WO2023173820A1

WO2023173820A1 - Quantum dot light diffusion panel, preparation method therefor and use thereof

Info

Publication number: WO2023173820A1
Application number: PCT/CN2022/136662
Authority: WO
Inventors: 杨金山; 陈平绪; 叶南飚; 付锦锋; 王林; 刘学亮
Original assignee: 成都金发科技新材料有限公司
Priority date: 2022-03-16
Filing date: 2022-12-05
Publication date: 2023-09-21
Also published as: CN114889268A; CN114889268B

Abstract

Provided in the present invention are a quantum dot light diffusion panel, a preparation method therefor and the use thereof. The quantum dot light diffusion panel of the present invention uses, as a light diffusion layer, polystyrene (GPPS) into which a light diffusion agent master batch and a quantum dot master batch are added, and a protection layer is compounded on each of the upper surface and the lower surface of the light diffusion layer; and each protection layer is a PMMA resin layer subjected to blending modification by an SMA resin and an EAA resin, thus effectively improving an interlayer bonding force between the PMMA resin layer and the GPPS layer which are made of two different materials, and further remarkably prolonging the service life of the material. The quantum dot light diffusion panel of the present invention has a total light transmittance that is higher than 40% and can be as high as 60%, has a haze that is higher than 85% and can be up to 97%, and has a surface hardness grade that can be up to grade 2H; and after 600 hours of irradiation, a light aging color difference value of the quantum dot light diffusion panel reaches a level of △E≤1.5 and can be as low as 0.5.

Description

A kind of quantum dot light diffusion plate and its preparation method and application

Technical field

The invention belongs to the technical field of light diffusion materials and specifically designs a quantum dot light diffusion plate and its preparation method and application.

Background technique

Light diffusion material is a material that can allow light to pass through and effectively diffuse light. It can convert point and line light sources into line and surface light sources. It has a large scattering angle, good light conductivity, and uniform light transmission. Therefore, it is widely used in liquid crystal displays, LED lighting and imaging display systems. Its main function is to fully scatter the incident light to achieve a softer and more uniform illumination effect.

Light diffusion materials are generally made of transparent resin as a matrix and by adding a certain proportion of light diffusing agents and other additives. Commonly used transparent substrates include polycarbonate (PC), polymethylmethacrylate (PMMA), polystyrene (GPPS), and polypropylene (PP). Due to the advantages of polystyrene such as good rigidity, dimensional stability, high light transmittance, low haze and low cost, more and more backlight display devices and LED lamp covers are made of polystyrene-based light diffusion materials.

At present, polystyrene-based light diffusion materials are often prepared by blending, extruding and granulating polystyrene resin with a suitable proportion of light diffusing agent. Light diffusing agents mostly use organic polymer particles such as organic silicone, cross-linked PMMA microspheres, and polystyrene microspheres with a spherical structure. Although adding these light diffusing agents can better achieve higher light transmittance and effectively diffuse light, the overall cost is high and the preparation process is complicated, especially for light diffusing agents with microsphere structures. The shortcomings of polystyrene (GPPS) light diffusion plates are also obvious, such as poor transparency, poor surface scratch resistance, poor weather resistance, easy yellowing, and poor solvent resistance.

With the upgrading of products, there are higher requirements for the performance of light diffusion sheets. For example, with the development and progress of quantum dot display technology, quantum dot light diffusion materials have made progress in recent years, and products have begun to come out, such as TVs. Backsheet quantum dot film. Different from traditional liquid crystal displays, quantum dot displays use blue LED as the light source. The quantum dot film will excite pure green and red light when excited by blue light, and then mix the blue light to form high-quality white light. This special nanometer The technology achieves high color gamut coverage of the display and restores colors.

Quantum dot light diffusion plates can be prepared by adding quantum dots to GPPS resin. A layer of protective coating is compounded on the upper and lower surfaces of the polystyrene light diffusion plate. Although the performance of the light diffusion plate can be improved, the protective layer has nothing to do with light diffusion. The poor interlayer bonding strength of the board is an important factor affecting its widespread use.

