High-density polyethylene silicon core pipe and preparation method thereof

Abstract

The invention discloses a high-density polyethylene silicon core pipe and a preparation method thereof, and relates to the technical field of silicon core pipes. The high-density polyethylene is subjected to modification treatment in different modes to obtain different modified high-density polyethylene; different modified high-density polyethylene is used as a main component, and a silicon core pipe outer-layer mixture and a silicon core pipe inner-layer mixture are prepared respectively; finally, the silicon core pipe outer layer mixture and the silicon core pipe inner layer mixture are subjected to melt co-extrusion, Si-O-C chemical bonding is generated on the inner layer and the outer layer, and the high-density polyethylene silicon core pipe is obtained. The high-density polyethylene silicon core pipe prepared by the invention is very high in interlayer bonding strength and very excellent in flame retardant property and mechanical property.

Description

Technical Field

[0001] The present application relates to the technical field of silicon core tubes, and in particular to a high-density polyethylene silicon core tube and a preparation method thereof. Background Art

[0002] There are two main types of silicone-core tubes currently in use. One is a polyethylene tube with pre-installed silicone in the inner layer. Silicone is pre-placed in the inner layer of this type of tube during production. However, during the production and construction process, silicone is easily contaminated, and during the cable threading process, silicone may be damaged due to factors such as friction, thus affecting its performance. The other is a silicone-core tube with synchronously extruded silicone in the inner layer. This type of silicone-core tube is extruded into the inner layer at the same time as the polyethylene tube is extruded. Although this method solves the problem of silicone contamination to a certain extent, in actual production, there is a situation where the bonding strength between silicone and polyethylene is insufficient, which easily leads to the falling off of the silicone-containing inner layer, affecting the use effect of the silicone-core tube; in addition, the current silicone-core tubes mostly achieve flame retardant effects by adding flame retardants, and the flame retardancy is often not excellent enough.

[0003] Chinese patent application publication number CN117103791A discloses an environmentally friendly polymer silicon-core tube and its preparation method. The silicon-core tube comprises a silicon-core outer tube and a silicon core layer within the outer tube. The silicon core layer is made from high-density polyethylene, ethylene-acrylate-maleic anhydride terpolymer, organically modified magnesium-aluminum hydrotalcite powder, silica-coated basalt fiber, a silane coupling agent, a lubricant, and an antioxidant. The silicon-core outer tube is made from high-density polyethylene, metallocene polyethylene, a polyolefin elastomer, silica-coated basalt fiber, a lubricant, and an antioxidant. The polymer silicon-core tube of this invention exhibits excellent mechanical properties, a smooth inner wall of the silicon core layer, and excellent flame retardancy and environmental performance.

[0004] However, the flame retardancy of the above-mentioned silicon-core tube is improved by directly adding organically modified magnesium-aluminum hydrotalcite powder, rather than introducing the flame retardant component through a chemical reaction. The organically modified magnesium-aluminum hydrotalcite powder introduced in this way is difficult to disperse on the one hand and easy to migrate on the other hand, which is not conducive to long-term flame retardancy. Moreover, the silicon core outer tube of the above-mentioned silicon core tube adopts high-density polyethylene, metallocene polyethylene, and polyolefin elastomer as the resin matrix, and the silicon core layer adopts high-density polyethylene and ethylene-acrylate-maleic anhydride terpolymer as the resin matrix, thereby enhancing the bonding strength between the silicon core outer tube and the silicon core layer. The bonding strength can be further enhanced by modifying the high-density polyethylene of the inner and outer layers in different ways and then further generating Si-OC chemical bonding between the inner and outer layers during melt co-extrusion. Summary of the Invention

[0005] To address the shortcomings of the prior art, the present application provides a high-density polyethylene (HDPE) silicon-core tube and a method for preparing the same. High-density polyethylene (HDPE) is modified in different ways to obtain different modified HDPEs. A silicon-core tube outer layer mixture and a silicon-core tube inner layer mixture are then prepared using the different modified HDPEs as main components. Finally, the silicon-core tube outer layer mixture and the silicon-core tube inner layer mixture are melt-coextruded to form Si-OC chemical bonds between the inner and outer layers, thereby obtaining the HDPE silicon-core tube.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions: In the first aspect, the present application provides a high-density polyethylene silicon core tube, which includes a silicon core tube outer layer and a silicon core tube inner layer that are composited with each other; there is Si-OC chemical bonding between the silicon core tube outer layer and the silicon core tube inner layer; the raw material of the silicon core tube outer layer includes a first modified high-density polyethylene; the raw material of the silicon core tube inner layer includes a second modified high-density polyethylene; the first modified high-density polyethylene is obtained by ozone oxidation treatment of high-density polyethylene particles under ultraviolet light, and then modified with an epoxy silane coupling agent and a diethylphosphoethyltriethoxysilane coupling agent; the second modified high-density polyethylene is obtained by melt grafting high-density polyethylene particles with a silane coupling agent containing carbon-carbon double bonds under the action of an initiator.

