Antibacterial mildew-proof plastic foot pad and preparation method thereof

Abstract

The invention discloses an antibacterial and mildew-proof plastic foot pad and a preparation method thereof, and relates to the technical field of foot pads. S2, blending the three layers of raw materials; s3, carrying out three-layer co-extrusion molding; and S4, detecting the quality of a finished product. According to the invention, a three-layer structure comprising a base layer, an antibacterial and mildew-proof layer and a protective surface layer can be formed by prefabricating functional master batches, obtaining antibacterial master batches and antifouling master batches, blending three layers of raw materials and co-extruding and forming three layers, complex steps such as multi-layer compounding, chemical crosslinking and nitrogen protection are cancelled, the production process is simplified and the production difficulty is reduced through one-step co-extruding and forming, the production cost is reduced, and the production efficiency is improved. PE is used as a main raw material and is matched with calcium carbonate, talcum powder and an antibacterial and mildew-proof agent, the raw material cost can be reduced, the high antibacterial rate can still be kept after multiple times of water washing, the performance of the foot pad in use can be maintained, dependence on special chemicals is avoided, the raw materials are wide in source and environmentally friendly, and the limitation of raw material selection can be reduced.

Description

Technical Field

[0001] This invention relates to the field of foot pad technology, specifically to an antibacterial and anti-mildew plastic foot pad and its preparation method. Background Technology

[0002] A floor mat is a mat placed in a specific location and has multiple functions. It can be divided into car floor mats, furniture floor mats, etc., and its application is quite widespread.

[0003] For example, Chinese patent CN118514367B discloses a multilayered composite coated foot pad and its preparation method. An antibacterial and flame-retardant impregnation solution is prepared using fluorinated organosilicon polyurethane and composite zinc phytate. The burred fabric composite material is impregnated in the antibacterial and flame-retardant impregnation solution. An organosilicon prepolymer is synthesized using hydroxyl-terminated polydimethylsiloxane and isophorone diisocyanate as raw materials. A hydroxylated fluorinated borneol copolymer, synthesized by free-base polymerization of isoborneol methacrylate, dodecafluoroheptyl methacrylate, and 1-thioglycerol, is used as a chain extender along with quaternized glycogen, and triethanolamine is used as a capping agent to obtain fluorinated organosilicon polyurethane. Zinc phytate is prepared using phytic acid and zinc acetate. Then, Schiff base copolymers are synthesized in a one-pot process using 3,4-dihydroxybenzaldehyde, quaternized glycogen, and DOPO as raw materials. Intermolecular forces are used to coat the zinc phytate, preparing a composite zinc phytate which is then introduced into the flame-retardant and antibacterial impregnation solution as both a flame retardant and an antibacterial agent.

[0004] Although the aforementioned patent solved the problem of the foot pad's short-lasting antibacterial properties and easy bacterial growth and mold by modifying the burr cloth composite material, the preparation of the foot pad requires the addition of multiple raw materials in stages under nitrogen atmosphere with controlled heating and timing. The production process is complex and difficult, which increases the risk of errors and limits the production efficiency of the foot pad. Summary of the Invention

[0005] The purpose of this invention is to provide an antibacterial and anti-mildew plastic foot pad and its preparation method, in order to solve the problem mentioned in the background art that the preparation of fluorinated organosilicon polyurethane in the foot pad preparation process requires the addition of multiple raw materials in stages under a nitrogen atmosphere and controlled time, which is a complex and difficult process, increases the risk of errors, and limits the production efficiency of foot pads.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing an antibacterial and antifungal plastic foot pad, comprising the following steps:

[0007] S1. Pre-made functional masterbatch: The carrier resin, functional additives, dispersants and processing aids are melt-blended and granulated to form functional masterbatch, namely antibacterial masterbatch and antifouling masterbatch;

[0008] S2. Three-layer material blending: The three layers of the foot pad are the base layer, the antibacterial and anti-mildew layer, and the protective surface layer. The raw materials required for the preparation of the three layers are weighed and proportioned separately, and the raw materials for each layer are mixed. The base layer, the antibacterial and anti-mildew layer, and the protective surface layer are respectively made from the following parts by weight of raw materials:

[0009] Base layer: 70-80 parts HDPE, 10-20 parts LDPE, 15-20 parts calcium carbonate, 5-8 parts EVA, 0.5-1 parts antioxidant;

[0010] Antibacterial and antifungal layer: 60-70 parts LDPE, 10-15 parts antibacterial masterbatch, 3-5 parts zinc oxide, 2-3 parts thiabendazole, 5-10 parts talc;

[0011] Protective surface layer: 50-60 parts LDPE, 5-10 parts silicone masterbatch, 8-12 parts nano silica, 1-2 parts hindered amine light stabilizer, 1-2 parts zinc stearate;

[0012] S3, Three-layer co-extrusion molding: Prepare a three-layer co-extrusion mold and a cooling calender unit, feed the raw material into the extrusion equipment, and extrude the three layers into shape;

[0013] S4. Inspect the quality of the finished product: Cut the extruded pre-products into foot pads according to the dimensions, inspect the appearance of the foot pads, and perform performance tests on the foot pads to determine whether the finished product is qualified.

