EP0854908B1 - Descaling and cleaning compositions containing cellulose microfibrils - Google Patents

Abstract

PCT No. PCT/FR96/01206 Sec. 371 Date Apr. 2, 1998 Sec. 102(e) Date Apr. 2, 1998 PCT Filed Jul. 31, 1996 PCT Pub. No. WO97/12954 PCT Pub. Date Apr. 10, 1997The invention relates to a descaling formulation comprising cellulose microfibrils, in which at least 80% of the cells have primary walls and not more than 20% of the cells have secondary walls, with a degree of crystallinity of not more than 50%. The pH of the formulation is less than or equal to 1 and more particularly less than or equal to 0.5.

Description

The present invention relates to descaling and cleaning formulations with base of cellulose microfibrils.

The detergent formulations used for descaling have very specific characteristics. Thus, the products used in its composition must be able to remain stable and maintain their properties at very acidic pH, the most of the time less than 2 and very often less than 1. Furthermore, it is very desirable that the rheology of the formulations be of the pseudo-plastic type. Indeed, these formulations, for optimal use, must have a low viscosity when they are subjected to a significant shear as it is the case during the application of the product, then a high viscosity when the shear stresses are weak, so as to allow a slow flow along the walls to be descaled.

Current formulations are based on a mixture of surfactants representing up to 10% by weight of the formulation. However, this type of formulation is not totally satisfactory in the sense that the rheological behavior is not pseudo-plastic but Newtonian. In addition, such formulations are relatively expensive because the amount of surfactant is very important.

Classic thickeners such as polysaccharides have been tested in media whose pH is lower than 1 but without great result. Indeed, the stability of these produced in such environments is not very good and degrades the lower the pH.

The object of the present invention is to propose a descaling formulation presenting a pseudo-plastic rheological profile, stable over time.

Thus, the subject of the invention is a descaling formulation comprising cellulose microfibrils, of which at least 80%, preferably at least 85% of the cells are with primary walls and at most 20%, preferably at most 15% of the cells are secondary walls, having a degree of crystallinity of at most 50%, preferably at least plus 40%.

But other characteristics and advantages of the present invention will appear more clearly on reading the description and the examples which follow.

Thus, it has been found that the above-mentioned microfibrils give the formulation a pseudo-plastic rheology, moreover and that these microfibrils, surprisingly, remained stable and retained their properties in very acidic media, i.e. with a pH between 0 and 1.

The microfibrils used in the composition of the formulations according to the invention therefore consist of cellulose.

Cellulose represents the essential element of the walls of plant cells. The latter consist of primary walls (parenchyma cells) and secondary walls, in different proportions depending on the nature of the plant from which they come. The primary walls mainly comprise certain pectins and proteins and little cellulose, generally around 5%, and depend on the development of the cell. The fibrils of the secondary walls constitute networks forming lamellae in which there is a layer S ₁ (thickness of 0.2 to 0.35 μm) comprising very entangled and spiraled microfibrils, a layer S ₂ (thickness of 1.8 to 3.8 µm) essentially based on cellulose in a very compact, oriented form, with slightly tangled microfibrils forming concentric lamellae, and finally a layer S ₃ (thickness of 0.1 to 0.15 µm) based on cellulose fibers entangled and spiraled.

The microfibrils used as an additive in the formulations according to the invention have at least 80%, preferably at least 85% of cells with primary walls and at most 20%, preferably at most 15% of cells with secondary walls.

In addition the cellulose microfibrils have an average diameter included between 20 and 40 Å, preferably between 30 and 40 Å.

As previously indicated, the crystallinity of the microfibrils is at most 50%, preferably at most 40%. In particular, the rate of crystallinity is between 20 and 38%.

The length of these microfibrils is of the order of 10 μm, and less. We can more particularly, use microfibrils with a length less than or equal to 2 μm.

More particularly, the cellulose microfibrils are obtained from the beet, bran from cereals or any other vegetable.

The cellulose microfibrils have a high purity of the order of 90%. The remaining 10% consists in particular of residual compounds such as water, pectins, such as galacturonic acid, rhamnose or ferulic acid, hemicelluloses, such as arabinose, galactose, mannose, xylose as well as mineral salts.

