WO1994028751A1

WO1994028751A1 - Hook and loop connection

Info

Publication number: WO1994028751A1
Application number: PCT/SE1994/000546
Authority: WO
Inventors: Björn Larsson; Hannele Nurmi; Per Berntsson
Original assignee: Mölnlycke AB
Priority date: 1993-06-14
Filing date: 1994-06-07
Publication date: 1994-12-22
Also published as: GB2279106A; SE501513C2; SE9302041D0; GB9411731D0; AU7011994A; ZA943997B; TNSN94067A1; SE9302041L

Abstract

The invention relates to a hook and loop connection. It is characterized in that the hook layer consists of plastics or the like having attachment protrusions in the shape of a neck (2) with an outwardly widening cone shaped hat (3) and an attachment surface of non-woven material.

Description

TITLE:

Hook and loop connection.

TECHNICAL FIELD:

The present invention relates to a hook and loop connection which can be used generally but which is especially intended for different kinds of absorbent products such as nappies and sanitary towels, but which can also be used for surgery coats, surgery sheets and other medical applications.

PRIOR ART:

Hook and loop connections are commonly known. They consist traditionally of a hook-containing part and a loop- containing part. Both are produced by different weaving or knitting processes, which are complicated and expensive. They have therefore only been used to a very small extent in disposable products. The hooks which usually have the shape of hitches or mushrooms must be adapted to the loops to give an effective connection.

To improve the hook and loop connections and make them cheaper extruded films having different types of hooks have been developed and been used commercially. The use of non- woven materials instead of the loop-containing material has also been tried since non-woven material can be manufactured very efficiently and cheaply. Attempts have also been made to mechanically modify the non-woven material to obtain the desired effect, however with no success. TECHNICAL PROBLEM:

Since a hook and loop connection consists of two parts these must be adapted to each other. Non-woven materials are usually thin plain materials consisting of a dense fibre net. Traditional hook and loop materials as well as extruded films with hooks have a shape or size which does not allow any effective penetration in a non-woven material according to the above. Attempts have been made to modify non-woven material mechanically or to produce non-woven material having a more open structure, so called stitch- bonded, water jet bound or air jet bound non-woven to make the hooks penetrate the non-woven material better. These materials however lack sufficient inner strength to give an effective connection.

THE SOLUTION:

It has therefore long been a desire to have the possibility of using a hook layer also with other materials with an attachment surface that has smaller pores or openings and therefore, according to the present invention a hook and loop connection has been achieved comprising a layer with projecting attachment threads or protrusions on one surface and a surface which allows adherence through anchoring of the projecting threads or protrusions, which is characterized in that the layer consists of plastics or the like with the attachment protrusions in the shape of a neck having an outwardly widening cone-shaped hat, the anchoring surface being of non-woven material.

According to the invention it is suitable that the conical side of the cone shaped hat has a slope relative to the base surface of approximately 0-90°, preferably 25-50°. According to the invention it is further suitable that the total height of the protrusion with respect to the base of the neck is 0,8-1,7 and that the neck narrows outwardly.

According to the invention the non-woven material can suitably consist of a thermo-bonded filamentary fibre sheet (spun-bonded fabric) , a carded spun-bonded fabric or an elastic non-woven material having an inner tensile strength (MD) of 15-40 N/50 mm, preferably 20-30 N/50 mm and an inner tensile strength (CD) of 5-25 N/50 mm, preferably 10- 20 N/50 mm both having a surface weight of 23 g/m². For other surface weights the inner strength is proportionally calculated with respect to 23 g/m².

The average equivalent diameter of the circle (ECB) in the pores of the non-woven material should suitably be 0,10- 2,0 mm.

DESCRIPTION OF FIGURES:

The invention will in the following be described in more detail in connection with the attached drawings where

Fig. 1 in section shows a protrusion according to the invention and where

Fig. 2 shows the pore formation and pore measurement in the non-woven material.

DETAILED DESCRIPTION:

Fig. 1 shows, in section, a typical protrusion on a hook layer according to the invention. This protrusion is made of plastics as is also the support 1 from which the protrusion extends outwardly. The layer 1 together with the protrusions can be moulded according to known methods. The material in the protrusion and the layer 1 suitably consists of thermoplastics but also other materials are imaginable. Plastics which may be used are for example polyethylene, polypropene, polya ide, aliphatic polyesters or copolymers of these materials, also together with other materials.

