UV-moisture dual-curing silicon resin composition and preparation method thereof

Abstract

The invention relates to the technical field of organic silicon resin coatings, in particular to a UV-moisture dual-curing silicon resin composition and a preparation method thereof. The silicone resin composition comprises 90-100 parts of a silicone resin prepolymer; 5 to 25 parts of a silane coupling agent; 0.2 to 0.5 part of a coupling catalyst; 10 to 35 parts of a reactive diluent; 3-8 parts of a photoinitiator; 0-2 parts of a flatting agent and 0-2 parts of a defoaming agent. According to the dual-curing silicon resin composition disclosed by the invention, two mechanisms of ultraviolet curing and moisture curing are combined, so that the problems of low curing speed and high VOC (Volatile Organic Compounds) content of a traditional moisture-curing silicon resin coating are solved, and the dual-curing silicon resin composition is suitable for scenes with relatively high requirements on environmental adaptability and environmental protection, such as consumer electronics, automobiles, aerospace and medical treatment.

Description

Technical Field

[0001] This invention relates to the field of organosilicon resin coating technology, specifically to a UV-moisture dual-curing silicone resin composition and its preparation method. Background Technology

[0002] Silicone resin coatings, due to their resistance to high and low temperatures (-60℃ to 200℃), waterproofing (IP67 / IP68 rating), chemical corrosion resistance, and environmental friendliness, have become core materials in consumer electronics (approximately 45%), automotive industry (approximately 20%), aerospace, and medical fields. Although silicone resins possess excellent weather resistance, temperature resistance, and chemical corrosion resistance, their development as a base material for UV coatings is challenging due to the unique molecular structure. Currently, the curing of silicone resins largely relies on moisture. Moisture curing is suitable for complex structures, can penetrate areas with insufficient light, such as crevices, and can achieve full curing of multi-layered and thick materials. Furthermore, it requires no additional heating or UV equipment, making it energy-saving, environmentally friendly, and cost-effective. However, existing moisture-cured silicone resin products have the following drawbacks: 1. Slow curing speed: Traditional moisture curing relies on the reaction between moisture in the air and active groups in the resin (such as NCO or Si-OH), and the curing process takes several hours to several days, severely impacting processing efficiency. 2. High VOC content: Traditional products that use organic solvents such as toluene as dispersion media (such as the company's existing product 9277) release a large amount of volatile organic compounds (VOCs) during construction and curing, posing safety hazards and violating increasingly stringent environmental protection policies.

[0003] The market demand for high-performance, environmentally friendly curing resins is growing, especially in the consumer electronics and automotive sectors, where customers are placing higher demands on weather resistance, curing speed, and environmental friendliness. UV-moisture dual-curing mechanisms can effectively meet these requirements.

[0004] UV curing enables rapid surface drying and setting. Under UV light, surface curing can be achieved within seconds to tens of seconds, significantly shortening production time (such as in assembly lines for electronic components) and avoiding the problem of "prolonged uncured and prone to displacement" that occurs with moisture curing alone. Moisture curing can achieve complete curing of deep / shaded areas: For thick coatings (>500μm) that UV cannot penetrate, and shaded areas of complex structures (such as connector gaps), moisture curing can achieve complete cross-linking by reacting with moisture in the air, avoiding the defects of insufficient strength and poor weather resistance caused by "dry surface, uncured interior" in UV curing alone.

[0005] Existing UV curing technologies for silicone resins are mainly based on acrylic or polyurethane systems, and dual-curing products combining both have not yet been widely developed and promoted. For example, the patent application filed by Guangdong Jinhongtai Chemical New Materials Co., Ltd. for LED-moisture dual-curing silicone-modified hyperbranched polyurethane acrylic resin (CN 120118271 A) involves silicone modification, but mainly uses polyurethane acrylate as the matrix, and has not fully broken through the deep integration of silicone resin and UV curing technology. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a UV-moisture dual-curing silicone resin composition and its preparation method, so as to solve the problems of slow curing speed and high VOC content of traditional moisture-curing silicone resin, while retaining its temperature resistance, waterproof and corrosion resistance properties, and meeting the requirements of high-demand scenarios for processing efficiency and environmental protection.

