Reinforced and toughened regenerated polyamide material and processing method thereof

Abstract

The invention relates to the technical field of recycled material regeneration processing, in particular to a reinforced and toughened regenerated polyamide material and a processing method thereof, and adopts the following technical scheme that the reinforced and toughened regenerated polyamide material is prepared from the following components in percentage by mass: 50 to 90 percent of recycled polyamide, 1 to 5 percent of isocyanate-terminated polysiloxane, 3 to 20 percent of epoxy POSS, 0 to 30 percent of reinforcing filler, 0 to 5 percent of compatilizer, 0.01 to 1 percent of lubricant and 0.01 to 1 percent of antioxidant. The method has the beneficial effects that all the components fully react with one another to form a compact macromolecular cross-linked structure while fully extending the chain of the recycled polyamide, so that the viscosity, molecular weight, mechanical property, impact resistance, heat resistance, weather resistance and the like of the regenerated polyamide material are effectively improved. And the components are fully reacted with each other through specifically selected functional groups, so that the regenerated polyamide material can be prepared only through simple melting reaction extrusion without demanding the adding sequence of the components, and complicated processing procedures are not needed.

Description

Technical Field

[0001] The present invention relates to the technical field of recycled material regeneration processing, in particular to a reinforced and toughened recycled polyamide material and a processing method thereof. Background Art

[0002] Polyamide has excellent wear resistance and self-lubrication, high mechanical strength, good heat resistance and electrical insulation, and is widely used in the fields of fibers, automotive parts, electronic appliances, etc. At present, the secondary brands or substandard products produced during the industrial production of polyamide cannot be used normally due to shortcomings such as low viscosity and insufficient mechanical properties, resulting in a waste of resources. At the same time, waste materials from items made of polyamide materials such as fishing nets and carpets on the market, after being recycled, are subjected to aging and degradation environments such as hydrolysis, photolysis, and pyrolysis during use, resulting in a serious reduction in their molecular weight, and their mechanical properties and reprocessing performance are also greatly reduced. The shortcomings of recycled polyamide materials such as insufficient heat resistance, poor impact toughness, and poor water resistance also limit their use in recycled applications.

[0003] The conventional method for reusing recycled polyamide materials at a lower cost is to mix the recycled polyamide materials with a chain extender and then perform a melt chain extension reaction to increase the viscosity and extend the chain of the recycled polyamide materials. However, the recycled polyamide materials obtained by this conventional method have the disadvantages of poor strength and toughness.

[0004] Furthermore, patent CN201611242189.0 discloses a high-viscosity polyamide 6 composite material prepared by melt extrusion chain extension reaction and a preparation method thereof. By adding a certain amount of a 1:1 alternating copolymer of ethylene and maleic anhydride as a thickener, polyamides of different viscosities are prepared. Although this patent has a certain thickening effect, the modification effect is general, the process is complicated, and the thickening masterbatch needs to be prepared in advance.

[0005] Patent CN202210768888.8 discloses an isomeric micro-crosslinked regenerated polyamide and a preparation method thereof. The patent utilizes the synergistic effect of active end-group dendritic polyamide amine and a chain extender to first prepare pretreated hyperbranched polyamide amine, then use a twin-screw extruder to obtain isomeric micro-crosslinked regenerated polyamide particles, and finally use solid-phase thickening under nitrogen protection in a rotary drum reactor to obtain micro-crosslinked polyamide with improved viscosity and performance. However, this patent has the defects of a complex preparation process and a long process time, and its improved mechanical properties are also difficult to meet high performance requirements.

[0006] Improving the comprehensive properties of recycled polyamide materials, such as mechanical properties, impact toughness, heat resistance, and weather resistance, to achieve their reuse while simplifying the process and minimizing resource waste is a pressing issue for recycled polyamide materials, offering significant practical, environmental, and economic value. The prior art lacks a recycled polyamide material that combines simple processes and reduced time consumption with improved molecular weight, mechanical properties, impact toughness, heat resistance, and weather resistance. Summary of the Invention

[0007] The purpose of the present invention is to provide a reinforced and toughened recycled polyamide material and a processing method thereof, specifically to provide a recycled polyamide material and a processing method thereof that has excellent comprehensive properties such as mechanical properties, impact toughness, heat resistance, and weather resistance, while taking into account simple process and reduced resource waste.

