DIMER ACID

Dimer Acid, also known as dimer fatty acid or dimerized fatty acids, is a predominantly C36 carboxylic acid material identified under CAS 61788-89-4 and used to manufacture polyamide resins, adhesives, polyesters and lubricant derivatives. Its long hydrocarbon segments are selected to introduce flexibility, hydrophobic character and compatibility benefits into suitable resin systems. The carboxyl groups react with amines or alcohols to build amide or ester linkages, while the commercial product's monomer, dimer and higher-oligomer distribution influences the resulting polymer architecture.

CAS No: 61788-89-4
EC No: 500-148-0
Chemical identity: fatty acids, C18-unsaturated, dimers
Appearance: viscous liquid, generally yellow to amber in conventional grades
Main carbon fraction: predominantly C36 dimer-derived structures
Acid value: a representative conventional grade specifies 190-196 mg KOH/g
Water behavior: very low water solubility
Commercial forms: conventional, distilled high-dimer and hydrogenated grades

WHAT IS DIMER ACID?

Dimer Acid is a fatty-acid-derived reactive building block used principally in polyamide resins, hot-melt adhesives, polyester resins and specialty industrial derivatives. Dimer fatty acid, CAS 61788-89-4, usually contains a major dimer fraction together with smaller amounts of residual monomer acids and higher oligomers.

Commercial material is a substance of variable composition, commonly described as a UVCB. It is not adequately represented by one unique molecular formula, molecular weight or structural drawing. The C36 designation describes the main fraction formed from C18 fatty-acid feedstocks, rather than guaranteeing a chemically pure C36 molecule.

Production involves catalytic dimerization of unsaturated fatty acids, often obtained from tall oil or other oil-derived feedstocks. Separation and distillation adjust the proportions of monomer, dimer and higher components. Hydrogenation can reduce residual unsaturation and improve color and oxidative stability in suitable grades.

Standard products retain a broader functionality distribution, while high-dimer grades provide a greater proportion of difunctional material. These differences matter when molecular weight, branching and gel formation must be controlled. High dimer content and hydrogenation describe different quality features and should not be treated as synonyms.

A dimer acid is not a dimer diol, dimer diamine or finished polyamide hardener. Those materials have different functional groups or have already undergone further chemical conversion. Likewise, a finished ester lubricant derived from the acid is different from the free acid supplied as a resin raw material.

COMMON PRODUCT & CHEMICAL NAMES OF DIMER ACID:

Dimer acid
Dimer fatty acid
Dimerized fatty acids
C36 dimer acid
Fatty acids, C18-unsaturated, dimers
Fatty acids, C18-unsatd., dimers

Commercial families include UNIDYME, Pripol and FloraDyme. Each family contains specific grades, so the trade name alone does not establish dimer content, hydrogenation status or regulatory coverage.

The term C36 dimer acid describes the dominant carbon fraction. Monobasic acid and trimer acid are not interchangeable synonyms, because they describe different functionalities or fractions. Hydrogenated derivatives also require confirmation of their own product identity rather than automatic assignment of the identifier used here.

CAS NO, EC NO AND CHEMICAL IDENTIFICATION OF DIMER ACID

Product name: Dimer Acid
Chemical identity: fatty acids, C18-unsatd., dimers
CAS No: 61788-89-4
EC No: 500-148-0
Substance type: UVCB, variable-composition fatty-acid reaction product
Main chemical class: long-chain dicarboxylic acid material with grade-dependent oligomer fractions
Main functions: reactive resin building block and precursor for amides, esters and other industrial derivatives

EC 500-148-0 is recorded in the former No-Longer Polymer inventory. It should not be described indiscriminately as an EINECS entry. A commercial product can be reported as 100% of this substance identity in its safety documentation while still containing less than 100% dimer fraction.

REACH registration information is available for the identified substance. Registration does not approve every application or establish that every supplier's material has the same composition. Confirm the offered grade and applicable supply-chain documentation with Ataman Kimya.

CHEMICAL STRUCTURE AND MOLECULAR PROPERTIES OF DIMER ACID

The main dimer fraction contains two carboxylic acid groups attached to a large hydrocarbon framework. The industrial product contains different structures and degrees of residual unsaturation. A single cyclic model should not be presented as the complete composition of every grade.

