A pe-rt pipe and a method for producing the same

Abstract

The application discloses a PE-RT pipe and a preparation method thereof, and relates to the technical field of building heating and ventilation. The PE-RT pipe comprises an outer layer and an inner layer, the outer layer comprises heat-resistant polyethylene, and the surface of the inner layer is provided with V-shaped convex structures; the inner layer comprises the following components in parts by weight: 75-80 parts of low-density polyethylene A; 20-25 parts of low-density polyethylene B; 5-15 parts of amino-modified silver-loaded silicon dioxide nanoparticles; 0.05-1.5 parts of amino-modified polystyrene microspheres; 5-15 parts of alkyl-modified silicone auxiliary agents with C a a being greater than or equal to 5; 0.5-2 parts of a compatilizer; and 0.5-2 parts of a coupling agent; the low-density polyethylene A is metallocene linear low-density polyethylene. The inner wall of the PE-RT pipe has a micro-nano structure and a low-surface-energy antibacterial and hydrophobic layer at the same time, and has long-lasting and durable hydrophobic and anti-fouling functions.

Description

Technical Field

[0001] This invention relates to the technical field of building heating, ventilation and air conditioning, and particularly to a PE-RT pipe and its preparation method. Background Technology

[0002] In underfloor heating systems, the underfloor heating pipes are a crucial component, playing a vital role in transporting hot water and transferring heat energy. Currently, most underfloor heating pipes in China are made of PE-RT pipes, which have advantages such as high temperature resistance, corrosion resistance, and long-term hydraulic pressure resistance. They are also flexible and easy to install, making them widely used. However, as the inner wall of the pipes used for transporting hot water, scale easily forms on the pipe surface during water transport due to microorganisms, mineral ions in the water, and the complexity of the pipe structure. The presence of scale increases head loss, and within the underfloor heating pipes, the presence of scale reduces heat transfer efficiency, affecting the heating effect.

[0003] Accumulated scale buildup on the inner walls of underfloor heating pipes leads to a drop in indoor heating temperature, affecting not only the normal operation of the underfloor heating system but also wasting energy. Due to the widespread use of PE-RT pipes, higher requirements are placed on the pipes themselves: they must possess hydrophobic, anti-fouling, and anti-scaling properties. A hydrophobic layer can effectively reduce water resistance, prevent the adhesion of dirt and grime, and improve the efficiency and lifespan of the piping system.

[0004] Currently, there are two main methods for achieving hydrophobic surfaces: one is to construct micro-nano rough structures on the surface of a material with low surface energy, and the other is to cover a surface with a certain degree of roughness with a layer of low surface energy material. Only a hydrophobic layer that possesses both micro-nano structures and low surface energy can have long-lasting hydrophobic and anti-scaling functions. However, due to the curved and closed structure of the inner wall of underfloor heating pipes and the requirement for continuous lengths of 100-500m, it is difficult to achieve continuous industrial production. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a PE-RT pipe and its preparation method. The inner wall of the PE-RT pipe of this invention simultaneously possesses a micro-nano structure and a low-surface-energy antibacterial and hydrophobic layer, thus exhibiting long-lasting hydrophobic and anti-scaling properties.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a PE-RT pipe, comprising an outer layer and an inner layer, the outer layer comprising heat-resistant polyethylene (PE-RT), and the inner layer having a V-shaped protrusion structure on its surface, the inner layer comprising the following components in parts by weight:

[0008] Low-density polyethylene A 75-80 parts; low-density polyethylene B 20-25 parts; amino-modified silver-loaded silica nanoparticles 5-15 parts; amino-modified polystyrene microspheres 0.05-1.5 parts; C-type... a The alkyl-modified silicone additive is 5-15 parts, a≥5; compatibilizer is 0.5-2 parts; coupling agent is 0.5-2 parts; the low-density polyethylene A is metallocene linear low-density polyethylene (M-LLDPE).

[0009] In this invention, M-LLDPE exhibits high molecular chain entanglement, high melt strength, and good mechanical and heat resistance properties, but its high melt viscosity hinders processing. Adding a certain proportion of long-branched LDPE (low-density polyethylene B) to M-LLDPE strengthens intermolecular entanglement, improves shear sensitivity, and reduces the melt viscosity of the blend, thereby improving processing performance. Simultaneously, the addition of LDPE to M-LLDPE increases the irregularity of the molecular chain structure, reduces crystallinity, and thus lowers the shrinkage rate of the mixture, promoting the formation of micro- and nano-sized particles on the inner wall of the pipe. Furthermore, the addition of amino-modified silver-loaded silica nanoparticles and amino-modified polystyrene microspheres provides excellent hydrophobic and antifouling effects. Amino modification improves compatibility with PE resin, reduces agglomeration, and enhances the hydrophobicity of the inner layer. Simultaneously, the antibacterial properties of silver ions better inhibit the growth and adhesion of bacteria and microalgae on the inner wall of the pipe, gradually reducing the impact of the adhered biofilm on the contact angle of the inner wall, thus improving the hydrophobic performance of the pipe. a The alkyl-modified silicone additive is a long-chain alkyl-modified silicone additive that exhibits good compatibility with M-LLDPE and LDPE resins. Its long-chain structure is reinforced by entanglement with the molecular chains of M-LLDPE and LDPE, preventing the silicone additive from precipitating onto the outer surface of the pipe wall and reducing the time-sensitive effect of water conveyance performance. This results in long-term, durable hydrophobic properties on the inner wall of the pipe. Therefore, this invention, through the synergistic effect of its components, enables the pipe to possess excellent long-term, durable hydrophobic properties.

