Efficient heat shrink tube preparation method and equipment thereof

Abstract

The invention relates to an efficient heat shrink tube preparation method and equipment thereof. FEP granules and modified CaSi2 are fed into an extruder to be extruded, and an FEP pipe is obtained; placing the FEP pipe in an expansion box, taking out the FEP pipe after the pressure in the FEP pipe and the pressure in the expansion box reach expansion pressure and are stabilized for a period of time and the pressure and the temperature in the expansion box and the FEP pipe are reduced to normal pressure and low-temperature oil temperature, and respectively washing the inside and the outside of the FEP pipe with water until the product meets the use requirement; the modified CaSi2 is prepared by the following steps: reacting CaSi2 powder, DMF (Dimethyl Formamide), isocyanatopropyltriethoxysilane, 4-hydroxyphenylboronic acid pinacol ester, lanthanum 5-hydroxyisophthalate, organic tin and methylbenzene, washing, carrying out suction filtration, and drying, thereby obtaining the modified CaSi2. The lanthanum 5-hydroxyisophthalate disclosed by the invention is prepared from 5-hydroxyisophthalic acid and lanthanum nitrate; the heat-shrinkable tube prepared by the invention has a relatively high heat shrinkage ratio.

Description

Technical Field

[0001] The invention relates to the technical field of heat shrinkable tubes, and in particular to an efficient method for preparing a heat shrinkable tube and equipment thereof. Background Art

[0002] Compared with other thermoplastics, fluoroplastics are widely used in food, medical, energy, aerospace, electronics and other fields due to their excellent chemical stability, heat resistance and good biocompatibility. Heat shrink tubing made of fluoroplastic FEP can tightly wrap around the surface of other materials, thus playing a reliable role in insulation, anti-sticking and anti-corrosion. This makes FEP heat shrink tubing not only have a very broad application prospect, but also play an important role in the development of various fields, especially in the development of forward-looking scientific and technological fields such as human health, green energy, and space exploration.

[0003] Chinese patent CN115716974B: relates to the technical field of heat shrink tubes, and provides a polyester heat shrink tube resistant to mechanical impact, and a preparation method and application thereof. The heat shrink tube provided by the present invention comprises the following raw materials: polyethylene terephthalate, poly(1,3-propylene glycol terephthalate), poly(1,4-butylene glycol terephthalate), polyethylene terephthalate-1,4-cyclohexanedimethanol ester, polyethylene, ethylene-butyl acrylate-glycidyl methacrylate copolymer, masterbatch and chain extender.

[0004] Chinese patent CN117774444B: discloses a highly flame-retardant and high-temperature-resistant composite heat shrinkable tube for electric vehicles and its preparation method, which relates to the technical field of heat shrinkable tubes. The body of the highly flame-retardant and high-temperature-resistant composite heat shrinkable tube for electric vehicles is divided into four layers from the inside to the outside, which are a heat shrinkable layer, an expansion layer, a hot melt layer and a protective layer. The heat shrinkable layer is made of polyolefin material, the expansion layer is made of a reheatable expansion material, the hot melt layer is made of hot melt adhesive material, and the protective layer is made of a mixture of polyurethane material, diamond powder and polyolefin material. The present invention also provides a corresponding preparation method, which specifically includes the steps of masterbatch granulation, tube extrusion, radiation cross-linking, tube expansion and tube slitting.

[0005] Chinese patent CN113001932B: relates to a heat shrink tube production system and a heat shrink tube preparation method using the system. The heat shrink tube production system includes a mixing mechanism, a melt extrusion mechanism, a cooling mechanism and a material receiving mechanism; the mixing mechanism includes a feed channel, a first mixing barrel, a second mixing barrel, a discharge channel and a connecting channel; the feed channel is connected to the bottom of the first mixing barrel, a screw that can rotate around its axis is arranged inside the first mixing barrel, and the screw runs through the entire first mixing barrel, and the two ends of the connecting channel are respectively connected to the top of the first mixing barrel and the top of the second mixing barrel, and the second mixing barrel has a plurality of baffles arranged obliquely downward inside, and the baffles are arranged in a spiral, and the bottom of the second mixing barrel is connected to the discharge channel.

[0006] The production efficiency of the heat shrink tubing in the above patents and prior art varies greatly with the product specifications, equipment form, expansion technology, etc., but is much smaller than other plastic products in general. Usually, the output per hour is only a few meters to tens of meters, and as the heat shrink ratio requirements of the heat shrink tubing increase, the production efficiency will decrease significantly. In addition, this kind of product that is mechanically conveyed and controlled by molds also has certain fluctuations in quality, such as unstable heat shrink ratio and large length changes before and after heat shrinkage, which has a significant impact on the stable application under subsequent different working conditions. Summary of the invention

[0007] In order to solve the above problems, the present invention provides an efficient method for preparing a heat shrink tube and an apparatus thereof, wherein the operating steps are as follows:

[0008] S1: According to weight, 100-200 parts of FEP pellets and 0.04-0.5 parts of modified CaSi2 are fed into an extruder for extrusion to obtain a FEP pipe;

[0009] S2: The FEP pipe is placed in an expansion box in the expansion control system, and both ends of the pipe are connected to the oil inlet pipe and the oil outlet pipe respectively; the expansion control system is used to control the expansion box and the FEP pipe to introduce lubricating oil at the expansion temperature, and the lubricating oil in the expansion box completely submerges the FEP pipe;

[0010] S3: Seal the expansion box, and continue to inject lubricating oil at the expansion temperature into the FEP tube and the expansion box through the expansion control system, so that the pressure in the FEP tube and the expansion box reaches the expansion pressure;

