JP2002539315A - Absorbent polymer composition showing high absorption capacity under pressure - Google Patents

Abstract

(57) SUMMARY Disclosed in this application are absorbable polymer compositions useful for absorbing body fluids such as urine, menstrual secretions, and the like. The present invention particularly relates to a mixed-layer ion-exchange absorbent polymer composition having excellent absorption performance in terms of absorption capacity under a constraint pressure of 0.7 psi and / or 1.4 psi. Some mixed layer ion exchange absorbent polymer compositions of the present invention have compositions typical for younger babies and synthetic urine with ionic strength, as well as compositions typical for older babies and toddlers. It has excellent absorption characteristics even for high ionic strength synthetic urine having high ionic strength. The present invention also relates to an absorbent member comprising the mixed layer ion exchange absorbent polymer composition, and an absorbent product comprising the absorbent member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001] TECHNICAL FIELD This application relates to absorbent polymer compositions which exhibit a high absorption capacity under load. The present application further relates to absorbent members comprising the absorbent polymer and absorbent products comprising these absorbent members. These absorbent polymer compositions, components and products are particularly useful for absorbing body fluids such as urine and menstrual secretions.

[0002] because the background art disposable diapers, incontinence pads and pants for adults, and highly absorbent product of development for use as sanitary products such as sanitary napkins is a fairly lean subject of commercial interest. A property strongly required for such products is thinness.
For example, thin diapers are less bulky to wear, fit better under clothing and are less noticeable. Such diapers also become more compact when packaged, making it easier for consumers to carry and store diapers. The compact packaging also reduces distribution costs for manufacturers and wholesalers, including the need for smaller storage space per diaper.

Whether a thinner absorbent product such as a diaper can be provided depends on developing a relatively thin absorbent core or member capable of capturing and storing a large amount of excreted body fluids, particularly urine. It was hanging. In this regard, the use of certain absorbent polymers, often referred to as "hydrogels", "superabsorbers", "xerogels", or "hydrocolloids" was of particular importance. For example, the use of such materials (hereinafter "absorbent polymers") in absorbent products is disclosed in 1972.
U.S. Patent No. 3,699,103 issued June 13, 1972 (Harper et al.) And U.S. Patent No. 3,770,731 issued June 20, 1972 (Harmon).
Please refer to each specification. In fact, thinner diapers have been developed to take advantage of the ability of these absorbent polymers to absorb large amounts of excreted body fluids, typically when used in combination with a fibrous matrix. It was a direct result of the thinner absorbent core. For example, the U.S. Pat. No. 6,197,1987 discloses a two-layer core structure comprising a fibrous matrix and an absorbent polymer useful for making thin, compact, non-bulky diapers. Patent No. 4,67
See U.S. Pat. No. 3,402 (Weisman et al.) And U.S. Pat. No. 4,935,022 (June 19, 1990) (Lash et al.).

[0004] These absorbent polymers compare acrylic acid, alkali metal (eg sodium and / or potassium) salts of acrylic acid, or unsaturated carboxylic acids such as ammonium salts, alkyl acrylates or the like, or derivatives thereof. First polymerized in the presence of a relatively small amount of a difunctional or polyfunctional monomer such as N, N'-methylenebisacrylamide, trimethylolpropane triacrylate, ethylene glycol di (meth) acrylate or triallylamine Often made. The bifunctional or polyfunctional monomeric material serves to lightly crosslink the polymer chains, thereby making them insoluble but swellable in water. These lightly crosslinked absorbent polymers contain multiple carboxyl groups attached to the polymer backbone. These carboxyl groups provide the penetration driving force necessary for body fluid absorption by the network of crosslinked polymers. Absorbent polymers can also be made by polymerizing unsaturated amines or their derivatives in a similar manner in the presence of relatively small amounts of difunctional or polyfunctional monomers.

[0005] The degree of crosslinking of these absorbent polymers is an important factor in determining their absorption capacity and gel strength. Absorbent members and absorbent polymers useful as absorbents in absorbent products such as disposable diapers, besides appropriate absorbent capacity,
It must have a suitable high gel strength. The absorption capacity must be high enough to allow the absorbent polymer to absorb a significant amount of aqueous bodily fluids encountered during use of the absorbent product. Gel strength is related to the tendency of swollen polymer particles to deform under stress, so that the particles do not deform and do not allow the voids in the absorbent member or product to be capillary. It must be so close that it does not inhibit the rate of liquid uptake or dispersion of the liquid by the part / product. In general, the permeability of the compartment or layer comprising the swollen absorbent can be increased by increasing the crosslink density of the polymer gel and thereby increasing the gel strength. However, this also undesirably generally reduces the absorption capacity of the gel. For example, 1987
U.S. Pat. No. 4,654,039 issued March 31, 2014 (Brandt et al.) (19)
(Reissued on April 19, 1988 as U.S. Reissue Patent No. 32,649), and 19
See U.S. Patent No. 4,834,735 issued May 30, 1989 (Alemany et al.).

[0006] Many absorbent polymers may exhibit gel blocking under certain conditions. "Gel blocking" means that the particles of the absorbent polymer are deformed and unacceptably occlude the capillary cavities in the absorbent member or product, whereby the component / product This occurs when the liquid suction speed or the dispersion of the liquid is suppressed. Once gel blocking has occurred, further wicking or dispersion of the liquid takes place by a very slow diffusion process. This means that, in practical terms, gel blocking may substantially hinder the dispersion of liquids into relatively dry compartments or portions in the absorbent member or product. It means that.
Long before the particles of the absorbent polymer in the absorbent product are completely saturated, or before the liquid diffuses past the "blocking" particles to other parts of the absorbent product or is carried away. Leakage may occur from the May 30, 1989
See U.S. Pat. No. 4,834,735, issued to Alemany et al.

[0007] This gel blocking phenomenon has generally necessitated the use of a fibrous matrix with dispersed particles of an absorbent polymer. The fibrous matrix provides a capillary structure that keeps the particles of the absorbent polymer apart and allows the liquid to reach the absorbent polymer at a location remote from the point of initial excretion. U.S. Pat. No. 4,834,7, issued May 30, 1989
See No. 35 (Alemany et al.). However, dispersing the absorbent polymer at a relatively low concentration in the fibrous matrix to minimize or prevent gel blocking can significantly increase the bulk of the absorbent product or reduce the thickness of the absorbent structure. Or the body's overall liquid storage capacity may be reduced. The use of low concentrations of absorbent polymers somewhat limits the substantial benefit of these materials, namely their ability to absorb and retain large amounts of body fluids per volume.

[0008] Absorbent polymers are typically lightly cross-linked polyelectrolytes that swell primarily in aqueous solutions of simple electrolytes as a result of osmotic driving forces. The osmotic driving force for swelling the absorbent polymer is mainly generated by the counterions of the polyelectrolyte that dissociate from the polyelectrolyte but remain inside the swollen polymer because they are considered to be electrically neutral Things. Absorbing polymers that contain weakly neutral or weakly basic groups (eg, carboxylic acid groups, amine functional groups) in their unneutralized state dissociate little counterion in urine solution. In order to generate significant concentrations of dissociating counterions, these weakly acidic or weakly basic absorbing polymers must be at least partially neutralized with a base or acid, respectively. These weakly acidic or weakly basic absorbent polymers do not swell to their potential maximum absorption capacity or gel volume unless they are partially neutralized. Conversely, the absorption capacity of an absorbent polymer comprising a relatively strong acidic or basic functional group (for example, a sulfonic acid group or a quaternary ammonium hydroxide group) is not significantly affected by the degree of neutralization. However, if these strongly acidic or strongly basic absorbent polymers are used in an unneutralized state, the pH of the liquid in contact with the polymer may change to unacceptably low or high values. There is.
These polymers also tend to have relatively few functional groups per unit weight of polymer due to the high molecular weight of the repeating units. This tends to reduce the penetration driving force required for liquid absorption in these materials.

[0009] Even after neutralization, the osmotic driving force required for swelling, and thus the absorption capacity or gel volume of the polyelectrolyte-absorbing polymer, is the simple dissolved, normally present in body fluids such as urine. It is greatly reduced by the electrolyte. The concentration of the electrolyte dissolved in urine (
By lowering (eg, by diluting with distilled water) the absorption capacity of the polyelectrolyte-absorbing polymer can be greatly increased.

[0010] The concentration of the electrolyte dissolved in the aqueous solution can be significantly reduced by appropriate mixed layer ion exchange techniques. (In order to remove water ions, an ion exchange column is often used industrially.) The electrolyte concentration depends on the effect of exchanging dissolved cations (for example, Na ⁺ ) for H ⁺ ions, Anions (eg Cl ⁻ )
The OH ^- reduced by a combination of the effect of exchanging the ions. The H ⁺ ions and OH ⁻ ions effectively combine in the solution to generate H ₂ O. The degree to which a mixed-layer ion exchange system can potentially lower the electrolyte concentration depends on the ion exchange capacity of the system, the concentration of the simple electrolyte dissolved in the aqueous solution, and the ratio of the aqueous electrolyte to the ion exchange polymer. .

[0011] Ion exchange resins have been used to increase the absorption capacity of products containing absorbent polymers. See, for example, U.S. Pat. No. 4,818,598 issued to Wong on April 4, 1989; International Patent Application WO 96/15163 to Palumbo et al. Published on May 23, 1996; Palu released on May 23
International Patent Application No. WO 96/151180 by Mbo et al., JP-A-57-045057 published on March 13, 1982, and JP-A-57-035938 published on February 26, 1982. See each specification. However, ion exchange resins with relatively low ion exchange capacity, low absorption capacity, or non-absorption capacity must be added in relatively large amounts, so that generally the bulk and cost of the absorbent product is acceptable. It increases to an insignificant degree.

A mixture of an absorbent polymer containing non-neutralized acidic groups and an absorbent polymer containing non-neutralized basic groups serves as a mixed-layer ion exchange system and dissolves in the solution. May effectively reduce the concentration of simple electrolytes. When the absorbent polymer in the mixed-layer ion exchange system contains a weakly acidic group in an unneutralized state, the absorbent polymer is not neutralized, for example, by exchange of H ^{+ with} Na ^+. Change from state to neutralized state. Therefore, the penetration driving force (and thus the absorption capacity) required for swelling of the weakly acidic absorbent polymer is increased as a result of ion exchange in such a mixed layer ion exchange absorption system. Similarly, if the absorbent polymer in the mixed layer ionic exchange system contains a weakly basic groups in the state that has not been neutralized, for example, Cl ^- in accordance OH ^- by effective exchange (or,
The addition of HCl to the free amine groups) changes the absorbent polymer from an unneutralized state to a neutralized state. Therefore, the penetration driving force required for swelling of the weakly basic absorbent polymer is also increased as a result of ion exchange in the mixed-layer absorbent system. Even if virtually all of the weakly acidic groups or weakly basic groups in the absorbent polymer are neutralized (ie, completely neutralized), the pH is not always neutral. In mixed layer ion exchange systems comprising these polymers, it appears that some of the weakly acidic groups and / or basic groups are actually neutralized (ie, partially neutralized). The use of mixed layer ion exchange absorbent polymers to enhance absorption capacity has been described in International Patent Application WO 96/17681 (Palumbo, published June 13, 1996) and International Patent Application WO 96/15162 (Fornasari et al. Released May 23, 1996),
And US Patent No. 5,274,018 (Tanaka, issued December 28, 1993)
Are described in each specification.

In an absorbent member (eg, a mixture of an absorbent polymer and cellulose fibers), the absorbent polymer absorbs only a portion of the total liquid contained in the member. The remaining liquid is typically absorbed by other components (eg, in pores formed by the fibrous structure). However, even though the liquid is not absorbed by the absorbent polymer, the electrolyte dissolved in the liquid can diffuse into the absorbent polymer. Reducing the amount of fiber (or other non-absorbable polymer component capable of absorbing liquid) reduces the amount of extra solution that must be replaced to achieve a given reduction in electrolyte concentration, and therefore extra The amount of salt is minimized. Thus, mixed layer ion exchange absorbent polymer systems offer the greatest benefit in absorbent members containing relatively high concentrations of absorbent polymer in terms of maximizing absorption capacity. .

[0014] The mixed layer ion exchange absorbent polymer in the absorbent member can enhance the osmotic driving force required for swelling, but this results in an absorption capacity in terms of absorption capacity under a constraint pressure of 0.7 psi or more. The expected improvement in performance has never been achieved. It is believed that a confining pressure of 0.7 psi or greater is a typical operating pressure on the absorbent member while wearing the absorbent product. Under such constrained pressures, the previously disclosed mixed layer ion exchange absorbent polymers tend to deform and fill the capillary voids between the particles, thereby reducing the rate of liquid uptake. As a result, the absorption capacity of the previously disclosed mixed layer ion exchange absorbent polymer will not be significantly higher than that of conventional absorbent polymers under confined pressures of 0.7 psi or more.

[0015] Accordingly, it is desirable to provide a composition comprising an absorbent polymer capable of absorbing large amounts of synthetic urine solution under a constraint pressure of 0.7 psi or more. Also,
It is desirable that relatively high absorption capacities be obtained within a time generally less than the time of use of a product comprising the absorbent composition (eg, overnight). In this regard, it is desirable for the absorbent polymer to achieve high absorption capacity within, for example, 2, 4, 8, or 16 hours. It is further desired to provide an absorbent polymer system having high porosity and / or permeability and good gel layer integrity. Furthermore, it is desirable that such absorbent polymers exhibit high absorption capacity when exposed to synthetic urine having a high ionic strength typical of older babies and toddlers.

SUMMARY OF THE INVENTION The present invention relates to an absorbent material useful for containing bodily fluids such as urine. The present invention particularly relates to an absorbent material having excellent absorption performance characteristics in terms of absorption capacity under a constraint pressure of 0.7 psi and / or 1.4 psi.

