EP1027402A1 - Gel de polyacrylate destine a etre utilise dans l'horticulture - Google Patents

Gel de polyacrylate destine a etre utilise dans l'horticulture

Info

Publication number
EP1027402A1
EP1027402A1 EP98916723A EP98916723A EP1027402A1 EP 1027402 A1 EP1027402 A1 EP 1027402A1 EP 98916723 A EP98916723 A EP 98916723A EP 98916723 A EP98916723 A EP 98916723A EP 1027402 A1 EP1027402 A1 EP 1027402A1
Authority
EP
European Patent Office
Prior art keywords
polyacrylate
water
weight
composition
gel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98916723A
Other languages
German (de)
English (en)
Inventor
Kenneth Roger Williams
Marlene Elizabeth Conway
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
1340911 Ontario Inc
Original Assignee
1340911 Ontario Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 1340911 Ontario Inc filed Critical 1340911 Ontario Inc
Publication of EP1027402A1 publication Critical patent/EP1027402A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
    • A01G24/00—Growth substrates; Culture media; Apparatus or methods therefor
    • A01G24/30—Growth substrates; Culture media; Apparatus or methods therefor based on or containing synthetic organic compounds
    • A01G24/35—Growth substrates; Culture media; Apparatus or methods therefor based on or containing synthetic organic compounds containing water-absorbing polymers
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
    • C05G3/00—Mixtures of one or more fertilisers with additives not having a specially fertilising activity
    • C05G3/80—Soil conditioners
    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
    • C05G5/00—Fertilisers characterised by their form
    • C05G5/40—Fertilisers incorporated into a matrix

