Aramid pulp reinforced PVC-C mine casing pipe and preparation method thereof

Abstract

The application discloses a kind of aramid pulp reinforced PVC-C mine casing pipes and preparation methods, it is related to deep well mining casing pipe technical field, wherein, aramid pulp reinforced PVC-C mine casing pipe, raw material is by weight parts, including following components: chlorinated polyvinyl chloride 100 parts, stabilizer 5-20 parts, surface active agent 5-15 parts, aramid pulp 10-50 parts, reinforcing and compatibilizing agent 10-30 parts, impact resistance agent 10-30 parts, lubricant 0.5-30 parts, processing aid 5-40 parts;The stabilizer includes rare earth stabilizer and calcium zinc stabilizer;The surface active agent is silicon coupling agent;The reinforcing and compatibilizing agent is one or more in white carbon black, titanium white powder, light calcium carbonate;The impact resistance agent is rubber-based elastomer;The lubricant is one or two in polyethylene wax or paraffin wax;The processing aid is one or two in ACR-401 or ACR-ZB-21.The mine casing pipe prepared by the application increases the tensile strength, sealing and pressure resistance performance and impact strength of casing pipe, so that it is more suitable for new mining technology.

Description

Technical Field

[0001] This invention relates to the field of deep well mining casing technology, and in particular provides an aramid pulp-reinforced PVC-C mining casing and its preparation method, which enables the casing to have thin-walled flame-retardant properties. Background Technology

[0002] In the testing and production of casing for hydrometallurgical processes such as uranium mining and the extraction of acid, alkali, and saline minerals in deep wells, various casing materials have been used, including PVC pipes, PE pipes, stainless steel pipes, and fiberglass pipes. Successful applications of each type of casing have been documented. Due to the combined geological, hydrological, and ore body depth conditions of various mineral resources, advanced technologies for deep, high-temperature well mining globally tend to use pipes primarily made of PVC and PVC-C. Currently, the following issues need to be addressed in new deep-well liquid mining processes:

[0003] 1. Improvements in mining technology require lightweight, thin, high-strength, and large-diameter well casing:

[0004] The current outdated cementing technology is to cast cement forward to seal the sidewall ore layer. This process will produce a mixed slurry layer, which will affect the quality and efficiency of the ore fluid.

[0005] To improve mining quality and efficiency, Chinese technical researchers, drawing on international experience, adopted a reverse casting method. This method involves pressurizing and injecting cement grout into the casing, then using through-holes in the bottom casing wall to slurry into the annular space between the mine wall and the casing wall to seal the ore layer and prevent mixing of the collected fluid with the grout. Sufficient through-holes with a diameter of approximately 10-20 mm need to be pre-drilled at the bottom of the casing to allow the cement grout to solidify and seal layer by layer from the bottom upwards in the annular space, displacing any mixed grout to the surface. This new process requires the casing to possess the following properties:

[0006] a. Without increasing the outer diameter, reduce the wall thickness to increase the working inner diameter; then open a sufficient inner diameter and a hole diameter of about 10-20mm through the bottom pipe body, so that the injected mud can enter the annular gap between the casing and the well wall through the bottom through hole, squeeze the residual liquid upward and fill it to achieve the fixing effect. The high strength and small wall thickness make drilling and grouting operations convenient.

[0007] b. As the depth of various mines increases, reaching a maximum depth of 1500-2000 meters, such deep bottom layers, although having cooling systems, are still in a high-temperature geothermal environment. Therefore, the protective pipes that penetrate deep into the mine layer are required to have sufficient temperature resistance to ensure normal operation at higher temperatures, that is, the pipe material must be more resistant to high temperatures.

[0008] 2. Long-length pipe bodies in deep mines require high-strength, lightweight materials to reduce the weight load on the main body;

[0009] 3. Pipe material costs are relatively high; the goal is to reduce the thickness of the protective pipe to save 50 yuan per meter of well depth in material costs.

