CN113400509B - Preparation method, device and application of modified PVC material with NTC effect - Google Patents

Abstract

The invention provides a preparation method, a device and an application of a modified PVC material with NTC effect, comprising the following steps: weighing raw materials with corresponding components according to the mass percentage; step (2), placing the raw materials into a vertical stirring cylinder, and mixing and stirring the raw materials by the vertical stirring cylinder until the raw materials are plasticized to obtain a semi-finished product; and (3) putting the semi-finished product into an extruder, and performing extrusion granulation by using the extruder to obtain the modified PVC material with the NTC effect. The invention is convenient for people to quickly replace different die heads so as to switch and produce plastic particles with different sizes, and after the die heads are replaced, the die heads and the connecting channel are tightly pressed, so that the sealing property is improved, raw materials are prevented from overflowing, the stability is higher, and the cleaning is convenient.

Description

Preparation method, device and application of modified PVC material with NTC effect

Technical Field

The invention relates to the technical field of PVC material preparation, in particular to a preparation method, a device and application of a modified PVC material with an NTC effect.

Background

NTC refers to a thermistor phenomenon and material having a negative temperature coefficient, which decreases exponentially with temperature rise. The material is a semiconductor ceramic which is prepared by fully mixing, molding, sintering and other processes of two or more than two metal oxides of manganese, copper, silicon, cobalt, iron, nickel, zinc and the like, and can be prepared into a thermistor with a Negative Temperature Coefficient (NTC). The resistivity and material constant of the material vary with the material composition ratio, sintering atmosphere, sintering temperature and structural state. Non-oxide NTC thermistor materials typified by silicon carbide, tin selenide, tantalum nitride, and the like have also been developed;

PVC, i.e., polyvinyl chloride, is a high molecular material obtained by addition polymerization of vinyl chloride, and is a third most widely produced synthetic plastic polymer after polyethylene and polypropylene, and is widely used because of its excellent properties and low price.

The PVC material applied to wires and cables in the market at present has the characteristics that the molecular acting force is reduced and the polarity is enhanced along with the rise of the temperature, the volume resistivity is slowly reduced, but the PVC material still has certain resistance at the temperature of 300 ℃ or even above 300 ℃ so as to keep the insulating property;

when the PVC material is prepared, the plasticized raw materials are added into an extruder, and then are molded and cut into granules to finally produce plastic granules;

however, when the existing extruder for producing PVC materials is used, plastic particles with different particle diameters need to be produced, the die head of the extruder cannot be quickly replaced, and the extruder is inconvenient for people to operate.

Therefore, there is a need to provide a method, an apparatus and an application for preparing a modified PVC material with NTC effect to solve the above technical problems.

Disclosure of Invention

In order to solve the technical problems, the invention provides a preparation method, a device and application of a modified PVC material with NTC effect.

The invention provides a preparation method of a modified PVC material with NTC effect, which comprises the following steps:

weighing raw materials with corresponding components according to the mass percentage;

step (2), placing the raw materials into a vertical stirring cylinder, and mixing and stirring the raw materials by the vertical stirring cylinder until the raw materials are plasticized to obtain a semi-finished product;

and (3) putting the semi-finished product into an extruder, and performing extrusion granulation by using the extruder to obtain the modified PVC material with the NTC effect.

The raw materials in the step (1) comprise the following components in percentage by mass: 50-55 parts of polyvinyl chloride resin, 8-11 parts of calcium carbonate, 10-13 parts of a meta-phenyl ester plasticizer, 11-15 parts of a polyester plasticizer, 2-4 parts of a zinc stearate/calcium stearate compound, 1-3 parts of antimony trioxide, 4-7 parts of a high molecular amide compound and 4-7 parts of a silicon compound.

Preferably, the temperature of the vertical stirring cylinder is raised to 125 ℃ to realize the plasticization of the raw materials; the temperature of the discharging section of the extruder is 140 ℃, the temperature is gradually increased to 145 ℃ section by section, and the temperature of the section of the die head (12) is set to 155 ℃.

The invention also provides a preparation device of the modified PVC material with NTC effect, which is used for the preparation method of the invention, the preparation device comprises a vertical stirring cylinder and an extruder, the extruder comprises a bottom plate, supporting plates, extruder shells, an extrusion screw, a speed reducer, a servo motor, a feeding hopper, a heating device and a granulator, the supporting plates are symmetrically fixed on the upper surface of the bottom plate, the extruder shells are fixed on the tops of the two supporting plates, the inner wall of the extruder shell is rotationally connected with the extrusion screw through a bearing, the speed reducer is fixed at one end of the upper surface of the bottom plate, the output end of the speed reducer is fixedly connected with the extrusion screw, the servo motor is fixed at one end of the speed reducer, the output end of the servo motor is fixedly connected with the input end of the speed reducer, the feeding hopper is fixed at one end of the top of the extruder shell close to the speed reducer, the heating device is fixed at equal intervals outside the extruder shell, the one end that the reduction gear was kept away from to the extruder shell is fixed with the discharge gate, discharge gate one end articulates there is the mechanism that opens and shuts, mechanism one end that opens and shuts is fixed with switching mechanism, switching mechanism one side equidistance is fixed with the die head, and the diameter of four die heads is different, the one end that the bottom plate upper surface is close to the die head is fixed with the cooling bath, the cooling bath inner wall is connected with the guide roll through bearing symmetry rotation, the one end that the bottom plate upper surface is close to the cooling bath is fixed with the pelleter.

