Two-component RTV silicone rubber and preparation method and application thereof

Abstract

The invention discloses two-component RTV silicone rubber and a preparation method and application thereof.The two-component RTV silicone rubber is composed of a component A and a component B. The component A comprises vinyl-containing polysiloxane and filler, the component B comprises hydrogen-containing polysiloxane, a cross-linking agent and an organic tin catalyst, and the component A and / or the component B further comprises a microencapsulated phase-change material, the phase change temperature of the phase change material in the microencapsulated phase change material is 25-45 DEG C. The skinning time of the component A and the component B of the two-component RTV silicone rubber in a static mixer is remarkably prolonged, so that the operation time of the silicone rubber is remarkably prolonged, the main curing performance of the silicone rubber can be reserved, and the two-component RTV silicone rubber has extremely high industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of organosilicon polymer materials technology, specifically to the field of room temperature vulcanizing silicone rubber technology, and more specifically, this invention relates to a two-component RTV silicone rubber, its preparation method and application. Background Technology

[0002] Two-component addition-curing room temperature vulcanizing silicone rubber is widely used in electronic component encapsulation, new energy vehicle bonding, LED lighting, and other fields due to its excellent weather resistance, electrical insulation, thermal stability, and environmental friendliness. In modern automated production, components A and B are typically mixed in a ratio (e.g., 10:1) and extruded using metering pumps and static mixers.

[0003] However, platinum-catalyzed addition reactions are exothermic. When the mixed adhesive passes under high pressure through a static mixer with a complex internal structure, it generates enormous shear heat. This heat is difficult to dissipate within the confined space, leading to a rapid increase in localized temperature. This significantly accelerates the curing reaction rate, causing the adhesive to prematurely skin and solidify inside the static mixer, making it prone to clogging and resulting in short operating times. This not only leads to material waste but also necessitates frequent shutdowns to replace the mixing tubes, severely reducing production efficiency and increasing production costs.

[0004] Currently, the industry typically mitigates this problem by adjusting the amount of catalyst, adding reaction inhibitors, or lowering the ambient temperature. However, these methods may result in excessively slow curing speeds, implementation difficulties, or ultimately, a decline in mechanical properties. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to extend the operating time of the two-component RTV silicone rubber in the static mixer while ensuring the normal mechanical properties of the two-component RTV silicone rubber.

[0006] The technical solutions for achieving the above-mentioned objectives include the following.

[0007] In a first aspect, the present invention provides a two-component RTV silicone rubber, comprising component A and component B, wherein component A comprises the following raw materials in parts by weight: 100 parts of vinyl polysiloxane and 100 to 140 parts of filler; component B comprises the following raw materials in parts by weight: 100 parts of hydrogen-containing polysiloxane, 15 to 20 parts of crosslinking agent and 0.1 to 0.5 parts of organotin catalyst; and component A and / or component B further comprises 1 to 15 parts of microencapsulated phase change material, wherein the phase change temperature of the microencapsulated phase change material is 25°C to 45°C.

[0008] In a second aspect, the present invention provides a method for preparing the above-mentioned two-component RTV silicone rubber, comprising the following steps: adding the raw material of component A to a planetary mixer in parts by weight and stirring under vacuum until homogeneous to obtain component A; adding the raw material of component B to a planetary mixer in parts by weight and stirring under vacuum until homogeneous to obtain component B.

[0009] A third aspect of the present invention provides the application of the above-mentioned two-component RTV silicone rubber in electronic component encapsulation, new energy vehicle bonding, or LED lighting.

[0010] In this invention, by selecting a specific type of phase change material with a phase change temperature of 25℃~45℃ as the core material and a specific type of wall material, a microencapsulated phase change material is prepared. By controlling the particle size of the microencapsulated phase change material, the skinning time of the A and B components of the prepared bicomponent RTV silicone rubber in the static mixer can be significantly extended, thereby significantly extending the operating time of the silicone rubber, greatly reducing the frequency of downtime cleaning, improving the efficiency of automated production, and having extremely high industrial application value.