Therefore, there is a need to develop a quantum dot light diffusion sheet with better mechanical properties and light diffusion properties.

Contents of the invention

The purpose of the present invention is to provide a method of mechanical properties and light diffusion in order to overcome the existing defects of easy delamination of quantum dot light diffusion sheets during use, and to further improve the light diffusion performance and mechanical strength of quantum dot light diffusion sheets. Quantum dot light diffusion sheet with good performance.

Another object of the present invention is to provide a method for preparing the quantum dot light diffusion plate.

Another object of the present invention is to provide the application of the quantum dot light diffusion plate in the field of imaging display.

In order to achieve the above objects, the present invention adopts the following technical solutions:

A quantum dot light diffusion sheet, including a GPPS quantum dot light diffusion core layer and PMMA protective layers located on the upper and lower surfaces of the GPPS quantum dot light diffusion core layer;

Wherein, the PMMA protective layer includes components calculated according to the following weight points:

The quantum dot light diffusion plate of the present invention uses polystyrene (GPPS) added with light diffusing agent masterbatch and optical quantum dot masterbatch as the light diffusion layer, and a protective layer is compounded on the upper and lower surfaces of the light diffusion layer. The protection layer The layer is a PMMA resin layer modified by blending SMA (styrene maleic anhydride copolymer) resin and EAA (ethylene acrylic acid copolymer) resin.

PMMA resin itself has good light transmittance and high surface hardness. While protecting the polystyrene light diffusion sheet, it does not affect the light diffusion (light transmittance and haze) of the light diffusion sheet. It can also be added by adding Weathering agents and other additives can improve the weather resistance of materials. However, studies have found that due to the high surface hardness of PMMA resin, its bonding performance with the GPPS light diffusion layer is poor. Especially after adding quantum dots, the surface polarity further decreases. If conventional adhesives are used, the Affects the light diffusion performance of the board, especially the light transmittance. The inventor of the present invention found through a large number of experimental studies that if the SMA resin and EAA resin added to the PMMA protective layer are blended and modified, PMMA can be effectively improved without affecting the hardness and light transmittance of the PMMA resin. The bonding force between the two different material layers, the resin layer and the GPPS layer, significantly increases the service life of the material.

Conventional GPPS quantum dot light diffusion core layers can be used in the present invention. The GPPS quantum dot light diffusion core layer includes components calculated according to the following weight:

It should be noted that conventional commercially available GPPS resins of medium and high viscosity can be used in the present invention. Optionally, the melt flow rate of the GPPS resin at 200°C and 5kg is ≤5g/10min. Higher melt viscosity is conducive to better dispersion of light diffusing agent masterbatch and quantum dot masterbatch in GPPS resin matrix. The melt flow rate of the GPPS resin under the conditions of 200°C and 5kg is in the range of 2.0-3.0g/10min, and the performance of the obtained plate is good.

Preferably, the PMMA resin has a melt flow rate of 2 to 10 g/10 min at 230°C and a load of 3.16 kg.

In the present invention, the melt flow rate of GPPS resin and PMMA resin is detected according to the ISO 1133-1:2011 standard method.

Optionally, the light diffusing agent is one or a combination of organic silicon light diffusing agents or inorganic light diffusing agents.

Conventional quantum dots can be used in the present invention. Optionally, the quantum dots are one or a combination of Cd-based quantum dots or ZnSe/ZnS quantum dots.

All currently commercially available SMA resins with conventional MA (maleic anhydride) content can be used in the present invention. The weight content of MA in existing commercially available SMA resins is 15 to 30%.

Existing commercially available EAA resins with conventional AA (acrylic acid) content can be used in the present invention. Preferably, the weight content of AA in the EAA resin is generally 8 to 25%, and more preferably 18 to 20%.

Optionally, the weathering agent is an ultraviolet absorber and/or a light stabilizer.

