What Is Tributyl Citrate (TBC)?

Tributyl citrate, abbreviated as TBC, is a citrate ester plasticizer identified by CAS number 77-94-1. It is also known as tri-n-butyl citrate, citric acid tributyl ester and tributyl 2-hydroxypropane-1,2,3-tricarboxylate.

TBC is normally supplied as a clear, colorless to pale-yellow oily liquid. Its principal commercial function is to improve the flexibility, processing behavior and film-forming performance of compatible polymer systems.

Unlike conventional ortho-phthalate plasticizers, TBC does not contain a phthalate structure. However, describing a product as non-phthalate does not by itself establish compliance with food-contact, pharmaceutical, medical-device, toy or cosmetic regulations. These applications require the correct product grade and supporting documentation.

AOZUN supplies tributyl citrate for industrial evaluation in plastics, coatings, inks, cellulose derivatives and other compatible formulations.

Tributyl Citrate Quick Facts

Is TBC the Same as ATBC?

No. Tributyl citrate and acetyl tributyl citrate are two different chemical substances.

TBC retains a free hydroxyl group on the citrate structure. ATBC is produced by acetylating that hydroxyl group, increasing its molecular weight and changing its polarity, extraction behavior, polymer compatibility and regulatory profile.

A formulation approved with ATBC must not automatically be changed to TBC. The finished product should be re-evaluated for compatibility, migration, mechanical properties and regulatory compliance.

Typical Tributyl Citrate Specifications

The following table reflects AOZUN’s current published product targets. Confirm the latest sales specification and batch COA before purchasing.

Additional typical physical properties may include:

Physical-property values are identification and formulation references unless they are expressly included as batch-release limits in the agreed specification.

What Do the Main TBC Specifications Mean?

Assay or Ester Content

Assay is normally measured by gas chromatography. A result of at least 99% indicates the relative amount of the principal TBC component, but it does not describe every impurity that may affect a sensitive formulation.

For critical applications, buyers may also need limits for residual butanol, partial citrate esters, free citric acid or other process-related components.

Acid Value

Acid value measures acidic components and is usually reported in milligrams of potassium hydroxide required to neutralize one gram of sample.

Elevated acid value may affect heat stability, color, odor, polymer degradation or equipment corrosion. The acceptable limit depends on the resin, stabilizer package and processing conditions.

“Acid value in mg KOH/g” and “acidity calculated as citric acid percentage” are different reporting methods. Results using these two methods should not be compared without conversion and test-method confirmation.

Water Content

Water can influence hydrolytic stability, coating clarity, emulsion behavior, electrical properties and storage stability. Low water content is particularly important in moisture-sensitive resins and reactive formulations.

Karl Fischer testing is generally more informative than a nonspecific loss-on-drying result for low-moisture liquid plasticizers.

APHA Color

APHA or Hazen color is important in transparent, white or lightly colored finished products. A low value reduces the contribution of the plasticizer to initial product color.

Color stability after heating must still be evaluated in the complete formulation.

Density and Refractive Index

Density and refractive index are useful identity and consistency checks. They can reveal major contamination or formulation errors, but they do not replace chromatographic assay.

How Does Tributyl Citrate Work as a Plasticizer?

TBC molecules position themselves between compatible polymer chains. This increases molecular mobility and free volume, helping reduce stiffness and improve flexibility, fusion and film formation without becoming a permanent covalently bonded part of the polymer.

Why Formulation Results Vary

Plasticizer performance depends on more than the chemical name. Important variables include:

• Polymer polarity and molecular weight

• Resin morphology and crystallinity

• TBC concentration

• Stabilizers, fillers and pigments

• Processing temperature and residence time

• Humidity and water content

• Required extraction and migration resistance

• Finished-product thickness

• Storage and service temperature

A plasticizer that works well in one PVC, cellulose or biopolymer formulation may produce haze, surface exudation or inadequate flexibility in another.

What Are the Main Benefits of TBC?

When it is compatible with the selected polymer, tributyl citrate can offer:

• Effective plasticization

• Improved flexibility

• Faster fusion or film formation in selected systems

• Good transparency in properly matched formulations

• Low volatility relative to many lower-molecular-weight plasticizers

• Low-temperature flexibility

• Compatibility with several cellulose and vinyl resins

• A chemically non-phthalate structure

• Utility in coatings, inks and specialty polymer systems

These are formulation-dependent performance characteristics rather than guaranteed properties of every finished product.

