CN114103194A - Preparation method of polytetrafluoroethylene insulating film - Google Patents
Preparation method of polytetrafluoroethylene insulating film Download PDFInfo
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- CN114103194A CN114103194A CN202111446232.6A CN202111446232A CN114103194A CN 114103194 A CN114103194 A CN 114103194A CN 202111446232 A CN202111446232 A CN 202111446232A CN 114103194 A CN114103194 A CN 114103194A
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- polytetrafluoroethylene
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D7/00—Producing flat articles, e.g. films or sheets
- B29D7/01—Films or sheets
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
- B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
- B29C43/10—Isostatic pressing, i.e. using non-rigid pressure-exerting members against rigid parts or dies
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
- B29C43/32—Component parts, details or accessories; Auxiliary operations
- B29C43/58—Measuring, controlling or regulating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C67/00—Shaping techniques not covered by groups B29C39/00 - B29C65/00, B29C70/00 or B29C73/00
- B29C67/02—Moulding by agglomerating
- B29C67/04—Sintering
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
- B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
- B29C43/10—Isostatic pressing, i.e. using non-rigid pressure-exerting members against rigid parts or dies
- B29C2043/106—Isostatic pressing, i.e. using non-rigid pressure-exerting members against rigid parts or dies using powder material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
- B29C43/32—Component parts, details or accessories; Auxiliary operations
- B29C43/58—Measuring, controlling or regulating
- B29C2043/5808—Measuring, controlling or regulating pressure or compressing force
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2027/00—Use of polyvinylhalogenides or derivatives thereof as moulding material
- B29K2027/12—Use of polyvinylhalogenides or derivatives thereof as moulding material containing fluorine
- B29K2027/18—PTFE, i.e. polytetrafluorethene, e.g. ePTFE, i.e. expanded polytetrafluorethene
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
- B29K2105/0005—Condition, form or state of moulded material or of the material to be shaped containing compounding ingredients
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2507/00—Use of elements other than metals as filler
- B29K2507/04—Carbon
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
Abstract
The invention relates to a preparation method of a polytetrafluoroethylene insulating film. The method comprises the following steps: s1: sieving raw materials: the preparation method of the polytetrafluoroethylene insulation film comprises the steps of preparing polytetrafluoroethylene powder raw materials and electrodeless fillers, uniformly stirring the polytetrafluoroethylene powder and the inorganic fillers at a high speed in a high-speed mixer to obtain a mixture, carrying out vertical isobaric pressing on the mixture by adopting a step-by-step pressurizing and slow pressure relief mode, wherein the pressing pressure is 515MPa, the pressed blank is placed at 120 ℃ for more than 24 hours, and the blank is pressed by adopting a step-by-step pressurizing and slow pressure relief mode, so that the pressing pressure can be increased to 1015MPa without causing the blank to crack, thereby being beneficial to discharging air in the blank.
Description
Technical Field
The invention relates to the field of fluoroplastic processing and manufacturing, in particular to a preparation method of a polytetrafluoroethylene insulating film.
Background
The oriented polytetrafluoroethylene film is produced with polytetrafluoroethylene resin and through die pressing, sintering, cooling to form blank, turning, rolling and orienting. The polytetrafluoroethylene film has high strength, good insulation and non-stick property. Among fluoroplastics, Polytetrafluoroethylene (PTFE) is the most consumed and widely used, and has outstanding non-stick property and low friction coefficient due to an inert fluorine-containing shell outside a PTFE molecule. PTFE has excellent high and low temperature resistance, chemical stability, good electrical insulation performance, non-adhesion, weather resistance, flame retardance and good self-lubrication, and is known as king plastic. At present, when a polytetrafluoroethylene oriented film is prepared in the market, blanks are easy to crack in the blank die-casting process, and the quality of finished products is influenced, so that a preparation method of a polytetrafluoroethylene insulating film is provided.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a preparation method of a polytetrafluoroethylene insulating film, which solves the problems.
