Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Treating polymer containing material or treating a solid...
Patent
1993-12-15
1996-05-14
Page, Thurman K.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Treating polymer containing material or treating a solid...
528405, B01J 3904, C08G 5900, C08F 606, C08F 610
Patent
active
055168850
DESCRIPTION:
BRIEF SUMMARY
The invention pertains to a process for the preparation of a water-soluble, nitrogen-containing, epihalohydrin-based resin comprising the step of subjecting the resin to an organic halogen reducing after-treatment.
Resins of the above type, mainly polyaminoamide-epihalohydrin resins, are well-known and find wide usage as wet-strength agents for paper. Epihalohydrin is known to impart wet-strength efficacy to polyaminoamides, but also causes the eventual resins to contain large amounts of organic halogen. A significant number of efforts to overcome this problem while retaining the product's wet-strength imparting effect has been reported.
Thus, a process of the type mentioned in the opening paragraph, which can be based on conventional previous reaction steps, e.g. comprising the reaction of polyaminoamide and epihalohydrin, is known from published European Patent Application No. 0 349 935. Said step consists of contacting the prepared resin with a base to convert it into a product having a pH >8, after which neutralization can take place. In this manner the organic chlorine content can be reduced to as little as 1% by weight. However, it is disclosed that, irrespective of the extent of the reduction of the organic chlorine content, the total chlorine content will remain unchanged. This is a serious limitation of the effect of the after-treatment, the remaining inorganic chlorine being a potential source of newly formed organic chlorine since it is the aqueous resin solution in which a new equilibrium will be established.
The invention has for one of its objects to obviate this drawback by providing a method for reducing the total chlorine content. Also, the invention meets the objective of further reducing the content of organic halogen without the resin's favourable properties being adversely affected.
In order to meet these and other objectives, the invention consists in that in a process of the above-described known type the after-treatment comprises contacting the resin with a basic ion-exchanger.
Unexpectedly, the after-treatment according to the present invention results in the resin subjected to it having a surprisingly low total halogen content of 1% by weight or lower, calculated on solid resin. It should be noted that in EP 389 935 the total halogen content remains at a level of 13,52% by weight, calculated on solid resin. So, clearly, the process according to the invention results in an unobvious improvement, further evidenced by the fact that the total halogen content in the novel resins prepared in accordance with the invention is even lower than the organic halogen content of the known resins.
Evidently, the total halogen content of the resins prepared in accordance with the present invention being considerably lower than in known resins, the resulting organic halogen content is lower also, viz. below 0.1% by weight, calculated on solid resin. In this respect it should be noted that .the following art-recognized definitions of halogen contents apply to the description of subject invention: the sum of all organic and inorganic halogen present, i.e. total halogen minus inorganic halide ions. widely used in the art of wet-strength agents for paper. It indicates all organic halogen that can be determined by means of adsorption onto activated carbon using the method according to DIN 38409, part 14. 1-halo-2,3-propane diol (MXP), which are the most important undesired by-products formed when a resin is prepared from a reaction mixture containing epihalohydrin. Since the most common epihalohydrin in the art is epichlorohydrin, by-products content frequently indicates DCP (dichloro propanol) and MCP (mono chloro propane diol).
A different approach towards low halogen contents is followed in EP 335 158, which discloses substitution of epihalohydrin by halogen-free crosslinkers. The crosslinker being allowed to contain a maximum of 15 mole % epihalohydrin, the resin is not an epihalohydrin-based resin in accordance with the present invention. Particularly low halogen values are disclosed if no epiha
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Gorzynski Marek
Pingel Andreas
Akzo Nobel N.V.
Kulkosky Peter F.
Mancini Ralph J.
Morris Louis A.
Page Thurman K.
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