FR2635961A1 - PROCESS FOR PROVIDING SUSTAINABLE BIOCIDAL PROPERTIES TO A CELLULOSE-BASED CLEANING AND / OR TOWING PRODUCT - Google Patents

Abstract

A biocide and a binder are simultaneously precipitated in the pores of the sponge, the latter allowing a controlled release of the biocide into the water retained by the pores of the sponge.

Description

Process for imparting sustainable biocidal properties to a

  cleaning and / or wiping product made from cellulose.

  The present invention relates to the field of articles or substrates, flexible and porous, compressible and elastic,

  intended for housekeeping and personal care.

  Among these articles, mention may in particular be made of cellulosic sponges, expanded polymer foams and nonwovens

  cellulose and synthetic polymerised materials.

  It is known that a flexible and porous article, even compressed, always retains in its pores a certain amount of moisture which, in the absence of appropriate biocides, promotes the development of malodorous or unhealthy microorganisms. It is therefore desirable to give such a flexible and porous article a lasting disinfecting power with respect to the water of which it is

soaked.

  Various methods have been proposed, according to the state of the art, to solve this problem. Thus, according to a first route, the biocide can be mixed with the monomers used for the manufacture, by polymerization, of the flexible and porous article. Such a pathway is described, for example, in the following documents: PCT / US84 / 01264 (WO / 85/02422), AVTEX; US-A-4,476,251, CIANCOLO et al., OLIN CORP .; U.S. Patent No. 4,177,056, MUELLER et al., CIBA-GEIGY;

  FR-A-2,372,623, FOKUOKA; US-A-4,654,234, ROSIN et al., OLIN CORP.

  This method is however not applicable to porous materials

cellulosic compressibles.

  According to another route described in US-A-4,525,411, SCHMIDT, FIRMA C. FREUDENBERG, the porous water-retaining material consists of polyamide, polypropylene or cellulose microfibers of which an external portion is microporous (pores of 0.01 to 0.5 -m); these micropores can absorb and retain a biocide which is then released gradually to use. This document further indicates that, for practical applications, the fibrous structure of the article is completed by a nonwoven bond

  to microfibres by welding or binder.

  In yet another way, a biocide can be fixed in the pores of the sponge by immobilization by means of a precipitating agent or binder. Thus, the documents FR-A-1 200 663 and US-A-3 018 192, ENKA CORP., Describe the treatment of cellulosic sponges on the one hand by an aqueous solution of biocide (in this case a salt). quaternary ammonium) and, on the other hand, by an aqueous solution of carboxymethylcellulose or a salt thereof, the order of the treatments being arbitrary. The reaction product between a quaternary ammonium salt and, for example, carboxymethylcellulose adheres to the cellulosic material of the sponge. Similarly, FR-A-1 345 614, DILLON, DU PONT, describes the impregnation of cellulosic sponges, on the one hand, with a biocidal quaternary ammonium salt and, on the other hand, by a Amino rosin resin and anionic surfactide. During this reaction, a water-insoluble precipitate is formed in which

  the biocide is incorporated and resists subsequent leaching.

  US-A-4,615,937, MP BOUCHETTE, JAMES RIVER CORP., Describes the "sanitization" of a cellulosic non-woven terrycloth or sponge by biocidal agents fixed by substantive bonds, both to the fibers as well as to the non-woven binder. As

  binder, there are cited acrylic, butadiene-styrene, ethyl,

  lene, vinyl acetate and acrylonitrile-butadiene. As biocides, trialkoxysilanes containing a group

quaternary ammonium.

  DE-A-2730266, COLLO GMBH, discloses a cellulosic cleaning pad or sponge formed of a foam containing, bound, particulate active agents, especially biocides. The binders mentioned include epoxy, polyurethane and polyvinyl alcohols. From the practical point of view, according to this document, the additive is incorporated in the binder and, subsequently,

  attaches the binder to the surface of the sponge material.

  Since the techniques of the prior art have undeniable qualities, they also have certain shortcomings, namely either their complexity and their cost, or a loss of their

efficiency over time.

