Precipitated Calcium Carbonate (PCC): Properties, Uses in Plastics and Regulatory Status

Precipitated calcium carbonate (PCC, CAS 471-34-1) is synthetic calcium carbonate, made by carbonation instead of by grinding rock, and in plastics it works as a fine-particle filler that raises stiffness and opacity and acts as an impact co-modifier in rigid PVC. Because the particle is grown in a reactor rather than milled out of limestone, the practical question is not what PCC is made of, but when a compounder pays for it instead of using ground calcium carbonate (GCC).

Calcium carbonate is authorised for EU food-contact plastics as FCM substance 21 with no specific migration limit, is not on the REACH Candidate List, and carries no harmonised classification under the CLP Regulation, Regulation (EC) No 1272/2008. PCC is one of the filler entries in our database of plastic additives, each carrying the same identity, loading and regulatory fields.

This page holds the particle view and the compliance view together: the identity that separates a precipitated grade from a ground one, the carbonation route, the nanoscale boundary, the measured constants, the loading recorded for PVC, polypropylene and polyethylene, the 4 plastics applications, the dated matrix across REACH, EU 10/2011, 21 CFR and Proposition 65, the comparison against six alternative fillers, and the producers a buyer can approach.

Table T1. PCC identity card.

Footnote: identity and physical data from PubChem CID 10112; regulatory entries from ECHA CHEM, the EU 10/2011 consolidation and the 21 CFR sections cited in each section. Status as of 22 September 2026.

What Is Precipitated Calcium Carbonate (PCC)?#

PCC is calcium carbonate (CaCO3, CAS 471-34-1, EC 207-439-9) precipitated from solution in a plant rather than ground from limestone, marble or chalk, so its particle size and crystal habit are set by the process and not by the rock. The substance is a synthetic carbonate filler with a molecular weight of 100.09 g/mol, and its job in a polymer is to occupy volume, raise stiffness and opacity and, in the finest coated grades, co-modify impact in rigid PVC. What does a process-controlled particle give a compounder that a milled particle cannot? A narrower size distribution and a chosen crystal habit at a size the mill cannot reach, which is why PCC sits at the fine end of the carbonate range, from 0.02 to 30 micrometres mean size.

Ground grades carry the same identity, EC 207-439-9, while ground limestone also carries the separate CAS number 1317-65-3, so a certificate of analysis is read for its process description as well as its assay. As a particulate mineral additive, PCC belongs to the largest additive family by weight, and the hub on fillers for plastics compares every class by shape, density and function.

How is precipitated calcium carbonate made?#

PCC is made by carbonation: carbon dioxide is passed into a calcium hydroxide suspension, and the calcium carbonate that precipitates is then filtered, dried and classified. The United States Food and Drug Administration names the same routes in its food-additive listing for calcium carbonate, 21 CFR 184.1191, which recognises the lime-soda process, the carbonation process and other processes as manufacturing methods for the substance. Precipitation is therefore a route the regulator itself describes, which is one reason a food-contact user reads the same entry for a precipitated and a ground grade.

Carbonation differs from grinding in what it controls. Grinding reduces a quarried rock until a classifier cuts whatever distribution it produces, while carbonation grows the particle and lets the producer set its size and habit before the powder is dried. Our source library records no reaction temperature, carbon dioxide concentration, residence time or yield for the route, so this page names the steps and publishes no process conditions.

Which crystal forms does PCC take?#

PCC is supplied in two crystal forms: calcite, grown as scalenohedral or rhombohedral particles, and aragonite, which grows as needles. The two habits are the shape record of the precipitation step, and they sit inside the same blocky aspect ratio band of 1 to 3 that the carbonate class carries as a whole. Calcite is also the form behind the optical contribution of the filler, with a refractive index of 1.6584 at 589 nm.

What the habits do to a compound is a separate question from what they are. Our source library records the habits producers supply, not a measured opacity, reinforcement or viscosity difference between them, so no performance difference is stated here.

Is PCC the same as nano calcium carbonate?#

Nano calcium carbonate is one part of the PCC range, not another name for it: a filler counts as a nanofiller only when at least one dimension measures below 100 nm, and PCC mean particle sizes run from 0.02 to 30 micrometres. The fine end of that range, 0.02 micrometres, is 20 nm, so ultrafine PCC grades are nanoforms while standard PCC grades are not. A grade sold as nano calcium carbonate is a size selection out of the same substance, with the same CAS number and the same food-contact entry as a 10 micrometre grade.

The size question is a specification question before it is a legal one. Where the nanoscale boundary sits for a mineral additive is explained under filler particle size and aspect ratio. The boundary changes the paperwork: a nanoform carries extra REACH and food-contact duties, which the regulatory section below sets out against Regulation (EU) 2018/1881 and Article 9(2) of Regulation (EU) No 10/2011.

