Micro-foamed mildew-proof and antibacterial polyamide thermal insulation material and preparation method thereof

Abstract

This invention relates to the field of polyamide thermal insulation materials, specifically to a micro-foamed antifungal and antibacterial polyamide thermal insulation material and its preparation method. The raw materials of the micro-foamed antifungal and antibacterial polyamide thermal insulation material, by weight, include the following components: 42-47 parts PA66, 8-12 parts PA6, 4.9-5.3 parts foaming agent, 2-3 parts toughening agent, 2-3 parts black masterbatch, 0.3-0.5 parts organosilicon additive, 20.6-22.2 parts glass fiber, and 3-5 parts modified antibacterial masterbatch. This invention achieves uniform dispersion of the modified antibacterial material in the matrix through surface treatment of the loaded material, avoiding the agglomeration problem caused by direct addition. During the melt extrusion process of masterbatch preparation and molding, the imine network on the surface of the modified antibacterial material undergoes an imine exchange reaction with the terminal amino groups in the polyamide matrix, firmly fixing the antibacterial agent in the thermal insulation material and serving as crosslinking sites, thus enhancing the mechanical properties of the thermal insulation material while making the antibacterial effect more durable and stable.

Description

Technical Field

[0001] This invention relates to the field of polyamide thermal insulation materials technology, specifically to a micro-foamed, mildew-proof, and antibacterial polyamide thermal insulation material and its preparation method. Background Technology

[0002] Polyamide thermal insulation materials are composite thermal insulation materials made by adding glass fiber, mineral powder, etc., to polyamide as a base. Their core function is to block thermal bridges in building doors and windows or industrial equipment through low thermal conductivity. While polyamide has excellent mechanical properties, it is prone to bacterial growth in humid environments, posing a threat to the environment and human health. Blending antibacterial agents with polyamide and then molding them can impart antibacterial effects to polyamide thermal insulation materials. Common antibacterial agents are divided into organic and inorganic types. Organic antibacterial agents have poor heat resistance and are easily hydrolyzed; in comparison, inorganic antibacterial agents such as silver ions and zinc ion compounds have longer antibacterial effects and higher stability, making them more suitable for polyamide substrates.

[0003] The application, CN201811252879.3, entitled "Antibacterial Thermal Insulation Strip Material for Thermally Broken Aluminum Alloy Doors and Windows," uses nano-silver, aluminosilicates, silane coupling agents, and polymer waxes as long-lasting antibacterial additives. However, the dispersion effect in nylon resin is poor, and the high-temperature resistance of the silane coupling agent is slightly inferior, resulting in relatively more internal defects in the thermal insulation strip and reduced strength. Currently, most train components such as luggage racks and air conditioning vent grilles on high-speed trains are made of metal materials, which, while strong, are heavy. Developing high-strength, mildew-resistant, and antibacterial polyamide thermal insulation materials can replace the currently used metal luggage racks or air conditioning vent grilles. This not only reduces the weight of high-speed trains and saves energy and emissions but also inhibits the growth of mold in humid and hot environments, playing a vital role in improving the environmental quality inside trains. Summary of the Invention

[0004] The purpose of this invention is to provide a micro-foamed antifungal and antibacterial polyamide thermal insulation material and its preparation method, so as to achieve uniform dispersion of inorganic antibacterial agents in polyamide thermal insulation material, and improve its mechanical properties while satisfying the antibacterial and antifungal properties of polyamide thermal insulation material.

[0005] To achieve the above objectives, the present invention provides a micro-foamed anti-mildew and antibacterial polyamide thermal insulation material and its preparation method. The raw materials of the micro-foamed anti-mildew and antibacterial polyamide thermal insulation material include the following components by weight: 42-47 parts of PA66, 8-12 parts of PA6, 4.9-5.3 parts of foaming agent, 2-3 parts of toughening agent, 2-3 parts of black masterbatch, 0.3-0.5 parts of organosilicon additive, 20.6-22.2 parts of glass fiber, and 3-5 parts of modified antibacterial masterbatch.

[0006] Preferably, the PA66, PA6, black masterbatch and modified antibacterial masterbatch are all pre-treated by drying at 120-130°C before use to ensure that the moisture content is <0.02%.

[0007] Preferably, the foaming agent is azodicarbonamide; the toughening agent is maleic anhydride-grafted POE; the organosilicon additive is silicone powder with a silicon content of 70%; and the glass fiber has a diameter of 7-13 μm and a length of 0.5-1 mm.

