AU737286B2

AU737286B2 - A composition comprising a fine powder

Info

Publication number: AU737286B2
Application number: AU62224/98A
Authority: AU
Inventors: Brent Swaisland; Richard Tanton
Original assignee: SAITRON Ltd
Current assignee: SAITRON Ltd
Priority date: 1997-02-15
Filing date: 1998-02-13
Publication date: 2001-08-16
Anticipated expiration: 2018-02-13
Also published as: GB2337052B; AU6222498A; EP1007196A1; GB9919043D0; CN1247484A; CN1116101C; WO1998035750A1; HK1026382A1; GB2337052A; GB9703195D0

Description

WO 98/35750 PCT/GB98/00457 -1-

DESCRIPTION

A COMPOSITION COMPRISING A FINE POWDER The present invention relates to a composition comprising a fine powder and more particularly, though not exclusively, to a composition in which the fine powder is a colorant. Such compositions have particular use in the construction industry for colouring building materials, particularly cementitious products, mortar, asphalt and tarmac.

It will, however, be appreciated that the invention disclosed, whilst exemplified with reference to colorants as the fine powders, could be applied to other situations where the handling of a fine power is subject to the problems outlined below with reference to colorants.

GB2291600 discloses a mix comprising a colourant powder and a particulate material, for example, sand, which mix has improved flowability and is less likely to block, for example pneumatic and mechanical conveying lines than a colourant powder per se.

Whilst the mix is a considerable improvement over the use of a colourant powder it is not ideal as the fine powder in the mixture can still cause blockage and can become airborne. Pigment loadings are also restricted.

Airborne powder can give rise to health problems, losses and cause cross contamination thereby affecting the quality of coloured products.

Because of these problems, the industry has tried using liquid -2colourants. These are considerably more expensive than powders and suffer a number of drawbacks including settlement. They are also prone to freeze in winter, are messy if spilt and can't be used with wet aggregates in concrete block pavings.

Granular versions of pigments have also been produced and are typically made by a process involving pre-dispersion followed by spray drying.

This process is very expensive and is suitable only for long runs and large batches of single colours. The granules are often not of a particularly resilient nature and tend to break down easily on handling, conveying and metering.

This has the effect of re-creating the dust and handling problems associated with 'powders'.

It is an aim of the present invention to provide a composition which overcomes one or more of the problems associated with fine powder products of the art.

A composition including a fine powder bound to a particulate material with a coating agent in which the fine powder is releasably bound to the particulate •material with a wetting agent which is liquid at room temperature such that the fine powder can be released in an aqueous environment.

Preferably the coating agent is a liquid, more preferably a wetting-agent and more preferably still a non-drying wetting agent. The coating agent functions by displacing the air from about the particle, maximising the amount of fine powder that can be bound thereto.

Since the preferred coating agents comprise hydrophilic groups the fine Since the preferred coating agents comprise hydrophilic groups the fine WO 98/35750 PCT/GB98/00457 powder can be easily displaced from the particle by the addition of water.

The fine powder will typically have a particle size (diameter) of from O.Ol/A to The fine powder is preferably a colourant and may comprise one or more pigments such as, for example, red iron oxide, yellow iron oxide, black iron oxide, carbon and phthalocyanine blues-greens etc.

The particulate material will typically have a particle size (diameter) of greater than 2 0 A. More preferably it will have a particle size (diameter) ranging from 20A 5001t with a mean particle size (diameter) of about 100ft.

The particulate material is preferably an ingredient of the end product to be produced. Preferred particulate materials for use in a composition for use in the building industry include sand and limestone, although other particulate materials, such as microsphere, which have little or no effect on the properties of the end product can be used. In this regard the end products to be produced for use in the building industry include, for example, paving blocks, roof tiles or bricks, and will typically contain 0.5 to 5% by weight of a colorant.

It is preferred to maximise the amount of fine powder relative to the particulate material to reduce transport costs ie. attain greater than 1:1 by weight loadings of fine powder: particulate. To achieve this aim, the coating agent is added in an amount of 0.1 to 15% by weight based on the weight of the composition.

