CA2009500A1 - Absorbent composite and method for production thereof - Google Patents
Absorbent composite and method for production thereofInfo
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- CA2009500A1 CA2009500A1 CA002009500A CA2009500A CA2009500A1 CA 2009500 A1 CA2009500 A1 CA 2009500A1 CA 002009500 A CA002009500 A CA 002009500A CA 2009500 A CA2009500 A CA 2009500A CA 2009500 A1 CA2009500 A1 CA 2009500A1
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Abstract
ABSTRACT OF THE DISCLOSURE
An absorbent composite comprising 100 parts by weight of an absorbent polymer, 1 to 600 parts by weight of a fibrous substrate, and 0.1 to 50 parts by weight of polyaluminum chloride and having said absorbent polymer adjoined to and fixed on said fibrous substrate through the medium of said polyaluminum chloride as a binder, and production thereof.
An absorbent composite comprising 100 parts by weight of an absorbent polymer, 1 to 600 parts by weight of a fibrous substrate, and 0.1 to 50 parts by weight of polyaluminum chloride and having said absorbent polymer adjoined to and fixed on said fibrous substrate through the medium of said polyaluminum chloride as a binder, and production thereof.
Description
ABSORBENT COMPOSITE AND METHOD FOR P~ODUCTION THEREOF
BACKGROUND OF THE INVENTION
Field o~ the Invention:
This invention relates to an absorbent compo~ite and a method for the production thereof. More particularly, it relates to an absorbent composite which has an absorbent polymer fixed so firmly on a fibrous substrate a~ to remain in~eparably on the fibrous substrate even aft~r it ha~
absorbed an aqueous liquid and con~equently as~umed the state of a hydrated gel and, therefore, advantageously fitq applications manifestation of' an ability to absorb and retain water and to a method for the production of the absorbent composite.
Description oP the Prior Art:
In recent years, absorbent polymer~ capable of absorbing water in amounts some ten to some hundred times their own weights have been developed and have been finding extensive utility in the agricultural and ~oreqtal field and the civil engineering field as well as in the sanitary ~ield covering disposable diapers and sanitary napkins.
These absorbent polymers are ~enerally in a powdery form. Since these absorbent polymers exhibit no sufficient absorbing speed when they are used by themselves, conversion of these absorbent polymers into composites by the oombination thereof with various ~ibrous substrates has been proposed [Japanese Patent Laid-Open SHO 56(1981)-129,165, Japanese Patent Laid-Open SHO 55(1980)-148, 1549 Japanese Patent Laid-Open SHO 56(1981)-2,163, Japanese Patent Laid-Open SHO 58(1983)-131,133, Japanese Patent Laid Open SHO
58(1983)-84,804, Japanese Patent Laid-Open SHO 59(1984)-86,657, Japanese Patent Laid-Open SHO 61(1986)-62,463 9 and Japanese Patent Laid-Open SHO 63(1988)-63,723].
The conversion of such absorbent polymers into the composites which resorts exclusively to the deposition of absorbent polymers on fibrous substrates is effective in improving the absorbent polymers' absorbing speed. The produced composites, under the conditlon~ of their actual use, are de~icient in capacity and speed of absorption under application of pressure. Particularly the absorbent compositeæ produced by the conventional methods resorting to deposition of absorbent polymers on fibrous substrates hav~ a disadvantage that the hyclra~ced gels o~ absorbent polymers resulting from absorption of an aqueous liquid are readily separable from the ~ibrous sub~trates.
An object of an a~pect of this invention, there-fore, is to provide a novel absorbent composite and a method for the production o~ the absorbent composite.
An object o~ an aspect o~ this invention is to provide an absorbent composite having an absorbent polymer fixed firmly on a fibrous substrate and exhibiting a notably improved capacity for absorption under application of pres~ure and a method for the production o~ the absorbent composite.
An object of an aspect of thi~ invention is to provide an absorbert composite whicll has an absorbent polymer fixed so firmly on a fibrous substrate that aven a~ter the absorbent polymer is converted into a hydrated g~l in consequenc~ of absorption of an aqueous liquid, the absorbent polymer now in the form of the hydrated gel remains insep~ra~ly on the fibrous substrate and a method for the production of the absorbent composite.
SUMMARY OF T~E INVENTION
The objects described above are accomplished by an absorbent composite comprising 100 part~ by weight of an absorbent polymer, 1 to 600 parts by weight of a fibrous substrate, and 0.1 to 50 parts by weight of polyaluminum chloride and having the absorbent polymer adjoined to and fixed on the fibrou~ substrate through the medium of the polyaluminum chloride as a binder.
These objects are also accomplished by a method for the production of an absorbent oom~osite, which comprisas causing 100 parts by weight of an absorbent polymer to contact 1 to 600 parts by weight of a fibrous substrate in the presence of an aqueous li~uid containing 0.1 to 50 parts by weight of polyaluminum chloride.
This invention has originated in a new kno~ledge that polyaluminum chloride is particularly useful as a binder for ~ixing an absorbent polymer on a ~ibrou~
substrate. In accordance with this invention, an absorbent composite po3sessing heretofore unattainable excellent absorption characteri~tics and exhibiting an ability to retain the shape thereof even after absorption of an aqueous liquid is obtained by uniting polyaluminum chloride and a fibrous substrate with an absorbent polymer in a ~peci~ic quantitative ratio in the presence of an aqueous liquid.
The absorbent composite of this invention, owing to the synergistic effect produced by the absorbent polymer, the polyaluminum chloride, and the fibrous substrate in the united mass, enjoys generous improvement in capacity and speed of absorption under pressure. Thus, it possesqes heretofore unattainable excellent absorption characteristics.
The absorbent composite of this invention, therefore, can be combined with some other material capable of absorbing, diffusing, and retaining an aqueous liquid and, in the combined state, utilized advantageously in sanitary articles as absorbents represented by sanitary napkins and disposable diapers. It is also utilizable advantageously in various applications necessitating retention and absorption of water such as are found in medical ~ield, agricultural and horticultural field, civil engineering ~ield, food processing field, and other industrial fields.