The present invention, in one embodiment, provides a constraint pressure of 0.7 psi for synthetic urine solutions.
The present invention relates to a mixed-layer ion-exchange absorbent polymer composition having a performance under pressure (Performance Under Pressure, hereinafter referred to as “PUP” or “PUP capability”) of at least about 30 g / g under (4.8 kPa). is there. (A method of measuring PUP capacity over a period of time under a given pressure is described in the "Test Methods" section below.) In another aspect, the present invention provides a method for binding high ionic strength synthetic urine solutions. Absorbency under pressure (Capacity Und) after 2 hours under a pressure of 0.7 psi (4.8 kPa)
er Pressure (hereinafter referred to as “CUP”) is at least about 25 g / g. (A method of measuring CUP at a given pressure over a period of time is described in the "Test Methods" section below.)
In yet another aspect, the invention is directed to a mixed layer ion exchange absorbent polymer composition having a PUP capacity of at least about 36 g / g after 4 hours under a confined pressure of 0.7 psi (4.8 kPa). . In yet another aspect, the invention is directed to a mixed layer ion exchange absorbent polymer composition having a PUP capacity of at least about 40 g / g after 8 hours under a confined pressure of 0.7 psi. In yet another aspect,
The invention provides a PUP capacity of at least about 42 g after 16 hours under a confined pressure of 0.7 psi.
/ G of mixed layer ion exchange absorbent polymer composition. As used herein, the term "after" means immediately after.

In another aspect, the present invention provides a method comprising applying a pressure of 1.4 psi (9.6 kPa) to a pressure of 2 psi.
It is directed to a mixed layer ion exchange absorbent polymer composition having a PUP capacity after time of at least about 24 g / g. In another aspect, the present invention provides a method comprising:
. A mixed layer ion exchange absorbent polymer composition having a PUP capacity of at least about 27 g / g after 4 hours at 4 psi. In yet another embodiment, the present invention provides a method wherein the PUP capacity after 8 hours under a confined pressure of 1.4 psi is at least about 30 g.
/ G of mixed layer ion exchange absorbent polymer composition. In yet another aspect, the invention is directed to a mixed layer ion exchange absorbent polymer composition having a PUP capacity of at least about 33 g / g after 16 hours under a confined pressure of 1.4 psi.

In a preferred embodiment, the present invention provides a cation exchange absorbent polymer having a weakly acidic group in a non-neutralized state and an anion exchange absorbent polymer having a weakly basic group in a non-neutralized state. Wherein the mixture comprises P
The present invention relates to a composition exhibiting high absorption of synthetic urine solution within a time shorter than the use time (for example, overnight) of a product comprising the absorbent composition under UP and / or CUP absorption conditions. is there. In this regard, when the PUP and / or CUP capacity is measured over, for example, 2 hours, 4 hours, 6 hours, 8 hours, and / or 16 hours, the mixed layer ion exchange absorbent polymer exhibits such improved properties. The measured absorbency is shown. The present invention also relates to an absorbent member comprising the above-mentioned absorbent polymer composition, and to an absorbent product comprising such an absorbent member.

[0020] BEST MODE FOR CARRYING OUT THE INVENTION A. Definitions As used herein, the term "body fluid" includes urine, blood, menstrual discharge, and vaginal discharge.

As used herein, the term “synthetic urine solution” refers to 2.0 g of KCl in distilled water, ₂ SO₄2.0 g, NH₄H₂PO₄0.85 g, (NH₄)₂HPO₄To
0.15 g, CaCl₂・ 2H₂0.25 g of O and MgCl₂・ 6H₂O
It refers to an aqueous solution in which 0.50 g is dissolved to make a 1 liter solution.

As used herein, the term “high ionic strength synthetic urine solution” refers to the addition of KCl to distilled water.
. 0g, _Na 2 SO ₄ and 2.0 _g, the _{NH 4 H 2 PO 4 1.2g,} (NH 4) a 2 HPO ₄ 1.6 g, the _{CaCl 2 · 2H 2 O 0.20g,} MgCl 2 · 6H 2 It refers to an aqueous solution in which 0.55 g of O and 7.0 g of NaCl are dissolved to form a 1-liter solution.

As used herein, the term “ion exchange capacity” refers to the theoretical value of a polymer, assuming that each non-neutralized acidic or basic group is neutralized during the ion exchange process. Alternatively, it refers to ion exchange capacity in milliequivalents per gram calculated.

As used herein, the term “absorbent polymer” refers to a polymer that absorbs at least 10 times its weight of deionized water within the polymer, allowing the pH of the system to be adjusted.

The term “absorbent core” as used herein refers to a component of an absorbent product that is primarily concerned with the liquid handling properties of the absorbent product, including the capture, transfer, dispersion, and storage of bodily fluids. As such, the absorbent core generally does not include the topsheet or backsheet of the absorbent product.

The term “absorbent member” as used herein includes, for example, liquid capture, liquid dispersion,
Refers to components of the absorbent core that generally provide one or more liquid handling properties, such as liquid transfer, liquid storage, and the like. The absorbent member may constitute the entire absorbent core, or may constitute only a part of the absorbent core. That is, the absorbent core can comprise one or more absorbent members. The improved mixed layer ion exchange absorbent polymer compositions described herein are particularly useful for absorbent members whose primary function is to store aqueous bodily fluids. However, these compositions may be present in other absorbent members.

As used herein, the term “portion” or “compartment” refers to a portion or portion of an absorbent member with a microscopic feel.

[0028] As used herein, the term "layer" refers to a portion of an absorbent product whose basic size is along its length and width. It should be understood that the term layer is not necessarily limited to a single layer or sheet of material. To that end, the layers may be composed of several sheets or web laminates or combinations of the required type of substance. Thus, the term "layer (singular)" includes the words "layer (plural)" and "layered."

The term “comprising” as used herein means that various components, members, steps, etc., can be used in combination in accordance with the invention. Thus, the term "comprising" includes the more restrictive terms "consisting essentially of" and "consisting of." These latter terms are more restrictive, with standard meanings as understood in the art.

[0030] Percentages, ratios, and ratios used herein are, unless otherwise indicated,
All are by weight.

B. Mixed-layer ion-exchange absorbent polymer composition present invention is, in part, to a mixed-layer ion-exchange absorbent polymer compositions that exhibit very high absorbency against synthetic urine solution under load. These mixed layer ion-exchange absorbent polymer compositions comprise a mixture of an anion-exchange absorbent polymer and a cation-exchange absorbent polymer, as described in detail below.

[0032] 1. Chemical composition a. Anion exchange absorbing polymers Anion exchange absorbing polymers containing weakly basic groups include various polymers that are insoluble in water but swell with water. These are typically first, second, and / or
Alternatively, it is a lightly crosslinked polymer containing a plurality of basic functional groups such as tertiary amines or their corresponding phosphines. Examples of polymers suitable for use in the present invention include polymers made from polymerizable monomers having basic groups or groups that can be converted to basic groups after polymerization. Accordingly, such monomers include those containing primary, secondary, and / or tertiary amines, or their corresponding phosphines. Representative monomers include ethyleneimine (aziridine), allylamine, diallylamine, 4-aminobutene, alkyloxazoline, vinylformamide, 5-aminopentene, carbodiimide, formaldazine, melamine, and the like, and secondary or tertiary amine derivatives thereof. , But is not limited thereto.

In making the anion exchange absorbent polymers of the present invention, certain monomers that do not contain basic groups can also be included, although usually in small amounts. The absorbent polymers described herein may be homopolymers, copolymers (including terpolymers and higher copolymers), or mixtures of different homopolymers or copolymers. . These polymers may also be random copolymers, graft copolymers, block copolymers, and may have a linear structure or a branched structure.

Due to the relatively low degree of crosslinking, these polymers are not soluble in water but are swellable with water. This can be done by including an appropriate amount of an appropriate crosslinking monomer during the polymerization reaction. Examples of crosslinking monomers include N
, N'-methylenebisacrylamide, ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, triallylamine,
And a diaziridine compound. Alternatively, after polymerization, the polymer may be crosslinked by reacting with a suitable crosslinker such as a dihalogenated or polyhalogenated compound and / or a diepoxy or polyepoxy compound. Examples include diiodopropane, dichloropropane, ethylene glycol diglycidyl ether and the like. The crosslinks may be distributed uniformly throughout the gel particles or may be preferentially concentrated at or near the surface of the particles.

The anion exchange absorbent polymer is preferably of one type (ie, homogeneous), but a mixture of anion exchange polymers can also be used in the present invention. For example, a mixture of cross-linked polyethyleneimine and cross-linked polyallylamine can be used in the present invention.

When the anion exchange absorbent polymer is used as part of a mixed layer ion exchange composition, it may comprise from about 50% to about 100%, preferably from about 80% to about 100%, of the unneutralized base. , More preferably about 90% to about 100%.

In order to maximize the ion exchange capacity of the mixed layer ion exchange absorbent polymer composition,
Desirably, the absorbent polymer has a high ion exchange capacity per gram of dry polymer. Therefore, the ion exchange capacity of the anion exchange absorbent polymer component is preferably at least about 10 meq / g, more preferably at least about 15 meq / g, and most preferably at least about 20 meq / g.

B. Cation Exchange Absorbent Polymers Absorbent polymers useful as cation exchangers typically have multiple acidic functional groups, such as carboxylic acid groups. Examples of cation exchange polymers suitable for use in the present invention include polymers made from polymerizable monomers containing acids or monomers having functional groups that can be converted to acidic groups after polymerization. Accordingly, such monomers include olefinically unsaturated carboxylic acids, their anhydrides, and mixtures thereof. Cation exchange polymers can also include polymers that are not made from olefinically unsaturated monomers. Examples of such polymers include polysaccharide-based polymers such as carboxymethyl starch and carboxymethyl cellulose, and poly (amino acid) -based polymers such as poly (aspartic acid). See, for example, U.S. Pat. No. 5,247,068 issued to Donachy et al. On September 21, 1993 for absorbable poly (amino acid) polymers. This patent is incorporated herein by reference.

In making the cation exchange absorbent polymer of the present invention, certain non-acidic monomers can be included, usually in small amounts. Such non-acidic monomers can include, for example, monomers having the following types of functional groups. Carboxylic acid esters, sulfonic acid esters, hydroxyl groups, amide groups, nitrile groups, and aryl groups (eg, phenyl groups such as those derived from styrene monomers). Other optional non-acidic monomers include unsaturated hydrocarbons such as ethylene, propylene, 1-butene, butadiene, and isoprene. These non-acidic monomers are well known substances, for example, February 28, 1978.
No. 4,076,663 (Masda et al.), Issued on Dec. 1, and US Pat. Has been described. These two patents are described herein by reference.

The olefinically unsaturated carboxylic acid monomer and the olefinically unsaturated carboxylic acid anhydride monomer include acrylic acid itself, methacrylic acid, α-chloroacrylic acid, α-cyanoacrylic acid, β-methylacrylic acid (croton Acid), α-phenylacrylic acid, β-acryloxypropionic acid, sorbic acid, α-chlorosorbic acid, angelic acid, cinnamic acid, p-chlorocinnamic acid, β-stearylacrylic acid, itaconic acid, citraconic acid, mesacon Acids, glutaconic acid, aconitic acid, maleic acid, fumaric acid, tricarboxyethylene, and acrylic acids represented by maleic anhydride are included.

Preferred cation exchange absorbent polymers are those containing a carboxyl group.
These polymers include hydrolyzed starch-acrylonitrile graft copolymers,
Partially neutralized hydrolyzed starch-acrylonitrile graft copolymer, starch-acrylic acid graft copolymer, partially neutralized starch-acrylic acid graft copolymer, hydrolyzed vinyl acetate-acrylic ester copolymer, hydrolyzed acrylonitrile or acrylamide copolymer, any of the above copolymers And polyacrylic acid, and lightly crosslinked polyacrylic acid. These polymers can be used alone, or two,
Alternatively, it can be used in the form of a mixture of different polymers. Examples of these polymeric materials are described in U.S. Pat. No. 3,661,875, U.S. Pat.
No. 6,663, U.S. Pat. No. 4,093,776, U.S. Pat.
No. 3 and U.S. Pat. No. 4,734,478.

The most preferred polymeric materials for use in making the cation exchange absorbent polymer are lightly crosslinked polymers of polyacrylic acid and their starch derivatives. Reticulated cross-linking renders the polymer substantially insoluble in water, and to some extent determines the absorption capacity, a characteristic of the absorbent polymer, and the content of extractable polymer. Methods of network crosslinking these polymers, and typical network crosslinking agents, are described in more detail in U.S. Pat. No. 4,076,663.

The cation exchange absorbent polymer is preferably of one type (ie, homogeneous), but a mixture of cation exchange polymers can be used in the present invention. For example, a mixture of a starch-acrylic acid graft copolymer and a lightly crosslinked polyacrylic acid polymer can be used in the present invention.

When the cation exchange absorbent polymer is used as part of a mixed layer ion exchange composition, it may be in the form of an unneutralized acid in an amount of about 50% to about 100%, preferably about 8%.
0% to about 100%, more preferably about 90% to about 100%.

In order to maximize the ion exchange capacity of the mixed layer ion exchange absorbent polymer composition,
It is desirable that the cation exchange absorbent polymer has a high ion exchange capacity per gram of dry polymer. Thus, the ion exchange capacity of the cation exchange absorbent polymer component is at least about 4 meq / g, more preferably at least about 8 meq / g, even more preferably at least about 10 meq / g, and most preferably at least about 13 meq / g.
It is preferably meq / g.

C. Composition and general material properties In the mixed ion exchange absorbent polymer composition, the anion exchange capacity and the cation exchange capacity may be the same or different. For example, to offset differences in pK, to offset differences in neutralization, to change the pH of ion-exchanged urine (eg, to acidify), to absorb anion-exchange or cation-exchange absorbent polymers It may be desirable to have some equivalent to.

A mixed layer ion exchange absorbent polymer composition in a highly absorbent core cannot rely on the fluidity, agitation, etc. of the solution to help carry ions or increase the rate of ion exchange. . Therefore, it is desirable to make the particle form suitable for promoting the ion exchange activity. Desirable forms include (i) mixed layer aggregates of high surface area (eg, small and / or porous) particles with a broad or narrow particle size distribution, (ii)
A) particles comprising, for example, smaller discontinuous regions of, for example, a cation exchange absorbent polymer in the anion exchange absorbent polymer; and (iii) two particles of both the anion exchange absorbent polymer and the cation exchange absorbent polymer. Particles containing continuous regions are included.

[0048] Mixed layer ion exchange absorbent polymer compositions having the above forms can be made using various mixing techniques that are well known in the art. Specific blending techniques include high shear blending, ball mills, pin mills, and the like. As will be appreciated by those skilled in the art, the mixing and / or blending of the components may be performed before or after the drying step in the manufacturing process. Water, glycerol,
Additives, such as oils, silica, or mixtures thereof, or processing aids may be added to the components in the blend to facilitate mixing.

