Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Patent
1998-01-08
1999-09-21
Hampton-Hightower, P.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
528322, 523417, 525377, 525416, 524273, C08G 6908, C08L 7700
Patent
active
059555670
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a new process for the production of cross-linked cationic polymers for the treatment of paper and to the use of the crosslinked cationic polymers as wet strength resins.
DISCUSSION OF THE RELATED ART
The generic term "paper" encompasses about 3,000 different types and articles which can differ, in some cases considerably, in their fields of application and their properties. For their production, aqueous 1 to 5% by weight suspensions of cellulose fibers are applied in thin layers to screens on which they are dewatered at high speeds to a solids content of around 40% by weight by application of heat and mechanical pressure. While the still moist raw paper is dried in further steps, the water squeezed off returns to the circuit.
In modern paper mills, it is regarded as important for economic and ecological reasons to keep the water circuit substantially closed. To this end, the process water must of course be free from waste or should only contain waste which is easy to reuse. Particular importance is attributed to the so-called AOX content of the process water, i.e. the content of unwanted halogen compounds.
Unfortunately, the papermaking process unavoidably involves the addition of various additives, including for example fillers, defoamers, dyes, retention agents and auxiliaries which improve the mechanical strength of the paper and which are known as dry or wet strength resins, depending on the field of application. Since the additives accumulate in the process water together with cellulose fibers over a period of time, there is a considerable need for ecologically safe products.
The additives which are regarded as critical in this respect include, in particular, wet strength resins which are crosslinked polyaminoamides. These substances, which are also known commercially as Fibrabones.RTM., are produced from polyaminoamides of which the chains are crosslinked via nitrogen atoms using epichlorohydrin. U.S. Pat. No. 5,116,887, U.S. Pat. No. 5,120,773, U.S. Pat. No. 5,239,047, U.S. Pat. No. 5,350,796 (Henkel Corp.) and European patent application EP-A1 0 553 575 (Hercules) are cited as representative of the extensive prior art available on this subject.
It has been found that there is a direct connection between the degree of crosslinking of the wet strength resins and the improvement in the strength of the paper treated with them. From this point of view, it is advisable to crosslink all the nitrogen groups in the polyaminoamide available for crosslinking through epichlorohydrin units. On the other hand, the reaction of each nitrogen group with epichlorohydrin leads to the elimination of hydrogen chloride (which remains bound as adduct) and, hence, to the presence of AOX in the product which is extremely undesirable for the reasons explained above. Accordingly, attempts have hitherto been made to maintain a balance between the two conflicting parameters (degree of crosslinking and AOX content). In actual fact, however, the results are unsatisfactory because, in many cases, the performance properties are not entirely acceptable, nor is the ecological compatibility of the products by any means adequate.
Accordingly, the problem addressed by the present invention was to provide a process for the production of wet strength resins which would be free from the disadvantages mentioned.
DESCRIPTION OF THE INVENTION
The present invention relates to a process for the production of crosslinked cationic polymers, in which polyaminoamides nitrogen available for quaternization, of a quaternizing agent and molar quantity of epichlorohydrin corresponding to the content of non-quaternized nitrogen.
It has surprisingly been found that the performance properties of the crosslinked polyamides can be significantly improved by quaternizing a particular quantity of nitrogen groups in the polymer before crosslinking without the wastewater being additionally polluted with AOX.
The polyaminoamides suitable as starting materials for the purposes of the invention are commercial
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Bigorra Llosas Joaquim
Pi Subirana Rafael
Hampton-Hightower P.
Henkel Kommanditgesellschaft auf Aktien
J. Murphy Glenn E.
Jaeschke Wayne C.
Szoke Ernest G.
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