JP2000083996A - Absorptive article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an absorbent article which is not only excellent in absorption of body fluid, such as urine, but also excellent in the body fluid retaining property to substantially prevent the deterioration and decomposition even in the state of absorbing the body fluid. SOLUTION: This absorptive article is constituted by disposing an absorbent contg. a water absorptive resin and a hydrophilic fiber material between a liquid permeable top sheet and a liquid impermeable back sheet. Aminopolycarboxylic acid and/or its salt is formulated with the hydrophilic fiber material. The aminopolycarboxylic acid and/or its salt is preferably the pentavalent or higher valent aminopolycarboxylic acid and/or its salt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an absorbent article.
More particularly, the present invention relates to absorbent articles such as disposable diapers, pads, and female sanitary napkins for infants, adults, or incontinent persons.

[0002]

2. Description of the Related Art In recent years, absorbent articles such as disposable diapers for infants, adults and incontinent persons, pads, and sanitary napkins for women have been widely used for the purpose of absorbing body fluids.

[0003] As an absorber of such an absorbent article,
A composite of a hydrophilic fibrous material such as cotton, pulp, paper or the like and a water-absorbing resin is used. In recent years, from the viewpoint of portability and wearability, there has been an increasing tendency to make these absorbent articles compact, and absorbent articles having an increased ratio of the water-absorbing resin in the absorber have also appeared.

[0004] In the case where the proportion of the water-absorbing resin is increased as described above, the action of the L-ascorbic acid component contained in urine or the like and a trace amount of metal ions contained in the hydrophilic fiber material and the like are particularly effective. The swollen gel tends to deteriorate and decompose over time. As a result, the absorbent may not be able to stably retain body fluids, causing liquid leakage, soiling the trousers, sheets, clothes, etc., and increasing the amount of liquid return that occurs when a load such as body weight is applied to the absorbent. Sometimes it caused discomfort.

[0005] As described above, the conventional absorbent article using a water-absorbent resin for the absorber has a problem that the body fluid retention of the absorber deteriorates with time, and liquid leakage and liquid return are likely to occur. .

[0006]

Therefore, the water-absorbent resin in the absorbent absorbs the body fluid, and the swelling gel deteriorates with time.
Various methods have been proposed for suppressing the decomposition and stabilizing the body fluid retention of the absorber. For example, JP-A-6-26
1924 discloses a liquid-permeable sheet containing a substance that captures ions. However, the degradation and decomposition of the water-absorbent resin in the absorber depends on trace metal ions and L
-Since ascorbic acid is caused by acting on the water-absorbent resin, it is necessary to reduce the influence of metal ions in the hydrophilic fiber material near the water-absorbent resin.

[0007] Accordingly, an object of the present invention is to provide an absorbent article excellent in body fluid retention, in which deterioration of physical properties over time due to deterioration or decomposition of a water-absorbent resin is suppressed.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, have found that a liquid permeable top sheet is a composite of a hydrophilic fiber material and a water absorbing resin between liquid impermeable sheets. The present inventors have found that the above problems can be solved by using an absorbent article having a body, in which an aminopolycarboxylic acid and / or a salt thereof is added to a hydrophilic fiber material, and have completed the present invention.

That is, the present invention provides an absorbent article comprising an absorbent containing a water-absorbing resin and a hydrophilic fiber material provided between a liquid-permeable top sheet and a liquid-impermeable back sheet. Aminopolycarboxylic acid and / or
Or, an absorbent article provided with a salt thereof is provided.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, examples of hydrophilic fiber materials include cellulose fibers such as mechanical pulp, chemical pulp, semi-chemical pulp, and dissolved pulp obtained from wood; artificial cellulose fibers such as rayon and acetate; and thermoplastic fibers. And the like, and the shape is, for example, fibrous, or tissue paper, and those formed into a sheet shape such as a pulp mat, and the like. There is no particular limitation as long as it is used for the absorber.

As the water-absorbing resin that can be used in the present invention, any water-absorbing resin that is generally used can be used, but it is a resin that absorbs a large amount of water in water to form a hydrogel. And preferably has a carboxyl group. Examples of such a water-absorbing resin include a crosslinked product of partially neutralized polyacrylic acid, starch-
Acrylonitrile graft polymer hydrolyzate, starch-acrylic acid graft polymer hydrolyzate, vinyl acetate-acrylate copolymer saponified product, acrylonitrile copolymer or acrylamide copolymer hydrolyzate or these Examples thereof include a crosslinked product, a carboxyl group-containing crosslinked polyvinyl alcohol modified product, and a crosslinked isobutylene-maleic anhydride copolymer. As the shape of the water-absorbent resin, various shapes such as irregularly crushed, spherical, substantially spherical, and scale-like shapes can be used.

