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Isophorone Diisocyanate (IPDI), also called Isophorone Diisocyanate in Turkish, is a cycloaliphatic diisocyanate with the formula C₁₂H₁₈N₂O₂ and carrying two reactive isocyanate groups (-NCO). This raw material, defined by CAS No 4098-71-9; It is an important building block used in the production of polyurethane resins, coatings, adhesives, sealants, elastomers, water-based polyurethane dispersions and special purpose polymers.
Due to its cycloaliphatic structure, it stands out especially in polyurethane systems where light and outdoor resistance is required; it may exhibit higher resistance to yellowing compared to aromatic diisocyanates such as MDI and TDI.
Isophorone Diisocyanate (IPDI) can generally be evaluated at approximately 15–25% of the total formulation for initial studies in polyurethane prepolymer formulations; for example, 19% IPDI can be used in the first laboratory trial. The exact percentage of use should be calculated based on the hydroxyl number of the polyol and the targeted NCO/OH ratio.
The molecule has two separate isocyanate groups with a cyclohexane ring carrying three methyl groups. Since one of the groups is directly attached to the ring and the other to the isocyanatomethyl side group, their chemical environment and reactivity are different from each other. This property can be evaluated in controlled prepolymer synthesis and in the preparation of low-viscosity polyurethane intermediates.
IPDI is not only used as a monomer; It can also be used as a starting raw material in the production of trimer, blocked polyisocyanate, urethane acrylate and silane terminated polyurethane.
In commercial IPDI grades, the NCO content is approximately 37.5–37.8%, and the product must be protected from moisture.
WHAT IS ISOPHORONE DIISOCYANATE (IPDI)?
Isophorone Diisocyanate (IPDI) is a cycloaliphatic organic compound with two isocyanate functional groups. In industry, it is used as a reactive raw material in the synthesis of high-performance polyurethane materials. The commercial product is usually colorless to light yellow, clear and low viscosity liquid.
The molecular structure of IPDI is not symmetrical. One isocyanate group is directly attached to the cyclohexane ring, while the second isocyanate group is attached to the molecule via a methylene group. This structural difference results in no two NCO groups reacting at the same rate and can provide a significant advantage in terms of controlled prepolymer synthesis.
Its nominal functionality is 2. Since its molecular weight is about 222.28 g/mol, its theoretical NCO equivalent weight is about 111.14 g/eq and its theoretical NCO content is about 37.8%.
IPDI; It can react with polyether, polyester, polycarbonate and other hydroxyl function polyols. Polyether polyols provide low temperature flexibility and hydrolysis resistance, while polyester polyols can provide advantages in terms of hardness, abrasion and resistance to certain chemicals. The final polyurethane properties depend on the chemistry and functionality of the polyol used alongside IPDI.
While the cycloaliphatic structure gives a certain rigidity to the polyurethane rigid segments, the fact that it does not contain aromatic rings reduces the tendency to light-induced yellowing. For this reason, IPDI is especially preferred in transparent, white, pastel and outdoor polyurethane systems.
IPDI is not just a directly used monomer. It can be industrially converted to IPDI-based polyisocyanates, isocyanurate trimers, blocked isocyanates, NCO-functional prepolymers, waterborne polyurethane dispersions, and urethane acrylates.
The product is insoluble in water and reacts chemically with water. Water contact depletes NCO groups, can lead to carbon dioxide formation and subsequent polyurea structures. Therefore, storage tanks, drums, transfer lines, solvents and process equipment need to be kept dry.
For commercial high-purity monomeric IPDI, purity, NCO content, color, viscosity, total chlorine, and hydrolyzable chlorine are important quality parameters. Low initial color is particularly important in transparent and light-colored polyurethanes.
Monomeric IPDI, IPDI trimer, IPDI-based polyisocyanates, blocked IPDI derivatives, and IPDI prepolymers are not the same product. The CAS number of Monomeric Isophorone Diisocyanate is 4098-71-9; the functionality, NCO content, viscosity, and uses of derivative products may be different.
COMMON PRODUCT AND CHEMICAL NAMES
Isophorone Diisocyanate
IPDI
Isophorone Diisocyanate
3-Isocyanatomethyl-3,5,5-trimethylcyclohexyl Isocyanate
Cycloaliphatic Diisocyanate
CAS NO, EC / EINECS NO AND CHEMICAL IDENTIFICATION
Product Name: Isophorone Diisocyanate (IPDI)
Turkish name: Isophorone Diisocyanate
Chemical name: 3-Isocyanatomethyl-3,5,5-trimethylcyclohexyl Isocyanate
Abbreviation: Isophorone Diisocyanate (IPDI)
CAS No: 4098-71-9
EC/EINECS No: 223-861-6
Molecular formula: C₁₂H₁₈N₂O₂
Molecular weight: Approximately 222.28 g/mol
Chemical class: Cycloaliphatic diisocyanate
Functionality: 2
Theoretical NCO content: Approximately 37.8%
Commercial NCO content: Approx. 37.5–37.8%
NCO equivalent weight: Approx. 111.1 g/eq
Purity: Usually 99.5% ≥ in high-purity commercial grades
Physical form: Clear liquid between colorless and light yellow
Its main functions: Polyurethane raw material, prepolymer raw material, polyisocyanate precursor, polyurethane dispersion raw material and production raw material of crosslinking derivatives
Monomeric IPDI, IPDI trimer, and IPDI-based polyisocyanates are not the same product; CAS No 4098-71-9 and product type must be verified together at the time of purchase.
CHEMICAL STRUCTURE AND MOLECULAR PROPERTIES OF ISOPHORONE DIISOCYANATE (IPDI)
Isophorone Diisocyanate has a cyclohexane-based structure carrying three methyl groups. There are two separate isocyanate groups in the molecule and these groups are located in different steric circles.
The first isocyanate group is directly connected to the cycloaliphatic ring. Since the second group is located on the isocyanatomethyl side chain, the steric barrier formed by the surrounding atoms is different.
This structural asymmetry ensures that the reactivity of the two NCO groups differs from each other. The Evonik white paper also states that primary and secondary isocyanate groups provide selective reaction behavior in prepolymer synthesis.
