One-component UV fast curing silicone gasket adhesive and preparation method thereof

Abstract

The application relates to the technical field of silicone sealing materials, and particularly discloses a single-component UV rapid curing silicone gasket adhesive and a preparation method thereof. The gasket adhesive contains, in parts by mass, 50-70 parts of end-vinyl polydimethylsiloxane, 10-20 parts of hydrogen-containing silicone oil, 3-8 parts of vinyl MQ silicone resin, 5-15 parts of low-viscosity vinyl silicone oil, 8-15 parts of hydrophobic fumed white carbon black, 0.8-1.5 parts of a photoinitiator, 0.02-0.1 parts of a platinum-based catalyst, 0.5-1.5 parts of a silane coupling agent, 0.02-0.1 parts of an alkyne alcohol inhibitor and 0.1-0.5 parts of a functional additive. The low-viscosity vinyl silicone oil has a viscosity of 50-100 mPa.s at 25 DEG C, and a vinyl content of 0.2-0.5 mmol / g. The gasket adhesive has the advantages of stable storage for more than 6 months under the condition of light avoidance at-10 DEG C to 5 DEG C, UV second-level rapid curing, excellent mechanical properties and sealing performance after curing, and can be widely applied to the sealing and gasket forming of electronic appliances, automobile parts, household appliances and the like.

Description

Technical Field

[0001] This invention relates to the field of silicone sealing materials technology, specifically to a single-component UV-curable silicone gasket adhesive and its preparation method. Background Technology

[0002] Silicone gaskets, due to their excellent weather resistance, high and low temperature resistance, and low compression set, have become a core material for sealing and gasket molding in the electronics, automotive, and home appliance industries. Currently, silicone gaskets are mainly based on two-component addition-curing silicone rubber. These products require on-site mixing, which can easily introduce air bubbles leading to sealing failure. Furthermore, they rely on platinum catalysts for curing at temperatures above 80°C, resulting in high energy consumption and stringent requirements for equipment temperature control accuracy. Additionally, they are prone to catalyst deactivation and premature cross-linking, affecting product quality and production efficiency.

[0003] To address the shortcomings of two-component systems, the industry has begun developing single-component UV-curable silicone rubbers. However, existing single-component products still suffer from several key technical defects: First, conventional photoinitiators often contain phosphorus, sulfur, and nitrogen heteroatoms, which can easily coordinate with platinum-based catalysts, causing poisoning and deactivation, resulting in incomplete curing and a sharp reduction in product shelf life. Second, they lack sealing and adhesion properties, exhibiting poor adhesion to commonly used substrates such as metals and engineering plastics, failing to meet actual sealing requirements. Third, they exhibit poor low-temperature storage stability, making them unsuitable for the requirements of long-term industrial storage and transportation.

[0004] UV-activated platinum-based catalysts are the preferred catalytic system for one-component UV-cured silicone rubbers. However, their compatibility with photoinitiators and the control of low-temperature stability remain technical challenges in this field. Currently, there are no mature one-component products that effectively combine UV-activated platinum-based catalysts with rapid UV curing, long-term low-temperature storage, and excellent adhesion. Therefore, developing a one-component silicone gasket adhesive that is free from catalyst poisoning, stable at low temperatures, rapidly cures under UV light, and exhibits excellent adhesion has significant industrial application value for promoting the automated production of silicone sealing materials. Summary of the Invention

[0005] To address the shortcomings of existing technologies, such as the need for mixing and high-temperature curing of two-component addition-curing silicone rubber, which places high demands on equipment, and the poisoning of platinum catalysts by photoinitiators, short shelf life, and poor adhesion of one-component UV-cured silicone rubber, this invention provides a one-component UV-curable silicone gasket adhesive and its preparation method. This invention enables long-term stable storage at -10~5℃ in the dark and allows for second-level rapid curing under 365nm UV light. Simultaneously, it ensures that the cured product possesses excellent adhesion, mechanical properties, and sealing performance. Furthermore, the preparation process is simple and suitable for industrial production.

