JPH05149A - Disposable diaper - Google Patents

Abstract

PURPOSE:To eliminate spillage of urine from a diaper with a higher liquid absorption rate of a disposable diaper by arranging a chelate agent between a liquid permeating sheet and a water absorbing layer or in the water absorbing layer. CONSTITUTION:A water absorbing layer is made of a water absorbing resin and a chelate agent is arranged between a liquid permeating sheet and a water absorbing layer or in the water absorbing layer. The chelate agent herein used is preferably glycine, acetylacetone, dimethylglyoxime, ethylenediamine tetraacetate or a sodium salt thereof or the like. The chelate agent in the form of a liquid or an aqueous solution is preferably absorbed by active alumina, zeolite or a silica powder or turned to a microcapsule. Thus, the chelate agent is arranged at a specified part of the diaper to utilize performance of the water absorbing resin more effectively hereby achieving higher liquid absorption rate of urine for the diaper.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disposable diaper using a water absorbent resin. More specifically, the present invention makes use of the characteristics of the water absorbent resin so that the characteristics of the water absorbent resin can be further utilized in a disposable diaper in which the water absorbent resin plays an important role.

[0002]

2. Description of the Related Art The disposable diapers currently on the market are
Most of them are composed of a laminated material composed of a liquid-permeable nonwoven fabric sheet, a liquid-permeable leak-proof sheet, and a water-absorbing layer located therebetween. In such a disposable diaper, a powdery water-absorbent resin has recently been used in order to improve the water-absorbing ability of the water-absorbing layer and further reduce the thickness and weight of the diaper itself. The role of the absorption layer is to absorb a large amount of urine so that the urine does not leak from the diaper and to prevent the once absorbed urine from leaking to the outside.

[0003]

Most of the above functions depend on the performance of the water absorbent resin. However, the water retention capacity of water-absorbent resin is several tens of times that of pure water, but it decreases to several tens of times with liquid containing salt such as human urine, so urine should not leak from the diaper. In order to increase the liquid absorption amount, it was necessary to put a large amount of water absorbent resin into the disposable diaper. For this reason, the product cost of the disposable diaper becomes high, and from the production of the disposable diaper, some improvement has been required to take advantage of the high water-absorbing ability of the water-absorbent resin.

[0004]

[Means for Solving the Problems]

[Summary of the Invention] <Summary> The present invention provides a laminated material including a liquid-permeable sheet, a liquid-impermeable leak-proof sheet, and a water-absorbing layer containing a water-absorbent resin located between the both sheets. In the disposable diaper that is configured, by eliminating the problems of the prior art and making better use of the performance of the water-absorbent resin for urine, etc., a disposable diaper that increases the amount of liquid absorption and prevents urine from leaking from the diaper is provided. It is the one to be provided.

As a result of various studies, the inventors of the present invention removed the salt contained in the urine to be absorbed by some means, and then absorbed the urine into the water-absorbent resin to absorb the diaper. Therefore, the present invention has been completed by finding out that the above-mentioned increase. That is, the disposable diaper according to the present invention is composed of a liquid-permeable sheet, a liquid-impermeable leak-proof sheet, and a laminated material composed of a water-absorbing layer containing a water-absorbent resin located between the both sheets. In another disposable diaper, the chelating agent is arranged between the liquid-permeable sheet and the water-absorbing layer or / and in the water-absorbing layer.

<Effects> Disposable diapers are required to have a sufficient liquid absorption capacity so that urine does not leak from the diaper and a water retention capacity for preventing the once absorbed urine from leaking to the outside. Furthermore, the diaper itself should be as thin as possible. There is a strong demand for weight reduction and low price. for that reason,
Conventionally, the performance of a water absorbent resin has been widely used in diapers. However, in general, the water-absorbent resin has a problem that, although the water-absorbing capacity is several hundred times that of pure water, the liquid containing salt contained in human urine is reduced to several tens of times. However, it has been difficult to simultaneously satisfy the requirements for sufficient water absorption / water retention capacity and weight reduction and price reduction.

The present invention provides a solution to such a problem. By placing a chelating agent at a specific site of the diaper, the performance of the water-absorbent resin is made more effective, thereby absorbing the urine of the diaper. (EN) A light-weight and low-priced disposable diaper in which urine is prevented from leaking from a diaper even with a small amount of water-absorbent resin by increasing the amount.

[Detailed Description of the Invention] <Water Absorbent Resin> The water absorbent resin used in the present invention is a (meth) acrylic acid polymer and / or a crosslinked product thereof, a (meth) acrylic acid ester- Saponified product of vinyl acetate copolymer, and / or crosslinked product thereof, starch-acrylic acid salt graft copolymer, and / or crosslinked product thereof, saponified product of starch-acrylonitrile graft copolymer, and / or Crosslinked product thereof, saponified starch- (meth) acrylic acid ester graft copolymer, and / or crosslinked product thereof, saponified starch-acrylonitrile-vinylsulfonic acid graft copolymer, and / or crosslinked product thereof Etc. Here, "(meth) acrylic" is a generic term for "acrylic" and "methacrylic".