[0014] Preferably, in S1, the antibacterial masterbatch is prepared from the following raw materials in parts by weight: 60-70 parts of carrier resin, 10-15 parts of antibacterial agent, 2-5 parts of dispersant, 0.5-1 part of antioxidant and 0.5-1 part of coupling agent;

[0015] The antifouling masterbatch is made from the following raw materials in parts by weight: 50-60 parts carrier resin, 20-30 parts antifouling agent, 5-10 parts dispersant, and 0.5-1 part temperature-resistant additive.

[0016] Preferably, during the manufacturing of antibacterial masterbatch, the solid quaternary ammonium salt antibacterial agent is screened to remove impurities, premixed with the weighed dispersant / antioxidant for 5 minutes, and carrier LDPE particles are added in a high-speed mixer. The temperature is raised to 50-60°C, and the premixed antibacterial agent, dispersant and antioxidant are added in batches. The mixture is continuously mixed for 15-20 minutes until the material is in uniform granular form. After melt blending and extrusion, the material is pelletized by water-cooled string cutting or underwater pelletizing. Irregular particles are screened out after pelletizing.

[0017] Preferably, during the manufacture of the antifouling masterbatch, the silicone powder undergoes surface treatment by spraying it with a 3% silane coupling agent KH-560 ethanol solution, drying it at 50°C for 2 hours to remove the ethanol, and then granulating it by melt blending and extrusion followed by cooling.

[0018] Preferably, when blending the three layers of raw materials, the following steps are also included:

[0019] S21. Base layer mixing: The base layer raw materials are fed into a high-speed mixer and stirred at 50°C for 10 minutes to disperse the filler, and the discharge test is performed.

[0020] S22, Antibacterial and mildew-proof layer treatment: The raw materials are fed into a mixer and stirred, and 0.5% silane coupling agent KH-550 is added to treat the inorganic filler;

[0021] S23. Protective Surface Dispersion: Set the parameters of the twin-screw extruder to a temperature of 160-180℃ and a speed of 200rpm to pre-disperse the raw materials and conduct a dispersibility test.

[0022] Preferably, during the discharge inspection in S21, visual inspection is conducted to determine whether white calcium carbonate lumps are present. A small sample is burned, and if the residual ash is evenly distributed without aggregation, the recommended dispersibility test is completed.

[0023] Preferably, in S3, the extrusion temperatures are set as follows: base layer 180-190℃, antibacterial layer 170-180℃, and protective layer 160-170℃.

[0024] Preferably, in S3, the screw speeds are: 120 rpm for the base layer, 100 rpm for the antibacterial layer, 150 rpm for the protective layer, and the cooling roller temperature is 50-60℃.

[0025] Preferably, in S4, when performing performance testing on the foot pads, the following is also included:

[0026] A1. Antibacterial performance test: The initial antibacterial rate of the foot pad was tested using the vibration method. Then, the foot pad was subjected to 50 standard washes. After washing, the vibration method test was repeated to test the wash-resistant antibacterial rate.

[0027] A2. Anti-mold performance test: Place the foot pad sample in a petri dish containing agar medium, inoculate with mixed mold spore solution, incubate for 28 days, and observe the surface mold coverage area;

[0028] A3. Anti-fouling performance test: Conduct contact angle test and anti-fouling level test on the foot pads;

[0029] A4. Abrasion resistance test: Use a Martindale abrasion tester with a load of 9 kPa and observe the surface roughness and damage after 50,000 to 100,000 abrasion cycles.

[0030] An antibacterial and anti-mildew plastic foot pad is prepared by a method for preparing an antibacterial and anti-mildew plastic foot pad.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] 1. In this invention, antibacterial masterbatch and antifouling masterbatch can be obtained by pre-fabricating functional masterbatch. Through three-layer raw material blending and three-layer co-extrusion molding, a three-layer structure of base layer, antibacterial and antifungal layer and protective surface layer can be formed. Complex steps such as multi-layer composite, chemical cross-linking and nitrogen protection are eliminated. One-step co-extrusion molding shortens the production cycle, simplifies the production process and production difficulty, reduces the risk of errors, and thus improves the production efficiency of foot pads. Using PE as the main raw material, combined with calcium carbonate, talc powder and antibacterial and antifungal agent, the raw material cost can be reduced.

