A sprayable, high-adhesion, room-temperature curing liquid silicone rubber, its preparation method, and its applications.

Abstract

This invention discloses a sprayable, high-adhesion, room-temperature curing liquid silicone rubber, its preparation method, and its applications. The rubber comprises component A, containing a base silicone rubber and a catalyst, and component B, containing a base silicone rubber and a crosslinking agent, wherein the mass ratio of component A to component B is 1:1. Compared with existing technologies, the product of this invention has extremely low viscosity, can be sprayed, and cures rapidly at room temperature in the presence of solder, flux, etc., allowing workpieces to be handled 30 minutes after application.

Description

Technical Field

[0001] This invention relates to polymer materials, specifically to a sprayable, high-adhesion, room-temperature curing liquid silicone rubber, its preparation method, and its applications. Background Technology

[0002] Most general polymer materials have a carbon-carbon (C / C) bond main chain structure, such as plastics, rubber, and chemical fibers. Organosilicon products, however, have a silicon-oxygen (Si-O) bond main chain structure. The bond energy of a C / C bond is 82.6 kcal / mol, while the bond energy of a Si-O bond in organosilicon is 121 kcal / mol. Therefore, organosilicon products have high thermal stability; the chemical bonds of the molecules do not break or decompose at high temperatures (or under radiation). Furthermore, because organosilicon molecules have a flexible helical structure, they are resistant to both high and low temperatures, allowing for use over a wide temperature range. Due to the unique nature of the O-Si-O- main chain in organosilicon products, there are no double bonds, making them less susceptible to decomposition by ultraviolet light and ozone. In organosilicon products, the chain length of the Si-O bond is approximately one and a half times the chain length of the C / C bond. This longer chain length gives organosilicon better thermal stability, radiation resistance, and weather resistance than other polymer materials. Organosilicon products possess excellent electrical insulation properties. Their dielectric loss, voltage withstand capability, arc resistance, corona resistance, volume resistivity, and surface resistivity are among the best in insulating materials, and their electrical properties are minimally affected by temperature and frequency. Therefore, they are stable electrical insulating materials widely used in the electronics and electrical industries. In addition to excellent heat resistance, organosilicon also exhibits superior water repellency, ensuring high reliability of electrical equipment used in humid conditions.

[0003] Due to these excellent properties, organosilicon has a very wide range of applications. It is used not only as a special material in aerospace, cutting-edge technology, and military technology sectors, but also in various sectors of the national economy, with applications expanding to include: construction, electronics, textiles, automobiles, machinery, leather and papermaking, chemical and light industry, metals and paints, pharmaceuticals, and more.

[0004] In the electronics and electrical industry, due to the inability of some new electronic components to withstand high temperatures and national requirements for energy conservation and emission reduction, room temperature curing silicone liquid rubber is increasingly needed. Condensation-type room temperature curing silicone rubber cannot meet the specific needs of the electronics and electrical industry due to its odor and volume shrinkage. Therefore, addition-type room temperature curing liquid silicone rubber has become the optimal choice. Spray application is widely used in the electronics and electrical industry due to its high efficiency, uniformity, and strong controllability. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide a sprayable, high-adhesion, room-temperature curing liquid silicone rubber, its preparation method, and its application to meet the specific application scenarios of the electronics and electrical industries.

[0006] The objective of this invention can be achieved through the following technical solution: a sprayable, high-adhesion, room-temperature curing liquid silicone rubber, characterized in that it comprises component A containing basic silicone and a catalyst and component B containing basic silicone and a crosslinking agent: wherein the mass ratio of component A to component B is 1:1.

[0007] Component A comprises the following components in parts by weight: 90-110 parts of one or more low-volatility dimethyl polysiloxanes containing at least two vinyl groups per molecule; 0.1-8.5 parts of platinum catalyst; 1-15 parts of hydrophobic fumed silica; 0.05-2 parts of viscosity reducer; and 0.5-3 parts of pigment.

[0008] The aforementioned low-volatility dimethyl polysiloxane containing two vinyl groups includes vinyl-terminated polydimethylsiloxanes. Preferably, it is a mixture of vinyl-terminated polydimethylsiloxanes with a viscosity of 1000 mPa·s and vinyl-terminated polydimethylsiloxanes with a viscosity of 500 mPa·s in a mass ratio of 1.2 to 1.5:1.

