Alkali-soluble light-cured polyurethane resin as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to a preparation method and application of alkali-soluble light-cured polyurethane resin. The preparation method comprises the following steps: dissolving dihydroxy acid and isocyanate in a solvent in parts by weight, then adding a catalyst, reacting at the reaction temperature of 60-100 DEG C until the content of isocyanate groups reaches a theoretical value, and then carrying out an end-capping reaction with an end-capping reagent to obtain the alkali-soluble light-cured polyurethane resin. The alkali-soluble light-cured polyurethane resin is used for white solder resist ink, so that the glossiness of the white solder resist ink after curing can be effectively improved, the surface of the white solder resist ink has higher reflectivity, more light rays are reflected forwards, the light rays can point to viewers more intensively, the display effect during side view is improved, and the service life of the white solder resist ink is prolonged. The white solder resist ink has the advantages of ensuring uniform diffusion of light rays, improving the overall brightness and color vividness of an LED white back plate and the like, ensuring the light use efficiency, resisting yellowing at high temperature, and not influencing other properties of the white solder resist ink.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to an alkali-soluble photocurable polyurethane resin, its preparation method, and its application. Background Technology

[0002] Photocurable resins are photosensitive resins with relatively low molecular weight, possessing reactive groups such as unsaturated double bonds or epoxy groups. They can activate photoinitiators to initiate a curing reaction under ultraviolet or visible light irradiation. They are characterized by fast curing speed, low pollution, energy saving, and excellent performance of cured products, and are therefore widely used in coatings, printing, adhesives, optical fibers, optical discs, and electronic components or devices.

[0003] White solder resist ink used in the LED industry (especially LED text displays and small-pitch displays) requires high gloss and reflectivity due to its specific application scenarios. This is because white solder resist ink acts as a reflective layer on the PCB board of LED displays. A high-gloss surface has higher reflectivity, reflecting more light forward, thus improving the overall brightness and color vibrancy of the display. Simultaneously, high gloss provides mirror-like reflective properties, helping to concentrate light more effectively towards the viewer and improving the display effect when viewed from the side. Furthermore, for devices requiring uniform backlighting, high-gloss white ink reflects light better, ensuring even light diffusion and avoiding dark areas.

[0004] Currently, the low gloss of white solder resist inks on the market after curing indirectly affects the brightness of white LED backplanes and other components, thus impacting the light utilization efficiency of these products. Therefore, researching a polyurethane resin additive for use with white solder resist inks on LED backplanes is particularly important. This additive would not only effectively improve the gloss of the cured white solder resist ink and prevent yellowing at high temperatures, but also maintain the other properties of the white solder resist ink. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, the present invention aims to provide a method for preparing and applying an alkali-soluble photocurable polyurethane resin. This invention obtains the alkali-soluble photocurable polyurethane resin using a defined preparation method. In LED backplane manufacturing, adding a certain proportion of this polyurethane resin to white solder resist ink can effectively improve the gloss and reflectivity of the white solder resist ink after curing, as well as its resistance to yellowing at high temperatures, without affecting other properties of the solder resist ink. Therefore, it improves product quality and performance.

[0006] Therefore, the present invention provides the following technical solution: The present invention provides a method for preparing an alkali-soluble photocurable polyurethane resin, specifically as follows: 20-50 parts by weight of dihydroxy acid and 80-120 parts by weight of isocyanate are dissolved in 65-100 parts by weight of solvent, and then 0.15-0.35 parts by weight of catalyst are added. The reaction is carried out at a reaction temperature of 60-100℃ until the isocyanate group content reaches the theoretical value and the reaction is stopped. Then, 40-110 parts by weight of end-capping agent are used for end-capping reaction to obtain the alkali-soluble photocurable polyurethane resin.

[0007] Furthermore, the present invention also limits the temperature to 70-90°C, preferably 80°C.

[0008] Furthermore, the present invention further specifies that the dihydroxy acid is at least one or a mixture of two of dihydroxypropionic acid, dihydroxybutyric acid and their isomers.

[0009] Furthermore, the present invention also specifies that the solvent is an ester solvent, preferably one or a mixture of dipropylene glycol ethyl ether acetate, propylene glycol methyl ether acetate or divalent esters.

[0010] Furthermore, the present invention further specifies that the catalyst is one or a mixture of tetraethylammonium bromide, tetrabutylammonium chloride, and tetrabutylammonium bromide.

[0011] Furthermore, the present invention further specifies that the isocyanate is isoflurane diisocyanate or dicyclohexane-4,4'-diisocyanate.

[0012] Furthermore, the present invention further specifies that the capping agent is one or a mixture of two of hydroxyethyl methacrylate or hydroxypropyl methacrylate.

[0013] Furthermore, the present invention also defines an alkali-soluble photocurable polyurethane resin obtained by a defined preparation method.

