FR2460970A1 - POLYELECTROLYTES POLYMERES - Google Patents

Abstract

THE INVENTION RELATES TO A POLYMER FOR USE AS A WATER ABSORBING AGENT. THE POLYMER PREFERABLY CONTAINS THE REACTION PRODUCT OF AN OLEFINICALLY UNSATURATED CARBOXYLIC ACID, AN ALKYL ACRYLATE AND MINOR QUANTITIES OF A CROSSLINKING AGENT. THE SAID POLYMERS ARE FOR USE IN LAUNDRY OR OTHER MANUFACTURED PRODUCTS WHICH MUST ABSORB WATER. THEY CAN ALSO BE USED TO MODIFY THE SOILS AND PROMOTE PLANT GROWTH.

Description

The present invention relates to the preparation of

  polymers, and more specifically of solid polymers,

  in water and insoluble in water, which are used in

in absorbent articles.

  Various systems have been proposed for producing water-swellable and water-insoluble polymeric materials. In these processes, these materials are prepared from

  of polymers containing carboxyl groups, by polymerisation

  monomers of carboxylic acids in the presence of a

  gent of crosslinking; these monomers include acrylic acid

  lique, maleic acid, maleic anhydride and the like.

  Among these linear carboxylate polymers,

  copolymers of acrylic acid-acrylate, copolymers of

  acrylic acrylamide, copolymers of acrylic acid,

  olefin. US Patent 3,980,663 describes the production of such polymers by reaction of a water-soluble polyelectrolyte

  low molecular weight that contains carboxyl ions

  ophiles, with a crosslinking agent comprising at least two sites which undergo a nucleophilic attack on the part of

  carboxylate groups. The process is illustrated by the reaction

  in an aqueous solution of a sodium salt from a copo-

  acrylic acid-methyl acrylate (prepared by Ad-

  addition of sodium hydroxide to a latex of the copolymer)

  diglycidyl ether of glycerine. The resulting product is cast into a film and cured for one hour in

an oven.

  These process and product, however, have various

  disadvantages. The crosslinking reaction is slow, requiring large special dryers to provide the residence time necessary for the polymerization. In addition, the crosslinking is obtained by forming diester bridges between the chains of

  linear polymers. Such links are subject to

  drolysis, and therefore results in degradation of the polymer.

  Another disadvantage of the process according to said patent lies

  in the preparation of a film that only a grinding can trans-

  form into a particulate material. This results in a product that has a low surface-to-weight ratio inherent in a film, which results in slow water absorption and

  tendency of the swollen surface of the film to block penetration

  water during an absorption test. This is how the heart of the film contributes little, or not even

  at all, to its ability to swell.

  Other polymer systems have been proposed, with the basic intention of obtaining or forming an inflatable and insoluble material in water, and capable of absorbing

  large quantities of water without disintegrating or dissolving

  dre. In an article entitled "Mechanism of Alkali Thickening of Emulsion Polymers Containing an Acid", Journal of Applied Polymer Science 14, 897-928 (1970),

  Verbrugge has observed that latexes containing an acid

  all during the neutralization a common process of

  swelling leading to complete solubilization for the

  most hydrophilic polymers. Verbrugge has described specific neutralization reactions in a series of polymers of

  various glass transition temperatures Tg and

  different hydrophilic substances corresponding to the general formula

  methyl methacrylate / ethyl acrylate / methacrylic acid

  that (MMA / EA / MAA) containing 20 mole percent MAA and MMA / EA ratios ranging from 50/0 to 0/80. In the microscope, we have

  observed both viscosity changes and changes in

  visual elements. The study also concerns a most hydrophilic range of monomers, for example by using

  EA / MAA high, such as 80/20 and 70/30, without MMA. The half

  croscope reveals progressive swelling of the particles at

  as the neutralization of the carboxylic acid groups

  xylique. At 80% neutralization, the particles appear so swollen that it is practically impossible to distinguish between solid and liquid phases. A 90 and

  % of neutralization, the particles have disappeared and it is

  is formed a real solution. The latex particles of

  which are less hydrophilic, for example those observed

  at high levels of MMA and lower levels of EA and MAA, eg 60/20/20 of MMA / EA / MAA, give viscous gels at neutralization and appear under the microscope as unbounded swollen gel particles. very clear

  between the swollen particle and the solution. Under a microscope

  In the electron, 100% neutralized and dry latex particles show numerous tentacles projecting from the central nucleus, which results in agglomeration or joining or sticking of the particles together and consequently by a high viscosity. Verbrugge then described the preparation of 4 polymers of EA / MAA which are highly crosslinked with ethylenebis dimethacrylate at a rate of 15 and 30%. The MAA content is 20 and 30%. Latex

  prepared with a crosslinking of 15%

  have reached a viscosity higher than that

  the obtained for the uncrosslinked polymer. The cross-linked material

  at 30%, because of its extremely high cross-linking density

  high, showed neither swelling nor viscosity.

  The present invention relates to improvements to known water-swellable, water-insoluble polymers which, in their most general form, combine

  short chain specific monomers with half

  neurons of a crosslinking agent during polymerization.

  The resulting polymer, when neutralized, gives a

  absorbent product which, when inflated, forms microspheres

  gelled resins giving a feeling of "dry" to the touch. This-

  the property associated with the retention of the absorbed fluids,

  unusual for absorbents, renders the absorbent according to the

  an essential importance for all articles

  requiring absorbency and, for example, in

  such as surgical and dental sponges,

  catamenials, diapers, meat trays, ser-

  paper napkins and mattresses or bedding mattresses for

small pets.

  Unexpectedly, a polymer according to the invention has been found which comprises:

  (a) from about 15 to about 50% by weight of a carboxylic acid

olefinically unsaturated;

  (b) from about 49.07% to about 82% by weight of an acrylate of

  alkyl groups in which the alkyl group has from 1 to 4 carbon atoms.

bone; and

  (c) from about 0.03 to about 3.0% by weight of a

  reticulation. All quantities indicated are by weight

  relative to the total weight of the constituents of the polymer.

  The invention also relates to an alkaline salt and an organic amine salt of the polymer defined above, which materials are useful as water-absorbing agents. As examples of alkaline salts, mention may be made of sodium salts,

  potassium, lithium and ammonium. The amine salts

  can be selected from trimethylammonium salts.

  and triethanolamine salts.

