A high-strength silicon core tube and its preparation method

Abstract

The present invention relates to the technical field of silicon-core tubes and proposes a high-strength silicon-core tube and a method for preparing the same. The high-strength silicon-core tube comprises an outer layer and an inner layer. The outer layer comprises the following raw materials by weight: 60-80 parts high-density polyethylene, 8-12 parts maleic anhydride-grafted high-density polyethylene, 2-5 parts initiator, 10-20 parts filler, 1-3 parts flame retardant, and 5-7 parts auxiliary agent. The inner layer comprises the following raw materials by weight: 6-8 parts polydimethylsiloxane, 60-80 parts high-density polyethylene, 8-12 parts maleic anhydride-grafted high-density polyethylene, 2-5 parts initiator, and 1-3 parts flame retardant. The auxiliary agent includes fiber-modified polypropylene and / or an epoxy compound. The above technical solution solves the problem of low compressive strength and tensile strength in the related art.

Description

Technical Field

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

[0002] A silicon core tube is a pipe product with a built-in silicone or silicone rubber core, usually composed of an outer protective layer and an inner silicon core. As a special pipe product, silicon core tubes play an important role in the communications, power and other industries, providing reliable protection and support for the transmission of optical fiber and cable lines. Although silicon core tubes have shown good application effects in many fields, there are also some problems and challenges. For example, when silicon core tubes are used for underground pipeline communications, silicon core tubes are relatively soft and their pressure resistance is not as good as traditional plastic pipes or metal pipes. If the underground environment exerts strong pressure, it is easy to cause damage to the pipes; in the case of complex underground communication pipeline layout and complex stress environment, such as soil movement, earthquakes, etc., tensile force will be applied to the communication pipelines. Silicon core tubes are prone to breakage or tensile deformation when subjected to tension. Therefore, the development of a high-strength silicon core tube with compressive and tensile properties is an urgent problem that needs to be solved. Summary of the Invention

[0003] The present invention provides a high-strength silicon core tube and a preparation method thereof, which solves the problem of low compressive strength and tensile strength in the related art.

[0004] The technical solution of the present invention is as follows: The present invention provides a high-strength silicon core tube, comprising an outer layer and an inner layer, wherein the outer layer comprises the following raw materials in parts by weight: 60-80 parts of high-density polyethylene, 8-12 parts of maleic anhydride grafted high-density polyethylene, 2-5 parts of initiator, 10-20 parts of filler, 1-3 parts of flame retardant, and 5-7 parts of additive;

[0005] The inner layer comprises the following raw materials in parts by weight: 6-8 parts of polydimethylsiloxane, 60-80 parts of high-density polyethylene, 8-12 parts of maleic anhydride grafted high-density polyethylene, 2-5 parts of initiator, and 1-3 parts of flame retardant; the auxiliary agent comprises fiber-modified polypropylene and / or epoxy compound.

[0006] As a further technical solution, the auxiliary agent consists of fiber-modified polypropylene and an epoxy compound.

[0007] As a further technical solution, the epoxy compound includes one or more of epoxysuccinic acid, 3-epoxypropylene carboxylic acid, and (S)-epoxystyrene.

[0008] As a further technical solution, the epoxy compound is 3-propylene oxide carboxylic acid.

[0009] The carboxyl groups contained in 3-propylene oxide carboxylic acid can provide more active functional groups, forming stronger chemical bonds between the inner and outer layers, thereby enhancing the adhesion of the inner and outer layers, reducing peeling and delamination between layers, improving the interface compatibility between the inner and outer layers, and reducing the possibility of stress concentration or cracks caused by differences in the materials of the inner and outer layers, thereby further improving the overall strength of the silicon core tube.

[0010] As a further technical solution, the mass ratio of the fiber-modified polypropylene to the epoxy compound is 2-4:1.

[0011] As a further technical solution, the initiator is one or more of diisopropyl peroxide, tert-butyl peroxide, and ethyl peroxide.

[0012] As a further technical solution, the filler is one or more of carbon black, carbon nanotubes, and potassium titanate whiskers.

[0013] As a further technical solution, the flame retardant includes one or both of magnesium oxide and triphenyl phosphate.

[0014] The present invention also provides a method for preparing a high-strength silicon core tube, comprising the following steps:

[0015] S1, mixing the outer layer raw materials uniformly to obtain an outer layer mixture;

[0016] S2, mixing the inner layer raw materials uniformly to obtain an inner layer mixture;

[0017] S3. After the outer layer mixture and the inner layer mixture are heated and melted respectively, they are extruded and compounded simultaneously, and the silicon core tube is obtained after shaping.

