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CN-122008669-A - Polyester film with high CTI value and preparation method thereof

CN122008669ACN 122008669 ACN122008669 ACN 122008669ACN-122008669-A

Abstract

The invention relates to a polyester film with high CTI value and a preparation method thereof, belonging to the technical field of polyester, the polyester film provided by the invention is a three-layer structure film formed by a surface layer, a core layer and a surface layer, the raw materials involved in preparing the surface layer and the core layer comprise high CTI modified polyester chips, which are modified by adding modified silica during preparation. The preparation method of the modified silicon dioxide comprises the following steps of S1, namely, dopamine hydrochloride is polymerized to coat the silicon dioxide, S2, namely, allyl alcohol and 3-urea propyl trimethoxy silane are subjected to exchange reaction to synthesize an ureido electric leakage resistant tracking agent, S3, namely, synthesizing a polymerized ureido electric leakage resistant tracking agent under the action of an initiator, and S4, namely, surface modification of the polymerized ureido electric leakage resistant tracking agent. The polyester film provided by the invention has high CTI value and strong tracking resistance, can greatly reduce the probability of surface leakage and insulation failure, widens the application scene in household electrical appliance products, and improves the market competitiveness.

Inventors

  • Luo Dingbin
  • LI DEQING

Assignees

  • 宝智兴(广东)薄膜科技有限公司

Dates

Publication Date
20260512
Application Date
20260228

Claims (10)

  1. 1. A polyester film with a high CTI value is characterized in that the polyester film is a three-layer structure film formed by a surface layer, a core layer and a surface layer, wherein the surface layer is prepared from 70-100% of high CTI modified polyester chips and 0-30% of high-gloss polyester chips by weight percent, and the core layer is prepared from 10-50% of high-gloss polyester chips and 50-90% of high CTI modified polyester chips by weight percent.
  2. 2. A high CTI polyester film according to claim 1, wherein the thickness of the polyester film is 12 to 50. Mu.m.
  3. 3. The high CTI polyester film according to claim 1, wherein the preparation method of the high CTI modified polyester chip comprises the following steps: the method comprises the steps of carrying out esterification reaction on refined terephthalic acid, ethylene glycol and a catalyst in a reaction kettle, adding an auxiliary agent and modified silicon dioxide, carrying out reduced pressure polycondensation, discharging, cooling and granulating a casting belt, removing water, and tackifying by using a rotary drum type solid-phase tackifying device.
  4. 4. A high CTI polyester film as claimed in claim 3, wherein the weight ratio of the refined terephthalic acid to the ethylene glycol to the catalyst to the auxiliary agent to the modified silica is 50-60:22-27:0.01-0.014:0.005-0.01:0.8-1.1.
  5. 5. A polyester film with high CTI value as set forth in claim 3, wherein the preparation method of the modified silica comprises the following steps: Step S1, stirring and dispersing silicon dioxide and Tris-HCl buffer solution under ultrasound, adding dopamine hydrochloride, performing first temperature control stirring reaction, centrifuging, collecting precipitate, washing with deionized water, and drying to obtain coated silicon dioxide; Step S2, in nitrogen atmosphere, allyl alcohol, 3-urea propyl trimethoxy silane and toluene are stirred and mixed at a controlled temperature, butyl titanate is added, the mixture is subjected to a second temperature-controlled stirring reaction, distillation and a third temperature-controlled stirring reaction, and purification is carried out, so that the ureido electric leakage resistant tracking agent is obtained; Step 3, in nitrogen atmosphere, the ureido electric leakage resistant tracking agent, azodiisobutyronitrile and N, N-dimethylformamide are subjected to fourth temperature control stirring reaction, and are kept stand, a solid phase is filtered out, and the solid phase is washed by toluene and then dried, so that the polymeric ureido electric leakage resistant tracking agent is obtained; And S4, reacting the polymeric ureido electric leakage resistant tracking agent, the coated silicon dioxide and the dimethyl sulfoxide aqueous solution for the fifth time under the condition of temperature control and stirring in a nitrogen atmosphere, centrifuging, collecting the precipitate, washing with deionized water, and drying.
  6. 6. A high CTI polyester film as set forth in claim 5 wherein the weight ratio of silica, tris-HCl buffer and dopamine hydrochloride in step S1 is 2.6-3.8:192-215:4.5-5.2.
  7. 7. A high CTI polyester film as set forth in claim 5 wherein the weight ratio of said allyl alcohol to said toluene in step S2 is 10-17:220-238 and the molar ratio of said allyl alcohol to said 3-ureidopropyltrimethoxysilane is 1-2:1.
  8. 8. The high CTI polyester film of claim 5, wherein the weight ratio of the ureido tracking agent to the N, N-dimethylformamide in step S3 is 6-6.6:135-155, and the weight ratio of the ureido tracking agent to the azobisisobutyronitrile is 100-120:0.8.
  9. 9. The polyester film with high CTI value as claimed in claim 5, wherein the weight ratio of the polymeric urea-based tracking agent, the coated silica and the dimethyl sulfoxide aqueous solution in the step S4 is 0.4-0.9:1.5:150-170.
  10. 10. A process for the preparation of a polyester film having a high CTI value according to any one of claims 1 to 9, characterized in that the process comprises the steps of: step A1, drying the raw materials for preparing the core layer, and then carrying out melt extrusion by using a single screw extruder to obtain a core layer melt; step A2, drying the preparation raw materials of the surface layer, and then carrying out melt extrusion by using a double-screw extruder to obtain a surface layer melt; and step A3, conveying the core layer melt and the surface layer melt to a die head, converging and extruding, casting the core layer melt and the surface layer melt on a cooling roller, casting the cast sheet, biaxially stretching, shaping, traction, corona and winding.