The absorbent polymer can also constitute a mixture containing low levels of one or more additives, such as, for example, powdered silica, surfactants, glues, binders and the like. The components in the mixture may be physically and / or chemically linked such that the absorbent polymer component and additives other than the absorbent polymer do not readily separate physically. The absorbent polymer may be essentially non-porous (ie, zero internal porosity) or may have substantially internal porosity. In a mixed layer absorbent polymer composition, one type of absorbent polymer may have a higher crosslink density than the other type of absorbent polymer.

For absorbent polymer particles useful in the present invention, the usual range of particle sizes is from about 1 to
It is about 2000 microns, more preferably about 20 to about 1000 microns. The mass median particle size is generally from about 20 to about 1500 microns, more preferably from about 50 to about 1000 microns, and even more preferably from about 100 to about 8 microns.
00 microns.

An important property of an absorbent polymer is the level of extractable components present in the polymer itself. U.S. Patent No. 4,654, issued March 31, 1987
No. 3,039 (Brandt et al.) (U.S. Pat.
(Reissued as No. 9). The disclosure content of each specification is described herein by reference. Many absorbable polymers contain significant levels of extractable polymeric material that can be leached by the body fluid from the swollen polymer matrix while the body fluid (eg, urine) is in contact with the absorbent polymer. Such polymeric substances thus extracted by bodily fluids change both the chemical and physical properties of the bodily fluids, delaying the absorption of bodily fluids by the absorbent polymer in the absorbent product, and It is considered that the retention may be insufficient. Also,
Extractable polymers are believed to be particularly detrimental in mixed-layer ion-exchange absorbent polymer systems because soluble polymers tend to migrate toward gel particles of oppositely charged polymers. These two polymers internally neutralize, thereby reducing the ion exchange capacity of the system. The extractable polymer may form ionic cross-links that reduce the ability of the gel to swell, as it effectively contains a multivalent counterion for the oppositely charged polymer.

Thus, for the ion exchange absorbent polymer of the present invention, the level of extractable polymer is preferably less than about 15%, more preferably less than about 10%, and most preferably less than about 7% of the total polymer.

[0053] 2.Physical properties a.Performance Under Pressure (PUP) By measuring the required wetness or weight absorbency, the high absorbency polymer
Obtain information about the ability of the concentration compartment or layer to absorb body fluids under working pressure
Can be. For example, U.S. Pat. No. 5,562, issued Oct. 8, 1996
No. 646 (Goldman et al.) And U.S. Pat.
599,335 (Goldman et al.). In these specifications
, The required wetness, or weight absorption, is referred to as performance under pressure (PUP). PU
In the measurement of P, an initially dry 100% strength absorbent polymer
The composition is applied to a piston / cylinder device (cylinder) under mechanical constraint pressure.
The bottom of the membrane can permeate the solution but not the absorbent polymer
No), with zero hydraulic suction and high mechanical pressure under the required absorption conditions.
Absorb the urine solution. “PUP” ability is a composition and ion concentration typical of urine in young infants.
0.032 g / cm of synthetic urine solution having a strong ² Is defined as g / g absorption by the absorbent polymer layer. PUP ability is high
This means that if absorbent polymers are used in high concentrations in absorbent products,
It is a very important property for remar.

The working pressure applied to the absorbent polymer includes a mechanical pressure (for example, a pressure applied by a user's weight or movement, a taping force, etc.) and a capillary pressure (for example, a liquid is absorbed by the absorbent polymer). (Capillary desorption pressure of the capture component in an absorbent core that temporarily holds the liquid). The total pressure of about 0.7 psi (4.8 kPa) reflects the sum of these pressures on the mixed layer absorbent polymer composition as it absorbs bodily fluids under conditions of use, and upon the polymer composition. Conceivable. However, under use conditions, both higher and lower pressures may be applied to the absorbent polymer. Accordingly, it is desirable that the mixed layer ion exchange absorbent polymers of the present invention exhibit high PUP capability at pressures up to about 1.4 psi (9.6 kPa). Preferably, a relatively high PUP performance value is obtained within a shorter time of use of the product comprising the absorbent composition (eg, overnight). In this regard, mixed layer ion exchange absorbent polymers exhibit such improved absorbency when PUP capacity is measured, for example, at 2, 4, 8, and / or 16 hours.

The method for measuring the PUP ability of these absorbent polymers is described in the Test Methods section below. This method is disclosed in U.S. Pat.
No., 562,646 (Goldman et al.) (Herein incorporated by reference), based on the procedure described in the specification, which more closely simulates the individual states in use. For this reason, modifications have been made to extend for a longer time under various desired constraint pressures.

(I) PUP Capability Under Restraint Pressure of 0.7 psi In one embodiment, the mixed layer ion exchange absorbent polymer composition of the present invention is prepared as follows .
This will be described in terms of the ability to absorb synthetic urine under a constraint pressure of 7 psi. In this regard, the present invention is directed to a mixed layer ion exchange absorbent polymer composition having a performance under pressure of at least about 30 g / g after 2 hours under a confined pressure of 0.7 psi for a synthetic urine solution. . Preferably, the PUP capacity of the polymer composition after 2 hours under a constraint pressure of 0.7 psi for a synthetic urine solution is at least about 32 g / g, more preferably at least about 35 g / g, and most preferably at least about 38g / g
It is. Typically, the P of the polymer composition after 2 hours under a constraint pressure of 0.7 psi
UP capacity is from about 30 to about 49 g / g, and more typically from about 32 to about 47 g / g.
And even more typically about 35 to about 45 g / g, even more typically about 38 to about 4 g / g.
3 g / g.

In a similar embodiment, the invention provides a confined pressure of 0.7 psi for synthetic urine solutions.
A mixed layer ion exchange absorbent polymer composition having a performance under pressure after 4 hours under at least about 36 g / g. Preferably, the PUP capacity of the polymer composition after 4 hours under a confining pressure of 0.7 psi for a synthetic urine solution is at least about 3
8 g / g, more preferably at least about 40 g / g, and most preferably at least about 42 g / g. Typically, the PUP capacity of the polymer composition after 4 hours under a constraint pressure of 0.7 psi is about 36 to about 55 g / g, more typically about 38 to about 52 g / g, and even more. Typically from about 40 to about 50 g / g, even more typically from about 42 to about 48 g / g.

In a similar embodiment, the PUP capacity of the mixed layer ion exchange absorbent polymer composition after 8 hours under a confined pressure of 0.7 psi for a synthetic urine solution is at least about 40 g.
/ G. Preferably, the PUP capacity of the polymer composition after 8 hours under a confining pressure of 0.7 psi is at least about 42 g / g, more preferably at least about 4 g / g.
4 g / g, most preferably at least about 46 g / g. Typically, the PUP capacity of the polymer composition after 8 hours under a constraint pressure of 0.7 psi is from about 40 to about 59 g /
g, more typically about 42 to about 57 g / g, even more typically about 44 g / g.
To about 55 g / g, even more typically from about 46 to about 52 g / g.

In another similar embodiment, the PUP capacity of the mixed layer ion exchange absorbent polymer composition after 16 hours under a confined pressure of 0.7 psi is at least about 42 g / g. Preferably, the PUP capacity of the polymer composition after 16 hours under a confining pressure of 0.7 psi is at least about 44 g / g, more preferably at least about 46 g / g, and most preferably at least about 48 g / g. . Typically, a confining pressure of 0.7 psi
After 16 hours, the PUP capacity of the polymer composition is from about 42 to about 61 g / g, more typically from about 44 to about 59 g / g, and even more typically from about 46 to about 57 g / g.
/ G, even more typically from about 48 to about 54 g / g.

(Ii) PUP Capability under Restraint Pressure of 1.4 psi The mixed layer ion exchange absorbent polymer composition will be described separately in terms of its ability to absorb synthetic urine under a restraint pressure of 1.4 psi. Of course, it will be appreciated that certain absorbent materials exhibit the described absorption characteristics at both 0.7 psi and 1.4 psi.

In this regard, the present invention is directed to a mixed layer ion exchange absorbent polymer composition having a PUP capacity of at least about 24 g / g after 2 hours under a confined pressure of 1.4 psi. Preferably, the PUP capacity of the polymer composition after 2 hours under a confined pressure of 1.4 psi is at least about 26 g / g, more preferably at least about 2 g / g.
8 g / g, most preferably at least about 30 g / g. Typically, the PUP capacity of the polymer composition after 2 hours under a constraint pressure of 1.4 psi is from about 24 to about 40 g /
g, more typically about 26 to about 38 g / g, and even more typically about 28 g / g.
To about 36 g / g, even more typically from about 30 to about 35 g / g.

[0062] In a similar embodiment, the PUP capacity of the mixed layer ion exchange absorbent polymer composition after 4 hours under a confined pressure of 1.4 psi is at least about 27 g / g. Preferably, the PUP capacity of the polymer composition after 4 hours under a confined pressure of 1.4 psi is at least about 29 g / g, more preferably at least about 32 g / g, and most preferably at least about 35 g / g. . Typically, under a confining pressure of 1.4 psi, 4
After time, the PUP capacity of the polymer composition is from about 27 to about 46 g / g, more typically from about 29 to about 44 g / g, even more typically from about 32 to about 42 g / g, More typically from about 35 to about 40 g / g.

In a similar embodiment, the PUP capacity of the mixed layer ion exchange absorbent polymer composition after 8 hours under a confined pressure of 1.4 psi is at least about 30 g / g. Preferably, the PUP capacity of the polymer composition after 8 hours under a confined pressure of 1.4 psi is at least about 32 g / g, more preferably at least about 35 g / g, and most preferably at least about 37 g / g. . Typically, 8 at 1.4 psi constraint pressure.
After time, the PUP capacity of the polymer composition is from about 30 to about 49 g / g, more typically from about 32 to about 47 g / g, even more typically from about 35 to about 45 g / g, More typically from about 37 to about 43 g / g.

In another similar embodiment, the PUP capacity of the mixed layer ion exchange absorbent polymer composition after 16 hours under a confined pressure of 1.4 psi is at least about 33 g / g.
Preferably, the PUP capacity of the polymer composition after 16 hours under a confined pressure of 1.4 psi is at least about 35 g / g, more preferably at least about 38 g / g,
Most preferably it is at least about 40 g / g. Typically, a confining pressure of 1.4 ps
The PUP capacity of the polymer composition after 16 hours under i is about 33 to about 52 g / g, more typically about 35 to about 50 g / g, and even more typically about 38 to about 48 g / g.
g / g, even more typically from about 40 to about 45 g / g.

B. As mentioned above, PUP capability provides important information regarding the absorption of synthetic urine by the absorbent polymer composition. It should be noted, however, that the synthetic urine used to measure PUP is based on the composition of the urine of relatively small infants. As is known, the composition of urine changes as infants grow larger, due to changes in diet, maturation of body organs, increased activity, and the like. Absorbent products are also understood to be commonly worn by such older babies and toddlers until they are trained on the toilet. Therefore, there is a need for a method of measuring the performance of an absorbent polymer composition when exposed to urine, typical of such older infants and toddlers. The CUP test described in the test method section below is one such method. "CUP" is used in substantially the same manner as "PUP" ability, except that it uses as a test solution synthetic urine having a high ionic strength and a composition typical of the urine of older babies and toddlers. Measure. Therefore "CUP"
G / cm ² of a synthetic urine solution having the composition and ionic strength typical of the urine of older babies and toddlers, with a 0.032 g / cm ² absorbent polymer layer over a period of time at a specified pressure. g absorption. As you can see, high PUP capacity and high CU
Absorbent polymer compositions having both P are particularly useful for absorbent components and products.

(I) CUP under constrained pressure of 0.7 psi .
The ability to absorb high ionic strength synthetic urine under a constraint pressure of 7 psi is further described. In this regard, the present invention provides a constraint pressure of 0,0 for high ionic strength synthetic urine solutions.
A mixed layer ion exchange absorbent polymer composition having an absorption capacity under pressure after 1 hour at 7 psi of at least about 23 g / g. Typically, a confining pressure of 0.
After 1 hour at 7 psi, the CUP of the polymer composition is from about 23 to about 35 g / g.

In a similar embodiment, a confining pressure of 0.7 ps for a high ionic strength synthetic urine solution
After 4 hours under i, the CUP of the mixed layer ion exchange absorbent polymer composition is at least about 25 g / g. Preferably, the CUP of the polymer composition after 4 hours under a constraint pressure of 0.7 psi for a high ionic strength synthetic urine solution is at least about 27 g.
/ G, more preferably at least about 30 g / g. Typically, the CUP of the polymer composition after 4 hours under a constraint pressure of 0.7 psi is from about 25 to about 35 g.
/ G, more typically from about 27 to about 33 g / g.

In another similar embodiment, a confining pressure of 0.7 for the high ionic strength synthetic urine solution
After 8 hours under psi, the CUP of the present mixed layer ion exchange absorbent polymer composition is at least about 27 g / g. Preferably, the CUP of the polymer composition after 8 hours under a confined pressure of 0.7 psi is at least about 29 g / g, more preferably at least about 31 g / g. Typically, the CUP of the polymer composition after 8 hours under a confining pressure of 0.7 psi is from about 27 to about 37 g / g, more typically from about 29 to about 33 g / g.

(Ii) CUP Mixed-Layer Ion-Exchange Absorbable Polymer Composition Under a Restraint Pressure of 1.4 psi is Separately Described from the Point of Ability to Absorb Synthetic Urine Under a Restraint Pressure of 1.4 psi. Of course, it will be appreciated that certain absorbent materials exhibit the described absorption characteristics at both 0.7 psi and 1.4 psi.

In this regard, the present invention is directed to a mixed layer ion exchange absorbent polymer composition having a CUP of at least about 20 g / g after 2 hours under a confined pressure of 1.4 psi. Preferably, the CUP of the polymer composition after 2 hours under a confining pressure of 1.4 psi is at least about 23 g / g, and more preferably at least about 27 g / g.
/ G. Typically, the CUP of the polymer composition after 2 hours under a confining pressure of 1.4 psi is from about 20 to about 35 g / g, more typically from about 23 to about 32 g / g.
g, even more typically from about 23 to about 30 g / g.