  Also, the techniques according to which the biocide is fixed essentially permanently to the flexible and porous article or incorporated in an insoluble manner in the material thereof provide products whose effectiveness is limited in time because little the inner surface of the pores of the compressible material becomes polluted and its direct contact with the impregnating water becomes imperfect. In addition, biocides based on siloxane quaternary ammonium compounds (see document

  US-A-4,615,937) are expensive.

  On the other hand, the techniques following which the biocide is retained in the pores by simple precipitation often lack

  because, in the presence of certain solutions, these

  are redissolvent and the biocide is removed by leaching.

  Finally, known techniques apparently do not allow

  not, by a variation of some of their operational parameters.

  the effectiveness of the biocidal effect of articles so treated when

  in particular by adjusting the rate of release of the incor-

  pore. The present invention overcomes these disadvantages and makes it possible to obtain controlled release of the biocide into the water

  retained by the pores of cellulosic articles.

  Thus, the present invention thus relates to a process for imparting durable biocidal properties to a cellulose cleaning and / or wiping product by incorporating into the pores thereof a biocidal compound, which consists of: partially impregnate the product with a first

  aqueous medium containing, in solution, said biocide and, in dispersing

organic binder; -

  2) then contacting said product with a second aqueous medium containing, in solution, a precipitating and coagulating agent capable of precipitating the biocide on the surface of the

  pores of said product and, in combination, to coagulate the organic binder

lunch;

  3) to pack the sponge.

  By "cleaning products and / or wipers based on

  "cellulose", in the present description both

  cellulosic sponges as cellulosic nonwovens. For the sake of convenience and clarity of the following description, the term "sponge" will be used, it being understood that this term denotes a wipe product and / or cellulose-based cleaner as defined.

above.

  It has been found that the sponges must retain about 0.5% by weight of biocide based on the dry weight of the sponge to achieve sufficient disinfecting power. Consequently, to implement the process of the invention, the sponge in step (1) is impregnated with an aqueous solution of the biocide, the quantity of solution retained, coupled with the biocide concentration of this solution, being such that after precipitation the amount fixed on the sponge corresponds to the range above. For example, a solution containing 5% by weight of the biocide can be used, and to obtain a level of 5% of biocide in a 10 g sponge, it will be impregnated with 10 ml of said solution. If working with a 1% solution of biocide and it is desired to fix 3% of it on the sponge, use 30 ml of solution. In the

  In practice, we first saturate the sponge and then compress it (foular-

  so that only the desired amount remains in the sponge, the remainder being removed by squeezing. Preferably, the degree of impregnation in step 1) of the process is between 5 and 60%

  the maximum liquid absorption capacity of the sponge.

  The amount of binder to be used in the first aqueous medium must be sufficient to slow the release of the biocide. rle is preferably between 0.01 and 5% by weight relative to the dry weight of the sponge. It has been found that, in order to slow down as much as possible the release of the biocide, the binder / biocide weight ratio should preferably be between 0.2 and 0.8. Since the precipitation of the biocide and the coagulation of the binder

  stage 2) are practically quantitative, we will use

  in which the amount of binder relative to that of the biocide is in the range above. Thus, it will be possible to use a solution containing 1% of biocide and 0.5% of binder; by precipitating in a dry sponge of 10 g the solids content of 40 ml (400% padding) of such a solution, we obtain, calculated with respect to the dry weight of the sponge, an amount of

  4% biocide and 2% binder amount.

  Biocides which are suitable for the purposes of the invention are

  quaternary ammonium compounds and polyalkylene salts

  bis-guanide oligomers. Examples of such biocides that may be mentioned include the halides of the following compounds and more particularly their chlorides: benzyl-lauryl-dimethylammonium, cetyl-trimethylammonium, cetyl-dimethyl-ethylammonium, benzyl-tridecyl-hydroxyethylimidazolinium, Lauryl-pyridinium, benzyl-myristamidopropyl dimethylammonium, stearyltrimethylammonium, benzyloctadecyl dimethylammonium, benzyl-tetradecyl dimethylammonium, benzyltridecyl dihydroxyethylammonium, benzyldimethyltridecylammonium and hydrochloride.

  hexamethylene bis-guanide oligomer.

