N-Phenylmaleimide (IMILEX™-P) N-phenylmaleimide

  • Main Applications

    High HDT thermoplastic resins, Paints and coatings, Adhesives, Pharmaceutical and agrochemical intermediates, Bactericides, Fungicides, Underwater organism repellents, Rubber vulcanization modifiers, Photosensitive resins, Insulating varnishes

  • Applications
  • Functions

Basic Information

Chemical Structure
Chemical Formula C10H7NO2
CAS No.941-69-5
Molecular Weight 173.16
Packing TypePaper bag (20 kg), Container bag (800 kg)

N-phenylmaleimide (IMILEX™-P) is a highly reactive compound, which Nippon Shokubai was the first in the world to commercialize using our proprietary technology. With its various unique features such as radical and ionic polymerization, photosensitivity, and disinfectant properties, IMILEX™-P can be used in a wide range of applications.

Typical Properties

Item Unit Representative Values
Appearance Yellow solid
Melting Point 88 – 90
Boiling Point 135 (0.48 kPa)
SolubilityGenerally, IMILEX™-P dissolves well in organic solvents, and is highly soluble particularly in acetone, DMF, acetic acid esters, and benzene, etc.
Please refer to the Section 6. Solubility of IMILEX™-P.


Item Unit Standard Values
Appearance Yellow flakes
Melting Point 89 min.
Water Content wt% 0.1 max.

Copolymerization Reactivity

Listed below are the monomer reactivity ratios in the copolymerization of IMILEX™-P (M1) and various monomers (M2).

Styrene 0.0470.0120.0006
Vinyl Chloride 1.2600.0620.08
Methyl Methacrylate 0.1831.0220.19
Source: Journal of Macromolecular Science, Part A, Vol.11, p.267 (1977); Memoirs of the Faculty of Engineering, Yamaguchi University, Vol.27, p.257 (1977)

Packing Type

Paper bag (20 kg), Container bag (800 kg)

Applicable Laws and Regulations

Foreign laws and regulations on chemical substances

USA TSCA: Listed
SARA Title III 313: Not listed
SNUR: Not listed
Canada CEPA: NDSL listed
Australia AICS: Listed
Europe EINECS: 213-382-0
Classification, etc.: Not listed on 67/548/EEC ANNEX I
Korea ECL: KE-28389
Switzerland SWISS: Not listed
The Philippines PICCS: Listed

Solubility of IMILEX™-P (Amount of IMILEX-P soluble to 100 g of solvent at 25°C)

Solvent Solubility (g) Solvent Solubility (g) Solvent Solubility (g)
Acrylonitrile 100Ethyl acetate 29o-Xylene 14
DMF51Benzene 28Methanol 9
Acetone 48Styrene 21Ethanol 5
THF44Toluene 18Water0.11
MEK39Butyl acetate 18  

Examples of Applications

High HDT thermoplastic resins, Paints and coatings, Adhesives, Pharmaceutical and agrochemical intermediates, Bactericides, Fungicides, Underwater organism repellents, Rubber vulcanization modifiers, Photosensitive resins, Insulating varnishes

Details of Functions

Modifies various resins

IMILEX™-P has radical polymerization properties and can be easily homopolymerized or copolymerized with other vinyl monomers.

Applications of Resin Modifiers

Resins Purpose Applications
Styrenic Polymers
(ABS, ACS, AES, AAS, etc.)
Improves heat resistance and heat stability Vehicle parts, light electrical appliances
PVCImproves the heat resistance of PVC-ABS compounds Housing for televisions, office devices, etc.
PMMAImproves the heat resistance of acrylic resins Optical disc substrates, optical fibers, lighting equipment parts
Polymer Alloys Modifies PA, PC, PBT Vehicle parts, household electrical appliances parts, office devices
(Maleic Anhydride, N-Phenylmaleimide Copolymer)
 Water-soluble hot-melt adhesives, honeymoon adhesives
Phenolic Resins Improves heat resistance Heat-resistant adhesives of printed-circuit boards

Comparison of N-phenylmaleimide-modified ABS (IMILEX™-P) and α-methylstyrene-modified ABS

 N-phenylmaleimide-modified ABS α-methylstyrene-modified ABS
Monomers for Improving Heat Resistance IMILEX™-P α-methylstyrene
Copolymerization Rate Fast Slow
ΔHDT/wt% – Monomer Additive Amount 1.5 – 2.5°C Up to 0.5°C
HDT Upper Limit 150°C is also possible Up to 115°C
Thermal Decomposition Temperature High Low
Melt Flow Rate High Low

Comparison of physical properties of N-phenylmaleimide-modified ABS (IMILEX™-P) and α-methylstyrene-modified ABS at same HDT

PropertiesUnit N-phenylmaleimide-modified ABS α-methylstyrene-modified ABS
Heat Deflection Temperature 105105
Izod Impact Strength
(1/2″, Notched)
Melt Flow Rate
(220°C/10 kg Load)
Tensile Strength kg/cm2455440
Flexural Strengthkg/cm2760720
Source: NIKKEI NEW MATERIALS, March 9, 1992
Example of copolymerization
Initial composition in reactorMethylethylketone25.6wt%
Styrene 6.5wt%
Composition in dropping vesselMethylethylketone23.6wt%
IMILEX™-P 7.8wt%
Styrene 35.7wt%
Temperature85 C
Period5 hours

After the reaction, the reaction mixture is poured into plenty of methanol. Then, the copolymer is separated from the solution by filtration and dried under reduced pressure.

Properties of IMILEX-P/styrene copolymer

Composition:Styrene/N-Phenylmaleimide = 70/30 (Molar ratio)
Molecular Weight :Mw = 10*104 (G.P.C., Polystyrene standard)
  5*104 (G.P.C., Polystyrene standard)

Glass transition temp.:165(DSC)

Modification of PVC

PVC is blended with ABS resin in order to improve its low impact strength at low temperature, however, the softening temperature of the blend is still low. IMILEX-P is effective for improvement of the softening temperature.

Handling and Hazards

Please refer to Safety Data Sheet (SDS) for detail)

Skin irritationMild to moderately irritative
Skin inflames when IMILEX-P is kept contacting with skin
Eye irritationModerately irritative
Acute oral toxicity (LD50)128mg/kg (rat, male), 148mg/kg (rat, female)
Handling and Protection

Read material safety data sheet (MSDS) before handling IMILEX-P. Put on rubber gloves, long sleeve clothing, gas mask for organic gas and protective spectacles to avoid contact with skin, especially contact with eyes when handling IMILEX-P. Take off the clothing which IMILEX-P contacts after handling. If you have any question about handling IMILEX-P, please contact us.

First Aid

Contact with skin: Flush with running water using a mild soap. Contact with eyes: Gently rinse with clean water for at least 15 minutes and call a physician.


Store in a warehouse at temperature lower than 40 C. Avoid sunshine and moisture.

Please read Safety Data Sheet (SDS) before handling.