MOCA (4,4'-METHYLENE-BIS(2-CHLOROANILINE))

CAS Number: 101-14-4.
EC Number: 202-918-9.
Molecular Formula: C13H12Cl2N2.
Molecular Weight: Approximately 267.15 g/mol; references may round this to 267.2 g/mol.
Boiling Point: Decomposition occurs before ordinary atmospheric boiling; a reliable normal boiling point is not assigned here.
Melting Point: Approximately 110 degrees Celsius in chemical safety references; one commercial pellet-grade sheet specifies a melting range of 98-102 degrees Celsius.
Viscosity: Not applicable as a neat-liquid property of the room-temperature solid; molten-grade viscosity requires a stated temperature and method.
Density: Approximately 1.44 g/cm3 for the solid in chemical safety references; this is not its bulk density or a molten-liquid density.

COMMON PRODUCT AND CHEMICAL NAMES

MOCA
MBOCA
MbOCA
4,4'-Methylene-bis(2-chloroaniline)
4,4'-Methylenebis(2-chloroaniline)
4,4'-Methylenebis(o-chloroaniline)
Methylenebis(ortho-chloroaniline)
4,4'-Methylenebis(2-chlorobenzenamine)
2,2'-Dichloro-4,4'-methylenedianiline
3,3'-Dichloro-4,4'-diaminodiphenylmethane
4,4'-Diamino-3,3'-dichlorodiphenylmethane
Bis(4-amino-3-chlorophenyl)methane
DACPM

DESCRIPTION AND CHEMICAL IDENTITY

MOCA is an aromatic diamine supplied in solid forms such as pellets, granules or flakes. Chemical references describe colorless crystals, while technical products can appear pale yellow, tan or light brown.
The abbreviations MOCA and MBOCA refer to the same principal chemical identity. However, a product marketed as a liquid alternative or a modified curative should be assessed by its actual composition rather than assumed to be neat MOCA.
MOCA should also be distinguished from methylenedianiline and methylene diphenyl diisocyanate. Similar names and related aromatic structures do not make these chemicals interchangeable: MOCA carries amino groups, while a diisocyanate carries isocyanate groups.

The phrase curing agent describes the participation of MOCA in polymer formation. In conventional amine-cured polyurethane prepolymer systems, the diamine reacts with terminal isocyanate functionality and becomes incorporated into the polymer.
Commercial grades of MOCA may differ in assay, amine value, water, color, insoluble matter and residual manufacturing components. A CAS number confirms the principal substance identity but is not a complete purchasing specification.
MOCA is associated with serious occupational and environmental hazards. An industrial product profile must therefore consider performance, exposure control and the legal basis for the intended use together.
For an enquiry about MOCA to Ataman Chemicals, the intended prepolymer and application should be identified alongside the required chemical and physical specifications. Neither a familiar abbreviation nor an established application establishes unrestricted availability or suitability.

MOLECULAR STRUCTURE AND CURING MECHANISM

Each MOCA molecule contains two primary aromatic amino groups. The aromatic rings are connected through a methylene bridge, and each ring has a chlorine substituent adjacent to its amino group.
The amino groups of MOCA react with suitable isocyanate groups to form substituted urea linkages. When the starting prepolymer already contains urethane groups, the resulting material can contain both urethane and urea structures.
In a simplified linear chain-extension description, one MOCA molecule can connect isocyanate-terminated chains through its two amino groups. This increases chain length and introduces aromatic urea-containing segments.
The terms chain extender, curative and crosslinking agent are used in commercial descriptions, but they do not mean that every MOCA formulation forms the same covalent network. Network formation depends on the functionality of the whole system and any relevant secondary chemistry.

The urea-containing portions contribute to the hard-segment structure within a segmented elastomer. The softer prepolymer-derived portions and the hard segments together influence mechanical behavior rather than allowing the curative alone to determine every property.
Reaction rate and useful working time for MOCA depend on the prepolymer, temperature, composition and mixing conditions. The presence of aromatic amino groups and chlorine substituents is not sufficient to calculate a universal pot life.
MOCA is consumed as a reactant during cure. Calling it a catalyst would obscure both the need for an appropriate mixing ratio and the possibility of residual unreacted material when conversion or formulation balance is inadequate.

AMINE EQUIVALENCE AND FORMULATION BASIS

For conventional polyurethane chain-extension calculations, MOCA is commonly treated on a two-amine-group basis. Dividing its molecular weight by two gives an equivalent weight of approximately 133.6 g/equivalent.
That convention is important because each primary amino group initially reacts with one isocyanate group to form a urea linkage. Counting every nitrogen-bound hydrogen as an identical polyurethane chain-extension equivalent would use a different basis and can produce an incorrect curative calculation.
For an ideal pure compound, two amino groups per molecule correspond to approximately 7.49 mmol of amino groups per gram. This helps explain why a commercial amine value may be expressed near 7.4-7.6 mmol/g.
An amine result expressed in mmol/g should not be copied into a record labeled mg KOH/g without conversion and method confirmation. Numerical values from different analytical conventions are not automatically comparable.

