I. Raw Materials for Neutral Sealant

1. Base Polymer
   α,ω-Dihydroxy polydimethylsiloxane: The core base resin provides flexibility and adhesion, with a viscosity range typically between 50,000–80,000 mPa·s (25℃)17.

   Methyl silicone oil: A plasticizer that adjusts rheology and extrudability, with a viscosity of 100–500 mPa·s (25℃), used at 20–35 parts14.

2. Fillers and Reinforcers
   Modified silica: A key reinforcing filler that enhances mechanical properties (e.g., tensile strength). It needs to be synthesized by reacting hydrophilic silica with antifungal agents (e.g., isothiazolinone) at 100–150℃, used at 8–25 parts17.

   Nano titanium dioxide: An inorganic antifungal agent that provides long-lasting antibacterial properties (e.g., model JWN-A01), used at 4–10 parts7.

3. Crosslinking System
   Crosslinking agents: Ketoxime silanes (e.g., methyltributylketoxime silane, vinyltributylketoxime silane), used at 9–15 parts, which release ketoxime during curing, non-corrosive14.

   Silane coupling agents: Enhance adhesion (e.g., KH-550, KH-560), used at 2–5 parts17.

4. Catalysts and Auxiliary Agents
   Organic tin catalyst: Dibutyl tin dilaurate (0.015–0.05 parts), accelerates curing7.

   Antifungal agents: Isothiazolinone types (composite BIT/OIT/MIT), achieve long-lasting antifungal effects through chemical bonding with modified silica7.

⚗️ II. Raw Materials for Acidic Sealant

1. Base Polymer
   α,ω-Dihydroxy polydimethylsiloxane: Similar to neutral sealant, but typically has a lower viscosity (40,000–60,000 mPa·s) to accommodate acidic systems8.

2. Crosslinking Agent
   Methyl triacetoxysilane: The core crosslinking agent that releases acetic acid during curing, providing rapid curing characteristics (surface dry ≤ 20 minutes), used at 10–15 parts8.

3. Fillers and Aids
   Fumed silica: A reinforcing filler (unmodified), used at 15–25 parts, enhances sag resistance8.

   Calcium carbonate/silica micro powder: A low-cost filler, but excessive amounts can lead to shrinkage (low-grade sealants can shrink up to 30%)5.

   Acetic acid regulator: Controls the release rate of acid, reducing corrosion risks to metals58.

4. Functional Additives
   Weathering agents: UV absorbers (e.g., benzotriazole types), used in outdoor scenarios (e.g., curtain wall sealants)8.

   Pigments: Iron oxide-based colorants to meet architectural decoration requirements. Neutral sealant: Based on modified antifungal fillers and ketoxime crosslinking, suitable for high hygiene requirement scenarios (e.g., kitchens and bathrooms), with relatively high raw material costs but environmentally friendly properties17.

   Acidic sealant: Relies on acetoxy crosslinking and low-cost fillers, advantageous for rapid curing and high bonding strength (curtain wall structural adhesive), but poses corrosion risks to metal substrates.