Preferably, the mechanism that opens and shuts includes solid fixed ring, interface channel, first U-shaped piece, second U-shaped piece, bolt and nut, discharge gate one end articulates through the hinge has solid fixed ring, gu fixed ring middle part is fixed with interface channel, gu the fixed ring outside is fixed with first U-shaped piece, discharge gate outside second U-shaped piece, second U-shaped piece inner wall rotates through the pivot and is connected with the bolt, bolt one end is inserted first U-shaped piece inner wall threaded connection and is had the nut.

Preferably, the switching mechanism comprises a first fixing plate, a first rotating shaft, a limiting block, a first fixing cylinder, a limiting groove, a rotating disc, a second fixing plate, a pressing mechanism, a worm wheel and a worm, the first fixing plate is fixed at the top of the outer side of the fixing ring, the first rotating shaft is rotatably connected to the middle of the first fixing plate through a bearing, the limiting block is symmetrically fixed at the outer side of the first rotating shaft, the first fixing cylinder is sleeved at the outer side of the first rotating shaft, the limiting groove is symmetrically formed in the inner wall of the first fixing cylinder, the limiting block is slidably connected with the limiting groove, the rotating disc is fixed at one end of the first fixing cylinder, the die heads are fixed on the surface of the rotating disc at equal intervals, the second fixing plate is symmetrically fixed at one side of the first fixing plate, the worm wheel is fixed at one end of the first rotating shaft, the worm is fixed at one end of the two second fixing plates close to the worm wheel, and the worm is meshed with the worm wheel, and a compression mechanism is fixed at one end of the first fixing plate.

Preferably, the pressing mechanism comprises a rotating ring, a first fixed block, a second fixed block, a threaded rod, threaded holes, positioning rods, a first bevel gear, a second rotating shaft and a second bevel gear, the rotating ring is rotatably connected to the outer side of the first fixed cylinder through a bearing, the first fixed blocks are symmetrically fixed to the outer side of the rotating ring, the second fixed block is symmetrically fixed to one end of the first fixed plate, one end of the second fixed block is rotatably connected with the threaded rod through the bearing, the threaded hole is formed in one end of the first fixed block, the threaded rod is in threaded connection with the threaded hole, the positioning holes are equidistantly formed in the outer side of the rotating ring, the positioning rods are slidably connected to the inner wall of the positioning holes and fixedly connected with the first fixed plate, the first bevel gear is fixed to one end of the threaded rod, one ends of the two second fixed plates are rotatably connected with the second rotating shaft through bearings, and the second bevel gears are symmetrically fixed to two ends of the second rotating shaft, and the first bevel gear is in meshed connection with the second bevel gear.

Preferably, a first hexagonal knob is fixed at one end of the worm, a second hexagonal knob is fixed in the middle of the second rotating shaft, and an inner hexagonal groove is formed in the middle of the first hexagonal knob.

Preferably, one side equidistance that the die head was kept away from to the carousel is fixed with first spacing ring, first ring channel has been seted up to connect channel one end, and just first spacing ring pegs graft with first ring channel inner wall, gu fixed ring one side is fixed with the sealing ring, the seal groove has been seted up to discharge gate one side, and the sealing ring pegs graft with the seal groove inner wall.

The modified PVC material with NTC effect prepared by the invention can be applied to the manufacture of insulating materials on wires in high-temperature environments.

Compared with the related technology, the preparation method, the device and the application of the modified PVC material with the NTC effect have the following beneficial effects:

the invention provides a preparation method, a device and application of a modified PVC material with NTC effect:

when the device provided by the invention is used in the preparation method, the second hexagonal knob is rotated through the wrench, the threaded rod is driven to rotate through the first bevel gear and the second bevel gear, the threaded rod drives the first fixing block to move through the threaded hole, and then the rotating ring can be driven to move, the rotating ring drives the rotating disc to move for a certain position through the first fixing cylinder, and then the first rotating shaft is driven to rotate through the worm gear and the worm, so that the rotating disc is driven to rotate through the first fixing cylinder, the positions of the die heads are switched, people can conveniently and rapidly replace different die heads, and plastic particles with different sizes can be switched and produced;

the die head can be replaced and then the die head and the connecting channel can be compressed through the compressing mechanism, so that the sealing performance is improved, raw materials are prevented from overflowing, and the stability is high;

through rotatory nut, the bolt that overturns after meals removes the fixed of first U-shaped piece and second U-shaped piece, and people can overturn solid fixed ring to the clearance of the interior raw materials of convenient extruder shell and the clearance of the inside raw materials of die head.

The invention relates to a modified PVC material with NTC effect and a preparation method thereof, which solves the problem that the electric blanket is easy to generate overhigh temperature under the condition of heating wire failure or other uncontrolled conditions in the heating wire of the existing electric blanket, so that the electric blanket is in a fire situation, and the safety threat is caused to users.