  As binders, acrylic latices, butadiene-styrene, acrylonitrile-butadiene latices and vinyl latices can be used. Such latices are commercially available, such as, for example, the acrylic latices known under the name

  "ACRONAL" and marketed by BASF.

  As precipitating and coagulating agents used in the second step of the process of the invention, it is possible to use the alkaline salts and the ammonium salts of mineral acids or the water-soluble organic acids. The pH of the second aqueous medium used according to the invention must be in a pH zone where there is both precipitation of the biocide and coagulation of the binder without resolubilization of the biocide. In general, this pH must

263596-1

  be acidic, that is to say between 1 and 6 and preferably

between 3 and 4.

  It will be noted that the precipitation of benzyl chloride

  dimethyl tridecylammonium or benzyl tridecyl dihydrate

  droxyethylammonium is carried out at pH even very acidic (pH <1)

  while the precipitation of hexamethylene hydrochloride

  Guanide polymer should be performed at pH> 2.7. In fact, at pH <2.7, the precipitate obtained is resolubilized. It will be easy for one skilled in the art to choose by routine tests the agent

  precipitant and coagulant appropriate for each biocidal agent.

  By way of examples of precipitating and coagulating agents, mention may be made of the following compounds: chloride, sulfate, nitrate

  or ammonium persulfate; thiosulfate, persulfate, pyrophosphate

  phate, perborate or sodium citrate; potassium persulfate,

  maleic acid, etc. Especially

  ammonium sulphate, sodium sulphate or potassium sulphate

  do not promote the resolubilization of the precipitate formed.

  The concentration of precipitating and coagulating agent in the second

  An aqueous medium will advantageously be between 4 and 5% by weight.

  With regard to the final packaging of the sponge, this is a subsequent treatment with a primer or water-retaining agent to prevent the sponge from drying out on storage. Such a water retainer may consist of a concentrated solution of a water-soluble alkaline earth salt, for example magnesium chloride, with which the sponge is impregnated before packaging. The amount of MgCl2 retained by a

  sponge 10 g (dry) can be of the order of 5 g.

  It will be noted that the method of the invention is implemented

at room temperature.

  It is particularly interesting to note that the sponges treated by the process of the invention retain their bacteriostatic properties with respect to the water which they are impregnated for a very long time, practically throughout the life of the sponge. despite intensive use. This effect is due to a very slow release of the biocide and it is possible to control the rate of this release as a function of

biocide / binder weight ratio.

  This results not only in effective disinfection of

  the water retained by the sponge outside its use, but also

  cellulose protection throughout its useful life.

  tion. The sponges treated according to the invention are practically indistinguishable from conventional sponges. Their fluid absorption capacity is not changed, nor are their flexibility and

"to touch".

  The following examples illustrate the invention with the aid of the accompanying drawing, in which:

  - Figure 1 graphically represents the rela-

  guarantee of the biocide as a function of time for sponges treated according to the method of the invention, this for different values of the

binding / biocide ratio.

  - Figure 2 graphically represents the rela-

  guarantee of the biocide as a function of time for sponges treated according to the process of the invention, this at two different pHs of

  water whose sponge is impregnated.

  In these examples, the following products were used: - Sponges: regenerated cellulose, samples of 10 to g cut in a plate of 0.5 - 1 cm thick. - Biocide: benzyl-dimethyl-tridecylammonium chloride in aqueous solution (hereinafter referred to as A biocide). - Binder: ACRONAL 32DT Acrylic Latex BASF 50%

dry matter.

  Dilute solutions of the biocide and the latex (between 0.5 and 5% solids) were used and, for the treatment baths,

  Latex / biocide weight ratios from 0 to 1.66%.

  - Precipitant and coagulant: aqueous ammonium persulfate at 5%.

  - Packaging: magnesium chloride at 213 g / l.

