Clarifying Agents for Plastics (Clarifiers): 3 Types, Mechanisms, Dosage and Selection

Clarifying agents are nucleating agents that force polypropylene to crystallize into structures smaller than the wavelength of visible light, so the part stops scattering light and turns from milky to see-through. Three chemical types do this at very different loadings, from the 3,000 to 4,000 ppm that earlier clarifier generations needed for ultra-clear polypropylene down to 150 to 200 ppm for a trisamide, so which type belongs in which polypropylene grade?

The 3 types are sorbitol and nonitol acetals, led by DMDBS (Millad 3988) and Millad NX 8000 at 0.2 to 1 wt%; trisamides, represented by Irgaclear XT 386 at 150 to 200 ppm; and organophosphate metal salts such as ADK STAB NA-21. All three are used almost exclusively in polypropylene, because polypropylene is the large-volume polymer whose haze comes from crystalline superstructures that a clarifier can shrink.

This reference covers what a clarifying agent is and how it differs from a plain nucleating agent, why polypropylene is hazy, the 4-step dissolution and self-assembly mechanism, the 3 chemical types with CAS numbers, which polymers can be clarified and which are only nucleated, dosage in ppm and wt% against the US and EU legal ceilings, a 6-step selection route, the interactions with acid scavengers and pigments, how haze and crystallization temperature are measured, the FDA and EU food-contact positions, the producers behind the trade names, and all 9 clarifier substances in the directory.

The table below compares the 3 types of clarifying agents by chemistry, example grades, typical loading, host polymers and the food-contact route each type travels.

ADEKA's ADK TRANSPAREX (2025) is a fourth, commercially launched clarifier whose chemistry the producer does not disclose; it is therefore not counted as a type here.

What Is a Clarifying Agent in Plastics?#

A clarifying agent is a plastic additive that multiplies the number of crystal nuclei in a semi-crystalline polymer until its crystalline superstructures are smaller than the wavelength of visible light, which lowers haze and raises see-through clarity. Haze is the share of transmitted light scattered by more than 2.5 degrees, measured under ASTM D1003-21, so a clarifier is judged by an optical number rather than by an impression. Why then do clear polycarbonate and PMMA parts need no clarifier at all? Amorphous polymers have no crystalline superstructure to scatter light, so there is nothing for a clarifier to refine.

Clarifiers are one of the 43 families of plastic additives on this site, and they sit in the property-modifier group beside the nucleating agents from which they descend. The term has a hard boundary in two directions. It applies only to semi-crystalline polymers, which in practice means polypropylene and a few polyethylene grades, and it means something entirely different outside plastics, where a clarifying agent is a flocculant or fining agent used on wine, beer, juice and water.

Clarifying agent vs nucleating agent: what is the difference?#

Every clarifying agent is a nucleating agent, but only a clarifier reaches the nucleus density at which crystalline superstructures fall below the wavelength of light: talc and sodium benzoate raise the crystallization temperature of polypropylene without making it clear. The separation is physical rather than commercial. A clarifier dissolves in the melt above a dissolution temperature and rebuilds on cooling as a nanofibrillar network, while a particulate nucleator such as talc, sodium benzoate or a phosphate salt stays dispersed as solid particles and nucleates on its own surface.

That difference decides what each additive is bought for. Particulate nucleators raise stiffness, heat deflection temperature and crystallization temperature, and talc raises haze rather than lowering it, so the wider family of nucleating agents covers talc, sodium benzoate and the Hyperform grades as well. Efficiency in both groups is read on one scale: on the self-nucleation efficiency scale published by Fillon, Lotz, Thierry and Wittmann in the Journal of Polymer Science Part B in 1993, the best commercial polypropylene nucleators rate at 60 to 70 percent.

Why Is Polypropylene Hazy, and Can It Be Made Clear?#

Polypropylene is hazy because it crystallizes into spherulites that are larger than the wavelength of visible light and scatter it, and a clarifying agent makes the same polymer see-through by replacing those spherulites with crystallites too small to scatter. Visible light runs from roughly 400 to 700 nm, and unmodified isotactic polypropylene builds superstructures well above that size as it cools, which is why a moulded homopolymer cup looks milky.

