JPS60185805A - Disposable diaper - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to disposable diapers using cotton pulp and/or absorbent paper and polymeric absorbent material.

More specifically, the present invention relates to a disposable diaper in which the polymeric absorbent material is not used as an auxiliary material, but has an absorbent role equivalent to or greater than that of cotton pulp or absorbent paper.

Most disposable diapers currently on the market have a suction layer made of cotton pulp and paper, but recently some diapers have come out that use polymeric absorbent material as an adjunct to the cotton pulp. ing. However, there are almost no disposable diapers that consist of an absorbent layer made entirely of polymer absorbent material. The general role of this absorption layer is that it has a large absorption capacity so that urine does not leak from the diaper, it absorbs instantaneously, and the absorbed urine is retained in the absorption layer without returning to the surface. I can list many. When a polymer absorber is used as the main component of this absorption layer, the functions of the polymer absorber include absorption capacity, absorption rate, and gel shape retention during swelling, and all of these performances are It is necessary to be satisfied. However, although the polymeric absorbent materials currently used in disposable diapers have a nearly satisfactory absorption capacity, they are not satisfactory in terms of absorption speed and gel shape retention during swelling, resulting in large liquid absorption and poor urine return. It was not possible to make disposable diapers that were a little fuzzy.

In order to create a disposable diaper with excellent absorption capacity and absorption rate, and with a small amount of urine returning, we at Komeiko have conducted intensive studies on polymer absorbent materials, and have found that the absorption capacity and absorption rate of polymer absorbent materials are excellent. The present invention was accomplished by using a polymeric absorbent material that can be controlled within a certain range and maintain a swollen gel shape for at least 8 hours after absorbing urine.

In other words, in the present invention, the entire absorbent layer is composed mainly of a polymeric absorber in combination with cotton-like pulp, and the amount of physiological saline absorbed by the polymeric absorber (hereinafter simply referred to as liquid absorption amount) is 40%. ~9
0 &/11 Polymer, physiological saline absorption rate (hereinafter simply referred to as liquid absorption rate) F3ml/0.3-Ji' polymer or more, and at least 8% after absorbing urine
To provide a disposable diaper using a polymeric absorbent material having excellent shape retention properties and capable of retaining the shape of a time-swelling gel.

The advantage of using oil in the present invention is that since the polymer absorber is the main component of the absorbent layer, the polymer absorber is superior in terms of liquid absorption amount, - liquid absorption rate, and gel strength, especially in terms of absorption rate and swelling. It is excellent in retaining its shape when used.

In addition to the advantage of eliminating moisture, it is an important factor in making disposable diapers because it gives the surface of the diaper (the side in contact with the skin) a dry feel, and it also absorbs urine and swells. Sometimes, if the shape cannot be maintained for a long time, the polymer absorbent material will collapse due to the weight of the person and will come out on the surface of the diaper, causing discomfort on the skin. Body gel strength is also an important factor in making disposable diapers. Therefore, by using a polymeric absorbent having excellent liquid absorption amount, liquid absorption rate, and gel shape retention after swelling, it becomes possible to produce disposable diapers that do not cause discomfort.

Therefore, a more important point in the present invention is that the polymeric absorbent having the above-mentioned absorption performance is a water-insoluble crosslinked sodium polyacrylate based polymer having a crosslink density and odor distribution.

Usually, the following relationship exists between the absorption properties of a polymer absorber: liquid absorption amount, liquid absorption rate, and gel shape retention during swelling.

However, currently commercially available polymer absorbers have the above-mentioned absorption properties; liquid absorption 40 to 901/11-polymer, absorption rate 8M or higher 10,59-polymer, and the shape of a swollen gel after lying down (both 8 hours). 1.C is satisfied in all aspects of being maintained.

Polymer absorbers that satisfy all of these physical properties include those that have a difference in crosslinking density between the particle surface and the inside, and the surface portion has a large crosslinking density.