Description

Polyester film with high CTI value and preparation method thereof Technical Field The invention belongs to the technical field of polyester, and particularly relates to a polyester film with a high CTI value and a preparation method thereof. Background In household electrical appliances, the insulating material is usually in a state of being charged, heated and acted under complex environments for a long time, and the surface of the insulating material is inevitably deposited with pollutants such as dust, greasy dirt, water vapor and the like. Under the action of an electric field, the conductive or semiconductive dirt easily forms a leakage channel on the surface of the insulating material, so that potential safety hazards such as surface creepage, breakdown short circuit, even fire and the like are induced. Therefore, the tracking resistance has become an important index for evaluating the safety of insulating materials for household appliances, wherein CTI value is used as a key characterization parameter for reflecting the tracking resistance of materials under severe conditions such as humidity, pollution and the like. Polyester films are widely applied to insulating layers, isolating sheets and the like in household appliances due to good mechanical strength, heat resistance, electrical insulation and processability, however, conventional polyester films still have certain defects in tracking resistance, CTI values of the conventional polyester films are generally low, and in an actual use environment, when dirt is attached to the surfaces of the polyester films and the polyester films are wetted, continuous tracking phenomena are easily formed between electrodes, so that the surfaces are carbonized and corroded, conductive traces are gradually formed, and the insulation reliability is remarkably reduced. For household appliances with higher working voltage or long-term continuous operation, the polyester film with lower CTI value is difficult to meet the design requirement of higher safety level, and the application of the polyester film in complex environment and high-safety requirement scenes is limited. Disclosure of Invention (One) solving the technical problems Aiming at the defects of the prior art, the invention provides a polyester film with a high CTI value and a preparation method thereof, and solves the problems mentioned in the background art. (II) technical scheme In order to achieve the above purpose, the present invention provides the following technical solutions: According to the first aspect, the polyester film with the high CTI value is a three-layer structure film formed by a surface layer, a core layer and a surface layer, the thickness of the surface layer is 10-20% of that of the polyester film, the thickness of the polyester film is 12-50 mu m, the preparation raw materials of the surface layer comprise 70-100% of high CTI modified polyester chips and 0-30% of high-gloss polyester chips by weight percentage, and the preparation raw materials of the core layer comprise 10-50% of high-gloss polyester chips and 50-90% of high CTI modified polyester chips by weight percentage. In a preferred embodiment of the invention, the preparation method of the high CTI modified polyester chip comprises the following steps: And (3) carrying out esterification reaction on the refined terephthalic acid, ethylene glycol and a catalyst in a reaction kettle in a nitrogen atmosphere until the esterification rate is 95-96.5%, adding an auxiliary agent and modified silicon dioxide, carrying out reduced pressure polycondensation, discharging, cooling and granulating a casting belt, removing water, and tackifying by using a rotary drum type solid-phase tackifying device until the intrinsic viscosity is 0.75-0.85dL/g. Specifically, the weight ratio of the refined terephthalic acid to the ethylene glycol to the catalyst to the auxiliary agent to the modified silicon dioxide is 50-60:22-27:0.01-0.014:0.005-0.01:0.8-1.1, the catalyst is at least one of an antimony-based catalyst and a titanium-based catalyst, and the auxiliary agent is at least one of triphenyl phosphite and triphenyl phosphate. In particular, the esterification reaction temperature is 220-250 ℃, the pressure is 0.2-0.3MPa, the decompression polycondensation temperature is 278-282 ℃, the vacuum degree is 50-80Pa, and the time is 90-120min. In particular, the preparation method of the modified silicon dioxide comprises the following steps: Step S1, stirring and dispersing silicon dioxide and Tris-HCl buffer solution under ultrasound, adding dopamine hydrochloride, performing first temperature control stirring reaction, centrifuging, collecting precipitate, washing with deionized water, and drying to obtain coated silicon dioxide; step S2, in nitrogen atmosphere, allyl alcohol, 3-urea propyl trimethoxy silane and toluene are stirred and mixed at a controlled temperature, butyl titanate is added, the mixture is subjected to a second temperatu