WO2002018691A2

WO2002018691A2 - Jute/cotton composites for use in the manufacture of footwear components and method of manufacture of such composites

Info

Publication number: WO2002018691A2
Application number: PCT/IN2001/000149
Authority: WO
Inventors: Mani Shankar Almal
Original assignee: Mani Shankar Almal
Priority date: 2000-08-28
Filing date: 2001-08-28
Publication date: 2002-03-07
Also published as: WO2002018691A3; AU8438301A

Abstract

A composite in the form of sheet, fabric and the like for use in the manufacture of footwear components, said composite comprising jute fibre/fabric optionally with cotton or other known natural or synthetic fibres/fabrics, said fibres/fabrics being impregnated with emulsion and/or coated with adhesive. The emulsion is prepared by combining styrene monimer, talc, PVA and SBR. The adhesive used for producing sheet materials for toe puffs and counters has the following formulation: Polystyrene - 25 to 40 % by wt., Waste material - 10 to 25 % by wt., Plasticizers - 0.5 to 3 % by wt., Filler - 5 to 25 % by wt., and Solvent - balance.

Description

JUTE/COTTON COMPOSITES FOR USE IN THE MANUFACTURE OF FOOTWEAR

COMPONENTS AND METHOD OF MANUFACTURE OF SUCH COMPOSITES

The present invention relates to jute composites in the form of sheets, fabrics and like for use as footwear components and method of manufacture of such composites. In particular, the jute composites of the invention are used for the manufacture of various footwear components such as toe puff sheets, counter stiffener sheets, insoles sheet and cut and skived components. The footwear components produced from the jute composites according to the invention have superior application properties.

It is well known to provide toe puff in toe (front) portion of a footwear while counter stiffener is used on the backside of a footwear. Both are inserted between the leather and lining material for the purpose of stiffness, shape retention etc. Insoles are important components are used while pasting and stitching with the upper and is inside the outer sole. All these components or semi-finished sheet materials are commonly produced from leather, leather board, man-made synthetic non-woven, cotton woven fabrics, cellulose paper pulp etc.

Such cotton and leather based materials are expensive and add to the footwear cost. Also such cotton/ leather based materials are not readily available and involve complex manufacturing process. Such materials are required to be imported in the form of large volumes of semi finished sheet materials for toe puff, counters and insoles. These sheet materials are cut to shape either by the fabricators doing job work or by the footwear manufacturers themselves in view of non-availability in the required quality and volumes. The cheaper availability of man made synthetic non- woven fabrics in the international market has been dominating over expensive cotton and leather based materials.

Also where leather scrap and leather board has been cheaper such as in India there has been many problems like thickness variation, complicated process in- consistency etc. As a result toe puff, counter and insoles, made of indigenously generated non-leather materials has emerged as major drawback for producing components consistently. The presence of banned chemicals like PCP, Benzodine, AZO etc. also poses problems in leather or leather board materials produced in India. The present inventors have found that jute which is a natural fiber available in abundance in India and Bangladesh and also cheap, high strength, and eco-friendly could be processed into useful material for footwear application.

It has, therefore, been the main object of the present invention to make effective use of jute for products used in the various footwear components.

It is a further object of the present invention to produce footwear accessories by the use of jute fabrics or jute mixed with other fiber/fabrics.

Yet another object of invention is to reduce the cost of such footwear components at the user's end by way of cost-effective replacement of leather, synthetic and cotton based footwear components presently in use, without compromising on the quality.

Yet further object of the invention is to produce jute composite or mixed fiber composites in the shape of semi finished sheet materials and finished components which are cut to shape and size for its ready use in footwear.

Yet another object of the invention is to provide an antistatic insole/fabric material for use in footwear for the safety reasons on jute /cotton/ mixed fabric, with or without chemical treatments.

Thus the invention relates to a composite in the form of sheet, fabric and the like for use in the manufacture of footwear components, said composite comprising jute fibre/fabric optionally with cotton or other known natural or synthetic fibres/fabrics, said fibres/ fabrics being impregnated with emulsion and/or coated with adhesive.

The jute fabric/ fibres are in the form of fabric, non-woven jute fibres, a mixture of fabrics and fibres and sandwitched fabrics.

The principal shoe components are toe puffs, counters, insoles and lining materials Such components prepared by the composite according to the invention have enhanced user properties. For toe puffs and counters the use of the composites according to the invention are found to have enhanced bond strength, shape stability, elongation and area shrinkage. For insoles produced by the components according to the invention properties such as water absorption, water de- absorption, flexing index/value, adhesion properties and tensile strength are superior to the known components available in the trade and known in the field.

Depending on the type of footwear and its use the specific properties of the material are determined for applications such as toe puffs, counters, insoles and lining materials.