Tributyl Citrate Applications

Flexible PVC and Vinyl Formulations

TBC may be evaluated as a primary or blended plasticizer in compatible flexible PVC and vinyl systems. Potential applications include flexible sheets, flooring compounds, artificial leather, coated textiles and selected technical films.

The formulator should test:

• Fusion behavior

• Shore hardness

• Tensile strength and elongation

• Low-temperature flexibility

• Heat aging

• Volatility

• Extraction resistance

• Migration and surface exudation

• Color stability

TBC should not be substituted for another plasticizer on a one-to-one weight basis without a formulation study.

Cellulose Acetate and Cellulose Derivatives

TBC is used as a plasticizer and film-forming aid for compatible cellulose derivatives, including cellulose acetate and selected nitrocellulose systems.

In these formulations it can affect:

• Film flexibility

• Drying behavior

• Adhesion

• Gloss

• Crack resistance

• Solvent release

• Blocking

• Long-term plasticizer retention

Compatibility with the complete solvent and resin package must be confirmed before scale-up.

Coatings, Lacquers and Printing Inks

TBC can be evaluated in solvent-borne coatings, lacquers, printing inks and specialty film-forming systems. It may improve flexibility and reduce brittleness in compatible binders.

Because TBC has limited water solubility, its use in water-based coatings normally requires appropriate emulsification, dispersion or binder compatibility. Adding it directly to water does not create a stable water-based formulation.

PLA and Other Biopolymer Systems

TBC has been studied and commercially used as a plasticizer for PLA and selected bio-based or biodegradable polymer systems.

Plasticization may reduce stiffness and improve elongation, but it can also affect crystallization, thermal transitions, dimensional stability, migration and aging. The optimal concentration must be established experimentally.

The use of TBC does not automatically make the final plastic biodegradable, compostable or bio-based. Those claims require testing of the finished material against the applicable standard.

Adhesives and Sealants

TBC may be used to adjust flexibility, viscosity or film formation in compatible adhesive and sealant formulations.

Testing should include:

• Initial adhesion

• Cohesive strength

• Open time

• Cure behavior

• Plasticizer migration

• Substrate staining

• Heat and humidity aging

• Package stability

Rubber and Elastomer Formulations

TBC can be screened as a softener or processing aid in selected rubber and elastomer systems. Compatibility varies substantially between elastomer types, so laboratory compounding and aging tests are required.

Cosmetic, Pharmaceutical and Other Regulated Applications

Certain grades of TBC may be evaluated for cosmetic or pharmaceutical formulations, but industrial-grade TBC must not automatically be presented as cosmetic, pharmaceutical, food-contact or medical grade.

The buyer must confirm:

• Applicable monograph or regulation

• Required purity and impurity profile

• Residual solvent limits

• Trace metals

• Microbiological requirements where relevant

• Extractables and leachables

• Supplier declarations

• Intended dosage and route of exposure

CAS number and 99% assay alone do not establish regulatory suitability.

Which Polymers Are Compatible with TBC?

The following table is a screening guide rather than a universal compatibility guarantee.

A clear initial mixture is not proof of long-term compatibility. Aging, extraction and migration testing are necessary.

TBC vs ATBC vs TEC

The best choice depends on polymer compatibility, processing conditions, migration requirements, volatility, extraction resistance, regulatory documentation and total formulation cost.

Is TBC a Phthalate-Free Plasticizer?

TBC is chemically a citrate ester and does not have a phthalate structure. It can therefore be described as a non-phthalate plasticizer.

However, a “phthalate-free” claim for a commercial batch or finished product may require:

• Defined restricted-phthalate limits

• Analytical testing

• Controlled production and storage equipment

• Raw-material traceability

• Prevention of cross-contamination

• Finished-product verification

Chemical identity alone does not prove that trace phthalates are absent below a customer’s required limit.

Is TBC Bio-Based or Biodegradable?

TBC can be produced using citric acid and n-butanol, but the origin of those raw materials varies.

