H646 Non-Corrosive Plastic Ink

What ink is suitable for solvent-sensitive plastic?

Evaluate an ink whose documented substrate scope and solvent system fit the exact resin, grade and molded part. H646 is a single-component system developed for confirmed solvent-sensitive plastics, especially PC and PS, subject to actual-part testing.

What ink can be evaluated for screen printing on PC?

H646 can be evaluated on PC within its confirmed scope. Check the actual grade, molded-in stress, surface condition, ink deposit, drying, adhesion, substrate integrity and final appearance before production.

What pad-printing ink should be considered for PS?

For an existing H646 screen or pad printing application, confirm the exact PS grade, molded part, transfer conditions, deposited film, drying and required appearance. Compatibility cannot be inferred from the resin name alone.

What should be checked before printing stress-sensitive plastic parts?

Confirm the exact resin and grade, actual molded part, internal stress, surface condition, solvent sensitivity, printing process, film thickness, drying, adhesion requirement, substrate-integrity requirement and final appearance.

Why does ink selection matter more on solvent-sensitive plastics?

An ink must form and adhere without causing unacceptable whitening, crazing, cracking, haze, deformation or other visible damage. The balance depends on the actual part and process.

Why does PC develop fine cracks after printing?

Possible factors include solvent sensitivity, molded-in stress, resin grade, part geometry or molding condition, ink-solvent interaction, deposited film and printing conditions. A crack is not automatically caused by one factor, so inspect the actual part and process.

Why does PS turn white or hazy after printing?

Whitening or haze can be associated with solvent attack, substrate stress, the actual PS grade, ink compatibility, printing conditions and film thickness. Diagnose these factors on representative molded parts.

Why can crazing appear after the print initially looks normal?

A good initial appearance does not confirm longer-term compatibility. Delayed stress response, solvent interaction, molded-part stress, drying and later exposure conditions should be included in the evaluation.

Why can the same ink affect one PC part but not another?

Resin grades, additives, wall thickness, geometry, molding conditions, internal stress and surface condition can differ. Test each actual production part rather than transferring a result from another PC component.

Can ink have good adhesion but still damage PC?

Yes. Adhesion describes whether the ink film remains attached. Substrate compatibility describes whether the ink and solvent system cause whitening, crazing, cracking, haze, deformation or other visible damage.

Why can a print pass adhesion testing but show cracking later?

An adhesion result does not measure delayed substrate response. Molded-in stress, solvent interaction, film deposit, drying and exposure conditions can affect the part after the initial test.

Should substrate damage be checked separately from adhesion?

Yes. Inspect substrate integrity and appearance independently, then perform the required adhesion test after complete drying on the same representative production part.

What should buyers evaluate besides tape adhesion?

Evaluate whitening, crazing, cracks, haze, deformation, complete drying, final appearance and customer-specific acceptance requirements. Good adhesion alone does not prove substrate compatibility.

How can crazing be reduced when printing on PC?

Confirm the exact resin and molded part, assess internal stress, review the current ink and solvent system, use a suitable lower-aggression system where appropriate, control deposit, complete drying and inspect substrate integrity after printing.

How can stress cracking be reduced on solvent-sensitive plastics?

Test the actual molded part, identify the failure mode, review solvent sensitivity and molded-in stress, control film thickness and drying, and complete a representative production trial before mass printing.

What should be checked if printed plastic is being attacked?

Check the exact grade, part geometry and stress, surface condition, current ink and thinner, printing process, deposit, drying and the timing and location of visible damage.

Does lower solvent aggression solve every cracking problem?

No. It may reduce one source of risk, but resin grade, molding stress, part design, deposit, drying and end-use exposure still require actual-part validation. H646 does not guarantee crack-free results.

Why is the ink still soft after printing?

Review substrate, film thickness, temperature, ventilation and elapsed drying time. H646 drying varies with these conditions; its documented full-drying references are 24 hours at room temperature or 80°C for 30 minutes.

Does incomplete drying affect adhesion?

It can affect the measured result and final film condition. Allow the ink film to fully dry before evaluating adhesion or other performance.

Can heavier ink deposit affect drying and substrate response?

A heavier deposit can change drying time and solvent exposure. For screen printing, work within the documented 100–200T mesh range and select the final setup from the artwork, deposit and actual-part result.

Why should compatibility be checked after full drying?

Final evaluation should include the dried ink film and the substrate condition after the intended process, because initial appearance alone may not reveal delayed response.

What should be confirmed before final evaluation?

Confirm the actual part, ink and recommended thinner system, print deposit, 40–60°C hot-air reference where used, complete drying, substrate integrity, adhesion and final appearance.

How should compatibility with solvent-sensitive plastic be evaluated?

Print representative production parts, complete the intended drying process, then inspect substrate integrity, adhesion and appearance separately against the customer acceptance standard.

What should be checked if adhesion is good but the plastic turns white?

Treat the whitening as a substrate-compatibility failure even if adhesion is acceptable. Review the resin grade, molded stress, ink and solvent interaction, deposit and drying conditions.

How should stress-crack resistance be assessed?

Use the actual molded part and intended process, then inspect for whitening, crazing, cracks, haze, deformation and other visible changes after complete drying and any required conditioning.

What should be confirmed before mass production?

Confirm the exact substrate, current failure mode, ink compatibility, drying, substrate integrity, adhesion, final appearance and customer-specific acceptance criteria through a production trial.

Why inspect both adhesion and substrate condition?

They measure different outcomes. The ink film can remain attached while the underlying plastic develops unacceptable visible damage.

Reference data reflects documented H646 test conditions. Actual performance depends on substrate grade, molded-in stress, surface condition, ink-film thickness, printing process and drying conditions.

When should buyers consider a lower-solvent-attack plastic ink?

Consider it when a confirmed solvent-sensitive plastic application shows or risks whitening, crazing, fine cracks, haze, stress cracking or other substrate damage. The actual material and molded part still require testing.

What should buyers compare when choosing ink for PC or PS?

Compare the exact resin and grade, molded-part stress, solvent sensitivity, substrate compatibility, screen or pad printing process, adhesion, drying, final appearance, actual-part results and available technical support.

Is stronger solvent interaction always better for adhesion?

Not necessarily. On solvent-sensitive plastics, aggressive interaction may increase substrate-damage risk. Selection must balance adhesion, compatibility, film formation, drying, appearance and production stability.

1. 1
   Identify the exact resin

   Confirm PC, PS, PVC, ABS or PMMA within H646's documented scope.

2. 2
   Confirm grade and molded part

   Record the material grade, additives, geometry, wall thickness and actual production part.

3. 3
   Check stress sensitivity

   Consider molding history, internal stress and any mechanical load on the part.

4. 4
   Identify the failure mode

   Distinguish whitening, crazing, cracking, haze, deformation and adhesion failure.

5. 5
   Confirm the printing setup

   Record the existing screen or pad printing conditions and recommended H646 thinner system.

6. 6
   Check ink deposit

   Review film thickness, number of passes and, for screen printing, the 100–200T mesh range.

7. 7
   Verify drying

   Confirm temperature, ventilation and enough time for complete drying before testing.

8. 8
   Inspect substrate integrity

   Check the printed part for visible damage after the intended drying and conditioning.

9. 9
   Evaluate adhesion

   Run the required adhesion test separately on the fully dried production part.

10. 10
    Confirm appearance and acceptance

    Compare the complete result with the customer's final appearance and performance standard.

11. 11
    Select the appropriate system

    Use H646 only when its documented substrate and performance scope fit; otherwise request evaluation of another Hongsheng ink system or formulation.