Cling Agents for Stretch Film: PIB and Other Tackifiers

Cling agents are tacky polyolefin oligomers, mainly polyisobutylene (PIB, CAS 9003-27-4), that reach the surface of polyethylene stretch film after extrusion and make overlapping layers of that film adhere to one another, so a wrapped pallet holds without tape. Two routes to a clinging film are established in our sources, and only the first of them uses a cling agent: polyisobutylene in polyethylene stretch film, and plasticizer tack in PVC cling film, where the softener already in the compound does the work. Which route belongs in which film, and what does the published record actually fix about the dosage?

Cling agents are family 43 of the 43 families of plastic additives, and they sit in the surface and optical modifier group beside antistatic agents, antifog additives, anti-scratch additives, matting agents and light diffusers. They are the thinnest documented family of that group. One substance carries the function in the polyisobutylene route, one regulatory file exists for it, and no dosage, no cling-force test criterion, no producer list and no market figure for cling agents is established in our sources, so this page states the gaps where they fall rather than filling them with supplier copy.

This page defines a cling agent and separates it from a slip agent, explains why stretch film needs cling at all, works through tack and surface enrichment as the mechanism, gives the identity, class and regulatory file of polyisobutylene, sets the PVC route beside it with the adipate, citrate and epoxidized-oil plasticizers that make cling film cling, covers the interaction with slip, antiblock, antifog and antistatic additives that share the same surface, names the three uses that matter, sets out the food-contact position in the EU, the United States and Korea, and closes with the complete substance list and the recycling and safety questions below the contextual border.

The 2 established routes to a clinging film differ in the polymer they belong to, in the substance that carries the tack and in whether an additive is dosed for cling at all.

Route 2 is not a cling-agent route in the strict sense: the cling is a consequence of the plasticizer level chosen for flexibility, not of a separate tackifier.

What Is a Cling Agent for Stretch Film?#

A cling agent is an additive that raises the tack of a plastic film surface so that overlapping layers of the same film adhere to one another, and in polyethylene stretch film that additive is polyisobutylene. Tack here means the resistance of two surfaces to being pulled apart after light contact and short contact time, which is a different property from the friction a film feels while sliding and a different property again from the permanent bond an adhesive builds.

The function carries 3 names in specifications: cling agent, cling additive and tackifier. The third one is the trap. A tackifier in the wider chemical trade is a resin for hot-melt and pressure-sensitive adhesives, where rosins, terpenes and C5 or C9 hydrocarbon resins make up as much as 40 % of the mass of a hot-melt formulation, and that adhesive use lies outside the plastics border of this reference. Inside plastics, the tackifier function has one established home, which is the cling layer of polyethylene stretch film.

Cling Agent vs Slip Agent: Opposite Jobs at the Same Surface#

A cling agent raises the adhesion between film layers while a slip agent lowers the friction between them, so the two families work against each other at the same film surface. Both reach that surface from inside the polymer, both are consumed by the same surface area, and a film that carries the wrong one performs the opposite of its intended job: a stretch wrap that slips does not hold a pallet, and a bag that clings does not open on the packing line.

The dosage scales of the two families are documented very differently. Erucamide and oleamide in LDPE and LLDPE film are dosed at 500 to 1,200 ppm (0.05 to 0.12 wt%) with a target coefficient of friction of around 0.2 in supplier guidance, and the substances, bloom times and test method of that family are set out on slip additives for plastic film. No equivalent published window exists for polyisobutylene in stretch film in our sources. A converter therefore reads a cling level from a supplier data sheet and a slip level from a body of shared industry data, which is the practical asymmetry between the two families.

Why Does Stretch Film Need a Cling Agent?#

Stretch film needs a cling agent because the film has to hold itself closed around a load with no tape, no heat seal and no adhesive tape join, and untreated polyethylene surfaces do not stay together once the winding tension relaxes. The cling layer replaces a mechanical fastening with a surface property, which is what makes pallet wrapping a single continuous operation.

Four requirements follow from that job.

• Layer-to-layer adhesion, because the wrap is held by the overlap between successive turns of film rather than by any fastener.
• Retention over time, because a wrapped pallet is stored and transported after the wrapping machine has released it.
• Separability on unwrapping, because the film has to come off the load again without tearing into fragments.
• Compatibility with the rest of the film package, because the same surface also carries whatever slip, antiblock or antistatic additive the structure needs.

How strong does the cling have to be? No cling-force value, no test criterion and no standard test method for cling is established in our sources, so the honest form of the requirement is a property to specify with the film supplier rather than a number to quote. Stretch film sits in the wider family of film formulations described on additives for packaging film, where cling is balanced against the friction, blocking and static properties of the same surface.

