JPH06166111A - Surface material of absorbent article and manufacture of the same - Google Patents

Abstract

PURPOSE:To try to prevent longitudinal tearing, to reduce elongation and to maintain liquid permeability and other properties for preventing liquid return, fitting, and shielding of a surface material of an absorbent article by forming the material with a resin composition in which a specified amount of polypropylene is blended to 100 pts.wt. of low density polyethylene or linear low density polyethylene. CONSTITUTION:A surface material comprises a liquid-inpermeable material covering the surface of an absorbent 3 of an absorbent article 1 and has a number of pore parts 4 in which an opening for liquid permeation is formed. The surface material comprises a resin composition in which 1-50 pts.wt. of polypropylene is blended to 100 pts.wt. of low density polyethylene or linear low density polyethylene. When the amount of polypropylene is less than 1 pts.wt., the improvement in tear strength and tensile strength is inadequate, and when the amount exceeds 50 pts.wt., the touch of the surface material is deteriorated in spite of the improvement in strength. This is the reason for the restriction of the composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface material for absorbent articles such as sanitary napkins and diapers and a method for producing the same.

[0002]

2. Description of the Related Art Generally, absorbent articles such as sanitary napkins and diapers include an absorbent body that absorbs liquid such as blood and urine, a surface material that covers the surface of the absorbent body, and a surface material that is applied to the skin. And a back surface material that covers the back surface of the above and prevents liquid leakage. The surface material of the absorbent article is required to have liquid permeability so that liquid such as blood and urine can be rapidly transferred to the absorbent body and absorbed by the absorbent body, and once A liquid return prevention property that does not return the absorbed liquid to the skin side, a dry property that essentially does not leave the liquid on the skin, and a shielding property that shields the color of blood or the like diffused in the absorber are required.

Conventionally, in order to meet the above demands, for example,
A surface material that uses a non-woven fabric, which is a hydrophobic fine fiber aggregate, and forms a space between the skin and the absorbent body in a hydrophobic atmosphere to reduce liquid return from the absorbent body without impairing liquid permeability. (See Japanese Patent Application Laid-Open No. 58-180602), or a surface material in which pores are provided in a hydrophobic liquid-impermeable sheet to reduce liquid return from the absorber (Japanese Utility Model Laid-Open No. 54-124398, Japanese Patent Publication No. JP-A-57-17081, JP-A-57-13
No. 40, Japanese Unexamined Patent Publication No. 61-45753) and the like have been proposed.

Among the above-mentioned surface materials, the latter surface material is further improved, and a surface provided with micro-embossing so that the base surface which is a non-opening portion does not come into contact with the skin and causes discomfort. Wood is also proposed. And, since the former surface material described above is a structure of a fine fiber aggregate, when it comes into contact with the body, the area of the contacting surface is extremely small, so that a comfortable texture can be provided, and Even when a shearing force is applied between the surface material and the surface material, the fiber feeling constituting the surface material causes free relaxation,
The ability to relieve stress can provide a very comfortable texture.

[0005]

However, the above-mentioned surface material of the former, when the liquid is excreted to the surface material during the use of the absorbent article using the surface material, the minute amount in the fiber assembly. Liquid easily accumulates in the space, and when pressure is applied, the accumulated liquid moves to the surface side (skin side) and gives a tactile discomfort such as stickiness, and also visually discomfort such as blood stains. There was a drawback to give.

Further, the latter surface material mentioned above uses a hydrophobic film and is provided with an opening for the free movement of the liquid. On the contrary, when it comes into contact with the body, since it is a continuous body of hydrophobic film, the area in contact with the body is extremely large, which inhibits physiological functions of the skin, such as heat dissipation and moisture release, and causes discomfort. There is a drawback that it causes disorders such as swelling and itching. Further, even when a shearing force is applied between the body and the surface material, the contact area is large, so that the resistance becomes remarkably large, which gives an uncomfortable feeling.