In a similar embodiment, the CUP of the present mixed layer ion exchange absorbent polymer composition after 8 hours under a confined pressure of 1.4 psi is at least about 22 g / g. Preferably, the CUP of the polymer composition after 8 hours under a confined pressure of 1.4 psi is at least about 25 g / g, more preferably at least about 27 g / g. Typically, the CUP of the polymer composition after 8 hours under a confined pressure of 1.4 psi is about 22-
About 35 g / g, more typically from about 25 to about 33 g / g.

In another similar embodiment, the CUP of the present mixed layer ion exchange absorbent polymer composition after 16 hours under a confined pressure of 1.4 psi is at least about 25 g / g. Preferably, the CUP of the polymer composition after 16 hours under a confined pressure of 1.4 psi is:
It is at least about 27 g / g. Typically, the CUP of the polymer composition after 16 hours under a confined pressure of 1.4 psi is from about 25 to about 35 g / g.

C. The permeability of compartments or layers comprising absorbent polymers An important property of compartments or layers comprising absorbent polymers is their permeability to liquids. In an absorbent member or product, this permeability directly affects the ability of a material, such as a layer comprising a swollen absorbent polymer, to move bodily fluids from the trap at an acceptable rate. Permeability / flow conductivity can be defined by saline flow conductivity (SFC). This is a measure of the ability of a substance to move salt water. The absorbent polymer is
If the SFC value is at least about 30 × 10 ⁻⁷ cm ³ s / g, it is considered to have the desired permeability. U.S. Pat. No. 5,562,646 issued Oct. 8, 1996 (Goldman et al.) Describes a method for measuring salt water flow transfer. This method is partially modified to account for the de-swelling of the gel layer that occurs during the measurement of the SFC value of the mixed layer ion exchange absorbent polymer, as described in the Test Methods section below. While not wishing to be bound by theory, it is believed that while measuring the SFC of the mixed layer ion exchange absorbent polymer, the polymer sample continues to exchange ions from the saline. Eventually, the ion exchange capacity of the absorbent polymer will be exceeded, and the ionic strength of the solution surrounding the swollen polymer will increase, resulting in some de-swelling of the gel layer. The amount of liquid squeezed out of the gel as a result of this de-swelling is small compared to the amount of liquid flowing through the gel layer during SFC measurements. Since the final thickness of the gel layer is much smaller than the initial thickness, the final thickness of the gel layer is used for calculating the SFC value. Using the final thickness of the gel layer in the calculation gives the minimum SFC achieved during the measurement. Using an initial or intermediate thickness of the gel layer results in a higher SFC value.

The SFC value of the absorbent polymer composition of the present invention is at least about 30 × 10^-7cm ³ Sec / g, more preferably at least about 50 × 10^-7cm³Seconds / g, even more
Preferably at least about 70 × 10^-7cm³Seconds / g is preferred, but
This need not be the case. Typically, the SFC value of the absorbent polymer of the present invention
Is about 30 to about 100 × 10^-7cm³Second / g, more typically from about 50 to
About 90 × 10^-7cm³Seconds / g, even more typically from about 70 to about 80 × 10^-7 cm³Seconds / g.

D. The porosity of the compartment or layer comprising the absorbent polymer Another important property of the mixed layer ion exchange absorbent polymer of the present invention is that when the absorbent polymer is swollen by body fluids under constrained pressure, Is the degree of openness or porosity of the compartment or layer comprising The absorbent polymer useful in the present invention is present at a high concentration in the absorbent member or the absorbent product, and when it subsequently swells under operating pressure, the boundaries of the particles come into contact with each other and are located in this high concentration portion. It is believed that interstitial voids are generally closed by the swollen polymer. When this occurs, the openness or porosity properties of this portion will generally reflect the porosity of the compartment or layer formed from the swollen absorbent polymer alone. As used herein, the term "porosity" means a small volume (dimensionless) that is not occupied by solid material. JM Coulson et al., `` Chemical
Engineering, Vol. 2, 3rd Edition (issued by Pergamon Press, 1978)
See page 26.

Porosity is a practical measure of the ability of a compartment or layer comprising a swollen absorbent polymer to remain open to capture and disperse bodily fluids under working pressure. The higher the porosity of the swollen, high-concentration portion, the better the absorbency and liquid handling properties of the absorbent core, thereby reducing the occurrence of leaks, especially when the liquid load is high. . Desirably, the porosity of the compartment or layer comprising the swollen absorbent polymer is close to or greater than the porosity of conventional trapping / dispersing materials such as wood pulp fuzz. Goldma on October 8, 1996
See U.S. Pat. No. 5,562,646 issued to N. et al.

E. Another important factor affecting the movement of the liquid in the absorbent polymer comprising a compartment or the integrity absorbent member layer, a partial integrity comprising these polymers. Such portions having a high concentration of the absorbent polymer, when subjected to normal conditions of use, can provide the physical continuity of the absorbent member (
And therefore partially moist, so that the ability to capture and move liquids into and through the voids / capillaries of adjacent gaps is not substantially disrupted or altered; And / or exhibit sufficient integrity when wet. During normal use, the absorbent core in an absorbent product is generally subjected to various strengths and directions of tensile and torsional forces. These tensile and torsional forces include crimping at the crotch and stretching and twisting forces when a person wearing the absorbent product walks, squats, or crouches. If wet integrity is not adequate, these tensile and torsional forces may substantially alter and / or disrupt the physical continuity of the absorbent member, and may cause adjacent voids and capillaries The ability to capture and move liquids during and through them is reduced. The layer comprising the absorbent polymer may be partially separated, completely separated, have gaps therein, have significantly thinner portions, and / or It may be divided into a plurality of extremely small parts. Such a modification may minimize or none of the advantages of the porosity of the absorbent polymer and any of the advantages of osmosis / flow conductivity. Things.

The good integrity of a compartment or layer comprising an absorbent polymer may be due to the absorbent member having a high concentration of the absorbent polymer, other components in the absorbent core (eg, liquid trapping members), The design, shape, and / or other components in the cosmetic product (eg, topsheet and / or backsheet), or any combination of these components.
It can be achieved by variously devising the configuration and the like according to the present invention. 19
U.S. Pat. No. 5,562,64, issued Oct. 8, 1996 to Goldman et al.
See No. 6.

In a preferred mixed layer ion exchange system, the cation exchange component and the anion exchange component tend to adhere to each other. Without wishing to be bound by theory, this is because the oppositely charged polyions and / or acidic / basic on the surface of the polymer gel particles are essentially attracted to oppositely charged species in adjacent particles. Probably due to the species. This results in a three-dimensional network of adherent polymer particles in the compartment or layer comprising the absorbent polymer, thereby greatly improving the integrity of the compartment or layer.

The integrity of the part comprising the polymer composition of the present invention can be measured by the Ball Burst Strength (BBS) test described below. Ball burst strength is the force (grams) required to break a layer of the absorbent polymer composition swollen with synthetic urine. Preferably, but not necessarily, the BBS value of the absorbent polymer composition of the present invention is at least about 50 gf, more preferably at least about 100 gf, even more preferably at least about 150 gf, even more preferably at least about 200 gf. There is no. Typically, the BBS value is about 50
To about 1000 gf, more typically from about 100 to about 800 gf, even more typically from about 150 to about 400 gf, and most typically from about 200 to about 300 gf.

[0081] 3. Methods of Making Absorbent Polymers Absorbent polymers useful in the mixed layer ion exchange compositions of the present invention can be made by any polymerization and / or cross-linking techniques. A typical method for making these polymers is described in U.S. Reissue Patent No. 32,6, issued April 19, 1988.
No. 49 (Brandt et al.), US Pat. No. 4,666, issued May 19, 1987.
, 983 (Tsubakimoto et al.) And US Pat. No. 4,625,001 (November 25, 1986) (Tsubakimoto et al.). All of these patents are incorporated herein by reference.

[0082] Polymerization methods for making ion exchange polymers useful in the present invention can include free radical methods, ring opening methods, condensation methods, anion methods, cation methods, and irradiation methods. Although the desired product is substantially unneutralized, it may produce a polymer in a neutralized, partially neutralized, or non-neutralized state. The absorbent polymer may be made using a homogeneous solution polymerization method or by a multi-stage polymerization method such as an inverse emulsion or suspension polymerization method.

Crosslinking can be performed during polymerization by adding a suitable crosslinking monomer. Alternatively, the polymer may be crosslinked by reacting with a suitable reactive crosslinking agent after polymerization. By performing surface crosslinking of the initially formed polymer, a relatively high P
An absorbent polymer with UP capacity, porosity, and permeability is obtained. Without being bound by theory, the surface resistance of the swollen absorbent polymer particles is enhanced by surface cross-linking, so that adjacent polymer particles come into contact when the swollen polymer particles are deformed by external pressure It is considered that the degree becomes small. Surface crosslinked absorbent polymers have a higher level of crosslinking near the surface than inside. As used herein, “surface” refers to the outer boundary of a particle. For porous absorbent polymers (eg, porous particles, etc.), exposed internal boundaries can also be included.
A high surface cross-linking level means that the level of functional cross-linking near the surface of the absorbent polymer is generally higher than the level of functional cross-linking inside the polymer. A gradation of cross-linking from the surface to the interior can be applied to both depth and cross-section.

A number of methods for introducing surface cross-linking have been disclosed in the art. Suitable methods for performing surface cross-linking include (i) applying a bifunctional or polyfunctional reagent capable of reacting with a functional group present in the absorbent polymer to the surface of the absorbent polymer. , (Ii) other additive reagents and bifunctional or polyfunctional reagents capable of reacting with the functional groups believed to be present in the absorbent polymer to increase the level of cross-linking at the surface. Methods applied to the surface (e.g. addition of monomer + crosslinker and initiation of the second polymerization reaction), (iii) no additional multifunctional reagents are added, but during or after the main polymerization process, Methods that increase the level of cross-linking at or near the surface by causing an additional reaction between the components present in the absorbent polymer (eg, the cross-linking agent is initially present at a higher level near the surface) Hanging Polymerization method), and (iv) or other substances added to the surface increase the level of crosslinking or otherwise, include methods of reducing the surface deformability of the resultant swollen polymer. General methods suitable for performing surface cross-linking of absorbent polymers according to the present invention are described in US Pat. No. 4,541,871 issued Sep. 17, 1985 (Obayashi), Oct. 1, 1992. International Patent Application No. WO 92/165 published
No. 65 (Stanley), International Patent Application No. WO 90, published August 9, 1990.
No. 08879 (Tai), International Patent Application No. W published March 18, 1993.
No. O93 / 05080 (Stanley); U.S. Pat. No. 4,824,901 issued Apr. 25, 1989 (Alexander); U.S. Pat. No. 4,789,861 issued Jan. 17, 1989. (Johnson), U.S. Patent No. 4,587,308 (Makita) issued May 6, 1986, U.S. Patent No. 4,734,478 (Tsubakimoto) issued March 29, 1988, U.S. Pat. No. 5,164,459 issued on Nov. 17, 1992 (Kimura et al.), Aug. 2, 1991
German Patent Application No. 4,020,780 published on 9th (Dahmen), and 199
European Patent Application No. 509,708 published October 21, 2009 (Gartner
) Is disclosed in each specification. All of these patents are incorporated herein by reference. For cation-absorbing polymers, suitable difunctional or multifunctional crosslinkers include di / poly-haloalkanes, di / poly-epoxides, di / poly-acid chlorides, di / poly-tosylalkanes, Di / poly-aldehyde, di / poly-acid and the like.

In general, surface cross-linking results in an absorbent polymer composition having improved PUP ability, porosity, and permeability. Surprisingly, however, mixed layer absorbent polymer compositions comprising cation exchange absorbent polymers made with relatively high levels of crosslinking monomers and having a uniform distribution of cross-links throughout the polymer are surface cross-linked. Compared to similar compositions having a modified cation exchange absorbent polymer,
Both UP and PUP capabilities have been found to be particularly desirable and improved (see example below).

[0086] Without being bound by theory, the mixed-layer ion-exchange absorbent polymer composition absorbs a very large amount of liquid, so that the surface of individual gel particles swells many times their original size. In the case of an absorbent polymer composition having a cross-linked surface, such a disintegration is likely to cause deformation under the pressure applied during use as described above, and also to cause gel blocking. In some cases, the relatively soft (low modulus) inner core of the particles may escape out.Homogeneously crosslinked absorbent polymer particles have a relatively uniform modulus throughout the particle,
Therefore, even when it swells very much, it does not cause much gel blocking. "

[0087] Homogeneously crosslinked cation exchange absorbent polymers are even more advantageous than surface crosslinked cation exchange absorbent polymers in that a surface cross-linking step can be eliminated from the manufacturing process. Thus, (i) the particles of, for example, the anion exchange absorbent polymer have smaller internal, discontinuous regions of, for example, the cation exchange absorbent polymer, or (ii) the particles of the anion exchange absorbent polymer The production of a mixed layer composition from an anion exchange absorbent polymer component and a cation exchange absorbent polymer component comprising both bicontinuous regions of the cation exchange absorbent polymer and the cation exchange absorbent polymer is facilitated. Such a form is particularly advantageous in that the anion exchange and cation exchange absorbent polymers are brought into close proximity in the final mixed layer absorbent polymer composition to provide the desired improvement in ion exchange rates. is there.

C. Test method 1. Performance Under Pressure (PUP) This test was performed in accordance with U.S. Pat. No. 5,599,335 issued Feb. 4, 1997.
No. (Goldman et al.). This test shows that a synthetic urine solution having a composition and ionic strength typical of the urine of young infants, for example, 0.1 mL.
It measures the amount absorbed by an absorbent polymer (including a mixed layer ion exchange absorbent polymer composition) literally trapped in a piston / cylinder assembly under a constraint pressure of 7 psi, or 1.4 psi. The purpose of this test corresponds to the use time (for example, overnight) of a product comprising the absorbent composition when the absorbent polymer is present in high concentration in the absorbent member and is exposed to use pressure. Time (for example,
(1 hour, 2 hours, 4 hours, 8 hours, or 16 hours) to assess the ability of the absorbent polymer to absorb body fluids. Use pressures at which the absorbent polymer must absorb liquids include mechanical pressures caused by the weight and / or movement of the wearer, mechanical pressures caused by elastic rubber or fastening systems, and adjacent layers and / or Includes desorption water pressure of the member.