The polymer is unusually open to that intervention. Gahleitner and colleagues at Borealis described isotactic polypropylene in International Polymer Processing in 2011 as combining slow crystal growth at large undercooling with almost no spontaneous nucleation, which makes it an ideal material for controlled nucleation: each spherulite is larger than the wavelength it scatters, and nothing in the neat polymer stops the structures from growing that large. Clarified polypropylene is the commercial answer, and Milliken states that it is used in more than 22 markets.

How do clarifying agents reduce haze?#

A clarifying agent works in 4 steps: it dissolves in the polypropylene melt, separates out again as the melt cools, crystallizes into a network of nanofibrils, and lets polypropylene grow on those fibrils at a nucleus density high enough to stop light scattering. The 4 steps below happen in that order between the barrel and the mould.

1. Dissolve the clarifier in the melt above its dissolution temperature, which for traditional sorbitol grades is about 220 °C.
2. Cool the melt, which drives the dissolved clarifier back out of solution by phase separation.
3. Crystallize the separated clarifier into a nanofibrillar network whose fibril surface becomes the nucleation site.
4. Nucleate the polypropylene epitaxially on those fibril surfaces, which builds shish-kebab-like structures instead of spherulites.

Marc Kristiansen, Theo Tervoort and Paul Smith at ETH Zürich mapped this behaviour as a monotectic phase diagram for DMDBS in isotactic polypropylene (Macromolecules, 2003), and the solubility of the clarifier caps the whole type: Horváth, Menyhárd and colleagues at BME Budapest reported in RSC Advances in 2014 that sorbitol clarifiers dissolve in polypropylene only to a few thousand ppm, with the Flory-Huggins interaction parameter correlating with the lowest achievable haze. Trisamides reach the same nucleus density by a second route, because they hydrogen-bond into columnar fibrils at 200 ppm (Blomenhofer and colleagues, Macromolecules, 2005). The underlying kinetics are on polymer crystallization and nucleation.

What changes besides clarity: crystallization temperature, cycle time and stiffness#

A clarifier changes 5 properties at once: haze falls, the crystallization temperature rises, the moulding cycle shortens, stiffness and heat deflection temperature rise, and shrinkage becomes more isotropic. Each of those 5 effects follows from the same nucleus density that removes the haze, and each is listed below with the evidence attached to it.

• Haze and clarity: the headline effect, measured as scattered transmitted light under ASTM D1003-21 at a stated wall thickness.
• Crystallization temperature: nucleation shifts the crystallization exotherm to a higher temperature on cooling, which is the fastest screening measurement for any nucleator.
• Cycle time and energy: Milliken reports a cycle-time reduction of more than 10 percent and about 15 percent energy saving for Millad NX 8000 against conventional clarifiers, and a 10 percent average energy saving for Millad NX 8000 ECO under a UL Environmental Claim Validation.
• Stiffness and heat resistance: higher crystallinity raises flexural modulus and heat deflection temperature, and ADEKA reports that 0.1 wt% of its NA-27 nucleator lets a polypropylene part be 10 percent thinner at equal load.
• Shrinkage: crystallization on a dense nucleus population shrinks more evenly in the flow and cross-flow directions, which takes warpage out of thin-wall parts.

Stiffness is also where the trade-off sits, because the opposite design choice, toughness instead of stiffness, is made with beta nucleating agents, which raise impact strength and give up modulus.

3 Types of Clarifying Agents for Plastics#

The 3 types of clarifying agents used in plastics are sorbitol and nonitol acetals, trisamides, and organophosphate metal salts, and all three are used almost exclusively in polypropylene. The order runs from the oldest and highest-volume chemistry to the newest and lowest-dosed, and every table, list and image on this page keeps it.

1. Sorbitol and nonitol acetals (DBS, MDBS, EDBS, DMDBS, Millad NX 8000)#

Sorbitol and nonitol acetals are melt-soluble acetals of sorbitol or nonitol, such as DMDBS (Millad 3988, CAS 135861-56-2) and Millad NX 8000 (CAS 882073-43-0), and they are the clarifier type with the longest commercial record and the only one with named entries in 21 CFR 178.3295. All five grades work by the same dissolution and fibril-network route, and they differ in the substituent on the benzylidene ring, which sets the dissolution temperature and the effective loading.

The type spans four generations in one chemical line. DBS carries no ring substituent, MDBS carries one methyl group, DMDBS carries two, and Millad NX 8000 moves from a sorbitol to a nonitol backbone with propylphenyl substituents, which lowers the dissolution temperature and widens the processing window according to Milliken. The 5 grades and their identities are listed below.