In order to achieve the above purpose, the invention provides the following technical scheme: a preparation method of a polytetrafluoroethylene insulating film comprises the following steps:
s1: sieving raw materials: firstly, preparing polytetrafluoroethylene powder raw materials and inorganic fillers, wherein the polytetrafluoroethylene powder raw materials are easy to agglomerate and agglomerate, so that the polytetrafluoroethylene powder raw materials are broken up by a pounding machine, then are vibrated and sieved by a 20-mesh screen, the polytetrafluoroethylene powder raw materials with large particles are removed, the polytetrafluoroethylene powder raw materials with the particle size of less than 45 mu m are left for use, and then the polytetrafluoroethylene powder and the inorganic fillers are uniformly stirred at high speed in a high-speed mixer to obtain a mixture;
the inorganic filler is graphite, the inorganic filler needs to be dried in an infrared drying or air drying mode, after the drying is finished and the inorganic filler is cooled to room temperature, the inorganic filler is modified by adopting a silane coupling agent, and the modified filler is obtained after drying and crushing;
respectively sieving the modified filler and the polytetrafluoroethylene resin by a stainless steel sieve with more than 60 meshes, uniformly mixing by a high-speed stirrer, and sieving again to obtain a high-heat-conductivity polytetrafluoroethylene mixture;
the weight percentage of the polytetrafluoroethylene powder and the inorganic filler is 1: 2.4-3;
s2: blank preparation: under the dust-free environment, pouring the mixture into a die, carrying out die-casting molding under high pressure to obtain a blank, pouring the mixture into a cylindrical barrel die under the dust-free environment, and carrying out die-casting molding under a 100-ton four-column hydraulic press, wherein a die-casting period is preferably 15 min;
the mixture is placed in a cylindrical die with a core rod, the mixture is pressed in an upper and lower isobaric manner by adopting a gradual pressurization and slow pressure relief manner, the pressing pressure is 515MPa, the pressed blank is placed at 120 ℃ for more than 24h, and the blank is pressed by adopting a gradual pressurization and slow pressure relief manner, so that the pressing pressure can be increased to 1015MPa without causing the blank to crack, the air in the blank is favorably discharged, the prepared composite membrane material has low porosity and high density, GF is tightly combined with PTFE, the interface interaction is strong, and GF cannot be debonded from a PTFE matrix to cause more interface defects.
S3: sintering and forming: and (3) placing the prepared blank in a sintering furnace, and adopting a blast rotary sintering mode. The sintering furnace temperature control system is controlled by a computer program, heating is carried out by adopting heating modes of temperature rise, heat preservation, temperature re-rise and heat re-preservation in different temperature areas, the room temperature is raised to 195 and 195 for heat preservation, the temperature is raised from 195 to 270 and 270 for heat preservation, the temperature is raised from 270 to 315 and 315 for heat preservation, the temperature is raised from 315 to 380, the sintering temperature is 380, the temperature is lowered to 270 and 270 for heat preservation, the temperature is lowered from 270 to 195, after the temperature is kept for a period of time at 195, the cylindrical blank is cooled to form a cylindrical blank, the cylindrical blank is convenient for subsequent processing to be a required film product, and the cylindrical blank is taken out after being stopped;
s4: turning to form a film: preheating the sintered and cooled blank to 100, hoisting the blank to a lathe for clamping and fixing, turning at the speed of 1525 r/min to form an unidirectional polytetrafluoroethylene film, winding the film to form an unidirectional polytetrafluoroethylene film roll so as to convey the film to subsequent production equipment for cutting, wherein the thickness of the turned film is controlled to be 2.7 times that of the oriented film;
s5: calendering and orientation: the crystal orientation degree of the turning film in the film is improved through calendering and orientation, the size of a roller used for the calendering and orientation is 210310mm, the precision of the roller requires 14 mirror surfaces, the surface is plated with chrome, the hardness is 60HRC, the heating mode adopts internal and external heating, and electronic numerical control is carried out, so that the calendering and orientation film is obtained;
the wound non-directional polytetrafluoroethylene film roll is installed on a discharging mechanism, or the non-directional polytetrafluoroethylene film turned by a lathe is directly conveyed to a calender through a feeding mechanism, after the non-directional polytetrafluoroethylene film roll passes through an upper roller and a lower roller of the calender, the upper roller and the lower roller of the calender are preheated to set temperatures, and the temperature of the upper roller is higher than that of the lower roller in the calendering process, so that the set temperature of the upper roller is lower than that of the lower roller, specifically, the set temperature of the lower roller is 62, and the set temperature of the upper roller is 58; then adjusting the gap between the upper roller and the lower roller, and starting a calender to roll the non-oriented polytetrafluoroethylene film into an oriented polytetrafluoroethylene film; the speed of the calender for calendering the non-directional polytetrafluoroethylene film is controlled to be 58m/min so as to be connected with the running speed of the turning procedure of the previous lathe and adapt to the running speed of the subsequent production procedure.
