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AssigneeTesa SE
InventorsMarc Husemann, Stephan Zollner, Nico Diamantis
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The invention relates to a method for the production of cross-linked acrylate contact adhesive materials characterised in that polyacrylates are firstly produced from the following monomers by free-radical (co-)polymerisation: (d) acrylic and methacrylic acid monomers with the following structure, where R1═H or CH3 and R2=an alkyl chain with 2-20 C atoms, at a proportion of 45 99.5 wt. % of the monomer mixture, (e) one or several carboxylic acid anhydrides, containing olefinic double bonds, at a proportion of 0.5-25 wt. % of the monomer mixture, (f) further unsaturated olefinic monomers containing functional group A, at a proportion of 0-30 wt. % of the monomer mixture. The polymers thus produced are concentrated to give a polyacrylate material with a solvent content ≦2 wt. %, further monomers are added to the polyacrylate material, which contain at least two functional groups B and C, whereby the group B can undergo polymerisation-type reactions with the carboxylic acid anhydrides and the groups C are cross-linkable groups. A reaction between the functional groups B and the carboxylic acid anhydrides occurs, which links the monomer containing the functional group B to the polymer in the form of a sidechain. After the reaction between the functional group B and the carboxylic acid anhydride a cross-linking of the polymers is carried out by means of an energetic irradiation.
A process for preparing crosslinked acrylic pressure sensitive adhesives which comprises
The process of one of the preceding claims, characterized in that, between the reaction of the functional groups B with the carboxylic anhydride and the crosslinking, the pressure sensitive adhesive is applied from the melt to a backing.
The process of one of the preceding claims, characterized in that the addition of the monomers possessing the functional groups B and C and the reaction of the functional groups B with the carboxylic anhydride take place directly after the concentrating step, in particular in an extruder.
The process of one of the preceding claims, characterized in that the solvent content after concentration is ≦0.5% by weight.
The process of one of the preceding claims, characterized in that the functional groups B of the monomers are hydroxyl groups, alkoxy groups, mercapto groups, thioether groups, unsubstituted and substituted amino groups, oxalines and/or unsubstituted or substituted amido groups.
The process of one of the preceding claims, characterized in that the functional groups C of the monomers are vinyl groups, acrylate groups and/or methacrylate groups.
The process of one of the preceding claims, characterized in that monomers containing functional groups B and C that are used comprise 2-hydroxyethyl acrylate (2-HEA, acrylic acid 2-hydroxyethyl ester), hydroxypropyl acrylate (acrylic acid 3-hydroxypropyl ester), 2-hydroxy-ethyl methacrylate (2-HEMA, methacrylic acid 2-hydroxyethyl ester) and/or hydroxypropyl methacrylate (methacrylic acid 3-hydroxypropyl ester).
The process of one of the preceding claims, characterized in that the molar ratio of the number nB of the functional groups B of the added monomers to the number nCSA of the copolymerized carboxylic anhydride units, nB/nCSA, lies between 0.8 and 1.2, very preferably between 0.8 and 1.
The process of one of the preceding claims, characterized in that catalysts added to the polyacrylate composition, especially Lewis acids, particularly p-toluenesulfonic acid, or Lewis bases, particularly 4-vinylaniline.
The process of one of the preceding claims, characterized in that the reaction temperature of the polymer-analogous reaction is chosen to be between 60° C. and 180° C., in particular between 10 and 160° C.
The process of one of the preceding claims, characterized in that resins or other additives, such as aging inhibitors, light stabilizers, ozone protectants, fatty acids, plasticizers, nucleators, blowing agents, accelerators and/or fillers are added to the monomer mixture or to the acrylic pressure sensitive adhesive.
The process of one of the above claims, characterized in that crosslinkers are added to the polyacrylate composition to be crosslinked, especially difunctional and/or polyfunctional acrylates and/or methacrylates or photoinitiators.
The process of one of the preceding claims, characterized in that electron beams or UV radiation are used as high-energy radiation for the crosslinking.
The use of an acrylic pressure sensitive adhesive prepared by a process according to at least one of the preceding claims for an adhesive tape, the acrylic pressure sensitive adhesive being applied to one or both sides of a backing.
Dependencies are inferred from the claim text.