• DBS, 1,3:2,4-dibenzylidene sorbitol, CAS 32647-67-9, melting point 224 °C, cleared under 21 CFR 178.3295 at up to 0.25 wt% for conditions of use C to G, with a purity of at least 95 percent DBS.
• MDBS, 1,3:2,4-bis(4-methylbenzylidene)sorbitol, CAS 81541-12-0, sold as Gel All MD by New Japan Chemical, cleared at up to 0.32 wt%.
• EDBS, bis(4-ethylbenzylidene)sorbitol, CAS 79072-96-1, cleared at up to 0.35 wt% under 21 CFR 178.3295 and at up to 0.2 wt% in LLDPE and LDPE under FCN 509, held by Ampacet.
• DMDBS, 1,3:2,4-bis(3,4-dimethylbenzylidene)sorbitol, CAS 135861-56-2, EC 413-110-2, sold as Millad 3988, effective at 0.2 to 1 wt% and cleared at up to 0.4 wt% in polymers with at least 85 percent propylene units, conditions A to H.
• Millad NX 8000, a nonitol acetal, CAS 882073-43-0, the subject of FCN 825 at up to 0.5 wt% for films and moulded articles, and FCM 808 in the EU with a specific migration limit of 5 mg/kg including the sum of its hydrolysis products.

Clarifier generations: from 3,000 ppm sorbitol to 200 ppm trisamide#

Clarifier loading has fallen by more than an order of magnitude across 4 generations: ultra-clear polypropylene once needed 3,000 to 4,000 ppm of sorbitol clarifier, while a benzenetrisamide clarifies the same polymer at 200 ppm. Blomenhofer and colleagues put that lower bound at a weight fraction of 0.0002 in Macromolecules in 2005, and Ciba set the commercial recommendation for Irgaclear XT 386 at 150 to 200 ppm in 2008.

The two newest grades are not counted as a generation here, because their chemistry is unpublished. Milliken does not disclose the chemistry of Millad ClearX 9000 and positions it below the earlier 3,000 to 4,000 ppm ultra-clear level, with 17 times less migration into olive oil normalised against the market-leading clarifier. ADEKA reports 2.2 percent haze at 1 mm wall thickness for ADK TRANSPAREX against a market low of 3.2 percent, third-party verified, and states that the product holds a Guinness World Records title from 2025.

2. Trisamide clarifiers (Irgaclear XT 386, RiKACLEAR PC1)#

Trisamide clarifiers are 1,3,5-benzenetrisamides and aliphatic trisamides, such as Irgaclear XT 386 (CAS 745070-61-5), that hydrogen-bond into columnar nanofibrils and clarify polypropylene at 150 to 200 ppm, roughly one twentieth of a sorbitol loading. Irgaclear XT 386 is 1,3,5-tris(2,2-dimethylpropionylamino)benzene, supplied by BASF from the former Ciba portfolio. It is the subject of FCN 824, effective 11 September 2008, for use at up to 250 ppm with all food types under conditions of use A to H, and it carries FCM 784 in the EU with a specific migration limit of 5 mg/kg. In the aggregated CLP notifications the substance is not classified in 105 of 105 reports.

Small changes in the amide substituent decide what the fibril nucleates. Blomenhofer, Schmidt and Kreger at the University of Bayreuth, working with Ciba and ETH Zürich, showed in Macromolecules in 2005 that a benzenetrisamide can be switched between alpha, beta and mixed nucleation of isotactic polypropylene by structural design alone. The second commercial trisamide is aliphatic rather than aromatic: N,N',N''-tris(2-methylcyclohexyl)-1,2,3-propanetricarboxamide, CAS 160535-46-6, supplied by New Japan Chemical under the RiKACLEAR name, with the trade name to be confirmed. It is the subject of FCN 860 at up to 0.25 wt% for all foods under conditions A to H, carries FCM 870 with a specific migration limit of 5 mg/kg, and is subject to the TSCA significant new use rule at 40 CFR 721.10695. Trisamides also nucleate foam cells, a separate use studied at 0.1 to 0.5 wt% in extruded polystyrene by Aksit and colleagues in 2019.