[0018] As a further technical solution, the outer layer raw materials are mixed at a temperature of 120-130° C. and a mixing time of 50-70 min.

[0019] As a further technical solution, the temperature for mixing the inner layer raw materials is 100-120° C., and the mixing time is 30-40 minutes.

[0020] The working principle and beneficial effects of the present invention are:

[0021] In the present invention, fiber-modified polypropylene and epoxy compounds are used as auxiliary agents. Polypropylene is a commonly used plastic material. Because its molecules are usually in a straight-chain structure and there are no side chains or branches between the molecular chains, the molecular arrangement is more regular and compact, which is conducive to the transmission of external stress and the improvement of the strength and rigidity of the material. At the same time, it has a high degree of crystallinity. The molecular chains can form an orderly arrangement in the crystallized state, which increases the hardness and stability of the material. By adding reinforcing fillers such as fibers to modify the polypropylene, the strength and rigidity of the polypropylene can be improved, thereby enhancing the tensile strength and compressive strength of the HDPE silicon core tube. The epoxy group contained in the epoxy compound has active chemical reactivity and can undergo a ring-opening reaction with the hydroxyl group in the silicon core tube to form a cross-linked structure. This cross-linked structure can improve the compressive and tensile properties of the material, making it more suitable for complex use environments. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0023] In the following examples and comparative examples:

[0024] High-density polyethylene: model number is TR-144, the manufacturer is Suzhou Yuzhimei Plastic Co., Ltd.;

[0025] Maleic anhydride grafted high-density polyethylene: Model E100, manufacturer: Shanghai Jingzhengfeng Chemical Additives Co., Ltd.

[0026] Fiber-modified polypropylene: The model is polypropylene with 10% fiber modification, and the manufacturer is Suzhou Hongke Plastics Co., Ltd.

[0027] Polydimethylsiloxane: Model is ST-30, content is 30%, manufacturer is Suzhou Jingyu Biotechnology Co., Ltd.

[0028] Example 1

[0029] A method for preparing a high-strength silicon core tube comprises the following steps:

[0030] S1. Weigh 60 parts of high-density polyethylene, 8 parts of maleic anhydride-grafted high-density polyethylene, 2 parts of diisopropyl peroxide, 10 parts of carbon black, 1 part of magnesium oxide, and 5 parts of fiber-modified polypropylene, heat to 120°C, stir for 70 minutes, and mix well to obtain an outer layer mixture;

[0031] S2. Weigh 6 parts of polydimethylsiloxane, 60 parts of high-density polyethylene, 8 parts of maleic anhydride-grafted high-density polyethylene, 2 parts of diisopropyl peroxide, and 1 part of magnesium oxide, raise the temperature to 100° C., stir for 40 minutes, and mix evenly to obtain an inner layer mixture;

[0032] S3. After the outer layer mixture and the inner layer mixture are heated and melted respectively, they are extruded and compounded simultaneously, and the silicon core tube is obtained after shaping.

[0033] Example 2

[0034] A method for preparing a high-strength silicon core tube comprises the following steps:

[0035] S1. Weigh 70 parts of high-density polyethylene, 10 parts of maleic anhydride-grafted high-density polyethylene, 3.5 parts of tert-butyl peroxide, 15 parts of carbon nanotubes, 2 parts of magnesium oxide, and 6 parts of fiber-modified polypropylene, heat to 125° C., stir for 60 minutes, and mix well to obtain an outer layer mixture;

[0036] S2. Weigh 7 parts of polydimethylsiloxane, 70 parts of high-density polyethylene, 10 parts of maleic anhydride-grafted high-density polyethylene, 3.5 parts of tert-butyl peroxide, and 2 parts of magnesium oxide, raise the temperature to 110° C., stir for 35 minutes, and mix well to obtain an inner layer mixture;

[0037] S3. After the outer layer mixture and the inner layer mixture are heated and melted respectively, they are extruded and compounded simultaneously, and the silicon core tube is obtained after shaping.