Definitions

  • the present invention relates to polyacrylate gel for horticultural uses, and its use therein, and in particular to modification of sodium polyacrylate superabsorbent polymer gels for horticultural use.
  • absorption capacity index is defined as: (wt of water saturated gel polymer - polymer dry wt) /polymer dry wt. The measurement of ACI is described below.
  • Plants and seedlings are normally germinated and grown in commercial operations dedicated to that business. However, the plants and seedlings are normally not offered to sale, or only a small percentage is offered for sale, at the location at which the plants and seedlings are germinated. It is common practice for plants and seedlings to be shipped to other locations involved in the retail of plants and seedlings to the public. In cities, a wide variety of stores will offer plants and seedlings for sale, including grocery stores, department stores, multi-purpose stores, hardware stores and many others. In addition, there are retail stores that specialize in the sale of horticultural products to the public. Alternatively, the plants and seedlings might be mailed or shipped directly to a person or entity e.g. a market gardener, that has ordered the plants or seedlings from the grower.
  • a person or entity e.g. a market gardener
  • SAP superabsorbent polymer
  • anionic SAP's which are sodium polyacrylate, tend to lose their ability to absorb large quantities of water in a cyclic wet/dry environment because of exchange of cations from the surrounding soil, particularly from clay soils.
  • sodium polyacrylate tends to condense and form crosslinks that inhibit re-swelling when it is re-wetted. Even when used in situations where a limited number of wet/dry cycles are experienced, sodium polyacrylate inhibits plant growth or in some cases is toxic to plants. This inhibition of plant growth or toxicity is believed to arise because the sodium ions in the sodium polyacrylate network are exchangeable and these ions are adsorbed by clay particles or tend to undergo exchange with cations on the surface of plant roots. The consequence is a condition that is analogous to an alkali soil, which generally tends to adversely affect or inhibit plant growth.
  • Sodium polyacrylate is the dominant superabsorbent polymer product in use today. Its major application is as a body fluid absorbent in hygienic disposal products, particularly in diapers. In such uses, rapid absorption of water is an essential requirement, and the polymer must have a strong affinity for water. It is estimated that over 90% of all superabsorbent polymer produced is sodium polyacrylate. Such an economy of scale in its production means that the cost of sodium polyacrylate tends to be lower than that of superabsorbent polymers otherwise used for agricultural end uses. In addition commercial processes are now available for recovery of superabsorbent polymer from hygienic disposal products, including diapers. Such a process is disclosed by M.E. Conway et al in U.S. 5,558,745.
  • a number of water absorbing substances have been disclosed as additives for soil to provide a moisture source for plants.
  • An important criteria for successful use is that the water absorbing substance must be capable of maintaining its water retention characteristics over a series of wet/dry cycles.
  • Polyacrylamides appear to have superior cyclic moisture retention characteristics than polyacrylates and commercial agricultural SAP's are polymers or co-polymers of acrylamide.
  • U.S. 5,405,425 discloses that a sulphonyl-containing polyacrylamide shows superior retention of its ability to reabsorb water during cyclic wet/dry treatment cycles.
  • Sodium polyacrylate gel offers potential for use in horticultural end uses, provided that the tendency of sodium polyacrylate to inhibit plant growth or be toxic to plants can be reduced. Accordingly, the present invention provides a polyacrylate for horticultural use, said polyacrylate being a polyacrylate of a divalent cation and having an ACI in the range of 30-100, especially 40-100.
  • the polyacrylate is obtained from a sodium polyacrylate by exchange of said sodium cation with said divalent cation.
  • the polyacrylate of the divalent cation has a water content of less than 50%.
  • the divalent cation is an alkaline earth metal, especially calcium.
  • the present invention also provides a method for the preparation of a polyacrylate for horticultural use, comprising the steps of treating an alkali metal polyacrylate in aqueous solution with a water-soluble compound of a divalent cation, separating the gel so formed from the aqueous solution and drying the gel to a moisture content of less than 50%.
  • the water- soluble compound is a compound of an alkaline earth metal, zinc or iron (ferric) , especially a calcium compound e.g. calcium hydroxide or lime, calcium sulfate or gypsum, or calcium nitrate.
  • a calcium compound e.g. calcium hydroxide or lime, calcium sulfate or gypsum, or calcium nitrate.
  • a nonionic water-soluble compound is added to the aqueous solution prior to filtering the gel e.g. urea or sucrose.
  • the present invention also provides horticultural use of the polyacrylate disclosed herein for the germination of seedlings, or for the transportation of plants or seedlings, the polyacrylate being used as a water-retentive medium.
  • the present invention is a polyacrylate gel for horticultural end-uses, although it could be more generally used in agricultural end-uses, depending on cost. It will be referred to herein as a soil additive.
