Soft touch plastics are designed for comfort, grip and flexibility, and the right process oil can make a big difference in how they feel, look and perform. Here’s what manufacturers should know. Questions? Contact us.
Soft touch plastics are everywhere we interact with manufactured products: the grip around a medical device, the console inside a vehicle, the handle on a tool or the flexible surface on a consumer product.
Manufacturers use these materials to add comfort, grip, flexibility and a higher-quality feel, and producing that feel consistently depends on more than choosing the right polymer.
For many thermoplastic elastomer (TPE) formulations, process oils play an important role in creating the desired softness while supporting processing, appearance and long-term performance.
Choosing the wrong oil can contribute to problems ranging from excessive tack and poor wear resistance to oil migration, fogging and color changes.
What Are Soft Touch Plastics?
“Soft touch plastics” is a broad term rather than a single class of materials. Manufacturers can create a soft surface through coatings, flexible foams, thermoplastic elastomers and other material systems.
TPEs are particularly useful because they combine some of the elasticity and flexibility associated with rubber with the manufacturing advantages of thermoplastics. Depending on the formulation, they can be injection molded, extruded or overmolded onto a harder plastic substrate.
That makes them useful across many markets. These are just a few examples.
Automotive Interiors
TPE compounds can be found in console mats, cupholder liners, overmolded knobs and grips, bezels, instrument panels and door trim. They’re important for everything from fuel economy (as lightweight compounds help reduce the overall vehicle weight) to passenger comfort and safety.
Research into SEBS/polypropylene TPEs for automotive interior skins has focused on how important TPE composition is to not only softness, but also flow, mechanical strength, scratch resistance, low odor, low interior emissions, and low fogging.
“[Soft-touch polypropylene] enriches the tactile experience and enhances comfort, providing extra value to the automotive consumer, without compromising design or functionality.” — Ramesh Iyer, Vice President of Commercial Operations, Asahi Kasei Plastics
Medical Equipment
TPEs can provide flexible tubing, seals, soft patient-contact surfaces and overmolded grips. They offer medical designers a broad range of “soft-feel” materials that can be combined with other polymers through processes such as coinjection molding and coextrusion.
Soft touch TPEs can also appear in industrial tools, grips, sporting goods, appliances, packaging, wearable products and other molded consumer goods where manufacturers need a combination of tactile feel, durability, color and processability.
Industrial Tools and Equipment
TPEs are commonly used on handles, knobs, levers and grips where operators need both comfort and control. Soft-touch TPE surfaces can improve grip in the presence of moisture or grease while also helping absorb vibration and reduce hand fatigue during repetitive work.
For example, industrial component manufacturer Elesa uses TPE coatings on machine handles and controls specifically for secure grip, ergonomics and vibration absorption.
What Goes Into Manufacturing Soft Touch Plastics?
The recipe depends heavily on the end use, but many soft-touch TPE formulations contain several basic components:
- As a block copolymer, there is a rigid thermoplastic and a soft rubbery phase
- A TPE, such as styrene-ethylene-butylene-styrene (SEBS) has rigid styrene polymer and soft ethylene-butylene elastomer
- Sometimes an additional stiff polymer like polypropylene (PP) is added
- A plasticizer or process oil to further soften the elastomer phase
- Fillers
- Pigments or colorants
- Stabilizers and antioxidants
- Other additives selected for properties such as ultraviolet resistance, adhesion, slip or abrasion resistance
The ingredients are compounded under controlled heat and shear to form a uniform material. The resulting compound may then be injection molded into a finished component, extruded into a profile or overmolded onto a rigid substrate.
The challenge is getting all those ingredients to work as a system.
For example, researchers studying automotive SEBS/PP TPEs found that changing the SEBS-to-PP ratio, polymer structure and oil loading could affect hardness, melt flow and wear performance.
That is why “soft” cannot be the only specification.
Plasticizers Help Give Soft Touch Plastics Their Feel
Plasticizers reduce interactions between polymer chains, allowing greater molecular movement and creating a softer, more flexible compound. In many TPE systems, mineral oils can perform this plasticizing role while also serving as processing aids.
Academic research on olefinic TPEs (made from olefins)—often used in automotive applications—has found that processing oil can lower hardness and improve processability. In SEBS/PP compounds, paraffinic oils can affect both rheological (how a material flows and deforms under force) and final mechanical behavior.
But adding more oil does not automatically create a better soft-touch product.
