CA1109586A - Lignsulfonate-based graft polymers, their preparation and uses - Google Patents

Abstract

ABSTRACT OF INVENTION

The present invention relates to new graft polymers obtained from lignosulfonate and a monomer selected from vinyl benzene, vinyl cyanide, vinyl acetate, vinyl pyridine, vinyl chloride and di-vinyl butadiene and mixtures thereof at a pH
between 2 to 6 in the presence of an initiator.
The new graft polymers have been found to be very useful as soil conditioners and as binding reagents for agglomerating single particles of particulate materials.
The graft polymers according to the invention are obtained in the form of an aqueous solution, which may be transformed into a powder by spray drying. As soil conditioners they may be applied by spraying, alone or admixed with fertilizers or pesticides and also combined with the operation of planting and soil stabilization.

Description

Tl~e present invention reLates to new soil conditioners for improving soil structure and to r,~et}lods for their manufacture.

As known, tlle structure~of a soil determines a large nl~nber of its ~roperti~s suclt as permeability ~o water~ ~orosity, crust formcl~ion, S aera~ion etc. ~m improved structure will be beneficial to the prevention of erosion by liater, increase in crop yields etc. It also simplifies tl~e mecllanical preparation ol the ~ield before planting. ~\n increase in a~regate size alld in per cent of aggrega~es will reduce n~ d eroslon. It ~iill also recluce a lligh penetration o:E rain in~o the soil ~0 and will improve l~ater holdillg capacity and reduce evaporation, the result of l~llicll is a better ~ater balallce in arid ~ones. Of special importance is t}le prevention of crus~ formation due to puddling by rain drops, Prevention of this puddling, allows for a better rain infiltration into tlle soil and causes a reduction of rlm of~ llith a consequent erosion decrease. The crust prevention improves gerrnination and aeration of sa~lings.

It has been postulated tllat the di~ferences in structure between the ~mdesirable and tile desirable types of soils are attributable to differences in the type of the electrical charges of the individual soil ~0 particles. Accordingly, it has been proposed to condition or to im~rove poor soils, for example structurally unclesirable clàyey and loam soils~
by applying to them certain synthetic yolyelectrolytes which are water soluble, partially water soluble or l~ater insoluble. ~lese are mainly based on polyacrylaniides, polyJ~Iethyl-acrylonitriles, copolymers o~
acrylonitriles wi~h vinyl acetate etc. ~lus, for exa~le, U.S. Patent No. 2,625.~71 claims a copolymer containing 80-84% acryloni~rile, 11-15~ meth~crylonitrile and 5% vinyl acetate and hydrolysed in order to make it hydropllilic. U.S. Patent No. 2,8~7.392 describes a co~lolymer containing 50% metllacrylonitrile and 50% butadiene. U.S. Patent No.

2~7~5.2'70 claims a modification of polymetllylacrylonitrile~ after llydrolysis to the acidic form~ the polymer is absorbed on *o ~he surface o vermiculite particles and used in this form as soil conditioner.

Altllough these polyelectrolytes have been used successfully in a n~mber o 1imi-ted applications, such as llouse gardening, tiley have not become ~idespread due to one or more of ~he following reasons:

~.

.~, i;8~

~a) Tlley c~r_ too ex?ensive for large scale ~e.

(b) ~le streng*ll oE bonds lloldillg the par~icles of soil in cm aggrega~e~
is too higll and t]lus detrir,lelltal or certain ~roycrties.

~c) Very oten they ap~ear in a ~OWàer form, WhiC]I causes problems in s tileir s~orage and is very inefficient in field aI)plica~ion.

~d~ ~ome o tnelllllave toxical proper~ies :~or ~nimals and `tuullall beings.

(e) Some of tilem are easily decomposed by bacteria present in ~l~e soil.

~f) Some o~ -tllem are not suf~icien*ly stable even for a complete season ~eillg readily deco~nposable and washed out.

efcrences are encountered describing the use of li~osulfonatc as ;oil contlitioller. Some improved results are claimed to be achieved in ol)tainillg soil agg~egctes using amounts o~ about 2~ or more by weigh~
lignQslllEonate. ~lol~evcr, 5uC}I relatively large amoullts of lignosulfona~e become expensive in application as ~ell as in manipu~ation and also raise ~roblems concerning the bacterial activities in the soil. Also the hi~l~ lignosulonate concentration affects the soil chemical properties important for plant nutri*ion. ~le lignosulfonate is leaclled through the soil and thus is wasted ~o a large extent; it also pene*rates to certain layers where it is not nee~led and may even ~e harmful and cause problems of contamination. Large amounts of lignosulfonate also tend to produce a massivc ratiler than the friable aerated structure desirable in most soils for agricultural purposcs. The lignosulfonates may become irreversibly dîsactivated by some mul_tivalent cations and at the same tlme when applied in large amounts deprive the plants from some of the ~5 necessnry microelements.