[0009] The A component is prepared by the following method: a low-volatility dimethyl polysiloxane containing two vinyl groups is mixed evenly with a platinum catalyst, hydrophobic fumed silica is added, and the mixture is rapidly dispersed in a high-speed disperser for 5-15 minutes. A viscosity reducer and pigment are added, and the mixture is further dispersed at high speed for 5-15 minutes. Then, the mixture is degassed under vacuum to obtain the A component.

[0010] The B component comprises the following components in parts by weight: 90-100 parts of one or more low-volatility dimethyl polysiloxanes containing at least two vinyl groups per molecule; 10-15 parts of one or more dimethyl polysiloxanes containing at least two or more Si-H groups per molecule; 1-15 parts of hydrophobic fumed silica; and 0.05-2 parts of inhibitor.

[0011] The aforementioned low-volatility dimethyl polysiloxane containing two vinyl groups includes vinyl-terminated polydimethylsiloxanes. Preferably, it is a mixture of a vinyl-terminated polydimethylsiloxane with a viscosity of 2000 mPa·s and a vinyl-terminated polyvinyl polydimethylsiloxane with a viscosity of 500 mPa·s in a mass ratio of 1.1 to 1.2:1.

[0012] The dimethyl polysiloxane containing two or more Si-H groups includes one or both of trimethylsilyl-terminated hydrogen-containing polyorganosiloxanes or silane-hydrogen-terminated polydimethylsiloxanes.

[0013] The B component is prepared by the following method: a low-volatility dimethyl polysiloxane containing two vinyl groups and an inhibitor are rapidly dispersed in a high-speed disperser for 5-15 min, then a dimethyl polysiloxane containing two or more Si-H groups, hydrophobic fumed silica, and an adhesive are added, and the dispersion is continued at high speed for 5-15 min, followed by vacuum degassing to obtain the B component.

[0014] The above-mentioned method for preparing sprayable high-adhesion room temperature curing liquid silicone rubber involves mixing component A and component B in a 1:1 mass ratio using a static mixer.

[0015] The above-mentioned application of sprayable high-adhesion room temperature curing liquid silicone rubber involves mixing components A and B and applying the mixture by spraying. After application, the colloid achieves surface drying and portability within 30 minutes at room temperature (25±2℃), and forms good adhesion on the PCBA surface in the presence of solder and additives within 24 hours.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. It uses low-volatility dimethylpolysiloxane raw materials, making it safe and environmentally friendly;

[0018] 2. Extremely low viscosity; suitable for spray application.

[0019] 3. It cures rapidly at room temperature in the presence of solder, flux, etc., and the workpiece can be handled 30 minutes after application;

[0020] 4. No small molecule release, no odor, and no volume shrinkage;

[0021] 5. Forms a reliable and strong bond at room temperature. Detailed Implementation

[0022] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[0023] All raw materials used in the following examples are commercially available, for example:

[0024] Vinyl-terminated polydimethylsiloxanes can be selected from Ambia's VS2000, VS1000, VS500, and other models;

[0025] For vinyl-terminated polyvinyl dimethylsiloxanes, you can choose products such as Ambia's VDM500 model;

[0026] For trimethylsilyl-terminated hydrogen-containing polyorganosiloxanes, products such as Ambia XL-1B can be selected.

[0027] For silane-hydrogen-terminated polydimethylsiloxane, you can choose products such as Ambia's CE500 and CE13 models.

[0028] Platinum catalysts such as Anbia's Pt-1020 can be selected;

[0029] For hydrophobic fumed silica, Evonik's 8200 and other similar products can be selected.

[0030] For viscosity reducers, you can choose products from Evonik's Glide series;

[0031] Pigments can be selected from the vinyl silicone oil series products of Jiasheng Company;

[0032] Inhibitors can be selected from products such as Anbia's 2827-186L;

[0033] For adhesive additives, you can choose products such as Shin-Etsu Chemical's KH560 and KH5070, including but not limited to the adhesive additives mentioned above.

[0034] Example 1

[0035] Weigh 52g of vinyl-terminated polydimethylsiloxane (VS2000) with a viscosity of 2000mPa·s and 36g of vinyl-terminated polydimethylsiloxane (VS1000) with a viscosity of 1000mPa·s, and 4.7g of platinum catalyst (Pt-1020) and stir until homogeneous; rapidly disperse 5.3g of hydrophobic fumed silica (8200) in a high-speed disperser for 10min, add 1 part of viscosity reducer and 1 part of pigment, continue high-speed dispersion for 10min, and then degas under vacuum to obtain catalyst component (A) mixture for later use.