[0010] Furthermore, the present invention provides a V-shaped convex structure on the surface of the inner layer, which makes the inner wall of the pipe form a rough structure (micro-nano structure) at the micron to nano level, which has biomimetic superhydrophobicity and is conducive to further improving the long-term hydrophobic performance of the pipe.

[0011] Preferably, the thickness ratio of the outer layer to the inner layer is (7-8):(3-2).

[0012] Preferably, the height of the V-shaped convex structure is 8-180μm, and the width of the top convex of the V-shaped convex structure is 5-45nm.

[0013] Preferably, the V-shaped protrusion structure is composed of a plurality of V-shaped protrusions, and the plurality of V-shaped protrusions are evenly distributed along the radial direction of the pipe and extend along the axial direction of the pipe.

[0014] Preferably, the metallocene linear low-density polyethylene is ethylene-1-hexene copolymer M-LLDPE.

[0015] Preferably, the metallocene linear low-density polyethylene (M-LLDPE) has a density of 0.91-0.925 g / cm³. 3 Under test conditions of 190℃ and 5kg, the melt index is 1.0-2.2 g / 10min, the mass content of the comonomer 1-hexene is 2-3% (the content test standard is ASTM D5017-24), and the crystallinity is 41-49%.

[0016] Preferably, the density of the low-density polyethylene B is 0.915-0.920 g / cm³. 3 Under test conditions of 190℃ and 5kg, the melt index is 1-2 g / 10min and the crystallinity is 30-40%.

[0017] Preferably, the amino-modified silver-loaded silica nanoparticles have a particle size range of 50-150 nm and a specific surface area of ​​130-400 m². 2 / g, amino content is 0.1-0.25mmol / g, silver loading is 2.5-4wt%.

[0018] Preferably, the amino-modified polystyrene microspheres have a particle size range of 0.1-100 μm and an amino mass percentage of 2-5%.

[0019] Preferably, the amino-modified silver-loaded silica nanoparticles can be prepared by the following method:

[0020] Amino-modified silica nanoparticles were dispersed in silver nitrate (AgNO3) solution, the pH was adjusted to 8.5-9.5, and after centrifugation and washing, amino-modified silver-loaded silica nanoparticles were obtained.

[0021] Preferably, the mass ratio of the amino-modified silica nanoparticles to the silver nitrate solution is (15-20):1.

[0022] This invention does not have any particular limitation on the source of amino-modified silica nanoparticles, as long as the purpose of this invention can be achieved.

[0023] Preferably, the band C a In alkyl-modified silicone additives, the alkyl group includes haloalkyl, alkoxy, epoxyalkoxy, or carboxylic alkoxy; C a The number of carbon atoms is an integer between 5 and 50; the C-band a The molecular weight of the alkyl-modified silicone additive is 2000-6000.

[0024] More preferably, the C a It is an integer representing the number of carbon atoms between 10 and 30.

[0025] Preferably, the band C a Alkyl-modified silicone additives include at least one of octadecanoamide alkoxy-modified silicone additives and hexadecanoamide carboxylic acid alkoxy-modified silicone additives.

[0026] Preferably, the compatibilizer includes at least one of maleic anhydride-grafted polyethylene, acrylic acid-grafted polyethylene, and glycidyl methacrylate-grafted polyethylene.

[0027] Preferably, the coupling agent includes at least one of titanate coupling agents, silane coupling agents, and aluminate coupling agents.

[0028] Secondly, the present invention also provides a method for preparing PE-RT pipes, comprising the following steps:

[0029] (1) After the components in the inner layer are mixed evenly, the inner layer mixture is obtained;

[0030] (2) The inner layer compound and the heat-resistant polyethylene in the outer layer are co-extruded in an inner layer extruder and an outer layer extruder respectively to obtain the PE-RT pipe.

[0031] Preferably, in step (2), the temperature of the outer extruder is 180-210℃ and the temperature of the inner extruder is 170-200℃; the die head of the inner extruder includes a core die, the core die temperature is set to 170-190℃, and the extrusion speed is 20-25 m / min.