[0008] The preparation method of the modified antibacterial masterbatch includes the following steps: S1, Load Zeolite powder is activated at 320-350℃ for 3-4 hours in a muffle furnace. After cooling, it is ground to ≤2μm to obtain activated zeolite powder. The activated zeolite powder is added to a mixed solution of silver nitrate and zinc nitrate. The pH is adjusted to 4.5-5.5 with dilute nitric acid solution. The mixture is stirred and impregnated at 60-70℃ in the dark for 2-3 hours. After washing with water, drying, sintering, and cooling, the loaded material is obtained.

[0009] Preferably, in the mixed solution of silver nitrate and zinc nitrate, the concentration of silver nitrate is 0.05–0.1 mol / L, the concentration of zinc nitrate is 0.2–0.3 mol / L, and the concentration of the dilute nitric acid solution is 0.1–0.5 mol / L.

[0010] Preferably, the solid-liquid ratio of the activated zeolite powder to the mixed solution of silver nitrate and zinc nitrate is 1g:10-15mL.

[0011] Preferably, the drying temperature is 80-90°C and the drying time is 4-8 hours.

[0012] Preferably, the sintering temperature is 400–600°C, the holding time is 2–3 h, and the heating rate is 3–6°C / min.

[0013] S2, Surface Treatment Anhydrous N,N-dimethylacetamide and terephthalaldehyde were added to a reaction vessel and stirred for 10–15 min. Ethylenediamine and triethylenetetramine were added under nitrogen atmosphere, and the reaction was carried out at 50–60 °C for 3–4 h to obtain a linear polyimide solution. The linear polyimide solution was cooled to room temperature, and then 2,2'-bis(trifluoromethyl)diaminobiphenyl and an acidic catalyst were added to the linear polyimide solution and stirred for 20–30 min. The loading material was then added and impregnated for 30–50 min. After impregnation, the material was removed and vacuum dried to obtain the modified antibacterial material.

[0014] Preferably, the molar ratio of terephthalaldehyde, ethylenediamine, triethylenetetramine and 2,2'-bis(trifluoromethyl)diaminobiphenyl is 1:0.7-0.8:0.2-0.3:0.15-0.2.

[0015] Preferably, the solid-liquid ratio of terephthalaldehyde and anhydrous N,N-dimethylacetamide is 1g:12-15mL.

[0016] Preferably, the acidic catalyst is trifluoroacetic acid or p-toluenesulfonic acid, and the amount added is 5 to 7% of the mass of 2,2'-bis(trifluoromethyl)diaminobiphenyl.

[0017] Preferably, the amount of the load material added is 15-20% of the mass of the linear polyimide solution.

[0018] Preferably, the vacuum drying temperature is 120–140°C and the time is 4–6 hours.

[0019] First, terephthalaldehyde reacts with the primary amino groups of ethylenediamine and triethylenetetramine to generate linear polyimide. Under high-temperature vacuum drying, anhydrous N,N-dimethylacetamide solvent gradually evaporates. Due to the combined effects of high temperature and catalyst, the amino groups on the 2,2'-bis(trifluoromethyl)diaminobiphenyl impregnated on the surface of the supported material undergo an imine exchange reaction with the imine bonds of the linear polyimide to generate aromatic imine bonds, which crosslink in situ on the surface of the supported material, forming a crosslinked network film. The rigid aromatic crosslinking sites and the flexible aliphatic segments provided by ethylenediamine and triethylenetetramine endow the crosslinked network film with better flexibility. The residual secondary amine groups of triethylenetetramine and the hydroxyl groups between zeolites form a hydrogen bond network, making the bond between the crosslinked network film and the zeolite stronger. The introduction of aromatic rings improves the heat resistance of the crosslinked network film, while the introduction of fluorocarbon chains improves the hydrophobicity and dispersibility of the modified antibacterial material, inhibits the water absorption characteristics of zeolite in the supported material, and avoids increasing the overall water absorption of the polyamide insulation material.

[0020] S3. Preparation of modified antibacterial masterbatch The modified antibacterial material, PA6, and antioxidant are mixed evenly and then melt-extruded through a twin-screw extruder. After cooling, the mixture is granulated and vacuum-dried to obtain the antibacterial masterbatch.

[0021] Preferably, the mass ratio of the modified antibacterial material, PA6, and antioxidant is 20-25:75-80:0.2-0.4.

[0022] Preferably, the antioxidant is one or more of antioxidant 168 and antioxidant 1098.

[0023] Preferably, the temperatures of each zone in the melt extrusion are: Zone 1 225-235℃, Zone 2 240-250℃, Zone 3 235-245℃, die head 230-240℃, and rotation speed 100-150 r / min.