The difference in reactivity can be particularly advantageous in controlled prepolymer production. With the appropriate use of temperature and catalyst, intermediates with narrower molecular weight distribution, lower viscosity, and lower free diisocyanates can be obtained.
The carbon atom in the isocyanate group is electron-poor and reacts easily with nucleophilic groups. As a result of the reaction with the hydroxyl group in alcohol, a urethane bond is formed.
The reaction with amines is generally faster than with hydroxyl groups. Urea bonds are formed as a result of the reaction of primary and secondary amines with Isophorone Diisocyanate (IPDI).
Water can also react with NCO groups. Therefore, reaction systems containing Isophorone Diisocyanate (IPDI) and Isophorone Diisocyanate (IPDI) need to be protected from moisture.
The cycloaliphatic ring forms the basis of the light stability of Isophorone Diisocyanate (IPDI). Since there is no aromatic structure, it has a lower tendency to intense yellowing, which can be seen in aromatic MDI or TDI systems under ultraviolet light.
This does not mean that Isophorone Diisocyanate (IPDI) based polyurethanes are completely incorruptible to ultraviolet light. The actual outdoor resistance of the polyurethane system also depends on the polyol, pigment, light stabilizer, film thickness and other formulation components.
The irregular and branched structure of the molecule helps to have a low tendency to crystallize. For this reason, Isophorone Diisocyanate (IPDI) can remain liquid even at low temperatures and can show a freezing temperature of around -60 °C.
The cycloaliphatic ring of Isophorone Diisocyanate (IPDI) can provide a certain hardness and rigidity in the final polyurethane structure. This property is particularly useful for coating systems where hardness and light resistance are required together.
PHYSICAL AND CHEMICAL PROPERTIES OF ISOPHORONE DIISOCYANATE (IPDI)
Isophorone Diisocyanate is a clear and low viscosity liquid, usually ranging from colorless to slightly yellow. Appearance and some numerical values may vary slightly depending on the manufacturer, purity and measurement temperature.
General technical specifications:
Physical appearance: Clear liquid between colorless and slightly yellow
Odor: Mild but characteristic pungent odor
Chemical character: Cycloaliphatic diisocyanate
Molecular formula: C₁₂H₁₈N₂O₂
Molecular weight: Approximately 222.28 g/mol
CAS No: 4098-71-9
EC/EINECS No: 223-861-6
Functionality: 2
NCO content: Approx. 37.5–37.8%
Purity: About ≥99.5%
Density: Approx. 1.058 g/cm³ (20 °C)
Viscosity: Approx. 13–15 mPa·s (23 °C)
Color: 10< APHA in a current commercial product with high purity
Refractive index: Approx. 1.483 (25 °C)
Freezing point: Around -60 °C
Vapor pressure: Approx. 6.35 × 10⁻⁴ hPa (20 °C)
Flash point: Approx. 151 °C, closed cup
Autoignition temperature: Approx. 430 °C
Total chlorine: 10≤ ppm in a current high-purity commercial product
Behavior in water: Reacts chemically with water
NCO equivalent weight: Approx. 111.1 g/eq
NIOSH physical description: Colorless to slightly yellow, pungent-smelling liquid
In Evonik's current VESTANAT Isophorone Diisocyanate (IPDI) product data for 2025, density is given as 1.058 g/cm³ at 20 °C, viscosity 13–15 mPa·s at 23 °C, refractive index 1.483, vapor pressure 6.35 × at 20 °C 10⁻⁴ hPa, and closed cup flash point of 151 °C.
NIOSH data state that Isophorone Diisocyanate (IPDI) has a specific gravity of approximately 1.06, a very low vapor pressure, and a freezing point of approximately -76 °F. Very low vapor pressure does not mean that there is no risk of inhalation exposure in aerosol or heated processes.
These values are for general technical demonstration purposes. The supplier's current TDS and batch-based COA values should be used as the binding specification of the product to be purchased.
HOW DOES ISOPHORONE DIISOCYANATE (IPDI) WORK AT THE MOLECULAR LEVEL?
The basic working mechanism of Isophorone Diisocyanate is based on the reaction of two isocyanate groups in the molecule with active hydrogen-containing compounds. In polyurethane technology, the most common reaction occurs between the NCO groups and the hydroxyl groups present in the polyols.
When a hydroxyl group reacts with an isocyanate group, a urethane bond is formed. Since two NCO groups are present in the same Isophorone Diisocyanate (IPDI) molecule, the molecule can link two different polyol chains together or contribute to the formation of long polyurethane chains.
When the functionality of the polyol is higher than two, branching and cross-linking can increase in the system. Thus, not only linear polyurethane chain, but also three-dimensional network structure can be formed.
As a result of the reaction with amines, urea bonds are formed instead of urethane. This reaction is usually faster than the reaction with hydroxyl groups and can be used in the preparation of polyurethane-urea systems.
Contact with water is of particular importance. When the NCO group reacts with water, carbon dioxide can be formed, which can lead to increased pressure in closed systems and bubble formation in liquid or casting systems.
The reactivity of the two isocyanate groups of Isophorone Diisocyanate (IPDI) is different from each other. This difference can provide selectivity in controlled propolymer synthesis and contribute to more regular product formation.
Evonik states that this property of Isophorone Diisocyanate (IPDI) helps in the preparation of products with narrow molecular weight distribution, low viscosity and low residual monomers. The same source explains that the highest selectivity can be achieved under specific catalyst and temperature conditions.
The molecular and reaction-level functions of Isophorone Diisocyanate can differ based on the application:
Creating a urethane bond with polyols
Forming urea bonds with amines
Preparing polyurethane prepolymers
Increasing the molecular weight of polyurethane chains
Producing water-based polyurethane dispersions
Preparing moisture-curing prepolymers
To be a raw material in the production of polyisocyanates based on Isophorone Diisocyanate (IPDI)
To be the starting material in the production of Isophorone Diisocyanate (IPDI) trimers
To be used in the preparation of blocked polyisocyanates
Producing urethane acrylate
Being a building block for UV-curing resins
To be used in the production of silane terminated polyurethanes
To create polyurethane structures with high light resistance
Contributing to the mechanical strength of polyurethanes
Supporting chemical resistance and hardness in coatings
IN WHICH SECTORS IS ISOPHORONE DIISOCYANATE (IPDI) USED?