BRIEF DESCRIPTION OF THE DRAWIN&
Fig. 1 is a schematic explanatory diagram of a device for deter~ining the absorbing capacity of an absorbent composite under application of pressure.
EXPLANATION OF THE PREFER~ED EMBODIMENT
The term "ab~orbent polymer" as used in the pre~ent invention refers to a polymer of the type which, on exposure to water, swells and f'orms a hydrated gel (hydrogel) by absorbing a large amount of' water. The absorbent polymers which answer this description include a hydrolyzed ~taroh-acr~lonitrile graft copolymer, a neutralized starch-acrylic acid graft copolymer, a saponified aorylic ester-vinyl acetate copolymer, a hydrolyzed acrylonitrile oopolymer or acrylamide copolymer, a modified cros~ linked polyvinyl alcohol, a neutralized self'-cross-linking polyacrylic acid, a oross-llnked polyacrylate salt, and a neutralized cross-lin~ed isobutylene-maleic anhydride copolymer, for example.
Since these absorbent polymers generally form a hydrogel, they possess a cross-linked structure in their polymers.
For this invention, the absorbent polymers possessing a uniform cross linking density and those having a cross linking density heightened in the surf'ace region by a surface treatment are both usable.
In these absorbent polymers, cross-linked polymers of water-soluble ethylenically unsaturated monomers having acrylic acid (or a salt thereof) as a main component thereof prove to be particularly desirable. In these cross-linked polymers, cross-linked copolymers of` acrylic acid with acrylate salt (molar ratio in the range of' 5 : 95 to 50 :
50) and partially neutralized crosY-linked polyacrylic acid (neutrali~ation ratio in the range of ~0 to 95 mol%) are particularly desirable. The salt as comonomers in the copolymers mentioned above is desired to be salt of' such alkali metals as sodium and potassium and ammonium salt.
The form of such an absorbent polymer is not critical. When the absorbent polymer is in the form of powder, granules~ fibers~ or sheet, f'or example, it can be used safely for the production of the compssit~ contemplated by this invention.
The polyaluminum chloride to be used in this invention is the product of polymerization of basic aluminum 5~
chloride and is represented by the general formula, [Al2 (OH)n Cl6_n]m, wherein n satisfies 1 < n C 5 and m ~atisfies m ~ 10.
The amount of this polyaluminum chloride to be used in the absorbent composite is in the range of 0.1 to 50 parts by weight, preferably 1 to 30 parts by weight, based on 100 parts by weight o~ the absorbent polymer. If thi~
amount is less than 0.1 parl; by weight, an absorbent composite having an absorbent polymer fixed flrmly on a fibrous substrate is not obtained. I~ thi~ amount exceeds 50 parts by weight, the amount oP the ad~orbent polymer to be incorporated in the absorbent oomposite proportionately decreases and the saturated absorption capacity of the produced absorbent composite is not su~ficient.
The flbrous substrates which are usable in this invention include synthetic fibers of polyamide, polyacrylonitrile, polyester, and polyurethane and cellulose fibers of cotton, rayon, and pulp, for example. These fibers are used in the form of long-staple fiber~ or short-staple fibers or in the form of sheets such as paper, non-woven fabric, woven fabric, and knitted fabric which are obtained by molding or interlacing such fibers.
The amount of the fibrous substrate to be incorporated in the absorbent composite is in the range of 1 to 600 parts by weight, preferably 2 to 300 parts by weight, based on 100 parts by weight of the absorbent polymer. If this amount is less than 1 part by weight, the produced absorbent composite is deficient in the absorption speed.
If the amount exceeds 600 parts by weight, the absorption capacity exhibited by the produced absorbent composite under application of pressure is unduly low.
The absorbent composite of this invention is obtained by mutual adhesion of the absorbent polymer and the fibrous substrate through the medium of the polyaluminum chloride as a binder component. This mutual adhesion is accomplished by causing the absorbent polymer and the fibrous substrate to contact the polyaluminum chloride in a prescribed ratio in the presence of an aqueous liquid. This procedure, when necessary, may further comprise a qtep oP
drying or compression molding.
The specific methods by which the production of the abqorbent composite of this invention is attained include those indicated below, for example.
(1) A method which comprises mixing the absorbent polymer with a solution containing the polyaluminum chloride, spreading or spraying the re~ultant mixed ~olution on the fibrous substrate7 and thereafter drying the re~ultant composite desirably at a temperature in the range o~ 60 to 180C.
(2) A method which comprises immersing the fibrous substrate in the mixed solution prepared in the method of (1), then removing the substrate from the mixed solution, and drying the wet substrate.
BACKGROUND OF THE INVENTION
Field o~ the Invention:
This invention relates to an absorbent compo~ite and a method for the production thereof. More particularly, it relates to an absorbent composite which has an absorbent polymer fixed so firmly on a fibrous substrate a~ to remain in~eparably on the fibrous substrate even aft~r it ha~
absorbed an aqueous liquid and con~equently as~umed the state of a hydrated gel and, therefore, advantageously fitq applications manifestation of' an ability to absorb and retain water and to a method for the production of the absorbent composite.
Description oP the Prior Art:
In recent years, absorbent polymer~ capable of absorbing water in amounts some ten to some hundred times their own weights have been developed and have been finding extensive utility in the agricultural and ~oreqtal field and the civil engineering field as well as in the sanitary ~ield covering disposable diapers and sanitary napkins.
These absorbent polymers are ~enerally in a powdery form. Since these absorbent polymers exhibit no sufficient absorbing speed when they are used by themselves, conversion of these absorbent polymers into composites by the oombination thereof with various ~ibrous substrates has been proposed [Japanese Patent Laid-Open SHO 56(1981)-129,165, Japanese Patent Laid-Open SHO 55(1980)-148, 1549 Japanese Patent Laid-Open SHO 56(1981)-2,163, Japanese Patent Laid-Open SHO 58(1983)-131,133, Japanese Patent Laid Open SHO
58(1983)-84,804, Japanese Patent Laid-Open SHO 59(1984)-86,657, Japanese Patent Laid-Open SHO 61(1986)-62,463 9 and Japanese Patent Laid-Open SHO 63(1988)-63,723].