Drawings

Fig. 1 is a schematic structural view of a heating wire for an electric blanket in the prior art;

FIG. 2 is a table showing the temperature variation of the resistance value of the inner tube made of the modified PVC material with NTC effect according to the present invention after being baked at 80 ℃ for different periods of time;

FIG. 3 is a graph plotted according to the data table of FIG. 2.

FIG. 4 is a flow chart of the preparation process provided by the present invention

FIG. 5 is a schematic view of the overall structure provided by the present invention;

FIG. 6 is a schematic view of a seal groove structure provided in the present invention;

FIG. 7 is a schematic structural diagram of a switching mechanism according to the present invention;

FIG. 8 is a schematic view of a die structure provided by the present invention;

FIG. 9 is a schematic view of a pressing mechanism provided in the present invention;

FIG. 10 is a schematic structural view of a first fixed cylinder provided by the present invention;

FIG. 11 is a second schematic structural diagram of a switching mechanism according to the present invention;

FIG. 12 is an enlarged view taken at A in FIG. 5;

fig. 13 is a schematic structural view of a first hexagonal knob according to the present invention.

The reference numbers in the figures:

100. an insulating outer tube; 200. an inner tube; 300. a heater; 400. a temperature sensing wire; 1. a base plate; 2. a support plate; 3. an extruder housing; 4. extruding a screw; 5. a speed reducer; 6. a servo motor; 7. an opening and closing mechanism; 71. a fixing ring; 72. a connecting channel; 73. a first U-shaped block; 74. a second U-shaped block; 75. a bolt; 76. a nut; 8. a switching mechanism; 81. a first fixing plate; 82. a first rotating shaft; 83. a limiting block; 84. a first fixed cylinder; 85. a limiting groove; 86. a turntable; 87. a second fixing plate; 88. a hold-down mechanism; 881. rotating the ring; 882. a first fixed block; 883. a second fixed block; 884. a threaded rod; 885. a threaded hole; 886. positioning holes; 887. positioning a rod; 888. a first bevel gear; 889. a second rotating shaft; 8810. a second bevel gear; 89. a worm gear; 810. a worm; 9. a feed hopper; 10. a heating device; 11. a discharge port; 12. a die head; 13. a cooling tank; 14. a guide roller; 15. a granulator; 16. a second hexagonal knob; 17. a first limit ring; 18. a first annular groove; 19. a seal ring; 20. a sealing groove; 21. a first hexagonal knob.

Detailed Description

The invention is further described with reference to the following figures and embodiments.

In the specific implementation process, as shown in fig. 4 and 13, a method for preparing a modified PVC material with NTC effect includes the following steps:

weighing raw materials with corresponding components according to the mass percentage; the raw materials comprise the following components in percentage by mass: 50-55 parts of polyvinyl chloride resin, 8-11 parts of calcium carbonate, 10-13 parts of a meta-phenyl ester plasticizer, 11-15 parts of a polyester plasticizer, 2-4 parts of a zinc stearate/calcium stearate compound, 1-3 parts of antimony trioxide, 4-7 parts of a high molecular amide compound and 4-7 parts of a silicon compound.

Step (2), placing the raw materials into a vertical stirring cylinder, and mixing and stirring the raw materials by the vertical stirring cylinder until the raw materials are plasticized to obtain a semi-finished product;

and (3) putting the semi-finished product into an extruder, and performing extrusion granulation by using the extruder to obtain the modified PVC material with the NTC effect. In the steps, the temperature of the vertical stirring cylinder is raised to 125 ℃ and maintained so as to plasticize the raw materials; the temperature of the discharging section of the extruder is 140 ℃, the temperature is gradually increased to 145 ℃ section by section, and the temperature of the 12-section die head is set to 155 ℃.

As shown in fig. 5, 6 and 8, the present invention further includes a device for preparing a modified PVC material with NTC effect, the device includes a vertical mixing tank, an extruder, the vertical mixing tank is a prior art, the present invention is characterized in that the extruder used by the device of the present invention includes a bottom plate 1, a supporting plate 2, an extruder housing 3, an extrusion screw 4, a speed reducer 5, a servo motor 6, a feeding hopper 9, a heating device 10 and a pellet cutter 15, the supporting plate 2 is symmetrically fixed on the upper surface of the bottom plate 1, the extruder housings 3 are fixed on the top of the two supporting plates 2, the extrusion screw 4 is rotatably connected to the inner wall of the extruder housing 3 through a bearing, the speed reducer 5 is fixed on one end of the upper surface of the bottom plate 1, the output end of the speed reducer 5 is fixedly connected to the extrusion screw 4, the servo motor 6 is fixed on one end of the speed reducer 5, and servo motor 6's output and reduction gear 5's input fixed connection, the one end that extruder shell 3 top is close to reduction gear 5 is fixed with feeder hopper 9, the 3 outside equidistance of extruder shell is fixed with heating device 10, the one end that extruder shell 3 kept away from reduction gear 5 is fixed with discharge gate 11, 11 one end of discharge gate articulates there is mechanism 7 that opens and shuts, mechanism 7 one end that opens and shuts is fixed with switching mechanism 8, 8 one side equidistance of switching mechanism is fixed with die head 12, and the diameter of four die heads 12 is different, the one end that bottom plate 1 upper surface is close to die head 12 is fixed with cooling bath 13, cooling bath 13 inner wall rotates through the bearing symmetry and is connected with guide roll 14, the one end that bottom plate 1 upper surface is close to cooling bath 13 is fixed with pelleter 15.