Isophorone Diisocyanate is a versatile cycloaliphatic diisocyanate, particularly used in the paint-coating, adhesive, sealing, synthetic leather, textile, and specialty polyurethane industries. The usage method varies depending on whether Isophorone Diisocyanate (IPDI) is incorporated into the system directly as a monomer or through a prepolymer, polyisocyanate, or resin produced from it.
Main areas of use:
Automotive OEM coatings
Automotive refinish coatings
Transparent topcoats
Industrial metal coatings
Outdoor protective coatings
Wood varnishes and transparent wood coatings
Plastic surface coatings
High solids coating systems
Waterborne polyurethane dispersions
Solvent-based polyurethane resins
Polyurethane adhesives
Water-based adhesives
Laminating adhesives
Shoe adhesives
Automotive interior trim adhesives
Reactive hot melt adhesives
Moisture-curing adhesives
Construction adhesives
Polyurethane sealants and sealants
Automotive sealants
Construction grouts
Polyurethane elastomers
Cast elastomers with high light resistance
Artificial leather production
Natural leather surface coatings
Textile coatings
Flexible polyurethane films
Protective membranes
Urethane acrylates
UV-curing coatings
UV-curing inks
Radiation curing oligomers
Silane terminated polyurethanes
Hybrid adhesives and sealants
Production of trimers based on Isophorone Diisocyanate (IPDI)
Production of polyisocyanate based on Isophorone Diisocyanate (IPDI)
Blocked Isophorone Diisocyanate (IPDI) crosslinkers
Urethane modified alkyd resins
Special purpose polyurethane resins
One of the most important uses of Isophorone Diisocyanate is the preparation of polyurethanes with high light and outdoor resistance. The current white paper of Evonik states that Isophorone Diisocyanate (IPDI) is used in coating raw materials, water-based polyurethane dispersions, adhesives, hot melt systems, urethane acrylates and moisture-curing prepolymers.
The performance that each industry expects from Isophorone Diisocyanate (IPDI) is different. The paint manufacturer may focus on yellowing resistance, hardness and outdoor resistance, while the adhesive manufacturer may pay more attention to viscosity, adhesion, open time and residual monomer level.
PAINT, COATING, POLYURETHANE AND RESIN APPLICATIONS OF ISOPHORONE DIISOCYANATE (IPDI)
Paint and coating technology is one of the most important uses of Isophorone Diisocyanate (IPDI). However, monomeric Isophorone Diisocyanate (IPDI) and polyisocyanate hardeners offered to the end user are not the same product.
Monomeric Isophorone Diisocyanate (IPDI) is mostly used as a starting raw material in the production of higher functionality polyisocyanates, prepolymers and special polyurethane resins. The hardener used in two-component polyurethane paints is often Isophorone Diisocyanate (IPDI) trimer or modified polyisocyanate based on Isophorone Diisocyanate (IPDI).
Possible functions of Isophorone Diisocyanate in coating applications include:
To produce polyurethane resin with high light resistance
Developing yellow-resistant clear coats
Producing automotive transparent finishing systems
Improving the color stability of white and light coatings
To produce polyisocyanate hardeners based on Isophorone Diisocyanate (IPDI)
Preparing blocked crosslinkers
Producing water-based polyurethane resins
Developing high-solids coating resins
Preparing urethane acrylate oligomers
Increasing chemical resistance
Improving film stiffness
Supporting scratch and abrasion resistance
Contributing to shine preservation
Increasing outdoor resistance
Automotive OEM and refinish coatings are among the important application areas of Isophorone Diisocyanate (IPDI) derivatives. Due to the prolonged exposure of the transparent topcoat to sunlight, color stability and gloss preservation are important.
Evonik states that Isophorone Diisocyanate (IPDI)-based systems are used especially in large vehicle and automotive OEMs and refinishing. The same source identifies adduct products made to isocyanurates and alcohols prepared from Isophorone Diisocyanate (IPDI) as important derivatives for two-component polyurethane coatings.
Low yellowing is also an important advantage in wood coatings. Transparent varnish should not change the natural color of the wood underneath and should remain as colorless as possible with prolonged light exposure.
In plastic surface coatings, flexibility and surface hardness can be desired together. These properties can be adjusted in a wide range by changing the polyol structure of Isophorone Diisocyanate (IPDI) based polyurethanes.
Urethane acrylate technology is another important area of use. As a result of the reaction of Isophorone Diisocyanate (IPDI) with hydroxyl-function acrylates, urethane acrylate oligomers that can be cured with UV or electron beam can be prepared.
Evonik states that Isophorone Diisocyanate (IPDI)-based urethane acrylates are used in radiation-cured systems where high yellowing resistance is required.
Blocked Isophorone Diisocyanate (IPDI) derivatives can be used in one-component baking paints. Since the isocyanate group is temporarily blocked, the resin and crosslinker can be kept more stably in the same packaging.
During baking, the blocking group separates or conditions that allow the reaction are created and polyurethane crosslinking occurs. This technology can be used in coil coatings, metal packaging coatings and special industrial paint systems.
USE OF ISOPHORONE DIISOCYANATE (IPDI) IN ADHESIVE, SEALING, ELASTOMER AND WATER-BASED POLYURETHANE APPLICATIONS
Isophorone Diisocyanate can be used in the preparation of both waterborne polyurethane dispersions and NCO tipped prepolymers in the production of adhesives. Its ability to form low viscosity prepolymers is particularly valued for its ease of process.
Water-based polyurethane dispersions are one of the important uses of Isophorone Diisocyanate (IPDI). In its current product document, Evonik cites low prepolymer viscosity and low co-solvent requirement as the main advantages in this application.
Flexibility and strong adhesion are desired together in shoe adhesives. Polyurethane dispersions can be used to create bonds between leather, textiles, sole materials, and various synthetic surfaces.
In lamination adhesives, flexible surfaces such as films, textiles, foams and membranes need to be bonded together. Isophorone Diisocyanate (IPDI)-based polyurethane structures can be adjusted in terms of flexibility, adhesion and hydrolysis resistance with the appropriate selection of polyol options.