On the usual polyurethane calculation basis, the theoretical curative amount depends on the prepolymer NCO content, the selected equivalent weight and the intended amine-to-isocyanate ratio. A commercial formulation may deliberately specify a ratio different from exact theoretical equivalence.
The calculation relationship can be written as: curative parts per 100 parts prepolymer = amine equivalent weight x numerical NCO percentage x selected stoichiometric fraction / 42.02. This assumes the relevant equivalent convention and does not replace the validated formulation instructions.
For a purely illustrative calculation using 133.6 g/equivalent, 5.0% NCO and a stoichiometric fraction of 1.00, the result is approximately 15.9 parts of ideal MOCA per 100 parts prepolymer. This is an arithmetic example, not a recommended production recipe or a universally suitable mixing ratio.
Actual dosing should follow the approved system, the specified MOCA assay and the current prepolymer analysis. A change in NCO content or curative composition can affect the ratio even when the commercial product names remain unchanged.

PHYSICAL AND CHEMICAL PROPERTIES

The following properties combine chemical reference information, theoretical calculations and a clearly identified commercial-grade example. They are not a consolidated specification guaranteed for every MOCA product.
Physical State: Solid at normal room temperature.
Appearance: Colorless crystalline material in descriptions of the chemical; technical forms include pale yellow, tan or light-brown pellets, flakes and granules.
Odor: Often described as faintly amine-like. Odor cannot be used to confirm that exposure is adequately controlled.
Molecular Formula: C13H12Cl2N2.
Molar Mass: Approximately 267.15 g/mol.
Primary Amine Functionality: Two aromatic amino groups per molecule.
Conventional Polyurethane Amine Equivalent Weight: Approximately 133.6 g/equivalent, calculated on the two-amino-group chain-extension basis.
Calculated Amino-Group Concentration: Approximately 7.49 mmol/g for the ideal pure compound. This calculation is not a batch assay.
Melting Point: About 110 degrees Celsius is reported in chemical safety references. A representative commercial pellet grade separately specifies 98-102 degrees Celsius, so the selected grade and test method must accompany a purchasing limit.
Boiling Behavior: Thermal decomposition precedes a useful ordinary atmospheric boiling measurement. An estimated or unrelated boiling figure should not be presented as a practical processing limit.
Thermal Decomposition: Safety references describe decomposition at approximately 200 degrees Celsius, with one reference listing 202 degrees Celsius. This is hazard information rather than a guarantee of stability at every lower temperature or residence time.
Decomposition Products: Heating to decomposition can release toxic or corrosive fumes, including hydrogen chloride and nitrogen oxides. The behavior of a formulated mixture may differ from that of the neat substance.
Solid Density: Approximately 1.44 g/cm3 in reference descriptions. Temperature and physical state should accompany any more precise density figure used for process calculations.
Bulk Density: Not assigned here. Pellets, flakes and powder beds contain void space, so their bulk density cannot be obtained by treating them as a solid block of density 1.44 g/cm3.
Molten Density: A separate temperature-dependent liquid property. The reference solid density should not be used automatically to calibrate a heated volumetric metering system.
Vapor Pressure: One occupational reference reports 0.00001 mmHg at 25 degrees Celsius, approximately 0.0013 Pa. This low room-temperature value does not exclude dust exposure, skin absorption or exposure during heating.
Water Solubility: Very low; a technical reference reports approximately 14 mg/L without a temperature stated in its summary. Other descriptions use practically insoluble or slightly soluble, and the exact concentration should be tied to the test conditions.
Organic-Solvent Solubility: Solubility is reported in several organic solvents, with the extent depending on the solvent and conditions. This information does not establish that a solvent is suitable for workplace cleaning, product formulation or disposal.
Acid-Base Character: MOCA is a weak base. Interactions with strong acids and other incompatible chemicals must be assessed independently of its desired reaction with isocyanate groups.
pH: A single pH number is not an intrinsic property of dry solid MOCA. Any aqueous preparation requires a stated concentration, preparation procedure and analytical method.
Octanol-Water Partition Coefficient: A reference log Pow value is approximately 3.9. This is a partitioning descriptor and should not be treated as a direct prediction of exposure, degradation or permissible release.
Flash Point: A chemical safety reference gives 113 degrees Celsius by a closed-cup method. This is method-specific hazard information, not an approved heating setpoint or a safe operating boundary.
Combustibility: MOCA is combustible and can generate hazardous fire effluent. It should not be described as nonflammable merely because it is a solid with low room-temperature vapor pressure.
Neat-Liquid Viscosity: Not applicable to the room-temperature solid. A molten viscosity result requires temperature, grade identity and measurement conditions; no unverified universal figure is assigned.
Mechanical Properties: Hardness, tensile strength, elongation, tear resistance and compression set describe a cured elastomer formulation, not the uncured MOCA chemical.
Color Stability: Initial color and color after heating are different controls. A commercial claim about heat-color stability should remain specific to its grade and test conditions rather than becoming a property guaranteed for all MOCA.

