NZ250106A - Granular carrier of a water dispersible substance, the substance held in capillaries in the granules and also mixed with a harder granular substance to enhance mixture strength and flowability - Google Patents

Description

New Zealand Paient Spedficaiion for Paient Number £50106 0 i Priority Date(s) Complete Specification. Fi'.cd: ..

Class: fc,. ?«.<?? 2 2 DEC TO Publication Date: . r. r.

P.O. Journal, No: ...

Patents Form No. 5 NEW ZEALAND patents act 1953 complete specification GRANULAR MATERIAL '""V1993 WE, Christopher John Drysdale an Australian citizen of 3 Inglis Road, Berwick, Victoria 3806, Australian and David George Nichols, an Australian citizen of 20 Browns Road, Devon Meadow, Victoria 3977, Australia hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statements (followed by page la) la GRANULAR MATERIAL TECHNICAL FIELD This invention provides a novel form of granular 5 flowable material which serves as a carrier of a water dispersable substance.

The water dispersable substance in the granular material of the present invention may be a water soluble surfactant in which case the material of the present 10 invention may serve as a soil wetting aid. However the invention also has application to materials for dispersing other water dispersable substances such as pesticides, fungicides, trace elements and plant growth hormones.

There is a present need for an effective soil 15 wetting aid for use in horticulture, both in nurseries and home gardens, turf, recreational areas and also in general agriculture, particularly in dry climates where water may be scarce and expensive. There are known wetting aids in the form of dry flowable granular materials which are 20 loaded with a water soluble surfactant. It is desirable to have a dry mechanically strong granular material which can be readily stored and handled and is flowable so that it can be distributed either throughout soil to be treated or on the surface of the soil so that when water is added to 25 the soil it makes contact with the wetting aid and it dissolves some of the surfactant to improve wettability.

The presently known wetting aid products generally use calcined clay granular material or vermiculite as the carrier for the surfactant. The 30 production of such materials requires considerable consumption of energy. In the case of calcinated clay, heating is requiring in the calcining process (dehydrating) and there is a further energy input in order to dehydrate the absorbed surfactant to reduce the moisture level of the (followed by Page 2) 0 1 0 product to a degree which allows sufficient flowability. In the case of vermiculite, this is an exfoliated mineral which also uses energy for dehydration. The present invention enables the production of a granular wetting aid 5 which can produced with far less consumption of energy and which provides superior wetting and re-wetting properties.

The present invention takes advantage of the highly hydrophilic property of materials which have a microstructure comprising capillary vessels. Some 10 naturally occurring plant materials have highly porous microstruetures that can absorb very many times their own weight in water. One particularly hydrophilic material is coir pith which is a completely homogeneous material composed of millions of capillary vessels that can absorb 15 and hold almost 1000% of their own weight in water. Coir is accordingly able to take us vast quantities of water or other liquid without appearing wet or even damp. However this material is very soft and friable. It does not flow freely and cannot be readily stored. The present invention 20 provides a multi-component mixture which enables production of a granular flowable material with desirable mechanical properties and which provides very effective exposure of a water dispersable substance to any added water.

DISCLOSURE OF THE INVENTION According to the invention there is provided a granular flowable carrier of a water dispersable substance comprising: a first granular component which has a 30 microstructure of capillary vessels and is capable of taking liquid into those capillary vessels so as to be strongly hydrophilic; a water dispersable substance disposed within the capillary vessels of the first granular component so as to 3 250106 be held within the granules of that component; and a second granular component which is harder than the first granular component and is intimately mixed with the first granular component so as to enhance the 5 mechanical strength and flowability of the mixture.

The water dispersable substance may be water soluble. More particularly it may be a water soluble liquid absorbed into the capillary vessels of the first granular component.

Preferably the capillary vessels of the first granular component are not totally filled with said substance so that the first granular material remains strongly hydrophilic such that on contact with water it will absorb water into its capillary vessels to put that 15 water into intimate contact with said water dispersable substance.

The water dispersable substance may comprise a surfactant in which case said material may be a soil wetting aid.

Accordingly the invention specifically provides a soil wetting aid in the form of a granular flowable material and comprising: a first granular component which has a microstructure of capillary vessels and is capable of 25 taking liquid into those capillary vessels so as to be strongly hydrophilic; a liquid surfactant taken into the capillary vessels of the first granular component so as to be held within the granules of that component; 30 a second granular component which is harder than the first granular component and is intimately mixed with the first granular component to enhance the mechanical strength and flowability of the mixture.

The granules of the second granular component may 250106 4 - also be absorbent to the water dispersable substance and may have some of the water dispersable substance absorbed therein.

The first granular material may comprise granules 5 of coir, the average maximum dimension of which is in the range 0.005 mm to 3.0 mm.

