Preparation method of uniaxially stretched polyester film strip

Abstract

The invention provides a preparation method of a uniaxially stretched polyester film strip, which comprises the following steps: S1, adding pure resin into a drying tank, and drying at 150-170 DEG C for 2 hours; according to the preparation method of the uniaxially stretched polyester film strip, a three-time uniaxially stretching mode is adopted, one-time stretching is hot stretching, and small-multiple stretching is carried out before a PET melt is cooled; the secondary stretching is carried out at the temperature above the glass-transition temperature, the sheet is softened by preheating and far infrared heating, and a relatively low stretching temperature is used because the orientation degree of the sheet is relatively low; the three times of stretching are heated through the drying oven, the stretching temperature is higher, and meanwhile, the stretching acting force is increased in cooperation with the opposite clamping rollers, so that molecular chains can be better oriented in the longitudinal direction, meanwhile, the crystallinity is high, phonon vibration is easier to transmit in the longitudinal direction, and the heat conduction performance of the uniaxial stretching PET film strip is obviously improved.

Description

Technical Field

[0001] The invention relates to the field of polymer material processing, and in particular to a method for preparing a uniaxially stretched polyester film tape. Background Art

[0002] Polyethylene terephthalate (abbreviated as polyester) is a type of engineering plastic with excellent performance developed in the 1950s. It is a polymer material formed by esterification reaction of terephthalic acid and ethylene glycol. Polyester material can usually be processed into film by biaxial stretching. The product has the advantages of high mechanical strength, good transparency, low price, good dimensional stability, good insulation performance, etc. It is widely used in liquid crystal displays, tapes, insulated motors, food packaging, photovoltaic power generation and other fields.

[0003] In the prior art, the preparation method of polyester film usually adopts biaxial stretching or simple uniaxial stretching process. Although biaxial stretching can improve the strength and optical properties of the film to a certain extent, the effect on improving the thermal conductivity is limited. The simple uniaxial stretching process often cannot fully orient the molecular chains, and the crystallinity is not high enough, resulting in difficulty in significantly improving the thermal conductivity.

[0004] Therefore, it is necessary to provide a method for preparing a uniaxially stretched polyester film tape to solve the above technical problems. Summary of the invention

[0005] The present invention provides a method for preparing a uniaxially stretched polyester film tape, which solves the problems that the improvement of thermal conductivity by biaxial stretching is limited and simple uniaxial stretching cannot fully orient the molecular chains, resulting in low crystallinity and making it difficult to significantly improve the thermal conductivity.

[0006] In order to solve the above technical problems, the present invention provides a method for preparing a uniaxially stretched polyester film tape, comprising the following steps:

[0007] S1. Add pure resin into a drying tank at a drying temperature of 150-170°C for 2 hours;

[0008] S2. Put the dried resin into the melt extrusion equipment, the extrusion temperature is 280-290℃, the single screw extruder, the screw diameter is 35-65mm, the screw length-diameter ratio is 40:1-48:1, and the effective width of the die head is 400mm;

[0009] S3. After the sheet is extruded, before the melt solidifies on the cooling roller, the molten sheet is subjected to a heat stretching. The stretching multiple is adjusted by the cooling roller speed. The stretching multiple is controlled at 1.3-1.6 times. The cooling roller temperature is about 15°C.

[0010] S4. The PET film strip after primary stretching is heated by a preheating roller, the temperature of the preheating roller is 70-90°C, and is heated by far infrared in the secondary stretching zone. The secondary stretching multiple is adjusted by the speed of the secondary stretching roller, and the secondary stretching multiple is controlled at 3.2-4.3 times. After stretching, the film strip is appropriately cooled;

[0011] S5. After secondary stretching, the film strip enters the tertiary preheating oven, the oven temperature is 140-170℃, and the secondary stretching multiple is adjusted by the secondary stretching roller speed. Because the molecular chain has been clearly oriented during the secondary stretching, the crystallinity becomes higher, so the tertiary stretching temperature is higher, and the stretching rollers are sandwiched by two rollers, both of which are active rollers to increase the stretching force. The stretching multiple is controlled at 2.5-3.5 times;

[0012] S6. After three stretching steps, the film strip is cooled and then rolled up.

[0013] Preferably, the PET resin may be a homopolymer PET resin, or a copolymer PET resin modified with isophthalic acid, or a PETG or PCTG resin may be selected.