REPRESENTATIVE COMMERCIAL GRADE CHARACTERISTICS

One published MOCA pellet-grade technical sheet describes pale yellow pellets with a melting range of 98-102 degrees Celsius, a minimum purity of 99% and a water content below 0.20%. Its amine value is stated as 7.4-7.6 mmol/g.
These figures illustrate how a commercial grade can be specified. They are not a declaration of the specification, availability or batch performance of material offered through Ataman Chemicals.
The same type of documentation may include color, insoluble matter and residual-amine limits. A result labeled free aniline must retain that analytical meaning; it should not automatically be relabeled as ortho-chloroaniline or used to identify the complete impurity profile.

For MOCA, purity and amine value provide related but different information. An assay measures the principal substance under its method, while the amine result measures the response of relevant basic or reactive groups under another method.
Likewise, a melting interval is not a complete identity or purity test. A MOCA grade change should be assessed against the agreed specification and its performance in the target polymer system.
A low-dust physical form can assist controlled handling but does not remove the chemical hazard. Broken pellets, deposited residues, contaminated tools and molten material still require effective exposure controls.

APPLICATIONS

Cast Polyurethane Elastomers: MOCA is principally used as a curative for suitable isocyanate-terminated polyurethane prepolymers. Its reaction with the prepolymer develops the molecular structure needed for molded elastomer components.
The resulting materials can combine elasticity with substantial load-bearing and wear performance. Those characteristics belong to the complete elastomer system and depend on the prepolymer, curative ratio, processing and conditioning.

Hot-Cast Prepolymer Systems: Established industrial processes use MOCA with compatible prepolymers in controlled heated casting operations. The solid curative and liquid prepolymer must be incorporated according to the approved system instructions.
Published prepolymer documentation confirms use with TDI-terminated polyether systems. It does not follow that MOCA is compatible at the same ratio and temperature with every isocyanate prepolymer, and a change in chemistry requires a separate evaluation.

Industrial Wheels and Tires: MOCA-cured cast elastomers are documented for wheels and industrial tire applications, including material-handling equipment. Relevant service demands can include load, repeated deformation, abrasion and the temperature generated during operation.
A suitable evaluation should therefore consider the actual wheel geometry, duty cycle and bonding arrangement as well as a simple hardness result. The raw MOCA curative does not establish a load rating, rolling resistance or service life.

Rollers and Roller Coverings: Compatible cured polyurethane systems are used for rollers in industrial conveying and processing equipment. The elastomer can be selected to provide a required combination of deformation behavior, wear resistance and surface characteristics.
Roller performance also depends on the supporting core, attachment, dimensions and operating environment. A MOCA-based formulation should be tested for the intended contact conditions and any liquids or contaminants encountered in service.

Conveyor and Industrial Belting: Castable urethane products cured with MOCA include belts and related conveying components. The material system must tolerate the relevant tension, flexing, repeated contact and wear conditions.
The designation MOCA-cured does not specify one belt composition or construction. Belt design, reinforcement where present and the complete polymer formulation remain part of the application qualification.

Bushings and Engineered Moldings: MOCA-containing curative systems are used in cast products such as bushings and gears. These parts can require different combinations of dimensional control, stiffness, impact response and wear resistance.
A choice of MOCA curative suitable for one component should not automatically be applied to another. The required deflection, contact stress and manufacturing tolerances need to be considered with the elastomer properties.

Shock-Absorption Pads and Resilient Elements: Cast urethane rubber products include pads and similar components designed to deform under load. MOCA participates in developing the cured structure, while the full formulation determines damping, rebound and compression behavior.
For a shock-absorption application, a high tensile strength alone is insufficient to demonstrate suitability. Relevant comparisons can include repeated loading, permanent deformation and the response at the expected operating temperatures.

Seals and Gaskets: Suitable cast polyurethane systems are used in sealing components. The required material must be evaluated against the actual medium, pressure, movement, temperature and compression conditions.
It is inaccurate to infer universal chemical resistance from the curative name MOCA. The underlying polymer chemistry and finished formulation strongly influence swelling, hydrolytic behavior and long-term sealing performance.

Rods, Sheets and Machinable Stock: Prepolymer systems cured with MOCA can produce molded stock subsequently shaped into industrial components. Processing consistency and freedom from defects matter where the stock will be machined or placed under repeated stress.
A broad material description does not establish dimensional stability or machining quality. The actual casting process, cure state and conditioning should be connected to the requirements of the finished part.

Screening and Wear Components: Compatible cast polyurethane systems are documented for sieve plates and related industrial products. Such applications can require a balance between flexibility, abrasion behavior and resistance to repeated mechanical contact.
The preferred formulation depends on particle impact, geometry and the operating environment. No universal wear improvement can be attributed to MOCA independently of the polymer system and service test.

Polyether-Based Systems: Suitable polyether prepolymers can be cured with MOCA for engineered elastomers. A published system may demonstrate particular mechanical or hydrolytic properties, but those results should remain linked to that prepolymer and formulation.

