AU652726B2 - A net-shape non-woven cloth surface layer for an absorbent padding material - Google Patents

Description

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: V52726 Priority 9 Related Art: so Applicant(s): Kang Na Hsiung Enterprise Co., Ltd.

77-1 Minam Block Chiali Town, Tainan Hsien, TAIWAN O. C.) Address for Service is: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA S Complete Specification for the invention entitled: "A net-shape non-woven cloth surface layer for an absorbent padding SEGse material".

Our Ref 200188 POF Code: 126373/126381 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): 6006 The present invention relates to a surface layer for an absorbent padding material and in particular to a net-shape non-woven cloth surface layer for an absorbent padding material.

Various products using absorbent padding materials are available in the market place, for example, physiological sponges, which contain high molecular absorbents. The main difference between the physiological sponges of various manufacturers resides in the kind of contact surface layer used. Each kind of contact surface layer has its unique structure. For example, one type of surface layer is the Dry Mesh Film which is constructed by covering a high molecular absorbent padding material with a PE film having a mesh with ports of larger diameter on a top side thereof, and having ports of smaller diameter on a bottom side thereof to prevent the absorbed liquid from upward-infiltration. However, this structure also slows down the downward-infiltration speed. Since the liquid in the contact surface layer infiltrates down to the absorbent layer via a gradually narrowing passage with a larger port at its top side and a smaller port at its bottom side, this retards the liquid flowing speed and the time required to infiltrate a certain amount of liquid is thus lengthened. The contact surface layer cannot therefore quickly recover its initial dry state.

Furthermore, the machines used for manufacturing this type of physiological sponge must have additional equipment to overcome the special elasticity of the Dry Mesh Film. Another type of structure is constructed by placing a PE layer having meshes with anertures of uniform diameter over a layer of non-woven cloth in which the non-woven cloth is placed in between the PE layer and the absorbent material. The PE layer is provided by 2 layers of different types of mesh, i.e. a through type and a compression side-way.-broken type. This 2-layer type infiltration lamination has faster infiltration speed.

However, it is still far from ideal since each of the liquid passages formed by meshes are not short enough and 39 there is therefore only a slight improvement in the NF 2 infiltration speed. For sanitary sponges containing high molecular absorbent, no matter what type of structure is used, once the liquid is absorbed by the high molecules, they will become coagulated particles, except under comparatively larger compression. Otherwise the absorbed liquid will never come out. Therefore for almost all sanitary sponges containing high molecular absorbent, their absorption speed and the dryness of its contact surface layer are important features that are emphasized.

However none of them actually achieve the requirements of having a fast absorption speed and being dry to contact.

Another type of arrangement is to provide slots in the high molecular absorbent material for quickening the flow of the liquid. This however only marginally improves the absorption speed.

ing in iew the abv with accumulated years of manufacturing and lfes experience, the inventor has devised an absorbent adding material with a contact surface layer co osed of non-woven cloth and mesh plastic film. e present invention provides a net-shape non-woven loth surface layer for an absorbent padding materl 1 wherein the surface layer is an integral composi surface laminate made of a net-shape plastic film d a thin non-woven cloth layer. The present invention a provides an absorbent padding material having th /net-shape non-woven cloth surface layer described abo The present invent'in also provides a physiological product such as a sa ary sponge, a paper diaper or a paper diaper shor including the padding material described above.

The cont t surface layer may preferably have a thickness un 0.15 mm.

The llowing description refers in more detail to the va ous features of the present invention. To facil* ate an understanding of the invention, reference is ma in the description to the accompanying drawings where 'N f r nt invention i lusL-a d i t rfg-rrcr 3 According to one aspect of this invention there is provided a surface layer for an absorbent article having an absorbent pad including: a non-woven cloth; a plastic mesh adhered to the non-woven cloth to form a composite laminate, the mesh defining a plurality of mesh openings therethrough which provide a direct unobstructed path for liquid passing through the mesh, the non-woven cloth in use being adjacent the absorbent pad and the mesh spaced therefrom.

According to another aspect of this inventiop there is provided an absorbent article including: an absorbent pad; and a surface layer as described above extending over at :15 least part of said absorbent pad.

According to a further aspect of this invention there is provided an absorbent article as described above which is a physiological product such as a sanitary sponge, paper d!iaper, or paper diaper short.

The contact surface layer may preferably have a thickness under 0.15 mm.

The following description refers in more detail to the various features of the present invention. To •facilitate an understanding of the invention, reference is made in the description to the accompanying drawings where the present invention is illustrated in a preferred 3aembodiment. It is to be understood that the present invention is not limited to the preferred embodiment as illustrated in the drawings.

Figure 1 is an enlarged sectional view of a padding material having a surface layer of the known Dry Mesh Film structure; Figure 2 is an enlarged sectional view of a padding material having a surface layer of the known 2-layer laminate structure; Figure 3 is an enlarged sectional view of a padding material having a surface layer of the present invention; Figure 4 is a schematic view of an apparatus for manufacturing the surface layer of the present invention; Figure 5 is a top view of the upper surface of the surface layer of the present invention; and Figure 6 is a cross-sectional view along line A-A of Figure 5.

Referring to Figure i, there is shown an enlarged sectional view of the Dry Mesh Film structure. From this drawing it can be seen that the liquid passage has a larger port 11 at the top side and a smaller port 12 at the bottom side, and the liquid passage length between these ports is at least 0.3 mm. The gradual decreasing in the liquid passage diameter plus the comparatively larger length of the liquid passage impedes the flowing speed of the liquid. Therefore, this structure has a slow infiltration sneed as shown in Table i.

