WO1993021292A1

WO1993021292A1 - Free-flowing particulate detergent composition containing nonionic surfactant, and process and apparatus for producing same

Info

Publication number: WO1993021292A1
Application number: PCT/US1993/000020
Authority: WO
Inventors: Benny S. Yam
Original assignee: Church & Dwight Company, Inc.
Priority date: 1992-04-16
Filing date: 1993-02-17
Publication date: 1993-10-28
Also published as: AU3430893A

Abstract

A free-flowing particulate detergent composition containing nonionic surfactants, and methods and apparatus for making such detergent compositions, are disclosed. The free-flowing composition relates to detergent compositions comprising carbonate and bicarbonate builders and from about 2 to 20 percent by total weight nonionic surfactant. The process comprises mixing raw materials, applying nonionic surfactant to the mixture, compacting the mixture, granulating the mixture, and then screening the mixture to produce a free-flowing detergent. The apparatus comprises means for mixing raw materials, means for applying nonionic surfactant to the surface of the mixture, means for compacting, means for granulating, and means for screening to produce free-flowing detergent.

Description

Title: FREE-FLOWING PARTICULATE DETERGENT

COMPOSITION CONTAINING NONIONIC SURFACTANT, AND PROCESS AND APPARATUS FOR PRODUCING SAME

TECHNICAL FIELD The present invention relates to free- flowing particulate detergent compositions containing nonionic surfactants, and methods and apparatus for making such detergent compositions. The free-flowing compositions in particular relate to detergent compositions comprising carbonate and bicarbonate builders and from about 2 to 20 percent by total weight nonionic surfactant. The process comprises mixing raw materials, applying nonionic surfactant to the mixture, compacting the mixture, granulating the mixture, and then screening the mixture to produce a free-flowing detergent- The apparatus comprises means for mixing raw materials, means for applying nonionic surfactant to the surface of the mixture, means for compacting, means for granulating, and means for screening to produce free-flowing detergent.

BACKGROUND OF THE INVENTION It is known in the art of powder detergents to use nonionic surfactants as active detergent ingredients. However, nonionic surfactants generally impart tacky qualities to the powder detergents, thereby inhibiting flowability. For instance, particulate detergent compositions comprising more than 2 percent by weight nonionic surfactant will tend not to flow out of a container freely, but will rather cake and then block the opening of the container. Granular detergents are generally produced by spray drying. Such processes involve slurring detergent components and then spray atomizing in a high temperature air stream. However, such processes are generally not satisfactory for detergents containing nonionic surfactants; nonionic surfactants are volatile so there would be an increase in the probability of fire or explosion.

Attempts to avoid the problems of spray drying have focused on post-dosing wherein nonionic surfactants are added after the spray drying operation. However, post-dosing with nonionic surfactants in amounts sufficient to provide satisfactory wash performance generally results in poor flowing and aesthetically displeasing products. Accordingly, lesser amounts of nonionic surfactant must be used if flowability is desired, resulting in poor detergent performance.

Greene (U.S. Patent No. 4,473,485) attempts to overcome the flowability problems of high nonionic containing detergents with a chemical combination for use in wet agglomeration processes. Greene's approach has several drawbacks. For instance, alkali or alkaline earth metal carbonate raw materials must have a mean particle diameter of 20 microns or less. Also, the process of wet agglomeration is complicated and costly because water must be added to the detergent to dispense a structuring agent, and then the excess water must be removed.

Thus, the compositions, processes and apparatus of the prior art have not proven entirely satisfactory. Free-flowing detergents containing more than 2 percent nonionic surfactant generally must be agglomerated to achieve desired flow properties. Raw materials having small mean diameters must generally be utilized. The processes and apparatus to produce free-flowing detergents generally require difficult processing steps to produce, such as agglomeration and water removal.

SUMMARY OF THE INVENTION A free-flowing detergent composition, and process and apparatus for producing same, have now been developed that overcome the above-noted problems and also have numerous other advantages that will be apparent to those skilled in the art.