[0032] Preferably, the outer surface of the core mold is plated with a chromium layer of a pyramidal array structure, which is composed of a plurality of pyramidal cones, and the plurality of pyramidal cones are arranged in an array along the circumference of the core mold.

[0033] Preferably, the height of the pyramid cone is 10-200 μm, the spacing between adjacent pyramid cones is 10-50 nm, and the side length of the bottom of the pyramid cone is 100-1100 nm.

[0034] Since the pyramid cone is nanometer-sized, which is several orders of magnitude smaller than the core mold size, the bottom of the pyramid cone can be approximated as a flat square.

[0035] Preferably, the chromium layer of the pyramidal array structure on the outer surface of the core mold is prepared by masking and vapor deposition techniques.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] (1) In the inner layer of the present invention, M-LLDPE and LDPE resins are mixed with amino-modified silver-loaded silica nanoparticles, amino-modified polystyrene microspheres, and C-type silica nanoparticles. a The alkyl-modified silicone additives, compatibilizers, and coupling agents give the inner wall of the pipe excellent hydrophobic properties, while greatly reducing the crystallization properties of PE resin and significantly reducing the shrinkage rate. This promotes the formation of micro-nano-sized "V-shaped convex" structures on the inner wall of the pipe, thereby improving the compatibility and adhesion between the inner and outer layers and preventing delamination under heat, water, and pressure conditions.

[0038] (2) The present invention has a micro-nano-sized pyramidal array structure of chromium layer plated on the outer surface of the core mold, so that the inner wall of the continuously extruded tube has a micron-nano-sized “V-shaped synapse” structure, that is, a nano-scale synaptic structure on the micron-sized synaptic structure, which makes the inner wall of the tube have biomimetic superhydrophobicity.

[0039] (3) In this invention, the inner layer has the ability to inhibit the growth of bacteria and microorganisms and algae through silver-loaded silica nanoparticles, thereby reducing the formation of biofilm and helping to reduce scale formation. Combined with hydrophobic functional materials, it is beneficial to further improve the long-term hydrophobic performance of the inner wall of the pipe. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the end face structure of the PE-RT pipe described in this invention.

[0041] Figure 2 This is a schematic diagram illustrating the V-shaped convex structure in the inner layer of a pipe according to the present invention.

[0042] Figure 3 This is a cross-sectional structural diagram of the core mold described in this invention.

[0043] Figure 4 This is a schematic diagram of the core mold described in this invention. A is an end face view of the core mold, and B is a cross-sectional view of the core mold.

[0044] Figure 5 This is a three-dimensional structural diagram of the core mold described in this invention.

[0045] Figure 6 This is a partial side view of the chromium layer of the pyramidal array structure on the core mold described in this invention.

[0046] Figure 7 This is a partial top view of the chromium layer of the pyramidal array structure on the core mold described in this invention.

[0047] Figure 1-7In the diagram, 1 is the outer layer; 2 is the inner layer; 3 is the V-shaped convex structure; 4 is the core mold; 5 is the horizontal flow section; 6 is the sloping flow section; and 7 is the pyramidal cone array structure chromium layer. Detailed Implementation

[0048] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments, but the scope of protection and implementation of the present invention are not limited thereto.

[0049] Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0050] Example 1

[0051] This embodiment discloses a PE-RT pipe, such as Figure 1 As shown, it includes an outer layer 1 and an inner layer 2, with a thickness ratio of 7:3 between the outer and inner layers. Figure 2 As shown, the inner layer 2 has a V-shaped protrusion structure 3 on its surface. The V-shaped protrusion structure 3 is composed of several V-shaped protrusions, and the several V-shaped protrusions are evenly distributed along the radial direction of the pipe and extend along the axial direction.

[0052] The outer layer comprises PE-RT, grade SP980, manufactured by LG Chem, with a melt flow index of 1.86 g / 10 min and a density of 0.937 g / cm³. 3 .

[0053] The inner layer comprises the following components in parts by weight:

[0054] Low-density polyethylene A 75 parts; low-density polyethylene B 25 parts; amino-modified silver-loaded silica nanoparticles 6 parts; amino-modified polystyrene microspheres 0.05 parts; C a The low-density polyethylene A is 8 parts of alkyl-modified silicone additive; 1.5 parts of compatibilizer; 1 part of coupling agent; and the low-density polyethylene A is metallocene linear low-density polyethylene M-LLDPE.

[0055] The metallocene linear low-density polyethylene (M-LLDPE) is grade SP2520, manufactured by Primman Corporation of Japan, with a melt flow index of 1.9 g / 10 min and a density of 0.925 g / cm³. 3 The mass content of the comonomer 1-hexene is 2.52%, and the crystallinity is 48%.

