Low-reflection ink and preparation method thereof

Abstract

The invention discloses low-reflection printing ink and a preparation method thereof. The low-reflection printing ink is prepared by adding matting powder, carbon black and modified activated carbon powder into a resin material. Microcosmic roughness is formed on the surface of the coating after ink curing, specular reflection is reduced, in addition, the light absorption capacity of the coating is further enhanced through the modified activated carbon powder, and the modified activated carbon powder and the light absorption capacity of carbon black can well achieve a synergistic effect to jointly reduce light reflection of the coating. The prepared low-reflection ink has the advantages of being good in weather resistance, low in reflectivity, excellent in construction performance and the like.

Description

Technical Field

[0001] This invention relates to the field of ink and processing technology, and in particular to a low-reflection ink and its preparation method. Background Technology

[0002] In various advanced optical systems, such as camera lenses, microscopes, telescopes, lasers, and various photoelectric sensors, surface reflection control of optical components is one of the key technologies determining system performance. When light incident on the surface of optical components such as lenses, windows, and prisms, stray light inevitably occurs due to the refractive index difference between air and glass (or other optical materials). This stray light undergoes multiple reflections within the optical system before reaching the image plane, forming halos and ghosting, severely degrading the imaging effect. To eliminate the adverse effects of stray light, the commonly used solution is to coat the surface of the optical components with a coating to shield stray light.

[0003] Currently, common low-reflectivity coatings are applied by spraying or coating with low-reflectivity paint. These low-reflectivity coatings primarily use resin with the addition of large amounts of light-absorbing carbon black and matting agents that reduce specular reflection, such as matting powder and alumina, to synergistically reduce the coating's reflectivity. This combination generally struggles to achieve a reflectivity of less than 1% in the visible light 380-780nm range. Due to the large amount of carbon black and matting powder added, the coating often suffers from poor mechanical strength, failing to meet the stringent requirements of optical devices: high optical uniformity, excellent adhesion, and superior environmental reliability (resistance to humidity and heat, abrasion resistance, and aging resistance).

[0004] Therefore, a low-reflection ink that is easy to apply, has low reflectivity, excellent weather resistance and reliability is being developed to promote its application in lens imaging. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a low-reflection ink and its preparation method. By scientifically controlling the formulation system and modifying the activated carbon powder, the light absorption capacity of the film surface can be further enhanced, and the light reflection can be reduced, thereby meeting the low-reflection requirements of optical components.

[0006] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is: to provide a low-reflection ink, comprising, by weight, parts of: 33-38 parts of resin 18-24 parts diluent 5-8 parts of dispersant 9-12 parts carbon black 6-10 parts of modified activated carbon powder 3-5 parts matte powder 0.1-0.5 parts of defoamer 10-13 parts of curing agent 0.1-0.3 parts of drying agent In a preferred embodiment of the present invention, the method for preparing the modified activated carbon powder includes the following steps: (1) After thoroughly washing the activated carbon powder with deionized water, spread it evenly in a ceramic container and place it in a high-temperature tube furnace. Under a nitrogen atmosphere with a flow rate of 30-40 ml / min, heat the powder to 900-1000℃ at a rate of 3-5℃ / min and hold it at that temperature for 2-4 hours. Then, allow it to cool naturally to room temperature. Next, boil the powder in distilled water for 10-30 minutes and vacuum dry it at 80℃ for 6 hours. The pretreated activated carbon powder is obtained.

[0007] (2) Dissolve KH560 in a mixed solution of ethanol and deionized water, adjust the pH to 4-5 with acetic acid, and hydrolyze at 40°C for 40-60 minutes to generate active silanol groups (Si-OH); then add the pretreated activated carbon powder and stir at 60-80°C for 6-8 hours to allow the silanol groups of KH560 to undergo a condensation reaction with the hydroxyl groups (-OH) on the surface of the activated carbon powder to form covalent bonds (Si-OC); after the reaction, wash with anhydrous ethanol and deionized water until neutral to remove excess silane coupling agent from the powder surface. Transfer to 80°C for vacuum drying for 4 hours, and then dry at 120°C for 2 hours to further remove moisture and solvent from the modified activated carbon powder to obtain modified activated carbon powder.

[0008] Furthermore, the activated carbon powder is wood-based activated carbon powder with a mesh size of 2500-3000 mesh.

