Antibacterial light-blocking polypropylene tube and preparation method thereof

Abstract

The invention provides an antibacterial light-blocking polypropylene tube and a preparation method thereof, the antibacterial light-blocking polypropylene tube comprises a light-blocking outer layer and an antibacterial inner layer which are co-extruded, the light-blocking outer layer comprises a polypropylene base material and a light shielding system, and the antibacterial inner layer comprises a food-grade polypropylene base material and an antibacterial system; and the interface of the light-blocking outer layer and the antibacterial inner layer is of a periodic sawtooth structure. According to the invention, an axial zigzag interface is formed between the light-blocking outer layer and the antibacterial inner layer, and mechanical interlocking is formed between the light-blocking outer layer and the antibacterial inner layer, so that the interlayer binding force is multiplied, and the overall structural stability of the pipe is improved; moreover, due to the sawtooth structure, light rays are refracted or scattered for multiple times at an interface, so that the average propagation path of the light rays in the pipe wall is increased, the light shielding performance of the pipe is effectively improved, and the growth of microorganisms is better blocked; meanwhile, the sawtooth structure of the interface can increase the surface area of the antibacterial inner layer, increase the action area and adhesion density of an antibacterial system in the antibacterial inner layer, and enhance the antibacterial performance of the pipe.

Description

Technical Field

[0001] The present invention relates to the technical field of polypropylene pipes, in particular to an antibacterial and light-blocking polypropylene pipe and a preparation method thereof. Background Art

[0002] As people's living standards improve, the demand for drinking water quality is also increasing. Polypropylene pipes (PPR pipes) are widely used in building water supply systems due to their excellent corrosion resistance, non-toxicity, odorlessness, and long service life. However, traditional PPR pipes still have some urgent problems in practical applications. Common PPR pipes on the market are mainly single-layer structures and lack effective antibacterial and light-blocking properties. When light shines through the pipe wall into the water inside the pipe, it promotes the growth of microorganisms and algae, causing water quality to deteriorate. At the same time, biofilms are easily formed on the inner wall of the pipe, becoming a breeding ground for bacteria and affecting the safety of drinking water.

[0003] Chinese patent CN117341285A discloses a PP-R antibacterial pipe with high UV resistance and light-shielding properties. The pipe comprises an antibacterial layer, a light-shielding layer, and an anti-UV absorption layer, arranged sequentially from the inside out. While this solution provides both antibacterial and light-blocking properties, the interfaces between the three layers are flat, resulting in limited interlayer bonding strength and the risk of interfacial delamination during long-term use.

[0004] At present, the polypropylene pipes in the existing technology have the following shortcomings: first, the interface bonding strength of the multi-layer structure is insufficient, and interface peeling is prone to occur; second, the component ratio of the light shielding system and the antibacterial system is not optimized enough, and the light blocking and antibacterial effects are limited.

[0005] Therefore, there is an urgent need to develop an antibacterial and light-blocking polypropylene pipe with excellent interlayer bonding strength and high-efficiency light-blocking and antibacterial properties to meet the market demand for high-quality and high-safety water supply pipes. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide an antibacterial and light-blocking polypropylene tube to solve the problems of insufficient interlayer bonding strength and unsatisfactory light shielding and antibacterial properties of multi-layer PPR pipes in the prior art. At the same time, the present invention will also provide a method for preparing the antibacterial and light-blocking polypropylene tube.

[0007] To achieve the above-mentioned and other related purposes, the present invention provides the following technical solutions: The first aspect of the present invention provides an antibacterial and light-blocking polypropylene tube, comprising a co-extruded light-blocking outer layer and an antibacterial inner layer, wherein the light-blocking outer layer comprises a PPR substrate and a light-shielding system, and the antibacterial inner layer comprises a food-grade PPR substrate and an antibacterial system; the interface between the light-blocking outer layer and the antibacterial inner layer presents a periodic serrated structure.

[0008] The present invention forms a serrated interface structure along the axial direction between the light-blocking outer layer and the antibacterial inner layer, thereby forming a mechanical interlocking effect between the light-blocking outer layer and the antibacterial inner layer, thereby doubling the interlayer bonding force between the two and avoiding interface peeling; moreover, the serrated structure causes light to be refracted or scattered multiple times, increasing the average propagation path of light in the tube wall, and effectively improving the light shielding performance of the tube; in addition, the serrated structure of the interface can increase the surface area of ​​the antibacterial inner layer, increase the effective area and adhesion density of the antibacterial system therein, and enhance the antibacterial performance of the tube.