[0007] In a second aspect, the present application provides a method for preparing a high-density polyethylene silicon core tube, comprising the following steps: The high-density polyethylene particles are subjected to ozone oxidation treatment under ultraviolet light for 8 to 12 hours to obtain activated high-density polyethylene particles; Add the activated high-density polyethylene particles into a high-speed mixer, add the ethanol solution of epoxy silane coupling agent in the form of a spray while stirring, and continue stirring for 5-10 minutes; Then, an ethanol solution of diethylphosphoethyltriethoxysilane coupling agent was added in the form of a spray while stirring, and stirring was continued for 15 to 20 minutes to obtain a first modified high-density polyethylene; Adding the first modified high-density polyethylene, filler, first antioxidant, masterbatch and lubricant into a high-speed mixer, stirring at 60-80° C. for 30-60 minutes to obtain a silicon core tube outer layer mixture; Using a twin-screw extruder, high-density polyethylene particles, an initiator, and a silane coupling agent containing a carbon-carbon double bond are melt-blended and extruded at 160-180° C., and then cooled and granulated to obtain a second modified high-density polyethylene; Add the second modified high-density polyethylene, silicone masterbatch, dispersant and second antioxidant into a high-speed mixer and stir at room temperature for 10-20 minutes to obtain a silicone core tube inner layer mixture; The multi-layer co-extrusion technology is adopted, and the outer layer mixture of the silicon core tube is melted at 180-200°C and the inner layer mixture of the silicon core tube is melted at 170-190°C through two extruders respectively. The two are then composited and formed through a co-extrusion mold, and the high-density polyethylene silicon core tube is obtained after pulling and cutting.

[0008] Beneficial technical effects: The high-density polyethylene silicon core tube prepared in this application is modified by different methods on the high-density polyethylene in the outer layer and the inner layer of the silicon core tube, and then the inner and outer layers are compounded with each other through multi-layer co-extrusion technology, thereby achieving a synergistic improvement in the performance of the silicon core tube.

[0009] The high-density polyethylene (HDPE) in the outer layer of the silicon-core tube undergoes ozone oxidation under ultraviolet light, generating hydroxyl groups on its surface. This surface is then modified with an epoxy silane coupling agent and diethylphosphoethyltriethoxysilane coupling agents to introduce epoxy and phosphorus-containing groups. The HDPE in the inner layer of the silicon-core tube, on the other hand, generates macromolecular free radicals under the action of an initiator. The silane coupling agent, containing carbon-carbon double bonds, then grafts with these macromolecular free radicals under molten conditions, introducing groups containing silicon-oxygen bonds onto the HDPE.

[0010] After being modified separately, the high-density polyethylene (HDPE) in the outer and inner layers of the silicon-core tube are more easily mixed with other components, thereby producing the outer and inner layer mixtures, respectively. During co-extrusion, the epoxy groups retained in the outer layer mixture further react with the groups containing silicon-oxygen bonds retained in the inner layer mixture, thereby forming Si-OC chemical bonds between the outer and inner layers. This significantly enhances the interlayer adhesion strength of the inner and outer layers and the mechanical properties of the resulting high-density polyethylene (HDPE) silicon-core tube. Furthermore, the phosphorus-containing groups retained in the outer layer mixture are extremely difficult to migrate due to the strong bond between the inner and outer layers, thereby significantly enhancing the flame retardancy of the resulting HDPE silicon-core tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the structure of the high-density polyethylene silicon core tube of the present invention; Figure 2 It is a schematic flow chart of the preparation method of the high-density polyethylene silicon core tube of the present invention; Figure 3 This is a schematic diagram of the principle of the chemical reaction occurring during the preparation process of the high-density polyethylene silicon core tube of the present invention; Figure 4 This is a physical picture of the high-density polyethylene silicon core tube of the present invention.

[0012] Figure numerals: 1, outer layer of silicon core tube; 2, inner layer of silicon core tube. DETAILED DESCRIPTION

[0013] In order to make the technical problems, technical solutions, and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below with reference to the following examples. However, this should not be construed as limiting the scope of this application to the following examples. Without departing from the above-mentioned method concepts of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0014] In this application, the terms used in this application are for the purpose of describing specific embodiments only and are not intended to be limiting of the application.

[0015] As used in this application, the singular forms "for," "or," "an," "any," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0016] In addition, the terms “first” and “second”, if used, are only used for descriptive purposes and should not be understood as indicating or implying relative importance.

[0017] In the first aspect, the present application provides a high-density polyethylene silicon core tube, the structure of which is as follows: Figure 1 As shown, the high-density polyethylene silicon core tube includes a silicon core tube outer layer 1 and a silicon core tube inner layer 2 that are composited with each other; there is a Si-OC chemical bond between the silicon core tube outer layer 1 and the silicon core tube inner layer 2; the raw material of the silicon core tube outer layer 1 includes a first modified high-density polyethylene; the raw material of the silicon core tube inner layer 2 includes a second modified high-density polyethylene; the first modified high-density polyethylene is obtained by ozone oxidation treatment of high-density polyethylene particles under ultraviolet light, and then modified with an epoxy silane coupling agent and a diethylphosphoethyltriethoxysilane coupling agent; the second modified high-density polyethylene is obtained by melt grafting high-density polyethylene particles with a silane coupling agent containing a carbon-carbon double bond under the action of an initiator.

[0018] In a possible implementation, the epoxysilane coupling agent includes any one of γ-glycidyloxypropyltrimethoxysilane, γ-glycidyloxypropylmethyldimethoxysilane, γ-glycidyloxypropyltriethoxysilane, γ-glycidyloxypropylmethyldiethoxysilane and β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane.

[0019] In a possible implementation, the initiator includes any one of dicumyl peroxide, tert-butyl perbenzoate, and di-tert-butyl peroxide.

[0020] In one possible implementation, the silane coupling agent containing a carbon-carbon double bond includes any one of 3-(acryloyloxy)propyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, and vinyltrimethoxysilane; and the mass ratio of the high-density polyethylene particles, the initiator, and the silane coupling agent containing a carbon-carbon double bond is (90-95): (0.5-1.5): (3-10).

