Comparison of common coupling agents and titanate coupling agents

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Comparison of common coupling agents and titanate coupling agents: The following are several commonly used coupling agent products available on the market today. 1. Silane coupling agents 2. Titanate coupling agents 3. Aluminate coupling agents 4. Zirconate coupling agents 5. Aluminum-titanium composite series 6. Other series (borate type, aluminum-zirconium composite type, etc.) I. Comparison between silane coupling agents and titanate coupling agents: Silane coupling agents are effective only with fillers that contain silicon, whereas titanate coupling agents can be used with a variety of fillers. They also work well with a wide range of resins. Their function is not limited to enhancing the strength of composite materials; they can also impart a certain degree of flexibility. For more details, see Tables 1, 2, and 3. Table 1.1 Comparison of Titanate Coupling Agents and Silane Coupling Agents
Titanate Silane
① Compatibility with resins ② Compatibility with inorganic fillers
③ Primary performance aspect ④ Others

Thermosetting and thermoplastic resins Wide range of applications Does not increase strength Provides flexibility Primarily affects processing properties
Only suitable for thermosetting resins Limited range of applications Increases strength Provides rigidity Clear advantages and disadvantages

Table 1.2 Comparison of the Chemical Structures of Titanates and Silanes
Symbol Details
Titanate: R1-O-Ti-(O-X1-R2-Y)n
Silane: (R1-O)2-Si-R2-Y
R-O: Alkoxy group 1 3
Alkoxy chelating function: Present Absent
Instability: Requires elimination of immediate alcohol by-products when needed Possible Not possible
Ability to form a monolayer: Possible Not possible
Hydrolysis resistance: Low Moderate to high
Reaction with CaCO3: Possible Not possible
Adverse effects at excess amounts: Common Occasional
– (Ester transfer reaction – X-bonded polyesters): Possible Not possible
X-bonding without the aid of unsaturated structures: Possible Not possible
X1: Adjacent group function: Present Absent
Thermal stability when necessary: Possible Not possible
Sulfonyl group – Thixotropy: Possible Not possible
Phosphate group – Flame retardancy: Possible Not possible
Phosphite group – Anti-aging effect: Possible Not possible

R2: Length of R2 group Long to short Short
Effect on reducing viscosity: Significant None to moderate
Effect on improving the impact resistance of thermoplastics: Excellent None to moderate
Flash point: High to moderate Low

Y: Functional groups 3 1
n: Tri-functionality: Present Mon-functionality
Hydrolysis stability: Good to excellent Good to poor

Table 1.3 Comparison of the Effects of Coupling Agents on Fillers
Silane coupling agents Titanate coupling agents
Agents with excellent effects: Most inorganic fillers such as silica, glass, calcium carbonate, barium sulfate, aluminum hydroxide, titanium dioxide, etc.
Agents with certain effects: Talc powder, iron powder, alumina, aluminum hydroxide, magnesium oxide, calcium oxide, mica, silica, glass, etc.
Agents with limited effects: Asbestos, iron oxide, titanium dioxide, zinc oxide, talc powder, carbon black, wood powder
Agents with no effect: Calcium carbonate, calcium sulfate, barium sulfate, graphite, boron, graphite

II. Comparison of Titanate Coupling Agents, Zirconate Coupling Agents, and Aluminate Coupling Agents
Aluminum has greater reactivity than titanium and zirconium; due to its high reactivity, reactions often occur during storage, resulting in a short shelf life. The heat resistance of zirconium coupling agents is greater than that of titanium and aluminum coupling agents. For details, see Table 1.4. Table 1.4 Comparison of titanate, zirconate, and aluminate coupling agents. Properties: Order; Reaction activity; Storage stability; Chemical resistance; Price; Types: (High) Aluminum > Titanium ≥ Zirconium (Low); (Good) Titanium = Zirconium > Aluminum; (Poor). (Good) Titanium = Zirconium > Aluminum; (Poor). (Low) Aluminum > Titanium > Zirconium; (High). (Many) Titanium > Aluminum > Zirconium; (Few). Based on the above comparisons, as well as the fact that titanium-based coupling agents are widely used in both domestic and international markets – where they have a wide distribution range and high sales volumes – their main characteristics are as follows: 1. Wide range of applications (plastics, rubber, coatings, inks, magnetic materials, pigments, fillers) ； 2. A wide variety of grades is available (Kenrich Company in the United States lists nearly sixty different grades, and there are also dozens of grades available in China) ； 3. Stable storage (e.g., water-soluble varieties can be stored for several years) ； 4. Moderate price (definitely lower than silicon-based ones, slightly higher than aluminum-based ones).