Methylene bisphenyl isocyanate

Synonyms & Trade Names

4,4'-Diphenylmethane diisocyanate, MDI, Methylene di-p-phenylene ester of isocyanic acid, Methylene bis(4-phenyl isocyanate)

CAS No.

101-68-8

RTECS No.

NQ9350000

DOT ID & Guide

Formula

CH₂(C₆H₄NCO)₂

Conversion

1 ppm = 10.24 mg/m³

IDLH

75 mg/m³
See: 101688

Exposure Limits

NIOSH REL

TWA 0.05 mg/m³ (0.005 ppm) C 0.2 mg/m³ (0.020 ppm) [10-minute]

OSHA PEL

C 0.2 mg/m³ (0.02 ppm)

Measurement Methods

NIOSH 5521 , 5522 , 5525;
OSHA 18
See: NMAM or OSHA Methods

Physical Description

White to light-yellow, odorless flakes. [Note: A liquid above 99°F.]

Molecular Weight

250.3

Boiling Point

597°F

Melting Point

99°F

Solubility

0.2%

Vapor Pressure

(77°F): 0.000005 mmHg

Ionization Potential

Specific Gravity

1.23 (Solid at 77°F) 1.19 (Liquid at 122°F)

Flash Point

390°F

Upper Explosive Limit

Lower Explosive Limit

Combustible Solid

Incompatibilities & Reactivities

Strong alkalis, acids, alcohol [Note: Polymerizes at 450°F.]

Exposure Routes

inhalation, ingestion, skin and/or eye contact

Symptoms

irritation eyes, nose, throat; resp sensitization; cough, pulmonary secretions, chest pain, dyspnea (breathing difficulty); asthma

Target Organs

Eyes, respiratory system

Personal Protection/Sanitation

(See protection codes)
Skin:Prevent skin contact
Eyes:Prevent eye contact
Wash skin:When contaminated
Remove:When wet or contaminated
Change:Daily

First Aid

(See procedures)
Eye:Irrigate immediately
Skin:Soap wash immediately
Breathing:Respiratory support
Swallow:Medical attention immediately

Respirator Recommendations

NIOSH

Up to 0.5 mg/m³:
(APF = 10) Any supplied-air respirator*

Up to 1.25 mg/m³:
(APF = 25) Any supplied-air respirator operated in a continuous-flow mode*

Up to 2.5 mg/m³:
(APF = 50) Any self-contained breathing apparatus with a full facepiece
(APF = 50) Any supplied-air respirator with a full facepiece

Up to 75 mg/m³:
(APF = 2000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode

Emergency or planned entry into unknown concentrations or IDLH conditions:
(APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode
(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus

Escape:
(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted organic vapor canister having an N100, R100, or P100 filter.
Click here for information on selection of N, R, or P filters.
Any appropriate escape-type, self-contained breathing apparatus

Important additional information about respirator selection

Methylene bisphenyl isocyanate

NIOSH REL

OSHA PEL

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