CA2042183A1 - Absorbent polymers, their manufacturing process and their use - Google Patents
Absorbent polymers, their manufacturing process and their useInfo
- Publication number
- CA2042183A1 CA2042183A1 CA002042183A CA2042183A CA2042183A1 CA 2042183 A1 CA2042183 A1 CA 2042183A1 CA 002042183 A CA002042183 A CA 002042183A CA 2042183 A CA2042183 A CA 2042183A CA 2042183 A1 CA2042183 A1 CA 2042183A1
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- Prior art keywords
- silica
- alkali metal
- weight
- polymers
- acrylic acid
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F20/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof
- C08F20/02—Monocarboxylic acids having less than ten carbon atoms, Derivatives thereof
- C08F20/04—Acids, Metal salts or ammonium salts thereof
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
- A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
- A61L15/18—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons containing inorganic materials
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
- A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
- A61L15/42—Use of materials characterised by their function or physical properties
- A61L15/60—Liquid-swellable gel-forming materials, e.g. super-absorbents
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- Chemical & Material Sciences (AREA)
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- Veterinary Medicine (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Epidemiology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Hematology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Dispersion Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Materials For Medical Uses (AREA)
- Polymerisation Methods In General (AREA)
- Absorbent Articles And Supports Therefor (AREA)
Abstract
TITLE of the INVENTION
"New absorbent polymers, their manufacturing process and their use"
TEXT of ABSTRACT
Very absorbent, cross-linked, hydrophilic polymers, in the form of micropearls, insoluble in water, based on silica and acrylic acid partially salified by an alkali metal, their manufacturing process and their use, notably, as absorbent compounds.
"New absorbent polymers, their manufacturing process and their use"
TEXT of ABSTRACT
Very absorbent, cross-linked, hydrophilic polymers, in the form of micropearls, insoluble in water, based on silica and acrylic acid partially salified by an alkali metal, their manufacturing process and their use, notably, as absorbent compounds.
Description
~Z~33 The present invention relates to new a~sorbent polymers, their manufacturing process and theix use.
Ilydrophilic cross-linked polymers, which are insoluble in water, based on acrylic acid and an alkali metal acrylate are widely used today in articles of hygiene due to their astonishing absorption power for physiological fluids: urine, blood, etc... The market, which is buoyant for this type of product, is a buyer of products which either perform better, or are more economical or more ecologically sound.
Now the Rpplicant has discovered, with astonishment, new highly absorbent polymers with absorbent properties which are superior to the products currently commercially available or described, whilst on the one hand being less expensive and on the other hand having less impact on the environment.
The highly absorbent polymers according to the present invention are cross-linked, in the form of micropearls, hydrophilic, insoluble in water, based on acrylic acid partially salified by an alkali metal and silica.
By "micropearls", is meant approximately spherical pearls with a diameter of between 0.05 and 1 mm.
sy "insoluble in water", is meant that the polymers contain, at ambient temperature, less than 5% by weight of products which are soluble in ~ater.
Within the scope of the present invention, the term "silica" designates amorphous colloidal silica, in a particle state ~ith particles of an average diameter between 7 and 150 nm, which are non--agglomerated between themselves by siloxane bonds : Si-O-Si.
Currently, it is not known exactly how the colloidal silica is fixed in the polymers of the present invention;
however it is known that the discrete particles of silica are uniformly spread in the polymer micropearls.
Among the polymers defined above, there can be more particularly mentioned acrylic acid - alkali metal acrylate -silica polymers containing, by weight, 2 to 25% of silica and98 to 75% of acrylic acid of which 60 to 80% is salified by an alkali metal. Advantageously, the alkali metal is sodium or potassium and preerentially, the alkali metal is potassium.
More particularly a subject of the invention is polymers as defined above containing, by weight, from 5 to 20% of silica and from 95 to 80% of acrylic acid of which 65 to 75%
is salified by an alkali metal.
According to the invention, the polymers defined above can be prepared by a polymerization process as a water-in-oil suspension carried out in an inert atmosphere, characterized in that an aqueous phase obtained extemporaneously, preferably as the introduction proceeds, starting with, on the one hand, an aqueous solution, preferably de-oxygenated, containing one or more hydrosoluble polymerization initiators which are free radical generators and, on the other hand, an aqueous phase containing the silica and chosen monomers at a concentration of 50 + 15% by weight is introduced slowly, under agitation, into the oil phase which is de-oxygenated, preferably completely, maintained at boiling point and containing a colloid protector. Then, when the polymerization is finished, the solvents are eliminated by azeotropic distillation until a suspension with a dry content of about + 10% by weight is obtained and finally the desired polymer is isolated, notably by filtration.
The oil phase is constituted by one or more hydrocarbons which are non-miscible with water, inert with regard to the polymerization initiators and capable of forming an azeotropic mixture with water such as cyclohexane or petroleum fractions with a boiling point comprised between 50 and 180C.