[0011] S4: After being stable for a period of time, the expansion box starts to slowly reduce the pressure through the expansion control system, and finally the pressure of the expansion box is close to normal pressure;

[0012] S5: After the pressure of the expansion box drops to normal pressure, the expansion control system is used to control the high-temperature oil in the expansion box to be quickly discharged, and the low-temperature oil is quickly injected through the valve switching. After the low-temperature oil level completely submerges the FEP pipe, the oil outlet valve is opened, and the expansion box and the FEP pipe are quickly cooled by continuous injection and discharge of the low-temperature oil;

[0013] S6: When the oil outlet temperature in the FEP tube approaches the low-temperature oil temperature, stop injecting oil into the FEP tube and fully open the oil outlet regulating valve to reduce the pressure in the FEP tube to normal pressure;

[0014] S7: After the pressure and temperature in the expansion box and FEP tube are reduced to normal pressure and low-temperature oil temperature, take out the FEP tube and use clean water with a certain pressure to rinse the inside and outside of the FEP tube respectively. The cleaning water can be recycled. According to the cleaning requirements, add fresh clean water until the product meets the use requirements.

[0015] The melt index of the FEP is 2-4g / 10min; the inner diameter of the FEP pipe is 0.5-10mm, the tolerance is ±0.03mm; the wall thickness is 0.15-0.35mm, and the average concentricity of the pipe is 90-92%; the pipe shall not have defects such as black spots, black lines, white spots, white lines, pits, scratches, severe creases, etc. that obviously affect the expansion stability.

[0016] The aspect ratio of the extruder is 20-26:1, the screw groove depth ratio between the screw feeding section and the metering section is 2-4:1; the extrusion temperature is 320-350°C, the screw speed is 1-2rpm, the stretching ratio is controlled to be 4-9, the extrusion speed is 1.5-2m / min, the cooling temperature is 10-20°C, and the vacuum degree is 0-0.1MPa.

[0017] The theoretical calculation formula for the maximum expansion pressure of the FEP pipe is:

[0018] P=M×(OD2-ID2) / (OD2+ID2)×μ

[0019] P——theoretical maximum expansion pressure MPa;

[0020] M——yield strength at expansion temperature MPa;

[0021] OD——FEP pipe outer diameter (mm);

[0022] ID——Inner diameter of FEP pipe (mm);

[0023] μ——the average concentricity of FEP pipe, which is equal to the minimum wall thickness / maximum wall thickness*percentage on the same cross section;

[0024] Or according to the required expansion multiple, the expansion pressure or bursting pressure at the expansion temperature is tested to obtain the expansion parameters under the expansion multiple.

[0025] The expansion control system is composed of a pressure control system, a temperature control system, an expansion box, a recovery system and related instruments, valves, pipelines, etc.; the pressure control system controls the pressure transmission of the lubricating oil through a pressure supply device, an electric precision regulating valve, an electric shut-off valve, a pressure sensor, etc.; the temperature control system controls the temperature of the lubricating oil storage tank through a heating and cooling system, thereby controlling the temperature of the oil supply; the expansion box is composed of a barrel cover structure that can be simply and easily disassembled, a pressure sensor is arranged on the cover to monitor the pressure in the expansion box, and an observation window is arranged on the barrel to monitor the situation in the barrel; the expansion box, instruments, valves, pipelines and related accessories are made of stainless steel or corrosion-resistant products that are in contact with the lubricating oil; a recovery system is set up to recover the lubricating oil in the production process, so as to facilitate the recycling of materials and energy; the pressure sensors on each system are interlocked with the corresponding regulating valves, and then program control is performed through the pressure control system; the test temperature of the temperature sensor on each system is fed back to the temperature control system for feedback control.

[0026] The expansion box is designed based on the size of the FEP pipe that can be expanded 500 meters at a time. The expansion box matches the oil change channel with a nominal diameter of DN50, and the FEP pipe matches the oil pipeline with a nominal diameter of DN10.

[0027] The lubricating oil is PEG; the high temperature oil temperature is 80-200°C, the low temperature oil temperature is 0-30°C, the temperature fluctuation tolerance is ±1°C, the pressure range is 0-2MPa, and the pressure fluctuation tolerance is ±1kPa.

[0028] The time for the expansion box to balance the pressure inside the FEP pipe is 3-8 minutes; the pressure drop rate of the expansion box is: 0-10kPa / s.

[0029] The preparation method of the modified CaSi2 comprises the following steps:

[0030] A1: Weigh 80-100 parts of CaSi2 powder by weight, add it to 500-700 parts of DMF and stir, then add 3-6 parts of isocyanatepropyltriethoxysilane, stir at 40-50°C for 100-150 minutes, filter and spin dry;

[0031] A2: Add 0.5-2 parts of 4-hydroxyphenylboronic acid pinacol ester (CAS: 269409-70-3), 0.05-0.5 parts of lanthanum 5-hydroxyisophthalate, 2-5 parts of organotin, and 1000-1200 parts of toluene, and stir at 40-50°C for 60-120 minutes;

[0032] A3: Wash, filter and dry to obtain modified CaSi2.

[0033] The 5-hydroxylanthanum isophthalate is prepared by the following steps:

[0034] B1: by weight, 18-36 parts of 5-hydroxyisophthalic acid, 34-68 parts of lanthanum nitrate, 500-600 parts of water, stirred at 70-80°C for 100-150 minutes;

[0035] B2: Evaporation to remove water gives lanthanum 5-hydroxyisophthalate.