[0024] Preferably, the vacuum drying temperature is 80-90°C and the time is 6-8 hours.

[0025] The preparation method of the micro-foamed anti-mildew and antibacterial polyamide thermal insulation material is as follows: PA6, PA66, toughening agent, black masterbatch, silicone additive, and modified antibacterial masterbatch are mixed evenly and fed into the main feed port of a twin-screw extruder. Glass fiber is fed into the side feed port of the twin-screw extruder. After melt extrusion granulation, the mixture is dried to obtain mixed granules. The mixed granules and foaming agent are mixed evenly and then fed into a single-screw extruder for extrusion molding through a die. After cutting and processing, micro-foamed anti-mildew and antibacterial polyamide thermal insulation material is obtained.

[0026] Preferably, the temperatures of each zone in the melt extrusion are: zone 1 250-260℃, zone 2 265-275℃, zone 3 270-280℃, die head 260-270℃, and rotation speed 100-150 r / min.

[0027] Preferably, the extrusion molding temperature is 265-275℃, the screw speed is 30-60 r / min, the material residence time is 1.5-3 min, the traction speed is 10-20 m / min, and the cooling water temperature is 30-45℃.

[0028] By adopting the above technical solution, the technical effect achieved by the present invention is as follows: 1. The micro-foamed, mildew-proof, and antibacterial polyamide thermal insulation material prepared by this invention has a density of <1.3 g / cm³. 3 It meets the lightweighting standards of GB / T1033.1-2008; it has good mechanical properties, with tensile strength of 119-131 MPa, flexural strength of 150-162 MPa, and elongation at break of 4.2-4.9%; it has more stable performance, with water absorption of <1% (measured according to GB / T 1034-2008) and a coefficient of linear expansion of <8×10⁻⁶. -5 / ℃ (measured according to GB / T 1036-2008), heat distortion temperature >240℃ (measured according to GB / T1634.1-2019), meeting the performance requirements of products such as metal luggage racks or air conditioning vent grilles.

[0029] 2. The micro-foamed antifungal and antibacterial polyamide thermal insulation material prepared by this invention has excellent antibacterial effect, with an inhibition rate of more than 99% against Escherichia coli (as determined according to GB / T 31402-2015); the antibacterial effect is long-lasting, and the average decrease in inhibition rate after a heat aging test at 140℃ for 1000h is less than 1%.

[0030] 3. By treating the surface of the load material, the modified antibacterial material is uniformly dispersed in the matrix, avoiding the agglomeration problem caused by direct addition. During the melt extrusion process of masterbatch preparation and molding, the imine network on the surface of the modified antibacterial material undergoes an imine exchange reaction with the terminal amino groups in the polyamide matrix. The antibacterial agent is firmly fixed in the thermal insulation material through chemical bonding and serves as a local crosslinking site. This not only enhances the network structure of the thermal insulation material but also makes the antibacterial effect more durable and stable.

[0031] 4. The addition of toughening agent improves the interfacial bonding between glass fiber and PA; organosilicon additive reduces the surface tension of the melt and promotes nucleation; the zeolite in the modified antibacterial material is modified by fluorocarbon chain to reduce surface energy, and works synergistically with organosilicon additive to form a uniform closed-cell micro-foam structure from the gas generated by the decomposition of foaming agent, thereby reducing the density increase caused by the addition of glass fiber. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1: A micro-foamed anti-mildew and antibacterial polyamide thermal insulation material and its preparation method. The raw materials of the micro-foamed anti-mildew and antibacterial polyamide thermal insulation material include the following components by weight: 45.7 parts of PA66, 10 parts of PA6, 5.2 parts of foaming agent, 2.7 parts of toughening agent, 2 parts of black masterbatch, 0.4 parts of organosilicon additive, 21.6 parts of glass fiber, and 4 parts of modified antibacterial masterbatch.

[0034] The PA66, PA6, black masterbatch, and modified antibacterial masterbatch are all pre-treated by drying at 120℃ before use to ensure that the moisture content is <0.02%.

[0035] The foaming agent is azodicarbonamide; the toughening agent is maleic anhydride-grafted POE; the organosilicon additive is silicone powder with a silicon content of 70%; the glass fiber has a diameter of 10 μm and a length of 0.7 mm.

[0036] The preparation method of the modified antibacterial masterbatch includes the following steps: S1, Load 4A zeolite powder was activated at 340℃ for 3.5h in a muffle furnace, and after cooling, it was ground to ≤2μm to obtain activated zeolite powder. The activated zeolite powder was added to a mixed solution of silver nitrate and zinc nitrate, and the pH was adjusted to 5 with dilute nitric acid solution. The mixture was stirred and impregnated at 65℃ in the dark for 2.5h, and then washed with water, dried, sintered and cooled to obtain the loaded material.