[0014] Preferably, the intrinsic viscosity of the PET resin is 0.67-0.85 dl / g, and more preferably the intrinsic viscosity is 0.7-0.78 dl / g.

[0015] Preferably, the screw diameter of the single-screw extruder is 35-65 mm, and the screw aspect ratio is 40:1-48:1.

[0016] Preferably, the winding speed of the uniaxially stretched film tape is 15-25 m / min, and the thickness of the uniaxially stretched film tape is 0.02-0.06 mm.

[0017] Preferably, a cooling roller is used in the S3 step, and the cooling roller comprises a roller body, a plurality of cooling tubes are fixedly installed inside the roller body, fixing rings are fixedly installed at both ends of the roller body, one end of the outer side surfaces of the two fixing rings is provided with a groove, a bearing is fixedly installed on the inner side surface of the groove, a rotating ring is fixedly installed on the outer side surface of the bearing, a threaded ring is fixedly installed on the inner side surface of the rotating ring, a diverter frame is threadedly connected to the inner side surface of the threaded ring, a support shaft is fixedly installed on one side of the diverter frame, and a water pipe is rotatably connected to the inside of one end of the support shaft.

[0018] Preferably, a plurality of through holes are opened on the other side of the diverter frame, and a plurality of clamping rings are fixedly installed on the other side of the diverter frame, and the plurality of clamping rings are respectively arranged on the outer side surfaces of the plurality of through holes, and the inner side surfaces of the plurality of through holes are all provided with fixing rods, one end of the outer side surface of the fixing rod is threadedly connected with a threaded sleeve, and the threaded sleeve is fixedly installed inside the diverter frame, and the other end of the fixing rod is fixedly installed with a fixing seat, and a connecting rod is fixedly installed on the outer side surface of the fixing seat, and a scraping ring is fixedly installed on the outer side surface of the connecting rod, and the outer side surface of the scraping ring is fitted to the inner side surface of the cooling pipe.

[0019] Preferably, sealing rings are fixedly mounted on both ends of the cooling tube, and both ends of the cooling tube are clamped with inner side surfaces of the clamping rings.

[0020] Preferably, both ends of one end of the rotating circle are fixedly mounted with side plates, the internal threads of the side plates are connected with threaded rods, one end of the threaded rod is fixedly mounted with a rotating plate, and the other end of the threaded rod is rotatably connected with a clamping plate.

[0021] Preferably, the clamping plate is attached to a side surface of the diverter frame.

[0022] Compared with the related art, the preparation method of the uniaxially stretched polyester film tape provided by the present invention has the following beneficial effects:

[0023] The invention provides a preparation method of a uniaxially stretched polyester film tape. The method adopts three uniaxially stretched methods. The first stretching is hot stretching, and a small multiple stretching is performed before the PET melt is cooled; the second stretching is performed above the glass transition temperature, and softening is achieved by preheating and far-infrared heating of the sheet material. A relatively low stretching temperature is used because the orientation degree of the sheet material is low; the third stretching is performed by heating in an oven, and the stretching temperature is higher. At the same time, the stretching force of the clamping roller is increased, so that the molecular chain can be better oriented in the longitudinal direction, and the crystallinity is high, which makes the phonon vibration easier to transmit in the longitudinal direction, so that the thermal conductivity of the uniaxially stretched PET film tape is significantly improved, which is beneficial to the heat extraction of the heat generating part, reduces the working temperature of the product, and improves the service life of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic flow chart of a first embodiment of a method for preparing a uniaxially stretched polyester film tape provided by the present invention;

[0025] Figure 2 A schematic structural diagram of a second embodiment of a method for preparing a uniaxially stretched polyester film tape provided by the present invention;

[0026] Figure 3 for Figure 1 The schematic diagram of the cross-sectional structure of the roller body shown;

[0027] Figure 4 for Figure 1 The schematic diagram of the roller end surface structure shown;

[0028] Figure 5 for Figure 3 An enlarged schematic diagram of part A is shown;

[0029] Figure 6 for Figure 5 The schematic diagram of the fixed rod structure shown;

[0030] Figure 7 for Figure 6 The schematic diagram of the bottom structure of the eradication circle shown;

[0031] Figure 8 This is a schematic structural diagram of a third embodiment of a method for preparing a uniaxially stretched polyester film tape provided by the present invention.

