CN1105170C - Detergent composition comprising clay flocculating polymer with particle size less than 250 microns - Google Patents

Abstract

The invention relates to a granular detergent composition comprising (i) a softening clay and (ii) a clay flocculating polymer, and to a process for making the composition. The composition is particularly useful in 'softening-through-the-wash' products. The clay flocculating polymer is sieved or ground such that at least 95 % by weight of the clay flocculating polymer has a particle size of less than 250 micrometers, and preferably less than 150 micrometers, before adding it to the granular detergent composition.

Description

Detergent composition comprising clay flocculating polymer with particle size less than 250 microns

The present invention relates to granular detergent compositions comprising (i) a softening clay and (ii) a clay flocculating polymer, and to a process for preparing the compositions. The composition is especially suitable for "soft in the wash" products.

Clay flocculating polymers such as high molecular weight polyethylene oxide are commercially available as 100% active powders.

EP-A-0299575, published January 18, 1989, discloses granular detergent compositions comprising softening clay and a polymeric clay flocculating polymer. It illustrates that the polymeric clay flocculants can be added in various ways during the preparation of granular detergent compositions. It can be added to the crutcher mix prior to spray drying; or sprayed onto the granular detergent as a solution in water or an organic solvent; or dry mixed with the granular detergent in the form of granules. The application does not mention the preferred particle size of the clay flocculating polymer.

However, when the polymeric clay flocculating polymers were dry blended with granular detergents, undesired uneven clay deposits or residues were observed. Uneven deposition refers to visible clumps of clay deposited on the surface of the fabric. This is caused by the rapid flocculation of the clay particles before the clay is dispersed. This results in the formation of clay clumps that are deposited on the surface of the fabric. The carryover is caused by the high local concentration of clay flocculating polymers present in the formulation forming gels on contact with water, which leads to poor product dispersibility and increases the risk of product deposits on fabrics.

In addition, clay flocculating polymers can create handling and explosion problems when handled in granular form.

Summary of the invention

According to the present invention, the clay flocculating polymer is avoided by screening or grinding the clay flocculating polymer such that at least 95% by weight of the clay flocculating polymer has a particle size of less than 250 microns, preferably less than 150 microns, before being added to the granular detergent composition. Undesirable uneven clay deposits and residues.

The clay flocculating polymer is preferably polyethylene oxide having an average molecular weight of 100,000 to 10,000,000, more preferably 150,000 to 800,000.

In another aspect of the present invention, there is provided a process for preparing a granular detergent composition comprising combining a clay flocculating polymer with a compound selected from the group consisting of aluminosilicates, silicates, carbonates, citrates, phosphates or their The powder premixing of the mixture, and the subsequent step of mixing the premix with other detergent ingredients.

The premix preferably consists of clay flocculating polymer and aluminosilicate in a ratio of 1:20 to 20:1. DETAILED DESCRIPTION OF THE INVENTION Soft clay

Soft clays can be unmodified or organically modified. Non-organomodified clays can be described as expandable three-layer clays, ie, aluminosilicates and magnesium silicates, having an ion exchange capacity of at least 50 meq/100 g clay, preferably at least 60 meq/100 g clay. Starting clays for organomodified clays can be described similarly. The term "swellable" as used to describe clay relates to the ability of layered clay structures to swell or swell when in contact with water. The three-layer expandable clay used in the present invention is a material geologically classified as smectite. There are two different types of smectite-type clays, broadly distinguishable by the number of octahedral metal-oxygen arrangements in the central layer for a given number of silicon-oxygen atoms in the outer layer. A more complete description of clay minerals is given in "Clay Colloid Chemistry", H. van Olphen, John Wiley & Sons (Interscience Publishers), New York, 1963, Chapter 6, especially pages 66-69.

Smectite (or montmorillonite) clay series include the following three octahedral minerals: talc; hectorite; talcum powder; sauconite; vermiculite; and the following dioctahedral minerals: prophyllite; montmorillonite; chromolite; and nontronite.

