Nylon 12 material with high gas barrier property, nylon pipeline and application

Abstract

The invention discloses a nylon 12 material with high gas barrier property, a nylon pipeline and application. The nylon 12 material is prepared from the following raw materials in percentage by weight: 76.0%-90.3% of nylon 12; 0.1 to 0.8 percent of laurolactam; 8%-20% of a grafting toughening agent; 0.1%-1.0% of a lubricant; 0.5-1.2% of an antioxidant and 1-2% of other processing aids. The nylon 12 material disclosed by the invention has excellent gas barrier property and mechanical property, high melt strength and good long-term hydrostatic resistance, and can be applied to sub-high pressure gas pipelines, carbon dioxide pipelines, oil and gas pipelines, hydrogen delivery pipelines and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer material synthesis and processing, and relates to a high gas-barrier nylon 12 material and nylon pipes for sub-high-pressure gas pipelines, carbon dioxide pipelines, oil and gas pipelines, hydrogen transmission pipelines, etc. Background Art

[0002] Existing non-metallic gas pipelines mainly include PE pipes applied to medium and low pressure (≤0.4 MPa) and PA12 pipes for sub-high pressure (0.4 to 1.8 MPa); due to the insufficient intermolecular force of the PE pipe molecular chains, it cannot effectively prevent gas penetration; although the traditional PA12 gas pipeline has hydrogen bonds between molecular chains and its gas barrier property is improved compared with the PE gas pipeline, due to the reduction of the hydrogen bond density of the material after blending modification, it still cannot meet the use requirements under higher gas barrier, which limits the promotion of non-metallic pipelines in the gas and other fields.

[0003] To address the problem of insufficient gas barrier of pipeline materials, current technologies mainly improve it by methods such as blending modification and designing multi-layer structures. For example, CN 114957979 A discloses a method of blending MXD6 barrier masterbatch, elastomer, and organically coupled nano-montmorillonite with nylon to improve the gas barrier property of nylon materials. Although the obtained material effectively improves the barrier property, the inorganic filler-modified nylon does not meet the conditions for large-diameter extrusion molding of gas pipelines; CN 116355304 A discloses a multi-functional HDPE / PA structural wall pipe, which intends to use a non-polar PE and PA multi-layer structure to improve the gas barrier property of PE pipes. Although this structure effectively improves the methane gas barrier property of PE pipes, the pipeline performance is limited by the barrier property of the used nylon layer and still cannot meet the higher use requirements of non-metallic gas pipelines; CN 108250742 A discloses a technology using high-melting-point amide salts and mineral fillers as nucleating agents to improve the crystallinity of long-chain nylon. Although this technology can effectively improve the mechanical strength and crystallinity of long-chain nylon materials, due to the presence of aromatic structures in the high-melting-point amide salt structure, it will cause the material to become brittle and the crystal regions to show island-phase dispersion, and cannot meet the gas barrier property and material toughness required for gas pipeline applications.

[0004] Therefore, in this field, it is desirable to develop a high gas-barrier polyamide gas pipeline material, and the pipeline made of it has both the toughness and chemical corrosion resistance of non-metallic materials and the gas barrier property of metal pipelines. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the main purpose of the present invention is to provide a high gas-barrier nylon 12 material, which has high gas barrier property, suitable mechanical properties and processing properties, and can be applied to sub-high-pressure gas pipelines, carbon dioxide pipelines, oil and gas pipelines, hydrogen transmission pipelines, etc. after being processed into pipes and pipe fittings.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a high gas barrier nylon 12 material for gas pipelines, which is prepared from the following components:

[0008]

[0009] In the present invention, the dosage of the nylon 12 can be 76%, 80%, 85%, 90%, etc.

[0010] The entanglement effect of the high-viscosity nylon 12 molecular chains is more obvious, which is beneficial to the properties such as resistance to slow crack growth (SCG) and resistance to rapid crack propagation (RCP) of the nylon 12 gas pipeline material after blending modification. The lower melt index is also beneficial to the extrusion processing of large-diameter gas pipelines.

[0011] Preferably, the Ubbelohde viscosity of the nylon 12 is between 2.0 and 2.5, and the melt volume rate (MVR) at 235°C and 2.16 Kg is between 3 and 9 g / 10 min.

