Silicone sealants are high-performance elastomeric materials based on polydimethicone (PDMS). By blending PDMS with crosslinkers, remplissage, and catalysts, they cure into flexible, durable sealing layers—either at room temperature or with heat. Their exceptional weather resistance, stabilité chimique, and adhesion make them indispensable across industries. But how do you classify them, choose the right type for your project, et éviter les erreurs courantes?
1. Classification of Silicone Sealants: Une comparaison claire
Silicone sealants are categorized by three core factors: composant, curing mechanism, et fonction. The table below simplifies these classifications to help you identify the right fit:
| Classification Basis | Taper | Caractéristiques clés | Cas d'utilisation idéaux |
| By Component | Single-component | No mixing needed; cures by absorbing air moisture; facile à utiliser | Quick repairs (Par exemple, home sink waterproofing), small-area construction (Par exemple, glass fish tank gluing) |
| Two-component | Requires mixing Component A (silicon hydroxyl group) et Component B (silane crosslinker); deep curing ability | Large-scale engineering (Par exemple, curtain wall sealing), high-demand projects (Par exemple, high-temperature pipe joints) | |
| By Curing Mechanism | Condensation-type | Releases small-molecule by-products (Par exemple, éthanol) Pendant le durcissement; a besoin de ventilation | Construction générale (Par exemple, concrete expansion joints), scénarios non alimentaires/médicaux |
| Type d'additif | Aucun sous-produit; écologique; répond aux normes de sécurité strictes | Applications de qualité alimentaire (Par exemple, scellage de machines alimentaires), dispositifs médicaux (Par exemple, pièces en contact avec la peau) | |
| Par fonctionnalité | Usage général | Propriétés de base équilibrées (adhésion, flexibilité) | Entretien quotidien de la maison (Par exemple, installation de sanitaires) |
| Ignifuge | Réussit les tests de sécurité incendie; inhibe la combustion | Équipement électrique (Par exemple, revêtement de circuits imprimés), construire des barrières coupe-feu | |
| Conducteur thermique | Transfère efficacement la chaleur; maintient l'isolation | Composants électroniques (Par exemple, joints de dissipateur de chaleur) | |
| À haute résistance | Résistance supérieure à la traction et au cisaillement | Joints structurels (Par exemple, soudures de carrosserie automobile) | |
| Faible volatilité | Minimal volatile organic compounds (Chou) | Indoor sensitive environments (Par exemple, hospital operating rooms) |
2. Core Performance Characteristics: Why Silicone Sealants Stand Out
What makes silicone sealants superior to other sealing materials (Par exemple, acrylique, polyuréthane)? Their performance advantages are rooted in their chemical structure, Comme indiqué ci-dessous:
- Broad-Spectrum Temperature Resistance: Withstands extreme temperatures from -60°C à +250°C (short-term up to 300°C). This makes them ideal for outdoor pipelines, engine compartments, and other high/low-temperature alternating environments—unlike acrylic sealants, which crack at -20°C.
- Long-Lasting Aging Resistance: Resists UV radiation, ozone, humidité, and salt spray. In outdoor applications (Par exemple, murs-rideaux), their service life exceeds 10 années—far longer than polyurethane sealants (3–5 ans).
- Reliable Electrical Insulation: Boasts a high breakdown voltage (>20kV/mm) and stable dielectric constant. It protects electrical components (Par exemple, transformateurs) from moisture and dust without compromising insulation.
- Balanced Flexibility & Adhésion: Après guérison, it maintains adjustable Dureté des rives (20–80A) and can withstand up to 500% elongation without cracking. It adheres firmly to metals, verre, céramique, and plastics—even with thermal expansion or vibration.
- Biocompatibilité: Medical-grade silicone sealants meet FDA standards, supporting skin contact and short-term implantation (Par exemple, joints de dispositifs médicaux). No other common sealant material offers this combination of safety and performance.
3. Step-by-Step Application Guide: Ensure Success Every Time
Improper application can ruin even the best silicone sealant. Suivez ce linéaire, easy-to-follow process to achieve a durable seal:
Étape 1: Préparation de la surface (Critical for Adhesion)
- Clean the substrate (métal, verre, etc.) with a solvent (Par exemple, acétone) Pour enlever l'huile, poussière, and release agent residues.
- Dry the surface completely—moisture on non-porous substrates (Par exemple, verre) will weaken adhesion.
- For low-adhesion substrates (Par exemple, some plastics), appliquer un special primer and let it dry for 15–30 minutes before applying the sealant.
Étape 2: Sealant Application (Control Thickness & Forme)
- Load the sealant into a caulking gun. For single-component types, cut the nozzle at a 45° angle to match the joint width.
