TIJ Cartridges: Porous vs Non-Porous Inks on PET/PP

Written by: John LauChecked by: MarkOctober 12, 2025

TIJ Cartridges: Porous vs Non-Porous Inks on PET/PP

TIJ Cartridges: Porous vs Non-Porous Inks on PET/PP determine whether your date codes merely appear—or truly endure—on slick plastics under real factory conditions.

Overview — TIJ Cartridges: Porous vs Non-Porous Inks on PET/PP

Thermal Inkjet (TIJ) excels at high-resolution coding with minimal maintenance. On non-porous plastics like PET bottles, rPET sleeves, and PP closures, the decisive variable is the ink family: porous-media aqueous inks rely on wicking and fail to anchor; non-porous solvent inks lower surface tension, wet the plastic, and form durable films via fast solvent flash-off and binder deposition. Treat the porous vs non-porous decision as a pass/fail gate before you optimize dpi, character height, or line speed.

Decision Card (Executive)	Target / Threshold	Test/Tool
Substrate dyne level (PP after corona)	≥38–42 dyn/cm	ASTM D2578 dyne inks; see Adhesion Checker
Ink–substrate wetting margin	Substrate energy − ink γ ≥ 7–10 dyn/cm	Wetting formula + Adhesion Checker
Dry-to-touch vs first contact time	t_dry ≤ t_contact	Drying Window Estimator
Verifier grade (1D/2D)	≥1.5 (ISO/IEC 15415/15416), customer-specific	Scanner/verifier SOP; cluster: barcode readability

If your environment includes CIJ, TTO, or laser, keep a strategic view via the pillar: Coding & Marking Consumables where inks, ribbons, and optics are compared as a system across substrates and climates.

Core Definitions & Physics — TIJ Cartridges: Porous vs Non-Porous Inks on PET/PP

Definition (Porous-ink TIJ)

Water-based, paper-focused formulations that rely on absorption and wicking. On PET/PP they bead, smear, or wipe off.

Definition (Non-porous solvent TIJ)

Low-surface-tension carriers + binder resins that wet plastics and dry rapidly, leaving an anchored film with rub/chemical resistance.

Young's Equation

γ_SV − γ_SL = γ_LV cosθ → stable wetting when substrate energy > liquid surface tension by a safe margin.

Adhesion Work (Young–Dupré)

W_adh = γ_LV(1 + cosθ). Higher W_adh correlates with better rub/tape resistance on plastics.

Parameter	PET (untreated)	PP (untreated)	PP after corona/plasma	Guidance
Surface energy (dyn/cm)	~42–46	~29–33	≥38–42	Aim substrate ≥7–10 dyn/cm above ink γ
Ink family fit	Non-porous solvent TIJ broadly compatible	Challenging w/out pretreat; choose polyolefin-rated inks	Much wider ink window; stable adhesion	Verify with tape/scratch/condensation & oil rubs

Application Realities — TIJ Cartridges: Porous vs Non-Porous Inks on PET/PP

Treat PET and PP as different printing problems. PET's higher surface energy gives a broader compatibility window: many solvent TIJ cartridges achieve acceptable adhesion on untreated PET bottles and sleeves. PP is a low-energy polyolefin (often with slip/anti-stat additives); on caps or wrap films, inks may bead or scratch unless you combine polyolefin-rated solvent inks with in-line surface treatment (corona, plasma, or flame) placed immediately upstream of the print station.

Adhesion Readiness Checker (PET/PP + TIJ Solvent Ink)

Substrate:

Measured Surface Energy (dyn/cm):

Ink Surface Tension (dyn/cm):

Wetting Margin (dyn/cm): — Target ≥7–10 dyn/cm

Readiness Verdict:

Note: Rule-of-thumb only; confirm with tape/scratch/condensation tests on actual parts.

When to Add Surface Treatment (Corona/Plasma/Flame)

For PP—and for some rPET or slip-rich PET—deploy in-line corona/plasma just ahead of the printhead. Treatment oxidizes/polarizes the surface, raises dyne level, and creates sites where binder resins anchor. Net effects: longer decap tolerance, faster line speeds at same standoff, improved wet rubs. For closures and odd geometries, flame or atmospheric plasma can be more effective; choose hardware that maintenance teams can keep clean and safe. Track dyne decay over time on the run; re-treat long runs if dyne falls.