[0011] The phase change material used in this invention is microencapsulated and physically isolated from the silicone rubber system. Therefore, it does not interfere with the catalytic addition reaction and has no adverse effect on the storage stability and mechanical strength of the silicone rubber system.

[0012] The two-component RTV silicone rubber of the present invention can be prepared simply by adding microencapsulated phase change material to the existing formula and process, without changing the existing production equipment and process parameters, and is easy to promote. Detailed Implementation

[0013] To facilitate understanding of the present invention, a more complete description will be provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0014] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this invention includes any and all combinations of one or more of the associated listed items.

[0015] Unless otherwise specified, experimental methods in the following examples are generally performed under standard conditions or as recommended by the manufacturer. All commonly used chemical reagents used in the examples are commercially available products.

[0016] In some embodiments of the present invention, a two-component RTV silicone rubber is disclosed, which is composed of component A and component B, wherein component A comprises the following raw materials in parts by weight:

[0017] Contains 100 parts of vinyl polysiloxane

[0018] 100-140 parts of filler

[0019] Component B comprises the following raw materials in parts by weight:

[0020] 100 parts of hydrogen-containing polysiloxane

[0021] 15 to 20 parts of crosslinking agent

[0022] 0.1 to 0.5 parts of organotin catalyst

[0023] The A component and / or B component further include 1 to 15 parts of microencapsulated phase change material, wherein the phase change temperature of the microencapsulated phase change material is 25°C to 45°C. When the microencapsulated phase change material in the two-component RTV silicone rubber system reaches its phase change temperature, it melts and absorbs heat, acting like a "thermal sponge," actively absorbing and storing the heat of reaction of the two-component RTV silicone rubber system. This fundamentally inhibits the temperature surge of the system, breaking the vicious cycle of "exothermic reaction - temperature rise - accelerated reaction - further exothermic reaction," thereby significantly extending the operating time of the two-component RTV silicone rubber.

[0024] In one embodiment, component A and / or component B comprise 3 to 8 parts of microencapsulated phase change material.

[0025] In one embodiment, the phase change temperature of the phase change material in the microencapsulated phase change material is 30°C to 38°C, which is the temperature range that most effectively triggers the thermal management function and absorbs the peak heat in the static mixer.

[0026] In one embodiment, the core material of the microencapsulated phase change material is one or two of paraffin wax and fatty acids; the wall material of the microencapsulated phase change material is one or more of polymethyl methacrylate, polyurea, polyurethane, and melamine-formaldehyde resin.

[0027] In one embodiment, the paraffin is a C16-C28 n-alkane.

[0028] In one embodiment, the paraffin is a C18-C22 n-alkane.

[0029] In one embodiment, the wall material of the microencapsulated phase change material is polyurea.

[0030] In one embodiment, the microencapsulated phase change material has an average particle size of 1 μm to 20 μm and a particle size distribution index of less than 0.3 to ensure that it is uniformly dispersed in the base gel.

[0031] In one embodiment, the average particle size of the microencapsulated phase change material is 3 μm to 10 μm.

[0032] In one embodiment, the average particle size of the microencapsulated phase change material is 4 μm to 6 μm.

[0033] In one embodiment, the volume ratio of component A to component B is 8~12:1.

[0034] In one embodiment, the volume ratio of component A to component B is 9~11:1.

[0035] In one embodiment, the vinyl-containing polysiloxane has a molecular weight of 1000 cp to 20000 cp, a vinyl content of 0.4 wt% to 0.6 wt%, and the hydrogen-containing polysiloxane has a hydrogen content of 0.7 wt% to 0.9 wt%.

[0036] In one embodiment, the vinyl-containing polysiloxane has a molecular weight of 100 cp to 1000 cp and a vinyl content of 0.45 wt% to 0.55 wt%, and the hydrogen-containing polysiloxane has a hydrogen content of 0.75 wt% to 0.85 wt%.

[0037] In one embodiment, the filler is one or more of heavy calcium carbonate, light calcium carbonate, and diatomaceous earth.

[0038] In one embodiment, the filler is heavy calcium carbonate.

