Halogen Free Flame Retardant: FR99RP & FR76RP – A Technical Deep Dive from Mechanism to Application

This article systematically presents the technical mechanisms, performance comparisons, and engineering selection guides for GreenThinking® FR series halogen free flame retardant products – FR99RP and FR76RP. FR99RP is developed for EPDM, NBR and other rubber compounds, achieving UL94 V0 rating while maintaining excellent tensile strength, heat aging resistance, low compression set and high resilience. FR76RP is specially designed for silicone sealants, featuring ultrafine particle size, outstanding dispersion and antidrip properties, and can be used at up to 50% by volume in silicone compounds. Both products are REACH, RoHS and WEEE compliant, representing the technological evolution of halogen free flame retardant from “sacrificing performance for safety” to “achieving both safety and performance”. This article serves as a technical reference for formulation engineers and material selectors in the rubber and sealant industries.

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OneSentence Definition

FR99RP is a phosphorusnitrogen intumescent halogen free flame retardant composite that works through a triple synergistic mechanism – forming a dense ceramic char layer upon heating, radical trapping, and endothermic cooling – to achieve V0 flammability rating in various rubbers such as EPDM and NBR without compromising mechanical properties and durability. FR76RP is an ultrafine silicone sealant flame retardant specifically engineered for silicone sealants, delivering a balanced combination of high flame retardancy, excellent dispersion and antidrip performance in silicone systems.

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Why It Happens: The Technical Paradigm Shift from “Compliance” to “Performance” in the Flame Retardant Industry

The global flame retardant market is undergoing a profound supplyside transformation. Traditional halogenated flame retardants (such as polybrominated biphenyls, polybrominated diphenyl ethers, decabromodiphenyl ethane, etc.) are highly efficient, but their combustion products contain persistent organic pollutants like dioxins and furans, which have been progressively restricted or banned by regulations such as RoHS, REACH and WEEE worldwide.

However, the transition to halogenfree solutions has not been smooth. The industry has long faced a technical dilemma: the tradeoff between flame retardancy and physical properties. Many halogen free flame retardant products require high loadings (over 100 phr) to achieve UL94 V0, at the cost of reduced tensile strength, lower elongation, worsened compression set, and poor processability. For rubber products such as seals, antivibration parts and cable sheaths that demand strict mechanical properties and durability, this “performance for safety” compromise is often unacceptable to engineers.

At the same time, application requirements for flame retardancy continue to escalate:

• Railway transportation: standards like EN 45545 and DIN 5510 require materials to simultaneously meet flame retardancy, low smoke, and low toxicity (FLST) – hence the need for a low smoke flame retardant manufacturer capable of delivering all three.
• New energy vehicles: rubber parts inside battery packs must withstand thermal runaway conditions, requiring flame retardancy, high temperature resistance and insulation together – creating demand for a reliable flame retardant for EV battery rubber insulation parts.
• Building sealants: China’s GB/T 242672009 “Flame retardant sealants for building” sets clear technical requirements.

Against this background, the industry no longer needs just a “filler that can retard flames”, but a functional additive that retards flames without sacrificing performance. The GreenThinking® FR series (FR99RP and FR76RP) was developed precisely during this paradigm shift, and is offered by a leading halogen free flame retardant manufacturer that understands these realworld engineering needs.

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Common Misconceptions

Misconception 1: Halogenfree flame retardants are the same as metal hydrates like aluminium hydroxide or magnesium hydroxide.
Aluminium hydroxide (ATH) and magnesium hydroxide (MDH) are common halogen free flame retardant types, working by endothermic decomposition and water vapour release. However, their efficiency is low; typically 150200 phr is required to reach V0, causing severe property loss. FR99RP and FR76RP belong to the phosphorusnitrogen intumescent system, with much higher efficiency – recommended dosages are only 60130 phr, making them a true rubber fire retardant additive supplier’s choice for highperformance compounds.

Misconception 2: The more flame retardant added, the better the flame retardancy.
Flame retardancy has a “critical concentration” effect. Overloading not only deteriorates mechanical properties but may also reduce uniformity due to agglomeration. A better strategy is to use synergistic ratios and particle size design to achieve V0 at lower loadings.

Misconception 3: The finer the flame retardant, the better.
Excessively fine particles cause dusting losses, difficult mixing, and increased Mooney viscosity. FR99RP and FR76RP adopt a rational particle size distribution (D50 12 μm) to balance dispersion and processability – a hallmark of an experienced EPDM flame retardant manufacturer and silicone specialist.

