JP3058496B2 - Absorbent structure and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorbent structure which can be suitably used for absorbent articles such as sanitary napkins, disposable diapers, wound dressings, bandages, incontinence pads and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, an absorbent structure used for an absorbent article is a structure in which pulp and a water-absorbing polymer powder or particles are mixed. However, it is known that the structure may be distorted and the function cannot be sufficiently exhibited.

In order to solve the above problem, a method of mixing a binder or a thermoplastic resin into a structure (Japanese Patent Laid-Open No. 3-6 / 1991)
3049), a method in which a water-absorbing polymer is sandwiched between papers and pressed under wet conditions to fix the water-absorbing polymer (Japanese Patent Laid-Open No. 3-1).
73562), or a method of forming a composite by converting a water-absorbing polymer into a fiber (Japanese Patent Application Laid-Open No. 3-45769).

[0004]

However, in the method using an adhesive component such as a binder, if the amount of the adhesive component is to be increased to obtain the form stability, on the contrary, the expansion of the water-absorbing polymer is hindered, and the absorption performance is reduced. Lower it. Further, in the method of pressing the water-absorbing polymer under wet conditions, it is difficult to control the wetness, and the fixation to the hydrophilic fiber is not always stable and reliable.

Further, in the method of fiberizing a water-absorbing polymer, the fiber-forming technology of the water-absorbing polymer is difficult and the handling of the fibers is not easy, and the water absorbing ability is smaller than the surface layer of the spherical polymer, so that the water absorbing speed is inferior. . Therefore, an object of the present invention is to easily fix the water-absorbing polymer in the structure without observing a decrease in the water-absorbing ability and the water-absorbing speed of the water-absorbing polymer, and to generate the deformation of the structure itself due to an external force received during use. Another object of the present invention is to provide an absorptive structure and a method for producing the same, which hardly cause a decrease in absorption performance due to, for example, a bias of the polymer.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an absorbent structure containing crimp-forming fibers that are crimped in a helical form, wherein a water-absorbing particulate material is contained inside the crimped spiral structure of the crimp-forming fibers. Is held , and the longitudinal or lateral direction of the absorbent structure is
The object is achieved by providing an absorbent structure characterized in that the recovery rate after 20% elongation is 80% or more .

[0007]

According to the absorbent structure according to the present invention, since the water-absorbing granular material is held by the crimp-generating fiber, there is no occurrence of twisting or offset during use, and there is no adhesive. Since there is no swelling inhibition or the like, there is little decrease in absorption performance. Further, the fixation of the water-absorbing granules can be easily performed only by expressing the crimp-expressing fiber, and the water absorbing speed can be increased by using a spherical water-absorbing granule.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to an absorbent structure (web or the like) containing crimp-expressing fibers that are spirally crimped. Things are being held. Crimp development of the fibers constituting the absorbent structure of the present invention has a crimp development property, Ru der properties 20% post elongation recovery rate of 80% or more of the structure after the crimp development. 8
If it is less than 0%, the elastic recovery rate of the structure is insufficient, the structure cannot follow the external force applied to the absorbent structure, and the holding power of the water-absorbing particulate matter (such as a water-absorbing polymer) is also insufficient.

The absorbent structure of the present invention preferably contains at least 50% or more of the fiber,
If it is less than 10, sufficient absorption cannot be obtained, and sufficient elasticity cannot be exhibited. In the absorbent structure of the present invention, the area shrinkage ratio of the structure after crimping is preferably 30% or more with respect to the structure before crimping (or in a card web state), and is less than 30%. In addition to the insufficient elasticity, the holding power of the water-absorbing granular material is low.

It is also preferable that the absorbent structure of the present invention contains a water-absorbing or hydrophilic material. By mixing a water-absorbing or hydrophilic material such as rayon soup or pulp, even if the crimp-expressing fiber is hydrophobic, it functions as a water-guiding material to the water-absorbing granules, and the water-absorbing granules can be effectively used. . Further, a water-absorbing resin may be kneaded into the crimp-expressing fiber itself.

The crimp developing fiber has a thickness of 6 d (denier) in order to retain the water-absorbing granular material before swelling.
The following is preferable, and in consideration of the processability, it is more preferably 1 to 3d or less. The fiber length is preferably from 20 to 76 mm. If the fibers are too thick or if the fiber length is too short, the water-absorbing particulates cannot be gripped, and the web shrinkage is low. On the other hand, if it is too thin, or if the fiber length is too long, the cardability deteriorates.

