UV conductive slurry and preparation method thereof

Abstract

The preparation method comprises the following steps: (1) mixing a polysaccharide derivative solution, a carbon-based conductive filler dispersion liquid and a natural resin adhesive, and uniformly stirring to obtain a mixed solution A; (2) adding a polymeric dispersant, a rheology modifier, a reactive diluent and a photocuring component into the mixed solution A, and continuously stirring until the components are completely dissolved to obtain a mixed solution B; and (3) carrying out mechanical dispersion treatment on the mixed solution B for 2-4 hours at the rotating speed of 300-500 rpm to obtain the UV conductive electronic paste. The product has excellent conductivity (greater than or equal to 1.0 * 10 < 2 > S / cm), flexibility (bending radius less than or equal to 3 mm) and adhesive force (0-1 level), can be cured within 30 seconds under 80 mW / cm < 2 > UV light, and is suitable for preparing high-precision conductive patterns on a flexible substrate by a direct-writing printing process. The method is simple in process, environmentally friendly and efficient, can be widely applied to the fields of flexible electronics, wearable equipment and the like, and has remarkable industrial application value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic materials, in particular to a UV conductive electronic paste and a preparation method thereof, especially suitable for preparing flexible circuits by direct writing printing technology. BACKGROUND

[0002] With the rapid development of flexible electronics, the demand for conductive electronic paste is increasing. Traditional conductive paste mostly uses silver powder or copper powder as conductive filler, which has excellent conductivity, but high cost and insufficient flexibility. In recent years, carbon nanotubes (CNTs) have become an ideal choice for conductive fillers due to their excellent conductivity, mechanical strength and flexibility. However, the dispersion and stability of carbon nanotubes in the paste are still technical difficulties.

[0003] In the prior art, CNTs conductive paste mostly uses organic solvent as dispersion medium, which has environmental pollution and safety hazards. In addition, the curing method of traditional paste is mostly thermal curing, which has high energy consumption and is not suitable for heat-sensitive substrates. UV curing technology has the advantages of high efficiency, energy saving and environmental protection, but the existing UV conductive paste still has deficiencies in flexibility and adhesion.

[0004] Therefore, it is of great significance to develop a UV conductive electronic paste with good dispersion, excellent conductivity, strong flexibility and suitable for direct writing printing. For example, CN 10540028B discloses a water-based UV conductive ink, but its flexibility and printing precision need to be improved. SUMMARY

[0005] The purpose of the present application is to provide a UV conductive electronic paste and a preparation method thereof, which has excellent conductivity, flexibility and adhesion, and is suitable for preparing flexible circuits by direct writing printing technology.

[0006] The technical solution adopted by the present application is:

[0007] A preparation method of a UV conductive electronic paste, comprising the following steps:

[0008] (1) mixing a polysaccharide derivative solution, a carbon-based conductive filler dispersion liquid and a natural resin binder, stirring uniformly to obtain a mixed liquid A;

[0009] (2) adding a high molecular dispersant, a rheological modifier, an active diluent and a photocuring component to the mixed liquid A, continuing to stir until completely dissolved to obtain a mixed liquid B;

[0010] (3) mechanically dispersing the mixed liquid B, the dispersion time is 2h-4h, the rotation speed is 300rpm-500rpm, to obtain a UV conductive electronic paste.

[0011] As preferred, the polysaccharide derivative is acrylated hydroxyethyl cellulose, methacrylated sodium carboxymethyl cellulose, methacrylated carboxymethyl chitosan or methacrylic acid esterified sodium alginate, and the concentration of the polysaccharide derivative solution is 1-3%, i.e. 1-3 g of the polysaccharide derivative per 100 ml of water.

[0012] As preferred, the carbon-based conductive filler is conductive carbon black, graphene quantum dots (GQDs), carbon nanotubes (CNTs) or graphene, and the solid content of the carbon-based conductive filler dispersion is 1-5%, i.e. 1-5 g of the carbon-based conductive filler per 100 ml of water.

[0013] As preferred, the natural resin binder is glycerol ester of rosin, hydrogenated rosin or gum arabic, and the solid content of the natural resin binder is 20-30%, i.e. 20-30 g of the natural resin binder per 100 ml of water.