[0006] To achieve this objective, the present invention employs the following technical solution: A single-component UV-curable silicone gasket adhesive, by weight, comprises the following components: 50-70 parts of vinyl-terminated polydimethylsiloxane, 10-20 parts of hydrogen-containing silicone oil, 3-8 parts of vinyl MQ silicone resin, 5-15 parts of low-viscosity vinyl silicone oil, 8-15 parts of hydrophobic fumed silica, 0.8-1.5 parts of photoinitiator, 0.02-0.1 parts of platinum-based catalyst, 0.5-1.5 parts of silane coupling agent, 0.02-0.1 parts of alkynyl alcohol inhibitor, and 0.1-0.5 parts of functional additives; The low-viscosity vinyl silicone oil has a viscosity of 50-100 mPa·s at 25°C and a vinyl content of 0.2-0.5 mmol / g.

[0007] This invention relates to an organosilicon gasket adhesive composed of vinyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, and vinyl MQ silicone resin, etc., in parts by weight. The precise combination and synergistic design of a platinum-based catalyst and an alkynyl alcohol inhibitor are key. The platinum-based catalyst is a UV-activated latent catalyst, serving as the core catalytic unit for the hydrosilylation reaction. It is compatible with the system components and exhibits no coordination poisoning. The alkynyl alcohol inhibitor is added in equal proportions, crucial for the system's low-temperature stability, and the two form a stable complex. The alkynyl alcohol inhibitor shields the platinum-based catalyst at room temperature and low temperatures of -10 to 5°C, preventing premature cross-linking of the system. Upon irradiation with 365nm UV light, the complex structure rapidly dissociates, activating the platinum-based catalyst and triggering the hydrosilylation reaction for rapid curing. Furthermore, the catalyst and photoinitiator interact solely through energy transfer, without chemical poisoning. The solution ultimately produces a single-component product that can be used directly. It can be surface-dried by 365nm UV light irradiation for 20~60s, and can be stored at -10~5℃ in the dark for ≥6 months without crystallization, pre-crosslinking, or viscosity change. At the same time, the catalytic system is not deactivated and is completely cured, taking into account excellent mechanical, sealing and adhesive properties, and is suitable for the needs of industrialized automated production.

[0008] Optionally, the alkynol inhibitors include one or more of ethynylcyclohexanol and methylbutynol.

[0009] Optionally, the platinum-based catalyst includes one or more of UV-Pt100 and UV-Pt500.

[0010] Optionally, the vinyl-terminated polydimethylsiloxane has a viscosity of 50,000-80,000 mPa·s at 25°C and a vinyl content of 0.02-0.1 mmol / g.

[0011] Optionally, the end-vinyl polydimethylsiloxane contains silica, and the silica content is 22-28 wt%.

[0012] Optionally, the hydrogen-containing silicone oil includes end-capped hydrogen-containing silicone oil and highly active end-side hydrogen-containing silicone oil, with a mass ratio of (5-6):1.

[0013] Optionally, the photoinitiator comprises phenyltrimethylsiloxane and vinylphenylsiloxane in a mass ratio of 1:(2-3).

[0014] Optionally, the silane coupling agent comprises methacryloyloxypropyltrimethoxysilane and γ-epoxypropoxypropyltrimethoxysilane in a mass ratio of (3-5):1.

[0015] Optionally, the functional additives include hindered phenolic antiyellowing agents and polyether-modified silicone defoamers, with a mass ratio of (0.5-1.5):(0.5-1.5).

[0016] On the other hand, the present invention also provides a method for preparing a one-component UV-curable silicone gasket adhesive, comprising the following steps: (1) Under light-protected conditions and at 10~20℃, 2.5-7.5 parts by weight of low viscosity vinyl silicone oil, the photoinitiator, the inhibitor and the platinum-based catalyst are mixed and stirred at 300~500 r / min for 10~20 min to obtain a photocurable system; (2) Mix the terminal vinyl polydimethylsiloxane, the remaining low viscosity vinyl silicone oil and the vinyl MQ silicone resin, and stir at 20~35°C and 500~800 r / min for 30~60 min; under light-protected conditions, add the hydrogen-containing silicone oil, the silane coupling agent and the functional additive, and stir at 400~600 r / min for 15~30 min to obtain the basic system; (3) Add the hydrophobic fumed silica to the basic system, stir at 600~800 r / min for 15~30 min, and degas under vacuum to obtain the degassed system; (4) Mix the photocuring system and the degassed system, stir at 200~300r / min for 15~30min, and degassed under vacuum to obtain the silicone gasket adhesive.