In our co~endillg patellt application No. 267~239, new soil conditioners were yrovided t~hich were made by the graft polymerization o an acrylic n~ollo~ner an(l crude lignosulonate in the presence of an initiator. According to the present lnvention it has been fowld that other monomers can be successfully utili~ed in order to manufa~ture new soil conditioners.

.~ .

35i8~

us the invention consists of soil conditioners WiliCh are produced by the grat ~olymeri~ation of a vinylic monomer with crucle lignosulfona-te in tlle ~resence o~ an initiator. ~ne vinylic rmonomer can be any one selected rom tlle group of vinyl benzene (styrene), vinyl acetate~ hyclrolysed i vinyl acetate, vinyl cyanicle (acrylonitrile), vinyl cllloride, vinyl pyridine, vinyl butadiene etc. It is also possible to use a combination of two or ntore of the abQve monomers or ac~nixed Witll any one of the acrylic n~ollolllers described in the parent patent application.

One of tlle ~naill objects of the soil conditioners according to the resent invelltion is to im~rove the soil structure. Y'hls is contrary to ~he ef~cct obtainecl by other materials, which cause soil solidification i.e.
il~creased soil strength.
.
ADlong the adYantages o~ the new soil conditioners, the following can be mentionecl: ~1) Their manufacture is very simple, (2) they are relatively 1~ ine~c~)ellsive, (3) the amount of the vinylic component in the graft polymer m~y be small. Tl~us for example it was found that, instead of using equal ~arts ~y weigl~t o vinylic monomer and crude lignosul-fonate, even only one rt of vinylic monomer to 6 or 8 palts o crude lignosulfonate can be used, de~ending an the ty~e of soil required ~o be conclitioned and the specific goal desired. For example, for conditioning a soil in order to ~rotect it from erosion by rain and to prevent crust :c~ormation, it has been ouncl that a graft polymer containing 0.6 parts ~inyl acetate and 1 part lignosulfonate gave almost the same results as a ~raft polymer pre~ared from 1 part vinyl acetate and 1 part lignos~llfonate. Of course the latter graft yolymer~
~5 colltai~ g as it does more o the vinylic component, will be relatively more ex~ensive than the forlller one. The higher vinylic component in the grat ~olymer results in ~I soil conditioner with a hig}ler molecular wei~ht and stronger bonds with the soil.

~ pClSOII skilled in the art af-ter reading the present specification

3~ wlll certainly be able to determine the proper ratio between the lignosulfonate and a p~rticular vinylic monomer in order to obtain the soil conditloner most stutable ~or the l)u~pose recluire~l. It is also ~ossible to use a ~ixture of two or more graft ~olymers prepared separately Wi~}l different monomers or diffelent ratios between lignosulfonate and vinylic monomers. In this s~ manner each conditioner in the mixture will act on the soil according ~o i~s ~rj .
.
' ' 3~

composition, for tl.e specific goal. For e~a~ple if ~he condi~ioner is to be s~rayed, one niay use a mix~ure o, two types. One type ~ould be of a higher molecular weigllt for stronger bonds at ~he surface. ~le other may be of a lo~icr molecular weigllt to improve the penctration ~low the surface.

Conditioners of di:Eferellt compositions may form better boncls with clif~e~ent constituents in the svil. For example, graf~ polyl,\ers witll acrylonitrile, metllyl acrylate or l~oth, form better bonds with particles o CaCO3 wllile a gra~`t polymer with acrylic acid is just as good with ine llOUg]l silica and clay minerals.

According to a preferred embodiment of tlle ~resent invention~ it is possible to pol~nerize the crude lignosulfonate with ~wo or more vinylic monoillers in the same reactor. The two or more vinylic monomers may be illtro~uced eitller togetller, whereby thc graft polymerization occurs 1~ simultancously or separately, whereby the graft polymerizations with each mollomer will occur consequently. There are cases, ~or exaLmple, when vinyl acetate is utilized, where the polymcrization should be carried out in an atmosphere of nitrogen in order to prevent any possible inhibition by o~idation of ~he monomer. rnere are common e~pe~lients known to any person skilled in the art o polymerizing such monomers.

l~Le term "crude lignosulfonate" as is used in the present specification, includes the aqueous solution resulting from the processing o-f plants or ~ood for the separation oE cellulose and lignosulonic aoid or sal~s thereof as obtained without any puriication. ~le constitution of the crude ~5 lignosulfollate varies depellding on the type o plant or IYOOd u~ilized and on the method o processing; it appears generally in the orm of Ma .~ NH~
or Ca salts along with other polysaccharides, which for cert~in uses are harr,~ul and have to be removed. It has been found tha~ tl~e lignosulfonate salts to be utilized in the method according ~o the present invention, may 3V be in the crude form, which is also less expensive than the puri~ied form, witllout im~airing the activity per unit weight of the soil conditioner.
Fllrthermore, experiments with certain materials indicated higher activity per ~it welght of a soil conditioner procluced from crucLe lignosulfonate;
it goes however without saying that purified polysacchcLride - free lignosulfonate, often also referred to as lignosul~onic acid or lignosulfonate salts ~ay also be utilized.