Long hydrocarbon segments contribute hydrophobic character and can act as flexible segments after incorporation into a resin. Carboxyl groups provide reaction sites for polycondensation. Monomeric fatty acids can terminate chains, whereas higher-functional oligomers can promote branching and, under unsuitable conditions, gel formation.

An acid value measures titratable acidity per gram, not the percentage of dimer molecules. Two grades can have similar acid values but different monomer/dimer/trimer distributions. For reaction calculations, the measured acid value is more useful than assuming a universal molecular weight for the entire product.

HOW DOES DIMER ACID WORK AT THE MOLECULAR LEVEL?

Reaction with suitable diamines produces polyamides containing long fatty segments. The balance of reactive groups, conversion and feedstock functionality determines molecular weight and end groups. Flexible hydrocarbon sections can help reduce brittleness in an appropriately designed resin.

Reaction with diols creates polyester structures, while conversion with polyamines can produce amine-functional materials used in epoxy-curing systems. The free acid is the precursor, not a ready-to-use amine hardener. A polyamide hot-melt adhesive and a reactive polyamide epoxy hardener perform different roles even when both originate from dimer fatty acid.

Relevant contributions include:

Introducing flexible hydrocarbon segments into polymers
Providing carboxyl groups for amide and ester formation
Adjusting hydrophobic character and moisture response
Influencing adhesion, wetting and resin compatibility
Controlling branching through the selected functionality distribution

These effects depend on the complete resin design. Dimer acid does not independently guarantee water resistance, corrosion protection, a particular softening point or an adhesive strength.

PHYSICAL AND CHEMICAL PROPERTIES OF DIMER ACID

A representative conventional commercial grade has the following specification and typical composition:

Acid value: 190-196 mg KOH/g, typical approximately 192
Color: maximum 8 Gardner, typical approximately 7
Monomer acids by GC: 1.0-3.0%, typical approximately 2%
Dimer acids by GC: 78-84%, typical approximately 81%
Polymer acids by GC: 15-19%, typical approximately 17%
Moisture: maximum 0.25%, typical approximately 0.1%
Iron: maximum 2 ppm, typical below 1 ppm

These figures describe one grade and do not define all products sold as Dimer Acid. The typical fractions total 100%, but the separate upper and lower specification limits are not a single composition that should be added together.

Another conventional commercial product specifies a viscosity of 7500-8500 cP at 25°C and an acid value of 190-200 mg KOH/g. The measurement temperature is essential, and dynamic viscosity in cP or mPa·s should not be confused with kinematic viscosity in mm²/s.

High-dimer products can reach approximately 98-99% dimer fraction in selected grades. This percentage refers to the compositional fraction, rather than a universal analytical purity for all products. Hydrogenated grades can be substantially lighter in color than conventional grades, but the color scale and specification must be identified.

Color, acid value, water, residual monomer and higher-oligomer content should be interpreted together. A light color does not prove low trimer content, and an acid value near 195 mg KOH/g does not establish a 95% dimer fraction.

No universal boiling point, freezing point, flash point or molecular weight is assigned here. Exact values depend on grade and test basis, and estimated values from a representative structure should not be presented as measured properties of the commercial material.

FUNCTIONALITY AND EQUIVALENT BALANCE OF DIMER ACID

For an acid value AV expressed in mg KOH/g, the approximate acid equivalent weight is 56100 / AV in g per equivalent. At AV 196, this gives approximately 286.22 g per carboxyl equivalent. This is an equivalent weight derived from titration, not a molecular weight determination.

In a polymerization feed, the ratio of carboxyl equivalents to amino or hydroxyl equivalents is more meaningful than an equal-mass ratio. Raw-material assay, moisture, monofunctional species and higher-functional components must also be considered. Near-equivalent balance alone does not guarantee high molecular weight or prevent gelation.

SECTORS AND INDUSTRIAL APPLICATIONS OF DIMER ACID

Main areas of use:

Polyamide resins for printing inks and coatings
Polyamide hot-melt adhesives
Reactive polyamide materials for epoxy systems
Polyester and polymer modification
Synthetic lubricant derivatives
Oilfield and corrosion-inhibitor chemistry

DIMER ACID IN POLYAMIDE INKS AND ADHESIVES

Purpose: provide a long-chain acid building block for resin synthesis.
Function: reacts with the selected amine components to form polyamide linkages.
Performance contribution: supports flexibility, adhesion and compatibility in a suitable resin design.
Limitations: final solubility, softening point, viscosity and bond performance depend on the full reaction composition.