[0033] 2. In this invention, the antibacterial agent quaternary ammonium salt and the antifungal agent are inorganic and organic compounded to improve washability through physical encapsulation and chemical bonding. After multiple washes, the antibacterial rate can still be maintained, thus maintaining the performance of the foot pad during use. It uses general PE, EVA, etc., avoiding dependence on special chemicals. The raw materials are widely available and environmentally friendly, which can reduce the limitations of raw material selection. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating a method for preparing an antibacterial and antifungal plastic foot pad according to the present invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1: Refer to Figure 1 As shown: A method for preparing antibacterial and anti-mildew plastic foot pads, through pre-made functional masterbatch, three-layer raw material blending and three-layer co-extrusion molding, solves the problem that the preparation of fluorinated organosilicon polyurethane in the foot pad manufacturing process requires staged heating and time-controlled addition of multiple raw materials under nitrogen atmosphere, which is complicated, difficult, and prone to errors, thus limiting the production efficiency of foot pads.

[0037] I. Core Working Principle: Collaborative Design of Functional Layering and Process Simplification

[0038] This patent constructs a technical system of "high-efficiency production, synergistic performance, and controllable cost" through four core stages: "pre-made functional masterbatch → three-layer blending modification → one-step co-extrusion molding → system testing and verification." The core logic is as follows:

[0039] Avoiding complex chemical synthesis: Physical blending replaces the chemical polymerization of fluorinated organosilicon polyurethane in the original patent. Through functional masterbatch pre-dispersion technology, functional additives such as antibacterial agents and antifouling agents are uniformly loaded into general-purpose PE resin.

[0040] Layering provides differentiated functions: the base layer provides mechanical support and low cost, the antibacterial and anti-mildew layer achieves long-lasting antibacterial and anti-mildew properties, the protective surface layer enhances wear resistance and stain resistance, and the three layers complement each other in performance through raw material formulation optimization and interface treatment.

[0041] Standardized plastic processing technology: relying on mature melt blending and three-layer co-extrusion technologies, no special equipment or harsh reaction conditions (such as nitrogen protection and high-temperature polymerization) are required, which significantly reduces the production threshold.

[0042] II. Detailed Explanation of the Step-by-Step Working Principle

[0043] 1. Pre-made functional masterbatch: pre-dispersion of additives and modular production

[0044] Antibacterial masterbatch:

[0045] Technical approach: Quaternary ammonium salt antibacterial agents (such as benzalkonium bromide) are mixed with LDPE carrier at high speed and then melt-extruded and granulated to form a masterbatch in which the antibacterial agent is uniformly dispersed.

[0046] Key function: It solves the agglomeration problem when antibacterial agents are added directly, and can be quickly and evenly distributed when mixed with antibacterial and antifungal layer raw materials, while avoiding the moisture absorption and failure of quaternary ammonium salts.

[0047] Antifouling masterbatch:

[0048] Technical approach: Silicone powder is surface-treated with silane coupling agent (KH-560), then melt-blended and extruded with LDPE to form a low surface energy antifouling masterbatch.

[0049] Key function: After the silicone powder is evenly dispersed, it gives the protective surface a "lotus leaf effect", making it difficult for water stains and oil stains to adhere and preventing nanoscale agglomeration.

[0050] 2. Three-layer raw material blending: differentiated formulation design and interface optimization

[0051] Base layer (high-strength support layer):

[0052] Raw material logic: HDPE (high strength) + LDPE (flexibility) + calcium carbonate (low-cost filler) + EVA (toughening agent). After being treated with silane coupling agent (KH-560), the interfacial bonding force between calcium carbonate and PE resin is improved, avoiding filler agglomeration.

[0053] Key process points: High-speed mixing at 60℃ and 600rpm ensures that the surface of calcium carbonate is completely coated with resin, improving the tensile strength and low-temperature toughness of the base layer.

[0054] Antibacterial and antifungal layer (core functional layer):

[0055] Raw material logic: LDPE carrier + antibacterial masterbatch (quaternary ammonium salt) + inorganic antifungal agent (zinc oxide) + organic antifungal agent (thiabendazole). The inorganic-organic compound covers a variety of molds, and talc improves the surface smoothness.

[0056] Key process points: Low-temperature high-shear mixing at 55℃ and 800rpm to avoid high-temperature degradation of antibacterial / mildew inhibitors; treatment with silane coupling agent (KH-550) to improve water washability.

[0057] Protective surface layer (wear-resistant and anti-fouling layer):

[0058] Raw material logic: LDPE carrier + antifouling masterbatch (silicone powder) + nano silica (wear-resistant filler). After being modified with stearic acid, nano silica can effectively improve dispersion.

[0059] Key process points: High-shear mixing at 65℃ and 1000rpm ensures uniform distribution of nanoparticles and silicone powder; twin-screw pre-dispersion improves surface hardness and wear resistance.

[0060] 3. Three-layer co-extrusion molding: one-step compounding and precise parameter control

[0061] Equipment and processes:

[0062] Three-layer co-extrusion die: Independent feed inlets control the thickness of each layer, and coat hanger-type die head ensures uniform melt distribution.

[0063] Temperature control: base layer (185℃, HDPE fully melted), antibacterial layer (180℃, to protect the activity of quaternary ammonium salt), protective layer (160℃, to prevent silicone powder oxidation), cooling roller (50℃) for rapid shaping, improving interlayer adhesion strength.