- Apply the sealant in a continuous, even bead. Le single-application thickness should not exceed 6mm—thicker layers will not cure completely internally, leading to soft spots.
- Use a tool (Par exemple, a silicone smoothing tool) to shape the bead within 5–10 minutes (before surface curing) for a neat finish.
Étape 3: Durcissement & Post-Care (Évitez les pièges courants)
- Let the sealant cure in a well-ventilated area. Note: High humidity speeds up surface drying but slows deep curing—allow 24–48 hours for full curing (longer in cold/dry conditions).
- Avoid touching or disturbing the sealant during curing.
- Clean up uncured sealant with acetone; cured sealant must be cut or scraped off.
4. Guide de sélection: Match Sealant to Your Exact Needs
Choosing the wrong silicone sealant wastes time and money. Use this table to align the product with your scenario:
| Demand Scenario | Recommended Sealant Type | Key Performance Indicators to Check |
| Interior decoration (Par exemple, cadres de fenêtre, articles sanitaires) | Neutre monocomposant | Non corrosif, faible odeur, Dureté Shore 30–50A |
| Étanchéité des tuyaux à haute température (Par exemple, chaudières industrielles) | Bi-composant haut module (type additif) | Résistance à la chaleur >200° C, résistance à la traction >3MPA |
| Composants électroniques (Par exemple, cartes de circuits imprimées, capteurs) | Qualité ignifuge additive | Indice d'isolation CTI ≥600 V, retardateur de flamme UL94 V-0 |
| Réparation de machines alimentaires (Par exemple, Convoyeur, joints de réservoir) | Transparent certifié FDA | Conforme aux normes nationales de sécurité alimentaire GB/T, pas de COV |
| Travaux extérieurs (Par exemple, murs-rideaux, joints de toiture) | Bi-composant résistant aux intempéries | Résistance aux UV >10 années, résistance au brouillard salin >5000 heures |
5. Idées fausses courantes: Debunking Myths
De nombreux utilisateurs font des erreurs en raison de fausses hypothèses. Below are three key myths and the facts:
- Mythe 1: “All silicone sealants are high-temperature resistant.”
Fait: Temperature resistance depends on the formula. Normal-grade sealants only work below 80°C—only high-temperature grades (Par exemple, phenyl silicone-based) handle 200°C+.
- Mythe 2: “Acid glass glue = silicone sealant.”
Fait: Acidic glass glue is a type of silicone sealant but contains acetic acid. It is highly corrosive and cannot be used on metals (causes rust) or marble (etches surfaces). Choose neutral silicone for these substrates.
- Mythe 3: « Application plus épaisse = meilleure étanchéité. »
Fait: Épaisseur excessive (>6MM) provoque un durcissement interne incomplet, conduisant à une mauvaise durabilité. Pour joints larges, appliquer plusieurs couches fines (permettant à chacun de guérir partiellement) plutôt.
6. Yigu Technology’s Perspective on Silicone Sealants
À la technologie Yigu, nous considérons les mastics silicone comme des « protecteurs invisibles » pour les infrastructures et les produits. Pour les clients automobiles, notre mastics bi-composants à haute résistance réduire la corrosion des soudures de carrosserie en 80% et résiste à des températures du compartiment moteur jusqu'à 250°C. Pour les fabricants de dispositifs médicaux, notre Scellants de type additif certifiés FDA répondre à des normes strictes de biocompatibilité, supporting safe skin contact and short-term implantation.
Regarder vers l'avenir, we will focus on two innovations: 1) Développement low-VOC eco-friendly sealants to cut carbon emissions by 25% et 2) Enhancing the thermal conductivity of electronic-grade sealants to improve heat dissipation efficiency by 30%. Our goal is to make silicone sealants more sustainable, fiable, and tailored to industry-specific needs.
FAQ
- How long does silicone sealant take to fully cure, and what affects curing time?
Full curing takes 24–48 hours under standard conditions (25° C, 50% humidité). High humidity accelerates surface drying but slows deep curing; basses températures (<10° C) extend curing time to 72+ heures. Always check the product datasheet for specific times.
- Can silicone sealant be painted over, and if so, comment?
Most silicone sealants are non-paintable due to their smooth surface. For paintable needs, choose “paintable silicone sealants” (formulated with special additives). Attendez 72 hours for full curing, then use acrylic or latex paint—avoid oil-based paints (they peel off).
- How to store unused silicone sealant to extend its shelf life?
Seal the nozzle tightly (use a cap or tape) and store in a cool, lieu sec (5–25 ° C) away from heat sources and strong oxidants. Unopened single-component sealants have a shelf life of 12 mois; opened ones should be used within 1 mois. Two-component sealants must be stored separately to prevent premature curing.