[0008] To achieve the above objectives, the present invention employs the following technical solution: a reinforced and toughened recycled polyamide material, comprising, by mass percentage, the following components: 50-90% recycled polyamide, 1-5% toughening chain extender, 3-20% reinforcing and toughening branching agent, 0-30% reinforcing filler, 0-5% compatibilizer, 0.01-1% lubricant, and 0.01-1% antioxidant. The toughening chain extender is an isocyanate-terminated polysiloxane and / or isocyanate-terminated polyurethane, and the reinforcing and toughening branching agent is an epoxy-functionalized cage-type polysilsesquioxane (epoxy-POSS) containing three or more active epoxy groups. Cage-type polysilsesquioxane (POSS) is an inorganic "cage" core composed of a silicon-oxygen backbone with alternating Si-O linkages. It is a nanomaterial that combines toughness, hydrophobicity, and heat resistance. However, as a nanomaterial, it suffers from difficulties in dispersion, agglomeration, and extrusion processing in composite systems. This application uses epoxy-functionalized caged polysilsesquioxane (epoxy-POSS) containing three or more active epoxy groups, taking into account the dispersibility, processing viscosity, and modification effect of the recycled polyamide material composition. The use of epoxy-POSS can effectively improve the mechanical properties, heat resistance, and impact resistance of the system, while also improving the flame retardancy of the recycled polyamide material to a certain extent.

[0009] Specifically, the recycled polyamide uses unqualified polyamide materials produced industrially or waste polyamide materials recycled after consumer use.

[0010] Preferably, the toughening chain extender is an isocyanate-terminated polysiloxane, which can be obtained by reacting hydroxyl-terminated polydimethylsiloxane, amino-terminated polydimethylsiloxane, or carboxyl-terminated polydimethylsiloxane with excess diisocyanate.

[0011] Specifically, the reinforcing filler is one or more of calcium carbonate, silicon dioxide, talc, carbon fiber, and glass fiber.

[0012] Specifically, the mass percentage of the compatibilizer is 0.1-5%, and the compatibilizer is one or more of EVA, maleic anhydride grafted polyolefin, and silicone-polyamide grafted copolymer.

[0013] Specifically, white mineral oil is used as the lubricant.

[0014] Specifically, the antioxidant is hindered phenols or phosphites or a combination of hindered phenols and phosphites.

[0015] Preferably, the antioxidant is a compound of hindered phenols and phosphites, wherein the mass ratio of hindered phenols to phosphites is 1:1 to 1:4.

[0016] A method for processing the aforementioned reinforced and toughened recycled polyamide material comprises weighing all raw materials according to mass percentage and uniformly mixing them. The mixed raw materials are then fed into a twin-screw extruder for melt extrusion and pelletization to produce a flame-retardant, high-performance recycled polyamide material. During melt extrusion, the temperatures of the melting and homogenizing sections of the twin-screw extruder are controlled at 220-280°C.

[0017] The beneficial effects of the present invention are as follows: by specifically selecting the functional groups of the chain extender and the branching agent, the isocyanate-terminated polysiloxane as the chain extender has the highest reactivity with the polyamide material, and the epoxy group of the epoxy group POSS as the branching agent has a weaker reactivity relative to the isocyanate group, but the active epoxy group can react with the recycled polyamide and the isocyanate-terminated polysiloxane, so that during the melt reaction process, while the recycled polyamide is fully chain extended, the components fully react with each other to form a dense macromolecular cross-linked structure, effectively improving the viscosity, molecular weight, mechanical properties, impact resistance, heat resistance, weather resistance, etc. of the recycled polyamide material. And because the components fully react with each other through the specifically selected functional groups, the recycled polyamide material of the present invention does not need to be strictly required in the order of addition of the components, and can be obtained by simple melt reaction extrusion without complicated processing steps. DETAILED DESCRIPTION

[0018] In order to facilitate those skilled in the art to clearly understand the technical solutions provided by the present invention and the technical effects it can achieve, the present invention is described in detail with reference to the following specific examples and comparative examples. The following are the specific raw materials used in the examples and comparative examples: Recycled polyamide uses polyamide materials recycled from waste fishing nets.

[0019] The toughening chain extender is an isocyanate-terminated polysiloxane, which is obtained by reacting hydroxyl-terminated polydimethylsiloxane with excess HDI at a molar ratio of NCO / OH of 1.2.