As a test solution for the PUP ability test, 2.0 g of KCl and 2.0 g of Na ₂ SO ₄ were added to distilled water.
0 _g, and NH ₄ H 2 PO _{4 0.85g,} the _{(NH 4) 2 HPO 4 0.15g} , C
This is an aqueous solution in which 0.25 g of aCl ₂ .2H ₂ O and 0.50 g of MgCl ₂ .6H ₂ O are dissolved to form a 1-liter solution. Such solutions have a composition and ionic strength typical of urine in young infants. The liquid is absorbed by the absorbent polymer at a hydrostatic pressure close to zero under the required absorption conditions.

FIG. 1 shows an apparatus suitable for this test. At one end of the device is a liquid reservoir 712 (such as a Petri dish) with a cover 714. Reservoir 712 rides on an analytical balance, shown schematically as 716. The other end of the device 710 is a glass filter shown schematically as 718, a piston / cylinder assembly shown generally as 720, which fits inside the filter 718, and a top of the filter 718. A cylindrical plastic glass filter cover, shown generally as 722, that fits tightly, is open at the bottom, closed at the top, and has a pinhole at the top. The device 710 includes glass tube sections shown as 724 and 731a, a soft plastic tube shown as 731b (eg, a 1/4 inch ID, 3/8 inch OD Tygon® tube), Stopcock assembly 7
26 and 738, and glass tubes 724 and 731a and stopcock assemblies 726 and 7
Teflon connectors 748, 750, and 752
And a system for moving the liquid in either direction. Stopcock assembly 72
6 is a three-way valve 728, a glass capillary tube 730 and 734 in the main flow system, and a glass capillary tube for completely filling the reservoir 712 and flushing the glass filter plate in the glass filter 718 forward. It consists of a part 732. Stopcock assembly 738
Similarly, a three-way valve 740, glass tubules 742 and 74 in the main flow line.
6 as well as a glass tube section 744 which serves as the drainage of the system.

Referring to FIG. 2, the assembly 720 comprises a cylinder 754, a cup-shaped piston shown at 756, and a weight 758 that fits inside the piston 756. Attached to the bottom end of the cylinder 754 is a No. A mesh 759 made of 400 mesh stainless steel cloth. The absorbent polymer composition, shown generally as 760, rides on the net 759. Cylinder 754 is boring from a clear Lexan (R) rod (or equivalent) and has an inner diameter of 6.00 cm (
The area is 28.27 cm ² ), the wall thickness is about 5 mm, and the height is about 5 cm. Piston 75
6 is in the form of a cup made of Teflon (R) or Kel F (R), and the cylinder 754 is shaped so that the annular clearance between the cylinder and the piston is 0.114 to 0.191 mm. It is processed so that it can be slipped inside. A cylindrical stainless steel weight 758 is machined so that it can slide into piston 756 and has a handle (not shown) mounted on top for easy removal. When the confining pressure is 0.7 psi, the piston 756 and the weight 7
The combined weight of 58 is 1390 g, which corresponds to a pressure of 0.7 psi for an area of 28.27 cm ² . At a constraint pressure of 1.4 psi, the combined weight of piston 756 and weight 758 is 2780 g.

The components of device 710 are sized so that the flow rate of synthetic urine therethrough is at least 36 grams per square centimeter of glass filter plate in glass filter 718 at a hydrostatic head of 10 cm per hour. It is made in. Factors that particularly affect the flow rate are the water permeability of the glass filter plate in the glass filter 718, and the inside diameter of the glass tubes 724, 730, 734, 742, 746 and 731a and the stopcock valves 728 and 740.

The reservoir 712 is located on an analytical balance 716 that is accurate to at least 0.01 g and has a deviation of less than 0.1 g / hr. This balance can (i) monitor the weight change of the balance at the preset time interval from the start of the PUP test, and
ii) Depending on the sensitivity of the balance, it is preferably connected to a computer with software set to automatically start taking data when the weight changes from 0.01 to 0.05 g. The tube 724 plugged into the reservoir 712 must not be in contact with the reservoir bottom or cover 714. Storage 712
The volume of the liquid therein (not shown) must be sufficient to prevent air from being drawn into tube 724 during the measurement. The level of liquid in the reservoir 712 at the start of the measurement should be about 2 mm below the top of the glass filter plate in the glass filter 718. This places small droplets on the glass filter plate and this amount of liquid is stored in reservoir 712.
It can be confirmed by monitoring the flow returning to the above by weight measurement. This level is
When the piston / cylinder assembly 720 is in the filter 718, it must not change significantly. The reservoir must be large enough in diameter so that the change in liquid height when removing about 40 ml of liquid is less than 3 mm (eg, about 14 mm).
cm).

Prior to performing the measurement, the assemblage is filled with a synthetic urine solution and the glass filter plate in the filter is quickly rinsed so that the glass filter 718 is filled with fresh synthetic urine solution. Remove as much air bubbles as possible from the bottom of the glass filter plate and from the system connecting the filter and the reservoir. The following procedure is performed by operating the stopcock continuously. 1. Excess liquid on the top surface of the glass filter plate is removed (eg, drained) from the glass filter 718. 2. Adjust the height / weight of the solution in reservoir 712 to the appropriate level / value. 3. The glass filter 718 is positioned at the correct height relative to the reservoir 712. 4. Thereafter, the glass filter 718 is covered with a glass filter cover 722. 5. The valves 728 and 740 of the stopcock assemblies 726 and 738 are opened and in communication, and the reservoir 712 and the glass filter 718 are equilibrated. 6. Thereafter, valves 728 and 740 are closed. 7. The valve 740 is then twisted so that the filter communicates with the drain 744. 8. The system is kept in equilibrium for 5 minutes in this state. 9. Thereafter, the valve 740 is returned to the closed state.

In steps 7-9, the surface of glass filter 718 is subjected to a hydraulic suction of about 5 cm to temporarily “dry”. This aspiration is performed when the open end of the tube 744 extends to about 5 cm below the level of the glass filter plate in the glass filter 718 and is filled with synthetic urine. Typically, about 0.
2 g of liquid are discharged. By this procedure, the piston / cylinder assembly 72
When a zero is in the glass filter 718, premature absorption of synthetic urine is prevented. The amount of liquid discharged from the glass filter in this procedure (referred to as the glass filter corrected weight) is determined by the PUP test (without using the piston / cylinder assembly 720).
(See below) for 15 minutes. This procedure causes substantially all of the liquid discharged from the glass filter to be reabsorbed very rapidly into the glass portion of the filter when the test is started. Therefore, it is necessary to subtract this corrected weight from the weight of the liquid exiting the reservoir during the PUP test (see below).

[0096] To minimize the level of moisture and / or other solvents in the sample, dehydrate the absorbent polymer composition 760 by a suitable procedure, eg, under high vacuum at a suitable temperature for a sufficient time. To dry. The final level of residual moisture as measured by a suitable technique such as Karl Fischer titration or thermogravimetric analysis should be less than about 5%, preferably less than about 3%. About 0.9 g ( _Wap ) of the dried absorbent polymer composition 760 (basic weight 0.032 g / c
corresponding to m ^2), placed in a cylinder 754 is dispersed homogeneously over the network 759. If the absorbent polymer composition comprises more than one type of particles, the particles are uniformly mixed throughout the composition. Absorbent polymer 760 is cylinder 75
Be careful not to adhere to the inner wall of No. 4. The piston 756 is slid into the cylinder 754 and placed on the absorbent polymer 760 while ensuring the free sliding of the piston within the cylinder. The piston may be gently rotated to help disperse the absorbent polymer. The piston / cylinder assembly 720 is placed on the glass part of the filter 718 and the top of the filter 718 is covered with a glass filter cover 722 after the weight 758 is slid into the piston 756. After the balance has been checked for stability, valves 728 and 7 are connected so that filter 718 and reservoir 712 are connected.
Open 40 to start the test. As soon as the filter 718 begins to reabsorb the liquid, the automatic start immediately begins collecting data.

[0097] The weight of liquid remaining in reservoir 712 is recorded at short intervals during the test. I
The PUP capability at any given time t is calculated as follows. PUP capacity (g / g; t) = [W_r(T = 0) -W_r(T) -W_fc] / W_{a p} Where W_r(T = 0) is the weight of the reservoir 712 in grams before starting, W _r (T) is the elapsed time t (eg, 1 hour, 2 hours, 4 hours, 8 hours, or
16 hours), the weight of the reservoir 712 in grams, W_fcIs in grams
Is the corrected glass filter weight (measured separately)_apIs the absorbency in grams
The initial dry weight of the polymer.

[0098] 2. Capacity Under Pressure (CUP) This test uses essentially the same method and equipment as the PUP method described above. C
UP measures the absorption performance of absorbent polymers and absorbent polymer compositions when exposed to high ionic strength synthetic urine solutions having the composition and ionic strength typical of urine in older infants and toddlers. It is understood as a scale.

The test solution for the CUP test was prepared by adding 4.0 g of KCl to distilled water and Na₂SO₄2.0
g, NH₄H₂PO₄1.2 g, (NH₄)₂HPO₄1.6 g of CaCl ₂ ・ 2H₂0.20 g of O, MgCl₂・ 6H₂0.55 g of O and NaCl
Is an aqueous solution in which 7.0 g is dissolved to make a 1-liter solution. Such a solution
Has the typical composition and ionic strength of urine in older infants and toddlers
. This liquid is absorbed by the absorbent polymer under the required absorption conditions at a hydrostatic pressure close to zero.
Let it go.

Other aspects of the CUP test are all the same as the PUP test described above.

3. Ball Burst Strength (BBS) Test This test is for measuring the ball burst strength (BBS) of an absorbent polymer composition. BBS refers to the force (peak load, unit is gram weight, or "gf "). BBS is a measure of the integrity of the absorbent polymer composition layer in the swollen state.

FIG. 7 shows an apparatus suitable for the measurement of BBS. The device comprises an absorbent polymer layer 26.
Internal cylinder 270 used to fill 0, external cylinder 230, Teflon
It comprises a flat bottom tray 240 made of (R), a cover plate 220 for the inner cylinder, and a weight 210 made of stainless steel. The inner cylinder 270 is made of a transparent Lexan (R) rod or its equivalent, and has an inner diameter of 6.00 cm (area = 28.27 cm ² ), a wall thickness of about 0.5 cm, and a height of about 1 cm. .50
cm. The outer cylinder 230 is formed by boring a Lexan (R) rod or an equivalent thereof, and has an inner diameter slightly larger than the outer diameter of the inner cylinder 270. Fits perfectly and slides freely. The thickness of the outer cylinder 230 is about 0.5cm
And the height is about 1.00 cm. The bottom of the outer cylinder 230 is a 400 mesh stainless steel mesh 25 that has been stretched horizontally and vertically before installation.
0 surface finish. The cover plate 220 for the inner cylinder is made of a glass plate having a thickness of 0.8 cm and a weight of 500 g. The weight of the stainless steel weight 210 is 1700 g.

For this test, a tensile tester with load cell for burst test (Intellect II-STD tensile tester manufactured by Thwing-Albert Instrument Co., Pennsylvania)
Is used. Referring to FIG. 8, the apparatus includes a force sensing load cell 330 with a polished stainless steel spherical probe 290 mounted thereon, a movable crosshead 320, a stationary crosshead 310, a circular table 280, and an air inlet. It can be seen that it is composed of the upper fixing plate 300 used to press the sample 260 in the folded state. The table 280 rides on the stationary crosshead 310. The diameter of the table 280 and the upper fixed plate 300 are both 115 mm, the thickness is 2.9 mm, and the diameter of the circular opening is 18.65 mm. The diameter of the polished stainless steel spherical probe 290 is 15.84 mm. During the BBS test, the movable crosshead 320 moves upward, and the probe 290 comes into contact with and penetrates the sample 260. When the probe 290 has penetrated the sample 260, the test is considered finished and appropriate data is recorded.

Referring to the device depicted in FIG. 7, it can be seen that the inner cylinder 270 has been fitted into the outer cylinder 230. A 1.0 g sample of the absorbent polymer composition was placed in the inner cylinder 270 and a stainless steel 400
Disperse evenly on mesh net 250. The assembled cylinder and the absorbent polymer are transferred to a flat bottom tray 240 made of Teflon, and the cover plate 220 for the inner cylinder is placed on the inner cylinder 270. An aliquot of 30.0 ml of the synthetic urine solution is poured into a flat bottom tray 240 made of Teflon. This synthetic urine solution is absorbed by the absorbent polymer composition 260 through a stainless steel mesh. Five minutes after adding the liquid, a stainless steel weight 210 is placed on the cover plate 220 for the inner cylinder. After a further 25 minutes, the stainless steel weight 210 and the cover plate 220 for the inner cylinder are removed. At this point, all of the synthetic urine solution must be absorbed by the absorbent polymer composition for this procedure to be effective. Immediately transfer the inner cylinder 270 containing the layer of swollen absorbent polymer 260 to a burst tester for BBS measurement.

Referring to the burst tester depicted in FIG. 8, the swollen absorbent polymer layer 26
It can be seen that the inner cylinder 270 containing 0 is placed in the center of the table 280 and is fixed by the upper fixing plate 300 with air. The measurement is
The test is performed at a burst sensitivity of 10.00 g and a test speed of 5.00 inches / minute. When the measurement begins, the crosshead 320 moves up until the polished stainless steel spherical probe 290 penetrates the gel layer 260 of absorbent material. When the sample ruptures, the movable crosshead 320 returns to the starting position. BBS is expressed as peak load in gram weight. The average of the three measurements is reported as the BBS of the absorbent polymer composition.

D. Absorbent Member The absorbent member according to the present invention comprises the mixed layer ion exchange absorbent polymer composition described above, with or without other optional components such as fibers, thermoplastics, and the like. Preferred materials are described in U.S. Pat. No. 5,562,646 (Go
ldman et al.) The details are described in column 23, line 13 to column 29, line 16 of the specification. These absorbent members comprising these absorbent polymers can serve as liquid storage members in the absorbent core. The primary function of such a liquid storage member is to absorb excreted bodily fluids directly or from another absorbent member (eg, a liquid capture / dispersion member), after which the pressure normally produced as a result of the movement of the wearer is reduced. It is to keep such a liquid even when it is applied. However, it goes without saying that such a polymer-containing absorbent member can serve other functions than storage of liquid.