Broadly, the process of the present invention for producing free-flowing, nonionic surfactant containing particulate detergent comprises (a) mixing raw materials to produce a raw material mixture; (b) applying to the raw material mixture nonionic surfactant to produce an intermediate mixture, wherein the amount of the nonionic surfactant is in the range of about 2-20% by weight of the total intermediate mixture; (c) compacting the intermediate mixture to produce a compacted mixture; and (d) granulating and screening the compacted mixture to produce free-flowing, nonionic surfactant containing particulate detergent. The raw materials utilized in the process will preferably comprise carbonate and bicarbonate builders, especially a mixture of sodium carbonate and sodium bicarbonate. Such raw materials may further comprise sodium sulfate and sodium silicate. The nonionic surfactant can be applied to the raw material by spraying, and said surfactant will preferably comprise alkoxylated linear alcohol. The intermediate mixture will preferably be compacted with a roll compactor. The compacted mixture can comprise cohesive sheets, pallets, or sticks. Another aspect of the present invention concerns a free-flowing, nonionic surfactant containing particulate detergent which can be produced by the above-referenced process of the present invention. The detergent can comprise (a) carbonate and bicarbonate builders; and (b) nonionic surfactant. The detergent can comprise from about 2 to 20 percent by total weight nonionic surfactant, and the detergent composition can be compacted and granulated so that it has a bulk density of 0.7-1.3 g/cc; a mean particle diameter of about 200-2,000 microns; and a flowability factor (discussed below) of not more than 7. The free-flowing detergent can further comprise sodium sulfate and sodium silicate. The detergent will preferably have a mean bulk density of from about 0.8-1.20 g/cc. In especially preferred embodiments, the detergent will comprise about 1-12 weight percent sodium bicarbonate; about 10-40 weight percent sodium carbonate; about 4-18 weight percent sodium silicate; about 1-12 weight percent polyacrylate polymer blend; about 2-6 weight percent alkoxylated linear alcohol; and about 10-65 weight percent sodium sulfate.

Another aspect of the present invention concerns an apparatus for producing free-flowing, nonionic surfactant containing particulate detergent. The apparatus can comprise (a) means for mixing raw materials to produce a raw material mixture; (b) means for applying nonionic surfactant to the raw material mixture to produce an intermediate mixture; (c) means for compacting the intermediate mixture to produce a compacted mixture; (d) means for granulating the compacted mixture to produce granules; and (e) means for screening the granules; wherein said apparatus is capable of producing a free-flowing detergent powder comprising from 2 to 20 percent by weight nonionic surfactant. The means for applying nonionic surfactant can be a sprayer, and the means for compacting can be a roll press.

BRIEF DESCRIPTION OF THE DRAWING To facilitate further discussion of the invention, the following drawing is provided in which:

FIG. l is a view of an apparatus used to determine the flowability of the present invention. This drawing is for illustrative purposes only and should not be used to unduly limit the scope of the invention.

DETAILED DESCRIPTION OF THE INVENTION In a preferred embodiment, the raw materials are first premixed. Soda ash, bicarbonate salt, sodium sulfate, sodium silicate, polymers and bleach are introduced to a blender and then mixed. Nonionic surfactant is sprayed onto the powder materials in the blender. After the desired amount of nonionic surfactant has been sprayed onto the raw material mixture, the resulting nonionic containing mixture (intermediate mixture) is fed into a compactor to produce cohesive sheet, pallets, or sticks. The cohesive sheets, pallets or sticks are fed to a granulator to produce detergent particles. The particles are fed through a screening system which separates oversized and undersized particles. Oversized and undersized particles are returned to the compactor. Perfume is added to the free-flowing detergent particles. The final detergent flows to a surge bin, and then to packing. Mixing may be performed by any suitable mixing device, such as a rotating drum, ribbon blender or any other vessel with suitable means for mixing. Methods of mixing are well-known to those skilled in the art. Mixing may be performed by either a continuous or batch operation. The mixer may be adapted so that liquid nonionic surfactant can be sprayed onto base particles in the blender. Especially preferred for mixing is a ribbon blender. Generally the nonionic surfactant will be distributed on the raw materials during the mixing operation. Surfactant is preferably applied by spraying, such as by means of an atomizing nozzle of conventional type. Especially preferred for applying nonionic surfactant are air atomizing nozzles by Spraying Systems Co.

Compacting may be performed by applying pressure to the intermediate mixture of raw materials and nonionic surfactant. It may be performed by continuously admitting the intermediate mixture to a zone wherein the intermediate mixture is subjected to pressure between two rolls running oppositely with respect to each other. A preferred means of compacting is by a roll compactor wherein the intermediate mixture is subjected to pressure between two rolls under an adjustable compacting pressure. An especially preferred compactor is the Fitzpatrick Company "CHILSONATER" compactor. The gap between rolls and the amount of intermediate mixture introduced to such a roll compactor can be adjusted to produce cohesive detergent sheets, pallets, or sticks.

