CN-117507541-B - Optical polyester film and preparation method thereof

CN117507541BCN 117507541 BCN117507541 BCN 117507541BCN-117507541-B

Abstract

The optical polyester film comprises a core layer and at least one surface layer, wherein the core layer and the surface layer are prepared by adopting a coextrusion die head to carry out melt extrusion and biaxial stretching, the core layer comprises 30-90 wt% of conventional polyester and 10-70 wt% of semi-crystalline polyethylene naphthalate, the surface layer comprises 5-55 wt% of modified polyester, 35-94.9 wt% of conventional polyester and 0.1-10 wt% of functional master batch, the functional master batch contains smooth particles, the modified polyester is prepared by carrying out melt extrusion on 30-90 wt% of conventional polyester and 10-70 wt% of modified methacrylic resin, and the intrinsic viscosity of the modified polyester is 0.70-0.85 dL/g. The optical polyester film has the characteristics of low precipitation, excellent barrier property and good optical performance.

Inventors

Song Ruiran
LIU CHANGFENG
YAN ZHIXIONG
DU KUN
BAO SHIPING
CHENG LONGBAO
WANG QIN
SUN LUYANG

Assignees

合肥乐凯科技产业有限公司

Dates

Publication Date: 20260512
Application Date: 20231218

Claims (3)

1. The optical polyester film is characterized by comprising a core layer and at least one surface layer, wherein the core layer and the surface layer are prepared by adopting a coextrusion die head through melt extrusion and biaxial stretching, the core layer comprises 30-90 wt% of conventional polyester and 10-70 wt% of semi-crystalline polyethylene naphthalate, the surface layer comprises 5-55 wt% of modified polyester, 35-94.9 wt% of conventional polyester and 0.1-10 wt% of functional master batch, and the functional master batch contains smooth particles; the modified polyester is obtained by melt extrusion of 30-90 wt% of conventional polyester and 10-70 wt% of modified methacrylic resin, and the intrinsic viscosity of the modified polyester is 0.70dL/g-0.85dL/g; The modified methacrylic resin is prepared from methyl methacrylate, butyl acrylate, acrylic acid, glycidyl methacrylate, ammonium persulfate and sulfonate emulsifier, and is prepared by adding 1-3 wt% of sulfonate emulsifier and 5-10 wt% of deionized water into a three-neck flask filled with 15-25 wt% of methyl methacrylate, 20-25 wt% of butyl acrylate, 30-38 wt% of acrylic acid and 1-10 wt% of glycidyl methacrylate, stirring for 20min at 220r/min, adding 0.1-0.5% of acrylic acid, continuously stirring for 30min, reducing the rotation speed to 160r/min, heating to 75 ℃, adding 1-3mL of ammonium persulfate, continuously stirring for 30min, heating to 85 ℃, adding 1-3mL of ammonium persulfate, continuously stirring every 15min, adding 0.5-2mL of ammonium persulfate, cooling to 40 ℃ after 6 hours, and filtering; The semi-crystalline polyethylene naphthalate has an intrinsic viscosity of 0.5dL/g to 0.62dL/g; The intrinsic viscosity of the conventional polyester is from 0.65dL/g to 0.85dL/g.
2. The optical polyester film of claim 1, wherein the smooth particles are one or more of silicon dioxide, organic silicon, barium sulfate or calcium carbonate, the particle size of the smooth particles is 0.6-3.5 μm, and the addition amount is 1-10wt% of the weight of the master batch.
3. A process for producing an optical polyester film according to any one of claims 1 to 2, comprising the steps of: a. uniformly mixing conventional polyester and semi-crystalline polyethylene naphthalate, extruding and melting by a single screw, uniformly mixing conventional polyester, modified polyester and functional master batch containing smooth particles, extruding and melting by a double screw, and extruding the melt by a co-extrusion die head; b. casting the melt to form an amorphous polyester thick sheet on a cooling casting roller; c. Biaxially stretching and shaping, namely preheating a cooling roller casting sheet, longitudinally stretching for 2.9-4.6 times, preheating and transversely stretching for 3.0-5.1 times, and crystallizing and shaping; d. and (5) rolling and packaging, namely cooling and rolling the biaxially oriented polyester film to obtain the optical polyester film.

