A copolymer nylon material, its preparation method and use

Abstract

The present application relates to a kind of copolymer nylon material and its preparation method and application, belong to the composition technical field of polymer compound.The copolymer nylon material of the present application, by weight parts, includes the following components: copolymer nylon resin 34~66 parts, reinforcing fiber 30~45 parts;The copolymer nylon resin includes the structural unit derived from aliphatic diamine and the structural unit derived from diacid;The diacid includes aliphatic diacid, terephthalic acid and isophthalic acid;Based on the total molar amount of the structural unit derived from diacid in the copolymer nylon resin, the total mole ratio of the structural unit derived from terephthalic acid and isophthalic acid is 19% to 36%;The temperature difference of the crystallization temperature and melting point of the copolymer nylon resin is ≥60 DEG C.The copolymer nylon material has good appearance performance and excellent welding performance.

Description

Technical Field

[0001] This invention relates to the field of polymer composition technology, and more particularly to a copolymer nylon material, its preparation method, and its applications. Background Technology

[0002] Currently, the inner tanks of electric water heaters are mainly made of metal enamel, but these inner tanks have the following problems: metal corrosion after prolonged use leads to perforation and leakage; the metal material of the inner tank makes it prone to electrical leakage; and large amounts of scale will accumulate in the inner tank after long-term use, affecting water quality. To address these issues, existing technologies use lightweight, high-strength, and corrosion-resistant polyamide / fiber composite materials to create polyamide composite inner tanks to replace the metal enamel inner tanks. In practical applications, a high content of reinforcing fibers is often added to improve the strength and heat resistance of the polyamide composite inner tank. However, this leads to serious appearance problems during injection molding and also affects its subsequent welding performance. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a copolymer nylon material, its preparation method, and its application.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a copolymer nylon material comprising, by weight, the following components: 34-66 parts copolymer nylon resin and 30-45 parts reinforcing fiber; The copolynylon resin comprises structural units derived from aliphatic diamines and structural units derived from diacids; the diacids include aliphatic diacids, terephthalic acid, and isophthalic acid. Based on the total molar amount of structural units derived from dicarboxylic acids in the copolymer nylon resin, the total molar percentage of the structural units derived from terephthalic acid and isophthalic acid is 19% to 36%. The temperature difference between the crystallization temperature and the melting point of the copolymer nylon resin is ≥60℃, preferably 61℃ to 80℃.

[0005] Based on the total mass of the copolymer nylon material, the copolymer nylon resin accounts for ≥40% of the mass, and the reinforcing fiber accounts for 30% to 55% of the mass.

[0006] In some embodiments, the weight parts of the copolymer nylon resin in the copolymer nylon material may be, but are not limited to, any one or any two of the following values: 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 48 ​​parts, 49 parts, 50 parts, 51 parts, 52 parts, 53 parts, 54 parts, 55 parts, 56 parts, 57 parts, 58 parts, 59 parts, 60 parts, 61 parts, 62 parts, 63 parts, 64 parts, 65 parts, and 66 parts.

[0007] In some embodiments, the weight parts of reinforcing fibers in the copolymer nylon material may be, but are not limited to, any or both of the following ranges: 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, and 45 parts.

[0008] In some embodiments, based on the total molar amount of structural units derived from dicarboxylic acids in the copolymer nylon resin, the total molar percentage of the structural units derived from terephthalic acid and isophthalic acid may be, but is not limited to, any one or any two of the following values: 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, and 36%.

[0009] In some embodiments, based on the total molar amount of structural units derived from diacids in the copolynylon resin, the molar percentage of the structural units derived from aliphatic diacids is 64% to 81%, for example, but not limited to any or both of the following values: 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, and 81%.

[0010] In some embodiments, the temperature difference between the crystallization temperature and the melting point of the copolymer nylon resin may be, but is not limited to, any or both of the following ranges: 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, and 80°C.

[0011] In a preferred embodiment of the copolymer nylon material of the present invention, the molar ratio of the terephthalic acid-derived structural units to the isophthalic acid-derived structural units is 2:1 to 1:1, for example, but not limited to any one or both of the following: 2:1, 1.9:1, 1.8:1, 1.7:1, 1.6:1, 1.5:1, 1.4:1, 1.3:1, 1.2:1, 1.1:1, and 1:1. Studies have found that by controlling the molar ratio of the terephthalic acid-derived structural units to the isophthalic acid-derived structural units within the above range, the synergistic effect of the symmetrical structure of terephthalic acid and the sterically hindered and asymmetrical structure of isophthalic acid can be better promoted to adjust the crystallization temperature and melting point of the copolymer nylon resin, thereby better improving the welding performance of the copolymer nylon material.