  • the soil additive is a polyacrylate and would normally be formed from a sodium or potassium polyacrylate superabsorbent polymer (SAP) that has been treated in its gel state.
  • SAP sodium or potassium polyacrylate superabsorbent polymer
  • the superabsorbent polymer may be virgin polymer, but it is particularly intended that the superabsorbent polymer would be such polymer that has been recovered from another process.
  • One example of such recovery is from used disposable diapers or other absorbent sanitary paper products, also referred to as personal care products, during processes for recycling and recovery of components of such processes for future use.
  • One such process is that of the aforementioned U.S. 5 558 745.
  • the polyacrylate may be in a variety of forms before treatment as described herein.
  • Superabsorbent polymers that are acrylate polymers are normally cross-linked during the manufacturing process. Any cross-linking referred to herein is in addition to cross-linking that may have occurred in the processes for the manufacture of the polymer.
  • the super absorbent polymer after treatment for use in the soil additive of the present invention, has an absorption capacity index (ACI) that is at least 30, e.g. in the range of 30-100, especially in the range of 50-80.
  • ACI absorption capacity index
  • the ACI of an anionic superabsorbent polymer may be decreased by cross- linking of the polymer with cations.
  • chemical compounds that may be added to an aqueous solution of the anionic superabsorbent polymer to effect cross-linking of the superabsorbent polymer include soluble salts of at least one of an alkali metal, an alkaline earth metal, aluminium, copper (II) , iron (III) and zinc.
  • the salts that may be added to effect cross-linking of superabsorbent polymer for the present invention including sodium polyacrylate and potassium acrylate, are salts of divalent cations, especially alkaline earth metal cations. Examples of such divalent cations are magnesium, calcium, barium and zinc. Calcium is preferred.
  • salts examples include calcium chloride, calcium nitrate, dicalcium phosphate, tricalcium phosphate, magnesium chloride, magnesium nitrate, magnesium sulphate, barium chloride, barium nitrate, zinc sulphate and zinc nitrate.
  • Calcium hydroxide may also be included to aid in deswelling the SAP.
  • the salts may be soluble in water or only partially so. In the latter case, ions in solution will be absorbed, and the ions removed from solutions will be replenished from undissolved salt, according to solubility equilibria of the salt in the solution.
  • the amounts of cross-linking agent are preferably adjusted so that the absorption capacity index (ACI) of the super absorbent gel polymer is at least 30, especially 30-100, as indicated above.
  • ACI absorption capacity index
  • the particulate gel super absorbent polymer that has been treated as described herein is separated from the aqueous solution and subjected to drying procedures, preferably in a heated air stream at about 60°C. In embodiments, drying is allowed to proceed until a solid with a moisture content of less than 50% is obtained, especially a moisture content of about 1-10% moisture. The solid is then ground to size for adding to soil.
  • a non-ionic water-soluble additive may be added to the gel before drying.
  • the amount of the non-ionic water-soluble additive may be varied widely, but in embodiments is up to 50% by weight of the dried solid, especially 10-40% by weight. Examples of such non-ionic water-soluble additives are urea and sucrose.
  • the non-ionic water-soluble additive if used, may be added in a separate step. However, it is preferred that the treatment and formation of the particulate form of the super absorbent polymer and addition of the nonionic water-soluble additive be carried in one step. Growth promotion may also be achieved e.g. by addition of such an additive or by utilizing a cross-linking agent that is in itself also a growth-promoting agent e.g. a nitrate.
  • the soil additive of the invention is added to soil, for instance by using techniques typically used for the addition of fertilizers to soil.
  • the amount of soil additive added to soil may be varied over a wide range of concentrations.
  • the soil additive may be used as the only medium for the plant or seedling i.e. in the horticultural use e.g. the plant or seedling could be grown in the soil additive per se, or the soil additive may be admixed with soil or an inert material.
  • the soil additive is used in admixture with soil, especially with soil as the major component for germination of seedlings and used in higher concentrations, including used alone, with plants e.g. for the shipping of plants.
  • the present invention provides a horticultural composition formed by admixing sodium polyacrylate with at least 250 times its weight of water, preferably with an amount of water that is in excess of the amount of water that is absorbable by the sodium polyacrylate. A preferred amount is at least350 times its weight in water. Excess water is then removed e.g. by filtering or pressing.
  • the sodium polyacrylate may then be used in horticultural end-uses e.g. for shipping of plants.
  • the sodium polyacrylate may be partially dried. For instance, the sodium polyacrylate may be dried so that at least 50% of the water absorbed into the solution polyacrylate remains in the sodium polyacrylate.
  • the water used in the treatment of the sodium polyacrylate contain divalent cations e.g. calcium or magnesium.
  • divalent cations e.g. calcium or magnesium.