3. Organophosphate salt clarifiers (NA-21, NA-71)#

Organophosphate salt clarifiers are aryl phosphate metal salts such as NA-21 (main component CAS 151841-65-5), which stay particulate in the melt instead of dissolving and combine clarity with the stiffness and heat resistance of a classic nucleator. ADK STAB NA-21 from ADEKA is hydroxy aluminium bis[2,2'-methylenebis(4,6-di-tert-butylphenyl) phosphate] blended with a lithium fatty-acid salt, and Lin and colleagues showed in 2022 that the lithium component is essential for activity. ADK STAB NA-71 is the ADEKA clarifier grade for low-melt-flow polypropylene, with a melting point above 210 °C.

This is the only clarifier type with a harmonised EU hazard classification: the NA-21 main component is classified Aquatic Chronic 2, H411 under CLP Annex VI index 013-010-00-5, while no clarifying agent in the family appears on the REACH Candidate List, in Annex XIV or in Annex XVII. The food-contact position is split between two instruments. The aluminium salt is cleared under 21 CFR 178.3295 at up to 0.25 wt%, and FCN 202 allows up to 0.18 wt% for fatty and alcoholic foods under conditions B to H. In the EU it is FCM 771 with a specific migration limit of 5 mg/kg, and the Annex II metal limits apply to the cations: lithium 0.6 mg/kg and aluminium 1 mg/kg. The closely related nucleator NA-11, CAS 85209-91-2, clarifies as well, with FDA caps of 0.30 wt% and 0.10 wt% and FCM 749 with a 5 mg/kg limit, but it is filed on this site under the nucleating agents.

Which Plastics Can Be Clarified?#

Clarifying agents work in polypropylene first, in random copolymer grades best of all, in polyethylene only for selected grades, and not at all in amorphous plastics such as polycarbonate, PMMA and polystyrene, which have no light-scattering crystal structure to refine. The criterion is the one from the definition: the polymer must crystallize into superstructures that a higher nucleus density can shrink below the wavelength of visible light.

The FDA clearances draw the same line in legal language, because they name olefin polymers with at least 85 percent propylene units, which covers polypropylene homopolymer and random copolymer. Random copolymer is the dominant base for clarified polypropylene, since its comonomer content already disturbs crystallization and leaves less haze to remove. Polyethylene is a limited case, with EDBS cleared at up to 0.2 wt% in LLDPE and LDPE under FCN 509. PET and polylactic acid crystallize too slowly to be clarified at all and are nucleated instead, with a different chemistry set of sodium salts, LAK-301, orotic acid and talc.

Clarity is one property in a polypropylene formulation that also carries antioxidants, acid scavengers and slip additives, and the rest of the PP package is on additives for polypropylene.

How Much Clarifying Agent Does Polypropylene Need? Dosage in ppm and wt%#

Clarifier dosage in polypropylene runs from 150 ppm for a trisamide to 1 wt% (10,000 ppm) for a sorbitol acetal, and the effective range for DMDBS, the most-used grade, is 0.2 to 1 wt%. The unit convention is worth fixing before any comparison, because 1,000 ppm equals 0.1 wt% of the compound, and supplier literature moves between the two without warning. A patent example gives the practical middle of that range: US 8,232,335 B2 uses Millad 3988 at 2,000 ppm, that is 0.2 wt%, in an 11 MFR random copolymer.

Regulatory ceilings are a separate column and never a recommendation. The FDA caps in the table below are maximum use levels for food-contact conditions, and a formulator who reads 0.4 wt% for DMDBS as a target dose is running at twice the low end of the effective window and paying for it.

FDA caps are maximum use levels for food-contact conditions, not recommended dosages. An FCN is effective only for its notifier and that notifier's customers.

Cost follows loading directly at these levels, and ppm can be converted to cost per tonne with the additive dosage and cost-in-use calculator.

Why more clarifier does not mean more clarity#

Adding more clarifier stops helping above about 1 wt%: in DMDBS the optics deteriorate beyond that level, and above 2 wt% the clarifier and the polypropylene separate into two liquid phases. Kristiansen and colleagues at ETH Zürich established both boundaries in Macromolecules in 2003, in the same monotectic phase diagram that fixes the 0.2 to 1 wt% effective window, and the maximum gain in crystallization temperature sits inside that window rather than above it.