[0032] Numbers in the figure: 1. roller body, 11. cooling pipe, 12. sealing ring, 2. fixing ring, 21. groove, 22. bearing, 23. rotating ring, 24. threaded ring, 3. diverter frame, 31. supporting shaft, 32. water pipe, 33. through hole, 34. clamping ring, 35. threaded sleeve, 36. fixing rod, 37. fixing seat, 38. connecting rod, 39. scraping ring, 4. side plate, 41. threaded rod, 42. rotating plate, 43. clamping plate. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.

[0034] First embodiment

[0035] Please refer to Figure 1 ,in, Figure 1 A schematic flow chart of a first embodiment of a method for preparing a uniaxially stretched polyester film tape provided by the present invention. A method for preparing a uniaxially stretched polyester film tape comprises: S1, adding pure resin into a drying tank, the drying temperature is 150-170°C, and the drying time is 2 hours;

[0036] S2. Put the dried resin into the melt extrusion equipment, the extrusion temperature is 280-290℃, the single screw extruder, the screw diameter is 35-65mm, the screw length-diameter ratio is 40:1-48:1, and the effective width of the die head is 400mm;

[0037] S3. After the sheet is extruded, before the melt solidifies on the cooling roller, the molten sheet is subjected to a heat stretching. The stretching multiple is adjusted by the cooling roller speed. The stretching multiple is controlled at 1.3-1.6 times. The cooling roller temperature is about 15°C.

[0038] S4. The PET film strip after primary stretching is heated by a preheating roller, the temperature of the preheating roller is 70-90°C, and is heated by far infrared in the secondary stretching zone. The secondary stretching multiple is adjusted by the speed of the secondary stretching roller, and the secondary stretching multiple is controlled at 3.2-4.3 times. After stretching, the film strip is appropriately cooled;

[0039] S5. After secondary stretching, the film strip enters the tertiary preheating oven, the oven temperature is 140-170℃, and the secondary stretching multiple is adjusted by the secondary stretching roller speed. Because the molecular chain has been clearly oriented during the secondary stretching, the crystallinity becomes higher, so the tertiary stretching temperature is higher, and the stretching rollers are sandwiched by two rollers, both of which are active rollers to increase the stretching force. The stretching multiple is controlled at 2.5-3.5 times;

[0040] S6. After three stretching steps, the film strip is cooled and then rolled up.

[0041] The PET resin may be a homopolymer PET resin, or a copolymer PET resin modified with isophthalic acid, or a PETG or PCTG resin may be used.

[0042] The intrinsic viscosity of the PET resin is 0.67-0.85 dl / g, and more preferably the intrinsic viscosity is 0.7-0.78 dl / g.

[0043] The screw diameter of the single-screw extruder is 35-65 mm, and the screw length-to-diameter ratio is 40:1-48:1.

[0044] The winding speed of the uniaxially stretched film tape is 15-25 m / min, and the thickness of the uniaxially stretched film tape is 0.02-0.06 mm.

[0045] By combining the film drawing process with the wire drawing process, the PET molecular chain is unidirectionally stretched to orient it in a single direction, which leads to a rapid increase in the crystallinity of PET. Compared with the biaxially stretched film, the unidirectional film tape is obviously whiter, and the dimensional stability of the film tape is significantly improved;

[0046] The obtained uniaxially stretched film tape maintains the appearance of the film, but the internal molecular chain tends to be fiber-shaped. The film tape has ultra-high tensile strength and can be cut into narrow strips for winding applications. It has application value in cable coating and other fields.

[0047] The uniaxially stretched PET film tape prepared by the method of the present invention is simple, has small equipment changes, strong operability, excellent product performance, strong practicality and good repeatability, and is an effective method for realizing the production of high-multiple uniaxially stretched film tapes;

[0048] The obtained uniaxially stretched PET film tape has higher heat resistance, mainly due to its significantly improved crystallinity, and can be used in heat-resistant motors and high-temperature use environments. At the same time, high crystallinity can effectively improve the aging resistance of PET materials, such as hydrolysis resistance and UV resistance.