The clays used in these compositions contain cationic counterions such as protons, sodium ions, potassium ions, calcium ions and lithium ions. Clays are often distinguished by one predominantly or exclusively adsorbed cation. Sodium clays, for example, are clays in which the adsorbed cation is predominantly sodium. The adsorbed cations can undergo exchange reactions with cations present in the aqueous solution. A typical exchange reaction with a smectite-type clay is represented by the following equation:

Since an equal weight of ammonium ions replaces an equal weight of sodium in the preceding equilibrium reaction, one usually measures cation exchange capacity (sometimes called "base exchange capacity") in milliequivalents per 100 grams of clay (meq/100 g). The cation exchange capacity of clays can be determined in several ways, including electrophoresis, exchange with ammonium followed by titration, or by the methylene blue method, all of which are described in Grimshaw "The Chemistry and Physics of Clays", pp. 264-265, Interscience (19 -1) is fully described. The cation exchange capacity of a clay material is related to factors such as the swellable nature of the clay, the charge of the clay (which in turn is determined at least in part by the lattice structure), and the like. For certain smectite clays, the ion exchange capacity of the clay can vary widely from about 2 meq/100 g kaolin to about 150 meq/100 g, and more.

Preferred smectite-type clays are sodium montmorillonite, potassium montmorillonite, sodium hectorite and potassium hectorite. The clays used in the present invention have a particle size of up to about 1 micron.

Any clay used in the present invention may be naturally or synthetically derived. clay flocculation polymer

Most clay flocculating polymers are relatively long chain polymers derived from monomers such as ethylene oxide, acrylamide, acrylic acid, dimethylaminoethyl methacrylate, vinyl alcohol, vinylpyrrolidone, and ethyleneimine and copolymers. Gums, such as guar gum, are also suitable.

Preferred are polymers of ethylene oxide, acrylamide or acrylic acid. These polymers significantly improve the deposition of fabric softening clays if their molecular weight is in the range of 100 000 to 10 000 000. Preferred are polymers having a weight average molecular weight of 150,000 to 5,000,000.

The most preferred polymer is poly(ethylene oxide). Molecular weight distributions are readily determined using gel permeation chromatography against narrow molecular weight distribution poly(ethylene oxide) standards. method

The particle size of the polymer is reduced by standard milling operations or by physical sieving of the particles. The raw material is then optionally mixed with a powder such as fine aluminosilicate (zeolite A) in a mixer before being added to the finishing process. The zeolite acts as a carrier for the polymer, facilitating its dispersion in the preparation of the finished product.

Many types of particle size modification equipment can be used to reduce the average particle size of the clay flocculating polymer to below 250 microns. Continuous screens such as Russel Finex and Mogenson vibrating screens or continuous scraping screens. Batch sieving operation including the RoTap variant is also available for small quantities. For larger scale operations, continuous air jet mills are available which simultaneously reduce size and classify material.

In a particular embodiment of the invention, the polymer particles may be micronized to further reduce the average particle size. other detergent ingredients

The particulate components of the present invention are typically incorporated into final detergent products, especially those comprising softening clays. Other conventional detergent ingredients such as anionic and cationic surfactants, builders, bleaches, bleach activators, suds suppressors, enzymes (e.g. proteases, amylases, cellulases, lipases), perfumes can generally be used , brighteners, soil release polymers.

Example

In these examples, all percentages are by weight and unless otherwise stated the following abbreviations are used: PEO (as is): Polyethylene oxide polymer supplied by Union Carbide Corporation as WSRN750 (trade name). Typical particle size distribution:

          2% greater than 710 microns

8% between 710-500 microns

          20% are between 500-250 microns

30% between 250-150 microns

40% less than 150 microns PEO (sieving): Material as above, but with a size reduction process to remove 95% of material greater than 150 microns. Typical particle size distribution:

At least 100% smaller than 300 microns

At least 95% less than 150 microns

At least 50% smaller than 106 micron Zeolite A: supplied by Industrial Zeolite Ltd., Thurrock, England. Typical average particle size: 2-10 microns. Light soda ash A: Light density sodium carbonate, typically 97% pure carbonate with an average particle size of about 100 microns and an average aerated density of 550 g/l.