[0021] In one possible implementation, the raw materials of the outer layer 1 of the silicon core tube also include filler, a first antioxidant, a masterbatch and a lubricant; the mass ratio of the first modified high-density polyethylene, filler, first antioxidant, masterbatch and lubricant is (65~80): (15~30): (0.2~1): (1~3): (0.5~2).

[0022] In one possible implementation, the raw materials of the inner layer 2 of the silicon-core tube further include silicone masterbatch, dispersant and a second antioxidant; the mass ratio of the second modified high-density polyethylene, silicone masterbatch, dispersant and second antioxidant is (70~90): (5~25): (0.5~5): (0.1~1).

[0023] In one possible implementation, the filler includes one or more of light calcium carbonate, glass powder and mica powder; the first antioxidant includes one or more of 2,6-di-tert-butyl-p-cresol, antioxidant 1010, antioxidant 1076 and antioxidant GA-80; and the lubricant includes one or more of stearic acid, calcium stearate and glycerol monostearate.

[0024] In one possible implementation, the dispersant includes at least one of polyethylene glycol and fatty alcohol polyoxyethylene ether; and the second antioxidant includes one or more of dilauryl thiodipropionate, distearyl thiodipropionate, and myristyl thiodipropionate.

[0025] In a second aspect, the present application provides a method for preparing a high-density polyethylene silicon core tube, such as Figure 2 As shown, the following steps are included: The high-density polyethylene particles are subjected to ozone oxidation treatment under ultraviolet light for 8 to 12 hours to obtain activated high-density polyethylene particles; Add the activated high-density polyethylene particles into a high-speed mixer, add the ethanol solution of epoxy silane coupling agent in the form of a spray while stirring, and continue stirring for 5-10 minutes; Then, an ethanol solution of diethylphosphoethyltriethoxysilane coupling agent is added in the form of a spray while stirring, and stirring is continued for 15 to 20 minutes to obtain a first modified high-density polyethylene; Adding the first modified high-density polyethylene, filler, first antioxidant, masterbatch and lubricant into a high-speed mixer, stirring at 60-80° C. for 30-60 minutes to obtain a silicon core tube outer layer mixture; Using a twin-screw extruder, high-density polyethylene particles, an initiator, and a silane coupling agent containing a carbon-carbon double bond are melt-blended and extruded at 160-180° C., and then cooled and granulated to obtain a second modified high-density polyethylene; Add the second modified high-density polyethylene, silicone masterbatch, dispersant and second antioxidant into a high-speed mixer and stir at room temperature for 10-20 minutes to obtain a silicone core tube inner layer mixture; The multi-layer co-extrusion technology is adopted, and the outer layer mixture of the silicon core tube is melted at 180-200°C and the inner layer mixture of the silicon core tube is melted at 170-190°C by two extruders respectively, and then the two are compositely formed by a co-extrusion die, and the high-density polyethylene silicon core tube is obtained after pulling and cutting; the principle of the chemical reaction in the preparation process of the high-density polyethylene silicon core tube is as follows Figure 3 shown.

[0026] In a possible implementation, in the ethanol solution of the epoxy silane coupling agent, the mass proportion of the epoxy silane coupling agent is 2-5%; in the ethanol solution of the diethylphosphoethyltriethoxysilane coupling agent, the mass proportion of the diethylphosphoethyltriethoxysilane coupling agent is 3-8%.

[0027] The following will describe in detail a method for preparing a high-density polyethylene silicon core tube provided by the present application in combination with different embodiments.

[0028] Example 1

[0029] like Figure 2 As shown, a high-density polyethylene silicon core tube, the preparation method of which comprises the following steps: 1. The high-density polyethylene particles are subjected to ozone oxidation treatment under ultraviolet light for 8 hours to obtain activated high-density polyethylene particles; 2. Add the activated high-density polyethylene particles to a high-speed mixer, add the ethanol solution of γ-glycidyloxypropyltrimethoxysilane in the form of a spray while stirring, and continue stirring for 5 minutes; the weight proportion of γ-glycidyloxypropyltrimethoxysilane in the ethanol solution is 2%; 3. Then, an ethanol solution of diethylphosphoethyltriethoxysilane coupling agent was further added in the form of a spray while stirring, and stirring was continued for 15 minutes to obtain a first modified high-density polyethylene; the weight proportion of the diethylphosphoethyltriethoxysilane coupling agent in the ethanol solution was 3%; 4. Add the first modified high-density polyethylene, light calcium carbonate, 2,6-di-tert-butyl-p-cresol, masterbatch, and stearic acid into a high-speed mixer and stir at 60°C for 30 minutes to obtain a silicon-core tube outer layer mixture; the mass ratio of the first modified high-density polyethylene, light calcium carbonate, 2,6-di-tert-butyl-p-cresol, masterbatch, and stearic acid is 70:25:0.5:2.5:2; 5. Using a twin-screw extruder, high-density polyethylene particles, dicumyl peroxide, and 3-(acryloyloxy)propyltrimethoxysilane were melt-blended and extruded at 160° C., and cooled and granulated to obtain a second modified high-density polyethylene; the mass ratio of the high-density polyethylene particles, dicumyl peroxide, and 3-(acryloyloxy)propyltrimethoxysilane was 90:0.5:9.5; 6. Add the second modified high-density polyethylene, silicone masterbatch, polyethylene glycol and dilauryl thiodipropionate into a high-speed mixer and stir at room temperature for 10 minutes to obtain a silicone core tube inner layer mixture; the mass ratio of the second modified high-density polyethylene, silicone masterbatch, polyethylene glycol and dilauryl thiodipropionate is 80:15:4:1; 7. Using multi-layer co-extrusion technology, two extruders are used to melt the outer layer mixture of the silicon core tube at 180°C and the inner layer mixture of the silicon core tube at 170°C, and then the two are composited and formed through a co-extrusion die. After pulling and cutting, the high-density polyethylene silicon core tube is obtained. Figure 4 shown.