The second granular component may comprise granules of zeolite the average maximum dimension of which is in the range 0.02 mm to 3.0 mm.

The water dispersable substance may be a pluronic surfactant. More specifically it may be a liquid pluronic polyol.

The invention also provides a method of producing a granular flowable material carrying a water dispersable 15 substance, comprising mixing a quantity of the water dispersable substance with granules of a first material which has a microstructure of capillary vessels and is capable of taking liquid into those capillary vessels so as to be strongly hydrophilic and granules of a second 20 material which is harder than the first material so as to enhance the mechanical strength and flowability of the resulting mixture.

The water dispersable substance may be mixed with the granules of the second material before addition of the 25 granules of the first material to complete the mixture.

BEST MODE OF CARRYING OUT THE INVENTION A presently preferred soil wetting aid is produced as a mixture of granulated coir, granulated zeolite and a liquid surfactant which may be pluronic 30 polyol. The coir granules may be produced from high density moulded blocks of coir pith obtained as a bi-product from the Copra industry. The pith material is dispersed throughout the fibres around coconut husks. This material has myriads of capillary vessels which give it n remarkable capacity to absorb and hold water or oth^K c\<\ if • s 1! 'M 0 o 25Of0g liquids by capillary action. Specifically this material can take up to 100 times its own weight in water. The high density blocks of this material can be milled in conventional milling machinery and sieved to produce 5 appropriately sized granules. Coir has a natural pH of 5.4 - 6.8 plus an unusually high cation exchange capacity. It has carbon/nitrogen ratio of 110:1 and a high protective lignin content resists bacterial or chemical decomposition and breakdown.

Natural and synthetic zeolites are used in the petrochemical industry as catalysts and as "molecular sieves" to separate materials and as fillers in detergents. They have also been used as soil conditioners. Zeolite has a very high cation exchange capacity which enables it to 15 act as sponge absorbing ammonia in organic fertilisers (which in excess otherwise may be harmful) . It also attracts potassium, calcium, magnesium and some trace elements which cling to the zeolite until they can be released slowly and steady to plant life over time. It is 20 also highly absorbent to water and other liquids and it can take up some of the liquid surfactant to contribute to the surfactant holding capacity of the final mixture. Most importantly zeolite can be formed into strong hard granules which will give the final mixture mechanical properties 25 which make it easy to store and transport. Zeolite also confers good flowability to the resulting mixture so that the material in accordance with the invention may be easily handled and packaged by the manufacturer and can be readily distributed and worked by the end user. 30 A variety of surfactants could be used in the material according to the invention. For use as a wetting and re-wetting aid, the surfactant should not be quickly biodegradable but should have a relatively long life span and it should be effective as a wetting agent on 0 1 n 40 Unit 45 hydrophobic organic materials found in soils. One particularly suitable surfactant is the pluronic polyol sold commercially by BASF under the name Pluronic PE 6200, This is a block co-polymer in which the central polypropylene oxide group is flanked by two polyethylene oxide groups. The molar mass of the polypropylene oxide block is 1750 g/mol and the molecule contains 20% of polyethylene oxide. It conforms to the following structural formula: ho (ch2ch20) x ( chch2o ) y ( ch2ch2o ) 2h ch3 The main physical properties of PE 6200 are as follows: Pluronic Physical form Average molar mass, calculated from hydroxyl number Molar mass of hydrophobe Concentration Cloud point (DIN 53917) Butyl digol solution Water NaCl solution pH (5% in water) Density (23°C) Bulk density Viscosity (23°C, Brookfield, 60 rpm) Pour point Melting point Surface tension (DIN 53914, 1 g/1 in distilled water, 23°C) g/mol g/mol °C °C °C g/cm g/i mPa.s °C °C mN/m PE 6200 liquid ca. 2500 ca. 1750 ca. 100 ca. 54 ca. 33 ca. 7 ca. 1.04 ca. 500 ca. -1.4 ca. 46 Wetting power (DIN 53901, in distilled water containing 2 g soda/1, 23°C, 1 g/1) s > 300 The preferred method of production is to mix the 5 three components in the following ratios by weight of total composition: 40 - 80% Zeolite 10 - 40% Coir 10 - 40% Surfactant.

These are mixed in a conventional mixing unit until the liquid surfactant is fully absorbed into the granules of coir and zeolite. A typical naturally occurring Australian zeolite will take up 5 to 10% of the surfactant and the remainder will be absorbed by the coir, 15 the surfactant may be mixed firstly with the zeolite before the coir granules are added. This will ensure that surfactant is absorbed evenly through both the zeolite and the coir and will guard against excessive take up of the surfactant in localised clumps of the coir due to its 2 0 remarkable absorption capacity. The materials are simply mixed in a batch and the mixing process can take up to Vi an hour to be completed. There is no need to heat or dry the material and the only energy input is to produce the necessary mechanical mixing of the ingredients. 25 It has been found in practice that the coir particles should be in the size range 0.005 to 3.0 mm so as to spread evenly through the mixture without clogging or accumulating. The zeolite granules should be in the range 0.02 mm to 3.0 mm. If the zeolite granules are less than 30 0.02 mm they tend to form a dust and if greater than 3.0 mm they produce a heavy material with reduced flowability and a reduced surface area exposure to added moisture.