[0012] Copolymer nylon resin can be derived from commercially available products or made in-house. For in-house production, please refer to CN109503828A.

[0013] The homemade method specifically includes the following steps: In an inert gas atmosphere, a dicarboxylic acid, a diamine, a catalyst, and deionized water are mixed evenly and reacted at 70-90°C for 4.5-6.5 hours. Then, the temperature of the reaction system is raised to 130-150°C and held for 1-1.5 hours. Next, the temperature of the reaction system is raised to 200-250°C, and the pressure of the reaction system is maintained at 3-3.5 MPa for 1-1.5 hours. After that, the pressure of the reaction system is released to atmospheric pressure, and the temperature is raised to 340-380°C and held for 2-2.5 hours to obtain a copolymerized nylon resin.

[0014] As a preferred embodiment of the copolymer nylon material of the present invention, the melting point of the copolymer nylon resin is 220°C to 280°C; and / or, the crystallization temperature of the copolymer nylon resin is ≥160°C, preferably 200°C to 220°C.

[0015] In some embodiments, the melting point of the copolynylon resin may be, but is not limited to, a range of any one or both of the following: 220°C, 222°C, 224°C, 226°C, 228°C, 230°C, 232°C, 234°C, 236°C, 238°C, 240°C, 242°C, 244°C, 246°C, 248°C, 250°C, 252°C, 254°C, 256°C, 258°C, 260°C, 262°C, 264°C, 266°C, 268°C, 270°C, 272°C, 274°C, 276°C, 278°C, and 280°C.

[0016] In some embodiments, the melting point of the copolynylon resin may be, but is not limited to, a range of any one or both of the following: 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 201°C, 202°C, 203°C, 204°C, 205°C, 206°C, 207°C, 208°C, 209°C, 210°C, 211°C, 212°C, 213°C, 214°C, 215°C, 216°C, 217°C, 218°C, and 220°C.

[0017] As a preferred embodiment of the copolymer nylon material of the present invention, the relative viscosity of the copolymer nylon resin is 2 to 3, for example, but not limited to any one or any two of 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.

[0018] In a preferred embodiment of the copolynylon material of the present invention, the aliphatic diamine and / or the aliphatic dicarboxylic acid have 4 to 14 carbon atoms.

[0019] In some embodiments, the number of carbon atoms in the aliphatic diamine may be, but is not limited to, any or both of the following ranges: 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14.

[0020] In some embodiments, aliphatic diamines include, but are not limited to, butanediamine, 1,2-butanediamine, 1,3-butanediamine, pentanediamine, hexanediamine, heptamethamine, octanediamine, nonanediamine, decanediamine, undecanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, etc.

[0021] In some embodiments, the number of carbon atoms in the aliphatic dicarboxylic acid may be, but is not limited to, a range of any one or both of 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, and 14.

[0022] In some embodiments, aliphatic dicarboxylic acids include, but are not limited to, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, dodecanoic acid, tetradecanoic acid, etc.

[0023] In a preferred embodiment of the copolymer nylon material of the present invention, the reinforcing fiber includes at least one of glass fiber, carbon fiber, basalt fiber, and aramid fiber.

[0024] As a preferred embodiment of the copolymer nylon material of the present invention, the copolymer nylon material further includes 1 to 3 parts by weight of antioxidant and 1 to 2 parts by weight of lubricant.

[0025] In some embodiments, the weight parts of antioxidant in the copolynylon material may be, but are not limited to, any one or any two of the following: 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, 2.4 parts, 2.6 parts, 2.8 parts, and 3 parts.

[0026] In some embodiments, the antioxidant includes, but is not limited to, at least one of hindered phenolic antioxidants, hindered amine antioxidants, phosphite antioxidants, thioester antioxidants, and hydroxylamine antioxidants.

[0027] In some embodiments, the weight parts of lubricant in the copolynylon material may be, but are not limited to, any one or any two of the following values: 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, and 2 parts.

[0028] In some embodiments, the lubricant includes, but is not limited to, at least one of stearamide, oleamide, erucamide, zinc stearate, polymeric complex esters of metal soaps, ethylene bis-stearamide, polyethylene wax, and silicone lubricants.

[0029] Secondly, the present invention provides a method for preparing the above-mentioned copolynylon material, comprising the following steps: mixing the components evenly and then melting and extruding to obtain the copolynylon material.

[0030] Optionally, the above preparation method can use a twin-screw extruder for melt extrusion, with a melt extrusion temperature of 220°C to 280°C, a screw speed of 200 rpm to 350 rpm, and a length-to-diameter ratio of 36:1 to 48:1.

