High-strength low-density room-temperature vulcanized rubber and its preparation method and application

Abstract

The present application provides a high-strength and low-density room-temperature vulcanized rubber, a preparation method and application thereof. The high-strength and low-density room-temperature vulcanized rubber comprises the following components by weight: 100 parts of polydimethylsiloxane; 0-20 parts of dimethyl silicone oil; 10-50 parts of T-type methoxy silicone resin; 0-10 parts of filler; 2-6 parts of cross-linking agent; 0.2-3 parts of coupling agent; and 0.1-8 parts of catalyst. The present application uses polydimethylsiloxane as the main raw material and T-type methoxy silicone resin as the main reinforcing filler, so that the high-strength and low-density characteristics are realized, and the excellent bonding and simple process characteristics are also achieved. After the prepared high-strength and low-density room-temperature vulcanized rubber is completely cured, the density is 1.07 g / cm 3 or lower, the tensile strength is 3.0 MPa or higher, and can be as high as 4.53 MPa, and the shear strength is 2.0 MPa or higher, and can be as high as 2.57 MPa. 3 or lower, the tensile strength is 3.0 MPa or higher, and can

Description

Technical Field

[0001] This invention relates to the field of organic polymer materials technology, and in particular to a high-strength, low-density room-temperature vulcanizate, its preparation method, and its application. Background Technology

[0002] One-component room temperature vulcanizing silicone rubber possesses excellent adhesive and mechanical properties, low cost, and is easy to automate dispensing. Its outstanding resistance to high and low temperatures, electrical insulation, and weather resistance make it widely used in construction, electronics, and industrial fields. Based on its curing reaction type, it can be divided into de-alcoholization systems and deoxime systems. Among them, the small molecules released during the curing process of the de-alcoholization system are alcohols, which are non-toxic, environmentally friendly, and non-corrosive, leading to their increasingly widespread application across various industries.

[0003] High-strength, low-density silicone adhesives and sealants are increasingly widely used in lightweight applications in fields such as new energy, communications, electronics, power, and military, and represent a major future development trend. Currently, the main method to improve tensile strength is by adding a large amount of inorganic reinforcing fillers, which makes it difficult to achieve low density. On the other hand, it is difficult to achieve both high strength and high bulk strength using silicone resin reinforcement, or situations may occur where the bulk strength is very high but the adhesive strength is very poor.

[0004] Therefore, there is a need for a high-strength, low-density room-temperature vulcanizing adhesive with excellent bonding properties. Summary of the Invention

[0005] The purpose of this invention is to overcome the aforementioned defects and provide a high-strength, low-density room-temperature vulcanizing adhesive with excellent bonding properties. This invention uses polydimethylsiloxane as the main raw material and silicone resin with a specific molecular structure as the main reinforcing filler, achieving the high strength and low density characteristics of silicone adhesives.

[0006] Another object of the present invention is to provide a method for preparing the high-strength, low-density room-temperature vulcanizate.

[0007] Another object of the present invention is to provide the application of the high-strength, low-density room temperature vulcanizate in the fields of construction, electronic communications, industry, new energy, or corrosion protection.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A high-strength, low-density room-temperature vulcanizing rubber comprises the following components in parts by weight:

[0010]

[0011]

[0012] This invention designs the spatial structure of silicone resin to achieve a suitable degree of crosslinking, greatly increasing the compatibility between the silicone resin and the system. This prioritizes the reaction between polydimethylsiloxane adhesive and silicone resin, balancing the system's strength and toughness. It avoids the drawbacks of preferential reactions between polydimethylsiloxane adhesives or between silicone resins, which could negatively impact the system's curing and mechanical properties. Since the density of silicone resin is close to that of polydimethylsiloxane, the addition of silicone resin has a relatively small impact on density, but a significant effect on improving strength.

[0013] Preferably, the polydimethylsiloxane comprises one or a combination of several of methyldimethoxy-terminated polydimethylsiloxane, trimethoxy-terminated polydimethylsiloxane, and vinyldimethoxy-terminated polydimethylsiloxane.