What does the name tell you that the GCC name does not?#

The word "precipitated" records a manufacturing route, and that route decides the paperwork: PCC is a manufactured substance that needs REACH registration, while ground limestone, which also carries CAS 1317-65-3, is a naturally occurring mineral. Both grades answer to calcium carbonate under EC 207-439-9 and to the same food-contact entry, so the asymmetry is procedural.

REACH Annex V exempts naturally occurring minerals that are not chemically modified, at points 7 and 8, which is why ECHA CHEM shows no active registration dossier for limestone under EC 215-279-6 while calcium carbonate itself carries hundreds. The exemption is conditional rather than a blanket release, and because the exact Annex V wording is not in our source library, this page states the principle and the point numbers without quoting the text.

How Does PCC Work as a Filler in Plastics?#

PCC works as a low-aspect-ratio particulate filler: its blocky particles occupy volume in the polymer, raise the modulus, move heat out of the melt faster and, in fine coated grades, absorb impact energy by debonding from the matrix. A particle with an aspect ratio of 1 to 3 reinforces far less efficiently than a platelet or a fibre, which is why the carbonate class counts as an extender filler and becomes a functional filler only in specific grades.

A PCC particle changes 4 things in a compound, listed below.

• Stiffness rises with the filler volume fraction, following the shape of the particle as much as its amount.
• Impact strength rises for fine coated grades and falls where agglomerates and a coarse top cut act as crack initiators.
• Density rises towards the 2.7 to 2.95 g/cm3 of the mineral, against roughly 0.9 to 1.4 g/cm3 for the common thermoplastics.
• Cycle time falls, because the producer Omya states that polymers filled with calcium carbonate transfer heat more quickly, which increases production line speed.

Whether the particle delivers the stiffness or the agglomerates is decided in the extruder. Dispersion, feed sequence and the lubricant package govern whether a 20 wt% mineral load reaches the die as separated particles or as clusters. The dispersion step is set out on plastic compounding, where the mixing energy a mineral powder needs is compared with that of a liquid additive.

Why a blocky filler raises modulus less than a platy filler#

A blocky PCC particle with an aspect ratio of 1 to 3 raises the modulus of a compound far less than a talc platelet with an aspect ratio of 5 to 40, because the shape factor in the Halpin-Tsai equations rises with aspect ratio (Halpin and Kardos, Polymer Engineering and Science 16 (1976) 344 to 352). The shape factor used in those equations is about 2 times the aspect ratio for aligned fibres and platelets, which is why 20 wt% talc in polypropylene delivers substantially more stiffness than 20 wt% calcium carbonate in the same polymer at the same loading.

A near-spherical particle shrinks the same way in every direction, so a carbonate-filled part warps less and flows better than a platelet-filled or fibre-filled part, and that isotropy is often why a designer accepts the lower modulus. Our source library holds no modulus value in MPa or GPa for a PCC compound, so the model is given here and the number belongs to the grade.

How fine coated PCC toughens polypropylene#

Fine, well-dispersed, stearic-acid-coated calcium carbonate below about 3 micrometres can raise the notched impact strength of polypropylene, because the particles debond from the matrix and the polymer ligaments between the resulting voids then yield (Thio, Argon, Cohen and Weinberg, Polymer 43 (2002) 3661; Zuiderduin, Westzaan, Huetink and Gaymans, Polymer 44 (2003) 261). Debonding and matrix ligament yielding are two steps of one mechanism, and both need a particle that is small, coated and separated.

If fine particles toughen a compound, why does a filled part ever fail at low impact? Agglomerates and the coarse top cut initiate cracks instead of absorbing energy, which is why the d98 of a grade matters more than its d50 for both impact strength and film pinholes. The notched impact strength (Izod, Charpy) test is the one that records the effect, and our source library holds no impact value in kJ/m2 and no percentage improvement for a PCC-filled compound.

What Are the Physical and Chemical Properties of PCC?#

PCC is a white, odorless powder with a density of 2.7 to 2.95 g/cm3, a Mohs hardness of 3 to 4 and a mean particle size between 0.02 and 30 micrometres. The constants a formulator and a purchasing engineer both need are collected in Table T2, with the method or source per row.

Table T2. PCC physical and chemical properties.

Two kinds of number are missing from that table on purpose. Assay, whiteness, bulk density, pH and oil absorption are grade properties that belong on a supplier data sheet, and the figures circulating on trader pages carry no test method, so they are not reproduced here. The specification for calcium carbonate therefore has two parts: the substance properties above, which are fixed, and the grade properties, which a producer measures per product and prints on the certificate.