Further, a surface material has been proposed in which the above-mentioned defects are prevented by imparting micro unevenness to these hydrophobic perforated films, but the surface material is effective in a dry state before excretion of liquid. However, in the wet state after excretion,
It has not been able to prevent the essential physiological disorders of the skin. Further, the latter surface material, when the liquid such as blood is excreted, since the continuous layer of the hydrophobic film is present, the liquid is not retained in the surface layer, and titanium oxide having a further shielding effect is used. When blended with, etc., it also has a menstrual blood shielding effect, and has a great effect of providing a visual sense of cleanliness after use. However, during the use of the latter surface material, when the surface material adheres to the body, there is often a phenomenon that excreted liquid exists between the continuous layer of the hydrophobic film and the hydrophilic skin. , Has not come to give a substantially comfortable dry condition.

Furthermore, even if any of the above-mentioned conventional surface materials is made of a flexible material, due to its shape, the shear yield stress in the direction along the surface of the surface material is large, and there is a feeling of discomfort during mounting. It was In order to improve these drawbacks, the present inventors have previously proposed Japanese Patent Application No. 3-260791 and Japanese Patent Application No. 3260791.
-343333, Japanese Patent Application No. 4-16886, Japanese Patent Application No. 4
According to Japanese Patent Application No. 123923 and Japanese Patent Application No. 4-283274, liquid permeability that allows liquid to freely move, liquid return prevention property that prevents liquid once absorbed from returning to the skin side, and comfort that does not cause discomfort when worn. A surface material having wearability and a shielding property for hiding the color of absorbed liquid and a method for manufacturing the same have been proposed.

However, since the surface material proposed above has a flexible shape / physical property, vertical splitting is likely to occur in the production line when it is applied to the surface material of the absorbent article, and the carrier tension against the conveying tension at the time of high-speed production is high. It has a large elongation in the manufacturing line (MD) direction and has an element that makes it difficult to improve the productivity of the absorbent article.

Therefore, an object of the present invention is to provide the above liquid permeability,
Has the above liquid return prevention property, the above-mentioned wearability and the above-mentioned shielding property,
Further, it is an object of the present invention to provide a surface material for absorbent articles and a method for producing the same, which can eliminate the above-mentioned longitudinal tearing property and can reduce the above elongation with respect to the conveying tension.

[0011]

As a result of various studies, the present inventors have found that the above object can be achieved by using a resin composition having a specific composition as a surface material forming material. The present invention has been made based on the above findings, and provides the following surface material for absorbent articles.
A surface material that covers the surface of the absorbent body of an absorbent article having an absorbent body, is made of a liquid impermeable material, has a large number of holes, and has holes for liquid transmission formed in the holes. In the surface material, the surface material is (a) 100 parts by weight of low-density polyethylene and / or linear low-density polyethylene,
(B) A surface material for an absorbent article, which is formed of a resin composition containing 1 to 50 parts by weight of polypropylene.

As a preferred method for producing the above surface material, the present invention supplies the surface material forming resin to one surface portion of a surface material forming mold having a large number of fine spaces to form the above surface material forming mold. Vacuum suction is performed from the other surface portion of the above to mold the surface material forming resin into a sheet having a shape along the surface shape of the surface material molding die and having a hole portion at a position corresponding to the space. The present invention provides a method for manufacturing a surface material of an absorbent article, characterized by:

[0013]

According to the surface material of the present invention, when an absorbent article is manufactured, the surface material is stretched in the lateral direction in order to eliminate the slack of the surface material in the manufacturing line of the absorbent article, and by the lateral tension in bending. There is no vertical tear, and the elongation to the conveying tension in the manufacturing line direction (MD direction) is small. Therefore, it is excellent in high-speed productivity, and the vertical tear resistance prevents shear fracture caused by the movement when the absorbent article is worn. It

[Material for Forming Surface Material (Resin Composition)] The low density polyethylene (LD-) which constitutes the resin composition which is a material for forming a surface material of the present invention, which is made of a liquid impermeable material.
PE) is a polymer having a density of 0.905 to 0.935 and an MFR of 1 to 50, which is obtained by polymerizing ethylene at high pressure / high temperature, and includes a small amount of a copolymer with vinyl-based monomers such as vinyl acetate and vinyl acrylate. .