How Do Cling Agents Work? Tack, Migration and Contact Area#

Polyisobutylene works by leaving the bulk of the polyethylene and enriching the film surface, where its low glass transition and tacky character raise the adhesion between two layers pressed together. Polyisobutylene is classified as a polyolefin oligomer or polymer, and it migrates to the surface after extrusion, which places it with the migrating additives rather than with the permanently bound ones.

Surface enrichment is the same physical process that governs fatty amide slip agents, antistatic agents and antifog additives, and it is driven by limited solubility in the host polymer rather than by any reaction. The rate at which an additive crosses a polymer and reaches a surface is set by its diffusion coefficient and its solubility, which is why the effect of a migrating additive develops over hours to days instead of appearing at the die. The general treatment is on additive migration in plastics, and the surface-enrichment case of it is covered under blooming and exudation in plastics.

Two consequences of the migrating mechanism matter on the line. Cling develops after the film is wound rather than at the extruder, so a roll tested immediately after production is not the roll the packer will use, and a cling layer is a shared resource, because every other migrating additive in the formulation competes for the same surface.

How Much Polyisobutylene Does Stretch Film Contain?#

No dosage window for polyisobutylene in stretch film is established in our sources, so the level in a specification comes from the film or masterbatch supplier's technical data sheet rather than from published guidance. This is the largest single gap in the cling-agent record, and it is the reason this page gives no phr, wt% or ppm figure for PIB.

The arithmetic around that number is fixed even where the number is not. Cling is dosed through additive masterbatch in the same way as slip and antiblock, because a concentrate carries the active substance at a known percentage and the let-down ratio sets how much concentrate enters the polymer.

Only the product of the two gives the level in the finished film, and that product is what a specification should state. Check any concentrate addition against the target level with the let-down ratio calculator, and record the result as a film level, not as a hopper addition.

Polyisobutylene (PIB): The Standard Cling Agent for Polyethylene Stretch Film#

Polyisobutylene, PIB, CAS 9003-27-4 and EC 618-360-8, is a polyolefin oligomer or polymer used as the cling agent and tackifier of LLDPE stretch and cling film, and it is the only substance in our sources whose recorded function is cling. ECHA CHEM lists the trade name MAT 70 for it. Its molecular weight, its physical constants and its grade structure are not recorded in our sources, and grade selection in this family turns on molecular weight, so that gap is material rather than cosmetic.

The identity data come from the ECHA CHEM entry for polyisobutylene, checked on 22 September 2026.

A dedicated profile of the substance, with whatever identity and grade data can be verified, is being built as polyisobutylene (PIB) cling agent for stretch film. Our sources record no alternative cling substance for polyethylene film, so any second tackifier named in a supplier brochure has to be verified against a primary source before it belongs in a specification.

Regulatory Status of Polyisobutylene#

Polyisobutylene is not on the Candidate List of substances of very high concern, it is not listed in Annex I of Regulation (EU) No 10/2011, and it does hold an entry on the EU drinking-water positive list, so its regulatory profile is short but not empty. The Candidate List position was checked against ECHA CHEM on 22 September 2026.

Its REACH position follows from what it is. Polymers are exempt from registration under Article 2(9) of Regulation (EC) No 1907/2006 (REACH), and ECHA CHEM shows polyisobutylene with no tonnage band. The registration duties that apply to additives generally, including additives imported inside a masterbatch, are set out on REACH and plastic additives.

Food contact is where the absence matters. The Union list of Annex I to Regulation (EU) No 10/2011 carries the monomers, additives and polymer production aids that may be used in plastic food-contact materials, and polyisobutylene has no FCM number on the consolidated text re-checked on 14 July 2026. A stretch film carrying PIB therefore cannot rely on a Union list entry for its compliance argument, and the alternative routes in the same regulation, such as the functional-barrier provisions of Articles 13 and 14 for substances not detectable at 0.01 mg/kg, have to be documented case by case. The structure of the regulation is explained on EU 10/2011.

One positive list does name it. Polyisobutylene holds entry 0961 of the European positive list for substances in contact with drinking water under Commission Implementing Decision (EU) 2024/367, recorded in its ECHA CHEM obligations, and the drinking-water lists are covered on plastic additives in drinking-water contact.

Other Tackifiers and the Second Cling Route: Plasticized PVC#

The second established route to a clinging film uses no cling agent at all: plasticized PVC cling film clings because the plasticizer that makes it flexible also makes its surface soft and tacky. This is why household food wrap and industrial pallet wrap behave alike and are formulated on completely different principles.