S6: trimming and rolling: rewinding and trimming the calendered oriented film again, removing burrs and rolling a finished product;
and cutting the rolled oriented polytetrafluoroethylene film to remove waste edges according to the specification of the conductive bar, cutting the oriented polytetrafluoroethylene film into an oriented polytetrafluoroethylene film strip material, rolling the polytetrafluoroethylene film strip material by using a rolling roller, and determining the cutting distance by one hundred meters during rolling.
Preferably, the polytetrafluoroethylene powder and the inorganic filler are mixed according to the weight percentage of 1: 2.7.
compared with the prior art, the invention provides a preparation method of a polytetrafluoroethylene insulating film, which has the following beneficial effects:
1. according to the preparation method of the polytetrafluoroethylene insulating film, the mixture is subjected to up-down isobaric pressing by adopting a step-by-step pressurizing and slow pressure relief mode, the pressing pressure is 515MPa, the pressed blank is placed at 120 ℃ for more than 24h, and the blank is pressed by adopting a step-by-step pressurizing and slow pressure relief mode, so that the pressing pressure can be increased to 1015MPa without causing the blank to crack, and the air in the blank is favorably discharged.
2. The preparation method of the polytetrafluoroethylene insulating film adopts heating modes of temperature rise, heat preservation, temperature re-rise and heat re-preservation in different temperature areas, the room temperature is raised to 195 and 195 for heat preservation, then the room temperature is raised to 270, 270 for heat preservation, 270 is raised to 315, 315 for heat preservation, 315 is raised to 380, the sintering temperature is 380, then the temperature is lowered to 270, 270 for heat preservation, then the temperature is lowered to 195 from 270, after the temperature is kept for a period of time at 195, the cylindrical blank is cooled to form a cylindrical blank, and the cylindrical blank is convenient for subsequent processing to form a required film product.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The first embodiment is as follows: a preparation method of a polytetrafluoroethylene insulating film comprises the following steps:
s1: sieving raw materials: firstly, preparing polytetrafluoroethylene powder raw materials and inorganic fillers, wherein the polytetrafluoroethylene powder raw materials are easy to agglomerate and agglomerate, so that the polytetrafluoroethylene powder raw materials are broken up by a pounding machine, then are vibrated and sieved by a 20-mesh screen, the polytetrafluoroethylene powder raw materials with large particles are removed, the polytetrafluoroethylene powder raw materials with the particle size of less than 45 mu m are left for use, and then the polytetrafluoroethylene powder and the inorganic fillers are uniformly stirred at high speed in a high-speed mixer to obtain a mixture;
the inorganic filler is graphite, the inorganic filler needs to be dried in an infrared drying or air drying mode, after the drying is finished and the inorganic filler is cooled to room temperature, the inorganic filler is modified by adopting a silane coupling agent, and the modified filler is obtained after drying and crushing;
respectively sieving the modified filler and the polytetrafluoroethylene resin by a stainless steel sieve with more than 60 meshes, uniformly mixing by a high-speed stirrer, and sieving again to obtain a high-heat-conductivity polytetrafluoroethylene mixture;
the weight percentage of the polytetrafluoroethylene powder and the inorganic filler is 1: 2.4;
s2: blank preparation: under the dust-free environment, pouring the mixture into a die, carrying out die-casting molding under high pressure to obtain a blank, pouring the mixture into a cylindrical barrel die under the dust-free environment, and carrying out die-casting molding under a 100-ton four-column hydraulic press, wherein a die-casting period is preferably 15 min;
the mixture is placed in a cylindrical die with a core rod, the mixture is pressed in an upper and lower isobaric manner by adopting a gradual pressurization and slow pressure relief manner, the pressing pressure is 515MPa, the pressed blank is placed at 120 ℃ for more than 24h, and the blank is pressed by adopting a gradual pressurization and slow pressure relief manner, so that the pressing pressure can be increased to 1015MPa without causing the blank to crack, the air in the blank is favorably discharged, the prepared composite membrane material has low porosity and high density, GF is tightly combined with PTFE, the interface interaction is strong, and GF cannot be debonded from a PTFE matrix to cause more interface defects.