[0017] Beneficial effects 1. This invention uses alkynyl alcohol inhibitors such as ethynylcyclohexanol and methylbutynol, which can form stable complexes with platinum-based catalysts. Under light-proof and sealed conditions of -10~5℃, it can be stably stored for ≥6 months without crystallization, pre-crosslinking, or viscosity abrupt change, and its performance remains stable during storage.

[0018] 2. This invention uses a silicon-based aromatic ketone composite photoinitiator free of phosphorus, sulfur, and nitrogen heteroatoms. It only undergoes energy transfer activation with the UV-activated platinum-based catalyst, without coordination poisoning or chemical interaction, thus avoiding catalyst deactivation. The product dries rapidly in 20-60 seconds under 365nm UV light irradiation, reaches usable strength in 3-5 minutes, and is completely cured in 5-10 minutes, making it suitable for the fast-paced requirements of automated production lines.

[0019] 3. The entire process of this invention is room temperature mixing and vacuum degassing, without the need for high-temperature reaction, and there are no special requirements for equipment temperature control or mixing accuracy; the single-component system does not require on-site mixing, avoids the introduction of air bubbles, has high production efficiency, can achieve large-scale continuous production, and reduce industrial production costs. Detailed Implementation

[0020] The following detailed description of the claims of the present invention, in conjunction with specific embodiments, is optional and does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of the claims of the present invention are still within the protection scope of the claims of the present invention.

[0021] Unless otherwise specified, the following embodiments are all conventional experimental methods and operating procedures in the art.

[0022] Example 1 A single-component UV-curable silicone gasket adhesive, comprising the following raw materials by weight: 60 parts of vinyl-terminated polydimethylsiloxane, 15 parts of hydrogen-containing silicone oil, 7 parts of vinyl MQ silicone resin, 5 parts of low-viscosity vinyl silicone oil, 10 parts of hydrophobic fumed silica, 1.0 part of photoinitiator, 0.05 parts of platinum-based catalyst, 1.0 part of silane coupling agent, 0.05 parts of ethynylcyclohexanol, and 0.3 parts of functional additives.

[0023] The vinyl-terminated polydimethylsiloxane has a viscosity of 50,000 Pa·s (25°C), a vinyl content of 0.12 mmol / g, and a silica content of 25 wt%, and was purchased from Wacker Chemie AG.

[0024] The hydrogen-containing silicone oil is compounded from end-capped hydrogen-containing silicone oil and highly active end-side hydrogen-containing silicone oil in a mass ratio of 5.5:1.

[0025] The vinyl MQ silicone resin is model VQM 6 and was purchased from Shin-Etsu Chemical Co., Ltd., Japan. The low-viscosity vinyl silicone oil has a viscosity of 100 mPa·s (25°C) and a vinyl content of 0.37 wt%, and was purchased from Wacker Chemie AG.

[0026] The photoinitiator is a compound of phenyltrimethylsiloxane and vinylphenylsiloxane in a mass ratio of 1:2.5.

[0027] The platinum-based catalyst UV-Pt100 was purchased from Guangzhou Silicon Friends New Materials Technology Co., Ltd.

[0028] The silane coupling agent is a mixture of methacryloyloxypropyltrimethoxysilane and γ-epoxypropoxypropyltrimethoxysilane in a mass ratio of 4:1.

[0029] The functional additives are composed of hindered phenolic anti-yellowing agents and polyether-modified silicone defoamers in a mass ratio of 1:1.