Granulating can be performed by any suitable granulating or crushing means. The compacted sheets, pallets, or sticks may be crushed to a desired particle size distribution. Preferably, the compacted sheets, pallets, or sticks are fed through a sieve crusher to force the compacted mixture through a sieve with meshes of a given size determining the particle size of the final product. A preferred means for granulating is a FITZMILL manufactured by the Fitzpatrick Company.

Screening can be performed by any suitable screening device. Crushed material may be screened to separate oversized and undersized particles in conventional oscillating sieves- The oversized and undersized particles may be recycled into the compacter to be re-compacted

The raw materials of the present invention may vary, however the free-flowing detergent will typically comprise, in addition to nonionic surfactant, materials such as carbonate and/or bicarbonate builders, other builder materials, polymer additives, and other ingredients.

The carbonate and bicarbonate builders are preferably sodium salts, but other water soluble alkali metal carbonates and bicarbonates may be employed, at least in part. For instance, potassium carbonate and potassium bicarbonate may be employed. Such may be in anhydrous, hydrated or partially hydrated state. The anhydrous state is preferred. Sodium sesquicarbonate may be used in partial or complete replacements of the carbonate and bicarbonate. For the purposes of this invention, the carbonate and bicarbonate builders may be of any particle size.

Other builder materials may optionally be included in the detergent. For example, sodium and potassium salts of the following may be used: pyrosphosphate, tripolyphosphate, orthophospate , silicate, sesquicarbonate, borate, and aluminosilicate. Organic builders such as the following may be used: sodium and potassium salts of citrate, amino polycarboxylates, nitrilotriacetates, N-(2-hydroxyethyl)- nitrilodiacetates, ethylenediamine tetraacetates, hydroxyethylenedia ine tetraacetates, diethylenetriamino pentaacetates, dihydroxyethyl glycine, phytates, polyphosphonates, oxydisuccinates, oxydiacetates, carboxymethyloxysuccinates, hydrofuran tetracarboxylates, esterlinked carboxylate derivatives of polysaccharides such as the sodium and potassium starch maleates, cellulose phthalates, glycogen succinates, semi-cellulose diglycolates, starch, and oxidized heteropolymeric polysaccharides.

The silicate detergent builder may be an alkali metal silicate, such as sodium silicate having a weight ratio of Si0₂:Na₂O of from about 1:1 to 3.2:1, preferably from about 2:1 to about 2.8:1. A preferred alkali metal silicate is sodium silicate. Such alkali metal silicates may be present in amounts of from about 0 to 30 percent, preferably from about 5 to 25 percent. As with carbonate and bicarbonate builders, the other builder materials may be any particle size.

The nonionic surfactant of this invention may include one or more nonionic surfactant compounds. Suitable nonionic surfactant compounds may fall into several different chemical types. Preferred nonionic surfactants are polyoxyethylene or polyoxypropylene condensates of organic compounds. Examples of preferred nonionic surfactants are:

(a) Polyoxyethylene or polyoxypropylene condensates of aliphatic carboxylic acids, whether linear- or branched-chain and unsaturated or saturated, containing from about 8 to about 18 carbon atoms in the aliphatic chain and incorporating from 5 to about 50 ethylene oxide or propylene oxide units. Suitable carboxylic acids include "coconut" fatty acid (derived from coconut oil) which contains an average of about 12 carbon atoms, "tallow" fatty acids (derived from tallow-class fats) which contains an average of about 18 carbon atoms, palmitic acid, myristic acid, stearic acid and lauric acid;

(b) Polyoxyethylene or polyoxypropylene condensates of aliphatic alcohols, whether linear- or branched-chain and unsaturated or saturated, containing from about 8 to about 24 carbon atoms and incorporating from about 5 to about 50 ethylene oxide or propylene oxide units. Suitable alcohols include the "coconut" fatty alcohol (derived from coconut oil) , "tallow" fatty alcohol (derived from the tallow-class fats) , lauryl alcohol, myristyl alcohol, and oleyl alcohol.

An especially preferred nonionic surfactant is an alkoxylated linear alcohol having the following composition:

RO—(CH₂CHO).(CH₂ - CH₂0) (CH2CHO)z—H

I I

R' R" wherein R is a C₆-C,₀ linear alkyl mixture, R' and R" are methyl, x averages 3, y averages 12 and z averages 16. Such an alkoxylated linear alcohol is sold by BASF Corp. under the trademark "INDUSTROL DW 5", and is described in United States Patent No. 4,464,281, col. 5, lines 55 et seq. Other suitable nonionic surfactants are described in U.S. Patent NOS. 4,169,806 and 3,764,541. The nonionic surfactant may be present in the free-flowing detergent in amounts generally of from about 2 to about 20 percent by weight. A preferred range is from about 3 to about 15 percent by weight.