The skeleton of the i% molecular absorber that has this crosslinking density profile is starch/-acrylic acid (salt) graft co-fabric,
Examples include polyacrylic acid (salt), hydrolyzate of acrylic acid ester-vinyl acetate copolymer, and the like. Preferred is polyacrylic acid (salt). Alternatively, it will not impede the present invention to use other comonomers, such as methacrylic acid, (meth)acrylic acid ester, and (meth)acrylamide, as one synthetic component, as long as this polyacrylate does not completely reduce the absorption properties. . In the present invention, when referring to polyacrylate, in addition to polyacrylic acid in which 100% of the carboxylic acid is salt, 1 part is free salt.
Including those in which a portion forms a salt. As a method for imparting a crosslinking density profile to this polymer absorber, 1. A hydrophilic cross-linked polymer having hydroxyl groups and/or carboxyl groups (or carboxylate groups) is injected into a mixed solvent (mixed solvent) of water and a hydrophilic organic solvent. A method of dispersing the hydrophilic crosslinked polymer in a water/solvent ratio of 50 to 5150 to 95 and further contacting it with a crosslinking agent capable of reacting with the functional group of the hydrophilic crosslinked polymer to crosslink the entire surface. (The crosslinking reaction may be carried out by dispersing it in a mixed solvent.) 2. An aqueous solution of a hydrophilic monomer having a carboxyl group (or carboxylate group) containing a water-soluble initiator in the presence of a protective colloid. , after polymerization by dispersing/suspending in a non-aqueous solvent, the water content in the obtained hydrophilic polymer is 10~
After controlling the amount to 40 wt%, the surface of the hydrophilic polymer is further crosslinked by further contact reaction with a crosslinking agent that can react with the functional groups of the hydrophilic polymer. Considering the workability of the poultry house and the cross-linking reaction, method 2) is preferable. More preferably, the center diameter of the particles of the polymer absorber is 100 to 350 μm (
The following method can obtain a polymer absorber having z. That is, a sodium acrylate/aqueous solution containing a water-soluble initiator was dispersed and suspended in a total hydrocarbon or a halogenated aromatic hydrocarbon using heptalulose ester or cellulose ether, which is oil-soluble at the polymerization temperature, as a protective colloid. After polymerization, the water content of the obtained sodium polyacrylate is adjusted to 10 to 4071%, and then a crosslinking agent containing two or more functional groups capable of reacting with carboxyl groups is added. This method involves crosslinking. Examples of such crosslinking agents include ethylene glycol diglycidyl ether,
Polyglycidyl ethers such as polyethylene glycol diglycidyl ether and glycidyl triglycidyl ether, haloepoxy compounds such as epichlorohydrin and α-methylchlorohydrin, polyaldehydes such as glitaraldehyde and glyoxal, glycerin, pentaerythritol, ethylene glycol, etc. Polyamines such as polio/L' and ethylenediamine can be produced. Preferably (polyglycidyl ether such as ethylene glycol diglycidyl ether).The crosslinking density ratio of the polymer absorbing material obtained in this manner is 50-901//9-polymer with a liquid absorption rate of 8. me/
[1,3g-polymer or more, and the gel shape after IIH was small (both contained physical properties of being retained for 8 hours).By adjusting the synthesis conditions, for example, liquid absorption f/ , 100E/11-polymer or more have appeared, but since the above-mentioned relationship exists between the absorption properties, the liquid absorption rate is significantly reduced, which is not desirable.

Also, if the liquid absorption rate is less than 8 d/0.5.9-polymer, it is not desirable to use a large amount of polymer-absorbing material, as it will result in staleness. The eye physical properties of the material are liquid absorption of 50 to 9011/1.
1-Polymer, a liquid absorption rate of 8 ml, 10.5 mm or more, and a polymer in which the gel shape after swelling is maintained for at least 8 hours is most desirable. A polymeric absorbent material that satisfies all absorption properties can be inserted into the absorbent layer by sandwiching it between cotton-like pulp, which is another component of the absorbent layer, or by sandwiching it between sheets of paper. It may be either one. Furthermore, the layer containing the polymer absorber may be located at any position above, in the middle, or below the absorbent layer.

The embodiments of the disposable diaper of the present invention have been described above, but the embodiments are not limited to this description and can be modified as desired within the scope of the spirit thereof.

Examples will be described below.

The liquid absorption amount and liquid absorption rate of the polymer absorber mentioned here were measured as follows.

The liquid absorption 1ii'' is a physiological saline solution with a large excess of polymer (about 1if).
0.9% saline solution), swelled sufficiently, and then
The calculated weight of the swollen polymer obtained by filtration through a wire mesh with 0 mesh (w) ((measured)
& (wo).

The amount of liquid absorbed by the toothpick (9/I/) = W/Wo.

The liquid absorption rate was measured using the apparatus t' shown in Figure 1. Polymers a and sl12 were sprayed onto a 70φ glass filter plate 1 with the physiological saline liquid level set to an isohydric value, and then the physiological saline absorbed for 20 minutes was It is expressed by the value of saline solution.