[0014] As preferred, the high-molecular dispersant is polyvinylpyrrolidone, sodium polystyrene sulfonate, polyethylene glycol or polyether-modified polysiloxane.

[0015] As preferred, the rheology modifier is fumed silica, hydroxyethyl cellulose or hydrogenated castor oil derivative.

[0016] As preferred, the reactive diluent is hydroxyethyl methacrylate, N-vinylpyrrolidone or ethylene glycol dimethacrylate.

[0017] As preferred, the photocuring component is a free radical type photoinitiator, including but not limited to benzophenone, acyl phosphine oxide or a combination thereof.

[0018] As preferred, the mechanical dispersion treatment in step (3) adopts ball milling or high-speed shearing dispersion, and the grinding medium is ceramic ball, and the volume ratio of the grinding medium to the mixed solution B is 1:1-2:1.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] (1) excellent conductive performance: the conductivity is ≥1.0×10 2 S / cm. The carbon-based conductive filler is added in the present application to ensure the conductive performance of the paste by using its high conductivity; in addition, the polysaccharide derivative and the high-molecular dispersant are also added in the present application to improve the dispersion stability of the carbon-based conductive filler in the aqueous system by using their synergistic effect, thereby further improving the conductive performance of the paste. This technical solution of the present application improves much more than simply adding the conductive filler, and has strong synergistic effect.

[0021] (2) Excellent flexibility and adhesion: The present application adopts natural resin adhesive and rheology modifier, which provides excellent adhesion and film-forming property, thereby enhancing the interface bonding of the sizing material with flexible substrates, and making the sizing material exhibit excellent adhesion and bending performance on flexible substrates such as TPU and PE. And adhesion (0-1 level).

[0022] (3) Environmentally friendly and efficient: The present application uses a water-based system, which greatly reduces the use of organic solvents.

[0023] (4) Excellent mechanical properties and flexibility: The photocuring component initiates rapid curing under UV irradiation, and the sizing material can be cured within 30 seconds under UV light of 80 mW / cm 2 . The active diluent participates in crosslinking reaction during UV curing, forming a three-dimensional network structure, thereby improving the mechanical properties and flexibility of the sizing material. Flexibility (bending radius ≤ 3 mm).

[0024] (5) Good printing suitability: The optimized rheological properties are suitable for precision machining technologies such as direct writing printing. The optimized rheological properties are achieved by precisely controlling the shear thinning properties, thixotropy and yield stress of the sizing material, mainly relying on the reversible three-dimensional network structure constructed by the rheology modifier (such as hydroxyethyl cellulose), which makes the viscosity of the sizing material decrease under high shear force during printing, facilitating extrusion, and quickly restores the viscosity to maintain the shape after deposition (under low shear force); at the same time, through the dispersion form control of conductive fillers (such as graphene / CNTs), the control of resin-active diluent ratio, and the precise control of solid content (20-30% resin, 1-5% filler) and the optimization of solvent evaporation rate, the sizing material has high printing precision, line stability and interlayer bonding strength, thereby meeting the requirements of direct writing printing for precision machining. DETAILED DESCRIPTION

[0025] The present application will be further described below in conjunction with specific examples and comparative examples, but the scope of protection of the present application is not limited thereto.

[0026] Example 1:

[0027] A UV conductive electronic sizing material is prepared by the following method:

[0028] (1) Mix 100 mL of acrylated hydroxyethyl cellulose (solid content 2%), 50 mL of carbon nanotube dispersion (solid content 3%), and 50.0 mL of natural rosin glycerol ester adhesive 25%, and stir for 30 min to obtain a mixed solution A;

[0029] (2) Add 5 g of polyvinylpyrrolidone, 0.50 g of hydroxyethyl cellulose, 0.50 g of ethylene glycol dimethyl acrylate, and 3.00 g of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methyl benzoin to the mixed solution A, and continue to stir for 1 h until completely dissolved to obtain a mixed solution B;

[0030] (3) Put the mixed solution B into a ball mill, add 150 mL of ceramic milling balls (1 mm in diameter), and mill at 400 rpm for 3 h to obtain a UV-curable flexible conductive paste.