According to a preferred aspect of the invention jute non-woven or jute/cotton weaved fabrics are impregnated in emulsion or coated with adhesive for the purpose of obtaining stiffness in the materials. The formulation and the solid percentage of the adhesive or emulsions are to be selected on the basis of requirements in the finished sheet which is to be formulated as per the suitability of the footwear design and requirement of the customer.

The adhesive used for the purpose of this invention is formulated with polystyrene along with waste material of expanded polystyrene (popularly known as Thermocol), solvents, fillers and plasticizers. The process for the preparation of the adhesive comprises mixing of the said raw materials in a stirrer for about 3 hours. The relative portions of the raw materials depends on specific applications.

The adhesive used for the composite for use in toe puffs and counters the following formulation :

Polystyrene - 25 to 40% by wt., preferably 30 to 35% by wt.

Waste material - 10 to 25% by wt., preferably 15 to 20% by wt. Plasticizers - 0.5 to 3% by wt., preferably 1 to.2% by wt.

Filler - 5 to 25% by wt., preferably 10 to 20% by wt.

Solvent - balance

For achieving greater stiffness and thickness properties in the toe puffs or counters solid materials in the formulation i.e. polystyrene, waste material and filler are used in higher levels. Greater stiffness is required for toe puffs and counters for use in. footwear for the gents and those for defence use.

Common plasticizers available in commerce may be used for the purpose of the invention, ^he-most ^■ pieferred-piasticizer is dioctyl pthalate (DOP).

Mineral powders are available commercially in diverse mesh size and may be used as fillers. It is preferred to use filler of finer mesh. The most preferred mesh size is between 200-300 mesh. The preferred fillers are dolomite, calcite, talc. Other fillers with similar properties may also be used.

The solvent used for the purpose of invention is selected from toluene, benzene, ethyl acetate, acetone, methyl ethyl ketone. The most preferred solvent is toluene and ethyl acetate.

The high impact polystyrene material having rubber content in the layer of 6-10% is used in the formulation of the invention. Commercially available polystyrene may be chosen. Polystyrene marketed by BASF, LG POLYMERS, SUPREME PETRO CHEMICALS are most suitable.

The emulsion used for the purpose of the invention are commercially available. The preferred ones are produced by using styrene monomer, talc, PVA and SBR in different ratios depending on application. One or more types of emulsions such as styrene, SBR, PVA etc are mixed with suitable fillers while formulating the emulsions used for fabric impregnation. Their ratio depends on the applications and the fabrics used for impregnation. Suitable emulsions are produced by M/s. Pidilite Industries, India and Bayer AB, Geπnany and are suitable for the purpose of the invention.

The fabric impregnated with emulsion/ coated with adhesive is cut into desired shapes by standard means. The cut components before application are dropped in solvent for activation of adhesive properties.

Some manufacturers do not prefer the solvent dip process but prefer a hot melt process in which the impregnated fabric is further coated with hot melt adhesive. The material thus obtained is cut into desired shapes for their use. The cut components in this case are subjected to heating for activating the adhesive properties.

-Jute fiber and -fabrics ιave-very good strength and compatibility with rubber-, - plastics and thermoplastic hot melt adhesive. A suitable combination with these materials could lead to better shape retention, strength, mouldability, moisture absorption and de-absorption, flexibility and like apart from considerable cost reduction and easy availability of raw material due to strong presence of jute crop in India and Bangladesh.

It is thus possible by way of this invention to provide jute composites for various footwear components following simple and cost effective process of manufacturing such as :

a. jute composite impregnated fabric for use in toe puff by solvent dip process

b. jute composite impregnated fabric for use in Counter stiffener by solvent dip process

c. impregnated fabric as stated in (a) and (b) above coated with hot melt adhesive for using in toe or counter by heat setting process

d. extruded film lamination of hot melt on impregnated a and b fabrics above for filmic - ping pong properties.

e. jute Composite fabrics impregnated in chemicals and/or sandwitch laminated fabrics for use in insoles in different thickness

f. cut and skived components for its ready to use.

According to one embodiment the invention, the process for the manufacturing of the composite fabric according to the invention comprises :

i) providing non-woven and/or woven fabric of jute and optionally cotton and other fibrous material: ii) impregnating the fabric with an emulsion or coated with an adhesive on one or both sides of the fabric;

iii) curing the impregnated fabric under heating ;

iv) cooling the fabric.

Both the emulsion impregnated and adhesive coated fabrics are suited for toe and/or counter applications and can be wound in roller form or cut to sheets. The emulsion /impregnated fabric of required thickness is also suitable for insoles. The adhesive coated fabrics are however not preferred for insoles. For thicker insoles two layered laminated sandwiched sheets are formed. In the invention razed or brushed jute fabric have resulted in better properties.

