How to Recycle Industrial Plastic Resin Waste
Manufacturing scrap plastic: injection-molding runners and sprues, thermoforming trim, blown-film waste, and off-spec resin. Clean, single-resin production scrap is excellent feedstock, but its status as certified recycled content is more limited than most shops assume.
Quick answer
In-house regrind from your own molding or extrusion process is real, usable feedstock, but it doesn't count as recycled content under ISO 14021, the standard most brand and EPR programs use; it's classified as rework, not post-industrial recycled material. Keep regrind to roughly 25 to 30 percent of the melt for non-critical parts, higher than the 5 to 15 percent many shops assume, watch glass-filled resins for fiber breakage, and don't identify unknown plastic with a burn test. Before you go, confirm that a local recycling center accepts the material in its current condition.
- Recycling route
- Check locally
- Typical value
- No verified, dated per-pound price range could be confirmed for post-industrial resin; prices vary widely by resin type, color, and regional market and are usually negotiated directly with a reclaimer or broker rather than posted.
How to Prepare
- 1Sort by resin type using production records and resin ID codes first; density testing (polypropylene floats, PET sinks) is a reasonable shop-floor backup
- 2Never use burn or smell tests to identify unknown plastic; burning PVC releases hydrogen chloride, and burning fluoropolymers releases hydrogen fluoride
- 3Keep colors separated within each resin type; clear and natural material holds more value than mixed colors
- 4Remove metal inserts, labels, and non-plastic components before grinding
- 5Grind at low RPM and screen out fines; fines and inconsistent particle size cause uneven melting and streaking
- 6For glass-filled resins, track how many times material has been reground; each pass breaks more glass fiber and reduces mechanical properties
- 7Keep purge compound and purge slugs separate from clean regrind; a purge slug is mixed-resin, additive-loaded material by design and doesn't share the same value
- 8Store away from UV exposure to prevent degradation before reprocessing
Where to Recycle
- Plastic reclaimers and reprocessors
- Resin brokers specializing in industrial scrap
- In-house regrinding, for clean single-resin runners and trim
- Chemical/advanced recycling facilities, for mixed or contaminated streams
Special Instructions
Thermoset plastics (epoxy, polyurethane) can't be mechanically remelted and need chemical recycling or another disposal route; PVC needs to stay separate from other resins because of chlorine contamination risk during reprocessing. The more important distinction is definitional: under ISO 14021 as applied by the Association of Plastic Recyclers, in-house regrind that's reclaimed by the same process that generated it is explicitly excluded from post-industrial recycled content; it's classified as rework. That matters because only certified post-consumer recycled content satisfies most brand sustainability pledges and state minimum-recycled-content laws, so don't market a regrind stream as meeting those requirements. As feedstock, clean post-industrial scrap is still useful: known resin, known heat history, no sorting cost. International shipments of mixed or contaminated plastic scrap can also trigger Basel Convention prior-informed-consent requirements adopted in 2021, and several states have their own extended producer responsibility laws for packaging; check both before an international shipment or a recycled-content claim.
Environmental Impact
Regrind ratios are more forgiving than most shops assume. Industry sources, including custom molders and resin distributors, put the safe blending range at up to 25 to 30 percent compatible regrind mixed with virgin material without compromising mechanical properties, well above the 5 to 15 percent figure that circulates informally. Two real caveats: glass-filled resins lose tensile and impact strength as regrinding breaks more fiber with each pass, and fines from grinding cause non-uniform melting, variable drying in hygroscopic resins, and visible streaking or black specks. Purging compounds are a separate product category used for color and material changeovers; whether purge slugs themselves have any recycling value isn't established, since they're mixed-resin, additive-loaded, and often thermally degraded by design.
Official guidance and resources
Accepted items and drop-off rules can vary by location. Check the destination before you go.
What’s Accepted
Accepted
- Clean injection-molding runners and sprues
- Thermoforming trim and edge waste
- Blown-film and sheet trim
- Off-specification resin and pellets, single-polymer
Not Accepted
- Thermoset plastics (epoxy, polyurethane) - can't be mechanically remelted
- Multi-layer films and laminates
- Mixed-resin purge slugs - no established recycling market
- Plastic with metal inserts or composite construction
Donation & Take‑Back Options
Estimated value: No verified, dated per-pound price range could be confirmed for post-industrial resin; prices vary widely by resin type, color, and regional market and are usually negotiated directly with a reclaimer or broker rather than posted.
Hazardous Components
- Flame retardants in some electronics-grade plastics
- Phthalate plasticizers in flexible PVC
- Residual processing aids and monomers
FAQs
Does my in-house regrind count as recycled content?
No. Under ISO 14021, as applied by the Association of Plastic Recyclers, material reclaimed by the same process that generated it is classified as rework, not post-industrial recycled content. It's still useful feedstock, just not something you can certify as recycled content for a brand pledge or EPR law.
How much regrind can I mix with virgin resin?
Industry guidance from custom molders and resin distributors puts the safe range at up to 25-30 percent for non-critical parts, higher than the 5-15 percent many shops default to. Glass-filled resins are the exception; each regrind pass breaks more fiber and lowers strength, so the safe ratio is lower there.
How do I identify unknown scrap plastic safely?
Start with production records, supplier data sheets, and resin ID codes. Density testing (PP floats, PET sinks) is a reasonable backup. Don't use a burn test: burning PVC releases hydrogen chloride and burning fluoropolymers releases hydrogen fluoride. Send anything genuinely unknown for lab identification.
Are purge compound slugs recyclable?
No established recycling market exists for them. A purge slug is by construction a mixed-resin, additive-loaded, often thermally degraded lump, the opposite of the clean single-resin condition that gives production scrap its value.
Is post-industrial scrap worth more than post-consumer scrap?
As feedstock, yes: it's cleaner, single-resin, and has known heat history. As certified recycled content, no: only post-consumer material satisfies most EPR laws and brand recycled-content commitments, so post-industrial resin can't substitute for it on paper even when it's better material.
Do any special rules apply to shipping plastic scrap internationally?
Potentially. International shipments of mixed or contaminated plastic scrap can trigger Basel Convention prior-informed-consent requirements, and some states have their own extended producer responsibility rules for packaging. Check both before an international shipment.
Related recycling guides
- How to recycle Industrial Adhesives & Sealants
- How to recycle CNC Machine Tools & Cutting Tools
- How to recycle Industrial Cleaning Chemicals
- How to recycle Industrial Batteries & Power Systems
- How to recycle Manufacturing Scrap Metal
- How to recycle Industrial Solvents & Degreasers
- How to recycle Industrial Packaging Materials
- How to recycle Machining Coolant & Cutting Fluids
- How to recycle Industrial Textiles & Fabrics
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