[0049] Compared with the related art, the preparation method of the uniaxially stretched polyester film tape provided by the present invention has the following beneficial effects:

[0050] By adopting three uniaxial stretching methods, the first stretching is hot stretching, and a small multiple stretching is performed before the PET melt is cooled; the second stretching is performed above the glass transition temperature, and the sheet is softened by preheating and far-infrared heating. A relatively low stretching temperature is used due to the low orientation degree of the sheet; the third stretching is heated in an oven, and the stretching temperature is higher. At the same time, the stretching force on the clamping roller is increased, so that the molecular chains can be better oriented in the longitudinal direction. At the same time, the crystallinity is high, which makes the phonon vibration easier to transmit in the longitudinal direction, so that the thermal conductivity of the uniaxially stretched PET film tape is significantly improved, which is beneficial to the heat extraction of the heat-generating parts, reduces the working temperature of the parts, and increases the service life of the products.

[0051] Second embodiment

[0052] Please refer to Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 Based on the method for preparing a uniaxially stretched polyester film tape provided in the first embodiment of the present application, the second embodiment of the present application provides another method for preparing a uniaxially stretched polyester film tape. The second embodiment is only a preferred embodiment of the first embodiment, and the implementation of the second embodiment will not affect the independent implementation of the first embodiment.

[0053] Specifically, the second embodiment of the present application provides a method for preparing a uniaxially stretched polyester film tape. The difference is that, in a method for preparing a uniaxially stretched polyester film tape, a cooling roller is used in the S3 step, and the cooling roller includes a roller body 1, and a plurality of cooling tubes 11 are fixedly installed inside the roller body 1, and fixed rings 2 are fixedly installed at both ends of the roller body 1, and one end of the outer side surfaces of the two fixed rings 2 is provided with a groove 21, and a bearing 22 is fixedly installed on the inner side surface of the groove 21, and a rotating ring 23 is fixedly installed on the outer side surface of the bearing 22, and a threaded ring 24 is fixedly installed on the inner side surface of the rotating ring 23, and a diverter frame 3 is threadedly connected to the inner side surface of the threaded ring 24, and a support shaft 31 is fixedly installed on one side of the diverter frame 3, and a water pipe 32 is rotatably connected to the inside of one end of the support shaft 31.

[0054] A plurality of through holes 33 are opened on the other side of the diverter frame 3, and a plurality of clamping rings 34 are fixedly installed on the other side of the diverter frame 3. The plurality of clamping rings 34 are respectively arranged on the outer side surfaces of the plurality of through holes 33, and the inner side surfaces of the plurality of through holes 33 are all provided with fixing rods 36. A threaded sleeve 35 is threadedly connected to one end of the outer side surface of the fixing rod 36, and the threaded sleeve 35 is fixedly installed inside the diverter frame 3. A fixing seat 37 is fixedly installed on the other end of the fixing rod 36, and a connecting rod 38 is fixedly installed on the outer side surface of the fixing seat 37. A scraping ring 39 is fixedly installed on the outer side surface of the connecting rod 38, and the outer side surface of the scraping ring 39 is attached to the inner side surface of the cooling pipe 11.

[0055] Sealing rings 12 are fixedly mounted on both ends of the cooling pipe 11 , and both ends of the cooling pipe 11 are clamped with the inner side surfaces of the clamping ring 34 .

[0056] When in use, the support shaft 31 is installed on the frame, and the polyester film belt is placed on the top of the roller body 1, so that the polyester film belt moves on the surface of the roller body 1, and at the same time, the cooling water is transported from the water pipe 32 at one end of the roller body 1 to the inner side of the diverter frame 3, and then transported to the inner side of the other diverter frame 3 through the cooling pipe 11, and then discharged through the other water pipe 32, so as to achieve the effect of cooling the roller body 1;

[0057] During installation, the sealing ring 12 on the end face of the cooling pipe 11 abuts against the side face of the diverter frame 3, thereby achieving a sealing effect between the cooling pipe 11 and the diverter frame 3;

[0058] After installation, the scraper ring 39 is located at one end of the cooling pipe 11, so that when the fixing rod 36 is pulled, the scraper ring 39 can be moved from one end of the cooling pipe 11 to the other end, thereby cleaning the entire cooling pipe 11;

[0059] During use, the user can rotate the fixing rod 36 to thread one end of the fixing rod 36 down from the inner side surface of the threaded sleeve 35 , thereby disassembling the fixing rod 36 from the diverter frame 3 .

