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CN-122008666-A - Low-light-transmittance white polyester film and preparation method thereof

CN122008666ACN 122008666 ACN122008666 ACN 122008666ACN-122008666-A

Abstract

The invention discloses a low-light-transmittance white polyester film and a preparation method thereof, wherein the film is of a three-layer gradient composite structure and comprises an A-layer functional surface layer, a C-layer interface transition layer and a B-layer main light-blocking layer, wherein the A-layer, the C-layer and the B-layer are sequentially laminated, the total thickness of the film is 19-75 mu m, and the light transmittance is 12-20%. The low-light-transmittance white polyester film adopts a three-layer gradient composite structure, wherein the A layer directly faces the external environment, has the functions of weather resistance, scratch resistance and the like, the B layer is used as a light blocking main body to realize light scattering and concealing effects, anatase type TiO 2 hollow microspheres are used for replacing stretching to generate cells, and the sensitive influence of process fluctuation on porosity is eliminated. The C layer is used as a transition layer, matches the thermal expansion coefficient of the A/B layer, and enhances the stability of the whole structure. The layer C plays a role in buffering and bonding between the layer A and the layer B, so that the influence of the property difference of the two materials is minimized, and the internal stress is reduced, and the warping or layering risk is reduced.

Inventors

  • WU PEIFU
  • LIU HONGWEI
  • WU DI
  • CHI WEI
  • TANG XUCHENG

Assignees

  • 江苏双星彩塑新材料股份有限公司

Dates

Publication Date
20260512
Application Date
20250331

Claims (10)

  1. 1. A low-light-transmittance white polyester film is characterized by being of a three-layer gradient composite structure and comprising an A-layer functional surface layer, a C-layer interface transition layer and a B-layer main light blocking layer, wherein the A-layer, the C-layer and the B-layer are sequentially laminated, the total thickness of the film is 19-75 mu m, and the light transmittance is 12-20%.
  2. 2. The low light transmittance white polyester film according to claim 1, wherein the thickness of the a layer is 10% -15% of the total thickness of the film, and the low light transmittance white polyester film is prepared by using the copolymerization modified polyester containing 3% -5% of isophthalate of the total mass of the a layer as a base material, and adding 1% -3% of nano barium sulfate of the total mass of the a layer, 0.5% -1.0% of boron nitride nano sheet of the total mass of the a layer and 3% -5% of polyester elastomer TPEE of the total mass of the a layer.
  3. 3. The low light transmittance white polyester film according to claim 1 or 2, wherein the thickness of the B layer is 70% -80% of the total thickness of the film, and the film polyester with an intrinsic viscosity of 0.62 to 0.65dL/g is used as a base material, and anatase type titanium dioxide of 20% -25% of the total mass of the B layer, porous silica hollow microspheres of 8% -10% of the total mass of the B layer and a silane coupling agent KH-570 of 0.3% -0.5% of the total mass of the B layer are added.
  4. 4. A low light transmittance white polyester film according to any one of claims 1 to 3, wherein the thickness of the C layer is 10% to 15% of the total thickness of the film, and wherein the substrate is an epoxy-based modified copolyester containing 8% to 10% of an epoxidized component, and wherein 0.1% to 0.3% of a benzotriazole uv absorber and 0.5% of a lubricant of the total mass of the C layer are added.
  5. 5. The low light transmittance white polyester film according to any one of claims 1 to 4 wherein layer a is an outer layer, layer B is an inner layer, and layer C is located between layer a and layer B.
  6. 6. A process for preparing the low-light-transmittance white polyester film according to any one of claims 1 to 5, which comprises the steps of pre-mixing, granulating and drying the raw materials of the layers A, B and C respectively to prepare a raw material master batch, carrying out melt extrusion on the raw material master batch by adopting at least three independent extruders to form A, B, C three layers of melt, carrying out die coextrusion stretching to obtain a film with a three-layer composite structure, carrying out longitudinal and transverse stretching on the film after the die coextrusion, and carrying out ion surface modification treatment on the stretched film.
  7. 7. The method of claim 6, wherein the starting materials for the a layer, the B layer and the C layer are dried at a temperature of 120 ℃ to 150 ℃ for a drying time of 4 to 6 hours before melt extrusion.
  8. 8. The method of claim 6 or 7, wherein the melt extrusion is performed at a temperature in the range of 310-315 ℃ for layer a, 305-310 ℃ for layer B, 295-300 ℃.
  9. 9. The method according to any one of claims 6 to 8, wherein the machine direction stretch ratio is 3.0 to 3.5, the machine direction stretch temperature is 100 to 110 ℃, the transverse direction stretch ratio is 3.2 to 3.8, and the transverse direction stretch temperature is 115 to 120 ℃.
  10. 10. The method according to any one of claims 6 to 9, wherein the temperature of the ion surface modification treatment is 200 ℃ to 230 ℃ and the treatment time is 3-5 seconds.