The fiber according to the present invention may be a polyolefin resin such as polypropylene or polyethylene, a polyester resin such as polyethylene terephthalate, a nylon resin or an eccentric core / sheath type or a sand-by-side type obtained by structurally combining these. Can be used. Examples of the water-absorbing granules include starch-based, cellulose-based, and synthetic polymer-based materials. For example, starch-acrylic acid (salt) graft copolymer, starch-
Saponified acrylonitrile copolymer, cross-linked sodium carboxymethyl cellulose, acrylic acid (salt) polymer, and the like are preferable. The shape may be any shape, such as a sphere or a scale, as long as crimp-expressing fibers can be gripped, and the particle size is preferably 50 to 400 μm.
More preferably, it is 150 to 250 μm.

A preferred method for producing the absorbent structure of the present invention is to form a card web (structure) by a known method containing at least 50% of the above-mentioned crimp-expressing fiber, and then to form a water-absorbing granular material. Spray. Thereafter, a heat treatment is performed at a temperature equal to or higher than the crimp development temperature so that the area shrinkage of the structure is set to 30% or more, whereby a fiber structure in which the water-absorbing particulate matter is incorporated can be formed. Further, the mesh of the web transport conveyor for spraying the water-absorbing particulates is coarse, and extra water-absorbing particulates are dropped and collected. Furthermore, when a large amount of water-absorbing particulates are sprayed on the structure to make the absorbent structure having a higher water-absorbing performance, the heat-treated crimps are weakly expressed, and after increasing the fiber density, the water-absorbing particulates are sprayed. Then, by heat-treating again and firmly crimping, more water-absorbing granules can be fixed. Further, after sufficiently expressing the crimp of the crimp-expressing fiber, the same absorbent structure can be obtained even if the absorbent structure is widened and stretched and the water-absorbing granules are dispersed. The rate is 1.1 to 3.0 times and the stretching rate is 1.0
It is desirable to be in the range of 2.0 to 2.0 times.

The absorbent structure according to the present invention configured as described above is used not only in the form of a sheet or other appropriate shape, but also as one constituent layer of another laminated absorbent structure. be able to. In addition, it can be suitably used for absorbent articles such as sanitary napkins, disposable diapers, wound care products, bandages, incontinence pads and the like.

[0015]

Next, the present invention will be described with reference to examples.
The present invention is not limited to these embodiments. Example 1 Daiwabo Co., Ltd. CPP fiber (thickness 2d, fiber length 20 mm, material: polypropylene) and PET fiber (thickness 2d, fiber length 51 mm) were mixed at 80:20, 50:50, and 30 pairs. Create a card web to be 70,
A water-absorbing polymer (average particle size: 100 μm, material: crosslinked polyacrylate) was sprayed, and heat treatment was performed at 130 ° C. for 5 to 90 seconds to prepare samples having different area shrinkage rates with respect to each mixing ratio.

Mixing ratio of CPP fiber and PET fiber: 80:20
The samples having shrinkage ratios of 80, 30, and 20% were samples 1, 2, and 3, respectively, and the mixture ratio was 50:50, and the shrinkage ratio was 8
Samples of 0, 30, and 20% were assigned to sample 4,
Samples having 5, 6 and a mixture ratio of 30:70 and a shrinkage ratio of 30 and 20% were designated as Samples 7 and 8, respectively. In addition, sample
3, 6, 7, and 8 are comparative examples . (Example 2) The fiber mixed with the CPP fiber was rayon 1.5d × 3.
A sample 9 was prepared using 2 mm (Daiwabo Co., Ltd.) under the same conditions as in Example 1.

(Example 3) A card web of 100% CPP fiber was prepared, and then a mixture of a water-absorbing polymer and pulp was sprayed and heat-treated at 130 ° C for 1 minute to prepare a sample, thereby obtaining sample 10. Table 1 shows the sample characteristics of each of the examples and the comparative examples.

[0018]

[Table 1] If the CPP fiber is less than 50% and the area shrinkage is less than 30%,
The recovery rate, falling off property, and repelling property were insufficient. Also, CP
When the mixing ratio of P was 30%, a shrinkage of 80% was not obtained.

(Example 4) The CPP fiber (thickness 2d,
A mixture of polymer and pulp was sprayed on a 100% card web having a fiber length of 20 mm, and a sample 10 was prepared by heat treatment at 130 ° C. for 90 seconds. (Comparative Example 1) A normal pulp and a polymer were laminated, wrapped with absorbent paper, and a structure was prepared as Comparative Product 1.