Low emissions and long-term flexibility are important in automotive interior trim adhesives. Water-based polyurethane dispersions can therefore be considered in automotive interior applications.
In reactive hot melt polyurethane adhesives, the pre-polymer is applied in a hot state. While cooling provides initial adhesion, the ongoing reaction with atmospheric moisture improves the final strength.
Isophorone Diisocyanate (IPDI)-tipped prepolymers can be used in moisture-curing polyurethane adhesives and sealants. Atmospheric moisture reacts with the terminal NCO groups, allowing the network structure to develop.
Evonik states that Isophorone Diisocyanate (IPDI)-based moisture-curing prepolymers stand out with their properties such as low viscosity, low free diisocyanate level and yellowing resistance.
High flexibility, adhesion and external strength are important in construction sealants. Isophorone Diisocyanate (IPDI) based prepolymers can be used especially in light-colored sealants where color change is not desired.
Isophorone Diisocyanate (IPDI) can also be used in the preparation of silane-terminated polyurethanes. First, the NCO-tipped polyurethane structure is prepared, then it is reacted with silane with the appropriate amine or hydroxyl function to form alkoxycyanyl end groups.
Such systems are cured by moisture through silane hydrolysis and condensation. Construction and assembly adhesives and hybrid sealants are the main product groups in which this chemistry is used.
In polyurethane elastomers, Isophorone Diisocyanate (IPDI) can be used, especially in products where color and light resistance are important. The cycloaliphatic structure can allow for the preparation of light-colored or transparent elastomers.
Evonik also cites solvent-free, lightfast polyurethane RIM technology as one of the important application areas of Isophorone Diisocyanate (IPDI).
Artificial leather and natural leather coatings are known uses of high molecular weight polyurethanes based on Isophorone Diisocyanate (IPDI). Long-term flexibility and light resistance are particularly important for these applications.
IS ISOPHORONE DIISOCYANATE (IPDI) USED IN FOOD, COSMETIC AND PHARMACEUTICAL APPLICATIONS?
Isophorone Diisocyanate (IPDI) is mainly industrial polyurethane production raw material. It is not used as a food ingredient, flavoring agent, or directly food additive.
Isophorone Diisocyanate (IPDI) does not have a food flavor or additive ID in the form of FEMA, JECFA, or E code. Therefore, monomeric Isophorone Diisocyanate (IPDI) should not be evaluated directly in food formulation.
For coatings or adhesives that come into contact with food, the evaluation is different. Here, instead of the general name of the monomer, the final cured system, the amount of residual monomer, migration values and the food contact legislation of the target market should be examined.
In cosmetic and personal care applications, monomeric Isophorone Diisocyanate (IPDI) is not a general cosmetic raw material. Due to its reactive isocyanate structure, it is not considered a suitable ingredient for use directly in end-user cosmetic formulation.
In the pharmaceutical industry, Isophorone Diisocyanate (IPDI) is not a standard active ingredient or excipient. It should not be assumed for pharmaceutical use other than chemical synthesis or research purposes.
Polyurethane materials used in medical devices are a separate issue. In such an application, the biocompatibility of the final polymer, the amount of residual monomer, and the relevant medical device standards must be evaluated separately.
Isophorone Diisocyanate is an essential raw material used in various industrial polyurethane systems, thanks to its two reactive NCO groups and cycloaliphatic structure.
The following functions may come to the fore in industrial Isophorone Diisocyanate applications:
Polyurethane synthesis
NCO tip prepolymer production
Production of water-based polyurethane dispersion
Polyurethane-urea synthesis
Isophorone Diisocyanate (IPDI) trimer production
Production of polyisocyanate hardener
Production of blocked polyisocyanate
Two-component paint hardener raw material
One-component baking paint crosslinker raw material
Production of moisture-curing prepolymer
Production of adhesive resin
Production of sealing polymer
Elastomer production
Production of artificial skin resin
Textile coating resin production
Production of urethane acrylate
Production of UV-cured resin
Production of silane-terminated polyurethane
Production of urethane modified alkyd
Development of high-solids coating resins
Production of low-free monomer prepolymer
Clear coat resins with high light resistance
Outdoor resistant protective coatings
In polyurethane synthesis, the NCO/OH ratio is one of the key design parameters. The use of excess or underisocyanate alters the molecular weight, amount of NCO remaining, cross-link density, and final material properties.
The hydroxyl number and functionality of the polyol should also be evaluated together. A high hydroxyl count means that there are more reactive OH groups in the same mass and can increase the amount of Isophorone Diisocyanate (IPDI) required.
The amount of water in polyol and solvents should be kept as low as possible. Moisture can lead to both NCO consumption and carbon dioxide formation.
Reaction temperature affects reactivity and selectivity. Evonik states that under low temperature and appropriate catalyst, the selectivity between the two NCO groups of Isophorone Diisocyanate (IPDI) can be more pronounced.
The use of catalysts is especially important in aliphatic and cycloaliphatic diisocyanates. Isophorone Diisocyanate (IPDI) reacts more slowly with hydroxyl groups than aromatic diisocyanates, so catalysts may be required in some formulations.
The following issues should be evaluated in the use of Isophorone Diisocyanate in industrial systems:
Product purity
NCO content
Color value
Viscosity
Total chlorine
Hydrolysis can chlorine
Polyol type
Polyol hydroxyl number
Polyol functionality
Polyol moisture content
NCO/OH ratio
Catalyst type
Catalyst quantity
Reaction temperature
Reaction time
Amount of free monomer
Remaining NCO amount
Prepolymer viscosity
Solvent purity
Solvent moisture content
Chain extender type
Dispersion solids ratio
Ultimate film hardness
Flexibility
Adhesion
Chemical resistance
Outdoor resistance
TDS information
SDS information
Batch-wise COA values
WHAT PROBLEMS CAN ISOPHORONE DIISOCYANATE (IPDI) HELP SOLVE?
Isophorone Diisocyanate; It can help solve various technical problems such as yellowing, insufficient external strength, high pre-polymer viscosity and the need for controlled reactions in polyurethane coating, adhesive, sealant and resin systems. However, performance depends not only on Isophorone Diisocyanate (IPDI), but also on polyol structure, catalyst, ratios and process conditions.