[0056] The low-density polyethylene B mentioned is grade 18D, produced by Daqing Petrochemical, with a density of 0.919 g / cm³. 3 The melt index is 1.5 g / 10 min, and the crystallinity is 36.2%.

[0057] The amino-modified silver-loaded silica nanoparticles are amino-modified silver-loaded mesoporous silica nanoparticles: customized by East China University of Science and Technology, with a particle size range of 70-120 nm and a specific surface area of ​​210-235 m². 2 / g; amino content 0.15mmol / g, silver loading 2.8wt%.

[0058] The amino-modified silver-loaded mesoporous silica nanoparticles are loaded with silver ions through amino-modified spherical silica nanoparticles (Nanjing Dongna Biotechnology Co., Ltd., product model SM-N, particle size 100nm), as follows:

[0059] Amino-modified spherical silica nanoparticles were uniformly dispersed in a silver nitrate solution (concentration 0.2 mol / L), and the pH was adjusted to 9.0 to allow Ag to... + After complexing with an amino group and centrifugation and washing, amino-modified silver-loaded mesoporous silica nanoparticles were obtained. The reaction temperature was 30℃ and the reaction time was 2 h; the mass ratio of amino-modified spherical silica nanoparticles to silver nitrate solution was 16:1.

[0060] The amino-modified polystyrene microspheres: brand name R-PSN-100 micrometers, produced by Xi'an Ruixi Biotechnology, with a particle size range of 90-100 μm.

[0061] The band C a The alkyl-modified silicone additive is an octadecamide alkoxy-modified silicone additive: brand name 66001G, produced by Chengdu Silike, with a molecular weight of 3300-4200.

[0062] The compatibilizer is maleic anhydride-grafted polyethylene, DuPont Bynel 41E762.

[0063] The coupling agent is a silane coupling agent, brand name KH550.

[0064] This embodiment discloses an inner layer extruder. The extruder die includes a mandrel, which is a plastic extrusion die. The front end of the mandrel is used to heat the inner wall of the pipe and to shape it. Figure 3 As shown, the mandrel 4 includes a horizontal flow section 5 and a sloping flow section 6. The outer surface of the horizontal flow section 5 is coated with a chromium layer 7 of a pyramidal cone array structure. The chromium layer of the pyramidal cone array structure is composed of a plurality of pyramidal cones, and the plurality of pyramidal cones are arranged in an array along the circumference of the mandrel. The height of the pyramidal cone is 50 μm, the spacing between adjacent pyramidal cones is 20 nm, and the side length of the bottom of the pyramidal cone is 300 nm.

[0065] This embodiment also discloses a method for preparing PE-RT pipes, including the following steps:

[0066] (1) First, electrolytic chromium plating is used to uniformly plate chromium on the slope section and the horizontal section of the core die of the inner extruder, with a thickness of 0.03 mm, to prevent the core die from being corroded; then, a pyramidal cone array structure chromium layer with a length of 1 cm and a thickness of 0.05 mm is added to the horizontal section of the core die using the mask method and physical vapor deposition technology.

[0067] (2) After the components in the inner layer are mixed evenly, the inner layer mixture is obtained.

[0068] (3) The inner layer compound and PE-RT are added to the inner layer extruder and the outer layer extruder respectively for double-layer co-extrusion molding to obtain the PE-RT pipe. The temperature of the outer layer extruder is set to 180-180-190-200-200℃; the temperature of the inner layer extruder is set to 170-170-180-185-190℃; the mandrel temperature is set to 175℃; and the extrusion speed is 20m / min.

[0069] The outer surface of the mandrel horizontal flow section of the inner layer extruder is plated with a chromium layer of pyramidal cone array structure. The inner layer compound is extruded from the mandrel slope flow section through the horizontal flow section, so that the surface of the inner layer of the PE-RT pipe has a V-shaped convex structure.

[0070] Example 2

[0071] This embodiment discloses a PE-RT pipe, such as Figure 1 As shown, it includes an outer layer 1 and an inner layer 2, with a thickness ratio of 8:2 between the outer and inner layers. Figure 2 As shown, the inner layer 2 has a V-shaped protrusion structure 3 on its surface. The V-shaped protrusion structure 3 is composed of several V-shaped protrusions, and the several V-shaped protrusions are evenly distributed along the radial direction of the pipe and extend along the axial direction.

[0072] The outer layer comprises PE-RT, grade SP980, manufactured by LG Chem, with a melt flow index of 1.86 g / 10 min and a density of 0.937 g / cm³. 3 .

[0073] The inner layer comprises the following components in parts by weight:

[0074] Low-density polyethylene A 80 parts; low-density polyethylene B 20 parts; amino-modified silver-loaded silica nanoparticles 12 parts; amino-modified polystyrene microspheres 1 part; with C a The low-density polyethylene A is 10 parts of alkyl-modified silicone additive; 1.5 parts of compatibilizer; 1.5 parts of coupling agent; and metallocene linear low-density polyethylene M-LLDPE.