In a preferred embodiment, the absorbent member according to the invention contains one or more parts having a relatively high concentration of these absorbent polymers. To provide relatively thin absorbent products that can absorb and retain large amounts of bodily fluids, maximize the level of these absorbent polymers and minimize the levels of other components, especially fibrous components. It is desirable to suppress to. However, in order to use these absorbent polymers at relatively high concentrations, these polymers exhibit a relatively high required absorption capacity (ie, PUP ability) under relatively high confining pressures, and preferably have a relatively high absorption capacity under pressure. It is important to show a very high permeability (ie SFC). This is because when the polymer swells in the presence of bodily fluids, the polymer exhibits adequate absorption capacity to capture these excreted bodily fluids, and then dissipate these fluids through relatively gel-rich compartments or layers. It is for transferring to the absorbent member and / or other parts of the absorbent core and / or for storing these body fluids.

When measuring the concentration of the mixed layer ion exchange absorbent polymer composition in a given portion of the absorbent member, the absorbent polymer and any other components present in the portion containing the polymer ( For example, the weight percent of the absorbent polymer based on the combined weight of the absorbent polymer and the fibers, the thermosetting material, etc.) is used. With this in mind, the concentration of the mixed layer ion exchange absorbent polymer composition in a given portion of the absorbent member of the present invention is typically about 40-100%, about 50-100%, about 60-100%. ,
About 70-100%, about 80-100%, or about 90-100%. Of course, in general, the higher the relative concentration of the absorbent polymer, the thinner the absorbent member and the less bulk.

E. Absorbent Core and Absorbent Product The mixed layer ion exchange absorbent polymer composition of the present invention is described in U.S. Pat. No. 5,562,646 (Goldman et al.), Similar to conventional absorbent polymers. It can be used in any absorbent core and / or absorbent product for absorbing bodily fluids as described above. No. 5,562,646 describes the absorbent core in detail from column 33, line 7 to column 52, line 24;
From line 5 to column 54, line 9, the absorbent product is described in detail. Such products include diapers, sanitary products, and / or adult incontinence products. By replacing the conventional absorbent polymer with the same weight of the present mixed layer ion exchange absorbent polymer, the absorbent capacity of the product can be increased. Alternatively, to make the product lighter, thinner and / or less bulky without increasing the absorption capacity of the product,
It may be replaced by a lower weight of the mixed layer ion exchange absorbent polymer than before.

The incorporation of a mixed layer ion exchange absorbent polymer into any of the absorbent products disclosed above is a matter of course for those skilled in the art. Such products include those with functions such as breathable backsheets, fasteners, bicomponent fiber matrices, and the like.

Absorbent products that can include the mixed layer ion exchange absorbent polymers described herein include, for example, US Pat. No. 3,224, issued Dec. 21, 1965.
No. 926 (Bernardin), U.S. Pat. No. 3,4, issued Apr. 22, 1969.
No. 40,135 (Chung), U.S. Pat.
Nos. 932,209 (Chatterjee) and U.S. Pat. No. 4,035,147, issued Jul. 12, 1977 (Sangenis et al.). More preferred stiffened fibers are disclosed in U.S. Pat. No. 4,822, issued Apr. 18, 1989.
No. 4,453 (Dean et al.), US Pat. No. 4,8, issued Dec. 19, 1989.
U.S. Pat. No. 4,8,88,093 (Dean et al.), Issued Feb. 6, 1990.
No. 98,642 (Moore et al.), U.S. Pat. No. 5, issued Aug. 11, 1992.
U.S. Patent No. 4,818,598 (Wong), issued April 4, 1989; U.S. Patent No. 5,562, issued October 8, 1996. No. 646 (Goldman et al.); U.S. Pat. No. 5,217,445 issued Jun. 8, 1993 (Young et al.); U.S. Pat. No. 5,360,420 issued Nov. 1, 1994. (Cook et al.), U.S. Pat. No. 4,935,022 (
Lash et al.), US patent application Ser. No. 08/153, filed Nov. 16, 1993.
No. 739 (Dragoo et al.), U.S. patent application Ser.
/ 164,049 (Dragoo et al.), U.S. Patent No. 4,260,443 (Lindsay
U.S. Pat. No. 4,467,012, issued Aug. 21, 1984 (Pe
dersen et al.), US Pat. No. 4,715,91 issued Dec. 29, 1987.
No. 8 (Lang), US Pat. No. 4,851,06, issued Jul. 25, 1989.
No. 9 (Packard et al.), US Pat. No. 4,950, issued Aug. 21, 1990.
U.S. Pat. No. 4,99, issued Feb. 19, 1991.
No. 4,037 (Bernardin), U.S. Pat. No. 5, issued April 23, 1991.
U.S. Patent No. 5,009,653 (Osborn), issued April 23, 1991; U.S. Patent No. 5,128,082, issued July 7, 1992. No. 5,149,335 (Kellenberger et al.), Issued Sep. 22, 1992, U.S. Pat. No. 5,176,668 (Bernardin) issued Jan. 5, 1993. U.S. Patent Application No. 141,156, filed October 21, 1993 (Richards et al.); U.S. Patent No. 4,429,001 issued January 31, 1984 (Kolpin et al.), 1991. No. 07 / 794,745, filed Nov. 19, 2011 (Aziz et al.). All of these patents are incorporated herein by reference.

F. Illustrative Example A lightly crosslinked partially neutralized poly (acrylic acid) absorbent polymer having relatively high PUP capacity (about 33 g / g at 0.7 psi; 60 minutes) is obtained from Chemdal, Inc. of Parrantine, Illinois. (ASAP-2300, lot number 42615
2). (A similar sample of ASAP-2300 is available from The Procter &Gamble's Paper Technology Division, Cincinnati, Ohio.) This material serves as a control sample. , Referred to herein as the “control sample”.

A sample of an absorbent polymer that provides higher integrity compared to a conventional polyacrylate absorbent polymer is obtained from Nippon Shokubai (lot number TN37408).
This is a polyacrylate surface treated with polyethyleneimine. This polymer is described in detail in U.S. Pat. No. 5,382,610, filed Jan. 17, 1995. This substance is referred to herein as “sample ST”.

Example 1 Preparation of an Ion Exchange Absorbent Polymer (i) Cation Exchange Absorbent Polymer To prepare a cation exchange absorbent polymer, some of the control samples were sieved through a US standard 50 mesh sieve with a diameter of about Remove particles larger than 300 microns. About 46.5 g of concentrated HCl (baker, 36.5 to 38% HCl) is added to about 900
About 50 grams of a sieved absorbent polymer having a particle size of less than about 300 microns is suspended in dilute hydrochloric acid obtained by adding to the ml of distilled and deionized water to convert the polymer to the acid form. After gently stirring the suspension for about 1.5 hours, the absorbent polymer precipitates and the supernatant is removed by decantation. The suspension is gently shaken for about 1 hour by adding the same volume of distilled and deionized water in place of the decanted liquid, allowing the absorbent polymer to precipitate, and the supernatant liquid being again decanted. This exchange step is repeated using the same volume of distilled and deionized water until the pH of the supernatant is 5-6 (about 8 times). The exchange step was then repeated three times using isopropanol (reagent grade, VWR, West Chester, PA), three times using acetone (reagent grade, VWR), and anhydrous ether (reagent grade,
EM Science, Gibbston, NJ). The product is gently spread on a sheet of polytetrafluoroethylene and dried overnight. The product is gently loosened by hand with a spatula and then dried under high vacuum at room temperature for 96 hours to remove any residual solvent. The sample is sieved through a US standard 20 mesh screen to remove any large particles or agglomerates. About 30 grams of a crosslinked poly (acrylic acid) ion exchange absorbent polymer in the acid form is obtained. This is stored under a dry atmosphere (sample PAA).

(Ii) Anion exchange absorbent polymer Branched polyethyleneimine having a nominal weight average molecular weight of 750,000 g / mol was obtained from Aldrich Chemical Company, Milwaukee, Wis., 50%.
Obtain as an aqueous solution (catalog number 18,917-8, lot number 12922)
PQ). 20 grams of this solution is further diluted with 37 grams of distilled water and stirred in a 250 ml beaker for 30 minutes to completely dissolve. Ethylene glycol diglycidyl ether (50% solution) (Aldrich Chemical Co., catalog number E2, 720-3, lot number 07405DN) was added to this polyethyleneimine solution at 2.14.
Grams are added and the mixture is stirred at room temperature for about 2 minutes and then placed in a vented oven at about 65 ° C. for 3 hours. After cooling the obtained gel, it is broken into a size of about 1 to 5 mm in diameter. The mixture is then transferred to a 4000 ml beaker containing 2 liters of distilled water and gently stirred overnight. The excess water is decanted off and the remaining sample is dried under high vacuum for about 96 hours to yield a lightly crosslinked polyethyleneimine anion exchange absorbent polymer. Store this in a dry atmosphere (
Sample BPEI).

(Iii) Mixed layer ion exchange absorbent polymer Crosslinked polyethyleneimine anion exchange absorbent polymer (Sample BPEI) is ground at cryogenic temperatures and sieved under a dry nitrogen atmosphere. The particle size fraction that passes through a U.S. standard 25 mesh screen but not through a U.S. standard 70 mesh screen (i.e.,
(A fraction of particles of about 200-700 microns in diameter).

A crosslinked poly (acrylic acid) cation exchange absorbent polymer (sample P
AA) and the sieved crosslinked polyethyleneimine anion exchange absorbent polymer (Sample BPEI) are mixed by approximately the same weight to uniformly disperse the particles of both polymers throughout the mixture. This mixture constitutes the mixed layer ion exchange absorbent polymer composition of the present invention (Sample MB-1).

(Iv) Measuring the PUP Capability About 0.9 gram of the mixed layer ion exchange absorbent polymer composition (Sample MB-1) was transferred to a PUP cylinder (as described in the test method section above) and Gently spread over the entire net that makes up the surface. The amount of liquid absorbed is measured at short intervals over a period of 16 hours, and the PUP capacity under a confining pressure of 0.7 psi and under 1.4 psi is measured on separate samples. The PUP performance measured at 0.7 psi and 1.4 psi as a function of time is shown in FIGS. 3 and 4, respectively. 2 hours, 4 hours, 8
The data for the time, and the PUP capacity selected at 16 hours are shown in Table 1 below. Table 1 PUP capacity of mixed layer ion exchange absorbent polymer composition 0.7 psi 0.7 psi 0.7 psi 1.4 psi 1.4 psi 1.4 psi
(4hrs) (8hrs) (16hrs) (2hrs) (8hrs) (16hrs)
Sample MB-1 44g / g 48g / g 50g / g 32g / g 40g / g 42g / g Control sample 33g / g 33g / g 33g / g 20g / g 20g / g 20g / g

When comparing the PUP capacity, the mixed layer ion exchange absorbent polymer composition (sample M
B-1) has a PUP capacity of about 100% higher at a confining pressure of 1.4 psi and a confining pressure of 0.7 psi, compared to the capacity of the partially neutralized polyacrylate absorbent polymer (control sample) under the same test conditions. It can be seen that the PUP capacity after 8 hours was about 40% higher.

(V) Measurement of CUP About 0.9 gram of the mixed layer ion exchange absorbent polymer composition (Sample MB-1) was transferred to a CUP cylinder (described in the test method section above) and the lower surface of the cylinder was measured. Gently spread over the entire network that constitutes. The amount of liquid absorbed was measured at short intervals over 16 hours and the CUP under 0.7 psi confining pressure and 1.4 psi.
Is measured on a separate sample. Selected CUP data at 1 hour, 2 hours, 4 hours, 8 hours, and 16 hours are shown in Table 2 below. Table 2 CUP data for mixed layer ion exchange absorbent polymer compositions 0.7 psi 0.7 psi 0.7 psi 0.7 psi 1.4 psi 1.4 psi 1.4 psi 1.4 psi (1 hr) (4 hrs) (8 hrs) (16 hrs) (1 hr) (2 hrs) (8 hrs ) (16hrs) Sample MB-1 17g / g 20g / g 21g / g 22g / g 15g / g 18g / g 21g / g 22g / g Control sample 21g / g 21g / g 22g / g 22g / g 13g / g 13g / g 15g / g 17g / g

When comparing CUP, the mixed layer ion exchange absorbing polymer composition (sample MB
-1) shows a significantly higher liquid absorption at a confined pressure of 1.4 psi compared to the absorption capacity of the partially neutralized polyacrylate absorbent polymer (control sample) under the same test conditions.

(Vi) Measurement of permeability The measure of permeability and the porosity are described in US Pat. No. 5,562,646 (Goldman et al.) Issued Oct. 8, 1996. It is defined by the saline flow conductivity of the gel layer being applied. This method is modified in part to accommodate mixed layer ion exchange absorbent polymer systems, as discussed below. Approximately 0.9 grams of the mixed layer ion exchange absorbent polymer composition (Sample MB-1) was charged with saline flow transfer (S
FC) Transfer to a cylinder designed for measurement and gently spread over the entire net making up the lower surface of the cylinder. The measurements of saline flow transfer are shown in Table 3 below. Table SFC value of 3 mixed layer ion-exchange absorbent polymer composition SFC value sample MB-1 to about 68 × ¹⁰ -7 cm ³ · sec / g Control Sample about ¹⁰ × 10 -7 cm ³ · sec / g

Comparing the saline flow transfer values, the permeability of the mixed layer ion exchange absorbent polymer composition (Sample MB-1) shows that the partially neutralized polyacrylate absorbent polymer under the same test conditions (Control sample) It can be seen that it is significantly greater than the permeability of It is believed that the mixed layer ion exchange absorbent polymer sample continues to exchange ions from the saline while measuring the SFC. Eventually, the ion exchange capacity of the absorbent polymer will be exceeded, and the ionic strength of the solution surrounding the swollen polymer will increase, resulting in some de-swelling of the gel layer. The amount of liquid squeezed out of the gel as a result of this de-swelling is less than the amount of liquid flowing through the gel layer during SFC measurements.
Since the final thickness of the gel layer is significantly smaller than the initial thickness, the final thickness of the gel layer is used for calculating the SFC value. Using the final thickness of the gel layer in the calculation gives the minimum SFC reached during the measurement. Using an initial or intermediate thickness of the gel layer results in higher SFC values.

SFC is not a direct measure of porosity, but generally speaking, when liquid permeability is high, the degree of porosity in the particulate absorbent polymer system must also be high. Thus, the relatively high SFC value of the mixed layer ion exchange absorbent polymer composition also indicates that the level of porosity is relatively high.