Example 1

The PEO samples (as is) were converted to PEO (sieved) by the RoTap batch sieving method on a 150 micron sieve. The resulting polymer was mixed in a small food processor in the ratio: 1 part PEO (sifted) to 2 parts Zeolite A until homogeneous.

The PEO/Zeolite A premix was mixed with the granular component of the "soft in wash" detergent composition shown below in a batch rotary mixer. Then spray the liquid component on top. The final composition has outstanding clay deposition and softening properties.

Example 1 (percentage by weight

PEO/zeolite A premix 0.5

soft clay 18

Anionic surfactant agglomerates 26

Cationic Surfactant Agglomerates 6

Non-ionic surfactants 3

Sodium percarbonate 13

Phyllosilicate/citric acid 12

Zeolite 4

Bleach Activator Granules 4

Foam suppressor 3.5

Sodium Carbonate, Enzymes, Fragrance, Stain Release Polymers,

Whitening agent and other minor components The balance is up to 100

Example 2

Example 1 was repeated except that the size reduction step was accomplished by passing the PEO (as received) through a continuous Russel Finex oscillating sieving system fitted with a 150 micron sieve.

Example 3

Example 1 was repeated except that the size reduction step included grinding the PEO (as is) in a small batch coffee grinder, then completing the RoTap batch sieving. This avoids any PEO (as is) loss.

Example 4

Example 1 was repeated except that the size reduction step was performed by passing the PEO (as is) through a standard non-oscillating screen equipped with a 150 micron screen and fitted with rotating brushes to improve screening efficiency.

Example 5

Example 1 was repeated except that the size reduction step was performed by passing the PEO (as is) through standard air jet milling such that only particles smaller than 150 microns were entrained in the air stream, removed and collected. This approach avoids the loss of PEO (as is) and is useful for large volume requirements.

Example 6

Repeat Example 4, but mix the PEO (screened) with Zeolite A in a batch verto mixer or similar device that incorporates a concentric mixer with a screw rotating around its own axis which simultaneously surrounds the mixing room operation.

Example 7

Example 6 was repeated except that the resulting premix contained PEO (sieved) to Zeolite A in a 1:1 part ratio.

Example 8

Example 6 was repeated except that the resulting premix contained PEO (sieved) to Zeolite A in a ratio of 1:10 parts.

Example 9

Example 8 was repeated except that the resulting premix contained PEO (screened) to fine light soda ash in a ratio of 1:10 parts.

Example 10

Example 6 was repeated except that the premix was added directly to the continuous detergent preparation process before any liquid was sprayed.

Example 11

Example 6 was repeated, except that the premix was dusted onto the surface of the detergent prepared by the continuous preparation process after spraying any liquid.

Claims (6)

1. A particulate detergent composition comprising (i) a softening clay and (ii) a clay flocculating polymer, characterised in that at least 95% by weight of the clay flocculating polymer has a particle size of less than 250 microns.

2. A granular detergent composition according to claim 1 in which at least 95% by weight of the clay flocculating polymer has a particle size of less than 150 microns.

3. A granular detergent composition according to claim 1 or 2 wherein the clay flocculating polymer is a polyethylene oxide having an average molecular weight of from 100,000 to 10,00O, 000.

4. A granular detergent composition according to claim 3 in which the clay flocculating polymer is a polyethylene oxide having an average molecular weight of from 150,000 to 800,000.

5. A process for making a granular detergent composition according to any of claims 1 to 4 further comprising a powder selected from aluminosilicate, silicate, carbonate, citrate, phosphate or mixtures thereof, the process comprising the steps of pre-mixing the clay flocculating polymer with the powder to form a pre-mix, and subsequently mixing the pre-mix with other detergent ingredients.

6. A process according to claim 5 in which the premix consists of the clay flocculating polymer and aluminosilicate in a ratio of from 1: 20 to 20: 1.