[0038] Example 3

[0039] A method for preparing a high-strength silicon core tube comprises the following steps:

[0040] S1. Weigh 80 parts of high-density polyethylene, 12 parts of maleic anhydride-grafted high-density polyethylene, 5 parts of ethyl peroxide, 20 parts of potassium titanate whiskers, 3 parts of triphenyl phosphate, and 7 parts of fiber-modified polypropylene, heat to 130° C., stir for 50 minutes, and mix well to obtain an outer layer mixture;

[0041] S2. Weigh 8 parts of polydimethylsiloxane, 80 parts of high-density polyethylene, 12 parts of maleic anhydride-grafted high-density polyethylene, 5 parts of ethyl peroxide, and 3 parts of triphenyl phosphate, raise the temperature to 120° C., stir for 30 minutes, and mix well to obtain an inner layer mixture;

[0042] S3. After the outer layer mixture and the inner layer mixture are heated and melted respectively, they are extruded and compounded simultaneously, and the silicon core tube is obtained after shaping.

[0043] Example 4

[0044] Compared with Example 2, Example 4 is different in that the fiber-modified polypropylene is replaced by an equal amount of 3-propylene oxide carboxylic acid.

[0045] Example 5

[0046] Compared with Example 2, Example 5 is different in that the fiber-modified polypropylene is replaced by an equal amount of epoxysuccinic acid.

[0047] Example 6

[0048] Compared with Example 2, Example 6 is different in that the fiber-modified polypropylene is replaced by an equal amount of (S)-styrene oxide.

[0049] Example 7

[0050] Compared with Example 2, Example 7 is different in that 6 parts of fiber-modified polypropylene are replaced by 3 parts of fiber-modified polypropylene and 3 parts of 3-propylene oxide carboxylic acid.

[0051] Example 8

[0052] Compared with Example 2, Example 8 is different in that 6 parts of fiber-modified polypropylene are replaced by 4 parts of fiber-modified polypropylene and 2 parts of 3-propylene oxide carboxylic acid.

[0053] Example 9

[0054] Compared with Example 2, Example 9 is different in that 6 parts of fiber-modified polypropylene are replaced by 4.5 parts of fiber-modified polypropylene and 1.5 parts of 3-propylene oxide carboxylic acid.

[0055] Example 10

[0056] Compared with Example 2, Example 10 is different in that 6 parts of fiber-modified polypropylene are replaced with 4.8 parts of fiber-modified polypropylene and 1.2 parts of 3-propylene oxide carboxylic acid.

[0057] Example 11

[0058] Compared with Example 2, Example 11 is different in that 6 parts of fiber-modified polypropylene are replaced with 5 parts of fiber-modified polypropylene and 1 part of 3-propylene oxide carboxylic acid.

[0059] Comparative Example 1

[0060] Compared with Example 2, Comparative Example 1 is different in that fiber-modified polypropylene is not added.

[0061] The high-strength silicon core tubes prepared in Examples 1 to 11 and Comparative Example 1 were tested according to the following method:

[0062] 1. Tensile strength: Test the tensile strength of the sample according to the test method specified in GB / T 24456-2009 "High-density polyethylene silicon core tube".

[0063] 2. Maximum traction load: The maximum traction load of the test sample shall be tested in accordance with the test method specified in YD / T 841.4-2016 "Plastic Pipes for Underground Communication Pipelines Part 4: Silicon-Core Pipes".

[0064] Table 1 Performance test results of silicon core tubes prepared in Examples 1 to 11 and Comparative Example 1

[0065]

[0066] Compared with Comparative Example 1, Examples 1 to 3 added fiber-modified polypropylene. As a result, the tensile strength and maximum traction load of Examples 1 to 3 were greater than those of Comparative Example 1, indicating that the addition of fiber-modified polypropylene can enhance the tensile strength and compressive strength of the silicon-core tube, giving the silicon-core tube higher strength performance.

[0067] Compared with Examples 5 and 6, the epoxy compound added in Example 4 is 3-propylene oxide carboxylic acid. As a result, the tensile strength and maximum traction load of Example 4 are greater than those of Examples 5 and 6, indicating that the addition of 3-propylene oxide carboxylic acid helps to further improve the tensile strength and compressive strength of the silicon core tube.

[0068] Compared with Examples 1 to 4, Examples 7 to 11 simultaneously added fiber-modified polypropylene and 3-propylene oxide carboxylic acid. As a result, the tensile strength and maximum traction load of Examples 8 to 11 were greater than those of Examples 1 to 4, indicating that the fiber-modified polypropylene and 3-propylene oxide carboxylic acid exerted a synergistic effect, which could further improve the tensile strength and compressive strength of the silicon-core tube.