The ceiling is a solubility ceiling. Horváth, Menyhárd and colleagues at BME Budapest reported in RSC Advances in 2014 that sorbitol clarifiers dissolve in polypropylene only to a few thousand ppm, and that the Flory-Huggins interaction parameter between clarifier and polymer correlates with the lowest haze the pair can reach. Undissolved clarifier does not build fibrils, so it adds cost, contributes nothing to nucleus density and becomes a second scattering population in the part.

Dissolution temperature, masterbatch and dosing practice#

A clarifier only works if the melt gets hot enough to dissolve it: traditional sorbitol grades need about 220 °C, and polypropylene moulded below the dissolution temperature comes out stiffer but not clearer. Iwasaki and colleagues measured the dissolution temperature of MDBS at 0.4 wt% in a polypropylene melt at about 210 °C in 2020 and showed that moulding below it raises orientation and modulus without delivering clarity. Millad NX 8000 dissolves at lower melt temperatures, which is why Milliken attributes about 15 percent energy saving to the grade against conventional clarifiers: the processing window opens downwards.

Getting 200 ppm of anything into a polypropylene melt accurately is the second practical problem, and the 3 dosing routes are listed below.

• Additive masterbatch: the standard route, because gravimetric accuracy at ppm level is difficult on neat powder, and most converters dose clarifiers as additive masterbatch rather than powder.
• One-pack blends: the clarifier is supplied pre-mixed with the antioxidant and acid-scavenger package, which removes one weighing step and fixes the ratio between components.
• Clarified resin: the polymer producer compounds the clarifier into the grade, so the converter buys a clarified polypropylene rather than a clarifier.

How Do You Select a Clarifying Agent? 6 Steps#

Select a clarifying agent in 6 steps: confirm the polymer can be clarified, set the haze target at a stated thickness, check the melt temperature against the dissolution temperature, choose the type by loading and cost-in-use, screen the food-contact route in each market, then check additive interactions and test. The sequence is ordered so that the cheapest disqualifying question is asked first.

1. Confirm the polymer is clarifiable: polypropylene homopolymer or random copolymer with at least 85 percent propylene units, which is also the wording the FDA clearances use.
2. Set the haze target together with the wall thickness it is measured at, because haze is thickness-dependent and a percentage without a thickness cannot be checked.
3. Check the melt temperature of the process against the clarifier's dissolution temperature: about 220 °C for traditional sorbitol grades, about 210 °C for MDBS at 0.4 wt%, lower for Millad NX 8000.
4. Choose the type by loading and cost-in-use: a sorbitol acetal at 0.2 to 1 wt%, a trisamide at 150 to 200 ppm, a phosphate salt at up to 0.25 wt%.
5. Screen the food-contact route in every target market: an entry in 21 CFR 178.3295, an FCN held by that supplier, or an EU FCM number with its specific migration limit.
6. Check the rest of the additive package for antagonism, then confirm haze and crystallization temperature by test on moulded parts, not on pellets.

Step 5 is where the supplier and the substance stop being separable, because a notification is company-specific, and step 6 should be run before a grade is written into a specification. The general framework behind these steps is on how to select plastic additives.

How Do Clarifiers Interact with Other Additives?#

A clarifier never acts alone: acid scavengers, pigments, antiblock and slip additives all change the haze and the crystallization behaviour of the same compound. Simanke and colleagues recorded a negative interaction between calcium stearate and sodium benzoate at 1,000 to 2,200 ppm in 2016, which is why hydrotalcite or zinc stearate is the preferred neutralizer where a salt-type nucleator is present. Colorants are the second reliable source of trouble, because pigments nucleate polypropylene on their own account: shrinkage in the flow direction rose from 13.6 percent to 22.3 percent across 1 to 5 wt% of a transparent phthalocyanine masterbatch.

Kisuma's Setogem RD, launched in 2025, combines nucleation and acid scavenging in one zinc-free product for polypropylene at 200 to 300 ppm, which removes the calcium stearate question at source. The full synergy and antagonism matrix is on additive interactions.

How Are Haze, Clarity and Nucleation Measured?#

Clarifier performance is measured with 3 tests: haze and luminous transmittance to ASTM D1003-21, narrow-angle clarity, and the crystallization temperature from a DSC cooling scan to ISO 11357-3. Haze is the share of transmitted light scattered by more than 2.5 degrees, and clarity is the narrow-angle scattering below that same 2.5 degree boundary, so the two numbers describe opposite halves of one measurement. Every haze value needs the wall thickness it was measured at, because haze rises with thickness and a bare percentage cannot be compared: ADEKA's 2.2 percent for ADK TRANSPAREX is a value at 1 mm, against a market low of 3.2 percent at the same thickness.