A polymer additive may optionally be included in the free-flowing detergent. For instance, a number of different polycarboxylic polymers or copolymers may be used. The polycarboxylic additives are generally organic substances having at least three carboxylic groups, and may be selected from the group consisting of ethylene-maleic anhydride copolymer, methyl vinyl ether- aleic anhydride copolymer, citric acid, nitrilotriacetic acid, ethylenediamine tetraacetic acid, carboxymethyloxy succinic acid and salts of said copolymers and acids, and mixtures thereof. Both linear and cross-linked copolymers may be utilized.

A preferred polymer additive is a polyacrylate polymer blend comprising a 75/25 weight percent blend of a sodium polyacrylate having a molecular weight of 4500 and a copolymer of maleic acid with an olefin having a molecular weight of 1500. In an especially preferred embodiment, the sodium polyacrylate is "ACUSOL 445ND", and the copolymer of maleic acid with an olefin is "ACUSOL 460ND". "ACUSOL" is a trademark of Rohm _ Haas Company.

The polymer additive may be present in amounts of about 0 to about 15 percent by weight of final product, preferably from about 2 to about 10 percent by weight. The polymer additive is relatively expensive, so the amount of polymer additive utilized will generally be limited by the cost of the polymer additive.

Other components may optionally be included in the free-flowing detergent. For instance, peroxy-bleach agents along with their activators, suds-controlling agents and suds boosters may be included. Anti-tarnishing agents, dyes, buffers, crystal modifiers, perfumes, anti redeposition agents, anionic surfactants, colorants, and fluoressers may also be included.

The final detergent compound will generally have a bulk density of from about 0.7 to about 1.3 g/cc, preferably from about 0.8 to about 1.20 g/cc. The mean particle diameter of the final detergent will generally be from about 200 to about 2,000 microns, preferably from about 500 to about 1,500 microns.

An especially preferred free-flowing detergent composition is as follows:

Total 100.0 Free-flowing as used in this application is defined as having a flowability factor (explained in the examples below) of not larger than 7, preferably not larger than 5.

The following examples illustrate but do no limit the invention.

EXAMPLES

The flowability of the detergents of this invention was evaluated with an apparatus represented in FIG. 1. The following method was utilized to determine flowability:

First a proper disc 2 was installed in the apparatus. One disc was generally suitable for free- flowing materials and the other disc was generally suitable for samples having poorer flow quality.

The prepared samples were poured into the filling funnel 4 so that the funnel was filled to about h inch from the top around the edge 6. The brass disc 2 was rotated to an opening slightly smaller than the sample is expected to pass through, then the hole was closed with the shutter.

The filling funnel door 12 was released and the sample was allowed to flow into the receiving hopper. When necessary, the sample was prodded with a spatula to cause the sample to flow from the filling funnel. The apparatus was not tapped during testing.

A dry liter beaker 14 was placed under the hopper 16 to receive the sample. The shutter 18 was released by carefully moving it to the left with a firm steady motion. When the sample did not flow through the opening, the indexing pin 20 was lifted and the brass disc was turned, slowly and gently, to successively larger openings until the product passed through. The result thus achieved was a first approximation and served only as an approximate indication of flowability.

Next, all of the sample was removed from the receiving hopper 16, the door 12 of the filling funnel was closed, and the samples were poured into the funnel as before. With the shutter 18 closed and the same hole in the brass disc exposed that had earlier permitted the sample to first flow, the receiving hopper was filled as before. The shutter 18 was carefully and gently released. When the sample flowed through this hole, the above-referenced process was repeated using the next smaller hole, and so on until the sample did not flow. The smallest hole, that permitted the sample to flow, in terms of its designated number, corresponded to the flowability factor of the material.

The following table shows the flowability factor corresponding to the different size openings.

COMPARATIVE EXAMPLES 1-5 Four batches of the detergent composition of the present invention were prepared according to the formulations set forth below in Table 1:

Total 100.0 100.0 100.0 100.0

Half of each batch was compacted, and the other half was not compacted. The bulk density of the compacted batches ranged from 0.9 - l.l g/cc, and the bulk density of the non-compacted batches ranged from 0.6 - 0.9 g/cc.

The flowability factor of the compacted and the non-compacted formulation was measured by the method and apparatus described above. The results are presented below in Table 2: Product

1 2 3 4

*Non compacted **Compacted

As can be seen by the above table, the compacted detergents exhibit surprisingly superior flowability.