Referring to fig. 7, 9 and 12, the opening and closing mechanism 7 includes a fixing ring 71, a connecting channel 72, a first U-shaped block 73, a second U-shaped block 74, a bolt 75 and a nut 76, one end of the discharge port 11 is hinged to the fixing ring 71 through a hinge, the middle of the fixing ring 71 is fixed with the connecting channel 72, the outer side of the fixing ring 71 is fixed with the first U-shaped block 73, the outer side of the discharge port 11 is fixed with the second U-shaped block 74, the inner wall of the second U-shaped block 74 is connected with the bolt 75 through a shaft pin in a rotating manner, one end of the bolt 75 is inserted into the inner wall of the first U-shaped block 73 and is connected with the nut 76 in a threaded manner, the bolt 75 is turned over after meals through the rotating nut 76, the fixing of the first U-shaped block 73 and the second U-shaped block 74 is released, and the fixing ring 71 is fixed, so that the raw material in the housing 3 and the die 12 can be turned over conveniently.

Referring to fig. 7, 8, 9, 10, 11 and 12, the switching mechanism 8 includes a first fixing plate 81, a first rotating shaft 82, a limiting block 83, a first fixing cylinder 84, a limiting groove 85, a rotating disc 86, a second fixing plate 87, a pressing mechanism 88, a worm gear 89 and a worm 810, the first fixing plate 81 is fixed on the top of the outer side of the fixing ring 71, the first rotating shaft 82 is rotatably connected to the middle of the first fixing plate 81 through a bearing, the limiting block 83 is symmetrically fixed on the outer side of the first rotating shaft 82, the first fixing cylinder 84 is sleeved on the outer side of the first rotating shaft 82, the limiting groove 85 is symmetrically formed on the inner wall of the first fixing cylinder 84, the limiting block 83 is slidably connected with the limiting groove 85, the rotating disc 86 is fixed on one end of the first fixing cylinder 84, the die heads 12 are equidistantly fixed on the surface of the rotating disc 86, the second fixing plate 87 is symmetrically fixed on one side of the first fixing plate 81, a worm wheel 89 is fixed at one end of the first rotating shaft 82, a worm 810 is fixed at one end of each of the two second fixing plates 87 close to the worm wheel 89, the worm 810 is meshed with the worm wheel 89, a pressing mechanism 88 is fixed at one end of the first fixing plate 81, people rotate the first hexagonal knob 21 through a wrench to drive the worm 810 to rotate, and then the worm wheel 89 can be driven to rotate, so that the worm wheel 89 drives the first rotating shaft 82 to rotate, the first fixing cylinder 84 is driven to rotate through the limiting block 83, and then the rotating disc 86 can be driven to rotate, and the die head 12 to be used is rotated to one end of the connecting channel 72 by the rotating disc 86 and is aligned with the connecting channel 72.

Referring to fig. 7, 8, 9, 10, 11 and 13, the pressing mechanism 88 includes a rotary ring 881, a first fixing block 882, a second fixing block 883, a threaded rod 884, a threaded hole 885, a positioning hole 886, a positioning rod 887, a first bevel gear 888, a second rotating shaft 889 and a second bevel gear 8810, the rotary ring 881 is rotatably connected to the outer side of the first fixing cylinder 84 through a bearing, the first fixing block 882 is symmetrically fixed to the outer side of the rotary ring 881, the second fixing block 883 is symmetrically fixed to one end of the first fixing plate 81, the threaded rod 884 is rotatably connected to one end of the second fixing block 883 through a bearing, the threaded hole 885 is opened to one end of the first fixing block 882, the threaded rod 884 is in threaded connection with the threaded hole 885, the positioning holes 886 are equidistantly opened to the outer side of the rotary ring 881, the positioning rod 887 is slidably connected to the inner wall of the positioning hole 886, and the positioning rod 887 is fixedly connected to the first fixing plate 81, a first bevel gear 888 is fixed at one end of the threaded rod 884, a second rotating shaft 889 is rotatably connected at one end of the two second fixing plates 87 through a bearing, second bevel gears 8810 are symmetrically fixed at two ends of the second rotating shaft 889, and the first bevel gear 888 is engaged with the second bevel gear 8810, the second hexagonal knob 16 is rotated by a wrench, thereby driving the second rotating shaft 889 to rotate, and further driving the threaded rod 884 to rotate through the first bevel gear 888 and the second bevel gear 8810, so that the threaded rod 884 drives the first fixing block 882 to move through the threaded hole 885, thereby driving the rotation ring 881 to move, so that the rotation ring 881 drives the rotation disc 86 to move a certain position through the first fixing cylinder 84, so that the first stop collar 17 on the rotating disc 86 is disengaged from the first annular groove 18, so that one can rotate the rotating disc 86, by driving the first retainer ring 17 into the first annular groove 18, the connection strength and the sealing property of the die head 12 with the connecting passage 72 can be increased.