[0064] Core advantages: Eliminating the multi-layer composite and chemical cross-linking of the original patent, the production cycle is shortened from 12 hours to 2 hours, reducing equipment investment.

[0065] 4. Finished Product Inspection: Multi-dimensional Verification and Quality Closed Loop

[0066] Functional testing: The antibacterial rate is measured by the oscillation method, the mold resistance level (level 0) is measured by the mold culture method, the contact angle / fouling resistance level is measured, and the Martindale abrasion resistance is measured. All of these tests adopt national standard methods and the equipment is widely used.

[0067] Physical and environmental testing: Mechanical indicators such as tensile strength, low-temperature bending, and high-temperature dimensional stability, as well as environmental indicators such as heavy metals and phthalates, to ensure compliance with standards such as GB4806.7-2016 and eliminate the risk of fluorides.

[0068] Example 2: Refer to Figure 1 As shown: A method for preparing an antibacterial and anti-mildew plastic foot pad includes the following steps:

[0069] Step 1: Pre-fabrication of functional masterbatches: The carrier resin, functional additives, dispersants and processing aids are melt-blended and granulated to produce functional masterbatches, namely antibacterial masterbatches and antifouling masterbatches;

[0070] In the preparation of antibacterial masterbatch, it is made from the following raw materials in parts by weight: 70 parts carrier resin, 15 parts antibacterial agent, 5 parts dispersant, 1 part antioxidant and 1 part coupling agent;

[0071] If the quaternary ammonium salt antibacterial agent is a solid powder, remove impurities by passing it through an 80-mesh sieve; if it is a liquid, it can be first mixed with a small amount of LDPE granules for granulation, premixed with the weighed dispersant / antioxidant for 5 minutes, and the carrier LDPE granules are added in a high-speed mixer. The temperature is raised to 60°C, and the premixed antibacterial agent, dispersant and antioxidant are added in batches. The mixture is continuously mixed for 15-20 minutes until the material is in uniform granule form. After melt blending and extrusion, it is pelletized by water-cooled strip cutting or underwater pelletizing. Irregular particles are removed by sieving after pelletizing.

[0072] Temperature settings for the twin-screw extruder: Zone 1 (feeding section) 145℃, Zone 2 (melting section) 165℃, Zone 3 (homogenization section) 175℃, die 180℃, screw speed: 200rpm, pelletizing via water-cooled strip cutting or underwater pelletizing.

[0073] In the preparation of antifouling masterbatch, it is made from the following raw materials in parts by weight: 60 parts carrier resin, 30 parts antifouling agent, 10 parts dispersant, and 1 part heat-resistant additive;

[0074] For surface treatment of silicone powder, spray the silicone powder with a 3% silane coupling agent KH-560 ethanol solution, dry at 50°C for 2 hours, and remove the ethanol.

[0075] The twin-screw extruder is equipped with a vacuum exhaust port to remove air adsorbed by silicone powder. Temperature settings: Zone 1 135℃, Zone 2 155℃, Zone 3 165℃, Die 175℃, Screw speed: 225rpm.

[0076] Feeding method: LDPE is added to the main feed port, and treated silicone powder and dispersant are added to the side feed port to avoid silicone powder accumulation in the feeding section. Underwater pelleting is used to prevent silicone powder from sticking to the blade, and the surface is smooth without white spots (white spots are silicone powder agglomeration).

[0077] Step 2: Blending of the three layers: The three layers of the foot pad are the base layer, the antibacterial and antifungal layer, and the protective surface layer. Weigh and proportion the raw materials required for each layer, and mix them. The base layer, antibacterial and antifungal layer, and protective surface layer are each made from the following parts by weight:

[0078] Base layer: 70 parts HDPE, 20 parts LDPE, 15 parts calcium carbonate, 8 parts EVA, 1 part antioxidant;

[0079] Antibacterial and antifungal layer: 65 parts LDPE, 12 parts antibacterial masterbatch, 4 parts zinc oxide, 2 parts thiabendazole, and 8 parts talc.

[0080] Protective surface layer: 55 parts LDPE, 8 parts silicone masterbatch, 10 parts nano silica, 1.5 parts hindered amine light stabilizer, 1 part zinc stearate;

[0081] The three-layer raw material blending process also includes the following steps:

[0082] 21. Base layer mixing: Add 15 parts of calcium carbonate to a high-speed mixer, add 0.5 parts of silane coupling agent KH-560, stir at 50°C for 10 minutes to allow the hydroxyl groups on the surface of calcium carbonate to react with the coupling agent, add 70 parts of HDPE and 20 parts of LDPE granules in sequence, start the mixer at 300 rpm, mix at room temperature for 5 minutes until the resin is evenly dispersed, add 8 parts of EVA and 1 part of antioxidant 1010, continue mixing for 5 minutes, slowly add the treated calcium carbonate to the mixer, raise the temperature to 60°C, increase the speed to 600 rpm, mix for 15 minutes, and perform discharge testing;