Yellowing of aromatic polyurethanes
MDI or TDI-based polyurethane systems may be more prone to color change under ultraviolet light. The cycloaliphatic nature of Isophorone Diisocyanate (IPDI) can help reduce the tendency to yellowing in transparent and light-colored applications.
Insufficient external strength
Outdoor coatings can be exposed to sunlight, moisture, temperature changes and chemicals. Isophorone Diisocyanate (IPDI) based polyurethane structures can contribute to the development of long-term outdoor durability with appropriate polyol and additives.
High prepolymer viscosity
High viscosity can complicate pumping, mixing, and application processes. The low viscosity and selective reaction behavior of Isophorone Diisocyanate (IPDI) can help prepare lower viscosity prepolymers.
Process challenge in waterborne polyurethane dispersion
Too high prepolymer viscosity can be problematic during the dispersion phase in water. Isophorone Diisocyanate (IPDI)'s tendency to form low viscosity prepolymer can facilitate the development of dispersions that require lower cosolvents.
High initial color in clear coating
In transparent systems, the color of the raw material itself can directly affect the film appearance. High-purity Isophorone Diisocyanate (IPDI) with a low color value can help prepare lighter polyurethane resins.
Outdoor yellowing of adhesives
Visible adhesive lines or light-colored adhesives may change color over time. Cycloaliphatic Isophorone Diisocyanate (IPDI) chemistry can be evaluated in an attempt to reduce this color change.
Yellowing of UV-cured resins
Aromatic urethane acrylates may create undesirable color in clear coating applications. Isophorone Diisocyanate (IPDI) based urethane acrylates can be preferred in UV coatings where low yellowing is required.
Low chemical resistance
Insufficient cross-link density can cause some coatings to soften in the face of solvents and cleaners. High-function polyisocyanates produced from Isophorone Diisocyanate (IPDI) can form strong network structures with appropriate hydroxyl-function resins.
Insufficient mechanical strength
When the amount of hard segments or cross-link density is low in a polyurethane system, scratch, abrasion or hardness performance may be insufficient. Isophorone Diisocyanate (IPDI)-based hard segments can support these properties with appropriate resin design.
It should not be assumed that every Isophorone Diisocyanate product will give the same performance. Purity, color, chlorine content, polyol type, and reaction conditions should be verified by laboratory and manufacturing trials.
THINGS TO CONSIDER WHEN USING ISOPHORONE DIISOCYANATE (IPDI)
One of the most important technical issues in the use of Isophorone Diisocyanate is humidity control. Since water reacts with NCO groups, humidity should be kept as low as possible during product storage and preparation of raw materials before reaction.
The following issues should be considered when using Isophorone Diisocyanate:
The appropriate quality should be selected for the intended use.
The purity value of the product should be checked.
The NCO content should be checked.
The color value should be evaluated.
Total chlorine should be checked.
Hydrolysis may occur, the amount of chlorine should be controlled.
The moisture content of the polyol should be controlled.
It should be ensured that the solvents are dry.
NCO/OH equivalent calculation should be made.
Polyol functionality should be considered.
The reaction temperature must be controlled.
It should be noted that the reaction is exothermic.
The amount of catalyst should be determined in a controlled manner.
The pre-polymer viscosity should be monitored.
The remaining amount of NCO should be analyzed.
The amount of free Isophorone Diisocyanate (IPDI) should be measured in necessary applications.
Contact with air and moisture should be kept to a minimum.
Water ingress into the storage tank should be prevented.
Transfer equipment must be kept dry.
Adequate ventilation should be provided.
Aerosol formation should be avoided.
TDS should be examined.
SDS should be examined.
Batch-based values should be verified via COA.
It should be noted that monomeric Isophorone Diisocyanate (IPDI) and Isophorone Diisocyanate (IPDI) trimer are not interchangeable. The two products differ in functionality, NCO content, viscosity, and role in formulation.
The reaction between Isophorone Diisocyanate and the polyol releases heat. In large-scale reactors, the feed rate and cooling capacity are therefore important for process safety.
Spraying or aerosol-generating processes can significantly increase exposure. Occupational safety measures in such processes should be determined based on the product's current SDS and workplace risk assessment.
INITIAL FORMULATION APPROACHES FOR ISOPHORONE DIISOCYANATE (IPDI)
The following examples are initial approaches designed to illustrate how Isophorone Diisocyanate can be evaluated during formulation and process development. These are not validated commercial recipes, manufacturing instructions, or final regulatory formulas.
The percentages given are for laboratory initial studies. The actual NCO/OH ratio should be recalculated based on the hydroxyl number of the polyol, the actual NCO content of the product, the auxiliary raw materials used, and the targeted final properties.
EXAMPLE 1: NCO/OH RATIO SCREENING IN ISOPHORONE DIISOCYANATE (IPDI)/POLYOL PREPOLYMER
Purpose: To compare the effect of Isophorone Diisocyanate level on prepolymer viscosity, amount of residual NCO and final polyurethane properties.
Starting components:
Polyether diol, OH number approx. 56 mg KOH/g: 80.98%
Isophorone Diisocyanate (IPDI): 19.00%
Suitable polyurethane catalyst: 0.02%
Total: 100%
This starting prescription is an example for a laboratory screening in the approximately NCO/OH 2.0 region. If the actual OH number of the polyol used and the NCO value of the IPDI on the COA are different, the IPDI percentage should be recalculated.
Application approach:
The hydroxyl equivalent of the polyol is calculated.
The actual NCO content of Isophorone Diisocyanate (IPDI) is taken via COA.
The required amount of IPDI is verified based on the target NCO/OH ratio.
Polyol is taken into the system in dry conditions as much as possible.
IPDI is added in a controlled manner.
Throughout the reaction, temperature, viscosity, and NCO value are monitored.
When the target NCO value is reached, the sample is analyzed.
Prepolymer viscosity, color, and amount of free IPDI are compared.
If necessary, the IPDI level is readjusted in the range of approximately 15–21% in the second scan.
EXAMPLE 2: ISOPHORONE DIISOCYANATE (IPDI)-BASED WATER-BASED POLYURETHANE DIVERSIFICATION DEVELOPMENT SCAN
Objective: To evaluate the effect of IPDI-based hard segment quantity on dispersion stability, film hardness, flexibility and water resistance.