[0036] Weigh 42g of vinyl-terminated polydimethylsiloxane (VS2000) with a viscosity of 2000mPa·s and 36g of vinyl-terminated polyvinyl dimethylsiloxane (VDM500) with a viscosity of 500mPa·s. Add 0.8g of inhibitor (2827-186L) and disperse rapidly in a high-speed disperser for 10min. Add 2g of trimethylsilyl-terminated hydrogen-containing polyorganosiloxane (XL-1B) and 10g of silane-terminated polydimethylsiloxane (CE500), 5.2g of hydrophobic fumed silica (8200), and 4.0g of γ-glycidyl etheroxypropyltrimethoxysilane (KH560). Continue high-speed dispersion for 10min, then degas under vacuum to obtain a crosslinking agent (B) component mixture for later use.

[0037] By weighing (measuring) equal amounts of catalyst (A) and crosslinking agent (B) in a 1:1 ratio and mixing them evenly, a sprayable, high-adhesion, room-temperature curing addition-type liquid silicone rubber can be prepared.

[0038] Example 2

[0039] Weigh 52g of vinyl-terminated polydimethylsiloxane (VS2000) with a viscosity of 1000mPa·s and 36g of vinyl-terminated polydimethylsiloxane (VS1000) with a viscosity of 500mPa·s, and 4.7g of platinum catalyst (Pt-1020) and stir until homogeneous; rapidly disperse 15.3g of hydrophobic fumed silica in a high-speed disperser for 10min, add 1 part of viscosity reducer and 1 part of pigment, continue high-speed dispersion for 10min, and then degas under vacuum to obtain catalyst component (A) mixture for later use.

[0040] Weigh 42g of vinyl-terminated polydimethylsiloxane (VS2000) with a viscosity of 1000mPa·s and 33g of vinyl-terminated polyvinyl dimethylsiloxane (VDM500) with a viscosity of 500mPa·s. Add 0.8g of inhibitor (2827-186L) and disperse rapidly in a high-speed disperser for 10min. Add 3g of trimethylsilyl-terminated hydrogen-containing polyorganosiloxane (XL-1B) and 12g of silane-terminated polydimethylsiloxane (CE500), 15.2g of hydrophobic fumed silica, and 4.0g of γ-glycidyl etheroxypropyltrimethoxysilane. Continue high-speed dispersion for 10min, then degas under vacuum to obtain a crosslinking agent (B) component mixture for later use.

[0041] By weighing (measuring) equal amounts of catalyst (A) and crosslinking agent (B) in a 1:1 ratio and mixing them evenly, a sprayable, high-adhesion, room-temperature curing addition-type liquid silicone rubber can be prepared.

[0042] Example 3

[0043] Weigh 52g of vinyl-terminated polydimethylsiloxane (VS2000) with a viscosity of 1000mPa·s and 36g of vinyl-terminated polydimethylsiloxane (VS1000) with a viscosity of 500mPa·s, and 4.7g of platinum catalyst (Pt-1020) and stir until homogeneous; rapidly disperse 5.3g of hydrophobic fumed silica in a high-speed disperser for 10min, add 1 part of viscosity reducer and 1 part of pigment, continue high-speed dispersion for 10min, and then degas under vacuum to obtain catalyst component (A) mixture for later use.

[0044] Weigh 42g of vinyl-terminated polydimethylsiloxane (VS2000) with a viscosity of 1000mPa·s and 33g of vinyl-terminated polyvinyl polydimethylsiloxane (VDM500) with a viscosity of 500mPa·s. Add 0.8g of inhibitor (2827-186L) and disperse rapidly in a high-speed disperser for 10min. Add 3g of trimethylsilyl-terminated hydrogen-containing polyorganosiloxane (XL-1B) and 12g of silane-terminated polydimethylsiloxane (CE500), 5.2g of hydrophobic fumed silica, and 4.0g of γ-methacryloyloxypropyltrimethoxysilane. Continue high-speed dispersion for 10min, then degas under vacuum to obtain a crosslinking agent (B) component mixture for later use.