Referring to fig. 13, a first hexagonal knob 21 is fixed to one end of the worm 810, a second hexagonal knob 16 is fixed to the middle of the second rotating shaft 889, an inner hexagonal groove is formed in the middle of the first hexagonal knob 21, and the first hexagonal knob 21 and the second hexagonal knob 16 facilitate people to rotate the worm 810 and the second rotating shaft 889 through a wrench.

Referring to fig. 6, 9, 10 and 13, first limit rings 17 are fixed on one side of the rotary table 86 far away from the die head 12 at equal intervals, a first annular groove 18 is formed in one end of the connecting channel 72, the first limit rings 17 are inserted into the inner wall of the first annular groove 18, the die head 12 can be positioned and the sealing performance can be improved through the first limit rings 17 and the first annular groove 18, a sealing ring 19 is fixed on one side of the fixing ring 71, a sealing groove 20 is formed in one side of the discharge port 11, and the sealing ring 19 is inserted into the inner wall of the sealing groove 20.

The PVC prepared by the device and the method is a high-molecular thermistor material and has an NTC effect. The NTC effect is particularly a thermistor phenomenon with a negative temperature coefficient, in which the resistance decreases exponentially with the temperature rise.

According to the step (1) of the preparation method, the preparation method of the modified PVC material with NTC effect comprises the following components in percentage by mass:

50-55 parts of polyvinyl chloride resin, 8-11 parts of calcium carbonate, 10-13 parts of a meta-phenyl ester plasticizer, 11-15 parts of a polyester plasticizer, 2-4 parts of a zinc stearate/calcium stearate compound, 1-3 parts of antimony trioxide, 4-7 parts of a high molecular amide compound and 4-7 parts of a silicon compound.

In a specific embodiment, the modified PVC material with NTC effect comprises the following components in percentage by mass:

50 parts of polyvinyl chloride resin, 11 parts of calcium carbonate, 10 parts of a meta-phenyl ester plasticizer, 11 parts of a polyester plasticizer, 4 parts of a zinc stearate/calcium stearate compound, 2 parts of antimony trioxide, 6 parts of a high molecular amide compound and 6 parts of a silicon compound.

In another specific embodiment, the modified PVC material with NTC effect comprises the following components in percentage by mass:

55 parts of polyvinyl chloride resin, 8 parts of calcium carbonate, 12 parts of a meta-phenyl ester plasticizer, 14 parts of a polyester plasticizer, 2 parts of a zinc stearate/calcium stearate compound, 1 part of antimony trioxide, 4 parts of a high molecular amide compound and 4 parts of a silicon compound.

In another specific embodiment, the modified PVC material with NTC effect comprises the following components in percentage by mass:

52 parts of polyvinyl chloride resin, 9 parts of calcium carbonate, 11 parts of a meta-phenyl ester plasticizer, 12 parts of a polyester plasticizer, 3 parts of a zinc stearate/calcium stearate compound, 3 parts of antimony trioxide, 5 parts of a high molecular amide compound and 5 parts of a silicon compound.

In another specific embodiment, the modified PVC material with the NTC effect comprises the following components in percentage by mass:

53 parts of polyvinyl chloride resin, 8 parts of calcium carbonate, 10 parts of a meta-phenyl ester plasticizer, 15 parts of a polyester plasticizer, 2 parts of a zinc stearate/calcium stearate compound, 3 parts of antimony trioxide, 5 parts of a high molecular amide compound and 7 parts of a silicon compound.

The raw materials are all existing materials, and are not described herein again; PVC prepared by weighing appropriate amount of polyvinyl chloride resin, calcium carbonate, meta-phenyl ester plasticizer, polyester plasticizer, zinc stearate/calcium stearate compound, antimony trioxide, polymer amide compound and silicon compound according to the weight ratio is a polymer type thermistor material with NTC effect. The NTC effect refers to a thermistor phenomenon in which resistance decreases exponentially with temperature rise, and has a negative temperature coefficient.

Compared with the existing PVC material used for wires and cables, the PVC material has the difference that the formula of the invention adds the polymer amide compound and the silicon compound with certain specific gravity, and the prepared PVC material has NTC effect by virtue of the characteristics of the two compounds.

In the specific embodiment, because the preparation raw materials of the PVC material used for the electric wire and the cable are still remained except the macromolecular amide compound and the silicon-based compound in the formula, the PVC material prepared by the formula still keeps the basic characteristics of the PVC material used for the traditional electric wire, such as compression resistance, tearing resistance, interference resistance and the like, besides the NTC effect, so that the wire prepared by the modified PVC material with the NTC effect is ensured not to be broken when being torn and extruded by external force, namely the normal work of the electric wire is ensured, and the due insulation performance between wires is kept.

Referring to fig. 1, a conventional heating wire for an electric blanket includes an outer insulating tube 100, an inner tube 200, a heater 300, and a temperature sensor 400; wherein, the heating wire 300 is arranged inside the inner tube 200 and is mainly used for heating to ensure that the electric blanket reaches and is constant at a specific temperature value; the temperature sensing wire 400 is wrapped on the outer wall of the inner tube 200 in a winding manner, and is mainly used for transmitting temperature control information so as to drive the heating wire 300 to generate a specific temperature; the inner tube 200 serves as an insulating medium to separate the heating wire 300 and the temperature sensing wire 400 to ensure normal operation therebetween; the insulating outer tube 100 plays a role of protecting the heating wire as a whole and insulating the heating wire from the outside. The heating wire is different from the heating wire for the electric blanket, the inner pipe of the heating wire is made of the modified PVC material with the NTC effect, so that when the electric heating wire fails and generates overhigh temperature, the resistance value of the inner pipe changes to be a conductor with the resistance value approaching zero along with the temperature, even if the electric heating wire is communicated with the temperature sensing wire to form short circuit, a normal loop in the circuit is damaged, the condition that the electric blanket is on fire due to overhigh temperature generated by the electric heating wire can be effectively avoided, and the safety of a user is ensured.