In accordance with another embodiment one side of the impregnated fabric is coated with hot melt adhesive. Such hot melt coated fabrics are most suitable for producing toes and counters.

In accordance with a further embodiment the impregnated fabric is provided with a coating of extruded film on the fabric (the filmic ping pong type for toe puff).

The impregnated fabrics according to the present invention is provided in roll or in sheet form which are then cut to desired shapes. The components thus produced are used as such or duly skived on the edges of the toe or counter. For insoles the unit shape is further moulded and fitted with shank in a separate fine in a conventional manner.

Standard impregnation machines/ stenters are used to carry out impregnation and drying of the fabric. The commonly used machines are marketed under the tradenames Bruckner, Isotex, Harish. The halt adhesive coating is made standard equipments which are commercially available and some popular names are NORDSON, ROBTECH and PRIMEC. The end products namely toe puff, counter and insole of different constructions are made from composite fabrics according to the invention and impregnated in types of specially formulated emulsions for stiffness. These fabrics are either supplied in rolls of standard sizes or in sheets of standard sizes packed in bundles or pellets. Such stiffened fabrics are cut to shape according to desired sizes. The hot melt adhesive coated stiffened fabrics are supplied in sheet form.

The invention also covers the production of finally shaped components i.e. toe puff, counters or insoles which are produced as per the pattern supplied by the customers and are sold in volume of pairs.

The details of the invention, its objects and advantages are illustrated hereunder in greater detail in relation to the non-limiting embodiments shown in the accompanying figures wherein :

Fig. 1 is a flow diagram of the manufacturing process for providing impregnated fabrics for the toe puff, coating and insoles.

Fig. 2 is a flow diagram of the manufacturing process of hot melt adhesive coating on impregnated fabric for use as thermoplastic toe puffs and counters.

Fig. 3 is a flow diagram of manufacturing cut and shaped components of toe puff, counters and insoles.

Fig. 1 shows an equipment in which process of impregnated fabric for toe puff- counters and insoles is effected. The calendar rolls and chiller rollers are added to the aforesaid standard machines by the manufacturers and this is a well known technique in the trade. In the flow diagram of Fig. 1 a standard equipment is shown which has the following components :

1. Fabric unwinder

2. Emulsion Tank for emulsion impregnation

3. A pair of squeeze rollers for removing excess material

4. Drying chamber fitted with rollers, heaters, exhaust, blower, radiators etc. 5. Three bowl Calendar rolls for surface finish and thickness control

6&7. Bowl Chilled Rollers for cooling the heated fabrics. 8. Shearing machine for sheet cutting in required sizes.

9. Winder for roll packing

10. Stacker

Fabrics are first put on the unwinder 1 in roll form which is passed through the emulsion tank 2 for impregnation in the required volume. The tank 2 is equipped with two dip rolls for impregnation of the required volume of emulsion in the fabric. The impregnated fabric are then passed through the squeeze rolls 3 to control the excess impregnated material and then enters the heating chamber 4 for curing of emulsion at the required temperature. The chamber 4 is designed to have rollers from inlet to outlet and fitted with heaters, air blower, exhaust, radiators etc. with the control panel for temp control. The heated fabric coming out from the chamber are passed through the 3 bowl chrome plated calendar rolls 5 for polishing, uniform surface and thickness. As the fabric remains heated with tack properties it is therefore passed through the chilled rolls 6 and 7, to cool them in total. The impregnated fabric can now be supplied in sheet or by cutting them in the required length on the shearing machine 8 or in rolls formed by winder 9. When sheets are formed the same is stacked on a stacker 10.

The impregnated fabric obtained from the steps shown in Fig. 1 is used for further application or subjected to hot melt adhesive coating on the machine shown in the fig. 2 for producing thermoplastic type materials.

Fig. 2 shows an equipment in which process of hot melt adhesive coating on impregnated fabric for use as thermoplastic toe puff and counters are carried out. In the process diagram of Fig. 2 a standard equipment is shown having the following main components :

11. Fabric Unwinder 12. Stand with roller for web tension 13. Adhesive tank with heating system 14&15. Roller with knife coating head 16*8517. A pair of bowl Chilled cooling roller 18. Sheet Cutter 19. Stacker stand for sheets 20. Winder for making rolls

The impregnated fabric coming out from the machine shown in Fig. 1 in roll form is put to unwinder 11 of the machine shown in Fig. 2. The fabric is then passed through the stand 12 fitted with rolls for controlling the web tension and then enters the adhesive coating stand 13 attached with the melting tank for regular flow of adhesive to roller with knife coating head 14. The fabric coated with adhesive is passed through the knife 15/rolls for controlling the thickness and then put through a pair of bowl chrome plated chilled rollers 16 & 17 for cooling the adhesive and remove surface tack. The sheet emerging from the roller 16&17 may be wound in the winder 20. If cut sheets are desired then sheets are formed by sheet cutter 18 and the sheets are stacked on stacker 19.