The linear low density polyethylene (L-LD-PE) constituting the above resin composition is a density of 0.890 to 0.94 obtained by copolymerization of ethylene and α-olefin.
0, a linear polymer of MFR 1 to 50, L of 50% or less
Also included is a blend system commonly referred to as L-LD-PE that includes D-PE. The polypropylene (PP) constituting the resin composition is a polymer of propylene and has a hardness (R) of 9
0-115, MFR. 2 to 50 homopolymers, which also include copolymers with minor amounts of ethylene and other α-olefins.

The above resin composition has a composition in which 1 to 50 parts by weight of polypropylene (PP) is mixed with 100 parts by weight of LD-PE and / or L-LD-PE. P
When the amount of P is limited to the above range, the longitudinal tear strength and the tensile strength in the MD direction are not significantly improved when the amount is less than 1 part by weight, and the vertical tear strength and the tensile strength are further improved when the amount exceeds 50 parts by weight. However, this is because the feel of the surface material of the present invention (the wearability) is reduced. A more preferable blending amount of PP is 2 to 20 parts by weight. From the viewpoint of the feel of the surface material, a homopolymer rather than a homopolymer (for example, 1 to 15%
Is preferably a copolymer of α-olefins such as ethylene), and the MFR of PP is LD-PE and / or L-LD from the viewpoint of melt vacuum perforation when manufacturing a surface material.
It is preferably higher than the MFR of PE.

The ratio of LD-PE and L-LD-PE is not particularly limited, but L-LD-P is preferred in view of flexibility and longitudinal tear strength.
A larger amount of E is more preferable, and a larger amount of LD-PE is preferable in terms of extrusion moldability of the molten resin and vacuum suction perforation property. LD-PE / L-LD-PE is 10-70 from the balance of both.
/ 90/30 is preferable and 20-50 / 80-50 is more preferable.

(Formulation compounded in the resin composition) The surface material (liquid impermeable material) is preferably opaque from the viewpoint of shielding properties. As the means, for example, a means of adding a white pigment such as titanium oxide, zinc oxide, etc., a filler such as calcium carbonate, talc, clay, calcium sulfate, barium sulfate, etc., alone or in combination, to the above resin composition is generally used. Is.

Further, it is preferable that the surface material has micro unevenness on its surface in order to give a dry feeling upon contact with the skin. The unevenness can be imparted to the surface of the surface material by changing the molding conditions of the surface material or by subjecting the surface material to a post-treatment, but in the resin composition, for example, the above-mentioned inorganic filler is relatively coarse (2 to 20 μm). ) Addition of particles or addition of high melting or non-flowing organic particles. Furthermore, in order to impart releasability, hydrophilicity and antistatic property to the surface material, known additives may be added to the surface of the resin composition, and a coloring agent for coloring may be added to the resin composition. it can.

Example An example of the surface material of the absorbent article of the present invention will be described with reference to the drawings. FIG. 1 is a partially cutaway perspective view of an absorbent article provided with a surface material of an embodiment manufactured using a spiral braided wire mesh, and FIG. 2A is a partially enlarged plan view of the surface material of the embodiment. 2B is a partially enlarged perspective view of the surface material shown in FIG. 2A viewed from the front side, and FIG. 2C is a partially enlarged vertical cross-sectional view showing one hole portion of the surface material shown in FIG. 2A. FIG. 3A is an enlarged plan view showing a part of a spiral knitted wire netting (surface material molding die) used in the method for manufacturing a surface material of the present invention, and FIG. 3B is a partially enlarged perspective view thereof.

The surface material 2 of this embodiment is made of a liquid impermeable material that covers the surface of the absorbent body 3 of the absorbent article 1 having the absorbent body 3, has a large number of holes 4, and has a plurality of holes 4. A surface material in which openings 4 for liquid permeation are formed in each of the parts 4 (see FIGS. 1 and 2), and specifically, a molten resin made of the above-mentioned resin composition is right-handed or left-handed. Of the same direction spiral braided wire mesh 11 (see FIGS. 3A and 3B) and the wire rod 11 of the spiral braided wire mesh 11 described above.
It is formed into a sheet having a hole 4 at a position corresponding to the space between a. In addition, 2'in FIG. 1 is a back surface material.