The conversion of such absorbent polymers into the composites which resorts exclusively to the deposition of absorbent polymers on fibrous substrates is effective in improving the absorbent polymers' absorbing speed. The produced composites, under the conditlon~ of their actual use, are de~icient in capacity and speed of absorption under application of pressure. Particularly the absorbent compositeæ produced by the conventional methods resorting to deposition of absorbent polymers on fibrous substrates hav~ a disadvantage that the hyclra~ced gels o~ absorbent polymers resulting from absorption of an aqueous liquid are readily separable from the ~ibrous sub~trates.
An object of an a~pect of this invention, there-fore, is to provide a novel absorbent composite and a method for the production o~ the absorbent composite.
An object o~ an aspect o~ this invention is to provide an absorbent composite having an absorbent polymer fixed firmly on a fibrous substrate and exhibiting a notably improved capacity for absorption under application of pres~ure and a method for the production o~ the absorbent composite.
An object of an aspect of thi~ invention is to provide an absorbert composite whicll has an absorbent polymer fixed so firmly on a fibrous substrate that aven a~ter the absorbent polymer is converted into a hydrated g~l in consequenc~ of absorption of an aqueous liquid, the absorbent polymer now in the form of the hydrated gel remains insep~ra~ly on the fibrous substrate and a method for the production of the absorbent composite.
SUMMARY OF T~E INVENTION
The objects described above are accomplished by an absorbent composite comprising 100 part~ by weight of an absorbent polymer, 1 to 600 parts by weight of a fibrous substrate, and 0.1 to 50 parts by weight of polyaluminum chloride and having the absorbent polymer adjoined to and fixed on the fibrou~ substrate through the medium of the polyaluminum chloride as a binder.
These objects are also accomplished by a method for the production of an absorbent oom~osite, which comprisas causing 100 parts by weight of an absorbent polymer to contact 1 to 600 parts by weight of a fibrous substrate in the presence of an aqueous li~uid containing 0.1 to 50 parts by weight of polyaluminum chloride.
This invention has originated in a new kno~ledge that polyaluminum chloride is particularly useful as a binder for ~ixing an absorbent polymer on a ~ibrou~
substrate. In accordance with this invention, an absorbent composite po3sessing heretofore unattainable excellent absorption characteri~tics and exhibiting an ability to retain the shape thereof even after absorption of an aqueous liquid is obtained by uniting polyaluminum chloride and a fibrous substrate with an absorbent polymer in a ~peci~ic quantitative ratio in the presence of an aqueous liquid.
The absorbent composite of this invention, owing to the synergistic effect produced by the absorbent polymer, the polyaluminum chloride, and the fibrous substrate in the united mass, enjoys generous improvement in capacity and speed of absorption under pressure. Thus, it possesqes heretofore unattainable excellent absorption characteristics.
The absorbent composite of this invention, therefore, can be combined with some other material capable of absorbing, diffusing, and retaining an aqueous liquid and, in the combined state, utilized advantageously in sanitary articles as absorbents represented by sanitary napkins and disposable diapers. It is also utilizable advantageously in various applications necessitating retention and absorption of water such as are found in medical ~ield, agricultural and horticultural field, civil engineering ~ield, food processing field, and other industrial fields.
BRIEF DESCRIPTION OF THE DRAWIN&
Fig. 1 is a schematic explanatory diagram of a device for deter~ining the absorbing capacity of an absorbent composite under application of pressure.
EXPLANATION OF THE PREFER~ED EMBODIMENT
The term "ab~orbent polymer" as used in the pre~ent invention refers to a polymer of the type which, on exposure to water, swells and f'orms a hydrated gel (hydrogel) by absorbing a large amount of' water. The absorbent polymers which answer this description include a hydrolyzed ~taroh-acr~lonitrile graft copolymer, a neutralized starch-acrylic acid graft copolymer, a saponified aorylic ester-vinyl acetate copolymer, a hydrolyzed acrylonitrile oopolymer or acrylamide copolymer, a modified cros~ linked polyvinyl alcohol, a neutralized self'-cross-linking polyacrylic acid, a oross-llnked polyacrylate salt, and a neutralized cross-lin~ed isobutylene-maleic anhydride copolymer, for example.
Since these absorbent polymers generally form a hydrogel, they possess a cross-linked structure in their polymers.
For this invention, the absorbent polymers possessing a uniform cross linking density and those having a cross linking density heightened in the surf'ace region by a surface treatment are both usable.
In these absorbent polymers, cross-linked polymers of water-soluble ethylenically unsaturated monomers having acrylic acid (or a salt thereof) as a main component thereof prove to be particularly desirable. In these cross-linked polymers, cross-linked copolymers of` acrylic acid with acrylate salt (molar ratio in the range of' 5 : 95 to 50 :
50) and partially neutralized crosY-linked polyacrylic acid (neutrali~ation ratio in the range of ~0 to 95 mol%) are particularly desirable. The salt as comonomers in the copolymers mentioned above is desired to be salt of' such alkali metals as sodium and potassium and ammonium salt.
The form of such an absorbent polymer is not critical. When the absorbent polymer is in the form of powder, granules~ fibers~ or sheet, f'or example, it can be used safely for the production of the compssit~ contemplated by this invention.
The polyaluminum chloride to be used in this invention is the product of polymerization of basic aluminum 5~
chloride and is represented by the general formula, [Al2 (OH)n Cl6_n]m, wherein n satisfies 1 < n C 5 and m ~atisfies m ~ 10.
The amount of this polyaluminum chloride to be used in the absorbent composite is in the range of 0.1 to 50 parts by weight, preferably 1 to 30 parts by weight, based on 100 parts by weight o~ the absorbent polymer. If thi~
amount is less than 0.1 parl; by weight, an absorbent composite having an absorbent polymer fixed flrmly on a fibrous substrate is not obtained. I~ thi~ amount exceeds 50 parts by weight, the amount oP the ad~orbent polymer to be incorporated in the absorbent oomposite proportionately decreases and the saturated absorption capacity of the produced absorbent composite is not su~ficient.