The material produced in accordance with the above described process contains the surfactant PE 6200 distributed throughout the material, primarily>in==.the coir /■* //'v ;25 r-r ;25 0 106 ;8 ;but also in the zeolite. The coir material is far from saturated with the surfactant and it remains strongly hydrophilic. Accordingly when the material comes into contact with water, it rapidly absorbs water into its 5 capillary vessels and the water is therefore brought into intimate contact with the surfactant which immediately dissolves in the water. The water can then readily wet even the most hydrophobic materials which occur in soils. Thus the material according to the invention is not only 10 capable of storing a much larger quantity of surfactant than previously available wetting aids but it also provides a strong capillary action which promotes contact between added water and the surfactant so that the surfactant is much more rapidly available and effective to quickly 15 enhance wettability and therefore to increase water retention in the soil. ;The greatly improved properties of the wetting aid produced in accordance with the invention as compared with commercially available materials have been 20 demonstrated experimentally as illustrated by the following examples: ;EXAMPLE 1 Materials ;(i) Potting mixture consisting of 85% pure bark and 25 15% fine sand was air dried in two 125 mm diameter plastic pots. The volume of the mixture in the pots was 800 ml .+ 50 ml. ;(ii) A granular wetting agent produced in the United States and sold commercially under the name ;30 HYDRAFLO. This material contains calcinated clay particles loaded with a surfactant. ;(iii) A granular wetting agent comprising (by weight) 70% of zeolite granules, 15% of coir granules and 15% of the surfactant PE 6200 produced in the ;25 0 1 0 8 ;9 ;manner described above. ;(iv) Tap water. ;Method ;12 grams of each wetting agent was spread on the surface of 5 separate containers of the dried potting mixture. 250 ml of water was poured over the surface of the pot. The water draining from the base of the pot was collected and measured. ;Results ;10 The water added to the pot with the wetting agent produced in accordance with the present invention percolated in to the potting mixture far more rapidly than the water added to the pot with the HYDRAFLO agent. 155 ml of water was collected from the base of the pot containing HYDRAFLO 15 indicating that 95 ml was retained in the potting mixture. Only 30 ml of water was collected from the base of the pot containing the wetting agent of the present invention, indicating that 220 ml of the water was retained in the potting mixture. ;20 EXAMPLE 2 Materials ;(i) Peat moss as supplied in bales. ;(ii) Granular wetting agent HYDRAFLO as described in Example 1. ;25 (iii) Granular wetting agent according to the invention as described in Example 1. ;(iv) Tap water. ;Method ;5 grams of each wetting agent were mixed separated into 150 30 ml samples of peat moss. After mixing, each sample was placed in a heap on the dish. A dessert spoon size indentation was made into the top of each heap and water was spread into each indentation. ;Results ;2*oioe The water added to the sample with the wetting agent produced in accordance with the invention percolated rapidly into the sample while the water in the sample with the HYDRAFLO wetting agent was retained in the indentation.

Other experiments have been conducted to compare the effects of various wetting agents in overcoming hydrophobicity in dry peat moss. These have shown that a dry granular material produced in accordance with the invention can promote the retention of water in dry peat 10 moss samples to an extent comparable with or even greater than by direct application of commercially available liquid surfactants, although the relative performance depends on the ratio of dilution of the liquid surfactants.

Although we prefer to use coir as the main 15 surfactant carrier, it would be possible to use other materials either in conjunction with or in substitution for the coir. Specifically it would be possible to use peat, milled palm tree trunk material or other naturally occurring fibrous material which absorb moisture at a rate 20 greater than 0.3% by weight without appearing wet or damp.

Material other than zeolite could also be used as the other granular component contributing mechanical strength and flowability to the final product. For example it would be possible to use calcinated clays and oth^r calcinated 25 products which have high absorption features.

Moreover the invention may be applied to the production of carriers for water dispersable substances other than surfactants. For example slow release insecticides or fungicides could be absorbed into the coir 30 or other capillary material to produce a granular flowable material loaded with the fungicide or insecticide which would be dispersed over relatively long periods on exposure to rain or artificial watering. Liquid fungicides or pesticides could be absorbed directly into the coir 250106 n material. Fungicides and insecticides in non-liquid form could be dissolved or suspended in a liquid or an emulsion prior to mixing with the coir material. Hormone growth stimulants, trace elements and other water dispersable 5 substances could be carried in a material produced in accordance with invention. It is accordingly to be understood that the invention can be applied to the production of a wide variety of materials with various applications. The invention is therefore in no way limited 10 to the details of the particular compositions or ingredients described but will include many modifications and variations within the scope of the appended claims.

