Alkali developing ultraviolet curing resin and preparation method thereof

Abstract

The invention provides alkali developing ultraviolet curing resin which is composed of methacrylic acid, acrylic ester, ethyl p-dimethylaminobenzoate, o-nitrophenol, barium sulfate, alcohol with the carbon molecule number of 2-5 and acetic acid, and the molar mass ratio of methacrylic acid to acrylic ester to ethyl p-dimethylaminobenzoate to o-nitrophenol is 20: (2-5): (8-12): (6-8). The weight of the barium sulfate accounts for 0.3-1.2% of the weight of the cured resin, and the molar mass ratio of the alcohol with 2-5 carbon molecules to the acetic acid is 10: (1-3). According to the invention, all the organic components can be polymerized, the viscosity of the final cured resin is controlled by evaporating alcohols, the operation is easy, and in addition, the barium sulfate is obtained by interface reaction, and the particles of the barium sulfate are small, so that the production requirement of the cured resin is met.

Description

Technical Field

[0001] The present invention relates to the technical field of ultraviolet curing resins, in particular to an alkali-developable ultraviolet curing resin and a preparation method thereof. Background Art

[0002] Alkali-developable UV-curable resin is a specialized photosensitive resin primarily used in photoresists and solder masks for printed circuit boards (PCBs) in electronic device manufacturing. It combines alkali-developable performance with UV-curable properties, making it suitable for high-precision patterning processes.

[0003] The viscosity of alkali-developable UV-curable resins is determined by the selected resin matrix. Reactive diluents, fillers, and additives can also be added to alter the final viscosity. The molecular weight or molecular length of the resin matrix directly influences its viscosity. Modifying the viscosity through the use of reactive diluents, fillers, and additives inevitably affects the crosslinking reaction of the resin matrix in the presence of a photopolymerization initiator. Summary of the Invention

[0004] To solve the above problems, the present invention discloses an alkali-developable UV-curable resin, which is composed of methacrylic acid, acrylate, ethyl p-dimethylaminobenzoate, o-nitrophenol, barium sulfate, alcohols with 2 to 5 carbon molecules, and acetic acid.

[0005] The alcohol can be selected from ethanol, propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl-2-butanol, and 2,2-dimethyl-1-propanol.

[0006] The molar mass ratio of methacrylic acid, acrylate, ethyl p-dimethylaminobenzoate, and o-nitrophenol is 20:2 to 5:8 to 12:6 to 8. Methacrylic acid is a commonly used alkali-soluble copolymer in alkali-developable UV-curable resins, while the carboxyl-containing unsaturated monomer provides developability. Ethyl p-dimethylaminobenzoate acts as a photopolymerization initiator, promoting the UV-curing reaction. Acrylate and o-nitrophenol, multifunctional monomers, enhance crosslinking density and improve mechanical properties.

[0007] The barium sulfate accounts for 0.3-1.2% of the weight of the curing resin. The barium sulfate is an inorganic filler and improves heat resistance and crack resistance.

[0008] The molar mass ratio of the alcohol with 2 to 5 carbon atoms to acetic acid is 10:1 to 3. The alcohol with 2 to 5 carbon atoms and acetic acid are used to control the fluidity of the cured resin. The alcohol with 2 to 5 carbon atoms and acetic acid can provide hydroxyl groups and carboxyl groups, respectively, and can also serve as polymerization monomers.

[0009] Preferably, the curing resin is treated with acetic acid and an alcohol having 2 to 5 carbon atoms, and its viscosity is less than 3000 mPa·s. Alcohols of appropriate molecular weight can be selected based on the desired viscosity of the product. Theoretically, the lower the viscosity, the smaller the molecular weight of the selected alcohol.

[0010] A method for preparing an alkali-developable ultraviolet-curable resin comprises the following steps: Preparation of component A: methacrylic acid, acrylic acid ester, alcohol with a carbon molecule number of 2 to 5, and acetic acid are placed in a container and stirred uniformly to obtain component A; Preparation of component B: (1) Heat ethyl p-dimethylaminobenzoate and o-nitrophenol in a container until they become liquid and dissolve in each other and keep warm; (2) Heat deionized water and dissolve barium chloride, then add it to the ethyl p-dimethylaminobenzoate and o-nitrophenol solution, and then let it stand for stratification; (3) Stir the upper layer slowly and add concentrated sulfuric acid dropwise; (4) After the addition of concentrated sulfuric acid is completed, the solution is allowed to stand, and no less than three-quarters of the water is removed from the water layer. Deionized water is then added, and the entire solution in the container is stirred. After the solution is allowed to stand and separate, all the water is removed to obtain component B. Preparation of curing resin: (1) heating component A and mixing with component B at an isothermal temperature to obtain a mixed system; (2) The mixed system is stirred and further heated to evaporate the alcohol having 2 to 5 carbon molecules, and a mixed system having a preset viscosity is obtained to obtain the cured resin.