[0030] Example 2

[0031] like Figure 2 As shown, a high-density polyethylene silicon core tube, the preparation method of which comprises the following steps: 1. The high-density polyethylene particles are subjected to ozone oxidation treatment under ultraviolet light for 10 hours to obtain activated high-density polyethylene particles; 2. Add the activated high-density polyethylene particles to a high-speed mixer, add the ethanol solution of γ-glycidyloxypropylmethyldimethoxysilane in the form of a spray while stirring, and continue stirring for 7 minutes; the weight proportion of γ-glycidyloxypropylmethyldimethoxysilane in the ethanol solution is 3%; 3. Then, an ethanol solution of diethylphosphoethyltriethoxysilane coupling agent was further added in the form of a spray while stirring, and stirring was continued for 17 minutes to obtain a first modified high-density polyethylene; the weight proportion of the diethylphosphoethyltriethoxysilane coupling agent in the ethanol solution was 5%; 4. Add the first modified high-density polyethylene, glass powder, antioxidant 1010, masterbatch and calcium stearate into a high-speed mixer and stir at 70°C for 45 minutes to obtain a silicon core tube outer layer mixture; the mass ratio of the first modified high-density polyethylene, glass powder, antioxidant 1010, masterbatch and calcium stearate is 65:30:1:2:2; 5. Using a twin-screw extruder, high-density polyethylene particles, tert-butyl perbenzoate, and 3-(methacryloyloxy)propyltrimethoxysilane were melt-blended and extruded at 170° C., and cooled and granulated to obtain a second modified high-density polyethylene; the mass ratio of the high-density polyethylene particles, tert-butyl perbenzoate, and 3-(methacryloyloxy)propyltrimethoxysilane was 91:1.0:8.0; 6. Add the second modified high-density polyethylene, silicone masterbatch, fatty alcohol polyoxyethylene ether and distearyl thiodipropionate into a high-speed mixer and stir at room temperature for 15 minutes to obtain a silicone core tube inner layer mixture; the mass ratio of the second modified high-density polyethylene, silicone masterbatch, fatty alcohol polyoxyethylene ether and distearyl thiodipropionate is 75:20:4.5:0.5; 7. Using multi-layer co-extrusion technology, two extruders are used to melt the outer layer mixture of the silicon core tube at 190°C and the inner layer mixture of the silicon core tube at 180°C, and then the two are composited and formed through a co-extrusion mold. After pulling and cutting, the high-density polyethylene silicon core tube is obtained.

[0032] Example 3

[0033] like Figure 2 As shown, a high-density polyethylene silicon core tube, the preparation method of which comprises the following steps: 1. The high-density polyethylene particles are subjected to ozone oxidation treatment under ultraviolet light for 12 hours to obtain activated high-density polyethylene particles; 2. Add activated high-density polyethylene particles to a high-speed mixer, add an ethanol solution of γ-glycidyloxypropyltriethoxysilane in the form of a spray while stirring, and continue stirring for 10 minutes; the weight proportion of γ-glycidyloxypropyltriethoxysilane in the ethanol solution is 5%; 3. Then, an ethanol solution of diethylphosphoethyltriethoxysilane coupling agent was further added in the form of a spray while stirring, and stirring was continued for 20 minutes to obtain a first modified high-density polyethylene; the mass proportion of the diethylphosphoethyltriethoxysilane coupling agent in the ethanol solution was 8%; 4. Add the first modified high-density polyethylene, mica powder, antioxidant 1076, masterbatch and glycerol monostearate into a high-speed mixer and stir at 80°C for 60 minutes to obtain a silicon core tube outer layer mixture; the mass ratio of the first modified high-density polyethylene, mica powder, antioxidant 1076, masterbatch and glycerol monostearate is 80:15:0.2:3:1.8; 5. Using a twin-screw extruder, melt-blending and extruding high-density polyethylene particles, di-tert-butyl peroxide, and vinyl trimethoxysilane at 180° C., cooling and granulating to obtain a second modified high-density polyethylene; the mass ratio of the high-density polyethylene particles, di-tert-butyl peroxide, and vinyl trimethoxysilane is 92:1.5:6.5; 6. Add the second modified high-density polyethylene, silicone masterbatch, polyethylene glycol and myristyl thiodipropionate into a high-speed mixer and stir at room temperature for 20 minutes to obtain a silicone core tube inner layer mixture; the mass ratio of the second modified high-density polyethylene, silicone masterbatch, polyethylene glycol and myristyl thiodipropionate is 90:5:4.9:0.1; 7. Using multi-layer co-extrusion technology, two extruders are used to melt the outer layer mixture of the silicon core tube at 200°C and the inner layer mixture of the silicon core tube at 190°C, and then the two are composited and formed through a co-extrusion mold. After pulling and cutting, the high-density polyethylene silicon core tube is obtained.

