Solution Guide: Setting Up the SXJ-15 Vacuum Planetary Mixer for Silicone Sealant Development

Establishing a reliable process for silicone sealant development requires careful consideration of equipment selection, process parameters, and operational procedures. This guide outlines the key steps for utilizing the SXJ-15 Vacuum Planetary Mixer for high-quality silicone sealant formulation and pilot production.

Step 1: Material Preparation and Formulation

The first step in successful silicone sealant production is proper material preparation. Silicone sealant formulations typically include:

• Base polymer: Polydimethylsiloxane (PDMS) or other silicone polymers

• Filler: Fumed silica, calcium carbonate, or other reinforcing fillers

• Crosslinkers: Alkoxy silanes, acetoxy silanes, or other curing agents

• Catalysts: Tin or titanium compounds for condensation cure

• Additives: Adhesion promoters, pigments, UV stabilizers, or thixotropic agents

All materials should be accurately weighed and pre-conditioned to remove moisture that could affect cure properties. For fumed silica, controlled addition during mixing prevents dust and ensures uniform dispersion. For moisture-sensitive systems, all materials should be stored in sealed containers under dry conditions.

Step 2: Planetary Mixing and Dispersion

The SXJ-15's combination of low-speed kneading and high-speed dispersion is ideal for silicone sealant preparation. The standard process involves:

1. Initial charging: Add polymer base and plasticizers to the mixing vessel

2. Filler addition: Introduce fillers and additives under vacuum

3. Low-speed mixing: Operate the planetary blades at 20-43 rpm for initial incorporation

4. High-speed dispersion: Activate the 2.2KW disperser at 1,500-2,980 rpm for 30-90 minutes

5. Final mixing: Continue low-speed mixing under vacuum for deaeration

The PTFE scraper ensures continuous wall cleaning, preventing material buildup that could affect heat transfer and mixing uniformity . The entire process should be performed under -0.09 MPa vacuum to remove entrapped air and prevent moisture contamination.

Step 3: Process Optimization and Quality Control

Achieving consistent sealant quality requires careful parameter control. The SXJ-15's parameters should be optimized for each formulation:

Quality control should include viscosity measurements (using a rheometer), filler dispersion assessment, and visual inspection for agglomerates and bubbles. The SXJ-15's 15L capacity allows for multiple test samples, enabling comprehensive characterization without excessive material consumption.

Step 4: Discharge and Downstream Processing

After mixing, the sealant must be discharged for packaging. The SXJ-15 offers two discharge options:

1. Direct discharge: Remove the mixing vessel and transfer sealant manually

2. Optional presser: Use the extrusion system for controlled, contamination-free discharge

The presser attachment is particularly valuable for high-viscosity sealants, as it applies uniform pressure to extrude the material without introducing air bubbles . The discharged sealant should be transferred to cartridges, sausages, or other packaging within a controlled timeframe to prevent moisture absorption.

Step 5: Cleaning and Maintenance

Proper cleaning is essential for maintaining the SXJ-15's performance. The electric lifting system provides easy access to the mixing vessel, disperser, and blades . For silicone sealant cleaning, protocols should include:

1. Solvent rinse: Use appropriate solvent (e.g., white spirit, isopropanol) to dissolve residual sealant

2. Mechanical cleaning: Scrape and wipe all contact surfaces

3. Inspection: Check PTFE scraper wear and blade clearances

4. Seal maintenance: Verify mechanical seal integrity for vacuum performance