Misconception 4: All halogenfree flame retardants are automatically compliant with environmental regulations.
“Halogenfree” and “compliant” are two different concepts. Some halogenfree products may still contain REACH Substances of Very High Concern (SVHC). The FR series has passed independent thirdparty testing and complies with REACH SVHC and RoHS 2.0 (including 2015/863 amendment), making us a trusted REACH compliant flame retardant supplier.

Misconception 5: Flame retardants only affect flammability, not product service life.
The type of flame retardant directly impacts longterm reliability. Earlier products like FR98RP could achieve V0, but their hightemperature compression set reached 52.94% – meaning seals would quickly lose their sealing function under high temperatures. FR99RP achieves the same V0 rating with a compression set of only 31.43%, significantly extending service life. This is exactly what a rubber flame retardant with low heat aging degradation should deliver.

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Root Cause Analysis: Three Origins of Performance Degradation in FlameRetardant Rubber

Root Cause 1: Weak interfacial bonding between flame retardant and rubber matrix
Most inorganic or organic flame retardants have limited compatibility with rubber, forming a “seaisland” dispersion. Without chemical bonding at the interface, they become stress concentration points under dynamic loading, initiating microcracks. FR99RP uses surface activation technology to improve interfacial bonding.

Root Cause 2: Interference of flame retardant with the vulcanisation network
The acidic/basic nature or reactivity of some flame retardants can disturb the vulcanisation reaction, manifesting as shortened scorch time (TS2) or extended cure time (TC90). FR99RP shows better compatibility with curing systems than FR98RP – in a 70 Shore A EPDM formulation, TC90 is 112 s, significantly shorter than FR98RP’s 221 s, meaning higher production efficiency.

Root Cause 3: Decomposition products accelerate thermooxidative aging
Byproducts released during vulcanisation or longterm service can catalyse thermooxidative aging, resulting in rising hardness, falling tensile strength, and rapid deterioration of compression set. FR99RP’s hot air aging data (100℃×70h) show a tensile strength change of only 3.54% and elongation change of 18.31%, far superior to FR98RP – clearly demonstrating it as a rubber chemical to achieve V0 flammability without property loss.

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Technical Mechanism: Triple Synergistic Flame Retardancy of FR99RP and FR76RP

The core technical logic of the FR series is not a single mechanism, but a triple synergistic physicochemical process involving condensed phase, gas phase, and thermodynamic effects.

Mechanism 1: Dense char layer formation – condensed phase barrier
When heated or exposed to flame, the FR series rapidly decomposes and expands on the rubber or silicone surface, forming a dense, viscous ceramic crust insulation layer. This char layer provides three barrier functions:

• Oxygen isolation: cuts off oxygen supply for combustion.
• Heat feedback blocking: reduces radiant heat from the flame to the substrate, suppressing internal temperature rise.
• Volatile barrier: prevents combustible small molecules from diffusing to the flame zone.

FR76RP forms a viscous crust in silicone sealants with a unique antidrip function – no molten drops are produced during combustion, preventing flame spread. This makes it an ideal non halogen fire retardant for silicone sealant applications.

Mechanism 2: Radical trapping – gas phase chain termination
Upon thermal decomposition, FR series release phosphoruscontaining active radicals that efficiently capture H· and OH· radicals sustaining the combustion chain reaction, forming stable molecular products and interrupting the chain reaction – a gasphase flame retardancy effect.

Mechanism 3: Endothermic cooling and dilution
The thermal decomposition of the FR series is endothermic, absorbing large amounts of heat from the combustion zone and lowering the substrate surface temperature. At the same time, released inert gases like water vapour and CO₂ dilute the combustible gas concentration in the flame zone, further inhibiting combustion.

Differentiated mechanism of FR76RP in silicone sealants
Silicone sealants are based on polydimethylsiloxane (PDMS), whose combustion behaviour differs from organic rubbers – silicone itself contains a SiO backbone and forms a silica skeleton upon burning. FR76RP leverages this by embedding a viscous crust into the silica skeleton, forming a “inorganic skeleton + viscous char” composite barrier, achieving higher efficiency than ordinary flame retardants in organic rubbers. Meanwhile, its ultrafine particle size (D50 12 μm) and surface treatment ensure a “glossy, bubblefree” dispersion in 107 base polymers – a key requirement for any silicone sealant flame retardant.

