A quantum dot composition for screen printing and a method of preparing the same

Abstract

The present application relates to a kind of quantum dot composition for screen printing and its preparation method, which is composed of component A, component B and diffusion powder;The A component is quantum dot dispersion, which includes quantum dot dry powder and low viscosity functional modifier;The B component includes main resin, crosslinking agent, adhesion promoter, photoinitiator, light initiation promoter and antioxidant.The present application directly dissolves quantum dot dry powder in low viscosity functional modifier, without using volatile solvent, and has better environmental performance, and the compatibility of the preferred main resin used with quantum dot is good, and quantum dot fluorescent material is not easy to make fluorescence quenching or appear agglomeration, the prepared composition can be directly applied to screen printing process, avoiding the shortcomings of existing quantum dot ink and quantum dot photoresist, and the same or even better optical effect can be achieved, meeting the demand of current LED display industry for optical performance parameters, and the requirement for equipment is low, waste is less, which helps to reduce cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nanomaterials, in particular to a quantum dot composition for screen printing and a preparation method thereof. BACKGROUND

[0002] Quantum dot materials are currently a strong competitor of OLED in the display field, and are receiving more and more attention and research. With the development of LED technology, micro-Led and mini-Led technologies are gradually maturing, and nanomaterial quantum dots are better developed and applied. Currently, the combination of quantum dot materials and blue backlight technology focuses on display printing technology and photolithography technology. Quantum dot ink can be combined with various blue backlight technologies (micro-Led, mini-Led, and other blue backlight technologies) through printing technology, or can be combined with various blue backlight technologies to form a high color gamut display through photolithography technology.

[0003] Quantum dot printing technology is a new technology, and its equipment is expensive. The printing equipment has strict requirements on the physical properties of the ink. In order to ensure the printing performance, the amount of quantum dot fluorescent material can only be reduced to ensure the printing stability. However, the reduction of quantum dot fluorescent material cannot completely meet the optical performance requirements of the final product during display, which may cause incomplete absorption of blue light in the blue backlight and partial blue light leakage, thereby reducing the display color gamut of the display rather than improving it. In this case, in order to improve the display color gamut, the quantum dot material that cannot be completely absorbed must be removed by other means to better ensure the improvement of the color gamut. This is the cause of some defects in the current printing technology.

[0004] The blue light absorption value (OD) of the fluorescent material is currently required by the industry to be not less than 2 under the condition of a quantum dot material film thickness of 10 μm, that is, 99% of the blue light is absorbed by the nanofluorescent material and converted into fluorescence. Currently, for quantum dot printing ink, the OD value is not higher than 1.5 without external force, and even only 1-1.3. The optical parameter requirements cannot be met by itself, and only additional means can meet the requirements. This additional means reduces production efficiency and increases cost.

[0005] Quantum dot photolithography technology can better introduce quantum dots into the current mature production line, and the optical performance can also meet the requirements. However, the quantum dot photolithography technology also has the problem that the current photolithography line width cannot completely meet the industrial requirements, and there is also a small amount of photolithography falling phenomenon due to the imperfection of the current quantum dot photoresist technology. The price of quantum dot photoresist is relatively high, and during use, most of the photoresist needs to be washed away to form a pattern, which causes a huge waste and further increases the cost.

[0006] Screen printing refers to using a silk screen as a plate base and making a silk screen printing plate with graphics through a photosensitive plate making method. Figure 1 , Figure 1 A schematic diagram of screen printing is shown in the figure, screen printing is composed of five elements, a silk screen printing plate 1, a squeegee 2, ink 3, a printing table 4 and a printing substrate 5, the printing substrate 5 is placed on the printing table 4, the silk screen printing plate 1 is fixed with a screen frame 6 and is arranged above the printing substrate 5, and printing is performed by using the principle that the mesh holes of the graphic part of the silk screen printing plate 1 can allow ink to pass through, and the mesh holes of the non-graphic part cannot allow ink to pass through. During printing, ink 7 is poured into one end of the silk screen printing plate 1, a certain pressure is applied to the ink part on the silk screen printing plate 1 by using the squeegee 2, and the squeegee 2 is uniformly moved towards the other end of the silk screen printing plate 1, the ink 7 is squeezed from the mesh holes of the graphic part of the silk screen printing plate 1 to the printing substrate 5 by the squeegee 2 in the moving process, and the printing is completed. At present, there are few studies on applying screen printing to the field of quantum dot technology, and there is no scheme design for a quantum dot composition for screen printing application. SUMMARY

[0007] Therefore, the present application aims to solve the problems of insufficient optical performance of quantum dot printing ink system and waste of raw materials during use of quantum dot photoresist, and provides a quantum dot composition for screen printing.