[0020] The reinforcing and toughening branching agent used is epoxy-functionalized cage-type polysilsesquioxane (hereinafter referred to as epoxy POSS) containing more than three active epoxy groups, specifically Ecotion POSS101.

[0021] BASF ADR4468 was used as the epoxy chain extender.

[0022] The branching agent used in the comparative example also includes amino POSS.

[0023] The lubricant is white mineral oil, specifically commercially available No. 68 white oil.

[0024] The antioxidant is a compound of hindered phenols and phosphites, specifically 1010 and 168 in a ratio of 1:2.

[0025] The compatibilizer is maleic anhydride grafted polyacetic acid.

[0026] During the test, all the raw materials in the following examples and comparative examples were mixed and added into a twin-screw extruder, and the recycled polyamide material was obtained by melt extrusion and granulation; the temperature of the melting section and homogenization section of the twin-screw extruder was controlled at 220~280℃.

[0027] The following are the raw material ratios of each embodiment and comparative example: Example

[0028] A reinforced and toughened recycled polyamide material is composed of the following components by mass percentage: 82% recycled polyamide, 2% isocyanate-terminated polysiloxane, 15% epoxy POSS, 0.5% lubricant, and 0.5% antioxidant. Example

[0029] A reinforced and toughened recycled polyamide material consists of the following components, measured by mass percentage: 82% recycled polyamide, 2% isocyanate-terminated polyurethane, 15% epoxy POSS, 0.5% lubricant, and 0.5% antioxidant. Example

[0030] A reinforced and toughened recycled polyamide material is composed of the following components by mass percentage: 60% recycled polyamide, 1% isocyanate-terminated polysiloxane, 7% epoxy POSS, 25% calcium carbonate, 5% compatibilizer, 1% lubricant, and 1% antioxidant. Example

[0031] A reinforced and toughened recycled polyamide material is composed of the following components, measured by mass percentage: 70% recycled polyamide, 2% isocyanate-terminated polysiloxane, 10% epoxy POSS, 13% calcium carbonate (reinforcing filler), 3% compatibilizer, 1% lubricant, and 1% antioxidant.

[0032] Comparative Example 1 A reinforced and toughened recycled polyamide material is composed of the following components by mass percentage: 82% recycled polyamide, 2% epoxy chain extender, 15% epoxy-based POSS, 0.5% lubricant, and 0.5% antioxidant.

[0033] Comparative Example 2 A reinforced and toughened recycled polyamide material is composed of the following components by mass percentage: 82% recycled polyamide, 2% isocyanate-terminated polysiloxane, 15% amino POSS, 0.5% lubricant, and 0.5% antioxidant.

[0034] Comparative Example 3 A reinforced and toughened recycled polyamide material is composed of the following components by mass percentage: 72% recycled polyamide, 2% isocyanate-terminated polysiloxane, 25% epoxy POSS, 0.5% lubricant, and 0.5% antioxidant.

[0035] Comparative Example 4 A reinforced and toughened recycled polyamide material is composed of the following components by mass percentage: 96% recycled polyamide, 2% isocyanate-terminated polysiloxane, 1% epoxy POSS, 0.5% lubricant, and 0.5% antioxidant.

[0036] The recycled polyamide materials obtained in the above Examples 1-4 and Comparative Examples 1-4 were injection molded into standard test specimens for the following performance tests: Tensile properties were tested according to ASTM D-638. Bending properties were tested according to ASTM D-790. Notched impact strength was tested according to ASTM D-256. The weather resistance test was conducted after 60 days of wet heat aging at a temperature of 85°C and a relative humidity of 85%, and the tensile strength retention rate of the recycled polyamide material was tested. Tensile strength retention rate = (tensile strength before aging - tensile strength after aging) / tensile strength before aging × 100%. The water absorption test was conducted by immersing the specimen in a room temperature deionized water bath for 7 days. The test structure is shown below: Tensile strength MPa Bending strength MPa Notched impact strength KJ / m2 Elongation at break (%) Weather resistance (%) Water absorption rate (%) Recycled polyamide 37 51 1.7 2.6% Fail 6.5% Example 1 196 294 56 132% 98% 0.1% Example 2 167 265 45 102% 93% 0.6% Example 3 178 276 48 113% 96% 0.3% Example 4 184 287 52 121% 97% 0.2% Comparative Example 1 122 186 36 77% 86% 3.5% Comparative Example 2 142 228 35 92% 85% 2.6% Comparative Example 3 156 243 42 96% 81% 1.8% Comparative Example 4 77 112 15 36% 75% 4.5% As can be seen from the comparison result of the above-described embodiment and comparative example, the present invention is coordinated to use isocyanate-terminated polysiloxane as toughening chain extender in polyamide material, improves the impact resistance and low-temperature resistance etc. that are derived from polysiloxane while the molecular weight of polyamide material is also obtained. Further, epoxy group(ing) POSS is grafted in the polyamide molecular structure by chemical reaction as branching agent, and gives the low melt processing viscosity of polyamide recycled material due to its branched structure, and then is beneficial to the dispersion between each component, uniform, fully reacting. Epoxy group(ing) POSS of the present invention, as strengthening toughening branching agent, can synergize with isocyanate-terminated polysiloxane chain extender, and collaboratively enhances the molecular weight, mechanical property, impact resistance, heat-resisting, weather resistance etc. of the recycled polyamide material.