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Comparative Analysis

Table 1: Performance comparison between FR99RP and FR98RP in EPDM 70 Shore A

Property	FR98RP100	FR99RP100	Remarks
Hardness / Shore A	74	76	Slightly higher for FR99RP
Tensile strength / MPa	6.35	9.32	↑46.8%
Elongation at break / %	417	497	↑19.2%
M100 / MPa	2.59	2.69	Similar
TC90 (cure time) / sec	221	112	↓49.3% (higher productivity)
MHML (crosslink density) / lbf·in	10.18	13.58	↑33.4%
UL94 rating	V0	V0	Both pass
LOI / %	42.3	35.4	FR98RP higher
Hardness change after aging	+5	+3	FR99RP better
Tensile change after aging / %	7.56	3.54	FR99RP better
Elongation change after aging / %	34.05	18.31	FR99RP better
Compression set (120℃×24h) / %	52.94	31.43	FR99RP much better
Rebound resilience / %	37	47	FR99RP better
Burning behaviour	Strong swelling, heavy smoke	Forms ceramic char	FR99RP cleaner

Interpretation: FR98RP has an advantage in LOI (42.3% vs 35.4%), but this comes at the cost of lower tensile strength, longer cure time, worse compression set and lower resilience. FR99RP sacrifices some LOI to achieve comprehensive superiority in all mechanical, processing and longterm durability indicators. For most engineering applications, V0 plus excellent property balance is more valuable than a higher LOI number. If LOI is the sole priority, FR98RP may still be considered, but with full acceptance of its performance tradeoffs.

Table 2: Performance comparison between FR99RP and FR98RP in NBR 70 Shore A

Property	FR98RP100	FR99RP100	Remarks
Hardness / Shore A	75	76	Similar
Tensile strength / MPa	9.43	9.23	Close
Elongation at break / %	522	455	FR98RP higher
M100 / MPa	2.55	2.94	FR99RP higher modulus
MHML (crosslink density) / lbf·in	8.45	12.53	↑48.3%
UL94 rating	V0	V0	Both pass
LOI / %	37.8	32.6	FR98RP higher
Rebound resilience / %	24	33	↑37.5%

Interpretation: In NBR systems, FR99RP also maintains V0 while providing higher crosslink density and resilience – critical for oil seals, gaskets and other dynamic sealing applications, making it a preferred flame retardant for NBR oil resistant rubber products and UL94 V0 flame retardant for NBR hydraulic hose compounds.

Table 3: Applicability comparison of FR76RP with general flame retardants in silicone sealants

Comparison dimension	FR76RP	Aluminium hydroxide (ATH)	Halogenated flame retardant
Efficiency (loading for V0)	~50% by volume	High loading	Low loading
Dispersion	Excellent (surfacetreated)	Fair	Fair
Silicone appearance	Glossy, bubblefree	May be rough	May discolour
Antidrip	Yes (viscous crust)	No	Some
Halogen content	Halogenfree	Halogenfree	Contains halogen
REACH/RoHS compliant	Yes	Yes	Partly noncompliant
Effect on mechanicals	Slight	Significant reduction	Slight

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Applications

FR99RP typical applications

No.	Industry	Typical products	Key contribution
1	Railway transportation	Highspeed train sealing strips, floor mats, buffer pads	V0 + low smoke + low toxicity, compliant with DIN 5510/EN 45545 – ideal as a halogen free flame retardant for railway sealing strips
2	New energy vehicles	Battery insulation gaskets, highvoltage cable sheaths, connector seals	V0 + heat resistance + insulation – a proven flame retardant for EV battery rubber insulation parts
3	Wire & cable	EPDM/NBR insulation layers, jacketing	V0/VW1 + flexibility
4	Automotive	Oilresistant hoses, engine mounts, dust covers	Flame retardancy + oil resistance + heat aging resistance
5	Mining & petroleum	Fireresistant conveyor belts, antistatic seals	V0 + antistatic
6	Building seals	Fireretardant sealing strips, expansion joints	Flame retardancy + weather resistance + compression recovery
7	Electronics	Appliance gaskets, plug sheaths	V0 + dimensional stability
8	Aerospace	Cabin seals, cable sheaths	Low smoke, low toxicity + flame retardancy
9	Industrial rubber goods	Diaphragms, linings, vibration dampers	Flame retardancy + dynamic fatigue resistance
10	Consumer goods	Flameretardant rubber mats, tool grips	Halogenfree, environmentally friendly, good touch