[0007] A UV-moisture dual-curing silicone resin composition of the present invention comprises the following components in parts by weight:

[0008] 90-100 parts of silicone resin prepolymer;

[0009] 5-20 parts of silane coupling agent;

[0010] 0.2-0.5 parts of coupling catalyst;

[0011] 10-40 parts of reactive diluent;

[0012] 3-5 parts of photoinitiator;

[0013] Leveling agent 0-2 parts;

[0014] 0-2 parts of defoamer.

[0015] The silane coupling agent is preferably γ-methacryloyloxypropylalkoxysilane, which is used as an introducer of UV-curable functional groups.

[0016] The coupling catalyst is a phthalate ester or an organotin compound.

[0017] The active diluent is an acrylate monomer, such as isobornyl acrylate.

[0018] The photoinitiator is one or more of acylphosphine oxides and α-hydroxy ketone derivatives, such as ethyl 2,4,6-trimethylbenzoylphosphonate and 2-hydroxy-2-methylphenylacetone.

[0019] This invention also provides a method for preparing a UV-moisture dual-curing silicone resin composition, comprising the following steps: 1) Synthesis of silicone resin prepolymer.

[0020] Phenylalkoxysilane, water, and toluene solvent are added to a reaction vessel, and the reaction is carried out at 30-70°C for 2-6 hours under the action of an acid catalyst.

[0021] After hydrolysis, methanol and excess water generated during the reaction are removed by layered water washing or toluene reflux.

[0022] Hydroxyl silicone oil was added to the toluene-containing phenylsilane hydrolysate, and an acid catalyst was added. The polycondensation reaction was carried out at a temperature of 30~70℃. Then, the temperature was raised and the water was separated by reflux at the toluene reflux temperature to obtain a prepolymer containing toluene solvent.

[0023] 2) Silane coupling agent end capping

[0024] γ-methacryloxypropylalkoxysilane was added to the prepolymer system, along with a coupling catalyst, to complete the end-capping reaction and form a moisture-curing silicone resin intermediate containing UV-curable groups.

[0025] 3) Solvent removal and UV-moisture dual-curing silicone resin formulation

[0026] Toluene solvent in the prepolymer is removed by physical methods to reduce VOC content; reactive diluent and photoinitiator are added to the system after solvent removal, and auxiliary agents are added as needed to achieve leveling and bubble-free coating.

[0027] In step 1), the acid catalyst can be sulfuric acid, p-toluenesulfonic acid, or hydrochloric acid.

[0028] In step 3), the physical method includes vacuum distillation or low-temperature evaporation. The additives include leveling agents and / or defoamers.

[0029] The dual-curing silicone resin composition of the present invention solves the problems of slow curing speed and high VOC content of traditional moisture-curing silicone resin coatings by combining ultraviolet light curing and moisture curing mechanisms. It is suitable for scenarios with high environmental adaptability and environmental protection requirements, such as consumer electronics, automobiles, aerospace and medical.

[0030] The beneficial effects of this invention are as follows:

[0031] 1. Dual Curing Characteristics: Through the synergistic effect of UV curing and moisture curing, initial curing can be achieved in 10-30 seconds under 365-405nm UV light irradiation, followed by further cross-linking through moisture, significantly improving processing efficiency. 2. Environmental Performance: Through solvent removal process, VOC content is significantly reduced (below national standard limits), meeting customers' requirements for safety and environmental protection. 3. Superior Performance: Retains the original moisture-cured product's resistance to high and low temperatures (-60℃ to 200℃), waterproofing (IP67 / IP68), and chemical corrosion resistance, and further enhances the physical and mechanical properties of the coating (such as tensile strength and adhesion) through UV modification. Detailed Implementation Method

[0032] The present invention aims to develop an organosilicon resin product that combines UV rapid curing and moisture-assisted crosslinking, thereby solving the problems of slow curing speed and high VOC content of traditional moisture-curing silicone resins.

