Fully cured crosslinkable pressure sensitive adhesive materials and method of making same

• US 3,920,877 A
• Filed: 03/23/1973
• Issued: 11/18/1975
• Est. Priority Date: 07/01/1971
• Status: Expired due to Term

• Current Assignee: W R Grace & Company - CONN (Standard Industries Holdings, Inc.)
• Original Assignee: Louis L Wood, Lundsager C. Bent, Robert C. Barber, Robert J. Bettacchi
• Inventors: Wood, Louis L., Barber, Robert C., Bettacchi, Robert J., Lundsager, C. Bent
• Primary Examiner(s): Martin, William D.
• Assistant Examiner(s): Newsome, John H.
• Application Number:
  US05/344,305
• Time in Patent Office: 970 Days
• Field of Search: 110/93.31,122P,122PA,122PF,161UZ 260/79,79.5R
• US Class Current: 428/345
• CPC Class Codes: C08G 18/835 Unsaturated polymers modified by compounds containing a thiol group
• CPC Class Codes: C08G 75/045 from mercapto compounds and unsaturated compounds
• CPC Class Codes: C08G 75/12 Polythioether-ethers C08G75/0245 takes precedence
• CPC Class Codes: C09J 7/38 Pressure-sensitive adhesives [PSA]
• CPC Class Codes: Y10T 428/2809 including irradiated or wave energy treated component

Abstract

Semi-solid pressure sensitive polythioether polymer systems are formed by quickly curing liquid components by UV or Beta irradiation. These polymer systems are tacky when fully cured and are useful as pressure sensitive adhesives. These polymers are characterized in that they are comprised of liquid polyene compositions containing at least two unsaturated carbon to carbon bonds per molecule located terminally or pendant on the main chain backbone and are cured to odorless tacky elastomeric products with polythiols under ambient conditions in the presence of a free radical generator. The cured products in a preferred embodiment are used as adhesives that are firmly bonded to flexible substrates and are useful as adhesive tapes, and adhesives for self-adhering labels, tiles, plaques, posters, wall coverings and other articles.

Claims

1. A PRESSURE-SENSITIVE, NORMALLY TACKY ADHESIVE COMPRISING A SUBSTANTIALLY COMPLETELY CROSSLINKED OR CURED POLYTHIOETHER CONSISTING ESSENTIALLY OF THE REACTION PRODUCT OF A LIQUID POLYENE CONTAINING AT LEAST TWO UNSATURATED CARBON TO CARBON BONDS PER MOLECULE AND A LIQUID POLYTHIOL CONTAINING AT LEAST TWO THIOL GROUPS PER MOLECULE AND THE TOTAL COMBINED FUNCTIONALITY OF THE UNSATURATED CARBON TO CARBON BONDS PER MOLECULE IN THE POLYENE AND THE THIOL GROUPS PER MOLECULE IN THE POLYTHIOL IS GREATER THAN FOUR, SAID POLYENE AND SAID POLYTHIOL BEING OF SUCH MOLECULAR WEIGHT THAT UPON COMPLETE CROSSLINKING THE POLYTHIOETHER HAS A THEORETICAL CROSSLINK DENSITY IN THE RANGE 0.001-0.230 MILLIEQUIVALENTS OF CROSSLINK SITES PER GRAM.

2. A pressure sensitive adhesive tape comprising a flexible support having thereon a layer of the adhesive of claim 1.

3. A method for producing a pressure sensitive adhesive tape which comprises coating a support on at least one side thereof with a composition comprising a liquid polyene containing at least two unsaturated carbon to carbon bonds per molecule and a liquid polythiol containing at least two thiol groups per molecule, the combined functionality of the carbon to carbon unsaturation in the polyene and the thiol groups in the polythiol being greater than four and curing said composition to form a substantially completely crosslinked or cured tacky, adhesive polythioether polymer, said polyene and said polythiol being of such molecular weight that upon complete crosslinking the polythioether has a theoretical crosslink density in the range 0.001 to 0.230 milliequivalents of crosslink sites per gram.

4. The method according to claim 3 wherein the curing is performed by UV irradiation in the presence of a photoinitiator.

5. The method according to claim 3 wherein the curing is performed by beta radiation.