[0010] Under the same functional conditions, reducing the casing wall thickness ensures that the tensile strength of a 6mm thick casing is equal to that of a 15mm thick casing. Cost calculations show that, for the same material, a 6mm thick casing saves 10,000 yuan in material costs compared to a 15mm thick casing for a 200-meter deep well. Summary of the Invention

[0011] To address the aforementioned technical problems, this invention provides an aramid pulp-reinforced PVC-C mine casing and its preparation method.

[0012] This invention is achieved by providing an aramid pulp-reinforced PVC-C mine casing. The raw materials, by weight, include the following components: 100 parts chlorinated polyvinyl chloride, 5-20 parts stabilizer, 5-15 parts surfactant, 10-50 parts tear-resistant aramid pulp, 10-30 parts reinforcing and compatibilizing agent, 10-30 parts impact resistant agent, 0.5-30 parts lubricant, and 5-40 parts processing aid. The stabilizer includes rare earth stabilizers and calcium-zinc stabilizers; the surfactant is a silicon coupling agent; the reinforcing and compatibilizing agent is one or more of silica, titanium dioxide, and light calcium carbonate; the impact resistant agent is a rubber-based elastomer; the lubricant is one or two of polyethylene wax or paraffin wax; and the processing aid is one or two of ACR-401 or ACR-ZB-21.

[0013] Preferably, the calcium-zinc stabilizer is synthesized using a composite process with calcium salt, zinc salt, lubricant and antioxidant as the main components.

[0014] This invention also provides a method for preparing aramid pulp reinforced PVC-C mine casing, comprising the following steps:

[0015] 1) Tackification treatment on the surface of tear-resistant aramid pulp: Mix tear-resistant aramid pulp with stabilizer, then impregnate, heat, and stir;

[0016] 2) Weigh the thickened tear-resistant aramid pulp and other raw materials, and premix them at the starting point of the production line until they are evenly mixed;

[0017] 3) The uniform powder is immersed in the high-temperature fusion section and mixed, physically agglomerating into a viscous fluid fusion body;

[0018] 4) The high-temperature viscous fluid fusion enters the pre-specified mold cavity pressurization section of the extrusion section, forming a pre-designed tube structure, and gradually cools down;

[0019] 5) The pre-formed tube body, which is at a relatively high temperature, is shaped by the cooling section;

[0020] 6) Cut to the specified length;

[0021] 7) After testing, the finished product is obtained if it passes the inspection.

[0022] Preferably, in step 1), the tear-resistant aramid pulp is mixed with a stabilizer, soaked for 2 hours, heated to 80°C, and stirred for 10 minutes every 20 minutes.

[0023] Further optimization involves using an inorganic salt ion complexation method, which allows the aramid pulp short fibers to undergo a coordination complexation reaction with the calcium ions in the liquid calcium-zinc stabilizer, which has a unique coupling effect, and the amide bonds on the aramid polyamide molecular chain. This opens the hydrogen bonds and crystallinity in the molecular chain, increases the surface roughness of the aramid microfibers, and enhances the adhesion to the substrate.

[0024] Further preferred, in step 3), the uniform powder is immersed in a high-temperature fusion section for mixing at a temperature of 165-180°C for 9 minutes.

[0025] In a further preferred embodiment, in step 4), the temperature of the pre-designed tube structure gradually decreases from 180°C to 30°C, and the cooling time is 25 minutes.

[0026] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0027] The aramid pulp-reinforced PVC-C mine casing and its preparation method of the present invention increase the tensile strength, sealing and pressure resistance, and impact resistance of the casing, making it more adaptable to new mining processes. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0029] This invention provides an aramid pulp-reinforced PVC-C mine casing. The raw materials, by weight, include the following components: 100 parts of chlorinated polyvinyl chloride, 5-20 parts of stabilizer, 5-15 parts of surfactant, 10-50 parts of aramid pulp, 10-30 parts of reinforcing and compatibilizing agent, 10-30 parts of impact-resistant agent, 0.5-30 parts of lubricant, and 5-40 parts of processing aid.

[0030] The stabilizer includes rare earth stabilizers and calcium-zinc stabilizers; the surfactant is a silicon coupling agent; the reinforcing and compatibilizing agent is one or two of silica, light calcium carbonate, and titanium dioxide; the impact-resistant agent is a rubber elastomer; the lubricant is one or two of polyethylene wax or paraffin wax; and the processing aid is one or two of ACR-401 or ACR-ZB-21.