[0083] 22. Antibacterial and antifungal layer treatment: Pass 4 parts zinc oxide and 8 parts talc powder through a 100-mesh sieve to remove impurities. Add 0.3 parts zinc stearate (dispersant) and stir at high speed for 5 minutes. Add 65 parts LDPE granules, start the mixer at 400 rpm, and mix at room temperature for 3 minutes. Add 12 parts antibacterial masterbatch and mix for 5 minutes. Add pretreated zinc oxide + talc powder and 2 parts thiabendazole in batches. Heat to 55℃, increase the speed to 800 rpm, and mix for 20 minutes. If the antifungal effect requires long-term water resistance, add 0.5 parts silane coupling agent KH-550 to react with the inorganic filler to form chemical bonds.

[0084] 23. Surface Dispersion for Protective Layer: Add 10 parts of nano-silica to the reactor, add 2 parts of stearic acid (melting point 69℃, heat to 75℃ to melt), stir at high speed for 30 minutes, cool to room temperature, pass through a 200-mesh sieve to complete the surface modification of nano-silica, add 55 parts of LDPE particles, add 8 parts of silicone masterbatch, mix at room temperature for 10 minutes, add the modified nano-silica, 1.5 parts of HALS, and 1 part of zinc stearate, heat to 65℃, rotate at 1000 rpm, mix for 25 minutes, pre-disperse through a twin-screw extruder, granulate, and then mix with other raw materials.

[0085] Step 3, Three-layer co-extrusion molding: Prepare a three-layer co-extrusion die and a cooling calender unit. Feed the raw material into the extrusion equipment and extrude the three layers. Set the extrusion temperatures as follows: base layer 180-190℃, antibacterial layer 170-180℃, protective layer 160-170℃. Set the screw speeds as follows: base layer 120rpm, antibacterial layer 100rpm, protective layer 150rpm. Set the cooling roller temperature to 50-60℃.

[0086] Step 4: Inspect the quality of the finished product: Cut the extruded pre-product into foot pads according to the dimensions, inspect the appearance of the foot pads, and perform performance tests on the foot pads to determine whether the finished product is qualified.

[0087] When performing performance testing on foot pads, the following are also included:

[0088] 1. Antibacterial performance testing: The initial antibacterial rate of the foot pads was tested using the shaking method, referring to GB / T20944.3-2008 "Evaluation of antibacterial properties of textiles - Part 3: Shaking method", with an inoculum concentration of 1×10⁻⁶. 5 The number of viable bacteria was measured after shaking culture for 24 hours, and the antibacterial rate was calculated.

[0089] Wash resistance and antibacterial rate: Perform 50 standard washes (40℃, neutral detergent) according to GB / T8629-2017 "Home Washing and Drying Procedures for Textile Testing", and repeat the above shaking method test after washing;

[0090] 2. Anti-mold performance test: Place the foot pad sample in a petri dish containing agar medium, inoculate with mixed mold spore solution, incubate for 28 days, and observe the surface mold coverage area;

[0091] 3. Anti-fouling performance testing: Conduct contact angle testing and anti-fouling level testing on the foot pads;

[0092] Contact angle test: The water drop method (GB / T24368-2009) is used. 5 μL of deionized water is dropped onto the sample surface, and the contact angle is measured using a contact angle meter. The average value of 5 points is taken.

[0093] Stain resistance rating: Refer to ISO105-X12:2001 "Textiles - Determination of resistance to liquid stains", add stains such as coffee, soy sauce, and machine oil, wipe with a damp cloth after 10 minutes, observe the residue, and rate;

[0094] 4. Abrasion resistance test: Use a Martindale abrasion tester with a load of 9 kPa and observe the surface roughness and damage after 50,000 to 100,000 abrasion cycles.

[0095] The formulation in this example focuses on enhancing antibacterial and antifouling functions, making it more suitable for scenarios with strict requirements for antibacterial and antifouling, such as hospitals, kitchens, car interiors, and laboratories.

[0096] Example 3: Reference Figure 1 As shown: A method for preparing an antibacterial and anti-mildew plastic foot pad includes the following steps:

[0097] Step 1: Pre-fabrication of functional masterbatches: The carrier resin, functional additives, dispersants and processing aids are melt-blended and granulated to produce functional masterbatches, namely antibacterial masterbatches and antifouling masterbatches;

[0098] In the preparation of antibacterial masterbatch, it is made from the following raw materials in parts by weight: 65 parts carrier resin, 12 parts antibacterial agent, 3 parts dispersant, 1 part antioxidant and 1 part coupling agent;

[0099] If the quaternary ammonium salt antibacterial agent is a solid powder, remove impurities by passing it through an 80-mesh sieve; if it is a liquid, it can be first mixed with a small amount of LDPE granules for granulation, premixed with the weighed dispersant / antioxidant for 5 minutes, and the carrier LDPE granules are added in a high-speed mixer. The temperature is raised to 60°C, and the premixed antibacterial agent, dispersant and antioxidant are added in batches. The mixture is continuously mixed for 15-20 minutes until the material is in uniform granule form. After melt blending and extrusion, it is pelletized by water-cooled strip cutting or underwater pelletizing. Irregular particles are removed by sieving after pelletizing.