  In the production of the polymers according to the invention, a

  monomer mixture which contains an unsaturated carboxylic acid

  olein content and an alkyl acrylate, is polymerized in

  the presence of minor amounts of a vinyl crosslinking agent

  than. Crosslinking is achieved by introducing the groups

  vinyl of the crosslinking agent directly into the skeleton

  the carbon-carbon of the polymer. If resistance to degrading

  In the long term it is necessary to use hydrolytically stable crosslinking agents, such as divinyl

  benzene or triallyl cyanurate.

  The olefinically unsaturated carboxylic acids which can be used according to the invention are materials containing an activated carbon-carbon double bond and at least one

  carboxyl group, that is to say an acid containing a

  olefinic bond. Examples of carboxylic acids

  appropriate examples are acrylic acid, methacrylic acid and

  crylique; ethacrylic acid, crotonic acid, muconic acid, aconitic acid and similar compounds, as well as mixtures thereof. Preferred carboxylic acids

  are acrylic acid and methacrylic acid.

  The alkyl acrylates which can be used in the invention are alkyl acrylates in which the alkyl group has from 1 to

  6 carbon atoms and preferably 1 to 4 carbon atoms.

  bone. Examples of suitable acrylates include

  methyl acrylate, ethyl acrylate, propylene acrylate,

  pyle, n-butyl acrylate and isobutyl acrylate.

  Preferred acrylates are methyl acrylate, ethyl acrylate and n-butyl acrylate, of which methyl acrylate is particularly preferred. Longer chain acrylates tend to become hydrophobic, with the final polymer salt showing lower swelling and less water absorption in water and saline solutions.

  Other monomers that do not meet the description

  monomers above, may also be used.

  in minor quantities, ie up to about 8%

  by weight, provided that they do not adversely affect the characteristics

  fundamental and new problems of polymers according to the invention

  tion. For example, acrylamide, 2-ethylhexyl acrylate,

  hydroxyethyl acrylate and hydroxyethyl methacrylate

  can be used to partially replace the acry-

  methylate or ethyl acrylate, and itaconic acid

  that maleic acid or maleic anhydride can be u-

  used to partially replace methacrylic acid or

acrylic acid.

  The crosslinking technique used in the invention

  to convert soluble polymers in water into poly-

  Water-Inflatable Salt Matrices, is well known as free-radical addition polymerization. The agents

  crosslinking agents which can be used according to the invention are monomers

  polyunsaturated polymerizable vinyl resins containing at least

  two ethylenic groups polymerizable by free radicals.

  Virtually any monomer having more than one ethylene chain

  polymerisable can be used if it is capable of

  per vinyl addition polymerization reactions,

  with the acids and acrylates mentioned above. As an example

  examples are: (1) glycols diacrylates and dimethacrylates, such as ethylene glycol dimethacrylate,

  propylene glycol dimethacrylate, the dimethyl

  butylene glycol methacrylate and dimethacrylate

  hexylene glycol; (2) diacrylates and dimethacrylates of ether or

  polyether glycols, such as diacrylate

  thylene glycol, diethylene dimethacrylate

  glycol, triethylene diacrylate or tetracycline

  ethylene glycol and trietylene dimethacrylate or tetraethylene glycol;

  (3) allyl esters of carboxylic acids which are

  polymers such as allyl acrylate

  methacrylate, methacrylate, methacrylate

  lyle, allyl ethacrylate, ethanol acrylate

  lyle, methacrylate methallyl; (4) aromatic di- or trivinyl compounds such as divinyl benzene and trivinyl benzene; (5) di- or triallyl esters of di- and tri-basic acids such as diallyl phthalate, triallyl cyanurate, diallyl maleate,

  diallyl succinate, trial

  lyl, diallyl oxalate, dialkyl malonate,

  lyle, diallyl citrate, dialkyl fumarate

  lyl, diallyl ether; and (6) acrylates or methacrylates of polyols such as di- or triacrylates or methacrylates of trimethylol ethane, trimethylolpropane or pentaerythritol.

  In order to obtain the desired properties for the poly-

  mother, it is important that the monomers be polymerized together in specified proportions, although

  exact proportions may vary depending on the

  desired for the polymer.Carboxylic acids with

  Olefinic saturation according to the invention are used in amounts of between approximately 15 and 50% by weight and preferably between approximately 20 and 40% by weight, relative to the total weight of the monomers used. If the amount of carboxylic acid used exceeds about 50% by weight, the salt of

  resulting polymer becomes excessively hydrophilic and absorbs

  be too much water, leading to (1) a poly-

  soluble mother, (2) a viscous solution or slurry, and (3) a loss of the integrity of the polymer structure. If the amount of carboxylic acid used is less than about%, the resulting polymer salt is insufficiently hydrophilic and exhibits poor water absorption. The alkyl acrylates are used in amounts of about 49.07 to 82% by weight and preferably about

  59.02 to 78% by weight, based on the total weight of the monomers

  used. If the amount of acrylate used exceeds

  Viron 82% by weight, the resulting polymer salt form is insufficiently hydrophilic and shows a low water absorption capacity. If the amount of acrylate used is less than about 49.07%, the resulting polymer becomes too hydrophilic, and absorbs too much water, resulting in (1) a soluble polymer, (2) a solution or a suspension viscous, and (3) loss of the integrity of the

structure of the polymer.

  The amount of crosslinking agent used is preferably limited to about 0.03

  and 3.0% by weight, preferably between 0.08 and 2.0%. This

  amount of crosslinking agent has been found to be sufficient to render the polymer salt insoluble in water, while

  maintaining a high degree of water absorption. The utilisa-

  less than 0.03% of crosslinking agent provides a po-

  lymere which, at neutralization, acts first as an agent

  thickener, not having a discrete identity

  the. If the amount of crosslinking agent exceeds 0.03%, the resulting polymer becomes more discrete and more rigid,

  decreasing the possibility of expansion of the salt particles.

  Water absorption falls to a commercially unacceptable level

  ceptable, if quantities of crosslinking agent are used

greater than 3.0%.

