Properties and uses of TDI trimers

TDI trimer

Chemical name: 1,3,5-tris(3-isocyanatomethylpheyl)-1,3,5-triazine-2,4,6-trione.

English name: TDI trimer ;1,3,5-tris(3-isocyanatomethylpheyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione; 1,3-diisocyanatomethyl-benzenemethanone trimer, etc.

Molecular formula is C27H18N6O6, molecular weight is 522.4. CAS number is 9019-85-6 and 26603-40-7, EINECS number is 247-840-6.

General TDI homopolymer (1,3-diisocyanatomethyl-benzene homopolymer) CAS No. 9017-01-0; 2,4-TDI homopolymer (2,4-TDI homopolymer) CAS No. 26006-20-2. TDI trimer products belong to the TDI homopolymer. polymer.

Structural formula:

Physical and Chemical Properties

The common industrial product is the 50% butyl acetate solution of TDI trimer, colorless to light yellow medium-low viscosity liquid, the mass fraction of NCO group is about 8%.Typical properties of TDI trimer products can be found in the product specifications of the relevant manufacturers.

The theoretical NCO mass fraction of pure TDI trimer is 24%, but in fact, the NCO mass fraction of the solid fraction of TDI trimer products is about 16%, which is because the trimer products contain part of the polymer, which reduces the actual content of NCO.

Product grade and performance indicators

The product indexes of relevant manufacturers are shown in Table 1-43 to Table 1-45.

Desmodur RC is a TDI trimer-type polyisocyanate (TDI isocyanurate), a colorless to slightly yellowish, low-viscosity liquid suitable for use as a cross-linking agent for thermoplastic polyurethane adhesives and rubber adhesives, and especially suitable for bonding light-colored rubber materials. For hydroxy polyurethane adhesive or neoprene adhesive with 20% solid content, the dosage of RC is 4-7 mass parts/100 mass parts of adhesive.

The low free monomer content TDI trimers PTD-50 and PTD-60 (solid content 50% and 60% respectively) of Beijing Haohua Fine Chemical Corporation have a free TDI content of 1.0% and less than 1.2% respectively. the viscosity of PTD-50 is 20-80 mPa.s. The solvent is ethyl acetate/butyl acetate, and the NCO mass fraction is (7.4±0.2) %. The free TDI content of modified TDI trimers PTD-2450 and PTD-270 (50% and 70% solids, respectively) was 1.0% and 1.4% or less, respectively.

Aknate TR -50 of Aekyung Chemical Co., Ltd. is a TDI trimer with 50% solids, solvent of ethyl acetate or butyl acetate (according to customer’s needs), NCO mass fraction of 7.8% to 8.20%, viscosity (25°C Gardner) T-V (50% in butyl acetate), or G-J (50% in ethyl acetate), and TDI free monomer of < 1.0%.

The fast-drying TDI trimer matte curing agent 505N from Taiwan’s Jayhwa Chemical Co. is also 50% solids, with an NCO mass fraction of 7.5% to 8.5% and free TDI < 1.5%.

Characteristics and Uses

With high reactivity, TDI trimer is generally used as a curing agent for fast-drying two-component polyurethane coatings, with applications including furniture paint and industrial on-line coating; it can also be used as a curing agent component for room-temperature curing two-component polyurethane adhesives. It gives the paint film outstanding fast drying and filling properties, high hardness and good heat resistance. The disadvantage is that it is not light resistant and will yellow.