[0009] Furthermore, the sawtooth structure is any one of a triangle, trapezoid, sinusoidal, or freeform shape; preferably a sinusoidal or triangular shape. The triangular sawtooth structure has a top angle of 50° to 70°, preferably 55° to 65°, and more preferably an equilateral triangle with a top angle of 60°.

[0010] Furthermore, the tooth depth h of the sawtooth structure and the wall thickness T of the polypropylene tube satisfy 0.01≤h / T≤0.1.

[0011] Furthermore, the thickness T of the light-blocking outer layer is 外 The thickness of the antibacterial inner layer T 内 The ratio is 1:(1~3).

[0012] As a preferred technical solution, the light shielding system includes the following components in weight percentage: 2.0-4.0% carbon black masterbatch, 0.8-2.0% rutile titanium dioxide and 0.2-0.8% ultraviolet absorber.

[0013] As a preferred technical solution, the antibacterial system includes the following components in weight percentage: 0.5-1.5% of silver ion antibacterial agent, 1.0-2.0% of nano ZnO, and 0.05-0.3% of organic antibacterial agent.

[0014] Furthermore, the silver ion antibacterial agent is selected from at least one of silver-loaded zirconium phosphate, silver-loaded zeolite, and silver-zinc borosilicate glass powder; the organic antibacterial agent is selected from at least one of isothiazolinone compounds, quaternary ammonium salt compounds, and guanidines.

[0015] Furthermore, the antibacterial system also includes TiO with oxygen vacancy defects x Nanoparticles with oxygen vacancy concentrations of 12-22 at% were prepared by adding oxygen-deficient TiO x , which can form a Z-type heterojunction with silver-loaded zirconium phosphate, slowing down the silver loss rate and extending the life of the antibacterial inner layer; and the Ti 3+ It can enhance ROS production, promote the oxidation of cell membranes, and improve bactericidal efficiency.

[0016] Furthermore, the TiOx The weight percentage of the nanoparticles is 0.2-0.8%.

[0017] Furthermore, the TiO x The surface of the nanoparticles is coated with a silane coupling agent layer, in which oxygen vacancies increase the surface hydroxyl density by 2 to 3 times, making it easier to graft the silane coupling agent.

[0018] As a preferred technical solution, a compatibility layer of maleic anhydride grafted polypropylene (PP-g-MAH) is formed at the serrated interface between the light-blocking outer layer and the antibacterial inner layer.

[0019] Specifically, maleic anhydride grafted polypropylene is added to the light-blocking outer layer and / or antibacterial inner layer raw materials in the form of masterbatch. During the co-extrusion process, the maleic anhydride groups in the melts on both sides tend to migrate to the interface, react with the PPR molecular chains, and form chemical bonds to bridge the interface, thereby forming a compatible layer of maleic anhydride grafted polypropylene.

[0020] Furthermore, the grafting rate of the maleic anhydride grafted polypropylene is 0.8-1.2 wt %.

[0021] Furthermore, the concentration of maleic anhydride grafted polypropylene in the antibacterial inner layer is greater than the concentration of maleic anhydride grafted polypropylene in the light-blocking outer layer.

[0022] Furthermore, the weight percentage of the maleic anhydride grafted polypropylene in the light-blocking outer layer is 0.3-0.8%, preferably 0.5%; the weight percentage of the maleic anhydride grafted polypropylene in the antibacterial inner layer is 0.5-1.0%, preferably 0.7%.

[0023] A second aspect of the present invention provides a method for preparing the antibacterial light-blocking polypropylene tube, comprising the following steps: (1) The raw materials of the light-blocking outer layer are melted and plasticized by a first extruder to obtain an outer layer melt, and the raw materials of the antibacterial inner layer are melted and plasticized by a second extruder to obtain an inner layer melt; (2) The inner layer melt and the outer layer melt are extruded synchronously through a concentric flow channel co-extrusion die, wherein a periodically vibrating flow guide device is provided at the die outlet so that the interface of the two layers of melt is subjected to shear force to form a periodic serrated structure; (3) After extrusion, the tube is cooled and shaped by a vacuum sizing sleeve to solidify and retain the serrated interface structure; (4) After pulling and cutting, a double-layer antibacterial and light-blocking polypropylene tube is obtained.

[0024] In step (2), the viscosity ratio of the outer layer melt to the inner layer melt is 1:1 to 1.2.

[0025] In step (2), the temperature of the co-extrusion die is controlled to be 180-220°C; the temperature difference between the inner and outer layer melts does not exceed 15°C; and the extrusion speed difference between the inner and outer layer melts is controlled within ±5%.