S3: sintering and forming: and (3) placing the prepared blank in a sintering furnace, and adopting a blast rotary sintering mode. The sintering furnace temperature control system is controlled by a computer program, heating is carried out by adopting heating modes of temperature rise, heat preservation, temperature re-rise and heat re-preservation in different temperature areas, the room temperature is raised to 195 and 195 for heat preservation, the temperature is raised from 195 to 270 and 270 for heat preservation, the temperature is raised from 270 to 315 and 315 for heat preservation, the temperature is raised from 315 to 380, the sintering temperature is 380, the temperature is lowered to 270 and 270 for heat preservation, the temperature is lowered from 270 to 195, after the temperature is kept for a period of time at 195, the cylindrical blank is cooled to form a cylindrical blank, the cylindrical blank is convenient for subsequent processing to be a required film product, and the cylindrical blank is taken out after being stopped;
s4: turning to form a film: preheating the sintered and cooled blank to 100, hoisting the blank to a lathe for clamping and fixing, turning at the speed of 1525 r/min to form an unidirectional polytetrafluoroethylene film, winding the film to form an unidirectional polytetrafluoroethylene film roll so as to convey the film to subsequent production equipment for cutting, wherein the thickness of the turned film is controlled to be 2.7 times that of the oriented film;
s5: calendering and orientation: the crystal orientation degree of the turning film in the film is improved through calendering and orientation, the size of a roller used for the calendering and orientation is 210310mm, the precision of the roller requires 14 mirror surfaces, the surface is plated with chrome, the hardness is 60HRC, the heating mode adopts internal and external heating, and electronic numerical control is carried out, so that the calendering and orientation film is obtained;
the wound non-directional polytetrafluoroethylene film roll is installed on a discharging mechanism, or the non-directional polytetrafluoroethylene film turned by a lathe is directly conveyed to a calender through a feeding mechanism, after the non-directional polytetrafluoroethylene film roll passes through an upper roller and a lower roller of the calender, the upper roller and the lower roller of the calender are preheated to set temperatures, and the temperature of the upper roller is higher than that of the lower roller in the calendering process, so that the set temperature of the upper roller is lower than that of the lower roller, specifically, the set temperature of the lower roller is 62, and the set temperature of the upper roller is 58; then adjusting the gap between the upper roller and the lower roller, and starting a calender to roll the non-oriented polytetrafluoroethylene film into an oriented polytetrafluoroethylene film; the speed of the calender for calendering the non-directional polytetrafluoroethylene film is controlled to be 58m/min so as to be connected with the running speed of the turning procedure of the previous lathe and adapt to the running speed of the subsequent production procedure.
S6: trimming and rolling: rewinding and trimming the calendered oriented film again, removing burrs and rolling a finished product;
and cutting the rolled oriented polytetrafluoroethylene film to remove waste edges according to the specification of the conductive bar, cutting the oriented polytetrafluoroethylene film into an oriented polytetrafluoroethylene film strip material, rolling the polytetrafluoroethylene film strip material by using a rolling roller, and determining the cutting distance by one hundred meters during rolling.