Preferably, the weather-resistant agent is a mixture of ultraviolet absorber and light stabilizer at a ratio of 1:1 to 1.5.

Preferably, the ultraviolet absorber is a benzotriazole ultraviolet absorber, including but not limited to 2-(2'-hydroxy-5'-methylphenyl) benzotriazole (UV-P) or 2- One or a combination of (2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole (UV-327).

Preferably, the light stabilizer is a hindered amine light stabilizer (HALS), including but not limited to one or a combination of HALS 944, HALS 770DF.

Preferably, in the quantum dot light diffusion plate, the thickness ratio of the GPPS quantum dot light diffusion core layer and the PMMA protective layer (referring to the protective layer of the single-sided surface layer, that is, the upper surface layer or the lower surface layer) is 1:0.05~0.15 .

The thickness of the light diffusion plate of the present invention can be 1.0 to 2.0 mm.

Preferably, other additives described in the GPPS quantum dot light diffusion core layer and PMMA protective layer are independently selected from one or a combination of lubricants, antioxidants or colorants.

Preferably, the PMMA protective layer includes components calculated according to the following parts by weight:

The preparation method of the quantum dot light diffusion plate includes the following steps:

After each component raw material of the GPPS quantum dot light diffusion core layer and each component raw material of the PMMA protective layer are mixed evenly, they are added to the co-extrusion extruder from different feeding ports. After melting and extruding , to obtain the quantum dot light diffusion plate.

It should be noted that in order to further improve the performance of the material, during the preparation process, we generally prepare the light diffusing agent and quantum dots separately from the matrix resin (such as GPPS) into masterbatch to improve the concentration of the light diffusing agent and quantum dots in the matrix. Dispersion properties in resins.

Preferably, the weight content of the light diffusing agent in the light diffusion masterbatch is 2-10%; the weight content of the quantum dots in the quantum dot masterbatch is 2-10%.

Preferably, the mixing is performed in a high-speed mixer, and the rotation speed of the high-speed mixer is 500 to 800 rpm.

Preferably, the extruder is a three-layer co-extrusion extruder. It should be noted that in the quantum dot light diffusion plate, the thickness ratio of each layer can be controlled by controlling the screw speed ratio of the extruder, and the thickness of the plate can be adjusted by the traction speed of the traction roller.

Preferably, the extrusion temperature (screw temperature) is 80-220°C. Specifically, from the feeding port to the machine head, the temperature is set to: the temperature in the first zone is 80-100°C, the temperature in the second zone is 180-200°C, and the temperature in the third zone is 200-220°C. ℃, the four zone temperature is 200~220℃, the screen changer temperature is 200~220℃, the transition zone temperature is 200~220℃, and the die head temperature is 200~220℃.

The application of the above-mentioned quantum dot light diffusion sheet in the field of imaging display is also within the scope of protection of the present invention, and can be specifically used to prepare the backplane of a liquid crystal display or the lampshade and panel of an LED lighting lamp.

Compared with the prior art, the beneficial effects of the present invention are:

The quantum dot light diffusion plate of the present invention uses polystyrene (GPPS) added with a light diffusing agent masterbatch and a quantum dot masterbatch as the light diffusion layer, and a protective layer is compounded on the upper and lower surfaces of the light diffusion layer. The protection layer The layer is a PMMA resin layer modified by blending SMA resin and EAA resin, which can effectively improve the interlayer bonding force between the PMMA resin layer and the GPPS layer, thus significantly increasing the service life of the material. Among them, the total light transmittance of the quantum dot light diffusion plate of the present invention is more than 40%, which can be as high as 60%; the haze is >85%, which can be as high as 97%; the surface hardness level can reach 2H level; after 600 hours of irradiation, The photoaging color difference value reaches the level of △E≤1.5 and can be as low as 0.5.

Description of the drawings

Figure 1 is a schematic structural diagram of the quantum dot light diffusion plate of the present invention.

Detailed ways

The present invention will be further described below with reference to specific embodiments and drawings, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field. Unless otherwise stated, the reagents and materials used in the present invention are all commercially available.