(a) première extraction acide ou basique, à l'issue de laquelle on récupère un premier résidu solide,

(b) éventuellement seconde extraction effectuée dans des conditions alcalines du premier résidu solide, à la suite de quoi, est récupéré un second résidu solide,

(c) lavage du premier ou du second résidu solide,

(d) éventuellement blanchiment du résidu lavé,

(e) dilution du troisième résidu solide obtenu à l'issue de l'étape (d) de manière à obtenir un taux de matières sèches compris entre 2 et 10 % en poids,

(f) homogénéisation de la suspension diluée.

These microfibrils can be obtained by extraction by conventional means. Preferably, they can be obtained according to a process described below, implementing a treatment carried out on the pulp of plants with primary walls, such as for example beet pulp after it has undergone a stage d prior extraction of sucrose, according to methods known in the art. Said method comprises the following steps:

(a) first acid or basic extraction, after which a first solid residue is recovered,

(b) possibly a second extraction carried out under alkaline conditions of the first solid residue, after which a second solid residue is recovered,

(c) washing the first or second solid residue,

(d) optionally bleaching the washed residue,

(e) dilution of the third solid residue obtained at the end of step (d) so as to obtain a dry matter content of between 2 and 10% by weight,

(f) homogenization of the diluted suspension.

In step (a), the term "pulp" means moist, dehydrated pulp, preserved by silage or partially defected.

The extraction step (a) can be carried out in an acid medium or in a basic medium.

For acid extraction, the pulp is suspended in a solution of water for a few minutes so as to homogenize the acidified suspension to a pH between 1 and 3, preferably between 1.5 and 2.5.

This operation is carried out with a concentrated solution of an acid such than hydrochloric acid or sulfuric acid.

This step can be advantageous to remove the calcium oxalate crystals which may be present in the pulp, and which, due to their abrasive nature important, can cause difficulties in the homogenization step.

For basic extraction, the pulp is added to an alkaline solution of base, for example soda or potash, with a concentration of less than 9% weight, more particularly less than 6% by weight. Preferably, the concentration of the base is between 1 and 2% by weight.

A small amount of a water-soluble antioxidant may be added, such as sodium sulfite Na ₂ SO ₃ , in order to limit the cellulose oxidation reactions.

Stage (a) is generally carried out at a temperature of between approximately 60 ° C and 100 ° C, preferably between about 70 ° C and 95 ° C.

The duration of step (a) is between approximately 1 hour and approximately 4 hours.

During step (a), partial hydrolysis takes place with release and solubilization of most pectins and hemicelluloses, while preserving the molecular weight of cellulose.

The solid residue is recovered from the suspension from step (a) in using known methods. So it is possible to separate the residue solid by centrifugation, by vacuum or pressure filtration, with fabrics filters, or filter presses for example, or by evaporation.

The first solid residue obtained is optionally subjected to a second step extraction, carried out under alkaline conditions.

A second extraction step is implemented when the first has been driving under acidic conditions. If the first extraction was carried out in alkaline conditions, the second step is only optional.

According to the method, this second extraction is carried out with a base of preference chosen from soda and potash, the concentration of which is less than about 9% by weight, preferably between about 1% and about 6% by weight.

The duration of the alkaline extraction step is between approximately 1 and approximately 4 hours. It is preferably equal to approximately 2 hours.

At the end of this second extraction, if it takes place, a second residue is recovered solid.

In step (c) the residue from step (a) or (b) is washed thoroughly with water to recover the residue of cellulosic material.

The cellulosic material of step (c) is then optionally bleached, in step (d), according to conventional methods. For example, we can perform a treatment with sodium chlorite, sodium hypochlorite, hydrogen peroxide at a rate of 5-20% compared to the quantity of dry matter treated.

Different concentrations of bleach can be used, at temperatures between about 18 ° C and 80 ° C, preferably between about 50 ° C and 70 ° C.

The duration of this stage (c) is between approximately 1 hour and approximately 4 hours, preferably between about 1 and about 2 hours.

A cellulosic material is then obtained containing between 85 and 95% by weight of cellulose.

At the end of this bleaching step, it may be preferable to wash abundantly cellulose with water.

The resulting suspension, possibly bleached, is then rediluted in water at a rate of 2 to 10% dry matter.

The homogenization stage corresponds to mixing, grinding or any operation high mechanical shear, followed by one or more passes of the suspension cells through a small diameter orifice, subjecting the suspension to a drop of pressure of at least 20 MPa and a high speed shearing action followed by a deceleration impact at high speed.

Mixing or grinding is, for example, carried out by passage (s) in the mixer or grinder for a period ranging from a few minutes to about an hour, in a type device such as a WARING BLENDOR equipped with a four-blade propeller or wheel mill or any other type of mill, such as a colloid mill.