[0036] Reaction mechanism

[0037] Introducing organic functional groups onto the surface of inorganic particles to change their surface properties:

[0038] 1. The hydroxyl groups on the surface of CaSi2 particles undergo condensation reaction with isocyanatepropyltriethoxysilane (IPTS) to obtain isocyanatepropyl CaSi2; subsequently, isocyanatepropyl CaSi2 undergoes condensation reaction with 4-hydroxyphenylboronic acid pinacol ester (CAS: 26940-73-0) and 5-hydroxyisophthalic acid lanthanum complex, respectively, to obtain CaSi2 particles with surface grafted with boric acid pinacol ester and lanthanum phthalate complex.

[0039] 2. After the introduction of isocyanate groups, new reaction sites are formed on the surface of CaSi2 particles, which can further undergo condensation reactions with hydroxyl-containing compounds such as 4-hydroxyphenylboronic acid pinacol ester and 5-hydroxyisophthalic acid lanthanum complex; these reactions are also based on the reaction between hydroxyl groups and isocyanate groups to form more complex organic-inorganic hybrid structures.

[0040] 3. Through the above two-step condensation reaction, organic groups with specific functions (such as pinacol borate and lanthanum phthalate complexes) are grafted onto the surface of CaSi2 particles; these organic groups not only change the surface properties of CaSi2 particles, but also give them new properties, such as improving compatibility with polymers and enhancing interfacial interactions.

[0041] Technical Effects

[0042] The invention discloses an efficient method for preparing a heat shrinkable tube and an apparatus thereof. Compared with the prior art, the invention has the following significant effects:

[0043] 1. Improved interface compatibility: The introduction of organic groups improves the compatibility between CaSi2 particles and FEP substrates, reduces interface defects and stress concentration, and thus improves the mechanical properties of the material.

[0044] 2. Enhanced interfacial interaction: Pinacol borate and lanthanum phthalate complexes as coupling agents can enhance the interfacial interaction between CaSi2 particles and FEP substrates; this enhanced interfacial effect helps to improve the thermal stability and dimensional stability of the material.

[0045] 3. Improved dispersibility: The surface-grafted organic groups may help the CaSi2 particles to disperse more evenly in the FEP matrix and reduce the occurrence of agglomeration; this helps to improve the overall performance of the material, including mechanical properties, thermal properties, and electrical properties.

[0046] In summary, the CaSi2 particles with surface grafted pinacol borate and lanthanum phthalate complexes significantly improved the performance of FEP heat shrink tubing through mechanisms such as improved interfacial compatibility, enhanced interfacial interaction and improved dispersibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of the FEP heat shrink tubing expansion control system. DETAILED DESCRIPTION

[0048] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0049] The shrinkage ratio of the heat shrink tubing = inner diameter before shrinkage / inner diameter after shrinkage.

[0050] Example 1

[0051] An efficient method and equipment for preparing a heat shrink tube, wherein the operating steps are as follows:

[0052] S1: 100 g FEP pellets and 0.04 g modified CaSi2 are fed into an extruder for extrusion to obtain a FEP pipe;

[0053] S2: The FEP pipe is placed in an expansion box in the expansion control system, and both ends of the pipe are connected to the oil inlet pipe and the oil outlet pipe respectively; the expansion control system is used to control the expansion box and the FEP pipe to introduce lubricating oil at the expansion temperature, and the lubricating oil in the expansion box completely submerges the FEP pipe;

[0054] S3: Seal the expansion box, and continue to inject lubricating oil at the expansion temperature into the FEP tube and the expansion box through the expansion control system, so that the pressure in the FEP tube and the expansion box reaches the expansion pressure;

[0055] S4: After being stable for a period of time, the expansion box starts to slowly reduce the pressure through the expansion control system, and finally the pressure of the expansion box is close to normal pressure;

[0056] S5: After the pressure of the expansion box drops to normal pressure, the expansion control system is used to control the high-temperature oil in the expansion box to be quickly discharged, and the low-temperature oil is quickly injected through the valve switching. After the low-temperature oil level completely submerges the FEP pipe, the oil outlet valve is opened, and the expansion box and the FEP pipe are quickly cooled by continuous injection and discharge of the low-temperature oil;

[0057] S6: When the oil outlet temperature in the FEP tube approaches the low-temperature oil temperature, stop injecting oil into the FEP tube and fully open the oil outlet regulating valve to reduce the pressure in the FEP tube to normal pressure;

[0058] S7: After the pressure and temperature in the expansion box and FEP tube are reduced to normal pressure and low-temperature oil temperature, take out the FEP tube and use clean water with a certain pressure to rinse the inside and outside of the FEP tube respectively. The cleaning water can be recycled. According to the cleaning requirements, add fresh clean water until the product meets the use requirements.

[0059] The melt index of the FEP is 2g / 10min; the inner diameter of the FEP pipe is 3.04mm, the tolerance is ±0.03mm; the wall thickness is 0.249mm, and the average concentricity of the pipe is 90%; the pipe shall not have defects such as black spots, black lines, white spots, white lines, pits, scratches, severe creases, etc. that obviously affect the expansion stability.

[0060] The aspect ratio of the extruder is 20:1, the screw groove depth ratio between the screw feeding section and the metering section is 2:1; the extrusion temperature is 320°C, the screw speed is 1rpm, the stretching ratio is controlled to 4, the extrusion speed is 1.5m / min, the cooling temperature is 10°C, and the vacuum degree is -0.03MPa.

[0061] The theoretical calculation formula for the maximum expansion pressure of the FEP pipe is:

[0062] P=M×(OD2-ID2) / (OD2+ID2)×μ

[0063] P——theoretical maximum expansion pressure MPa;

[0064] M——yield strength at expansion temperature MPa;

[0065] OD——FEP pipe outer diameter (mm);

[0066] ID——Inner diameter of FEP pipe (mm);

[0067] μ——the average concentricity of FEP pipe, which is equal to the minimum wall thickness / maximum wall thickness*percentage on the same cross section;

[0068] Or according to the required expansion multiple, the expansion pressure or bursting pressure at the expansion temperature is tested to obtain the expansion parameters under the expansion multiple.