More specifically, as shown in FIGS. 2A to 2C, the surface material 2 of this embodiment has a large number of tops 5 each having a convex curved surface having voids on the back side and a large number of open bottoms 6. And a cylindrical wall portion 7 that connects the top portion 5 and the hole bottom portion 6 respectively, and each of the hole portions 4 has a plurality of adjacent top portions 5 and one hole bottom portion 6. And one cylindrical wall portion 7 connecting them,
It has a communicating hole structure in which the hole bottom 6 constitutes the hole for liquid permeation.

[Shape / Physical Properties of Surface Material] FIG. 4 is an explanatory view showing an example of measurement of the physical properties of the surface material of the absorbent article of the present invention and an outline of the measurement results. FIG. 4B to 4E are plan views showing the outer periphery of the contact surface between the flat plate and the top of the surface material pressed against the flat plate, and FIG. FIG. 4C shows the outer circumference of the contact surface under load, FIG. 4C shows a low load, FIG. 4D shows a medium load, and FIG.

The surface material 2 of this example (the top 5 of this surface material 2
Is a rounded non-round convex shape) as shown in Figure 4A.
As you can see, pressing the flat plate Y from above will respond to the load.
Then, as shown in FIGS. 4C to 4E, the flat plate Y and the nip portion 5 are
The outer circumference Z of the contact surface of the
Is a shape having a contact surface close to a point or a line as shown in FIG. 4B.
Has physical properties. And the surface material of the present invention is
0.5 g / cm in the measuring method of physical properties as described above ²Load of
At this time, the outer circumference of the contact surface at the top of one that comes into contact with the flat plate is 0.1 mm ~
5mm, 50g / cm²0.3 mm to 15 mm when loaded
Those are preferable.

Further, in this embodiment, each of the hole portions 4 has four holes.
It is formed by being surrounded by the above-mentioned tops 5, and the distance between the tops facing each other across the hole 4 is 0.05 mm to 8 mm.
It is preferable to set in the range of 0.2 mm to 5 mm
It is more preferable to set in the range of. The above holes are
The shape of any different vertical section including the axis passing through the approximate center of the hole in the thickness direction of the surface material is asymmetrical or deformed.
Is preferable, and 0.5 mm-5 mm is more preferable.

The density of the holes 4 (the number of holes per unit area of the surface material) is determined in consideration of the balance between the liquid permeability and the liquid return prevention property. Depending on the difference in the form of the communication hole structure of part 4, it is 2 / c
It is preferably m ² to 200 pieces / cm ² . When the opening area of the opening bottom 6 is small and the density of the holes 4 is low, the liquid permeability is substantially inferior, and as the opening area between the tops 5 is increased, the sheet forming property is deteriorated. 2 pieces / cm ² to 200 pieces / cm ² , especially 2 pieces / cm ²
preferably in cm ² to 100 pieces / cm ^2. Also,
The size of the hole 4 is such that the opening area between the tops 5 is 0.02.
It is preferable to set it to 10 mm ² .

The surface material of the present invention is not limited to the above-mentioned embodiment, and the skin contact surface has no unevenness and has a flat plate shape, a hole having a tapered shape, or a small thickness and a net shape. It may be one or the like.

[Method of Manufacturing Surface Material] Next, a method of manufacturing the surface material of the present invention will be described with reference to FIG. As shown in FIG. 5, the method for producing a surface material according to the present invention is such that, as shown in FIG. 5, a surface material is formed on one surface portion (surface) of a surface material molding die composed of a wire mesh 11 of spiral knitting having a shape shown in FIGS. A sheet-shaped molten resin 50 made of the resin composition is supplied as a forming resin from a T-die of a tank 51, and the vacuum suction device 5 is supplied from the other surface portion (rear surface) of the surface material molding die 11.
3 is used for vacuum suction (vacuum suction), and air is blown from the supply side of the sheet-shaped molten resin 50 by the air blowing device 52 to obtain the sheet-shaped molten resin 50.
Is molded into a sheet having a shape along the surface shape of the wire net 11 and having holes at positions corresponding to spaces between the wire rods 11a of the wire net, that is, the surface material 2 of the present invention.

