Method of polymerizing ethylenically-unsaturated materials using ionizing radiation

Patent metadata

Field	Value
Publication number	US-9708514-B2
Application number	US-201314647924-A
Country	US
Kind code	B2
Filing date	Dec 6, 2013
Priority date	Dec 14, 2012
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

Methods of (co)polymerizing ethylenically-unsaturated materials, including the steps of providing a non-deaerated mixture of free radically (co)polymerizable ethylenically-unsaturated material in a batch reactor, exposing the non-deaerated mixture to a source of ionizing radiation for a time sufficient to initiate (co)polymerization of at least a portion of the free radically (co)polymerizable ethylenically-unsaturated material, and allowing the free radically (co)polymerizable ethylenically-unsaturated material to (co)polymerize under essentially adiabatic conditions while continuing to expose the mixture to the source of ionizing radiation for a time sufficient to yield an at least partially (co)polymerized (co)polymer. The ethylenically-unsaturated materials are selected from vinyl-functional monomers, vinyl-functional oligomers, vinyl-functional macromers, and combinations thereof. The mixture is preferably free of thermally-induced or UV-induced free radical polymerization initiators. The source of ionizing radiation may be a gamma ray source, an x ray source, an electron beam source with an emission energy greater than 300 keV, and combinations thereof.

First claim

The invention claimed is:

1. A method comprising:
(a) providing a non-deaerated mixture comprising free radically (co)polymerizable ethylenically-unsaturated material in a batch reactor;
(b) exposing the non-deaerated mixture to a source of ionizing radiation for a time sufficient to initiate (co)polymerization of at least a portion of the free radically (co)polymerizable ethylenically-unsaturated material; and
(c) allowing the free radically (co)polymerizable ethylenically-unsaturated material to (co)polymerize under essentially adiabatic conditions while continuing to expose the mixture to the source of ionizing radiation for a time sufficient to yield an at least partially (co)polymerized (co)polymer, wherein the mixture is non-heterogeneous and substantially free of thermally-induced (co)polymerization initiators.

2. The method of claim 1 , wherein the source of ionizing radiation is selected from a gamma ray source, an x-ray source, an electron beam source having an emission energy of greater than 300 keV, and combinations thereof.

3. The method of claim 1 , wherein the mixture is blanketed with an inert gas to reduce oxygen levels in a vapor space of the batch reactor in step (a), step (b), step (c), or combinations thereof.

4. The method of claim 1 , wherein the mixture further comprises a chain transfer agent.

5. The method of claim 1 , wherein the concentration of chain transfer agent in the mixture is from 0.01% to 20% by weight, based upon the total weight of the mixture.

6. The method of claim 1 , wherein the mixture is exposed to ionizing radiation for a time sufficient to receive a dose of ionizing radiation up to 100 kiloGray.

7. The method of claim 1 , wherein the mixture further comprises a photoinitator.

8. The method of claim 1 , wherein the free radically (co)polymerizable ethylenically-unsaturated material is comprised of vinyl-functional monomers, vinyl-functional oligomers, vinyl-functional macromers, or a combination thereof.

9. The method of claim 1 , wherein the free radically (co)polymerizable ethylenically-unsaturated monomers are comprised of difficult to (co)polymerize monomers selected from N-vinyl pyrrolidone, N,N-dimethyl acrylamide, (meth)acrylic acid, acrylamide, N-octyl acrylamide, styrene, vinyl acetate, and combinations thereof.

10. The method of claim 1 , wherein the mixture further comprises a non-reactive diluent selected from the group consisting of plasticizers, tackifiers, particulate fillers, non-volatile organic solvents, and combinations thereof.

11. The method of claim 10 , wherein the non-reactive diluent is selected from a plasticizer.

12. The method of claim 10 , wherein the non-reactive diluent is selected from a tackifier.

13. The method of claim 10 , wherein the non-reactive diluent is selected from a particulate filler.

14. The method of claim 10 , wherein the non-reactive diluent is added at a level of about 1% to about 25% by weight, based upon the total weight of the mixture.

15. The method of claim 1 , wherein the mixture has a concentration of the free radically (co)polymerizable ethylenically-unsaturated monomers less than 3% by weight of the total weight of the mixture, at the completion of step (c).

16. The method of claim 1 , wherein the mixture has a gel content less than 10% by weight, based on the total weight of the mixture, at the completion of step (c).

17. A pressure sensitive adhesive prepared according to claim 1 , wherein the pressure-sensitive adhesive exhibits a FOG value, determined according to VDA-278, of no more than 1,000 μg/g.

18. The pressure sensitive adhesive of claim 17 , wherein the at least partially (co)polymerized (co)polymer exhibits an optical activity substantially identical to an optical activity of the mixture comprising free radically (co)polymerizable ethylenically-unsaturated material.

19. A pressure sensitive adhesive article incorporating the pressure sensitive adhesive of claim 17 , wherein the pressure sensitive adhesive article comprises at least one layer of the pressure sensitive adhesive on a major surface of a substrate.

Assignees

• 3M Innovative Properties Co

Inventors

• Myers Sasha B
• O'Neal Daniel J
• Richter Karl B
• Tran Thu-Van T
• Hamer Craig E

Classifications

• C09J133/02

  Homopolymers or copolymers of acids; Metal or ammonium salts thereof · CPC title

• C08F2/46

  Polymerisation initiated by wave energy or particle radiation · CPC title

• C09J133/08

  Homopolymers or copolymers of acrylic acid esters · CPC title

• C09J133/10

  Homopolymers or copolymers of methacrylic acid esters · CPC title

• C08F2/54 Primary

  by X-rays or electrons · CPC title