  The preferred polymer is prepared from a

  containing as essential constituents from 20 to 40%

  about 1% by weight of an olefinically unsaturated carboxylic acid

  fin, such as methacrylic acid or acrylic acid; from about 59.02 to about 78 percent by weight of an alkyl acrylate selected

  among methyl acrylate, ethyl acrylate and acrylate

  n-butyl late; and from about 0.08 to 2.0% by weight of a

crosslinking agent.

  The polymeric components must be reacted as completely as possible during the polymerization. The

  polymer can be obtained by polymerization techniques.

  such as solution polymerisation,

  in suspension or emulsion, on a continuous batch, semi-con-

tinu or discontinuous.

  Suspended polymerization is preferred because

  The technique provides an acidic polymeric product in the form of a granular precipitate with a high specific surface area, having a mean particle size of between 50 and 400 microns, which product appears to be composed of accretions of smaller particles, from 10 to 50 microns. A big

  proportion of these smaller particles appear to be

  me "nun farts" with a large surface area

  collapsed my spherical /, with protuberances of 2 to 5 microns on

their surfaces.

  The polymerization reaction is conducted in advance.

  presence of a catalyst. The catalysts that form the radicals

  The free radicals necessary for the reaction are conventional catalysts such as in general organic peroxides, inorganic persulfates and azo compounds which generate

  free radicals. The amount of catalyst used is normally

  miscible from 0.01 to 2.0 parts by weight per 100 parts of the total weight of the monomeric materials

  to react. As representative examples of

  organic oxides, mention may be made of benzoyl peroxide,

  acetyl peroxide, bis (p-bromobenzoyl) peroxide, the

  di-t-butyloxide, t-butyl hydroperoxide, peroxide

  dicumyl hydroxide, cumene hydroperoxide, bis (p-metho-

  xybenzoyl) peroxide, 2,2'-azobisisobutyronitrile and

  very similar. Examples of inorganic persulfates include ammonium, sodium and potassium persulfates. They can be used alone or jointly

  with sodium or potassium bisulphite. Polymerization

  It is preferably carried out with a radia-

  free, but it is also possible to use the

  radiation lymerization, such as polymerization by

  very energetic X or gamma rays.

  During the polymerization reactions, it is also possible

  use commonly used surfactants and / or colloXdes. The times and temperatures of polymerization

  can vary considerably depending on the system of mono-

  mothers and the catalyst used. The polymerization reaction

  tion is usually completed in a period from

  minus 30 minutes to several hours, at

  between about 1000 ° C and preferably between 1 and 4 hours at temperatures of 65 ° C to 90 ° C

maximum efficiency.

  In the preferred embodiment of the invention, the polymerization is conducted as follows. In a reactor, deionized water and a suspending agent are charged and the air is flushed with an inert gas. We

  can possibly heat the reactor to dissolve the

  kind of suspension. Then add separately or together

  pre-determined amounts of carboxylic acid to

  olefinic teating and alkyl acrylate. The addition can 8-

  be carried out at room temperature or at room temperature

  of reaction. The crosslinking agent and the catalyst can

  can be added simultaneously with the monomer mixture,

or separately.

  The contents of the reactor are then agitated by

  conventional way and heated to initiate the polymerization

  at a temperature close to the lowest boiling point

  the monomers. When polymerizing the acrylate

  methyl, this temperature is of the order of 700C. We let

  then the reaction continues to complete the polymer.

  then cooled the contents of the reactor. The pro-

  This polymer can be collected from the suspension by conventional filtration or directly converted into Selsel.

  in the suspension. The suspension of the final product can e-

  be treated with steam at 1000C to remove all traces of unreacted monomers. According to one variant,

  add a highly reactive redox catalyst to obtain essentially

  100% yield. The suspension can then be filtered to collect the polymer in its non-swelling or neutralized acid form, adding to the suspension

  the final quantities of an alkaline solution

  in order to bring the free acid groups to the salt form.

  A variant consists in redispersing the cake of

  polymer separated by filtration and to neutralize it as

  to dry, spray and neutralize with an al-

cali.

  Typically, the solids content of the reaction mixture

  The final level is between 15 and 50%. In addition

  solid contents may be used, but they

  are generally undesirable from an economic point of view.

  The resulting polymer products, in dry form or

  in suspension, can then be put in stock, or used

* directly absorbent, for example by the treatment of

  substrate. The article, which may be a substrate, is for example treated with the acidic polymer which is then

  neutralized with an alkaline solution to form a poly-

  inflatable mother in water, by means of neutralisa-

  tion. It is obvious that for the intended purpose

  by the invention, the processing operation involves

  total persion of the particles on the substrate or a dispersion

  discontinuous The substrates to be treated may be very different depending on the end use, but include fibrous substrates such as wood pulp, refined cellulose, paper, woven or non-woven textile materials.

woven and others.

  Any suitable organic or inorganic base can

  to be used during the neutralization. As examples

  presentational, mention may be made of sodium hydroxide, hydro-

  potassium hydroxide, lithium hydroxide, ammonium hydroxide

  monium, ammonia, and sodium carbonate. Neutrality

  may also be carried out with organic amines

  such as ethanolamine, diethanolamine, triethanolamine,

  thanolamine, methyl diethanolamine, butyl diethanol

  mine, diethyl amine, dimethyl amine, trimethyl amine

  triethylamine, tributyl amine, and the like, and

  their mixtures. The preferred base is sodium hydroxide.

  In summary, any basic material can be used with

  that it is not detrimental to the composition of the polymer

re.

  It is decisive and essential in the process of

  tion, and in particular during the neutralization reaction

  to use the minimum amount of water required for

  conduct a total and unified reaction and neutralization

  forms. It has been found that effective amounts of water

  readable according to the invention are in a weight ratio of 4 to 10: 1, and preferably 5 to 7: 1, for the

  total water / polymer ratio. If an inferior report is used

  at 4: 1, there is a risk that all of the free water will be

  rapidly absorbed during neutralization by a

  Only when the acid polymer is neutralized, leaving little or no water at all, will the remaining neutralizing agent be

  non-neutralized acid polymer. On the other hand, a report

  below 10: 1 translates into excessive energy expenditure.

  during drying to remove the large amount of

  no need for absorbed water.