[0033] The following describes the implementation of the present invention with specific steps: Example 1 Synthesis of silicone resin prepolymer:

[0034] 100 parts of phenyltrimethoxysilane, 55 parts of water and an appropriate amount of toluene were added to the reaction vessel, and 0.05 parts of hydrochloric acid were added as an acid catalyst. The reaction temperature was controlled at 30~70℃, and hydrolysis was carried out for 4 hours.

[0035] The temperature was raised to 110°C, and methanol and excess water were removed by reflux of toluene to obtain the preliminary polycondensation product.

[0036] Add 90 parts of hydroxyl silicone oil and 0.03 parts of hydrochloric acid, continue polycondensation at 30~90℃ for 4~12 hours, and then reflux at the toluene reflux temperature to remove water, to obtain prepolymer 1 containing toluene solvent.

[0037] Example 2: Synthesis of silicone resin prepolymer:

[0038] 100 parts of phenyltrimethoxysilane, 75 parts of water and an appropriate amount of toluene were added to a reaction vessel, and 0.005 parts of sulfuric acid were added as an acid catalyst. The reaction temperature was controlled at 30~70℃, and hydrolysis was carried out for 4 hours. After standing and settling, methanol and excess water were removed, and the mixture was washed with water 2~3 times to obtain the preliminary polycondensation product.

[0039] Add 70 parts of hydroxyl silicone oil and 0.3 parts of hydrochloric acid, continue polycondensation at 30~90℃ for 4~12 hours, and then reflux at the toluene reflux temperature to remove water, to obtain prepolymer 2 containing toluene solvent.

[0040] Example 3: Silane coupling agent end-capping:

[0041] Add 15 parts of γ-methacryloxypropyltrimethoxysilane and 0.4 parts of tetrabutyl titanate to prepolymer 1, react at 80°C for 2 hours to complete end-capping, forming a UV-moisture dual-curing silicone resin intermediate. Remove toluene solvent under vacuum conditions, add 5-10 parts of reactive diluent isobornyl acrylate, 3-5 parts of photoinitiator ethyl 2,4,6-trimethylbenzoylphosphonate, 0-3 parts of 2-hydroxy-2-methylphenylacetone, 0.1-1 parts of leveling agent-polyether modified polysiloxane, and 0.1-0.5 parts of defoamer methyl silicone oil to obtain UV-1 UV-moisture dual-curing silicone resin coating.

[0042] Example 4: Silane coupling agent end-capping:

[0043] 20 parts of γ-methacryloxypropylmethyldimethoxysilane and 0.2 parts of isopropyl titanate were added to prepolymer 1 and reacted at 80°C for 2 hours to complete end-capping, forming a UV-moisture dual-curing silicone resin intermediate. Toluene solvent was removed under vacuum conditions, and 5-10 parts of reactive diluent isobornyl acrylate, 3-6 parts of photoinitiator 2,4,6-(trimethylbenzoyl)diphenylphosphine oxide, 0.1-1 parts of leveling agent polyether-modified polysiloxane, and 0.1-0.5 parts of defoamer methyl silicone oil were added to obtain UV-2 UV-moisture dual-curing silicone resin coating.

[0044] Example 5: Silane coupling agent end-capping:

[0045] Add 25 parts of γ-methacryloxypropyltrimethoxysilane and 0.2 parts of tetrabutyltin dilaurate to prepolymer 2, react at 90℃ for 4 hours to complete end-capping, forming a UV-moisture dual-curing silicone resin intermediate. Remove toluene solvent under vacuum conditions, add 5-10 parts of reactive diluent isobornyl acrylate, 2-5 parts of photoinitiator 2,4,6(trimethylbenzoyl)diphenylphosphine oxide, 0-3 parts of 1-hydroxy-cyclohexylbenzophenone, 0.1-1 parts of leveling agent polyether-modified polysiloxane, and 0.1-0.5 parts of defoamer methyl silicone oil to obtain UV-3 UV-moisture dual-curing silicone resin coating.