Starting components:
Polyether or polyester polyol: 28.00%
Isophorone Diisocyanate (IPDI): 11.00%
Inner emulsifier / hydrophilic diol: 2.50%
Neutralizing agent: 1.90%
Chain extender: 1.40%
Process solvent: 5.20%
Deionized water: 50.00%
Total: 100%
In this formulation, the baseline level for IPDI was taken as 11% of the total formulation. The actual NCO/OH balance should be recalculated based on the OH number of the polyol, the amount of reactive groups of the inner emulsifier, and the chain extender stoichiometry.
Application approach:
The humidity of polyol and other hydroxyl function components is controlled.
The prepolymer with the NCO tip is prepared with polyol, inner emulsifier and IPDI.
When the target NCO level is reached, the ionic groups are neutralized.
The prepolymer is dispersed into deionized water under controlled stirring.
The chain extender is added in a controlled manner.
The final pH, solids ratio, viscosity and particle size are checked.
The standard film is prepared and the hardness, flexibility, adhesion and water resistance are compared.
EXAMPLE 3: ISOPHORONE DIISOCYANATE (IPDI) BASED LIGHT RESISTANT POLYURETHANE COATING SCAN
Objective: To evaluate the effect of IPDI-based low-monomer polyisocyanate crosslinker on film hardness, chemical resistance, and yellowing resistance.
Starting components:
Acrylic resin solution with hydroxyl function: 55.00%
IPDI-based low-monomer polyisocyanate: 20.00%
Suitable ester/ketone type solvent mixture: 22.50%
UV absorber and light stabilizer package: 2.00%
Flow contribution: 0.40%
Suitable polyurethane catalyst: 0.10%
Total: 100%
In the initial formulation, IPDI-based polyisocyanate was used at the level of 20%. The exact amount of hardener should be adjusted by NCO/OH equivalent calculation according to the OH value of the hydroxyl function resin and the actual NCO content of the polyisocyanate.
Application approach:
Resin, solvent and additives with hydroxyl function are mixed homogeneously.
IPDI-based polyisocyanate is added just before administration.
Initial viscosity and usage time are monitored.
Equal film thickness is applied on standard panels.
Drying and curing behavior are evaluated.
Hardness, adhesion and chemical resistance are tested.
In the accelerated UV or outdoor weathering test, color change and gloss retention are compared.
ALTERNATIVES AND COMPARISONS OF ISOPHORONE DIISOCYANATE (IPDI)
When selecting the alternative for Isophorone Diisocyanate, one should not compare the NCO content alone. Molecular structure, reactivity, light resistance, viscosity, flexibility, and final product requirements should be evaluated together.
ISOPHORONE DIISOCYANATE (IPDI) AND HEXAMETHYLENE DIISOCYANATE (HDI)
HDI is an aliphatic diisocyanate with a linear structure. Isophorone Diisocyanate (IPDI), on the other hand, has a cycloaliphatic structure with a cycloaliphatic structure.
Both products can be used in the production of polyurethanes with high light resistance. However, the structure and final mechanical properties of the rigid segments they form are different.
Isophorone Diisocyanate (IPDI)-based systems can generally provide advantages in terms of stiffness and rigidity. HDI-based systems may be preferred for more flexible network structures.
The molecular weight and NCO equivalent weight of the two monomers are different. Therefore, one-to-one substitution should not be made by weight.
ISOPHORONE DIISOCYANATE (IPDI) AND H12MDI
H12MDI is another cycloaliphatic diisocyanate, also known as hydrogenated MDI. It has a larger and more rigid molecular structure than Isophorone Diisocyanate (IPDI).
H12MDI can also be used in polyurethane elastomers, coatings and special resins with high light resistance. However, it differs from Isophorone Diisocyanate (IPDI) in terms of viscosity, reaction rate and equivalent weight.
When switching from one system to another, the recipe should be recalculated and application tests should be performed.
ISOPHORONE DIISOCYANATE (IPDI) AND MDI
MDI is an aromatic diisocyanate and one of the most common raw materials in the polyurethane industry. It has a wide range of uses in foam, adhesive, elastomer, composite and insulation applications.
The main advantage of Isophorone Diisocyanate (IPDI) is its light and color stability. In transparent or light-colored systems used outdoors, Isophorone Diisocyanate (IPDI)-based chemistry may be preferred instead of aromatic MDI.
MDI may be more advantageous in some applications in terms of cost, reactivity, or mechanical performance. Therefore, product selection should not be based solely on yellowing behavior.
ISOPHORONE DIISOCYANATE (IPDI) AND TDI
TDI is an aromatic and more volatile diisocyanate. It is widely used in flexible polyurethane foams and some elastomer or prepolymer systems.
Isophorone Diisocyanate (IPDI), on the other hand, is more suitable for applications where color and light resistance are important thanks to its cycloaliphatic structure. The reaction rate and process behavior of the two products are also different.
TDI and Isophorone Diisocyanate (IPDI) do not have the same NCO equivalent weight. Therefore, direct weight substitution should not be performed.
ISOPHORONE DIISOCYANATE (IPDI) AND Isophorone Diisocyanate (IPDI) TRIMER
Monomeric Isophorone Diisocyanate (IPDI) and Isophorone Diisocyanate (IPDI) trimer are not the same product. Monomeric Isophorone Diisocyanate is a diisocyanate that carries two NCO groups.
Isophorone Diisocyanate (IPDI) trimer, on the other hand, is a higher-functioning polyisocyanate created by combining several Isophorone Diisocyanate (IPDI) molecules into an isocyanurate structure. It is used as a hardener, especially in two-component polyurethane coatings.
Monomeric Isophorone Diisocyanate (IPDI) is mostly the production raw material of such polyisocyanates. During formulation, the monomer and trimer are not directly interchangeable.
ISOPHORONE DIISOCYANATE (IPDI) AND BLOCKED Isophorone Diisocyanate (IPDI)
In blocked Isophorone Diisocyanate (IPDI) derivatives, the reactive NCO groups are temporarily reacted with another molecule, reducing the low-temperature reactivity. Thus, longer storage stability can be achieved in one-component resin systems.