26359 61

  Sponges (10 g dry) were immersed in a first aqueous medium containing 1.66% biocide and 1.1% latex (latex / biocide ratio (R) = 0.66) until saturation. The sponges were then pressed to a padding rate of 300%. The amount of solution retained in the pores was therefore 30 ml and then dipped into a second aqueous medium at 5% wt. NH4) 2S208, pH 1.5. After having compressed again the sponges in which the biocide and the latex were deposited together, they were soaked in an aqueous solution of

  MgCl2, then they were wrung out and dried for 24 hours in air.

  The above various operations were repeated by varying the biocide / binder ratio in the first aqueous medium between 0 and 1.66 and thus obtained a series of treated samples containing the coagulated latex immobilized biocide in said

proportions.

  The release power of the biocide was measured by soaking the samples with 100 ml of water and, after a given time,

  measuring the amount of biocide dissolved in this water by spectro-

  photometry at 260 nm. Every 24 hours, water was renewed in

the sample.

  The results are shown in Figure 1 which graphically represents the percentage of biocide released as a function of time. The different curves each refer to a different latex / biocide ratio (R), namely a ratio between 0 and 1. It can be seen that the lower this ratio, the faster is the release, at least during the first 24 to 48 h. These tests were repeated for R = 0.5, but using different pH values for the release water, respectively 7 and 12.5 (NaOH). The results obtained are reported in FIG. 2 which graphically represents the quantity of biocide (in mg) salted out as a function of time. It can be seen that the release is faster in

alkaline medium.

  The strength of the biocide "A" retained in the sponges against detergent solutions was tested by subjecting samples (5 g) to washing in a washing machine. After washing, the residual biocide was extracted from the sponge with alcohol and water and the extracts were assayed spectrophotometrically. The results below (Table I), expressed again according to the binding / biocide ratio,

  correspond to 5 wash cycles.

TABLE I

  Initial conditions Final conditions latex (mg) biocide (mg) R latex (mg) biocide (mg)

0 120 0 - 64

120 0.33 - 95.7

120 0.66 - 84.6

120 1.00 - 73.5

  We see that it is with R = 0.33 that we obtain the

  better resistance to washing in the washing machine.

  The mechanical action of a washing machine washing on the sponge (compression, friction) better simulates the reality of the release of the biocide than a simple immersioin of the sponge in water. To the controlled release effect of the biocide is added the eradication of the precipitate (biocid, latex, coprecipitation agent) and its mechanical expulsion of the cellulosic substrate. It has been noted that the cohesion of the precipitate and its adhesion to the cellulose varies according to the nature of the biocide, the latex and the coprecipitation agent. By manual squeezing it was observed similarly to the results in the washing machine that the optimum protection of the cellulosic substrate is obtained for a ratio "R" generally between 0.1 and 0.5 for the compounds mentioned. In practical tests, it was found that after intensive household use of one week the treated sponges

  This process did not emit any unpleasant odor.

  By replacing in the above tests biocide A with benzyl-dihydroxyethyl-tridecylammonium chloride (biocide B) or with hexamethylene-bis-guanide hydrochloride oligomer

  (C biocide), similar results are obtained.

  The influence of the operating conditions will be noted below.

of the process of the invention.

  1. Influence of the Persylate Counterion The ammonium, sodium and potassium persulfates were evaluated as precipitating agents for biocides A, B and C. In all cases, precipitation of biocides with however a reservation regarding Biocide C for

  Which resolubilization to pH too acidic was observed.

  2. Influence of pH on precipitation The precipitation of biocides A and B is not affected by pH, even in the case of very acid pH (<1). On the other hand, the precipitation of the biocide C must be carried out at pH> 2.7. Indeed, for values below this pH, the precipitate obtained is resolubilized. It is therefore preferable to use sodium or potassium (pH = 5-6) stimulates to effect the precipitation of the biocide C rather than using persulfate solutions.

  The pH could be less than 3

used (* 5%).