[0031] The above materials possess the following excellent properties:

[0032] I. Main Materials

[0033] 1. The main material of mine casing is chlorinated polyvinyl chloride, which is made by chlorinating polyvinyl chloride (PVC-V) resin.

[0034] Due to the introduction of chlorine into the polyvinyl chloride chain, the chlorine content increased from 56.4% to 63-69%.

[0035] 1) As the chlorine content increases, the intermolecular forces of the material are strengthened, thereby increasing the softening temperature and mechanical properties of the resin; the Vicat softening temperature of PVC material is 80℃, and the Vicat softening temperature of PVC-C material is 110℃, and it can be used for a long time at around 95℃.

[0036] 2) Moreover, due to the further introduction of chlorine, the polarity of the pipe wall material increases, making it easier to mix with polar fillers (containing ester, ketone, and aromatic groups) than polyvinyl chloride, thus achieving a better reinforcing effect.

[0037] 3) The increased chlorine content also improves the flame retardancy of the protective pipe.

[0038] 4) Polyvinyl chloride (PVC) with its own anti-corrosion function has enhanced intermolecular forces due to the increased chlorine content, resulting in superior resistance to corrosion from acid and alkali media and better aging resistance.

[0039] 2. Aramid pulp, as a short fiber homogeneous skeleton material, greatly increases the flexibility, impact resistance, and splitting strength of pipe wall materials.

[0040] 1) Aramid is a synthetic linear polymer composed of aromatic groups linked by polyamide. Para-structured aramid 1414 pulp-grade ultra-short fine fibers are selected. The tubes reinforced with aramid microfibers have high strength, good dimensional stability, high temperature resistance, corrosion resistance, increased impact resistance, low shrinkage, and good wear resistance.

[0041] 2) The reinforcing effect of aramid in the main material depends on the adhesion performance between aramid and the main material. An inorganic salt ion complexation method is used to allow the short aramid pulp fibers to undergo a coordination complexation reaction with the calcium ions in a liquid calcium-zinc stabilizer, which has a unique coupling effect, and the amide bonds on the aramid polyamide molecular chain. This opens the hydrogen bonds and crystallinity in the molecular chain, increases the surface roughness of the aramid microfibers, and thus enhances the adhesion to the substrate.

[0042] II. Environmentally friendly and stable system

[0043] 1. Choose stabilizers with excellent environmental performance;

[0044] PVC-C products must be heat-stabilized to prevent degradation and cracking that may occur during high-temperature fusion.

[0045] This invention employs a combination of a pollution-free rare earth stabilizer and a liquid calcium-zinc stabilizer with good wettability and unique coupling effect.

[0046] 2. Mechanism of Stabilizer Action: Rare earth compounds with strong adsorption capacity control the release of active chlorine elements in the double-bonded structure, delaying the auto-oxidation chain reaction of hydrogen chloride and thus achieving thermal stability. Calcium-zinc stabilizers are synthesized using a special composite process, with calcium salts, zinc salts, lubricants, and antioxidants as the main components. They can not only replace toxic stabilizers such as lead-cadmium salts and organotin compounds, but also possess excellent thermal stability, light stability, transparency, and coloring power. In PVC-C resin products, they exhibit good processing performance and thermal stabilization equivalent to lead-salt stabilizers, making them a good non-toxic stabilizer. The appropriate combination of rare earth elements and calcium-zinc stabilizers, with their unique synergistic effect, greatly improves thermal stability.

[0047] III. Active Reinforcing Materials

[0048] 1. Multifunctional surfactants:

[0049] Silicon coupling agent, while acting as a thickening agent to enhance the adhesion between aramid short fibers and PVC-C, adheres to the aramid short fibers and is mixed in PVC-C and a relatively large amount of light calcium carbonate powder. This improves the dispersibility of inorganic material calcium carbonate (CaCO3) in PVC-C, protects PVC-C products from corrosion when immersed in water, enhances electrical resistance, and reduces loss factors.

