USE OF PHOSPHORYLATED CELLULOSE IN DETERGENT COMPOSITIONS

Abstract: The invention pertains to the use of a water-soluble phosphorylated cellulose which is obtained by dissolving cellulose in a phosphoric acid-containing solvent to produce a solution 94-100 wt.% which is composed of the constituents cellulose, phosphoric acid and/or its anhydrides, and water, in detergent compositions. The use concerns utilisation both in detergents for textiles and in dishwashing detergents.

Description: Use of phosphorylated cellulose in detergent compositions The invention pertains to the use of a water-soluble phosphorylated cellulose in detergent compositions. The preparation of a water-soluble phosphorylated cellulose is described in US-A-2,759,924 and takes the form of treating cellulose with an esterifying solution of phosphoric acid and P 2 O 5 in an alcohol miscible therewith. The reaction takes place in a heterogeneous system, with care being taken to ensure that the particulate cellulose powder does not dissolve in the reaction mixture. Although it is indicated that the thus obtained products can be used in the textile industry, e.g., as detergent additives, it was found that under certain conditions the known products on being dissolved in water may cause gelling due to a too high degree of cross-linking locally. As a result, the products described in said document seem less suitable for general use in detergent compositions. The invention now provides a water-soluble phosphorylated cellulose for use in detergent compositions which on dissolution in water causes little if any gelling. The invention consists in that the water-soluble phosphorylated cellulose for the known use mentioned in the opening paragraph is obtained by dissolving cellulose in a phosphoric acid-containing solvent to produce a solution 94-100 wt.% of which is composed of the constituents cellulose, phosphoric acid and/or its anhydrides, and water. It should be noted that the preparation of a water-soluble phosphorylated cellulose by dissolving cellulose in a phosphoric acid-containing solvent to produce a solution 94-100 wt.% of which is composed of the constituents cellulose, phosphoric acid and/or its anhydrides, and water is known as such from non-prepublished patent application WO 97 30090. However, there is no question in said document of the potential use of the water- soluble phosphorylated cellulose described therein in detergent compositions. The term phosphoric acid in this application refers to all inorganic acids of phosphorus and their mixtures. Orthophosphoric acid is the acid of pentavalent phosphorus, i.e. H 3 PO 4 . Its anhydrous equivalent, i.e., the anhydride, is phosphorus pentoxide (P 2 O ). In addition to orthophosphoric acid and phosphorus pentoxide there is, depending on the amount of water in the system, a series of acids of pentavalent phosphorus having a water- binding capacity in between those of phosphorus pentoxide and orthophosphoric acid, e.g., polyphospho c acid (HeP^^, PPA). In addition to water, phosphoric acid and/or its anhydrides, and cellulose and/or reaction products of phosphoric acid and cellulose, other substances may be present in the solution when preparing phosphorylated cellulose. The solution can be prepared by mixing constituents classifiable into four groups: cellulose, water, inorganic acids of phosphorus including their anhydrides, and other constituents. The "other constituents" may be substances which benefit the processability of the cellulose solution, solvents other than phosphoric acid, or adjuvants (additives), e.g., to counter cellulose degradation as much as possible, or dyes and the like. Cellulose to which phosphorus is bound is also included among the group of constituents making up 94-100 wt.