The coating agent allows the particulate material to be wholly or WO 98/35750 PCT/GB98/00457 -4partially coated by the fine powder, alleviating many of the problems associated with the use of fine powders.

Because of the nature of the colourants used in producing cementicious products and their manufacturing processes it has been found that a coating agent which enables the fine powder to be releasably bound to the particulate material such that the fine powder can be released in an aqueous environment is preferred.

The preferred coating agents are wetting agents, more particularly nondrying wetting agents and more particularly still surfactants. Preferred coating agents are carboxylated surfactants, sorbitan esters, alcohol ethoxylates, alkylphenol ethoxylates and sulphonates.

Of these ethoxylated sorbitan esters with a high degree of ethoxylation i.e. those with an ethylene oxide content of 10-20 have been found to be particularly good.

According to a further aspect of the present invention there is provided a method of preparing a composition of the invention comprising wetting the particulate material with a coating agent and releasably binding the fine powder to the coated particulate material.

The fine powder is coated to the particulate material using a coating agent in an amount of 0.1 to 15% by weight based on the weight of the composition.

Preferably the coating agent is an ethoxylated surfactant.

According to a further aspect of the present invention there is provided WO 98/35750 PCT/GB98/00457 a method of producing a product, for use in the building industry, comprising from 1-5 by weight of a fine powder and one or more other ingredients characterised in that the fine powder is added to the other ingredients as a composition of the invention.

The invention will be further described, by way of example only, with reference to the following methods of manufacture, compositions and test data.

Method of Production The particulate material (sand) was placed in a low intensity mixing chamber, the coating agent (ethoxylated surfactant) added, mixed and the fine powder (colourant) gradually added. The components were subjected to further mixing and then packaged. Mixing was by way of a tumbling action and at a circumferential speed of between 0.2 1.2 metres per second, more preferably at 0.7 m sec Composition 1 by weight Fine Powder red iron oxide natural ion oxide Particulate sand 49 Coating agent Sorbitan ester 1 Composition 2 by weight WO 98/35750 PCT/GB98/00457 -6- Red Iron Oxide Sand Sorbitan Ester Composition 3 by weight Yellow Iron Oxide Sand Sorbitan Ester Composition 4 by weight Phthalocyanine Green Sand Sorbitan Ester 86.9 Composition by weight Chrome Green Sand Sorbitan Ester Composition 6 48 48 4 by weight Red Iron Oxide Sand Alcohol Ethoxylate 17 Composition 7 by weight WO 98/35750 PCT/GB98/00457 Black Iron Oxide Sand Alcohol Ethoxylate Comparative Example 1 11 9 by weight Red Iron Oxide Sand Comparative Example 2 by weight Red Iron Oxide Sand Comparative Example 3 by weight Red Iron Oxide Sand Test Samples of each composition were placed in a clear plastic vial, shaken and the degree of "dusting" determined visually. The samples were characterised on a scale of 1 to 5. 1 was used if the vial wall remained clear on shaking, indicating a lack of dusting (good coating of fine powder (colorant) to particulate (sand)) and 5 was used if a dense layer of fine powder formed on the vial wall on shaking (poor coating of fine powder (colorant) to -8particulate (sand)).

The bulk density was also determined and is given as the amount in Kgs occupied by 1 litre volume.

The results are shown in the table below.

Composition No Dust Factor Bulk Density (Kg/1) 1.4 1.2 1.2 1.3 1.2 1.3 1.4 Comparative 1 Comparative 2 Comparative 3 1.2 1.2 1.2 a. a a a a *a Of course it will be apparent to the man skilled in the art that a single coating agent could be replaced by a number of components so long as the fine powder is releasably bound to the particulate material such that the fine powder can be readily dissolved or dispensed in water.

For the purposes of this specification it will be clearly understood that the word "comprising" means "including but not limited to", and that the words "comprise" and "comprises" have a corresponding meaning.

It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents forms part of the common general knowledge in the art, in Australia or in any other country.

Claims

1. A composition including a fine powder bound to a particulate material with a coating agent in which the fine powder is releasably bound to the particulate material with a wetting agent which is liquid at room temperature such that the fine powder can be released in an aqueous environment.