.~

.

r,l~ graft poly~neri~ati~n bet~ieen the vinylic ~onomer an~l t}~e lignosulfonate is a sirllp1~ addi~ion reac~ion 1~nic1l occurs generally at a pl-l in tlle range of 2 to 6 and preferaloly in the ~ange oE 3 to ~. The product obtained is stable and even a E~er n~ore t~an one year of storage no cllange in its structure or in tlle results ob-tainecl from its utilization were observed. Tlle soil conclitioners obtained may be cïried or exc~nple by spray dryer ancl stored or used in a powder Eorlm Tlle grat polymers ol)~ained in accordance with the present inventlon ;II'C usecl preerably in their hydrophilic form ~hicil recluired l~ydrolysis oflU ~lle ~olyn~er for ~YIlich tile knol~n ~uethods l~ith an alkaline solution Sucll as NaOil, ~OIi, Ca(O}1)2 or ~ OH are usc)d; where the graft polymer also includes acry~ic acicl "nethacrylic acid~ or hydrolysed vinyl ace-tnte as on~ of the mollo~ners l~hich already possess a llydrophilic character only ~)artial hydrolysis may or mere neutralization be required. Beore hydrolysis l!i it c~n le ol~tainecl as a,l emulsion with a ~elatively gooci stability.

I`lle initia~or recluired to be present in the graft polymeriza~ion can l)e selected rom kllowll reagents usecl in this -type of reaction e.g. hydroge peroxi(le or various organic perocides such as cumene hydroperoxide. It is nlso possible to initlate tlle polynlerization reaction by purely pilysical n~eans, sucll as ultraviolet racl:iat:ion.

~le vinylic mono1llers may be u~ilized such as are commercially available t~ithout any prior treatn~ent ~e.g. distilling out the inhibitors ganerally usecl or tlleir storage). ~ person s~illed in the art Oll polymerization will selcct the proper reagent -~or parforming the grat polymeriza-~ion~ ma]cillg IlSe o tl~e available commodities and reagents.

Colllpared ~ith ti~e known polyelectrolytes ba~sed on acrylonitlile copolyalers~ as clescribed in the prior art~ the new soil conditiollers accol~dillg to the present invention, are claimed to be much superior being cl~aracterized by tile follo~ing improved properties;

~0 1. Tlley h2ve a long shsl li:Ee without special storage precautions such as clry atmospllere, darkness or oxygen-ree atmosphere.

2. The molecular weight of tlle graft polymer according to -the present invention is re~luced and therefore the nu]nber of effective bonds per unit weight of soil conditioner is il~creased facilitating a more uniforl~ s~readillg of the conditioner througll the soil and thus a greater efficiency.

3. Tlle graft polyDIer is more soluble and thus less sensitive to possible furt}ler polymerization or setting with time.

4. Tlle bonds Eormed between the new conditioner and t~le soil are strong enoug}l for maintainillg an aggregate of the proper magnitude, but not too strong so as to cause the formation of large soil cloc~ or too strong clods or not sufficiently permeable to permit adequate movelllent o water, air and nutrients into the soil treated.

S. rlle boncls formecl are at least partially regenerative, whicll means that the asgregate property of the soil persists even ~fter several cycles lS of rain, drying and working of the soil.

6. Tlle graft polymers are water soluble or may be produced as stable suspensions which can be easily transferred and diluted.

7. The hydrolysed graft polymers are not sensitive to solutions of many electrolytes even at high concentrations which enable use of water of various qualities.

8. 'rl~ey are practically non-toxic.

9. ~lost of them can be diluted to any extent and sprayed without problems of clogging the nozzles or pipes.

10. Il~e properties o the soil conditioners may be changed by varying the 2$ proportions between the monomers and lignosulonate as well as the extent of hydrolysis.

Concerning the procluction of the new soil conditions, the process involved is characterized by the following advantages:

j,~,, e main component, ~ osulolla~e, is a low cost raw m~terial whicl~
today is an environmental ~urden.

2. ~le process does not require the removal of tihe inhibitors fro~ the vinylic monomers, as generally encountered in such grat polymeri~ation.

3. ,~llen emulsions are desirable to be prepared~ no ad~itional surEace active agen~s or organic solvents are required.

4. l~e reaction occurs at ambient temperatures and in most o ~he cases at atmos~l~eric pressur&. Generally the reaction time is about 5 minutes ` at a temperature of l~etween 30 to 9SC~

10- 5. ~le ~olymsrization of the monomers is almost complete leaving only ~races of monomcr ~mich lllay be left in the end produc-t.

