CN-121978788-A - High-brightness small-size composite membrane for backlight module and preparation method thereof

Abstract

The invention belongs to the technical field of backlight modules, and particularly relates to a composite membrane for a high-brightness small-size backlight module and a preparation method thereof. The invention aims to solve the problems of uneven thermal expansion coefficient and optical loss of an interface of the traditional composite membrane. The composite membrane designed and prepared by the invention sequentially comprises a diffusion layer, an adhesive layer, a second prism layer, an adhesive layer, a first prism layer, a PET substrate and a back coating. According to the invention, after surface treatment is carried out on a PET substrate, a layer of functional UV curing resin is coated on the back surface to form a back coating, the prism layer resin is processed on the front surface through UV nanoimprint lithography to obtain a first prism film, a second prism film is prepared by the same process, then a double-layer prism composite structure is obtained through lamination, and a diffusion layer is obtained through further lamination, so that a composite film product is finally obtained. The composite membrane prepared by the invention has small internal stress difference, small optical loss of an interface and good application value.

Inventors

• WU PEIFU
• WU DI
• ZHU XIAOLEI
• CHI WEI
• LIN LIN
• ZHANG DAZHAO

Assignees

• 江苏双星彩塑新材料股份有限公司

Dates

Publication Date

20260505

Application Date

20260126

Claims (8)

1. 1. A preparation method of a composite membrane for a high-brightness small-size backlight module is characterized by comprising the following steps: carrying out surface treatment on the PET substrate; coating a layer of functional UV curing resin on the back of the PET substrate to form a back coating; Processing prism layer resin on the front side of the PET substrate through UV nanoimprint lithography to obtain a first prism film; Repeating the UV nanoimprint lithography process on a new PET carrier film, and removing the PET carrier film to obtain a second prism film; The method comprises the steps of carrying out on-line plasma treatment on a first prism film, attaching a UV adhesive on the surface of the first prism film, accurately aligning a second prism film with the first prism film, enabling prism directions of the second prism film to be mutually orthogonal, and laminating; And attaching the UV adhesive to the surface of the second prism film, laminating the second prism film and the diffusion film, and finally curing to obtain the composite film.
2. 2. The method of claim 1, wherein the pre-curing, annealing and the first UV curing are performed sequentially after the back coating is formed.
3. 3. The method of claim 1, wherein three engraving master molds with three combinations of spacing and height are used in the UV nanoimprint lithography process.
4. 4. The method for preparing the composite membrane for the high-brightness small-size backlight module according to claim 1, wherein the bonding process of the first prism membrane and the second prism membrane is characterized in that the UV adhesive is transferred to the peak top of the prism tip of the first prism membrane through an intermediate carrier roller, and the first prism membrane and the second prism membrane are bonded and then subjected to a second UV curing treatment to form a double-layer prism composite structure.
5. 5. The method for preparing the composite membrane for the high-brightness small-size backlight module according to claim 1, wherein the bonding process of the second prism membrane and the diffusion membrane is characterized in that the UV adhesive is transferred to the peak top of the prism tip of the second prism membrane through an intermediate carrier roller, laminated and finally cured after being bonded with the diffusion membrane, and the composite membrane is obtained.
6. 6. The method for preparing the composite membrane for the high-brightness small-size backlight module according to claim 1, wherein the UV adhesive comprises aliphatic polyurethane acrylic ester and 1-hydroxycyclohexyl phenyl ketone.
7. 7. The method for preparing the composite membrane for the high-brightness small-size backlight module according to claim 1, wherein the diffusion membrane comprises bisphenol A epoxy acrylate, trimethylolpropane triacrylate and polymethyl methacrylate microspheres.
8. 8. The composite membrane for the high-brightness small-size backlight module sequentially comprises a diffusion layer, an adhesive layer, a second prism layer, an adhesive layer, a first prism layer, a PET (polyethylene terephthalate) substrate and a back coating, and is further characterized in that the composite membrane for the high-brightness small-size backlight module is prepared by the preparation method of any one of claims 1-7.