[0037] In the mixed solution of silver nitrate and zinc nitrate, the concentration of silver nitrate is 0.08 mol / L and the concentration of zinc nitrate is 0.25 mol / L; the concentration of the dilute nitric acid solution is 0.3 mol / L.

[0038] The solid-liquid ratio of the mixed solution of activated zeolite powder, silver nitrate, and zinc nitrate is 1 g: 12 mL.

[0039] The drying temperature is 85℃ and the time is 6 hours.

[0040] The sintering temperature is 500℃, the holding time is 2.5h, and the heating rate is 4℃ / min.

[0041] S2, Surface Treatment Anhydrous N,N-dimethylacetamide and terephthalaldehyde were added to a reaction vessel and stirred for 15 min. Ethylenediamine and triethylenetetramine were added under nitrogen atmosphere, and the reaction was carried out at 55 °C for 3.5 h to obtain a linear polyimide solution. The linear polyimide solution was cooled to room temperature, and then 2,2'-bis(trifluoromethyl)diaminobiphenyl and an acidic catalyst were added to the linear polyimide solution and stirred for 25 min. The loading material was then added and impregnated for 40 min. After impregnation, the material was removed and vacuum dried to obtain the modified antibacterial material.

[0042] The molar ratio of terephthalaldehyde, ethylenediamine, triethylenetetramine, and 2,2'-bis(trifluoromethyl)diaminobiphenyl is 1:0.75:0.25:0.18.

[0043] The solid-liquid ratio of terephthalaldehyde and anhydrous N,N-dimethylacetamide is 1 g: 14 mL.

[0044] The acidic catalyst is p-toluenesulfonic acid, and the amount added is 6% of the mass of 2,2'-bis(trifluoromethyl)diaminobiphenyl.

[0045] The amount of the load material added is 18% of the mass of the linear polyimide solution.

[0046] The vacuum drying temperature is 130℃ and the time is 5 hours.

[0047] S3. Preparation of modified antibacterial masterbatch The modified antibacterial material, PA6, and antioxidant are mixed evenly and then melt-extruded through a twin-screw extruder. After cooling, the mixture is granulated and vacuum-dried to obtain the antibacterial masterbatch.

[0048] The mass ratio of the modified antibacterial material, PA6, and antioxidant is 23:77:0.3.

[0049] The antioxidants are antioxidant 168 and antioxidant 1098 in a mass ratio of 1:1.

[0050] The temperatures of each zone in the melt extrusion process are: Zone 1 230℃, Zone 2 245℃, Zone 3 240℃, die head 235℃, and rotation speed 120r / min.

[0051] The vacuum drying temperature is 85°C and the time is 7 hours.

[0052] The preparation method of the micro-foamed anti-mildew and antibacterial polyamide thermal insulation material is as follows: PA6, PA66, toughening agent, black masterbatch, silicone additive, and modified antibacterial masterbatch are mixed evenly and fed into the main feed port of a twin-screw extruder. Glass fiber is fed into the side feed port of the twin-screw extruder. After melt extrusion granulation, the mixture is dried to obtain mixed granules. The mixed granules and foaming agent are mixed evenly and then fed into a single-screw extruder for extrusion molding through a die. After cutting and processing, micro-foamed anti-mildew and antibacterial polyamide thermal insulation material is obtained.

[0053] The temperatures of each zone in the melt extrusion process are: Zone 1 255℃, Zone 2 270℃, Zone 3 275℃, and die head 265℃, with a rotation speed of 120 r / min.

[0054] The extrusion molding temperature is 270℃, the screw speed is 45r / min, the material residence time is 2.5min, and the traction speed is 15m / min; the cooling water temperature is 45℃ in the first stage and 35℃ in the second stage.

[0055] Example 2: A micro-foamed anti-mildew and antibacterial polyamide thermal insulation material and its preparation method. The raw materials of the micro-foamed anti-mildew and antibacterial polyamide thermal insulation material include the following components by weight: 42 parts of PA66, 12 parts of PA6, 4.9 parts of foaming agent, 2 parts of toughening agent, 2.5 parts of black masterbatch, 0.3 parts of organosilicon additive, 20.6 parts of glass fiber, and 3 parts of modified antibacterial masterbatch.

[0056] The PA66, PA6, black masterbatch, and modified antibacterial masterbatch are all pre-treated by drying at 120℃ before use to ensure that the moisture content is <0.02%.