Further, it is preferable that these polymers are surface cross-linked by a surface cross-linking agent having two or more functional groups capable of reacting with a carboxylic acid in the vicinity of the surface.

Examples of the aminopolycarboxylic acid and / or its salt include, for example, iminodiacetic acid, N- (2-hydroxyethyl) iminodiacetic acid, nitrilotriacetic acid, N- (2-hydroxyethyl) ethylenediamine-N, N ', N'-triacetic acid, ethylenediamine-N, N, N', N'-tetraacetic acid, ethylenediamine-N-monoacetic acid, ethylenediamine-N,
N'-diacetate, diethylenetriamine-N, N, N ', N'',
N ''-pentaacetic acid, triethylenetetramine-N, N, N ',
N '', N ''',N'''-hexaacetic acid, 1,2-cyclohexanediamino-N, N, N ', N'-tetraacetic acid, ethylene glycol diethyletherdiaminetetraacetic acid, ethylenediaminetetrapropionacetic acid, 3,6-dioxa-1,8
-Octanediamine-N, N, N ', N'-tetraacetic acid and alkali metal salts, ammonium salts or amine salts thereof.

Among the above-mentioned aminopolycarboxylic acids and / or salts thereof, pentavalent or higher valent aminocarboxylic acids and salts thereof are preferable because of their high effects. Still more preferably,
One or two or more kinds of diethylenetriaminepentaacetic acid and a salt thereof, and triethylenetetraaminehexaacetic acid and a salt thereof are used.

In addition, thermoplastic fibers, organic powders of natural polysaccharides, inorganic powders such as zeolite, activated carbon, and finely divided silica, coloring agents, antibacterial agents, bactericides, and fragrances are mixed with the absorber, or It may be added.

The method of adding the aminopolycarboxylic acid and / or its salt is not particularly limited. For example, a hydrophilic fiber material such as pulp and the aminopolycarboxylic acid and / or its salt are wet-mixed or dry-mixed. How to keep it mixed. A method of mixing aminopolycarboxylic acid and / or a salt thereof when dry mixing a hydrophilic fiber material and a water-absorbing resin. Examples of the method include adding aminopolycarboxylic acid and / or a salt thereof to an absorbent (formed into a sheet) made of a hydrophilic fiber material and a water-absorbing resin by spraying an aqueous solution or adding a powder.

The structure of the absorber is not particularly limited as long as it is a structure used for a general absorbent article. For example, a so-called sandwich structure in which a water-absorbing resin is arranged between hydrophilic fiber materials formed in a sheet shape. Absorbers and so-called blend-structured absorbers obtained by molding a mixture of a hydrophilic fiber material and a water-absorbing resin are exemplified.

The weight ratio of the water-absorbent resin to the hydrophilic fiber material in the absorber is as follows: water-absorbent resin: hydrophilic fiber material = 2
The ratio is preferably from 0:80 to 90:10, and more preferably from 30:70 to 80:20. When the weight ratio of the water-absorbent resin is less than 20 or the weight ratio of the hydrophilic fiber material exceeds 80, the performance of the absorbent article is not sufficiently exhibited, and liquid leakage or the like is likely to occur. When the weight ratio of the water-absorbent resin exceeds 90 or the weight ratio of the hydrophilic fiber material is less than 10, problems such as uneven distribution of the water-absorbent resin during use of the absorbent article occur. The performance of the article cannot be fully exhibited.

The amount of aminopolycarboxylic acid and / or salt thereof is in the range of 0.00001 to 10 parts by weight, preferably 0.00005 to 5 parts by weight, per 100 parts by weight of the hydrophilic fiber material. More preferably 0.00
The range is from 0.5 to 5 parts by weight. 0.000 chelating agent
When the amount is less than 01 parts by weight, a water-absorbent resin having excellent stability over time of the gel when swollen cannot be obtained. If the amount of the aminopolycarboxylic acid and / or its salt is more than 10 parts by weight, the aminopolycarboxylic acid and / or its salt may exude from the absorbent article.

