Evonik Degussa Gmbh

Evonik Operations Gmbh

Christina Cron

Gabriele Brenner

Bernhard Schleimer

Angela Köckritz

Sandra Reemers

Uwe Stapperfenne

Jens Deutsch

Marina-Elena Schmidt

Tobias Gutmann

Katja Neubauer

Leif Ickert

Birgit Drees

Kerstin Fuchs

Benjamin Schäffner

The invention relates to hotmelt adhesives based on polyesters, having low VOC and fogging values. In particular, the invention relates to reactive hotmelt adhesives including polyesters containing at least 50 mole percent, based on the polycarboxylic acid components, of terephthalic acid or a derivative thereof and containing at least 40 mole percent, based on the polyol components, of diols of the formula HO&#x2014;(CH)&#x2014;OH with x&#x2265;6.

Adhesives with low VOC and fogging values

The invention relates to a process for producing a prepreg based on polyurethane, which is notable for high storage stability at room temperature, a two-stage reaction mechanism, and adjustable adhesion on metal surfaces. It is based on the problem of making the surface tack of the prepregs controllable during processing. The solution is to assemble the PU mixture from which the matrix originates at a later stage such that the glass transition temperature of the thermoplastic polymer is above 30&#xb0; C. For this purpose, the invention proposes two basically independent but certainly synergistic measures, namely:

Polyurethane prepregs with controllable tack

The invention relates to hotmelt adhesives based on polyesters, having low VOC and fogging values. In particular, the invention is directed to a polyester based on polycarboxylic acids and di- or polyols, wherein the polyester including dicarboxylic acids of the formula HOOC&#x2014;(CH2)x-COOH with x&#x3e;10 and diols of the formula HO&#x2014;(CH2)y-OH, with the proviso that at least 50 mole percent of the dicarboxylic acids, based on the total amount of polycarboxylic acid components, and at least 50 mole percent of the diols, based on the total amount of di- or polyols, satisfy the condition x+y&#x3e;18, in hotmelt adhesives.

The invention relates to a hybrid component part comprising a local stiffening made of a two-stage-crosslinked polyurethane-based fiber composite material, more particularly to the production of such a hybrid component part. Said invention has for its object to specify a technology which makes it possible in cost-effective fashion to effect local stiffening of metal parts with a fiber composite material in order thus to obtain a hybrid component part. It is a fundamental concept of the process according to the present invention to use a particular polyurethane formulation which in a first crosslinking reaction can be converted into a thermoplastic polymer and later in a second crosslinking reaction is fully crosslinked to afford a thermoset matrix material. The thermoplastic polymer is characterized by a good adhesion to metal surfaces. The metal can be subjected to further forming with the attached thermoplastic material. The polyurethane is subsequently thermosettingly cured and achieves its final stiffness.

Hybrid component part comprising a local stiffening composed of a two-stage-crosslinked polyurethane-based fibre composite material

The present invention relates to an isocyanate-free and preferably solvent-free process for preparing polymers containing five-membered cyclic carbonate groups. In particular, the present invention is directed to a process for preparing polymers bearing cyclic carbonate groups by reacting carboxyl-bearing polymers selected from the group including polyesters based on di- or polyols and di- or polycarboxylic acids or derivatives thereof or poly(meth)acrylates, with hydroxyl-functionalized five-membered cyclic carbonates, without addition of isocyanates.

Isocyanate-free synthesis of carbonate-modified polymers

A two-pack polyurethane adhesive for semi-structural and structural adhesive bonds which are applied in melt form and have a high handling strength wherein the two-pack polyurethane adhesive includes a first pack A containing at least one polyester A1 which is solid at room temperature and at least one polyol A2 having a hydroxyl group functionality greater than 2.0, and a second pack B containing polyurethane prepolymers having isocyanate groups.

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Velbert, Germany

Christina Cron