Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Biocides; animal or insect repellents or attractants
Reexamination Certificate
2000-10-16
2002-04-23
Badio, Barbara P. (Department: 1616)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Biocides; animal or insect repellents or attractants
C424S409000, C424S411000, C424S413000, C514S764000, C523S122000
Reexamination Certificate
active
06375967
ABSTRACT:
The present invention relates to a regenerated cellulose-based cellular material with a long-term resistance to microorganisms—bacteria and/or fungi—and to a process for its preparation.
The present invention relates very particularly to sponges (voluminous cellular cellulosic products) and sponge-cloths (flat cellular cellulosic products (generally with a thickness less than or equal to 10 mm and often of the order of 5 mm)), which are intended especially for cleaning tasks, household maintenance or body hygiene and which have effective and long-term protection against the action of microorganisms. Those skilled in the art are aware that, after wringing, this type of material always retains a certain amount of water in its pores, which, in the absence of an appropriate biocidal treatment, encourages the development of foul-smelling and unhealthy microorganisms. It is therefore desirable to give these materials a long-term biocidal capability to combat the microorganisms which are present either in their structure or in the water with which they are almost permanently impregnated.
The base substrate of the materials of the invention is artificial sponge as obtained by the viscose process described especially in patent application FR-A-812 502. This process, which is familiar to those skilled in the art, is described in detail later in the present text with reference to the process for the preparation of the materials of the invention. Said process is based on a chemical modification of the cellulosic starting material. (Said cellulosic starting material, in this case wood pulp initially converted to alkaline cellulose, reacts with carbon disulfide to give cellulose xanthate, which is soluble in aqueous soda solution). The cellulose modified in this way (converted to one of its derivatives) has to be regenerated at the end of said process. The regeneration is carried out under harsh temperature and pH conditions.
According to the prior art, various methods have already been proposed for imparting long-term biocidal properties to cellular substrates based on regenerated cellulose.
These methods comprise the introduction and fixing of biocide(s) within the cellulosic structure of said substrates. Said introduction can be effected:
before the regeneration step; in this case, however, it is necessary to prevent the biocide from being released and/or destroyed during said regeneration;
after regeneration; the biocide can only be introduced if it is soluble or dispersible in an aqueous solution; in this case it is then essential to fix it in the porous structure so as to prevent it from being released during the first uses.
According to the prior art, it has been proposed in particular to introduce a biocidal agent into the semi-finished product (after regeneration of the cellulose). Said agent is fixed in the cellulose network either by precipitation—this technique is illustrated in patents U.S. Pat. No. 3,018,192, FR-A-1 200 663 and FR-A-1 345 614—or by a technique which combines precipitation with binding—the latter technique is illustrated in patent application EP-A-0 358 572 (the cellulosic product obtained contains the biocide, in solid form, mechanically trapped in a binder)—. The different variants of this method are adapted to cellulosic cellular products. However, insofar as they are based on precipitation, they impose the use of biocides capable of carrying a cationic charge, and post-treatments which can be expensive.
It has also been proposed:
to generate in situ a metal complex based on three components:
a chelating polymer and more particularly chitosan;
a transition metal (especially Zn) ion capable of forming a chelate with said chelating polymer; and
an anti-microbial agent capable of forming a chelate with said transition metal ion, and more particularly an alkyl dithiocarbamate, a thiazole, an imidazole or a pyrithione (or one of its salts).
In general, said polymer and said anti-microbial agent are respectively introduced upstream and downstream of the cellulose regeneration step. This complex technique has been described in WO-A-94 12034;
to introduce the biocidal agent, before regeneration of the cellulose, in the form of particles enclosed in a matrix (<<in protected form>>). The matrix of said particles, loaded with biocidal agent, serves a dual purpose:
it enables said biocidal agent to withstand the harsh conditions of the regeneration; and
it makes it possible to control the rate of release of said biocidal agent.
This technique has been described by the Applicant in EP-A-617 074;
to introduce a particular biocidal agent together with a binder, in the process of manufacture of sponges. Said particular biocide is introduced in the viscose, in solution in an organic solvent or in a mixture with a surfactant, upstream of the regeneration in basic medium (before the porophoric agent). This technique is described in JP-A-47 50867. For its implementation, the inventors explicitly excluded many biocides, including pentachlorophenol, and therefore implicitly excluded triclosan (which belongs to the same family of chlorinated derivatives of phenol and which possess physico-chemical characteristics which are close to those of said pentachlorophenol). Said inventors only retained bis(tributyltin) oxide and tributyltin fluoride.
More generally, the introduction of biocides has been described in contexts which are different to that of the manufacture of artificial cellular cellulosic products.
The following has notably been described:
in DE-A-32 14610, synthetic fibers known as anti-microbial fibers, obtained by the melting of a mass, dissolution of the anti-microbial agent in said mass and melting and spinning. The synthetic fibrous material obtained is totally unconnected with the products of the invention. The process for its manufacture is totally unconnected with the process of the invention (melting/solubilisation and then regeneration);
in EP-A-0 709 507, the introduction of a biocide during the manufacture of a latex and the use of said latex thus loaded with said biocide for the binding of nonwovens;
in DE-A-1 288 747, synergistic biocide combinations. Said combinations are described per se, with reference to the biocidal efficiency. The problem of the fixing of a biocide or a combination of biocides to any substrate is not addressed;
in BE-A-644 153, a process for the protection of organic materials against micro-organisms. According to a variant of said process, the biocidal products—1-phenoxy-2-hydroxybenzenes—are introduced into said materials. The means of introduction are not described in detail for every type of material cited. In particular, no indication is found which refers to artificial cellulosic cellular materials, nor are any precision found as to the means of fixing, in general, of the biocidal products introduced, as to the stability of said fixing, as to the durability of the protection imparted etc. Only the introduction of triclosan is illustrated, in non-fibrous viscose, prior to the acidic regeneration of said viscose, to obtain films of regenerated cellulose which as such possess a good resistance to bacterial attack.
With reference to the technical problem of the effective and long-term protection of regenerated cellulose-based cellular materials against the action of microorganisms, the Applicant proposes, within the framework of the present invention, an original solution which is based on the choice of a particular biocide and on its means of fixing within the cellulosic matrix. Said original solution is suitable both for sponges and sponge-cloths despite the conditions for obtaining said sponges and sponge-cloths (see later on) being substantially different.
The selected biocide is interesting from several points of view:
it is per se a very high-performance product: it is effective at reasonable doses, it is non-toxic, it has a broad spectrum, etc.;
by virtue of its physico-chemical characteristics, it can be used in cellular cellulosic materials without being conditioned and, more particularly, without being enclosed
Bedue Olivier
Chalvin Christophe
Badio Barbara P.
Financiere Elysees Balzac
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