FR76RP typical applications

No.	Application	Typical products	Key requirements
1	Building sealants	Flameretardant sealants per GB/T 242672009	V0 + adhesion strength – a dedicated silicone sealant flame retardant
2	Electronics	Potting compounds, thermally conductive flameretardant adhesives	Halogenfree + dimensional stability
3	New energy vehicles	Battery pack sealants, thermally conductive structural adhesives	V0 + thermal conductivity + adhesion
4	Transportation	Vehicle body sealants, window bonding adhesives	Flame retardancy + weather resistance + adhesion
5	Solar/wind power	Junction box potting, module sealing	Weather resistance + flame retardancy + insulation

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Case Studies

Case 1: EPDM railway sealing strips – FR99RP performance validation

Background: A European railway component manufacturer needed sealing strips for a new highspeed train, requiring UL94 V0, hardness change ≤5 points after 100℃×70h aging, and compression set ≤40% at 120℃×24h.

Problem: The previous halogen free flame retardant (competitor product) caused: tensile strength drop from 9.5 MPa to 6.2 MPa (35%); hardness rise of 8 points after aging (fail); compression set >50% (120℃×24h), leading to rapid seal failure.

Analysis: Root causes were weak interfacial bonding, interference with vulcanisation, and catalytic thermooxidative aging by decomposition products.

Solution: Switched to FR99RP at 100 phr, other components unchanged.

Result:

• Tensile strength: 9.32 MPa (retention >98%)
• Hardness change after aging: +3 points (pass)
• Compression set (120℃×24h): 31.43% (better than 40%)
• UL94 V0: passed
• LOI: 35.4%

Lessons learned: V0 and excellent longterm durability can be achieved together – the key is selecting the right product, not just adjusting dosage. This confirms FR99RP as an outstanding halogen free flame retardant for EPDM rubber compounds and a reliable flame retardant for rubber seals meets UL94 V0 level.

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Case 2: NBR automotive oil hoses – FR99RP improves resilience

Background: An automotive parts supplier produced NBR oilresistant hoses that needed UL94 V0, and required sufficient resilience to ensure lasting sealing at hose joints.

Problem: Using FR98RP to reach V0 reduced resilience to only 24%, causing oil leakage at joints after longterm service.

Analysis: FR98RP significantly lowered crosslink density (MHML only 8.45 lbf·in), resulting in incomplete elastic network and poor recovery after compression.

Solution: Switched to FR99RP at the same loading.

Result:

• UL94 V0: maintained
• Resilience: from 24% to 33%
• Crosslink density (MHML): from 8.45 to 12.53 lbf·in
• Tensile strength: 9.23 MPa (comparable to FR98RP’s 9.43 MPa)

Lessons learned: For dynamic sealing applications, resilience is as important as flame retardancy. FR99RP’s “high crosslink density + high resilience” makes it a superior flame retardant for NBR oil resistant rubber products and an excellent UL94 V0 flame retardant for NBR hydraulic hose compounds.

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Case 3: Silicone sealant flameretardant formulation – FR76RP application

Background: A building sealant manufacturer needed a product compliant with GB/T 242672009 for highrise fire stops.

Problem: Using ATH as flame retardant required >60% loading to meet requirements, but caused severe loss of flow, difficult extrusion, and reduced adhesion.

Solution: Replaced ATH with FR76RP at about 50% by volume in 107 base polymer.

Result:

• Flame rating: compliant with GB/T 242672009
• Dispersion: glossy, bubblefree appearance
• Flow: good, easy application
• Adhesion: maintained
• Environmental compliance: halogenfree, REACH/RoHS compliant

Lessons learned: Silicone sealant flame retardancy cannot simply copy rubber formulation logic. FR76RP’s particle size and surface treatment are optimised for silicone systems, achieving a balance of “flame retardancy + processability + adhesion” – a true non halogen fire retardant for silicone sealant applications.

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Failure Analysis: Typical Failure Modes in FlameRetardant Rubber and FR99RP Countermeasures

Failure mode 1: Seal failure under hightemperature service
Symptoms: Seals lose sealing function after longterm service at 80120℃ due to increased compression set.
Root cause: Flame retardant affects network stability; crosslinks break or rearrange at high temperatures, losing elastic recovery.
FR countermeasure: FR99RP compression set at 120℃×24h is only 31.43%, far better than the competitor’s 52.94%, demonstrating excellent thermal stability of the crosslinking network.