[0069] The expansion control system is composed of a pressure control system, a temperature control system, an expansion box, a recovery system and related instruments, valves, pipelines, etc.; the pressure control system controls the pressure transmission of the lubricating oil through a pressure supply device, an electric precision regulating valve, an electric shut-off valve, a pressure sensor, etc.; the temperature control system controls the temperature of the lubricating oil storage tank through a heating and cooling system, thereby controlling the temperature of the oil supply; the expansion box is composed of a barrel cover structure that can be simply and easily disassembled, a pressure sensor is arranged on the cover to monitor the pressure in the expansion box, and an observation window is arranged on the barrel to monitor the situation in the barrel; the expansion box, instruments, valves, pipelines and related accessories are made of stainless steel or corrosion-resistant products that are in contact with the lubricating oil; a recovery system is set up to recover the lubricating oil in the production process, so as to facilitate the recycling of materials and energy; the pressure sensors on each system are interlocked with the corresponding regulating valves, and then program control is performed through the pressure control system; the test temperature of the temperature sensor on each system is fed back to the temperature control system for feedback control.

[0070] The expansion box is designed based on the size of the FEP pipe that can be expanded 500 meters at a time. The expansion box matches the oil change channel with a nominal diameter of DN50, and the FEP pipe matches the oil pipeline with a nominal diameter of DN10.

[0071] The lubricating oil is PEG; the high temperature oil temperature is 80°C, the low temperature oil temperature is 0°C, the temperature fluctuation tolerance is ±1°C, the pressure range is 1MPa, and the pressure fluctuation tolerance is ±1kPa.

[0072] The time for the pressure in the expansion box and the FEP pipe to be balanced is 3 minutes; the pressure drop rate of the expansion box is: 5 kPa / s.

[0073] The preparation method of the modified CaSi2 comprises the following steps:

[0074] A1: Weigh 80g of CaSi2 powder, add it to 500g of DMF and stir, then add 3g of isocyanatepropyltriethoxysilane, stir at 40℃ for 100 minutes, filter and spin dry;

[0075] A2: Add 0.5 g of 4-hydroxyphenylboronic acid pinacol ester (CAS: 269409-70-3), 0.05 g of lanthanum 5-hydroxyisophthalate, 2 g of organotin, and 1000 g of toluene, and stir at 40° C. for 60 minutes;

[0076] A3: Wash, filter and dry to obtain modified CaSi2.

[0077] The 5-hydroxylanthanum isophthalate is prepared by the following steps:

[0078] B1: 18 g 5-hydroxyisophthalic acid, 34 g lanthanum nitrate, 500 g water, stirred at 70°C for 100 minutes;

[0079] B2: Evaporation to remove water gives lanthanum 5-hydroxyisophthalate.

[0080] Example 2

[0081] An efficient method and equipment for preparing a heat shrink tube, wherein the operating steps are as follows:

[0082] S1: 140 g FEP pellets and 0.2 g modified CaSi2 are fed into an extruder for extrusion to obtain a FEP pipe;

[0083] S2: The FEP pipe is placed in an expansion box in the expansion control system, and both ends of the pipe are connected to the oil inlet pipe and the oil outlet pipe respectively; the expansion control system is used to control the expansion box and the FEP pipe to introduce lubricating oil at the expansion temperature, and the lubricating oil in the expansion box completely submerges the FEP pipe;

[0084] S3: Seal the expansion box, and continue to inject lubricating oil at the expansion temperature into the FEP tube and the expansion box through the expansion control system, so that the pressure in the FEP tube and the expansion box reaches the expansion pressure;

[0085] S4: After being stable for a period of time, the expansion box starts to slowly reduce the pressure through the expansion control system, and finally the pressure of the expansion box is close to normal pressure;

[0086] S5: After the pressure of the expansion box drops to normal pressure, the expansion control system is used to control the high-temperature oil in the expansion box to be quickly discharged, and the low-temperature oil is quickly injected through the valve switching. After the low-temperature oil level completely submerges the FEP pipe, the oil outlet valve is opened, and the expansion box and the FEP pipe are quickly cooled by continuous injection and discharge of the low-temperature oil;

[0087] S6: When the oil outlet temperature in the FEP tube approaches the low-temperature oil temperature, stop injecting oil into the FEP tube and fully open the oil outlet regulating valve to reduce the pressure in the FEP tube to normal pressure;

[0088] S7: After the pressure and temperature in the expansion box and FEP tube are reduced to normal pressure and low-temperature oil temperature, take out the FEP tube and use clean water with a certain pressure to rinse the inside and outside of the FEP tube respectively. The cleaning water can be recycled. According to the cleaning requirements, add fresh clean water until the product meets the use requirements.

[0089] The melt index of the FEP is 3g / 10min; the inner diameter of the FEP pipe is 3.03mm, the tolerance is ±0.03mm; the wall thickness is 0.253mm, and the average concentricity of the pipe is 91%; the pipe shall not have defects such as black spots, black lines, white spots, white lines, pits, scratches, severe creases, etc. that obviously affect the expansion stability.

[0090] The aspect ratio of the extruder is 22:1, the screw groove depth ratio between the screw feeding section and the metering section is 3:1; the extrusion temperature is 330°C, the screw speed is 1rpm, the stretching ratio is controlled to 6, the extrusion speed is 1.6m / min, the cooling temperature is 15°C, and the vacuum degree is -0.05MPa.