The distinction has a practical consequence for sourcing. A PVC cling film specification is written in plasticizer terms, with a substance, a level in wt% and a migration limit, while a polyethylene stretch film specification is written in cling-agent terms with a masterbatch and a let-down ratio. The general behaviour of the softening additives is covered on plasticizers for plastics, and the compound around them on additives for PVC.

Which Plasticizers Make PVC Cling Film Cling?#

Bis(2-ethylhexyl) adipate, DEHA or DOA, CAS 103-23-1, is the main plasticizer of PVC cling film, and 4 further plasticizers in our sources record cling film among their applications. Adipates are chosen there for their low glass-transition contribution and cold flexibility, at the price of higher volatility and extraction than the phthalate and terephthalate esters.

Group restriction 32 of Regulation (EU) No 10/2011 caps the sum of the plasticizers it covers at 60 mg/kg. The DINCH level of 10 wt% for cling film for fresh meat is an HSDB use figure, not a supplier recommendation.

Two of these entries carry a warning for anyone writing a cling-film specification today. The adipate route is under active regulatory pressure in Korea, where Ministry of Food and Drug Safety Notification 2026-24 of 27 March 2026 sets DEHA at 18 mg/L with a "not detected" requirement for cling wrap from 27 March 2027, alongside a "not detected" requirement for DEHP in PVC food-contact materials; that reading rests on a secondary source. ESBO shows the other pattern, because it is dosed at 1 to 2 wt% as an HCl scavenger and co-stabilizer and only reaches 25 to 45 wt% when it carries the plasticization itself, so its presence in a cling film does not by itself mean it is the plasticizer.

How Do Cling Agents Interact with Slip, Antiblock, Antifog and Antistatic Additives?#

Cling agents share the film surface with 5 other surface-modifying families, and 2 of them work directly against cling: slip agents lower the friction of the same interface and antiblock particles hold the layers apart, and both reduce the contact area that cling depends on. All 6 families of the surface and optical modifier group act at or near the polymer surface, and 4 of them, slip, antistatic, antifog and cling, reach it by the same migration mechanism, which is exactly why they compete.

Dosage figures in the table are the published windows of each family, which exist for slip, antiblock and antifog and do not exist for cling.

The antifog row deserves a second look, because PVC cling film is one of the few structures that carries an antifog additive and cling in the same product. Glycerol monostearate is recommended at 0.5 to 1.0 % for cold-fog conditions and 0.3 to 0.6 % for hot-fog conditions in PVC cling film in Palsgaard's guidance for the Einar 211 grade, and GMS reaches the surface by the same migration route as every other additive in this group. Where two migrating additives share one surface, the outcome is set by the pair rather than by either dose alone, which is the subject of additive interactions.

Where Cling Film Is Used: Pallet Wrap, Silage Wrap and Food Wrap#

Cling film is used in 3 established places: pallet and transit wrapping in LLDPE stretch film, silage and bale wrapping in agriculture, and food wrapping in plasticized PVC. The first two use the polyethylene route with a cling agent, the third uses the plasticizer route, and the polymer decides which one applies.

The silage wrap figures are the recorded agricultural film data for bale wrapping, not a stretch-wrap specification.

Silage wrapping is the application where the cling requirement is most explicit, because the bale is wrapped in 4 to 6 layers of 25 µm film and the seal those layers form is what keeps oxygen out of the fermenting forage. Agricultural film formulation, where the UV and antifog requirements are at least as demanding as the mechanical ones, is covered on additives for agricultural film.

The polymer side of the pallet-wrap case belongs to the polyolefin file, since cling is one property of an LLDPE film whose stiffness, puncture resistance and stretch behaviour are set by the resin rather than by the additive. The additive package for that polymer family is on additives for polyethylene, and the food-contact versions of these structures on additives for food packaging.

How Are Cling Agents Regulated for Food Contact?#

Cling agents have no EU food-contact authorisation as a class, because polyisobutylene carries no FCM number under Regulation (EU) No 10/2011, while the plasticizers that create cling in PVC film are fully authorised and carry specific migration limits. The regulatory asymmetry between the 2 cling routes is therefore larger than the technical one.

The EU position runs through 3 instruments. Regulation (EU) No 10/2011 sets the Union list, the generic specific migration limit of 60 mg/kg under Article 11(2) and the overall migration limit of 10 mg/dm2 under Article 12, and it is the instrument that leaves polyisobutylene unlisted. Group restriction 32 caps the sum of the covered plasticizers at 60 mg/kg, which is what binds a PVC cling film carrying DEHA at 10 to 35 wt% alongside its own specific limit of 18 mg/kg. Commission Implementing Decision (EU) 2024/367 covers the separate drinking-water case and does list polyisobutylene.