[0008] A quantum dot composition for screen printing, which is composed of component A, component B and diffusion powder;

[0009] The component A is a quantum dot dispersion liquid, which is obtained by dispersing and dissolving quantum dot dry powder in a low-viscosity functional modifier; the low-viscosity functional modifier has a long carbon chain, which is an acrylate resin, a thiol resin, an organic amine resin, a benzene ring resin, an organic acid resin, a thiol compound, an organic amine compound or an organic acid, and the number of carbon atoms in the long carbon chain is not less than 6.

[0010] The component B includes a main body resin, a crosslinking agent, an adhesion promoter, a photoinitiator, a light initiation promoter and an antioxidant.

[0011] The quantum dot composition for screen printing according to the present application is obtained by directly dispersing and dissolving quantum dot dry powder in a low-viscosity functional modifier, the low-viscosity functional modifier is a low-viscosity material, which can increase the solubility of quantum dots in the composition system, adjust the crosslinking degree of the system, adjust the hardness of the finished product, and improve the leveling property of the overall formula; and the low-viscosity functional modifier is an active ingredient, which can not only dissolve the quantum dot dry powder, but also participate in the chemical reaction of the system, and will not volatilize into the environment, so the environmental protection performance is stronger than that of the volatile solvent commonly used in the prior art.

[0012] In addition, the embodiment of the present application preferably uses a main resin which has good compatibility with quantum dots, is not prone to quenching the fluorescence of quantum dot fluorescent materials or causing agglomeration, and can be directly applied to existing screen printing processes in the prepared quantum dot composition, thereby avoiding the shortcomings of existing quantum dot inks and quantum dot lithography, and achieving the same or even better optical effects, reducing the requirements for equipment, meeting the current demand for optical performance parameters in the LED display industry, and causing less waste than quantum dot lithography, thereby helping to reduce costs.

[0013] Further, the mass concentration of quantum dots in the quantum dot dispersion liquid is 50-75 wt.%.

[0014] Further, the low-viscosity functional modifier is a long carbon chain resin with a single functional group or a double functional group.

[0015] Further, the low-viscosity functional modifier is at least one of lauryl acrylate, lauryl methacrylate, tridecyl methacrylate, isodecyl methacrylate, isooctyl acrylate, 1,10-decanediol diacrylate, octyl mercaptan, dodecyl mercaptan, octylamine, oleic acid, styrene, and p-vinylbenzene.

[0016] The low-viscosity functional modifier is selected according to the principles of small polarity, low proportion of polar groups (carboxyl, amino, hydroxyl) in the resin, neutral pH value of the resin, good compatibility with quantum dots, and no quenching of quantum dot fluorescence performance. According to the experimental results, the presence of polar groups can cause fluorescence quenching, agglomeration, and other phenomena of quantum dot fluorescent materials, thereby reducing the efficiency of screen-printed quantum dot glue.

[0017] Further, the viscosity of the main resin is not less than 15000 cps, and the main resin is at least one of an acrylate resin, a polyurethane-modified acrylate resin, and an epoxy-modified acrylate resin. The main resin is selected based on the main selection criteria of good compatibility with quantum dot materials, no agglomeration of quantum dots after mixing, and no quenching of fluorescence performance, and is preferably an acrylate resin and a polyurethane-modified or epoxy-modified acrylate resin. Further selection is a pure acrylate resin and a polyurethane-modified acrylate resin, which can ensure the yellowing resistance of the overall formulation during the use of screen-printed quantum dot glue under long-term irradiation of blue light.

[0018] Further, the cross-linking agent is a multi-functional acrylic resin, and the compatibility with the quantum dots and the reaction speed during the curing process of the formula should be considered. In order to improve the compatibility with the quantum dots, the proportion of the polar structure in the whole resin should be reduced, and thus the ester group structure should be reduced. However, the quantum dots in the quantum dot glue can absorb ultraviolet energy during the curing process, and thus the curing efficiency is reduced. Therefore, in order to improve the efficiency, the functional group density should be as high as possible. According to the above factors and experimental data, the three-functional and four-functional acrylic ester resins are better, and further, the three-functional group is more suitable for the compatibility with the quantum dots and the curing efficiency in the later stage.

[0019] The antioxidant is selected from at least one of antioxidant 1076, antioxidant 1010, zinc dialkyldithiophosphate, and citric acid, so as to avoid the fluorescence quenching of the quantum dot nanomaterial due to the sensitivity to water and oxygen, and effectively improve the stability of the quantum dots in the composition.