The actual homogenization will advantageously be carried out in a homogenizer of the MANTON GAULIN type in which the suspension is subjected to a shear action at high speed and pressure in a narrow passage and against a shock ring. We can also cite the MICRO FLUIDIZER which is a homogenizer mainly consisting of a compressed air motor which will create very strong pressures, an interaction chamber in which the operation will take place homogenization (elongational shear, shock and cavitation) and a chamber low pressure which allows the depressurization of the dispersion.

The suspension is preferably introduced into the homogenizer after preheating at a temperature between 40 and 120 ° C, preferably between between 85 and 95 ° C.

The temperature of the homogenization operation is maintained between 95 and 120 ° C, preferably greater than 100 ° C.

The suspension is subjected in the homogenizer to pressures included between 20 and 100 MPa, and preferably greater than 50 MPa.

The homogenization of the cellulosic suspension is obtained by a number of passages can vary between 1 and 20, preferably between 2 and 5, until obtaining of a stable suspension.

The homogenization operation can advantageously be followed by an operation high mechanical shear, for example in a device such as the ULTRA TURRAX from SYLVERSON.

It should be noted that this process has been described in European patent application EP-A-0 726 356, reference may therefore be made to it if necessary.

The amount of microfibrils used in the composition of the formulation according to the invention is between 0.05 and 1.5% by weight. Preferably, this amount is between 0.1 and 1% by weight.

Here and for the rest of the description, unless otherwise specified, the percentages by weight are expressed by weight of material (for example the microfibrils) relative to the total weight of the formulation.

The formulation according to the invention also comprises an acidic compound. This the latter can be organic or mineral.

All organic acids are suitable as long as their pKa is lower or equal to 6. More particularly, mention may be made of mono- or polycarboxylic acids aliphatics comprising 1 to 12 carbon atoms.

As an example of acids of this type, mention may be made of formic acids, acetic, maleic, citric, sulfamic, oxalic, adipic, succinic, glutaric.

It should be noted that it would not be departing from the scope of the present invention to use one or more of the acids mentioned. So, for example, mixtures of acids citric and formic, suitable for carrying out the invention, as well as the mixture called "AGS", a by-product of the Nylon manufacturing line and including acids adipic, glutaric and succinic, in the following proportions: 15 to 30% acid succinic, 50 to 75% glutaric acid and 5 to 25% adipic acid.

All the mineral acids conventionally used in detergency are suitable. AT by way of example and without intending to be limited thereto, hydrochloric acid, acid phosphoric, or mixtures thereof.

Of course, it is possible to use a mixture of acids belonging to the two categories, if these are compatible.

The amount of acid used in the composition of the formulation is such that the pH of the final formulation is less than or equal to 2, more particularly less than 1.5.

According to a preferred embodiment of the invention, the amount of acid used is such that the pH of the formulation is less than or equal to 1, and more particularly less than or equal to 0.5.

The skilled person, given what has just been written, is able to adapt the quantity of acid to be used, according to the characteristics of the acid or acids envisaged. However, as an indication, the acid content in the formulation is between 1 and 20% by weight. More particularly it is between 3 and 15% by weight.

The formulation according to the invention also comprises at least one surfactant detergent. In general, this compound is chosen from nonionic surfactants, cationic or amphoteric.

All surfactants are suitable as long as they are stable in media with a pH below 2.

By way of example of a nonionic surfactant, mention may be made of polyoxyalkylenated alkylphenols, the alkyl substituent of which is C ₆ -C ₁₂ and containing from 5 to 25 oxyalkylene units (oxyethylene, oxypropylene, oxybutylene), polyoxyalkylenated alkylarylphenols of which the alkyl substituent is C ₁ -C ₆ and comprising 5 to 25 oxyalkylene units (oxyethylene, oxypropylene), aliphatic C ₈ -C ₂₂ polyoxyalkylene alcohols containing from 1 to 25 oxyalkylene units (oxyethylene, oxypropylene) the condensation of ethylene oxide or propylene oxide, with propylene glycol, ethylene glycol and / or glycerol.