[0075] The metallocene linear low-density polyethylene (M-LLDPE) is grade Exceed1018CA, manufactured by ExxonMobil, USA, with a melt flow index of 1.0 g / 10 min and a density of 0.918 g / cm³. 3 The mass content of the comonomer 1-hexene is 2.44%, and the crystallinity is 46%.

[0076] The low-density polyethylene B is grade L502, manufactured by Mitsubishi Chemical, with a density of 0.920 g / cm³. 3 The melt index is 1.4 g / 10 min, and the crystallinity is 39.6%.

[0077] The amino-modified silver-loaded silica nanoparticles are amino-modified silver-loaded mesoporous silica nanoparticles: customized by East China University of Science and Technology, with a particle size range of 110-150 nm and a specific surface area of ​​210-235 m². 2 / g, amino content 0.2mmol / g, silver loading 3wt%.

[0078] The amino-modified silver-loaded mesoporous silica nanoparticles are loaded with silver ions through amino-modified spherical silica nanoparticles (Nanjing Dongna Biotechnology Co., Ltd., product model SM-N, particle size 100nm), as follows:

[0079] Amino-modified spherical silica nanoparticles were uniformly dispersed in a silver nitrate solution (concentration 0.2 mol / L), and the pH was adjusted to 9.5 to allow Ag to... + After complexation with an amino group and centrifugation and washing, amino-modified silver-loaded mesoporous silica nanoparticles were obtained. The reaction temperature was 30℃ and the reaction time was 3h; the mass ratio of amino-modified spherical silica nanoparticles to silver nitrate solution was 18:1.

[0080] The amino-modified polystyrene microspheres: brand name R-PSN-100 micrometers, produced by Xi'an Ruixi Biotechnology, with a particle size range of 90-100 μm.

[0081] The band C a The alkyl-modified silicone additive is 401A, produced by Chengdu Silike, with a molecular weight of 4300-4800.

[0082] The compatibilizer is a terpolymer of GMA-ethylene-methyl acrylate, brand name Arkema Lotader AX8900.

[0083] The coupling agent is a silane coupling agent, brand name KH550.

[0084] The inner layer extruder differs from that in Example 1 in that the height of the pyramid cone is 80 μm, the spacing between adjacent pyramid cones is 50 nm, and the side length of the bottom of the pyramid cone is 600 nm.

[0085] A method for preparing PE-RT pipes differs from Example 1 in that the length of the chromium layer of the pyramidal array structure in step (1) is 1.5 cm and the thickness is 0.05 mm; the inner layer extruder temperature in step (3) is set to 170-170-180-190-200℃, the core mold temperature is set to 185℃, and the extrusion speed is 22 m / min.

[0086] Example 3

[0087] This embodiment discloses a PE-RT pipe, such as Figure 1 As shown, it includes an outer layer 1 and an inner layer 2, with a thickness ratio of 7:3 between the outer and inner layers. Figure 2 As shown, the inner layer 2 has a V-shaped protrusion structure 3 on its surface. The V-shaped protrusion structure 3 is composed of several V-shaped protrusions, and the several V-shaped protrusions are evenly distributed along the radial direction of the pipe and extend along the axial direction.

[0088] The outer layer comprises PE-RT, grade SP980, manufactured by LG Chem, with a melt flow index of 1.86 g / 10 min and a density of 0.937 g / cm³. 3 .

[0089] The inner layer differs from that of Example 1 in that the inner layer comprises the following components in parts by weight:

[0090] Low-density polyethylene A 78 parts; low-density polyethylene B 22 parts; amino-modified silver-loaded silica nanoparticles 10 parts; amino-modified polystyrene microspheres 1.5 parts; C a The low-density polyethylene A is 15 parts of alkyl-modified silicone additive; 2 parts of compatibilizer; 2 parts of coupling agent; and metallocene linear low-density polyethylene M-LLDPE.

[0091] The inner layer extruder differs from that in Example 1 in that the height of the pyramid cone is 100 μm, the spacing between adjacent pyramid cones is 50 nm, and the side length of the bottom of the pyramid cone is 800 nm.

[0092] The difference between the preparation method of the PE-RT pipe and that of Example 1 is that in step (1), the length of the chromium layer of the pyramidal array structure is 2cm and the thickness is 0.05mm; in step (3), the inner layer extruder temperature is set to 180-180-190-200-200℃, the core mold temperature is set to 190℃, and the extrusion speed is 25m / min.

[0093] Example 4

[0094] The difference from Example 1 is that the metallocene linear low-density polyethylene is of the Mobil 9365RT grade and has a density of 0.935 g / cm³. 3 The melt index is 1.9 g / 10min, the mass content of the comonomer 1-hexene is 4.8%, and the crystallinity is 56.4%.

