Uniqlo sells thermal underwear as HEATTECH

Underwear with a name

In 2003 Uniqlo began selling a range of men's innerwear designed to generate and retain heat.^1,2 Thermal underwear was not a new category. What was new was the name on it: HEATTECH, written in capital letters, used from July 2003 and later registered as a trademark of Fast Retailing, Uniqlo's parent company.³ The first season sold 1.5 million units.²

The fabric came from Toray Industries, the Japanese fibre and chemicals company. Toray's own history states that "UNIQLO Co., Ltd. started marketing HEATTECH™ in 2003".¹ The construction is technical: according to Toray, HEATTECH is knitted from rayon, acrylic, polyester and polyurethane, its acrylic fibres are a tenth of the thickness of a hair, and development ran to more than 10,000 prototypes.⁴ None of that appears on the label. The customer sees one word, on the label and in the advertising.

A partnership behind the name

In June 2006 Uniqlo and Toray formed a strategic business partnership, which Toray describes as an agreement to set and share five-year targets.^5,1 A second five-year plan followed in July 2010 for the years 2011 to 2015, with procurement reported at 400 billion yen, and a third stage in November 2015 with expected transactions of one trillion yen.^6,7

HEATTECH grew with the partnership. Uniqlo's release for the 2007 season split it into HEATTECH Plus for men and HEATTECH Moist for women and children, and described the products as developed jointly with Toray.⁸ Sales rose from 1.5 million units in 2003 to 20 million in 2007 and 50 million in 2009.² In 2012 the two companies announced a target of 130 million units for that year alone.⁹ In 2017 Uniqlo put cumulative worldwide sales since 2003 at about one billion items.¹⁰

Fabrics as sub-brands

HEATTECH became the template for a family of named technologies. Ultra Light Down, a lightweight down jacket, was born in 2009, with a high-density nylon shell developed with Toray.¹¹ In April 2012 Uniqlo introduced AIRism as an umbrella concept for its spring and summer innerwear, gradually replacing two existing product names, Sarafine for women and Silky Dry for men, which had sold about 54 million units between 2007 and 2011.¹² The release named the products global strategy items and set AIRism beside HEATTECH as year-round functional innerwear.¹²

The AIRism decision shows the logic of the system. Two gendered names became one, and the new name described a function rather than a customer. Summer and winter now had matching brands: AIRism for cooling, HEATTECH for warmth. Each name carries a promise that can be explained in one sentence and repeated every season, and each is styled in its own way, from the capitals of HEATTECH and BLOCKTECH to the mixed case of AIRism.^4,13

The supplier's work, the retailer's name

When a technology carries its own name, the question is whose name it is. With HEATTECH the answer is the retailer's. Toray develops the fibres, but the trademark belongs to Fast Retailing, and Toray's own history states that "HEATTECH™ is a trademark of FAST RETAILING CO., LTD."^1,3 As trademark owner, Fast Retailing controls the name, whoever makes the fibre.

The names also gave Uniqlo something to advertise that was neither fashion nor price. In autumn 2010 its global "Made for All" campaign featured Charlize Theron and Orlando Bloom as brand ambassadors, in advertising that included HEATTECH.¹⁴ In New York subway posters that December the two appeared in down jackets next to the HeatTech logo, although the fabric is used in base layers, not in those jackets.¹⁵ The name was already being used as a sign for warmth in general. HEATTECH also features in the brand's social programmes: in September 2025 Fast Retailing records the donation of one million HEATTECH items to people in need worldwide.¹⁶

The partnership itself became part of the communication. Under the title "The Art and Science of LifeWear", Uniqlo and Toray have staged exhibitions that explain the fibres behind the names, in New York in 2017, in Paris in 2018 and at Somerset House in London in 2019.⁴ At the 20th anniversary in 2023, Uniqlo adds HEATTECH Ultra Light, the thinnest version yet, and puts worldwide sales at around 1.5 billion items, as reported by FASHIONSNAP.¹⁷

For a company that sells basics, named fabrics solve a specific problem. A plain long-sleeved top is hard to distinguish from a competitor's. A HEATTECH top is a product only Uniqlo sells. The material became an argument the brand could repeat every season, and one it later folded into the idea of LifeWear.