When aminopolycarboxylic acid and / or its salt is added as an aqueous solution, the hydrophilic fiber material 10
The amount of water relative to 0 parts by weight is preferably not more than 60 parts by weight, and more preferably not more than 50 parts by weight. If the amount of water is 60 parts by weight or more based on 100 parts by weight of the hydrophilic fiber material, the hydrophilic fiber material and the water-absorbing resin cannot be uniformly blended, or molding becomes difficult, or The performance of the absorber is reduced due to the inclusion of water.

The liquid-permeable sheet used for the absorbent article is made of a material having a property of permeating an aqueous liquid, and is, for example, a nonwoven fabric or a woven fabric; a porous synthetic material made of polyethylene, polypropylene, polyamide or the like. Films and the like. The liquid-impermeable sheet is made of a material having a property of impervious to an aqueous liquid, for example, a synthetic resin film made of polyethylene, polypropylene, ethylene vinyl acetate, polyvinyl chloride, or the like, or a synthetic resin and a nonwoven fabric. And a film made of a composite material of the above synthetic resin and woven fabric. The liquid impermeable film may have a property of transmitting vapor.

The absorbent article of the present invention comprises a liquid-permeable top sheet, a liquid-impermeable back sheet, and the above-described absorber disposed between the liquid-permeable top sheet and the liquid-impermeable back sheet. Examples include disposable diapers for incontinent persons, and menstrual absorption napkins for women. The structure of the disposable diaper and menstrual absorption napkin can employ various structures similar to the conventionally known structures, and the materials of the top sheet and the back sheet also restrict the conventionally used materials. Can be used without.

The absorbent article of the present invention has a large amount of excretion and a long contact time with urine, so that the swelling gel of the water-absorbent resin is more likely to be deteriorated and decomposed more remarkably for infants and adults. Particularly effective in disposable diapers for the elderly.

[0024]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention.

Reference Example 1 67.0 parts by weight of a 37% by weight aqueous solution of sodium acrylate, 10.2 parts by weight of acrylic acid, 0.079 parts by weight of polyethylene glycol diacrylate (average number of polyethylene oxide units: 8), and 22.0 parts of water. 0 parts by weight were mixed to prepare an aqueous monomer solution. Transfer this monomer aqueous solution to a covered vat,
Nitrogen was blown into the monomer aqueous solution to reduce the amount of dissolved oxygen in the solution to 0.1 ppm or less. Under nitrogen atmosphere,
The temperature of the aqueous solution was adjusted to 18 ° C.
% By weight 2,2'-azobis (2-amidinopropane) 2
0.16 parts by weight of an aqueous solution of hydrochloride, 0.15 parts by weight of an aqueous solution of L-ascorbic acid of 0.5% by weight, 0.16 parts by weight of an aqueous solution of sodium persulfate of 5% by weight, and 0.17 parts by weight of an aqueous solution of hydrogen peroxide of 0.15% Parts by weight were added in order. Polymerization started immediately after the addition of hydrogen peroxide, and after 10 minutes, the temperature of the monomer reached the peak temperature. The peak temperature at this time was 85 ° C. Subsequently, the vat was immersed in a hot water bath at 80 ° C. and aged for 10 minutes. The resulting transparent hydrogel was crushed with a meat chopper and then dried at 170 ° C. for 40 minutes. This dried product was pulverized with a pulverizer, passed through a 500 μm sieve,
The material remaining on the μm sieve was classified. This classifier 100
A composition liquid composed of 0.03 parts by weight of ethylene glycol diglycidyl ether, 1 part by weight of propylene glycol, 3 parts by weight of water and 1 part by weight of isopropyl alcohol is uniformly mixed with respect to parts by weight, and treated at 180 ° C. for 40 minutes. A water-absorbing resin was obtained.

The physical properties of the polymer obtained as described above are as follows:
Absorption capacity for a 0.9% by weight aqueous sodium chloride solution is 45 times. The absorption capacity under a load of 0.7 psi was 28 times.