[0030] Its preparation method includes the following steps: (1) Under light-protected conditions, take 2.5 parts by mass of low viscosity vinyl silicone oil, add photoinitiator, inhibitor and platinum-based catalyst, stir at 400 rpm for 15 min at 15℃ to obtain photocurable system, and store at low temperature in the dark for later use.

[0031] (2) Add the terminal vinyl polydimethylsiloxane, the remaining low viscosity vinyl silicone oil and vinyl MQ silicone resin to the reactor and stir at 600 rpm for 45 min at 30 °C. Under light-protected conditions, add hydrogen-containing silicone oil, silane coupling agent, anti-yellowing agent and defoamer to the system and continue stirring for 20 min to obtain the basic system.

[0032] (3) Add hydrophobic fumed silica to the reactor and continue stirring at 700 rpm for 20 min. Vacuum the system to -0.09 MPa and stir at 28℃ and 350 r / min for 45 min to remove bubbles, and obtain the degassed system.

[0033] (4) Under light-protected conditions, the photocuring system and the degassed system are mixed, and the temperature is controlled at 15°C. The mixture is stirred at 250 rpm for 20 min. The mixed system is then evacuated to -0.095 MPa. After vacuum degassing for 18 min, the mixture is discharged and sealed to obtain the silicone gasket adhesive.

[0034] Example 2 The specific implementation method is the same as in Example 1, except that the raw materials are weighed according to the following parts by weight: 55 parts of vinyl-terminated polydimethylsiloxane, 18 parts of hydrogen-containing silicone oil, 7 parts of vinyl MQ silicone resin, 5 parts of low-viscosity vinyl silicone oil, 12 parts of hydrophobic fumed silica, 1.2 parts of photoinitiator, 0.06 parts of platinum-based catalyst, 1.0 part of silane coupling agent, 0.06 parts of inhibitor, and 0.3 parts of functional additives.

[0035] The preparation method was the same as in Example 1.

[0036] Comparative Example 1 The specific implementation method is the same as in Example 1, except that no inhibitor is added.

[0037] Comparative Example 2 The specific implementation method is the same as in Example 1, except that the photoinitiator is replaced with 1.0 part of a traditional acylphosphine oxide photoinitiator.

[0038] Comparative Example 3 The specific implementation method is the same as in Example 1, except that vinyl MQ silicone resin and silane coupling agent are not added.

[0039] Performance testing Storage stability: Store the sample in a sealed container in a 5°C refrigerator away from light, and periodically observe viscosity changes and whether gelation occurs.

[0040] Curing performance: Tested according to GB / T 13477.5-2002 standard, with a 365nm LED light source and a light intensity of 1500mW / cm².

[0041] Shore A hardness: tested according to GB / T 531.1-2008 standard.

[0042] Compression set: Tested according to GB / T 7759.1-2015 standard, 25% compression, 150℃×24h.

[0043] Volume shrinkage rate: tested according to ASTM D2566 standard.

[0044] Shear bond strength: tested according to GB / T 7124-2008 standard.

[0045] The performance test results of each sample are shown in Table 1: Table 1

[0046] Examples 1-2 can be stably stored for 6 months under light-protected conditions of -10~5℃. The system showed no crystallization, no pre-crosslinking, and no viscosity abrupt change, indicating that the precise combination of platinum-based catalyst and alkynol inhibitor can effectively shield catalytic activity, fundamentally solving the industry pain point of premature crosslinking of single-component systems at room temperature / low temperature, and achieving long-term stable storage and transportation.

[0047] Comparative Example 1, lacking an inhibitor, resulted in pre-crosslinking and uneven curing after only one week of storage, demonstrating that the inhibitor is crucial for ensuring storage stability. Comparative Example 2, using a traditional photoinitiator, caused platinum catalyst poisoning, leading to a sharp drop in curing rate and severe degradation of adhesion, confirming that good compatibility between silicon-based photoinitiators and platinum catalysts is a core prerequisite for achieving rapid UV curing. Comparative Example 3, without the addition of vinyl MQ silicone resin and silane coupling agent, showed a decrease in hardness and bond strength.