The polymer absorbers Q to ■ used in the examples are the following commercial molecular absorbers ■ and ■. 230 n+l of cyclohexane was placed in a 500+ m fourth round bottom flask equipped with a stirrer, reflux condenser, dropping port, and nitrogen gas inlet tube. , ethyl cellulose N-2001,86'
Raise the temperature to 75℃ for all preparations. Separately, in an Erlenmeyer flask, dissolve 50.9 g of acrylic acid in 59 g of water and
Neutralize with 15.417% sodium chloride.9. The monomer concentration in the monomer aqueous solution was 45% (water content 55%). Next, 1 gk of potassium persulfate was added and dissolved. This monomer aqueous solution was placed in the fourth flask mentioned above under a nitrogen atmosphere.
．． After dropwise polymerization for 5 hours, the temperature was 0.0°C at 70° to 75°C.
The polymerization was completed by holding for 5 hours. This is followed by azeotropic dehydration (cyclohexane is refluxed) to reduce the water content in the polymer to 35% (■) and 20%.
(■) were respectively controlled. After that, 0.051 ethylene glycol diglycidyl ether was dissolved in 1M water and added to each solution at 75°C, and after keeping at this temperature for 2 hours, the cyclohexane was removed, and the polymer was heated at 80~100°C. Dry under reduced pressure, center particle size is 1
It is a water-absorbing polymer 1) from 00 to 35,011 m.

Polymer absorbent ■ Commercially available cross-linked polyacrylic soda (part name Aqua Keep 10SH) Example: Kinshu Pulp 259 is divided into upper and lower layers, and in between, seed polymer absorbent ■, ■, ■ 5g of the pulp was sprayed on each day and the flocculent pulp was compressed to form a suction layer. A disposable diaper was prepared by combining the top sheet and back sheet consisting of the absorbent layer □ (130 mm x 500 m) thus produced. 10 od of urine from a six month old boy was poured into this diaper, and the gel of the polymer absorber was observed with the naked eye over time, and the following results were obtained.

0nigel maintained the same shape as when swollen.

× Nigel's shape when swollen was (shifted and muddy p)

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus for measuring the physical properties of a polymer absorber used in the present invention. Applicant's agent Kaoru Furuya - Purification of drawings! F (no change in content) Figure 1 Ef-continued 〒] 3N4-:' (Spontaneous) 1972
April 13, 2013 rl 44 "Fraud Office Chief HK Kazuo Wakasugi 2, Name of invention Disposable diaper 3, Ndi + I # Relationship with matter M Patent 1911 people ((+91) flower) Soap 4'L charge Meeting 14, agent Akii 111 damage and drawing 0, content of shaft stop (11 Akira 4111 W engraving (Schiff changed the content) and correction (1) same page 10 line 12 "50-90" changed to "40"~90''
Correction (1) 5 lines from the bottom of page 11 “70φ” is changed to r70miφ
” and revised iE

Claims (1)

[Claims] 1. A disposable diaper comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent layer located between the sheets, the absorbent layer comprising a polymeric absorbent material, cotton-like pulp, and / or made of paper, this polymeric absorber has a physiological saline absorption rate of 40 to 9077/i polymer, a physiological saline absorption rate of 8 m110,51 polymer or more, and has a urinary absorption rate of 40 to 9077/i polymer, and A disposable diaper characterized by retaining the shape of a swollen IF gel for at most 8 hours. Claim 1, wherein the polymeric absorbent material is a water-insoluble crosslinked polyacrylate. disposable diapers. 3. The polymer absorbent material is a water-insoluble cross-linked polyacrylate-based material having a structure density obtained by the reverse phase suspension vehicle method. Disposable diapers as described in item 1. 4. The polymer absorber is made by dispersing and suspending an aqueous solution of alkali metal acrylic acid salt containing a water-soluble initiator in a hydrocarbon cable or a halogenated aromatic hydrocarbon, and polymerizing it as a protective colloid. All cellulose esters or cellulose ethers that are oil-soluble at this temperature are used, and the water content is adjusted to 10 to 40% by weight after 1 reaction, and 2 that can react with carboxyl groups (or carboxylate groups). The disposable diaper according to claim 1, characterized in that it is a crosslinked polyacrylic acid alkali total salt crosslinked with a crosslinking agent containing the above-mentioned functional groups.