(Comparative Example 2) A card web was prepared from 100% of thermoplastic fiber NBF (H) (thickness: 2 d, fiber length: 51 mm) manufactured by Daiwabo Co., Ltd.
A comparative product 2 was prepared at 35 ° C. and a heat treatment of 90 seconds. (Comparative Example 3) A card web was prepared in the same manner as in Comparative Example 2, and heat treatment was performed at 135 ° C for 90 sec.

(Comparative Example 4) Spunlace N.D. W. Using "Sontara 8423", apply a hot melt adhesive on one side, then spray the polymer to W. Fix the polymer on the top to make comparative product 4. (Comparative Example 5) A pulp, a polymer, and a thermoplastic resin were mixed, heat-treated, and treated at a temperature 5 ° C higher than the melting point of the thermoplastic resin for 30 minutes to prepare Comparative Product 5.

Table 2 shows a performance comparison between the example sample and the comparative example sample.

[0023]

[Table 2] Note) The amount of polymer sprayed in this example is the same. Physical property measurement method * 1 Area shrinkage: When the web area S1 before shrinkage and the web area S2 after shrinkage, each area was measured by an image analyzer. Shrinkage = S2 / S1 * 100 * 2 Recovery after 20% elongation: In a Tensilon tensile tester, a test piece having a width of 50 mm is set at a chuck interval of 150 mm. When the elongate at a speed of 300 mm / min and the chuck interval becomes 180 mm, the absorbent structure length L at the point where the return stress becomes 0 at the same speed is read. Recovery rate = (1
80-L) / 30 * 100 Other evaluation criteria ：: High level of practicality レ ベ ル: Level that satisfies practicality temporarily △: Level with some uneasiness in practicality X: Level with problem in practicality

[0024]

The absorbent structure according to the present invention has a structure in which the water-absorbing polymer is easily fixed in the structure without deteriorating the water-absorbing ability and the water-absorbing speed of the absorbent polymer, and the absorbent is subjected to an external force received during use. It is also possible to prevent a decrease in absorption performance due to generation of skew or deviation of the polymer.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI D04H 1/40 1/50 (56) References JP-A-2-74254 (JP, A) JP-A-51-49979 (JP, A) JP-A-1-280058 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D04H 1/00-5/08

Claims (7)

(57) [Claims] 1. An absorbent structure comprising crimp-forming fibers that are spirally crimped , wherein a water-absorbing particulate material is held inside the crimped spiral structure of the crimp-forming fibers. sex
The recovery rate after 20% elongation in the vertical or horizontal direction of the structure is 8
Absorbent structure characterized by being 0% or more . 2. The absorbent structure according to claim 1, which contains the crimp developing fiber in an amount of 50 wt% or more. 3. The absorbent structure according to claim 1, wherein the crimp-exhibiting fiber can change its three-dimensional structure following the swelling of the water-absorbing granular material during liquid absorption. 4. The absorbent structure according to claim 1, further comprising a hydrophilic fiber. 5. A crimp-expressing fiber which is crimped helically.
In the absorbent structure, a crimped screw of the crimp-expressing fiber
A process for producing an absorbent structure absorbent granules inside handed structure is maintained, the step of spraying the upper Symbol absorbent granules to absorbent structures comprising the crimp fibers, the Crimp
Developing a crimp of the developable fiber.
In the step of expressing the crimp of the developing fiber, the crimping
30% area shrinkage before and after crimping of intact fiber
A method for producing an absorbent structure, characterized in that crimps are developed as described above, and the water-absorbent structure is held by the water-absorbent structure. 6. A crimp developing fiber which is crimped helically.
In the absorbent structure, a crimped screw of the crimp-expressing fiber
A method for producing an absorbent structure in which water-absorbing granules are held inside a spiral structure, wherein the absorbent structure made of the crimp-developing fiber is heat-treated at a temperature equal to or higher than a crimp-onset temperature to reduce crimping. After weakly developing, the method comprises a step of spraying the water-absorbent granules and a step of heat-treating the absorbent structure to strongly develop crimp, and the water-absorbent granules are formed inside the spiral structure of the fiber. A method for producing an absorbent structure, comprising: 7. A crimp-expressing fiber that is crimped helically.
In the absorbent structure, a crimped screw of the crimp-expressing fiber
A method for producing an absorbent structure in which water-absorbing granules are held inside a swirling structure, wherein the step of spreading the water-absorbing granules while widening and / or extending the absorbent structure, and the method of producing the fibers And a step of developing crimping of the absorbent structure, and causing the absorbent structure to grip the absorbent granules.