Built to Last: How ASA and HRTP Preserve the Performance of Building Materials
2026. 07. 30
Exterior walls that were vibrant when a building was first constructed may fade over time, while cold air may seep through gaps even when the windows are closed. These are changes many of us have encountered in older buildings.
From the moment construction is complete, building materials are constantly exposed to sunlight, wind, rain, and temperature fluctuations. Roofs and exterior walls must withstand intense ultraviolet (UV) radiation, heavy rainfall, and snow, while less visible components such as window gaskets, cables, and hoses are repeatedly subjected to compression, friction, and heat. More recently, climate change has brought more frequent extreme weather, including higher summer temperatures, stronger UV radiation, and localized heavy rainfall, raising performance requirements for building materials even further.
Today, the competitiveness of building materials is no longer assessed solely by their appearance or initial physical properties immediately after installation. Whether they can retain their color and appearance over many years, continue performing under repeated compression and friction, and maintain safety in harsh environments has become increasingly important.
From exterior materials that retain their appearance over time to components that support a building’s performance and safety, LG Chem’s high-performance ASA and HRTP materials help preserve the long-term value of building materials. Here, we take a closer look at both materials.
Depending on where and how they are used, building materials face different conditions, including UV radiation, wind and rain, repeated compression, heat, and friction. Three major factors can shorten their lifespan.
1. Fading and Loss of Gloss
Roofs and exterior walls are exposed to sunlight, wind, and rain throughout the year. Over time, their colors may fade and their gloss may deteriorate, potentially requiring repainting or component replacement. This affects not only the appearance of a building but also its maintenance costs.
2. Reduced Elastic Recovery of Gaskets
Even highly insulated windows can develop gaps if the gasket sealing the glass and frame loses its elasticity. To reduce outside air infiltration and heating and cooling energy loss, a gasket must be able to recover its original shape even after remaining compressed for long periods. Though small and often out of sight, gasket recovery and durability are critical to the airtightness and thermal insulation performance of the entire window system.
3. Harsh Operating Environments
Cables and hoses connecting the inside and outside of a building are continuously exposed to heat, friction, and chemicals. They must retain flexibility and durability even when repeatedly bent or dragged, while delivering stable performance at high temperatures.
As residential EV charging infrastructure expands, cable materials are required to deliver higher levels of heat resistance, flame retardancy, and mechanical strength than ever before. Because these components are directly linked to safety, material selection standards are becoming more stringent.
Ultimately, materials for building applications must combine weatherability that minimizes changes in appearance with the durability and safety needed to maintain performance under compression, bending, friction, and heat.
ASA (Acrylonitrile Styrene Acrylate) is a thermoplastic resin with excellent weatherability.
ASA has a structure similar to ABS, a material widely used for its excellent mechanical properties. The key difference is that components vulnerable to UV radiation are replaced with highly weatherable acrylic rubber, increasing resistance to UV exposure. As a result, ASA helps minimize changes in color, gloss, and physical properties even after prolonged outdoor exposure.
ASA also demonstrates excellent color retention in accelerated weathering tests. LG Chem offers an ASA grade portfolio with different gloss levels for specific applications, including high-gloss LI980, medium-gloss LI970, and low-gloss LI931C and LI971. This allows customers to select the color and surface texture best suited to each product design and operating environment, supporting a wide range of building material requirements.
The difference between conventional plastic exterior materials and ASA becomes clearer after prolonged exposure to outdoor conditions.
Even when conventional plastic exterior materials initially provide adequate physical properties, prolonged UV exposure can lead to discoloration and loss of gloss. Additional processes such as painting may be required to compensate for these changes.
By contrast, ASA incorporates both weatherability and color into the material itself, helping retain color and appearance for longer without painting. This can simplify painting processes, extend repainting and replacement cycles, and reduce the maintenance burden.
ASA is used across many exterior building components, including roofing, siding, decking and fencing, and window profiles.
Roofing is the first part of a building to be exposed to UV radiation, rain, and snow, and it must withstand these conditions over long periods. LG Chem’s LI970 combines excellent weatherability with the ability to achieve a wide range of colors and is used in roofing tiles.
Because siding covers large areas of a building exterior, it must maintain a stable appearance across varying weather conditions. In North America, where daily temperature swings and weather changes can be significant, low-gloss LI931C has been applied to siding products by major building materials manufacturers, demonstrating stable weatherability.
