A Guide to Manufacturing Inflatables with Thermoplastic Polyurethane (TPU)
Embracing Thermoplastic Polyurethane
Thermoplastic Polyurethane (TPU) stands at the forefront of inflatable manufacturing. Commanding a premium for its unparalleled blend of quality and sustainability, TPU embodies a move towards a lower environmental footprint without compromising on luxury or performance.
This forward-thinking material offers a radical alternative to traditional plastics like PVC, setting a new standard for eco-conscious manufacturing in the superyacht industry. Embracing TPU represents a conscientious choice for those who value innovation and are willing to invest in a cleaner future.
Our team is on hand to answer your questions; however, if they relate to the fundamentals of thermoplastics, the intricacies of TPU film manufacturing, or the material’s comprehensive benefits, we invite you to consult our detailed guide for a swift insight.
Contents
- How is Thermoplastic Polyurethane formed?
- Where does the name Thermoplastic Polyurethane come from?
- How do Thermoplastic and Thermoset Polyurethanes compare?
- How is a roll of TPU film manufactured post-polymerisation?
- What manufacturing techniques can be used in the processing of TPU pellets?
- Where can you find everyday examples of Thermoplastic Polyurethane?
- What are the advanced material properties of TPU?
- What are the environmental credentials of TPU?
- Which materials with a higher environmental impact can TPU replace?
- How do you use TPU in the construction of your inflatable platforms?
How is Thermoplastic Polyurethane formed?
Thermoplastic Polyurethane (TPU) is a derivative of Thermoplastic Elastomers (TPE), a general term for a class of materials designed to display characteristics of both plastic and rubber.
Creating TPU involves a reaction between two chemical compounds: diisocyanate (di-iso-cyan-ate) and diols (di-ols). Individually, these compounds are known as monomers. The product of the chemical reaction is the formation of a copolymer (that is, a ‘polymer’ derived from more than one monomer). The constitution of the copolymer is a viscous resin.
The copolymer can be formulated so that when processed, it exhibits properties that are both amorphous, meaning ‘without a clearly defined shape or form’ (giving TPU its elasticity), and crystalline, where atoms are arranged in an ordered way (giving TPU its strength and rigidity).
Other types of TPE include Thermoplastic Polyolefins (TPO), Thermoplastic Vulcanisates (TPV), and Thermoplastic Copolyesters (TPE-E).
See also
British Plastics Federation: How Is Plastic Made?
Xometry: 7 Types of Thermoplastic Elastomers
Where does the name Thermoplastic Polyurethane come from?
The term “thermo” refers to the application of heat.
The term “plastic” comes from the Latin “plasticus,” which means ‘capable of being moulded or shaped’.
Together, thermoplastic implies malleability under heat.
The word “poly” indicates ‘more than one’. This refers to the chemical reaction that bonds multiple elements together (our diisocyanate and diols) in a process known as polymerisation.
“Urethane” is a colourless crystalline compound that can become hard or soft.
Together, polyurethane indicates more than one compound.
Overall, the name Thermoplastic Polyurethane refers to a material made of more than one chemical compound that can be manipulated under heat.
The significance in relation to sustainability is that TPU is a thermoplastic and not a thermoset. A thermoplastic can be reheated and remoulded, while a thermoset plastic cannot.
How do Thermoplastic and Thermoset Polyurethane compare?
Thermoplastics form linear molecular chains during polymerisation. These chains do not interlink, allowing the product to be returned to a liquid form. This is why TPU is often described as ‘melt-processable’.
Thermoset plastics, on the other hand, form cross-linking molecular chains during polymerisation.
Once a plastic with cross-linking chains has cured, it cannot be altered. While this grants exceptional durability with heat and chemical resistance, it also means that once shaped, it cannot be melted down for recycling, limiting its versatility.
Common examples of thermoset materials include silicone, fibreglass, vulcanised rubber, and melamine.
How is a roll of TPU film manufactured post-polymerisation?
Following polymerisation, the synthetic resin is cooled and pelletised. The pellets are then dried to remove any moisture that may cause defects in the final film.
The dried pellets are melted and then forced through an extrusion line, shaping the molten TPU into a film. The sheet film is fed through a quenching tank and onto rollers to cool. Our TPU has a surface lamination applied to create an ultra-durable product for use in saltwater environments.