[0039] In one embodiment, the organotin catalyst is one or more of dibutyltin dilaurate, dibutyltin diacetate, dioctyltin dilaurate, stannous octoate, and dibutyltin acetylacetonate.

[0040] In one embodiment, the organotin catalyst is stannous octoate.

[0041] In one embodiment, the crosslinking agent is one or more of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-aminoethyl γ-aminopropyltrimethoxysilane, N-β-aminoethyl γ-aminopropyltriethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, 3-isocyanate-propyltrimethoxysilane, glycidyltriethoxysilane, and mercaptopropyltrimethoxysilane.

[0042] In one embodiment, the crosslinking agent is γ-aminopropyltriethoxysilane.

[0043] In other embodiments of the present invention, a method for preparing the above-mentioned two-component RTV silicone rubber is disclosed, comprising the following steps: adding the raw material of component A to a planetary mixer in parts by weight and stirring under vacuum until homogeneous to obtain component A; adding the raw material of component B to a planetary mixer in parts by weight and stirring under vacuum until homogeneous to obtain component B.

[0044] In other embodiments of the present invention, the application of the above-mentioned two-component RTV silicone rubber in electronic component encapsulation, new energy vehicle bonding, or LED lighting is disclosed. For example, in new energy vehicle bonding, by placing the above-mentioned two-component RTV silicone rubber in an automated dispensing device for application, the working time of the two-component RTV silicone rubber in the static mixer is significantly extended, which is more conducive to application.

[0045] The n-eicosane, toluene-2,4-diisocyanate, and ethylenediamine used in the following embodiments of the present invention were purchased from Merck, sodium dodecyl sulfate was purchased from Nanjing Chemical Reagent, and hydrogen-containing polysiloxane was purchased from Tailian.

[0046] The present invention will be described in detail below with reference to specific embodiments.

[0047] Example 1: Preparation of Microencapsulated Phase Change Materials

[0048] Microencapsulated phase change materials were prepared using an in-situ polymerization method, with n-eicosane (phase change temperature approximately 36°C) as the core material and polyurea as the wall material. The specific preparation method is as follows:

[0049] 1. Preparation of primary emulsion (oil phase dispersion)

[0050] (1) Mix 50 g of n-eicosane (oil phase) and 15 g of toluene-2,4-diisocyanate (oil-soluble monomer) evenly in a beaker, and record this mixture as the oil phase. .

[0051] (2) In another beaker, dissolve 1.5 g of sodium dodecyl sulfate in 100 g of deionized water to prepare an aqueous solution.

[0052] (3) Under stirring in a high-speed shear emulsifier (10,000 rpm), the oil phase is... Slowly add it dropwise to the aqueous solution and continue emulsifying for 5 minutes to form a uniform oil / water primary emulsion.

[0053] 2. Constructing a complex emulsion (within the aqueous phase)

[0054] (1) Dissolve 5 g of ethylenediamine (water-soluble monomer) in 50 g of deionized water to prepare an aqueous reaction solution.

[0055] (2) Under gentle stirring (magnetic stirring, 500 rpm), the aqueous phase reaction solution is slowly added dropwise to the oil / water type primary emulsion in step 1. At this time, the system is transformed into a water / oil / water type double emulsion, with the internal aqueous phase droplets containing ethylenediamine and the external oil phase droplets containing n-eicosane and isocyanate.

[0056] 3. Interfacial polymerization reaction

[0057] (1) Transfer the double emulsion to a three-necked round-bottom flask, place it in a constant temperature water bath, and heat it to 60°C.

[0058] (2) The reaction was carried out for 4 hours under nitrogen protection and constant stirring (300 rpm). During this process, toluene-2,4-diisocyanate in the oil phase droplets and ethylenediamine in the inner aqueous phase droplets underwent a polymerization reaction at the oil-water interface to generate polyurea wall material, which gradually encapsulated the n-eicosane core material to form complete microcapsules.

[0059] 4. Post-processing

[0060] After the reaction was complete, the reaction system was allowed to cool naturally to room temperature. The solid product was collected by vacuum filtration and washed three times successively with deionized water and anhydrous ethanol to remove residual emulsifier and unreacted monomers. The washed product was placed in a vacuum drying oven and dried at 40°C for 12 hours to obtain a white powdery microencapsulated phase change material.