[0045] By weighing (measuring) equal amounts of catalyst (A) and crosslinking agent (B) in a 1:1 ratio and mixing them evenly, a sprayable, high-adhesion, room-temperature curing addition-type liquid silicone rubber can be prepared.

[0046] The silicone rubber elastomers prepared in Examples 1, 2, and 3 above were subjected to product performance tests, and the results are shown in Table 1.

[0047] Table 1

[0048]

[0049] As can be seen from the table above, the viscosity of the products obtained by this invention is less than 2000 mPas, which can meet the process requirements of spray coating. Furthermore, the tensile strength after coating is ≥0.4 MPa and the tensile shear strength is ≥0.3 MPa, which can meet the performance requirements of special application scenarios for consumer electronics products.

[0050] The product of this invention can be cured at room temperature without additional heating; it adheres firmly to common engineering plastics such as metals, PC, ABS, and PA; moreover, it is an addition-cure silicone rubber, with no small molecule precipitation, no volume shrinkage, and is environmentally friendly; the product has a wide viscosity range, from hundreds of thousands to hundreds of mPas, and can achieve the above functions (high viscosity cannot guarantee spraying).

Claims

1. A sprayable, high-adhesion, room-temperature curing liquid silicone rubber, characterized in that, It includes component A containing basic silica gel and catalyst, and component B containing basic silica gel and crosslinking agent: wherein the mass ratio of component A to component B is 1:1; Component A comprises the following components in parts by weight: 90-110 parts of low-volatility dimethyl polysiloxane containing at least two vinyl groups per molecule; 0.1-8.5 parts of platinum catalyst; 1-15 parts of hydrophobic fumed silica; 0.05-2 parts of viscosity reducer; and 0.5-3 parts of pigment. The low-volatility dimethyl polysiloxane containing at least two vinyl groups per molecule in Component A comprises a mixture of vinyl-terminated dimethyl polysiloxane with a viscosity of 2000 mPa·s and vinyl-terminated dimethyl polysiloxane with a viscosity of 1000 mPa·s in a mass ratio of 52:

36. Component B comprises the following components in parts by weight: 90-100 parts of a low-volatility dimethyl polysiloxane containing at least two vinyl groups per molecule; 10-15 parts of one or more dimethyl polysiloxanes containing at least two or more Si-H groups per molecule; 1-15 parts of hydrophobic fumed silica; and 0.05-2 parts of an inhibitor; wherein the low-volatility dimethyl polysiloxane containing at least two vinyl groups per molecule in Component B comprises a mixture of vinyl-terminated dimethyl polysiloxane with a viscosity of 2000 mPa•s and vinyl-terminated polyvinyl dimethyl polysiloxane with a viscosity of 500 mPa•s in a mass ratio of 1.1-1.2:1; The viscosity reducer selected is a product from Evonik's Glide series; When using, mix components A and B and apply the adhesive by spraying. After application, the adhesive will be surface dry and transferable within 30 minutes at room temperature (25±2℃). It will form a good bond on the PCBA surface in the presence of solder and flux within 24 hours.

2. The sprayable high-adhesion room-temperature curing liquid silicone rubber according to claim 1, characterized in that, The A component is prepared by the following method: a low-volatility dimethyl polysiloxane containing two vinyl groups is mixed evenly with a platinum catalyst, hydrophobic fumed silica is added, and the mixture is rapidly dispersed in a high-speed disperser for 5-15 minutes. A viscosity reducer and pigment are added, and the mixture is further dispersed at high speed for 5-15 minutes. Then, the mixture is degassed under vacuum to obtain the A component.

3. The sprayable high-adhesion room-temperature curing liquid silicone rubber according to claim 1, characterized in that, The dimethyl polysiloxane containing two or more Si-H groups includes one or both of trimethylsilyl-terminated hydrogen-containing polyorganosiloxanes or silane-hydrogen-terminated polydimethylsiloxanes.

4. A method for preparing a sprayable, high-adhesion, room-temperature curing liquid silicone rubber as described in any one of claims 1-3, characterized in that, Simply mix component A and component B in a 1:1 mass ratio using a static mixer.

5. An application of the sprayable high-adhesion room-temperature curing liquid silicone rubber as described in any one of claims 1-3, characterized in that, After mixing components A and B, the adhesive is applied by spraying. After application, the adhesive is surface dry and portable within 30 minutes at room temperature (25±2℃). It forms good adhesion on the PCBA surface in the presence of solder and flux within 24 hours.

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