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| Synonyms:TPP Triphenylphosphate Phosphoric acid, triphenyl ester TPA Molecular Formula:C18H15O4P Molecular Weight: 326.28 HS Code: 2919900090 Grade: Industrial grade 99% Hazard Class:Class9 | |||||||||
115-86-6
bosschemical
115-86-6
Triphenyl phosphate (TPP, TPhP, or Triphenyl ester of phosphoric acid) is an aryl phosphate ester that is made by the esterification of phenol and phosphoric acid. It is one of the most popular halogen-free and environment-friendly organophosphorus flame retardants and plasticisers. Its chemical formula is often represented as:
C18H15O4P (CAS No.: 115-86-6. EINECS No.: 204-112-2. OP(OC6H5)3. Molecular weight: Approx. 326.29)
It is a white crystalline powder (needle-shaped crystals) at ordinary temperature, odourless, slightly hygroscopic, melting point about 48-50℃, boiling point about 370℃ (decomposes). Insoluble in water; soluble in organic solvents such as ether, benzene, chloroform and acetone. It is produced industrially by the esterification of phosphorus oxychloride (or phosphorus trichloride) with phenol.
Structurally , the TPP molecule consists of the phosphate group in the middle and three benzene rings attached to it . The flame retardant function is based on the phosphate group (it decomposes when heated to form phosphorus-containing active species). The three benzene rings give it rigidity and excellent compatibility, so it plays the role of flame retardant and plasticiser. It is a bifunctional phosphate ester providing both flame retardancy and plasticization.
TPP is chemically and hydrolytically stable and is compatible with most polymers. It is of low toxicity, but has been shown to have endocrine disrupting properties. Keep in a sealed, moisture-proof and light-protected environment.
This product is divided into application areas, generally including: industrial grade (used for flame retardant plasticising of PVC, engineering plastics and foams, common specifications are 99% or more), electronic grade (used for flame retardant additive in lithium battery electrolyte), reagent grade (used for analytical testing). Different grades have different purity control requirements, and the following indicators are paid special attention to:
1. Melting point
The melting point is a routine index for factory inspection, which reflects the purity and the consistency of the crystal form of the product, and must be controlled within the indicated range (about 48-50℃).
2.acid number
Acid value is a reflection of the free acid content , which affects the stability of products and the quality of downstream products, so it should be controlled within a reasonable range.
3. Moisture
Moisture content influences the stability of product storage and processing performance, and should be strictly controlled.
4. Colour (APHA)
The colour affects transparency and appearance of downstream products and the product has to have a white crystalline appearance.
5. Chlorine and ash content
The ash content is indicative of the total amount of inorganic impurities, and the chlorine content is an important indicator for halogen-free flame retardants and must be controlled within extremely low range.
6. Volatile Matter
Impurities with low boiling point will be reflected in volatile matter, which will affect processing stability and product performance, and need to be controlled within a reasonable range.
TPP with its unique “phosphorus-based flame retardancy+plasticization+lubrication” properties is used in plastics, rubber, coatings, electronics, new energy, hydraulics and daily chemical industry.
1. PVC flame retardant plasticizer(main application in plastics industry)
TPP is the most important flame-retardant plasticiser for PVC (polyvinyl chloride) (about 50% of its total usage). It has the functions of flame retardant and plasticiser. It is used in PVC sheets, films, wire and cable materials, artificial leather and roofing materials. It helps products meet flame retardant requirements while maintaining flexibility.
Why it is suitable for this purpose: One TPP molecule provides both phosphorus-based flame retardancy (gas-phase free radical quenching + solid-phase charring) and phosphate ester plasticization (intercalation between chains to lower T_{g}). It provides flame retardancy and flexibility without the addition of plasticisers. The benzene ring structure provides a good compatibility which is economical and efficient.
2. Flame retardants for engineering plastics (main application in engineering plastics field)
TPP serves as a flame retardant plasticiser for engineering plastics like PC/ABS, ABS, PC, PPO, HIPS, PP, and epoxy resin (EP), enhancing the flame retardancy rating and processing flowability of these materials. It is also used as a plasticiser and flame retardant for phenolic resin laminates and is widely used in electronic and electrical housings and automotive parts.