Claims (23)

WHAT WE CLAIM IS:

1. A granular flowable carrier of a water dispersable substance comprising: a first granular component which has a 5 microstructure of capillary vessels and is capable of taking liquid into those capillary vessels so as to be strongly hydrophilic; a water dispersable substance disposed within the capillary vessels of the first granular component so as to 10 be held within the granules of that component; and a second granular component which is harder than the first granular component and is intimately mixed with the first granular component so as to enhance the mechanical strength and flowability of the mixture. 15

2. A granular flowable carrier as claimed in claim 1, wherein the water dispersable substance is water soluble.

3. A granular flowable carrier as claimed in claim 2/ wherein the water dispersable substance is a water 20 soluble liquid absorbed into the capillary vessels of the first granular component.

4. A granular flowable carrier as claimed in any one of the preceding claims wherein the capillary vessels of the first granular component are not totally filled with 25 the water dispersable substance so that the first granular material remains strongly hydrophilic such that on contact with the water it will absorb water into its capillary vessels to put that water into intimate contact with said water dispersable substance. 30

5. A granular flowable carrier as claimed in any one of the preceding claims, wherein the first granular material comprises granules of coir.

6. A granular flowable carrier as claimed in claim

5. wherein the average maximum dimension of the granules of 35 coir is in the range 0.005 mm to 3.0 mm.

7. A granular flowable carrier as claimed in any one ,, * =- „ G - 13 - of the preceding claims, wherein the second granular material comprises granules of zeolite.

8. A granular flowable carrier as claimed in claim 7, wherein the average maximum dimension of the granules of 5 zeolite is in the range 0.02 to 3.0 mm.

9. A granular flowable carrier as claimed in any one of the preceding claims wherein the water dispersable substance is a surfactant.

10. A soil wetting aid in the form of a granular 10 flowable material and comprising: a first granular component which has a microstructure of capillary vessels and is capable of taking liquid into those capillary vessels so as to be strongly hydrophilic; 15 a liquid surfactant taken into the capillary vessels of the first granular component so as to be held within the granules of that component; a second granular component which is harder than the first granular component and is intimately mixed with 2 0 the first granular component to enhance the mechanical strength and flowability of the mixture.

11. A soil wetting aid as claimed in claim 10, wherein the first granular component comprises granules of coir the average maximum dimension of which is in the range 25 0.005 mm to 3.0 mm.

12. A soil wetting aid as claimed in claim 10 or claim 11, wherein the second granular material comprises granules of zeolite the average maximum dimension of which is in the range 0.02 mm to 3.0 mm. 30

13. A soil wetting aid as claimed in any one of claims 10 to 12, wherein the liquid surfactant is a liquid pluronic polyol.

14. A soil wetting aid as claimed in claim 10, wherein the first granular component comprises granules of 35 coir in the proportion 10 to 14% by weight, the second granular component comprises granules of zeolite 250106 - 14 - proportion 40 to 80% by weight and the liquid surfactant is in the proportion 10 to 40% by weight, said proportions being percentages of total composition of the soil wetting aid. 5

15. A method of producing a granular flowable material carrying a water dispersable substance, comprising mixing a quantity of the water dispersable substance with granules of a first material which has a microstructure of capillary vessels and is capable of taking liquid into 10 those capillary vessels so as to be strongly hydrophilic and granules of a second material which is harder than the first material so as to enhance the mechanical strength and flowability of the resulting mixture.

16. A method as claimed in claim 15, wherein the 15 first material is coir, the second material is zeolite, and the water dispersable substance is a surfactant.

17. A method as claimed in claim 16, wherein the surfactant is mixed with the granules of zeolite before addition of the granules of coir to the mixture. 20

18. A granular flowable carrier as claimed in any one of claims 1 to 9, substantially as herein described.

19. A granular flowable carrier as claimed in claim 1, substantially as herein described with reference to either one of the Examples. 25

20. A soil wetting aid as claimed in any one of claims 10 to 14, substantially as herein described.

21. A soil wetting aid as claimed in claim 10, substantially as herein described with reference to either of the Examples. 30

22. A method as claimed in any one of claims 15 to 17, substantially as herein described.

23. A method as claimed in claim 15, substantially as herein described with reference to either of the Examples. CHRISTOPHER JOHN DRYSDALE 35 AND DAVID GEORGE NICHOLS By Their Attorneys -BALDWIN, SON & CAREY ' c'\