[0046] Example 6: Silane coupling agent end-capping:

[0047] 20 parts of γ-methacryloxypropyltrimethoxysilane and 0.2 parts of tetrabutyl titanate were added to prepolymer 2 and reacted at 90°C for 4 hours to complete end-capping, forming a UV-moisture dual-curing silicone resin intermediate. Toluene solvent was removed under vacuum conditions, and 5-10 parts of reactive diluent isobornyl acrylate, 3-6 parts of photoinitiator 2-hydroxy-2-methylphenylacetone, 0.1-1 parts of leveling agent polyether-modified polysiloxane, and 0.1-0.5 parts of defoamer methyl silicone oil were added to obtain UV-4 UV-moisture dual-curing silicone resin coating.

[0048] Table 1 shows the UV moisture-curing dual-curing silicone resin coatings prepared in each example and their coating performance.

[0049] Example Curing time (s) Impact strength (cm) Non-volatile content % Adhesion level Thermal shock -60~150℃ / 1000 cycles Salt spray test: 5% salt spray, 168h UV-1 15 80 98.1 0 pass pass UV-2 12 85 97.8 0 pass pass UV-3 15 90 98.2 0 pass pass UV-4 15 90 98.5 0 pass pass

[0050] The UV moisture dual-curing silicone resin coating prepared above was tested in accordance with the standard "Conformal Coating Materials for Printed Circuit Board Assemblies" (TCSTM 00920-2023), and the test results are shown in Table 1.

Claims

1. A UV-moisture dual-curing silicone resin composition, characterized in that, It contains the following ingredients by weight: 90-100 parts of silicone resin prepolymer; 5-20 parts of silane coupling agent; 0.2-0.5 parts of coupling catalyst; 10-40 parts of reactive diluent; 3-5 parts of photoinitiator; Leveling agent 0-2 parts; 0-2 parts of defoamer.

2. The silicone resin composition according to claim 1, characterized in that, The silane coupling agent used is γ-methacryloxypropylalkoxysilane.

3. The silicone resin composition according to claim 1, characterized in that, The coupling catalyst is a phthalate ester or an organotin compound.

4. The silicone resin composition according to claim 1, characterized in that, The active diluent is one or more of the following: isobornyl acrylate, tripropylene glycol diacrylate, pentaerythritol triacrylate, and 1,6-hexanediol diacrylate.

5. The silicone resin composition according to claim 1, characterized in that, The photoinitiator is one or more of acylphosphine oxides and α-hydroxy ketone derivatives.

6. The method for preparing the UV-moisture dual-curing silicone resin composition according to claim 1, characterized in that, Includes the following steps: 1) Synthesis of silicone resin prepolymer Phenylalkoxysilane, water, and toluene solvent are added to a reaction vessel and hydrolyzed at 30-70°C for 2-6 hours under the action of an acid catalyst. After hydrolysis, methanol and excess water generated during the reaction are removed by layered water washing or toluene reflux. Hydroxyl silicone oil was added to the toluene-containing phenylsilane hydrolysate, and an acid catalyst was added. The polycondensation reaction was carried out at a temperature of 30~70℃. Then, the temperature was raised and the water was separated by reflux at the toluene reflux temperature to obtain a prepolymer containing toluene solvent. 2) Silane coupling agent end capping γ-methacryloxypropylalkoxysilane was added to the prepolymer system, along with a coupling catalyst, to complete the end-capping reaction and form a moisture-curing silicone resin intermediate containing UV-curable groups. 3) Solvent removal and UV-moisture dual-curing silicone resin formulation Toluene solvent in the prepolymer is removed by physical methods to reduce VOC content; reactive diluent and photoinitiator are added to the system after solvent removal, and auxiliary agents are added as needed to achieve leveling and bubble-free coating.

7. The preparation method according to claim 6, characterized in that, In step 1), the acid catalyst is sulfuric acid, p-toluenesulfonic acid, or hydrochloric acid.

8. The preparation method according to claim 6, characterized in that, In step 3), the physical method includes vacuum distillation or low-temperature evaporation.

9. The preparation method according to claim 6, characterized in that, The additives include leveling agents and / or defoamers.