[0050] 2. Preferred reinforcing filler

[0051] The production of PVC-C plastic profiles prioritizes ultrafine, lightweight, activated calcium carbonate, which not only increases rigidity and acts as a filler but also modifies the profiles, reducing dimensional changes after heating, improving impact resistance, and increasing rigidity.

[0052] IV. Select lubricants and processing aids with excellent compatibility with the base material:

[0053] 1. PE wax (polyethylene wax) exhibits excellent compatibility with chlorinated polyvinyl chloride (PVC-C) and impact-resistant chlorinated polyethylene (CPE). It possesses strong polar centers and long non-polar carbon chains. The polar portions of its structure, compatible with the plastic, act as internal lubricants, while the non-polar portions, incompatible with the plastic, act as external lubricants for demolding, thus improving the production efficiency of PVC-C pipe extrusion. Paraffin wax (n-alkanes C18-30) has good moisture resistance at room temperature, strong chemical resistance, and excellent electrical properties, which can improve the appearance of the finished product.

[0054] 2. Functions of multi-functional processing aids

[0055] By selecting ACR (acrylate-based) PVC-C additives with good dispersibility, the longer molecular chains of ACR adhere to the PVC-C resin particles during the melting and extrusion processes, transferring external heat and shear forces to the resin and promoting its melting and plasticization. This reduces the processing temperature, increases melt strength, and improves product quality without reducing the rigidity of rigid PVC-C.

[0056] V. Preferred Impact-Resistant Materials

[0057] CPE (chlorinated polyethylene) with a chlorine content of 36% is selected because it has good compatibility with PVC-C and excellent low-temperature resistance. This allows it to form a dispersed phase with good bonding force with PVC-C. When subjected to impact, the dispersed phase undergoes plastic deformation and orientation, thereby absorbing a large amount of impact energy and improving the toughness and impact resistance of PVC-C.

[0058] Impact resistant agents ACR-ZB-21, MBS-LB-156, and LT-61 are all flexible composite impact resistant materials made of acrylic resins, which have heat, oxygen, and oil resistance properties.

[0059] Example 1

[0060] This embodiment 1 provides an aramid pulp-reinforced PVC-C mine casing, the raw materials of which, by weight, include the following components:

[0061]

[0062] The preparation method of the above-mentioned aramid pulp reinforced PVC-C mine casing is as follows:

[0063] 1) Tackification treatment on the surface of tear-resistant aramid pulp: Mix tear-resistant aramid pulp with stabilizer, then impregnate, heat and stir; specifically, impregnate for 2 hours, heat at 80℃, and stir for 10 minutes every 20 minutes.

[0064] 2) Weigh the thickened tear-resistant aramid pulp and other raw materials, and premix them at the starting point of the production line until they are evenly mixed;

[0065] 3) The uniform powder is immersed in the high-temperature fusion section for mixing at a temperature of 165-180℃ for 9 minutes, and then physically coagulates into a viscous fluid fusion body.

[0066] 4) The high-temperature viscous fluid fusion enters the pre-specified mold cavity pressurization section of the extrusion section to form a pre-designed tube structure, and is gradually cooled; the gradual cooling is specifically that the pre-designed tube structure is gradually cooled from 180℃ to 30℃, and the cooling time is 25 minutes.

[0067] 5) The pre-formed tube body, which is at a relatively high temperature, is shaped by the cooling section;

[0068] 6) Cut to the specified length;

[0069] 7) After testing, the finished product is obtained if it passes the inspection.

[0070] Example 2

[0071] This embodiment 2 provides an aramid pulp-reinforced PVC-C mine casing, the raw materials of which, by weight, include the following components:

[0072]

[0073] The preparation method of Example 2 is the same as that of Example 1.

[0074] Example 3

[0075] This embodiment 3 provides an aramid pulp-reinforced PVC-C mine casing, the raw materials of which, by weight, include the following components:

[0076]

[0077] The preparation method of Example 3 is the same as that of Example 1.