The colloid protector, preferably used at the rate of 0.4 to 2% by weight relative to the weight of monomers, is chosen from those currently used in this type of polymerization in suspension (cf. Kirk-Othmer, Encyclopaedia of Chemical Technology, 3rd edition, vol. 1, page 400).
Advantageously a cellulose ether will be chosen and, preferably, a cellulose ethylether with an ethoxyl content of 48 to 49.5% (cf. Encyclopaedia of Polymer Science and Engineering, 2nd edition, vol. 3, page 254). The colloid protector is dissolved or dispersed beforehand in the oil phase. The polymerization reaction is carried out at the boiling point of the reaction mixture, usually at ambient pressure. It can also be carried out at a lower or higher pressure than ambient pressure.
The polymerization reaction is initiated by one or more hydrosoluble free radical generators, advantageously with a half-life at 70C of greater than 2 hours. Such initiating agents are notably certain mineral peroxides such as sodium peroxodisulphate or certain azo-compounds such as 4,4'-dicyano-4,4'-azopentanedioic acid. They are advantageously used at a concentration of 200 to 3,000 ppm relative to the weight of monomers and advantageously at a concentration of 500 to 1,500 ppm. The initiating agent or agents used are dissolved in water, then this solution is carefully de-oxygenated.
The potassium acrylate is obtained advantageously in aqueous solution, by direct salification of an aqueous solution of acrylic acid with potash. This salification is advantageously carried out at a temperature of between 20C
and 35C. The monomers used are dissolved in water at a concentration of about 50 + 15% by weight.
The silica is used in the form of concentrated aqueous suspensions of non-agglomerated particles of amorphous silica which is commercially available notably, by the Applicant, under the brand name "KLEBOSOL".
The aqueous solution of the initiator and the aqueous phase containing the monomers and the silica are mixed extemporaneously, in an inert atmosphere, as their introduction into the agitated oil phase proceeds, completely de-oxygenated and maintained at boiling point by external heating, if necessary. They therefore remain in contact for only a few seconds before their use and they are introduced slowly into the boiling reaction mixture. The duration of the introduction can vary according to the operating parameters, but generally it is between one and two hours. At the end of the introduction, it is advantageous to maintain the reaction medium at boiling point and under agitation in order to complete the polymerization. After the polymerization is finished, the reaction solvents are eliminated by azeotropic distillation until a suspension is obtained which has a dry content of 85 + 10% and the expected product is isolated.
With a view to this isolation, the suspension is filtered and the polymers according to the invention thus recovered are dried at 60C until the dry content is greater than 90%. Thus the polymers according to the invention are obtained in the form of micropearls which are devoid of fines.
In the course of the polymerization reaction, the polymers formed spontaneously cross-link with each other to create cross-linked polymers which are insoluble in water, with a very strong hydrophilic character and a very low proportion of residual monomers, which is always less than 0.01% by weight.
15The cross-linking is accordingly more promoted as the degree of neutralization of the acrylic acid is lower and as the polymerization temperature is higher. The copolymers of the present invention are therefore cross-linked thermally - and, due to this fact, become insoluble in water and acquire ` 20 hydrophilic properties.
These properties are easily determined by a set of simple tests.
Therefore, the water absorption capacity of the polymer, designated TG, is determined at 20C, by agitating 0.4 g of polymer in 500 g of water for 30 minutes, then by weighing the drained polymer gel obtained. The weight found is rounded to 1 g of dry polymer. The copolymers of the present invention show, in this test, an absorption capacity in the order of 300 to 700 g per gram of dry polymer. By "dry polymer", a polymer with 100% active material is referred to.
The absorption capacity of the polymer for salty physiological solutions, designated TGS, is determined at 20C, by agitating 2 g of polymer in 500 g of a salty physiological solution for 30 minutes, then by weighing the drained polymer gel obtained. The weight found is rounded, as previously, to 1 g of dry polymer. The copolymers of the present invention show, in this test, an absorption capacity in the order of 40 to 70 g per gram of dry polymer.
20421~3 The proportion of extractables, designated TE, is determined according to the following method:
- 1 g of test polymer is placed in 200 g of salty physiological solution;
S - this suspension is agitated for one hour at 20C then left at rest for 15 hours at 20C;
- the polymer gel obtained is drained and the filtrate is collected;
- the carboxylic and carboxylate functions present are determined for 100 cm3 of filtrate;
- the result of this determination is expressed in grams of polymer dissolved per 100 g of dry polymer.
In this test, the polymers of the present invention show a p~oportion of extractables of 1-5%.