Procedure A of ASTM D1003-21 uses a hazemeter and procedure B a spectrophotometer, and the standard notes that procedure A values run slightly higher and vary less. ASTM D1003 is not equivalent to ISO 13468-1 or ISO 14782, so a haze figure quoted without its method is not a comparable number, and every method used on this site is indexed under testing plastic additives.

How Are Clarifying Agents Regulated?#

Clarifying agents are regulated in 3 layers: chemical registration under REACH and TSCA, food-contact clearance (21 CFR 178.3295 or a Food Contact Notification in the US, the Union list of Regulation (EU) No 10/2011 in the EU), and hazard classification under CLP. The three layers answer different questions, and passing one says nothing about the others: all instruments are summarised in plastic additive regulations.

The chemical layer is quiet for this family. No clarifying agent appears on the SVHC Candidate List, in REACH Annex XIV or in Annex XVII, and none is listed under California Proposition 65. Under CLP only one entry exists: the NA-21 main component carries the harmonised classification Aquatic Chronic 2, H411 at Annex VI index 013-010-00-5. The food-contact layer is where the real constraints sit, and it splits cleanly between the EU and the United States.

EU food contact: Regulation (EU) No 10/2011 FCM numbers and SMLs#

In the EU every clarifying agent must appear on the Union list of Regulation (EU) No 10/2011 before it may be used in food-contact plastics, and the newer grades carry a specific migration limit of 5 mg/kg. The four sorbitol acetals were listed without an individual limit, so only the generic limits apply to them: the 60 mg/kg default and the overall migration limit of 10 mg/dm². The four grades listed since the 2000s each carry 5 mg/kg. Where the substance is a metal salt, the Annex II metal limits apply on top of the substance limit, and the Union list and its limits are explained on EU 10/2011.

US food contact: 21 CFR 178.3295 and Food Contact Notifications#

In the United States a clarifying agent is cleared either by 21 CFR 178.3295, which lists 8 clarifying agents for polymers with their maximum use levels, or by a Food Contact Notification that is effective only for the company that filed it. The regulation carries the older chemistries, including sodium di(p-tert-butylphenyl)phosphate at up to 0.35 phr and polyvinylcyclohexane at up to 0.1 wt% of the polyolefin alongside the sorbitol acetals. Everything cleared since the late 1990s travels the notification route instead, and the 21 CFR sections are mapped on FDA food contact rules. The clarifier notifications on the FDA inventory are listed below.

• FCN 509 (Ampacet, 2005): EDBS at up to 0.2 wt% in LLDPE and LDPE, conditions of use C to G.
• FCN 824 (11 September 2008): Irgaclear XT 386 at up to 250 ppm, all foods, conditions A to H.
• FCN 825 (28 August 2008): Millad NX 8000 at up to 0.5 wt% in films and moulded articles, all foods, conditions A to H.
• FCN 860 (New Japan Chemical, 2009): the aliphatic trisamide CAS 160535-46-6 at up to 0.25 wt%, all foods, conditions A to H.
• FCN 2344 (15 June 2024): an ADEKA biphenol, cyclohexylphenol and triazine reaction product at up to 0.15 wt% in polypropylene.
• FCN 2440 (31 July 2025): a Milliken trisamide at up to 0.08 wt%, conditions A to H and J, including repeat-use baby bottles.

Who Makes Clarifying Agents? Suppliers, Trade Names and Capacity#

Four companies supply most of the world's polypropylene clarifiers: Milliken (Millad), ADEKA (ADK STAB NA and TRANSPAREX), BASF (Irgaclear) and New Japan Chemical (Gel All, RiKACLEAR). Two more companies matter for the food-contact route rather than the chemistry: Ampacet holds FCN 509 for EDBS and supplies the masterbatch route, and Amfine distributes ADEKA grades in the United States. No independent market size for clarifying agents is published in our sources, because the family sits inside the nucleating-agent segment, and the full buyer directory is nucleating and clarifying agent suppliers.

Company profiles are in the directory of plastic additive manufacturers and suppliers.