Description

Optical polyester film and preparation method thereof Technical Field The invention relates to an optical polyester film and a preparation method thereof, belonging to the technical field of polyester films. Background With the rapid development of flat panel display industry, particularly liquid crystal display industry (LCD), high-end optical polyester films are widely used in products such as liquid crystal televisions, tablet computers, mobile phones, and the like. Meanwhile, the development of flexible displays is receiving increasing attention. Because the photoelectric layer in the flexible photoelectric device is easily seriously damaged by vapor in the air, the photoelectric device is required to be packaged by adopting a high-barrier material, so that the reliability and the service life of the component are improved, and the optical polyester film for various electronic product displays can be separated out of the surface of the film in the production process and the subsequent processing and use processes, so that the optical polyester film is whitened, the visibility is reduced, the optical performance of the optical polyester film is reduced, the subsequent use is influenced, the components in the working procedure are polluted, and the requirement of a high-end optical film cannot be met. Currently, in order to meet the requirement that the subsequent deep processing is subjected to high temperature and high humidity treatment, a coating layer is usually coated to inhibit precipitation of oligomers. For example, chinese patent CN202111576765.6, at least one functional coating layer containing polyurethane and a crosslinking agent is coated on a multilayer coextruded longitudinally stretched film, so that the precipitation of oligomers can be effectively prevented. However, the coating method has the following defects that (1) the coating has heat resistance, high thickness requirement and complex process, and the production cost is increased, (2) the coating can cause the film surface film to generate flowery and streaks, thereby increasing the risk of disadvantages and influencing the subsequent use downstream. In order to basically reduce the precipitation of the oligomer in the polyester, solid-phase polymerization is also proposed to improve the inherent viscosity of the polyester chip, and the inherent viscosity of the polyester of the surface layer is more than 0.7dL/g by utilizing multilayer coextrusion to play a role in plugging the precipitation of the oligomer of the core layer, but when the film is prepared by the method, the inherent viscosity of the polyester of the surface layer is overlarge, the load of the extrusion procedure is increased, the shearing stress is increased, and the polymer is possibly thermally degraded, so that the appearance and the inherent quality of the film are influenced. Disclosure of Invention The invention provides an optical polyester film and a preparation method thereof, which are used for overcoming the defects in the prior art and have the characteristics of low precipitation, excellent barrier property and good optical performance. The technical scheme adopted for solving the technical problems is as follows: The optical polyester film comprises a core layer and at least one surface layer, wherein the core layer and the surface layer are prepared by adopting a coextrusion die head to carry out melt extrusion and biaxial stretching, the core layer comprises 30-90 wt% of conventional polyester and 10-70 wt% of semi-crystalline polyethylene naphthalate, the surface layer comprises 5-55 wt% of modified polyester, 35-94.9 wt% of conventional polyester and 0.1-10 wt% of functional master batch, and the functional master batch contains smooth particles; The modified polyester is obtained by melt extrusion of 30-90 wt% of conventional polyester and 10-70 wt% of modified methacrylic resin, and the intrinsic viscosity of the modified polyester is 0.70dL/g-0.85dL/g. The optical polyester film has an intrinsic viscosity of 0.5dL/g to 0.7dL/g. The optical polyester film is prepared from methyl methacrylate, butyl acrylate, acrylic acid, ammonium persulfate and sulfonate emulsifier. The preparation method of the modified methacrylic resin comprises the steps of adding 1-3 wt% of sulfonate emulsifier and 5-10 wt% of deionized water into a three-neck flask filled with 15-25 wt% of methyl methacrylate, 20-25 wt% of butyl acrylate, 30-38 wt% of acrylic acid and 1-10 wt% of glyceride methacrylate, stirring for 20min at 220r/min, adding 0.1-0.5% of acrylic acid, continuing stirring for 30min, reducing the rotation speed to 160r/min, heating to 75 ℃, adding 1-3mL of ammonium persulfate, continuing stirring for 30min, heating to 85 ℃, adding 1-3mL of ammonium persulfate, continuing stirring every 15min, adding 0.5-2mL of ammonium persulfate, cooling to 40 ℃ after 6 h, and filtering to obtain the modified methacrylic resin. The optical polyester film has an intrinsic