The absorption capacity by capillary action under a load of 15 g per cm2, designated TGC, is determined at 20C
according to the following procedure: 40 g of Fontainbleu sand with a granulometry of 0.100 to 0.300 mm, 2 g of test copolymer and lastly 40 g of Fontainbleu sand are spread successively and uniformly on a 90 mm diameter filtering plate, with a porosity of 1, in a cylindrical funnel. Then a total load of 954 g is placed on top of the upper layer of sand with a 90 mm diameter glass disc as intermediary, then the funnel is plunged into a tank containing a salty physiological solution, at constant level, in such a way that the water level completely covers the upper face of the sintered glass and the quantity of salty physiological solution absorbed by capillary action by the copolymer over minutes is measured. The result is expressed in grams of salty physiological solution per gram of dry polymer.
The polymers of the present invention therefore have very useful absorbent properties which justify their use as an absorption agent and also a subject of the invention is, as absorption agents , the polymers as defined previously, notably for the manufacture of articles of hygiene, particularly babies' nappies.
The following examples illustrate the invention without however limiting it.
Bxamp~les Example 1 - 3.5 g of cellulose ethylether, designated EEC, containing 48 to 49.5% of ethoxylated groups and having, at 25C, a viscosity of 200 mPa.s, in solution at 5% in a mixture of toluene-ethanol 80-20 by weight, is dispersed, in an inert atmosphere, - in 634 g of cyclohexane designated CY.
In this dispersion, which is carefully de-oxygenated, agitated and maintained at boiling point, the following solution, which is mixed extemporaneously during the introduction, is introduced over 90 minutes in an inert atmosphere:
- on the one hand, a de-oxygenated solution of:
0.467 g of sodium peroxodisulphate, designated PDS, dissolved in 10 g of water, - on the other hand, 624 g of a solution prepared extemporaneously by dissolving the following at a temperature lower than 30C:
- 230 g (3.19moles)of acrylic acid, designated AA, in:
- 314 g of an aqueous solution of potash containing 128.9 g (2.3 moles) of potassium hydroxide and 185 g of water, then adding 80 g of a silica sol containing 50% silica in the form of particles with an average diameter, designated Dm, of 50 nm, having a pH of 9 and stabilized with sodium hydroxide at 0.3% by weight (KLEBOSOL, PL 1346 Na).
The solution obtained is then subjected to azeotropic distillation until 240 g of water is eliminated and, finally, it is cooled down to ambient temperature and filtered. The precipitate is then dried to 96% dryness under reduced pressure at 60C in a ventilated oven.
In this way 372 g of an acrylic acid - potassium acrylate - silica polymer is obtained, which is insoluble in water and is in the form of pearls of a few tenths of a millimetre in diameter. This polymer has a proportion of residual monomers which is less than 0.005% by weight, a water absorption capacity of about 430 g per gram, an absorption capacity for a salty physiological solution of about 53 g per gram and an absorption capacity under load of 23.5 g per gram.
The proportion of extractables, TE, is 2.8%.
Examples 2 - 10 and comparative example 11 Examples 2 - 10 and comparative Example 11 are carried out by following the operating procedure described in Example 1. Tables I and II mention the quantities of raw materials used, expressed in grams as well as the characteristics of the polymers obtained. The very absorbent polymer obtained in comparative Example 11 does not contain silica and is known.
Comparative Example 12 11.7 g of silica with an average particle diameter of 10 micrometers is mixed carefully with 88.3 g of the very absorbent polymer prepared in Example 11. The mixture obtained has a TGS of 8.3 and a TGC of 13.5, these values being clearly lower than those shown by the original polymer.
It is therefore noted that silica which is simply mixed with a very absorbent known polymer, instead of increasing the absorption characteristics of the polymer, reduces them drastically.
Examination of table II allows it to be stated that the presence of combined silica in the polymers of the present invention improves their absorption capacity under load, TGC, by almost 30 + 5%. Now, for their use in articles of hygiene, this property is important, indeed essential. Furthermore, this benefit is obtained with less organic materials, which constitute the most important part of the cost price of the polymer and the main expense in their destruction after use.
The polymers of the present invention therefore have superior characteristics to those of the prior art.
