Fluorescent whitening agent compositions

Abstract

Disclosed are compositions containing:a) 25-60% by weight of compound of formula (I)wherein X is hydrogen, an alkali or alkaline-earth metal, ammonium, alkylammonium and alkanolalkylammonium, alkanolammonium;b) at least 25% by weight of urea;up to 50% by weight of water.

Description

[0001]The present invention relates to fluorescent whitening compositions, processes for the preparation of said compositions, stable aqueous solutions of said compositions and the use of said compositions to bleach textile fibres and paper and in detergents.PRIOR ART[0002]The use of whitening agents to impart a higher degree of whiteness to products like paper, cardboard, fabrics and non-woven fabrics is well known. The whitening agents most commonly used in the paper and cardboard industry are derivatives of 4,4′-bis-[1,3,5-triazinyl]-diaminostilbene-2,2′-disulphonic acid substituted at the triazine ring with anilino and alkanolamino groups. The anilino groups can in turn contain other sulphonic groups, but as they increase the solubility in water of the corresponding molecules, they reduce the affinity of said molecules for the cellulose fibres constituting paper and fabric, leading to lower performance in terms of whiteness.[0003]For reasons of ease of processing, the industry r...

AI Technical Summary

Benefits of technology

The present invention provides a concentrated composition of whitening agents that is stable in aqueous solution, even in the presence of small amounts of inorganic chlorides, and is easy to produce and dilute. The concentrated composition is also resistant to low temperatures and can be used in environments with temperatures below 0°C. The composition contains a specific optical brightener that is solubilized with a solubilizing additive, reducing the amount of solubilizing additive required. The composition is stable and can be easily regenerated. The optical brighteners used in the composition can be synthesized using a process involving a reaction with a specific amino compound. The concentrated composition can be produced by mixing the three ingredients in any order at temperatures from 1°C to 150°C.

Problems solved by technology

The anilino groups can in turn contain other sulphonic groups, but as they increase the solubility in water of the corresponding molecules, they reduce the affinity of said molecules for the cellulose fibres constituting paper and fabric, leading to lower performance in terms of whiteness.

However, their presence is undesirable, because when the brightener solution has been used, they are discharged into the waste water, and are consequently pollutants.

The potential pollutant content of these formulations is very high and undesirable.

A further problem derives from the inevitable presence in the whitening agent solutions of inorganic chlorides such as sodium chloride, which derive from the whitening agent synthesis processes.

In fact, all the industrial processes for the production of stilbene whitening agents substituted with triazine involve the use of cyanuryl chloride as reagent, whose reaction in successive steps with the various necessary amine products inevitably leads to the generation of large amounts of inorganic chlorides which are difficult to eliminate.

As the residual inorganic chlorides generate instability in the concentrated aqueous solutions of whitening agents, it has been essential to date to reduce their content significantly, inevitably using expensive osmotic separation techniques to obtain aqueous solutions which are stable over time.

All the compositions in stable solution described so far suffer from the drawback of being too dilute.

Moreover, if any form of instability arises, said solutions produce sediments of packed product which are very difficult to recover, especially if the solution is in a container that cannot be stirred, like an ordinary tank.

Finally, in view of the low concentration of optical brightener, their transport is uneconomical.

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