2. A composition as claimed in claim 1 wherein the particulate material is an ingredient of a cementatious product or (ii) microspheres.

3. A composition as claimed in claim 1 or 2 wherein the wetting agent includes hydrophilic groups.

4. A composition as claimed in any one of the preceding claims wherein the wetting agent is a carboxylated surfactant, a sorbitan ester, an alcohol 20 ethoxylate, an alkyl phenol ethoxylate or a sulphonate. S: 5. A composition as claimed in any one of the preceding claims wherein the wetting agent is an e ethoxylated sorbitan ester.

6. A composition as claimed in claim 5 wherein the ethoxylated sorbitan ester has an ethylene oxide content of

10-20. 7. A composition as claimed in any one of the preceding claims in which the particulate material is partially coated with the fine powder. 8. A composition as claimed in any one of claims 1 to 6 wherein the particulate material is wholly coated with the fine powder. H:\bourke\Keep\Speci\62224-98 SPECI.doc 18/06/01 10 9. A composition as claimed in any one of the preceding claims wherein the fine powder is a colourant. A composition as claimed in claim 9 wherein the colourant comprises one or more pigments of: red iron oxide, yellow iron oxide, black iron oxide, carbon and phthalocyanine blue-green.

11. A composition as claimed in any one of the preceding claims wherein the fine powder has an average diameter of from 0.01g to

12. A composition as claimed in any one of the preceding claims wherein the particulate material has an

13. A composition as claimed in any one of the 15 average diameter greater than S*preceding claims wherein the particulate material has an *average diameter of from 20g to 500g. ooo 14. A composition as claimed in any one of the preceding claims wherein the particulate material has an average diameter of about 100g.

15. A composition as claimed in any one of the preceding claims wherein the ratio (weight:weight) of fine Spowder to particulate material is greater than 1 part fine powder to 1 part particulate material.

16. A composition as claimed in claim 15 wherein the ratio of fine powder to particulate material is at least 2.36:1.

17. A composition as claimed in any one of the preceding claims wherein the coating agent is present in an amount of from 0.1 to 15% by weight based on the total weight of the composition. amount of from 0.1 to 159 by weight based on the total \\melb_files\home$\Caroline\Keep\Speci\P35173 .doc 18/02/00 11

18. A composition as claimed in any one of claims 2 to 17 in which the ingredient of the cementatious product is sand on limestone.

19. A composition as claimed in claim 18 having a bulk density of greater than 1.2. when the particulate material is sand. A composition as claimed in claim 18 having a bulk density of 1.3 or greater when the particulate material is sand.

21. A composition as claimed in claim 18 having a bulk density of between 1.3 and 1.4 when the particulate material is sand.

22. A method of preparing a composition as claimed in any of claims 1 to 21 including wetting the particulate material with the wetting agent and releasably binding the :i 20 fine powder to the coated particulate material.

23. A method as claimed in claim 22 comprising sequentially adding, with mixing, to the particulate material first the wetting agent and then the fine powder.

24. A method as claimed in claim 22 or 23 wherein the mixing step is conducted in a slow speed mixer at a circumferential speed of from 0.2 to 1.2 m sec 30 25. A method of colouring a product for use in the building industry, including adding a composition as claimed in claim 9 to the product in an amount such that the product comprises from 0.5 5% by weight of colourant.

26. A method as claimed in claim 25 wherein the product is a concrete product, mortar, asphalt or tarmac. H:\mbourke\Keep\Speci\62224-98 SPECIdoc 18/06/01 12

27. A method as claimed in claim 26 wherein the concrete product is a paving block, roof tile or brick.

28. A composition substantially as hereinbefore described with reference to any one of the foregoing examples apart from comparative examples.

29. A method of preparing a composition substantially as hereinbefore described with reference to the accompanying drawings. Dated this 19th day of June 2001 SAITRON LIMITED By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia 9* o o *o o°* *gig *ooo• H:\mboUrke\Keep\Speci\62224-98 SPECIdoc 18/06/01