Method for Producing Cohesive Polyacrylate Adhesive Compounds with a Narrow Molar Mass Distribution

• US 20140329971A1
• Filed: 09/28/2012
• Published: 11/06/2014
• Est. Priority Date: 11/16/2011
• Status: Active Grant

• Current Assignee: Tesa SE (maxingvest GmbH & Co. KGaA)
• Original Assignee: Tesa SE (maxingvest GmbH & Co. KGaA)
• Inventors: Prenzel, Alexander
• Granted Patent: US 9,777,198 B2
• Time in Patent Office: Days
• US Class Current: 525/297
• CPC Class Codes: C08F 2/38 Polymerisation using regulators, e.g. chain terminating agents , e.g. telomerisation
• CPC Class Codes: C08F 220/06 Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
• CPC Class Codes: C08F 220/1804 C4-(meth)acrylate, e.g. butyl (meth)acrylate, isobutyl (meth)acrylate or tert-butyl (meth)acrylate
• CPC Class Codes: C08F 220/1808 C8-(meth)acrylate, e.g. isooctyl (meth)acrylate or 2-ethylhexyl (meth)acrylate
• CPC Class Codes: C08F 2438/03 Use of a di- or tri-thiocarbonylthio compound, e.g. di- or tri-thioester, di- or tri-thiocarbamate, or a xanthate as chain transfer agent, e.g . Reversible Addition Fragmentation chain Transfer [RAFT] or Macromolecular Design via Interchange of Xanthates [MADIX]
• CPC Class Codes: C09J 133/08 Homopolymers or copolymers of acrylic acid esters

Abstract

The invention relates to a method for producing polyacrylate adhesive compounds with a narrow molar mass distribution by means of a radical polymerization and a subsequent increase of the molar masses by reacting with bis- or multi-dienyl compounds, in particular with α,ω-bis-dienyl compounds, in order to increase the cohesion in particular.

Claims

1. A method for producing acrylate-based polymers, wherein first a controlled radial polymerization reaction of an initial reaction charge comprising at least one acrylate-based monomer is carried out in the presence of at least one chain transfer agent (CTA) having at least one functional group S—

C═

X, where X=S, O or N, the CTA being selected from the group consisting of dithioesters, dithiocarbonates, dithiocarbamates, trithiocarbonates, imidodithiocarbonates, and xanthates (“

RAFT CTAs”

), the majority of the CTA molecules being incorporated into the polymer chains that form, whereby the polymer chain in question has the functional group of the incorporated CTA, wherein at least one dienyl compound comprising at least one diene unit which has two conjugated double bonds is contacted with the polymers thus obtained, so that hetero-Diels-Alder reactions are brought about between the conjugated double bonds of the diene unit of each dienyl molecule and a double bond C═

X of the functional group S—

C═

X of the majority of the polymer chains, so that the corresponding polymer chains are linked to the respective dienyl molecule.

2. The method as claimed in claim 1 for preparing acrylate-based polymers, wherein the dienyl compound is a bisdienyl comprising at least two diene units, so that hetero-Diels-Alder reactions are brought about between the conjugated double bonds of the two diene units of a bisdienyl molecule and one double bond C═

X of the functional group S—

C═

X of each polymer chain, so that at least two polymer chains are linked by means of the bisdienyl molecule.

3. The method as claimed in claim 2, wherein two of the diene units of the bisdisdienyl compound are terminal so that the bisdienyl compound is an α

,ω

-bisdienyl compound.

4. The method as claimed in claim 1 wherein the polymers obtained are admixed with at least one chemical compound from which it is possible in situ to generate a chemical compound which has at least one or two conjugated double bonds.

5. The method as claimed in claim 1 wherein the compounds having the conjugated double bonds in the unit C═

C—

C═

C are not heterosubstituted.

6. The method as claimed in claim 1 wherein the diene units of the dienyl and/or bisdienyl compounds are selected independently of one another from the group consisting of 1,3-butadienes, 1-methoxy-1,3-butadienes, 2,4-hexadienes, (2E)-2,4-pentanedienoic acid, sorbic acid and its esters, 2,4-hexadiene-1,6-dicarboxylic acid and its esters, 1,3-cyclohexadienes, 1-methoxy-1,3-cyclohexadienes, anthracene, substituted and unsubstituted furans, substituted and unsubstituted thiophenes, substituted and unsubstituted cyclopentadienes, (E)-1-methoxy-3-trimethylsilyloxy-1,3-butadiene, 1-(trimethylsiloxy)-1,3-butadiene, 1-(triethylsiloxy)-1,3-butadiene, and (1E,3Z)-1-methoxy-2-methyl-3-(trimethylsilyloxy)-1,3-pentadiene.

7. The method as claimed in claim 1 wherein the chain transfer agent (CTA) used is a dithioester having one or more heteroaromatic substituents and/or having one or more phosphonate substituents in the acid radical.

8. The method as claimed in claim 1 wherein the acrylate-based polymers obtained are used as adhesives or further-processed to adhesives.

9. The method as claimed in claim 7 wherein the adhesives are pressure sensitive adhesives.

12. The method as claimed in claim 7 wherein the chain transfer agent is selected from the following compounds:

10. Acrylate-based polymers comprising at least one cyclo-1-X-hex-3-ene unit in the majority of the polymer chains, with X=S, O and/or N.

11. Acrylate-based polymers as claimed in claim 10 comprising at least two cyclo-1-X-hex-3-ene units in the majority of the polymer chains, with X=S, O and/or N.