Example two: a preparation method of a polytetrafluoroethylene insulating film comprises the following steps:
s1: sieving raw materials: firstly, preparing polytetrafluoroethylene powder raw materials and inorganic fillers, wherein the polytetrafluoroethylene powder raw materials are easy to agglomerate and agglomerate, so that the polytetrafluoroethylene powder raw materials are broken up by a pounding machine, then are vibrated and sieved by a 20-mesh screen, the polytetrafluoroethylene powder raw materials with large particles are removed, the polytetrafluoroethylene powder raw materials with the particle size of less than 45 mu m are left for use, and then the polytetrafluoroethylene powder and the inorganic fillers are uniformly stirred at high speed in a high-speed mixer to obtain a mixture;
the inorganic filler is graphite, the inorganic filler needs to be dried in an infrared drying or air drying mode, after the drying is finished and the inorganic filler is cooled to room temperature, the inorganic filler is modified by adopting a silane coupling agent, and the modified filler is obtained after drying and crushing;
respectively sieving the modified filler and the polytetrafluoroethylene resin by a stainless steel sieve with more than 60 meshes, uniformly mixing by a high-speed stirrer, and sieving again to obtain a high-heat-conductivity polytetrafluoroethylene mixture;
the weight percentage of the polytetrafluoroethylene powder and the inorganic filler is 1: 2.7;
s2: blank preparation: under the dust-free environment, pouring the mixture into a die, carrying out die-casting molding under high pressure to obtain a blank, pouring the mixture into a cylindrical barrel die under the dust-free environment, and carrying out die-casting molding under a 100-ton four-column hydraulic press, wherein a die-casting period is preferably 15 min;
the mixture is placed in a cylindrical die with a core rod, the mixture is pressed in an upper and lower isobaric manner by adopting a gradual pressurization and slow pressure relief manner, the pressing pressure is 515MPa, the pressed blank is placed at 120 ℃ for more than 24h, and the blank is pressed by adopting a gradual pressurization and slow pressure relief manner, so that the pressing pressure can be increased to 1015MPa without causing the blank to crack, the air in the blank is favorably discharged, the prepared composite membrane material has low porosity and high density, GF is tightly combined with PTFE, the interface interaction is strong, and GF cannot be debonded from a PTFE matrix to cause more interface defects.
S3: sintering and forming: and (3) placing the prepared blank in a sintering furnace, and adopting a blast rotary sintering mode. The sintering furnace temperature control system is controlled by a computer program, heating is carried out by adopting heating modes of temperature rise, heat preservation, temperature re-rise and heat re-preservation in different temperature areas, the room temperature is raised to 195 and 195 for heat preservation, the temperature is raised from 195 to 270 and 270 for heat preservation, the temperature is raised from 270 to 315 and 315 for heat preservation, the temperature is raised from 315 to 380, the sintering temperature is 380, the temperature is lowered to 270 and 270 for heat preservation, the temperature is lowered from 270 to 195, after the temperature is kept for a period of time at 195, the cylindrical blank is cooled to form a cylindrical blank, the cylindrical blank is convenient for subsequent processing to be a required film product, and the cylindrical blank is taken out after being stopped;
s4: turning to form a film: preheating the sintered and cooled blank to 100, hoisting the blank to a lathe for clamping and fixing, turning at the speed of 1525 r/min to form an unidirectional polytetrafluoroethylene film, winding the film to form an unidirectional polytetrafluoroethylene film roll so as to convey the film to subsequent production equipment for cutting, wherein the thickness of the turned film is controlled to be 2.7 times that of the oriented film;
s5: calendering and orientation: the crystal orientation degree of the turning film in the film is improved through calendering and orientation, the size of a roller used for the calendering and orientation is 210310mm, the precision of the roller requires 14 mirror surfaces, the surface is plated with chrome, the hardness is 60HRC, the heating mode adopts internal and external heating, and electronic numerical control is carried out, so that the calendering and orientation film is obtained;
the wound non-directional polytetrafluoroethylene film roll is installed on a discharging mechanism, or the non-directional polytetrafluoroethylene film turned by a lathe is directly conveyed to a calender through a feeding mechanism, after the non-directional polytetrafluoroethylene film roll passes through an upper roller and a lower roller of the calender, the upper roller and the lower roller of the calender are preheated to set temperatures, and the temperature of the upper roller is higher than that of the lower roller in the calendering process, so that the set temperature of the upper roller is lower than that of the lower roller, specifically, the set temperature of the lower roller is 62, and the set temperature of the upper roller is 58; then adjusting the gap between the upper roller and the lower roller, and starting a calender to roll the non-oriented polytetrafluoroethylene film into an oriented polytetrafluoroethylene film; the speed of the calender for calendering the non-directional polytetrafluoroethylene film is controlled to be 58m/min so as to be connected with the running speed of the turning procedure of the previous lathe and adapt to the running speed of the subsequent production procedure.
S6: trimming and rolling: rewinding and trimming the calendered oriented film again, removing burrs and rolling a finished product;
and cutting the rolled oriented polytetrafluoroethylene film to remove waste edges according to the specification of the conductive bar, cutting the oriented polytetrafluoroethylene film into an oriented polytetrafluoroethylene film strip material, rolling the polytetrafluoroethylene film strip material by using a rolling roller, and determining the cutting distance by one hundred meters during rolling.