[0014] Preferably, the dynamic viscosity of the polydimethylsiloxane at 25°C is 1500–80000 mPa·s, and the viscosity is obtained by testing according to the method in standard GB / T 22235-2008. Polydimethylsiloxane is the base resin, and the viscosity of the base resin within this range ensures the strength of the prepared vulcanizate and also allows other components, such as fillers and other inorganic substances, to be uniformly and stably dispersed in the system.

[0015] In this invention, the dimethyl silicone oil (i.e., polydimethylsiloxane) serves as a viscosity modifier to adjust the viscosity of the system, thereby giving the vulcanizate better processing and curing properties. The dynamic viscosity of the dimethyl silicone oil at 25°C can be selected as 50–12500 mPa·s.

[0016] Preferably, the T-type methoxysilane resin is prepared from a substance comprising the following weight ratio: dimethyldichlorosilane: methyltrimethoxysilane: phenyltrimethoxysilane: n-hexadecyltrimethoxysilane = 1:(2-6):(0-2):(0-2).

[0017] In this invention, the T-type methoxysilicone resin is prepared by a method comprising the following steps:

[0018] ① Add purified water to a flask and slowly add dimethyldichlorosilane dropwise while stirring at 5–40°C for 1–3 hours; ② Add methyltrimethoxysilane, phenyltrimethoxysilane, and n-hexadecyltrimethoxysilane dissolved in toluene to a dropping funnel and slowly add them dropwise to the flask while stirring at room temperature. Then, under nitrogen protection, raise the temperature to 50–90°C and stir for 1–5 hours; ③ Return to room temperature and adjust the pH to neutral; remove excess solvent toluene by rotary evaporation to obtain the T-type methoxysilicone resin.

[0019] Preferably, the filler comprises one or a combination of several of the following: calcium carbonate, talc, zinc borate, titanium dioxide, silica powder, quartz powder, aluminum hydroxide, alumina, silica, carbon black, magnesium oxide, zinc oxide, barium carbonate, diatomaceous earth, and kaolin. The addition of filler can improve the mechanical strength of the vulcanized rubber.

[0020] Preferably, the crosslinking agent includes, but is not limited to, one or a combination of several of vinyltrimethoxysilane, vinyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, phenyltrimethoxysilane, and diphenyldimethoxysilane.

[0021] Preferably, the coupling agent includes, but is not limited to, one or a combination of several of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, and γ-[(2,3)-epoxypropyl]propyltrimethoxysilane.

[0022] Preferably, the catalyst includes, but is not limited to, one or a combination of several of the following: dioctyltin diacetate, dioctyltin dilaurate, dioctyltin dioctanoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dioctanoate, isopropyl titanate, isobutyl titanate, n-butyl titanate, ethyl acetoacetate chelate of isopropyl titanate, and acetylacetone chelate of isopropyl titanate.

[0023] This invention also protects the method for preparing the above-mentioned high-strength, low-density room-temperature vulcanizate, comprising the following steps:

[0024] After polydimethylsiloxane, dimethyl silicone oil and filler are mixed evenly, they are dehydrated at 80-150℃ under vacuum conditions of -0.097 to -0.092 MPa, and then cooled to below 40℃. T-type methoxy silicone resin, crosslinking agent, coupling agent and catalyst are added, mixed evenly and discharged to obtain the high-strength low-density room temperature vulcanizate.

[0025] Preferably, the dehydration time is 2 to 4 hours.

[0026] Preferably, in the above steps, the raw materials are mixed by vacuum stirring. The conditions for vacuum stirring are: vacuuming to -0.097Mpa to -0.092Mpa and stirring in a sealed environment for 30±10min.