% of the solution. In the case of cellulose-bound phosphorus, the percentages by weight of cellulose in the solution listed in this patent specification relate to quantities calculated back on the cellulose. This applies in analogous fashion to the quantities of phosphorus mentioned in this specification. US 3,424,545 discloses the use of phosphorylated cotton in an aqueous detergent for home laundering. The phosphorylated cotton was obtained by impregnating "Indianhead" cotton with a solution containing urea and orthophosphoric acid. The resulting phosphorylated cotton, which is insoluble in water, was found to function as an effective water-softening agent when used in a detergent as described above. However, it was not found that using such phosphorylated cotton constitutes any improvement over known water-softening agents. Phosphorylated cellulose obtained by dissolving cellulose in a phosphoric acid-containing solvent to produce a solution 94-100 wt.% of which is composed of the constituents cellulose, phosphoric acid and/or its anhydrides, and water was found to be effective not only as a co-builder, but also as an anti-greying agent or as anti-redeposition agent and dispersant in detergent compositions. The term co-builders refers in particular to the polymers which are added to detergents which mostly contain zeolite as a builder. Co-builders serve to inhibit the formation and growth of a deposit, e.g., CaCO 3 , on laundered material. The degree of deposit formation is determined by ashing the woven fabric. Detergents for textiles commonly used in Western Europe generally contain 20 - 35 wt.% of zeolite. When used according to the present invention such detergents will contain at most 10 wt.% of phosphorylated cellulose, preferably 1-5 wt.%, more particularly, 2-4 wt % Phosphorylated cellulose obtained by the method described above was found to be especially suitable for use in non-aqueous, i.e. dry detergent compositions (in the form of powder or tablets) It was found that in well- known detergent compositions which contain zeolite among others, this phosphorylated cellulose is especially effective as a co-builder, with a greater effectiveness than well-known co-builders containing polycarboxylic acids and sodium salts. Furthermore, it was found that in such detergent compositions the phosphorylated cellulose is also effective as anti-greying agent or anti- redeposition agent. In addition to the aforesaid effects relating to detergent characteristics when using phosphorylated cellulose according to the present invention, this phosphorylated cellulose also possesses the favourable property of said constituent's biodegradability. It was found that the content of cellulose-bound phosphorus and the DP of the cellulose have some effect on the properties of phosphorylated cellulose. The most advantageous results in the case of use in detergents were found for phosphorylated cellulose corresponding to the present invention, which has a content of cellulose-bound phosphorus in the range of 3 to 10 % P, preferably in the range of 4 to 8% P, and a cellulose DP of less than 1000. Preferably, the cellulose DP is in the range of 100 to 750. Phosphorylated cellulose used according to the invention was found to be suitable for use in detergents for textile products as well as in dishwashing detergents. For use in powdered detergents preference is given to phosphorylated cellulose in the powder form. Alternatively, phosphorylated cellulose in the form of granules or short fibres (fibrils and/or fibrids) can be employed to this end. Methods for obtaining phosphorylated cellulose in various forms are described in WO 97 30090. Measuring methods Determination of DP The degree of polymerisation (DP) of the cellulose was determined with the aid of an Ubbelohde type 1 (k=0,01). To this end the cellulose specimens to be measured were dried in vacuo for 16 hours at 50°C after neutralisation, or the amount of water in the copper II ethylene diamine/water mixture was corrected to take into account the water in the cellulose. In this way an 0,3 wt.% of cellulose-containing solution was made using a copper II ethylene diamine/water mixture (1/1). On the resulting solution the viscosity ratio (vise. rat. or η re ι) was determined, and from this the limiting viscosity (η) was determined in accordance with the formula: r . vise, rat - 1 , _ _ [η] = x 100 c + (k x c x (vise, rat.