Further, one kind or two or more kinds of various monomers (for example, itaconic acid, acrylamide, etc.) may be copolymerized in an amount that does not deteriorate the performance of the water absorbent resin.

The polymerization method for obtaining the water absorbent resin is not particularly limited. For example, Japanese Patent Publication No. 60-25045 and Japanese Patent Laid-Open No.
7-158210, JP-A-57-21405, JP-A-57-98513, JP-A-61-87702 and the like, the details are shown. Static aqueous solution polymerization using a redox-based polymerization catalyst, (b) α, β-unsaturated carboxylic acid and its alkali metal salt aqueous solution containing sucrose fatty acid ester in the presence or absence of a crosslinking agent Suspension polymerization carried out in the presence of a radical polymerization initiator by suspending in a petroleum hydrocarbon solvent to be used, and (c) an aqueous solution of acrylic acid and an alkali salt of acrylic acid, which is an alicyclic group sharing a surfactant of HLB 8 to 12. Alternatively, suspension polymerization in the presence of a water-soluble radical polymerization initiator suspended in an aliphatic hydrocarbon solvent, (d) acrylic acid and an aqueous solution of an alkali salt of acrylic acid in a state of being impregnated in a nonwoven fabric, paper, etc. , Electronic Line and / or polymerization with redox type water-soluble radical polymerization initiator, (e) oil-soluble radical catalyst by gradually adding a polymerizable monomer such as acrylic acid into a boiling reaction mixture of a hydrophobic reaction medium with vigorous stirring. In the presence of the above, pearl polymerization and the like in which a polymerization regulator is added as necessary to perform polymerization are suitable.

The water-absorbent resin may be surface-modified with a surface-treating agent if necessary, or may be granulated or pulverized to change its shape or particle size. Can also be used.

Further, as an additive to the water-absorbent resin, there are an inert inorganic powder such as fine particle silica, titanium dioxide powder, and alumina powder, or a surface active agent, etc. It does not matter if it is done. The water-absorbent resin that can be used in the present invention has a water-absorption capacity (pure water) in the range of 100 to 2000 times, preferably 200 to 1300 times its own weight.
Double range is good. In order to absorb / hold a large amount of water with a small amount of water-absorbent resin, at least 100 times the water-absorbing capacity is required. Below this value, the amount of water-absorbent resin used will increase, and the disposable specification will increase costs, which is not desirable. .. Further, if the water absorption capacity is more than 2000 times, the gel strength is weak when absorbing water, the shape retention is weak, and the retention of retained water is lowered, which is not preferable.

The water-absorbent resin having a water absorption capacity of 400 times or less of its own weight, which is usually used in the conventional disposable diapers, has a urine absorption capacity of about 20 times, and therefore, such a material is used in the present invention. However, if a chelating agent is used, a water absorbing resin having such a small water absorbing ability can be used. Therefore, the range of selection of water-absorbent resin that can be used in disposable diapers has greatly increased.

<Chelating agent> A chelating agent is a polydentate ligand that forms a chelating compound by coordinating with a metal ion and is also called a chelating agent (Rikagaku Dictionary (Iwanami Shoten), Kagaku). Refer to the large dictionary (Maruzen Co., Ltd.). Any chelating agent of this kind can be the subject of the present invention, as long as it does not violate the spirit of the present invention.

Specific examples of preferred chelating agents in the present invention include glycine, acetylacetone, oxine, dithizone, dimethylglyoxime, ethylenediaminetetraacetic acid (EDTA) or its sodium salt, ethylenediaminetriacetic acid (HEDTA) or its sodium salt, Ethylenediamine diacetic acid (EDDA) or its sodium salt, nitrilotriacetic acid (NTA), N- (2-
Hydroxyethyl) iminodiacetic acid (HIDA), triethylenetetramine hexaacetic acid (TTHA), diethylenetriaminepentaacetic acid (DTPA), trans-1,2-cyclohexanediaminetetraacetic acid (CyDTA), glycol etherdiaminetetraacetic acid (EGTA), etc. is there.

These chelating agents are handled in the solid state as they are, and in the liquid state or in the aqueous solution state as absorbed on a carrier such as activated alumina, zeolite, titanium white, silica powder, or in the form of microcapsules. Preferably. In any case, the present invention may take any form as long as the performance as a chelating agent can be exhibited.

