Aluminum Foil, EPE, EPP: Which Of The Three Insulating Bag Materials Is Good?

When Insulated bags are removed, there are basically just a few layers. But what many people don't know is that there are three distinct types of insulation layer just in (expanded polyethylene middle: aluminum foil, EPE foam and EPP foam. Every manufacturer claims to have an advantage, which confuses consumers. Today we'll compare the three ingredients and you'll know which one to choose.
First, let's talk about aluminum foil: it's not an insulation material, it a "bullet deflector."
Many people think aluminum foil itself insulates against heat, but that's not true. Aluminum foil's core capability is the reflection of heat radiation, with a reflectivity of more than 95%. What does this mean? When heat escapes in the form of infrared radiation, the aluminum foil merely deflects it backward. Therefore, aluminum foil's true strength is not "insulation," but "containment."
It has a temperature resistance of between -50°C and 121°C, is nontoxic and odorless, meets food-grade standards, and is adept at blocking air, water, moisture and oxidation. However, aluminum foil has a fatal flaw-it is too soft, has low tear strength and requires a PE film lamination to heat sealing. There are also two types of aluminum foil: aluminum foil and aluminum film. Aluminum foil doesn't bounce back like wires when bent and has better insulation, while aluminum film bounces back as soon as it bends and is basically just a piece of plastic paper, which is cheaper but significantly less capable.
So, aluminum foil's role is obvious: it is a "reflective layer" of the insulating bag, not the main layer. Aluminum foil itself cannot handle conduction and convection.
Now let's talk about EPE (expanded polyethylene) foam: the king of cost-effectiveness, but with its limitations.
EPE is a polyethylene foam material with a closed cell structure, available in white and red (red is used for anti-static). Advantages include cushioning and insulation, a a tensile strength of 3.4 kg/cm2, an elongation more than 125%, the ability to bounce back after compression and the ability to shock absorption, moisture resistance, sound and heat. However, common polyethylene is very fragile, so to enhance tear resistance of the polyethylene film layer, this is a common ``polythene composite bag"on the market.
The problem with EPE is that its relatively high thermal conductivity. It can be used, but you have to overcome extreme temperature differences. In addition, EPE works at a temperature of around 80 degrees Celsius, beyond which the material begins to soften. For short takeaways and room temperature meals, EPE is the fullest and cheapest option. However, if you have to endure cold chain conditions of minus 10 degrees Celsius or prolonged heat, EPE will be the first to fail.
Finally, let's talk about EPP: the most widely used insulation material.
EPP is a sealed foam made of polypropylene with high melting point under high temperature and pressure. Its thermal conductivity is less than 0.028, lower than 0.035 of EPS, which is the thermal conductivity of most PU foam materials. For the same size, EPP has the best insulation.
Even more impressive is its temperature range: -40C to 130C. It's not brittle at -40 degrees Celsius and it doesn't soften at 130 degrees Celsius, which puts EPS well ahead of the curve-itEPS brittle below -10 degrees and soft and deformed above 60 degrees Celsius.
EPE has a compressive strength 2-3 times that of an EPS of the same density, with a rebound rate of above 90% after repeated compression and below 60% after three compressions. It has a density of between 30 and 100 kg/m3, which is about 30% less than EPS with the same level of protection. A 10-ton truck packed with EPE can carry 3000 kilograms of cargo, saving 1500 yuan in freight costs each time, a tangible economic benefit.
In addition, EPE can be reused more than 1000 times, 100% recyclable, no plasticizer or foaming agent, non-toxic and tasteless, can be self-extinguishing after being treated with environmental flame retardant technology. For cold chain logistics, fresh food distribution, drug transportation, EPE is the most balanced option at present.
So, which is better?
The answer depends on your situation.
If you're just delivering or packing lunch, EPE coated bags will do the trick-it's cheap and easy to use, and you don't need EPE. If you need a reflective layer to strengthen insulation, aluminum foil is essential and can be laminated with EPE and EPP without conflict. However, if your application involves cold chain transport, long-term insulation, or protection of high value goods, EPP is by far the strongest all-round material without exception.
Bottom line: aluminum foil is shielding, EPE is economical and EPP is the all-rounder. Don't get confused by marketing hype, choose according to your application scenario and spend wisely.