[0012] Preferably, the Ubbelohde viscosity of the nylon 12 is between 2.2 and 2.5, and the melt volume rate (MVR) at 235°C and 2.16 Kg is between 3 and 8 g / 10 min.

[0013] In the present invention, the dosage of the dodecyl lactam can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.8%, etc.

[0014] In the present invention, the solubility of dodecyl lactam in nylon 12 is excellent. Its addition can act as a plasticizer and a nucleating agent, that is, it can improve the crystallinity and play a role in lubricating and plasticizing, ensuring the toughness of the nylon 12 gas pipeline, and at the same time improving the gas barrier property of the material.

[0015] In addition, as the polymerization monomer of nylon 12, dodecyl lactam can resist the degradation of molecular chains caused by factors such as thermal processing and hydrolysis during the long-term use of the nylon 12 gas pipeline material, and improve the service life of the gas pipeline material. When its content in the nylon material is less than 0.1%, the lubricating and plasticizing effect cannot be achieved due to too low content. When the content is greater than 0.8%, its nucleating effect will accelerate the crystallization of the material, resulting in an increase in crystallization defects, thereby leading to an increase in the gas permeability of the material.

[0016] In the present invention, the dosage of the graft toughening agent can be 8%, 10%, 13%, 15%, 18%, 20%, etc.

[0017] In the present invention, the dosage of the lubricant can be 0.4%, 0.6%, 0.8%, 1.0%, etc.

[0018] In the present invention, the lubricant can be one or more of substances such as polytetrafluoroethylene, silicone, erucamide, montanic acid wax, polyethylene wax, zinc stearate, magnesium stearate, calcium stearate or titanate.

[0019] In the present invention, the lubricant is one or more of polytetrafluoroethylene, calcium stearate and silicone.

[0020] In the present invention, the dosage of the antioxidant can be 0.5%, 0.7%, 0.8%, 1.0%, 1.2%, etc.

[0021] In the present invention, the antioxidant includes one or more of hindered phenols, hindered amines, phosphite esters, potassium iodide - copper iodide inorganic stabilizers or aromatic amines.

[0022] In the present invention, the addition of the graft toughening agent effectively increases the molecular weight of the long-chain nylon material and improves the melt strength of the material to achieve the processing and molding of large-size pipes; preferably, the graft toughening agent is an EPDM-based matrix. EPDM is usually a copolymer of ethylene, propylene and a small amount of non-conjugated diolefins. Its main chain is composed of saturated hydrocarbons, but contains unsaturated double bonds in the side chain, and has greater polarity compared with POE-based toughening agents, improving the compatibility with long-chain nylon. The toughening agent has one or two of maleic anhydride and glycidyl methacrylate graft compatibilization modification, and the grafting rate is 0.5 - 1.2%, such as 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.2%, etc.

[0023] In the present invention, examples of the graft toughening agent include but are not limited to POE-MAH, POE-GMA, EPDM-MAH, EPDM-GMA, EMA-GMA, EBA-GMA.

[0024] Preferably, the antioxidant includes any one or a combination of at least two of hindered phenols, hindered amines, phosphite esters, potassium iodide - copper iodide inorganic stabilizers or aromatic amines.

[0025] Preferably, based on the weight of the nylon 12 material being 100%, the weight of the other additives is 1% - 2%.

[0026] Preferably, the other additives include any one or a combination of at least two of hydrolysis-resistant agents, flame retardants, ultraviolet stabilizers, light stabilizers, pigments, color masterbatches, inorganic salts.

[0027] The nylon 12 material described in the present invention can be processed into pipes and pipe fittings and applied to sub-high pressure gas pipelines, carbon dioxide pipelines, oil and gas pipelines, hydrogen transmission pipelines, etc. Its alkane gas permeability is less than 0.5 ml·mm / m 2 ·d·MPa.