The integrity of the layer of the absorbent polymer composition in the swollen state is determined by the ball breaking strength (BBS) described above. Sample MB-1, Sample ST
And the ball breaking strength values measured for the control samples are shown in Table 4 below. Table 4 BBS value of mixed layer ion exchange absorbent polymer composition BBS sample MB-1 225 gf sample ST 133 gf Control sample 17 gf

Comparing the ball breaking strengths in Table 4, the mixed layer ion exchange absorbent polymer composition (Sample MB-1) was compared to the partially neutralized polyacrylate absorbent polymer (Control sample) under the same test conditions as the gel. It can be seen that the integrity of the layer is quite high.

Example 2 Preparation of an ion exchange absorbent polymer (i) Cation exchange absorbent polymer A cation exchange absorbent polymer is prepared as described in Example 1, paragraph (i) (
Sample PAA).

(Ii) Anion Exchange Absorbable Polymer a) Preparation of Crosslinked Polyallylamine Polyallylamine hydrochloride with a nominal weight average molecular weight of 60,000 g / mol is obtained from Polysciences, Inc., Warrington, PA (catalog) No. 18378, lot number 455913). A solution of the polymer is prepared by dissolving 16.4 grams of polyallylamine hydrochloride in 165 ml of distilled water. While stirring, 15.6 grams of a 50% aqueous solution of sodium hydroxide is added dropwise to the solution. Ethylene glycol diglycidyl ether (50% solution) (Aldrich Chemical Co., catalog number E2, 720-) is added to this polyallylamine solution.
3, lot number 07405DN) is added and the mixture is stirred at room temperature for about 2 minutes and then placed in a vented oven at about 65 ° C for 3 hours. The obtained gel is broken into a size of about 5 mm in diameter and transferred to a 4000 ml beaker containing 1 liter of distilled water. The mixture is gently stirred overnight and the excess water is decanted off. The remaining sample is dried under high vacuum at room temperature for about 96 hours to yield a lightly crosslinked polyallylamine anion exchange absorbent polymer. This is stored under a dry atmosphere (sample PAAM).

[0129] b) Sample methylated formic acid (96% solution of PAAM) (Aldrich Chemical Co., Catalog No. 25,136
-4) 21.02 grams and formaldehyde (37% solution) (Aldrich Chemical Co., catalog number 25,254-9, lot number 04717TZ)
56 grams are added to 800 grams of distilled water. To the above solution is added 10 grams of crosslinked polyallylamine (sample PAAM) and the mixture is placed in a 70 ° C. oven for 24 hours. The gel is recovered by decantation and stirred overnight in 1000 ml of water to remove extractable components. The supernatant is decanted off and, instead, one liter of a 1.7% aqueous solution of sodium hydroxide is added to remove excess formic acid in the gel. The mixture is left for about 24 hours, and the supernatant is decanted to recover the polymer. This process is repeated using 1 liter of a 1.7% aqueous solution of sodium hydroxide until the pH reaches 13 (about three times). The gel is collected by vacuum filtration and soaked in 3000 ml of water overnight. Excess water is removed by decanting and the remaining sample is dried under high vacuum at room temperature for about 96 hours to yield a lightly crosslinked tertiary polyallylamine anion exchange absorbent polymer. This is stored in a dry atmosphere. NMR spectroscopy of the product shows that about 90 percent of the amine groups in the polymer have been methylated to form a tertiary amine component (sample t-PAAM).

(Iii) Mixed Layer Ion Exchange Absorbent Polymer Crosslinked Tertiary Polyallylamine Anion Exchange Absorbent Polymer (Sample t-PAA
M) is ground at cryogenic temperatures and sieved under a dry nitrogen atmosphere. The size fraction (i.e., the fraction of particles having a diameter of about 200-700 microns) is collected that passes through a U.S. standard 25 mesh sieve but not through a U.S. standard 70 mesh sieve.

A crosslinked poly (acrylic acid) cation exchange absorbent polymer (sample P
AA) Combine about 0.29 grams and 0.71 grams of sieved cross-linked tertiary polyallylamine anion exchange absorbent polymer (sample t-PAAM) to uniformly disperse particles of both polymers throughout the mixture. This mixture constitutes the mixed layer ion exchange absorbent polymer composition (Sample MB-2 of the present invention).

(Iv) Measuring PUP Capability About 0.9 gram of the mixed layer ion exchange absorbent polymer composition (Sample MB-2) was transferred to a PUP cylinder (as described in the test method section above) and Gently spread over the entire net that makes up the surface. The amount of liquid absorbed was measured at short intervals over 16 hours and the PUP under 0.7 psi confining pressure and 1.4 psi
Performance is measured on a separate sample. The PUP performance measured at 0.7 psi and 1.4 psi as a function of time is shown in FIGS. 3 and 4, respectively. 2 hours, 4 hours,
Selected PUP potency data at 8 hours and 16 hours are shown in Table 5 below. Table 5 PUP capacity of mixed layer ion exchange absorbent polymer composition 0.7 psi 0.7 psi 0.7 psi 1.4 psi 1.4 psi 1.4 psi (4 hrs) (8 hrs) (16 hrs) (2 hrs) (8 hrs) (16 hrs) Sample MB-2 41 g / g 43 g / g 44 g / g 33 g / g 40 g / g 42 g / g Control sample 33 g / g 33 g / g 33 g / g 20 g / g 20 g / g 20 g / g

Comparing the PUP capacity, under the above test conditions, the mixed layer ion exchange absorbent polymer composition (Sample MB-2) was better than the partially neutralized polyacrylate absorbent polymer (Control sample) in the synthetic urine solution. It can be seen that a large amount is absorbed.

Example 3 Preparation of an ion exchange absorbent polymer (i) Cation exchange absorbent polymer A cation exchange absorbent polymer is prepared as described in Example 1, paragraph (i) (
Sample PAA).

(Ii) Anion Exchange Absorbable Polymer (a) Preparation of Linear Polyethylenimine Poly (2-ethyl-2-oxazoline) having a nominal weight average molecular weight of 500,000 g / mol was prepared using Aldrich Chemical Co., Milwaukee, Wisconsin. Obtained from Chemical Company (catalog number 37,397-4, lot number 17223HG)
. In a hydrochloric acid solution obtained by mixing 1000 ml of water and 200 ml of concentrated hydrochloric acid, 100 g of poly (2-ethyl-2-oxazoline) is dissolved. The solution is refluxed at 100 ° C. for 72 hours and then cooled to room temperature. While stirring, add 50% sodium hydroxide solution to 25
The product is precipitated from the reaction solution by dropwise addition of 6 ml. The white solid precipitate is collected by vacuum filtration and washed with 5000 ml of water. The product is dried under high vacuum for 48 hours to obtain a linear polyethyleneimine.

B) Preparation of crosslinked linear polyethyleneimine 5.0 g of the linear polyethyleneimine obtained above is dissolved in 50 ml of methanol. Ethylene glycol diglycidyl ether (50% solution) (Aldrich Chemical Co., Catalog No. E2, 720-3,
(Lot number 07405DN) is added and the mixture is stirred at room temperature for about 2 minutes and then placed in a vented oven at about 65 ° C for 3 hours. The resulting gel is broken down to a size of about 5 mm in diameter and gently stirred overnight in 500 ml of methanol. The sample is collected by decantation and dried under high vacuum for about 48 hours to yield a lightly crosslinked polyethyleneimine anion exchange absorbent polymer. This is stored under a dry atmosphere (sample LPEI-1).

C) Partial methylation of the cross-linked polyethyleneimine The linear polyethyleneimine obtained above is dissolved in 5.37 g, 45 g of methanol. Ethylene glycol diglycidyl ether (50% solution) (Aldrich Chemical Co., Catalog No. E2, 720-) is added to this linear polyethyleneimine solution.
3, lot number 07405DN) and add the mixture at room temperature to about 2
Stir for 5 minutes and place in a vented oven at about 65 ° C. for 3 hours. The resulting gel is broken down to a size of about 5 mm in diameter and gently stirred overnight in 500 ml of methanol. The sample is collected by decantation and dried under high vacuum for about 48 hours to yield a lightly crosslinked polyethyleneimine anion exchange absorbent polymer. This is stored under a dry atmosphere (sample LPEI-2).

Formic acid (96% solution) (Aldrich Chemical Co., Catalog No. 25,136)
-4) 48.44 grams and 81.17 grams of formaldehyde (37% solution) (Aldrich Chemical Co., catalog number 25,254-9) were added to 370.39 grams of distilled water, and 500 grams of the stock solution was added. obtain. 46.
98 grams, 5.37 grams of cross-linked linear polyethyleneimine (sample LPEI
-2). The mixture is further diluted with 450 ml of distilled water and placed in a 70 ° C. oven for 24 hours. The gel is recovered by decantation and stirred overnight in 2500 ml of water to remove extractable components. Decant off the supernatant and remove
Instead, 20 ml of a 50% aqueous solution of sodium hydroxide is added to remove excess formic acid in the gel. The mixture is left for about 3 hours, and the supernatant is removed by decanting to recover the polymer. This process is repeated using 20 ml of a 50% aqueous solution of sodium hydroxide until the pH is 13 (about three times). The gel is collected by vacuum filtration and immersed in 1000 ml of water overnight. The supernatant is decanted off and 500 ml of tetrahydrofuran are added instead. After 24 hours, the tetrahydrofuran is decanted off and instead 500 ml of anhydrous ether are added. After 24 hours, the ether is decanted off and the gel is dried under high vacuum at room temperature for 48 hours. NMR spectroscopy of the product shows that about 65 percent of the amine groups in the polymer have been methylated to form a tertiary amine component (Sample N
MEI-65).

(Iii) Mixed Layer Ion Exchange Absorbent Polymer Crosslinked Linear Polyethyleneimine Anion Exchange Absorbent Polymer and Poly (N-methylethyleneimine) Anion Exchange Absorbent Polymer (Sample LPEI-1 and Sample NMEI-65) Are individually ground at cryogenic temperatures and sieved under a dry nitrogen atmosphere. For each material, collect the particle size fraction (i.e., the fraction of particles about 200-700 microns in diameter) that passes through a U.S. standard 25 mesh screen but not through a U.S. standard 70 mesh screen.

Each of the crosslinked anion exchange absorbent polymers (Sample LPEI-
1, and sample NMEI-65) are mixed separately with about 1 gram of sieved cross-linked poly (acrylic acid) cation exchange absorbent polymer (sample PAA) and the particles of each polymer are homogenized throughout the mixture. Disperse in. These mixtures are
The mixed layer ion exchange absorbing polymer composition of the present invention (each sample MB-3a)
, And sample MB-3b).

(Iv) Measuring PUP Capability A mixed layer ion exchange absorbent polymer composition (Sample MB-3a and Sample MB-3b) of about 0.9 gram was loaded into a PUP cylinder (as described in the test method section above). And gently spread it over the net that makes up the low side of the cylinder. The amount of liquid absorbed is measured at short intervals over a period of 16 hours, and the PUP capacity under a confining pressure of 0.7 psi and under 1.4 psi is measured on separate samples. 0.7p
The PUP performance measured at si and 1.4 psi as a function of time is shown in FIGS. 3 and 4, respectively. Selected PUP performance data at 4, 8, and 16 hours are shown in Table 6 below. Table 6 PUP capacity of mixed layer ion exchange absorbent polymer composition 0.7 psi 0.7 psi 0.7 psi 1.4 psi 1.4 psi (4 hrs) (8 hrs) (16 hrs) (8 hrs) (16 hrs) Sample MB-3a --- 32 g / g 37 g / g sample MB-3b 39g / g 42g / g 43g / g --- control sample 33g / g 33g / g 33g / g 20g / g 20g / g

When comparing the PUP capacity, under the test conditions described above, the mixed layer ion exchange absorbent polymer composition (Sample MB-3a and Sample MB-3b) was partially neutralized polyacrylate absorbent polymer (control sample). It can be seen that the synthetic urine solution is absorbed much more than the above.

Example 4 Preparation of an ion exchange absorbent polymer (i) Preparation of a cation exchange absorbent polymer crosslinked polyacrylic acid Acrylic monomer (Aldrich Chemical Co., Wis.) In a clean 4000 ml resin kettle Milwaukee, catalog number 14,72
3-0, lot number 15930CS), and synthesize uniformly crosslinked polyacrylic acid. N, N'-methylenebisacrylamide (Aldrich Chemical Co., catalog number 14,607-2, lot number 04511DR
) 7.2 g and 0.85 g of 2,2'-azobis (2-amidinopropane) dihydrochloride (Wako, lot number P2197) are dissolved in 2050 g of distilled water, and acrylic acid in the resin reaction kettle is dissolved. Add to monomer. The solution is flushed with nitrogen for 15 minutes to remove dissolved oxygen. Thereafter, the resin kettle is sealed and the solution is heated at 40 ° C. for 16 hours.

After cooling the obtained gel, it is broken into a size of about 1 cm in diameter and dried in a vacuum oven at 55 ° C. for 60 hours. This sample was crushed using a Willy mill,
Sieve through a 20 mesh US standard mesh to obtain uniformly crosslinked polyacrylic acid (sample PAA-2).

(Ii) Preparation of Anion Exchange Absorbable Polymer Cross-Linked Polyallylamine 1250 g of a 20% solution of polyallylamine (PAA-H) (Nitto Boseki Co., Ltd., Tokyo, Japan, lot number 80728) was mixed with 2000 ml of glass. Weigh in jar. 19 grams of a 50% solution of ethylene glycol diglycidyl ether (Aldrich Chemical Co., catalog number E2, 720-3) is diluted with 20 grams of distilled water and added to the polyallylamine solution. The mixture is stirred at room temperature for about 2 minutes and then placed in a vented oven at about 60 ° C. overnight.

When the obtained gel is broken into a size of about 5 mm in diameter and dried under high vacuum for about 96 hours, a lightly crosslinked polyallylamine anion exchange absorbent polymer is obtained. This is stored under a dry atmosphere (sample PAAM-2).

(Iii) Mixed Layer Ion Exchange Absorbent Polymer Crosslinked Polyallylamine Anion Exchange Absorbent Polymer (Sample PAAM-2)
And sieved. It passes through the U.S. standard 25 mesh sieve, but U.S. standard 7
The 0 mesh sieve collects the size fraction that does not pass (i.e., the fraction of particles of about 200-700 microns in diameter).