DIMER ACID IN EPOXY-CURING MATERIALS

Purpose: serve as a precursor to amine-functional polyamide curing agents.
Function: reacts with selected polyamines during hardener manufacture.
Performance contribution: helps introduce flexible, hydrophobic segments into the resulting curing material.
Limitations: the finished hardener requires its own amine value, active-hydrogen equivalent weight and epoxy mixing ratio.

DIMER ACID IN POLYESTERS AND LUBRICANT DERIVATIVES

Purpose: provide a reactive acid component for esterification.
Function: forms ester bonds with suitable alcohols or polyols.
Performance contribution: introduces long-chain segments into polyester or lubricant structures.
Limitations: properties of the ester cannot be assigned directly to the unreacted acid, and the finished product requires separate testing.

DIMER ACID IN FOOD-CONTACT RESIN APPLICATIONS

Certain specifically documented grades are offered for food-contact resin applications. Such status depends on the grade, jurisdiction, permitted use and finished article, rather than the generic product name. It does not make industrial dimer acid a food additive or an ingredient for direct consumption.

For packaging adhesives or coatings, obtain a statement covering the exact supplied product and intended conditions from Ataman Kimya. A general listing, a CAS number or approval of another grade does not establish finished-article compliance.

WHICH PROBLEMS CAN DIMER ACID HELP SOLVE?

Brittleness in a resin: suitable incorporation of long fatty segments can improve flexibility, with the hardness and strength balance checked in the finished polymer.

An unsuitable hydrophobicity balance: fatty-acid-derived segments can adjust the resin's moisture response, although formulation and cure remain important.

Insufficient control of molecular architecture: selecting a higher-dimer grade can reduce unwanted monofunctional and higher-functional fractions compared with a broader grade.

Color-sensitive polymer applications: a suitable hydrogenated, low-color product can be evaluated without assuming all dimer acids have the same appearance or color stability.

THINGS TO CONSIDER WHEN USING DIMER ACID

The most consequential mistake is choosing a reaction ratio from an assumed fixed molecular weight while ignoring the measured acid value and functionality distribution.

Specify dimer, monomer and higher-oligomer fractions.
Distinguish dimer enrichment from hydrogenation.
Use the actual batch acid value in equivalent calculations.
Control moisture and contamination before reaction.
Account for chain termination and branching effects.
Separate properties of the raw acid from those of its derivatives.
Evaluate the finished resin rather than relying on the feedstock's appearance.

Viscous material may require controlled warming for transfer, but heating conditions must be selected for the offered grade and equipment. Avoid overheating and do not assume that a statement about thermal stability is a permission to hold every product at 250°C in air.

INITIAL FORMULATION APPROACHES FOR DIMER ACID

The following are calculated starting feed compositions for laboratory resin development, not validated commercial recipes or operating instructions. All percentages are weight percentages of the initial raw-material charge before reaction water is removed. Both calculations assume a high-dimer acid with measured AV 196 mg KOH/g and dry co-reactants at 100% assay, so actual grades require recalculation.

EXAMPLE 1: DIMER ACID AND ETHYLENEDIAMINE POLYAMIDE FEED

Components:

Dimer Acid, assumed AV 196 mg KOH/g: 90.50%
Anhydrous ethylenediamine, assumed 100% assay: 9.50%
Total: 100.00%

The calculated acid equivalent weight is approximately 286.22 g/eq. Using ethylenediamine molecular weight 60.10 g/mol and two primary amino groups gives approximately 30.05 g per amino-group equivalent for amidation. The rounded feed is close to one amino-group equivalent per carboxyl equivalent, not a proven production optimum.

Evaluation criteria:

Actual acid and amine equivalent balance
Residual acid and amine values
Resin viscosity and molecular-weight development
Gel fraction, flexibility and application-specific adhesion
Residual free amine and volatile removal

This calculation does not describe an epoxy-hardener mixing ratio, where active amine hydrogens are counted on a different basis. Amine handling, reaction heat and condensate removal require a separately assessed process.