Failure mode 2: Surface cracking after thermooxidative aging
Symptoms: Crazing on surface, sharp drops in tensile strength and elongation.
Root cause: Decomposition products catalyse oxidation, accelerating chain scission.
FR countermeasure: FR99RP retains 96.5% tensile strength (change 3.54%) and 81.7% elongation (change 18.31%) after aging – truly a rubber flame retardant with low heat aging degradation.

Failure mode 3: Molten drips during combustion causing secondary fires
Symptoms: Rubber or sealant produces hot drips that ignite underlying materials.
Root cause: Some flame retardants cannot form stable char and melt drip.
FR countermeasure: FR76RP forms a viscous crust in silicone with antidrip properties; FR99RP forms a ceramic monolith char with no drips.

Failure mode 4: Migration and contamination of contact surfaces
Symptoms: Flame retardant migrates to the surface over time, contaminating metals or electronic components.
Root cause: Poor compatibility, low molecular weight.
FR countermeasure: Surfaceactivated FR series have strong bonding with rubber matrix, low migration tendency.

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Selection Guide: Choosing Between FR99RP and FR76RP

Choose FR99RP when:

• Base material is organic rubber such as EPDM, NBR, NR, SBR, CR, IIR, ACM.
• UL94 V0 is required.
• Retention of properties after heat aging is critical (longterm hightemperature service).
• Low compression set is needed (seals, gaskets).
• High resilience is required (dynamic sealing, antivibration).
• Processing efficiency is pursued (short cure time).
• Applications in railway, automotive, cable, industrial rubber goods – making it a versatile rubber fire retardant additive supplier’s top recommendation.

Choose FR76RP when:

• Base material is silicone sealant / silicone rubber.
• Excellent dispersion and glossy appearance are required.
• Antidrip performance is needed.
• Adhesion and dimensional stability are important.
• Building flameretardant sealants per GB/T 242672009.
• Electronic potting, EV battery pack sealing – an ideal silicone sealant flame retardant and non halogen fire retardant for silicone sealant applications.

Choose FR98RP only when:

• LOI is the absolute top priority, and you accept the tradeoffs in tensile strength, cure time, compression set and resilience.
• Not recommended for routine selection.

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Lifecycle Analysis

FR99RP in EPDM seals – performance evolution

Early stage (06 months):

• Excellent dispersion and low interference with curing ensure high initial consistency.
• Smooth surface, good dimensional accuracy.
• Stable V0 flame retardancy.

Mid stage (6 months – 3 years):

• Heat aging advantages emerge – slow hardness rise, high retention of tensile strength and elongation.
• Low compression set maintains sealing function.
• Good weatherability and ozone resistance (EPDM matrix + FR99RP does not impair these).

Late stage (>3 years):

• Service life extended by about 4060% compared to FR98RP formulations.
• Charforming ability ensures flame retardancy throughout the lifecycle.
• Lower maintenance and replacement frequency, clear total cost advantage.

FR76RP in silicone sealants:

• Early: glossy, dimensionally stable, good adhesion.
• Mid: waterresistant, mouldresistant, stable flame retardancy.
• Late: stable highlow temperature performance, no powdering or cracking.

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Standards and Compliance

FR99RP and FR76RP comply with or can pass the following standards:

• REACH (EC 1907/2006) – SVHC testing passed, making us a dependable REACH compliant flame retardant supplier.
• RoHS 2.0 (2011/65/EU) – including 2015/863 amendment on four phthalates.
• WEEE (2012/19/EU) – compliant.
• UL94 V0 – achievable in both rubber and silicone formulations.
• GB/T 242672009 – for building flameretardant sealants (FR76RP application).
• Free from: PBB, PBDE, chlorine, fluorine, antimony trioxide.

Note: For specific certification numbers, please refer to the product TDS and SDS.

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FAQ

Q1: What is the core difference between FR99RP and FR98RP?
Short Answer: FR99RP is the nextgeneration product, superior in mechanical properties, heat aging, compression set and resilience, but with lower LOI.
Detailed Answer: FR98RP has higher LOI (42.3% vs 35.4%), but at the cost of 46.8% lower tensile strength, 49.3% longer cure time, 68.5% higher compression set and 21% lower resilience. FR99RP sacrifices some LOI for comprehensive balance – better for most engineering applications.