Description

Low-light-transmittance white polyester film and preparation method thereof Technical Field The invention relates to an optical film, in particular to a low-light-transmission optical film which can be used in the fields of solar photovoltaic backboard, light source shielding material, electronic adhesive tape and the like, and particularly relates to a low-light-transmission white polyester film and a preparation method thereof. Background The low-light-transmission optical film is widely applied to the fields of solar photovoltaic backboard, light source shielding material, electronic adhesive tape and the like. For example, in a solar photovoltaic back sheet, the low light transmission optical film can provide a good shading effect, prevent mutual interference between the battery pieces, and improve the power generation efficiency of the assembly. In the optical light source, the low-light-transmission optical film can be used for manufacturing decorative wallpaper with special effects, such as shading wallpaper, noctilucent wallpaper and the like. Can be used as an inner layer material of the lamp box cloth to provide uniform backlight effect and good light shielding performance. In the electronic adhesive tape, the low-light-transmission optical film can be used as an insulating layer or a shielding layer, and the low light transmission can block light rays, prevent the light rays from interfering sensitive electronic elements, and is particularly suitable for application scenes needing shading. CN 101605841B discloses a white polyester film and a reflecting sheet, and the white polyester film of the prior art is suitable for the optical field, especially for applications such as liquid crystal display devices, backlight devices and reflecting mirrors. The white polyester film has high reflectivity and high concealment, and is suitable for optical films requiring light stability and antifouling property. The basic scheme of the white polyester film in the prior art is that the film comprises a hollow structure, and the resin forming the film consists of polyester resin and cyclic olefin copolymer resin. The void ratio of the film should be more than 25% and less than 75% to ensure high brightness and high concealment. However, the cavity structure of the prior art is prone to absorb moisture, and may expand and deform in a long-term humidity environment, and uniformity is lowered. CN 110837142B discloses a white polyester reflective film and its application in backlight source of liquid crystal display, in this prior art, through ABA three-layer structure design (surface layer a layer contains polyester, inorganic particles and toughening agent, middle layer B adds incompatible resin to form cells), the reflectivity is over 96%, the light uniformity is over 84.3%, and the reflective film is suitable for side-in type and direct type backlight source of ultrathin electronic equipment. The surface layer A in the prior art contains inorganic particles (such as silicon dioxide) and a toughening agent, so that the surface hardness and scratch resistance are improved, and meanwhile, the light is primarily scattered. The intermediate B layer forms a micron-sized cell structure after stretching by adding an incompatible resin (such as polymethylpentene), enhances light scattering and improves reflectivity. According to the prior art, through a layered isolation design, interface defects caused by direct mixing of incompatible resin and surface layer materials are avoided, and the maximum performance of each component is ensured. However, the cell structure of this prior art is also prone to moisture absorption, and may expand and deform in a long-term humidity environment, with reduced uniformity. In addition, the A/B layer material has larger thermal expansion coefficient difference, and is easy to generate internal stress under temperature circulation to cause warping or layering. Disclosure of Invention The technical problem to be solved by the invention is to provide a low-light-transmittance white polyester film and a preparation method thereof, so as to reduce or avoid the problems. In order to solve the technical problems, the invention provides a low-light-transmittance white polyester film, wherein the film is of a three-layer gradient composite structure and comprises an A-layer functional surface layer, a C-layer interface transition layer and a B-layer main light-blocking layer, wherein the A-layer, the C-layer and the B-layer are sequentially laminated, the total thickness of the film is 19-75 mu m, and the light transmittance is 12-20%. Preferably, the thickness of the layer A accounts for 10% -15% of the total thickness of the film, the copolymer modified polyester containing 3% -5% of isophthalic acid ester of the total mass of the layer A is used as a base material, and nano barium sulfate accounting for 1% -3% of the total mass of the layer A, boron nitride nano sheets accounting for 0.5% -1.0