[0020] The photoinitiator is selected from at least one of 2,4,6-trimethylbenzoyl ethyl phosphonate, 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone, 1-hydroxy-cyclohexyl-phenyl ketone, 3-methyl-4, phenyl benzophenone, 2-hydroxy-methyl phenyl propane-1-ketone, 2-isopropyl-thioxanthone, benzoin dimethyl ether, and 4-phenyl benzophenone photoinitiator.

[0021] Further, the viscosity of the adhesion promoter is not less than 5000 cps, so as to avoid the decrease of the overall viscosity of the composition formula.

[0022] The addition of the diffusion powder can improve the utilization rate of the quantum dot material, and further, the diffusion powder is an organic diffusion powder or an inorganic diffusion powder. In order to ensure the smoothness of the printing process and the optical performance, the particle size range is 0-1 μm, and the effect is better. The organic diffusion powder is selected from at least one of organic silicon diffusion powder, PMMA diffusion powder, PC diffusion powder, and nylon diffusion powder, and the inorganic diffusion powder is selected from at least one of calcium carbonate, aluminum oxide, zinc oxide, nickel oxide, and titanium dioxide. Through comprehensive experimental evaluation, the diffusion powder with a particle size of 150-700 nm has a better effect. More preferably, the diffusion powder with a particle size of 200-500 nm has a better effect.

[0023] In addition, the embodiment of the present application also provides a preparation method of the above-mentioned quantum dot composition for screen printing, which comprises the following specific operation steps:

[0024] S1, dispersing and dissolving the quantum dot dry powder in the low-viscosity functional regulator according to the formula weight ratio to obtain the quantum dot dispersion liquid;

[0025] S2, under yellow light environment, each raw material of B component is weighed according to the formula, and then mixed uniformly, and then B component is added into the quantum dot dispersion liquid in batches under mechanical stirring, and mixed uniformly;

[0026] S3, the mixture obtained in step S2 is added with the formula weight of the diffusion powder, and then the preset weight of the zirconium beads is added for grinding, and the quantum dot composition for screen printing is obtained after uniform grinding.

[0027] Further, the B component in step S2 is added in 3 batches, and each batch adds 15%, 35% and 50% of the total mass of the B component, respectively, to ensure that no agglomeration is generated after mixing.

[0028] The preparation method of the quantum dot composition for screen printing has simple preparation process, low requirement for equipment in the construction process, good environmental performance, low production cost, and is suitable for industrial scale production.

[0029] In order to better understand and implement, the present application will be described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a schematic diagram of screen printing. DETAILED DESCRIPTION

[0031] The present application will be further described below in conjunction with the embodiments of the present application. The following description is only for the purpose of explaining the present application and does not limit the content thereof.

[0032] Embodiment 1

[0033] Embodiment 1 of the present application provides a quantum dot composition for screen printing, which is composed of A component, B component and diffusion powder;

[0034] The A component is a quantum dot dispersion liquid, which is obtained by dispersing and dissolving quantum dot dry powder in a low viscosity functional modifier; the low viscosity functional modifier has a long carbon chain, which is an acrylate resin, a thiol resin, an organic amine resin, a benzene ring resin, an organic acid resin, a thiol compound, an organic amine compound or an organic acid, and the number of carbon atoms of the long carbon chain is not less than 6;

[0035] The B component includes a main body resin, a crosslinking agent, an adhesion promoter, a photoinitiator, a photoinitiator promoter and an antioxidant.

[0036] Embodiment 2

[0037] Embodiment 2 of the present application provides a preparation method of a quantum dot composition for screen printing, which includes the following specific operation steps:

[0038] S1, 10 g of green quantum dot powder is dispersed into 10 g of lauryl methacrylate to form a uniform quantum dot dispersion A, and the concentration of green quantum dots in the quantum dot dispersion A is 50 wt.%.

[0039] S2, 20 g of epoxy acrylate oligomer CNUVE150 is uniformly mixed with 10 g of epoxy methacrylate CN159, 4 g of adhesion promoter A55 acrylate resin, 1 g of antioxidant 1010, and 5 g of photoinitiator 184 to form a B component; then 6 g of the B component is added to the quantum dot dispersion A under mechanical stirring, and after uniform mixing, 16 g of the B component is slowly added, and after uniform stirring and dispersion, the remaining 20 g of the B component is added, and the mixture is uniformly stirred;

[0040] S3, 10 g of 500 nm silicone diffusion powder is added to the mixture obtained in step S2, and then a predetermined amount of zirconium beads is added to assist grinding to form the finished quantum dot composition for screen printing.