[0027] The application of the aforementioned high-strength, low-density room temperature vulcanizing rubber in the fields of construction, electronic communications, industry, new energy, or corrosion protection is also within the scope of protection of this invention.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] Compared to existing room temperature vulcanizing silicone rubbers, this invention uses polydimethylsiloxane as the main raw material and T-type methoxysilicone resin as the main reinforcing filler to achieve high strength and low density, while also possessing excellent adhesion and simple processing characteristics. The resulting high-strength, low-density room temperature vulcanizate, after complete curing, exhibits a tensile strength ≥3.0 MPa and a density ≤1.07 g / cm³. 3 And the bonding strength is above 2.0MPa. Detailed Implementation

[0030] To better illustrate the purpose, technical solution, and advantages of this invention, specific embodiments will be used to further describe the invention below. However, these embodiments do not limit the invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in this invention are conventional reagents, methods, and equipment in this technical field. Unless otherwise specified, all reagents and materials used in this invention are commercially available.

[0031] Raw material description:

[0032] Polydimethylsiloxane:

[0033] 1#: Trimethoxy-terminated polydimethylsiloxane, O-FT15, viscosity at 25℃ is 2000 mPa·s, purchased from Orange Sky New Materials (Guangzhou) Co., Ltd.;

[0034] 2#: Trimethoxy-terminated polydimethylsiloxane, O-FT200, with a viscosity of 20000 mPa·s at 25°C, purchased from Orange Sky New Materials (Guangzhou) Co., Ltd.

[0035] 3#: Trimethoxy-terminated polydimethylsiloxane, O-FT800, with a viscosity of 80,000 mPa·s at 25°C, purchased from Orange Sky New Materials (Guangzhou) Co., Ltd.

[0036] 4#: Vinyl dimethoxy-terminated polydimethylsiloxane, O-F1500, with a viscosity of 1550 mPa·s at 25°C, purchased from Orange Sky New Materials (Guangzhou) Co., Ltd.

[0037] Dimethyl silicone oil :

[0038] 1#: AK 50, with a viscosity of 50 mPa·s at 25°C, was purchased from Wacker Chemie (China) Co., Ltd.

[0039] 2#: AK 100, with a viscosity of 100 mPa·s at 25°C, was purchased from Wacker Chemie (China) Co., Ltd.

[0040] 3#: AK 12500, with a viscosity of 12500 mPa·s at 25°C, was purchased from Wacker Chemie (China) Co., Ltd.

[0041] filler:

[0042] Silica: H18, purchased from Wacker Chemie (China) Co., Ltd.;

[0043] Titanium dioxide: SR-237, purchased from Shandong Dongjia Group Co., Ltd.;

[0044] Calcium carbonate: CCS-25, purchased from Guangxi Huana New Material Technology Co., Ltd.;

[0045] Crosslinking agent: Vinyltrimethoxysilane, commercially available;

[0046] Coupling agent: γ-aminopropyltriethoxysilane, KH-550, commercially available;

[0047] Catalyst: Dioctyltin diacetate, commercially available;

[0048] T-type methoxy silicone resin:

[0049] The following raw material formula and method are used to prepare the product:

[0050] ① Add purified water to a flask, and add dimethyldichlorosilane dropwise while stirring at 40°C. Stir for 3 hours to mix thoroughly. ② Add toluene-dissolved methyltrimethoxysilane, phenyltrimethoxysilane, and n-hexadecyltrimethoxysilane to a dropping funnel. While stirring at room temperature (25°C), slowly add the mixture dropwise to the flask. Then, under nitrogen protection, raise the temperature to 80°C and stir for 4 hours. ③ Return to room temperature (25°C) and adjust the pH to neutral. Remove excess solvent toluene by rotary evaporation to obtain the T-type methoxysilane resin.