6. Tap water or even ~ith a higher salt content may be utilized.

Tlle application of the soil condi~ioners prepared in accordance with the present invent:ion can be done by the known methods. ~hen used in the solid form, it can be mixed ~ith the soil or spread mechanically~ watering and if necessary rewor~ing the mixture. I~len usecl as an aqueous solution~
the soil conditioner is simply mixed with the wet soil. The soil conditioner may be also applied together with the irrigation water. The amount of soil conditioner to be given will vary fr~m soil to soil in accordance ~ith ~he goal envisaged; th~ :Eor example, for a loess-type soil, illTproved results in the structure, such as increased aggregation, were obtained by using bet~een C3.025o and 0.1% by lYt of the soil. Hi~her amoullts of soil conditioner, up to 0.2% by \~t ~on a dry basis) will further increase the proportion of stable aggregates~ but this will gen2rally not be econon\ically attractive. For soil stren~thening in construc~ion work however, higller no~ults may b~ recon~ended.

preerred method for the application of the new soil conditloner, ~hicll is 3nuch simpler than the above Xnomn l~ays, is by spraying the aqueous solution di~ectly on the soil. This method of application for soil condition-ing has become possible, thanks to the particular properties of the copolymer obtained according to the present invention.

X`
., .
- . . . .

I~ has beell fo~lcl tha~ the condi -tioner sprayed on -~o tll~ s oi 1 -.~orms a protective layer ~hicil prevents aggrega~e brea~age by action of rain~rops o~ ind erosion. ~le rate of ~ater iililtration into tlle soil is maintained, ~reventing the for~lation of an impermeable crllst by the i~npact o-f raindro~s. It also improves the regeneration of infiltra~ion capacity after drying and th~ls hel~s in the germination of seeds.

It l~as beell fo~uld -that by repeated spraying, dryirlg and sllallow cultivatioll, all excellent protective mulc}l layar is producecl wJlicil is ~ellaorated, reduces the evaporation Erom the soil and thus re-~ains the ~ater, alld leads to m~r~e~ly il~proved crop ~ie:lds. This has a s-~ecial in~ortance ~here Cl`USt fOrlllatiOlI iS detrimelltal and water supply is limited.

Instead of usillg aqueous solutions~ the hydroly~ed graft polymer obtained according to the present invention~ may be sprayed admixed with an ~queous f~rtilizer sucl~ as anullonia solution. In this manner the incorporationlS of tlle soil con~itioner is carrie~ out at the same time as the fer~ er ap~licat:ioll, thlls saving additiollally an agro-technical operation. In a similar mallller it is also possible to incoryorate the soil conditioner in various pesticides or herbicides and apply to the soil to~ether wi~h these.

~ccordillg to another embodiment of the present invention, the soil conditi~nillg apparatus can be mounted on various soil working implements and es~ecially on the planting macllines. T~is apparatus consists o devices ~or spreading tile conditioner either in powder form or preferably in an aqueous solution on to the soil. ~le soil with ~li.Ch the seeds are covered, will already contaill the conditioner reagent and thus will retain good wELter iniltr~tion and good aeration prospects even after heavy rains or irrigation.
Tllis combined operation o~ simultaneous planting and soil sta~ilizatioTI can be carried Ollt by the simple addition o the appropriate nozzles in front of, besides or behind the planting tool. Generally speaking, the amount of soil conditioller needed is about 20 to 50 ~g. ~er hectare o soil.
LRrger amounts can be used with better results howeve~ are less attractive ~rom an economical point of view. It has been fo~md that the application oE the ne~ soil condi~ioll can also be carried out on an area of limited extellt in strips, or on ~atches of soil. Better results are obtained with larger water dilution and in humid soil.

~r ~ne ii~proved results oE soil condi~ionillg olrtaine~ with ~le grat polymers according to the present invention were substantiated both in laboratory and in ield ~ests, and muc]l better results as regards the s~ability oF ag~regates than those ob-tained with a l~nowll acryllc polymer ~manu~actured and marlceted by ~lollsanto ullder the Trade ;~iark of '~7~ryli~lm') ~ere ac.~ieved. [t ~as founcl that the beneEicial e~fec-t oE the ne~ soil conditioners on aggrc~ate fc)r~l~ation appc-~ars evcn with a v~ry l~w -~)ercentage of soil con~itioner produced according to the ~7resent inveiltion.