[0060] The working principle of the preparation method of a uniaxially stretched polyester film tape provided by the present invention is as follows:

[0061] After long-term use, when the scale inside the cooling tube 11 needs to be cleaned, the user can rotate the rotating circle 23 so that the rotating circle 23 drives the threaded circle 24 to be threaded down from the top of the diverter frame 3, and then pull the diverter frame 3 to make the clamping ring 34 fall off from the outer side of the cooling tube 11, so that the diverter frame 3 drives the fixing rod 36 and the scraping circle 39 to move. At this time, since the outer side of the scraping circle 39 is attached to the inner side of the cooling tube 11, the scraping circle 39 can clean the scale adhered to the inner wall of the cooling tube 11 when it moves.

[0062] Compared with the related art, the preparation method of the uniaxially stretched polyester film tape provided by the present invention has the following beneficial effects:

[0063] The fixed rod 36 is driven to move by the diverter frame 3, and then the fixed rod 36 drives the scraper ring 39 to move on the inner side of the cooling pipe 11, so that the scale adhered to the inner wall of the cooling pipe 11 can be cleaned, and the operation is convenient and quick.

[0064] Third embodiment

[0065] Please refer to Figure 8 Based on the method for preparing a uniaxially stretched polyester film tape provided in the first embodiment of the present application, the third embodiment of the present application proposes another method for preparing a uniaxially stretched polyester film tape. The third embodiment is only a preferred embodiment of the first embodiment, and the implementation of the third embodiment will not affect the independent implementation of the first embodiment.

[0066] Specifically, the difference of the preparation method of a uniaxially stretched polyester film tape provided in the third embodiment of the present application is that, in a preparation method of a uniaxially stretched polyester film tape, both ends of one end of the rotating circle 23 are fixedly installed with side panels 4, the internal threads of the side panel 4 are connected with a threaded rod 41, one end of the threaded rod 41 is fixedly installed with a rotating plate 42, and the other end of the threaded rod 41 is rotatably connected with a clamping plate 43.

[0067] The clamping plate 43 is attached to the side surface of the diverter frame 3 .

[0068] The working principle of the preparation method of a uniaxially stretched polyester film tape provided by the present invention is as follows:

[0069] After rotating the rotating circle 23, the user can rotate the rotating plate 42 so that the rotating plate 42 drives the threaded rod 41 to be threadedly connected inside the side plate 4, so that one end of the threaded rod 41 drives the clamping plate 43 to move toward one side of the diverter frame 3, so that one side of the clamping plate 43 abuts against the side of the diverter frame 3, thereby limiting the rotating circle 23.

[0070] Compared with the related art, the preparation method of the uniaxially stretched polyester film tape provided by the present invention has the following beneficial effects:

[0071] By cooperating with each other through structures such as the side plate 4, the threaded rod 41, the rotating plate 42 and the clamping plate 43, when in use, the rotating plate 42 drives the threaded rod 41 to be threadedly connected inside the side plate 4, so that one side of the clamping plate 43 abuts against the side of the diverter frame 3, thereby limiting the rotating circle 23.

[0072] Fourth embodiment

[0073] Add film-grade PET pure resin (intrinsic viscosity 0.75dl / g) into a drying tank, dry at 165℃, dry for 2h, then add the dried resin into the melt extrusion equipment, extrusion temperature 285℃, single screw extruder, screw diameter 35mm, screw length-diameter ratio 48:1. After the melt flows out of the die, it is stretched once, the cooling roller speed is 2.4m / min, and the stretching multiple is controlled at about 1.45 times; after the first stretching, it is cooled by the cooling roller, and then preheated twice, the preheating roller temperature is 88℃, the second stretching multiple is controlled at about 3.2 times, the stretching roller speed is about 7.7m / min, and then cooled twice; the film strip after the second stretching is preheated for the third time, the oven temperature is 148℃, the third stretching multiple is controlled at 2.5 times, and the stretching roller speed is about 19.5m / min; finally, the unidirectional film strip after the third stretching is cooled and rolled up.

[0074] Fifth embodiment

[0075] Bottle-grade PET resin (isophthalic acid modified, intrinsic viscosity 0.8dl / g) was added to a drying tank, the drying temperature was 165℃, and the drying was carried out for 2h. The dried resin was then added to the melt extrusion equipment, the extrusion temperature was 280℃, the single screw extruder, the screw diameter was 35mm, and the screw aspect ratio was 48:1. After the melt flows out of the die head, it was subjected to a heat stretching, the cooling roller speed was 2.7m / min, and the stretching multiple was controlled at about 1.55 times; after the first stretching, it was cooled by the cooling roller, and then preheated for the second time, the preheating roller temperature was 83℃, the second stretching multiple was controlled at about 3.3 times, the stretching roller speed was about 9m / min, and then cooled for the second time; the film strip after the second stretching was preheated for the third time, the oven temperature was 140℃, the third stretching multiple was controlled at 2.7 times, and the stretching nip roller speed was about 25m / min; finally, the unidirectional film strip after the third stretching was cooled and rolled up.