The flbrous substrates which are usable in this invention include synthetic fibers of polyamide, polyacrylonitrile, polyester, and polyurethane and cellulose fibers of cotton, rayon, and pulp, for example. These fibers are used in the form of long-staple fiber~ or short-staple fibers or in the form of sheets such as paper, non-woven fabric, woven fabric, and knitted fabric which are obtained by molding or interlacing such fibers.
The amount of the fibrous substrate to be incorporated in the absorbent composite is in the range of 1 to 600 parts by weight, preferably 2 to 300 parts by weight, based on 100 parts by weight of the absorbent polymer. If this amount is less than 1 part by weight, the produced absorbent composite is deficient in the absorption speed.
If the amount exceeds 600 parts by weight, the absorption capacity exhibited by the produced absorbent composite under application of pressure is unduly low.
The absorbent composite of this invention is obtained by mutual adhesion of the absorbent polymer and the fibrous substrate through the medium of the polyaluminum chloride as a binder component. This mutual adhesion is accomplished by causing the absorbent polymer and the fibrous substrate to contact the polyaluminum chloride in a prescribed ratio in the presence of an aqueous liquid. This procedure, when necessary, may further comprise a qtep oP
drying or compression molding.
The specific methods by which the production of the abqorbent composite of this invention is attained include those indicated below, for example.
(1) A method which comprises mixing the absorbent polymer with a solution containing the polyaluminum chloride, spreading or spraying the re~ultant mixed ~olution on the fibrous substrate7 and thereafter drying the re~ultant composite desirably at a temperature in the range o~ 60 to 180C.
(2) A method which comprises immersing the fibrous substrate in the mixed solution prepared in the method of (1), then removing the substrate from the mixed solution, and drying the wet substrate.
(3) A method which comprises mixing the fibrous substrate and the absorbent polymer with a solution containing the polyaluminum chloride, molding the resultant mixture in the form of sheet, and drying the resultant sheet.
(4) A method which comprises dry mixing the fibrous substrate with the ab~orbent polymer, adding a solution containing the polyaluminum chloride to the resultant mixture, and, if necessary, drying the resultant composite.
(5) A method which comprises dry mixing the fibrous substrate, the absorbent polymer, and the polyaluminum chloride, adding an aqueous liquid or steam to the resultant mixture, and~ if necessary, drying the resultant composite.
(6) A method which comprises mixing the absorbent polymer thoroughly swelled in advance with an aqueous liquid with the polyaluminum chloride and the fibrous substrate, and drying the resultant composite.
(7) A method which comprises dr~ mixing the absrobent polymer and the polyaluminum chloride, mixing the resultant mixture with the fibrous substrate wetted in advance with an s~)~
aqueous liquid, and optionally drying the resultant composite.
aqueous liquid, and optionally drying the resultant composite.
(8) A method which comprises mixing the absorbent polymer with the fibrous substrate wetted in advance with an aqueous solution of the polyaluminum chloride and optionally drying the resultant mixture.
Optionally, during the dryin~ of the produced composite in these methods, a press may be used in order for the composite to be simultaneQusly dried and compression molded.
The aqueous liquid to be used in this invention has no particular restriction except for the sole requirement that it should be capable of dissolving the polyaluminum chloride. The aqueous liquids which are usable hersin include water and mixed solutions of water with hydrophilic organic solvents such as methanol and ethanol, for example.
Optionally, the aqueous liquid may incorporate therein deodorant, antioxidant, antifungal agent, fungicide, herbicide, fertilizer, perfume, ultraviolet absorbent, etc.
to suit the purpose for which the absorbent composite is used. Further, the aqueous liquid may contain a thickening agent such as hydroxyethyl cellulose and methyl cellulose in order to improve the coat-workability.
Now, the present invention will be described more specifically below with reference to working examples. It should be noted, however, that this invention is not limited in any respect to these examples. The magnitudes of the capacity for absorption, the amount of absorption under application of pressure, and the ratio of separation of absorbent polymer mentioned hereinafter are those determined respectively by the methods indicated below.
(1) Capacity of absorbent composite for absorption This property was determined by keeping about 0.2 g ~WO) of a sample absorbent composite stirred and immersed in 200 g of physiological saline solution for 30 minutes, then collecting the swelled absorbent composite on tissue paper to be drained therewith, and ohecking the weight (W) of the drained absorbent composite.
The capaciky of the absorbent composite f'or absorption was calculated in accordance with the following ~ormula using the found weight (W).
Capacity for absorption (g/g) = W/WO
wherein WO is the weight of the absorbent composite before the absorption and W is the weight of the absorbent composite after the absorption.
(2) Ratio of separation of absorbent polymer This property was determined by removing the swelled absorbent composite obtained in the procedure of (1), filtering the residual ph~siological saline solution thereby collecting the hydrated gel of the absorbed polymer separated from the ~ibrous substrate and dispersed in the physiological saline solution, and taking the dry weight of this gel.
This ratio of separation of the absorbent polymer was calculated in accordance with the following formula using the found weight.
Ratio of separation of absorbent polymer (% by weight) -Weight of separated polymer (g) - -- --- x 100 Weight of polymer adhering to fibrous substrate (g) (3) Amount of absorption under application of pressure This property was determined by the use of a device configured as illustrated in Fig. 1. This determination was performed by f`irst placing artificial urine (aqueous solution containin~ 1.9% by weight of' urea, 0.8~ by weight of sodium chloride, 0.1% by weight of calcium chloride, and 0.1% by weight of magnesium sulfate) 7 in a buret 1, closing a cock 8 in the upper inlet of the buret, setting a measuring base 2 on the same level as a closed air inlet 3 to the buret, opening the air inlet 3 of the buret 1, mounting 0.3 g of a sample absorbent composite 5 interposed between two opposed cireular sheets of filter paper (Toyo 2~
Filter Paper No. 2) 9 measuring 9 cm in diameter on a glas~
filter ~ measuring 90 mm in diameter laid on the measuring base 2, exerting a load 6 (20 g/cm2) measuring 9 cm in diameter on the sample for 10 minutes, finding the amount (W) of the artificial urine absorbed by the ~ilter paper and the absorbent composite from the scale reading of the buret, and separately finding as a blank (WO) the amou~t o~ urine similarly absorbed without use of the absorbent composite~
The amount of absorption was calculated in accordance with the following ~ormula using the found amounts.