[0091] The theoretical calculation formula for the maximum expansion pressure of the FEP pipe is:

[0092] P=M×(OD2-ID2) / (OD2+ID2)×μ

[0093] P——theoretical maximum expansion pressure MPa;

[0094] M——yield strength at expansion temperature MPa;

[0095] OD——FEP pipe outer diameter (mm);

[0096] ID——Inner diameter of FEP pipe (mm);

[0097] μ——the average concentricity of FEP pipe, which is equal to the minimum wall thickness / maximum wall thickness*percentage on the same cross section;

[0098] Or according to the required expansion multiple, the expansion pressure or bursting pressure at the expansion temperature is tested to obtain the expansion parameters under the expansion multiple.

[0099] The expansion control system is composed of a pressure control system, a temperature control system, an expansion box, a recovery system and related instruments, valves, pipelines, etc.; the pressure control system controls the pressure transmission of the lubricating oil through a pressure supply device, an electric precision regulating valve, an electric shut-off valve, a pressure sensor, etc.; the temperature control system controls the temperature of the lubricating oil storage tank through a heating and cooling system, thereby controlling the temperature of the oil supply; the expansion box is composed of a barrel cover structure that can be simply and easily disassembled, a pressure sensor is arranged on the cover to monitor the pressure in the expansion box, and an observation window is arranged on the barrel to monitor the situation in the barrel; the expansion box, instruments, valves, pipelines and related accessories are made of stainless steel or corrosion-resistant products that are in contact with the lubricating oil; a recovery system is set up to recover the lubricating oil in the production process, so as to facilitate the recycling of materials and energy; the pressure sensors on each system are interlocked with the corresponding regulating valves, and then program control is performed through the pressure control system; the test temperature of the temperature sensor on each system is fed back to the temperature control system for feedback control.

[0100] The expansion box is designed based on the size of the FEP pipe that can be expanded 500 meters at a time. The expansion box matches the oil change channel with a nominal diameter of DN50, and the FEP pipe matches the oil pipeline with a nominal diameter of DN10.

[0101] The lubricating oil is PEG; the high temperature oil temperature is 120°C, the low temperature oil temperature is 10°C, the temperature fluctuation tolerance is ±1°C, the pressure range is 1MPa, and the pressure fluctuation tolerance is ±1kPa.

[0102] The time for the expansion box to balance the pressure inside the FEP pipe is 5 minutes; the pressure drop rate of the expansion box is: 5 kPa / s.

[0103] The preparation method of the modified CaSi2 comprises the following steps:

[0104] A1: Weigh 85g of CaSi2 powder, add it to 550g of DMF and stir, then add 4g of isocyanatepropyltriethoxysilane, stir at 45°C for 110 minutes, filter and spin dry;

[0105] A2: Add 1 g of 4-hydroxyphenylboronic acid pinacol ester (CAS: 269409-70-3), 0.2 g of lanthanum 5-hydroxyisophthalate, 3 g of organotin, and 1050 g of toluene, and stir at 45°C for 80 minutes;

[0106] A3: Wash, filter and dry to obtain modified CaSi2.

[0107] The 5-hydroxylanthanum isophthalate is prepared by the following steps:

[0108] B1: 24 g 5-hydroxyisophthalic acid, 45 g lanthanum nitrate, 540 g water, stirred at 75 ° C for 110 minutes;

[0109] B2: Evaporation to remove water gives lanthanum 5-hydroxyisophthalate.

[0110] Example 3

[0111] An efficient method and equipment for preparing a heat shrink tube, wherein the operating steps are as follows:

[0112] S1: 180 g FEP pellets and 0.4 g modified CaSi2 are fed into an extruder for extrusion to obtain a FEP pipe;

[0113] S2: The FEP pipe is placed in an expansion box in the expansion control system, and both ends of the pipe are connected to the oil inlet pipe and the oil outlet pipe respectively; the expansion control system is used to control the expansion box and the FEP pipe to introduce lubricating oil at the expansion temperature, and the lubricating oil in the expansion box completely submerges the FEP pipe;

[0114] S3: Seal the expansion box, and continue to inject lubricating oil at the expansion temperature into the FEP tube and the expansion box through the expansion control system, so that the pressure in the FEP tube and the expansion box reaches the expansion pressure;

[0115] S4: After being stable for a period of time, the expansion box starts to slowly reduce the pressure through the expansion control system, and finally the pressure of the expansion box is close to normal pressure;

[0116] S5: After the pressure of the expansion box drops to normal pressure, the expansion control system is used to control the high-temperature oil in the expansion box to be quickly discharged, and the low-temperature oil is quickly injected through the valve switching. After the low-temperature oil level completely submerges the FEP pipe, the oil outlet valve is opened, and the expansion box and the FEP pipe are quickly cooled by continuous injection and discharge of the low-temperature oil;

[0117] S6: When the oil outlet temperature in the FEP tube approaches the low-temperature oil temperature, stop injecting oil into the FEP tube and fully open the oil outlet regulating valve to reduce the pressure in the FEP tube to normal pressure;

[0118] S7: After the pressure and temperature in the expansion box and FEP tube are reduced to normal pressure and low-temperature oil temperature, take out the FEP tube and use clean water with a certain pressure to rinse the inside and outside of the FEP tube respectively. The cleaning water can be recycled. According to the cleaning requirements, add fresh clean water until the product meets the use requirements.

[0119] The melt index of the FEP is 3g / 10min; the inner diameter of the FEP pipe is 3.03mm, the tolerance is ±0.03mm; the wall thickness is 0.252mm, and the average concentricity of the pipe is 91%; the pipe shall not have defects such as black spots, black lines, white spots, white lines, pits, scratches, severe creases, etc. that obviously affect the expansion stability.