[0061] The microencapsulated phase change material prepared in this embodiment has an average particle size of 5 μm and a particle size distribution index of approximately 0.25.

[0062] Examples 2-4, Comparative Examples 1-5

[0063] Components A and B were prepared according to the formulations (parts by weight) shown in Table 1. The vinyl content of the vinyl-containing polysiloxane (molecular weight 5000 cp, prepared using methods known in the art) was 0.5%, the hydrogen content of the hydrogen-containing polysiloxane (molecular weight 350 cp) was 0.8%, and heavy calcium carbonate was used as a reinforcing filler. The microencapsulated phase change material (PCM-MC) was mixed uniformly with the other raw materials of component A under vacuum in a planetary mixer.

[0064] Table 1

[0065]

[0066] Note: The crosslinking agent in Table 1 is γ-aminopropyltriethoxysilane, and the catalyst is stannous octoate. The phase change material in Comparative Example 2 is n-eicosane (unmicroencapsulated), the phase change material in Comparative Example 3 is microencapsulated phase change material, the core material is n-eicosane, and the wall material is acrylic acid (preparation method is the same as in Example 1), the phase change material in Comparative Example 4 is microencapsulated phase change material, the core material is sodium sulfate decahydrate (Merck), and the wall material is polyurea (preparation method is the same as in Example 1); the core material and wall material of the microencapsulated phase change material in Comparative Example 5 are the same as in Example 1, and the preparation method is the same as in Example 1. The difference is that the rotation speed of the high-speed shear emulsifier in step 1 (3) is 3000 rpm, the average particle size of the microencapsulated phase change material is 25 μm, and the particle size distribution index is about 0.35.

[0067] Components A and B were mixed at a volume ratio of 10:1 and injected into a standard static mixer, which was then placed in a constant temperature environment at 35°C. The time from the start of mixing to the point at the outlet of the mixing tube when the colloid lost its fluidity (i.e., formed a skin), and the mechanical properties after complete curing were recorded. The results are shown in Table 2.

[0068] Table 2

[0069]

[0070] As shown in Table 2, compared to Comparative Example 1 without the addition of microencapsulated phase change material, Examples 2-4 with the addition of microencapsulated phase change material exhibited significantly prolonged skinning times for both components A and B in the static mixer. Examples 3 (with 5 parts added) and 4 (with 8 parts added) showed an extension of approximately 130%. Meanwhile, the final mechanical properties of the silicone rubber in Examples 2-4 showed only minor changes compared to Comparative Example 1, fully meeting application requirements. Furthermore, like Comparative Example 1, the silicone rubber in Examples 2-4 exhibited good storage stability and could be stored for 3 months. Among them, the silicone rubber in Example 3 showed the best overall performance.

[0071] The phase change material used in Comparative Example 2 was n-eicosane. No wall material was used to microencapsulate it. The skinning time of its components A and B in the static mixer was as long as 300 s. However, the final mechanical properties of the silicone rubber decreased significantly, and the storage stability also decreased significantly. This is because the phase change material without microencapsulation would leak out from the silicone oil system, destroy the material structure, affect the curing performance, and lead to a decrease in strength and storage stability.

[0072] The microencapsulated phase change materials in Comparative Examples 3 and 4 were prepared using different types of core and wall materials. Compared with Comparative Example 1, the skinning time of components A and B in the static mixer was significantly improved. However, the final mechanical properties and storage stability of the silicone rubber in Comparative Example 3 decreased significantly. This may be because acrylic acid, as the wall material, is brittle, making the microcapsules prone to rupture and thus difficult to maintain its curing performance. The silicone rubber in Comparative Example 4 exhibited excellent skinning time, final mechanical properties, and storage stability of components A and B in the static mixer. However, sodium sulfate decahydrate exhibited supercooling and phase separation. To overcome this defect, a thickener needed to be added to the system. This resulted in a large difference in viscosity between the two components, leading to uneven proportions of components A and B during construction and increasing the difficulty of operation.