[0031] Example 2:

[0032] Referring to Example 1, replace "acrylated hydroxyethyl cellulose" in step (1) with "sodium methacrylated carboxymethyl cellulose", and the rest is exactly the same as Example 1.

[0033] Example 3:

[0034] Referring to Example 1, replace "carbon nanotube dispersion (solid content 3%)" in step (1) with "graphene quantum dot (GQDs) dispersion (solid content 3%)", and the rest is exactly the same as Example 1.

[0035] Example 4:

[0036] Referring to Example 1, replace "50 mL of carbon nanotube dispersion (solid content 3%)" in step (1) with "25 mL of carbon nanotube dispersion (solid content 3%) + 25 mL of conductive carbon black dispersion (solid content 3%)", and the rest is exactly the same as Example 1.

[0037] Example 5:

[0038] Referring to Example 1, replace "acrylated hydroxyethyl cellulose (solid content 2%)" in step (1) with "sodium methacrylated carboxymethyl cellulose (solid content 2%)" and "carbon nanotube dispersion (solid content 3%)" with "graphene dispersion (solid content 1%)", and the rest is exactly the same as Example 1.

[0039] Example 6:

[0040] Referring to Example 1, replace "polyvinylpyrrolidone" in step (2) with "polyethylene glycol", and the rest is exactly the same as Example 1.

[0041] Example 7:

[0042] Referring to Example 1, replace "2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone" in step (2) with "phenyl (2.4,6-trimethylbenzoyl) phosphinic acid lithium salt", and the rest is exactly the same as Example 1.

[0043] Comparative Example 1: No polysaccharide added

[0044] Referring to Example 1, no polysaccharide derivative solution is added in step (1), and the rest is exactly the same as Example 1.

[0045] Comparative Example 2: Difference in polysaccharide concentration

[0046] Comparative Example 1, the solid content of the acrylicated hydroxyethyl cellulose in step (1) was changed to 1%, and the rest was exactly the same as Example 1.

[0047] Comparative Example 3: Difference in solid content of conductive filler

[0048] Comparative Example 1, the solid content of the acrylicated hydroxyethyl cellulose in step (1) was changed to 1%, and the rest was exactly the same as Example 1.

[0049] Comparative Example 4: Conductive carbon black dispersion

[0050] Comparative Example 1, the solid content of the acrylicated hydroxyethyl cellulose in step (1) was changed to 1%, and the rest was exactly the same as Example 1.

[0051] Comparative Example 5: Low concentration combination of polysaccharide

[0052] Comparative Example 1, the solid content of the acrylicated hydroxyethyl cellulose in step (1) was changed to 1%, and the rest was exactly the same as Example 1.

[0053] Comparative Example 6: No addition of high molecular dispersant

[0054] Comparative Example 1, step (2) does not add high molecular dispersant, and the rest is exactly the same as Example 1.

[0055] Comparative Example 7: No addition of photoinitiator

[0056] Comparative Example 1, step (2) does not add light curing component, and the rest is exactly the same as Example 1.

[0057] Performance test:

[0058] The performance test data of the UV conductive electronic paste of Examples 1-7 and the paste of Comparative Examples 1-7 are shown below:

[0059] Table 1, performance test data of the UV conductive electronic paste of Examples 1-7 and the paste of Comparative Examples 1-7

[0060]

[0061] Note:

[0062] Performance test standardization requirements: conductivity test must use four-probe method, before testing, the equipment should be calibrated with standard resistance sheet; adhesion test should be performed according to GB / T 9286-1998 standard, the grid spacing is 1mm x 1mm; flexibility test should be performed in constant temperature and humidity environment (23±2℃, 50±5%RH). Key process control points:

[0063] 1) Ball milling process parameter control: zirconium oxide ball diameter should be 0.5-1mm; ball-to-material ratio should be strictly controlled at 1:1-2:1; rotation speed fluctuation range should not exceed ±10rpm;

[0064] 2) UV curing conditions: ultraviolet light intensity: 80-100mW / cm 2 (365nm); curing distance: 5-10cm; exposure time: 30-60 seconds.