Further, these chelating agents (including those in the solid state, those supported on a carrier, those encapsulated in microcapsules, etc.) may be used in a cotton-like pulp, fibrous pulp, tissue paper, A chelating agent composite layer can be formed by mixing with a non-woven fabric or by mixing and laminating. The amount of the chelating agent used varies depending on the setting of the urine absorption amount of the disposable diaper, but since the purpose of the chelating agent is to form a chelate compound with divalent to tetravalent metal ions in urine, Although it varies slightly depending on the position where the chelating agent is arranged, it is sufficient if it is 0.8 to 5 times, preferably 1 to 3 times the theoretical amount for forming the chelate compound.

<Arrangement of Chelating Agent> A chelating agent is a chelating agent that causes a part or all of the polyvalent metal salt contained in urine to be absorbed before or when the urine is absorbed by the water-absorbent resin. It is necessary that the metal complex is formed in the diaper so that the metal complex is formed. Therefore, (a) between the liquid-permeable sheet and the water-absorbing layer, (b) in the water-absorbing layer, or (c) above (a). And (b).

<Disposable Diaper> The disposable diaper according to the present invention is composed of a laminated material composed of a liquid-permeable sheet, a liquid-impermeable leak-proof sheet, and a water-absorbing layer located between the both sheets as described above. And the chelating agent is disposed between the liquid-permeable sheet and the water-absorbing layer or (and) in the water-absorbing layer. It is a thing.

The liquid-permeable sheet and the leak-proof sheet used in the present invention are conventionally known ones. In the present invention, those conventionally used in various sanitary materials, disposable diapers and the like can be used as they are, or It can be used with appropriate modifications. For example, a thermoplastic resin sheet may be used as a leak-proof sheet, while a sufficiently fine non-woven fabric made of a thermoplastic resin material may be used as a liquid-permeable sheet, or a thermoplastic resin sheet once made impermeable. It is possible to use any purposeful one such as one provided with fine communication holes by electron beam irradiation or the like.

The method for producing a disposable diaper of the present invention is essentially the same as the method for producing a conventional disposable diaper except that a step for placing a chelating agent at a predetermined site is added. .. For example, (a) after spraying a water-absorbent resin together with a chelating agent on a water-absorbent paper such as continuous cotton-like pulp or tissue paper, if necessary,
Other water-absorbent papers are piled up, or (b) the water-absorbent resin obtained as a sheet on a support is sandwiched with a chelating agent, if necessary, and then the above water-absorbent resin and chelating agent are embossed or the like. Or (c) a substrate obtained by impregnating a substrate with a monomer to form a water-absorbing resin there, and optionally applying a chelating agent to form a water-absorbing layer. Can be manufactured by cutting a leak-proof sheet on one side, fixing a cotton-like pulp layer having a chelating agent arranged on the other side and a liquid-permeable sheet, and cutting the sheet into a predetermined shape. ..

Further, in the present invention, in order to improve the water-absorbing property of the water-absorbing layer, a fibrous pulp is mixed in the powdery water-absorbent resin, or an adhesive tape or gather for attaching the diaper to the body is provided. It is also possible to add steps. Therefore, the disposable diaper according to the present invention also includes the one to which such a conventionally known auxiliary material for improving the water absorption property or the feeling of use is added.

[0023]

The following experimental examples will more specifically illustrate the present invention. Therefore, it goes without saying that the present invention is not limited to these. The present invention has the main characteristics in the water absorbing layer constituting the diaper, and the effects of the present invention are mainly brought about by this water absorbing layer. Therefore, although the following Experimental Examples 2 to 10 are about the water absorbing layer of the diaper, it can be said that this is the effect of the disposable diaper of the present invention.

Artificial urine composition Urine 1.94% Sodium chloride 0.80% Calcium chloride 0.06% Magnesium sulfate 0.11% Pure water 97.09%

Amount of artificial urine absorption of water-absorbent resin 1 g of water-absorbent resin was added to a 400-mesh nylon bag (10 cm
X 10 cm) 30 in 1 liter of artificial urine
Soak for a minute (at the same time, soak a blank nylon bag). After 30 minutes, the nylon bag was pulled up, drained for 15 minutes, weighed, blank-corrected, and the weight of the artificial urine absorbed by 1 g of the water-absorbent resin was taken as the amount of absorbed liquid.

Amount of artificial urine absorbed by a water-absorbent resin treated with a chelating agent 100 parts by weight of artificial urine were used as a chelating agent of ethylenediaminetetraacetic acid disodium salt (Na ₂ H ₂ Y · 2H ₂ O).
0.55 parts by weight was added and stirred for 10 minutes. 1 g of water-absorbent resin is a 400 mesh nylon bag (10 cm x 10 cm)
Size), and soak in 1 liter of chelating agent-treated artificial urine for 30 minutes (at the same time, soak a blank nylon bag). After 30 minutes, pull up the nylon bag, drain for 15 minutes, weigh, weigh the blank, and correct the weight to 1 g of water-absorbent resin.
The weight of the chelating agent-treated artificial urine absorbed by was taken as the amount of absorbed liquid.