[0048] In summary, this invention, through the precise design of the catalytic-inhibitor system and the synergistic formulation of multiple components, successfully achieves the organic unity of single-component, rapid UV curing and long-term low-temperature storage stability, while also taking into account excellent mechanical and adhesive properties, and has significant industrial application value and market competitiveness.

Claims

1. A one-component UV-curable silicone gasket adhesive, characterized in that, By weight, it comprises the following components: 50-70 parts of vinyl-terminated polydimethylsiloxane, 10-20 parts of hydrogen-containing silicone oil, 3-8 parts of vinyl MQ silicone resin, 5-15 parts of low-viscosity vinyl silicone oil, 8-15 parts of hydrophobic fumed silica, 0.8-1.5 parts of photoinitiator, 0.02-0.1 parts of platinum-based catalyst, 0.5-1.5 parts of silane coupling agent, 0.02-0.1 parts of alkynyl alcohol inhibitor, and 0.1-0.5 parts of functional additives; The low-viscosity vinyl silicone oil has a viscosity of 50-100 mPa·s at 25°C and a vinyl content of 0.2-0.5 mmol / g.

2. The single-component UV-curable silicone gasket adhesive according to claim 1, characterized in that, The alkynyl alcohol inhibitors include one or more of ethynylcyclohexanol and methylbutynol.

3. The single-component UV-curable silicone gasket adhesive according to claim 1, characterized in that, The platinum-based catalyst includes one or more of UV-Pt100 and UV-Pt500.

4. The single-component UV-curable silicone gasket adhesive according to claim 1, characterized in that, The vinyl-terminated polydimethylsiloxane has a viscosity of 50,000-80,000 mPa·s at 25°C and a vinyl content of 0.02-0.1 mmol / g.

5. The single-component UV-curable silicone gasket adhesive according to claim 4, characterized in that, The terminal vinyl polydimethylsiloxane contains silica, and the silica content is 22-28 wt%.

6. The single-component UV-curable silicone gasket adhesive according to claim 1, characterized in that, The hydrogen-containing silicone oil includes end-capped hydrogen-containing silicone oil and highly active end-side hydrogen-containing silicone oil, with a mass ratio of (5-6):

1.

7. The single-component UV-curable silicone gasket adhesive according to claim 1, characterized in that, The photoinitiator comprises phenyltrimethylsiloxane and vinylphenylsiloxane in a mass ratio of 1:(2-3).

8. The single-component UV-curable silicone gasket adhesive according to claim 1, characterized in that, The silane coupling agent comprises methacryloyloxypropyltrimethoxysilane and γ-epoxypropoxypropyltrimethoxysilane, with a mass ratio of (3-5):

1.

9. The single-component UV-curable silicone gasket adhesive according to claim 1, characterized in that, The functional additives include hindered phenolic anti-yellowing agents and polyether-modified silicone defoamers, with a mass ratio of (0.5-1.5):(0.5-1.5).

10. A method for preparing a single-component UV-curable silicone gasket adhesive as described in any one of claims 1-9, characterized in that, Includes the following steps: (1) Under light-protected conditions and at 10~20℃, 2.5-7.5 parts by weight of low viscosity vinyl silicone oil, the photoinitiator, the alkynol inhibitor and the platinum-based catalyst are mixed and stirred at 300~500 r / min for 10~20 min to obtain a photocurable system; (2) Mix the terminal vinyl polydimethylsiloxane, the remaining low viscosity vinyl silicone oil and the vinyl MQ silicone resin, and stir at 20~35°C and 500~800 r / min for 30~60 min; under light-protected conditions, add the hydrogen-containing silicone oil, the silane coupling agent and the functional additive, and stir at 400~600 r / min for 15~30 min to obtain the basic system; (3) Add the hydrophobic fumed silica to the basic system, stir at 600~800 r / min for 15~30 min, and degas under vacuum to obtain the degassed system; (4) Mix the photocuring system and the degassed system, stir at 200~300r / min for 15~30min, and degassed under vacuum to obtain the silicone gasket adhesive.

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