Single-component room temperature vulcanized silicone rubber spray paint and preparation method thereof

Abstract

The invention discloses a single-component room temperature vulcanized silicone rubber spray paint and a preparation method thereof, and solves the problems of poor storage stability, complex construction and easy blockage in filling of a system product. The formula comprises the following components: 60-70% of alpha, omega-dihydroxy polydimethylsiloxane, 5-10% of hydrophobic fumed silica, 5-10% of silane modified mica powder, the dielectric strength of which is greater than or equal to 60 kV / mm, a pigment, tetraethoxysilane, dibutyltin dilaurate, dimethyl silicone oil, 120 # solvent oil and a propellant. During preparation, the moisture of the system is controlled through raw material drying, vacuum mixing and three-stage filling processes (semi-finished product filling, solvent flushing and pipeline sealing by excessive dimethyl silicone oil). The storage period of the product reaches 24 months, the breakdown voltage is larger than 25 kV / mm, the self-spraying tank design supports one-hand operation, and the product is suitable for the scenes of electrical equipment insulation, pollution flashover prevention and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of self-spraying paint materials, and specifically provides a one-component room temperature vulcanizing silicone rubber self-spraying paint and a preparation method thereof, which are applicable to the convenient construction of insulating, anti-pollution flashover, moisture-proof and sealing coatings. Background Art

[0002] One-component room temperature vulcanizing silicone rubber coatings cure rapidly through moisture, and have characteristics such as high and low temperature resistance, insulation, weather resistance, flexibility and environmental protection. They are widely used in fields such as electricity, construction, electronics, automobiles, new energy, medical treatment, industrial molds and aerospace, and are a multi-functional material with strong adaptability, safety and reliability. Traditional one-component room temperature vulcanizing silicone rubber coatings use an alkoxysilane cross-linking system, which relies on environmental moisture to initiate hydrolysis and condensation reactions to form a film, but has the following defects: 1. Poor storage stability: Moisture penetration easily leads to pre-vulcanization or abnormal viscosity; 2. High construction complexity: It relies on heavy equipment such as airless sprayers and air compressors, and has poor portability; 3. Defects in the filling process: In the existing filling method, the pipeline is easily blocked due to the curing of silicone rubber and cannot be used. Summary of the Invention

[0003] The present invention solves the above problems through formula optimization and filling process innovation, and the technical solutions are as follows: 1. Design of the formula system (by weight percentage):

[0004] Component Function Content Range Preferred Value α,ω-dihydroxypolydimethylsiloxane (1000 - 5000 mPa·s) Base Film-forming Substance 60-70% 65% Fumed silica (hydrophobic, specific surface area 100 - 400 m² / g) Reinforcement and Thickening Agent 5-10% 8% Tetraethyl orthosilicate (TEOS) Cross-linking Agent 2-4% 3% Dibutyltin dilaurate Catalyst 0.1-0.3% 0.2% Silane-modified mica powder (D50 = 20 - 50 μm) Dielectric Enhancement and Filler 5-10% 7% Pigment Pigment 3-5% 3% 120# Solvent Oil Diluent 3-5% 4% Dimethyl silicone oil (50 - 500 mPa·s) Leveling and Moisture Barrier 3-5% 4% Nitrogen / Dimethyl Ether Propellant Balance Balanced to 100% 2. Preparation Method

[0005] Mix dry fumed silica, silane-modified mica powder, pigment with α,ω-dihydroxypolydimethylsiloxane, tetraethyl orthosilicate, dibutyltin dilaurate, stir at 50 °C for 2 h under vacuum conditions (5 - 15 kPa), and pass through a 200-mesh sieve to obtain a semi-finished product; Three-stage filling process: a. Quantitatively fill the semi-finished product into a self-spray can containing a propellant; b. Inject 120# solvent oil to rinse the pipeline residue; c. Overfill 3 - 10 g of dimethyl silicone oil on the basis of the formula, and use its hydrophobicity to seal the filling pipeline; Seal the canning port with an elastic rubber cap to further isolate moisture penetration. 3. Preferred Solution

[0006] Fumed silica, silane-modified mica powder and pigment need to be dried at 150 °C for 4 h before feeding; The viscosity of α,ω-dihydroxypolydimethylsiloxane is preferably 3000 mPa·s; The specific surface area of fumed silica is preferably 200 m² / g; The dielectric strength of silane-modified mica powder is >60 kV / mm, improving the insulation performance, and D50 = 25 μm; The viscosity of the leveling agent dimethyl silicone oil is preferably 100 mPa·s. Overfilling forms a water molecule barrier to control the system moisture ≤50 ppm; The propellant is nitrogen with a pressure of 0.3 - 0.5 MPa to ensure the atomization effect. 4. Beneficial effects