[0034] Example 4

[0035] like Figure 2 As shown, a high-density polyethylene silicon core tube, the preparation method of which comprises the following steps: 1. The high-density polyethylene particles are subjected to ozone oxidation treatment under ultraviolet light for 9 hours to obtain activated high-density polyethylene particles; 2. Add activated high-density polyethylene particles to a high-speed mixer, add an ethanol solution of γ-glycidyloxypropylmethyldiethoxysilane in the form of a spray while stirring, and continue stirring for 6 minutes; the weight proportion of γ-glycidyloxypropylmethyldiethoxysilane in the ethanol solution is 4%; 3. Then, an ethanol solution of diethylphosphoethyltriethoxysilane coupling agent was further added in the form of a spray while stirring, and stirring was continued for 16 minutes to obtain a first modified high-density polyethylene; the weight proportion of the diethylphosphoethyltriethoxysilane coupling agent in the ethanol solution was 6%; 4. Add the first modified high-density polyethylene, light calcium carbonate, antioxidant GA-80, masterbatch and stearic acid into a high-speed mixer and stir at 65°C for 40 minutes to obtain a silicon core tube outer layer mixture; the mass ratio of the first modified high-density polyethylene, light calcium carbonate, antioxidant GA-80, masterbatch and stearic acid is 75:20:0.8:1.5:2.7; 5. Using a twin-screw extruder, high-density polyethylene particles, dicumyl peroxide, and 3-(acryloyloxy)propyltrimethoxysilane were melt-blended and extruded at 165° C., and cooled and granulated to obtain a second modified high-density polyethylene; the mass ratio of the high-density polyethylene particles, dicumyl peroxide, and 3-(acryloyloxy)propyltrimethoxysilane was 93:0.8:6.2; 6. Add the second modified high-density polyethylene, silicone masterbatch, fatty alcohol polyoxyethylene ether and dilauryl thiodipropionate into a high-speed mixer and stir at room temperature for 12 minutes to obtain a silicone core tube inner layer mixture; the mass ratio of the second modified high-density polyethylene, silicone masterbatch, fatty alcohol polyoxyethylene ether and dilauryl thiodipropionate is 85:10:4.8:0.2; 7. Using multi-layer co-extrusion technology, two extruders are used to melt the outer layer mixture of the silicon core tube at 185°C and the inner layer mixture of the silicon core tube at 175°C, and then the two are composited and formed through a co-extrusion mold. After pulling and cutting, the high-density polyethylene silicon core tube is obtained.

[0036] Example 5

[0037] like Figure 2 As shown, a high-density polyethylene silicon core tube, the preparation method of which comprises the following steps: 1. The high-density polyethylene particles are subjected to ozone oxidation treatment under ultraviolet light for 11 hours to obtain activated high-density polyethylene particles; 2. Add activated high-density polyethylene particles to a high-speed mixer and add an ethanol solution of β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane in the form of a spray while stirring. Continue stirring for 8 minutes; the mass proportion of β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane in the ethanol solution is 3.5%; 3. Then, an ethanol solution of diethylphosphoethyltriethoxysilane coupling agent was further added in the form of a spray while stirring, and stirring was continued for 18 minutes to obtain a first modified high-density polyethylene; the weight proportion of the diethylphosphoethyltriethoxysilane coupling agent in the ethanol solution was 7%; 4. Add the first modified high-density polyethylene, glass powder, 2,6-di-tert-butyl-p-cresol, masterbatch, and calcium stearate into a high-speed mixer and stir at 75°C for 50 minutes to obtain a silicon core tube outer layer mixture; the mass ratio of the first modified high-density polyethylene, glass powder, 2,6-di-tert-butyl-p-cresol, masterbatch, and calcium stearate is 72:23:0.6:2.5:1.9; 5. Using a twin-screw extruder, high-density polyethylene particles, tert-butyl perbenzoate, and vinyl trimethoxysilane were melt-blended and extruded at 175° C., and cooled and granulated to obtain a second modified high-density polyethylene; the mass ratio of the high-density polyethylene particles, tert-butyl perbenzoate, and vinyl trimethoxysilane was 94:0.5:5.5; 6. Add the second modified high-density polyethylene, silicone masterbatch, polyethylene glycol and distearyl thiodipropionate into a high-speed mixer and stir at room temperature for 18 minutes to obtain a silicone core tube inner layer mixture; the mass ratio of the second modified high-density polyethylene, silicone masterbatch, polyethylene glycol and distearyl thiodipropionate is 78:18:3:1; 7. Using multi-layer co-extrusion technology, two extruders are used to melt the outer layer mixture of the silicon core tube at 195°C and the inner layer mixture of the silicon core tube at 185°C, and then the two are composited and formed through a co-extrusion mold. After pulling and cutting, the high-density polyethylene silicon core tube is obtained.