  To achieve total neutralization, we must

  stoichiometry between the basic equivalents dis-

  bunker in the alkaline neutralization solution and

  carboxylic acid equivalents in the suspension of

  lymère. This is the way to use at least one equiva-

  a base such as sodium hydroxide, by equivalence

  slow of the monomeric half containing the carboxylic acid.

  However, one can use an excess of basic equivalent

  at least 20% to be sure that all the acidic car-

  Boxylic are affected by the neutralization solution.

  In fact, a slight excess is desirable for driving

  action and get the maximum swelling. Excess alkalinity

  This is not harmful, as it reacts to the sapono-

  partially releasing the ester-acrylate segments, in particular

  methyl acrylate, to provide additional units.

  of sodium acrylate monomers in the skeleton

te of the polymer chain.

  The drying of the polymer salt can be carried out by any conventional means such as fluid bed drying, rotary kiln drying, vacuum drying and drying.

  in an oven, at temperatures sufficient to eliminate practically

  the totality of the water associated with the polymer product,

  without resulting in the decomposition of the polymer. Some

  up to 5% of residual absorbed water are

  acceptable. Preferred drying temperatures are

  between 25 and 1500C, and preferably between 80 and 1000C.

  During drying, the polymer salt particles

  re agglomerate forming a friable mass of particles

  solid. This mass can be ground to form

  the discreet ones that are easy to handle and carry. according to

  envisaged end use, it has been found that

  taken between 50 microns and about 2 mm result in a particle that absorbs water quickly and allows water

  to cross a mass of particles already inflated to

  dye the material not yet touched. It should be noted that,

  when the particle size increases, the surface area

  the volume decreases, resulting in lower water absorption and

  swollen particles eventually larger. Likewise, a

  smaller particle size, used "in bulk" tends to absorb water less rapidly than

  large particles because of the decrease in

  pores between particles and the speed of

resulting filtration.

  The polymer product according to the invention has a molecular weight "average weight" undetermined, as a result of its

  crosslinking and its insolubility in the usual solvents.

  used to determine molecular weights. The

  Neutralized polymer is able to absorb water from the am-

  surrounding environment up to a quantity representing several

  several times its own weight. As a result, each individual absorbent particle swells or increases by several

  its individual diameter without destroying the inte-

  particulate matter of the particles. Absorption of distilled water in amounts greater than 100 times the weight of the polymer was observed. In solutions with 1% sodium chloride, weight increases of 30 times were noted, whereas in solutions of sodium chloride between

  and 25%, weight increases of 10 times. This amount of absorption is significant, in particular

  bind when it is known that the polymer immobilizes substantially the same amount in it and that the particulate material

  resulting maintains its structural integrity.

  The water-insoluble, water-swellable polymer according to the invention is preferably used in

  dressings, linens or products of manufacture absorb

  bants, requiring an ability to retain water.

  When used in the foregoing applications

  the polymer material is preferably in solid, granulated form to provide the greatest possible surface area for absorption and to ensure that the

  maximum surface area is available for absorption

  tion. The absorbent articles should contain at least 1% by weight, and possibly up to 90% by weight of the

  relative to the total weight of the absorbent article

composite bant.

  Depending on the specific type of the absorbent article, the polymer salt may be dispersed on a carrier sheet or on a flexible support comprising an absorbent layer of textile fibers, wood pulp fibers, linters

  cotton and the like, and mixtures thereof. These cou-

  absorbent substances may be those that are commonly

  used in the manufacture of dressings or cloths ab-

  sorbents and the aforesaid manufactures, such as surgical and dental sponges, catamenial tampons,

  diapers, meat trays, bedding mate-

  domestic animals, separation devices

  water such as filter cores, and the like.

  These materials may contain several layers of

  the supports or supports, and sheets of coating-

  all types of known types.

  These absorbent articles can be prepared during

  that the polymeric material is incorporated in the dressing

  or other absorbent by conventional methods, which

  sure that the desired particulate polymer is maintained in the final structure. In the case of a catamenial tampon, this can be produced by spreading the particles of

  polymer into a bed on the absorbent fiber layer, then.

  by winding the layer into a roll so that the polymer particles are trapped therein. A treatment

  steaming followed by drying the composite increases the

  particle adhesion to the fibers. The absorbing material

  the resulting bant retains its particulate character

  that it absorbs water. Other known methods for pre-

  paration of these articles may also be used in

the scope of the invention.

  The polymers according to the invention, insoluble in

  water and inflatable in water, can also be used

  as a soil modifying agent to improve

  water retention and increase the aeration capacity. Lors-

  that they are mixed with soils of various compositions

  sand-silt-clay and in particular with high levels of

  sand, there is considerable water retention capacity

  badly improved. This power of high water retention

  is observed even at pressures of 1 to 15 bar.

  The use of polymer salts in soils gives significantly better results than untreated control soils, the effect being most significant in more porous sandy soils. These soils typically lose excessive amounts

  evaporative and drainage water and polymers combat-

  energetically this effect. A concomitant effect of excessive drainage in sandy soils is the loss of nutrients by leaching. The polymers according to the invention also suppress this effect so that the nutrients added to the soil are retained for a longer time. Given the remarkable water retention properties of these polymers, they are particularly suitable for preventing dieback of plants growing in easily drainable sandy soils such as those

  encountered in the arid regions of the globe.They have the advantage

  to allow the survival of plantations during periods of

  periods of drought and are particularly useful for

  grow sod in sand or soil.

  bluish, easily drainable, such as those used

  for golf courses, sports tracks and

  They are also useful in nurseries, greenhouses, private gardens, in artificial soils and for potted plants. The expense and the need for a

  watering and constant monitoring are considerable-

  diminished. In this way, they facilitate irrigation loads by maintaining more water in the plantation layers and reducing the number of irrigations in the fields or watering greenhouses, resulting in an economy of workforce. They also improve marginal lands by increasing retention capacity

  soil, making them more suitable for crop production.

  your. Finally, they are useful for loosening soils that have been compacted by natural or artificial methods such as grassy or bare sidewalks, or parts of the ground

hardened by evaporation.

  They are also useful in transplants o water retention properties and intimate contact between

  root tendrils and gon-

  Water fl oods reduce the shock of transplantation and the loss of subjects. These polymers are also used in seed coatings that provide a water-rich, drought-resistant environment for germination

  and the initial stages of growth.

