GB2149715A - Manufacturing footwear - Google Patents

Abstract

A method for manufacturing footwear, especially slippers is described wherein the upper is comprised of fibrous layers, one of which contains thermoplastic fibres which are softenable at a temperature in the range of 90 DEG -180 DEG C, and during the manufacture of the slipper heat is applied to the upper in order to soften the fibres. This has the effect of melting and fusing the fibres to provide rigidity in the upper. The heat may be provided by the heat of vulcanisation if the footwear sole is vulcanised to the upper. Alternatively the sole may be injection moulded onto the upper.

Description

SPECIFICATION Improvements relating to footwear This invention relates to the production of footwear, and in particular concerns the production of slippers, and in this specification hereinafter, reference will be made only to slippers. It may be however, that footwear produced according to the invention can be used other than as slippers, and the scope of the invention should be construed accordingly.

The invention is concerned with the materials which are used for slipper uppers, and provides a significant departure from the usual materials used for this purpose with, as will be clear hereinafter, considerably improved effect.

In known construction, the material which is used for a slipper upper is soft and flexible and comprises a laminated sheet structure including a lining fleece layer, a layer of foam and a covering fabric, adhered in that order. A blank is cut from this material and portions of the blank are connected to give the blank a rough three dimensioned shape of the slipper upper, with the lining fleece to the inside. The blank is placed on a last and then a sole is applied to the upper either by vulcanising moulding or by injection moulding, whilst the upper is on the last. In this arrangement, the foam layer performs two functions, namely to connect the inner fleece and the outer layer and to add body or rigidity to the laminate which is required of the slipper upper.

In another known arrangement, the upper material comprises a needle punched fabric which is impregnated with a synthetic resin and to this fabric is laminated the covering fabric. The resin impregnation tends or contributes to the said body or rigidity of the laminate. Again, the sole is applied by vulcanising moulding or injection moulding.

The known methods have the same disadvantage thatthe production ofthe laminated upper material is time consuming and expensive. In the first method the disadvantage arises because of the need to laminate the inner fleece, foam layer and outer layer, and in the second method the disadvantage arises from the need to use an impregnating resin.

The present invention provides, by material design, that the said disadvantage of each of the known methods can be overcome.

In accordance with the invention, there is provided a method of manufacturing a slipper wherein an upper blank of sheet material has a sole applied thereto in a moulding process, wherein the said sheet material includes a fibrous structure which increases in body and rigidity at least in preselected areas under the action of heat, and heat is applied to cause said increase in body or rigidity.

This method permits of eliminating the need to have a foam layer, and also the need to resin impregnate the upper material or any part thereof with synthetic resin.

It will be seen that the body and rigidity of the upper material increases, at least in preselected areas, during the moulding operation, and when the moulding operation is byvulcanising the heat of the vulcanising operation can be used or in fact serves to effect the increase of the body of the fibrous structure.

It may be necessary to add additional heat when the moulding operation is an injection moulding process.

The blank material may be a laminate including a fibrous layer including thermoplastic fibres of a low softening point, such layer forming the said fibrous structure, and the thermoplastic fibres softening during the process and subsequently setting to provide the increase in body and rigidity.

The said fibrous layer may comprise a mixture of thermoplastic low melting point fibre and another fibre which will not soften during the process of the invention, such other fibre (the stable fibre) being for example a polyester fibre. The range of the proportions of the fibres may be from 95% to 30% of the stable fibre and 5% to 70% of the thermoplastic fibre.

When the blank material is a laminate, good results have been obtained using a needled fibrous layer of weight approx. 240 grms/sq m and comprised 60% of stable fibre and 40% of the low melting point fibre, which represents same 30-50% of the total weight of the blank material. The low melting point fibre should be of a type which softens at a temperature in the range of 90 - 1 80 C. The weight of the fibrous layer can vary over a wide range, from 10 to 100% of the total fabric weight.

To the said fibrous layer may be needled a fleece layer (itself needled and of suitable acrylic, viscose or other fibre) which provides a soft lining in the finished slipper and also keeps the softenable layer out of contact with the last during the moulding operation. The fleece layer may be of a weight of 100 grms/sq metre. To the other side of the fibrous layer there may be a covering layer, suitably connected thereto by adhesive or by flame bonding, for example according to the technique according to British Patent No. 2024099.

By selecting the shape of the last, it can be arranged that the heat (and pressure if appropriate or required) to rigidify the fibrous layer is applied only in selected regions, for example in the toe and/or heel region, where the rigidifying effect is required leaving the upper in the soft state in other regions, making the slipper more comfortable to the wearer.

The degree to which the fibrous layer is softened and subsequently rigidified depends upon the quantity of heal softenable fibres in the layer and a number of factors including temperature, pressure and the time during which the heat and/or pressure are applied, and these can be varied to experiment to find the best conditions for particular applications.

After the heat has been applied to soften the fibres, sufficient time must be allowed to enable the fibres to solidify to achieve the increase in rigidity in the upper material.

Although the material of the blank is said possibly to be a laminate, the invention can be applied to one and two layer fabrics, wherein (a) the fibrous layer provides the total mass so there is no face cloth or lining, or (b) only the lining is dispensed with.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, wherein: Figure 1 is an exploded perspective view of the layers of the material which forms a slipper upper; Figure 2 is a plan view of a slipper upper blank cut from the material shown in Figure 1; Figure 3 shows in perspective view how the blank of Figure 2 is formed to rough three dimensional form for fitting on the mould last; Figure 4 shows in side view the three dimensional form of blank shown in the Figure 3 when in position on the last of the mould in which the slipper sole is formed; and Figures 5 and 6 show in top and underneath perspective views respectively a "bagged" slipper construction prior to the lasting thereof.