Polyester and Polycaprolactone-Based Systems: MOCA is also documented in commercial prepolymer ranges based on polyester or polycaprolactone chemistry. Different soft-segment chemistries can lead to different balances of physical properties and environmental resistance.
Consequently, a curative familiar from one prepolymer family is not sufficient to predict the properties of another. The approved dosage, working time and resulting performance should be established for the actual system.
Specialty Coatings and Adhesive Systems: Industrial documentation also describes MOCA in certain polyurethane coating and adhesive applications. These uses need specific formulation support and a clear exposure-control and regulatory basis.
They should not be interpreted as a recommendation for uncontrolled spraying, consumer application or substitution into an unrelated coating. A cast-elastomer formulation and a coating application have different requirements for processing and exposure assessment.

Established-Product Maintenance: MOCA may be relevant where an existing industrial component has already been qualified using a particular prepolymer-curative combination. Maintaining consistency requires more than matching the curative abbreviation on a purchase order.
The incoming MOCA grade, prepolymer analysis, formulation ratio and performance tests should remain connected to the approved material record. This is particularly important when an existing production process is transferred or an additional material source is considered.

Application Boundaries: The established uses above describe where the chemistry has been used, rather than unrestricted approval for every product category. Food-contact, medical, drinking-water or other regulated applications require their own applicable evidence and must not be inferred from industrial elastomer use.

PROCESSING AND PERFORMANCE CONSIDERATIONS

MOCA processing must follow the validated instructions for the selected prepolymer-curative system. There is no universal melt temperature, working time, mold temperature or post-cure schedule that applies to all products.
The analytical NCO content provides a basis for calculating the prepolymer's available isocyanate functionality. A nominal product description should not replace the specified analysis when a formulation depends on controlled equivalence.
Water is a separate source of reaction variability in an isocyanate-containing system. It can consume isocyanate groups and generate carbon dioxide, contributing to bubbles or changes in the intended reaction balance.
The dryness of the MOCA curative alone does not establish a dry process. Prepolymer, additives, equipment and handling can also introduce moisture.
Complete and uniform incorporation matters because local concentration differences can create uneven cure. An acceptable average mixing ratio does not by itself demonstrate that the mixture is homogeneous throughout a casting.

Working time is specific to the formulation and measurement conditions. A time measured for a small sample cannot automatically be used as the available filling time for a larger casting with a different thermal history.
The reaction generates heat, and part geometry and batch size can influence temperature development. A scale change should therefore be evaluated against the established processing window rather than justified solely by equal component ratios.
Cure and post-cure can affect the properties measured on the finished elastomer. Compare materials after equivalent conditioning and using the same test methods so that differences are not attributed incorrectly to the curative grade.
For a wheel or roller, an evaluation may need to include compression behavior and repeated loading as well as hardness. For a seal, media exposure and dimensional response may be more relevant than a tensile result alone.
The melting range, flash point and decomposition information describe different phenomena. None of these numbers independently supplies an approved maximum operating temperature or removes the need for controlled equipment and exposure assessment.

STARTING FORMULATION APPROACHES FOR MOCA (4,4'-METHYLENE-BIS(2-CHLOROANILINE))

The following examples illustrate how MOCA (4,4'-Methylene-bis(2-chloroaniline)) can be evaluated during polyurethane formulation and process development. They are preliminary laboratory screening approaches, not validated commercial recipes, production instructions or finished formulations with established regulatory compliance.

MOCA, also known as MBOCA, 4,4'-methylenebis(2-chloroaniline) or 3,3'-dichloro-4,4'-diaminodiphenylmethane, is an aromatic diamine curative and chain extender for compatible isocyanate-terminated prepolymers. These examples focus on supplier-approved TDI-based systems. They assume dry, unblended MOCA with a nominal diamine-curing equivalent weight of 133.6 g/equivalent; commercial blends require their own verified equivalent weight and processing instructions.

All formulation quantities below are parts by mass per 100 parts of supplied prepolymer. They are not percentages of the complete mixed formulation. Use the actual batch NCO content and the curative supplier's declared equivalent weight. Laboratory trials, mechanical testing, residual-curative assessment, workplace exposure controls and jurisdiction-specific regulatory review are required before implementation.

MOCA presents serious carcinogenicity and skin-absorption hazards. These examples are for controlled industrial development facilities equipped for contained charging, temperature-controlled curative handling, extraction and contamination control. Review current safety data sheets for both MOCA and the isocyanate prepolymer, and verify any applicable restrictions or authorization obligations. A cured appearance or a hardness result does not establish the absence of residual MOCA.

EXAMPLE 1: MOCA STOICHIOMETRY SCREENING IN A POLYETHER-BASED CAST POLYURETHANE ELASTOMER

Objective: Determine how the MOCA-to-NCO equivalent ratio affects processing time, hardness, tensile properties, tear resistance and compression behavior in a selected polyether urethane system.

Starting components:

MOCA-compatible TDI/polyether prepolymer: 100 parts by mass

Illustrative measured prepolymer NCO content: 5.00% by mass

MOCA curative/NCO equivalent ratios: approximately 0.90, 0.95 and 1.00, only within the prepolymer supplier's approved range

MOCA (4,4'-Methylene-bis(2-chloroaniline)): respectively approximately 14.31, 15.10 and 15.90 parts

Additional curatives, catalysts, plasticizers, fillers and pigments: omitted during the initial comparison

Prepolymer conditioning, MOCA preparation, mixing, mold temperature, specimen geometry and cure/post-cure schedule: held constant using the approved processing instructions

For the stated assumptions, MOCA parts = NCO percentage × 133.6 / 42.02 × curative/NCO equivalent ratio. Enter the NCO percentage as 5.00 in this equation, not 0.0500. The ratios above express curative equivalents divided by NCO equivalents and should not be confused with an oppositely defined isocyanate index.