[0041] After testing, the viscosity of the quantum dot composition for screen printing is 10000-10800 cps.

[0042] Example 3

[0043] The embodiment 3 of the present application provides a preparation method of a quantum dot composition for screen printing, which comprises the following specific operation steps:

[0044] S1, 15 g of green quantum dot powder is dispersed into 10 g of lauryl methacrylate to form a uniform quantum dot dispersion A, and the concentration of green quantum dots in the quantum dot dispersion A is 75 wt.%.

[0045] S2, 20 g of aliphatic polyurethane acrylate CN989NS is uniformly mixed with 10 g of polyurethane acrylate CN983NS, 4 g of adhesion promoter A55 acrylate resin, 1 g of antioxidant zinc dialkyldithiophosphate, and 5 g of photoinitiator 184 to form a B component; then 6 g of the B component is added to the quantum dot dispersion A under mechanical stirring, and after uniform mixing, 16 g of the B component is slowly added, and after uniform stirring and dispersion, the remaining 20 g of the B component is added, and the mixture is uniformly stirred;

[0046] S3, 10 g of 700 nm PMMA diffusion powder is added to the mixture obtained in step S2, and then a predetermined amount of zirconium beads is added to assist grinding to form the finished quantum dot composition for screen printing.

[0047] The viscosity of the quantum dot composition for screen printing is 11000-12000cps after testing.

[0048] Embodiment 4

[0049] Embodiment 4 of the present application provides a preparation method of a quantum dot composition for screen printing, which comprises the following specific operation steps:

[0050] S1, 10g of red quantum dot powder is dispersed into 10g of tridecyl methacrylate to form a uniform quantum dot dispersion A, and the concentration of green quantum dots in the quantum dot dispersion A is 50wt.%.

[0051] S2, 20g of aliphatic polyurethane acrylate CN989NS is uniformly mixed with 10g of polyurethane acrylate CN983NS, 4g of adhesion promoter A55 acrylate resin, 1g of antioxidant zinc dialkyldithiophosphate, and 5g of photoinitiator 184 to form component B; then 6g of component B is added to the quantum dot dispersion A under mechanical stirring, and after uniform mixing, 16g of component B is slowly added, and after uniform stirring and dispersion, the remaining 20g of component B is added and stirred uniformly;

[0052] S3, 12g of 700nm PMMA diffusion powder is added to the mixture obtained in step S2, and then a preset weight of zirconium beads is added to assist grinding to form the finished quantum dot composition for screen printing.

[0053] The viscosity of the quantum dot composition for screen printing is 10000-11000cps after testing.

[0054] Embodiment 5

[0055] Embodiment 5 of the present application provides a preparation method of a quantum dot composition for screen printing, which comprises the following specific operation steps:

[0056] S1, 15g of red quantum dot powder is dispersed into 10g of tridecyl methacrylate to form a uniform quantum dot dispersion A, and the concentration of green quantum dots in the quantum dot dispersion A is 75wt.%.

[0057] S2, 20 g of epoxy acrylate oligomer CNUVE150 is mixed with 10 g of epoxy methacrylate CN159, 4 g of adhesion promoter A55 acrylate resin, 1 g of antioxidant zinc dialkyldithiophosphate, 5 g of photoinitiator 184 to form a B component; then 6 g of the B component is added to the quantum dot dispersion A under mechanical stirring, and after being mixed and uniformly dispersed, 16 g of the B component is slowly added, and the remaining 20 g of the B component is added after the quantum dot material is uniformly dispersed without agglomeration, and the mixture is stirred uniformly;

[0058] S3, 10 g of 500 nm silicone diffusion powder is added to the mixture obtained in step S2, and a predetermined amount of zirconium beads is added to assist grinding to form the quantum dot composition for screen printing.

[0059] After testing, the viscosity of the quantum dot composition for screen printing is 10000-11000 cps.