[0026] In step (2), the vibration frequency of the guide device is 10-50 Hz, the amplitude is 0.1-1 mm, and the period length of the sawtooth structure is 0.5-5 mm.

[0027] In step (2), the two layers of melt are pressed together at the confluence section of the die head, and an interface pressure of 3.5~5.0MPa is applied.

[0028] In step (3), segmented water cooling is adopted, and the temperature of the external cooling water is 10~20℃ lower than that of the internal cooling water.

[0029] As described above, the antibacterial light-blocking polypropylene tube and its preparation method of the present invention have the following beneficial effects: 1. The present invention forms a serrated interface structure along the axial direction between the light-blocking outer layer and the antibacterial inner layer, thereby forming a mechanical interlocking effect between the two layers, doubling the interlayer bonding force, effectively avoiding the interface peeling problem that is prone to occur in traditional double-layer pipes, and improving the overall structural stability of the pipe; moreover, the serrated structure causes light to be refracted or scattered multiple times at the interface, increasing the average propagation path of light in the pipe wall. Compared with traditional double-layer pipes with straight interfaces, the light shielding performance of the pipe is effectively improved, and the light source required for microbial growth is better blocked; at the same time, the serrated structure of the interface can increase the surface area of ​​the antibacterial inner layer, increase the effective area and attachment density of the antibacterial system therein, and enhance the antibacterial performance of the pipe compared with traditional straight interfaces, thereby improving the inhibitory effect on microorganisms in water.

[0030] 2. The present invention adds TiO with oxygen vacancy defects to the antibacterial system x Nanoparticles can form a Z-type heterojunction with silver-loaded zirconium phosphate, slowing down the loss rate of silver ions, significantly extending the service life of the antibacterial inner layer, and solving the problem of rapid attenuation of the antibacterial effect of traditional antibacterial pipes.

[0031] 3. The present invention forms a compatibility layer of maleic anhydride grafted polypropylene at the serrated interface between the light-blocking outer layer and the antibacterial inner layer, and bridges the interface through chemical bonds, further enhancing the interlayer bonding force. Compared with double-layer pipes without the addition of a compatibilizer, the interlayer peel strength is increased by more than 30%. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It shows a schematic cross-sectional view of the antibacterial and light-blocking polypropylene tube disclosed in Example 1 of the present invention.

[0033] Component number description: 1. Light-blocking outer layer; 2. Antibacterial inner layer. DETAILED DESCRIPTION

[0034] The following describes the implementation of the present invention through specific embodiments. People skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0035] Example 1 This embodiment provides an antibacterial light-blocking polypropylene tube, comprising a co-extruded light-blocking outer layer 1 and an antibacterial inner layer 2, wherein the light-blocking outer layer comprises a PPR substrate and a light-shielding system, and the antibacterial inner layer comprises a food-grade PPR substrate and an antibacterial system; Figure 1 The interface between the light-blocking outer layer and the antibacterial inner layer presents a periodic triangular sawtooth structure, and the tooth depth h of the triangular sawtooth structure and the wall thickness T of the polypropylene tube satisfy h / T=0.05.

[0036] Specifically, the light-blocking outer layer comprises 95wt% PPR substrate, 3.0wt% carbon black masterbatch, 1.5wt% rutile titanium dioxide, and 0.5wt% UV absorber. The carbon black masterbatch is a highly dispersible carbon black with a carbon content of 30%. The rutile titanium dioxide has an average particle size of 0.3μm and a purity greater than 98%. The UV absorber is a benzotriazole-based UV absorber.

[0037] The antimicrobial inner layer is made of 97.3wt% food-grade PPR substrate, 1.0wt% silver ion antimicrobial agent, 1.5wt% nano-ZnO, and 0.2wt% organic antimicrobial agent. The silver ion antimicrobial agent is silver-loaded zirconium phosphate with a silver content of 2.5wt% and an average particle size of 2μm; the nano-ZnO has an average particle size of 50nm and a purity greater than 99.5%; and the organic antimicrobial agent is an isothiazolinone compound.

[0038] The preparation method of the antibacterial light-blocking polypropylene tube comprises the following steps: (1) The raw materials of the light-blocking outer layer are melted and plasticized by a first extruder to obtain an outer layer melt, and the raw materials of the antibacterial inner layer are melted and plasticized by a second extruder to obtain an inner layer melt.