EXAMPLE 2: DIMER ACID AND 1,6-HEXANEDIOL POLYESTER FEED

Components:

Dimer Acid, assumed AV 196 mg KOH/g: 82.89%
1,6-Hexanediol, assumed 100% assay: 17.11%
Total: 100.00%

With a molecular weight of approximately 118.17 g/mol and two hydroxyl groups, the diol has an approximate hydroxyl equivalent weight of 59.085 g/eq. The rounded feed is near equal carboxyl and hydroxyl equivalents. It does not specifically target a hydroxyl-terminated polyester polyol, which would require a deliberately selected excess and a defined end-group specification.

Evaluation criteria:

Residual acid and hydroxyl values
Viscosity, molecular weight and branching
Color development and phase homogeneity
Hydrolytic behavior of the resulting polyester
Water removal and final mass balance

Condensation changes the final mass, so these initial charge percentages are not final polymer composition percentages. Catalyst choice, any chain stopper, reaction conditions and target conversion are outside these screening examples and must be developed separately.

DIMER ACID SIMILAR PRODUCTS AND ALTERNATIVES

Choose an alternative by reactive functionality and the intended resin properties, rather than appearance alone. Equivalent balance and processing generally need adjustment when the acid component changes.

DIMER ACID AND TRIMER-RICH FATTY ACIDS

A trimer-rich fraction introduces more higher-functional material and can increase branching. It is not a direct substitute for a high-dimer feed when linear chain growth is the priority.

DIMER ACID AND ADIPIC OR SEBACIC ACID

These defined diacids have shorter and more regular structures than the long-chain commercial dimer material. They provide alternative polymer building blocks, but can change crystallinity, flexibility and processing behavior.

DIMER ACID AND DIMER DIOL

A dimer diol supplies hydroxyl groups rather than carboxyl groups. It belongs on a different side of an esterification equivalent balance and cannot be substituted as though its functionality were unchanged.

DIMER ACID AND HYDROGENATED DIMER ACID

Hydrogenation reduces unsaturation and can improve color and oxidative stability in a suitable product. Confirm its own identity, dimer fraction and specification, because hydrogenation does not automatically remove monomer or trimer fractions.

QUALITY CONTROL AND PURCHASING CRITERIA FOR DIMER ACID

First define whether the target is a thermoplastic polyamide, a reactive hardener, a polyester or a lubricant derivative. The optimum grade can differ substantially among these uses.

Information to review before purchasing:

Chemical identity and hydrogenation status
Acid value and test method
Dimer, monomer and higher-oligomer distribution
Composition measurement method and reporting basis
Viscosity and measurement temperature
Color scale, moisture and metal contamination limits
Batch COA, technical specification and current SDS
Application-specific food-contact statements where relevant
Bio-based content evidence if required
Packaging, traceability and delivery requirements

The COA describes a batch, the TDS summarizes technical characteristics and the SDS describes hazards and handling. A COA dimer percentage is not interchangeable with the total substance concentration shown in an SDS. For missing grade-specific limits or regulatory coverage, please contact Ataman Kimya.

Pricing depends on purification, hydrogenation, color requirements, packaging and order size. Comparing conventional and high-dimer material by price alone can overlook a significant difference in reactive functionality.

STORAGE AND HANDLING OF DIMER ACID

Store in closed, identified containers protected from contamination, moisture and excessive heat. Separate from strong oxidizing agents and use clean transfer equipment. Obtain the grade-specific storage temperature, approved warming method and shelf life from Ataman Kimya.

Collect spills and prevent entry into drains or waterways. Supplier safety documentation warns that porous materials wetted with some dimer fatty acid products can self-heat and ignite. Handle contaminated rags, paper and absorbents through a controlled collection and disposal procedure, and do not leave them piled together.

Reviewed supplier documentation describes the identified grade as not regulated as dangerous goods under road, rail, sea and air transport provisions. No UN number is assigned to that grade. Confirm the current classification for the offered material, and assess heated transport separately if relevant.

SAFETY INFORMATION OF DIMER ACID

A reviewed European supplier SDS does not classify the specified grade as hazardous under CLP and does not assign hazard pictograms or H statements. This does not mean that every grade or derivative is harmless, and the current safety information for the supplied product remains decisive.