[0057] The foaming agent is azodicarbonamide; the toughening agent is maleic anhydride-grafted POE; the organosilicon additive is silicone powder with a silicon content of 70%; the glass fiber has a diameter of 10 μm and a length of 0.7 mm.

[0058] The preparation method of the modified antibacterial masterbatch includes the following steps: S1, Load 4A zeolite powder was activated at 320℃ for 4 hours in a muffle furnace. After cooling, it was ground to ≤2μm to obtain activated zeolite powder. The activated zeolite powder was added to a mixed solution of silver nitrate and zinc nitrate. The pH was adjusted to 4.5 with dilute nitric acid solution. The mixture was stirred and impregnated at 70℃ in the dark for 2 hours. After washing with water, drying, sintering, and cooling, the loaded material was obtained.

[0059] In the mixed solution of silver nitrate and zinc nitrate, the concentration of silver nitrate is 0.05 mol / L and the concentration of zinc nitrate is 0.2 mol / L; the concentration of the dilute nitric acid solution is 0.5 mol / L.

[0060] The solid-liquid ratio of the mixed solution of activated zeolite powder, silver nitrate, and zinc nitrate is 1 g: 10 mL.

[0061] The drying temperature is 80℃ and the time is 8 hours.

[0062] The sintering temperature is 400℃, the holding time is 3h, and the heating rate is 3℃ / min.

[0063] S2, Surface Treatment Anhydrous N,N-dimethylacetamide and terephthalaldehyde were added to a reaction vessel and stirred for 10 min. Ethylenediamine and triethylenetetramine were added under nitrogen atmosphere, and the reaction was carried out at 50 °C for 3 h to obtain a linear polyimide solution. The linear polyimide solution was cooled to room temperature, and then 2,2'-bis(trifluoromethyl)diaminobiphenyl and an acidic catalyst were added to the linear polyimide solution and stirred for 20 min. The loading material was then added and impregnated for 30 min. After impregnation, the material was removed and vacuum dried to obtain the modified antibacterial material.

[0064] The molar ratio of terephthalaldehyde, ethylenediamine, triethylenetetramine, and 2,2'-bis(trifluoromethyl)diaminobiphenyl is 1:0.7:0.3:0.15.

[0065] The solid-liquid ratio of terephthalaldehyde and anhydrous N,N-dimethylacetamide is 1 g: 12 mL.

[0066] The acidic catalyst is p-toluenesulfonic acid, and the amount added is 5% of the mass of 2,2'-bis(trifluoromethyl)diaminobiphenyl.

[0067] The amount of the load material added is 15% of the mass of the linear polyimide solution.

[0068] The vacuum drying temperature is 120℃ and the time is 6 hours.

[0069] S3. Preparation of modified antibacterial masterbatch The modified antibacterial material, PA6, and antioxidant are mixed evenly and then melt-extruded through a twin-screw extruder. After cooling, the mixture is granulated and vacuum-dried to obtain the antibacterial masterbatch.

[0070] The mass ratio of the modified antibacterial material, PA6, and antioxidant is 20:80:0.2.

[0071] The antioxidants are antioxidant 168 and antioxidant 1098 in a mass ratio of 1:1.

[0072] The temperatures of each zone in the melt extrusion process are: Zone 1 225℃, Zone 2 240℃, Zone 3 235℃, and die head 230℃, with a rotation speed of 100 r / min.

[0073] The vacuum drying temperature is 80℃ and the time is 8 hours.

[0074] The preparation method of the micro-foamed anti-mildew and antibacterial polyamide thermal insulation material is as follows: PA6, PA66, toughening agent, black masterbatch, silicone additive, and modified antibacterial masterbatch are mixed evenly and fed into the main feed port of a twin-screw extruder. Glass fiber is fed into the side feed port of the twin-screw extruder. After melt extrusion granulation, the mixture is dried to obtain mixed granules. The mixed granules and foaming agent are mixed evenly and then fed into a single-screw extruder for extrusion molding through a die. After cutting and processing, micro-foamed anti-mildew and antibacterial polyamide thermal insulation material is obtained.

[0075] The temperatures of each zone in the melt extrusion process are: Zone 1 250℃, Zone 2 265℃, Zone 3 270℃, and die head 260℃, with a rotation speed of 100 r / min.

[0076] The extrusion molding temperature is 275℃, the screw speed is 30r / min, the material residence time is 1.5min, and the traction speed is 10m / min; the cooling water temperature is 40℃ in the first stage and 30℃ in the second stage.