Examples of the present invention use the following raw materials:

Polystyrene (GPPS):

1#: GPPS-1050, the melt flow rate under 200℃ and 5kg load is 2.0g/10min, purchased from Foshan Total;

2#: GPPS-500N, the melt flow rate under 200℃ and 5kg load is 3.0g/10min, purchased from Dushanzi Petrochemical;

3#: GPPS WD-500E, the melt flow rate under 200℃ and 5kg load is 5.0g/10min, purchased from Shanghai Secco;

Light diffusing agent:

1#: Silicone light diffusing agent, KMP-590, purchased from Shin-Etsu, Japan;

2#: Silica, HDK H2000, purchased from Wacker, Germany;

Quantum dots:

1#: CdSe/ZnS quantum dots, OA-21158-25, purchased from Xingzi (Shanghai) New Materials;

2#: InP/ZnS quantum dots, OA-26158-25, purchased from Xingzi (Shanghai) New Materials;

PMMA resin:

1#: PMMA 205, the melt flow rate under 230℃ and 3.16kg load is 2.5g/10min, purchased from Zhenjiang Chimei;

2#: PMMA 207, the melt flow rate under 230℃ and 3.16kg load is 8.0g/10min, purchased from Zhenjiang Chimei;

SMA resin:

SMA-1: SZ10010, MA weight content is 25%, purchased from POLYSCOPE in the Netherlands;

SMA-2: SMA-700, MA weight content is 18%, purchased from Shanghai Huawen;

EAA resin:

EAA-1: 5990I, AA weight content is 20%, purchased from Dow Chemical of the United States;

EAA-2: 3004, AA weight content is 9.7%, purchased from Dow Chemical of the United States;

EAA-3: U00563, AA weight content is 18wt%, purchased from PLASTICS in the United States;

EMA resin: AC1330, purchased from DuPont in the United States;

Weathering agent:

1#-UV absorber UV-P: commercially available;

2#-Light stabilizer HALS 770DF: commercially available;

Other additives:

Lubricant: calcium stearate, commercially available;

It should be noted that in the present invention, the weathering agent and other additives used in each embodiment and comparative example are the same.

Examples 1 to 14

This embodiment provides a series of quantum dot light diffusion plates, which are prepared according to the formulas in Tables 1 to 2 and a preparation method including the following steps:

S1. Preparation of light diffusion masterbatch

The light diffusing agent and part of the GPPS resin are mixed evenly in a high-speed mixer at a weight ratio of 1:9, then added to a twin-screw extruder, and prepared by melt extrusion at 180 to 210°C;

S2. Preparation of quantum dot masterbatch

The quantum dots and part of the GPPS resin are mixed evenly in a high-speed mixer at a weight ratio of 1:9, then added to a twin-screw extruder, and prepared by melt extrusion at 180 to 210°C;

S3. Preparation of quantum dot light diffusion plate

According to the formula shown in Tables 1 to 2, mix the raw materials of each component of the GPPS quantum dot light diffusion core layer (GPPS resin, the light diffusing agent masterbatch obtained in S1., and the quantum dot masterbatch obtained in S2.) at high speed. After mixing evenly in the machine, add it to the feeding port of the main machine of the three-layer co-extrusion extruder; after mixing the raw materials of each component of the PMMA protective layer evenly in the high-speed mixer, add it to the auxiliary machine of the three-layer co-extrusion extruder. port; the above raw materials are melted and plasticized through each single-screw extruder respectively (wherein, the extrusion temperature (screw temperature) is 80~220℃, specifically from the feeding port to the machine head, the temperature in the first zone is 80~100℃ , the second zone temperature is 180～200℃, the third zone temperature is 200～220℃, the fourth zone temperature is 200～220℃, the screen changer temperature is 200～220℃, the transition zone temperature is 200～220℃, the die head temperature is 200～220℃) , and then extruded from a T-shaped die into a sheet. The extruded sheet is cooled with multiple cooling rollers, and the quantum dot light diffusion plate is obtained after being pulled and cut by a traction roller (schematic diagram is shown in Figure 1 Show).