Cartridge Ecosystem — TIJ Cartridges: Porous vs Non-Porous Inks on PET/PP

Modern non-porous TIJ solutions center on solvent-compatible heads (e.g., HP 45si platform and long-throw variants) plus black/colored solvent inks tuned for plastics. Beyond optical density and dry time, assess binder chemistry (adhesion to PET/PP; water/oil/ethanol resistance), decap time (open time without nozzle drying), and throw distance for curved or textured parts. Expect vendors to publish decap and adhesion claims and to supply cartridges for on-part tests.

Parameter	Why it matters	Typical targets	Checks
Decap (open-nozzle)	Reduce purges/stops; keep edges sharp after pauses	≥8–12 h for non-porous production	Pause/print test at line RH/temperature
Drying window	Avoid smear at target conveyor speed	Dry-to-touch < 1–2 s at set throw distance	Smear finger at 0.5/1.0/2.0 s
Binder compatibility	Anchorage to PET/PP; rub/chemical endurance	Pass tape (cross-hatch), wet rub, oil rub, condensation	Cross-hatch peel + photo evidence
Throw distance	Curved parts—avoid standoff smear	≥3–5 mm (application-specific)	HRI check at minimum curvature radius

Drying Window Estimator (Speed × Standoff)

Conveyor Speed (m/min):

Throw Distance (mm):

Dry-to-Touch Time (s):

Time to First Contact (~50mm downstream) (s):

Smear Risk: — OK if dry time ≤ contact time

Note: Heuristic only; verify on-line with finger/label smear checks at actual contact points.

Barcode & Symbol Verification — TIJ Cartridges: Porous vs Non-Porous Inks on PET/PP

Solvent TIJ produces crisp 1D/2D codes at 300–600 dpi, but compliance is proven at the verifier, not by eye. Apply GS1/ISO methods and align thresholds to customer inbound QC (for example, ≥1.5 average grade). On small caps or tight curvature, prioritize contrast, quiet zones, and grid uniformity; compensate for dot gain by tuning dpi and font/symbol size.

Verifier Quick Rules

1D: ISO/IEC 15416; 2D (label): ISO/IEC 15415; 2D DPM: ISO/IEC TR 29158.
Report formal grade as G/Aperture/Wavelength/Lighting (e.g., 2.5/10/660/45).
For curved plastics, consider 30°/90° or dome lighting verifiers.

"Recipe Cards" — TIJ Cartridges: Porous vs Non-Porous Inks on PET/PP

Untreated PET, Round Bottle, Dry Room Temp

Ink: Standard non-porous solvent TIJ black; dry-to-touch ≤1.5 s.
Setup: 300 dpi for lot/expiry; 600 dpi for tiny DataMatrix.
Speed & Standoff: 30–50 m/min; throw 3–5 mm; keep first contact ≥1.5 s.
QC: Tape pass; 50× dry rub; verifier grade ≥1.5; condensation check if refrigerated chain exists.

PP Cap, Molded Matte (Ambient or Refrigerated)

Ink: Polyolefin-rated solvent TIJ with aggressive binder and long decap.
Pretreat: Corona in-line; aim ≥38–42 dyn/cm; re-treat if long run shows dyne decay.
Setup: 300–450 dpi; increase throw for curvature; minimize vibration with rigid mounts.
QC: Tape + scratch; oil rub; condensation dwell; verifier scans for any 2D; record power, speed, dyne.

PP Wrap Film, High-Speed Multipacker

Ink: Fast-dry, high-OD solvent TIJ; bulk feed to reduce swaps.
Pretreat: Web corona; monitor power and electrode cleanliness; trend dyne levels.
Setup: 300 dpi at ≥60 m/min; guard rollers to avoid early contact; watch flutter.
QC: On-web smear checks at 0.5/1.0/2.0 s; abrasion with felt; periodic verifier scans.