[0100] Temperature settings for the twin-screw extruder: Zone 1 (feeding section) 145℃, Zone 2 (melting section) 165℃, Zone 3 (homogenization section) 175℃, die 180℃, screw speed: 200rpm, pelletizing via water-cooled strip cutting or underwater pelletizing.

[0101] In the preparation of antifouling masterbatch, it is made from the following raw materials in parts by weight: 55 parts carrier resin, 25 parts antifouling agent, 8 parts dispersant, and 1 part heat-resistant additive;

[0102] For surface treatment of silicone powder, spray the silicone powder with a 3% silane coupling agent KH-560 ethanol solution, dry at 50°C for 2 hours, and remove the ethanol.

[0103] The twin-screw extruder is equipped with a vacuum exhaust port to remove air adsorbed by silicone powder. Temperature settings: Zone 1 135℃, Zone 2 155℃, Zone 3 165℃, Die 175℃, Screw speed: 225rpm.

[0104] Feeding method: LDPE is added to the main feed port, and treated silicone powder and dispersant are added to the side feed port to avoid silicone powder accumulation in the feeding section. Underwater pelleting is used to prevent silicone powder from sticking to the blade, and the surface is smooth without white spots (white spots are silicone powder agglomeration).

[0105] Step 2: Blending of the three layers: The three layers of the foot pad are the base layer, the antibacterial and antifungal layer, and the protective surface layer. Weigh and proportion the raw materials required for each layer, and mix them. The base layer, antibacterial and antifungal layer, and protective surface layer are each made from the following parts by weight:

[0106] Base layer: 70 parts HDPE, 20 parts LDPE, 15 parts calcium carbonate, 8 parts EVA, 1 part antioxidant;

[0107] Antibacterial and antifungal layer: 65 parts LDPE, 12 parts antibacterial masterbatch, 4 parts zinc oxide, 2 parts thiabendazole, and 8 parts talc.

[0108] Protective surface layer: 55 parts LDPE, 8 parts silicone masterbatch, 10 parts nano silica, 1.5 parts hindered amine light stabilizer, 1 part zinc stearate;

[0109] The three-layer raw material blending process also includes the following steps:

[0110] 21. Base layer mixing: Add 15 parts of calcium carbonate to a high-speed mixer, add 0.5 parts of silane coupling agent KH-560, stir at 50°C for 10 minutes to allow the hydroxyl groups on the surface of calcium carbonate to react with the coupling agent, add 70 parts of HDPE and 20 parts of LDPE granules in sequence, start the mixer at 300 rpm, mix at room temperature for 5 minutes until the resin is evenly dispersed, add 8 parts of EVA and 1 part of antioxidant 1010, continue mixing for 5 minutes, slowly add the treated calcium carbonate to the mixer, raise the temperature to 60°C, increase the speed to 600 rpm, mix for 15 minutes, and perform discharge testing;

[0111] 22. Antibacterial and antifungal layer treatment: Pass 4 parts zinc oxide and 8 parts talc powder through a 100-mesh sieve to remove impurities. Add 0.3 parts zinc stearate (dispersant) and stir at high speed for 5 minutes. Add 65 parts LDPE granules, start the mixer at 400 rpm, and mix at room temperature for 3 minutes. Add 12 parts antibacterial masterbatch and mix for 5 minutes. Add pretreated zinc oxide + talc powder and 2 parts thiabendazole in batches. Heat to 55℃, increase the speed to 800 rpm, and mix for 20 minutes. If the antifungal effect requires long-term water resistance, add 0.5 parts silane coupling agent KH-550 to react with the inorganic filler to form chemical bonds.

[0112] 23. Surface Dispersion for Protective Layer: Add 10 parts of nano-silica to the reactor, add 2 parts of stearic acid (melting point 69℃, heat to 75℃ to melt), stir at high speed for 30 minutes, cool to room temperature, pass through a 200-mesh sieve to complete the surface modification of nano-silica, add 55 parts of LDPE particles, add 8 parts of silicone masterbatch, mix at room temperature for 10 minutes, add the modified nano-silica, 1.5 parts of HALS, and 1 part of zinc stearate, heat to 65℃, rotate at 1000 rpm, mix for 25 minutes, pre-disperse through a twin-screw extruder, granulate, and then mix with other raw materials.

[0113] Step 3, Three-layer co-extrusion molding: Prepare a three-layer co-extrusion die and a cooling calender unit. Feed the raw material into the extrusion equipment and extrude the three layers. Set the extrusion temperatures as follows: base layer 180-190℃, antibacterial layer 170-180℃, protective layer 160-170℃. Set the screw speeds as follows: base layer 120rpm, antibacterial layer 100rpm, protective layer 150rpm. Set the cooling roller temperature to 50-60℃.