[0037] In addition, the composition system of the present invention carries out specific selection to the functional groups of chain extender and branching agent, wherein, isocyanate-terminated polysiloxane has the highest reactivity with polyamide material, and the reactivity of epoxy group relative isocyanate group of epoxy group POSS is weaker, but active epoxy group can react with recycled polyamide and isocyanate-terminated polysiloxane simultaneously. Thus, while ensuring that polyamide fully extends chain, each component fully reacts with each other to form a dense macromolecular cross-linked structure, thereby giving the recycled polyamide material improved viscosity, molecular weight, mechanical properties, impact properties, heat resistance, weather resistance, etc. And the processing process is simple, without the need to control the raw material addition sequence and complicated processing flow, and the processing cost is low.

[0038] Of course, the above are only preferred embodiments of the present invention and are not intended to limit the scope of use of the present invention. Therefore, any equivalent changes based on the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A reinforced and toughened recycled polyamide material, characterized in that: The invention is composed of the following components in percentage by mass: 50-90% recycled polyamide, 1-5% toughening chain extender, 3-20% reinforcing toughening branching agent, 0-30% reinforcing filler, 0-5% compatibilizer, 0.01-1% lubricant, and 0.01-1% antioxidant; the toughening chain extender is isocyanate-terminated polysiloxane and / or isocyanate-terminated polyurethane, and the reinforcing toughening branching agent is epoxy-functionalized cage-type polysilsesquioxane containing more than three active epoxy groups.

2. The reinforced and toughened recycled polyamide material according to claim 1, characterized in that: The recycled polyamide is made of unqualified polyamide materials produced industrially or waste polyamide materials recycled after consumer use.

3. The reinforced and toughened recycled polyamide material according to claim 1, characterized in that: The toughening chain extender is isocyanate-terminated polysiloxane.

4. The reinforced and toughened recycled polyamide material according to claim 1, characterized in that: The reinforcing filler is one or more of calcium carbonate, silicon dioxide, talc, carbon fiber, and glass fiber.

5. The reinforced and toughened recycled polyamide material according to claim 1, characterized in that: The mass percentage of the compatibilizer is 0.1-5%, and the compatibilizer is one or more of EVA, maleic anhydride grafted polyolefin, and silicone-polyamide grafted copolymer.

6. The reinforced and toughened recycled polyamide material according to claim 1, characterized in that: The lubricant is white mineral oil.

7. The reinforced and toughened recycled polyamide material according to claim 1, characterized in that: The antioxidant is hindered phenols or phosphites or a mixture of hindered phenols and phosphites.

8. The reinforced and toughened recycled polyamide material according to claim 7, characterized in that: The antioxidant is a compound of hindered phenols and phosphites, wherein the mass ratio of hindered phenols to phosphites is 1:1-1:

4.

9. A method for processing the reinforced and toughened recycled polyamide material according to any one of claims 1 to 8, characterized in that: All raw materials are weighed according to mass percentage and uniformly mixed, and then the mixed raw materials are added into a twin-screw extruder, and flame-retardant high-performance recycled polyamide materials are obtained after melt extrusion and granulation.

10. The method for processing toughened and reinforced recycled polyamide material according to claim 9, characterized in that: During melt extrusion, the temperature of the melting section and homogenizing section of the twin-screw extruder is controlled at 220~280℃.