Ops KPIs & Troubleshooting — TIJ Cartridges: Porous vs Non-Porous Inks on PET/PP

First-pass read rate: Target ≥99.5% on in-line scanners/verifiers.
Mean time between purges: Hours (not minutes) when decap ≥8–12 h.
Smear events per 10k prints: Target 0; inspect product contact points if rising.
Dyne decay: Track vs run length; re-treat if PP falls <38–40 dyn/cm.

Troubleshoot the system: blurred edges after format change → check bracket rigidity; misplaced code → inspect product sensor/encoder; ragged 2D after lunch break → validate decap and RH/temperature; random missing nozzles → purge/prime sequence, cartridge age, and capping discipline.

Interactive Suite — TIJ Cartridges: Porous vs Non-Porous Inks on PET/PP

Quiet Zone & Module Helper (1D/2D)

Symbology:

Module (X) Size (mm):

Quiet Zone (each side) (mm): — 1D: ≥10×X; DataMatrix: ≥1 module

Minimum Symbol Width/Height (mm): — Approximate based on selected matrix

Decap Pause Risk (Open-Nozzle)

Cartridge Decap Rating (h):

Longest Planned Pause (h):

Room Relative Humidity (%):

Pause Tolerance Verdict:

Recommendation:

Note: Margin adjusted for RH. Low RH accelerates drying; high RH slows it.

Ink Cost per Code (Rule of Thumb)

DPI (text):

Average Coverage (%):

Cartridge Cost (USD):

Cartridge Volume (ml):

Approx. Prints per Cartridge: codes — Lower dpi & coverage → more prints

Ink Cost per Code (USD):

Corona Watt Density (Web Treating)

Power (kW):

Web Width (m):

Web Speed (m/min):

Watt Density (W·min/m²): — Typical 0.5–2.0 W·min/m² (application-dependent)

Hint:

Dyne Decay Trend (Rule of Thumb)

Initial Dyne After Treatment (dyn/cm):

Hours Since Treatment:

Decay Factor (0.00–0.04 per hour):

Estimated Current Dyne (dyn/cm): — If <38–40 on PP, re-treat

Treatment Sufficiency:

Curvature vs Throw Distance

Bottle/Cap Diameter (mm):

Throw Distance (mm):

DPI:

Arc Across Swath (mm): — Larger arc → more defocus risk

Dot Spread Risk:

Qualification Protocol — TIJ Cartridges: Porous vs Non-Porous Inks on PET/PP

Requirements: Resolution (300–600 dpi), code types (expiry/lot/GS1 2D), verifier thresholds, environment (RH/temp, condensation, oils).
Substrate baseline: Measure dyne (ASTM D2578). For PP <38 dyn/cm, plan pretreat; record resin, slip/anti-stat, mold/tool for caps/films.
Ink shortlist: Two to three non-porous cartridges with documented decap and plastic adhesion; request samples for your exact parts.
Off-line screening: Print on panels; run tape (cross-hatch), 60 s wet rub, oil rub, 10–20 min condensation; rank and down-select.
Line integration: Rigid brackets; encoder/sensor tuned; standoff 3–5 mm; ESD and guarding to prevent early contact.
On-line validation: Increase speed until smear; capture speed-vs-grade curve; add verifier scans each N minutes.
Documentation: One-page SOP (ink lot, dpi, speed, dry time, treatment power, tests, pass/fail) with photos & verifier reports.

Acceptance Criteria (paste into your SOP)

Tape: No coating lift inside hatch.
Wet rub: 60 s under light load; characters intact.
Oil rub: 30 s edible oil; legible.
Condensation: 10–20 min; no bleeding/whitening.
Barcode: GS1/ISO grade ≥1.5 (or customer-specified).

Deep-dive test methods live at cluster: smear/scratch/abrasion tests. Symbol compliance at customers' gates is covered in cluster: barcode readability (ANSI/ISO). Bundling consumables across technologies? See cluster: TIJ + TTO + labels bundle, and for flexible labels, cluster: TTO ribbon selection. Start broader with the pillar: Coding & Marking Consumables.