Trade Name:PTSI / TI
Similar Name:Tosylisocyanate, p-toluenesulfonyl isocyanate, para-tosylisocyanate, 4-methylbenzenesulfonyl isocyanate
Molecular Formula:C8H7NO3S
Molecular Weight:197.21
Content %:≥ 99.0
UN No.:2206
CAS Number:4083-64-1

Harttive MSI MSI (PTSI), p-toluenesulfonyl isocyanate, a commonly used monoisocyanate, a highly reactive compound which is widely used as a dehydrating agent in chemical products, such as solvents, fillings, pigments and pitch tar areas. Being a moisture scavenger for solvent-based polyurethane (PU) coatings, sealants, adhesives and as an intermediate of various industrially important chemicals. p-toluenesulfonyl isocyanate (PTSI) prevents undesirable premature reaction of the painting & coating, therefore, it allows formulators to produce high quality polyurethanes. By using Harttive MSI in the production of polyurethane paints, the loss of gloss, yellowing and reactive foam caused by the wet surface in the system are all reduced. p-toluenesulfonyl isocyanate can also be a stabilizer additive for moisture-curing materials to prevent deterioration or/and discoloration while storage.


  • Eliminates the effects of humidity and prevents moisture related problems in polyurethane coatings
  • Low viscosity, monofunctional isocyanate which chemically reacts with water to form an inert amide
  • Used for the dehydration of solvents, fillers, pigments and bituminous tars
  • Improves the storage stability of diisocyanates against decomposition and discoloration
  • Removes moisture introduced with solvents, pigments, and fillers in Single-component and Dual-component PU systems


  • 6 months since the date of production.


20 KG/Iron Drum.

It can be packaged on demand. Please inquire.      

Harttive MSI (PTSI) reacts with water, giving off carbon dioxide and resulting in the formation of reaction products which are soluble in conventional paint formulations. Approximately 12g of the stabilizer is theoretically required for reacting with 1g of water. Experience has shown, however, that the reaction is more effective in the presence of a surplus of HARTTIVE MSI(PTSI). Compatibility with paint binders should always be tested beforehand.

p-toluenesulfonyl isocyanate is recommended to be used as a chain terminator during polymerization and as a remover of unwanted reactive functional groups in PU raw materials. In coal tar PU coatings, Harttive MSI can be used to neutralize amines and OH functional groups and remove water in tar to avoid foaming and premature gelation when tar is mixed with PU prepolymer.


Adding 1.2% of Harttive MSI to tar kerosene can completely neutralize the 0.1% active amine and OH functional groups contained in tar kerosene. Similarly, adding 2.4% of Harttive MSI can remove 0.1% of water from tar, zinc powder, paint, and solvents. When using a higher amount of Harttive MSI than normal, it can neutralize the moisture, amines or active OH groups in the coating formulation, such as Single-component moisture-cured PU or Dual-component PU causing the curing rate and the final physical properties to be significantly reduced.

Chemical NameTosylisocyanate, p-toluenesulfonyl isocyanate, para-tosylisocyanate, 4-methylbenzenesulfonyl isocyanate
Supply formNon-solvent type, colorless liquid
SpecificationActive substance (Gas-chromatographic method): 98±2%
Other dataFlash point ........150°C (DIN51584)
 Density..............Approx. 1.29g/cm3 at 20°C (DIN51757)
 *These values are general information and are not parts of the product specification
SolubilitySoluble in most common solvents. Can NOT be used with solvents containing active hydrogen functional groups such as alcohols, amines, etc. This is because they will react with the terminal isocyanate functional groups of the prepolymer.
StorageHarttive MSI (PTSI) is moisture-sensitive and should therefore always be stored in tightly sealed original containers at temperatures between 5°C and 30 °C. Once opened, containers should be resealed immediately after each removal of the product. Keep away from alcohols, strong bases, amines, strong oxidizing agents.
Handling precautionsThe product is a highly reactive compound and therefore needs to be handled with particular care. The safety data sheet should be heeded. It contains information on labeling, transport and storage as well as handling, product safety and ecological effects.
 The product reacts spontaneously and very vigorously with water, alcohols, amines, acids and alkalis. Such substances must therefore not be poured into vessels already containing the product. The reaction with water yields carbon dioxide at quantities of 1.3 liters per gram of water. The sudden formation of large amounts of gas in a container into which water has penetrated, may cause the container to explode, even if the seal has already been broken.
 Care must therefore be taken during transportation, storage and handling of HARTTIVE MSI(PTSI) to prevent the penetration of moisture into the containers. Once added to the paint as a drying agent, existing guideline on the application of paint containing solvents must be applied. Additional precaution is unnecessarily provided that the addition rate is proportional to the water content does not exceed about 5% of the total formulation.
 p-toluenesulfonyl isocyanate is a very reactive compound. Although not very toxic, it causes severe irritation of skin and mucous membranes. It is therefore essential to prevent exposure of skin, eyes and airways to undiluted Harttive MSI (PTSI).
 Safety goggles and protective gloves must be worn and the inhalation of vapors and aerosols must be avoided when handling the product. To protect the skin, preventive application of an appropriate barrier preparation is recommended. Breathing apparatus is necessary in inadequately ventilated work-places. Use of an air-fed hood or a face mask with an A2-P2 combination filter is advisable. Contaminated areas of skin should be washed immediately with plenty of soap-suds. Contaminated clothing should be removed immediately. In the event of contact with the product, the eyes should be rinsed carefully and thoroughly with water and medical advice should be sought. In the event of inhalation of quite large amounts of vapor or dust of products, any resulting irritation of the airways should be treated symptomatically (in the same way as any symptoms of irritation cause by inhalation of irritant substances). Medical advice must always be sought.
Package20 KG/Iron Drum
 180 KG/Iron Drum
Waste DisposalProduct residues can be disposed of in accordance with the following guidelines:
 1. Containers must be emptied as completely as possible. Do NOT clean them with water.
 2. Pools of Harttive MSI (PTSI) on the floor or on a lab bench can be carefully removed with water or by covering them with the paste-like materials described below.
 3. Using below materials to clean containers or leave empty containers open for couple days in safe areas. Harttive MSI (PTSI) is sensitive to moisture and the residues within empty containers can be reacted with the humid air to form white solids.




Tertiary butyl alcohol
Butyl acetate (Bac)
Diatomaceous earth
(industrial grade)






*100g of the solution is sufficient to react with approx. 42g of Harttive MSI (PTSI).


Harttive MSI (PTSI) is used as a stabilizer for moisture-curing materials. It prevents undesirable premature reaction of the painting & coating. p-toluenesulfonyl isocyanat is commonly applied as following areas:

  • Single-component and Dual-component polyurethane adhesives and sealants.
  • Single-component and Dual-component polyurethane coatings and paints.
  • Solvents
  • Pigments
  • Fillers
  • Reagents