[0060] The quantum dot composition products prepared in examples 2-5 are spin-coated into quantum dot fluorescent films with a thickness of 10 μm, and the optical performance is tested under the conditions of a main wavelength of 450 nm and an intensity of 1000 nits, and the test data are shown in the following table:

[0061] Sample Measured film thickness pm OD Brightness nits External quantum efficiency % EQE Example 2 10 2.3 5684 46.8 Example 3 9.5 2.4 6894.7 49.7 Example 4 10.5 2.7 1987 42.5 Example 5 10 2.8 2249 45.1

[0062] The quantum dot composition for screen printing in example 1 of the present application is prepared by directly dispersing and dissolving quantum dot dry powder in a low-viscosity functional modifier, which is a low-viscosity material that can increase the solubility of quantum dots in the composition system, and also adjust the crosslinking degree of the system to adjust the hardness of the finished product and improve the leveling property of the overall formulation; and the low-viscosity functional modifier is an active ingredient that not only dissolves the quantum dot dry powder, but also participates in the chemical reaction of the system, and does not volatilize into the environment, which has stronger environmental protection performance than the volatile solvent commonly used in the prior art; in addition, the main resin is preferably used in the present application, which has good compatibility with quantum dots and is not easy to cause fluorescence quenching or agglomeration of quantum dot fluorescent materials, and the prepared quantum dot composition can be directly applied to the existing screen printing process, which can avoid the shortcomings of existing quantum dot ink and quantum dot lithography, and can achieve the same or even better optical effect, and can reduce the requirements for equipment compared with the quantum dot ink printing process, and meet the demand for optical performance parameters in the current LED display industry, and has less waste compared with the quantum dot lithography process, which helps to reduce costs.

[0063] The preparation method of the quantum dot composition for screen printing in the embodiments 2-5 has simple preparation process, less operation steps, lower requirement for equipment in the construction process, good environmental protection performance, low production cost and is suitable for industrial scale production.

[0064] The above embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the scope of protection of the present application.

Claims

1. A quantum dot composition for screen printing, characterized in that: Composed of component A, component B, and diffusing powder, the quantum dot composition for screen printing has an OD value greater than 2 in the fluorescent dot film. Component A is a quantum dot dispersion, obtained by dispersing and dissolving quantum dot dry powder in a low-viscosity functional modifier; the low-viscosity functional modifier is a long-chain resin with monofunctional or difunctional groups, and is selected from at least one of lauryl acrylate, lauryl methacrylate, tridecyl methacrylate, isodecanyl methacrylate, isooctyl acrylate, 1,10-decanediol diacrylate, octyl mercaptan, dodecanethiol, octylamine, oleic acid, styrene, and p-vinylbenzene; Component B includes a main resin, a crosslinking agent, an adhesion promoter, a photoinitiator, a photoinitiation promoter, and an antioxidant. The mass concentration of quantum dots in the quantum dot dispersion is 50~75 wt.%; The viscosity of the main resin is not less than 15000 cps, and it is selected from at least one of acrylate resin, polyurethane-modified acrylate resin, and epoxy-modified acrylate resin. The crosslinking agent is a multifunctional acrylic resin; the antioxidant is selected from at least one of antioxidant 1076, antioxidant 1010, antioxidant zinc dialkyl dithiophosphate, and citric acid; the photoinitiator is selected from at least one of ethyl 2,4,6-trimethylbenzoylphosphonate, 2-methyl-1-(4-methylthiophenyl)-2-morpholinyl-1-propanone, 1-hydroxy-cyclohexyl-phenyl ketone, 3-methyl-4-phenylbenzophenone, 2-hydroxy-methylphenylpropane-1-one, 2-isopropyl-thioxanthrone, benzoin dimethyl ether, and 4-phenylbenzophenone photoinitiator.

2. The quantum dot composition for screen printing according to claim 1, characterized in that: The viscosity of the adhesion promoter is not less than 5000 cps.

3. The quantum dot composition for screen printing according to claim 1, characterized in that: The diffusion powder is an organic or inorganic diffusion powder with a particle size range of 0-1 μm; the organic diffusion powder is selected from at least one of silicone diffusion powder, PMMA diffusion powder, PC diffusion powder, and nylon diffusion powder, and the inorganic diffusion powder is selected from at least one of calcium carbonate, aluminum oxide, zinc oxide, nickel oxide, and titanium dioxide.

4. A method for preparing a quantum dot composition for screen printing as described in any one of claims 1 to 3, characterized in that, The specific operating steps include the following: S1. Disperse and dissolve the quantum dot dry powder in a low viscosity functional regulator according to the formula weight ratio to obtain the quantum dot dispersion; S2. Weigh each raw material of component B according to the formula weight under yellow light environment, mix them evenly, and then add component B in several batches to the quantum dot dispersion under mechanical stirring, and mix evenly. S3. Add the formula weight of diffusion powder to the mixture obtained in step S2, and then add the preset weight of zirconium beads for grinding. After grinding evenly, the quantum dot composition for screen printing is obtained.

5. The method for preparing the quantum dot composition for screen printing according to claim 4, characterized in that: In step S2, component B is added in three batches, with each batch containing 15%, 35%, and 50% of the total mass of component B, respectively.

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