1. Top
  2. About Us
  3. 2023 News Release
  4. Introducing the Enhanced Version of "LIFREE Ultra Slim Comfort Pants"


Adopting 'Ultrasonic Bonding Technology' in Adult Disposable Pants
  Introducing the Enhanced Version of "LIFREE Ultra Slim Comfort Pants"

Unicharm Corporation (CEO & President, Mr. Takahisa Takahara) will sequentially release the “LIFREE Ultra Slim Comfort Pants” nationwide from mid-November 2023. These pants, which are part of the best-selling adult incontinence care brand “LIFREE”, feature the adoption of Ultrasonic Bonding Technology in the waist area, allowing for easy lifting with minimal effort and providing a comfortable fit.

This improvement also enhances compression rate and loading efficiency, reducing environmental impact. *1

*1 Intage Research on adult diaper market SRI (June 2013-December 2016) + SRI + (January 2017-May 2023) cumulative sales amount ranking."

"LIFREE Ultra Slim Comfort Pants"

Background of the New Improvement of "LIFREE Ultra Slim Comfort Pants"

Ultra slim disposable pants have been increasingly favored for their "underwear-like comfort" and are being used not only for outings but also as everyday wear. We have discovered that users who prefer such pants prioritize not only basic functions like "leakage protection" but also convenience in terms of "easy change" and comfort in terms of "good fit."*2

Therefore, we have adopted patented technology related to Ultrasonic Bonding in the waist area of “LIFREE-Ultra Slim Comfort Pants” to further enhance the comfortable fit.

Moreover, the adoption of Ultrasonic Bonding Technology improves the compression rate during packaging of the pants, leading to increased loading efficiency and improved delivery efficiency, thereby reducing environmental impact. Additionally, by reducing the amount of hot melt adhesive used in the conventional bonding process, the pants become easier to recycle, contributing to the realization of a circular economy-oriented product design.

*2 Research by Unicharm

Product Features

 (1) Improvement of Waist Tightness with the Adoption of Ultrasonic Bonding Technology

- By upgrading the waistband bonding process from using conventional adhesives to Ultrasonic Bonding in order to maintain the inherent softness of the non-woven fabric and improve comfort by reducing tightness.

- With reduced tightness, it is now easier to lift and lower the disposable pants with minimal effort, allowing for smooth wearing and removal.

<Video showing Easy Wearing>

(2) Improved fitness through the combination of disposable pants and pad for pants

- By incorporating a unique "slit structure" in the absorbent core, the crotch area deforms into a convex shape.

- Even when used in combination with a pad for pants, both the disposable pants and the pad deform synchronously into a convex shape, providing a perfect fit to the body.

- The deformation of the absorbent core according to the body's movements helps minimize gaps and reduce leakage.

The Effect of Wearing Disposable Pants and Pad for Pants on the Standing-Up Motion of the Elderly: Joint Research with Professor Fujii from the University of Tsukuba

In general, "standing up" from a "sitting" posture requires tilting the pelvis forward and shifting the body’s center of gravity forward. However, for the elderly, it is difficult to stand up smoothly because the pelvis tilts forward and the center of gravity shifts less forward due to physical weakness.

Furthermore, when using a combination of disposable pants and pad for pants, it is believed that the presence of bulkiness can affect the standing-up motion compared to when wearing only regular underwear.

In this study, we examined the impact of the combination of disposable pants and pad for pants on the standing-up motion. It was revealed that the combination of the newly improved disposable pants, which deform according to the body's shape in the crotch area, and pad for pants resulted in an improved forward tilt angle of the pelvis during the standing-up motion compared to conventional products, making the motion more similar to that when wearing regular underwear.

Other Effects of Adopting Ultrasonic Bonding Technology

(1) Product packaging and cardboard box design for efficient logistics delivery

- By using Ultrasonic Bonding for the waistband, we were able to achieve a higher compression ratio, eliminating the need to consider the effects of compression on the adhesive.

- The new products with higher compression rates also recover to the same thickness as the conventional product within approximately 24 hours after the package is opened.

- The adoption of Untrasonic Bonding Technology is expected to reduce adhesive usage by approximately 190 tons per year.

- The newly improved packaging has successfully achieved over 10% reduction in size compared to conventional products.*3

- As a result, the size of the cardboard boxes has also been reduced by over 10% compared to conventional products.*4

- Consequently, the loading efficiency in logistics and distribution has improved, and an estimated annual reduction of approximately 220 tons*5 of carbon dioxide (CO2) emissions is expected.

*3 Applies for only the front width of the package. The depth and height remain the same as conventional products.

*4 Applies for regular and jumbo size products displayed in stores.

*5 Expected to reduce the emissions equivalent to approximately 1,000 of ten tons large trucks per year.

(2) Product Design considering Horizontal Recycling

- When recycling used disposable pants, the materials are separated into "pulp," "super absorbent polymer," and "plastic." Without using adhesive in the waistband makes it easier to separate and extract the "recycled pulp" with no residue from adhesives.

Product Information



Product  Size


of Items


"LIFREE Ultra Slim Comfort Pants"

Regular type 

S 24

Open Price

M 22
L 20
LL 18

Release Date:

The product will be sequentially released nationwide from mid-November 2023.

<Related Information>

Unicharm Kyo-sei Life Vision 2030   https://www2.unicharm.co.jp/english/csr/kyoseilifevision/index.html

Contributing to the 17 SDGs through launching "LIFREE Ultra Slim Comfort Pants"

Unicharm believes that this act will contribute to the following goal of the 17 Sustainable Development Goals (SDGs) adopted by the United Nations in 2015.


3.Good Health and Well-Being   12.Responsible Consumption and Production     


We will continue to the achievement of the SDGs by solving environmental and social issues through our business activities, including the provision of products and services.

 <<For Inquiries>>

Unicharm Corporation, ESG Division, Public Relations Office

Email: brand-pr@unicharm.com

Unicharm Corporation Website https://www.unicharm.co.jp/en/home.html

Share On