Why it is suitable for this purpose:TPP has moderate melting point (about 48-50℃), good compatibility with engineering plastics, and can be uniformly dispersed at processing temperature; phosphorus-based halogen-free flame retardant is in line with environmental trends, and its plasticising effect can also reduce melt viscosity and improve the mould filling flowability of thin-walled electronic and electrical components.
3. Flame retardants for polyurethane foam (furniture and home furnishings)
TPP is used as a flame retardant in flexible and rigid polyurethane foams to help reduce the flammability of sofas, mattresses, chairs and insulation foams. It is widely used in furniture upholstery, children’s products and building insulation materials. Why it is suitable for this purpose:Flexible polyurethane foam is highly porous, has a large specific surface area and is highly flammable. The chain reaction could be interrupted by the free radical quenching mechanism of TPP in the gas phase at the early stages of combustion. It is low dosage, low smoke and low toxicity, and does not affect the resilience or feel of the foam.
4.Plasticizers for cellulose resin plastics (plastic coating industry)
TPP is employed as a plasticiser for cellulose acetate , nitrocellulose and varnishes . It is also a non-flammable substitute for camphor in celluloid and aids in enhancing the flexibility and flame retardancy of cellulose. It is widely used in plastic products, varnishes and paints.
Why it is suitable for this purpose: Nitrocellulose and other products made from it are extremely flammable. TPP can replace camphor to provide plasticising effects, and also provide phosphorus-based flame retardancy, achieving two benefits at the same time. It has good polar compatibility with cellulose and the benzene ring structure can be uniformly dispersed without precipitation.
5.Softeners for Synthetic Rubber (Rubber Industry)
TPP is used as a softener and flame retardant for natural and synthetic rubber, contributing to improvement of rubber processing properties and the flame retardancy of finished products, serving the rubber products industry.
Why it is suitable for this purpose: The polar phosphate groups in TPP can reduce the intermolecular forces in rubber and increase the flexibility and processability. It can also provide phosphorus-based flame retardancy, which is suitable for rubber products that require flame retardancy such as flame-retardant sheets and cable rubber sheaths.
6.Fire-resistant wires and cables (cable industry)
TPP is used as a flame-retardant plasticiser for flame-retardant PVC wire and cable materials and cable sheaths to meet the flame-retardant rating requirements for cables. It is widely used in wiring of buildings and electronic cables.
Why it is suitable for this purpose:Wires and cables have to be both flame retardant and flexible, and TPP’s dual-functional properties match this requirement perfectly. Its resistance to hydrolysis and non-migration properties ensure the stable flame retardant performance of the cable for long-term use and high temperature environment.
7.Hydraulic fluid (hydraulic area) fire retardant
TPP is widely used in hydraulic systems in mining, aviation and industry as a component of flame-retardant hydraulic fluids to help prevent combustion under high temperature and pressure.
Why it is suitable for this purpose:Under high temperature and pressure conditions, there is a risk of combustion and explosion for hydraulic fluids. The phosphorus-based flame retardant property of TPP enhances the flash point and flame-retardant safety of the hydraulic fluid, and its polar molecules can form an adsorption film and tribochemical reaction film on the metal surface, reducing wear and friction and protecting the hydraulic components at the same time.
8. Coatings industry – flame retardant and plasticising coatings
TPP is used as a flame retardant plasticiser in paints, coatings & paint layers to improve the flexibility and flame retardancy of coating films and is used in the architectural and industrial coatings industry.
Why it is suitable for this purpose: Coatings tend to crack and become flammable after film formation. TPP intercalates between resin chains to improve flexibility of the film and reduce the tendency for internal stress cracking and at the same time provide phosphorus based flame retardancy to improve fire resistance rating of coatings. It is also well compatible and does not affect the glossiness.
