Method for preparing formed polyurethane foam materials and formed polyurethane foam materials therefrom

Abstract

This invention relates to a novel method for the preparation of polyurethane foam materials suited for seamless breast pads, cups, fronts and the like for use in brassieres and other garments. Polyurethane foam is produced from aliphatic isocyanates and polyols. The aliphatic polyurethane foam is reticulated to remove all celled membranes and sliced into sheet with a thickness greater than the thicker wall of the finished brassiere cup. The sliced aliphatic polyurethane foam sheet is then pressed between mold parts of a female mold part and a male mold part. The mold parts are closed and pressed whereby the aliphatic polyurethane foam material is molded into the exact shape of the mold cavity. The molded aliphatic polyurethane foam material can be used as seamless breast pads, cups, fronts and the like in brassieres and other garments and expresses superior non-yellowing properties over previous aromatic polyurethane brassiere pads and improved breathability and porosity.

Description

FIELD OF THE INVENTION [0001] This invention relates to a novel method for the preparation of formed polyurethane foam materials, especially to method for preparation of formed polyurethane foam materials for breast pads, cups, fronts and the like for use in brassieres and other garments, and the breast pads, cups fronts and the like prepared according to the invented method. This method is especially useful in the preparation of a molded seamless brassiere cup from soft polyurethane foam materials that were produced from the polymerization of aliphatic isocyanates and polyols. BACKGROUND OF THE INVENTION [0002] In the manufacture of brassieres and other garments that include formed breast pads, cups, fronts and the like, there is a need for resilient materials that can adapt themselves to the various positions and motions of the wearer, while always retaining their original shape. Further, their shape and resilience should not be affected by laundering and machine washing. Still fu...

AI Technical Summary

Benefits of technology

[0008] The above-discussed problems of the prior art are overcome by the present invention with which molded brassiere cup with sufficient porosity and breathability is produced. Brassiere cups made from aliphatic polyurethane foam with excellent color fastness against UV light can also be obtained.

[0009] The present invention provides an economic solution for the production of brassiere pads with improved breathability, while maintaining the smoothness of the brassiere cup.

[0011] Another objective of the present invention is to provide a novel method to improve thermal dissipation in the foam and to reduce molding temperature and process time of the thermal formation procedure. The invented method helps to avoid polymer degradation under extreme hot circumstance and to protect workers from exposure to harmful hydrogen cyanide fumes resulted from such thermal degradation.

[0012] A further objective of the present invention is to provide a method to mold a brassiere cup with shorter production cycle time. With the reduced production cycle time, the production capacity of a brassiere cup molding line can be significantly increased.

[0014] This invention relates to a novel method for the preparation of polyurethane foam materials suited for seamless breast pads, cups, fronts and the like for use in brassieres and other garments. This method is especially useful in the preparation of a molded seamless brassiere cup from soft polyurethane foam materials that were produced from the polymerization of aliphatic isocyanates and polyols. Such aliphatic polyurethane foam is reticulated to remove all celled membranes and sliced into sheet with a thickness greater than the thicker wall of the finished brassiere cup. The molded seamless brassiere cups have a thicker wall at the outer or apex portion than at the peripheral portion thereof. The sliced aliphatic polyurethane foam sheet is then pressed between mold parts of a female mold part and a male mold part. The mold parts are closed and pressed by hydraulic press. The aliphatic polyurethane foam material is therefore molded into the exact shape of mold cavity. The molded aliphatic polyurethane foam material can be used as seamless breast pads, cups, fronts and the like in brassieres and other garments. The molded aliphatic polyurethane brassiere pads have superior non-yellowing properties over previous aromatic polyurethane brassiere pads and have improved body temperature dissipation due to improved breathability and porosity.

Problems solved by technology

Prior art processes have suffered from thinning at the apex and consequently resulted in poor shape stability after laundering and machine washing.

The sewing, however, cannot meet current fashion requirement for a seamless brassiere cup.

This process, however, requires homogeneous distribution of the thermoplastic resin within the fibrous material and, thus, production of brassiere cups with even softness and resilience using this process is difficult.

Another drawback of this invention is the requirement for a precise resin contain.

A brassiere cup with an insufficient amount of resin binding tends to be affected by laundering and results in poor shape stability.

Such thermal treatment causes dissociation of chemical bond in the polyurethane, which results in loss in physical properties and accelerated yellowing in the service life of the polyurethane foam.

A significant drawback resulted from using aromatic polyurethane foam is its color change nature.

However, the aliphatic polyurethane foam has close cells in most all parts of its structure due to the lack of blowing as result from slow reactivity of the aliphatic isocyanate functional group.

Such close cell structure within polyurethane foam requires higher thermal formation temperature and longer process time due to slower thermal dissipation and processing difficulty.

Resulted foam brassiere pads have only limit breathability owing to the residual cell membranes.

Another problem with thermally formed polyurethane brassiere pad is in its limited breathability as resulted from reduced porosity after thermal formation.

However, those air holes bring in negative impact on the smoothness of the resulted brassiere cup.

As a result, such pad structure has only limit market acceptance.