[0031] Thirdly, the present invention provides an application of the above-mentioned copolymer nylon material in the preparation of water heater inner tanks.

[0032] Fourthly, the present invention provides a water heater comprising a shell and an inner tank, the inner tank being made of the aforementioned copolynylon material.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows: The copolymer nylon material of the present invention maintains high strength while also possessing good appearance and excellent weldability. Detailed Implementation

[0034] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0035] Unless otherwise specified, all other materials, reagents, etc. used in the examples and comparative examples are commercially available.

[0036] 1. Raw materials and reagents 1) Copolymer Nylon Resin The copolymer nylon resin is prepared by the following method: Method A: Under a nitrogen atmosphere, dicarboxylic acids (terephthalic acid, isophthalic acid, and aliphatic dicarboxylic acids), diamines, catalysts (sodium hypophosphite), and deionized water are sequentially added to a reactor. After thorough stirring, the reactor temperature is raised to 75±5℃ and reacted for 5.5±0.5h. Under nitrogen protection, the reactor is further heated to 140±10℃ and held for 1.25±0.25h, then heated to 225±25℃. The pressure inside the reactor is adjusted to maintain 3.25±0.25MPa and held for 1.25±0.25h. Afterward, the pressure is released to atmospheric pressure, the temperature is raised to 350±10℃ and held for 2.25±0.25h, and then cooled and discharged. The molar ratio of dicarboxylic acid to diamine is 1:1, and terephthalic acid, isophthalic acid, and aliphatic dicarboxylic acids are added according to the molar ratios in Table 1.

[0037] Method B: Under a nitrogen atmosphere, dicarboxylic acids (terephthalic acid, isophthalic acid, and aliphatic dicarboxylic acids), diamines, catalysts (potassium phosphate), and deionized water are sequentially added to a reactor. After thorough stirring, the reactor temperature is raised to 85±5℃ and reacted for 5.5±0.5h. Under nitrogen protection, the reactor is further heated to 140±10℃ and held for 1.25±0.25h, then heated to 225±25℃. The pressure inside the reactor is adjusted to maintain 3.25±0.25MPa and held for 1.25±0.25h. Afterward, the pressure is released to atmospheric pressure, the temperature is raised to 370±10℃ and held for 2.25±0.25h, and then cooled and discharged. The molar ratio of dicarboxylic acid to diamine is 1:1, and terephthalic acid, isophthalic acid, and aliphatic dicarboxylic acids are added according to the molar ratios in Table 1.

[0038] Table 1. Components of Copolymer Nylon Resin Table 2 Crystallization temperature, melting point, and relative viscosity of copolynylon resin The crystallization temperature and melting point of the copolymer nylon resin can be determined according to standard GB / T 19466.3-2004; The relative viscosity of the copolymer nylon resin can be measured using the Ubbelohde viscometer method with concentrated sulfuric acid. The specific steps are as follows: accurately weigh 0.5 ± 0.0002 g of the dried copolymer nylon resin sample, add 50 mL of concentrated sulfuric acid (98%) to dissolve it, measure and record the flow time t1 of the concentrated sulfuric acid and the flow time t2 of the copolymer nylon resin solution in a constant temperature water bath at 25℃, and the relative viscosity = t2 / t1.

[0039] The molar content and molar ratio of terephthalic acid and isophthalic acid in copolymer nylon resin can be determined by acid hydrolysis-high performance liquid chromatography (HPLC). The specific steps include: accurately weighing 0.10 ± 0.0002 g of the dried copolymer nylon resin sample, placing it in a pressure-resistant hydrolysis tube, adding 6 mol / L hydrochloric acid solution, sealing, and hydrolyzing at 110–130 °C for 6–12 h, cooling to room temperature, making up to volume, and filtering to obtain the sample solution to be tested; preparing standard solutions of terephthalic acid and isophthalic acid separately and establishing standard curves; using a C18 column with acetonitrile-0.1% phosphoric acid aqueous solution as the mobile phase, performing HPLC testing at a detection wavelength of 240 nm, recording the peak area, and obtaining the mass content of terephthalic acid and isophthalic acid in the sample from the standard curve; and then calculating the corresponding molar content and molar ratio based on their molar masses.

[0040] 2) Reinforcing fibers Reinforcing fiber 1 is round glass fiber, grade ECS301HP-3-H, manufactured by Chongqing International Composite Materials Co., Ltd. Reinforcing fiber 2 is carbon fiber, grade ST800, manufactured by Guangzhou Sente New Materials Co., Ltd.

[0041] 3) Antioxidants The antioxidant is a phosphite antioxidant, brand name RIANOX168, manufactured by Tianjin Lialong.