Complete List of Clarifying Agent Substances (9 Pages)#

The 9 clarifying agents documented on this site are listed below with their CAS number, chemical class, typical level, US ceiling and EU food-contact status, in the order of the 3 types. Each substance name is the single entry point to that substance's own page, where identity data, dosage evidence and regulatory history sit in full.

All 435 substance pages sit in the plastic additives database, where each clarifier is cross-linked to its polymer, test and regulation pages.

Are Clarifiers Safe for Food Contact, Recycling and the Environment?#

No clarifying agent is a substance of very high concern, restricted under REACH or listed under Proposition 65, and the only harmonised hazard classification in the family is the aquatic-toxicity entry for the NA-21 main component. DMDBS, MDBS, Millad NX 8000 and Irgaclear XT 386 are reported as not classified in the great majority of CLP notifications, and Irgaclear XT 386 is not classified in all 105 of its 105 notifications. The open questions for this family are therefore not hazard questions but exposure and end-of-life questions: how much of the additive leaves the part into food, and what happens to a clarified polypropylene when it is recycled.

Do clarifying agents migrate out of polypropylene?#

Yes, clarifiers can migrate, which is why the newer grades carry a specific migration limit of 5 mg/kg in the EU and a maximum use level in the US rather than a free-use clearance. Migration is controlled by two EU numbers at once: the substance-specific limit in the Union list of Regulation (EU) No 10/2011, and the overall migration limit of 10 mg/dm² that applies to everything leaving the material. For Millad NX 8000 the 5 mg/kg limit is written to include the sum of its hydrolysis products, which is the regulator's answer to an acetal that can split in an acidic simulant.

Measured migration values are not published for most grades, and only one comparative figure exists: Milliken reports 17 times less migration into olive oil for Millad ClearX 9000, normalised against the market-leading clarifier. Simulants, contact times and temperatures for these tests are set out on migration testing, and a compliance file needs the tested article rather than the additive alone.

Do clarifiers affect polypropylene recycling?#

Clarifiers do not block polypropylene recycling: the Association of Plastic Recyclers rates nucleating agents among the workhorse additives that are design-preferred for rigid polypropylene. The additive is present at hundreds to thousands of ppm and does not change the polymer backbone, so it does not interfere with washing, sorting or re-extrusion the way an incompatible barrier layer or a dark pigment does.

Two supplier claims go further. Milliken states that clarifiers are used in post-consumer recycled polypropylene, and that Millad ClearX 9000 reduces the need to segregate recycled polypropylene streams, which is a sorting-cost argument rather than a technical-property argument. Milliken also states that Millad NX 8000 ECO is RecyClass-certified and recognised by the Association of Plastic Recyclers. Restabilisation and nucleation of recyclate are covered on nucleating agents for recycled plastics.

A short history of polypropylene clarifiers#

Polypropylene clarifiers are about 45 years old as a product class, and the science caught up in 2003, when the DMDBS phase diagram explained why the effect peaks between 0.2 and 1 wt%. Milliken states that it invented polypropylene clarifying agents nearly 45 years ago, which places the first commercial sorbitol acetals in the early 1980s, a full generation before the mechanism was mapped.

The dated milestones since then are close together. Kristiansen, Tervoort and Smith published the DMDBS phase diagram in Macromolecules in 2003. Blomenhofer and Schmidt at the University of Bayreuth, with Ciba and ETH Zürich, published designer trisamides in the same journal in 2005. FCN 824 cleared Irgaclear XT 386 and FCN 825 cleared Millad NX 8000 in 2008. ADEKA announced its ADK TRANSPAREX clarifier plant in South Korea on 25 August 2026.

Is a plastics clarifier the same as a wine, water or pool clarifier?#

No: a clarifying agent for wine, juice or pool water is a flocculant that pulls suspended particles out of a liquid, while a clarifying agent for plastics is a nucleating additive that changes how a polymer crystallizes. The two share a name and nothing else, since one removes matter from a liquid and the other rearranges the crystal structure of a solid without removing anything.

Can polypropylene be made clear without a clarifying agent?#

Partly: a random copolymer grade, a thin wall and fast cooling all lower haze, but only a clarifying agent brings moulded polypropylene close to the look of an amorphous plastic. Switching to polycarbonate, PMMA or polystyrene removes the problem rather than solving it, because those polymers are amorphous and never had a crystalline superstructure to scatter light in the first place.