Table 1 Contents of each component in the quantum dot light diffusion plates of Examples 1 to 7 (parts by weight)

Note: In each embodiment of the present invention, the upper and lower protective layers have the same thickness by default.

Table 2 Contents of each component in the quantum dot light diffusion plates of Examples 8 to 14 (parts by weight)

Comparative example 1

This comparative example provides a quantum dot light diffusion plate. The difference between the formula and Example 2 is that no SMA resin and EAA resin are added.

Comparative example 2

This comparative example provides a quantum dot light diffusion plate. The difference between the formula and Example 2 is that the added amount of SMA resin is replaced by 13 parts.

Comparative example 3

This comparative example provides a quantum dot light diffusion plate. The difference between the formula and Example 2 is that SMA resin and EAA resin are replaced with EMA.

Comparative example 4

This comparative example provides a quantum dot light diffusion plate. The difference between the formula and Example 2 is that the SMA resin and EAA resin in the PMMA protective layer are replaced and added to the GPPS quantum dot light diffusion core material.

Comparative example 5

This comparative example provides a quantum dot light diffusion plate. The difference between the formula and Example 2 is that the EAA resin in the PMMA protective layer is replaced with SMA resin (that is, no EAA resin is added).

Comparative example 6

This comparative example provides a quantum dot light diffusion plate. The difference between the formula and Example 2 is that the SMA resin in the PMMA protective layer is replaced with EAA resin (that is, no SMA resin is added).

Comparative example 7

This comparative example provides a quantum dot light diffusion plate. The difference between the formula and Example 2 is that the added amount of EAA resin is replaced by 1.5 parts.

Performance Testing

The quantum dot light diffusion plate prepared in the above examples and comparative examples was cut into a 100mm×100mm square plate sample, and its performance was tested. The specific test items and test methods are as follows:

1. Light diffusion performance test:

Test the light transmittance of the sample in accordance with the GB/T2410-2008 standard; use a haze meter to test the haze of the sample in accordance with the ASTM D1003-2013 standard.

2. Surface hardness: measured using a pencil hardness tester according to the national standard GB/T 6739-1996.

3. Photoaging resistance: tested according to the ISO 4892.2-2013 standard, test conditions: 0.51W/m ² , including 102 minutes of drying, 18 minutes of spraying, and 30 continuous cycles of irradiation, totaling 600 hours;

In addition, the present invention also tested the light transmittance of the light diffusion plate after 600 hours of simulation in the above-mentioned simulated environment.

The test results are detailed in Table 5:

Table 5 Performance test results

It can be seen from the above results:

The multi-layer (three-layer) co-extruded quantum dot light diffusion sheet prepared in various embodiments of the present invention has good optical properties, high surface hardness and light aging resistance. Specifically: the light transmittance of the light diffusion sheet is More than 40%, can be as high as 60%; haze >85%, can be as high as 97%; surface hardness level can reach 2H level; after 600h of irradiation, photoaging color difference value reaches △E≤1.5 level, can be as low as 0.5 . At the same time, it also has a long use time. After a 600h xenon lamp aging simulation test, the light transmittance can be maintained at more than 90%, which can be as high as 98.3%.

The results of Example 2 and Examples 4 to 5 show that the GPPS resin matrix within the melt flow rate range selected by the present invention can be used in the present invention, and the light diffusion performance (light transmittance and Haze) is better, but low melt flow rate (high viscosity) substrates perform better.

The results of Example 2 and Example 6 show that ordinary light diffusion masterbatch can be used in the present invention, but the light transmittance performance of inorganic light diffusion masterbatch is poor, but in the case of a small amount of addition, the light transmittance can reach 40 %.

The results of Example 2 and Example 7 show that ordinary quantum dots can be used in the present invention, and the prepared quantum dot light diffusion plate has good performance and can meet the basic usage requirements.