9 2042~83 TABLE I
No. Oi 1 p] lase A lueous pha ~e Silica sol Df EEC CY Weight PDS AA KOH WATER Weight %SiO2 Dm Total Ex. (g) (g) (g) weight _ _ ._ 1 3.5 634 637.5 0.467 230 129.2 195.3 80 50 50 nm 634.5 2 3.5 634 637.5 0.467 230 129.2 195.3 80 30 25 nm 634.5 3 3.5 634 637.5 0.467 230 129.2 195.3 80 30 13 nm 634.5 4 3.5 634 637.5 0.467 230 129.2 235.3 40 30 25 nm 634.5 3.5 634 637.5 0.467 230 129.2 195.3 80 15 7 nm 634.5 6 3.5 607 610.5 0.318 230 107.7 189.6 80 50 50 nm 607.3 7 3.5 619 622.5 0.318 ~30 116.7 192.6 80 50 50 nm 619.3 8 3.5 634 637.5 0.318 230 129.2 195.3 80 50 50 nm 634.5 9 3.5 634 637.5 0.318 230 129.2 115.3 16050 50 nm 634.5 10 3.5 634 637.5 0.467 230 129.2 115.3 80 30 9 nm 634.5 11 3.5 634 637.5 0.467 230 129 2 275.3 0 _ 634.5 1 o 2042183 TABLE II
No. TN~ - %Sio2 TG TGS TGC TE TMR~*
1 72% 357 11.2430 53 23.5 2.8 c50 ppm 2 72% 341 7.04414 52 19.5 3 72% 341 7.04426 52.5 21 4 72% 329 3.6571 51.5 17.3 4.8 <50 ppm 72% 329 3.6357 50 21.5 4.0 ~50 ppm 6 60% 343 11.7677 61 22.5 7 65% 349 11.4608 58 22 8 72% 357 11.2617 60 22 9 72% 397 20.1480 48 19.5 72% 341 7.04333 48 24 11 72% 317 0 447 57 17 12 60% 100 11.7 8.3 13.5 _ .
* TN : neutralization percentage ** PP : weight of dry polymers expressed in grams *** TMR : proportion of residual monomers expressed in ppm :
Ilydrophilic cross-linked polymers, which are insoluble in water, based on acrylic acid and an alkali metal acrylate are widely used today in articles of hygiene due to their astonishing absorption power for physiological fluids: urine, blood, etc... The market, which is buoyant for this type of product, is a buyer of products which either perform better, or are more economical or more ecologically sound.
Now the Rpplicant has discovered, with astonishment, new highly absorbent polymers with absorbent properties which are superior to the products currently commercially available or described, whilst on the one hand being less expensive and on the other hand having less impact on the environment.
The highly absorbent polymers according to the present invention are cross-linked, in the form of micropearls, hydrophilic, insoluble in water, based on acrylic acid partially salified by an alkali metal and silica.
By "micropearls", is meant approximately spherical pearls with a diameter of between 0.05 and 1 mm.
sy "insoluble in water", is meant that the polymers contain, at ambient temperature, less than 5% by weight of products which are soluble in ~ater.
Within the scope of the present invention, the term "silica" designates amorphous colloidal silica, in a particle state ~ith particles of an average diameter between 7 and 150 nm, which are non--agglomerated between themselves by siloxane bonds : Si-O-Si.
Currently, it is not known exactly how the colloidal silica is fixed in the polymers of the present invention;
however it is known that the discrete particles of silica are uniformly spread in the polymer micropearls.
Among the polymers defined above, there can be more particularly mentioned acrylic acid - alkali metal acrylate -silica polymers containing, by weight, 2 to 25% of silica and98 to 75% of acrylic acid of which 60 to 80% is salified by an alkali metal. Advantageously, the alkali metal is sodium or potassium and preerentially, the alkali metal is potassium.
More particularly a subject of the invention is polymers as defined above containing, by weight, from 5 to 20% of silica and from 95 to 80% of acrylic acid of which 65 to 75%
is salified by an alkali metal.
According to the invention, the polymers defined above can be prepared by a polymerization process as a water-in-oil suspension carried out in an inert atmosphere, characterized in that an aqueous phase obtained extemporaneously, preferably as the introduction proceeds, starting with, on the one hand, an aqueous solution, preferably de-oxygenated, containing one or more hydrosoluble polymerization initiators which are free radical generators and, on the other hand, an aqueous phase containing the silica and chosen monomers at a concentration of 50 + 15% by weight is introduced slowly, under agitation, into the oil phase which is de-oxygenated, preferably completely, maintained at boiling point and containing a colloid protector. Then, when the polymerization is finished, the solvents are eliminated by azeotropic distillation until a suspension with a dry content of about + 10% by weight is obtained and finally the desired polymer is isolated, notably by filtration.
The oil phase is constituted by one or more hydrocarbons which are non-miscible with water, inert with regard to the polymerization initiators and capable of forming an azeotropic mixture with water such as cyclohexane or petroleum fractions with a boiling point comprised between 50 and 180C.
The colloid protector, preferably used at the rate of 0.4 to 2% by weight relative to the weight of monomers, is chosen from those currently used in this type of polymerization in suspension (cf. Kirk-Othmer, Encyclopaedia of Chemical Technology, 3rd edition, vol. 1, page 400).
Advantageously a cellulose ether will be chosen and, preferably, a cellulose ethylether with an ethoxyl content of 48 to 49.5% (cf. Encyclopaedia of Polymer Science and Engineering, 2nd edition, vol. 3, page 254). The colloid protector is dissolved or dispersed beforehand in the oil phase. The polymerization reaction is carried out at the boiling point of the reaction mixture, usually at ambient pressure. It can also be carried out at a lower or higher pressure than ambient pressure.