Application approach:

Verify the prepolymer identity, actual NCO result, moisture specification and compatibility with the selected MOCA grade.
Calculate the curative requirement for each trial from the batch data.
Condition the prepolymer and prepare MOCA in dedicated, contained, temperature-controlled equipment according to supplier instructions.
Meter the components with calibrated equipment and mix by the approved procedure while limiting moisture and air incorporation.
Cast matched test specimens within the measured working time.
Record material temperatures, mixing time, working time and the specimen temperature profile.
Complete the specified cure and post-cure before conditioning all samples identically.
Compare hardness, tensile strength, elongation, tear resistance, rebound and compression set as relevant to the application.
Measure extractable or residual MOCA using a validated method appropriate to the material, and repeat the most balanced ratio.

A higher curative level is not automatically a better cure. Select the equivalent ratio from the combined processing, mechanical and residual-curative results. Recalculate whenever NCO content or curative equivalent weight changes.

Prevent skin contact with solid or molten MOCA and control airborne exposure through containment and extraction. Select chemical and thermal protection from the actual process assessment and glove-permeation data; protective equipment supplements the engineering controls.

EXAMPLE 2: MOCA CURATIVE-RATIO EVALUATION IN A POLYESTER-BASED CAST POLYURETHANE

Objective: Evaluate the balance between cure development, abrasion resistance, tensile behavior and dimensional stability in a specified polyester urethane prepolymer.

Starting components:

MOCA-compatible TDI/polyester prepolymer: 100 parts by mass

Illustrative measured prepolymer NCO content: 4.00% by mass

MOCA curative/NCO equivalent ratios: approximately 0.90, 0.95 and 1.00, restricted to the supplier-approved range

MOCA (4,4'-Methylene-bis(2-chloroaniline)): respectively approximately 11.45, 12.08 and 12.72 parts

Additional chain extenders, fillers, pigments and catalysts: omitted during the initial comparison

Drying or conditioning, mixing, specimen geometry, mold conditions, cure/post-cure and test conditioning: held constant according to the exact polyester-prepolymer instructions

These quantities use the same nominal MOCA equivalent weight as the first example. A polyether formulation must not be transferred directly to a polyester system, even when the nominal NCO content appears similar. Backbone chemistry and the approved processing window remain important.

Application approach:

Check the prepolymer batch NCO value, moisture and the recommended MOCA stoichiometric range.
Prepare the prepolymer and curative using the specified conditioning and contained handling procedures.
Meter and mix each composition using the same approved sequence.
Cast matched specimens and monitor working time, temperature development and visible defects.
Apply the complete supplier-approved cure and post-cure schedule.
Condition specimens for a defined period before measuring hardness, tensile properties, tear resistance and abrasion loss.
Compare dimensional change and compression behavior where relevant to the intended component.
If moisture, hot water or oils are expected in service, perform separately defined exposure tests and compare retained properties.
Check residual or extractable MOCA before selecting the most suitable formulation.

Neither room-temperature hardness nor demoldability alone establishes final service performance. Exposure tests must reflect the intended environment and should not be replaced by a general claim that all MOCA-cured polyester elastomers have the same durability.

Keep moisture under control because water can react with isocyanate groups and cause gas formation or defective castings. Provide extraction for prepolymer and heated-curative handling, prevent MOCA skin contamination and follow the current chemical-specific hygiene and exposure-monitoring program.

EXAMPLE 3: MOCA-CURED POLYURETHANE FILLER-LOADING SCREENING

Objective: Investigate how a dry, compatible mineral filler affects processing, density, hardness, void formation and mechanical performance while retaining the same nominal curative-to-prepolymer calculation.

Starting components:

MOCA-compatible TDI/polyether prepolymer: 100 parts by mass

Illustrative measured prepolymer NCO content: 5.00% by mass

MOCA curative/NCO equivalent ratio: 0.95, only if approved for the selected system

MOCA (4,4'-Methylene-bis(2-chloroaniline)): approximately 15.10 parts

Dry, supplier-approved barium sulfate filler with verified low moisture and low reactivity toward the system: approximately 0, 10 and 20 parts

Additional curatives, catalysts and plasticizers: omitted during the initial comparison

Filler grade, preparation, incorporation sequence, casting geometry, cure/post-cure and conditioning: held constant

The nominal total mixture masses are respectively 115.10, 125.10 and 135.10 parts. MOCA is calculated from prepolymer NCO equivalents, not from the total mass including filler. Confirm that filler moisture, surface treatment and adsorption do not materially change the effective cure chemistry.