[0120] The aspect ratio of the extruder is 24:1, the screw groove depth ratio between the screw feeding section and the metering section is 3:1; the extrusion temperature is 340°C, the screw speed is 2rpm, the stretching ratio is controlled to 7, the extrusion speed is 1.8m / min, the cooling temperature is 15°C, and the vacuum degree is -0.08MPa.

[0121] The theoretical calculation formula for the maximum expansion pressure of the FEP pipe is:

[0122] P=M×(OD2-ID2) / (OD2+ID2)×μ

[0123] P——theoretical maximum expansion pressure MPa;

[0124] M——yield strength at expansion temperature MPa;

[0125] OD——FEP pipe outer diameter (mm);

[0126] ID——Inner diameter of FEP pipe (mm);

[0127] μ——the average concentricity of FEP pipe, which is equal to the minimum wall thickness / maximum wall thickness*percentage on the same cross section;

[0128] Or according to the required expansion multiple, the expansion pressure or bursting pressure at the expansion temperature is tested to obtain the expansion parameters under the expansion multiple.

[0129] The expansion control system is composed of a pressure control system, a temperature control system, an expansion box, a recovery system and related instruments, valves, pipelines, etc.; the pressure control system controls the pressure transmission of the lubricating oil through a pressure supply device, an electric precision regulating valve, an electric shut-off valve, a pressure sensor, etc.; the temperature control system controls the temperature of the lubricating oil storage tank through a heating and cooling system, thereby controlling the temperature of the oil supply; the expansion box is composed of a barrel cover structure that can be simply and easily disassembled, a pressure sensor is arranged on the cover to monitor the pressure in the expansion box, and an observation window is arranged on the barrel to monitor the situation in the barrel; the expansion box, instruments, valves, pipelines and related accessories are made of stainless steel or corrosion-resistant products that are in contact with the lubricating oil; a recovery system is set up to recover the lubricating oil in the production process, so as to facilitate the recycling of materials and energy; the pressure sensors on each system are interlocked with the corresponding regulating valves, and then program control is performed through the pressure control system; the test temperature of the temperature sensor on each system is fed back to the temperature control system for feedback control.

[0130] The expansion box is designed based on the size of the FEP pipe that can be expanded 500 meters at a time. The expansion box matches the oil change channel with a nominal diameter of DN50, and the FEP pipe matches the oil pipeline with a nominal diameter of DN10.

[0131] The lubricating oil is PEG; the high temperature oil temperature is 160°C, the low temperature oil temperature is 20°C, the temperature fluctuation tolerance is ±1°C, the pressure range is 1MPa, and the pressure fluctuation tolerance is ±1kPa.

[0132] The time for the pressure in the expansion box and the FEP pipe to be balanced is 7 minutes; the pressure drop rate of the expansion box is: 8 kPa / s.

[0133] The preparation method of the modified CaSi2 comprises the following steps:

[0134] A1: Weigh 95g of CaSi2 powder, add it to 650g of DMF and stir, then add 5g of isocyanatepropyltriethoxysilane, stir at 45°C for 140 minutes, filter and spin dry;

[0135] A2: Add 1.5 g of 4-hydroxyphenylboronic acid pinacol ester (CAS: 269409-70-3), 0.4 g of lanthanum 5-hydroxyisophthalate, 4 g of organotin, and 1150 g of toluene, and stir at 45° C. for 100 minutes;

[0136] A3: Wash, filter and dry to obtain modified CaSi2.

[0137] The 5-hydroxylanthanum isophthalate is prepared by the following steps:

[0138] B1: 32g 5-hydroxyisophthalic acid, 60g lanthanum nitrate, 580g water, stirred at 75°C for 140 minutes;

[0139] B2: Evaporation to remove water gives lanthanum 5-hydroxyisophthalate.

[0140] Example 4

[0141] An efficient method and equipment for preparing a heat shrink tube, wherein the operating steps are as follows:

[0142] S1: 200 g FEP pellets and 0.5 g modified CaSi2 are fed into an extruder for extrusion to obtain a FEP pipe;

[0143] S2: The FEP pipe is placed in an expansion box in the expansion control system, and both ends of the pipe are connected to the oil inlet pipe and the oil outlet pipe respectively; the expansion control system is used to control the expansion box and the FEP pipe to introduce lubricating oil at the expansion temperature, and the lubricating oil in the expansion box completely submerges the FEP pipe;

[0144] S3: Seal the expansion box, and continue to inject lubricating oil at the expansion temperature into the FEP tube and the expansion box through the expansion control system, so that the pressure in the FEP tube and the expansion box reaches the expansion pressure;

[0145] S4: After being stable for a period of time, the expansion box starts to slowly reduce the pressure through the expansion control system, and finally the pressure of the expansion box is close to normal pressure;

[0146] S5: After the pressure of the expansion box drops to normal pressure, the expansion control system is used to control the high-temperature oil in the expansion box to be quickly discharged, and the low-temperature oil is quickly injected through the valve switching. After the low-temperature oil level completely submerges the FEP pipe, the oil outlet valve is opened, and the expansion box and the FEP pipe are quickly cooled by continuous injection and discharge of the low-temperature oil;

[0147] S6: When the oil outlet temperature in the FEP tube approaches the low-temperature oil temperature, stop injecting oil into the FEP tube and fully open the oil outlet regulating valve to reduce the pressure in the FEP tube to normal pressure;

[0148] S7: After the pressure and temperature in the expansion box and FEP tube are reduced to normal pressure and low-temperature oil temperature, take out the FEP tube and use clean water with a certain pressure to rinse the inside and outside of the FEP tube respectively. The cleaning water can be recycled. According to the cleaning requirements, add fresh clean water until the product meets the use requirements.