Still as nonionic surfactants, there may be mentioned glucosamides, glucamides, glycerolamides, the products resulting from the condensation of ethylene oxide or propylene oxide, with ethylenediamine, the oxides of amines such as C ₁₀ -C ₁₈ alkyl oxides dimethylamines, C ₈ -C ₂₂ alkoxy oxides ethyl dihydroxy ethylamines, alkylpolyglycosides described in US-A-4,565,647, C ₈ fatty acid amides -C ₂₀ , ethoxylated fatty amides, ethoxylated amines.

According to a particular embodiment of the invention, preferably using polyoxyalkylenated aliphatic alcohols as well as polyoxyalkylenated alkylphenols, these surfactants being used alone or as a mixture.

Among the alkylphenols, use is more particularly made of compounds having 1 or 2 alkyl groups, linear or branched, having 4 to 12 carbon atoms, in particular octyl, nonyl or dodecyl.

Ethoxylated alkylphenols (EO units) or ethoxy-propoxylated (EO units + OP) have generally 1 or 2 alkyl groups, linear or branched, having 4 to 12 atoms of carbon, in particular octyl, nonyl or dodecyl.

As examples of surfactants of this type, mention may be made most particularly of ethoxylated nonylphenol with 6 OE units, ethoxylated nonylphenol with 9 OE units, ethoxylated nonylphenol with 10 OE units, ethoxylated nonylphenol with 12 OE units, ethoxy-propoxylated nonylphenols with 25 OE + OP units, ethoxy-propoxylated nonylphenols with 30 OE + OP units, ethoxy-propoxylated nonylphenols with 40 units OE + OP.

As cationic surfactants capable of entering into the formulation according to the invention, the quaternary ammoniums are suitable for carrying out the invention.

More particularly and without intending to be limited, mention may be made of halides alkyltrimethylammonium, dialkyldimethylammonium, alkyldimethyl-benzylammonium, alkyldimethylethyl ammonium, the Quat Esters, benzalkonium chloride as Rhodaquat®.

The surfactants included in the formulation according to the invention can also be chosen from amphoteric surfactants. For example, alkyl betaines, alkyl dimethylbetaines, alkylamidopropylbetaines, alkylamidopropyl-dimethylbetaines, alkyltrimethyl-sulfobetaines, imidazoline derivatives such as alkyl amphoacetates, alkylamphodiacetates, alkylamphopropionates, alkylampho dipropionates, alkylsultaines or alkylamidopropyl-hydroxysultaines, products condensation of fatty acids and protein hydrolysates, these compounds being able be used alone or as a mixture.

Mirapon® Excel, Mirataine® CBS, Mirataine® CB surfactants, the range of Miranol®, Amphionic® SFB, Amphionic® XL may be particularly suitable for the realization of the present invention.

It is clear that it would not be departing from the scope of the present invention to prepare a formulation comprising one or more surfactants chosen from categories identical or different, insofar as they are compatible.

The amount of surfactants is between 0.1 and 5% by weight. Preferably, it is between 0.8 and 3% by weight.

The formulation according to the present invention may further comprise the additives classics of this type of application in particular. Thus, the formulations can contain dyes, perfumes, preservatives.

Usually the additive content is less than 2% by weight, or even 1% by weight. weight. In fact, the content of these compounds depends on the effect to be obtained and this is very often achieved with contents as low as 0.1 to 0.2% by weight.

The complement to 100% by weight of the formulation consists of water.

The process for preparing the formulation according to the invention will now be described.

One can proceed according to conventional methods in the field. So we put in contact with the various constituent elements of the formulation, in an indifferent order, simultaneously or successively, in an apparatus homogenizing the mixture.

However, according to a particular embodiment of the invention, all is dispersed first the cellulose microfibrils in at least a fraction of the water entering the formulation.

This operation is of course carried out with stirring.

It is important to note that the viscosity characteristics of the formulation can be adapted according to the quality of the agitation. So when the commotion is slow, i.e. with a speed of less than 1000rpm, the viscosity of the resulting formulation is lower than the viscosity of a formulation obtained with the same amount of microfibrils, but prepared under intense agitation, for example greater than 5000 rpm. Therefore, more intense agitation will decrease the amount of microfibrils needed to obtain the viscosity level wish.

The devices with which the formulation is prepared are conventional and are in particular devices of the Ultra-Turrax® type, devices with blades deflocculers or mixers.

Once the aqueous dispersion of the cellulose microfibrils is obtained, add the acid or mixture of acids, then the detergent surfactant (s) and finally the additives.

In the event that the final viscosity of the formulation is not sufficient, it is possible to add an additional quantity of microfibrils.

