electric field strength enables fluorinated graphene to rapidly align with the electric field direction, allowing the curled portions to lay flat in the plane to varying degrees. In three-dimensional space, fluorinated graphene can be stacked layer by layer, ultimately significantly improving not only the barrier properties of the nylon composition but also its mechanical properties.

[0076] When the electric field strength is low, only a portion of the fluorinated graphene can spread out in a plane, resulting in limited spread and varying degrees of improvement in tensile strength, impact strength, and gasoline barrier properties. This trend becomes more pronounced when the electric field strength is below 5 kV / m. When the electric field strength is high, the fluorinated graphene may partially tear during planar spreading, forming numerous small, curled fragments, or it may fail to spread smoothly, remaining curled. Its tensile strength, impact strength, and gasoline barrier properties are all affected to varying degrees. These trends become even more pronounced when the electric field strength exceeds 10 kV / m.

[0077] Fluorinated graphene particles that are too small will agglomerate, a problem that cannot be solved even with the application of an electric field. If the particle size is too small or too large, the fluorinated graphene will struggle to spread properly within a plane, resulting in very limited enhancement to the mechanical and barrier properties of the composition.

[0078] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A nylon composition with excellent barrier properties, prepared from the following components in parts by weight: 80-100 parts lactam monomer, 0.1-2 parts catalyst, 0.1-2 parts activator, 1-8 parts fluorinated graphene, and 0.2-2 parts antioxidant.

2. The nylon composition excellent in barrier properties according to Claim 1, wherein The lactam monomer is selected from at least one of octyllactam, caprolactam, nonanolactam, heptanlactam, decanolactam, dodecalactam, and undecanolactam.

3. The nylon composition excellent in barrier properties according to Claim 1, wherein the nylon composition is a nylon 6 composition. The catalyst is one of sodium caprolactam and sodium hydroxide.

4. The nylon composition excellent in barrier properties according to Claim 1, wherein The activator is one of hexamethylene diisocyanate or 2,4-toluene diisocyanate (TDI).

5. The nylon composition excellent in barrier properties according to Claim 1, wherein the nylon composition is a nylon 6 composition. The fluorinated graphene has a fluorine-to-carbon ratio of ≥1.0; a bulk density of ≥0.02 g / cm3; and a particle size D50 of 5-10 μm.

6. The nylon composition having excellent barrier properties according to Claim 1, wherein the polyamide resin is a polyamide resin having a melting point of 220°C or higher. The antioxidant is at least one of hindered amines, hindered phenols, thiolated antioxidants, and phosphite antioxidants.

7. The nylon composition having excellent barrier properties according to Claim 1, wherein the nylon composition is a nylon 6,6 composition. The antioxidant is at least one of antioxidant 1010, antioxidant 1098, antioxidant 1076, and antioxidant 168.

8. A method for producing a nylon composition having excellent barrier properties, characterized by, Includes the following steps: (1) Add 1-8 parts of fluorinated graphene, 0.2-2 parts of antioxidant, 80-100 parts of lactam monomer and 0.1-2 parts of catalyst to the reactor, heat to 125-150℃, and remove water under negative pressure (gauge pressure 0 to -0.1MPa) for 5-120 minutes; (2) Maintain the temperature, restore normal pressure, add 0.1-2 parts of activator, stir evenly, and then pour into a mold at 150-190℃. After curing for 5-60 minutes, the product is obtained. An electric field with an electric field strength of 5-10 kV / m is set around the mold.

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