[0095] Example 5

[0096] The difference from Example 1 is that the compatibilizer is maleic anhydride-grafted polyolefin elastomer, brand name Mitsui Chemicals MH7010.

[0097] Example 6

[0098] The difference from Example 1 is that the inner layer comprises the following components in parts by weight:

[0099] Low-density polyethylene A 76 parts; low-density polyethylene B 24 parts; amino-modified silver-loaded silica nanoparticles 5 parts; amino-modified polystyrene microspheres 1 part; with C a The low-density polyethylene A is 12 parts of alkyl-modified silicone additive; 1 part of compatibilizer; 1 part of coupling agent; and metallocene linear low-density polyethylene M-LLDPE.

[0100] Example 7

[0101] The difference from Example 1 is that the inner layer comprises the following components in parts by weight:

[0102] Low-density polyethylene A 77 parts; low-density polyethylene B 23 parts; amino-modified silver-loaded silica nanoparticles 15 parts; amino-modified polystyrene microspheres 1.2 parts; C a The low-density polyethylene A is metallocene linear low-density polyethylene M-LLDPE. The alkyl-modified silicone additive is 5 parts; compatibilizer is 0.5 parts; coupling agent is 0.5 parts;

[0103] Comparative Example 1

[0104] The difference from Example 1 is that the outer surface of the horizontal flow section of the core die in the inner extruder is not plated with a chromium layer of pyramidal array structure, that is, the surface of the inner layer is not provided with a V-shaped convex structure.

[0105] Comparative Example 2

[0106] The difference from Example 1 is that low-density polyethylene B is not added to the inner layer; that is, the inner layer comprises the following components in parts by weight:

[0107] 100 parts of metallocene linear low-density polyethylene (M-LLDPE); 6 parts of amino-modified silver-loaded silica nanoparticles; 0.05 parts of amino-modified polystyrene microspheres; C-type... a Eight parts of alkyl-modified silicone additive; 1.5 parts of compatibilizer; and 1 part of coupling agent.

[0108] Comparative Example 3

[0109] The difference from Example 1 is that the inner layer does not contain metallocene linear low-density polyethylene; that is, the inner layer comprises the following components in parts by weight:

[0110] 100 parts of low-density polyethylene B; 6 parts of amino-modified silver-loaded silica nanoparticles; 0.05 parts of amino-modified polystyrene microspheres; and C-type... a Eight parts of alkyl-modified silicone additive; 1.5 parts of compatibilizer; and 1 part of coupling agent.

[0111] Comparative Example 4

[0112] The difference from Example 1 is that the polyethylene resin in the inner layer is all high-density polyethylene, that is, the inner layer comprises the following components in parts by weight:

[0113] 100 parts high-density polyethylene; 6 parts amino-modified silver-loaded silica nanoparticles; 0.05 parts amino-modified polystyrene microspheres; C-type... a Eight parts of alkyl-modified silicone additive; 1.5 parts of compatibilizer; and 1 part of coupling agent.

[0114] Comparative Example 5

[0115] The difference from Example 1 is that the inner layer does not contain amino-modified silver-loaded silica nanoparticles; that is, the inner layer comprises the following components in parts by weight:

[0116] Low-density polyethylene A 75 parts; low-density polyethylene B 25 parts; amino-modified polystyrene microspheres 0.05 parts; with C a The low-density polyethylene A is 8 parts of alkyl-modified silicone additive; 1.5 parts of compatibilizer; 1 part of coupling agent; and the low-density polyethylene A is metallocene linear low-density polyethylene M-LLDPE.

[0117] Comparative Example 6

[0118] The difference from Example 1 is that the inner layer does not contain C. a The alkyl-modified silicone additive, i.e., the inner layer, comprises the following components in parts by weight:

[0119] 75 parts of low-density polyethylene A; 25 parts of low-density polyethylene B; 6 parts of amino-modified silver-loaded silica nanoparticles; 0.05 parts of amino-modified polystyrene microspheres; 1.5 parts of compatibilizer; 1 part of coupling agent; wherein the low-density polyethylene A is metallocene linear low-density polyethylene M-LLDPE.

[0120] Comparative Example 7

[0121] The difference from Example 1 is that the inner layer does not contain amino-modified polystyrene microspheres; that is, the inner layer comprises the following components in parts by weight:

[0122] Low-density polyethylene A 75 parts; low-density polyethylene B 25 parts; amino-modified silver-loaded silica nanoparticles 6 parts; with C a The low-density polyethylene A is 8 parts of alkyl-modified silicone additive; 1.5 parts of compatibilizer; 1 part of coupling agent; and the low-density polyethylene A is metallocene linear low-density polyethylene M-LLDPE.