Particle size, aspect ratio and surface area#

Three particle properties decide how a PCC grade behaves in a compound: the median size d50, the top cut d98 and the specific surface area. Each one is measured by a named method, and each one changes a different part of the compound, as the list below sets out.

• Median size d50, measured by laser diffraction under ISO 13320, which positions the grade between a coarse extender and an ultrafine functional filler.
• Top cut d98, the coarse fraction that initiates cracks in a notched impact test and pinholes in a stretched film.
• Specific surface area, measured by nitrogen adsorption under ISO 9277, which drives coupling-agent and lubricant demand and raises melt viscosity.

Oil absorption is the fourth grade property, measured by ISO 787-5 or ASTM D281, as a proxy for plasticizer uptake in flexible PVC and viscosity in plastisols. The two numbers a data sheet reports for the distribution, d50 and d98, are defined under particle size (d50, top cut). No BET value, no per-grade d50 and no oil absorption value is published here, because our source library records the methods rather than measured values for a precipitated grade.

Coated PCC: why precipitated calcium carbonate is treated with stearic acid#

Coated PCC grades carry a stearic-acid layer on the particle surface, because an untreated carbonate surface is polar and disperses poorly in a polyolefin melt. The treatment also unlocks the toughening mechanism, since the condition recorded in the polypropylene studies is a coated, well-dispersed fine particle rather than a fine particle alone. European window profile runs stearate-coated chalk or marble at 5 to 15 %, a value for calcium carbonate in general.

Silane coupling agents are ineffective on calcium carbonate, which appears on the Gelest silane guide's list of poor substrates beside gypsum, barytes, graphite and carbon black, so a fatty acid is the surface answer rather than a silane. Why every grade of calcium carbonate in plastics is coated with a fatty acid rather than a silane is covered on the mineral's own page, and the coating, stearic acid, is a lubricant in its own right. No coating level in percent is given here, because our source library records none for a PCC grade.

Which Polymers Use PCC, and at What Loading?#

PVC is the largest plastics consumer of calcium carbonate: uPVC drainpipe carries 15 to 20 %, window profile 5 to 15 % of a stearate-coated grade and cable compounds up to 70 phr, while polypropylene compounds often run at 20 to 40 %, all values for calcium carbonate in general, covering both ground and precipitated grades. The PCC-specific entry in our source library is a role rather than a level: in rigid PVC the precipitated grade is specified as a fine filler and an impact co-modifier. How does a phr figure convert to weight percent? Divide the ingredient's phr by the total phr of the whole formulation and multiply by 100, so the 5.00 phr of calcium carbonate in the 108.03 phr pressure-pipe compound published in Plastics Pipe Institute TR-2 (2023) is 4.63 wt%, against 92.57 wt% for the PVC itself.

PVC recipes give filler in PHR (parts per hundred resin), which converts to weight percent only against the full formulation total, and a real recipe also carries stabilizer, lubricant and pigment, so the denominator is larger than resin plus filler. The complete picture for one polymer, including the calcined kaolin and barium sulfate cases, sits on fillers for PVC.

Table T3. Reported calcium carbonate levels by polymer, and what each value covers.

PCC in rigid PVC: pipe and window profile#

In rigid PVC, PCC and nano-PCC are specified as fine fillers and impact co-modifiers rather than as cost extenders, which is the opposite of the role ground calcium carbonate plays in the same compounds. A fine, uniform particle contributes to notched impact and to surface finish in a thin section, where a coarse extender costs both. Window profile uses a stearate-coated grade at 5 to 15 %, again a value for calcium carbonate in general.

A published pressure-pipe recipe shows how little filler a pressure application takes: the Plastics Pipe Institute TR-2 example carries 5.00 phr of calcium carbonate in a 108.03 phr compound, beside 0.70 phr of heat stabilizer and 0.45 phr of calcium stearate. The rest of the recipe around the filler is set out in rigid PVC (uPVC) formulations. A fine carbonate co-modifies impact, while the primary toughening job in these compounds belongs to the impact modifiers for PVC, and our source library records no PCC loading for that co-modifier role.

PCC in PVC cable compounds#

PVC cable compounds take calcium carbonate up to 70 phr, and in flame-retarded recipes chalk appears at about 10 phr beside 45 to 100 phr of aluminium trihydrate, at a limiting oxygen index of 26 to 27 % and a UL 94 V-0 rating at 3 mm (Huber Advanced Materials cable formulations). The published recipes run PVC K70 at 100 phr with 55 phr of DIDP, 2.7 phr of a lead-free stabilizer and, in the third formulation, 5 phr of zinc borate, which places the filler inside a crowded compound.