COMPARATIVE EXAMPLES 5-9 Five batches of raw materials were prepared according to the formulations presented below in Table 3:

Half of each batch was compacted, and the other half was not compacted. The flowability factor of the compacted and the non-compacted formulation was measured by the method and apparatus described above. The results are presented in Table 4 below:

Table 4

Product NC_ C

5 1 2

6 >12 2

7 >12 3

8 >12 3

9 >12 7

*Non-compacted ♦♦Compacted As can be seen by the above table, detergents with varying levels of nonionic surfactant exhibited superior flowability when compacted.

All of the patents and other references identified herein are incorporated by reference in their entireties for all purposes.

The foregoing description and examples Illustrate selected embodiments of the present invention and in- light thereof variations and modifications will be suggested to one skilled in the art, all of which are within the spirit and purview of this invention.

Claims

1. A process for producing free-flowing, nonionic surfactant containing particulate detergent, the process comprising:

(a) mixing raw materials to produce a raw material mixture;

(b) applying to the raw material mixture nonionic surfactant to produce an intermediate mixture, wherein the amount of the nonionic surfactant is in the range of about 2-20% by weight of the total intermediate mixture;

(c) compacting the intermediate mixture to produce a compacted mixture; and

(d) granulating and screening the compacted mixture to produce free-flowing, nonionic surfactant containing particulate detergent.

2. A process as defined in claim 1 wherein the raw materials comprise carbonate and bicarbonate builders.

3. A process as defined in claim 2 wherein the carbonate and bicarbonate builders comprise a mixture of sodium carbonate and sodium bicarbonate.

4. A process as defined in claim 2 wherein said raw materials further comprise sodium sulfate and sodium silicate.

5. A process as defined in claim 1 wherein step

(b) comprises spraying nonionic surfactant onto the raw material mixture.

6. A process as defined in claim 5 wherein the nonionic surfactant comprises alkoxylated linear alcohol.

7. A process as defined in claim 1 wherein step

(c) comprises compacting the intermediate mixture with a roll compactor.

8. A process as defined in claim 7 wherein said compacted mixture comprises cohesive sheets, pallets, or sticks.

9. A process as defined in claim 1 wherein said particulate detergent comprises particles having a mean particle diameter of not less than 200 microns.

10. A process as defined in claim 1 wherein said particulate detergent has a bulk density of from <about 0.7 to about 1.3 g/cc.

11. A process as defined in claim 10 wherein said particulate detergent comprises particles having a mean particle diameter of not less than 200 microns and has a flowability factor of not greater than 7.

12. The free-flowing, nonionic surfactant containing particulate detergent produced by the process defined in claim 1.

13. A free-flowing, nonionic surfactant containing particulate detergent comprising:

(a) carbonate and bicarbonate builders; and

(b) nonionic surfactant; wherein said detergent comprises from about 2 to 20 percent by total weight nonionic surfactant, the detergent composition being compacted and granulated so that it has a bulk density of 0.7-1.3 g/cc; a mean particle diameter of about 200-2,000 microns; and a ^■ flowability factor not more than 7.

14. A free-flowing detergent as defined in claim 13, wherein the mean particle diameter of said detergent is about 500-1,500 microns.

15. A free-flowing detergent as defined in claim 13 further comprising sodium sulfate and sodium silicate.

16. A free-flowing detergent as defined in claim 13 wherein said detergent has a mean bulk density of from about 0.8 to 1.20 g/cc.

17. A free-flowing detergent as defined in claim 13 comprising about 1-12 weight percent sodium bicarbonate; about 10-40 weight percent sodium carbonate; about 4-18 weight percent sodium silicate; about 1-12 weight percent polyacrylate polymer blend; about 2-6 weight percent alkoxylated linear alcohol; and about 10-65 weight percent sodium sulfate.

18. An apparatus for producing free-flowing, nonionic surfactant containing particulate detergent, the apparatus comprising

(a) means for mixing raw materials to produce a raw material mixture;

(b) means for applying nonionic surfactant to the raw material mixture to produce an intermediate mixture;

(c) means for compacting the intermediate . mixture to produce a compacted mixture;

(d) means for granulating the compacted mixture to produce granules; and

(e) means for screening the granules; wherein said apparatus is capable of producing a free-flowing detergent powder comprising from 2 to 20 percent by weight nonionic surfactant.

19. An apparatus as defined in claim 18 wherein said means for applying nonionic surfactant is a sprayer.

20. An apparatus as defined in claim 18 wherein said means for compacting is a roll press.