  • the invention discloses a way to modify a polyacrylate, especially a sodium or potassium polyacrylate, so that it may be used for, in particular, horticultural end-uses, especially for plants and seedlings without the adverse effects of sodium or other alkali metal.
  • a polyacrylate especially a sodium or potassium polyacrylate
  • the zone surrounding the super absorbent particulate better retains its moisture.
  • a more desirable environment is created for the plant roots in these zones.
  • Such environment is beneficial until such time as the plant or seedling is planted, providing a more consistent supply of moisture, especially during long periods of moisture deficiency.
  • the absorption capacity index (ACI) test used herein was as follows: l.Og of the dried particulate product was placed in 200 ml of water for a period of time. The resultant gel was collected on a fine mesh screen and the weight of the gel was measured, from which the ACI value was calculated. The procedure was repeated, after discarding the water not absorbed in the gel, using a further 200 ml of water and the ACI value was recalculated. This procedure was repeated for 5 or more cycles. This testing cycle was used as a simulation of the moisture behaviour found in soil. For instance, under wet soil conditions, where there is runoff and/or loss to the water table in the soil, the SAP should experience swelling similar to immersion in water.
  • the gels were made up 1:100 with tap water.
  • EXAMPLE II The efficacy of chemically modified sodium polyacrylate SAP gels as a plant transplant medium were studied using Blue Lake bush bean seedlings grown for 17 days in Peter's Professional Potting Soil, Scots-Sierra Horticultural Products Co., Marysville, OH. The bare root seedlings were transplanted after two permanent leaves were developed on each specimen, into 6 oz clear polyester cups containing various SAP gels. The dry SAP test items were mixed 1:400 with tap water and they were then filtered using a screen to remove unabsorbed water. After 15 days the seedlings were rated for new leaf growth after transplanting. The gels used were as follows:
  • Example II Good seedling leaf growth in the Stockhausen gel viz. a sodium polyacrylate, is believed to be a result of treatment with excess tap water. It is to be noted that in Example I, the seeds were planted directly in the gels. In contrast, in Example II the gels were first swollen in an excess of water which was removed during a filtration step. The filtration step may have resulted in removal of sufficient sodium ions to render this product acceptable as a plant transplant medium.
  • Example II The effect of reduced degree of hydration of sodium polyacrylate gel on growth of bush bean seedlings was tested.
  • a ratio of sodium polyacrylate: water of 1:400 was used.
  • the ratio was reduced in separate tests, to 1:200, 1:100 and 1:50.
  • Example II Treatment of the bean seedlings followed the procedure outlined in Example II. Separate tests were conducted in which tap water and distilled water were used to hydrate the sodium polyacrylate.
  • a divalent compound to a sodium polyacrylate gel must be sufficient to replace most or all of the sodium ion attached to the polymer chain. However, use of excess divalent cations will prevent the resulting product, after it has been dried, from reabsorbing significant quantities of water. Such a product would be expected to have little utility as a plant transplant or preservation medium.
  • the reswelling characteristics of a processed recycled sodium polyacrylate gel can be determined from the ACI value after the divalent deswelling compound is added to the swollen gel.
  • a gel was made by adding 6.0 g agricultural gypsum [82.2% CaS0 4 H 2 0] to 10 g of Stockhausen Fam SAP, followed by 5.0 g of urea. The ACI was then determined, and found to be 29.6. After drying, this material which then had an ACI of 23, did not reswell adequately in tap water.
  • Example II In contrast, the experimental gel described in Example II had an ACI value of 61 after addition of Calcium hydroxide. After drying and reswelling in tap water, this gel had an ACI of 91.
  • a gel was formed from 3.0 g of sodium polyacrylate mixed in 405 g of tap water. To this gel was added a solution of 0.9 g of ferric chloride hexahydrate in 45 g of water. The gel dewatered to yield an ACI value of 82. This result indicates that a large quantity of sodium ion present in the original super absorbent polymer had been replaced by ferric ion. When this product was dried and water was reintroduced [1.0 g dry solid/200ml water], an ACI value of 30 was obtained. Rewetting the filtered gel with 200 ml quantities of water yielded succeeding ACI values of 43 and 51. Thus the swelling characteristics are similar to those found when calcium compounds are mixed with SAP.
  • the swelling characteristics observed in the previous examples using sodium polyacrylate polymer were also observed with potassium polyacrylate polymer.
  • AridallTM 1460 (a potassium polyacrylate super absorbent polymer, produced by the Chemdal Corp.) was added to a ferric chloride solution composed of 0.4 g of ferric chloride hexahydrate in 240 g of tap water.
  • the Aridall 1460 polymer absorbed all of the ferric chloride solution.
  • 0.8 g of ferric chloride hexahydrate dissolved in 50 g of water was added to the gel and rapid dewatering occurred.
  • the filtered gel had an ACI of 41.
  • the consecutive ACI values were 14, 23 and 27.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Pest Control & Pesticides (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Environmental Sciences (AREA)
  • Soil Sciences (AREA)
  • Cultivation Of Plants (AREA)
  • Soil Conditioners And Soil-Stabilizing Materials (AREA)