[0009] Furthermore, the mass ratio of KH560, ethanol, and deionized water is 1:7~9:1~2.

[0010] Furthermore, the mass ratio of KH560 to activated carbon powder is 1:3~5.

[0011] In a preferred embodiment of the present invention, the resin is a branched saturated polyester resin with a hydroxyl value of 45~55 mgKOH / g.

[0012] In a preferred embodiment of the present invention, the curing agent is a blocked hexamethylene diisocyanate trimer (HDI trimer).

[0013] In a preferred embodiment of the present invention, the dispersant is one of polyester-type polymeric dispersant and polyurethane-type polymeric dispersant.

[0014] In a preferred embodiment of the present invention, the drying agent is one of organotin drying agents and organobismuth drying agents. In a preferred embodiment of the present invention, the defoamer is one of polydimethylsiloxane and polyether-modified siloxane.

[0015] In a preferred embodiment of the present invention, the diluent is at least one of dimethyl nylonate and propylene glycol methyl ether acetate.

[0016] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is: to provide a method for preparing low-reflection ink as described in any of the preceding claims, comprising the following steps: After mixing resin, diluent, dispersant, and defoamer evenly, add carbon black, matting powder, and modified activated carbon powder and mechanically stir at 1200 R / min for 20 minutes. Grind using a three-roll mill until the fineness is less than 20 μm. Remove the ground material, add curing agent and drying agent, and mechanically stir at 600~900 R / min for 10~20 minutes to disperse it evenly. After filtration, the low-reflection ink is obtained.

[0017] The present invention aims to achieve the following objectives: First, through scientific control of the formulation system, the ink has sufficient working time at room temperature to meet the process adjustment needs during production; the ink can be screen printed, sprayed or coated, and has excellent aging reliability after curing into a film.

[0018] Secondly, high-temperature treatment of activated carbon powder can further open its originally closed pores. Modifying activated carbon with silane coupling agents can improve its compatibility and stability in the formulation system. Because activated carbon powder has well-developed pores, it can further enhance the light absorption capacity of the film surface, reducing light reflection and thus meeting the low-reflection requirements of optical components.

[0019] The beneficial effects of this invention are: (1) The present invention can open the originally closed pores of activated carbon powder by high temperature treatment under nitrogen atmosphere, thereby increasing the micropore content and expanding the pore size of the original pores, so that the light absorption effect of activated carbon powder when adding ink to form film is further enhanced, thereby further reducing the light reflection effect of film layer. (2) The present invention uses silane coupling agent to modify the surface of activated carbon powder, which increases the compatibility between activated carbon powder and resin, and can further increase the amount of activated carbon powder added in the system. (3) The low-reflection ink of the present invention has good leveling properties and can meet the requirements of screen printing, spraying or coating processes; the coating has low reflectivity and excellent aging reliability. Detailed Implementation

[0020] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention are described in detail below. The following content is merely illustrative and explanatory of the concept of the present invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not depart from the inventive concept or exceed the scope defined in these claims, all of which should fall within the protection scope of the present invention.

[0021] The following is information on the raw materials used in the implementation plan: Activated carbon powder: 3000 mesh wood-based activated carbon produced by Shenzhen Xingwanbang Activated Carbon Co., Ltd. Carbon black: Orion's high-pigment carbon black FW-200; Matting agent: SD-530U manufactured by Aerospace Saide; average particle size: 5-7μm; Resin: Shanghai Kangming Chemical NL387-6 resin (hydroxyl value: 50mgKOH / g, solid content: 63~67%). Curing agent: PT-1080Y from Guangzhou Lvbao New Materials Co., Ltd. (NCO content: 10.5±0.2%, solid content: 68~72%). Diluents: Dimethyl methacrylate (MDBE) produced by Yuanli Chemical Co., Ltd., and Propylene glycol methyl ether acetate (PMA) produced by Jiangsu Yida Chemical Co., Ltd. Dispersant: KEPERDISP from Zhuhai Jintuan Chemical Co., Ltd. ® -6538; Defoamer: QM-2068 from Dongguan Qiming New Material Technology Co., Ltd.; Drying agent: OB-5 from Guangzhou Tukebang New Materials Co., Ltd.