— 1)) wherein c = cellulose concentration of the solution (g/dl) and k = constant = 0,25 From this formula the degree of polymerisation DP was determined as follows: DP = (for[η]<450 ml / g), or 0,42 DP >0 υ ,7'6° = - [^η] (for [η]> 450 ml / g) Determining the DP of (phosphorylated) cellulose in the solution proceeded as described above, after the following treatment: 20 g of the solution were charged to a Waring Blender (1 liter), 400 ml of acetone were added, and the whole was then mixed at the highest setting for 10 minutes. The resulting mixture was transferred to a sieve and washed thoroughly with acetone. Finally, there was neutralisation with a 2%-NaHCO 3 /water solution in acetone to a pH of about 7, followed by afterwashing with acetone. The DP of the resulting products was determined as described above, starting from the preparation of the copper II ethylene diamine/water/cellulose solution. Determination of phosphorus content The content of cellulose-bound phosphorus can be measured as described in WO 96/06208. However, there is also a simpler way of determining the phosphorus content of cellulose products. To this end the cellulose product is tabletted after being dried in vacuo for some 15 hours at 50°C. Using an x-ray fluorescent emission spectrometer (e.g., a Philips PW 1400 with chromium tube, line: Kα, 50 kV, 50 mA, GE crystal, angle: 141.025, counting time: 50 s) the tablet's x-ray fluorescence intensity of phosphorus is then measured. By calibrating the spectrometer using tablets with a known phosphorus content, the measured intensity can be converted in a simple manner known to the skilled person to the phosphorus content of the specimen. Detergent testing So-called standardised detergent tests are employed to determine the effectiveness of additions to detergents. These are performed as follows. A laboratory washing machine, make Linitest, is heated to a temperature of 60°C. A standard hard water solution is prepared by dissolving 1 ,56 g of CaCI 2 » 2H 2 O and 1 ,50 g of Na 2 SO in 2 I of demineralised water. - Concentrated basic washing solutions which contain 1 ,25 g of Na 2 CO 3 , 1 , 15 g of NaHCO 3 , 1 ,80 g of water glass 27/8, 1 ,00 g of LABS acid, 1 ,00 g of Elfapur LT 65 SLN, and 12,00 g of zeolite are prepared by dissolving the constituents in 1 I of demineralised water. The acidity of this washing solution is brought to a value of pH=10. 50 ml of the basic washing solution is heated to 40°C and the amount of material to be tested is dissolved in it. The following standard washcloths are employed per test setting: Table I Code Overall Size in cm^ number comments weight in g EMPA 101 1 7 x 7 2 grey fabric EMPA 211 8 10 x 10 9 white cotton EMPA 213 1 10 x 10 1 white PE/cotton - Into a cup are poured 150 ml of the standard hard water solution. To the contents of the cup are added 10 steel balls each weighing 1 g. To this are added, in succession, the 10 standard washcloths and the 50 ml of basic washing solution containing the constituent to be tested. The cup is sealed and placed in the Linitest washing machine. - The Linitest washing machine is kept in operation for 30 minutes. After the test each cup is emptied, and the standard washcloths are rinsed in a beaker containing 1 I of water. The washcloths are wrung out by hand and spread out on a towel. The EMPA 101 standard washcloths are removed after each washing cycle. In all, the washing step is performed 10x, with use being made of a new EMPA 101 standard washcloth in every washing step. There are 3 washing steps per day. The standard washcloths are dried during the night. - On conclusion of the 10 washing steps the washcloths are dried and ironed. Using a Minolta CR 110 Reflectance meter the reflectance in the Yxy and the C mode is measured. The amount of residual ash is determined by pyrolising 2 g (m 0 ) of the EMPA 211 washcloths in a china crucible for 1 hour at 900°C. On conclusion of the test the weight of the remaining ash is determined The ash content (in %) is calculated via mj/m 0 x 100%. Greying is measured as the difference in reflectance between treated and untreated washcloths. Example 1 In the detergent test described above the effect of adding phosphorylated cellulose to a basic washing solution was determined by measuring the effect on greying and the effect on ash content as compared with known additives to detergents. The following results were measured: Table II Added constituent Added quantity Greying ΔR Ash content (in %) (in %) - - 24 2,4 Sokalan CP 5 ® 1) 300 mg/l 24 0,9 CMC 2) 75 mg/l 6 2,1 Phosphorylated cellulose 3) 300 mg/l 14 0,6 1) : a copolymer based on acrylic acid and maleic anhydride partially neutralised with sodium hydroxide. This copolymer is used in large quantities in detergents. 