A high-surface-area filler also competes for the plasticizer. Oil absorption, measured by ISO 787-5 or ASTM D281, predicts how much plasticizer the mineral takes up, so a change of grade at a constant plasticizer dose shifts the hardness of the insulation. The full insulation package, from plasticizer to flame retardant, is on additives for wire and cable compounds. For volume resistivity, compounders reach for calcined kaolin in plastics instead of a carbonate.

PCC in polypropylene and polyethylene#

Polypropylene compounds carry 20 to 40 % calcium carbonate, a value for the mineral in general, and the fine coated grades are the ones that can raise impact strength instead of only cutting cost. Nano calcium carbonate also appears among the mineral nucleating fillers for polypropylene, beside talc, which is a crystallization effect rather than a stiffness effect. Whether a nano grade nucleates at all is measured by DSC testing: crystallization temperature and nucleation efficiency, which reports the shift in crystallization temperature that a nucleating filler produces.

In polyethylene the mineral normally arrives as a filler masterbatch rather than as a dry-blended powder, and a second role exists at a far lower dose: calcium carbonate can act as an antiblock at 2,500 to 20,000 ppm, a level 250 to 300 % higher than diatomaceous earth or talc needs. Nano calcium carbonate sits among the mineral nucleating agents, where the comparison with talc and with the sorbitol clarifiers is made per polymer.

PCC in filler masterbatch#

Filler masterbatch concentrates 70 to 85 % calcium carbonate in a polyethylene or polypropylene carrier, which is well above the 40 to 65 wt% of a typical additive masterbatch, and above the 15 to 80 wt% band that covers the extreme cases. A converter therefore buys the mineral as a pellet and doses it on the extruder instead of handling powder at the throat.

Loading that much mineral costs flow. A 60 wt% calcium carbonate masterbatch in LLDPE showed a melt viscosity three times that of the neat polymer, and 3 wt% of wax with 1.0 wt% of zinc stearate returned it to just above the neat value (Journal of Polymer Engineering, 2022). Concentrations, carriers and let-down ratios for filler masterbatch are tabulated on its own page.

The flow recovery came from wax plus zinc stearate, the same lubricant pairing PVC recipes use at a far lower dose.

What Is PCC Used For? 4 Applications in Plastics#

PCC is used in 4 plastics applications: rigid PVC pipe and profile, PVC cable compounds, breathable polyethylene film, and filler masterbatch for polyethylene and polypropylene. The four are listed below in section order.

• Rigid PVC pipe and profile, where the fine particle serves surface finish and impact.
• PVC cable compounds, the highest-loading calcium carbonate application in plastics.
• Breathable and microporous polyethylene film, where the particle nucleates the pores.
• Filler masterbatch for polyethylene and polypropylene, the form most converters buy.

Rigid PVC pipe and profile#

Rigid PVC pipe and window profile are the applications where a precipitated grade earns its place, because both need a fine, uniform particle that does not spoil surface finish or notched impact. Pressure pipe takes the least filler of the group, at 5.00 phr in the Plastics Pipe Institute TR-2 example, while drainpipe runs at 15 to 20 % and profile at 5 to 15 % of a coated grade.

Line speed is the second argument for the mineral here, since Omya states that a calcium carbonate filled polymer transfers heat more quickly, which increases production line speed. Pipe compounds balance filler against stabilizer and lubricant, as additives for plastic pipes sets out, and the level in a pressure application is limited by the pressure rating rather than by the mineral.

PVC cable#

PVC cable is the highest-loading calcium carbonate application in plastics, at up to 70 phr, where the filler shares the compound with the plasticizer, the stabilizer and, in flame-retarded recipes, 45 to 100 phr of aluminium trihydrate. Chalk sits at about 10 phr in those recipes, beside the mineral flame retardant that carries the fire performance.

The fire numbers belong to the compound rather than to the carbonate. The 26 to 27 % figure in those recipes is a limiting oxygen index (LOI) value, measured on the compound at a UL 94 V-0 rating at 3 mm, and calcined kaolin rather than calcium carbonate is the filler recorded for raising volume resistivity in insulation.

Breathable and microporous PE film#

Breathable microporous film is made by filling polyethylene with fine calcium carbonate and then stretching it: the pores nucleate around the particles during biaxial stretching. Breathable PE film appears on the application list for PCC, while the pore-nucleation evidence in our source library names fine ground calcium carbonate, so the honest formulation is that fine calcium carbonate, ground or precipitated, nucleates the pores, and no PCC advantage in this application is claimed here.

The top cut decides the defect rate in a stretched film, because a coarse particle that survives classification becomes a pinhole rather than a pore, which is why d98 is the number a film converter asks for first. Breathable film sits inside the wider film additive package described under additives for packaging film, where slip, antiblock and antifog additives share the same recipe.