[0022] Example 1: Take 33 parts of resin, then add 21 parts of diluent (PMA:MDBE weight ratio of 2:1), 5 parts of dispersant, 0.1 parts of defoamer, 9 parts of carbon black, 8 parts of modified activated carbon powder, and 3 parts of matting agent. Mechanically stir at 1200 R / min for 20 min, then grind using a three-roll mill. When the fineness is less than 20 μm, remove the ground material, then add 12 parts of curing agent and 0.1 parts of drying agent. Mechanically stir at 800 R / min for 20 min to ensure uniform dispersion, then filter through a 200-mesh filter to obtain flexible low-reflection ink.

[0023] The modified activated carbon powder is prepared as follows: 1250-mesh activated carbon powder is thoroughly washed with deionized water, then 28g is weighed and spread evenly in a ceramic container, placed in a high-temperature tube furnace, heated to 950℃ at a rate of 4℃ / min under a nitrogen atmosphere with a flow rate of 35mL / min, held for 3 hours, and then naturally cooled to room temperature. The powder is then boiled in distilled water for 30 minutes and vacuum dried at 80℃ for 6 hours to obtain pretreated activated carbon powder.

[0024] Add 6g of silane coupling agent KH560 to 48g of ethanol and 9g of deionized water, then add 0.6mL of acetic acid to adjust the pH to 4-5. Heat in a water bath to 40℃ and stir continuously at 200R / min for 50min. Then add 24g of the pretreated activated carbon powder and stir in a 72℃ water bath for 6 hours. After the reaction, wash with anhydrous ethanol and deionized water until neutral to remove excess silane coupling agent from the powder surface. Transfer to 80℃ for vacuum drying for 4h, then dry at 120℃ for 2h to further remove moisture and solvent from the modified activated carbon powder, obtaining the modified activated carbon powder.

[0025] Example 2: The difference from Example 1 is that the amount of modified activated carbon powder added is 6g.

[0026] Example 3: The difference from Example 1 is that the amount of modified activated carbon powder added is 10g.

[0027] Example 4: The difference from Example 1 is that the resin is 38g and the curing agent is 13g.

[0028] Example 5: The difference from Example 1 is that the amount of carbon black added is 12g.

[0029] Comparative Example 1: The difference from Example 2 is that the activated carbon powder is commercially available activated carbon powder and has not been modified.

[0030] Comparative Example 2: The difference from Example 2 is that the activated carbon powder was treated at high temperature under a nitrogen atmosphere and was not modified with a silane coupling agent.

[0031] Comparative Example 3: The difference from Example 1 is that the amount of modified activated carbon added is 4g.

[0032] Comparative Example 4: The difference from Example 1 is that the amount of modified activated carbon added is 12g.

[0033] Comparative Example 5: Take 33 parts of resin, then add 21 parts of diluent (PMA:MDBE weight ratio of 2:1), 5 parts of dispersant, 0.1 parts of defoamer, 17 parts of carbon black, and 7 parts of matting agent. Mechanically stir at 1200-1500 R / min for 20 min, then grind using a three-roll mill. When the fineness is less than 25 μm, remove the ground material, then add 12 parts of curing agent and 0.1 parts of drying agent. Mechanically stir at 800 R / min for 20 min to ensure uniform dispersion, then filter through a 200-mesh filter to obtain flexible low-reflection ink.

[0034] The inks prepared in the above examples and comparative examples were applied using two different methods. One method involved printing the inks onto a PC / ABS substrate using a 250-mesh polyester screen, baking at 100°C for 1 hour, and then performing performance testing on the resulting samples. The other method involved diluting the inks prepared in the examples and comparative examples by 5-10% with a thinner, then spraying them onto the PC / ABS substrate using an air spray gun, baking at 100°C for 1 hour to form a dry film thickness of 16-20 μm, and then performing performance testing on the resulting samples.

[0035] The coating was tested according to the following test methods.

[0036]

[0037] Table 1. Screen printing performance test parameters for each embodiment.

[0038] Table 2 Screen Printing Performance Tests for Each Comparative Example

[0039] Table 3. Spraying performance test parameters for each embodiment.