Referring to the drawings, in Figure 1 there are shown the three layers 10,12, of a laminated flexible fibrous material which is used for making slipper uppers. The significant layer as concerns the present invention is the middle layer 12, which is a fibrous needled material of a weight of approximately 240 gramms per square metre, and the layer is made up of some 60% stable fibres, such as polyester fibres which are not effected by the heat subsequently applied in the process, and some 40% of thermoplastic low melting point fibres which soften at a temperature of the order of 140"C.

To the top of the middle layer 12 is a fleece lining layer 10, which is also a needled fabric, and typically it may be of a weight of the order of 100 gramms per square metre. The layers 10 and 12 may suitably be connected by being needled together. To the other side of the intermediate layer 12 is a covering layer of any suitable, conventional covering fabric 14 as used for slipper uppers. The covering layer may be connected to the intermediate layer by any suitable means, such as adhesive, although we prefer+ use a flame bonding technique as described in British Patent No. 2024099, in which the surface fibres of the intermediate layer 12 are softened by flame heating, and then the covering layer 14 is applied thereto whilst the surface fibres are still soft.

The laminate material constructed from the layers as indicated in Figure lisa soft flexible material of insufficient coherence and rigidity to form a slipper upper, but it can be made of acceptable stiffness by heating same, so as to cause softening of the thermoplastic low melting point fibres in the intermediate layer which, after such softening, set in welded together arrangement, thereby to increase the stiffness of the laminate. Suitably, the application of heat takes place during the moulding of the slipper sole, as will be explained.

Figure 2 shows a blank 16 of material cut from the laminate illustrated in Figure 1,such blank being formable to provide the slipper upper. In the toe region, the slipper upper may be provided with a motive or other decoration 18.

The blank is initially shaped to a rough three dimensional form as indicated in Figure 3, by connecting together the end regions 20, 22, by sewing or other means. It may be possible, by suitable utilisation of the heat softenable fibres, to connect these edges by a heat sealing process.

In order to complete the slipper, the rough three dimensional form as shown in Figure 4 is applied to a last 24 to which has been pre-applied an insole 26.

The lower edges of the rough three dimensional form may be connected by cord or string 28 across the sole region, in order to ensure that the blank lower edge will iie to the underside of the last 24 and will lie in the mould 30 for the sole material. When the sole is applied by vulcanising rubber, the mould is filled with blocks of rubber, and then heat is applied, which will result in the rubber softening and flowing to fill the mould 30. In fact, when the sole moulding process has been completed, and the slipper removed from the mould, a few minutes cooling time is required before the sole and upper are set sufficiently ready for dispatch.

By so shaping the last, it is possible to arrange for heat to be applied to the upper only in selected regions, so that said stiffening effect will take place only in selected regions, and it is possible to intensify this stiffening effect in other regions, such as the heel and toe area, by using external pressure pads which are applied to the upper fabric during the moulding. The whole of the upper will be under slight pressure during the moulding operation, as the last 24 is sized in relation to the blanks that they have to be tensioned in being positioned on the last.

in the arrangement of Figures 5 and 6, a "bagged" slipper is shown and comprises an upper blank 30 and an insole blank 32 sewn together at 34 as shown before the bagged slipper is placed in the mould to have the sole applied by any arrangement as described herein. The upper, and also sole may be any of the materials as described previously herein.

Claims (13)

1. A method of manufacturing a slipper wherein an upper blank of sheet material has a sole applied thereto in a moulding process, wherein the said sheet material includes a fibrous structure which increases in body and rigidity at least in preselected areas under the action of heat, and heat is applied to cause said increase in body or rigidity.

2. A method according to claim 1, wherein the moulding operation is byvulcanising, and the heat of the vulcanising operation is used or served to effect the increase of the body of the fibrous structure.

3. A method according to claim 1 or 2, wherein the blank material is a laminate including a fibrous layer containing thermoplastic fibres of a low softening point, such layer forming the said fibrous structure, and the thermoplastic fibres soften during the process and subsequently set to provide the increase in body and rigidity.

4. A method according to claim 3, wherein the fibrous layer comprises a mixture of thermoplastic low melting point fibre and another fibre which will not soften during the heating.

5. A method according to claim 4, wherein the said other fibre is a polyester fibre.

6. A method according to claim 5, wherein the range of proportions of the fibres comprise 80% to 30% of the stable fibre and 20% to 70% of the thermoplastic fibre.

7. A method according to claim 6, wherein the fibrous layer comprises a needled fibrous layer of weight approx. 240 grms/sq m and comprising 60% of the stable fibre and 40% of the low melting point fibre.

8. A method according to claims 5,6 or 7, wherein the low melting point fibre softens at a temperature in the range of 90 - 180"C.

9. A method according to any preceding claim, wherein the fibrous layer is needled to a fleece layer which serves to provide a soft lining in the finished slipper, and also serves to keep the softenable layer out of contact with the moulding last during the moulding operation.

10. A method according to claim 9, wherein to the otherside of the fibrous layer from the fleece layer is a covering layer suitably connected to the fibrous layer by adhesive or flame bonding.

11. A method according to any preceding claim, wherein the heat to residify the fibrous layer applied only in the toe and/or heel region.

12. A method of manufacturing a slipper substantially as hereinbefore described with reference to the accompanying drawings.

13. A slipper produced bythe method according to any one of the preceding claims.