Example three: a preparation method of a polytetrafluoroethylene insulating film comprises the following steps:
s1: sieving raw materials: firstly, preparing polytetrafluoroethylene powder raw materials and inorganic fillers, wherein the polytetrafluoroethylene powder raw materials are easy to agglomerate and agglomerate, so that the polytetrafluoroethylene powder raw materials are broken up by a pounding machine, then are vibrated and sieved by a 20-mesh screen, the polytetrafluoroethylene powder raw materials with large particles are removed, the polytetrafluoroethylene powder raw materials with the particle size of less than 45 mu m are left for use, and then the polytetrafluoroethylene powder and the inorganic fillers are uniformly stirred at high speed in a high-speed mixer to obtain a mixture;
the inorganic filler is graphite, the inorganic filler needs to be dried in an infrared drying or air drying mode, after the drying is finished and the inorganic filler is cooled to room temperature, the inorganic filler is modified by adopting a silane coupling agent, and the modified filler is obtained after drying and crushing;
respectively sieving the modified filler and the polytetrafluoroethylene resin by a stainless steel sieve with more than 60 meshes, uniformly mixing by a high-speed stirrer, and sieving again to obtain a high-heat-conductivity polytetrafluoroethylene mixture;
the weight percentage of the polytetrafluoroethylene powder and the inorganic filler is 1: 2.9;
s2: blank preparation: under the dust-free environment, pouring the mixture into a die, carrying out die-casting molding under high pressure to obtain a blank, pouring the mixture into a cylindrical barrel die under the dust-free environment, and carrying out die-casting molding under a 100-ton four-column hydraulic press, wherein a die-casting period is preferably 15 min;
the mixture is placed in a cylindrical die with a core rod, the mixture is pressed in an upper and lower isobaric manner by adopting a gradual pressurization and slow pressure relief manner, the pressing pressure is 515MPa, the pressed blank is placed at 120 ℃ for more than 24h, and the blank is pressed by adopting a gradual pressurization and slow pressure relief manner, so that the pressing pressure can be increased to 1015MPa without causing the blank to crack, the air in the blank is favorably discharged, the prepared composite membrane material has low porosity and high density, GF is tightly combined with PTFE, the interface interaction is strong, and GF cannot be debonded from a PTFE matrix to cause more interface defects.
S3: sintering and forming: and (3) placing the prepared blank in a sintering furnace, and adopting a blast rotary sintering mode. The sintering furnace temperature control system is controlled by a computer program, heating is carried out by adopting heating modes of temperature rise, heat preservation, temperature re-rise and heat re-preservation in different temperature areas, the room temperature is raised to 195 and 195 for heat preservation, the temperature is raised from 195 to 270 and 270 for heat preservation, the temperature is raised from 270 to 315 and 315 for heat preservation, the temperature is raised from 315 to 380, the sintering temperature is 380, the temperature is lowered to 270 and 270 for heat preservation, the temperature is lowered from 270 to 195, after the temperature is kept for a period of time at 195, the cylindrical blank is cooled to form a cylindrical blank, the cylindrical blank is convenient for subsequent processing to be a required film product, and the cylindrical blank is taken out after being stopped;
s4: turning to form a film: preheating the sintered and cooled blank to 100, hoisting the blank to a lathe for clamping and fixing, turning at the speed of 1525 r/min to form an unidirectional polytetrafluoroethylene film, winding the film to form an unidirectional polytetrafluoroethylene film roll so as to convey the film to subsequent production equipment for cutting, wherein the thickness of the turned film is controlled to be 2.7 times that of the oriented film;
s5: calendering and orientation: the crystal orientation degree of the turning film in the film is improved through calendering and orientation, the size of a roller used for the calendering and orientation is 210310mm, the precision of the roller requires 14 mirror surfaces, the surface is plated with chrome, the hardness is 60HRC, the heating mode adopts internal and external heating, and electronic numerical control is carried out, so that the calendering and orientation film is obtained;
the wound non-directional polytetrafluoroethylene film roll is installed on a discharging mechanism, or the non-directional polytetrafluoroethylene film turned by a lathe is directly conveyed to a calender through a feeding mechanism, after the non-directional polytetrafluoroethylene film roll passes through an upper roller and a lower roller of the calender, the upper roller and the lower roller of the calender are preheated to set temperatures, and the temperature of the upper roller is higher than that of the lower roller in the calendering process, so that the set temperature of the upper roller is lower than that of the lower roller, specifically, the set temperature of the lower roller is 62, and the set temperature of the upper roller is 58; then adjusting the gap between the upper roller and the lower roller, and starting a calender to roll the non-oriented polytetrafluoroethylene film into an oriented polytetrafluoroethylene film; the speed of the calender for calendering the non-directional polytetrafluoroethylene film is controlled to be 58m/min so as to be connected with the running speed of the turning procedure of the previous lathe and adapt to the running speed of the subsequent production procedure.