[0076] Sixth embodiment

[0077] Add PETG resin (intrinsic viscosity 0.85dl / g) into a drying tank, dry at 150℃, dry for 2h, then add the dried resin into the melt extrusion equipment, extrusion temperature 280℃, single screw extruder, screw diameter 35mm, screw aspect ratio 48:1. After the melt flows out of the die, it is stretched once, the cooling roller speed is 2m / min, and the stretching multiple is controlled at about 1.25 times; after the first stretching, it is cooled by the cooling roller, and then preheated twice, the preheating roller temperature is 70℃, the second stretching multiple is controlled at about 2.7 times, the stretching roller speed is about 5.5m / min, and then cooled twice; the film strip after the second stretching is preheated for the third time, the oven temperature is 140℃, the third stretching multiple is controlled at 2.7 times, and the stretching roller speed is about 15m / min; finally, the unidirectional film strip after the third stretching is cooled and rolled.

[0078] Seventh embodiment

[0079] PCTG resin (intrinsic viscosity 0.7dl / g) was added to the drying tank, the drying temperature was 170℃, and the drying was carried out for 2h. The dried resin was then added to the melt extrusion equipment, the extrusion temperature was 280℃, the single screw extruder, the screw diameter was 35mm, and the screw aspect ratio was 48:1. After the melt flows out of the die, it was subjected to a heat stretching, the cooling roller speed was 2m / min, and the stretching multiple was controlled at about 1.25 times; after the first stretching, it was cooled by the cooling roller, and then preheated for the second time, the preheating roller temperature was 70℃, the second stretching multiple was controlled at about 2.7 times, the stretching roller speed was about 5.5m / min, and then cooled for the second time; the film strip after the second stretching was preheated for the third time, the oven temperature was 140℃, the third stretching multiple was controlled at 2.7 times, and the stretching roller speed was about 15m / min; finally, the unidirectional film strip after the third stretching was cooled and rolled up.

[0080] Eighth embodiment

[0081] Add film-grade PET pure resin (intrinsic viscosity 0.7dl / g) into a drying tank, dry at 160℃, dry for 2h, then add the dried resin into the melt extrusion equipment, extrusion temperature 280℃, single screw extruder, screw diameter 65mm, screw length-diameter ratio 40:1. After the melt flows out of the die, it is stretched once, the cooling roller speed is 2.9m / min, and the stretching multiple is controlled at about 1.75 times; after the first stretching, it is cooled by the cooling roller, and then preheated twice, the preheating roller temperature is 85℃, the second stretching multiple is controlled at about 3 times, the stretching roller speed is about 8.5m / min, and then cooled twice; the film strip after the second stretching is preheated for the third time, the oven temperature is 160℃, the third stretching multiple is controlled at 2.8 times, and the stretching roller speed is about 24m / min; finally, the unidirectional film strip after the third stretching is cooled and rolled up.

[0082] The performance indicators of the uniaxially stretched PET film tapes prepared in Examples 4 to 8 are shown in the following table:

[0083]

[0084]

[0085] From the data shown in the above table, it can be concluded that the uniaxially stretched polyester film tape prepared by the present invention has relatively simple processing equipment, high mechanical strength, small longitudinal shrinkage, good insulation performance, and thermal conductivity or heat-dissipating performance. At the same time, the uniaxially stretched film tape combines the advantages of film and fiber, has good thickness uniformity, and can be used as a winding tape after slitting, which is similar to the use of a braided tape, and has very high processing formability and application prospects.