  When used in soils, the material

  Preferred is the sodium salt of EA / MAA EGDMA or EDMA / 35 / 0.1. Although generally lower than sodium salt

  in terms of water retention properties, potassium salt

  sium has an advantage in providing a nutrient

  tif that is not easily leached and remains available

  for the plant for a prolonged period of growth.

  This is due to the fact that potassium in the form of the complementary ion for the polymer is only slowly released

  compared to the solubilization rate of synthetic fertilizers

  typical soluble ticks containing potassium. The ferti

  potassium and water retention can also

  if optimized using poly-salt mixtures

mothers of sodium and potassium.

  As used herein, the term "soil" refers to any medium in which plants can grow.

  and which provides support for oxygen, water and water.

  nutrients. Examples of such materials include natural development media such as glass beads, organic foam materials such as

  polystyrene or polyurethane foams,

  calcined clay particles, crushed plastics

and others.

  Non-limiting examples of the invention are described below. In these examples, all / parts and all

  the percentages are by weight unless otherwise indicated.

  In the examples, it was used when applied

  the following procedure to determine the absorbency

  water and saline solution. 1 g of sodium salt is added

  lymere at 100 g of a solution of 1% NaCl or 200 g of water

  distilled. Rest is left without stirring for 2 hours.

  The material is filtered through Whatman No. 4 filter paper until no more water is flowing through it (usually at 15 minutes). The swollen product is weighed, the weight of the polymer, i.e. one gram, is subtracted and the result is recorded as the swelling value. The rate of absorption is determined by adding 1 g of the polymer salt in 30 g of distilled water in a small vial. The contents are shaken gently by shaking the flask. We observe and we

  note the time required for the polymer to become

  very solid, that is to say, so that the product does not

  falls more freely when the vial is spilled.

EXAMPLE I

  This example describes a process for the preparation of

  the polymers according to the invention by the preferred method of

lymerization in suspension.

  In a polymerization reactor, 2000 g of deionized water and 3 g of "Cellosize QP-4400" (produced by the company Union Carbide which is a powdered hydroxyethyl cellulose having a viscosity of 4000 to 6000 cps in solution at 2 %) as suspending agent. The contents of the

  reactor at 650C until the hydroxyethyl cellulose is dissolved

lose and cool to 350C.

  In the reactor, a mixture of

  lange containing 325 g of methyl acrylate, 175 g of glacial methacrylic acid, 0.5 g of ethylene dimethacrylate

  glycol as crosslinking agent and 0.5g azobisisobuty-

  ronitrile as a catalyst. We deaerated the content of the re-

  actor by purging with a stream of nitrogen under a flow

  moderate of 100 ml / minute, for example.

  saturated at 70C and allowed the mixture to polymerize

  3 hours. In the last hour, the temperature has been raised

  Re reactor at 800C to complete the reaction. The total duration of the reaction was 3 hours. During the whole

  the duration of the polymerization reaction, the mixture was stirred

naked of the reactor.

  Once the reaction is complete, the mixture is cooled

  binds or suspends in the reactor at 250 ° C and the suspension is filtered through a vacuum filter. The filter cake weighed 1000 grams. To analyze the product and determine the yield, one fifth of the weight of the filter cake was dried for 16 hours in a vacuum oven at 800 ° C. and milled to an average particle size of 0 ° C. , 42 mm to prepare a granular acidic polymer containing about 34 to 35% methacrylic acid. The conversion percentage of the monomers into

polymer product reached 97.0%.

  The remainder of the filter cake was neutralized with

  basic solution of sodium hydroxide by dispersing

  each fifth of the remaining cake in 400 g of water

  ionized, then adding 195 g of a 10% sodium hydroxide solution (for example an excess of 20% over the theoretical amount necessary to neutralize the polymer). The resulting masses were dried at 80 ° C in a vacuum oven to remove the water contained therein.

  and grinded up to a sieve having an opening

mesh size 0.84 mm.

  Absorbance (absorption capacity) was determined

  saline solution with the polymer salt in a solution of

  1% sodium chloride. The filter cake weighed 24g, which corresponded to a water absorption of 23 times its own weight. In the water absorbance test, a water absorption corresponding to about 100 times was obtained

the weight of the polymer.

EXAMPLES 2 to 17

  In Examples 2 to 17, polymers were prepared according to the suspension polymerization example of Example 1; different weight ratios of acrylates of

  methyl (MA), methacrylic acid (MAA) and dimethacrylate

  ethylene glycol (EDMA or EGDMA) as a crosslinking agent

  in the quantities indicated in Table 1. We have

  neutralized the polymers of Examples 2 to 12 according to the procedure

  dice of Example 1, with the difference that we used a

  lithium hydroxide solution instead of a solution of hy-

  sodium droxide. The procedure of the former

  Example 1 to neutralize the acidic polymers of the examples

13 to 17.

  In Table I, the absorption capacity (absorbency)

  ce) alkaline polymers is expressed in multiples of the dry weight of the polymer. Absorbance values are shown for deionized water, 15% calcium chloride solution and 15% sodium chloride solution. To facilitate

  calculations, the indicated quantities of the crosslinking agent

  are the quantities of material added to the other two

monomers used.

  The results clearly indicate that the polymers according to the invention have a high absorbance vis-à-vis

  water and saline solutions over a wide range of

  monomer and crosslinking agent treatments. The data

  also show that water absorption decreases

  that the level of crosslinking agent increases. Products

  obtained with an absorbed water content of approximately 95%

  consisted of rigid inflated particles

  serving a stuctural integrity, and dry to the touch. For

  higher water absorption rates, particulate matter

  flairs were slightly softer but remained

  the form of discrete and non-agglomerated particles, half

dry to the touch.

EXAMPLES 18 to 24

  Examples 18 to 24 give the preparation of poly-

  according to the procedure of Example 1, with

  different weight ratios of the various monomers.