The stress of the sheet is 60 g / c at 10% elongation.
It is necessary to be at least m, and if it is less than m, the elongation with respect to the conveying tension is large at the time of production and a stable sheet cannot be obtained.
The vertical tear strength of the sheet must be 800 g / cm or more,
If it is less than this, vertical tearing of the seat occurs during manufacturing or mounting.

When the above surface material is manufactured, the resin composition and manufacturing conditions such as the viscosity of the resin when melted, the direction of vacuum suction, the direction of the pressurized flow pressurized from the side opposite to the suction, and the like are appropriately selected. , The shape of the communication hole of the hole is “spiral” corresponding to the shape of the spiral braided wire net 11 described above.
It is also possible to mold into. Furthermore, if the peripheral portion of the liquid permeation opening bottom portion 6 is made more flexible by blowing heated air by the air blowing device 54, this portion acts as a valve and is guided to the absorber 2. It is also possible to improve the liquidity and the liquid return property.

[Production Example of Surface Material] This production example was carried out according to the embodiment shown in the process chart of FIG. As the spiral braided wire net 11, a 26-mesh wire net (SP-26-0.35 manufactured by Kansai Wire Net Co., Ltd.) having a wire diameter of 0.35 mm and formed of the same direction spiral is used. From a T-die having a width of 400 mm in which a resin composition having the composition described above is bonded to an extruder having a diameter of 40 mm, a basis weight of 30 is obtained.
A sheet-shaped molten resin of g / cm ² is supplied onto the spiral mesh wire net 11 while the spiral knit wire mesh 11 is supplied.
From the lower part (the side opposite to the molten resin supply side) of the vacuum nozzle 53
Then, a sheet (surface material of the present invention) having a shape corresponding to the surface shape of the spiral braided wire net 11 and having the same number of holes as the number of meshes of the wire net was formed. For each of the obtained sheets, the following (evaluation method) gives 10%
The stress during stretching and the longitudinal tear strength were measured, and the results are shown in Table 2 below.

(Resin used) PE-1; L-2 / LL-1 = 40/60 (weight ratio) PE-2; L-1 LL-2 = 20/80 (weight ratio) L-1; LD- PE, density 0.925, MFR15 L-2; LD-PE, density 0.920, MFR11 LL-1; L-LD-PE: density 0.915, MFR1.
0 LL-2; L-LD-PE: Density 0.920, MFR1
4 Based on the above density; ASTM D1505 (g / cm ² ). The above MFR; ASTM D1238 (g / 10min)
by. PP-1; Hardness (R) 97, MFR8 PP-2; Hardness (R) 97, MFR30 PP-3; Hardness (R) 107, MFR8 PP-4; Hardness (R) 110, MFR23 The above hardness; ASTM D- According to 785 (Rock El R). The above MFR; ASTM D1238 (g / 10min)
by. TiO ₂ ; L-LD-PE to be blended with each other is used by making a 30% masterbatch with a twin-screw kneading extruder.

(Evaluation method) 10% M; In order to evaluate the elongation of the sheet against the conveying tension in the production line, the stress at 10% elongation in the MD direction (flow direction) of the sheet was measured (g / cm; basis weight 30 g). / M ² of stress per 1 cm sheet). Longitudinal tear strength: In order to evaluate the tensile strength in the lateral direction in the production line and the tensile strength in the lateral direction during bending, the tensile breaking strength in the direction perpendicular to the MD direction of the sheet (lateral direction) is measured (g / cm; tsubo). (Stress per 1 cm of sheet having an amount of 30 g / m ² ).