[0039] (2) The inner layer melt and the outer layer melt are extruded synchronously through a co-extrusion die with a concentric flow channel. A periodically vibrating flow guide device is provided at the die outlet so that the interface between the two layers of melt forms a periodic serrated structure under the action of shear force. The temperature of the co-extrusion die is 215°C, and the flow guide device adopts an electromagnetic drive mode with a vibration frequency of 1.2 Hz, an amplitude of 0.3 mm, and a vibration direction perpendicular to the extrusion direction of the pipe.

[0040] (3) After extrusion, the pipe is cooled and shaped by a vacuum sizing sleeve, wherein the cooling water temperature is 15 ° C, the vacuum degree is -0.05 MPa, and the cooling time is 45 seconds, so that the serrated interface structure is solidified and retained.

[0041] (4) After traction and cutting, a double-layer antibacterial and light-blocking polypropylene tube is obtained. The traction speed is 2.5 m / min and the cutting length is 4 m.

[0042] Testing has shown that the tubing exhibits excellent light-blocking properties, with a transmittance of less than 0.5% in the visible light band of 400-700nm and a UV blockage rate exceeding 99%. Antibacterial testing has shown that the tubing exhibits an inhibition rate of over 97% against both Escherichia coli and Staphylococcus aureus, demonstrating a long-lasting and stable antibacterial effect. The serrated interface improves the bonding strength of the two layers by 28%, achieving a peel strength of 10N / mm, effectively preventing interlayer separation.

[0043] Example 2 This embodiment provides an antibacterial, light-blocking polypropylene tube. Compared with Example 1, the only difference is that the antibacterial inner layer uses 96.8wt% food-grade PPR substrate, 1.0wt% silver ion antibacterial agent, 1.5wt% nano-ZnO, 0.2wt% organic antibacterial agent, and 0.5wt% TiOx nanoparticles with oxygen vacancy defects. The silver ion antibacterial agent is silver-loaded zirconium phosphate with a silver content of 2.5wt% and an average particle size of 2μm; the nano-ZnO has an average particle size of 50nm and a purity greater than 99.5%; the organic antibacterial agent is an isothiazolinone compound; the oxygen vacancy concentration of the TiOx nanoparticles is 15at%, the average particle size of the TiOx nanoparticles is 40nm, and the surface of the TiOx nanoparticles is coated with a silane coupling agent layer. The silane coupling agent is γ-aminopropyltriethoxysilane, and the coating amount is 3% of the mass of the TiOx nanoparticles.

[0044] Testing has shown that the tubing exhibits excellent light-blocking properties, with a transmittance of less than 0.5% in the visible light band of 400-700nm and a UV blockage rate exceeding 99%. Antibacterial testing has shown that the tubing exhibits an inhibition rate of over 99% against both Escherichia coli and Staphylococcus aureus, demonstrating a long-lasting and stable antibacterial effect. The serrated interface improves the bonding strength of the two layers by 28%, achieving a peel strength of 10N / mm, effectively preventing interlayer separation.

[0045] Example 3 This embodiment provides an antibacterial and light-blocking polypropylene tube. Compared with Example 1, the only difference is that the light-blocking outer layer includes 94.5wt% of PPR substrate, 3.0wt% of carbon black masterbatch, 1.5wt% of rutile titanium dioxide, 0.5wt% of ultraviolet absorber, and 0.5wt% of maleic anhydride grafted polypropylene. The antibacterial inner layer adopts 96.6wt% of food-grade PPR substrate, 1.0wt% of silver ion antibacterial agent, 1.5wt% of nano-ZnO, 0.2wt% of organic antibacterial agent, and 0.7wt% of maleic anhydride grafted polypropylene. Among them, the grafting rate of maleic anhydride grafted polypropylene is 0.8%, and the melt index is 0.28g / 10min. Thus, a compatibility layer of maleic anhydride grafted polypropylene is formed at the serrated interface between the light-blocking outer layer and the antibacterial inner layer, and the thickness of the compatibility layer is about 10μm.

[0046] Testing has shown that the tubing exhibits excellent light-blocking properties, with a transmittance of less than 0.4% in the visible light band of 400-700nm and a UV blockage rate exceeding 99%. Antibacterial testing has shown that the tubing exhibits an inhibition rate of over 99% against both Escherichia coli and Staphylococcus aureus, demonstrating a long-lasting and stable antibacterial effect. The serrated interface improves the bonding strength of the two layers by 35%, achieving a peel strength of 12N / mm, effectively preventing interlayer separation.

[0047] Example 4 This embodiment provides an antibacterial, light-blocking polypropylene tube. Compared to Example 3, the only difference is that the interface between the light-blocking outer layer and the antibacterial inner layer exhibits a periodic, sinusoidal sawtooth structure. The sawtooth depth h and the wall thickness T of the polypropylene tube satisfy h / T = 0.08.

