US 4,537,313 · Granted 1985-08-27

The Layered Insulation Patent That Launched Modern Cooler Bags

Imagine a sandwich bag made of five different super-smart materials stacked on top of each other—nylon on the outside, fancy insulation in the middle, and special foils that bounce heat away. This patent from 1984 is the blueprint for how those flexible cooler bags keep your lunch cold without being rigid or bulky.

Curated and verified by the IsItPatented Editorial team

The plain-English version

What it protects

The claim covers a flexible insulated container with a specific multi-layer construction: nylon fabric forming inner and outer liners, thermal suede as the primary insulation layer, needle-punched Dacron fabric as a vapor and thermal barrier, aluminum foil as a thermal barrier, and metalized Mylar as a vapor barrier. What's protected is this exact combination of materials in this specific order and arrangement—not just using insulation, but using these five particular materials working together in a bag that can flex and fold.

Why it matters

This patent represents a key moment in consumer product design when flexible coolers became practical alternatives to rigid hard-sided coolers. By combining multiple thin barrier materials instead of relying on thick foam alone, the inventor created a bag that was lightweight, packable, and effective at temperature control. This approach became the foundation for modern lunch boxes, food delivery insulation, and reusable grocery totes—products that needed to be portable while protecting contents from temperature swings.

Real-world use

Every soft-sided lunch cooler you pack for school or a picnic relies on this layering principle: the nylon keeps it looking nice, the thermal suede holds the cold in, and the foil and Mylar work behind the scenes to block heat from sneaking through the walls.

Original USPTO abstract

There is provided an insulated bag of a multi-layer construction employing nylon fabric as inner and outer liners, thermal suede as thermal insulation inside the outer liner, needle punched Dacron fabric as a vapor and thermal barrier, aluminum foil as a thermal barrier and metalized Mylar as a vapor barrier.

Patent details

Publication number: US 4,537,313
Filing date: 1984-02-27
Grant date: 1985-08-27
Assignee: Eleanor Workman
Inventor(s): WORKMAN; ELEANOR
CPC class: A47J47/145

View original record on Google Patents →

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