[0077] Example 3: A micro-foamed anti-mildew and antibacterial polyamide thermal insulation material and its preparation method. The raw materials of the micro-foamed anti-mildew and antibacterial polyamide thermal insulation material include the following components by weight: 47 parts PA66, 8 parts PA6, 5.3 parts foaming agent, 3 parts toughening agent, 3 parts black masterbatch, 0.5 parts organosilicon additive, 22.2 parts glass fiber, and 5 parts modified antibacterial masterbatch.

[0078] The PA66, PA6, black masterbatch, and modified antibacterial masterbatch are all pre-treated by drying at 130℃ before use to ensure that the moisture content is <0.02%.

[0079] The foaming agent is azodicarbonamide; the toughening agent is maleic anhydride-grafted POE; the organosilicon additive is silicone powder with a silicon content of 70%; the glass fiber has a diameter of 10 μm and a length of 0.7 mm.

[0080] The preparation method of the modified antibacterial masterbatch includes the following steps: S1, Load 4A zeolite powder was activated at 350℃ for 3 hours in a muffle furnace. After cooling, it was ground to ≤2μm to obtain activated zeolite powder. The activated zeolite powder was added to a mixed solution of silver nitrate and zinc nitrate. The pH was adjusted to 5.5 with dilute nitric acid solution. The mixture was stirred and impregnated at 60℃ in the dark for 3 hours. After washing with water, drying, sintering, and cooling, the loaded material was obtained.

[0081] In the mixed solution of silver nitrate and zinc nitrate, the concentration of silver nitrate is 0.1 mol / L and the concentration of zinc nitrate is 0.3 mol / L; the concentration of the dilute nitric acid solution is 0.1 mol / L.

[0082] The solid-liquid ratio of the mixed solution of activated zeolite powder, silver nitrate, and zinc nitrate is 1 g: 15 mL.

[0083] The drying temperature is 90℃ and the time is 4 hours.

[0084] The sintering temperature is 600℃, the holding time is 2h, and the heating rate is 6℃ / min.

[0085] S2, Surface Treatment Anhydrous N,N-dimethylacetamide and terephthalaldehyde were added to a reaction vessel and stirred for 10 min. Ethylenediamine and triethylenetetramine were added under nitrogen atmosphere, and the reaction was carried out at 60 °C for 4 h to obtain a linear polyimide solution. The linear polyimide solution was cooled to room temperature, and then 2,2'-bis(trifluoromethyl)diaminobiphenyl and an acidic catalyst were added to the linear polyimide solution and stirred for 30 min. The loading material was then added and impregnated for 50 min. After impregnation, the material was removed and vacuum dried to obtain the modified antibacterial material.

[0086] The molar ratio of terephthalaldehyde, ethylenediamine, triethylenetetramine, and 2,2'-bis(trifluoromethyl)diaminobiphenyl is 1:0.8:0.2:0.2.

[0087] The solid-liquid ratio of terephthalaldehyde and anhydrous N,N-dimethylacetamide is 1 g: 15 mL.

[0088] The acidic catalyst is p-toluenesulfonic acid, and the amount added is 7% of the mass of 2,2'-bis(trifluoromethyl)diaminobiphenyl.

[0089] The amount of the load material added is 20% of the mass of the linear polyimide solution.

[0090] The vacuum drying temperature is 140℃ and the time is 4 hours.

[0091] S3. Preparation of modified antibacterial masterbatch The modified antibacterial material, PA6, and antioxidant are mixed evenly and then melt-extruded through a twin-screw extruder. After cooling, the mixture is granulated and vacuum-dried to obtain the antibacterial masterbatch.

[0092] The mass ratio of the modified antibacterial material, PA6, and antioxidant is 25:75:0.4.

[0093] The antioxidants are antioxidant 168 and antioxidant 1098 in a mass ratio of 1:1.

[0094] The temperatures of each zone in the melt extrusion process are: Zone 1 235℃, Zone 2 250℃, Zone 3 245℃, and die head 240℃, with a rotation speed of 150 r / min.

[0095] The vacuum drying temperature is 90℃ and the time is 6 hours.

[0096] The preparation method of the micro-foamed anti-mildew and antibacterial polyamide thermal insulation material is as follows: PA6, PA66, toughening agent, black masterbatch, silicone additive, and modified antibacterial masterbatch are mixed evenly and fed into the main feed port of a twin-screw extruder. Glass fiber is fed into the side feed port of the twin-screw extruder. After melt extrusion granulation, the mixture is dried to obtain mixed granules. The mixed granules and foaming agent are mixed evenly and then fed into a single-screw extruder for extrusion molding through a die. After cutting and processing, micro-foamed anti-mildew and antibacterial polyamide thermal insulation material is obtained.