[0042] 4) Lubricant The lubricant is a silicone-based lubricant, brand name GT-300, manufactured by Zhejiang Jiahua.

[0043] 2. Preparation method of the copolymerized nylon material of the present invention According to the formula, the components are mixed evenly and then added to a twin-screw extruder for melt extrusion and granulation to obtain a copolymer nylon material. The reinforcing fiber is fed in by side feeding. The twin-screw extruder has a screw length-to-diameter ratio of 40:1, and the barrel temperatures are 270℃, 250℃, 250℃, 250℃, 250℃, 260℃, and 280℃, respectively. The screw speed is 200 rpm.

[0044] 3. Performance Testing 1) Welding tensile strength: The copolymer nylon material of each embodiment and comparative example was injection molded into 80mm×10mm×4mm specimens. Two bent specimens were welded head to head by vibration welding (amplitude of 1mm, pressure of 30bar, welding depth of 1.5mm, holding time of 3s) to obtain welded specimens. Then, the tensile strength of the welded specimens was tested at a tensile rate of 10mm / min (test method refers to ISO 527-2:2025) to obtain the welding tensile strength.

[0045] 2) Appearance performance: The copolynylon materials of each embodiment and comparative example are injection molded into strips of the same size (100mm×100mm×2mm), and the appearance of the strips is observed. If there are no floating fibers on the appearance of the strip, it is considered excellent; if there are very slight or very few floating fibers on the surface, it is considered good; if there are obvious and a large number of floating fibers on the surface and the surface is rough, it is considered poor; when the appearance performance reaches good, it is considered qualified.

[0046] Table 3 shows the weight parts and properties of each component in the copolynylon materials of Examples 1 to 11. Table 4 shows the weight parts and properties of each component in the copolynylon materials of Comparative Examples 1 to 3. In Tables 3 and 4, " / " indicates that there are no relevant parameters.

[0047] As shown in Tables 3 and 4, the weld tensile strength of the copolymer nylon materials in Examples 1 to 11 all reached over 50 MPa, and their appearance properties were all good or excellent, indicating that the copolymer nylon materials of the present invention possess both good appearance properties and excellent weldability. According to Comparative Examples 1 to 3, it can be found that, based on the total molar amount of structural units derived from dicarboxylic acids in the copolymer nylon resin, if the total molar proportion of structural units derived from terephthalic acid and isophthalic acid is too small or too large, or if the temperature difference between the crystallization temperature and melting point of the copolymer nylon resin is too small, it is impossible to effectively improve the appearance and weldability of the copolymer nylon materials.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A copolymer nylon material, characterized in that, By weight, it includes the following components: 34-66 parts of copolymerized nylon resin and 30-45 parts of reinforcing fiber; The copolynylon resin comprises structural units derived from aliphatic diamines and structural units derived from diacids; the diacids include aliphatic diacids, terephthalic acid, and isophthalic acid. Based on the total molar amount of structural units derived from dicarboxylic acids in the copolymer nylon resin, the total molar percentage of the structural units derived from terephthalic acid and isophthalic acid is 19% to 36%. The temperature difference between the crystallization temperature and the melting point of the copolymer nylon resin is ≥60℃.

2. The copolymer nylon material as described in claim 1, characterized in that, The molar ratio of the structural unit derived from terephthalic acid to the structural unit derived from isophthalic acid is 2:1 to 1:

1.

3. The copolynylon material as described in claim 1, characterized in that, The copolymer nylon resin has a melting point of 220°C to 280°C; and / or, the copolymer nylon resin has a crystallization temperature ≥160°C.

4. The copolymer nylon material as described in claim 1, characterized in that, The relative viscosity of the copolymer nylon resin is 2 to 3.

5. The copolymer nylon material as described in claim 1, characterized in that, The aliphatic diamine and / or the aliphatic dicarboxylic acid have 4 to 14 carbon atoms.

6. The copolymer nylon material as described in claim 1, characterized in that, The reinforcing fiber includes at least one of glass fiber, carbon fiber, basalt fiber, and aramid fiber.

7. The copolynylon material according to any one of claims 1 to 6, characterized in that, The copolymer nylon material also includes 1-3 parts by weight of antioxidant and 1-2 parts by weight of lubricant.

8. A method for preparing the copolynylon material according to any one of claims 1 to 7, characterized in that, The process includes the following steps: mixing the components evenly and then melting and extruding them to obtain a copolynylon material.

9. The use of the copolymer nylon material according to any one of claims 1 to 7 in the preparation of a water heater inner tank.

10. A water heater, characterized in that, It includes an outer shell and an inner liner, the inner liner being made of the copolynylon material according to any one of claims 1 to 7.

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