[0028] Compared with the prior art, the present invention has at least the following technical advantages:

[0029] (1) By introducing an appropriate amount of dodecanolactam, the alkane gas permeability of the nylon 12 gas pipeline material is reduced to less than 0.5 ml·mm / m 2 ·d·MPa, which is significantly improved compared with the traditional nylon 12 gas pipeline material;

[0030] (2) Although common crystallization modification methods (such as adding montanic acid nucleating agents, etc.) can improve the crystallinity of the material, they will lead to an island-phase distribution of crystal regions and embrittlement of the material, which cannot meet the requirements of alkane gas permeability and mechanical properties of the nylon 12 gas pipeline material. Adding dodecanolactam that is completely compatible with nylon 12 can not only reduce the gas barrier property but also play a role in lubrication and plasticization, ensuring the toughness of the nylon 12 gas pipeline. Specific embodiments

[0031] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should clearly understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0032] The raw material grades and supplier information used in the preparation examples and embodiments of the present invention are as follows:

[0033] Table 1 Raw material grades and supplier information

[0034]

[0035]

[0036] Example 1

[0037] Prepare a high gas barrier nylon 12 material for gas pipelines according to the following raw materials by weight percentage:

[0038]

[0039] Among them, the grade of nylon 12 resin used is L3001; the purity of laurolactam is greater than 98%; the toughening agent is GR216; the lubricants are calcium stearate (0.3%) and erucamide (0.2%); the antioxidants are 1098 (0.4%) and 168 (0.2%); other additives include ultraviolet stabilizer UV 329 (0.2%), light stabilizer 770 (0.2%), and color masterbatch (0.6%).

[0040] The nylon 12 material particles are prepared through the following steps:

[0041] Mix nylon 12, laurolactam, graft toughening agent, lubricants, antioxidants, and other additives evenly according to the ratio using a low-speed mixer at a rotation speed of 100 rpm for 10 minutes. The extrusion temperature is 250°C, the screw rotation speed is 500 - 700 rpm, the production capacity is 35 Kg / h, and the vacuum degree is -0.05 MPa.

[0042] Example 2

[0043] The difference between this example and Example 1 is only that the dosage of laurolactam is changed from 0.5% to 0.2%, and the dosage of nylon 12 resin is changed from 87.4% to 87.7%, while other conditions are the same as those in Example 1.

[0044] Example 3

[0045] The difference between this example and Example 1 is only that the dosage of laurolactam is changed from 0.5% to 0.8%, and the dosage of nylon 12 resin is changed from 87.4% to 87.1%, while other conditions are the same as those in Example 1.

[0046] Example 4

[0047] The difference between this example and Example 1 is only that the dosage of graft toughening agent is changed from 10% to 18%, and the dosage of nylon 12 resin is changed from 87.4% to 79.4%, while other conditions are the same as those in Example 1.

[0048] Comparative Example 1

[0049] The difference between this comparative example and Example 1 is only that the dosage of laurolactam is changed from 0.5% to 1.2%, and the dosage of nylon 12 resin is changed from 87.4% to 86.7%, while other conditions are the same as those in Example 1.

[0050] Comparative Example 2

[0051] The difference between this comparative example and Example 1 is only that the dosage of graft toughening agent is changed from 10% to 5%, and the dosage of nylon 12 resin is changed from 87.4% to 92.4%, while other conditions are the same as those in Example 1.

[0052] Comparative Example 3

[0053] The difference between this comparative example and Example 1 is only that the dosage of the graft toughening agent is changed from 10% to 25%, and the dosage of nylon 12 resin is changed from 87.4% to 72.4%, and other conditions are the same as those in Example 1.

[0054] Comparative Example 4

[0055] The difference between this comparative example and Example 1 is only that the high-viscosity nylon 12 resin (grade L3001) is changed to a medium-viscosity nylon 12 resin (grade L2001), and the dosage remains unchanged, and other conditions are the same as those in Example 1.

[0056] Comparative Example 5

[0057] The difference between this comparative example and Example 1 is only that laurolactam is changed to CAV 102, and the dosage remains unchanged, and other conditions are the same as those in Example 1.

[0058] Comparative Example 6

[0059] The difference between this comparative example and Example 1 is only that laurolactam is changed to hexamethylene diamine terephthalate, and the dosage remains unchanged, and other conditions are the same as those in Example 1.

[0060] Comparative Example 7

[0061] The difference between this comparative example and Example 1 is only that laurolactam is changed to dodecanedioic acid dodecamethylene diamine salt, and the dosage remains unchanged, and other conditions are the same as those in Example 1.