Description

High-brightness small-size composite membrane for backlight module and preparation method thereof Technical Field The invention belongs to the technical field of backlight modules, and particularly relates to a composite membrane for a high-brightness small-size backlight module and a preparation method thereof. Background With the continuous evolution of consumer electronics toward lighter, thinner, higher image quality and lower power consumption, backlight modules as core components of LCD modules have undergone significant technological changes. Among these, the advent of composite optical films is a key ring in this revolution. The integrated optical film integrates functions conventionally realized by stacking a plurality of independent optical films into a single component, and plays a role in realizing high-brightness and ultrathin small-size displays, especially in the application of a new generation of backlight technology represented by Mini LEDs. Conventional backlight modules typically require stacking at least three films, a bottom diffuser film for homogenizing light and two mutually orthogonal prism films for improving brightness. The composite membrane integrates the functional layers, the adhesive layer for adhesion and the protective layer into a whole through a precise manufacturing process. The design of the composite membrane is initially designed to meet the urgent demands of the market for thinner, brighter and more efficient displays, the application scene is highly concentrated in the fields with limited space and severe performance requirements, the thickness and the weight are remarkably reduced, the supply chain and the assembly difficulty can be simplified, and the optical coupling efficiency can be improved. While the advantages of composite membranes are significant, their highly integrated design and fabrication also present serious technical challenges. In terms of optical performance, a regular micro array on a prism film is easy to interfere with a pixel grid of an LCD panel to generate mole patterns, an interface optical loss is caused by a bonding layer of a composite film, and in terms of mechanical reliability, the composite film is formed by laminating a plurality of polymer materials, and internal stress imbalance is caused by the difference of thermal expansion coefficients of the materials, so that the film can be warped, curled and even layered. In order to solve the problems of uneven thermal expansion coefficient and optical loss of an interface of the traditional composite membrane, a composite membrane for a high-brightness small-size backlight module and a preparation method thereof are provided. Disclosure of Invention The invention aims to provide a composite membrane for a high-brightness small-size backlight module and a preparation method thereof. The composite membrane designed and prepared by the invention sequentially comprises a diffusion layer, an adhesive layer, a second prism layer, an adhesive layer, a first prism layer, a PET substrate and a back coating. According to the invention, after surface treatment is carried out on a PET substrate, a layer of functional UV curing resin is coated on the back surface to form a back coating, the prism layer resin is processed on the front surface through UV nanoimprint lithography to obtain a first prism film, a second prism film is prepared by the same process, then a double-layer prism composite structure is obtained through lamination, and a diffusion layer is obtained through lamination on the basis of the second prism film, so that a composite film product is finally obtained. In order to achieve the above purpose, the present invention provides the following technical solutions: A preparation method of a composite membrane for a high-brightness small-size backlight module comprises the following steps: unless otherwise specified, parts in the present invention refer to parts by mass. At the beginning of the production line, an optical grade PET substrate web was unwound and surface treated. Wherein, the transmittance of the PET substrate coiled material is more than 92 percent and the haze is less than 1 percent. And coating a layer of functional UV curing resin on the back surface of the PET substrate through a slit coating process to form a back coating, then performing low-energy pre-curing, and performing high-energy first UV curing after annealing. Wherein the thickness of the back coating is 3-5 mu m, the functional UV curing resin comprises 40 parts of bisphenol A epoxy acrylate, 30 parts of dipentaerythritol hexaacrylate, 20 parts of isobornyl acrylate, 3 parts of fumed silica, 3 parts of 1-hydroxycyclohexyl phenyl ketone, 1.5 parts of diphenyl (2, 4, 6-trimethylbenzoyl) phosphine oxide and 0.5 part of polyether modified polydimethylsiloxane, and the average molecular weight of the functional UV curing resin is 1000-1500 g/mol. And processing prism layer resin on the front surface of the PET