[0073] The average particle size and particle size distribution index of the microencapsulated phase change material used in Comparative Example 5 are relatively large, making it difficult to disperse evenly in the silicone oil system and easily forming stress concentration points. Therefore, it will affect the curing performance of silicone rubber and significantly reduce its final mechanical properties.

[0074] The above results indicate that by introducing suitable microencapsulated phase change materials into the RTV silicone rubber system, the main curing properties of the product can be successfully preserved while greatly extending the operating time.

[0075] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0076] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A two-component RTV silicone rubber, characterized in that, It consists of component A and component B, wherein component A comprises the following raw materials in parts by weight: Contains 100 parts of vinyl polysiloxane 100-140 parts of filler Component B comprises the following raw materials in parts by weight: 100 parts of hydrogen-containing polysiloxane 15 to 20 parts of crosslinking agent 0.1 to 0.5 parts of organotin catalyst The A component and / or B component further include 1 to 15 parts of microencapsulated phase change material, wherein the phase change temperature of the phase change material in the microencapsulated phase change material is 25°C to 45°C.

2. The two-component RTV silicone rubber according to claim 1, characterized in that, The core material of the microencapsulated phase change material is one or two of paraffin wax and fatty acids; the wall material of the microencapsulated phase change material is one or more of polymethyl methacrylate, polyurea, polyurethane, and melamine-formaldehyde resin.

3. The two-component RTV silicone rubber according to claim 2, characterized in that, The paraffin is a C16-C28 n-alkane, preferably a C18-C22 n-alkane.

4. The two-component RTV silicone rubber according to claim 3, characterized in that, The core material of the microencapsulated phase change material is a C20 n-alkane, and the wall material of the microencapsulated phase change material is polyurea.

5. The two-component RTV silicone rubber according to claim 1, characterized in that, The microencapsulated phase change material in component A and / or component B is 3 to 8 parts by weight; And / or, the phase transition temperature of the phase change material in the microencapsulated phase change material is 30℃~38℃.

6. The two-component RTV silicone rubber according to any one of claims 1 to 5, characterized in that, The average particle size of the microencapsulated phase change material is 1 μm to 20 μm, and the particle size distribution index is less than 0.3; preferably, the average particle size of the microencapsulated phase change material is 3 μm to 10 μm; more preferably, it is 4 μm to 6 μm.

7. The two-component RTV silicone rubber according to any one of claims 1 to 5, characterized in that, The volume ratio of component A to component B is 8~12:1, preferably 9~11:

1.

8. The two-component RTV silicone rubber according to any one of claims 1 to 5, characterized in that, The vinyl-containing polysiloxane has a molecular weight of 1000 cp to 20000 cp and a vinyl content of 0.4 wt% to 0.6 wt%, preferably 0.45 wt% to 0.55 wt%; the hydrogen-containing polysiloxane has a molecular weight of 100 cp to 1000 cp and a hydrogen content of 0.7 wt% to 0.9 wt%, preferably 0.75 wt% to 0.85 wt%. And / or, the filler is one or more of heavy calcium carbonate, light calcium carbonate, and diatomaceous earth; And / or, the organotin catalyst is one or more of dibutyltin dilaurate, dibutyltin diacetate, dioctyltin dilaurate, stannous octoate, and dibutyltin acetylacetonate; And / or, the crosslinking agent is one or more of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-aminoethylγ-aminopropyltrimethoxysilane, N-β-aminoethylγ-aminopropyltriethoxysilane, γ-glycidyl etheroxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, 3-isocyanate-propyltrimethoxysilane, glycidyltriethoxysilane, and mercaptopropyltrimethoxysilane.

9. A method for preparing the two-component RTV silicone rubber according to any one of claims 1 to 8, characterized in that, Includes the following steps: The raw materials of component A are added to a planetary mixer according to the weight ratio and stirred under vacuum until homogeneous to obtain component A; the raw materials of component B are added to a planetary mixer according to the weight ratio and stirred under vacuum until homogeneous to obtain component B.

10. The application of the two-component RTV silicone rubber according to any one of claims 1 to 8 in electronic component encapsulation, new energy vehicle bonding, or LED lighting.

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