In order to ensure that the inner tube made of the modified PVC material with the NTC effect can still keep the NTC characteristic after being used for a long time, the invention carries out aging test on the inner tube, namely, the inner tube is placed in a high-temperature environment for baking, and then the change of the resistance value along with the change of the temperature value is detected.

The test operation is as follows:

selecting a plurality of inner tubes made of modified PVC materials with NTC effect;

step (2), placing each inner tube at the temperature of 80 ℃ for baking for different time lengths, wherein the specific baking time in the test is 48 hours of baking, 96 hours of baking, 144 hours of baking and 192 hours of baking, and a group of unbaked inner tubes are arranged in the test as a reference group;

step (3), placing and cooling each baked inner tube for one hour, and then detecting resistance values at different temperatures; the temperature value selected in the test is 35-100 ℃, the resistance value test is carried out by taking the temperature as a temperature grade every 10 ℃, and the resistance value test is carried out by taking the temperature as a temperature grade every 5 ℃ in the temperature of 100-140 ℃.

Furthermore, each inner pipe is made of modified PVC material with NTC effect prepared by mixing polyvinyl chloride resin, calcium carbonate, meta-phenyl ester plasticizer, polyester plasticizer, zinc stearate/calcium stearate compound, antimony trioxide, high molecular amide compound and silicon compound in the same mass part.

Specifically, an inner tube is selected as a first test piece and is baked for 48 hours at the environment temperature of 80 ℃ for two times, so that the change of the resistance value of the inner tube in the state of repeated use and approximate duration is detected, and the stability of the NTC effect of the PVC material related by the invention is preliminarily judged; preferably, the test of the first test piece baked at the ambient temperature of 80 ℃ for 48 hours is not limited to two times, and can be two or more than two times, so as to ensure the accuracy of the test;

after the tests show that the NTC effect of the PVC material has stability, an inner tube is selected as a second test piece to be respectively subjected to tests of baking for 48 hours, 96 hours, 144 hours and 192 hours at the ambient temperature of 80 ℃, the test values can show whether the inner tube is aged or not in the states of multiple uses and different use durations, namely whether the inner tube can keep the required NTC characteristic or not, and the PVC material related to the invention is further judged to have the stable NTC effect.

Preferably, the inner tubes selected by the first test piece and the second test piece are the same, that is, one inner tube is subjected to a test of baking for 48 hours at 80 ℃ for two or more times, after the NTC effect of the inner tube is preliminarily determined to have stability, the inner tube is subjected to tests of baking for 96 hours, baking for 144 hours and baking for 192 hours at 80 ℃ for environmental temperature, and thus, the long-term practicability of the inner tube can be embodied.

Preferably, the length of each section of the inner pipe is five meters.

Drawing a data table and a curve chart of the resistance value changing with the temperature after the inner tube is baked at 80 ℃ for different time lengths according to the numerical values obtained by the test, and referring to fig. 2 and 3 specifically;

as can be seen from fig. 2 and 3, in the interval of 35 ℃ to 140 ℃, after the modified PVC material with NTC effect prepared by the above formula and the above preparation method is baked at 80 ℃ for different time periods, the resistance value of the PVC material detected at the same temperature has very small change, and the resistance value still changes in the same exponential relationship with the change of temperature. It can be concluded that the NTC effect of the PVC material is stable, i.e. the PVC material can still have the original NTC effect in long-term use.

The temperature of the electric blanket used in the family is mostly in the range of 35 ℃ to 75 ℃, and the electric blanket does not belong to the temperature comfortable for human body when the temperature is higher than 75 ℃, as can be seen from fig. 2 and 3, the resistance value of the inner tube is in a specific exponential relationship with the temperature rise from the original 1200K omega in the temperature range of 35 ℃ to 75 ℃ and is in a trend of sharp decrease, but the resistance value is still kept above 50K omega, and the electric blanket has enough insulation performance to ensure that the temperature sensing wire and the electric heating wire are not interfered with each other; when the temperature of the electric blanket rises to 75 ℃, the resistance value of the inner tube continuously drops, and when the temperature reaches 140 ℃, the resistance value approaches zero, namely the inner tube becomes a conductor medium, so that the electric heating wire is communicated with the temperature sensing wire, and a short circuit occurs between the electric heating wire and the temperature sensing wire, so that a circuit cannot form normal loop conduction, namely the electric heating wire does not heat any more; the existing electric blanket is characterized in that cotton or other fiber materials are filled in the electric blanket to ensure the comfort of the electric blanket, the ignition point of the cotton and most of the fiber materials is above 300 ℃, the inner tube made of the modified PVC material with the NTC effect can promote the short circuit between the heating wire and the temperature sensing wire at 140 ℃, and therefore the heating of the electric heating wire is stopped before the ignition point of the electric blanket.