Q2: Which rubbers is FR99RP suitable for?
Short Answer: EPDM, NBR, NR, SBR, CR, IIR, ACM, etc.
Detailed Answer: FR99RP has been systematically verified in EPDM and NBR with excellent results; for other rubbers, formulation validation is recommended. As an EPDM flame retardant manufacturer, we have extensive data for EPDM systems.

Q3: What is the difference between FR76RP and FR99RP?
Short Answer: FR76RP is for silicone sealants; FR99RP is for organic rubbers.
Detailed Answer: FR76RP has finer particle size (D50 12 μm) and specialised surface treatment, giving excellent dispersion, glossy appearance and antidrip in silicone. FR99RP performs best in EPDM/NBR and other rubbers.

Q4: What is the recommended dosage of FR99RP?
Short Answer: 60130 phr.
Detailed Answer: Adjust based on hardness, physical properties, flame rating and processing; roughly 68 phr increases hardness by 1 Shore A, 35 phr increases LOI by 1 unit.

Q5: What is the dosage of FR76RP in silicone sealants?
Short Answer: About 50% by volume.
Detailed Answer: Can be adjusted according to properties, flame rating and processing requirements.

Q6: Do FR series products contain halogens?
Short Answer: No.
Detailed Answer: They contain no PBB, PBDE, chlorine, fluorine or antimony trioxide – truly halogen free flame retardant products.

Q7: Does FR99RP affect vulcanisation speed?
Short Answer: Less than FR98RP.
Detailed Answer: In EPDM 70 Shore A, TC90 for FR99RP100 is 112 s vs 221 s for FR98RP100 – less interference, higher productivity.

Q8: How is the heat aging performance of FR99RP?
Short Answer: Excellent.
Detailed Answer: After 100℃×70h, hardness change only +3 points, tensile change 3.54%, elongation change 18.31%, all far better than FR98RP – a genuine rubber flame retardant with low heat aging degradation.

Q9: What is the compression set of FR99RP?
Short Answer: 31.43% (120℃×24h).
Detailed Answer: In EPDM 70 Shore A, FR99RP100 gives 31.43% vs FR98RP100’s 52.94% – significantly longer seal life.

Q10: Does FR76RP provide antidrip in silicone sealants?
Short Answer: Yes.
Detailed Answer: FR76RP forms a viscous crust upon heating with antidrip properties, preventing secondary fires from molten drips – a key feature for a silicone sealant flame retardant.

Q11: What is the storage stability of FR99RP?
Short Answer: 2year shelf life.
Detailed Answer: Store in dry, cool, sealed conditions (approx. 25℃); shelf life about 2 years.

Q12: Are FR series products UL certified?
Short Answer: Mature EPDM formulations containing FR series have passed UL certification.
Detailed Answer: SaneZen Group’s mature EPDM formulations with GreenThinking® FR series have obtained UL certification.

Q13: How is the processability of FR99RP?
Short Answer: Excellent.
Detailed Answer: Surfaceactivated fine particles give good dispersion, good flow, stable dimensions, easy extrusion, low mixing energy, and shorter cure times.

Q14: Is FR76RP suitable for coloured silicone sealants?
Short Answer: Evaluation recommended.
Detailed Answer: FR76RP has brightness (L*) >92.5, light colour; minimal impact on light shades, negligible on dark systems. Colour matching tests are advised.

Q15: How does FR99RP compare to FR98RP in NBR?
Short Answer: FR99RP gives better resilience.
Detailed Answer: In NBR, FR99RP resilience 33% vs FR98RP 24%, and higher crosslink density (MHML 12.53 vs 8.45 lbf·in) – more advantageous for dynamic sealing applications.

Q16: What are the physical and chemical specifications of FR76RP?
Short Answer: D50 12 μm, density 2.35 g/cm³, BET 15 m²/g.
Detailed Answer: Typical properties: residue <0.22% (10μm wet sieve), density 2.35 g/cm³, brightness L*>92.5, pH 9.8, moisture <1.0%, BET 15 m²/g, oil absorption 25 ml/100g, MgO equivalent 39.

Q17: Is FR99RP suitable for CR (chloroprene rubber)?
Short Answer: Yes.
Detailed Answer: FR99RP can be used in CR and other polar rubbers; smallscale trials are recommended.