[0069] Compared with Example 7, Examples 8 to 11 added fiber-modified polypropylene and 3-propylene oxide carboxylic acid in different proportions. As a result, the tensile strength and maximum traction load of Examples 8 to 10 were greater than those of Examples 7 and 11, indicating that the strength of the silicon-core tube was maximum when the mass ratio of fiber-modified polypropylene and 3-propylene oxide carboxylic acid was 2 to 4:1, and the preferred ratio was 3:1.

[0070] Referring to the test methods specified in the standard GB / T 24456-2009 "High-density polyethylene silicon core tube", Examples 1 to 11 were tested for appearance, drop hammer impact resistance, cold bending radius, chemical corrosion resistance, hydraulic resistance, thermal stress cracking resistance, and hydrocarbon resistance. The test results are as follows:

[0071] Appearance: The color is uniform, the inner and outer surfaces are flat, uniform and smooth, without defects such as collapse, pits, holes, tear marks and impurity pits, the cross section is bright, without bubbles or cracks, the inner wall of the silicon core tube is tightly sintered and there is no detachment, all meeting the requirements.

[0072] Drop hammer impact resistance: At the specified temperature (normal temperature 23℃, low temperature -20℃), at a height of 2m, 10 specimens were impacted by a 15.3kg hammer, and all 10 specimens showed no cracking, meeting the qualification standards.

[0073] Cold bending radius: No cracking, cracking or obvious stress whitening.

[0074] Resistance to chemical corrosion: The samples were immersed in 5% NaCl, 40% H2SO4 and 40% NaOH solutions for 24 hours respectively, and there was no obvious fading or corrosion.

[0075] Hydraulic resistance: Under the conditions of temperature 20℃ and water pressure 2.0MPa, no cracks are visible on the samples after 15min.

[0076] Resistance to thermal stress cracking: 168h, failure rate 0.

[0077] Hydrocarbon resistance: Three sections of silicon-core tube specimens with a length of (300±1) were taken, soaked in heptane for 720 hours, taken out, drained, and left for 30 minutes. A radial pressure of 528N was applied to the silicon-core tube and maintained for 1 minute. After unloading, the specimens were immediately observed. No damage was found on the specimens, and the permanent deformation was ≤3.8%, which met the qualification standard (permanent deformation did not exceed 5%).

[0078] Therefore, the silicon-core tubes of Examples 1 to 11 of the present invention all meet the relevant requirements of the standard GB / T 24456-2009 “High-density polyethylene silicon-core tube”.

[0079] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-strength silicon core tube, characterized in that: The outer layer comprises an outer layer and an inner layer, wherein the outer layer comprises the following raw materials in parts by weight: 60-80 parts of high-density polyethylene, 8-12 parts of maleic anhydride grafted high-density polyethylene, 2-5 parts of initiator, 10-20 parts of filler, 1-3 parts of flame retardant, and 5-7 parts of auxiliary agent; The inner layer comprises the following raw materials in parts by weight: 6-8 parts of polydimethylsiloxane, 60-80 parts of high-density polyethylene, 8-12 parts of maleic anhydride grafted high-density polyethylene, 2-5 parts of initiator, and 1-3 parts of flame retardant; The auxiliary agent consists of fiber-modified polypropylene and epoxy compound; The epoxy compound includes one or more of epoxysuccinic acid, 3-propylene oxide carboxylic acid, and (S)-epoxystyrene; The mass ratio of the fiber-modified polypropylene to the epoxy compound is 2-4:

1.

2. A high-strength silicon core tube according to claim 1, characterized in that: The initiator is one or more of diisopropyl peroxide, tert-butyl peroxide and ethyl peroxide.

3. A high-strength silicon core tube according to claim 1, characterized in that: The filler is one or more of carbon black, carbon nanotubes, and potassium titanate whiskers.

4. A high-strength silicon core tube according to claim 1, characterized in that: The flame retardant includes one or both of magnesium oxide and triphenyl phosphate.

5. The method for preparing a high-strength silicon core tube according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, mixing the outer layer raw materials uniformly to obtain an outer layer mixture; S2, mixing the inner layer raw materials uniformly to obtain an inner layer mixture; S3. After the outer layer mixture and the inner layer mixture are heated and melted respectively, they are extruded and compounded simultaneously, and the silicon core tube is obtained after shaping.

6. The method for preparing a high-strength silicon core tube according to claim 5, characterized in that: The outer layer raw materials are mixed at a temperature of 120-130° C. and for a time of 50-70 minutes.

7. The method for preparing a high-strength silicon core tube according to claim 5, characterized in that: The inner layer raw materials are mixed at a temperature of 100-120° C. and for a time of 30-40 minutes.

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