[0097] The temperatures of each zone in the melt extrusion process are: Zone 1 260℃, Zone 2 275℃, Zone 3 280℃, and die head 270℃, with a rotation speed of 150 r / min.

[0098] The extrusion molding temperature is 265℃, the screw speed is 60r / min, the material residence time is 3min, and the traction speed is 20m / min; the cooling water temperature is 45℃ in the first stage and 30℃ in the second stage.

[0099] Comparative Example 1: A representative example, Example 1, was selected. Step S2 was omitted, and in Step S3, antibacterial masterbatch was prepared directly using the loading material. All other steps were the same as in Example 1. This example was used as Comparative Example 1.

[0100] Comparative Example 2: A representative example, Example 1, was selected. Step S2 was removed, and the surface of the loaded material was treated with aminosilane coupling agent KH-550 to prepare a modified antibacterial material. All other steps were the same as in Example 1. This example is Comparative Example 2.

[0101] Comparative Example 3: A representative example, Example 1, was selected, and the triethylenetetramine in step S2 was replaced with ethylenediamine. All other aspects were the same as in Example 1. This was used as Comparative Example 3.

[0102] The molds used in Examples 1-3 and Comparative Examples 1-3 were all air conditioning vent grille molds; the performance of the polyamide thermal insulation materials prepared in Examples 1-3 was tested, as shown in Table 1.

[0103] Table 1

[0104] The performance of the polyamide thermal insulation materials prepared in Comparative Examples 1-3 was tested, and the results are shown in Table 2.

[0105] Table 2

[0106] The polyamide thermal insulation materials prepared in Examples 1-3 not only have excellent mechanical properties, but also have long-lasting antibacterial properties.

[0107] Comparative Example 1 used only the supporting material, which had poor dispersion in the polyamide matrix. Furthermore, the zeolite in the supporting material had strong water absorption. Therefore, the mechanical properties and antibacterial rate of the polyamide thermal insulation material prepared in Comparative Example 1 decreased, while the water absorption rate increased. The bonding force between the supporting material and the polyamide matrix was also weak. Comparative Example 2 uses KH550 to treat the load material, which improves the performance compared to Comparative Example 1, but it is still inferior to the imine exchange network structure constructed in Example 1. Therefore, its performance is worse than that of Example 1.

[0108] Comparative Example 3 removed triethylenetetramine and used only ethylenediamine, resulting in the cross-linked network film on the surface of the modified antibacterial material lacking flexible segments and hydrogen bond networks with zeolite hydroxyl groups. During the high-shear extrusion process of twin-screw extrusion, it was prone to breakage and peeling, leading to local defects in the polyamide thermal insulation material. During thermal aging, some antibacterial active ingredients migrated, so its various properties were slightly inferior to those of Example 1.

[0109] Unless otherwise specified, all proportions and percentages mentioned in this invention are mass proportions and mass percentages; all raw materials are commercially available.

[0110] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A micro-foamed, mildew-proof, and antibacterial polyamide thermal insulation material, characterized in that, The raw materials of the micro-foamed anti-mildew and antibacterial polyamide thermal insulation material include the following components by weight: 42-47 parts PA66, 8-12 parts PA6, 4.9-5.3 parts foaming agent, 2-3 parts toughening agent, 2-3 parts black masterbatch, 0.3-0.5 parts organosilicon additive, 20.6-22.2 parts glass fiber, and 3-5 parts modified antibacterial masterbatch; The preparation method of the modified antibacterial masterbatch includes the following steps: S1. Loading: Zeolite powder is placed in a muffle furnace and activated at 320-350℃ for 3-4 hours. After cooling, it is ground to ≤2μm to obtain activated zeolite powder. The activated zeolite powder is added to a mixed solution of silver nitrate and zinc nitrate. The pH is adjusted to 4.5-5.5 with dilute nitric acid solution. The mixture is stirred and impregnated at 60-70℃ in the dark for 2-3 hours. After washing with water, drying, sintering, and cooling, the loaded material is obtained. S2. Surface treatment: Anhydrous N,N-dimethylacetamide and terephthalaldehyde are added to a reaction vessel and stirred for 10-15 min. Ethylenediamine and triethylenetetramine are added under nitrogen atmosphere. After reacting at 50-60℃ for 3-4 h, a linear polyimide solution is obtained. The linear polyimide solution is cooled to room temperature, and then 2,2'-bis(trifluoromethyl)diaminobiphenyl and an acidic catalyst are added to the linear polyimide solution and stirred for 20-30 min. The loading material is then added and impregnated for 30-50 min. After impregnation, the material is removed and vacuum dried to obtain the modified antibacterial material. S3. Preparation of modified antibacterial masterbatch: The modified antibacterial material, PA6 and antioxidant are mixed evenly and then melt-extruded through a twin-screw extruder. After cooling, the mixture is granulated and vacuum dried to obtain the antibacterial masterbatch.