Filler masterbatch for PE and PP#

Filler masterbatch is how most polyethylene and polypropylene converters buy calcium carbonate, because a 70 to 85 % concentrate can be dosed on the extruder without handling mineral powder on the shop floor. A typical additive masterbatch is let down at 1 to 5 %, while a filler masterbatch is dosed far higher, since the point of the pellet is to replace resin rather than to deliver a trace additive.

The economics are family economics. Fillers account for more than 19.5 million tonnes of the 36.7 million tonnes of plastic additives consumed each year (Ceresana, 2023), and Omya states that calcium carbonate can replace up to 60 % of the polymer in a finished article, a supplier claim. Masterbatch makers and mineral producers are listed separately under calcium carbonate and mineral filler suppliers.

How Does PCC Perform in a Compound?#

PCC changes four measurable properties of a compound: flexural modulus rises with the filler volume fraction, tensile strength falls unless the particle is bonded to the matrix, notched impact can rise for fine coated grades, and density rises towards the 2.7 to 2.95 g/cm3 of the mineral itself. Why does a filler that raises stiffness lower strength? Stiffness follows volume and shape while strength follows adhesion, so a poorly bonded blocky particle can raise the modulus and still cut the tensile strength, an effect the Pukanszky interaction parameter B was introduced to quantify (Pukanszky, Composites 21 (1990) 255 to 262; reviewed by Fu, Feng, Lauke and Mai, Composites Part B 39 (2008) 933 to 961).

Table T4. PCC performance indicators, direction of change and the methods that measure them.

Equipment wear follows hardness. Abrasion scales with Mohs hardness, where talc is 1, calcium carbonate 3, wollastonite 4.5, silica 5.5 to 7 and alumina 9, so a move from talc to a carbonate costs tool life while a move from silica to a carbonate saves it. Heat deflection temperature rises with the mineral as well, less than with talc or glass fibre, and the flow penalty of a high filler load shows up as a changed melt flow rate (MFR).

Four indicators in that table carry a method and no number. Our source library holds no PCC value for volatility, migration, oil absorption, specific surface area or melt viscosity, so Table T4 names the standard that measures each one and leaves the value to the grade data sheet.

How Does PCC Interact with Other Additives?#

PCC interacts with three additive groups in a compound: the acid scavengers and heat stabilizers, because carbonates react with hydrogen chloride; the metal stearates and waxes, because they share the particle surface and the flow problem; and the coupling agents, because silanes do not bond to a carbonate surface. Each interaction and its consequence is set out below.

• Acid scavengers and PVC heat stabilizers, because a carbonate consumes hydrogen chloride, the same chemistry the acid scavengers and catalyst neutralizers are chosen for, and PVC releases that acid slowly from 100 to 120 °C (212 to 248 °F) and rapidly near 250 °C (482 °F).
• Lubricants and metal stearates, because 3 wt% of wax plus 1.0 wt% of zinc stearate restored the flow of a 60 wt% filled LLDPE masterbatch, and the Plastics Pipe Institute pipe recipe carries 0.45 phr of calcium stearate beside 5.00 phr of filler.
• Coupling agents, because silanes are ineffective on calcium carbonate, which sits on the poor-substrate list for silane coupling agents beside gypsum, barytes, graphite and carbon black, so a stearic-acid coating is the surface answer.

Plasticizer competition closes the list, since a high-surface-area grade absorbs plasticizer in flexible PVC and shifts the hardness of the compound at a constant dose, measured as oil absorption under ISO 787-5 or ASTM D281.

What Is the Regulatory Status of PCC?#

PCC is registered under REACH as calcium carbonate, is not on the SVHC Candidate List, is not restricted under REACH Annex XVII, is authorised for EU food-contact plastics as FCM substance 21 with no specific migration limit, and is generally recognized as safe for food use in the United States under 21 CFR 184.1191 (status 22 September 2026). Fourteen instruments reach the substance, in three mechanisms: a registration duty that depends on the manufacturing route, a food-contact authorisation that covers both routes, and nanoform rules that reach only the ultrafine grades.

Table T5. PCC regulatory matrix, as of 22 September 2026.

Two rows do the practical work. What FCM numbers, Ref numbers and the overall migration limit mean is explained on EU 10/2011, and the REACH row is the only place where a precipitated grade and a quarried grade part company.

Is PCC registered under REACH, or exempt as a natural mineral?#

Yes, PCC is covered by a REACH registration: calcium carbonate under EC 207-439-9 carries 296 active dossiers in a joint submission, and PCC needs that registration because it is manufactured rather than quarried. The dossier evaluation concluded on 22 January 2016, and the ECHA CHEM record was checked for this page on 22 September 2026.