  The polymers of Examples 18, 20 and 21 were neutralized

  according to Example 1, with the difference that one has used a

  lithium hydroxide solution instead of a solution of hy-

  sodium droxide. Examples 19 and 22 to 24 were neutralized

  according to the method of neutralization of Example 1 in use

  reading a solution of sodium hydroxide. The quantities of

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TABLE I

  Water Absorption Multiple dry weight CaC12 at 15% NaCl at. 15%

8.1 10.9

  , 5 6.2 7.7 9.1 8.6 In this table: = methyl acrylate = methacrylic acid = ethylene glycol dimethacrylate

Example

  MA EDMA 0.1 MAA 0.5 0.3 0.1 0.05 6.3 7.8, 1 13.0 MA MAA EDMA 13.0 W O Cr os c>% O (cont.) Polymeric constituents used and test results

  of absorbance are shown in Table II. For ease

  In the calculations, the amounts indicated for the crosslinking agent represent the amount of material added to the other two monomers used. The results indicate that acrylic acid

  gives results roughly equivalent to metha-

  crylic as to swelling in water. For swelling

  in the presence of high concentrations of electrolyte, the

  Methacrylic acid is preferred. The results indicate that

  all the polymers tested are sensitive to concentrations

  CaCl 2 and NaCl, but the polymers

  still have a high degree of absorbency by

  structural integrity. Example 24 also shows the

  of a polymer of which a part of the carboxylic acid monomer is replaced by a minor amount of a

other acid monomer.

  EXAMPLES 25 and 26 In Examples 25 and 26,

  polymers prepared according to the method of polymerization

  Board of Example 1 with different weight ratios of monomers and crosslinking agents. Acidic polymers were neutralized with basic solutions prepared from lithium hydroxide, sodium hydroxide,

  of potassium hydroxide and triethanolamine. The mono-

  mothers used were methyl acrylate (MA), acid

  methacrylic acid (MAA), and ethylene glycol dimethacrylate

  col (EDMA). The amounts of monomers used and the results are shown in Table III. The amount of crosslinking agent represents the amount added to both

other monomers used.

  The results show the effect of the different neutralizing agents on the resulting polymer salt product. The results show that sodium polymers

  and lithium have substantially equal water absorption.

  the, although the lithium compound gives results

TABLE II

Example Monomer of acid

carboxy

  MAA MAA AA AA AA MAA

, 8 MAA

  Alkyl acrylate monomer (parts) 8OEA EA MY MA MA MA MA Agent

crosslinking

tion (parts)

2 EDMA

0.1 EDMA

1 EDMA

0.5 EDMA

0.1 EDMA

0.1 EDMA

0, 1 EDMA

  Multiples Water ND ND ND NA NaCl 1% ND ND ND Dry Weight Absorption NaCl at% ND ND ND 2,3 ND ND ND +, 8 M In this table: MAA = methacrylic acid AA = acrylic acid M = acid maleic acid EA = ethyl acrylate MA BA EDMA ND = methyl acrylate = butyl acrylate = ethylene glycol dimethacrylate = not determined CaCl 2 at% i 0.8 ND 2.6 1, 5 ND ND NA a ba tu co. higher levels in electrolyte solutions. The potassium polymer shows lower swelling although it is used especially in agriculture because of its potential nutritional value. Triethanolamine salts have an even lower absorption capacity, but quite

  usable in cosmetic applications.

TABLE III

  Absorption Example MA MAA EDMA Multiples dry weight Salt Water CaCl2 at 3, 5% 80 20 2 Li il 3.2 Na 12.4 2

K 9 1.8

TEA 5 1,3

26 80 20 1 Na 16 2.3 Li 18 3.2

EXAMPLES 27 to 40

  These examples show the influence of variations

  the amount of polymeric constituents in the preparation of

  Inflatable polymers in water, insoluble in water. The procedure was as in Example 1 to prepare the salt

  of sodium polymers. The quantities of monomers used

  and the results are shown in Table IV.

  A simple acrylate system has been studied.

  methyl, methacrylic acid and ethyl dimethacrylate

  glycol (MA / MAA / EDMA) over a range of AD concentrations of 50 to 80, MAA of 20 to 50 and EDMA of 0.03 to

  0.3. The results indicate that for each

  culation, maximum swelling is achieved in a

  1% NaCl with polymers containing approximately 40% MAA. Polymer particles that gave swollen particles with the greatest structural integrity corresponded to an MAA concentration range of about 20 to 40%. Beyond 50% in MAA and in one

  concentration range from 0.3 to 0.03 as crosslinking agent

  The structural integrity of the swollen particles was lost. The structural integrity was also degraded to less than 0.03% crosslinking agent, under conditions such that the neutralized polymer in the water gave poorly defined, non-filterable articules that it was not

  possible to distinguish suspensions or solutions visually

  its jellified of the prior art.

TABLE IV

  1% NaCl Absorption Examples MA MAA EDMA Multiple dry weight

27 80 20 0.3 5

28 75 25 0.3 8.5

29 65 35 0.3 8.7

50 50 0.3 8.7

31 75 25 0.1 17

32 65 35 0.1 20.5

33 60 40 0.1 20

34 50 50 0.1 17.5

75 25 0.05 18

36 70 30 0.05 24

37 50 50 0.05 25

38 80 20 0.03 17

39 65 35 0.03 32.5

40 50 50 0.03 26.5

  MA = methyl acrylate MAA = methacrylic acid

  EDMA = ethylene glycol dimethacrylate.

EXAMPLES 41 to 46

  In Examples 41 to 46, polymers according to Example 1 were prepared using methyl acrylate and methacrylic acid with various amounts of different crosslinking agents. The results are shown in Table V. The results indicate that the polymer prepared from diethylene glycol dimethacrylate at 0.1 and 0.05% gives 25 and 34 fold swelling ratios, respectively, in NaCl. 1%. This is the rate of

  lower crosslinking gives the polymer the easiest

  hydratable and expandable. The lower limit used

  sand is, however, 0.03%, because beyond this value,

  the particles no longer expand to an absorption rate

  equilibrium o the swollen particles maintain their structural integrity, but rather absorb so much water that this structural integrity is lost. In the

  In the latter case, the particles become very soft,

  together and eventually give a viscous gel or even a viscous polymer solution. Going beyond the

  diethylene glycol dimethacrylate, gly-

  such as tetraethylene glycol under

  of its dimethacrylate derivative, to increase the

  hydrophilic material of the crosslinking unit. Allyl methacrylate is an example of a crosslinking agent where a vinyl group is in the alkyl group of an acrylate and

  the second in the carboxylate group, ie the group

  eg methacrylate. Divinyl benzene is an example of a

  hydrocarbon crosslinking agent not containing a group

  hydrolysable esters and, accordingly, the resulting polymer is structurally supplemented by

  carbon-carbon resistant to hydrolysis, on all its sque-

  lette and its crosslinking bridges.