~mount of absorption under application of pressure (ml/g) -~mount of artificial urine absorbed (W)] -[Blank amount of absorption ~WO)~
... .... _ ~
Weight of absorbent composite Referential Example 1 In an atmosphere of nitrogen gas, ~,000 parts byweight of an aq~eous 40% solution of an acrylate type monomer containing 71~. 98 mol% of sodium acrylate, 25 mol~ o~
acrylic acid, and 0.02 mol~ of trimethylol propane triacrylate was subjected to stationary polymerization using 0.5 part by weight of ammonium persul~ate and 0.1 part by weight o~ sodium hydrogan sulfite at a temperature in the range of 50 to 80C to obtain a gel-like hydrated polymer.
This gel-like hydrated polymer was dried in a hot air drier at 180C, pulverized with a hammer type pulverizer, and sifted with a 20-mesh metallic gauze to obtain a 20-mesh pass powder (hereinafter referred to as "Absorbent Polymer (1)").
Referential Example 2 In a reaction vessel, 0.7 part by weight of sorbitan monostearate was dissolved in 300 parts by weight of n-hexane. Separately, an aqueous monomer solution was prepared by dissolving 30 parts by weight of acrylic acid and 0.006 part by weight of methylene bisacrylamide in 63 parts by weight of water, neutralizing the resultant solution by the addition of 12.5 parts by weight of sodium ,r~
hydroxide, and further dissolving 0.05 part by weigh~ of potassium persulfate in the neutralized solution.
Then, the aqueous monomer solution was added to and suspended in the solution prepared as deqcribed above in the reaction vessel and the resultant suspension was polymerized under a current of` nitrogen ~as at 65C for 5 hours~ After the polymerization was completed, the polymerization product was dried under a vacuum to produce a powder (hereinafter referred to as "Absorbent Polymer (2)").
Example 1 In a liquid obtained by mixing 100 parts by weight of Absorbent Polymer (1) with 10 parts by weight of polyaluminum chloride, (manufactured by Kishida Kagaku l~.K.), 600 parts of methanol, and 1,000 parts by weight of water, 60 parts by weight of a polyester nonwoven fabric having a basis weight of 32 g/m2 was immersed. The wet non-woven fabric was pulled out on a metallic gauze and left draining thereon. The drained fabric was dried in a hot air drier at 120C for 10 minutes to obtain an Absorbent Composite (1).
The absorbent composite (1) thus obtained was found to have a basis weight of 80 g/m2.
Example 2 A liquid obtained by mixing 200 parts by weight of Absorbent Polymer (2) with 20 parts by weight of polyaluminum chloride, 600 parts by weight of methanol, and 1,000 parts by weight of water was applied to a polyester non-woven fabric having a basis weight of 32 g/m2. The resultant coated fabric was dried in a hot air drier at 120C for 15 minutes, to obtain an Absorbent Composite (2).
The absorbent composite (2) thus obtained was found to have a basis weight of 130 g/~2 Example 3 In a liquid obtained by mixing 100 parts by weight of Absorbent Polymer (2) with 20 parts by weight of polyaluminum chloride, 600 parts by weight of ethanol, and 1,000 parts by weight of water, 80 parts by weight of a wood pulp fiber sheet having a basis weight o~ 40 g/m2 and a thickness of 1 mm was immersed" The wet sheet was pulled out on a metallic gauze and left draining thereon~ The drained sheet was vacuum dried at 80C to obtain an Absorbent Composite (3).
The absorbent composite (3) thus obtained was found to have a basis weight of 90 g/m2.
Exatnple ll An Absorbent Composite (4) was obtained by mixing 100 parts of fluff pulp with 1,000 parts b~ weight o~ an aqueous 2 wt% polyaluminum chloride solution thereby preparing a pulp slurry, mixing this pulp slurry with 10~
parts by weight o~ Absorbent Polymer (2), and then vacuum drying the slurry at 120C.
Example 5 An Absorbent Composite (5) was obtained by mixing lO0 parts by ~eight o~ an aqueous 2 wt% pulp slurry prepared in advance by disintegrating vir~in pulp in water with 150 parts by weight o~ ethanol, 0.25 part by weight of polyaluminum chloride, and 1.0 part by weight of Absorbent Polymer (2), molding the resultant mixed solution in the form of sheet on a 200-mesh metallic gau~e, and drying the resultant sheet at 120C ~or 5 minutes.
Examples 6 to 9 Absorbent Composites (6), (7), (8), and (9) were obtained by following the procedure o~ Example 1, except that the amount o~ polyaluminum chloride to be used was changed respectively to 30 7 20 7 5, and 1 part by weight.
The physical propert.ies o~ the absorbent composites were as shown in Table 1.
The absorbent composites (6), (7), (8), and (9) invariably had a basis weight of 80 g/m2.
Control l 2~5~
An Absorbent Composite (1) for Comparison wa~
obtained by following the procedure of Example 1, except that the use of polyaluminum chloride was omitted.
The absorbent composite (1) for comparison was found to have a basis weight of 60 g/m2.
Control 2 An Absorbent Composike (2) for compari~on wa~
obtained by following the procedure of Example 9, except that 1 part by weight of aluminum chloride wa9 u~ed in th~
place of 1 part by weight of polyaluminum chlori~e.
The absorbent composite (2) for comparison was ~ound to have a basis weight of 62 g/m2.