  3. Influence of Concentration on Precipitation Precipitation yields are quantitative as soon as biocide concentrations equal to or greater than 8 g / l are reached. This value seems quite reasonable according to the constraints related to impregnation stages and La

  amount of biocide to incorporate into the sponges. In these circumstances

  tions, the use of persulfate solutions at concentrations

  4-5% seems satisfactory.

  4. Influence of the latex on the precipitation The ACRONAL type latices (BASF) used are aqueous dispersions of acrylic copolymers that can be crosslinked thermally. This coagulation is preferably carried out in an acid medium and / or in the presence of ammonium salts. This is the reason why satisfactory coagulation of this type of latex has been observed by addition of ammonium persulfate having an acidic pH. Ammonium persulfate therefore seems to be an appropriate compound for jointly carrying out a precipitation of the biocide

  and coagulation of the latex at room temperature.

  5. Influence of the Co-Precipitation Agent of the Biocide and the Latex (other than Persulfate) The results of Table II which follow show that the precipitation of the biocides can be obtained by addition of numerous inorganic salts other than persulfate. . As regards the biocides A and B, it will be possible to envisage using these various mineral salts provided that the pH is lowered sufficiently so as to jointly precipitate the latex. In the case of biocide C, it will be necessary to choose precipitating and coagulating agents

  whose aqueous solutions have a pH greater than 2.7.

  From the theoretical point of view, the only plausible explanation for the precipitation of quaternary ammonium salts or polymeric bisguanide salts in the presence of mineral salts

  is the formation of ion pairs, entities formed by the association

  tion of two ions of opposite charge. Generally, this association

  This is due either to electrostatic interactions or to hydrophobic effects. In the latter case, the large organic ions comprising an apolar part and an ionic group combine in pairs of ions in aqueous solution forming cavities such that the structure of the water is disturbed on the

  less possible. This phenomenon is used to perform a separation

  Chromatographic feed of ionized or ionizable substances

(ion pair chromatography).

  In Table II, the degree of precipitation is indicated

  by the following signs: - (no precipitation); + (precipitated

  tation); ++ (instant precipitation).

TABLE II

  Precipitating and coagulating agent Biocide A Biocide B Biocide C

NH4CL + ++ +

(NH4) 2S04 ++

NH NO ++ ++

4 3

(NH4) 2S208 ++ ++ ++

  Na2S208 ++ ++ ++ Na2S203 ++ ++ Na2P20? Na 2 P 2 O ++ + Na 2 O 3 + ++ NaHSO 3 + Na citrate - - + NaCl ++ ++ ++ NaOH - +

K2S208 ++ ++ ++

HCl ++ -

H2S04 + - -

Ac. maleic ++ ++ -

Claims (8)

  A process for imparting durable biocidal properties to cleaning products and / or wipers based on cellulose by incorporating into the pores thereof a biocidal agent, characterized in that it consists in: 1) partially impregnating said product of a first   aqueous medium containing, in solution, said biocide and, in dispersing   organic binder; 2) then contacting said product with a second aqueous medium containing, in solution, a precipitating and coagulating agent capable of precipitating the biocide on the surface of the   pores of said product and, in combination, to coagulate the organic binder lunch;   3) to pack the sponge.   2. Method according to claim 1, characterized in that the packaging consists of incorporating in the sponge an agent water retainer.   3. Method according to one of claims i or 2, carac-   in that the impregnation rate in step 1) corresponds to -60% of the maximum liquid absorption capacity.   4. Method according to any one of claims 1 to   3, characterized in that the biocide is an ammonium compound   quaternary or an alkylene bis-guanide oligomer.   5. Method according to any one of claims 1 to   4, characterized in that the precipitating and coagulating agent is an alkaline or ammonium salt of a mineral acid or a water-soluble organic acid.   6. Process according to any one of claims 1 to   5, characterized in that the binder is an acrylic latex.   7. Process according to any one of claims 1 to   6, characterized in that the amount by weight of binder used relative to the weight of the dry sponge is 0.01 to 5% and that biocide of 0.5 to 10%.   8. Process according to any one of claims 1 to   7, characterized in that the weight ratio binder / biocide is between 0.2 and 0.8.