[0040] Table 4. Test parameters for spraying performance of each comparative example

[0041] The test results above show that the low-reflectivity ink provided by this invention has good adhesion and low reflectivity; it is simple to apply and has a wide range of choices. After 1250 hours of high temperature and humidity, thermal shock, and xenon lamp aging tests, the reflectivity of the coating still maintains good stability (Examples 1-5); with the addition of unmodified activated carbon, the reflectivity of the coating is high, and the adhesion decreases under long-term aging tests (Comparative Example 1); with the addition of activated carbon treated at high temperature in a nitrogen atmosphere but not modified with silane coupling agent, the reflectivity of the coating can be further reduced, but it does not have good compatibility in the system, and the adhesion decreases under long-term aging tests (Comparative Example 2); when the amount of modified activated carbon powder added is below the lower limit, the reflectivity of the coating is not reduced well (Comparative Example 3); when the amount of modified activated carbon powder added is above the upper limit, the viscosity of the ink increases and the mechanical properties of the coating decrease (Comparative Example 4); with the addition of modified activated carbon powder to the ink, compared with the addition of only high-pigment carbon black and matting powder, the reflectivity of the coating can be reduced better (Examples 1-5 and Comparative Example 5).

[0042] This invention improves the dispersibility and compatibility of activated carbon powder in the system by modifying it. The modified activated carbon powder can synergistically enhance the light absorption capacity of the coating with high-pigment carbon black, thereby reducing the reflectivity of the coating. In addition, the modified activated carbon further enhances its surface roughness, which can synergistically increase the microscopic uneven structure of the coating surface with matting powder, thereby reducing specular reflection and giving the coating a low and stable low reflectivity.

[0043] This embodiment is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may use the above content as inspiration to make changes or modifications to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications listed in the above embodiments that do not depart from the technical essence of the claims of the present invention shall still fall within the scope of protection of the claims of the present invention.

Claims

1. A low-reflection ink, characterized in that, Composed of, by weight, parts including: 33-38 parts of resin 18-24 parts diluent 5-8 parts of dispersant 9-12 parts carbon black 6-10 parts of modified activated carbon powder 3-5 parts matte powder Defoamer 0.1-0.5 parts 10-13 parts of curing agent Drying agent 0.1-0.3 parts.

2. The low-reflection ink according to claim 1, characterized in that, The preparation method of the modified activated carbon powder includes the following steps: (1) After thoroughly washing the activated carbon powder with deionized water, spread it evenly in a ceramic container, place it in a high-temperature tube furnace, heat it to 900-1000℃ at a rate of 3-5℃ / min under a nitrogen atmosphere with a flow rate of 30-40ml / min, keep it at the temperature for 2-4 hours, and then cool it naturally to room temperature. Then put the powder into distilled water to boil and vacuum dry it to obtain pretreated activated carbon powder. (2) Dissolve KH560 in a mixed solution of ethanol and deionized water, adjust the pH to 4-5 with acetic acid, and hydrolyze for 40-60 minutes; then add the pretreated activated carbon powder, stir at 60-80℃ for 6-8 hours, wash with anhydrous ethanol and deionized water until neutral after the reaction is completed; transfer to 80℃ for vacuum drying, and then dry at 120℃ to further remove the moisture and solvent from the modified activated carbon powder to obtain the modified activated carbon powder.

3. The low-reflection ink according to claim 2, characterized in that, The activated carbon powder is wood-based activated carbon powder with a mesh size of 2500-3000 mesh.

4. The low-reflection ink according to claim 2, characterized in that, The mass ratio of KH560, ethanol, and deionized water is 1:7~9:1~2.

5. The low-reflection ink according to claim 2, characterized in that, The mass ratio of KH560 to activated carbon powder is 1:3~5.

6. The method for preparing low-reflection ink according to claim 1, characterized in that, The resin used is a branched saturated polyester resin with a hydroxyl value of 45~55 mgKOH / g.

7. The method for preparing low-reflection ink according to claim 1, characterized in that, The drying agent is one of organotin drying agents or organobismuth drying agents.

8. The method for preparing low-reflection ink according to claim 1, characterized in that, The curing agent is a blocked hexamethylene diisocyanate trimer.

9. The method for preparing low-reflection ink according to claim 1, characterized in that, The dispersant is one of polyester-type polymeric dispersants or polyurethane-type polymeric dispersants.

10. A method for preparing a low-reflection ink as described in any one of claims 1-9, characterized in that, The process includes the following steps: After mixing and stirring the resin, diluent, dispersant, and defoamer evenly, add carbon black, matting powder, and modified activated carbon powder and stir. Grind the mixture until the fineness is less than 20μm, remove the ground material, add curing agent and drying agent, and stir for 10-20 minutes to disperse it evenly. After filtration, a low-reflection ink is obtained.

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