Temperature sensitive polymers and water-dispersible products containing the polymers

• US 6,451,429 B2
• Filed: 05/18/2001
• Issued: 09/17/2002
• Est. Priority Date: 12/31/1996
• Status: Expired due to Term

• Current Assignee: Kimberly-Clark Worldwide Incorporated (Kimberly-Clark Corporation)
• Original Assignee: Kimberly-Clark Worldwide Incorporated (Kimberly-Clark Corporation)
• Inventors: Wang, James Hongxue, Chang, Yihua, Mumick, Pavneet Singh
• Primary Examiner(s): Woodward, Ana
• Application Number:
  US09/861,401
• Publication Number:
  US 20010029143A1
• Time in Patent Office: 487 Days
• Field of Search: 442/330, 442/333, 442/394, 442/396, 442/399, 442/59, 442/118, 442/164, 442/374, 428/364, 428/394, 428/395, 604/358, 604/365, 604/366, 604/367, 604/372, 604/373, 604/385.18, 604/385.201, 604/385.23, 604/304, 604/904
• US Class Current: 428/394
• 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 15/62 Compostable, hydrosoluble or hydrodegradable materials
• CPC Class Codes: C08F 120/06 Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
• CPC Class Codes: C08F 8/32 by reaction with amines
• CPC Class Codes: C08F 8/44 Preparation of metal salts or ammonium salts
• CPC Class Codes: C08L 33/26 Homopolymers or copolymers of acrylamide or methacrylamide
• CPC Class Codes: Y10S 604/904 Tampons
• CPC Class Codes: Y10T 428/2913 Rod, strand, filament or fiber
• CPC Class Codes: Y10T 428/2967 Synthetic resin or polymer
• CPC Class Codes: Y10T 428/2969 Polyamide, polyimide or polyester
• CPC Class Codes: Y10T 428/2971 Impregnation
• CPC Class Codes: Y10T 428/31725 Of polyamide
• CPC Class Codes: Y10T 428/31728 Next to second layer of polyamide
• CPC Class Codes: Y10T 442/20 Coated or impregnated woven, knit, or nonwoven fabric which is not [a] associated with another preformed layer or fiber layer or, [b] with respect to woven and knit, characterized, respectively, by a particular or differential weave or knit, wherein the coating or impregnation is neither a foamed material nor a free metal or alloy layer
• CPC Class Codes: Y10T 442/2484 Coating or impregnation is water absorbency-increasing or hydrophilicity-increasing or hydrophilicity-imparting
• CPC Class Codes: Y10T 442/2779 Coating or impregnation contains an acrylic polymer or copolymer [e.g., polyacrylonitrile, polyacrylic acid, etc.]
• CPC Class Codes: Y10T 442/2861 Coated or impregnated synthetic organic fiber fabric
• CPC Class Codes: Y10T 442/3366 Woven fabric is coated, impregnated, or autogenously bonded
• CPC Class Codes: Y10T 442/603 Including strand or fiber material precoated with other than free metal or alloy
• CPC Class Codes: Y10T 442/607 Strand or fiber material is synthetic polymer
• CPC Class Codes: Y10T 442/637 : Including strand or fiber material which is a monofilament composed of two or more polymeric materials in physically distinct relationship [e.g., sheath-core, side-by-side, islands-in-sea, fibrils-in-matrix, etc.] or composed of physical blend of chemically different polymeric materials or a physical blend of a polymeric material and a filler material
• CPC Class Codes: Y10T 442/652 : Nonwoven fabric is coated, impregnated, or autogenously bonded
• CPC Class Codes: Y10T 442/659 : Including an additional nonwoven fabric
• CPC Class Codes: Y10T 442/66 : Additional nonwoven fabric is a spun-bonded fabric
• CPC Class Codes: Y10T 442/671 : Multiple nonwoven fabric layers composed of the same polymeric strand or fiber material
• CPC Class Codes: Y10T 442/674 : Nonwoven fabric with a preformed polymeric film or sheet
• CPC Class Codes: Y10T 442/676 : Vinyl polymer or copolymer sheet or film [e.g., polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, etc.]
• CPC Class Codes: Y10T 442/679 : Natural or synthetic rubber sheet or film
• CPC Class Codes: Y10T 442/68 : Melt-blown nonwoven fabric
• CPC Class Codes: Y10T 442/681 : Spun-bonded nonwoven fabric

Abstract

The present invention is directed to a novel process of making N-isopropyl acrylamide (NiPAm) polymers based upon the reaction of poly(acrylic acid) and N-isopropylamine. The disclosed method of the present invention uses polyacrylic acid as a starting material to synthesize NiPAm polymers. In one embodiment, the present invention discloses a condensation reaction of an intermediate salt to form homopolymers, copolymers and terpolymers of N-isopropyl acrylamide (NiPAm) with acrylic acid and/or alkyl acrylates in a molten state, which is adaptable to a continuous reactive extrusion process. Binder compositions, water-dispersible products and thermoformable articles containing the NiPAm polymers are also disclosed.

Claims

1. A water-dispersible product containing at least one fibrous substrate, wherein the fibrous substrate comprises:

at least one fibrous material; and

a binder composition for binding said at least one fibrous material into an integral web, said binder composition comprising a polymer containing N-isopropyl acrylamide and acrylic acid structural units, said polymer produced by extrusion method, said method comprising;

forming an intermediate salt from a reaction mixture comprising polyacrylic acid and isopropylamine; and

conducting a condensation reaction to convert the salt to the polymer and water.

2. The water-dispersible product of claim 1, wherein the copolymer is poly(N-isopropyl acrylamide-co-acrylic acid).

3. The water-dispersible product of claim 2, wherein the polymer is a terpolymer containing N-isopropyl acrylamide structural units.

4. The water-dispersible product of claim 3, wherein the polymer further comprises N-tert-butylacrylamide structural units.

5. The water-dispersible product of claim 4, wherein the polymer comprises at least about 80 mole percent N-isopropyl acrylamide structural units and less than about 20 mole percent N-tert-butylacrylamide structural units.

6. The water-dispersible product of claim 1, wherein the binder composition further comprises at least one hydrophobic polymer.

7. The water-dispersible product of claim 6, wherein the at least one hydrophobic polymer comprises polyvinyl acetate.

8. The water-dispersible product of claim 7, wherein the binder composition comprises at least about 30 weight percent of the polymer and less than about 70 weight percent polyvinyl acetate.

9. The water-dispersible product of claim 1, wherein the at least one fibrous material comprises natural fibers.

10. The water-dispersible product of claim 1, wherein the at least one fibrous material comprises synthetic fibers.

11. The water-dispersible product of claim 1, wherein the fibrous material comprises a nonwoven fabric.

12. The water-dispersible product of claim 1, further comprising a fluid impervious film formed from the polymer containing N-isopropyl acrylamide structural unit.

13. The water-dispersible product of claim 1, wherein the water-dispersible product is a flushable personal care product selected from the group consisting of tampons, feminine pads, pantiliners, diapers, wound dressings, wet wipes and tissues.