Example 1 40 parts by weight of the water-absorbent resin obtained in Reference Example 1 and 60 parts by weight of ground wood pulp were dry-mixed with a mixer. The obtained mixture is 200 mm × 20
It was formed into a web having a size of 0 mm. By pressing this web at a pressure of 2 kg / cm ² for 5 seconds, a basis weight of 500 g /
An m ² absorber was obtained. A diethylenetriaminepentaacetic acid pentasodium aqueous solution (concentration: 1% by weight)
g was spray-added uniformly. Next, a liquid-impermeable polypropylene backsheet, the absorber, and a liquid-permeable polyethylene topsheet were adhered to each other in this order with a double-sided tape to obtain an absorbent article.

<Example 2> When 40 parts by weight of the water-absorbent resin obtained in Reference Example 1 and 60 parts by weight of the ground wood pulp were dry-mixed with a mixer, triethylene tetraamine 6
An aqueous solution of hexasodium acetate (concentration: 5% by weight) was added in an amount of 1 part by weight based on 100 parts by weight of the pulverized wood pulp to obtain a mixture. Using 60 parts by weight of this mixture and 40 parts by weight of the water-absorbent resin obtained in Reference Example 1, an absorber was obtained in the same manner as in Example 1. Next, a liquid-permeable polyethylene sheet and the absorber,
Then, an absorbent article was obtained by attaching a liquid-impermeable polypropylene sheet in the same manner as described above.

<Example 3> 10 parts by weight of an aqueous solution of pentasodium diethylenetriaminepentaacetate (concentration: 0.5% by weight) was uniformly added to 100 parts by weight of crushed wood pulp, and the resulting mixture was dried. A carboxylic acid added pulp was obtained. Pulp containing the aminopolycarboxylic acid 6
0 parts by weight and 40 parts by weight of the water absorbent resin obtained in Reference Example 1 were dry-mixed with a mixer. The obtained mixture was treated in the same manner as in Example 2 to obtain an absorbent article.

Comparative Example 1 40 parts by weight of the water-absorbent resin obtained in Reference Example 1 and 60 parts by weight of ground wood pulp were dry-mixed with a mixer. The obtained mixture is 200 mm × 20
It was formed into a web having a size of 0 mm. By pressing this web at a pressure of 2 kg / cm ² for 5 seconds, a basis weight of 500 g /
An m ² absorber was obtained. Next, a liquid-impermeable polypropylene backsheet, the absorber, and a liquid-permeable polyethylene topsheet were adhered to each other in this order with a double-sided tape to obtain an absorbent article.

Example 4 Examples 1-3 and Comparative Example 1
The following physical properties of the absorbent article were evaluated.
The results are shown in Table 1.

(Amount of liquid returned) 150 g of artificial urine containing 0.005% by weight of L-ascorbic acid was absorbed by an absorbent article, and the absorbent article was sealed in a polyethylene bag.
After standing at 7 ° C. for 16 hours, a paper towel on the surface of the absorber was placed, a load of 35 g / m ² was applied thereon for 2 minutes, and the amount of liquid absorbed by the paper towel was measured.

(Stability of swollen gel) 0.005% by weight L
-Absorbing 150 g of ascorbic acid-containing artificial urine into an absorbent article, sealing the absorbent article in a polyethylene bag and leaving it at 37 ° C for 16 hours, decomposing the absorbent article, and removing the water-absorbent resin therein; The appearance of the swollen gel was visually evaluated.

：: The swollen gel has neither fluidity nor spinnability and does not change its shape. Δ: The swollen gel has not been dissolved yet.
It has fluidity and spinnability, and its shape is deformed.

×: The swollen gel is partially dissolved, and most of the gel does not retain its shape.

The composition of the artificial urine is shown below.

Urea 1.9% by weight Sodium chloride 0.8% by weight Magnesium chloride 0.1% by weight Calcium chloride 0.1% by weight

[0038]

[Table 1]

[0039]

As described in detail above, the absorbent article of the present invention has no deterioration of the swollen gel when held for a long time in the state of absorbing urine, as compared with the conventional absorbent. It was one with little back.

The absorbent article of the present invention can be suitably used for sanitary materials such as disposable diapers.

Claims (2)

[Claims] 1. An absorbent article comprising an absorbent containing a water-absorbent resin and a hydrophilic fiber material provided between a liquid-permeable top sheet and a liquid-impermeable back sheet. An absorbent article comprising an aminopolycarboxylic acid and / or a salt thereof. 2. The absorbent article according to claim 1, wherein the aminopolycarboxylic acid and / or a salt thereof is a pentavalent or higher aminopolycarboxylic acid and / or a salt thereof.