Control 3 An Absorbent Composite (3) for comparison wa~
obtained by following the procedure of Example 8, except that 5 parts by weight of polyoxyethylene glycidyl ether (produced by Nagase Kasei Kogyo K.K. and marketed under trademark designation of "Denacol EX-810") was used in the place o~ 5 parts by weight of polyaluminum chloride.
The absorbent composite (3) for comparison thus obtained was found to have a basis weight of 65 g/m2.
Example 10 An Absorbent Composi~e (10) was obtained by mixing 100 parts by weight of the absorbent polymer (2) with 20 parts by weight of polyaluminum chloride 9 600 parts by weight of methanol, 1~000 parts by weight of water/ and 8 parts by weight of methyl cellulose (produced by Shin-etsu Chemical Industry Co., Ltd. and marketed under trademark designation of "Metholose 60SH") thereby preparing a liquid, applying the liquid to 60 parts of a polyester non-woven fabric having a basis weight of 32 g/m2, and then drying the coated fabric in a hot air drier at 120C for 15 minutes.
The absorbent composite (10) thus obtained was found to have a basis weight of 82 g/m2.
Example 11 Z ~ 3 The absorbent composites (1) to (lO) and the absorbent composites (1) to (3) for comparison obtained respectively in Examples 1 to 10 and in Controls 1 to 3 were tested for capacity for absorption, amount of absorption under pressure, and ratio of separation of absorbent polymer by the methods described above.
The results were as shol~n in Table 1.
~ 3 Table 1 _ _ ._ Capacity o~ Ratio of Amount of absorbent separation absorption oomposite ~or o~ absorbent under absorption (g/g) polymer (%) pr ure ...... __ _ . _ _ ~.
Absorbent compos~te (1) 30 1 29 Absorbent composite (2) 35 2 33 Absorbent composite (3) 25 1 24 Absorbent oomposite (4) 27 l~ 25 Absorbent composite ( 5 ) 20 0 . 7 18 Absorbent composite ( 6 ) 23 0 . 5 22 Absorbent composite (7) 29 0.8 25 Absorbent composite (8) 35 1.3 28 Absorbent composite (9) 40 3 30 Absorbent composite (lO) 29 1 . 1 27 .... _ _ ..... ... _ Absorbent composite for comparison (l) _ lO0 10 Absorbent composite for comparison ( 2 ) _ 1 13 Absorbent composite for comparison ( 3 ) 15 3 1 ~ _ 14
Optionally, during the dryin~ of the produced composite in these methods, a press may be used in order for the composite to be simultaneQusly dried and compression molded.
The aqueous liquid to be used in this invention has no particular restriction except for the sole requirement that it should be capable of dissolving the polyaluminum chloride. The aqueous liquids which are usable hersin include water and mixed solutions of water with hydrophilic organic solvents such as methanol and ethanol, for example.
Optionally, the aqueous liquid may incorporate therein deodorant, antioxidant, antifungal agent, fungicide, herbicide, fertilizer, perfume, ultraviolet absorbent, etc.
to suit the purpose for which the absorbent composite is used. Further, the aqueous liquid may contain a thickening agent such as hydroxyethyl cellulose and methyl cellulose in order to improve the coat-workability.
Now, the present invention will be described more specifically below with reference to working examples. It should be noted, however, that this invention is not limited in any respect to these examples. The magnitudes of the capacity for absorption, the amount of absorption under application of pressure, and the ratio of separation of absorbent polymer mentioned hereinafter are those determined respectively by the methods indicated below.
(1) Capacity of absorbent composite for absorption This property was determined by keeping about 0.2 g ~WO) of a sample absorbent composite stirred and immersed in 200 g of physiological saline solution for 30 minutes, then collecting the swelled absorbent composite on tissue paper to be drained therewith, and ohecking the weight (W) of the drained absorbent composite.
The capaciky of the absorbent composite f'or absorption was calculated in accordance with the following ~ormula using the found weight (W).
Capacity for absorption (g/g) = W/WO
wherein WO is the weight of the absorbent composite before the absorption and W is the weight of the absorbent composite after the absorption.
(2) Ratio of separation of absorbent polymer This property was determined by removing the swelled absorbent composite obtained in the procedure of (1), filtering the residual ph~siological saline solution thereby collecting the hydrated gel of the absorbed polymer separated from the ~ibrous substrate and dispersed in the physiological saline solution, and taking the dry weight of this gel.
This ratio of separation of the absorbent polymer was calculated in accordance with the following formula using the found weight.
Ratio of separation of absorbent polymer (% by weight) -Weight of separated polymer (g) - -- --- x 100 Weight of polymer adhering to fibrous substrate (g) (3) Amount of absorption under application of pressure This property was determined by the use of a device configured as illustrated in Fig. 1. This determination was performed by f`irst placing artificial urine (aqueous solution containin~ 1.9% by weight of' urea, 0.8~ by weight of sodium chloride, 0.1% by weight of calcium chloride, and 0.1% by weight of magnesium sulfate) 7 in a buret 1, closing a cock 8 in the upper inlet of the buret, setting a measuring base 2 on the same level as a closed air inlet 3 to the buret, opening the air inlet 3 of the buret 1, mounting 0.3 g of a sample absorbent composite 5 interposed between two opposed cireular sheets of filter paper (Toyo 2~
Filter Paper No. 2) 9 measuring 9 cm in diameter on a glas~
filter ~ measuring 90 mm in diameter laid on the measuring base 2, exerting a load 6 (20 g/cm2) measuring 9 cm in diameter on the sample for 10 minutes, finding the amount (W) of the artificial urine absorbed by the ~ilter paper and the absorbent composite from the scale reading of the buret, and separately finding as a blank (WO) the amou~t o~ urine similarly absorbed without use of the absorbent composite~
The amount of absorption was calculated in accordance with the following ~ormula using the found amounts.