[0051] Table 1. Raw material ratio of silicone resin (by weight)

[0052]

[0053] Examples 1-8

[0054] This embodiment provides a series of high-strength, low-density room temperature vulcanizing rubbers, the preparation method of which includes the following steps:

[0055] According to the raw material composition in Table 2, polydimethylsiloxane, dimethyl silicone oil and filler are mixed evenly using a power mixer. After being dehydrated for 3 hours at 150°C under vacuum conditions of -0.092 MPa, the mixture is then cooled to below 40°C. T-type methoxysilicone resin, crosslinking agent, coupling agent and catalyst are added. The mixture is then vacuumed to -0.097 MPa and stirred in a sealed container for 30 minutes until evenly mixed. The resulting high-strength, low-density room temperature vulcanizate is then obtained.

[0056] Table 2 High-strength, low-density room-temperature vulcanizates (parts by weight) of Examples 1-8

[0057]

[0058]

[0059] Comparative Example 1

[0060] This comparative example provides a room temperature vulcanizing adhesive, prepared according to the method of Example 1, except that the T-type methoxysilicone resin is replaced by calcium carbonate in equal mass.

[0061] Comparative Example 2

[0062] This comparative example provides a room temperature vulcanizing rubber, prepared according to the method of Comparative Example 1, except that the amount of calcium carbonate is increased to 100 parts by weight.

[0063] Comparative Example 3

[0064] This comparative example provides a room temperature vulcanizing adhesive, prepared according to the method of Example 1, except that the T-type methoxy silicone resin A is replaced by silicone resin E by mass.

[0065] Comparative Example 4

[0066] This comparative example provides a room temperature vulcanizing adhesive, prepared according to the method of Example 1, except that the T-type methoxy silicone resin A is replaced by silicone resin F by mass.

[0067] Comparative Example 5

[0068] This comparative example provides a room temperature vulcanizing adhesive, prepared according to the method of Example 1, except that the T-type methoxy silicone resin A is replaced by silicone resin G by mass.

[0069] Comparative Example 6

[0070] This comparative example provides a room temperature vulcanizing adhesive, prepared according to the method of Example 1, except that the T-type methoxy silicone resin A is replaced by silicone resin H by mass.

[0071] Performance testing

[0072] After the room temperature vulcanizates obtained in the above embodiments and comparative examples were cured, the properties of the cured vulcanizates were characterized. The curing method of the vulcanizates was as follows: a polytetrafluoroethylene container with a wedge-shaped groove depth of 2 mm, a length of 25 cm, and a width of 20 cm was used. The prepared high-strength, low-density room temperature vulcanizate was uniformly poured into the polytetrafluoroethylene container. Then, the sample was placed under the conditions of (23±2)℃ and 55% relative humidity for 7 days to cure. After that, the sample was taken out, the test sample was cut, and the performance was tested.

[0073] The specific test items and test methods are as follows:

[0074] 1. Surface drying time: Tested according to GB / T 13477.5;

[0075] 2. Density: Tested according to standard GB / T 13477.2-2018, using the density balance method;

[0076] 3. Tensile strength and elongation at break: Tested according to GB / T 528-2009, wherein the specimen is prepared as a dumbbell-shaped sample (Type I, thickness of 2 mm), the tensile rate is 500 mm / min, and the test temperature is 25℃;

[0077] 4. Hardness: Tested according to GB / T 531.1-2008;

[0078] 5. Shear strength (adhesive performance): According to GB / T 7124-2008, specifically: the prepared high-strength, low-density room temperature vulcanizing silicone is uniformly coated on the surface of 3003 series aluminum material, with an adhesion area of ​​25mm x 12.5mm and a thickness of 1mm. The sample is then placed in a temperature of (23±2)℃ and a relative humidity of 55% for 7 days to cure, and then taken out for testing.

[0079] The test results are shown in Table 3.

[0080] Table 3 shows the test results of the vulcanizates obtained from the examples and comparative examples.

[0081]

[0082]

[0083] The results above show that:

[0084] The vulcanizate prepared by this invention simultaneously possesses low density, high strength, and excellent adhesive properties, with a density of 1.07 g / cm³. 3 Below that, it can be as low as 1.03 g / cm³. 3The tensile strength is above 3.0 MPa, and can reach up to 4.53 MPa; the shear strength is above 2.0 MPa, and can reach up to 2.57 MPa.