In the United States the plasticizer route is again the documented one: 21 CFR 178.3740 authorises DEHA and DINA in vinyl chloride polymers up to 24 % for film of 0.005 in or less and up to 35 % for film of 0.002 in or less, under the conditions stated there, and the general structure of those clearances is explained on FDA food contact rules. No 21 CFR clearance for polyisobutylene as a cling agent is recorded in our sources.

Outside the EU and the United States, Korea is the jurisdiction currently moving. Ministry of Food and Drug Safety Notification 2026-24 of 27 March 2026 requires DEHA to be not detected in cling wrap from 27 March 2027 and DEHP to be not detected in PVC food-contact materials from the same date, according to a secondary summary of the notification. Anyone selling PVC cling film into Korea reads that date as a reformulation deadline. The instruments that govern every additive family are indexed on plastic additive regulations.

Complete List of Cling Agent Substances (1 Page)#

One substance page belongs to the cling agent family: polyisobutylene, the tackifier of LLDPE stretch film. The plasticizers that create cling in PVC film are filed under plasticizers, because their function in the compound is softening and the cling is a consequence of it.

Only the first row is a cling agent. The 4 plasticizer rows are listed because they are the substances that make a PVC film cling, and every one of them has its own profile in the plastic additives database.

The single-substance list is the honest state of this family rather than an editorial shortcut. Where a family hub on this site normally lists 6 to 20 substance pages, the cling record holds one, and filling that list requires primary-source identity and grade data for the other tackifiers that suppliers name for polyethylene film.

Are Cling Agents Safe, and Do They Affect Film Recycling?#

Cling agents carry no SVHC listing, no REACH Annex XVII restriction and no POPs entry, and the open questions about them are migration into food and behaviour in the polyethylene film recycling stream rather than hazard classification. Polyisobutylene has no recorded GHS classification in our sources, which is a gap in the record and not a statement that the substance is unclassified.

Do Cling Agents Migrate into Food?#

Cling agents reach the film surface by migration, which is the same route that takes any surface additive towards a food in contact with the film, and no migration measurement for polyisobutylene from stretch film exists in our sources. The absence of an FCM number means the question is answered by the film maker's own compliance file rather than by a published limit.

The plasticizer route is measured far better. DEHA carries a specific migration limit of 18 mg/kg under FCM 207 and falls under group restriction 32 at 60 mg/kg, and the International Agency for Research on Cancer classifies it in Group 3, not classifiable as to its carcinogenicity to humans. How additives cross from a polymer into a food, and which models describe it, is covered on additive migration.

Do Cling Agents Affect Stretch Film Recycling?#

No recycling assessment of cling agents is recorded in our sources, while the Association of Plastic Recyclers rates the neighbouring film additives, including slip and antiblock, as preferred for polyethylene film. Stretch film belongs to the polyethylene flexible stream, and the design guidance for that stream sets 2 recorded limits that any additive package has to respect.

• Density: the Association of Plastic Recyclers asks for testing as polyethylene film approaches 0.996 g/cm3 and treats film above 1.00 g/cm3 as non-recyclable.
• Degradable additives: the same guidance treats them as rendering a polyethylene or polypropylene package non-recyclable outright.

A cling agent that is itself a polyolefin raises neither of those flags on the record available, and no cling-specific entry appears in the design guidance at all. Which additive choices raise or lower recyclability across every family is set out on design for recycling.

Is a Tackifier the Same Thing as a Cling Agent?#

A tackifier and a cling agent are the same thing inside plastics, where the term means the additive that makes stretch film adhere to itself, but the same word names a different class of product in adhesives. Rosins, terpene resins and C5 or C9 hydrocarbon resins are tackifiers for hot-melt and pressure-sensitive adhesives, at levels reaching 40 % of a hot-melt mass, and those uses fall outside the plastics scope of this reference.

The practical test for a specification is the function, not the word. Select the additive by the property it has to deliver, film-to-film tack in this case, and then verify the substance identity, as described in how to select plastic additives.

Is Cling Film the Same as Stretch Film?#

Cling film and stretch film are different products in everyday usage: cling film usually means the plasticized PVC or polyethylene wrap sold for food, while stretch film means the LLDPE film used to wrap pallets and bales. The shared property is layer-to-layer tack; the polymers, the formulation route and the regulatory files behind them are separate.

The naming matters when a specification crosses a border, because a request for "cling film" answered with a PVC grade and a request for "stretch film" answered with an LLDPE grade lead to two different compliance arguments: FCM 207 with its 18 mg/kg limit in the first case, and an unlisted polyolefin oligomer in the second.

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