In one automotive-interior study, hardness decreased as paraffinic-oil loading increased up to an oil-to-SEBS ratio of roughly 1:1. Researchers also found that higher oil loading could increase surface stickiness and sticky wear, reducing abrasion resistance.
The lesson for compounders is simple: oil quantity matters, but oil quality and chemistry matter too.
Choosing the Right Process Oil for Soft Touch Plastics
A process oil needs to be compatible with the polymer system while supporting the properties manufacturers need from the finished product.
Depending on the application, buyers may need to consider:
- Viscosity and molecular weight. Lower-viscosity oils may improve flow and processing, while higher-molecular-weight options can be useful when retention and lower volatility are priorities.
- Compatibility and solvency. Poor compatibility may contribute to migration, blooming, inconsistent mechanical properties or changes at the surface.
- Volatility. This becomes especially important for automotive interiors and other enclosed environments. Escaping oil can contribute to fogging, odor, emissions and unwanted deposits.
- Color and color stability. Clear, white, translucent or carefully color-matched soft touch plastics can expose even small differences in process oils. (We discuss these considerations further in our guide to color-stable process oils for TPE manufacturers.)
- Migration resistance. Extender-oil composition can also change the material’s microphase structure as well as mechanical properties, thermal behavior and oil-migration resistance.
These considerations become even more important when soft-touch components must survive heat, ultraviolet light, cleaning products, repeated handling or years of service.
Better Soft Touch Plastics Start With the Right Supply Partner
The end-user may never know which process oil went into a dashboard grip, medical-device handle or molded consumer product. But they will notice when that product feels sticky, yellows, develops an odor or no longer feels the way it did when it was new.
That puts a lot of responsibility on a seemingly small part of the formulation.
Renkert Oil helps TPE and polymer manufacturers match process oils to their specific performance requirements. Our portfolio includes premium Chevron ParaLux oils, Renoil low-volatility oils and other specialty products with different viscosity, volatility, purity and performance profiles.
Just as important, we help customers look beyond a product data sheet. Our experienced technical team can help you evaluate factors including polymer compatibility, color stability, volatility and finished-product requirements.
Strategically located inventory and an established specialty-oil supply network also help keep material moving when production depends on consistent availability.
When you are developing soft touch plastics, softness is only the beginning. Contact Renkert Oil to discuss the right process oil for the way your compound needs to process, feel, look and perform.
FAQs: Soft Touch Plastics
- What are soft touch plastics?
Soft touch plastics are polymer materials designed to provide a softer, more comfortable or more secure surface than conventional rigid plastics. Thermoplastic elastomers, or TPEs, are commonly used for these applications. - Where are soft touch plastics used?
Soft touch plastics can be found in automotive interiors, medical devices, industrial tools, consumer products, sporting goods, appliances and other products where grip, flexibility or tactile feel matters. - What are soft touch plastics made from?
Formulations vary, but many soft-touch TPEs are comprised of a block co-polymer with soft elastomer portion grafted onto rigid thermoplastic such as styrene or polypropylene. Process oil or plasticizer and additives such as stabilizers, pigments and fillers complete the formulation. - Why are process oils used in soft touch plastics?
Process oils can help lower hardness, as well as improve flow and make TPE compounds easier to process. They can also influence the finished material’s flexibility, surface feel and mechanical properties. - How does process oil affect the softness of a TPE?
Increasing oil content can generally make an oil-compatible TPE softer by swelling the soft elastomer portion within the polymer system. However, excessive oil can contribute to unwanted effects such as tackiness or reduced wear resistance. - Can process oil migrate out of soft touch plastics?
Yes. Oil migration can occur if the process oil is poorly matched to the polymer system or formulation. Selecting an oil with appropriate compatibility, molecular weight and volatility can help reduce migration concerns. - Why does process oil volatility matter?
Lower-volatility oils can help reduce the amount of material that evaporates from a compound during processing or use. This can be particularly important in applications where odor, emissions, fogging or long-term oil retention matter. - Does process oil affect the color of soft touch plastics?
It can. For light-colored, clear or carefully color-matched compounds, manufacturers may need a highly refined, color-stable oil to help maintain the desired appearance during processing and over time. - What type of process oil is used with SEBS TPEs?
Highly refined paraffinic oils are commonly used with SEBS-based TPE formulations, although the right product depends on the polymer system and desired performance characteristics. - How can Renkert Oil help manufacturers select a process oil?
Renkert Oil offers specialty oils for polymer and elastomer applications, including low-volatility and color-stable options. We can help manufacturers evaluate factors such as viscosity, volatility, compatibility, color stability and finished-product requirements.