[0038] Example 6

[0039] like Figure 2 As shown, a high-density polyethylene silicon core tube, the preparation method of which comprises the following steps: 1. The high-density polyethylene particles are subjected to ozone oxidation treatment under ultraviolet light for 8.5 hours to obtain activated high-density polyethylene particles; 2. Add activated high-density polyethylene particles to a high-speed mixer, add an ethanol solution of γ-glycidyloxypropyltrimethoxysilane in the form of a spray while stirring, and continue stirring for 9 minutes; the weight proportion of γ-glycidyloxypropyltrimethoxysilane in the ethanol solution is 2.5%; 3. Then, an ethanol solution of diethylphosphoethyltriethoxysilane coupling agent was further added in the form of a spray while stirring, and stirring was continued for 19 minutes to obtain a first modified high-density polyethylene; the weight proportion of the diethylphosphoethyltriethoxysilane coupling agent in the ethanol solution was 4%; 4. Add the first modified high-density polyethylene, mica powder, antioxidant 1010, masterbatch and glycerol monostearate into a high-speed mixer and stir at 68°C for 35 minutes to obtain a silicon core tube outer layer mixture; the mass ratio of the first modified high-density polyethylene, mica powder, antioxidant 1010, masterbatch and glycerol monostearate is 68:28:0.4:3:0.6; 5. Using a twin-screw extruder, high-density polyethylene particles, di-tert-butyl peroxide, and 3-(methacryloyloxy)propyltrimethoxysilane were melt-blended and extruded at 168° C., and cooled and granulated to obtain a second modified high-density polyethylene; the mass ratio of the high-density polyethylene particles, di-tert-butyl peroxide, and 3-(methacryloyloxy)propyltrimethoxysilane was 95:1.0:4.0; 6. Add the second modified high-density polyethylene, silicone masterbatch, fatty alcohol polyoxyethylene ether and myristyl thiodipropionate into a high-speed mixer and stir at room temperature for 13 minutes to obtain a silicone core tube inner layer mixture; the mass ratio of the second modified high-density polyethylene, silicone masterbatch, fatty alcohol polyoxyethylene ether and myristyl thiodipropionate is 72:23:4.5:0.5; 7. Using multi-layer co-extrusion technology, two extruders are used to melt the outer layer mixture of the silicon core tube at 188°C and the inner layer mixture of the silicon core tube at 178°C, and then the two are composited and formed through a co-extrusion mold. After pulling and cutting, the high-density polyethylene silicon core tube is obtained.

[0040] Comparative Example 1 A high-density polyethylene silicon core tube, the preparation method of which comprises the following steps: 1. The high-density polyethylene particles are subjected to ozone oxidation treatment under ultraviolet light for 8 hours to obtain activated high-density polyethylene particles; 2. Add the activated high-density polyethylene particles to a high-speed mixer, add the ethanol solution of γ-glycidyloxypropyltrimethoxysilane in the form of a spray while stirring, and continue stirring for 5 minutes to obtain a first modified high-density polyethylene; the mass proportion of γ-glycidyloxypropyltrimethoxysilane in the ethanol solution is 2%; 3. Add the first modified high-density polyethylene, light calcium carbonate, 2,6-di-tert-butyl-p-cresol, masterbatch and stearic acid into a high-speed mixer and stir at 60°C for 30 minutes to obtain a silicon core tube outer layer mixture; the mass ratio of the first modified high-density polyethylene, light calcium carbonate, 2,6-di-tert-butyl-p-cresol, masterbatch and stearic acid is 70:25:0.5:2.5:2; 4. Using a twin-screw extruder, high-density polyethylene particles, dicumyl peroxide, and 3-(acryloyloxy)propyltrimethoxysilane were melt-blended and extruded at 160° C., and cooled and granulated to obtain a second modified high-density polyethylene; the mass ratio of the high-density polyethylene particles, dicumyl peroxide, and 3-(acryloyloxy)propyltrimethoxysilane was 90:0.5:9.5; 5. Add the second modified high-density polyethylene, silicone masterbatch, polyethylene glycol and dilauryl thiodipropionate into a high-speed mixer and stir at room temperature for 10 minutes to obtain a silicone core tube inner layer mixture; the mass ratio of the second modified high-density polyethylene, silicone masterbatch, polyethylene glycol and dilauryl thiodipropionate is 80:15:4:1; 6. Using multi-layer co-extrusion technology, two extruders are used to melt the outer layer mixture of the silicon core tube at 180°C and the inner layer mixture of the silicon core tube at 170°C, and then the two are composited and formed through a co-extrusion mold. After pulling and cutting, the high-density polyethylene silicon core tube is obtained.

[0041] Comparative Example 2 A high-density polyethylene silicon core tube, the preparation method of which comprises the following steps: 1. The high-density polyethylene particles are subjected to ozone oxidation treatment under ultraviolet light for 12 hours to obtain activated high-density polyethylene particles; 2. Add the activated high-density polyethylene particles to a high-speed mixer, add the ethanol solution of phenyltriethoxysilane in the form of a spray while stirring, and continue stirring for 10 minutes; the weight proportion of phenyltriethoxysilane in the ethanol solution is 5%; 3. Then, an ethanol solution of diethylphosphoethyltriethoxysilane coupling agent was further added in the form of a spray while stirring, and stirring was continued for 20 minutes to obtain a first modified high-density polyethylene; the mass proportion of the diethylphosphoethyltriethoxysilane coupling agent in the ethanol solution was 8%; 4. Add the first modified high-density polyethylene, mica powder, antioxidant 1076, masterbatch and glycerol monostearate into a high-speed mixer and stir at 80°C for 60 minutes to obtain a silicon core tube outer layer mixture; the mass ratio of the first modified high-density polyethylene, mica powder, antioxidant 1076, masterbatch and glycerol monostearate is 80:15:0.2:3:1.8; 5. Using a twin-screw extruder, melt-blending and extruding high-density polyethylene particles, di-tert-butyl peroxide, and vinyl trimethoxysilane at 180° C., cooling and granulating to obtain a second modified high-density polyethylene; the mass ratio of the high-density polyethylene particles, di-tert-butyl peroxide, and vinyl trimethoxysilane is 92:1.5:6.5; 6. Add the second modified high-density polyethylene, silicone masterbatch, polyethylene glycol and myristyl thiodipropionate into a high-speed mixer and stir at room temperature for 20 minutes to obtain a silicone core tube inner layer mixture; the mass ratio of the second modified high-density polyethylene, silicone masterbatch, polyethylene glycol and myristyl thiodipropionate is 90:5:4.9:0.1; 7. Using multi-layer co-extrusion technology, two extruders are used to melt the outer layer mixture of the silicon core tube at 200°C and the inner layer mixture of the silicon core tube at 190°C, and then the two are composited and formed through a co-extrusion mold. After pulling and cutting, the high-density polyethylene silicon core tube is obtained.