Application approach:

Verify the filler identity, particle distribution, moisture specification and compatibility with both the prepolymer and MOCA cure system.
Prepare the filler as instructed and protect it from moisture uptake.
Incorporate the measured filler quantity into the prepolymer using the approved sequence.
Assess viscosity and dispersion before introducing the curative.
Add the calculated MOCA quantity by contained metering and mix according to the approved procedure.
Cast specimens of identical geometry and record the actual temperature profile, working time and any trapped air.
Complete cure and post-cure, then measure density, hardness, tensile properties, tear resistance and compression behavior.
Inspect filler dispersion, voids, settling and dimensional change.
Compare residual or extractable MOCA and repeat the most balanced filler level.

Filler can change viscosity, heat transfer and sedimentation even when the nominal equivalent ratio is unchanged. Assess the resulting temperature profile and mechanical properties before scaling the formulation. Introducing reactive fillers or additional reactive additives requires a revised equivalent balance.

Maintain containment and extraction during filler charging and MOCA addition, and prevent transfer of contaminated tools or clothing to clean areas. Manage uncured mixtures, cleaning residues and contaminated consumables under the applicable MOCA and isocyanate waste procedures; do not infer waste safety from solidification alone.

SELECTION, SUBSTITUTION AND QUALITY CONTROL

MOCA selection should start with an identified prepolymer and a defined component requirement. A technically successful system needs both a reproducible reaction process and evidence that the cured material meets its intended service demands.
Incoming controls for MOCA can include identity, assay, amine value, water, melting range, color and relevant insoluble matter or residual components. The importance of each parameter depends on the agreed material specification and process sensitivity.
A curative described as a MOCA replacement may have a different chemical composition, equivalent weight and physical state. It should not be assumed to be a mass-for-mass replacement even if its intended applications overlap.
Alternative diamines or other curative technologies can change mixing, temperature requirements, working time and final properties. Their own hazards and regulatory status also require evaluation rather than assuming that an alternative is automatically suitable.

The practical comparison should retain the same required service tests and clearly identify any changes to the formulation basis. Equal mass loading and equal amine equivalents are different comparisons.
For an established industrial process, the reason to retain MOCA may be existing qualification and known system behavior. That is an application-specific rationale, not a claim that MOCA is universally superior to other chain extenders.
Ataman Chemicals can be contacted with the target prepolymer, required MOCA curative specification, intended end use and delivery destination. Any supply discussion should also identify the documentation needed to establish a lawful and controlled use.

HEALTH HAZARDS AND EXPOSURE CONTROL

MOCA is classified as carcinogenic to humans under the international cancer-hazard evaluation framework. This is a central material hazard and should not be diluted by describing the product simply as an ordinary low-volatility curing agent.
MOCA can enter the body through skin absorption, inhalation of airborne material and ingestion. Contaminated gloves, equipment and work surfaces can contribute to exposure even when airborne measurements appear low.
Reported acute hazards include effects on the blood, including methemoglobinemia, which can impair oxygen transport. Possible symptoms include headache, dizziness, nausea and a bluish appearance of the skin or lips; significant exposure requires urgent medical assessment.
An occupational program should address containment, controlled transfer, effective extraction, hygiene and protective equipment together. Low vapor pressure at room temperature does not demonstrate adequate control of either skin exposure or heated operations.
Protective gloves and clothing need selection for the actual chemical contact, temperature and task. A glove suitable for handling dry packaging is not automatically suitable for prolonged chemical contact or molten material.

Respiratory protection requires task-specific selection and a properly managed program. A generic dust mask recommendation would not adequately describe every MOCA handling, heating, maintenance or emergency scenario.
Biological monitoring can help occupational-health professionals assess uptake from multiple exposure routes. It complements other exposure controls and should not be used as a substitute for preventing contamination.
Avoid eating, drinking or smoking in handling areas, and prevent transfer of contamination into clean areas. Contaminated work clothing should be managed through controlled arrangements rather than taken home.
As one jurisdiction-specific reference, the US recommended occupational exposure limit is 0.003 mg/m3 as a time-weighted average with a skin notation. This is not a worldwide legal limit or a guarantee that exposure below that value eliminates cancer risk.

REGULATORY STATUS AND USE REQUIREMENTS

MOCA is included in the EU REACH Authorisation List as entry 27 under the name 2,2'-dichloro-4,4'-methylenedianiline. The listed latest application date was 22 May 2016 and the sunset date was 22 November 2017.
Uses and placing on the market for uses within the scope of the authorisation requirement after the sunset date need an applicable legal basis, such as coverage by a relevant authorisation or an applicable exemption. The actual use, actors in the supply chain and authorisation conditions must be checked.
A REACH registration statement is not equivalent to authorisation for a particular use. Likewise, a supplier's general statement of international availability does not establish that every customer or application is covered.
The EU authorisation listing is associated with carcinogenic classification in category 1B. This terminology and the international Group 1 cancer-hazard classification belong to different assessment frameworks and should not be treated as identical category systems.
Requirements outside the EU must be checked for the relevant jurisdiction and use. No Turkish, UK or other national approval is implied by this product profile.
Regulatory and safety documentation should be reviewed for the actual transaction and processing location. Authorisations can carry specific conditions, review periods and supply-chain obligations that a generic chemical description cannot establish.