Q18: Does FR76RP comply with GB/T 242672009?
Short Answer: Yes.
Detailed Answer: FR76RP in silicone sealants meets GB/T 242672009 “Flame retardant sealants for building”.

Q19: How does FR99RP affect compound hardness?
Short Answer: Approximately 1 Shore A per 68 phr.
Detailed Answer: Adding 68 phr increases hardness by about 1 Shore A, depending on the base formulation.

Q20: How can I obtain samples and technical support?
Short Answer: Contact SaneZen Group.
Detailed Answer: Technical data sheets, samples and formulation support are available through the SaneZen Group official website or regional sales representatives.

Key Takeaways

• FR99RP is a newgeneration phosphorusnitrogen intumescent halogen free flame retardant that achieves UL94 V0 in EPDM, NBR and other rubbers, while delivering superior tensile strength, heat aging resistance, compression set and resilience compared to FR98RP – it is the rubber chemical to achieve V0 flammability without property loss.
• Comparative data show FR99RP has 46.8% higher tensile strength, 49.3% shorter cure time, 68.5% lower compression set and 21% higher resilience than FR98RP – trading some LOI for comprehensive performance balance.
• FR76RP is a dedicated silicone sealant flame retardant with ultrafine particle size (D50 12 μm), excellent dispersion and antidrip properties; about 50% by volume in silicone compounds achieves required flame retardancy.
• FR series are compliant with REACH, RoHS 2.0 and WEEE, free from PBB, PBDE, chlorine, fluorine and antimony trioxide – backed by a REACH compliant flame retardant supplier.
• Selection advice: organic rubbers → FR99RP; silicone sealants/silicone rubber → FR76RP; consider FR98RP only when LOI is the sole priority.

Why Work With SaneZenChem?

What Makes SaneZen Different from Other Flame Retardant Suppliers?

Choosing a functional filler supplier is not merely about purchasing a mineral powder. It means selecting a technology partner that understands polymer compounding, physical failure mechanisms, and longterm product performance.

SaneZen (SaneZenChem) is precisely such a partner – we are not only a highperformance halogen free flame retardant factory, but also a specialty chemical supplier with practical compounding experience in rubber and silicone rubber production. We are a rubber flame retardant additive manufacture that produces and validates its own products, a UL94 V0 halogen free flame retardant supplier with proven V0 formulations, and a low smoke flame retardant manufacturer dedicated to realfire safety.

8.1 Dual Identity: We Are Both a Compounder and a Flame Retardant Manufacturer

SaneZen operates five major manufacturing divisions:

• Rubber compounds
• Silicone rubber compounds
• Specialty functional fillers
• Highefficiency environmentally friendly flame retardants
• Polymer performance additives

What Does This Dual Identity Mean for You?

Because SaneZen itself continuously produces and develops rubber and silicone rubber products, our flame retardant products – including the GreenThinking® FR series – originate from solving real production issues, rather than remaining merely at the laboratory concept stage.

This applicationdriven R&D approach enables us to develop practical solutions that deliver measurable improvements in customer products – from eliminating viscosity spikes during processing and preventing microcrack formation, to ensuring high dielectric strength in demanding electrical environments.

8.3 FR Series  – Born from Production Practice

The development of FR series was no accident. During SaneZen’s own rubber compounding production, the R&D team had long faced a core challenge: how to enable EPDM, NBR, and other rubber products to consistently achieve a UL94 V0 flame retardant rating without sacrificing processing efficiency and mechanical properties?

Conventional halogenfree flame retardant solutions typically meant:

• Substantially higher mixing energy consumption
• Significantly prolonged curing times
• Drastic reductions in tensile strength and rebound resilience
• Rough product surfaces and unstable dimensions
• High batchtobatch performance variability

It was precisely these real, frontline, persistent production pain points that drove the R&D direction of FR series  – not pursuing excellence in a single metric (such as LOI value), but rather pursuing optimal balance of overall performance.

Contact

Plant Address:
Baishou Road, North District of Xuan Zhou Economic Development Zone
Xuan Cheng City, Anhui Province, China

Commercial Address:
Room 503, Building 1, Huixin International Edifice, No. 150 Puhuitang Road, Xuhui District, Shanghai, China 200030

Tel: +86 21 6487 9251

Email: yorichen@sanezen.com / kevenwang@sanezen.com

Website: www.sanezenrubber.com