When the required reaction conditions are met at oven temperature, isocyanate functionality participates in crosslinking. These systems can be used in oven paints and some powder coating technologies.
Monomeric Isophorone Diisocyanate (IPDI), on the other hand, does not exhibit the same usage behavior as the blocked derivative because it has free NCO groups.
QUALITY CONTROL AND PURCHASING CRITERIA FOR ISOPHORONE DIISOCYANATE (IPDI)
When purchasing Isophorone Diisocyanate, it is not enough to make a decision based solely on the product name and price. Parameters such as NCO content, purity, chlorine content, color, and viscosity can affect the reproducibility of the polyurethane reaction.
Recommended information to review before purchasing:
Product name and manufacturer
Full chemical identity
CAS number
EC/EINECS number
Whether Monomeric Isophorone Diisocyanate (IPDI)
Purity
NCO content
NCO equivalent weight
Total chlorine
Hydrolysis can chlorine
Color value
Viscosity
Density
Refractive index
If there is a water or humidity specification, the relevant value
Storage conditions
Shelf life
Packaging Type
Net quantity
Production and batch information
Information of origin
TDS
SDS
COA
REACH information
Diisocyanate use restriction and educational information
The COA shows the actual analysis results of a given batch of Isophorone Diisocyanate. The TDS describes the standard technical specifications and uses of the product. The SDS contains safe handling, storage, handling, and emergency information.
These documents are not interchangeable and should be evaluated together. In particular, NCO content is an important parameter that can be used directly in polyurethane prescription calculation.
Color value is important for transparent and light-colored polyurethane systems. The high color of the starting raw material can affect the final resin and coating color.
Chlorine content can be important in some sensitive polyurethane reactions, catalyst systems, or special electronic applications. Low-chlorine grades may therefore be preferred in certain applications.
When switching to a new Isophorone Diisocyanate (IPDI) supplier, it is useful to perform a laboratory-scale comparison reaction. The reaction rate, prepolymer viscosity, color, NCO content, and amount of free monomers are comparable.
STORAGE AND HANDLING OF ISOPHORONE DIISOCYANATE (IPDI)
Storage: Isophorone Diisocyanate should be stored within the manufacturer's recommended temperature range, in a dry, well-ventilated environment, and in appropriate tightly sealed packaging. Packaging should not be left open, as moisture ingress can deplete the product's NCO groups and lead to carbon dioxide formation.
Protection from moisture: Since Isophorone Diisocyanate (IPDI) reacts with water, it is important to keep storage tanks, pumps, piping, and connections dry. Methods such as dry gas blanketing to be used in large-volume storage should be applied according to the supplier's technical and safety instructions.
Transfer and handling: Splashing and aerosol formation should be minimized when transferring the product. Clean, dry and chemically compatible equipment should be used, and operation in open systems should be limited as much as possible.
Incompatible substances: Uncontrolled contact with water, alcohols, amines, strong acids, strong bases and other active hydrogen-containing substances should be avoided. Other incompatible substances specified in the supplier's current SDS should also be taken into account.
Shelf life: Evonik reports a storage period of at least one year without loss of specification for VESTANAT Isophorone Diisocyanate (IPDI) that is closed and properly stored, and indicates that an increase in color number may be seen with longer storage. This value should not be generalized for all Isophorone Diisocyanate (IPDI) grades, but should be based on the TDS of the purchased product.
Transportation: The transportation classification for Isophorone Diisocyanate should be checked against the supplier's current SDS document. NIOSH provides DOT ID 2290 information for Isophorone Diisocyanate (IPDI).
ISOPHORONE DIISOCYANATE (IPDI) SAFETY INFORMATION
The safe use of Isophorone Diisocyanate depends on the up-to-date SDS document of the supplied product and the implementation of appropriate occupational safety measures.
According to ECHA's harmonized EU classification, Isophorone Diisocyanate (IPDI) is toxic if inhaled; it may cause skin and eye irritation, cause an allergic skin reaction, cause allergy or asthma symptoms or breathing difficulties when inhaled, irritate the respiratory tract, and have a long-term toxic effect in the aquatic environment.
NIOSH gives an 8-hour time-weighted average exposure limit of 0.005 ppm and a short-term limit of 0.02 ppm for Isophorone Diisocyanate (IPDI); it also has a skin notation. In the NIOSH physical description, the product is specified as a colorless to slightly yellow liquid with a pungent odor.
A closed system, local suction, appropriate gloves, eye/face protection and, where necessary, appropriate respiratory protection should be used when working with the product. Detailed personal protective equipment selection and emergency procedures should be determined on the current SDS.
It should not be assumed that the safety classification of different Isophorone Diisocyanate (IPDI) derivatives is the same. Monomeric Isophorone Diisocyanate (IPDI), Isophorone Diisocyanate (IPDI) trimer, blocked Isophorone Diisocyanate (IPDI) and low monomer prepolymers should be evaluated on separate SDS documents.
WHAT TO CONSIDER WHEN BUYING ISOPHORONE DIISOCYANATE (IPDI)?
The first step in sourcing Isophorone Diisocyanate is to clarify in which polyurethane system the product will be used. The quality criteria sought for waterborne polyurethane dispersion, prepolymer, urethane acrylate, trimer production or adhesive application may not be exactly the same.
For this reason, instead of writing only "Isophorone Diisocyanate (IPDI)" in the purchase request, clearly stating that monomeric Isophorone Diisocyanate is requested provides a more accurate evaluation of the product.
The following information should be clarified before purchasing:
Use sector and end application
Monomeric Isophorone Diisocyanate (IPDI) requirement
Minimum desired purity
Desired NCO content
Total chlorine limit
Hydrolysis can chlorine limit
Color limit
Viscosity range
Density value
Humidity limit, if any
Manufacturer and origin information requirement
Desired packaging type and quantity
Shelf life requirement
The need for TDS
The need for SDS
The need for COA
REACH documents
Documentation on diisocyanate use restrictions
If substituting with an existing product, current TDS and COA information
Isophorone Diisocyanate price; It may vary depending on product purity, NCO content, chlorine specification, manufacturer, origin, order quantity, packaging and current logistics conditions. For this reason, the current price should be evaluated on the offer together with the technical specification and delivery conditions.
