Self-Expanding Insulated Mailers

KENT supplies self-expanding insulated mailers with a VMPET metallized polyester outer film, polyurethane (PU) foam and an LDPE inner film. Delivered vacuum-compressed, the foam recovers after you load the goods and remove the air inlet seal. The recovered foam provides insulation and cushioning around the packing space.

Standard nominal sizes include 9 × 12, 12 × 14 and 15 × 18 inches. Choose a standard size or discuss custom dimensions, foam thickness and logo printing for bulk orders. The closure combines a press-to-close zip with a self-adhesive flap.

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How Self-Expanding Insulated Mailers Work

1. Load the goods into the compressed mailer.

2. Remove the air inlet seal from the designated opening on the mailer.

3. Allow the foam to recover as air enters the compressed PU foam.

The foam is already formed inside the mailer. Activation requires no chemical mixing, foam injection or inflation pump. Follow the packing instructions for your selected specification when sealing the main bag opening.

Before and After Foam Expansion

Vacuum compression keeps unused mailers compact for storage and bulk packing. The recovered foam takes up more space, so allow for the final wall thickness when choosing the mailer and outer shipping carton.

Zip Closure and Self-Seal Flap

This configuration combines a press-to-close zip with a self-adhesive flap. The zip closes the bag mouth, while the flap provides an additional closure.

The air inlet seal and the flap’s release liner are separate components. Check their locations and operation when reviewing your sample.

Three-Layer Construction: VMPET, PU Foam and LDPE

The mailer combines three main functional layers:

“Three-layer” describes the main functional structure. VMPET means metallized polyester film. For custom orders, confirm the outer film and PU foam specifications together.

Standard Sizes and Custom Specifications

Usable Internal Size and Flap Allowance

The listed sizes are nominal dimensions and should not be treated as usable internal measurements. Confirm how the bag body is measured, the space taken up by seams and the flap length before ordering.

Measure your product in its primary packaging, including any coolant packs. Allow space for insertion, foam recovery and closure. A sample fit is especially useful for rigid or irregular contents.

Compressed and Expanded Foam Thickness

Specify whether the thickness refers to compressed or recovered foam, and whether it measures one wall or both walls together. KENT can review the required foam thickness for your project. Use the recovered dimensions of the approved sample to assess the final packing arrangement.

Carton Quantity and Shipping Dimensions

Confirm the case quantity, carton dimensions and gross weight together. These details support storage planning and freight quotations. Case count alone does not describe shipping volume.

Insulated Mailers for Temperature-Sensitive Shipping

Product Applications and Packing Requirements

These thermal mailers can be evaluated for packaged chocolate, chilled food and other temperature-sensitive goods. Define the acceptable temperature range, primary packaging and delivery requirements for your product.

Fragile, heavy or leak-prone contents may need extra support, leakage containment and an outer carton. Keep food in suitable primary packaging. An LDPE material description alone does not establish suitability for direct food contact.

Coolants, Outer Cartons and Transit Conditions

An insulated shipping mailer slows heat transfer but does not generate cooling. Whether you need gel ice packs or other coolants, and how much to use, depends on the starting temperature, target range, expected transit time and surrounding conditions.

Test the mailer, coolant, goods and outer packaging as a complete arrangement against the intended route and delivery window.

Custom Insulated Mailers and Wholesale Supply

Custom Sizes and PU Foam Options

Send your packed product dimensions, coolant arrangement and proposed loading method. KENT can review custom bag sizes and PU foam thickness requirements to match the internal space with your outer packaging.

Logo Printing and Outer Film Options

Discuss logo, graphic or text printing and your preferred outer film color. Provide the artwork, print position and intended appearance. Confirm the printing configuration and result through a sample.

If you already have dimensions and artwork, send your specifications for a custom quotation.

Samples, MOQ and Lead Time

The typical minimum order quantity is 5,000 pieces, confirmed according to size, material and printing requirements. Other quantities can be discussed with KENT for review.

Request a sample to check fit, foam recovery, zip closure and the self-adhesive flap. Existing samples and custom artwork samples have separate cost and preparation requirements. Production timing is quoted against the final specification and order quantity.

Bulk Packing and Shipping Preparation

The video shows finished mailers being packed into cartons, followed by carton sealing, labeling and strapping. Agree the case quantity, carton label details and shipping dimensions alongside the product specification to plan receiving and storage.

Foam Insulated Mailers vs. Insulated Bubble Mailers and Box Liners

Choose by the complete packing arrangement. Material names or thickness figures alone do not establish which option will maintain the required temperature for longer. Browse our protective packaging bags for related bag formats.

Self-Expanding Insulated Mailers FAQ

1. What size insulated mailer do I need?

Standard nominal sizes include 9 × 12, 12 × 14 and 15 × 18 inches, with custom dimensions available for review. Start with the dimensions of your packaged product and coolants. Confirm the usable internal space, recovered wall thickness and flap allowance, then check the fit with a sample.

2. What do the zip closure and self-seal flap do?

The zip closes the bag mouth, and the self-adhesive flap provides an additional closure. The air inlet seal is a separate activation component. Follow the selected specification’s closure instructions. These features alone do not establish an airtight or leakproof finished package.

3. Can I request samples, and what is the minimum order quantity?

Yes, samples can be requested. The typical MOQ is 5,000 pieces, with the final quantity confirmed by size, material and printing requirements. Discuss the sample type, charges and any alternative quantity requirements when requesting a quote.

4. Can I customize the size, foam thickness and printing?

Yes. Send your required bag dimensions, foam thickness and artwork. KENT will review a suitable configuration for the order and confirm it through the specification and sample.

5. How do self-expanding insulated mailers work?

After loading, remove the air inlet seal. Air enters the compressed PU foam and allows it to recover thickness. No chemical mixing or separate inflation pump is required.

6. How long can these mailers keep products cold, and do I need ice packs?

There is no single duration for every shipment. Performance depends on the starting temperature, target range, coolant arrangement, insulation, outer packaging and route conditions. The mailer does not generate cooling. Select coolants according to your temperature requirements and test the complete packing arrangement.

7. Do I need an outer shipping box?

Base that decision on product weight, fragility, stacking and handling conditions. A suitable carton can provide structural support and help keep the goods and coolants in position.

8. Can these mailers be used for food shipments?

They can be evaluated for food shipments with suitable primary packaging, subject to the product’s temperature requirements. Keep food in its primary packaging. Direct food contact requires a separate material suitability assessment.

9. Are foam insulated mailers waterproof?

Water resistance of individual films does not establish a waterproof finished mailer. Seams, closures and the air inlet affect the complete package. Use suitable leakproof primary packaging for contents that may leak, and assess the outer protection needed during shipping.

10. Are foam insulated mailers recyclable?

The mailer combines materials including VMPET, PU foam and LDPE. Recycling depends on the composition, separation requirements and local collection facilities. Do not assume it can enter the same recycling stream as a single-material PE bag. Check disposal requirements for the selected construction and destination.

Request a Quote for Your Insulated Mailers

Send your packed product dimensions and weight, target temperature range, starting temperature, expected transit time and destination. Include your coolant plan, order quantity, foam requirements and artwork where applicable.

KENT will help establish the product specification and quotation for sample evaluation and bulk supply.

Request an Insulated Mailer Quote