Use eye protection and suitable chemical-resistant gloves, and provide ventilation where mist or heated emissions can occur. Heated viscous liquid can cause thermal burns. After skin contact wash with soap and water, and after eye contact rinse with clean water. Seek medical attention for persistent symptoms or significant exposure.

Fire can produce carbon oxides and other irritating decomposition products. Self-heating of wetted porous materials is a separate hazard from the bulk liquid's flash point. Prevent environmental release and dispose of residues according to the applicable local requirements.

SUPPLY OF DIMER ACID FROM ATAMAN KIMYA

ATAMAN KİMYA can be contacted for Dimer Acid supply and selection of a suitable industrial grade. Dimer content, hydrogenation status, packaging and required documents should be confirmed for the offered product.

A quotation request is easier to evaluate when it includes:

Intended resin or derivative
Required acid value and dimer fraction
Acceptable monomer and higher-oligomer limits
Color, viscosity and moisture requirements
Regulatory or bio-based-content documentation needs
Trial quantity, commercial quantity and delivery destination

FREQUENTLY ASKED QUESTIONS ABOUT DIMER ACID

What is Dimer Acid?
It is a long-chain fatty-acid-derived reactive material used to manufacture polyamides, polyesters, adhesives and industrial derivatives.

What is its CAS number?
The identity discussed here has CAS number 61788-89-4.

What is its EC number?
The EC number is 500-148-0.

Does it have one fixed molecular formula?
No, the commercial UVCB contains a distribution of structures and fractions, so one formula does not define every grade.

Why is it called C36 dimer acid?
The main fraction is typically formed by combining two C18 fatty-acid units.

Does 100% substance concentration mean 100% dimer content?
No, the substance identity can include monomer and higher-oligomer fractions within the commercial composition.

How is high-dimer material different?
It contains a larger dimer fraction, which can help control functionality and polymer architecture.

Is hydrogenation the same as purification?
No, hydrogenation reduces unsaturation, while fractionation and purification adjust composition.

What does acid value show?
It measures titratable acidity per gram and provides a basis for calculating acid equivalents.

Is acid value the same as dimer percentage?
No, these describe different properties and both can be important for resin synthesis.

Is Dimer Acid soluble in water?
It has very low water solubility and is not supplied as a freely water-soluble acid.

Can it be used to make hot-melt polyamides?
Yes, it is an established acid building block for suitable polyamide adhesive resins.

Is the raw acid a ready-to-use epoxy hardener?
No, amine-functional curing materials require further reaction and their own specification.

Can it be used to make polyesters?
Yes, its carboxyl groups react with appropriate alcohols or polyols to form ester linkages.

Why do monomer and trimer fractions matter?
Monofunctional species can limit chain growth, while higher-functional species can promote branching and gelation.

Is there a universal use percentage?
No, the amount depends on equivalent balance, feedstock functionality and the target resin or derivative.

Is every grade approved for food contact?
No, the exact grade, intended use and jurisdiction need supporting documentation.

What handling issue deserves particular attention?
Some supplier documents warn of self-heating and ignition of porous materials wetted with the product, alongside the usual hot-liquid and spill hazards.

DIMER ACID - TECHNICAL SUMMARY

Dimer Acid, or dimer fatty acid, is a variable-composition material predominantly containing long-chain C36 dimer-derived acids. Its carboxyl functionality and hydrocarbon framework make it a useful industrial resin building block.

CAS 61788-89-4 and EC 500-148-0 identify the substance discussed here. A universal molecular formula or molecular weight is inappropriate for the complete commercial UVCB, and hydrogenated derivatives require their own identity confirmation.

Conventional, high-dimer and hydrogenated products differ in functionality distribution, color and residual unsaturation. Dimer percentage, acid value, viscosity, moisture and higher-oligomer content should be assessed together.

Applications include ink polyamides, hot-melt adhesives, precursors to reactive epoxy-curing materials, polyesters and lubricant derivatives. Formulation requires equivalent calculations and verification of the finished resin, rather than assuming that one acid grade suits every application.

Safety, transport and food-contact status are product-specific. Particular attention should be paid to heated handling, environmental containment and the self-heating potential of contaminated porous materials where identified by the supplier.

Dimer Acid can be sourced from ATAMAN KİMYA. For further information and supply inquiries about Dimer Acid, please contact ATAMAN KİMYA.