S6: trimming and rolling: rewinding and trimming the calendered oriented film again, removing burrs and rolling a finished product;
and cutting the rolled oriented polytetrafluoroethylene film to remove waste edges according to the specification of the conductive bar, cutting the oriented polytetrafluoroethylene film into an oriented polytetrafluoroethylene film strip material, rolling the polytetrafluoroethylene film strip material by using a rolling roller, and determining the cutting distance by one hundred meters during rolling.
The proportion of the cracking rate of the preparation process and the existing preparation process in the die-casting forming process is as follows:
| contrast item | Existing solutions | This scheme |
| Cracking Rate (%) | 10.5% | 0.5% |
| Scrap rate (percentage) due to die casting | 15.5% | 1.5% |
The following are indexes of the polytetrafluoroethylene film prepared by the scheme
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (9)
1. A method for preparing a polytetrafluoroethylene insulating film, characterized by comprising the steps of:
s1: sieving raw materials: firstly, preparing polytetrafluoroethylene powder raw materials and inorganic fillers, wherein the polytetrafluoroethylene powder raw materials are easy to agglomerate and agglomerate, so that the polytetrafluoroethylene powder raw materials are broken up by a pounding machine, then are vibrated and sieved by a 20-mesh screen, the polytetrafluoroethylene powder raw materials with large particles are removed, the polytetrafluoroethylene powder raw materials with the particle size of less than 45 mu m are left for use, and then the polytetrafluoroethylene powder and the inorganic fillers are uniformly stirred at high speed in a high-speed mixer to obtain a mixture;
s2: blank preparation: under the dust-free environment, pouring the mixture into a die, carrying out die-casting molding under high pressure to obtain a blank, pouring the mixture into a cylindrical barrel die under the dust-free environment, and carrying out die-casting molding under a 100-ton four-column hydraulic press, wherein a die-casting period is preferably 15 min;
s3: sintering and forming: placing the prepared blank in a sintering furnace, and calcining and forming;
s4: turning to form a film: preheating the sintered and cooled blank to 100, hoisting the blank to a lathe for clamping and fixing, turning at the speed of 1525 r/min to form an unidirectional polytetrafluoroethylene film, winding the film to form an unidirectional polytetrafluoroethylene film roll so as to convey the film to subsequent production equipment for cutting, wherein the thickness of the turned film is controlled to be 2.7 times that of the oriented film;
s5: calendering and orientation: the crystal orientation degree of the turning film in the film is improved through calendering and orientation, the size of a roller used for the calendering and orientation is 210310mm, the precision of the roller requires 14 mirror surfaces, the surface is plated with chrome, the hardness is 60HRC, the heating mode adopts internal and external heating, and electronic numerical control is carried out, so that the calendering and orientation film is obtained;
s6: trimming and rolling: rewinding and trimming the calendered oriented film again, removing burrs and rolling a finished product.
2. A method for producing a polytetrafluoroethylene insulating film according to claim 1, wherein: the inorganic filler is graphite, the inorganic filler needs to be dried in an infrared drying or air drying mode, after the drying is finished and the inorganic filler is cooled to room temperature, the inorganic filler is modified by adopting a silane coupling agent, and the modified filler is obtained after drying and crushing;
and respectively sieving the modified filler and the polytetrafluoroethylene resin by a stainless steel sieve with more than 60 meshes, uniformly mixing by a high-speed stirrer, and sieving again to obtain the polytetrafluoroethylene mixture with high heat conductivity.
3. A method for producing a polytetrafluoroethylene insulating film according to claim 1, wherein: the polytetrafluoroethylene powder and the inorganic filler are mixed according to the weight percentage of 1: 2.4-3.