The polymerization reaction is initiated by one or more hydrosoluble free radical generators, advantageously with a half-life at 70C of greater than 2 hours. Such initiating agents are notably certain mineral peroxides such as sodium peroxodisulphate or certain azo-compounds such as 4,4'-dicyano-4,4'-azopentanedioic acid. They are advantageously used at a concentration of 200 to 3,000 ppm relative to the weight of monomers and advantageously at a concentration of 500 to 1,500 ppm. The initiating agent or agents used are dissolved in water, then this solution is carefully de-oxygenated.
The potassium acrylate is obtained advantageously in aqueous solution, by direct salification of an aqueous solution of acrylic acid with potash. This salification is advantageously carried out at a temperature of between 20C
and 35C. The monomers used are dissolved in water at a concentration of about 50 + 15% by weight.
The silica is used in the form of concentrated aqueous suspensions of non-agglomerated particles of amorphous silica which is commercially available notably, by the Applicant, under the brand name "KLEBOSOL".
The aqueous solution of the initiator and the aqueous phase containing the monomers and the silica are mixed extemporaneously, in an inert atmosphere, as their introduction into the agitated oil phase proceeds, completely de-oxygenated and maintained at boiling point by external heating, if necessary. They therefore remain in contact for only a few seconds before their use and they are introduced slowly into the boiling reaction mixture. The duration of the introduction can vary according to the operating parameters, but generally it is between one and two hours. At the end of the introduction, it is advantageous to maintain the reaction medium at boiling point and under agitation in order to complete the polymerization. After the polymerization is finished, the reaction solvents are eliminated by azeotropic distillation until a suspension is obtained which has a dry content of 85 + 10% and the expected product is isolated.
With a view to this isolation, the suspension is filtered and the polymers according to the invention thus recovered are dried at 60C until the dry content is greater than 90%. Thus the polymers according to the invention are obtained in the form of micropearls which are devoid of fines.
In the course of the polymerization reaction, the polymers formed spontaneously cross-link with each other to create cross-linked polymers which are insoluble in water, with a very strong hydrophilic character and a very low proportion of residual monomers, which is always less than 0.01% by weight.
15The cross-linking is accordingly more promoted as the degree of neutralization of the acrylic acid is lower and as the polymerization temperature is higher. The copolymers of the present invention are therefore cross-linked thermally - and, due to this fact, become insoluble in water and acquire ` 20 hydrophilic properties.
These properties are easily determined by a set of simple tests.
Therefore, the water absorption capacity of the polymer, designated TG, is determined at 20C, by agitating 0.4 g of polymer in 500 g of water for 30 minutes, then by weighing the drained polymer gel obtained. The weight found is rounded to 1 g of dry polymer. The copolymers of the present invention show, in this test, an absorption capacity in the order of 300 to 700 g per gram of dry polymer. By "dry polymer", a polymer with 100% active material is referred to.
The absorption capacity of the polymer for salty physiological solutions, designated TGS, is determined at 20C, by agitating 2 g of polymer in 500 g of a salty physiological solution for 30 minutes, then by weighing the drained polymer gel obtained. The weight found is rounded, as previously, to 1 g of dry polymer. The copolymers of the present invention show, in this test, an absorption capacity in the order of 40 to 70 g per gram of dry polymer.
20421~3 The proportion of extractables, designated TE, is determined according to the following method:
- 1 g of test polymer is placed in 200 g of salty physiological solution;
S - this suspension is agitated for one hour at 20C then left at rest for 15 hours at 20C;
- the polymer gel obtained is drained and the filtrate is collected;
- the carboxylic and carboxylate functions present are determined for 100 cm3 of filtrate;
- the result of this determination is expressed in grams of polymer dissolved per 100 g of dry polymer.
In this test, the polymers of the present invention show a p~oportion of extractables of 1-5%.
The absorption capacity by capillary action under a load of 15 g per cm2, designated TGC, is determined at 20C
according to the following procedure: 40 g of Fontainbleu sand with a granulometry of 0.100 to 0.300 mm, 2 g of test copolymer and lastly 40 g of Fontainbleu sand are spread successively and uniformly on a 90 mm diameter filtering plate, with a porosity of 1, in a cylindrical funnel. Then a total load of 954 g is placed on top of the upper layer of sand with a 90 mm diameter glass disc as intermediary, then the funnel is plunged into a tank containing a salty physiological solution, at constant level, in such a way that the water level completely covers the upper face of the sintered glass and the quantity of salty physiological solution absorbed by capillary action by the copolymer over minutes is measured. The result is expressed in grams of salty physiological solution per gram of dry polymer.
The polymers of the present invention therefore have very useful absorbent properties which justify their use as an absorption agent and also a subject of the invention is, as absorption agents , the polymers as defined previously, notably for the manufacture of articles of hygiene, particularly babies' nappies.
The following examples illustrate the invention without however limiting it.
