Treating interparticle bonded aggregates with latex to increase flexibility of porous, absorbent macrostructures

• US 5,859,074 A
• Filed: 05/09/1997
• Issued: 01/12/1999
• Est. Priority Date: 11/09/1994
• Status: Expired due to Term

• Current Assignee: The Procter & Gamble Company
• Original Assignee: The Procter & Gamble Company
• Inventors: Shimizu, Motohiro, Rezai, Ebrahim, Hsueh, Kesyin
• Primary Examiner(s): Foelak, Morton
• Application Number:
  US08/836,333
• Time in Patent Office: 613 Days
• Field of Search: 521/54, 521/57, 521/64, 604/358, 604/369, 604/367
• US Class Current: 521/54
• CPC Class Codes: A61L 15/24 Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives thereof A61L15/225 takes precedence
• CPC Class Codes: A61L 15/425 Porous materials, e.g. foams or sponges
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: C08L 33/08 Homopolymers or copolymers of acrylic acid esters
• CPC Class Codes: C08L 33/14 of esters containing halogen, nitrogen, sulfur, or oxygen atoms in addition to the carboxy oxygen

Abstract

Porous, absorbent macrostructures that comprise flexible interparticle bonded aggregates and are useful in absorbent articles such as diapers, adult incontinence pads, and sanitary napkins are disclosed. These porous macrostructures are treated with an effective amount of a latex to coat at least a portion of the particles comprising the bonded aggregate so as to impart increased flexibility to the macrostruture. This latex is capable of being sintered at a temperature of about 25° C. or lower, is at least somewhat hydrophilic when sintered, and has a Tg of about 25° C. or lower when sintered.

Claims

1. A method for imparting improved flexibility to a porous, absorbent macrostructure, said method comprising the steps of:

(a) treating a porous aggregate macrostructure comprising an interparticle bonded aggregate having pores interconnected by intercommunicating channels such that the macrostructure is liquid permeable with an effective amount of a latex to coat a portion of said particles of said porous aggregate macrostructure, said latex being capable of being sintered at a temperature of about 25°

C. or lower, being at least somewhat hydrophilic when sintered, and having a Tg of about 25°

C. or lower when sintered; and

(b) sintering said porous aggregate macrostructure at a temperature of about 25°

C. or lower to impart increased flexibility thereto.

2. The method of claim 1 wherein said porous aggregate macrostructure is in the form of a sheet having thickness of at least about 0.2 mm and a density of from about 0.5 to about 1.0 g/cc.

3. The method of claim 2 wherein said latex is made by emulsion polymerization of an olefinic monomer selected from the group consisting of C₂ -C₄ alkyl and hydroxy alkyl acrylates, C₁ -C₄ alkyl or hydroxy alkyl methacrylates and mixtures thereof.

4. The method of claim 3 wherein said C₂ -C₄ alkyl and hydroxy alkyl acrylates are selected from the group consisting of propyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, ethyl acrylate and mixtures thereof.

5. The method of claim 3 wherein said C₁ -C₄ alkyl or hydroxy alkyl methacrylates are selected from the group consisting of propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, ethyl methacrylate, methyl methacrylate, vinyl acetate and mixtures thereof.