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

EFFECT OF THE INVENTION The surface material of the absorbent article of the present invention is, first of all, free from longitudinal tearing due to lateral pulling, has a small elongation with respect to the conveying tension of the production line, and has a liquid permeability which allows free movement. Secondly, there is a possibility that the once absorbed liquid will not return to the skin side, a liquid return prevention property, a wearability that does not make the user feel uncomfortable when wearing, and that the color of the absorbed liquid does not match the surface. It has a shielding property. Further, according to the method for manufacturing a surface material for absorbent articles of the present invention, a surface material having the above effects can be efficiently manufactured.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of an absorbent article including a surface material according to an embodiment of the present invention.

2A is a partially enlarged perspective view of the surface material of the above embodiment, FIG. 2B is a partially enlarged perspective view of the surface material shown in FIG. 2A viewed from the surface side, and FIG. 2C is an example of the surface material shown in FIG. 2A. It is a partial expansion perspective view which shows a hole part.

FIG. 3A is an enlarged plan view showing a part of a spiral woven wire net (mold for surface material molding) used in the method for manufacturing a surface material of the present invention, and FIG. 3B is a partially enlarged perspective view thereof.

FIG. 4 is an explanatory view showing one measurement side of the physical properties of the surface material of the absorbent article of the present invention and an outline of the measurement results, and FIG.
FIG. 6B to FIG. 6E are plane views showing the outer periphery of the contact surface between the flat plate and the top of the surface material pressed against the flat plate, respectively. FIG. 4B is a diagram when no load, FIG. 4C is a diagram when low load,
FIG. 4D shows the outer circumference of the contact surface under medium load, and FIG. 4E shows the outer circumference of the contact surface under high load.

FIG. 5 is a process explanatory view showing an embodiment of the method for manufacturing a surface material of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Absorbent article 2 Surface material 4 Hole part 3 Absorber 5 Top part 6 Opening bottom part 7 Cylindrical wall part 11 Wire material 11a Wire material 50 Surface material forming resin (sheet-like molten resin) Y Flat plate Z Contact surface of top part of surface material Perimeter

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location B01J 20/28 A 7202-4G B32B 5/18 27/00 K 7258-4F 27/32 C08J 5 / 12 CES 9267-4F // C08L 23/08 LCD 7107-4J B29K 23:00 105: 04 7603-4C A61F 13/18 310 Z

Claims (5)

[Claims] 1. A surface material for covering the surface of the absorbent body of an absorbent article having an absorbent body, which is made of a liquid impermeable material, has a large number of holes, and has openings for liquid permeation in the holes. In the surface material in which the pores are formed, the surface material comprises (a) 100 parts by weight of low-density polyethylene and / or linear low-density polyethylene, and (b) 1-50 parts by weight of polypropylene. A surface material for an absorbent article, which is formed of a resin composition. 2. The surface material comprises: a plurality of tops each having a convex curved surface having a void on the back side; a plurality of bottoms of apertures; and a cylindrical wall portion connecting the tops and the bottoms of the apertures, respectively. Each of the hole portions is formed from a plurality of adjacent top portions, one opening bottom portion, and one cylindrical wall portion connecting them, and the opening bottom portion is used for liquid permeation. The surface material of the absorbent article according to claim 1, wherein the surface material has a communication hole structure that constitutes the opening portion. 3. The respective hole portions are characterized in that different arbitrary vertical cross-sectional shapes including an axis passing through substantially the center of the hole portion in the thickness direction of the surface material are left-right asymmetrical shapes or irregular shapes. The surface material of the absorbent article according to claim 1. 4. A method of manufacturing a surface material for an absorbent article according to claim 1, wherein the surface material is provided on one surface portion of a surface material molding die having a large number of fine spaces. The resin for forming is supplied, vacuum suction is performed from the other surface portion of the die for molding surface material, and the resin for forming surface material has a shape along the surface shape of the die for surface material molding and A method for manufacturing a surface material of an absorbent article, comprising forming a sheet having holes at positions corresponding to spaces. 5. The method for manufacturing an absorbent article according to claim 4, wherein the surface material molding die comprises a wire mesh of spiral knitting.