[0048] Testing has shown that the tubing exhibits excellent light-blocking properties, with a transmittance of less than 0.2% in the visible light band of 400-700nm and a UV blockage rate exceeding 99.5%. Antibacterial testing has shown that the tubing exhibits an inhibition rate of over 99.5% against both Escherichia coli and Staphylococcus aureus, demonstrating a long-lasting and stable antibacterial effect. The serrated interface increases the bonding strength of the two layers by 42%, achieving a peel strength of 15N / mm, effectively preventing interlayer separation.

[0049] In summary, the present invention forms a mechanical interlock between the light-blocking outer layer and the antibacterial inner layer by forming an axially serrated interface, multiplying the interlayer bonding force and improving the overall structural stability of the pipe. Furthermore, the serrated structure causes light to refract or scatter multiple times at the interface, increasing the average propagation path of light within the pipe wall, effectively enhancing the pipe's light-shielding performance and better blocking microbial growth. Furthermore, the serrated interface increases the surface area of ​​the antibacterial inner layer, increasing the active area and adhesion density of the antibacterial system therein, and enhancing the pipe's antibacterial performance. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial value.

[0050] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. An antibacterial light-blocking polypropylene tube, characterized in that: It comprises a co-extruded light-blocking outer layer and an antibacterial inner layer, wherein the light-blocking outer layer comprises a polypropylene substrate and a light-shielding system, and the antibacterial inner layer comprises a food-grade polypropylene substrate and an antibacterial system; the interface between the light-blocking outer layer and the antibacterial inner layer presents a periodic sawtooth structure.

2. The antibacterial light-blocking polypropylene tube according to claim 1, characterized in that: The sawtooth structure is any one of a triangle, a trapezoid, a sine wave or a random shape.

3. The antibacterial light-blocking polypropylene tube according to claim 1, characterized in that: The tooth depth h of the sawtooth structure and the wall thickness T of the polypropylene tube satisfy 0.01≤h / T≤0.

1.

4. The antibacterial light-blocking polypropylene tube according to claim 1, characterized in that: The light shielding system includes the following components in weight percentage: 2.0-4.0% carbon black masterbatch, 0.8-2.0% rutile titanium dioxide and 0.2-0.8% UV absorber.

5. The antibacterial light-blocking polypropylene tube according to claim 1, characterized in that: The antibacterial system comprises the following components in percentage by weight: 0.5-1.5% silver ion antibacterial agent, 1.0-2.0% nano ZnO, 0.05-0.3% organic antibacterial agent.

6. The antibacterial light-blocking polypropylene tube according to claim 5, characterized in that: The silver ion antibacterial agent is selected from at least one of silver-loaded zirconium phosphate, silver-loaded zeolite, and silver-zinc borosilicate glass powder; the organic antibacterial agent is selected from at least one of isothiazolinone compounds, quaternary ammonium salt compounds, and guanidines.

7. The antibacterial light-blocking polypropylene tube according to claim 5, characterized in that: The antibacterial system further comprises TiO with oxygen vacancy defects x Nanoparticles with oxygen vacancy concentration of 12~22at%.

8. The antibacterial light-blocking polypropylene tube according to claim 7, characterized in that: The TiO x The surface of the nanoparticles is coated with a silane coupling agent layer. x The addition amount of nanoparticles is 0.2~0.8wt%.

9. The antibacterial light-blocking polypropylene tube according to claim 1, characterized in that: A compatibility layer of maleic anhydride grafted polypropylene is formed at the zigzag interface between the light-blocking outer layer and the antibacterial inner layer.

10. A method for preparing the antibacterial light-blocking polypropylene tube according to any one of claims 1 to 9, characterized in that: The steps include: (1) The raw materials of the light-blocking outer layer are melted and plasticized by a first extruder to obtain an outer layer melt, and the raw materials of the antibacterial inner layer are melted and plasticized by a second extruder to obtain an inner layer melt; (2) The inner layer melt and the outer layer melt are extruded synchronously through a concentric flow channel co-extrusion die, wherein a periodically vibrating flow guide device is provided at the die outlet so that the interface of the two layers of melt is subjected to shear force to form a periodic serrated structure; (3) After extrusion, the tube is cooled and shaped by a vacuum sizing sleeve to solidify and retain the serrated interface structure; (4) After pulling and cutting, a double-layer antibacterial and light-blocking polypropylene tube is obtained.

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