9. Adhesives and sealants (adhesive area)
TPP is used as a flame retardant plasticiser in adhesives and sealants. It helps to improve the flexibility and flame retardancy of adhesives. It serves the construction, packaging and electronics adhesive industries.
Why it is suitable for this purpose: After curing the adhesive layer is likely to be hard and brittle. TPP reduces the glass transition temperature of the adhesive, improves its flexibility and low temperature performance, and provides flame retardancy, thus meeting the flame-retardant requirements of electronic adhesives and building sealants.
10. Daily Chemical Industry Plasticisers for Nail Polish
TPP is used as a plasticiser and film-forming aid in nail polish products to improve the flexibility and adhesion of the nail polish film. This is the use of TPP in the cosmetics industry (and one of the sources of concern regarding human exposure to it).
Why it is suitable for this purpose:The phosphate ester plasticising mechanism of TPP can reduce the glass transition temperature of the nail polish film-forming resin, thus making the nail polish film more flexible and less likely to crack, with better adhesion, and forming a transparent and glossy film .
11. Flame retardant additive for lithium ion battery electrolyte (new energy area, core electronic applications)
The flame-retardant additives of electronic-grade TPP in lithium-ion battery electrolytes can suppress electrolyte combustion and improve battery safety during battery thermal runaway, which is an important direction of new energy battery safety technology.
Why it is suitable for this purpose:TPP scavenges active free radicals generated during the decomposition of electrolyte during battery thermal runaway or overcharging and inhibits the combustion chain reaction of flammable carbonate solvents. The trade-off is a potential slight decrease in ionic conductivity, which requires optimising the amount of addition to balance flame retardancy and electrochemical performance.
12. Stationary phase for gas chromatography (core reagent-grade for use in analytical testing).
Reagent grade TPP is used as stationary phase in gas chromatography (GC) (max operating temperature ca 175°C, solvent: diethyl ether) for the specific separation and analysis of certain components and is commonly utilised as a stationary phase in analytical laboratories.
Why it is suitable for this purpose:TPP has a high boiling point (approximately 370°C) and good thermal stability, so it will not bleed in the temperature range of the column. It has aryl phosphate structure that selectively retains aromatic hydrocarbons and oxygenated organic compounds giving excellent separation.
13. Fine chemical intermediates (chemical industry)
TPP is an intermediate in fine chemicals used in the manufacture of trimethyl phosphate and other organophosphate esters, providing the phosphorus-based fine chemicals industry.
Why it is suitable for this purpose:TPP can be transesterified with other alcohols to give a variety of organophosphate esters. It has moderate reactivity and the by-product (phenol) can be easily separated and recovered, thus it is an ideal raw material to prepare phosphorus-based fine chemicals.
Triphenyl phosphate (TPP, C18H15O4P, CAS No. 115-86-6, EINECS No. 204-112-2) is a white, odourless crystalline powder, which is insoluble in water. It has become one of the most widely used halogen-free organophosphorus flame retardants and plasticisers with its dual mechanisms of phosphorus-based flame retardancy (gas-phase free radical quenching + solid-phase char formation) and phosphate ester plasticization (interchain insertion to reduce Tg). It shows up in our everyday lives as wires and cables, electronic devices, sofa foam, automotive interiors, flooring and roofing, nail polish, and lithium batteries. TPP is widely used in applications such as flame retardant plasticiser for PVC, flame retardant for engineering plastics, flame retardant for polyurethane foam, plasticiser for cellulose resin, softener for synthetic rubber, flame retardant for wires and cables, flame retardant hydraulic fluid, flame retardant plasticiser for coatings, adhesive sealant, nail polish plasticiser, flame retardant additive for lithium-ion battery electrolytes, stationary phase in gas chromatography and fine chemical It’s a multi-functional flame retardant plasticiser that fills the gap between “phosphorus-based flame retardant chemistry” and “plastics, rubber, coatings, electronics, new energy, hydraulics and daily chemicals”. Meanwhile, the endocrine disrupting potential calls for a focus on environmental compliance and green alternatives.