The agitation of the first stage, that of the dispersion of the microfibrils in water may or may not be conserved.

It is indeed possible to carry out the dispersion of the microfibrils under a strong agitation then to decrease this during the introduction of the other elements of the formulation.

The preparation of the formulation is usually carried out at the temperature ambient.

The formulations according to the invention in particular find their application in the descaling of sanitary facilities whether in the household or institutional field (community).

Concrete but nonlimiting examples of the invention will now be presented.

EXAMPLES EXAMPLES 1a and 1b

The purpose of these examples is to show the influence of the implementation on the viscosity of the microfibril suspension.

A suspension is prepared comprising an amount of cellulose microfibrils in an aqueous solution comprising 10% hydrochloric acid, so as to obtain a pH of 0.
These cellulose microfibrils were supplied by GENERALE SUCRIERE; they were prepared according to Example 20 of European patent application EP-A-0 726 356.

Example 1a consists in suspending the microfibrils using a pale deflocculator, with a speed of 1400 rpm.

Example 1b consists in suspending the microfibrils using an Ultra-Turrax, with a speed of 500 rpm.

The viscosity measurement was carried out with a Brookfield device (needle No. 3).

The table below brings together the results obtained: Example Quantity of microfibrils viscosities (mPa.s) 10 rpm 20 rpm 50 rpm 1a 0.42% 900 490 250 1b 0.85% 720 440 210

We see that we can get the same level of viscosity with half as much of microfibrils, increasing the speed and shear of agitation.

EXAMPLE 2

The purpose of this example is to evaluate the viscosity of a suspension of microfibrils with a pH of 2.

The suspension comprises 0.8% microfibrils and was obtained by shaking with a pale deflocculator rotating at 500 rpm.

The viscosities measured with a Brookfield device (needle # 2) are as follows: 0.3 rpm 7200 mPa.s 3 rpm 1000 mPa.s 30 rpm 770 mPa.s

Claims (17)

1. A descaling formulation, characterized in that it comprises cellulose microfibrils comprising at least 80%, preferably at least 85% of cells with primary walls and at most 20%, preferably at most 15%, of cells with secondary walls, and with a degree of crystallinity of less than 50%, preferably less than 40%.
2. A formulation according to the preceding claim, characterized in that the average diameter of the microfibrils is in the range 20 to 40 Å, preferably in the range 30 to 40 Å.
3. A formulation according to any one of the preceding claims, characterized in that the microfibrils originate from primary wall vegetable pulp.
4. A formulation according to the preceding claim, characterized in that the microfibrils originate from sugar beet or cereal bran.
5. A formulation according to any one of the preceding claims, characterized in that the microfibril content of the cellulose is in the range 0.05% to 1.5% by weight, preferably in the range 0.1% to 1%.
6. A formulation according to any one of the preceding claims, characterized in that it comprises at least one organic or mineral compound or a mixture of these two types of acid.
7. A formulation according to the preceding claim, characterized in that the organic acid is selected from aliphatic mono- or poly-carboxylic acids containing 1 to 12 carbon atoms.
8. A formulation according to the preceding claim, characterized in that the organic acid is selected from formic, acetic, maleic, citric, sulphamic, oxalic, adipic, succinic and glutaric acid, these acids being present alone or as a mixture.
9. A formulation according to claim 6, characterized in that the mineral acid is selected from hydrochloric and phosphoric acid or a mixture thereof.
10. A formulation according to any one of claims 6 to 9, characterized in that the quantity of acid is such that the pH is 2 or less, preferably less than 1.5.
11. A formulation according to any one of claims 6 to 10, characterized in that the quantity of acid is such that the pH is 1 or less, preferably is 0.5 or less.
12. A formulation according to any one of the preceding claims 6 to 11, characterized in that the quantity of acid is in the range 1% to 20% by weight, preferably in the range 3% to 15%.
13. A formulation according to any one of the preceding claims, characterized in that it comprises at least one detergent surfactant selected from non ionic, cationic and amphoteric surfactants or mixtures thereof.
14. A formulation according to the preceding claim, characterized in that the surfactant content is in the range 0.1% to 5% by weight, preferably in the range 0.8% to 3%.
15. A formulation according to any one of the preceding claims, characterized in that it comprises additives such as colorants, preservatives, or fragrances.
16. A formulation according to the preceding claim, characterized in that the additive content is less than 2%, preferably less than 1%.
17. A formulation according to any one of the preceding claims, characterized in that it comprises water.