Multi Skilled Isocyanates In The Chemical Raw Material Industry

Isocyanates

A versatile expert in the field of chemical raw materials

Isocyanates

Multi skilled chemical raw materials

Does isocyanate sound a bit unfamiliar? In fact, it is a general term for various esters of isocyanates, widely used in multiple fields such as home appliances, automobiles, construction, footwear, furniture, and adhesives. It has a wide variety of types, classified by the number of NCO groups, such as monoisocyanates, diisocyanates, and polyisocyanates, and each has its unique uses and charm.

In the family of isocyanates, diisocyanate is the most core member. It includes toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI), and lysine diisocyanate (LDI). These different types of diisocyanates each have unique chemical properties and application areas.

For example, hexamethylene diisocyanate (HDI) has become the preferred choice in industrial paints, adhesives, and other fields due to its low viscosity, high hardness, and high gloss; Aliphatic isocyanates are widely used in matte coatings, floor paints, and other applications due to their good extinction, easy dispersion, and long activation period.

01 High activity: the ability to react with all things

The key to why isocyanates stand out among many chemical substances is their unique chemical reactivity. The unsaturated bonds in the isocyanate structure give it high activity. It can not only react with polyols and polyethers to form polyurethane elastomers, but also undergo wonderful chemical reactions with amine compounds, water, carboxyl compounds, and so on. Every reaction is an improvement in performance.

PART / 01

Reaction with hydroxyl compounds

Reacts with active hydroxyl compounds such as polyols, polyethers, polyesteramides, castor oil, etc. to form aminomethyl esters.

PART / 02

Reaction with amino containing compounds

Reacting with amine compounds usually produces substituted urea, and if further reaction occurs, it ultimately produces biuret.

RNCO + R′NH2 → RNHCONHR′

RNCO+R'nHR → RNHCONR'R

Fatty primary amines react too quickly and are generally rarely used. Aliphatic secondary amines and aromatic primary amines react slightly slower and are commonly used to solidify NCO terminated prepolymers.

PART / 03

Reaction with water

2RNCO + H2O → RNHCONHR + CO2↑

One water molecule reacts with two NCO groups to obtain a substituted urea, and water can be used as a chain extender or curing agent.

The reaction of isocyanate with water can not only release carbon dioxide gas (which is particularly important in the production of polyurethane foam), but also generate substituted urea, which is an important curing agent.

Therefore, it is crucial to strictly control the moisture content in raw materials and products during the production and storage of polyurethane.

PART / 04

Reaction with carboxyl containing compounds:

Reacts with organic carboxylic acids, polyesters with carboxyl end groups, and other compounds to form mixed anhydrides, which eventually decompose and release carbon dioxide to produce amides.

PART / 05

Reaction with amino esters

Reaction generates urea ester

PART / 06

Self aggregation reaction

Isocyanates can undergo self polymerization under appropriate conditions, forming dimers or high molecular weight polymers. Therefore, isocyanates generally require storage under low temperature and no light conditions.

Reaction activity of different active hydrogens with isocyanates

In theory, isocyanates can react with all compounds that can provide active hydrogen, belonging to nucleophilic reactions. In compounds containing active hydrogen, the higher the electron cloud density of the nucleophilic center, the stronger its negative charge, the higher its reactivity with isocyanates, and the faster the reaction rate.

02 Existing products

Kastar's existing isocyanate curing agent products are as follows

2K water-based PU

With the increasing demand for environmental protection, 2K water-based PU, as an environmentally friendly coating, is gradually gaining favor in the market. It uses water-based isocyanate curing agent, which not only reduces the emission of volatile organic compounds, but also improves the environmental performance and construction safety of the coating.

2K water-based PU has excellent permeability and adhesion, and can form strong and durable coatings on various substrates. Meanwhile, its long activation period and low temperature turbidity characteristics also enable it to maintain stable performance in various complex environments.

03 Experimental data

Test Report Form (Hydroxypropyl Dispersion) - White Paint+Water based Curing Agent