A renewable or bio-based percentage should only be stated when the supplier has suitable feedstock documentation or a recognized analytical result such as radiocarbon-based testing. Citric-acid origin alone does not establish the renewable carbon percentage of the finished TBC.

Biodegradability is a separate property. A claim such as “readily biodegradable” should identify the test method, product tested and result. It must not be used as proof that a finished plastic containing TBC will biodegrade or compost.

How Should TBC Be Added to a Formulation?

A practical laboratory evaluation can follow these steps:

1. Confirm that all raw materials are within their release specifications.

2. Establish a control formulation using the current plasticizer.

3. Prepare a TBC concentration ladder rather than testing only one loading.

4. Add TBC under controlled agitation at a temperature suitable for the resin.

5. Avoid excessive local concentration before uniform mixing is achieved.

6. Record mixing time, temperature, torque, viscosity and appearance.

7. Process specimens using identical conditions.

8. Condition test samples before mechanical evaluation.

9. Perform accelerated aging, migration and extraction testing.

10. Recheck performance after the intended storage period.

For reactive systems, confirm that TBC’s hydroxyl functionality and residual acidity will not interfere with curing or catalyst activity.

Recommended Finished-Product Tests

Depending on the application, evaluate:

• Tensile strength and elongation

• Shore hardness

• Glass-transition temperature

• Low-temperature bending

• Heat aging

• Oven weight loss

• Volatility or fogging

• Water, oil, detergent and solvent extraction

• Plasticizer migration

• Surface tack or exudation

• Transparency and haze

• Initial and aged color

• Odor

• Adhesion

• Blocking

• Electrical properties

• Finished-product regulatory migration

A batch COA confirms raw-material conformity; it does not replace testing of the final formulation.

How Should Buyers Evaluate TBC Quality?

Verify Chemical Identity

The quotation, label, COA, SDS and TDS should consistently show:

• Tributyl citrate

• TBC

• CAS 77-94-1

• EC 201-071-2

• Formula C18H32O7

Reject documentation that substitutes ATBC, CAS 77-90-7.

Confirm the Acidity Method

Ask whether acidity is reported as:

• Acid value in mg KOH/g

• Free acidity as citric acid percentage

• Another titration method

The specification and COA must use the same method.

Review More Than Purity

A strong procurement specification can include:

• GC assay

• Color

• Water

• Acid value

• Density

• Refractive index

• Residual n-butanol

• Partial ester profile

• Odor

• Application-specific trace impurities

Test a Representative Sample

Use a sample from the same commercial grade proposed for the bulk order. Evaluate it in the customer’s own resin, additives, processing conditions and end-use tests.

Check Packaging Compatibility

TBC should be packaged in clean, compatible containers. Previous cargo, liner composition, seals and transfer equipment can affect odor, color and contamination risk.

What Documents Should a TBC Supplier Provide?

Depending on the intended use, request:

• Current Technical Data Sheet

• Current Safety Data Sheet

• Batch Certificate of Analysis

• Product specification

• Country-of-origin statement

• Packaging specification

• Shelf-life or retest guidance

• REACH or inventory information where applicable

• Non-phthalate statement with a defined scope

• Regulatory declarations for the intended market

• Additional impurity testing when required

A generic statement such as “FDA approved” is insufficient. The declaration should identify the applicable regulation, product grade, conditions of use and supporting test scope.

Food-Contact, Medical and Pharmaceutical Compliance

TBC must not be described as universally approved for food-contact, medical or pharmaceutical applications.

Before using it in a regulated application, determine:

• Whether TBC is specifically listed or otherwise permitted

• Whether the intended polymer and use conditions are covered

• Applicable specific or overall migration limits

• Temperature and contact-time restrictions

• Required purity or monograph

• Extractables and leachables requirements

• Finished-product testing responsibilities

Regulatory permissions applicable to ATBC, TEC or another citrate ester cannot be transferred to TBC.

Packaging Options

AOZUN’s published packaging options include:

• 200 L steel drums

• 1000 L IBC tanks

• Flexitank supply

• Customized packaging by agreement

Net weight, container material, loading quantity and transport conditions should be confirmed in the commercial quotation.