Water- Absorbent Resin Water-Absorbent Resin 1: Commercially Available Crosslinked Sodium Polyacrylate (Trade Name: Aqua Keep 10SH) Water-Absorbent Resin 2: Commercially Available Crosslinked Sodium Polyacrylate (Tradename: Diawet) Water-Absorbent Resin 3: Commercially available cross-linked starch-acrylic acid graft copolymer (trade name: Sunwet IM-1000)

<Experimental Example 1 (Reference Experimental Example 1)> Table 1 shows the amount of artificial urine absorption of each water absorbent resin and the amount of artificial urine absorption treated with a chelating agent.

<Experimental Examples 2 to 4 (Comparative Experimental Examples 1 to 3)> Three sheets of cotton-like pulp (weighed 150 g / m ² , 10 cm × 10 cm in size) were prepared. 1 g of various water-absorbent resins were evenly distributed between two sheets of cotton-like pulp, and the cotton-like pulp was compressed to form a water absorbing layer. On the other hand, the remaining flocculent pulp was compressed to form a pulp layer. Place this pulp layer on the above water-absorbent layer, lightly compress it, absorb 30 ml of artificial urine from the center, and after 15 minutes, return the artificial urine that returns for 3 minutes at a pressure of 40 g / cm ² to a filter paper. It was made to absorb liquid. Table 2 shows the amount of return.

<Experimental Examples 5 to 7 (Examples 1 to 3)> As in Experimental Examples 2 to 4, cotton-like pulp (weighing 150 g / m ² , 1
Three pieces of 0 cm × 10 cm size) were prepared. 1 g of various water-absorbent resins were evenly distributed between two sheets of cotton-like pulp, and the cotton-like pulp was compressed to form a water absorbing layer. On the other hand, 0.24 g of ethylenediaminetetraacetic acid tetrasodium salt (Na ₄ Y.4H ₂ O) was applied as a chelating agent to the remaining cotton-like pulp and then compressed to form a chelating agent composite layer. This chelating agent complex layer is placed on the water absorbing layer and lightly compressed, and then 30 ml of artificial urine is absorbed from the central portion to
After 5 minutes, artificial urine returning for 3 minutes at a pressure of 40 g / cm ² was absorbed into a filter paper. Table 2 shows the amount of return.

<Experimental Examples 8 to 10 (Examples 4 to 6)> As in Experimental Examples 2 to 4, cotton-like pulp (weighing 150 g / m ² ,
3 pieces of 10 cm × 10 cm size) were prepared. Between two cotton-like pulps, 1 g of various water-absorbent resins, ethylenediaminetetraacetic acid disodium salt (Na ₂ H ₂ Y.
2H ₂ O) 0.08 g was evenly dispersed, and the cotton-like pulp was compressed to form a water absorbing layer. On the other hand, the remaining cotton-like pulp was sprayed with 0.12 g of the same Na ₂ H ₂ Y · 2H ₂ O and compressed to form a chelating agent composite layer. After placing this chelating agent complex layer on the water absorbing layer and compressing lightly,
Absorb 30 ml of artificial urine from the center, and after 15 minutes 40
The artificial urine that returned for 3 minutes at a pressure of g / cm ² was absorbed into a filter paper. Table 2 shows the amount of return.

_{Table 1 Water-absorbent resin artificial urine liquid absorption amount Chelating agent-treated} artificial urine liquid absorption amount g / g-resin g / g-resin 1 41 59 2 49 72 3 3 36 51

_{Table 2 Water-absorbent resin Chelating agent Return amount} g Comparative experimental example 1 1 0.63 2 2 0.32 3 3 0.42 Example 1 1 Na ₄ Y.4H ₂ O 0.25 2 2 〃 0. 12 3 3 〃 0.17 4 1 Na ₂ H ₂ Y · 2H ₂ O 0.19 5 2 〃 0.10 6 3 〃 0.14

[0034]

As described above in the section "Means for solving the problems", it is possible to obtain a disposable diaper in which urine does not leak from the diaper even with a small amount of water-absorbent resin.

Claims (1)

Claim: What is claimed is: 1. A laminated material comprising a liquid-permeable sheet, a liquid-impermeable leak-proof sheet, and a water-absorbing layer containing a water-absorbent resin located between the both sheets. In the disposable diaper thus obtained, a chelating agent is disposed between the liquid-permeable sheet and the water absorbing layer and / or in the water absorbing layer.