[0007] Storage stability: The moisture-absorbing powder materials are dried to avoid introducing moisture from the source. The innovative three-stage filling process, combined with the hydrophobic and leveling effects of dimethyl silicone oil, constructs a multi-layer moisture barrier system, effectively blocking the moisture intrusion path and extending the product's storage period to 24 months, which is a significant improvement compared to traditional products; Construction convenience: The self-spray can design is adopted, eliminating the need for professional equipment, enabling single-handed operation, being simple and convenient, reducing the construction difficulty and cost, and being suitable for construction in various complex scenarios and hard-to-reach areas; Optimization of electrical performance: By adding silane-modified mica powder, the breakdown voltage of the paint film is >25 kV / mm, significantly improving the insulation performance of the product and expanding its application fields to those with high electrical performance requirements such as high-voltage insulation; Optimization of production process: Vacuum stirring is used during production, which can effectively defoam and extract moisture to ensure product quality; The method of post-filling the diluent avoids the extraction of 120# solvent oil diluent in a vacuum, thus ensuring the viscosity stability of the material and improving the controllability of the production process and the stability of product quality. Specific implementation manners

[0008] The following will describe the present invention in detail in combination with specific implementation methods. The following is the test design of the embodiment: Test Group Material Treatment Whether to Evacuate Filling Process Filler Type Test Item Example 1 Powder Drying Treatment Yes Three-stage Filling Process Silane-modified mica powder Storage Period and Breakdown Voltage Example 2 Powder Drying Treatment Yes Direct Filling Silane-modified mica powder Storage Period and Breakdown Voltage Example 3 Powder Not Dried No Three-stage Filling Process Silane-modified mica powder Storage Period and Breakdown Voltage Example 4 Powder Drying Treatment Yes Three-stage Filling Process Modified Nano Calcium Carbonate Storage Period and Breakdown Voltage

[0009] Example 1: According to the preferred value ratio and the indicators in the preferred scheme in the formulation system (by weight percentage), dry fumed silica, silane-modified mica powder, pigments are mixed with α,ω-dihydroxypolydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dilaurate, stirred at a constant temperature of 50°C for 2 h under vacuum conditions, and passed through a 200-mesh sieve to obtain semi-finished products. After filling 40 bottles of the semi-finished products according to the three-stage filling process, 5 bottles are tested every 3 months to record the clogging or normal use situation, and the breakdown voltage of the paint film of the last normally used sample is tested.

[0010] Example 2: According to the preferred value ratio and the indicators in the preferred scheme in the formulation system design (by weight percentage), mix the dry fumed silica, silane-modified mica powder, pigment with α,ω-dihydroxypolydimethylsiloxane, tetraethyl orthosilicate, dibutyltin dilaurate, dimethyl silicone oil, and 120# solvent oil, stir at a constant temperature of 50 °C for 2 h under vacuum conditions, sieve through a 200-mesh sieve to obtain semi-finished products. After directly filling 40 bottles of the semi-finished products, test 5 bottles every 3 months to record the clogging or normal use situation, and test the breakdown voltage of the paint film of the last sample with normal use.

[0011] Example 3: According to the preferred value ratio and the indicators in the preferred scheme in the formulation system design (by weight percentage), mix the undried fumed silica, silane-modified mica powder, pigment with α,ω-dihydroxypolydimethylsiloxane, tetraethyl orthosilicate, dibutyltin dilaurate, stir at a constant temperature of 50 °C for 2 h, sieve through a 200-mesh sieve to obtain semi-finished products. The semi-finished products are filled according to the three-stage filling process. After filling 40 bottles, test 5 bottles every 3 months to record the clogging or normal use situation, and test the breakdown voltage of the paint film of the last sample with normal use.

[0012] Example 4: According to the preferred value ratio and the indicators in the preferred scheme in the formulation system design (by weight percentage), mix the undried fumed silica, modified nano-calcium carbonate equivalent to silane-modified mica powder, pigment with α,ω-dihydroxypolydimethylsiloxane, tetraethyl orthosilicate, dibutyltin dilaurate, stir at a constant temperature of 50 °C for 2 h under vacuum conditions, sieve through a 200-mesh sieve to obtain semi-finished products. The semi-finished products are filled 40 bottles according to the three-stage filling process, and then test 5 bottles every 3 months to record the clogging or normal use situation, and test the breakdown voltage of the paint film of the last sample with normal use.