[0085] Comparative Example 1 Replacing T-type methoxysilicone resin with calcium carbonate results in a higher density, but due to insufficient addition, the tensile strength is also lower; Comparative Example 2 In Comparative Example 1, after increasing the calcium carbonate to 100 parts by weight, a large amount of inorganic filler was added. Although the strength was improved, the density was significantly higher than that of the vulcanized rubber prepared in the embodiments of the present invention. Example 1 Comparative Examples 3-6 The results further demonstrate that only by selecting the silicone resin with the specific structure of this invention can the strength and bonding strength of the vulcanizate be improved while maintaining a low density.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A high-strength, low-density room-temperature vulcanizing rubber, characterized in that, It includes the following components in parts by weight: 100 parts of polydimethylsiloxane; 0-20 parts of dimethyl silicone oil; 10-50 parts of T-type methoxysilicone resin; 0-10 parts of filler; Crosslinking agent 2-6 parts; 0.2-3 parts of coupling agent; Catalyst 0.1~8 parts; The T-type methoxysilicone resin is prepared from substances comprising the following weight ratios: Dimethyldichlorosilane: methyltrimethoxysilane: phenyltrimethoxysilane: n-hexadecyltrimethoxysilane = 1: (2~6): (0~2): (0~2).

2. The high-strength, low-density room-temperature vulcanizing rubber according to claim 1, characterized in that, The polydimethylsiloxane includes one or a combination of several of methyldimethoxy-terminated polydimethylsiloxane, trimethoxy-terminated polydimethylsiloxane, and vinyldimethoxy-terminated polydimethylsiloxane.

3. The high-strength, low-density room-temperature vulcanizing rubber according to claim 1, characterized in that, The dimethyl silicone oil has a dynamic viscosity of 50~12500 mPa·s at 25°C.

4. The high-strength, low-density room-temperature vulcanizing rubber according to claim 1, characterized in that, The filler includes one or a combination of several of the following: calcium carbonate, talc, zinc borate, titanium dioxide, silica powder, quartz powder, aluminum hydroxide, alumina, silica, carbon black, magnesium oxide, zinc oxide, barium carbonate, diatomaceous earth, and kaolin.

5. The high-strength, low-density room-temperature vulcanizing rubber according to claim 1, characterized in that, The crosslinking agent includes one or a combination of several of vinyltrimethoxysilane, vinyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, phenyltrimethoxysilane, and diphenyldimethoxysilane.

6. The high-strength, low-density room-temperature vulcanizing rubber according to claim 1, characterized in that, The coupling agent includes one or a combination of several of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, and γ-[(2,3)-epoxypropyl]propyltrimethoxysilane.

7. The high-strength, low-density room-temperature vulcanizing rubber according to claim 1, characterized in that, The catalyst comprises one or a combination of several of the following: dioctyltin diacetate, dioctyltin dilaurate, dioctyltin dioctanoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dioctanoate, isopropyl titanate, isobutyl titanate, n-butyl titanate, ethyl acetoacetate chelate of isopropyl titanate, and acetylacetone chelate of isopropyl titanate.

8. The method for preparing the high-strength, low-density room-temperature vulcanizate according to any one of claims 1 to 7, characterized in that, Includes the following steps: After polydimethylsiloxane, dimethyl silicone oil and filler are mixed evenly, they are dehydrated at 80~150℃ under vacuum conditions of -0.097 to -0.092 MPa, and then cooled to below 40℃. T-type methoxy silicone resin, crosslinking agent, coupling agent and catalyst are added, mixed evenly and discharged to obtain the high-strength low-density room temperature vulcanizate.

9. The application of the high-strength, low-density room temperature vulcanizing adhesive according to any one of claims 1 to 7 in the fields of construction, electronic communication, industry, new energy or corrosion protection.

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