~mount of absorption under application of pressure (ml/g) -~mount of artificial urine absorbed (W)] -[Blank amount of absorption ~WO)~
... .... _ ~
Weight of absorbent composite Referential Example 1 In an atmosphere of nitrogen gas, ~,000 parts byweight of an aq~eous 40% solution of an acrylate type monomer containing 71~. 98 mol% of sodium acrylate, 25 mol~ o~
acrylic acid, and 0.02 mol~ of trimethylol propane triacrylate was subjected to stationary polymerization using 0.5 part by weight of ammonium persul~ate and 0.1 part by weight o~ sodium hydrogan sulfite at a temperature in the range of 50 to 80C to obtain a gel-like hydrated polymer.
This gel-like hydrated polymer was dried in a hot air drier at 180C, pulverized with a hammer type pulverizer, and sifted with a 20-mesh metallic gauze to obtain a 20-mesh pass powder (hereinafter referred to as "Absorbent Polymer (1)").
Referential Example 2 In a reaction vessel, 0.7 part by weight of sorbitan monostearate was dissolved in 300 parts by weight of n-hexane. Separately, an aqueous monomer solution was prepared by dissolving 30 parts by weight of acrylic acid and 0.006 part by weight of methylene bisacrylamide in 63 parts by weight of water, neutralizing the resultant solution by the addition of 12.5 parts by weight of sodium ,r~
hydroxide, and further dissolving 0.05 part by weigh~ of potassium persulfate in the neutralized solution.
Then, the aqueous monomer solution was added to and suspended in the solution prepared as deqcribed above in the reaction vessel and the resultant suspension was polymerized under a current of` nitrogen ~as at 65C for 5 hours~ After the polymerization was completed, the polymerization product was dried under a vacuum to produce a powder (hereinafter referred to as "Absorbent Polymer (2)").
Example 1 In a liquid obtained by mixing 100 parts by weight of Absorbent Polymer (1) with 10 parts by weight of polyaluminum chloride, (manufactured by Kishida Kagaku l~.K.), 600 parts of methanol, and 1,000 parts by weight of water, 60 parts by weight of a polyester nonwoven fabric having a basis weight of 32 g/m2 was immersed. The wet non-woven fabric was pulled out on a metallic gauze and left draining thereon. The drained fabric was dried in a hot air drier at 120C for 10 minutes to obtain an Absorbent Composite (1).
The absorbent composite (1) thus obtained was found to have a basis weight of 80 g/m2.
Example 2 A liquid obtained by mixing 200 parts by weight of Absorbent Polymer (2) with 20 parts by weight of polyaluminum chloride, 600 parts by weight of methanol, and 1,000 parts by weight of water was applied to a polyester non-woven fabric having a basis weight of 32 g/m2. The resultant coated fabric was dried in a hot air drier at 120C for 15 minutes, to obtain an Absorbent Composite (2).
The absorbent composite (2) thus obtained was found to have a basis weight of 130 g/~2 Example 3 In a liquid obtained by mixing 100 parts by weight of Absorbent Polymer (2) with 20 parts by weight of polyaluminum chloride, 600 parts by weight of ethanol, and 1,000 parts by weight of water, 80 parts by weight of a wood pulp fiber sheet having a basis weight o~ 40 g/m2 and a thickness of 1 mm was immersed" The wet sheet was pulled out on a metallic gauze and left draining thereon~ The drained sheet was vacuum dried at 80C to obtain an Absorbent Composite (3).
The absorbent composite (3) thus obtained was found to have a basis weight of 90 g/m2.
Exatnple ll An Absorbent Composite (4) was obtained by mixing 100 parts of fluff pulp with 1,000 parts b~ weight o~ an aqueous 2 wt% polyaluminum chloride solution thereby preparing a pulp slurry, mixing this pulp slurry with 10~
parts by weight o~ Absorbent Polymer (2), and then vacuum drying the slurry at 120C.
Example 5 An Absorbent Composite (5) was obtained by mixing lO0 parts by ~eight o~ an aqueous 2 wt% pulp slurry prepared in advance by disintegrating vir~in pulp in water with 150 parts by weight o~ ethanol, 0.25 part by weight of polyaluminum chloride, and 1.0 part by weight of Absorbent Polymer (2), molding the resultant mixed solution in the form of sheet on a 200-mesh metallic gau~e, and drying the resultant sheet at 120C ~or 5 minutes.
Examples 6 to 9 Absorbent Composites (6), (7), (8), and (9) were obtained by following the procedure o~ Example 1, except that the amount o~ polyaluminum chloride to be used was changed respectively to 30 7 20 7 5, and 1 part by weight.
The physical propert.ies o~ the absorbent composites were as shown in Table 1.
The absorbent composites (6), (7), (8), and (9) invariably had a basis weight of 80 g/m2.
Control l 2~5~
An Absorbent Composite (1) for Comparison wa~
obtained by following the procedure of Example 1, except that the use of polyaluminum chloride was omitted.
The absorbent composite (1) for comparison was found to have a basis weight of 60 g/m2.
Control 2 An Absorbent Composike (2) for compari~on wa~
obtained by following the procedure of Example 9, except that 1 part by weight of aluminum chloride wa9 u~ed in th~
place of 1 part by weight of polyaluminum chlori~e.
The absorbent composite (2) for comparison was ~ound to have a basis weight of 62 g/m2.
Control 3 An Absorbent Composite (3) for comparison wa~
obtained by following the procedure of Example 8, except that 5 parts by weight of polyoxyethylene glycidyl ether (produced by Nagase Kasei Kogyo K.K. and marketed under trademark designation of "Denacol EX-810") was used in the place o~ 5 parts by weight of polyaluminum chloride.
The absorbent composite (3) for comparison thus obtained was found to have a basis weight of 65 g/m2.
Example 10 An Absorbent Composi~e (10) was obtained by mixing 100 parts by weight of the absorbent polymer (2) with 20 parts by weight of polyaluminum chloride 9 600 parts by weight of methanol, 1~000 parts by weight of water/ and 8 parts by weight of methyl cellulose (produced by Shin-etsu Chemical Industry Co., Ltd. and marketed under trademark designation of "Metholose 60SH") thereby preparing a liquid, applying the liquid to 60 parts of a polyester non-woven fabric having a basis weight of 32 g/m2, and then drying the coated fabric in a hot air drier at 120C for 15 minutes.