[0078] The sleeve prepared in Example 1 was tested, and the results are as follows:

[0079] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. An aramid pulp-reinforced PVC-C mine casing, characterized in that, The raw materials, by weight, include the following components: 100 parts chlorinated polyvinyl chloride, 5-20 parts stabilizer, 5-15 parts surfactant, 10-50 parts tear-resistant aramid pulp, 10-30 parts reinforcing and compatibilizing agent, 10-30 parts impact agent, 0.5-30 parts lubricant, and 5-40 parts processing aid. The stabilizer is composed of rare earth stabilizer and calcium-zinc stabilizer in a mass ratio of 2:5; the surfactant is a silicon coupling agent; the reinforcing and compatibilizing agent is one or more of silica, titanium dioxide, and light calcium carbonate; the impact-resistant agent is a rubber elastomer; the lubricant is one or two of polyethylene wax or paraffin wax; and the processing aid is one or two of ACR-401 or ACR-ZB-21. The preparation method of the aramid pulp reinforced PVC-C mine casing includes the following steps: 1) Tackification treatment on the surface of tear-resistant aramid pulp: Mix tear-resistant aramid pulp with stabilizer, then impregnate, heat, and stir; 2) Weigh the thickened tear-resistant aramid pulp and other raw materials, and premix them at the starting point of the production line until they are evenly mixed; 3) The uniform powder is immersed in the high-temperature fusion section and mixed, physically agglomerating into a viscous fluid fusion body; 4) The high-temperature viscous fluid fusion enters the pre-specified mold cavity pressurization section of the extrusion section, forming a pre-designed tube structure, and gradually cools down; 5) The pre-formed tube body, which is at a relatively high temperature, is shaped by the cooling section; 6) Cut to the specified length; 7) After testing, the finished product is obtained if it passes the inspection.

2. The aramid pulp-reinforced PVC-C mine casing according to claim 1, characterized in that, The calcium-zinc stabilizer is synthesized using a composite process with calcium salt, zinc salt, lubricant and antioxidant as the main components.

3. The method for preparing aramid pulp reinforced PVC-C mine casing according to claim 1 or 2, characterized in that, Includes the following steps: 1) Tackification treatment on the surface of tear-resistant aramid pulp: Mix tear-resistant aramid pulp with stabilizer, then impregnate, heat, and stir; 2) Weigh the thickened tear-resistant aramid pulp and other raw materials, and premix them at the starting point of the production line until they are evenly mixed; 3) The uniform powder is immersed in the high-temperature fusion section and mixed, physically agglomerating into a viscous fluid fusion body; 4) The high-temperature viscous fluid fusion enters the pre-specified mold cavity pressurization section of the extrusion section, forming a pre-designed tube structure, and gradually cools down; 5) The pre-formed tube body, which is at a relatively high temperature, is shaped by the cooling section; 6) Cut to the specified length; 7) After testing, the finished product is obtained if it passes the inspection.

4. The method for preparing aramid pulp reinforced PVC-C mine casing according to claim 3, characterized in that, In step 1), the tear-resistant aramid pulp is mixed with a stabilizer, soaked for 2 hours, heated to 80°C, and stirred for 10 minutes every 20 minutes.

5. The method for preparing aramid pulp reinforced PVC-C mine casing according to claim 4, characterized in that, An inorganic salt ion complexation method is used to allow the short aramid pulp fibers to undergo a coordination complexation reaction with the calcium ions in the liquid calcium-zinc stabilizer, which has a unique coupling effect, and the amide bonds on the aramid polyamide molecular chain. This opens the hydrogen bonds and crystallinity in the molecular chain, increases the surface roughness of the aramid microfibers, and enhances the adhesion to the substrate.

6. The method for preparing aramid pulp reinforced PVC-C mine casing according to claim 3, characterized in that, In step 3), the uniform powder is immersed in a high-temperature fusion section for mixing at a temperature of 165-180℃ for 9 minutes.

7. The method for preparing aramid pulp reinforced PVC-C mine casing according to claim 3, characterized in that, In step 4), the temperature of the pre-designed tube structure is gradually reduced from 180°C to 30°C, and the cooling time is 25 minutes.

Images