ISOPHORONE DIISOCYANATE (IPDI) SUPPLY FROM ATAMAN KIMYA
Isophorone Diisocyanate (IPDI) is an important cycloaliphatic diisocyanate evaluated in paint-coating, polyurethane resin, adhesive, sealing, elastomer, artificial leather and special polymer applications. It is important for companies planning to purchase the product to clarify the quality, NCO content and other technical specifications suitable for the area of use before ordering.
Companies that want to get information about the supply of Isophorone Diisocyanate (IPDI) from Ataman Kimya can request information about product suitability, current supply status, packaging options and price offers by sharing their usage areas and technical needs.
The current stock status, origin, manufacturer, purity, NCO content, technical specifications, packaging and specifications of the product should be confirmed from Ataman Kimya before ordering.
Sharing the following information in the request for quotation facilitates the evaluation of the right Isophorone Diisocyanate product:
Use sector and end application
Monomeric Isophorone Diisocyanate (IPDI) requirement
Minimum purity requested
Requested NCO content
Total chlorine requirement
Hydrolysis can chlorine requirement
Color requirement
Viscosity requirement
Information about the polyol or resin system used
Estimated order quantity
Type of packaging requested
Requested technical documents
TDS or COA information of the current product, if applicable
FREQUENTLY ASKED QUESTIONS ABOUT Isophorone Diisocyanate (IPDI)
What is Isophorone Diisocyanate (IPDI)?
Isophorone Diisocyanate is a cycloaliphatic diisocyanate carrying two reactive isocyanate groups. It is used in the production of polyurethane resins, coatings, adhesives, sealants, elastomers, and waterborne polyurethane dispersions.
What is Isophorone Diisocyanate (IPDI) short for?
IPDI is the common industrial abbreviation for Isophorone Diisocyanate.
What is the CAS number of Isophorone Diisocyanate?
CAS No is 4098-71-9.
What is the EC number of Isophorone Diisocyanate (IPDI)?
EC/EINECS No is 223-861-6.
What is the molecular formula of Isophorone Diisocyanate (IPDI)?
C₁₂H₁₈N₂O₂.
What is the molecular weight of Isophorone Diisocyanate (IPDI)?
It is approximately 222.28 g/mol.
What is the NCO content of Isophorone Diisocyanate (IPDI)?
The theoretical NCO content is approximately 37.8%. Values in the range of approximately 37.5–37.8% can be seen in high-purity commercial products.
What is the NCO equivalent weight of Isophorone Diisocyanate (IPDI)?
It is approximately 111.1 g/eq.
Is Isophorone Diisocyanate a liquid?
It is a colorless to slightly yellow, low-viscosity liquid at room temperature.
Why is Isophorone Diisocyanate used in the production of polyurethane?
The NCO groups react with the hydroxyl groups of the polyols to form urethane bonds and enable the formation of polyurethane chains.
What is the main advantage of IPDI over MDI and TDI?
Due to its cycloaliphatic structure, polyurethanes exposed to light may have a lower yellowing tendency than aromatic MDI and TDI systems.
Are IPDI and HDI the same product?
Both are diisocyanates that can be used in polyurethanes with high light resistance, but their molecular structure, equivalent weight, and ultimate mechanical properties differ.
Is monomeric IPDI and IPDI trimer the same product?
Monomeric IPDI is a difunctional diisocyanate; The IPDI trimer is a polyisocyanate structure with higher functionality and can be used as a hardener, especially in two-component polyurethane coatings.
Is IPDI used in waterborne polyurethane dispersions?
IPDI is one of the important diisocyanates used in the preparation of waterborne polyurethane dispersions.
Is IPDI used in adhesives and sealants?
IPDI-based polyurethane dispersions and NCO tipped prepolymers can be used in a variety of adhesive and sealant systems.
Does IPDI react with water?
Water depletes NCO groups and can lead to the formation of carbon dioxide. Therefore, the product must be protected from moisture.
Is IPDI used in food or cosmetics?
Monomeric IPDI is not directly used as a food ingredient, flavoring agent, or general cosmetic raw material.
What technical specifications are important when buying IPDI?
Purity, NCO content, color, viscosity, total chlorine, hydrolyzable chlorine and current batch COA values are the main control points.
What documents should be required for IPDI?
TDS, SDS and COA are the basic documents. Depending on the application, REACH and other regulatory documents may also be requested.
How should IPDI be stored?
It should be stored in tightly closed and suitable packaging protected from moisture, under the storage conditions recommended by the manufacturer.
ISOPHORONE DIISOCYANATE (IPDI) – TECHNICAL SUMMARY
Isophorone Diisocyanate (IPDI), known as Isophorone Diisocyanate, is a cycloaliphatic diisocyanate with the formula C₁₂H₁₈N₂O₂ and carrying two reactive NCO groups. It is identified by CAS No 4098-71-9 and EC No 223-861-6; its molecular weight is approximately 222.28 g/mol.
It has a nominal functionality of 2, a theoretical NCO content of about 37.8%, and an NCO equivalent weight of about 111.1 g/eq. A NOO content of about 37.5–37.8% and purity values of at least 99.5% can be seen in high-purity commercial products.
The presence of two isocyanate groups in the molecule in different chemical environments can provide an advantage in terms of controlled prepolymer synthesis. Cycloaliphatic structure, on the other hand, reduces the tendency to light-induced yellowing compared to aromatic diisocyanates such as MDI and TDI.
IPDI; It can be used in the production of coatings, adhesives, sealants, elastomers, waterborne polyurethane dispersions, moisture-curing prepolymers, urethane acrylates and special polyurethane resins.
Monomeric IPDI and IPDI trimer are not the same product. Product type, NCO content, purity, color, viscosity and chlorine values should be checked together during purchase and formulation.
Since the product reacts with water, it should be stored and transferred in dry conditions. TDS, SDS and batch COA are basic documents for product selection, safe use and formulation calculation.
It is recommended that companies planning to procure Isophorone Diisocyanate (IPDI) from Ataman Kimya confirm up-to-date product and offer information by sharing their usage area, monomeric IPDI requirement, minimum purity, NCO content, chlorine limits, quantity, packaging and technical document needs.