[0086] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a uniaxially stretched polyester film tape, It is characterized in that The following steps are involved: S1. Add pure resin into a drying tank at a drying temperature of 150-170°C for 2 hours; S2. Put the dried resin into the melt extrusion equipment, the extrusion temperature is 280-290℃, the single screw extruder, the screw diameter is 35-65mm, the screw length-diameter ratio is 40:1-48:1, and the effective width of the die head is 400mm; S3. After the sheet is extruded, before the melt solidifies on the cooling roller, the molten sheet is subjected to a heat stretching. The stretching multiple is adjusted by the cooling roller speed. The stretching multiple is controlled at 1.3-1.6 times. The cooling roller temperature is about 15°C. S4. The PET film strip after primary stretching is heated by a preheating roller, the temperature of the preheating roller is 70-90°C, and is heated by far infrared in the secondary stretching zone. The secondary stretching multiple is adjusted by the speed of the secondary stretching roller, and the secondary stretching multiple is controlled at 3.2-4.3 times. After stretching, the film strip is appropriately cooled; S5. After secondary stretching, the film strip enters the tertiary preheating oven, the oven temperature is 140-170℃, and the secondary stretching multiple is adjusted by the secondary stretching roller speed. Because the molecular chain has been clearly oriented during the secondary stretching, the crystallinity becomes higher, so the tertiary stretching temperature is higher, and the stretching rollers are sandwiched by two rollers, both of which are active rollers to increase the stretching force. The stretching multiple is controlled at 2.5-3.5 times; S6. After three stretching steps, the film strip is cooled and then rolled up.

2. The method for preparing a uniaxially stretched polyester film tape according to claim 1, It is characterized in that The PET resin may be a homopolymer PET resin, or a copolymer PET resin modified with isophthalic acid, or a PETG or PCTG resin may be used.

3. The method for preparing a uniaxially stretched polyester film tape according to claim 1, It is characterized in that The intrinsic viscosity of the PET resin is 0.67-0.85 dl / g, and more preferably the intrinsic viscosity is 0.7-0.78 dl / g.

4. The method for preparing a uniaxially stretched polyester film tape according to claim 1, It is characterized in that The screw diameter of the single-screw extruder is 35-65 mm, and the screw length-to-diameter ratio is 40:1-48:

1.

5. The method for preparing a uniaxially stretched polyester film tape according to claim 1, It is characterized in that The winding speed of the uniaxially stretched film tape is 15-25 m / min, and the thickness of the uniaxially stretched film tape is 0.02-0.06 mm.

6. The method for preparing a uniaxially stretched polyester film tape according to claim 1, It is characterized in that A cooling roller is used in the S3 step, and the cooling roller comprises a roller body, a plurality of cooling tubes are fixedly installed inside the roller body, fixing rings are fixedly installed at both ends of the roller body, one end of the outer side surfaces of the two fixing rings is provided with a groove, a bearing is fixedly installed on the inner side surface of the groove, a rotating ring is fixedly installed on the outer side surface of the bearing, a threaded ring is fixedly installed on the inner side surface of the rotating ring, a diverter frame is threadedly connected to the inner side surface of the threaded ring, a support shaft is fixedly installed on one side of the diverter frame, and a water pipe is rotatably connected to the inside of one end of the support shaft.

7. The method for preparing a uniaxially stretched polyester film tape according to claim 6, It is characterized in that A plurality of through holes are opened on the other side of the diverter frame, and a plurality of clamping rings are fixedly installed on the other side of the diverter frame, and the plurality of clamping rings are respectively arranged on the outer side surfaces of the plurality of through holes, and a fixing rod is arranged on the inner side surfaces of the plurality of through holes, and a threaded sleeve is threadedly connected to one end of the outer side surface of the fixing rod, and the threaded sleeve is fixedly installed inside the diverter frame, and a fixing seat is fixedly installed on the other end of the fixing rod, and a connecting rod is fixedly installed on the outer side surface of the fixing seat, and a scraping ring is fixedly installed on the outer side surface of the connecting rod, and the outer side surface of the scraping ring is fitted to the inner side surface of the cooling pipe.

8. The method for preparing a uniaxially stretched polyester film tape according to claim 7, It is characterized in that Sealing rings are fixedly mounted on both ends of the cooling pipe, and both ends of the cooling pipe are clamped with the inner side surfaces of the clamping rings.

9. The method for preparing a uniaxially stretched polyester film tape according to claim 8, It is characterized in that Both ends of one end of the rotating circle are fixedly installed with side plates, the internal threads of the side plates are connected with threaded rods, one end of the threaded rod is fixedly installed with a rotating plate, and the other end of the threaded rod is rotatably connected with a clamping plate.

10. The method for preparing a uniaxially stretched polyester film tape according to claim 9, It is characterized in that The clamping plate is attached to the side surface of the diverter frame.

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