Bxamp~les Example 1 - 3.5 g of cellulose ethylether, designated EEC, containing 48 to 49.5% of ethoxylated groups and having, at 25C, a viscosity of 200 mPa.s, in solution at 5% in a mixture of toluene-ethanol 80-20 by weight, is dispersed, in an inert atmosphere, - in 634 g of cyclohexane designated CY.
In this dispersion, which is carefully de-oxygenated, agitated and maintained at boiling point, the following solution, which is mixed extemporaneously during the introduction, is introduced over 90 minutes in an inert atmosphere:
- on the one hand, a de-oxygenated solution of:
0.467 g of sodium peroxodisulphate, designated PDS, dissolved in 10 g of water, - on the other hand, 624 g of a solution prepared extemporaneously by dissolving the following at a temperature lower than 30C:
- 230 g (3.19moles)of acrylic acid, designated AA, in:
- 314 g of an aqueous solution of potash containing 128.9 g (2.3 moles) of potassium hydroxide and 185 g of water, then adding 80 g of a silica sol containing 50% silica in the form of particles with an average diameter, designated Dm, of 50 nm, having a pH of 9 and stabilized with sodium hydroxide at 0.3% by weight (KLEBOSOL, PL 1346 Na).
The solution obtained is then subjected to azeotropic distillation until 240 g of water is eliminated and, finally, it is cooled down to ambient temperature and filtered. The precipitate is then dried to 96% dryness under reduced pressure at 60C in a ventilated oven.
In this way 372 g of an acrylic acid - potassium acrylate - silica polymer is obtained, which is insoluble in water and is in the form of pearls of a few tenths of a millimetre in diameter. This polymer has a proportion of residual monomers which is less than 0.005% by weight, a water absorption capacity of about 430 g per gram, an absorption capacity for a salty physiological solution of about 53 g per gram and an absorption capacity under load of 23.5 g per gram.
The proportion of extractables, TE, is 2.8%.
Examples 2 - 10 and comparative example 11 Examples 2 - 10 and comparative Example 11 are carried out by following the operating procedure described in Example 1. Tables I and II mention the quantities of raw materials used, expressed in grams as well as the characteristics of the polymers obtained. The very absorbent polymer obtained in comparative Example 11 does not contain silica and is known.
Comparative Example 12 11.7 g of silica with an average particle diameter of 10 micrometers is mixed carefully with 88.3 g of the very absorbent polymer prepared in Example 11. The mixture obtained has a TGS of 8.3 and a TGC of 13.5, these values being clearly lower than those shown by the original polymer.
It is therefore noted that silica which is simply mixed with a very absorbent known polymer, instead of increasing the absorption characteristics of the polymer, reduces them drastically.
Examination of table II allows it to be stated that the presence of combined silica in the polymers of the present invention improves their absorption capacity under load, TGC, by almost 30 + 5%. Now, for their use in articles of hygiene, this property is important, indeed essential. Furthermore, this benefit is obtained with less organic materials, which constitute the most important part of the cost price of the polymer and the main expense in their destruction after use.
The polymers of the present invention therefore have superior characteristics to those of the prior art.
9 2042~83 TABLE I
No. Oi 1 p] lase A lueous pha ~e Silica sol Df EEC CY Weight PDS AA KOH WATER Weight %SiO2 Dm Total Ex. (g) (g) (g) weight _ _ ._ 1 3.5 634 637.5 0.467 230 129.2 195.3 80 50 50 nm 634.5 2 3.5 634 637.5 0.467 230 129.2 195.3 80 30 25 nm 634.5 3 3.5 634 637.5 0.467 230 129.2 195.3 80 30 13 nm 634.5 4 3.5 634 637.5 0.467 230 129.2 235.3 40 30 25 nm 634.5 3.5 634 637.5 0.467 230 129.2 195.3 80 15 7 nm 634.5 6 3.5 607 610.5 0.318 230 107.7 189.6 80 50 50 nm 607.3 7 3.5 619 622.5 0.318 ~30 116.7 192.6 80 50 50 nm 619.3 8 3.5 634 637.5 0.318 230 129.2 195.3 80 50 50 nm 634.5 9 3.5 634 637.5 0.318 230 129.2 115.3 16050 50 nm 634.5 10 3.5 634 637.5 0.467 230 129.2 115.3 80 30 9 nm 634.5 11 3.5 634 637.5 0.467 230 129 2 275.3 0 _ 634.5 1 o 2042183 TABLE II
No. TN~ - %Sio2 TG TGS TGC TE TMR~*
1 72% 357 11.2430 53 23.5 2.8 c50 ppm 2 72% 341 7.04414 52 19.5 3 72% 341 7.04426 52.5 21 4 72% 329 3.6571 51.5 17.3 4.8 <50 ppm 72% 329 3.6357 50 21.5 4.0 ~50 ppm 6 60% 343 11.7677 61 22.5 7 65% 349 11.4608 58 22 8 72% 357 11.2617 60 22 9 72% 397 20.1480 48 19.5 72% 341 7.04333 48 24 11 72% 317 0 447 57 17 12 60% 100 11.7 8.3 13.5 _ .