[0065] Raw material quality control standards:

[0066] 1) Carbon-based conductive filler: purity ≥98%; length 1-10μm; diameter 20-50nm.

[0067] 2) Light curing component: storage condition: avoid light, 4-10℃.

[0068] 3) Polysaccharide derivative solution: viscosity: 50-100cP (25℃); pH value: 6.5-7.5. Product performance acceptance standards: conductivity: ≥1.0×10 2 S / cm, adhesion: ≤1 grade (grid method), flexibility: bending radius ≤3mm (resistance change ≤10% after 100 cycles), surface drying time: ≤60 seconds (80mW / cm 2 UV irradiation).

[0069] Safety production matters needing attention:

[0070] 1) Carbon-based material handling: must be operated under local exhaust device; the operator should wear dust mask (P2 level or above)

[0071] 2) UV curing process: avoid direct view of ultraviolet light source;

[0072] 3) Waste liquid treatment: carbon-containing material waste liquid should be collected separately; photoinitiator waste liquid should be stored in dark. Process amplification matters needing attention: the milling equipment should be kept geometrically similar amplification, UV curing should consider the uniformity of light intensity distribution, it is recommended to first conduct 1:10 pilot test. When batch production, every 50kg product is a test batch.

Claims

1. A method of preparing a UV conductive electronic paste, characterized in that The method comprises the following steps: (1) mixing a polysaccharide derivative solution, a carbon-based conductive filler dispersion, and a natural resin binder, stirring uniformly to obtain a mixed solution A; (2) adding a high molecular dispersant, a rheological modifier, an active diluent, and a photocuring component to the mixed solution A, continuing to stir until completely dissolved to obtain a mixed solution B; (3) performing mechanical dispersion treatment on the mixed solution B, the dispersion time being 2-4 hours and the rotation speed being 300-500 rpm to obtain a UV conductive electronic paste.

2. The method for preparing the UV conductive electronic paste according to claim 1, characterized in that... The polysaccharide derivative is acrylated hydroxyethyl cellulose, methacrylated carboxymethyl cellulose sodium, methacrylated carboxymethyl chitosan, or methacrylic acid esterified sodium alginate, and the concentration of the polysaccharide derivative solution is 1-3%, i.e. 1-3 grams of the polysaccharide derivative per 100 milliliters of water.

3. The method for preparing the UV conductive electronic paste according to claim 1, characterized in that... The carbon-based conductive filler is conductive carbon black, graphene quantum dots, carbon nanotubes, or graphene, and the solid content of the carbon-based conductive filler dispersion is 1-5%, i.e. 1-5 grams of the carbon-based conductive filler per 100 milliliters of water.

4. The method for preparing the UV conductive electronic paste according to claim 1, characterized in that... The natural resin binder is glycerol ester of rosin, hydrogenated rosin, or gum arabic, and the solid content of the natural resin binder is 20-30%, i.e. 20-30 grams of the natural resin binder per 100 milliliters of water.

5. The method for preparing the UV conductive electronic paste according to claim 1, characterized in that... The high molecular dispersant is polyvinylpyrrolidone, polystyrene sulfonate sodium, polyethylene glycol, or polyether-modified polysiloxane.

6. The method for preparing the UV conductive electronic paste according to claim 1, characterized in that... The rheological modifier is fumed silica, hydroxyethyl cellulose, or hydrogenated castor oil derivative.

7. The method for preparing the UV conductive electronic paste according to claim 1, characterized in that... The active diluent is hydroxyethyl methacrylate, N-vinylpyrrolidone, or ethylene glycol dimethacrylate.

8. The method for preparing the UV conductive electronic paste according to claim 1, characterized in that... The photocuring component is a free radical type photoinitiator, including but not limited to benzophenone, acyl phosphine oxide, or a combination thereof.

9. The method for preparing the UV conductive electronic paste according to claim 1, characterized in that... In step (3), the mechanical dispersion treatment adopts ball milling or high-speed shearing dispersion, the grinding medium is ceramic balls, and the volume ratio of the grinding medium to the mixed solution B is 1:1-2:1.

Images