[0042] Comparative Example 3 A high-density polyethylene silicon core tube, the preparation method of which comprises the following steps: 1. The high-density polyethylene particles are subjected to ozone oxidation treatment under ultraviolet light for 8.5 hours to obtain activated high-density polyethylene particles; 2. Add activated high-density polyethylene particles, mica powder, antioxidant 1010, masterbatch and glycerol monostearate into a high-speed mixer and stir at 68°C for 35 minutes to obtain a silicon core tube outer layer mixture; the mass ratio of the activated high-density polyethylene particles, mica powder, antioxidant 1010, masterbatch and glycerol monostearate is 68:28:0.4:3:0.6; 3. Add high-density polyethylene particles, silicone masterbatch, fatty alcohol polyoxyethylene ether and myristyl thiodipropionate into a high-speed mixer and stir at room temperature for 13 minutes to obtain a silicone core tube inner layer mixture; the mass ratio of the high-density polyethylene particles, silicone masterbatch, fatty alcohol polyoxyethylene ether and myristyl thiodipropionate is 72:23:4.5:0.5; 4. Using multi-layer co-extrusion technology, two extruders are used to melt the outer layer mixture of the silicon core tube at 188°C and the inner layer mixture of the silicon core tube at 178°C, and then the two are composited and formed through a co-extrusion mold. After pulling and cutting, the high-density polyethylene silicon core tube is obtained.

[0043] The high-density polyethylene silicon core tubes prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were subjected to performance tests using the following standards: The interlayer bonding strength of the prepared high-density polyethylene silicone core tube is tested in accordance with GB / T 14905-2009, and this is used to reflect the firmness of the interlayer bonding of the prepared high-density polyethylene silicone core tube.

[0044] The tensile strength of the prepared high-density polyethylene silicone core tube was tested in accordance with GB / T1040-2006, and the bending strength of the prepared high-density polyethylene silicone core tube was tested in accordance with GB / T 9341-2008. The results of the above tests reflect the mechanical properties of the prepared high-density polyethylene silicone core tube.

[0045] The oxygen index test was conducted on the prepared high-density polyethylene silicone core tube in accordance with GB / T 2406.2-2009, and the test results were used to reflect the flame retardant properties of the prepared high-density polyethylene silicone core tube. The test results are shown in Table 1.

[0046] Table 1 Test results of high-density polyethylene silicon core tubes prepared in Examples and Comparative Examples:

[0047] As shown in Table 1, all test data of the high-density polyethylene silicon-core tubes prepared in Examples 1 to 6 are better than those in Comparative Examples 1 to 3.

[0048] This is because, in the high-density polyethylene (HDPE) silicon-core tubes prepared in Examples 1-6, the HDPE in the outer layer of the silicon-core tube undergoes ozone oxidation under UV irradiation, generating surface hydroxyl groups. By modifying the HDPE with an epoxy silane coupling agent and a diethylphosphoethyltriethoxysilane coupling agent, epoxy and phosphorus-containing groups can be introduced into the HDPE. Furthermore, the HDPE in the inner layer of the silicon-core tube generates macromolecular free radicals under the action of an initiator. The silane coupling agent containing carbon-carbon double bonds then undergoes a grafting reaction with the macromolecular free radicals under molten conditions, thereby introducing groups containing silicon-oxygen bonds into the HDPE.

[0049] After being modified separately, the high-density polyethylene (HDPE) in the outer and inner layers of the silicone-core tube are more easily mixed with other components, thereby producing the silicone-core tube outer layer mixture and the silicone-core tube inner layer mixture, respectively. During co-extrusion, the epoxy groups retained in the silicone-core tube outer layer mixture further react with the groups containing silicon-oxygen bonds retained in the silicone-core tube inner layer mixture, thereby forming Si-OC chemical bonds between the silicone-core tube outer and inner layers. This significantly enhances the interlayer adhesion strength between the inner and outer layers and the mechanical properties of the resulting high-density polyethylene silicone tube. Furthermore, the phosphorus-containing groups retained in the silicone-core tube outer layer mixture are extremely difficult to migrate due to the strong bond between the inner and outer layers, thereby significantly enhancing the flame retardancy of the resulting high-density polyethylene silicone tube.

[0050] Compared with Example 1, Comparative Example 1 does not use diethylphosphinoethyltriethoxysilane coupling agent to modify the high-density polyethylene, so no phosphorus-containing groups are ultimately introduced into the outer layer of the silicon core tube. Therefore, although the interlayer bonding strength and mechanical properties of the high-density polyethylene silicon core tube finally obtained are good, its oxygen index is significantly lower than that of Example 1.

[0051] Compared with Example 3, in Comparative Example 2, although the high-density polyethylene of the inner layer and the outer layer of the silicon core tube were modified, the retained groups did not react with each other. Therefore, no chemical bonding occurred between the layers of the high-density polyethylene silicon core tube finally obtained, and thus the interlayer bonding strength and mechanical properties were significantly reduced.

[0052] Compared with Example 6, in Comparative Example 3, the high-density polyethylene of the inner layer and the outer layer of the silicon-core tube were not modified. Based on the same reasons, the interlayer bonding strength, mechanical properties and flame retardant properties of the high-density polyethylene silicon-core tube finally obtained were the worst.

[0053] The above results show and describe the basic principles and main features of this application as well as the advantages of this application.

