Thermoplastic TPC-ET and specialty hotmelt adhesives

Thanks to its high competence in polymer chain modification, Sipol offers tailor-made materials designed to match each application requirements

The Sipol production plant in Mortara (Italy)

Sipol SpA is a privately owned Italian company whose core business is the polymerization of high performance polymers dedicated to both the adhesive and the engineering plastics domains. The company currently sells 25 million euro of specialty polymers developed and manufactured at its plant in Mortara (about 40 km west of Milan, Italy). Its main activities are the development and manufacturing of thermoplastic ether-ester elastomers (TPC-ET) and specialty hotmelt adhesives (co-polyester and co-polyamide based).
Sipol’s business policy is based on marketing its superior competence in polymer chain modification.

Depending on application needs, the R&D department creates new copolymers by inserting different blocks (co-monomers) into the polymer chain; this produces tailor-made materials designed to match application requirements with the level of business flexibility that only a medium-sized company is able to offer.

The Sipolprene family

In 2002 the company introduced Sipolprene® as trade brand for its thermoplastic ether ester elastomer range (TPC-ET), achieving in over 10 years of activity an excellent reputation in a niche market, in a field where the number of companies with proprietary chemical know-how is extremely limited worldwide.
These engineering polymers are made through the macromolecular combination of rigid polyester blocks (crystalline segments) and flexible long-chain polyether blocks (amorphous segments).

This combination grants the polymer a unique behavior as the rigid part of the molecule develops intermolecular associations with the other rigid segments, providing the dimensional stability and the mechanical properties of a semicrystalline polymer, while the flexible part, with its relatively low glass transition temperature, imparts elastomeric properties to the material.
Tipically the crystalline part of a TPC-ET is a PBT short chain (or a modified PBT) and the amorphous component is a polyether based on polytetramethylene ether glycol (PTMEG). The ratio of the two components as well as the length of their polymer chains provides the product different combinations of hardness, melting point and other distinctive properties.

Sipol’s polymerization know-how in regard to hot melt adhesives and its familiarity with the building of a polymer chain using different co-monomers like in toy blocks, enabled the company to develop several Sipolprene grades through the variation of the macromolecular composition.

Sipolprene’s characteristics
The Sipolprene family offers a good balance of characteristics, which can be briefly summarized as follows: • performances over a temperature range from -40 °C to +120 °C; • excellent flexibility with high-impact strength even at low temperatures; • high mechanical strength; • good resilience; • excellent wear resistance; • high resistance to chemicals (e.g. organic solvents, gasoline, naphtha, light acids, sea water and zinc chloride solution); • excellent surface gloss and good paintability; • easy welding with several techniques (e.g. spin, ultrasonic, and hot-plate); • printable using sublimation inks, pad printing and silk screening; • laser markable with the most conventional techniques; • suitable for sterilization with gamma radiations, ethylene oxide and steam autoclave (harder types); • availability of stabilized versions providing an increased resistance to heat, UV, hydrolysis, NOx and copper contact.

Chemical and physical characteristics

The Sipolprene standard portfolio of products covers a range in hardness levels going from ShD 25 up to ShD 72 with melting temperatures between 170 °C and 220 °C, where all grades share a common “polyester” backbone which provides superior chemical and thermal resistance.
In addition to the traditional Sipolprene range, Sipol has been continuously adding specialty grades providing a unique performance, like Sipolprene® 35150 (TPC-ET low melting point suitable for PVC modification), Sipolprene® 55211 (TPC-ET with improved rate of hardening for ultra- high-speed injection molding) and the Sipolprene® B series, showing a moisture absorption value greater than 15 percent (breathable products).

Sipolprene is utilized for making low noise gears, covers, pulleys, distribution valve bodies, and cable jacketing

Easy processing

The entire Sipolprene® range provides a combination of sharp melting points typical of every single product with an excellent melt stability; this combination allows easy and reliable product processing in various injection molding techniques, pipe extrusion, film extrusion, monofilament extrusion and rotomolding (powder).

In injection molding, which is the most common technology used to process Sipolprene®, the rheological behavior of the polymer shows curves of viscosity vs. nearly flat shear rate (non Newtonian), allowing the stable flow of molten polymer through mold restrictions found in complex molds and in multi-cavity molds without the over-heating, and consequent degradation, of the polymer. The products can be injection molded by means of conventional runners as well as runnerless molds.

The soft nature of Sipolprene and its chemical structure, which allows the development of good compatibility with several rigid engineering plastic products, has made Sipolprene commonly used in 2K molding applications where a “soft touch” is needed and where other thermoplastic elastomers do not provide sufficient adhesion.

The absence of any plasticizer make Sipolprene an excellent polymer for various applications in the consumer goods markets

Applications

Besides the easy and economical processing, there are several benefits to choosing Sipolprene in demanding applications where other TPEs cannot be used because of the high mechanical performance required or because of the working temperature of the parts.

Sipolprene is used in several market fields for industrial applications as well as for consumer goods. Considering its excellent mechanical properties, together with its good thermal and chemical resistance, the automotive segment represents one of the most important areas of application for Sipolprene, which is used to make gaskets, door latch covers, special connectors, clips, vibration absorbers, thermoplastic hoses, trim rods, monofilaments for seats support and many other types of products.

Another important area of application is the industrial segment where Sipolprene is utilized for making low noise gears, covers, pulleys, distribution valve bodies, and cable jacketing.
Its suitability for food contact and the absence of any plasticizer make it an excellent polymer for various applications in the consumer goods markets where Sipolprene is used to make kitchen tools, toy components, valves for packaging, body-care equipment, and in many other specialized applications.

Hot-melt adhesives

As for hot-melt adhesives, Sipol operates with special co-polyesters and co-polyamides (dimeric acid based) specifically designed for many industrial sectors, like the footwear industry, where the company is a worldwide leader with regard to the production of long-lasting products, and automotive filters, where Sipol is one of the best known worldwide players.

All the hot-melt adhesives specifically designed for textile lamination are marketed under the trade name Sipoltex®, while all the other grades are under the trade name Technipol®.

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