Comparison of Self-Adhesive Film Processes for Keton SEBS (G1542 / G1645 / G1646)

I. Basic Physical Properties Comparison Table

Project	Kraton G1542	Kraton G1645	Kraton G1646
Material Type	SEBS thermoplastic elastomer	SEBS thermoplastic elastomer	SEBS thermoplastic elastomer
Styrene content	≈18%	≈30%	≈31%
Shaw A Hardness	65	85	87
PS hard segment Tg	90~95℃	92~98℃	93~99℃
EB soft segment Tg	-55℃	-58℃	-58℃
Vicat softening point	≈78℃	≈93℃	≈95℃
Safe processing range	190–225℃	200–230℃	205‑235℃
Melt Degradation Alert Temperature	>260℃	>265℃	>265℃
Short-term peak temperature resistance	125℃	140℃	145℃
Long-term safe operating temperature	≤100℃	≤115℃	≤120℃
Processing difficulty	Low	Medium	High (prone to watermarks)

II. Definition of Shore Hardness (Technical Explanation)

Shaw’s A hardness represents the rigidity index of SEBS elastomers:

Hardness ↑ → Higher cohesion, improved temperature resistance, and reduced risk of high‑temperature residual adhesive.
Hardness ↓ → The material is softer and offers better initial adhesion, but its heat resistance and high‑temperature tack are relatively weak.
G1542 (65A): Soft formulation, excellent initial adhesion, suitable for ambient-temperature protective applications.
G1645 (85A): A balanced, all-purpose formulation that balances adhesion with high-temperature resistance and excellent residue‑free performance.
G1646 (87A): A high-rigidity, high-temperature‑resistant specialty material, suitable for high‑temperature baking processes.

III. Reference for On-Machine Film-Blowing Process

Process parameters	G1542	G1645	G1646
Barrel set temperature	200–215℃	210–225°C	215–230℃
Actual controlled temperature of the melt	≤220℃	≤230℃	≤235℃
Formula Adjustment Recommendations	A small amount of PP309 improves foaming.	Low-additive PP, shear heat control	Low-shear screw, rigorously controlling thermal degradation.
Screw Design Direction	Improved BM screw, mid-section mixing	Low-shear dedicated screw, with a large groove-depth metering section.	Low-shear structure; mixing is carried out in the melt phase, with strong shear avoided at the downstream end.

IV. Product Selection & Customer Application Recommendations

Raw material grade	Positioning	Applicable Product Scenarios
G1542	Economy-class room-temperature model	Floor tiles and standard stainless steel sheets, stored under ambient conditions for protection.
G1645	Mainstream high-end model	Aluminum panels and coated sheets, medium-to-high temperature processing operations
G1646	High-Temperature-Resistant Special Edition	Powder coating and high-temperature embossing processes, with no residual adhesive required at 110–120°C.

V. Short Sales Scripts

For Shao’s products, the higher the A‑hardness, the less likely residual adhesive will remain after high‑temperature processing; conversely, lower hardness results in a softer film with better initial adhesion to the substrate. For standard room‑temperature protection, choose 1542; for mid‑to‑high‑end temperature resistance, select 1645; and for high‑temperature baking‑paint applications, prioritize 1646.

VI. Key Points for Production Warnings

SEBS is prone to degradation, yellowing, and the formation of watermarks and crystalline defects when exposed to temperatures exceeding 260°C.
High-hardness grades 1645/1646 prohibit the use of high-shear screws, and the metering section groove depth must not be too shallow.
To improve the film‑forming and encapsulating performance, a small amount of PP309 can be added; however, excessive addition will reduce adhesion.

Yanshan Petrochemical F8403 (PP) Specification

Corrected grade: The full name is Yanshan Petrochemical F8403.

Basic Positioning

Block copolymer impact‑resistant PP, a film‑grade resin suitable for both blown‑film and cast‑film processes, featuring low crystal points, excellent retort resistance, and superior impact toughness. Melt index ≈ 2.5 g/10 min (230°C), with good melt strength.

Can it be blown into a film? Is it easy to process?

It can be used for blown film, but PP blown film must be… Downward-blowing water-cooling process . With conventional PE blown‑film cooling units, directly using pure F8403 results in an unstable bubble, poor cooling, a tendency for the bubble to stick, low transparency, and difficulty in achieving proper orientation.

✅ Advantages

The melt strength is stable, making it suitable for blending with SEBS to formulate high-temperature‑resistant self‑adhesive films.
Excellent impact resistance; the finished product exhibits high temperature resistance (suitable for steaming and boiling at 120°C).
Excellent gel and crystal‑spot control, with a clean film surface.

⚠️ Processing Challenges

Cooling requirements are stringent; air cooling is difficult to achieve effectively, so water cooling is preferred for shaping.
Extrusion temperature is higher than that for PE: barrel 200–230°C, die 220–235°C.
Pure PP film is relatively stiff and feels brittle when blown on its own; blending it with SEBS (1645/1646) is highly suitable, as it improves bubble formation and enhances heat resistance.

Practical Conclusions on Self-Adhesive Film Production

Pure F8403 blown film production alone: difficult to achieve (air‑cooled machine is unsuitable)
As a formulation‑grade processing aid (added at 5–15% in SEBS/PE blends): excellent processability!
Conventional five‑layer blown‑film extruder: Do not run at 100% F8403; a small amount of blend modification (5–12%) is most suitable.

Grade	Type	Features
F8403	Copolymer PP	Excellent toughness and superior temperature resistance, making it suitable for high-temperature‑resistant self‑adhesive film formulations.
PP309	Homopolymer PP	Greater rigidity, enhanced hardness, and a more pronounced improvement in foam formation.

Machining Process Reference (Blending and Additive Version)