We construct our inflatable platforms and sea pools using a Drop-stitch or Double-Wall Fabric (DWF) method. This design features a top and bottom layer of TPU film bonded to thousands of polyester yarns, ensuring exceptional rigidity upon inflation.
What manufacturing techniques can be used in the processing of TPU pellets?
Once pelletised, TPU can be processed using various manufacturing techniques, including injection moulding, blow moulding, and extrusion.
Where can you find everyday examples of Thermoplastic Polyurethane?
Thanks to a raft of advanced material properties, Thermoplastic Polyurethane is used in a spectrum of everyday applications. Tangible examples include the soles of trainers, bicycle saddles, backpacks, exercise and play mats, watch straps, and medical devices such as oxygen masks. In the US, the Food and Drug Administration can certify specific grades of TPU for Food Contact (FC).
What are the advanced material properties of TPU?
There are two grades of TPU films: Polyester TPU and Polyether TPU.
Since our products are designed to be used in contact with water, we use Polyether TPU, which boasts enhanced moisture resistance.
Both grades of TPU offer comparable benefits, including:
– High abrasion resistance
– High tenacity and tear strength
– Chemical and oil resistance
– Low-temperature durability
– Excellent shaping properties
– Suitability for bonding
What are the environmental credentials of TPU?
Bio-sourced raw materials
The raw materials required for polymerisation can be derived from renewable or recycled sources. Using bio-sourced polyols and diisocyanates can make manufacturing TPU less dependent on fossil fuels.
Low toxicity
TPU is void of hazardous substances like Vinyl Chloride, asbestos, mercury, lead, and latex. Its formulation also eliminates the need for plasticisers. Thus, it’s free from toxic phthalates, known as disruptors of hormonal balance. Furthermore, it does not emit dioxins upon incineration, safeguarding environmental health.
See also
Health Care Without Harm: Why PVC remains a problematic material
Energy-efficiency
TPU stands out as an energy-efficient choice compared to alternatives like PVC due to its intrinsic flexibility. The natural elasticity of TPU eliminates the need for plasticisers (chemical compounds added to polymers to improve their workability and durability), streamlining the manufacturing process. With fewer components requiring processing and the ability to operate at reduced temperatures, TPU requires less energy throughout the production line.
Recyclability
Thermoplastic polyurethane films can be recycled. The key to recycling TPU films efficiently lies in separating the different components. Once separated, polyurethane films can undergo methods such as shredding, tearing, cutting, and grinding to create more granular forms (such as powders, pellets, or flakes). This preparation facilitates easier reintegration into new products. Additionally, the polyester yarns we use for enhanced strength and durability are also recyclable.
See also
Royal Society of Chemistry: Recycling of polyurethanes: where we are and where we are going
Salvation Army: Salvation Army plans first commercial-scale polyester recycling facility
Reusability
Recycling, while beneficial, often comes with significant costs and energy demands. In our commitment to fostering a circular economy, we’ve chosen a different path by crafting duffle and weekend bags from reclaimed TPU material. The inherent durability of TPU allows us to create bags designed not just for aesthetic appeal but for enduring performance, ensuring a product that stands the test of time and reduces its environmental footprint.
Which materials with a higher environmental impact can TPU replace?
- Polyvinyl chloride (PVC): TPU can replace PVC in insulation, footwear, and automotive parts.
- Rubber: TPU can replace natural rubber in seals, gaskets, and hoses.
- Leather: TPU can replace leather in clothing and automotive interiors.
- Nylon: TPU can replace nylon in sports equipment and textile coatings.
- Polycarbonate (PC): TPU can replace PC in protective cases and electronic components.
How do you use TPU in the construction of your inflatable platforms?
Drop-stitch construction
Drop-stitch, or Double-Wall Fabric (DWF), is a 3D construction method for making ultra-firm inflatables. This method involves thermally bonding thousands of polyester yarns, evenly spaced, between a top and bottom layer of TPU. This technique, complete with robust TPU sidewalls, results in a consistent depth and shape upon inflation. Our drop-stitch construction ensures our products boast an exceptional strength-to-weight ratio, unmatched air tightness, and superb stability underfoot.
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