[0114] Step 4: Inspect the quality of the finished product: Cut the extruded pre-product into foot pads according to the dimensions, inspect the appearance of the foot pads, and perform performance tests on the foot pads to determine whether the finished product is qualified.

[0115] When performing performance testing on foot pads, the following are also included:

[0116] 1. Antibacterial performance testing: The initial antibacterial rate of the foot pads was tested using the shaking method, referring to GB / T20944.3-2008 "Evaluation of antibacterial properties of textiles - Part 3: Shaking method", with an inoculum concentration of 1×10⁻⁶. 5 The number of viable bacteria was measured after shaking culture for 24 hours, and the antibacterial rate was calculated.

[0117] Wash resistance and antibacterial rate: Perform 50 standard washes (40℃, neutral detergent) according to GB / T8629-2017 "Home Washing and Drying Procedures for Textile Testing", and repeat the above shaking method test after washing;

[0118] 2. Anti-mold performance test: Place the foot pad sample in a petri dish containing agar medium, inoculate with mixed mold spore solution, incubate for 28 days, and observe the surface mold coverage area;

[0119] 3. Anti-fouling performance testing: Conduct contact angle testing and anti-fouling level testing on the foot pads;

[0120] Contact angle test: The water drop method (GB / T24368-2009) is used. 5 μL of deionized water is dropped onto the sample surface, and the contact angle is measured using a contact angle meter. The average value of 5 points is taken.

[0121] Stain resistance rating: Refer to ISO105-X12:2001 "Textiles - Determination of resistance to liquid stains", add stains such as coffee, soy sauce, and machine oil, wipe with a damp cloth after 10 minutes, observe the residue, and rate;

[0122] 4. Abrasion resistance test: Use a Martindale abrasion tester with a load of 9 kPa and observe the surface roughness and damage after 50,000 to 100,000 abrasion cycles.

[0123] The formulation in this example emphasizes a balance between performance and cost control, making it suitable for general scenarios where antibacterial and antifouling requirements are not extremely high, such as ordinary home interiors (bedrooms, living rooms) and office environments with less pollution.

[0124] The working principle of this invention is as follows: First, in the pre-fabrication of functional masterbatches, antibacterial masterbatches and antifouling masterbatches can be prepared by melt blending. In the preparation of antibacterial masterbatches, the solid antibacterial agent is screened to remove impurities → pre-mixed with a dispersant → blended with LDPE particles in a high-speed mixer → melt extrusion granulation. This completes the preparation of the antibacterial masterbatch. The quaternary ammonium salt is uniformly dispersed in the LDPE carrier, and when subsequently mixed with the antibacterial and antifungal layer raw materials, it can be quickly and uniformly distributed, improving the antibacterial durability. In the preparation of antifouling masterbatches, silicone powder is surface-treated with silane coupling agent KH-560 → melt blending extrusion → cooling granulation. After the silicone powder is uniformly dispersed, the surface energy of the protective layer is reduced, achieving a "lotus effect" antifouling effect. According to different raw material ratios, the raw materials required for preparing the base layer, antibacterial layer, and protective surface layer are weighed separately, and the raw materials are treated separately to mix the raw materials of different layers. After mixing, the raw materials are fed into the mold. The extrusion temperature, screw speed, and cooling roller temperature are set. After setting, the three layers are co-extruded using an extruder. The extruded pre-product is then cut into shape. The finished product is judged to be qualified by appearance inspection and performance testing. If qualified, it is packaged and stored. If unqualified, the reasons are analyzed and the subsequent manufacturing process is improved. In the three-layer foot pad structure, the base layer provides mechanical support, weather resistance, and low cost. Calcium carbonate reduces costs, EVA improves toughness, and the antibacterial and anti-mildew layer, containing quaternary ammonium salts and inorganic / organic anti-mildew agents, ensures anti-mildew effect. Talc powder improves surface smoothness and ensures the foot pad's performance. Silicone masterbatch in the protective surface layer reduces surface energy and prevents staining. Nano silica enhances wear resistance, HALS improves weather resistance, and zinc stearate promotes dispersion.