[0149] The melt index of the FEP is 4g / 10min; the inner diameter of the FEP pipe is 3.05mm, the tolerance is ±0.03mm; the wall thickness is 0.257mm, and the average concentricity of the pipe is 92%; the pipe shall not have defects such as black spots, black lines, white spots, white lines, pits, scratches, severe creases, etc. that obviously affect the expansion stability.

[0150] The aspect ratio of the extruder is 26:1, the screw groove depth ratio between the screw feeding section and the metering section is 4:1; the extrusion temperature is 350°C, the screw speed is 2rpm, the stretching ratio is controlled to 9, the extrusion speed is 2m / min, the cooling temperature is 20°C, and the vacuum degree is -0.1MPa.

[0151] The theoretical calculation formula for the maximum expansion pressure of the FEP pipe is:

[0152] P=M×(OD2-ID2) / (OD2+ID2)×μ

[0153] P——theoretical maximum expansion pressure MPa;

[0154] M——yield strength at expansion temperature MPa;

[0155] OD——FEP pipe outer diameter (mm);

[0156] ID——Inner diameter of FEP pipe (mm);

[0157] μ——the average concentricity of FEP pipe, which is equal to the minimum wall thickness / maximum wall thickness*percentage on the same cross section;

[0158] Or according to the required expansion multiple, the expansion pressure or bursting pressure at the expansion temperature is tested to obtain the expansion parameters under the expansion multiple.

[0159] The expansion control system is composed of a pressure control system, a temperature control system, an expansion box, a recovery system and related instruments, valves, pipelines, etc.; the pressure control system controls the pressure transmission of the lubricating oil through a pressure supply device, an electric precision regulating valve, an electric shut-off valve, a pressure sensor, etc.; the temperature control system controls the temperature of the lubricating oil storage tank through a heating and cooling system, thereby controlling the temperature of the oil supply; the expansion box is composed of a barrel cover structure that can be simply and easily disassembled, a pressure sensor is arranged on the cover to monitor the pressure in the expansion box, and an observation window is arranged on the barrel to monitor the situation in the barrel; the expansion box, instruments, valves, pipelines and related accessories are all made of stainless steel or corrosion-resistant products that are in contact with the lubricating oil; a recovery system is set up to recover the lubricating oil in the production process, so as to facilitate the recycling of materials and energy; the pressure sensors on each system are interlocked with the corresponding regulating valves, and then program control is performed through the pressure control system; the test temperature of the temperature sensor on each system is fed back to the temperature control system for feedback control.

[0160] The expansion box is designed based on the size of the FEP pipe that can be expanded 500 meters at a time. The expansion box matches the oil change channel with a nominal diameter of DN50, and the FEP pipe matches the oil pipeline with a nominal diameter of DN10.

[0161] The lubricating oil is PEG; the high temperature oil temperature is 200°C, the low temperature oil temperature is 30°C, the temperature fluctuation tolerance is ±1°C, the pressure range is 2MPa, and the pressure fluctuation tolerance is ±1kPa.

[0162] The time for the expansion box to balance the pressure inside the FEP pipe is 8 minutes; the pressure drop rate of the expansion box is: 10 kPa / s.

[0163] The preparation method of the modified CaSi2 comprises the following steps:

[0164] A1: Weigh 100g of CaSi2 powder, add it to 700g of DMF and stir, then add 6g of isocyanatepropyltriethoxysilane, stir at 50℃ for 150 minutes, filter and spin dry;

[0165] A2: Add 2 g of 4-hydroxyphenylboronic acid pinacol ester (CAS: 269409-70-3), 0.5 g of lanthanum 5-hydroxyisophthalate, 5 g of organotin, and 1200 g of toluene, and stir at 50° C. for 120 minutes;

[0166] A3: Wash, filter and dry to obtain modified CaSi2.

[0167] The 5-hydroxy lanthanum isophthalate is prepared by the following steps:

[0168] B1: 36 g 5-hydroxyisophthalic acid, 68 g lanthanum nitrate, 600 g water, stirred at 80°C for 150 minutes;

[0169] B2: Evaporation to remove water gives lanthanum 5-hydroxyisophthalate.

[0170] Comparative Example 1

[0171] No modified CaSi2 is added, and the rest is the same as in Example 1.

[0172] Comparative Example 2

[0173] The other steps were the same as in Example 1 except that lanthanum 5-hydroxyisophthalate was not added.

[0174] Comparative Example 3

[0175] The other steps were the same as in Example 1 except that 4-hydroxyphenylboronic acid pinacol ester was not added.

[0176]

[0177] Through the data analysis of the above embodiments and comparative examples, the heat shrinkable tube prepared by the present invention has a higher heat shrinkage ratio.

[0178] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An efficient method and equipment for preparing a heat shrink tube, wherein the operating steps are as follows: S1: According to weight, 100-200 parts of FEP pellets and 0.04-0.5 parts of modified CaSi2 are fed into an extruder for extrusion to obtain a FEP pipe; S2: The FEP pipe is placed in an expansion box in the expansion control system, and both ends of the pipe are connected to the oil inlet pipe and the oil outlet pipe respectively; the expansion control system is used to control the expansion box and the FEP pipe to introduce lubricating oil at the expansion temperature, and the lubricating oil in the expansion box completely submerges the FEP pipe; S3: Seal the expansion box, and continue to inject lubricating oil at the expansion temperature into the FEP tube and the expansion box through the expansion control system, so that the pressure in the FEP tube and the expansion box reaches the expansion pressure; S4: After being stable for a period of time, the expansion box starts to slowly reduce the pressure through the expansion control system, and finally the pressure of the expansion box is close to normal pressure; S5: After the pressure of the expansion box drops to normal pressure, the expansion control system is used to control the high-temperature oil in the expansion box to be quickly discharged, and the low-temperature oil is quickly injected through the valve switching. After the low-temperature oil level completely submerges the FEP pipe, the oil outlet valve is opened, and the expansion box and the FEP pipe are quickly cooled by continuous injection and discharge of the low-temperature oil; S6: When the oil outlet temperature in the FEP tube approaches the low-temperature oil temperature, stop injecting oil into the FEP tube and fully open the oil outlet regulating valve to reduce the pressure in the FEP tube to normal pressure; S7: After the pressure and temperature in the expansion box and FEP tube are reduced to normal pressure and low-temperature oil temperature, take out the FEP tube and use clean water with a certain pressure to rinse the inside and outside of the FEP tube respectively. The cleaning water can be recycled. According to the cleaning requirements, add fresh clean water until the product meets the use requirements.