4. A method for producing a polytetrafluoroethylene insulating film according to claim 1, wherein: the polytetrafluoroethylene powder and the inorganic filler are mixed according to the weight percentage of 1: 2.7.
5. a method for producing a polytetrafluoroethylene insulating film according to claim 1, wherein: and placing the mixture into a cylindrical die with a core rod, carrying out up-down isobaric pressing on the mixture by adopting a mode of gradually pressurizing and slowly releasing pressure, wherein the pressing pressure is 515MPa, placing the pressed blank at the temperature of 120 ℃ for more than 24h, and pressing the blank by adopting a mode of gradually pressurizing and slowly releasing pressure.
6. A method for producing a polytetrafluoroethylene insulating film according to claim 1, wherein: the sintering furnace temperature control system is controlled by a computer program, heating is carried out by adopting heating modes of temperature rise, heat preservation, temperature re-rise and heat re-preservation in different temperature areas, the room temperature is raised to 195 and 195 for heat preservation, the room temperature is raised to 270 and 270 for heat preservation, the temperature is raised to 315 and 315 for heat preservation, the temperature is raised to 380 by 315, the sintering temperature is 380, then the temperature is lowered to 270 and 270 for heat preservation, then the temperature is lowered to 195 by 270, and after the constant temperature of 195 is kept for a period of time, the cylindrical blank is formed after cooling.
7. A method for producing a polytetrafluoroethylene insulating film according to claim 1, wherein: the wound non-directional polytetrafluoroethylene film roll is installed on a discharging mechanism, or the non-directional polytetrafluoroethylene film turned by a lathe is directly conveyed to a calender through a feeding mechanism, after passing through an upper roller and a lower roller of the calender, the upper roller and the lower roller of the calender are preheated to a set temperature, then a gap between the upper roller and the lower roller is adjusted, and the calender is started to calender the non-directional polytetrafluoroethylene film into the directional polytetrafluoroethylene film; the speed of the calender for calendering the non-directional polytetrafluoroethylene film is controlled to be 58m/min so as to be connected with the running speed of the turning procedure of the previous lathe and adapt to the running speed of the subsequent production procedure.
8. A method for forming a polytetrafluoroethylene insulating film according to claim 7, wherein: the upper roll temperature is higher than the lower roll temperature during rolling, so that the upper roll set temperature is lower than the lower roll set temperature, specifically, the lower roll set temperature is 62 and the upper roll set temperature is 58.
9. A method for producing a polytetrafluoroethylene insulating film according to claim 1, wherein: and cutting the rolled oriented polytetrafluoroethylene film to remove waste edges according to the specification of the conductive bar, cutting the oriented polytetrafluoroethylene film into an oriented polytetrafluoroethylene film strip material, rolling the polytetrafluoroethylene film strip material by using a rolling roller, and determining the cutting distance by one hundred meters during rolling.
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| CN101491945A (en) * | 2009-02-19 | 2009-07-29 | 广州市东泓橡塑制品有限公司 | Preparation method of teflon oriented film of ultra-thin breadth |
| CN109181178A (en) * | 2018-08-27 | 2019-01-11 | 四川大学 | A kind of preparation method of high thermal conductivity PTFE composite membrane material |
| WO2020253332A1 (en) * | 2019-06-21 | 2020-12-24 | 日东电工（上海松江）有限公司 | Polytetrafluoroethylene thin film and manufacturing method therefor |
| CN113861863A (en) * | 2021-12-06 | 2021-12-31 | 中国电子科技集团公司第四十六研究所 | Flame-retardant low-dielectric-constant bonding sheet and preparation method thereof |
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| CN101491945A (en) * | 2009-02-19 | 2009-07-29 | 广州市东泓橡塑制品有限公司 | Preparation method of teflon oriented film of ultra-thin breadth |
| CN109181178A (en) * | 2018-08-27 | 2019-01-11 | 四川大学 | A kind of preparation method of high thermal conductivity PTFE composite membrane material |
| WO2020253332A1 (en) * | 2019-06-21 | 2020-12-24 | 日东电工（上海松江）有限公司 | Polytetrafluoroethylene thin film and manufacturing method therefor |
| CN113861863A (en) * | 2021-12-06 | 2021-12-31 | 中国电子科技集团公司第四十六研究所 | Flame-retardant low-dielectric-constant bonding sheet and preparation method thereof |
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