Product

PRODUCT

SEPS (Styrene-Ethylene-Propylene-Styrene Block Copolymer)

Styrene-Ethylene-Propylene-Styrene block copolymer (SEPS), produced by hydrogenating SIS, is one of the main products of Shanghai Haihai Zhonglong Technology Co., Ltd. It offers high transparency, excellent weatherability, aging and heat resistance, and is non-toxic and eco-friendly. SEPS is widely used in premium elastomers, medical devices, cosmetics modification (e.g., shampoo conditioners) and high-end adhesives.

Product consultation 021-56070698

Physical Properties

SEPS is the hydrogenated product of SIS (styrene-isoprene-styrene), which retains the processing convenience of thermoplastic elastomers while significantly improving aging and yellowing resistance.

Excellent transparency
SEPS has very high optical transparency and low haze, being one of the few thermoplastic elastomers combining rubber elasticity with a transparent appearance.
Rubber elasticity with plastic processability
It shows high rubber elasticity at room temperature and can be thermoformed when heated, combining the flexibility of rubber with the easy processing of plastics.
Ozone, UV and heat-aging resistance
The saturated ethylene-propylene segments give SEPS outstanding weather resistance and thermal-oxidative resistance, with little yellowing during long-term use.
Non-toxic, odorless, food & medical grade
With minimal residual double bonds, low odor and low extractables, it meets food-contact and medical-grade requirements.

Main Applications

With transparent, weather-resistant and safe properties, SEPS is widely used in several high-end fields:

Transparent Adhesives & PSAs
SEPS offers high transparency and good adhesion, making it an ideal base for high-end transparent pressure-sensitive adhesives, label adhesives and medical tapes.
Transparent Packaging, Labels & Film
Suitable for transparent boxes, anti-counterfeit labels and high-gloss films with strict appearance and weather-resistance requirements.
Medical & Cosmetic Materials
Low extractables and non-toxic/odorless, it can be used for medical catheters, cosmetic conditioners and skin-contact products.
Footwear & Plastic Modification
As a toughening modifier for footwear and plastics, it improves elasticity, transparency and impact resistance.

Differences & Application Comparison: SEPS vs SBS / SEBS / SIS

vs SBS: SBS is a styrene-butadiene-styrene block copolymer containing unsaturated double bonds, with ordinary weather and heat resistance; SEPS is the hydrogenated product with yellowing and ozone resistance plus high transparency, better suited to outdoor and transparent products.

vs SEBS: SEBS is the hydrogenated product of SBS with ordinary transparency; SEPS is derived from hydrogenated SIS, offering superior transparency and lower haze, with advantages in transparent adhesives and medical fields.

vs SIS: SIS contains many unsaturated double bonds, prone to yellowing and poor weather resistance; after hydrogenation SEPS has higher saturation, combining SIS adhesion with better aging and yellowing resistance.

Product	Structure	Transparency	Styrene %	Shore A	Typical Features & Uses
SEPS	Linear/Star (hydrogenated SIS)	High transparency	15–30	60–90	Transparent adhesives, medical, labels, packaging film
SBS	Linear/Star	Opaque/Milky	30–40	70–95	Footwear, asphalt modification, rubber goods
SEBS	Linear/Star (hydrogenated SBS)	Semi-transparent	30–40	65–95	Plastic modification, auto parts, toys
SIS	Linear	Semi-transparent	15–25	50–80	Pressure-sensitive adhesives, labels, tapes

Safety Information

(1) Hazard overview: SEPS itself is low-toxicity and low-odor, with high safety under normal use; however, high-temperature processing (>200°C) may generate fumes, which should be avoided by inhalation.

(2) Storage: Store in a cool, dry, ventilated place, avoiding direct sunlight and high temperature; unopened original packaging can be stored long-term, and after opening protect from moisture and dust.

(3) First aid: Move to fresh air if discomfort from processing fumes; wash skin with water; if into eyes, rinse with plenty of water and seek medical attention.

(4) Fire fighting: It is a combustible pellet; use dry powder, foam or carbon dioxide extinguishers; molten material may splash on contact with water, so direct water spraying is prohibited.

(5) Personal and environmental protection: Local exhaust should be provided in high-temperature processing areas; operators wear heat-resistant gloves and goggles; waste is recycled as general plastic, avoiding incineration that produces harmful gases.