BOARD

  NaCl Absorption Example MA MAA 1% X Bond X Multi Dry Weight Agent 41 65 Diethylene glycol Dimethacrylate 0.1% 42 65 35 Diethylene glycol Dimethacrylate 0.05% 43 65 35 Trimethacrylate 23.5 0.1% Trimethylolpropane methacrylate 44 65 35 0.1% allyl methacrylate 45 65 35 0.2% tetraethylene glycol dimethacrylate 46 65 35 Divinyl benzene 23

at 0.1%

MA = methyl acrylate

MAA = methacrylic acid.

EXAMPLE 47

  This example describes a process for preparing the polymers according to the invention and for neutralizing the suspension or polymer slurry in the presence of different surfactants. In a polymerization reactor,

  2000 g of deionized water and 3 g of Cellosize QP-4400 (one

  from Union Carbide), which is a hydroxyethyl cellulose powder having a viscosity of 4000 to 6000

  eps in 2% solution), as suspending agent. We heated

  the contents of the reactor at 65 C until

  hydroxyethyl cellulose, then cooled to 35 C.

  In the reactor, was added with stirring, a

  mixture containing 325 g of methyl acrylate, 175 g of

  of glacial methacrylic acid, 0.5 g of ethyl dimethacrylate

  g / yol as crosslinking agent and 0.5 g of azobisiso-

butyronitrile as catalyst.

  The reactor contents were then deaerated by purging with a stream of nitrogen at a moderate flow rate of 100 mJ / min for example. We raised the temperature to

  This allowed the mixture to polymerize for 3 hours.

  In the last hour, the temperature of the reaction

  at 80 ° C. to complete the reaction. The total duration of the reaction was 3 hours. The contents of the reactor were constantly agitated throughout the duration of the reaction.

of polymerization.

  Once the reaction is complete, we have cooled

  the suspension in the reactor at 25 C. The suspension was diluted with 500 g of water to facilitate stirring

and flow.

  An aliquot was transferred from one

  (600g) of the suspension in a steel beaker and stirred very rapidly (3000 rpm) with a

  dispersion device. 5% Aerosol OT com

  surfactant (a dioctyl sodium sulfosuccinate

  American Cyanamid firm "), which was then added to the suspen-

  195 g of 10% NaOH and the suspension solidified or taken up once in a soft mass, swollen, friable, granulated. The weight ratio of water to polymer in the

  neutralization stage was 6.76 to 1. The salt of poly-

  Sodium mother, solid and friable, was then dried at 80 ° C. in an empty study to remove the water contained therein, and then crushed to pass through a sieve with a mesh size of 0.18 mm. The resulting dry product was absorbed 100 times with water in a 1% NaCl solution.

  absorbed Sl times his weight. The absorption rates

  were respectively 8 and 21 seconds.

EXEXPLE 48

  This example describes the preparation of various

  absorbent articles with the polymers according to the invention.

  A. To a suspension of 250 g of cellulose de-

  fiber containing 5 g of cellulose, we have

  slowly added 0.5 g of finely ground dry polymer salt, obtained according to Example 1. After mixing for 2 minutes, the suspension was diluted in the machine head dough of a conventional laboratory sheet machine. of Noble & Wood, and it was shaped into sheets or towels of 30 x 30 cm that were dried

  and subjected to the water absorbance test.

  The article contained 10% of polymer salt.

  Dry paper absorbed 12 times its weight

of water.

  B. A suspension of polymer,

  prepared in accordance with Example 47 at a solids content and neutralized with an excess of 20 mol% of a 10% NaOH solution. The neutralized polymer swollen and

  absorbed all the water, forming a so-

  This paste was diluted with water to a solids content of 0.5%. 100 g of the suspension were added

  250 g of a suspension of a paste of this

  refined lulose containing 5 g of cellulose.

  Leaves or ser-

  30 cm x 30 cm as described above.

  above and the absorbance of water was determined.

  Dry paper absorbed 6.6 times its weight

of water.

  C. 6 sheets of 10 x 25 cm toilet paper weighing 3.5 g were piled one on top of the other and powder was sprinkled uniformly between

  the layers 3.5 g of fine polymer salt

  The resulting multilayer buffer was sprayed with a water mist until its weight was increased.

  at 20 g. The human buffer was then dried

  mide at B4'C so that the layers stick together. The pad was rolled into an elongated form, immersed in 1% NaCl solution for a few minutes, and then compressed under a pressure of

  0.1 kg / cm for 5 minutes to determine

  the degree of absorption of the solution

  line. The buffer absorbed 9 times its weight of 1% NaCl solution. As above, a similar control towel was treated, but without the addition of a polymer, the absorbent

  was then 3 times its weight of

saline solution.

COMPARATIVE EXAMPLES A to G

  The absorption rates of water and saline for various

  water-swellable and water-insoluble polymers,

  marketed with the dry polymer salt prepared according to

  Example 1. The polymers tested and their chemical description

  as well as the results of the tests are indi-

  in Table VI. The results show that

  polymers according to the invention have an unexpected superiority.

  stretched over the inflatable compositions in water, insolu-

in the water.

  In the example, the comparison material or control A is AQUALON, a product marketed by the firm HERCULES INC.,. The comparison material or control B is VITERRA-1, a product marketed by the Union-Carbide Corporation. Comparative or control material C is VITERRA-2 a product marketed by Union-Carbide Corporation. Comparative or control material D is PERMASORB-10, a product marketed by National Starch & Chemical Corporation. The comparison material or control F is PERMASORB-30, a product marketed by the firm National Starch &

  Chemical Corporation. The comparison material or

  F is H-SPAN, a product marketed by Fir-

  General Mills Chemicals, Inc. The material is produced under license from the US Department of Agriculture. The comparison material or control G is DOWFLAKE, a product

  marketed by Dow Chemical Company and produced by

  US Pat. Nos. 3,980,663 and 3,993,616.