* TN : neutralization percentage ** PP : weight of dry polymers expressed in grams *** TMR : proportion of residual monomers expressed in ppm :
Claims (9)
1. Very absorbent cross-linked, hydrophilic polymers, in the form of micropearls, which are insoluble in water, based on silica and acrylic acid partially salified by an alkali metal.
2. Polymers according to claim 1, characterized in that they contain, by weight, from 2 to 25% silica and from 98 to 75% acrylic acid of which 60 to 80% is salified by an alkali metal.
3. Polymers according to claim 1 or 2, characterized in that they contain, by weight, from 5 to 20% silica and from to 80% acrylic acid of which 65 to 75% is salified by an alkali metal.
4. Polymers according to any one of claims 1 to 3, characterized in that the alkali metal is sodium.
5. Polymers according to any one of claims 1 to 3, characterized in that the alkali metal is potassium.
6. Preparation process for a polymer according to any one of claims 1 to 5, by polymerization in a water-in-oil suspension carried out in an inert atmosphere, characterized in that an aqueous phase obtained extemporaneously, starting with, on the one hand, a de-oxygenated aqueous solution containing one or more hydrosoluble polymerization initiators which are free radical generators and, on the other hand, an aqueous phase containing the chosen monomers and silica at a concentration of 50 + 15% by weight is introduced slowly, under agitation into the de-oxygenated oil phase, maintained at boiling point and containing a colloid protector. Then, when the polymerization reaction is finished, the solvents are eliminated by azeotropic distillation until a suspension with a dry content of about 85 + 10% by weight is obtained and then the formed polymer is isolated, notably by filtration.
7. Process according to claim 6, characterized in that the oil phase is cyclohexane.
8. Use of a hydrophilic polymer according to any one of claims 1 to 5 as an absorbing component.
9. Use of a hydrophilic polymer according to claim 8 in an article of hygiene.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9005989A FR2661912B1 (en) | 1990-05-14 | 1990-05-14 | NOVEL ABSORBENT POLYMERS, THEIR MANUFACTURING PROCESS AND THEIR APPLICATION. |
| FR9005989 | 1990-05-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2042183A1 true CA2042183A1 (en) | 1991-11-15 |
Family
ID=9396583
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002042183A Abandoned CA2042183A1 (en) | 1990-05-14 | 1991-05-09 | Absorbent polymers, their manufacturing process and their use |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0457660B1 (en) |
| JP (1) | JP3145423B2 (en) |
| AT (1) | ATE148892T1 (en) |
| CA (1) | CA2042183A1 (en) |
| DE (1) | DE69124639T2 (en) |
| DK (1) | DK0457660T3 (en) |
| ES (1) | ES2100219T3 (en) |
| FR (1) | FR2661912B1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6514615B1 (en) | 1999-06-29 | 2003-02-04 | Stockhausen Gmbh & Co. Kg | Superabsorbent polymers having delayed water absorption characteristics |
| US10881555B2 (en) | 2016-03-30 | 2021-01-05 | Basf Se | Fluid-absorbent article |
Families Citing this family (24)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BR9005475A (en) * | 1990-10-29 | 1992-06-16 | Johnson & Johnson Ind Com | CONFORMABLE STRUCTURE, ABSORBENT ARTICLE AND MANUFACTURING PROCESS OF ABSORBENT ARTICLE |
| FR2682390B1 (en) * | 1991-10-11 | 1994-01-14 | Hoechst Ste Francaise | NOVEL ABSORBENT POLYMERS, METHOD OF MANUFACTURE AND THEIR APPLICATION, PARTICULARLY TO HYGIENE ARTICLES. |
| US5549590A (en) * | 1994-08-01 | 1996-08-27 | Leonard Pearlstein | High performance absorbent particles and methods of preparation |
| MX9700779A (en) * | 1994-08-01 | 1997-05-31 | Stuart Suskind | High performance superabsorbent material and absorbent devices containing the same. |
| US5849816A (en) * | 1994-08-01 | 1998-12-15 | Leonard Pearlstein | Method of making high performance superabsorbent material |