FIRST AID MEASURES

MOCA Inhalation: Move the exposed person to fresh air without exposing rescuers and obtain prompt medical advice. Breathing difficulty, bluish skin or lips, collapse or other significant symptoms require emergency medical assistance.

MOCA Skin Contact: Remove contaminated clothing and rinse and wash the skin thoroughly with water and soap. Obtain medical advice promptly after significant contact because absorption can occur through the skin; do not clean the skin with organic solvents.

MOCA Eye Contact: Rinse immediately with plenty of water and remove contact lenses if easily possible. Arrange medical assessment and continue care according to professional advice.

MOCA Ingestion: Rinse the mouth and obtain immediate medical attention. Do not induce vomiting unless directed by medical personnel, and do not give anything by mouth to an unconscious person.

Molten MOCA Contact: Contact can combine chemical exposure with a thermal injury. Obtain urgent medical assistance and follow the site's chemical-exposure and burn-response procedure.

MOCA Medical Information: Provide medical personnel with the chemical identity and current safety data sheet. Treatment of suspected blood effects requires clinical assessment and should not be attempted through workplace self-medication.

HANDLING AND STORAGE

MOCA Handling: Use closed or otherwise effectively controlled transfer wherever practicable. Prevent dust release, splashes, contaminated surfaces and unnecessary manual contact during charging, casting and maintenance.
MOCA Heated Operations: Use equipment with suitable temperature control and extraction, following the approved process. Avoid uncontrolled heating and assess both chemical exposure and thermal hazards.

MOCA Personal Protection: Select protective clothing, eye and face protection, gloves and any respiratory protection from the task-specific exposure assessment and supplied safety documentation. Maintain clean removal and replacement procedures for contaminated equipment.

MOCA Storage: Keep MOCA in tightly closed, labeled containers in a designated dry storage area with controlled access. Protect packaging from damage and prevent contamination of adjacent materials.

MBOCA Compatibility: Segregate from strong oxidizing agents, strong acids and other incompatible substances identified in the current safety data sheet. Reactive metals and other incompatible process chemicals should also be considered in equipment and maintenance planning.

MOCA Environmental Containment: Storage should prevent release to drains and provide suitable containment for spills and contaminated firefighting water. Its low water solubility does not justify uncontrolled discharge.

MOCA Shelf Life and Packaging: Follow the actual supplied grade documentation and agreed storage conditions. No universal package size, storage temperature or shelf life is guaranteed for every commercial grade.

SPILLAGE, FIRE AND DISPOSAL

MOCA Spillage: Isolate the affected area and use trained personnel with suitable protection for recovery. Avoid dust generation, skin contamination and spread into clean areas; place recovered material in compatible closed waste containers.

MOCA Cleaning: Use a documented decontamination procedure suited to the equipment and contamination. Do not use compressed air or uncontrolled dry sweeping to disperse residues, and do not wash contamination into drains.

MOCA Fire: The substance is combustible, and decomposition can generate toxic and corrosive fumes. Emergency responders need appropriate respiratory and chemical protection, and the extinguishing method should follow the supplied safety data and site plan.

MOCA Contaminated Water: Collect spill-cleaning liquids and firefighting runoff for controlled management. Prevent environmental release because the substance presents serious aquatic hazards.

MOCA Waste: Manage unused chemical, contaminated packaging, protective equipment and residues under applicable hazardous-waste requirements. A cured-looking waste mass should not automatically be assumed free from unreacted MOCA or suitable for ordinary disposal.

FREQUENTLY ASKED QUESTIONS

What is MOCA?
MOCA is 4,4'-methylene-bis(2-chloroaniline), a chlorinated aromatic diamine used mainly as a curative for suitable polyurethane prepolymers.

Are MOCA and MBOCA the same chemical?
Yes, these abbreviations refer to the same principal substance, CAS 101-14-4. Modified products or liquid substitutes still require their own composition check.

Is MOCA a catalyst?
No. MOCA reacts with isocyanate functionality and becomes incorporated into the cured polymer, so its amount and reaction balance matter.

What polymer linkages does MOCA form during polyurethane cure?
The primary amino groups of MOCA react with suitable isocyanate groups to form substituted urea linkages. A urethane-containing prepolymer can therefore produce a material containing both urethane and urea structures.

What equivalent weight is used for MOCA in conventional polyurethane calculations?
Approximately 133.6 g/equivalent on the usual two-amino-group chain-extension basis. The convention and actual commercial composition must be confirmed for the system.

Why should the four nitrogen-bound hydrogens of MOCA not simply be counted as four identical curing equivalents?
The conventional polyurethane chain-extension calculation treats each primary amino group as initially consuming one isocyanate group to form urea. Using a different active-hydrogen convention without checking the reaction basis can give an incorrect dosage.

Is there one MOCA mixing ratio for every prepolymer?
No. The ratio depends on the NCO content, curative equivalence, composition and selected stoichiometry of the validated system.

What are the main applications of MOCA?
Established applications include cast polyurethane wheels, rollers, belts, bushings, seals and shock-absorption components. Performance belongs to the complete cured formulation.