[0013] The storage stability test results are as follows (in the test, all 5 bottles are sprayed normally each time as "normal", and any 1 bottle is clogged as "clogged"): Storage Time / Group 3 months 6 months 9 months 12 months 15 months 18 months 21 months 24 months Example 1 Normal Normal Normal Normal Normal Normal Normal Normal Example 2 Blocked Blocked Blocked Blocked Blocked Blocked Blocked Blocked Example 3 Normal Blocked Blocked Blocked Blocked Blocked Blocked Blocked Example 4 Normal Normal Normal Normal Normal Normal Normal Normal

[0014] The breakdown voltage results of the paint film of the last sample with normal use are as follows: Group Example 1 Example 2 Example 3 Example 4 Breakdown Voltage / (kV / mm) 26.7 - 26.5 20.3 Key conclusions

[0015] Process synergy effect: Drying treatment (150 °C, 4 h) + vacuum stirring (moisture ≤ 50 ppm) + three-stage filling process are necessary conditions to ensure a 24-month storage period; The hydrophobic sealing effect of excessive dimethyl silicone oil (3 - 10 g) in the three-stage filling is significant for anti-clogging effect.

[0016] Influence of material selection: Silane-modified mica powder (D50 = 25 μm, dielectric strength > 60 kV / mm) is the core filler for improving the breakdown voltage; Silane-modified mica powder has an obvious effect of enhancing the insulation performance of the material compared with conventional fillers.

[0017] Verification of process defects: Direct filling causes sulfurization blockage of pipeline residues (Comparative Example 1 vs. Comparative Example 2); Moisture introduced by undried raw materials causes pre-sulfurization (Comparative Example 1 vs. Comparative Example 3); This experimental system completely verifies the effectiveness of the "raw material pretreatment - formulation optimization - filling innovation" trinity technical solution proposed in the patent. In particular, the persuasiveness of the innovation points is strengthened through multi-dimensional comparative experiments.

Claims

1. A one-component room temperature vulcanized silicone rubber self-spray paint, characterized in that: The following components are included by weight percentage: α,ω-dihydroxypolydimethylsiloxane (viscosity 1000-5000 mPa·s) 60-70%; Hydrophobic fumed silica (surface area 100-400 m² / g) 5-10%; Tetraethyl orthosilicate (TEOS) 2-4%; Dibutyltin dilaurate 0.1-0.3%; Silane-modified mica powder (D50=20-50 μm, dielectric strength ≥60 kV / mm) 5-10%; Pigment 3-5% 120# solvent oil 3-5%; Dimethyl silicone oil (viscosity 50-500 mPa·s) 3-5%; Nitrogen / dimethyl ether balance; The silane-modified mica powder and the hydrophobic fumed silica are dried at 150°C for 4 hours before feeding, and the spray paint is prepared by a three-stage filling process, including: a. quantitatively filling the mixed semi-finished product into a spray can containing a propellant; b. injecting 120# solvent oil to flush the filling pipeline residue; c. overfilling 3-10 g of dimethyl silicone oil to form a hydrophobic barrier to close the pipeline.

2. The method for preparing the one-component room temperature vulcanized silicone rubber self-spray paint according to claim 1, characterized in that: The following steps are involved: (1) Mix the dried hydrophobic fumed silica, silane-modified mica powder, pigment, α,ω-dihydroxypolydimethylsiloxane, tetraethyl orthosilicate, and dibutyltin dilaurate, stir at 50°C for 2 h under vacuum conditions (5-15 kPa), and pass through a 200-mesh sieve to obtain a semi-finished product; (2) Use a three-stage filling process: a. Fill the semi-finished product into a self-spray can containing nitrogen propellant; b. Inject 120# solvent oil to flush the pipeline; c. Overfill with 3-10 g of dimethyl silicone oil; (3) Seal the canning port with an elastic rubber cap to isolate moisture from penetrating.

3. Dependent claims.

4. The one-component room temperature vulcanized silicone rubber self-spray paint according to claim 1, characterized in that: The viscosity of the α,ω-dihydroxypolydimethylsiloxane is 3000 mPa·s; The specific surface area of ​​the hydrophobic fumed silica is 200 m² / g; The D50 particle size of the silane-modified mica powder is 25 μm.

5. The one-component room temperature vulcanized silicone rubber self-spray paint according to claim 1, characterized in that: The viscosity of the dimethyl silicone oil is 100 mPa·s; The pressure of the nitrogen propellant is 0.3-0.5 MPa.

6. The preparation method according to claim 2, characterized in that: The amount of the overfilled dimethyl silicone oil is 5-8g.