I~igule 1 illustrates in grapllic for~n t}~e percelltage of s-~able aggregates 10 largcr ~ all 0.1 mm (by wet sieving) in a loess type soil obtailled, as a functioll of tl-c ~ercentage (by wt) of conditioner used. For comparison, correspondillg tests were perormed l~ith crude lignosulIollate - given in Gra~ll 1 - and witll the sa~e "Kryliu~i' given in Grapll 2. rhe im~roved resultsof the nes~ soil conditioner are self-evident. l~hereas witll an amou~lt of 15 0.05O by wt li~nosulonate or Kryliun~, the stable aggregates were 37~ ancl ~13~ respectively, the stablc aggrega`tes were 67% and 72% (Graphs 3~
Wliell USillg the same amouilt of conditioner ~reparecl accorliing to the present invention. In Graph 3 the soil conditioner conslsts oE a graE-t polymer oE
0.5 part metllyl acrylate~ 0.5 part acryloilitrile and 1 part lignosulfonate 20 15o(l~y w~) w]~ile in Grapi-l 4 it consists of t'ne same acrylate and acrylonitrile compositions ~ut tlle lignosulfollate was of a 25~ ~7~y wk) concentration.
The new Ograft polymers obtained according to tlle present invention ]~ave also various ot}ler uses such as: animal-feed pelletizersJ leather tamling~ cement products, industrial cleaners~ sequestering agents oE metallic ions e~c.

2S A good illustration of the various effects obtained by *lle soil conditioners according to the present invention can be presentecl by sedimentation tests carried out on different soils. An amount of ground soil was added to water resulting in a suspension of lS0 mls. To the suspension obtained, an amount of 100 mls of a solution oE soil conditioner 3~ was added, thus resultinO in a total slurry of 250 mls of suspended soil.
rl~e sedimelltation tests measurements were done according to the settling o the suspension and the relatively clear water layer forllled at the top.
~le readings given in the Eollowing Ta7.~1es are in ~m o~ the settling material Erom its 7~ottom to the settling level.

~ .

T~BL~ 1.

Us~ of tlle soil condi tioner prep.lred in ~,~amt~le 4 with a calcareous clayish soil ~ _ _ ~ _ _ . _ ~. _ _ _ _ _ _ _ .. . .. _ _ l~t concellt-l`,l~iOll o Fillal ~0 ne~ soil soil condi- Re;lding of sedimen~s readiil~ sedin~ent tiont3~ in at di:~:E2rent times af-te:r 18 iormed ~ L;l~ltes) w ___ ~ __ _ _ llrs.
Cil~ SOll O ~ 1.0 1.5 2.03.0~.0 5.0 :L0 ~..~

5.() 2~ 210 1~-~ 157 1~011094 S5 ~ 50 2S.`2 2.~ 250 210 :L7~ 14812~ 0 89 ~3 68 52 33.
1.0 250 212 17S 1~8 12~10292 ~5 6~ 50 2S.2 0~75 25Q 214 1~2 15~ 1301059~ 86 70 ~9 25.~
0.5 250 ?22 1~5 172 lS2119102. 92 72 ~7 20.5 0.2~ 250 226 206 ~ 1701~3122 105 74 ~5 15.4 ~).1 25~ ~2 21~ 20~ lgS162142 125 77 ~3 10.

rnus adding a 2~ solution of the soil conditioner caused an increase of 33.3% in`volume of the soil~ with a corresponding increased porosity~ and produced a better germination and ~rowtn in crop thAn tht-3 untreated soil.
~ach soil ~Yill requi~e a different optimal a~nount o:E soil condi~ioner in order to achieve the hi~hest sediment. ~\t lower concentrations of the soil conditioner, the flocc~llation effect will be more enhanced~ tne veloci~y of se~tt1ing tle~ending on the size of agrgregates and their bu1k den~ity.

Tl~e soil conditioner prepared accordilig to ~xample ~ was also tested ~ith a standard kao1in soil. ~le set~ling measure~nents are given in ~lle ollowing Table 2:

T~`~'., LL 2 .

!~e of -~h" soil conditioner prepclred in 'L~xan~31e 4 ~;i-th a. standard lia.olin soil _ _ _ _ _ _ _ _ _ .. _ _, _ _ _ _ ~ _ _ _ _ _ .. _ _ _ _ ~ . _ . _ _ . . _ _ _ . ,. _ . _ _ _ . . . _ .
~it, COllCen- Fillal '`o lleW
~rat:~on o.i soil COI~d - l~adings c~f seclil~leuts at read- sedi-: it.iouer in differe~t times lc~r ment 0/~() oL ~ mi~ tes) L' hrs. forl,led () l).s1.0 1.~ 2.0 3.~ ~.0 5.010.0 . . .. . _., .. _. .... _ .. _.. ._ ._ .. . _ ..... _ . . .. ~ .. ~.. __.. _. , ~ . _.~_ .. , .. .. _ . ___ _ ___ _. _ _ _ 2 . () ~50 170102 73 63 52 47 ~3 36 2635.S
1.~) 25~) LGO92 71 62 53 48 45 38 2742.1 ~).7~ l7()')S 76 67 56 51 ~7 39 ~ 47.4 ~ llO ~1 7() 5~ S3 ~9 40 ~74~.1 l).'5 250 204150 10~ ~4 G~ 61 55 44 2636.~
).:l 250 21~ 0 :L~6 116 80 66 60 ~5 2~ .3 ~0 2S0250 250 250 250 2S0 250 2~0 19 Thus adding 0.75/oo of the soil conditioner caused an increase of 47.4'`~ in volun~e of tlle soil witll a corresponding increasecL porosity alld bettcr g~er~ latioll-tllan the ~mtreated soil.