[0062] The materials of Examples 1-4 and Comparative Examples 1-7 were tested according to the following methods:

[0063] (1) Melt volume rate MVR: Tested according to the ISO 1133-1:2022 standard, and the test conditions are 5 Kg + 275 °C;

[0064] (2) Alkane gas permeability: Tested according to the GB / T 1038:2000 standard;

[0065] (3) Izod impact strength (23 °C & -30 °C): Tested according to the ISO 178-2:2020 standard;

[0066] (4) Tensile strength and elongation at break: Tested according to the ISO 527-1:2021 standard.

[0067] The test results are shown in Table 2:

[0068] Table 2 Test results of examples and comparative examples

[0069]

[0070]

[0071] As can be seen from Tables 1 and 2, for the high gas barrier nylon 12 materials prepared in Examples 1-4 of the present invention for gas pipelines, their melt indices match the extrusion process of large-diameter gas pipelines, with the MVR ranging from 10 to 25 ml / min, the notched Izod impact strength at 23 °C being greater than 55 KJ / m 2 , and the notched Izod impact strength at -30 °C being greater than 10 KJ / m 2 , the elongation at break being greater than 150%, and the tensile strength being greater than 40 MPa, meeting the mechanical strength and toughness requirements for the buried use of nylon 12 gas pipelines. Their alkane gas permeabilities are all lower than 0.5 ml·mm / m 2 ·d·MPa, greatly improving the alkane gas permeability of nylon 12 gas pipeline materials and meeting the necessary conditions for nylon 12 gas pipelines at higher transmission pressures. Comparing with the performance of the comparative examples, it can be seen that the addition of dodecanolactam effectively reduces the alkane gas barrier property of nylon 12 materials, while additives such as montmorillonite salts like CAV 102 and amide salts can only play a nucleating role, resulting in embrittlement of the materials and being unable to effectively reduce the gas barrier property of the materials, thus failing to meet the performance requirements of nylon 12 gas pipeline materials.

[0072] The present invention uses the above examples to illustrate the high gas barrier nylon 12 materials for gas pipelines and their preparation methods of the present invention, but the present invention is not limited to the above examples, that is, it does not mean that the present invention must rely on the above examples to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent substitution of each raw material of the products of the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A high gas barrier nylon 12 material is prepared from the following components:

2. The material according to claim 1, wherein, the Ubbelohde viscosity of the nylon 12 ranges between 2.0 and 2.5, and the melt volume rate MVR at 235°C and 2.16 Kg ranges between 3 and 9 g / 10 min.

3. The material according to claim 1 or 2, wherein, the Ubbelohde viscosity of the nylon 12 ranges between 2.2 and 2.5, and the melt volume rate MVR at 235°C and 2.16 Kg ranges between 3 and 8 g / 10 min.

4. The material according to any one of claims 1 - 3, wherein, the matrix of the graft toughening agent is selected from EPDM and POE, and is graft compatibly modified with one or two of maleic anhydride and glycidyl methacrylate, and the grafting rate is 0.5 - 1.2%.

5. The material according to any one of claims 1 - 4, wherein, the graft toughening agent is selected from one or more of POE - MAH, POE - GMA, EPDM - MAH, EPDM - GMA, EMA - GMA, and EBA - GMA.

6. The material according to any one of claims 1 - 5, wherein, the lubricant is selected from one or more of polytetrafluoroethylene, silicone, erucamide, montanic acid wax, polyethylene wax, zinc stearate, magnesium stearate, calcium stearate, and titanate.

7. The material according to any one of claims 1 - 6, wherein, the antioxidant includes one or more of hindered phenols, hindered amines, phosphites, potassium iodide - copper iodide inorganic stabilizers, or aromatic amines.

8. The material according to any one of claims 1 - 7, wherein, the other processing aids include one or more of hydrolysis resistant agents, flame retardants, UV stabilizers, light stabilizers, pigments, color masterbatches, and inorganic salts.

9. A nylon pipe, comprising the nylon 12 material according to any one of claims 1-8, and having an alkane gas permeability of 0.5 ml·mm / m 2 ·d·MPa or less.

10. Use of the nylon pipeline according to claim 9 for preparing sub - high - pressure gas pipelines, carbon dioxide pipelines, oil and gas pipelines, and hydrogen transmission pipelines.

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