The asymmetry runs the other way for the mined grades. REACH Annex V exempts naturally occurring minerals that are not chemically modified, at points 7 and 8, which is why ECHA CHEM shows no active dossier for limestone (EC 215-279-6), kaolin, dolomite, mica or wollastonite while calcium carbonate itself carries hundreds. Registration, joint submissions and the Annex V exemptions are covered on REACH and plastic additives. No tonnage band is stated here, because none is recorded in our source library.

Do nano-PCC grades carry extra REACH and food-contact duties?#

Yes, nano-PCC carries two duties that a standard grade does not: a REACH registrant must describe the nanoform under Regulation (EU) 2018/1881, and Regulation (EU) No 10/2011 allows a nanoform in food-contact plastics only where Annex I explicitly authorises it, under Article 9(2). The 100 nm criterion brings a grade into that category, so a 20 nm product is inside it and a 10 micrometre product is not.

The FCM 21 entry carries no nanoform specification, so a food-contact user of an ultrafine grade checks the grade specification against Article 9(2) with the supplier.

Is PCC allowed in food-contact plastics?#

Yes: calcium carbonate is listed in Annex I of Regulation (EU) No 10/2011 as FCM substance 21 (Ref 42500, "carbonic acid, salts"), authorised as an additive with no specific migration limit, so the generic limit of 60 mg/kg and the overall migration limit of 10 mg/dm2 apply to the finished article. For articles intended for infants the overall migration limit is 60 mg/kg instead. Annex II adds the metal limits: calcium carries no limit, while aluminium and barium are limited to 1 mg/kg and zinc to 5 mg/kg of food.

The entry places the mineral in the better half of its family: talc is FCM 615, dolomite FCM 623, kaolin FCM 410 with a nanoparticle restriction and synthetic amorphous silica FCM 504, while barium sulfate has no named Annex I entry and is used as a salt of an authorised acid under Article 6(3)(a), under the Annex II barium limit of 1 mg/kg. Additives without an individual limit fall back on the generic value, as the table of specific migration limits (SML) shows, and the simulants and conditions that produce the measured value are set out under migration testing.

United States: 21 CFR 184.1191 GRAS and 21 CFR 178.3297#

In the United States, calcium carbonate is generally recognized as safe for food use under 21 CFR 184.1191, a listing that names the carbonation process among its manufacturing methods, and it appears in 21 CFR 178.3297 as a colorant for polymers at the level needed for the colouring effect. The same list holds mica, China clay, barium sulfate, bentonite, calcium silicate, diatomaceous earth, talc and silica.

One nuance separates the two citations. Filler-level use in a food-contact polyolefin rests on the status of the substance together with the regulation of the polymer itself, not on the colorant listing, because 21 CFR 178.3297 limits the use level to what the colouring effect reasonably requires. Which 21 CFR route applies to which additive is set out under FDA food contact rules for plastic additives, and neither route is an approval of the filler, so this page cites the section and the condition instead.

Is calcium carbonate listed under California Proposition 65?#

Calcium carbonate is not among the mineral fillers listed under Proposition 65 in our regulatory data (OEHHA list, checked 22 September 2026), while four other mineral additives are: respirable crystalline silica since 1 October 1988, talc containing asbestiform fibers since 1 April 1990, respirable carbon black since 21 February 2003 and respirable titanium dioxide since 2 September 2011. Each listing names a respirable or fibrous form rather than the bulk mineral. Listing dates for every mineral additive are on California Proposition 65.

Is PCC Safe? Health, Safety and Handling#

Calcium carbonate has no harmonised hazard classification under the EU CLP Regulation, and 3,180 of the 3,535 companies that notified it to ECHA report that it does not meet the GHS hazard criteria. The absence of a classification describes the substance and not the dust, so the handling question is answered separately from the hazard question, as the three points below set out.

• Classification status, with no harmonised entry in Annex VI of the CLP Regulation and a minority of the 3,535 notifications citing eye or respiratory irritation.
• Dust handling, where the concrete comparison is respirable crystalline silica, limited to 0.1 mg/m3 in the EU under Directive (EU) 2017/2398 and to a permissible exposure limit of 50 micrograms per cubic metre with a 25 micrograms per cubic metre action level in the United States under 29 CFR 1910.1053, limits written for quarried minerals containing quartz rather than for a carbonate.
• The gap, since our source library holds no PCC-specific occupational exposure limit, respirable-fraction value or nanoform toxicology value.

Whether a PCC grade is free of crystalline silica is a grade property that no source in our library records, so it is not claimed, and the words "safe", "non-toxic" and "inert" describe no measured property of the powder. An unclassified substance still travels with safety data sheets and GHS labels.