[0123] Comparative Example 8

[0124] The difference from Example 1 is that silver-loaded silica nanoparticles of equal mass are used instead of amino-modified silver-loaded silica nanoparticles, that is, the silver-loaded silica nanoparticles are not amino-modified.

[0125] The silver-loaded silica nanoparticles were custom-made by East China University of Science and Technology, with a particle size of 100-150 nm and a specific surface area of ​​190-230 m². 2 / g, with a silver loading of 3wt%.

[0126] Comparative Example 9

[0127] The difference from Example 1 is that an equal mass of amino-modified silica nanoparticles is used instead of amino-modified silver-loaded silica nanoparticles, that is, the silica nanoparticles do not carry silver ions.

[0128] The amino-modified silica nanoparticles were custom-made by East China University of Science and Technology, with a particle size of 90-150 nm and a specific surface area of ​​190-230 m². 2 / g, with an amino content of 0.2mmol / g.

[0129] Comparative Example 10

[0130] The difference from Example 1 is that polystyrene microspheres of equal mass are used instead of amino-modified polystyrene microspheres, that is, the polystyrene microspheres are not amino-modified.

[0131] The unmodified polystyrene microspheres are produced by Zhongke Keyou, with a size of 80-100 μm.

[0132] Comparative Example 11

[0133] The difference from Example 1 is that an equal mass of silicone additive is used instead of the C-band. a Alkyl-modified silicone additives, i.e. silicone additives without long-chain alkyl modification.

[0134] The silicone additive without long-chain alkyl modification: 7003, produced by Chengdu Silike, has a molecular weight of 1000-2500.

[0135] Performance testing

[0136] The performance of the PE-RT pipes obtained in the above embodiments and comparative examples was tested. The specific test items, test methods, and results are as follows:

[0137] 1. Thermal cycling test

[0138] The test was conducted according to the standard GB / T 19993 "Test Method for Thermal Cycling of Thermoplastic Piping Systems and Fittings for Hot and Cold Water", with the following test conditions:

[0139]

[0140] ( a One cycle lasts 30+2 minutes, including 15+1 minutes at the highest test temperature and 15+1 minutes at the lowest test temperature.

[0141] The contact angle of the inner wall of the pipe was measured before the thermal cycling test and after 1000, 2000, 3000, 4000 and 5000 thermal cycling tests.

[0142] 2. Antibacterial and anti-algae tests

[0143] Cut the pipe into four sample tubes, each 20cm ± 0.5cm long, and place them in a 500mL glass beaker. Pour in 300mL of municipal tap water. Place the beaker in a constant temperature and humidity laboratory (temperature 25±2℃, humidity 50%±10%) and periodically add deionized water to the initial level. Keep the indoor LED lights on for 24 hours for continuous illumination, with an illuminance of 300lx~350lx.

[0144] The contact angle of the inner wall of the pipe was measured before the anti-algae test, and on days 50, 100, 150 and 200.

[0145] The contact angle results of the PE-RT pipes prepared in the above embodiments and comparative examples after thermal cycling test and antibacterial and anti-algae test are shown in Table 1-2.

[0146] Table 1. Test results of contact angle of the inner wall of the pipe during thermal cycling test.

[0147]

[0148] Table 2. Test results of contact angle of pipe inner wall in antibacterial and anti-algae tests.

[0149]

[0150] As shown in Table 1-2, this invention, by depositing a micro- to nano-sized pyramidal array of chromium layer on the outer surface of the mandrel, imbues the inner wall of the continuously extruded tube with a micro- to nano-sized V-shaped convex structure, thereby giving the inner wall of the tube biomimetic hydrophobicity. Simultaneously, the inner layer combines M-LLDPE and LDPE resins with amino-modified silver-loaded silica nanoparticles, amino-modified polystyrene microspheres, and C-type... a The hydrophobic formulation of alkyl-modified silicone additives, compatibilizers and coupling agents further enhances the long-term hydrophobic performance of the inner wall of the pipe.

[0151] Comparing Comparative Example 1 with Example 1, it can be seen that Comparative Example 1 uses a common mandrel, and the contact angle of the inner wall of the tube is 132.8°, which is more than 20° lower than that of Example 1. This indicates that the tube with a micro-nano-sized V-shaped convex structure on the inner wall has better hydrophobic performance.

[0152] Comparing Comparative Examples 2-7 with Example 1, it can be seen that while Comparative Examples 2-4 used pure M-LLDPE, LDPE, and HDPE resins respectively, the resin crystallization shrinkage properties differed from those in Example 1, resulting in the incomplete formation or defects of the micro-nano-sized V-shaped convex structures on the inner wall of the pipe, leading to a decrease in the hydrophobicity of the inner wall. In Comparative Examples 5 and 7, without the addition of amino-modified silver-loaded silica nanoparticles and amino-modified polystyrene microspheres respectively, the contact angle of the inner wall of the pipe was significantly reduced. Comparative Example 6 did not contain C-type... a Alkyl-modified silicone additives and other hydrophobic additives may precipitate onto the outer surface of the pipe wall. As the testing time increases, the long-term hydrophobic performance of the inner wall of the pipe will significantly decrease.