[0011] Preferably, the heating temperature range of ethyl p-dimethylaminobenzoate and o-nitrophenol is 60° C. to 70° C.

[0012] Preferably, the temperature at which the mixed system is further heated is not less than 90°C.

[0013] Preferably, the prepared curing resin needs to be kept at a temperature not completely cooled, at a vacuum degree of 20 to 60%, and without boiling the alcohol having 2 to 5 carbon atoms, for more than 10 minutes.

[0014] The beneficial effects of the present invention are as follows: 1. It is composed of methacrylic acid, acrylate, ethyl p-dimethylaminobenzoate, o-nitrophenol, barium sulfate, alcohols with a carbon molecule number of 2 to 5 and acetic acid. The organic components can polymerize with each other, and the control of the alcohol content can control the final viscosity of the cured resin without the need for other diluents, fillers and additives.

[0015] 2. During the preparation of the curing resin, barium sulfate can avoid the problem of excessively large barium sulfate particles through interfacial reaction, thus meeting the needs of use. DETAILED DESCRIPTION

[0016] The present invention will be further explained below in conjunction with specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Example

[0017] An alkali-developable ultraviolet curing resin is composed of methacrylic acid, acrylate, ethyl p-dimethylaminobenzoate, o-nitrophenol, barium sulfate, alcohols with 2 to 5 carbon molecules and acetic acid.

[0018] The alcohol can be selected from ethanol, propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl-2-butanol, and 2,2-dimethyl-1-propanol.

[0019] The molar mass ratio of methacrylic acid, acrylate, ethyl p-dimethylaminobenzoate, and o-nitrophenol is 20:2 to 5:8 to 12:6 to 8. Methacrylic acid is a commonly used alkali-soluble copolymer in alkali-developable UV-curable resins, while the carboxyl-containing unsaturated monomer provides developability. Ethyl p-dimethylaminobenzoate acts as a photopolymerization initiator, promoting the UV-curing reaction. Acrylate and o-nitrophenol, multifunctional monomers, enhance crosslinking density and improve mechanical properties.

[0020] The barium sulfate accounts for 0.3-1.2% of the weight of the curing resin. The barium sulfate is an inorganic filler and improves heat resistance and crack resistance.

[0021] The molar mass ratio of the alcohol with 2 to 5 carbon atoms to acetic acid is 10:1 to 3. The alcohol with 2 to 5 carbon atoms and acetic acid are used to control the fluidity of the cured resin. The alcohol with 2 to 5 carbon atoms and acetic acid can provide hydroxyl groups and carboxyl groups, respectively, and can also serve as polymerization monomers.

[0022] The curing resin is treated with acetic acid and evaporates alcohols with 2-5 carbon atoms, resulting in a viscosity of less than 3000 mPa·s. Alcohols with appropriate molecular weights can be selected based on the product's desired viscosity. Theoretically, the lower the viscosity, the smaller the molecular weight of the selected alcohol. Example

[0023] A method for preparing an alkali-developable ultraviolet-curable resin comprises the following steps: Preparation of component A: methacrylic acid, acrylic acid ester, alcohol with a carbon molecule number of 2 to 5, and acetic acid are placed in a container and stirred uniformly to obtain component A; Preparation of component B: (1) ethyl p-dimethylaminobenzoate and o-nitrophenol in a container are heated to liquid form and mutually dissolved and kept warm. The melting point of ethyl p-dimethylaminobenzoate is 63-66°C, and the melting point of o-nitrophenol is 43-45°C. Therefore, at room temperature, the mutual dissolution of the two can be achieved by heating; (2) Heat deionized water and dissolve barium chloride, then add it to the solution of ethyl p-dimethylaminobenzoate and o-nitrophenol, and then stand for stratification. The heating temperature of the deionized water is not lower than the temperature at which ethyl p-dimethylaminobenzoate and o-nitrophenol are mutually dissolved. After stratification, ethyl p-dimethylaminobenzoate and o-nitrophenol are located in the upper layer, while a small amount of o-nitrophenol is dissolved in the water. (3) Slowly stir the upper layer and add concentrated sulfuric acid dropwise. The concentrated sulfuric acid is dissolved in ethyl p-dimethylaminobenzoate and o-nitrophenol. During the stirring process, the concentrated sulfuric acid and barium chloride react at the interface between the upper and lower layers to produce barium sulfate precipitation. Since the reaction occurs at the interface, the barium sulfate particles are prevented from being too large. (4) After the addition of concentrated sulfuric acid is completed, the mixture is allowed to stand and no less than three-quarters of the water is extracted from the water layer. The water after the reaction contains sulfuric acid and hydrochloric acid. By removing most of the water, that is, removing the sulfuric acid and hydrochloric acid, and then adding deionized water, the entire solution in the container is stirred to dissolve the sulfuric acid and hydrochloric acid in the entire container into the deionized water. After standing and stratifying, all the water is extracted to obtain component B. The sulfuric acid and hydrochloric acid remaining in component B can be used as pH regulators; Preparation of curing resin: (1) heating component A and mixing with component B at an isothermal temperature to obtain a mixed system; (2) The mixed system is stirred and further heated to evaporate the alcohol having 2 to 5 carbon molecules, and a mixed system having a predetermined viscosity is obtained, which is the cured resin. During the heating and evaporation of the alcohol, the mixed system is stirred continuously.