The results of Example 2 and Examples 8 to 9 show that conventional PMMA resin and SMA resin can be used in the present invention, and the prepared light diffusion plate has good light diffusion performance (light transmittance and haze).

The results of Example 2 and Example 10 show that the addition of other additives has little impact on the performance of the prepared light diffusion plate.

The results of Example 2 and Examples 11 to 12 show that the thickness ratio of the protective layer surface layer to the core layer is within the scope of the present invention and has little impact on the performance of the prepared light diffusion plate.

The results of Example 2 and Examples 13-14 show that in EAA resin, as the AA content in EAA resin increases, the initial transmittance and haze of the obtained plate show an upward trend and gradually level off. It shows that EAA resin with appropriate AA content can improve the performance of the board.

The results of Example 2, Comparative Examples 1 to 2, and Comparative Examples 5 to 7 show that adding an appropriate amount of SMA resin and EAA resin to the protective layer can enhance the interlayer properties without affecting the light diffusion performance of the material. The role of adhesion; Comparative Example 1 did not add SMA resin and EAA resin, Comparative Examples 5 and 6 added SMA resin and EAA resin separately, the interlayer adhesion effect of the quantum dot light diffusion plate obtained was not good, resulting in The light transmittance decreased significantly after aging; Comparative Example 2 added a large amount of SMA resin, and Comparative Example 7 added a large amount of EAA resin. The overall light diffusion performance and hardness of the prepared quantum dot light diffusion sheet decreased significantly.

Comparative Example 3 adds a conventional interlayer adhesive, but it will significantly affect the light transmittance retention, haze and weather resistance of the light diffusion plate; Comparative Example 4 adds SMA resin and EAA resin to the GPPS quantum dot light diffusion core In the layer, SMA resin also plays a role in enhancing the inter-layer adhesion, but it will significantly affect the light transmission retention rate of the light diffusion plate.

The above results show that only adding appropriate amounts of SMA resin and EAA resin to the PMMA protective layer will enhance the interlayer adhesion.

The above-described specific embodiments further describe the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above-mentioned are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

A quantum dot light diffusion sheet, which is characterized in that it includes a GPPS quantum dot light diffusion core layer and a PMMA protective layer located on the upper and lower surfaces of the GPPS quantum dot light diffusion core layer;

Wherein, the PMMA protective layer includes components calculated according to the following parts by weight:
The quantum dot light diffusion plate according to claim 1, characterized in that the GPPS quantum dot light diffusion core layer includes components calculated according to the following parts by weight:
The quantum dot light diffusion plate according to claim 2, characterized in that the melt mass flow rate of the GPPS resin under the conditions of 200°C and 5kg is ≤5g/10min.
The quantum dot light diffusion plate according to claim 3, characterized in that the melt mass flow rate of the GPPS resin under the conditions of 200°C and 5kg is 2.0-3.0g/10min.
The quantum dot light diffusion plate according to claim 2, wherein the light diffusing agent is one or a combination of organic silicon light diffusing agents or inorganic light diffusing agents.
The quantum dot light diffusion plate according to claim 1, characterized in that the weather-resistant agent in the PMMA protective layer is an ultraviolet absorber and/or a light stabilizer.
The quantum dot light diffusion plate according to claim 1, characterized in that the thickness ratio of the GPPS quantum dot light diffusion core layer and the PMMA protective layer on one side is 1:0.05~0.15.
The quantum dot light diffusion plate according to claim 1, wherein the weight content of AA in the EAA resin is 8-25%.
The preparation method of quantum dot light diffusion plate according to any one of claims 1 to 8, characterized in that it includes the following steps:

After each component raw material of the GPPS quantum dot light diffusion core layer and each component raw material of the PMMA protective layer are mixed evenly, they are added to the co-extrusion extruder from different feeding ports. After melting and extruding, , to obtain the quantum dot light diffusion plate.
Application of the quantum dot light diffusion plate described in any one of claims 1 to 8 in the field of imaging display.