[0014] Furthermore, the present invention also specifies the application of alkali-soluble photocurable polyurethane resin in improving the gloss of white solder resist ink. In this application, a mixture of photocurable acrylate resin and alkali-soluble photocurable polyurethane resin is added to the white solder resist ink raw material, wherein 15-50 parts of alkali-soluble photocurable polyurethane resin are added to 100 parts of photocurable acrylate resin.

[0015] By employing the above-described technology, the technical solution of the present invention has the following advantages compared with the prior art: This invention prepares an alkali-soluble photocurable polyurethane resin through a specific method and raw material ratio. This resin is then added in a certain proportion to the white solder resist ink of an LED backplane. This effectively improves the gloss of the white solder resist ink after curing. A high-gloss surface has higher reflectivity, allowing more light to be reflected forward. It also provides mirror-like reflective properties, helping to concentrate light more effectively towards the viewer, improving the display effect when viewed from the side, ensuring uniform light diffusion, and avoiding dark areas. This improves the overall brightness and color vibrancy of the LED white backplane, ensuring its light utilization efficiency. Furthermore, it is resistant to yellowing at high temperatures and does not affect other properties of the white solder resist ink, thus improving product quality. Detailed Implementation

[0016] The present invention will be further described below with reference to the embodiments. However, the present invention is not limited to the preferred embodiments described herein and does not limit the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0017] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0018] Example 1: A method for preparing an alkali-soluble photocurable polyurethane resin, specifically as follows: 30.16 g of 2,3-dihydroxypropionic acid was reacted with 100 g of isoflurane diisocyanate, 85 g of divalent ester, and 0.26 g of tetraethylammonium bromide at 80 °C for 4 h. When the NCO value of the system was 8.90% ± 1%, 68.08 g of hydroxypropyl methacrylate was added, and the reaction was continued at 80 °C until the NCO value of the system was < 0.1%, at which point the product was discharged. The acid value was measured to be 43.64 mg KOH / g.

[0019] Method for testing NCO value: Refer to HG / T 2409-1992 Determination of isocyanate group content in polyurethane prepolymer.

[0020] The method for testing acid value is GB / T 12008.5.

[0021] Example 2: A method for preparing an alkali-soluble photocurable polyurethane resin, specifically as follows: 20.11 g of 2,3-dihydroxypropionic acid was reacted with 100 g of isoflurane diisocyanate, 89.64 g of dipropylene glycol ethyl ether acetate, and 0.24 g of tetraethylammonium chloride at 80 °C for 4 h. When the NCO value of the system was 12.01% ± 1%, 89.04 g of hydroxypropyl methacrylate was added, and the reaction was continued until the NCO value of the system was <0.1%. The product was then discharged. The acid value was measured to be 32.05 mg KOH / g.

[0022] Example 3: A method for preparing an alkali-soluble photocurable polyurethane resin, specifically as follows: 35g of 2,4-dihydroxybutyric acid was reacted with 105g of dicyclohexane-4,4'-diisocyanate, 85g of propylene glycol methyl ether acetate, and 0.28g of tetrabutylammonium bromide at 80℃ for 4 hours. When the NCO value of the system was 6.12%±1%, 56.5g of hydroxyethyl acrylate was added, and the reaction was continued until the NCO value of the system was <0.1%. The product was then discharged. The acid value was measured to be 50.30 mgKOH / g.

[0023] Example 4: A method for preparing an alkali-soluble photocurable polyurethane resin, specifically as follows: 20.36 g of 2,3-dihydroxypropionic acid was reacted with 100 g of isoflurane diisocyanate, 100 g of divalent ester, and 0.15 g of tetraethylammonium bromide at 90 °C. During the reaction, when the NCO value of the system was measured to be 11.36% ± 1%, 69.21 g of hydroxypropyl methacrylate was added, and the reaction was continued until the NCO value of the system was <0.1%. The product was then discharged. The acid value was measured to be 26.41 mg KOH / g.

[0024] Example 5: A method for preparing an alkali-soluble photocurable polyurethane resin, specifically as follows: 48.94 g of 2,3-dihydroxypropionic acid was reacted with 100 g of isoflurane diisocyanate, 65 g of divalent ester, and 0.35 g of tetraethylammonium bromide at 60 °C. During the reaction, when the NCO value of the system was measured to be 3.33% ± 1%, 19.72 g of hydroxypropyl methacrylate was added, and the reaction was continued until the NCO value of the system was <0.1%. The product was then discharged. The acid value was measured to be 87.60 mg KOH / g.