[0125] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an antibacterial and antifungal plastic foot pad, characterized in that: Includes the following steps: S1. Pre-made functional masterbatch: The carrier resin, functional additives, dispersants and processing aids are melt-blended and granulated to form functional masterbatch, namely antibacterial masterbatch and antifouling masterbatch; S2. Three-layer material blending: The three layers of the foot pad are the base layer, the antibacterial and anti-mildew layer, and the protective surface layer. The raw materials required for the preparation of the three layers are weighed and proportioned separately, and the raw materials for each layer are mixed. The base layer, the antibacterial and anti-mildew layer, and the protective surface layer are respectively made from the following parts by weight of raw materials: Base layer: 70-80 parts HDPE, 10-20 parts LDPE, 15-20 parts calcium carbonate, 5-8 parts EVA, 0.5-1 parts antioxidant; Antibacterial and antifungal layer: 60-70 parts LDPE, 10-15 parts antibacterial masterbatch, 3-5 parts zinc oxide, 2-3 parts thiabendazole, 5-10 parts talc; Protective surface layer: 50-60 parts LDPE, 5-10 parts silicone masterbatch, 8-12 parts nano silica, 1-2 parts hindered amine light stabilizer, 1-2 parts zinc stearate; S3, Three-layer co-extrusion molding: Prepare a three-layer co-extrusion mold and a cooling calender unit, feed the raw material into the extrusion equipment, and extrude the three layers into shape; S4. Inspect the quality of the finished product: Cut the extruded pre-products into foot pads according to the dimensions, inspect the appearance of the foot pads, and perform performance tests on the foot pads to determine whether the finished product is qualified.

2. The method for preparing the antibacterial and antifungal plastic foot pad according to claim 1, characterized in that: In S1, the antibacterial masterbatch is made from the following raw materials in parts by weight: 60-70 parts carrier resin, 10-15 parts antibacterial agent, 2-5 parts dispersant, 0.5-1 part antioxidant and 0.5-1 part coupling agent; The antifouling masterbatch is made from the following raw materials in parts by weight: 50-60 parts carrier resin, 20-30 parts antifouling agent, 5-10 parts dispersant, and 0.5-1 part temperature-resistant additive.

3. The method for preparing the antibacterial and antifungal plastic foot pad according to claim 1, characterized in that: In the manufacturing of antibacterial masterbatch, the solid quaternary ammonium salt antibacterial agent is screened to remove impurities and premixed with the weighed dispersant / antioxidant for 5 minutes. The carrier LDPE particles are added in a high-speed mixer, the temperature is raised to 50-60℃, and the premixed antibacterial agent, dispersant and antioxidant are added in batches. The mixture is continuously mixed for 15-20 minutes until the material is in uniform granular form. After melt blending and extrusion, the material is pelletized by water cooling strip cutting or underwater pelletizing. Irregular particles are screened out after pelletizing.

4. The method for preparing the antibacterial and antifungal plastic foot pad according to claim 1, characterized in that: In the manufacture of antifouling masterbatch, the silicone powder is surface treated by spraying it with a 3% silane coupling agent KH-560 ethanol solution, drying it at 50°C for 2 hours to remove the ethanol, and then cooling and granulating it after melt blending extrusion.

5. The method for preparing the antibacterial and antifungal plastic foot pad according to claim 1, characterized in that: The three-layer raw material blending process also includes the following steps: S21. Base layer mixing: The base layer raw materials are fed into a high-speed mixer and stirred at 50°C for 10 minutes to disperse the filler, and the discharge test is performed. S22, Antibacterial and mildew-proof layer treatment: The raw materials are fed into a mixer and stirred, and 0.5% silane coupling agent KH-550 is added to treat the inorganic filler; S23. Protective Surface Dispersion: Set the parameters of the twin-screw extruder to a temperature of 160-180℃ and a speed of 200rpm to pre-disperse the raw materials and conduct a dispersibility test.

6. The method for preparing the antibacterial and antifungal plastic foot pad according to claim 5, characterized in that: During the discharge inspection in S21, visual inspection is used to determine whether there are white calcium carbonate lumps. A small sample is burned, and the residual ash is evenly distributed without aggregation, thus completing the recommended dispersibility test.

7. The method for preparing the antibacterial and antifungal plastic foot pad according to claim 1, characterized in that: In S3, the extrusion temperatures are set as follows: base layer 180-190℃, antibacterial layer 170-180℃, and protective layer 160-170℃.

8. The method for preparing the antibacterial and antifungal plastic foot pad according to claim 1, characterized in that: In S3, the screw speeds are as follows: base layer 120 rpm, antibacterial layer 100 rpm, protective layer 150 rpm, and cooling roller temperature 50-60℃.

9. The method for preparing the antibacterial and antifungal plastic foot pad according to claim 1, characterized in that: In S4, the performance testing of the foot pads also includes the following: A1. Antibacterial performance test: The initial antibacterial rate of the foot pad was tested using the vibration method. Then, the foot pad was subjected to 50 standard washes. After washing, the vibration method test was repeated to test the wash-resistant antibacterial rate. A2. Anti-mold performance test: Place the foot pad sample in a petri dish containing agar medium, inoculate with mixed mold spore solution, incubate for 28 days, and observe the surface mold coverage area; A3. Anti-fouling performance test: Conduct contact angle test and anti-fouling level test on the foot pads; A4. Abrasion resistance test: Use a Martindale abrasion tester with a load of 9 kPa and observe the surface roughness and damage after 50,000 to 100,000 abrasion cycles.

10. An antibacterial and anti-mildew plastic foot pad, characterized in that: The antibacterial and antifungal plastic foot pad was prepared using any one of the preparation methods of claims 1-9.

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