[0153] Comparing Comparative Examples 8-11 with Example 1, it can be seen that the silver-loaded silica nanoparticles in Comparative Example 8 were not amino-modified, the silica nanoparticles in Comparative Example 9 were not loaded with silver ions, the polystyrene microspheres in Comparative Example 10 were not amino-modified, and the silicone additives in Comparative Example 11 were not modified with long-chain alkyl groups. The contact angle of the inner wall of the pipe in Comparative Examples 8-11 all decreased. This indicates that only by amino-modifying the silver-loaded silica nanoparticles, loading the silica nanoparticles with silver ions, amino-modifying the polystyrene microspheres, and modifying the silicone additives with long-chain alkyl groups can the pipes exhibit excellent long-term hydrophobic properties.

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A PE-RT pipe, characterized in that, The tube comprises an outer layer and an inner layer. The outer layer is made of heat-resistant polyethylene. The surface of the inner layer is provided with a V-shaped convex structure. The height of the V-shaped convex structure is 8-180 μm, and the width of the top convex of the V-shaped convex structure is 5-45 nm. The V-shaped convex structure is composed of a plurality of V-shaped protrusions, and the plurality of V-shaped protrusions are evenly distributed along the radial direction of the tube and extend along the axial direction of the tube. The inner layer comprises the following components in parts by weight: Low-density polyethylene A 75-80 parts; low-density polyethylene B 20-25 parts; amino-modified silver-loaded silica nanoparticles 5-15 parts; amino-modified polystyrene microspheres 0.05-1.5 parts; C-type... a Alkyl-modified silicone additives: 5-15 parts, a≥5; compatibilizer: 0.5-2 parts; coupling agent: 0.5-2 parts; The low-density polyethylene A is metallocene linear low-density polyethylene; the metallocene linear low-density polyethylene is ethylene-1-hexene copolymer M-LLDPE; The low-density polyethylene B is LDPE with long branches; The preparation method of the amino-modified silver-loaded silica nanoparticles is as follows: amino-modified silica nanoparticles are dispersed in silver nitrate solution, the pH is adjusted to 8.5-9.5, and after centrifugation and washing, amino-modified silver-loaded silica nanoparticles are obtained. The band C a In alkyl-modified silicone additives, the alkyl group includes one of haloalkyl, alkoxy, epoxyalkoxy, and carboxylic alkoxy; C a It is an integer representing the number of carbon atoms between 5 and 50.

2. The PE-RT pipe as described in claim 1, characterized in that, The density of the metallocene linear low-density polyethylene is 0.91-0.925 g / cm³. 3 The melt index is 1.0-2.2 g / 10min, the mass content of the comonomer 1-hexene is 2-3%, and the crystallinity is 41-49%.

3. The PE-RT pipe as described in claim 1, characterized in that, The density of the low-density polyethylene B is 0.915-0.920 g / cm³. 3 The melt index is 1-2 g / 10min, and the crystallinity is 30-40%.

4. The PE-RT pipe as described in claim 1, characterized in that, The amino-modified silver-loaded silica nanoparticles have a particle size range of 50-150 nm and a specific surface area of ​​130-400 m². 2 / g, amino content is 0.1-0.25 mmol / g, silver loading is 2.5-4 wt%.

5. The PE-RT pipe as described in claim 1, characterized in that, The amino-modified polystyrene microspheres have a particle size range of 0.1-100 μm and an amino content of 2-5% by mass.

6. The PE-RT pipe as described in claim 1, characterized in that, The band C a The molecular weight of the alkyl-modified silicone additive is 2000-6000.

7. The PE-RT pipe as described in claim 1, characterized in that, The compatibilizer includes at least one of maleic anhydride-grafted polyethylene, acrylic acid-grafted polyethylene, and glycidyl methacrylate-grafted polyethylene.

8. The PE-RT pipe as described in claim 1, characterized in that, The coupling agent includes at least one of titanate coupling agents, silane coupling agents, and aluminate coupling agents.

9. A method for preparing PE-RT pipe as described in any one of claims 1-8, characterized in that, Includes the following steps: (1) After the components in the inner layer are mixed evenly, the inner layer mixture is obtained; (2) The inner layer compound and the heat-resistant polyethylene in the outer layer are co-extruded in an inner layer extruder and an outer layer extruder respectively to obtain the PE-RT pipe.

10. The method for preparing PE-RT pipe as described in claim 9, characterized in that, The die head of the inner extruder includes a core die, the outer surface of which is plated with a chromium layer of a pyramidal array structure.

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