| KR100333972B1 (en) * | 1999-05-24 | 2002-04-24 | 송성원 | A water-absorbent resin compound, and a process of preparing the same |
| DE102005014291A1 (en) | 2005-03-24 | 2006-09-28 | Basf Ag | Process for the preparation of water-absorbing polymers |
| DE102005042604A1 (en) | 2005-09-07 | 2007-03-08 | Basf Ag | Neutralization process |
| EP2163266A1 (en) | 2008-09-12 | 2010-03-17 | The Procter & Gamble | Absorbent article comprising water-absorbing material |
| EP2470226A1 (en) | 2009-08-28 | 2012-07-04 | Basf Se | Process for producing triclosan-coated superabsorbents |
| BR112012005901A2 (en) | 2009-09-16 | 2019-09-24 | Basf Se | superabsorbent, process for producing a superabsorbent, article for absorbing fluids, and process for producing articles for absorbing fluids |
| US8815770B2 (en) | 2009-09-17 | 2014-08-26 | Basf Se | Color-stable superabsorber |
| EP2476714A1 (en) | 2011-01-13 | 2012-07-18 | Basf Se | Polyurethane integral foams with improved surface hardness |
| US8741169B2 (en) | 2011-09-26 | 2014-06-03 | Basf Se | Heat storage composition comprising sodium sulfate decahydrate and superabsorbent |
| EP2573153A3 (en) | 2011-09-26 | 2014-07-30 | Basf Se | Heat storing composition containing sodium sulfate, decahydrate and superabsorber |
| KR20140142740A (en) | 2012-03-30 | 2014-12-12 | 바스프 에스이 | Color-stable super-absorbent |
| CN104271622B (en) | 2012-03-30 | 2017-02-22 | 巴斯夫欧洲公司 | Color-stable super-absorbent |
| EP2730596A1 (en) | 2012-11-13 | 2014-05-14 | Basf Se | Polyurethane soft foam materials containing plant seeds |
| CN111278551B (en) | 2017-11-10 | 2023-09-29 | 巴斯夫欧洲公司 | Super absorbent |
| JP7361714B2 (en) | 2018-04-10 | 2023-10-16 | ビーエーエスエフ ソシエタス・ヨーロピア | Osmotic superabsorbent and method of manufacturing the same |
| CN112512476A (en) | 2018-08-01 | 2021-03-16 | 巴斯夫欧洲公司 | Fluid-absorbent core |
| DE102019216910A1 (en) | 2018-11-12 | 2020-05-14 | Basf Se | Process for post-crosslinking superabsorbents |
| JP2022542057A (en) | 2019-07-24 | 2022-09-29 | ビーエーエスエフ ソシエタス・ヨーロピア | Penetrating superabsorbent and method of making same |
| CN112704493B (en) * | 2021-01-05 | 2022-07-05 | 南方医科大学南方医院 | Medical sensor with long-acting super-hydrophilic performance and preparation method thereof |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3613081A1 (en) * | 1986-04-18 | 1987-10-29 | Basf Ag | METHOD FOR PRODUCING PEARL-SHAPED POLYMERISATES ON THE BASIS OF WATER-SOLUBLE ETHYLENICALLY UNSATURATED MONOMERS |
| FR2614027B1 (en) * | 1987-04-14 | 1989-08-18 | Hoechst France | HYDROPHILIC POLYMER BASED ON ACRYLIC ACID AND ALKALI METAL ACRYLATE, METHOD FOR PREPARING THE SAME AND APPLICATION AS AN ABSORBING AGENT, PARTICULARLY A PHYSIOLOGICAL SOLUTION |
-
1990
- 1990-05-14 FR FR9005989A patent/FR2661912B1/en not_active Expired - Fee Related
-
1991
- 1991-05-09 CA CA002042183A patent/CA2042183A1/en not_active Abandoned
- 1991-05-13 EP EP91401228A patent/EP0457660B1/en not_active Expired - Lifetime
- 1991-05-13 JP JP10622791A patent/JP3145423B2/en not_active Expired - Fee Related
- 1991-05-13 DE DE69124639T patent/DE69124639T2/en not_active Expired - Fee Related
- 1991-05-13 DK DK91401228.1T patent/DK0457660T3/en active
- 1991-05-13 ES ES91401228T patent/ES2100219T3/en not_active Expired - Lifetime
- 1991-05-13 AT AT91401228T patent/ATE148892T1/en active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6514615B1 (en) | 1999-06-29 | 2003-02-04 | Stockhausen Gmbh & Co. Kg | Superabsorbent polymers having delayed water absorption characteristics |
| US10881555B2 (en) | 2016-03-30 | 2021-01-05 | Basf Se | Fluid-absorbent article |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0457660A1 (en) | 1991-11-21 |
| ATE148892T1 (en) | 1997-02-15 |
| ES2100219T3 (en) | 1997-06-16 |
| JPH04227746A (en) | 1992-08-17 |
| DE69124639D1 (en) | 1997-03-27 |
| FR2661912A1 (en) | 1991-11-15 |
| EP0457660B1 (en) | 1997-02-12 |
| DE69124639T2 (en) | 1997-07-24 |
| DK0457660T3 (en) | 1997-08-18 |
| FR2661912B1 (en) | 1994-05-13 |
| JP3145423B2 (en) | 2001-03-12 |
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