Storage and Handling

Store tributyl citrate:

• In its original, tightly closed container

• In a cool, dry and well-ventilated area

• Away from direct sunlight and uncontrolled heat

• Away from strong oxidizing agents

• In equipment dedicated to compatible liquid chemicals

• With suitable secondary containment

• Under conditions that prevent water and particulate contamination

If material has been stored at low temperature, allow it to reach an appropriate handling temperature and mix gently before sampling. Investigate any unexpected haze, phase separation, sediment, odor or color change before use.

Follow the shelf-life or retest period shown in the applicable AOZUN documentation.

Safe Handling of Tributyl Citrate

Consult the current AOZUN SDS before handling TBC.

Normal industrial precautions include:

• Chemical-resistant gloves

• Safety glasses or splash goggles

• Suitable protective clothing

• Adequate workplace ventilation

• Controlled pumping and transfer

• Prompt cleanup of spills

• Prevention of discharge to drains or waterways

• Protection from heat and ignition sources

Although TBC has a relatively high flash point, it is an organic combustible liquid and should not be treated as fireproof.

Why Buy Tributyl Citrate from AOZUN?

AOZUN supports industrial buyers by matching the supplied TBC grade with the customer’s specification, application and logistics requirements.

Support may include:

• Pre-order specification review

• Representative samples

• Batch COA

• TDS and SDS documentation

• Drum, IBC or flexitank supply

• Export-document coordination

• Customer-defined testing by agreement

• Technical communication during material qualification

Final specifications, documentation, packaging and regulatory requirements should be agreed in writing before order confirmation.

What Information Should Be Included in a TBC RFQ?

To receive an accurate quotation, provide:

• Product name: Tributyl Citrate

• CAS number: 77-94-1

• Intended polymer or formulation

• Required assay

• Maximum acid value

• Maximum water and color

• Additional impurity limits

• Required regulatory documents

• Trial quantity

• Regular order volume

• Packaging preference

• Destination port or address

• Required delivery schedule

Frequently Asked Questions

What Is Tributyl Citrate Used For?

TBC is primarily used as a plasticizer or film-forming aid in compatible PVC, vinyl, cellulose, coating, ink, adhesive and selected biopolymer formulations.

Is Tributyl Citrate the Same as Acetyl Tributyl Citrate?

No. TBC is CAS 77-94-1, while ATBC is CAS 77-90-7. ATBC contains an additional acetyl group and has different physical, performance and regulatory characteristics.

Is TBC Soluble in Water?

TBC has low water solubility. It is more compatible with many organic solvents and selected polymers than with water. Water-based formulations generally require appropriate emulsification or dispersion technology.

Can TBC Replace DOP, DINP, DOTP or ATBC One for One?

No universal one-to-one replacement ratio exists. Plasticizer efficiency, molecular weight, compatibility, volatility, migration and regulatory properties differ. Use a concentration ladder and compare finished-product performance.

What Is the Typical Purity of TBC?

AOZUN’s published target is at least 99.0%. Buyers should also review acid value, water, color and any application-specific impurity requirements.

Why Is Acid Value Important?

Acidic impurities can affect heat stability, color, odor, corrosion and sensitive curing reactions. Confirm both the numerical limit and the analytical method.

Can TBC Be Used in Food Packaging?

Only when the exact supplied grade, intended material, destination regulation, use conditions and finished-product migration results support that application. Do not rely only on the CAS number or a general marketing statement.

Can TBC Be Used in Pharmaceutical Products?

Only a specifically qualified grade with the required regulatory, impurity and application documentation should be considered. Industrial-grade TBC must not automatically be used as a pharmaceutical excipient.

Is TBC a Non-Phthalate Plasticizer?

Yes. TBC is chemically a citrate ester rather than a phthalate. A commercial “phthalate-free” claim may still require trace testing and contamination controls.

What Packaging Is Available?

AOZUN lists 200 L steel drums, 1000 L IBC tanks, flexitank supply and customized packaging options. Confirm net weight and loading details in the quotation.

Request a Tributyl Citrate Sample or Quotation

Contact AOZUN for current TBC pricing, samples, specifications, COA, SDS, packaging and export information.

For technical evaluation, include your polymer, current plasticizer, target loading, processing temperature and required performance tests. This helps AOZUN align the proposed grade and documentation with your qualification program.