Tl~e. same svil conditioner prepared in ~xample 4, was tested with a loess ty~)e soil, and the settling measurements obtained are given in the ollol~ing Table 3:

.~

;8~

TABL~ ~.
__ _._ Use of the soil condi*ioner prepared ~n ~xar,~le 4 with a loess t~e soil.

I~it concen- ~inal % ne~
tratioll o~ read- soll soil cond- lng sedi-it.ioller in Readings of sediments at afte-r ment ()/0(~ 0:~ di:Efe-rent times lS hrs. :formecl tlle soil ~in nulu~tes~
0 0.~ 1.01.52.0 3.0 ~.0 5.010.() %
. ~
1.00 ~50 16~ 107S3 74 67 ~5 6~ 63 62 1~.2 0.75 250 166 107S3 74 S7 65 64 63 62 1~.2 0.50 250 170 10~83 7~ 67 65 6~ 61 60 lS.
~ 5 250 16~ 105~0 72 64 61 60 59 5S 11.5 0.10 250 1~(~ 112S7 7~ 64 ~0 5~ 56 55.5 6.7 0 250 250 2502502~() 250 250 150 220 52.0 0 llere again i~ was found that the adclition of 0.75~oo of the soil conditioner caus~d an increase of 19.2% in volume o~ ~he soil wi~ll a corresponding incrcascd porosity, and procluced a better ge.rmination ancl growth in crop than the ~m-treated soil.

The soil conditioner Rrepared as in ~xample S was tested with a ~aolin soil and the settling measureDIents obtained are gi~en in the ollowing Table 4:

~1 1~
T~
___ Ijs~ o:~ ~he soil condi~iuner -~re?ared in ~xample 5 with a kaolln so:il _ _ _ _ _ _ . _ .

I~'t COllCel~- fillal "~i ile~
~tl;ltion o~ cli~feten~ t.-in~es reac!- scdi-Lt.iOl~el ~Ln ~ after mel~-t ()/(~() o~' ~LII liUllUteSJ lS h1`5~ :FOrmed 0 0~5l.0 1.5 2 ~ 3.() ~.() 5.010.~ - -2.~ 250 '02lsa 112 S5 64 56 51 3g 22 15.S
.l.0 2;;~l:L'.~ 2 96 76 62 55 50 40 24 26.3 0.75 250 19S143 '~ 7~ 64 56 52 4:1 ~4.5 28.9 o. r~ 250 20~15~ 112 S5 6~ 59 54 42 2ci 26.3 ~ 25~ 21217~ 0 110 7S 66 58 ~c~ 23.5 23.7 O.l 250 22~190 154 t36 '~)3 71 ~2 46 ~2 15.~' ~) 2~0 250~50 250 250 250 250 250240 1'~

Th~ the addition of 0.75/oo o ~lle soil condi~ioller caused an increase o 2S.9% in volume of t}~e soil witll a corresponding increased ~oroslty, ancl produced a better germination and growth i.n crop -than the untreated soil.

S ~no~her illus-trati.on o-f -the bene:ficial effects of the soil condition~rs according -to the present invention, can be presented by thc ~reventioll of wind erosion. Thus for exarmple an amount of 3 g of the soil conclitioller ~prepared as in E ~Im~le 4) sprayed on to s~ncly areas ~ith 200 ~o 1000 mls o wa.~er ~er squarc me~er, pro~idccl p-ro~ect.i~n IQ a~ainst ~in~l erosion about one month after seedling of carrots.
It also ill~roved tiheir germinatioll by about 25%.

~X; , .

- - . - : : ~ . :

8~;

A sin,ilar test carried out ~ith a loess .ype soil utilizin~ 5 ~/sq.
r.leter of tlle so:il conditioner ~?reparec1 as in ~xample 4~ improved ~el~1ina~ion of carrots ~ h a~out 20o. ~un-o:Ff of irrigati.on 1~atcr c~ue to crust for]nation 1Yas practically preve1lted ~ to a total of 200 ~n rain.