What Are the Alternatives to PCC?#

The six alternatives to PCC in a filled compound are ground calcium carbonate, talc, dolomite, kaolin, barium sulfate and precipitated silica, and the choice turns on particle shape, hardness, density and food-contact status rather than on chemistry. Table T6 compares all seven minerals on the properties that decide a substitution.

Table T6. PCC compared with 6 alternative mineral fillers.

Footnote: PCC and GCC share the same substance identity and the same FCM entry. They differ in how the particle is made, in the uniformity of the result, and in the REACH obligation that follows from the route.

PCC vs GCC (ground calcium carbonate)#

PCC is worth its price over ground calcium carbonate only when the compound needs a finer and more uniform particle than grinding delivers: impact co-modification in rigid PVC, opacity in a thin section, and pore nucleation in a stretched film. Those three cases are the commercial argument for the synthetic route in plastics, and each rests on the particle rather than on the chemistry.

What does not differ is larger than what does. Both grades are calcium carbonate under the same substance identity and the same FCM 21 entry, so a switch from a ground grade to a precipitated one is a particle decision rather than a regulatory one, with one exception: the quarried grade relies on the Annex V exemption for unmodified natural minerals, while the manufactured grade is covered by the joint registration. Ground calcium carbonate does the same chemical job at a lower price, with a broader particle distribution, and the comparison figures circulating on supplier and trader pages for sedimentation volume, true density, oil absorption and whiteness are not reproduced here, because none is in our source library and one widely copied table labels two rows with the wrong material.

In short: the precipitated grade earns its price where the particle has to be fine, narrow and of a controlled habit, above all for impact co-modification in rigid PVC and for surface finish in a thin rigid section. The ground grade wins on cost per kilogram at high loading and on registration paperwork, and either route serves pore nucleation in breathable film. The food-contact entry is identical for both, FCM 21, Ref 42500, with no specific migration limit. The criterion-by-criterion comparison, with the loading bands each grade takes per polymer, is set out under calcium carbonate filler.

PCC vs talc#

Talc raises stiffness and heat deflection temperature more than PCC at the same loading, because its platelets carry an aspect ratio of 5 to 40 against 1 to 3 for a carbonate particle. Talc also nucleates polypropylene crystallization, it is the softest of the common fillers at Mohs 1, and its Lewis-acid surface sites can catalyse polymer oxidation at elevated temperature.

The compliance difference decides substitutions in the other direction. The ECHA Committee for Risk Assessment recommended on 20 September 2024 that talc be classified Carc. 1B (H350) and STOT RE 1 (H372, lungs), a recommendation that remains proposed and is not in Annex VI of the CLP Regulation as of the 1 July 2026 consolidation, and the International Agency for Research on Cancer placed asbestos-free talc in Group 2A in July 2024, while calcium carbonate carries no harmonised classification. The platelet case, including that pending classification, is on talc in plastics.

PCC vs dolomite, kaolin and barium sulfate#

Dolomite, kaolin and barium sulfate replace PCC when the compound needs a cheaper carbonate, a platy silicate or a much higher density.

Dolomite is the magnesium-bearing carbonate, at 2.85 g/cm3 and Mohs 3.5 to 4, with mean sizes from 1 to 30 micrometres and food-contact entry FCM 623 (Ref 52640). Kaolin is the platy option at 2.6 g/cm3 and Mohs 2, with entry FCM 410 (Ref 62720), which restricts particles thinner than 100 nm to less than 12 % w/w in an EVOH inner layer behind a functional barrier; the calcined grade raises volume resistivity in PVC wire insulation. Barium sulfate is the density and radiopacity choice at 4.25 to 4.5 g/cm3, used at up to 70 % in polypropylene and polystyrene, with no named Annex I entry and a barium migration limit of 1 mg/kg, and those two properties are the reasons to specify barium sulfate in plastics rather than a carbonate.

PCC vs precipitated silica#

Precipitated silica is the other synthetic precipitated filler used in polymers, but it does a different job: at a specific surface area of 5 to 100 m2/g it reinforces rubber and thermoplastic elastomers, where PCC extends and co-modifies a rigid compound. Its primary particles run from 5 to 100 nm, well below the carbonate range, and the same fineness makes it an antiblock and a matting agent in film.

The practical consequences are wear and paperwork. Silica at Mohs 5.5 is far more abrasive to screws, barrels and dies than calcium carbonate at Mohs 3, and the two minerals sit under different food-contact entries, FCM 504 against FCM 21. The reinforcing route, precipitated silica, carries CAS 7631-86-9, with the former CAS number 112926-00-8 still printed on data sheets.