2) : carboxymethyl cellulose, also used in large quantities in detergents to prevent greying. 3) : Phosphorylated cellulose phosphate obtained by dissolving cellulose in a solvent containing phosphoric acid, in which process a solution is obtained 94-100 wt.% of which is made up of the constituents cellulose, phosphoric acid and/or its anhydrides, and water with a DP = 484 and a content of cellulose-bound phosphorus = 5,3%. These results show that phosphorylated cellulose is effective both in lowering the ash content and in reducing greying. Example 2 The example below shows that the water-soluble cellulose according to the invention can also be employed successfully in a dishwashing detergent formulation. As a typical example of an Automatic Dish Wash Detergent (ADD) the following formulation was used: Table III Constituent invention, wt.% Prior art, wt.% Sodium carbonate 24 24 Sodium disilicate, hydrous 26 26 Sodium citrate, di hydrate 32 32 Sodium perborate, monohydrate 6 6 TAED 2 2 surfactant Plurafac LF 2 2 amylase, Duramyl 60T 0,5 0,5 protease, Savinase 6,0T 0,5 0,5 phosphorylated cellulose (DP = 130 and 7 ~ cellulose-bound P = 5,1 %) Sokolan CP 5 ® , powdered — 7 The detergent test was carried out under the following conditions: dosed amount : 20 g water hardness (°dH) (Ca/Mg = 3/1) : 15 type of dishwasher: Miele G 765 SCi program applied univ. 55°C The following changes were made to the composition of the soiled load according to DIN 44990 (July 1989): strength of the tea 10 g/l drying of the cup 1 hour at 90°C storage of soiled items 16 hours at 60 °C no rinsing formulation was applied. The washed dishes were also assessed in accordance with DIN 44990. The results are presented on a scale of 1 to 5, with the numeral 5 representing a perfect result. The outcome as the average of three assessments is given in the table below: Table IV The dishwashing results in the table above clearly show that phosphorylated cellulose according to the present invention at the very least matches the performance of Sokalan CP5 ® , which is less easily biodegradable.

Claims: Claims 1. Use of a water-soluble phosphorylated cellulose in detergent compositions, characterised in that the phosphorylated cellulose is obtained by dissolving cellulose in a phosphoric acid-containing solvent to produce a solution 94-100 wt.% of which is composed of the constituents cellulose, phosphoric acid and/or its anhydrides, and water. 2. Use according to claim 1 , characterised in that the DP of the phosphorylated cellulose is < 1000 and the content of cellulose-bound phosphorus is in the range of 3 to 10 wt.%. 3. Use according to claim 1 , characterised in that the DP of the phosphorylated cellulose is in the range of 100 to 750 and the content of cellulose-bound phosphorus is in the range of 4 to 8 wt.%. 4. A detergent composition containing zeolite and water-soluble phosphorylated cellulose. 5. A detergent composition according to claim 4, characterised in that the phosphorylated cellulose is obtained by dissolving cellulose in a phosphoric acid-containing solvent to produce a solution 94-100 wt.% of which is composed of the constituents cellulose, phosphoric acid and/or its anhydrides, and water. 6. A detergent composition according to claim 4 or 5, characterised in that the phosphorylated cellulose has a DP of less than 1000 and a content of cellulose-bound phosphorus in the range of 3 to 10 wt.%. 7. A detergent composition according to claim 4 or 5, characterised in that the phosphorylated cellulose has a DP in the range of 100 to 750 and the content of cellulose-bound phosphorus is in the range of 4 to 8 wt.%. 8. Use of the detergent composition according to any one of claims 4-7 in a detergent for textiles or a dishwashing detergent.

Inventors: PLOUMEN JAN JOSEPH HUBERT, PLOUMEN, JAN, JOSEPH, HUBERT
Applicants: AKZO NOBEL NV, PLOUMEN JAN JOSEPH HUBERT, AKZO NOBEL N.V., PLOUMEN, JAN, JOSEPH, HUBERT
Application year: 1998
Main classification: C11D3
IPC codes: C11D3