2. The micro-foamed, mildew-proof, and antibacterial polyamide thermal insulation material according to claim 1, characterized in that, In the mixed solution of silver nitrate and zinc nitrate in S1, the concentration of silver nitrate is 0.05–0.1 mol / L, and the concentration of zinc nitrate is 0.2–0.3 mol / L; the concentration of the dilute nitric acid solution is 0.1–0.5 mol / L. The solid-liquid ratio of the mixed solution of activated zeolite powder, silver nitrate, and zinc nitrate in S1 is 1g:10-15mL.

3. The micro-foamed, mildew-proof, and antibacterial polyamide thermal insulation material according to claim 1, characterized in that, The drying temperature in S1 is 80-90℃, and the time is 4-8h; the sintering temperature is 400-600℃, the holding time is 2-3h, and the heating rate is 3-6℃ / min.

4. The micro-foamed, mildew-proof, and antibacterial polyamide thermal insulation material according to claim 1, characterized in that, The molar ratio of terephthalaldehyde, ethylenediamine, triethylenetetramine, and 2,2'-bis(trifluoromethyl)diaminobiphenyl in S2 is 1:0.7-0.8:0.2-0.3:0.15-0.2; The solid-liquid ratio of terephthalaldehyde and anhydrous N,N-dimethylacetamide in S2 is 1g:12-15mL.

5. The micro-foamed, mildew-proof, and antibacterial polyamide thermal insulation material according to claim 1, characterized in that, The acidic catalyst in S2 is trifluoroacetic acid or p-toluenesulfonic acid, and the amount added is 5-7% of the mass of 2,2'-bis(trifluoromethyl)diaminobiphenyl. The amount of the loading material added in S2 is 15-20% of the mass of the linear polyimide solution; The vacuum drying in S2 is performed at a temperature of 120–140°C for 4–6 hours.

6. The micro-foamed, mildew-proof, and antibacterial polyamide thermal insulation material according to claim 1, characterized in that, The mass ratio of modified antibacterial material, PA6, and antioxidant in S3 is 20-25:75-80:0.2-0.4; The antioxidant in S3 is one or more of antioxidant 168 and antioxidant 1098; The temperatures of each zone in the S3 melt extrusion process are: Zone 1 225-235℃, Zone 2 240-250℃, Zone 3 235-245℃, die head 230-240℃, and rotation speed 100-150 r / min. The vacuum drying in S3 is performed at a temperature of 80–90°C for 6–8 hours.

7. The micro-foamed, mildew-proof, and antibacterial polyamide thermal insulation material according to claim 1, characterized in that, The foaming agent is azodicarbonamide; the toughening agent is maleic anhydride-grafted POE; and the organosilicon additive is silicone powder.

8. A method for preparing a micro-foamed, mildew-proof, and antibacterial polyamide thermal insulation material as described in any one of claims 1-7, characterized in that, The preparation method is as follows: PA6, PA66, toughening agent, black masterbatch, organosilicon additive, and modified antibacterial masterbatch are mixed evenly and fed into the main feed port of a twin-screw extruder. Glass fiber is fed into the side feed port of the twin-screw extruder. After melt extrusion granulation, the mixture is dried to obtain mixed granules. The mixed granules and foaming agent are mixed evenly and then fed into a single-screw extruder for extrusion molding through a die. After cutting and processing, micro-foamed anti-mildew and antibacterial polyamide thermal insulation material is obtained.

9. The method for preparing a micro-foamed, mildew-proof, and antibacterial polyamide thermal insulation material according to claim 8, characterized in that, The temperatures of each zone in the melt extrusion process are as follows: Zone 1 250–260℃, Zone 2 265–275℃, Zone 3 270–280℃, and die head 260–270℃, with a rotation speed of 100–150 r / min.

10. The method for preparing a micro-foamed, mildew-proof, and antibacterial polyamide thermal insulation material according to claim 8, characterized in that, The extrusion molding temperature is 265–275°C, the screw speed is 30–60 r / min, the material residence time is 1.5–3 min, the traction speed is 10–20 m / min, and the cooling water temperature is 30–45°C.

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