About 125 grams of sieved crosslinked polyacrylic acid (200-700 microns in diameter) cation exchange absorbent polymer (Sample PAA-2) and sieved crosslinked polyallylamine anion exchange absorbent polymer (Sample PAAM-2) ) To 125
Gram blend to uniformly disperse both polymer particles throughout the mixture.
This mixture is used as a mixed layer ion exchange absorbent polymer composition (Sample MB of the present invention).
-4).

(Iv) Measuring PUP Capability [0149] About 0.9 grams of the mixed layer ion exchange absorbent polymer composition (Sample MB-4) was transferred to a PUP cylinder (as described in the test method section above) and the cylinder low. Gently spread over the entire net that makes up the surface. The amount of liquid absorbed was measured at short intervals over 16 hours and the PUP under 0.7 psi confining pressure and 1.4 psi
Performance is measured on a separate sample. Selected PUP potency data at 2, 4, 8 and 16 hours are shown in Table 7 below. Table 7 PUP capacity of mixed layer ion exchange absorbent polymer composition 0.7 psi 0.7 psi 0.7 psi 1.4 psi 1.4 psi 1.4 psi (4 hrs) (8 hrs) (16 hrs) (2 hrs) (8 hrs) (16 hrs) Sample MB-4 53 g / g 56 g / g 59 g / g 38 g / g 50 g / g 55 g / g Control sample 33 g / g 33 g / g 33 g / g 20 g / g 20 g / g 20 g / g

When comparing the PUP capacity, under the test conditions described above, the mixed layer ion exchange absorbent polymer composition (Sample MB-4) was more effective than the partially neutralized polyacrylate absorbent polymer (Control sample) in the synthetic urine solution. It can be seen that a large amount is absorbed.

(V) Measurement of CUP About 0.9 gram of the mixed layer ion exchange absorbent polymer composition (Sample MB-4) was transferred to a CUP cylinder (described in the test method section above) and the lower surface of the cylinder was measured. Gently spread over the entire network that constitutes. The amount of liquid absorbed was measured at short intervals over 16 hours and the CUP under 0.7 psi confining pressure and 1.4 psi.
Is measured on a separate sample. The CUP measured at 0.7 psi and 1.4 psi as a function of time are shown in FIGS. 5 and 6, respectively. Selected CUP data at 1 hour, 2 hours, 4 hours, 8 hours, and 16 hours are shown in Table 8 below. Table 8 CUP data for mixed layer ion exchange absorbent polymer compositions 0.7 psi 0.7 psi 0.7 psi 0.7 psi 1.4 psi 1.4 psi 1.4 psi 1.4 psi (1 hr) (4 hrs) (8 hrs) (16 hrs) (1 hr) (2 hrs) (8 hrs ) (16hrs) Sample MB-4 23g / g 28g / g 29g / g 29g / g 19g / g 23g / g 28g / g 29g / g Control sample 21g / g 21g / g 22g / g 22g / g 13g / g 13g / g 15g / g 17g / g

Comparing the CUP data, under the above test conditions, the mixed layer ion exchange absorbent polymer composition (Sample MB-4) was significantly more abundant than the partially neutralized polyacrylate absorbent polymer (Control sample). It can be seen that the high ionic strength synthetic urine solution is absorbed.

Example 5 Preparation of Ion Exchange Absorbent Polymer (i) Preparation of Cation Exchange Absorbent Polymer Crosslinked Polyacrylic Acid Acrylic monomer (Aldrich Chemical Co., Catalog No.) in a clean 500 ml resin kettle 14,723-0, lot number 15930CS)
Is added to synthesize uniformly crosslinked polyacrylic acid. N,
0.65 g of N'-methylenebisacrylamide (Aldrich Chemical Co., catalog number 14,607-2, lot number 04511DR) and 2,2'-azobis (2-amidinopropane) dihydrochloride (Wako, lot number P219)
7) Dissolve 0.076 grams in 200 grams of water and add to the acrylic acid monomer in the resin kettle. The solution is flushed with nitrogen for 15 minutes to remove dissolved oxygen. Thereafter, the reaction kettle made of resin is sealed, and the solution is heated at 40 ° C. for 16 hours to obtain a lightly crosslinked polyacrylate cation exchange-absorbable polymer gel (sample PAA-3).

(Ii) Preparation of Anion Exchange Absorbable Polymer Crosslinked Polyallylamine 202 grams of a 20% solution of polyallylamine (PAA-H) (Nitto Boseki Co., Ltd., Tokyo, Japan, lot number 80728) was mixed with 500 ml of glass. Weigh in jar. A 50% solution of ethylene glycol diglycidyl ether (Aldrich Chemical Co., Catalog No. E2, 720-) was added to this polyallylamine solution.
3.0 grams of 3) is added. The mixture is stirred at room temperature for about 2 minutes and then
When placed in a vent oven at 2 ° C. for 2 hours, a lightly crosslinked polyallylamine anion exchange absorbent polymer gel (sample PAAM-3) is obtained. .

(Iii) In a mixed layer ion exchange absorbing polymer Osterizer blender (model # 855-08K), about 20 grams of crosslinked polyallylamine anion exchange absorbing polymer gel (sample PAAM-3) and Acrylic acid cation exchange absorbent polymer gel (Sample PAA-
Add about 20 grams of 3). The cation exchange absorbent polymer gel and the anion exchange absorbent polymer gel are mixed at a high speed in the blender for a total of 1 while allowing the gels to mix well (eg, while scraping the blender wall so that all substances reach the mixing zone). Mix for 5 minutes. The resulting mixture of cation exchange absorbent polymer and anion exchange absorbent polymer is dried under high vacuum for about 96 hours.

A mixture of the cation exchange absorbent polymer and the anion exchange absorbent polymer is ground and sieved. The particle size fraction (i.e., the fraction of particles having a diameter of about 200-700 microns) that passes through a U.S. standard 25 mesh screen but does not pass through a U.S. standard 70 mesh screen is collected and mixed layer ion exchange absorbent polymer composition Get things. The resulting particles contain bicontinuous regions of both an anion exchange absorbent polymer and a cation exchange absorbent polymer (Sample MB-5 of the present invention).

(Iv) Measuring PUP Capability About 0.9 gram of the mixed layer ion exchange absorbent polymer composition (Sample MB-5) was transferred to a PUP cylinder (as described in the test method section above) and Gently spread over the entire net that makes up the surface. The amount of liquid absorbed was measured at short intervals over 16 hours and the PUP under 0.7 psi confining pressure and 1.4 psi
Performance is measured on a separate sample. Selected PUP potency data at 2, 4, 8 and 16 hours are shown in Table 9 below. Table 9 PUP capacity of mixed layer ion exchange absorbent polymer composition 0.7 psi 0.7 psi 0.7 psi 1.4 psi 1.4 psi 1.4 psi (4 hrs) (8 hrs) (16 hrs) (2 hrs) (8 hrs) (16 hrs) Sample MB-5 45 g / g 48 g / g 52 g / g 29 g / g 32 g / g 41 g / g Control sample 33 g / g 33 g / g 33 g / g 20 g / g 20 g / g 20 g / g

[0158] Comparing the PUP capacity, under the above test conditions, the mixed layer ion exchange absorbent polymer composition (Sample MB-5) was more effective than the partially neutralized polyacrylate absorbent polymer (Control sample) in the synthetic urine solution. It can be seen that a large amount is absorbed.

(V) Measurement of CUP About 0.9 gram of the mixed layer ion exchange absorbent polymer composition (Sample MB-5) was transferred to a CUP cylinder (as described in the test method section above) and the lower surface of the cylinder was measured. Gently spread over the entire network that constitutes. The amount of liquid absorbed was measured at short intervals over 16 hours and the CUP under 0.7 psi confining pressure and 1.4 psi.
Is measured on a separate sample. The CUP measured at 0.7 psi and 1.4 psi as a function of time are shown in FIGS. 5 and 6, respectively. Selected CUP data at 1 hour, 2 hours, 4 hours, 8 hours, and 16 hours are shown in Table 10 below. Table 10 CUP data for mixed layer ion exchange absorbent polymer compositions 0.7 psi 0.7 psi 0.7 psi 0.7 psi 1.4 psi 1.4 psi 1.4 psi 1.4 psi (1 hr) (4 hrs) (8 hrs) (16 hrs) (1 hr) (2 hrs) (8 hrs ) (16hrs) Sample MB-5 29g / g 30g / g 31g / g 31g / g 28g / g 29g / g 30g / g 30g / g Control Sample 21g / g 21g / g 22g / g 22g / g 13g / g 13g / g 15g / g 17g / g

Comparing the CUP measurements, under the above test conditions, the mixed layer ion exchange absorbent polymer composition (sample MB-5) was higher than the partially neutralized polyacrylate absorbent polymer (control sample). It can be seen that the ionic strength synthetic urine solution is absorbed considerably.

The disclosures of all patents, patent applications (and all patents issued therefrom, as well as all corresponding foreign patent applications published) and publications mentioned herein are incorporated by reference. To the extent at least consistent with the terms and definitions disclosed in the specification, they are provided herein by reference. It is expressly acknowledged, however, that none of the documents mentioned herein as a reference teach or disclose the invention.

While specific embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. Of course. It is therefore intended that the appended claims cover all such changes and modifications as fall within the scope of the invention.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an apparatus for measuring the performance under pressure (PUP) of an absorbent polymer.

FIG. 2 is an enlarged cross-sectional view of the piston / cylinder assembly shown in FIG.

FIG. 3 shows a constraint pressure of 0 for the present invention and prior art absorbent polymer compositions.
. Figure 4 graphically illustrates PUP capacity data measured at 7 psi.

FIG. 4 shows a constraint pressure of 1 for the present invention and prior art absorbent polymer compositions.
. Figure 4 graphically illustrates PUP ability data measured at 4 psi.

FIG. 5 shows a constraint pressure of 0 for the present invention and prior art absorbent polymer compositions.
. 7 is a graph showing CUP data measured under 7 psi.

FIG. 6 shows a constraint pressure of 1 for the present invention and prior art absorbent polymer compositions.
. 4 is a graph showing CUP data measured under 4 psi.

FIG. 7 is a schematic diagram of an apparatus for preparing a sample of an absorbent polymer composition to measure the ball burst strength (BBS) of the composition.

FIG. 8 is a schematic diagram of an apparatus for measuring a ball burst strength (BBS) of an absorbent polymer composition.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 33/02 A61F 13/18 307A 39/00 (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CU, CZ, DE, DK, EE, S, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU , LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, UZ, VN, YU, ZW (72) Inventor Brine, Hard, Ohio, Cincinnati, USA, Eagle, Creek, Road, 8519 (72) Inventor Ahman, Ashraf, Ohio, Cincinnati, Napoleon, Rain, 1581 ( 72) Inventor John, Collins, Dyer, Ohio, Cincinnati, Sherbrooke, Drive, 3760 (72) Inventor Robert, Earl, Magnes United States of America Ohio, tip, tee, Hartman, Abenyu, 152 (72) inventor Stephen, Allen, Goldman Italy country Citta, Esse. Angelo, Via, Corle, Di, Moro, 62 F term (reference) 4C003 AA23 4C098 AA09 CC03 DD22 DD23 DD24 DD25 4J002 BE05W BG01X BJ00W

Claims (10)

[Claims] 1. Mixed layer ion exchange characterized in that the absorption capacity under pressure (CUP) after 1 hour under a load of 0.7 psi for a high ionic strength synthetic urine solution is at least about 23 g / g. Absorbent polymer composition. 2. The mixed-layer ion of claim 1, wherein the high ionic strength synthetic urine solution has an absorption capacity under pressure (CUP) after 1 hour under a load of 0.7 psi of about 23 to about 35 g / g. Exchange composition. 3. The absorption capacity under pressure (CUP) of the high ionic strength synthetic urine solution after 4 hours under a load of 0.7 psi of at least about 25 g / g, preferably 27 g / g.
g, more preferably 30 g / g, of a mixed layer ion exchange absorbent polymer composition. 4. The high ionic strength synthetic urine solution has an absorbency under pressure (CUP) after 2 hours under a load of 1.4 psi of at least about 20 g / g, preferably 23 g / g.
, And more preferably 27 g / g. 5. The high ionic strength synthetic urine solution has an absorption capacity under pressure (CUP) after 2 hours under a load of 1.4 psi of about 20 to about 35 g / g, preferably about 23 to about 3 g / g.
5. The mixed layer ion exchange composition of claim 4, wherein the composition is 2 g / g. 6. The composition according to claim 1, wherein (i) ethyleneimine, allylamine, vinylformamide,
And (ii) a cation exchange polymer made from a monomer blend comprising an acrylic acid monomer, wherein the cation exchange polymer is made from a monomer selected from the group consisting of: A mixed layer ion exchange composition according to any of the preceding claims, characterized in that the polymer is homogeneously crosslinked. 7. The composition according to claim 1, wherein (i) ethyleneimine, allylamine, vinylformamide,
And an anion exchange absorbent polymer made from a monomer selected from the group consisting of: and (ii) a cation exchange absorbent polymer made from a monomer blend comprising acrylic acid monomers, wherein: a. A) agglomerates of high surface area particles, b) particles in which smaller discontinuous regions of the cation exchange absorbent polymer are dispersed in the anion exchange absorbent polymer, c) in the cation exchange absorbent polymer, Fast ions selected from the group consisting of particles having a discontinuous region of an anion exchange absorbent polymer dispersed therein and d) particles comprising both bicontinuous regions of an anion exchange absorbent polymer and a cation exchange absorbent polymer. In order to obtain a particle form suitable for the exchange rate,
The mixed layer ion exchange composition according to any one of the preceding claims, wherein the anion exchange absorbent polymer and the cation exchange absorbent polymer are blended. 8. The mixed layer ion exchange composition of claim 7, wherein said region is formed using a blending technique selected from the group consisting of a high shear blend, a ball mill, and a pin mill. 9. An absorbent member for containing an aqueous body fluid, comprising at least one portion comprising the mixed layer ion exchange composition according to any one of the above claims. 10. A liquid-permeable topsheet, a backsheet, and an absorbent core located between the topsheet and the backsheet, wherein the absorbent core comprises the absorbent member of claim 9. Absorbent products.