1~.ind tunnel field tests on v~rious wind veloc:ities ~er~ carried out 1~it11 several soils fron1 nortilern Jordan Valley (Israel) until iltcipient erosion was noticed. '~e soil condition was applie(1 at. a rat~
o 5 g per s~uare meter in 500 1nls of ~ater. ~he results obtaine~ were l~ 1neasured l5 cm a~ove tlle soil aTlCI are given in the following Table 5:

rAsL~ 5.
Soil type P~a~ ~iarle soil Peat Peat Peat Peat soil ~Lacustrine) soil soil soil. soil (~lulla Lake3~Hulla Lake)(Hulla Lake) ~ (1 V~locity 1.5 in kn~ r, ~.it1~
treatec1 soil 60 85 55 55 50 55 1~1ind velocity in km/hr, with untreated soil ~8 35 30 3~ 36 36 ~e results show evidently the ~eneit of the treated soil with the soil conditioner accordi.ng to t1le present invention. ~or exan1ple ~hereas wit1~ a lacustrine soil only at a veloc~ity of S5 1~m/1~r. incipient erosion ~as noticed f.or a treated soil, the same incipient erosion wi~ an untreated soil was alreacly observed at a velocity of 35 km/hr. only.

In order further and more fully to illustrate the nature of ~his invention and the manner of practising it, the following ~xamples are ~rcsented fol~ clearness of ~mderstanding only, and no limitation should ~0 ~e ~u1derstood therefrom. The ~qmounts u5sd are expressed in parts by ~ei,~ht ~u1less othe~ise s-tated.

: . - ' , , ~ .:
. ~

s~

7~ e 100 par-ts of crude lignosulfonate (containillg polysaccharide~ as o~ained ~rom t~le paper industry) ~ere introduced into ?, reactor ~provi~lecl Witil a stirrer~ a thermollle~er, and a condenser) -tog~tller with 300 -~a~ts S of tap water. Subse~uentLy, ~l2 parts of vinyl cya~ no~n l.ulder tl~e naire o-f acrylonitril~) were ad~ l ind the mixtllre heated to about 5~ C.
lllen 2 parts of hydrogell pero~ide (lO~ by vollu~.le) were iddec! and all e~otl~ermic reaction sla.s observed. Tlle reaction was kept gOillg at 7~ G
or a :~ew minlltes. T~e product obta.ined was hydrolysed to an ex~ent of 50O by heatlng for two llours a.t SS - 90C with 10S ~arts o:f i'!aO~ solution ~30`O by sit.). Tlle end procluct in the foTm o:E a brolm co:Lloidal solution as foluld -to be a good soil conditioner ~ilen appli.ed in a concen~ratio of 0.1~o by ~eigiht to a clayey soil resulting in ~G.4So of wclter stal)le aguregates (larger than 0.1 llUll).

In this ~xan~le ~no par-t.s o ihe same a~ueous solution of crude lignosul.ollate~ as that used in ~xample 1, were graft polymeri~ed first witll 25 parts of methyl acrylate and subsequelltly witll 75 parts of vinyl cyanide. The conditions of polymerization were the same as in ~.xample :L.
The yroduct obtained s~as follnd to be a goocl soil conditioner~ applied in a concentration of 0.1% by weig]lt to a c:Layey soil, it gave 5~O of stal)le aggregates ~larger than 0.1 mm). The same product a:~er complete hydrol.isation Wit}l NaO~I ~as in ~xample 1) yielded a soil conditioner s~hich gave 7~.1% s~able aggregates (larger than 0.1 mm) when appl.ied at the same concentration o 0 1% by wt of the soil.

~xaDl~le 3 ~ he experiment ~as simi.lar to that described .in Example 1 but instead of 42 parts vinyl cyanide (acrylonitrile~ 50 parts of methyl acrylate and 50 parts of vinyl cyanide were introduced together fo:r the graft poly!nerization s~ith tlse crude lignosulfoncLte solution. The produc~ ob~ained ~i .

35~

.~EIS comp1ete1~ hyCirG1iseCI ~.'i th ~EIOil as in L~nple l anc! teste~l a~ ,~ soil COnCIitiOIIer. Tl1Q fO11Ol~Jillg staLle aggregates (by wt sieviilg lar~er th~n û. 1 1.Ur) ~ere obtained at variolIs amo~ts of soil conclitioners:

O . 05J i)Y w-t 0. 075O bY W~C O .1~o by ~t of Soil of soil of soil .~
~tai-lc aggrcg.Ites 65 . 5 69 . O 71 . S

le 4 . _. . ~ _ e e~erililent ns in ~ample 3 was reyeated ~Yith the sa~e amo~nts but tlle gr.lft polymerization ~-as perormed wi~h 50 parts o~ me~hyl acrylate - followccl by 50 parts o vinyl cyanide. The product obtailled ~as divided t:\~o ~atchcs, tlle first being hydrolysed to Em extent of 50% (50O of ~t~e estels I~rollps) ancl thc second completely hydrolysed. Tlle elld prod~Icts~iere tostecI as soil con~itioners and the results~ e,cpressed as a percentage t5 o stahle a~gregates obtailled were ElS follows:

Stable Aggregates by wet sieving ~larger than O.l IIUll) 0.05~0 by IYt 0.075% by ~t O~1~J by wt oE soil o soil o soil . . , .. .. . , .. ~ .. ~
50O IlydrolysedNo~ det~rminedNot determinecl 70.6 l()()"o Ilyclrolys~<I 65.8 71.5 77.8 }~ 1 c~ 5 _ . _ 150 parts o~ crude li~nos~llonate were introcluced into a reactor as ;n ~xE~Dple 1, together wi~ 50 parts of t.~p water. ~fter adjus~ing the ~II to about 3.5 Wit]l the aid o Na~ 30% by wt.), 20 parts o Imhyclrolysed vinyl acetate alld S0 parts of ~ethyl acrylate were adcLed together and the ~olymerization pcrformed in an at~nosp]lere of ni~rogen. The results expressed ~0 as percentages of stable aggregates obtailled in a clayey soil using -the re~ulting graft poly~er wers as ollows:

Stable Aggre~tes by wet sieving (larger tll~n Q.1 mm) O. 1o l~y ~t of soil Ih~llydro1ysed 62.7 50~0 hydro1ysecl 61.2 lOO`'o llydro1ysecl 69.2 lc fi rile e,Yperimellt as in Ixcamp1e 1 was repeated using the sa~ne amoullt oE cxude 1igllosu1fon.1te a~d ~ap wat~r. Su'~setlur-~ntly 50 p~rts of acrylic acicl were addecl cand po1ymeri~ecl. 'Mlis was ~ollowed by an acldi-ticnal ~() parts of vinyl cyanide ancl po1ymerized. The Imhydrolysed p~ocluct obtnined, was tested fc~r soil caggregates orlllation (wet sieving larger t~an ~.1 r,lm) al-cl Eo~tlld to ~ive 5~.9'0 st~1e aggreC~ates whell app1ied a~ 0.1~u by ~t oE
l!i tl~o soil.

T:xt~ple 7 100 parts of crude 1ignosu1~onate were introducod in~o a reactor (provided witll a stirrer~ a t]lerr~lorlleter and a condenser) togeth&r with lS0par-ts of tap water. I~fter tlr~lt S0 parts of me~lly1 acrylate and 50 parts o styrene were introducecl illtO the reactor ancl-the mixture heated -to about 50C. Tl~en ~ parts o~ hydrogen peroxicle (10~o `by vol~me) were added and an exotllermic reaction was observed. In order to assure tile co]n~)lete cons~nption of the monomerJ the mixture was heated at 95 - 96C for ten minutes. The product ob-tainr-~d appeared as a mill~y dispersion. AFter 2S llyclrolysis t50~o of the es~ers groups) the produc~ was ~ound to ~e usecul for surace stabi1ization of sand a~aillst wind erosion.

^,~

.

Claims (12)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for producing a soil conditioner which comprises graft polymerizing a vinyl monomer selected from the group consisting of vinyl benzene (styrene), vinyl cyanide (acrylonitrile), vinyl acetate, hydrolysed vinyl acetate, vinyl pyridine, vinyl chloride and di-vinyl butadiene or combinations thereof with crude lignosulfon-ate in the presence of an initiator, the polymerization being carried out at a weight ratio of vinyl monomer to lignosulfonate in the range of 1:0.8 to 1:8 and a pH at the beginning of the reaction of between 2 and 6.

2. A process in accordance with Claim 1, wherein the lignosulfonate utilized is substantially free of polysaccharides.

3. A process in accordance with Claim 1, wherein the graft polymerization of the crude lignosulfonate is carried out simultaneously with two or more vinylic monomers.

4. A process in accordance with Claim 3, wherein the graft polymerization of the crude lignosulfonate is carried out with a vinylic monomer and an acrylic monomer.

5. A process in accordance with Claim 3, wherein the graft polymerization of the crude lignosulfonate is carried out first with one monomer followed by a graft polymerization with another monomer.

6. A process in accordance with Claim 1, wherein the initiator used is of the peroxide type.

7. A process in accordance with Claim 6, wherein the peroxide used is selected from the group consisting of cumene hydroperoxide and hydrogen peroxide.

8. A process in accordance with Claim 1, wherein the soil conditioner obtained is subsequently partially or totally alkaline hydrolised.

9. A process in accordance with Claim 8, wherein the alkaline hydrolysis is performed with an aqueous solution of NaOH, KOH, Ca(OH)2 or NH4OH.

10. A soil conditioner which comprises a graft polymer which is the reaction product of a vinyl monomer selected from the group consisting of vinyl benzene (styrene), vinyl cyanide (acrylonitrile), vinyl acetate, hydrolysed vinyl acetate, vinyl pyridine, vinyl chloride and di-vinyl butadiene or combinations thereof with crude lignosulfonate in the presence of an initiator, in a weight ratio of vinylic monomer to lignosulfonate in the range of 1:0.8 to 1:8.

11. A soil conditioner according to Claim 10 in the form of a powder.

12. A method for improving the structure of soil which comprises applying to the soil a graft polymer as defined in Claim 10.