Process of enhanced chemical bonding by electron seam radiation

• US 6,210,516 B1
• Filed: 10/06/1997
• Issued: 04/03/2001
• Est. Priority Date: 02/18/1994
• Status: Expired due to Fees

• Current Assignee: John Gavin Macdonald, Ronald Sinclair Nohr
• Original Assignee: John Gavin Macdonald, Ronald Sinclair Nohr
• Inventors: MacDonald, John Gavin, Nohr, Ronald Sinclair
• Primary Examiner(s): ZIRKER, DANIEL R
• Application Number:
  US08/944,258
• Time in Patent Office: 1,275 Days
• Field of Search: 156/272.2, 156/275.5, 250/492.3, 250/400
• US Class Current: 156/272.2
• CPC Class Codes: D06M 10/008 Treatment with radioactive elements or with neutrons, alpha, beta or gamma rays
• CPC Class Codes: D06M 14/28 of macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds

Abstract

Permanent surface modification of polypropylene nonwoven fabrics is achieved through electron beam radiation induced chemical bonding. The electron beam energy levels suitable for such chemical bonding are between about 5 KeV to about 110 KeV at the surface of the fabric facing the electron beam radiation source. At these energy levels, chemical bonding, control of electron beam penetration and the formation of free radicals in the polypropylene nonwoven fabrics are achieved. Control of electron beam penetration produces free radical formation and chemical bonding at selective levels within the fabric as well as bonding of different chemicals asymmetrically to the same fabric with minimal, if any, loss of polymer fabric strength.

Claims

1. A process for selectively chemically modifying a shaped polymeric material having a first surface and a second surface separated by a thickness, the process comprising:

contacting the shaped polymeric material with a first unsaturated modifying compound having a first substituent capable of altering the surface characteristics of the shaped polymeric material;

exposing the shaped polymeric material under ambient pressure conditions to from about 5 KeV to about 85 KeV of ionizing radiation from an ionizing electron beam radiation source operating at an energy potential of from about 75 KeV to about 125 KeV to selectively chemically bond the first modifying compound to the first surface of the shaped polymeric material, wherein the first surface is facing the ionizing electron beam radiation source;

washing the shaped polymeric material to remove first modifying compound which was not chemically bonded;

contacting the shaped polymeric material with a second unsaturated modifying compound having a second substituent capable of altering the surface characteristics of the shaped polymeric material; and

exposing the shaped polymeric material under ambient pressure conditions to from about 5 KeV to about 85 KeV of ionizing radiation from an ionizing electron beam radiation source operating at an energy potential of from about 75 KeV to about 125 KeV to selectively chemically bond the second modifying compound to the second surface of the shaped polymeric material, wherein the second surface is facing the ionizing electron beam radiation source.

2. The process of claim 1 which further comprises:

washing the shaped polymeric material to remove second modifying compound which was not chemically bonded.

3. The process of claim 1, in which the shaped polymeric material is a fibrous web.

4. The process of claim 1, in which the shaped polymeric material is a nonwoven web.

5. The process of claim 1, in which the shaped polymeric material is a shaped polyolefin material.

6. The process of claim 5, in which the polyolefin is polypropylene or polyethylene.

7. The process of claim 1, in which the second substituent is fluorine, a hydroxy group, or a carboxy group.

8. The process of claim 1, in which the first and second substituents are the same.

9. The process of claim 8, in which the first and second substituents are fluorine, a hydroxy group, or a carboxy group.

10. The process of claim 1, in which the first and second substituents are different.

11. The process of claim 10, in which each of the first and second substituents independently is fluorine, a hydroxy group, or a carboxy group.