Abstract

Polyacrylate destiné à être utilisé dans l'horticulture. Le polyacrylate selon l'invention est un polyacrylate d'un cation divalent qui présente un indice de capacité d'absorption situé entre 30 et 100. L'invention concerne en outre une composition horticole contenant un polyacrylate qui a été mélangé avec au moins deux cents fois son poids en eau. L'invention concerne enfin un procédé de formation d'une composition horticole consistant à mélanger un polyacrylate avec au moins 250 fois son poids en eau, et en particulier avec au moins 350 fois son poids en eau. Le polyacrylate est utilisé, par exemple, dans la germination de semis, avec des plantes ou pour le transport de plantes ou de semis.
EP98916723A 1997-04-25 1998-04-21 Gel de polyacrylate destine a etre utilise dans l'horticulture Withdrawn EP1027402A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US4510497P 1997-04-25 1997-04-25
US45104P 1997-04-25
PCT/CA1998/000374 WO1998049252A1 (fr) 1997-04-25 1998-04-21 Gel de polyacrylate destine a etre utilise dans l'horticulture

Publications (1)

Publication Number Publication Date
EP1027402A1 true EP1027402A1 (fr) 2000-08-16

Family

ID=21936019

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98916723A Withdrawn EP1027402A1 (fr) 1997-04-25 1998-04-21 Gel de polyacrylate destine a etre utilise dans l'horticulture

Country Status (4)

Country Link
EP (1) EP1027402A1 (fr)
AU (1) AU7021998A (fr)
CA (1) CA2287352A1 (fr)
WO (1) WO1998049252A1 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005053381A1 (fr) * 2003-12-05 2005-06-16 Nippon Shokubai Co., Ltd. Matiere particulaire retenant l'eau, pour la culture de plantes, comprenant une resine absorbant l'eau comme composant principal
MX2010009942A (es) 2008-03-31 2010-09-28 Rhodia Operations Composiciones de polimero responsivas a estimulos de autosituacion en aditivos de suelo y metodos para uso.
CH708820A1 (de) 2013-11-07 2015-05-15 Tecan Trading Ag Inkubationskassette.
FR3016878B1 (fr) * 2014-01-30 2017-07-07 Liliz Polymere super absorbant modifie renfermant un engrais
CN109369260A (zh) * 2018-11-16 2019-02-22 东北大学 生态保水、节约肥料和促进增产的植物生长剂制备方法

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2801985A (en) * 1956-05-18 1957-08-06 American Cyanamid Co Soil stabilization
NL133350C (fr) * 1966-09-08
JPS5849515B2 (ja) * 1974-06-05 1983-11-04 日本化薬株式会社 ヨウエキサイバイホウ
US5065822A (en) * 1990-09-14 1991-11-19 American Cyanamid Company Crosslinking water soluble polymers with iron to form gels for use in subterranean profile modification
JP3155294B2 (ja) * 1991-06-20 2001-04-09 三菱化学株式会社 高吸水性ポリマーの製造法
JPH0978050A (ja) * 1995-09-08 1997-03-25 Nippon Shokubai Co Ltd 農園芸用保水材

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9849252A1 *

Also Published As

Publication number Publication date
WO1998049252A1 (fr) 1998-11-05
AU7021998A (en) 1998-11-24
CA2287352A1 (fr) 1998-11-05

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