In the invention, the modified PVC material with NTC effect is applied to but not limited to an inner tube as a heating wire, and can be applied to other wires operating in high-temperature environment as an insulating material; specifically, the modified PVC material with NTC effect is arranged between any two or more non-interfering wires in wires and cables in any form and any structure as an insulating layer, and when the wires are abnormally heated and reach a certain temperature value, the PVC material becomes a conductor with extremely small resistance value, so that the wires are mutually short-circuited, a normal loop of a circuit is damaged, and the safety of a user is ensured.

The invention relates to a modified PVC material with NTC effect and a preparation method thereof, which solves the problem that the electric blanket is on fire and the safety threat is caused to the user because the heating wire in the existing heating wire is easy to generate overhigh temperature under the condition of failure or other uncontrolled conditions.

When the preparation method of the modified PVC material with NTC effect provided by the invention is used for providing the preparation device, the specific device using method can be summarized as follows:

1. the raw materials mixed and plasticized by the vertical stirring cylinder are filtered and discharged into a feed hopper 9, a servo motor 6 drives an extrusion screw 4 to rotate through a speed reducer 5, the raw materials in the feed hopper 9 are conveyed to one end of a discharge port 11 and are heated by a heating device 10 in the conveying process, the raw materials enter a die head 12 through a connecting channel 72 and are extruded into a long and thin strip shape through the die head 12;

2. the strip raw material passes through a cooling tank 13, cold water is circularly added into the cooling tank 13 to cool and shape the raw material, and then the shaped strip raw material enters a granulator 15 to be granulated;

3. when different die heads 12 need to be replaced, a user rotates the second hexagonal knob 16 through a wrench to drive the second rotating shaft 889 to rotate, and then the threaded rod 884 can be driven to rotate through the first bevel gear 888 and the second bevel gear 8810, so that the threaded rod 884 drives the first fixing block 882 to move through the threaded hole 885, and then the rotating ring 881 can be driven to move, and the rotating ring 881 drives the rotating disc 86 to move a certain position through the first fixing cylinder 84, so that the first limiting ring 17 on the rotating disc 86 is separated from the first annular groove 18;

4. people rotate the first hexagonal knob 21 through a wrench to drive the worm 810 to rotate, and further drive the worm wheel 89 to rotate, so that the worm wheel 89 drives the first rotating shaft 82 to rotate, the first fixing cylinder 84 is driven to rotate through the limiting block 83, and further the rotating disc 86 can be driven to rotate, so that the die head 12 to be used is rotated to one end of the connecting channel 72 by the rotating disc 86 and is aligned with the connecting channel 72;

5. the second hexagonal knob 16 is rotated by a wrench, so that the turntable 86 drives the first limiting ring 17 to be inserted into the first annular groove 18, the die head 12 is communicated with the connecting channel 72, the die head 12 is replaced, and people can freely switch the die heads 12 of different models;

6. by rotating the nut 76, the bolt 75 is turned over after meals to release the fixation of the first U-shaped block 73 and the second U-shaped block 74, and one can turn over the fixing ring 71, thereby facilitating the cleaning of the raw material in the extruder housing 3 and the cleaning of the raw material inside the die head 12.

The circuits and controls involved in the present invention are prior art and will not be described in detail herein.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (4)

1. A preparation method of a modified PVC material with NTC effect is completed by matching a preparation device of the modified PVC material, and comprises the following steps:

weighing raw materials with corresponding components according to the mass percentage;

step (2), placing the raw materials into a vertical stirring cylinder, and mixing and stirring the raw materials by the vertical stirring cylinder until the raw materials are plasticized to obtain a semi-finished product;

step (3), putting the semi-finished product into an extruder, and performing extrusion granulation by using the extruder to obtain a modified PVC material with NTC effect; the raw materials in the step (1) comprise the following components in percentage by mass: 50-55 parts of polyvinyl chloride resin, 8-11 parts of calcium carbonate, 10-13 parts of a meta-phenyl ester plasticizer, 11-15 parts of a polyester plasticizer, 2-4 parts of a zinc stearate/calcium stearate compound, 1-3 parts of antimony trioxide, 4-7 parts of a high molecular amide compound and 4-7 parts of a silicon compound;

the preparation device comprises a vertical stirring cylinder and an extruder, wherein the extruder comprises a bottom plate (1), supporting plates (2), an extruder shell (3), extrusion screw rods (4), a speed reducer (5), a servo motor (6), a feed hopper (9), a heating device (10) and a granulator (15), and is characterized in that the supporting plates (2) are symmetrically fixed on the upper surface of the bottom plate (1), the extruder shell (3) is fixed on the tops of the two supporting plates (2), the inner wall of the extruder shell (3) is rotatably connected with the extrusion screw rods (4) through bearings, the speed reducer (5) is fixed on one end of the upper surface of the bottom plate (1), the output end of the speed reducer (5) is fixedly connected with the extrusion screw rods (4), the servo motor (6) is fixed on one end of the speed reducer (5), and the output end of the servo motor (6) is fixedly connected with the input end of the speed reducer (5), a feed hopper (9) is fixed at one end of the top of the extruder shell (3) close to the speed reducer (5), heating devices (10) are fixed on the outer side of the extruder shell (3) at equal intervals, a discharge hole (11) is fixed at one end of the extruder shell (3) far away from the speed reducer (5), one end of the discharge port (11) is hinged with an opening and closing mechanism (7), one end of the opening and closing mechanism (7) is fixed with a switching mechanism (8), die heads (12) are fixed on one side of the switching mechanism (8) at equal intervals, the diameters of the four die heads (12) are different, a cooling groove (13) is fixed at one end of the upper surface of the bottom plate (1) close to the die heads (12), the inner wall of the cooling groove (13) is symmetrically and rotatably connected with a guide roller (14) through a bearing, a granulator (15) is fixed at one end of the upper surface of the bottom plate (1) close to the cooling tank (13);