TABLE VI

  Absorption Multiple dry weight Water Product according to the invention 1% NaCl Product A 16 5

carboxymethylcellulose fibers

  internal crosslinked sodium lose Product B crosslinked polyethylene oxide 13 Non-gelled gelled product C no

acrylamide copolymer -

  filterable filterable Na-acrylate Non-gelled non-gelled acrylic product with a filterable hydrophilic filterable hydrophilic carboxylate Product E acrylic polymer with non-hydrophilic carboxylate groups Hydrocarbon-free non-starch product / filterable filterable graft-filtered filterable acrylamide Product G Gelified gelled crosslinked salt of a filterable filterable carboxylic acid polyelectrolyte non-lime It is clear that one can bring various

  modifications to the described invention without departing from its

of t :.

Claims (21)

  1. Polymer, characterized in that   takes: (a) from about 15 to about 50 weight percent of an olefinically unsaturated carboxylic acid;   (b) from about 49.07% to about 82% by weight of an acry-   alkyl terminus wherein the alkyl group has 1 to 6 carbon atoms; and (c) from about 0.03 to 3.0% by weight of an agent crosslinking.   2. Polymer according to claim 1,   it contains about 20 to 40% by weight   carboxylic acid with olefinically unsaturated thacrylic or acrylic acid.   3. Polymer according to claim 2, characterized   in that up to 8% by weight of the total amount of   carboxylic acid with olefinic unsaturation present are   selected from itaconic acid, maleic acid and anhy- maleic druid.   4. Polymer according to claim 1, characterized   rised in that it contains from 59.02% to 78% of a weight   of an alkyl acrylate chosen from methyl acrylate, the   ethyl crylate and n-butyl acrylate.   Polymer according to claim 1, characterized   in that it contains from about 0.08 to 2% by weight of a crosslinking agent.   6. Polymer salt usable as an abbreviation   water sorbent, comprising the salt of a polymer, characterized in that it is essentially the suspension polymerization reaction product of:   (a) about 15 to 50% by weight of a carboxylic acid;   olefinically unsaturated boxylic;   (b) 49.07 to 82% by weight of an acrylate   aloye salt wherein the alkyl group has 1 to 6 carbon atoms; and (c) from about 0.08 to 2.0% by weight of an agent crosslinking.   7. Polymer insoluble in water according to   claim 6, characterized in that it comprises from 20 to 40%   about 1% by weight of the carboxylic unsaturated carboxylic acid   fin, such as methacrylic acid or acrylic acid.   Water-insoluble polymer according to Claim 7, characterized in that up to 8% by weight of the total amount of the olefinically unsaturated carboxylic acid present is selected from itaconic acid,   maleic acid and maleic anhydride.   9. Polymer insoluble in water according to   claim 6, characterized in that it comprises from 59.02 to about 78% by weight of the alkyl acrylate chosen from acrylate   methyl, ethyl acrylate and n-butyl acrylate.   10. Polymer insoluble in water according to   claim 6, characterized in that it comprises O, OS to   About 2% by weight of crosslinking agent.   He. Polymer insoluble in water according to   Claim 6, characterized in that the salt is a salt of   chosen from among the sodium, potassium, thium and ammonium.   12. Perfecting a cloth or dressing   absorbent material comprising an absorbent layer containing a   Inflatable material in water, insoluble in water,   in that at least a portion of the inflatable material in   water, insoluble in water, is an alkaline salt of a poly-   mother prepared by the reaction of:   (a) about 15 to 50% by weight of a carboxylic acid;   olefinically unsaturated boxylic; (b) 49.07 to 82% by weight of an alkyl acrylate wherein the alkyl group has 1 to 6 carbon atoms; and   (c) 0.03 to 3.0% by weight of a cross-linking agent lation.   13. Linen or absorbent dressing according to the   12, characterized in that it comprises from 20 to 40%   about 1% by weight of the carboxylic unsaturated carboxylic acid   finique, selected from methacrylic and acrylic acids.   14. Linen or absorbent dressing according to the   12, characterized in that up to 8% by weight of   the total amount of carboxylic unsaturated carboxylic acid   present are selected from itaconic acid,   of maleic and maleic anhydride.   15. Absorbent linen or dressing according to the   12, characterized in that it comprises from 59.02 to   About 78% by weight of alkyl acrylate selected from acry-   methylate, ethyl acrylate and n-butyl acrylate   the. 16. Linen or dressing according to claim 12, characterized in that it comprises from 0.08 to 2% approximately in weight of crosslinking agent.   17. Manufactured product with support   flexible, allowing the absorption of water, which support is   characterized in that it contains a solid, water-swellable, water-insoluble polymer, which is the alkaline salt of a   polymer obtained by the reaction of the materials consisting of sensibly in:   (a) from about 15 to about 50% by weight of a carboxylic acid;   olefinically unsaturated boxylic; (b) from about 49.07 to about 82 percent by weight of an alkyl acrylate wherein the alkyl group has from 1 to 6 carbon atoms; and (c) from about 0.03 to 3.0% by weight of an agent crosslinking.   18. Manufactured product according to claim 17, characterized in that it comprises from 20 to 40% by weight of an olefinically unsaturated carboxylic acid,   selected from methacrylic acid or acrylic acid.   19. Manufactured product according to the   17, characterized in that up to 8% by weight of the   totality of the olefinically unsaturated carboxylic acid   that present are selected from itaconic acid,   maleic acid and maleic anhydride.   20. Manufactured product according to the   17, characterized in that it comprises from 59.02 to. 78%   by weight of alkyl acrylate selected from methyl acrylate   ethyl acrylate and n-butyl acrylate.   21. Manufactured product according to the   17, characterized in that it comprises 0.08 ± 2%   1% by weight of crosslinking agent.   22. Polymer-obtained polymer composition   suspension composition, characterized in that it comprises a mixture of the following essential constituents: (a) from 20 to. About 40% by weight of a carboxylic acid. olefinic unsaturation, such as methacrylic acid or acrylic acid;   (b) from 59.02 to. About 78% by weight of an acrylate   an alkyl group selected from the group acrylate   ethyl acrylate and n-butyl acrylate, and (c) from about 0.08 to about 2% by weight of an crosslinking.   23. Use of manufactured goods according to   claims 1 and 22 for the improvement of soils and cultures.