As appears from the figure the protrusion consists of a neck 2 which narrows somewhat as it extends outwardly. On this neck 2 a hat 3 is formed. This hat 3 has the shape of a cone which widens as it extends outwardly. The hat is suitably bowl shaped as is shown by the reference 4. The advantage therewith is that the edge of the cone becomes somewhat resilient and can more easily penetrate into the pores in the opposite material. The slope of the cone compared to the base surface, the angle α is not critical, it being able to vary from substantially 0 to substantially 90° but it is preferably in the order of size 25-50°.

The total height H of the protrusion can be of importance. If the neck 2 is too long, the protrusion can be bent, if it is pulled sidewardly when it is inserted in the opposite material. It should therefore not be too long, nor too short as problems can then arise when it is inserted into the opposing pores. A suitable relation between the section C of the base of the neck and the total height H of the protrusion is in the region of 0,8-1,7. The height H is 0,3-0,4 mm and the base dimension C, 0,2-0,4 mm. Other dimensions can also exist.

In Fig. 1 the protrusion has been drawn with an ideal shape whereby the neck 2 and the hat 3 are round. Large deviations from this shape can however exist and also from the conical shape of the hat. With the hooks described above an attachment surface such as a non-woven material can be used. With usual known hook and loop constructions non-woven can not be used as an attachment surface. This is due mainly to the fact that the heads of the hooks or protrusions of the known materials are too large to penetrate into the small pores of the non- woven material. With the protrusion according to the present invention the pores of a non-woven material can be entered and the attachment will be very good.

The non-woven material which can be used in accordance with the invention is for example a spun-bonded fabric, a carded thermo-bonded non-woven or an elastic non-woven material, for example of spun-bond/melt-blown/spun-bond-type, although other types can be used. These materials should have an inner tensile strength (in the direction of the machine) of 50-41 N/50 mm and preferably 20-30 N/50 mm. This tensile strength is measured according to the EDANA- standard of February 20, 1989.

The perhaps most important property of the material of the attachment surface is the inner pore diameter. This should on average be 0,10-2,0 mm. Fig. 2 shows how this diameter is measured. As appears the pore in the present case is formed by a distance between three fibres 5. The pore diameter 6 is the diameter which according to standard methods is measured in a circle which falls within this network of fibres 5. The measuring equipment that measures this kind of diameter is standardized and can be a Quantimet 900 Series Image Analysis from Cambridge Instrument Ltd of B Barhill, Cambridge, CB 38 EL United Kingdom. The pores in the material will of course be of very different size and one has therefore standardized the expression of the pores and introduced the expression equivalent circle diameter (ECD) . Through the present combination of a special hook and loop connection and use of a non-woven material one has obtained a new hook and loop connection having good properties and low production costs. This particular hook and loop connection opens new possibilities for the use of hook and loop connections, since it was previously impossible to use non-woven as an attachment surface for conventional hook and loop surfaces.

The invention is not limited to the embodiment examples shown but can be varied in different ways within the scope of the patent claims.

Claims

CLAIMS:

1. Hook and loop connection comprising a layer having attachment threads or protrusions protruding from one surface and a surface which allows adherence through anchoring of the projecting threads or protrusions, c h a r a c -t e r i z e d in that the layer consists of plastics or the like having the attachment protrusions in the shape of a neck (2) with an outwardly widening substantially cone-shaped hat (3) , the anchoring surface being of non-woven material.

2. Hook and loop connection according to claim 1, c h a r a c t e r i z e d in that the conical side of the cone shaped hat (3) has a slope (α) relative to the base surface (1) of substantially 0-90°, preferably 25-50°.

3. Hook and loop connection according to any of claims 1-2 , c h a r a c t e r i z e d in that the total height (H) of the protrusion with respect to the base (C) of the neck (2) is 0,8-1,7.

4. Hook and loop connection according to any of claims 1-3, c h a r a c t e r i z e d in that the neck (2) narrows outwardly somewhat.

5. Hook and loop connection according to any of claims 1-4 , c h a r a c t e r i z e d in that the non-woven material consists of a spun-bonded fabric, a carded ther o- bonded fabric or an elastic non-woven having an inner tensile strength MD of 15-40 N/50 mm, preferably 20-30 N/50 mm and an inner tensile strength CD of 5-25 N/50 mm, preferably 10-20 N/50 mm, both with a surface weight of 23 g/m².

6. Hook and loop connection according to any of the claims 1 and 5, c h a r a c t e r i z e d in that the equivalent circle diameter ECD in the pores of the non- woven material is on average 0,10-2,0 mm.