Referring to Figure 2, there is shown an enlarged sectional view of a laminate contact surface of 2-layer structure of a PE layer and a non-woven cloth layer, in which, the PE layer 21 is prcvided with plurality of compression sidewise broken slits, so that the liquid can infiltrate out from these slits. A non-woven cloth layer 22 is provided on the bottom side of the PE layer 21 to prevent the liquid from infiltrating back. Since the.

liquid passages on the PP layer are formed by compression force, the total liquid passage length should be much greater than the sum of the thickness of the PE layer and 39 the non-woven cloth, and may sometimes even exceed 0.3mm.

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CS S re usVF i, :d t' 4 Although the liquid passages of this structure do not have the port diameter gradual decreasing effect and has a faster infiltration speed than the Dry Mesh Film structure, nevertheless, it is not an ideal arrangement and needs to be improved.

Referring to Figure 3, there is shown an enlarged sectional view of a padding material having the surface layer of the present invention. Placed on the high molecular padding material 50 is an integral composite contact surface laminate made of a mesh punched plastic f.lm 31 and a non-woven cloth layer 32, the thickness of i: the plastic film 31 being only 0.1 mm. This laminate can be manufactured by spreading the molten plastic on the surface of a non-woven cloth, then letting it pass through a compression and punch roller for spreading plastic film in the required and a uniform thickness on the non-woven cloth as well as punching meshes of uniform diameter on the plastic film. Because of this additional thickness of the plastic film, the strength of the non-woven cloth is thus increased. A contact surface laminate manufactured by this process has a very fast liquid infiltration speed, as well as the reverse infiltration isolation property of the non-woven cloth layer. The contact surface can therefore be maintained constantly in a dry state. Table 1 as follows shows the results from tests conducted by the inventor for comparison, in which A represents the, present invention, an absorbent padding material with a net-shape non-woven cloth surface layer of the present invention, B represents a 2-layer type infiltration laminate, C represents a Dry Mesh Film.

Table 1 Type Item A B C Absorption speed 3.06 7.45 12.26 (Sec) Dryness 0.02 1.27 0.03 From table 1 it can be seen that padding material having the surface layer of the present invention has a VF- faster absorption speed than the 2-layer type infiltration laminate, and the Dry Mesh Film. Furthermore, the thickness of the surface layer of the present invention is very thin, and because its liquid passage are provided through bores with uniform inner diameter, extending laterally therethrough, this structure allows fast liquid infiltration into the padding material. In a comparison of dryness the present invention is also the best one, the Dry Mesh Film being the next, with the 2-layer type infiltration laminate being the third best. Therefore, it can be concluded that no matter what padding absorbent material is used, high molecular type or ordinary type, the present invention always has the fastest infiltration speed and the best dryness, and no matter that it is used as the contact surface of sanitary sponges or paper diaper shorts.

Furthermore, during the mesh punching process the plastic film of the present invention can be punched with a variety of meshes to fit the requirements of the padding absorbent materials.

An alternative method and apparatus for manufacturing the surface layer of the present invention is shown in Figure 4. A continuous non-woven cloth layer 32 may pass through the gap between a rotatable screen roller 5 and a smooth roller 6. The cylindrical outer wall of the screen roller 5 is formed with pores (tiny openings) of varying configuration, such as a diamond shape. In the inner space of the screen roller 5, there is provided a squeegee 7 having a downward extruding outlet facing the upper surface of the non-woven cloth layer 32. A pipe connection formed on a side end of the squeegee 7 may be connected to a pump (not shown) via any available pipe, so that molten plastic may be piped into the squeegee 7 by the pump.

In operation, molten plastic is pumped into the squeegee 7 by the pump, and then the molten plastic will be extruded to the extruding outlet by the operation of the squeegee 7. During the extrusion, the molten plastic ,F 6 I A r will be extruded out of the pores formed on the screen roller 5, and therefore the molten plastic will be printed onto the upper surface of the non-woven cloth layer 32 to form an apertured plastic film layer 31 thereon. After this process of compounding the film layer 31 will be dried up by passing through a dryer 8.

Since the plastic film layer 31 is compounded (not pressed or pierced) on the non-woven cloth layer 42 and there is a suitable narrow gap between the screen roller and the smooth roller 6, the bottom surface of the compounded non-woven cloth layer 42 is substantially smooth. On the contrary, the conventional products available in the market have a rough bottom surface with protuberant portions or penetrations.

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Claims (8)

1. A surface layer for an absorbent article having an absorbent pad including: a non-woven cloth; a plastic mesh adhered to the non-woven cloth to form a composite laminate, the mesh defining a plurality of mesh openings therethrough which provide a substantially direct and unobstructed path for liquid passing through the mesh, the non-woven cloth in use being adjacent the absorbent pad and the mesh spaced therefrom.

2. A surface layer according to claim 1 wherein the cross-sectional dimensions of the mesh openings are greater than the thickness of the mesh.

3. A surface layer according to claim 1 or claim :15 2 wherein the mesh openings have substantially constant cross-sectional dimensions along the length thereof.

4. A surface layer according to any one of the preceding claims wherein the mesh openings are punched in the plastic.

5. An absorbent article including: an absorbent pad; and a surface layer according to any one of claims 1 to 4 extending over at least part of said absorbent pad.

6. An absorbent article according to claim :*25 which is a physiological product such as a sanitary sponge, paper diaper, or paper diaper short.

7. A surface layer substantially as hereinbefore described and illustrated with reference to Figures 3 to of the drawings.

8. An absorbent article substantially as hereinbefore described and illustrated with reference to Figures 3 to 5 of the drawings. DATED: 11 July 1994 PHILLIPS ORMONDE FITZPATRICK Attorneys for: KANG NA HSIUNG ENTERPRISE CO., LTD. A7 g 0 4 5537b 8