The absorbent composite (10) thus obtained was found to have a basis weight of 82 g/m2.
Example 11 Z ~ 3 The absorbent composites (1) to (lO) and the absorbent composites (1) to (3) for comparison obtained respectively in Examples 1 to 10 and in Controls 1 to 3 were tested for capacity for absorption, amount of absorption under pressure, and ratio of separation of absorbent polymer by the methods described above.
The results were as shol~n in Table 1.
~ 3 Table 1 _ _ ._ Capacity o~ Ratio of Amount of absorbent separation absorption oomposite ~or o~ absorbent under absorption (g/g) polymer (%) pr ure ...... __ _ . _ _ ~.
Absorbent compos~te (1) 30 1 29 Absorbent composite (2) 35 2 33 Absorbent composite (3) 25 1 24 Absorbent oomposite (4) 27 l~ 25 Absorbent composite ( 5 ) 20 0 . 7 18 Absorbent composite ( 6 ) 23 0 . 5 22 Absorbent composite (7) 29 0.8 25 Absorbent composite (8) 35 1.3 28 Absorbent composite (9) 40 3 30 Absorbent composite (lO) 29 1 . 1 27 .... _ _ ..... ... _ Absorbent composite for comparison (l) _ lO0 10 Absorbent composite for comparison ( 2 ) _ 1 13 Absorbent composite for comparison ( 3 ) 15 3 1 ~ _ 14
Claims (18)
1. An absorbent composite comprising 100 parts by weight of an absorbent polymer, 1 to 600 parts by weight of a fibrous substrate, and 0.1 to 50 parts by weight of polyaluminum chloride and having said absorbent polymer adjoined to and fixed on said fibrous substrate through the medium of said polyaluminum chloride as a binder.
2. An absorbent composite according to claim 1, wherein said absorbent polymer is a cross-linked polymer of a water-soluble ethylenically unsaturated monomer having acrylic acid (or a salt thereof) as a main component thereof.
3. An absorbent composite according to claim 1, wherein the amount of said fibrous substrate is in the range of 2 to 300 parts and that of said polyaluminum chloride in the range of 1 to 30 parts by weight, respectively based on 100 parts by weight of said absorbent polymer.
4. An absorbent composite according to claim 1, wherein said fibrous substrate is at least one sheetlike article selected from the group consisting of paper, nonwoven fabric, woven fabric, and knit fabric.
5. An absorbent composite according to claim 2, wherein said absorbent polymer is a cross-linked copolymer of acrylic acid with an acrylate salt (molar ratio in the range of 5 : 95 to 50 : 50).
6. An absorbent composite according to claim 2, wherein said absorbent polymer is a partially neutralized cross-linked polyacrylic acid (neutralization ratio in the range of 50 to 95 mol %).
7. A method for the production of an absorbent composite, which comprises causing 100 parts by weight of an absorbent polymer to contact 1 to 600 parts by weight of a fibrous substrate in the presence of an aqueous liquid containing 0.1 to 50 parts by weight of polyaluminum chloride.
8. A method according to claim 7, wherein said absorbent polymer is a cross-linked polymer of a water-soluble ethylenically unsaturated monomer having acrylic acid (or a salt thereof ) as a main component thereof.
9. A method according to claim 7, wherein the amount of said fibrous substrate is in the range of 2 to 300 parts and that of said polyaluminum chloride in the range of 1 to 30 parts by weight, respectively based on 100 parts by weight of said absorbent polymer.
10. A method according to claim 7, wherein said fibrous substrate is at least one sheetlike article selected from the group consisting of paper, nonwoven fabric, woven fabric, and knit fabric.
11. A method according to claim 7, wherein said aqueous liquid is water or a mixed liquid consisting of water and a hydrophilic organic solvent.
12. A method according to claim 7, which comprise mixing said absorbent polymer with a solution of said polyaluminum chloride, causing the resultant mixture to contact said fibrous substrate, and drying the resultant wet substrate.
13. A method according to claim 7, which comprises mixing said fibrous substrate and said absorbent polymer with a solution of said polyaluminum chloride, molding the resultant mixture in the form of sheet and drying the resultant sheet.
14. A method according to claim 7, which comprises dry mixing said fibrous substrate with said absorbent polymer, and adding a solution of said polyaluminum chloride to the resultant mixture.
15. A method according to claim 7, which comprises dry mixing said fibrous substrate with said absorbent polymer and said polyaluminum chloride, and adding an aqueous liquid or steam to the resultant mixture.
16. A method according to claim 7, which comprises thoroughly swelling said absorbent polymer with an aqueous liquid, mixing the resultant swelled absorbent polymer with said polyaluminum chloride and said fibrous substrate, and drying the resultant mixture.
17. A method according to claim 7, which comprises dry mixing said absorbent polymer with said polyaluminum chloride and mixing the resultant mixture with said fibrous substrate wetted in advance with an aqueous liquid.
18. A method according to claim 7, which comprises wetting said fibrous substrate with a solution of said polyaluminum chloride and mixing the resultant wettted fibrous substrate with said absorbent polymer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002009500A CA2009500A1 (en) | 1988-08-19 | 1990-02-07 | Absorbent composite and method for production thereof |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63204731A JPH0253965A (en) | 1988-08-19 | 1988-08-19 | Fixing of water-absorbing polymer to fibrous substrate |
| CA002009500A CA2009500A1 (en) | 1988-08-19 | 1990-02-07 | Absorbent composite and method for production thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2009500A1 true CA2009500A1 (en) | 1991-08-07 |
Family
ID=25673933
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002009500A Abandoned CA2009500A1 (en) | 1988-08-19 | 1990-02-07 | Absorbent composite and method for production thereof |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2009500A1 (en) |
-
1990
- 1990-02-07 CA CA002009500A patent/CA2009500A1/en not_active Abandoned
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| Date | Code | Title | Description |
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| EEER | Examination request | ||
| FZDE | Discontinued |