the opening and closing mechanism (7) comprises a fixing ring (71), a connecting channel (72), a first U-shaped block (73), a second U-shaped block (74), a bolt (75) and a nut (76), wherein one end of the discharge port (11) is hinged with the fixing ring (71) through a hinge, the middle part of the fixing ring (71) is fixed with the connecting channel (72), the outer side of the fixing ring (71) is fixed with the first U-shaped block (73), the outer side of the discharge port (11) is provided with the second U-shaped block (74), the inner wall of the second U-shaped block (74) is rotatably connected with the bolt (75) through a shaft pin, and one end of the bolt (75) is inserted into the inner wall of the first U-shaped block (73) and is in threaded connection with the nut (76);

the switching mechanism (8) comprises a first fixing plate (81), a first rotating shaft (82), a limiting block (83), a first fixing barrel (84), a limiting groove (85), a rotary table (86), a second fixing plate (87), a pressing mechanism (88), a worm wheel (89) and a worm (810), the top of the outer side of the fixing ring (71) is fixed with the first fixing plate (81), the middle part of the first fixing plate (81) is rotatably connected with the first rotating shaft (82) through a bearing, the limiting block (83) is symmetrically fixed on the outer side of the first rotating shaft (82), the first fixing barrel (84) is sleeved on the outer side of the first rotating shaft (82), the limiting groove (85) is symmetrically formed in the inner wall of the first fixing barrel (84), the limiting block (83) is slidably connected with the limiting groove (85), the rotary table (86) is fixed at one end of the first fixing barrel (84), the die head (12) is equidistantly fixed on the surface of the rotary table (86), second fixing plates (87) are symmetrically fixed on one side of the first fixing plate (81), a worm wheel (89) is fixed at one end of the first rotating shaft (82), worms (810) are fixed at one ends, close to the worm wheel (89), of the two second fixing plates (87), the worms (810) are meshed with the worm wheel (89), and a pressing mechanism (88) is fixed at one end of the first fixing plate (81);

the pressing mechanism (88) comprises a rotating ring (881), a first fixing block (882), a second fixing block (883), a threaded rod (884), a threaded hole (885), a positioning hole (886), a positioning rod (887), a first bevel gear (888), a second rotating shaft (889) and a second bevel gear (8810), the outer side of the first fixing cylinder (84) is rotatably connected with the rotating ring (881) through a bearing, the outer side of the rotating ring (881) is symmetrically fixed with the first fixing block (882), one end of the first fixing plate (81) is symmetrically fixed with the second fixing block (883), one end of the second fixing block (883) is rotatably connected with the threaded rod (884) through a bearing, one end of the first fixing block (882) is provided with the threaded hole (885), the threaded rod (884) is in threaded connection with the threaded hole (885), the outer side of the rotating ring (881) is provided with the positioning hole (886), the inner wall of the equidistant positioning hole (886) is in sliding connection with the positioning rod (887), and the positioning rod (887) is fixedly connected with the first fixing plate (81), one end of the threaded rod (884) is fixed with a first bevel gear (888), one end of the two second fixing plates (87) is rotatably connected with a second rotating shaft (889) through a bearing, two ends of the second rotating shaft (889) are symmetrically fixed with second bevel gears (8810), and the first bevel gear (888) is meshed with the second bevel gears (8810).

2. The method for preparing modified PVC material with NTC effect according to claim 1, wherein the temperature of the vertical mixing tank is raised to 125 ℃ to plasticize the raw material; the temperature of the discharging section of the extruder is 140 ℃, the temperature is gradually increased to 145 ℃ section by section, and the temperature of the section of the die head (12) is set to 155 ℃.

3. The method for preparing modified PVC material with NTC effect according to claim 1, wherein a first hexagonal knob (21) is fixed at one end of the worm (810), a second hexagonal knob (16) is fixed at the middle part of the second rotating shaft (889), and an inner hexagonal groove is formed at the middle part of the first hexagonal knob (21).

4. The method for preparing the modified PVC material with the NTC effect according to claim 3, wherein the first limit rings (17) are equidistantly fixed on one side of the turntable (86) away from the die head (12), the first annular groove (18) is formed in one end of the connecting channel (72), the first limit rings (17) are inserted into the inner wall of the first annular groove (18), the sealing ring (19) is fixed on one side of the fixing ring (71), the sealing groove (20) is formed in one side of the discharge port (11), and the sealing ring (19) is inserted into the inner wall of the sealing groove (20).

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