[0025] Example 6: A method for preparing an alkali-soluble photocurable polyurethane resin, specifically as follows: 35.60 g of 2,3-dihydroxypropionic acid was reacted with 120 g of isoflurane diisocyanate, 85 g of divalent ester, and 0.21 g of tetraethylammonium bromide at 80 °C. During the reaction, when the NCO value of the system was measured to be 9.58% ± 1%, 63.71 g of hydroxypropyl methacrylate was added, and the reaction was continued until the NCO value of the system was <0.1%. The product was then discharged. The acid value was measured to be 48.93 mg KOH / g.

[0026] Example 7: A method for preparing an alkali-soluble photocurable polyurethane resin, specifically as follows: 48.94 g of 2,3-dihydroxypropionic acid was reacted with 105 g of isoflurane diisocyanate, 85 g of divalent ester, and 0.25 g of tetraethylammonium bromide at 80 °C. During the reaction, when the NCO value of the system was measured to be 3.87% ± 1%, 24.95 g of hydroxypropyl methacrylate was added, and the reaction was continued until the NCO value of the system was <0.1%. The product was then discharged. The acid value was measured to be 77.57 mg KOH / g.

[0027] According to Table 1, the photocurable acrylic resin was mixed with the alkali-soluble photocurable polyurethane resin of each embodiment with different feed amounts to obtain a photocurable acrylic resin mixture. Then, the mixture was prepared according to the conventional formula of white solder resist ink and premixed in a mixer. The mixture was then kneaded using a three-roll mill to obtain photocurable white solder resist ink. This white solder resist ink was printed using a 100-mesh screen with a printing thickness of 35-40 μm. After surface drying at 75°C and heat curing at 150°C, it was photocured. After photocuring, it was developed using a 1% sodium bicarbonate aqueous solution, soaked for 3 minutes, rinsed, and the exposure count and cleanliness were checked for any residue. After drying, its gloss was tested using CIE 130-1998. It was then subjected to tin immersion treatment at 288°C three times, each time for 10 seconds, and the change in b-value was measured using a colorimeter (the smaller the change in Δb, the better the resistance to yellowing). Adhesion test method: IPC-TM-6502.4.28.1, and its performance test results are shown in Table 2.

[0028] Table 1. Detailed list of ingredients for photocurable acrylic resin mixtures

[0029] White solder resist ink resin formulation (by weight parts): 45 parts of light-curable acrylic resin mixture; 3 parts of 819; 6 parts of TPO; 75 parts of titanium dioxide; 10 parts of fumed silica; 2 parts of dispersant; 1 part of leveling agent; 10 parts of propylene glycol methyl ether acetate.

[0030] Table 2 Performance test results after curing

[0031] The test results in Table 2 show that the gloss is significantly improved after adding the alkali-soluble photocurable polyurethane resin synthesized in this invention, and other properties are not affected. In practical applications, high gloss can improve the light reflection efficiency of the LED white display back panel, thereby improving light utilization and enhancing the brightness and color of electronic products.

[0032] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing an alkali-soluble photocurable polyurethane resin, characterized by The dihydroxy acid 20-50 parts and isocyanate 80-120 parts are dissolved in solvent 65-100 parts, then catalyst 0.15-0.35 parts is added, and the reaction is carried out at a reaction temperature of 60-100℃, until the isocyanate group content reaches the theoretical value, then end-capping agent 40-110 parts is added to carry out end-capping reaction to obtain alkali-soluble photocurable polyurethane resin.

2. The method for preparing an alkali-soluble photocurable polyurethane resin according to claim 1, characterized in that... The temperature is 70-90℃, preferably 80℃.

3. The method for preparing an alkali-soluble photocurable polyurethane resin according to claim 1, characterized in that... The dihydroxy acid is at least one of dihydroxypropionic acid, dihydroxybutyric acid and isomers thereof or a mixture of two.

4. The method for preparing an alkali-soluble photocurable polyurethane resin according to claim 1, characterized in that... The solvent is ester solvent, preferably one or a mixture of several of dipropylene glycol ethyl ether acetate, propylene glycol methyl ether acetate or divalent acid ester.

5. The method for preparing an alkali-soluble photocurable polyurethane resin according to claim 1, characterized in that... The catalyst is one or a mixture of tetraethylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium bromide.

6. The method for preparing an alkali-soluble photocurable polyurethane resin according to claim 1, characterized in that... The isocyanate is isophorone diisocyanate or dicyclohexylmethane-4,4'-diisocyanate.

7. The method for preparing an alkali-soluble photocurable polyurethane resin according to claim 1, characterized in that... The end-capping agent is one or a mixture of two of hydroxyethyl methacrylate or hydroxypropyl methacrylate.

8. An alkali-soluble photocurable polyurethane resin prepared by the method of claim 1.

9. Use of the alkali-soluble photocurable polyurethane resin of claim 8 to improve the gloss of white solder resist ink.

10. The use of claim 9, wherein 100 parts of photocurable acrylate resin is added with 15-50 parts of alkali-soluble photocurable polyurethane resin to the raw material of white solder resist ink resin.

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