Does MOCA determine the finished elastomer hardness by itself?
No. Prepolymer chemistry, component ratio, processing, cure and conditioning all contribute to the final properties.

What is the melting point of MOCA?
Chemical references commonly report about 110 degrees Celsius, while a published commercial pellet grade specifies 98-102 degrees Celsius. Use the actual grade specification and method for acceptance.

Can a room-temperature vapor-pressure value establish safe handling of MOCA?
No. Skin absorption, dust, contaminated surfaces and heated operations can remain important exposure routes despite low room-temperature volatility.

Is MOCA carcinogenic?
Yes. It is classified as carcinogenic to humans under the international cancer-hazard framework and requires stringent occupational exposure control.

Is MOCA freely usable throughout the EU?
No. MOCA is on the REACH Authorisation List, and uses within scope after the sunset date need an applicable legal basis and compliance with relevant conditions.

Does a REACH registration prove that my use is authorised?
No. Registration and authorisation are different requirements, and coverage must be checked for the actual use and supply chain.

Can an alternative curative replace it at the same mass loading?
Not automatically. An alternative may differ in equivalent weight, physical state, reactivity, processing requirements and the properties of the resulting polymer.

What information should accompany a commercial enquiry about MOCA?
Provide the prepolymer type and NCO specification, application, required MOCA grade characteristics, quantity and destination, together with relevant regulatory and supply-chain requirements.

TECHNICAL SUMMARY

MOCA, or 4,4'-methylene-bis(2-chloroaniline), is a chlorinated aromatic diamine used principally to cure suitable isocyanate-terminated polyurethane prepolymers. The abbreviations MOCA and MBOCA identify the same principal substance, CAS 101-14-4. Its molecule contains two aromatic rings joined by a methylene bridge, two primary amino groups and two chlorine substituents. The formula is C13H12Cl2N2, and the molecular weight is approximately 267.15 g/mol.
During conventional amine curing, the amino groups react with isocyanate groups to introduce urea linkages and extend prepolymer chains. MOCA is therefore a reactive formulation component rather than a catalyst. The usual polyurethane amine-equivalent convention gives approximately 133.6 g/equivalent, based on two amino groups per molecule. Counting every nitrogen-bound hydrogen as an identical initial chain-extension equivalent would use a different reaction basis and can lead to an incorrect curative calculation.

The required amount of MOCA depends on the prepolymer NCO content, actual curative composition and selected stoichiometry. Processing must also address uniform incorporation, moisture and temperature control. Water can consume isocyanate functionality and generate carbon dioxide, while incomplete mixing can create local variations in cure. Working time, mold temperature and post-cure requirements are properties of the specific formulation and process, rather than constants that can be assigned to the MOCA name.
Established applications of MOCA include cast polyurethane wheels, industrial tires, rollers, belts, bushings, seals and shock-absorption components. Suitable prepolymer systems include documented polyether, polyester and polycaprolactone-based products. Their finished properties depend on the complete polymer architecture, formulation and cure. Hardness, abrasion resistance, tensile behavior, compression response and environmental resistance should therefore be evaluated in the actual elastomer rather than described as intrinsic numerical properties of the uncured diamine.

MOCA is solid at room temperature. Reference descriptions give a melting point near 110 degrees Celsius and solid density around 1.44 g/cm3, while a published commercial pellet grade uses a lower melting interval. These data should remain tied to their source conditions and grade definitions. Ordinary atmospheric boiling is not a useful processing reference because thermal decomposition is relevant first. A molten viscosity or density requires its own temperature-dependent measurement. Commercial qualification should also distinguish assay, amine value, water content, color and insoluble matter. A modified or alternative curative may differ in composition and equivalent weight even when promoted for similar applications. Substitution therefore requires a documented comparison of processing behavior and finished performance, together with an assessment of the alternative material itself.

Health and regulatory considerations are central to material selection. MOCA is classified as carcinogenic to humans, can be absorbed through the skin and can affect the blood. Low room-temperature volatility does not remove risks from dust, contaminated equipment or heated operations. Effective containment, controlled transfer, suitable protection, hygiene and occupational-health arrangements need to address the complete exposure scenario. Its aquatic hazards also require prevention of uncontrolled environmental release.
MOCA appears in the EU REACH Authorisation List, and uses within scope need the applicable legal basis after the sunset date. Registration alone does not establish authorisation coverage. A sound Ataman Chemicals enquiry should therefore combine the intended prepolymer and application with grade requirements, performance criteria and destination-specific use conditions. This connects purchasing to a technically qualified process and the actual requirements for lawful, controlled industrial use.

COMMERCIAL ENQUIRIES

Contact Ataman Chemicals with the intended application, prepolymer details, required grade parameters, quantity and delivery destination. Where an existing material is being replaced, include its specification and the relevant processing and finished-product requirements.
Ask about the technical, safety and batch-quality documentation available for the proposed grade and the applicable supply conditions. Availability, packaging and any authorisation-related supply-chain coverage must be confirmed for the particular enquiry.
Ataman Chemicals
Phone: +90 216 577 10 10
Email: info@atamankimya.com