[0054] Those skilled in the art should understand that the present application is not limited to the above-described embodiments. The above-described embodiments and descriptions are merely illustrative of the principles of the present application. Various changes and improvements may be made to the present application without departing from the spirit and scope of the present application. Such changes and improvements are intended to fall within the scope of the present application. The scope of protection claimed in the present application is defined by the equivalents of the appended claims.

Claims

1. A high-density polyethylene silicon core tube, characterized in that: The high-density polyethylene silicon core tube comprises a silicon core tube outer layer (1) and a silicon core tube inner layer (2) which are composited with each other; there is a Si-OC chemical bond between the silicon core tube outer layer (1) and the silicon core tube inner layer (2); the raw material of the silicon core tube outer layer (1) comprises a first modified high-density polyethylene; the raw material of the silicon core tube inner layer (2) comprises a second modified high-density polyethylene; the first modified high-density polyethylene is obtained by ozone oxidation treatment of high-density polyethylene particles under ultraviolet light, and then jointly modified with an epoxy silane coupling agent and a diethylphosphoethyl triethoxysilane coupling agent; the second modified high-density polyethylene is obtained by melt grafting high-density polyethylene particles with a silane coupling agent containing a carbon-carbon double bond under the action of an initiator.

2. A high-density polyethylene silicon core tube according to claim 1, characterized in that: The epoxysilane coupling agent includes any one of γ-glycidyloxypropyltrimethoxysilane, γ-glycidyloxypropylmethyldimethoxysilane, γ-glycidyloxypropyltriethoxysilane, γ-glycidyloxypropylmethyldiethoxysilane and β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane.

3. A high-density polyethylene silicon core tube according to claim 1, characterized in that: The initiator includes any one of dicumyl peroxide, tert-butyl perbenzoate and di-tert-butyl peroxide.

4. A high-density polyethylene silicon core tube according to claim 1, characterized in that: The silane coupling agent containing a carbon-carbon double bond includes any one of 3-(acryloyloxy)propyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane and vinyltrimethoxysilane; the mass ratio of the high-density polyethylene particles, the initiator and the silane coupling agent containing a carbon-carbon double bond is (90~95): (0.5~1.5): (3~10).

5. A high-density polyethylene silicon core tube according to claim 1, characterized in that: The raw materials of the outer layer (1) of the silicon core tube further include filler, a first antioxidant, a masterbatch and a lubricant; the mass ratio of the first modified high-density polyethylene, the filler, the first antioxidant, the masterbatch and the lubricant is (65-80): (15-30): (0.2-1): (1-3): (0.5-2).

6. A high-density polyethylene silicon core tube according to claim 1, characterized in that: The raw materials of the inner layer (2) of the silicon core tube further include silicone masterbatch, dispersant and second antioxidant; the mass ratio of the second modified high-density polyethylene, silicone masterbatch, dispersant and second antioxidant is (70~90): (5~25): (0.5~5): (0.1~1).

7. A high-density polyethylene silicon core tube according to claim 5, characterized in that: The filler includes one or more of light calcium carbonate, glass powder and mica powder; the first antioxidant includes one or more of 2,6-di-tert-butyl-p-cresol, antioxidant 1010, antioxidant 1076 and antioxidant GA-80; the lubricant includes one or more of stearic acid, calcium stearate and glycerol monostearate.

8. A high-density polyethylene silicon core tube according to claim 6, characterized in that: The dispersant includes at least one of polyethylene glycol and fatty alcohol polyoxyethylene ether; the second antioxidant includes one or more of dilauryl thiodipropionate, distearyl thiodipropionate and myristyl thiodipropionate.

9. The method for preparing a high-density polyethylene silicon-core tube according to any one of claims 1 to 8, wherein: The steps include: The high-density polyethylene particles are subjected to ozone oxidation treatment under ultraviolet light for 8 to 12 hours to obtain activated high-density polyethylene particles; Add the activated high-density polyethylene particles into a high-speed mixer, add the ethanol solution of epoxy silane coupling agent in the form of a spray while stirring, and continue stirring for 5-10 minutes; Then, an ethanol solution of diethylphosphoethyltriethoxysilane coupling agent was added in the form of a spray while stirring, and stirring was continued for 15 to 20 minutes to obtain a first modified high-density polyethylene; Adding the first modified high-density polyethylene, filler, first antioxidant, masterbatch and lubricant into a high-speed mixer, stirring at 60-80° C. for 30-60 minutes to obtain a silicon core tube outer layer mixture; Using a twin-screw extruder, high-density polyethylene particles, an initiator, and a silane coupling agent containing a carbon-carbon double bond are melt-blended and extruded at 160-180° C., and then cooled and granulated to obtain a second modified high-density polyethylene; Add the second modified high-density polyethylene, silicone masterbatch, dispersant and second antioxidant into a high-speed mixer and stir at room temperature for 10 to 20 minutes to obtain a silicone core tube inner layer mixture; The multi-layer co-extrusion technology is adopted, and the outer layer mixture of the silicon core tube is melted at 180-200°C and the inner layer mixture of the silicon core tube is melted at 170-190°C through two extruders respectively. The two are then composited and formed through a co-extrusion mold, and the high-density polyethylene silicon core tube is obtained after pulling and cutting.

10. The method for preparing a high-density polyethylene silicon core tube according to claim 9, wherein: In the ethanol solution of the epoxy silane coupling agent, the mass proportion of the epoxy silane coupling agent is 2-5%; in the ethanol solution of the diethylphosphoethyltriethoxysilane coupling agent, the mass proportion of the diethylphosphoethyltriethoxysilane coupling agent is 3-8%.

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