Outdoor structures such as decking and fencing, which come into direct contact with hands and feet, often require a natural surface texture in addition to weatherability. LI971 is used in these applications to create a refined, low-gloss appearance.
Because window profiles are exposed to sunlight over long periods, minimizing discoloration is important. With its low-discoloration properties, LG Chem’s LI968W helps maintain the appearance quality of windows over time.
HRTP (Heat-resistant and Recyclable ThermoPlastic) is a special ultra-high-molecular-weight grade of PVC (Polyvinyl Chloride).
The degree of polymerization indicates the length of the molecular chains that make up a material. As the degree of polymerization increases, the material achieves an ultra-high molecular weight, providing rubber-like flexibility while retaining toughness. Based on this structure, HRTP offers enhanced elasticity and recovery, as well as improved heat and abrasion resistance, compared with general-purpose PVC.
Another distinguishing feature of HRTP is its non-crosslinked thermoplastic structure. Unlike rubber and other crosslinked materials, HRTP can be reheated and reprocessed, making it recyclable, while also providing excellent flame retardancy. These properties make HRTP suitable for building material components that must balance durability, safety, and sustainability.
LG Chem offers a range of grades, including HRTP4000 for window gaskets, cables, and hoses, as well as HRTP2000H and HRTP2000S with enhanced processability.
General-purpose PVC is widely used because it is cost-effective and easy to process, but it has limitations in heat resistance at high temperatures and recovery after repeated compression.
HRTP is a specialty grade designed with an exceptionally high degree of polymerization to address these limitations. It delivers differentiated performance in components where elasticity, heat resistance, and abrasion resistance are critical, such as gaskets subjected to long-term compression and specialty cables and hoses that are bent repeatedly.
In comparisons of materials for EV charging cables, HRTP demonstrated higher tensile strength and heat resistance than TPO and TPU, along with excellent flame retardancy. This differentiated performance is particularly evident in electrical components where heat and fire safety are critical.
HRTP is used in window gaskets, specialty cables, and hoses that must withstand repeated compression, friction, and heat.
Window gaskets seal the space between glass and the frame to reduce outside air infiltration and heating and cooling energy loss. HRTP4000 maintains elasticity and recovery even after extended compression, helping windows maintain airtightness and thermal insulation performance over time.
HRTP4000 for specialty cables offers high heat resistance, flame retardancy, and chemical resistance. It delivers particularly strong performance compared with TPO and TPU in EV charging cable applications.
Because hoses are repeatedly bent and dragged during use, abrasion resistance, flexibility, and chemical resistance are important. HRTP4000 helps improve product durability under these operating conditions.
Do ASA exterior materials require painting?
ASA is typically used without painting because color can be incorporated into the material itself. It can achieve a wide range of colors and gloss levels, from high gloss to low gloss, without a painting process, helping simplify production and reduce maintenance. LG Chem also provides customized color solutions through its global color system.
Can HRTP be processed using standard PVC equipment?
HRTP is a PVC-based material and is generally highly compatible with existing PVC processing infrastructure. However, selecting a grade optimized for the intended application and process is important. Because each grade offers different characteristics, including enhanced processability in HRTP2000S, technical consultation is recommended to select the appropriate grade for the component and process conditions.
What advantages does HRTP offer over rubber materials?
Crosslinked rubber and other crosslinked materials are difficult to recycle after molding, while HRTP, as a non-crosslinked thermoplastic resin, is recyclable. It also combines rubber-like elasticity and recovery with excellent heat resistance and flame retardancy, making it a suitable alternative for building material applications that require both performance and sustainability.
Are ASA and HRTP used only in residential buildings?
No. With their excellent durability and functionality, both materials have the potential to be used in commercial buildings, public facilities, and other applications. Because resilience to extreme weather and ease of maintenance are valued across all building types, their applications are expected to continue expanding.
ASA and HRTP play different roles in building materials. ASA helps exterior materials retain their color and appearance over time, while HRTP supports the performance and safety of key components such as gaskets, cables, and hoses.
As climate conditions become more demanding, building materials must be evaluated not only by their appearance and physical properties at installation, but also by how reliably they maintain their original performance over time. As evaluation criteria expand from initial performance to performance sustained over the long term, the roles of these two materials are expected to become even more important.
Building on its ASA and HRTP portfolios optimized for different building material applications and operating environments, LG Chem will continue strengthening its color design capabilities, comprehensive technical support, and stable global supply network to help enhance the competitiveness of customers’ products.
※Some images in this content were generated using AI.
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