2. The method and device for preparing an efficient heat shrink tube according to claim 1, characterized in that: The melt index of the FEP is 2-4g / 10min; the inner diameter of the FEP pipe is 0.5-10mm, the tolerance is ±0.03mm; the wall thickness is 0.15-0.35mm, and the average concentricity of the pipe is 90-92%; the pipe shall not have defects such as black spots, black lines, white spots, white lines, pits, scratches, severe creases, etc. that obviously affect the expansion stability.

3. The method and device for preparing an efficient heat shrink tube according to claim 1, characterized in that: The aspect ratio of the extruder is 20-26:1, the screw groove depth ratio between the screw feeding section and the metering section is 2-4:1; the extrusion temperature is 320-350°C, the screw speed is 1-2rpm, the stretching ratio is controlled to be 4-9, the extrusion speed is 1.5-2m / min, the cooling temperature is 10-20°C, and the vacuum degree is 0-0.1MPa.

4. The method and device for preparing an efficient heat shrink tube according to claim 1, characterized in that: The theoretical calculation formula for the maximum expansion pressure of the FEP pipe is: P=M×(OD2-ID2) / (OD2+ID2)×μ P——theoretical maximum expansion pressure MPa; M——yield strength at expansion temperature MPa; OD——FEP pipe outer diameter (mm); ID——Inner diameter of FEP pipe (mm); μ——the average concentricity of FEP pipe, which is equal to the minimum wall thickness / maximum wall thickness*percentage on the same cross section; Or according to the required expansion multiple, the expansion pressure or bursting pressure at the expansion temperature is tested to obtain the expansion parameters under the expansion multiple.

5. The method and device for preparing an efficient heat shrink tube according to claim 1, characterized in that: The expansion control system is composed of a pressure control system, a temperature control system, an expansion box, a recovery system and related instruments, valves, pipelines, etc. The pressure control system controls the pressure transmission of the lubricating oil through a pressure supply device, an electric precision regulating valve, an electric shut-off valve, a pressure sensor, etc. The temperature control system controls the temperature of the lubricating oil storage tank through a heating and cooling system, thereby controlling the temperature of the oil supply. The expansion box is composed of a barrel cover structure that can be simply and easily disassembled. A pressure sensor is set on the cover to monitor the pressure in the expansion box, and an observation window is set on the barrel to monitor the situation in the barrel. The expansion box, instruments, valves, pipes and related accessories that come into contact with the lubricating oil are made of stainless steel or corrosion-resistant products. A recovery system is set up to recycle the lubricating oil in the production process to facilitate the recycling of materials and energy. The pressure sensors on each system are interlocked with the corresponding regulating valves, and then program controlled through the pressure control system; the test temperature of the temperature sensors on each system is fed back to the temperature control system for feedback control.

6. The method and device for preparing an efficient heat shrink tube according to claim 1, characterized in that: The expansion box is designed based on the size of the FEP pipe that can be expanded by 500 meters at a time. The expansion box matches the oil change channel with a nominal diameter of DN50, and the FEP pipe matches the oil pipeline with a nominal diameter of DN10.

7. The method and device for preparing an efficient heat shrink tube according to claim 1, characterized in that: The lubricating oil is PEG; the high temperature oil temperature is 80-200°C, the low temperature oil temperature is 0-30°C, the temperature fluctuation tolerance is ±1°C, the pressure range is 0-2MPa, and the pressure fluctuation tolerance is ±1kPa.

8. The method and device for preparing an efficient heat shrink tube according to claim 1, characterized in that: The time for the expansion box to balance the pressure inside the FEP pipe is 3-8 minutes; the pressure drop rate of the expansion box is: 0-10kPa / s.

9. The efficient heat shrink tube preparation method and equipment according to claim 1, characterized in that: The preparation method of the modified CaSi2 comprises the following steps: A1: Weigh 80-100 parts of CaSi2 powder by weight, add it to 500-700 parts of DMF and stir, then add 3-6 parts of isocyanatepropyltriethoxysilane, stir at 40-50°C for 100-150 minutes, filter and spin dry; A2: Add 0.5-2 parts of 4-hydroxyphenylboronic acid pinacol ester, 0.05-0.5 parts of lanthanum 5-hydroxyisophthalate, 2-5 parts of organotin, and 1000-1200 parts of toluene, and stir at 40-50°C for 60-120 minutes; A3: Wash, filter and dry to obtain modified CaSi2.

10. The method and device for preparing an efficient heat shrink tube according to claim 9, characterized in that: The 5-hydroxylanthanum isophthalate is prepared by the following steps: B1: by weight, 18-36 parts of 5-hydroxyisophthalic acid, 34-68 parts of lanthanum nitrate, 500-600 parts of water, stirred at 70-80°C for 100-150 minutes; B2: Evaporation to remove water gives lanthanum 5-hydroxyisophthalate.

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