Who Manufactures PCC? Grades and Suppliers#

PCC for plastics comes from four producers recorded in our supplier data: Omya, Imerys, Minerals Technologies (Specialty Minerals) and Huber. Omya, founded in 1884 and based in Oftringen in Switzerland, employs about 9,000 people and carries calcium carbonate as its product line.

Table T7. PCC producers recorded in our supplier data.

Footnote: no PCC trade name is recorded in our source library, so this table names companies and not grades. Ask the supplier for the grade data sheet.

Buyers should ask for the grade data sheet with the d50, the top cut, the surface treatment and the specific surface area, because none of these is a substance property. PCC costs more per tonne than ground calcium carbonate, since the precipitation route adds a process step to a quarried raw material, and what that step adds is tracked on calcium carbonate filler price, because our source library holds no price figure. More producers and their locations sit in the directory of mineral filler suppliers, and the USGS Mineral Commodity Summaries 2026 names ground and precipitated calcium carbonate, kaolin and talc as substitutes for titanium dioxide as a white pigment.

How Does PCC Fit into the Wider Filler Family?#

PCC is the synthetic member of the carbonate filler class, the group that also holds ground calcium carbonate, nano-PCC, stearate-coated grades, dolomite, magnesium carbonate and the mineral flame retardant huntite-hydromagnesite, inside a filler family that accounts for more than 19.5 million tonnes of the 36.7 million tonnes of plastic additives used each year (Ceresana, 2023). Fillers across all industries exceed 53 million tonnes per year, worth about USD 18 billion, from more than 700 producers. Where the carbonate class sits among the types of fillers for plastics is mapped on the family hub.

How is the filler content of a PCC compound measured?#

The calcium carbonate content of a finished part is measured as ash, by ISO 3451-1 or ASTM D5630, and cross-checked against density by ISO 1183 or ASTM D792. Thermogravimetric analysis is the third route, and it separates the mineral residue from the polymer by mass loss rather than by combustion in a crucible.

A carbonate complicates the arithmetic, because it loses carbon dioxide when ashed, so the residue is not the filler as dosed. Our source library records the methods rather than the stoichiometric correction, so no correction factor is published here. Both methods are described under ash content and filler content testing.

Does PCC affect recyclability?#

A mineral-filled polypropylene above 1.0 g/cm3 sinks in float-sink separation, which is the recycling consequence of a filler whose own density is 2.7 to 2.95 g/cm3. Sinking sends the material into the wrong stream of a sorting plant, so filler loading is a sorting decision and not only a cost decision.

The Packaging and Packaging Waste Regulation, Regulation (EU) 2025/40, applies from 12 August 2026 and introduces recyclability performance grades, which turns that density effect into a graded requirement for packaging. No filler threshold is named on this page, because the RecyClass and APR values are not in our source library. Float-sink separation and the PPWR grades are covered under design for recycling.

Where PCC is used outside plastics#

Most of the world's PCC never reaches a plastic: paper is its largest market, and the substance is also used in food, in pharmaceuticals and in dipped latex gloves, which is a rubber application rather than a plastics one. The glove use is supplied as a PCC slurry, and it appears on the application record for the substance beside the four plastics applications covered above.

Food use rests on the same United States listing cited earlier, 21 CFR 184.1191. This site covers the plastics use, so the paper, food and pharmaceutical markets get this sentence and nothing more, and no tonnage split by industry is given, because none is recorded in our source library.

Is PCC better than GCC?#

No: PCC is finer and more uniform, not better, and it is the right choice only where the compound pays for that uniformity, as in impact co-modification of rigid PVC. Both grades share CAS 471-34-1, the 0.02 to 30 micrometre size range of the class and the FCM 21 entry, so the decision is made on the distribution and the top cut rather than on the substance.

What does PCC cost?#

PCC costs more per tonne than ground calcium carbonate, because the precipitation route adds a process step to a quarried raw material. No price figure for either grade is published on this page, since our source library holds none for PCC; the two grades are priced side by side under GCC vs PCC price.

Is nano-PCC a nanomaterial under EU law?#

An ultrafine PCC grade with a particle dimension below 100 nm is a nanoform, which triggers the REACH nanoform information requirements introduced by Regulation (EU) 2018/1881 and brings the food-contact nanoform rule of Regulation (EU) No 10/2011 into play. The criterion applied here is the 100 nm nanofiller size criterion recorded in our source library, and the EU recommended definition of a nanomaterial is not quoted, because it is not in that library.

Does PCC need a safety data sheet?#

Yes: suppliers provide a safety data sheet for PCC as for any traded chemical, even though calcium carbonate carries no harmonised CLP classification. The sheet records the supplier's own classification decision, which for 3,180 of the 3,535 notifiers is that the substance does not meet the GHS criteria.