[0024] Preferably, the heating temperature of ethyl p-dimethylaminobenzoate and o-nitrophenol is in the range of 60° C. to 70° C. This allows ethyl p-dimethylaminobenzoate and o-nitrophenol to melt while preventing o-nitrophenol from being overheated and decomposed.

[0025] Preferably, the mixed system is further heated to a temperature not lower than 90° C., so that the alcohol evaporates quickly, thereby obtaining a cured resin.

[0026] Preferably, the prepared curing resin needs to be kept at a temperature of 20-60% vacuum, without completely cooling down, and without boiling the alcohol having 2-5 carbon atoms, for at least 10 minutes. The degree of vacuum can be adjusted based on the current temperature of the curing resin to avoid excessive vacuum, which may cause boiling of the alcohol and result in significant loss of alcohol and poor bubble removal.

[0027] Furthermore, if there is a requirement for the acid value of the cured resin, step (4) of component B can be modified and specifically replaced with the following content: after the addition of concentrated sulfuric acid is completed, the mixture is allowed to stand and the upper layer of liquid is extracted for acidity testing. If the acidity is too low, concentrated sulfuric acid or acetic acid is continued to be added. If the acidity is too high, hydroxide can be added for balance, or deionized water can be added to dissolve more acid in the upper layer of liquid in water. In addition, in step (2) of preparing the cured resin, the mixture can be tested again and the acidity can be adjusted.

[0028] The technical means disclosed in the solution of the present invention are not limited to the technical means disclosed in the above-mentioned embodiment, but also include technical solutions composed of any combination of the above technical features.

Claims

1. An alkali-developable UV-curable resin, characterized in that: It is composed of methacrylic acid, acrylic acid ester, ethyl p-dimethylaminobenzoate, o-nitrophenol, barium sulfate, alcohols with 2 to 5 carbon molecules and acetic acid; The molar mass ratio of methacrylic acid, acrylic acid ester, ethyl p-dimethylaminobenzoate and o-nitrophenol is 20:2-5:8-12:6-8; Barium sulfate accounts for 0.3 to 1.2% by weight of the curing resin; The molar mass ratio between the alcohol having 2 to 5 carbon molecules and acetic acid is 10:1 to 3.

2. The alkali-developable UV-curable resin according to claim 1, wherein: The curable resin is treated by evaporating alcohols with 2 to 5 carbon molecules and acetic acid, and has a viscosity of less than 3000 mPa·s.

3. A method for preparing an alkali-developable UV-curable resin, according to any one of claims 1 to 2, characterized in that: Includes the following: Preparation of component A: methacrylic acid, acrylic acid ester, alcohol with a carbon molecule number of 2 to 5, and acetic acid are placed in a container and stirred uniformly to obtain component A; Preparation of component B: (1) Heat ethyl p-dimethylaminobenzoate and o-nitrophenol in a container until they become liquid and dissolve in each other and keep warm; (2) Heat deionized water and dissolve barium chloride, then add it to the ethyl p-dimethylaminobenzoate and o-nitrophenol solution, and then let it stand for stratification; (3) Stir the upper layer slowly and add concentrated sulfuric acid dropwise; (4) After the addition of concentrated sulfuric acid is completed, the solution is allowed to stand, and no less than three-quarters of the water is removed from the water layer. Deionized water is then added, and the entire solution in the container is stirred. After the solution is allowed to stand and separate, all the water is removed to obtain component B. Preparation of curing resin: (1) heating component A and mixing with component B at an isothermal temperature to obtain a mixed system; (2) The mixed system is stirred and further heated to evaporate the alcohol having 2 to 5 carbon molecules, and a mixed system having a preset viscosity is obtained to obtain the cured resin.

4. The method for preparing an alkali-developable UV-curable resin according to claim 3, wherein: The heating temperature range of ethyl p-dimethylaminobenzoate and o-nitrophenol is 60℃~70℃.

5. The method for preparing an alkali-developable ultraviolet curable resin according to claim 3, wherein: The temperature of the mixed system is further heated to not less than 90°C.

6. The method for preparing an alkali-developable ultraviolet curable resin according to claim 3, wherein: The prepared curing resin needs to be kept at a temperature of not completely cooled, at a vacuum degree of 20 to 60%, and without boiling the alcohol having 2 to 5 carbon molecules, for more than 10 minutes.