For reverse coat the fabric is wound on the roller after first side coat and then reversed on unwinder for coating the other side.

For filmic type toe puff : EVA/ polyester or polyamide based adhesive is coated on one side by using extrusion coating machine (single/co extrusion) instead of using a melt tank as shown in fig. 1 above.

The equipment shown in Fig. 3 carries out the process of manufacturing cut and shaped components of toe puff- counters and insoles. The machine of Fig. 3 is of beam press type and is provided to cut the sheets for making components in the required shape and size. The machine shown in Fig. 3 have the following main components :

21. Motor 22.Presser 23. Switch

24. Impregnated fabric sheets

25. Press

26. Clicking die

27. Machine base with oil tank The emulsion impregnated/ adhesive coated sheets are subjected to cutting to desired sizes and shapes in the machine of Fig. 3. The motor 21 is activated by switch_23_and_in turn the press 25 is pushed by the presser 22 and imparts presser on clicking dies 26 which in turn cuts the sheets 24 to produce components of desired shape and size. In the same operation a plurality of sheets 24 may be used. The machine based 27 as an oil tank provided therein. The beam press produces components using multiple number of sheets as per the thickness and the properties.

Samples produced by the process of the invention have been tested and the test results are shown in Tables I and II.

Table I shows data in respect of a sample of solvent activated stiffener sheet impregnated with emulsion 1.2 mm for toe and counter.

TABLE I

Test Methods : SATRA PM 83 : 1996 and SATRA AM 1 : 1992: SATRA PM 31 : 1997

A : for industrial and high quality footwear, B: for town and fashion comfort shoes, C : for inexpensive and light use footwear. This stiffener material is considered as medium hardness category suitable for industrial and high quality footwear as far as 1 - 4 tested properties is concerned.

Toluene is used as solvent. Dipping time 5 seconds. Drying, time to evaporate- surface solvent 60 seconds.

Table II shows data in respect of a sample of solvent activated stiffener sheet coated with adhesive on both sides for stiff counter.

TABLE II

Test Methods : SATRA PM 83 : 1996 and SATRA AM 1 : 1992: SATRA PM 31 : 1997

A : for industrial and high quality footwear, B: for town and fashion comfort shoes, C : for inexpensive and light use footwear.

This stiffener material is considered as very hard hardness category suitable for industrial and high quality footwear as far as 1 - 4 tested properties is concerned.

Toluene is used as solvent. Dipping time 5 seconds. Drying time to evaporate surface solvent 60 seconds. It is clear from the tables I and II that the jute composite produced according to present invention has the required properties and is most suitable for use as footwear components.

The machinery and raw materials and specification disclosed herein are only by way of illustration and not to the limit the invention. Variations of raw materials and specification including the machinery are included with the scope of the invention.

Claims

CLAIM

1. A composite in-tht- form-of sheet, fabric an the like for use in-the manufacture of footwear components, said composite comprising jute fibre/fabric optionally with cotton or other known natural or synthetic fibres/fabrics, said fibres/ fabrics being impregnated with emulsion and /or coated with adhesive.

2. A composite according to claim 1, being toe puffs and counters for use as footwear component having enhanced bond strength, shape stability, elongation and area shrinkage.

3. A composite according to claim 1, being insoles for use as footwear component having enhanced water absorption, water de-absorption, flexing index/value, adhesion properties and tensile strength.

4. A composite according to claim 1, wherein the emulsion is prepared by combining styrene monimer, talc, PVA and SBR.

5. A composite according to claim 1, wherein the adhesive used for producing sheet materials for toe puffs and counters has the following formulation :

Polystyrene - 25 to 40% by wt.

Waste material - 10 to 25% by wt.

Plasticizers - 0.5 to 3% by wt.

Filler - 5 to 25% by wt.

Solvent - balance

6. A composite according to claim 5, wherein the adhesive has the following formulation

Polystyrene - 30 to 35% by wt. Waste material - 15 to 20% by wt. Plasticizers - 1 to 2% by wt.

Filler - 10 to 20% by wt. Solvent - balance

7. A composite according to claim 5 or 6, wherein the plasticizer is dioctyl pthalate (DOP).

8. A composite according to claim 5 or 6, wherein the filler is selected from dolomite, calcite, talc and the like.

9. A composite according to claim 8, wherein the filler has mesh size of between 200-300 mesh.

10. A composite according to claim 5 or 6, wherein the solvent is selected from toluene, benzene, ethyl acetate, acetone, methyl ethyl ketone.

1 l.A composite according to claim 10, wherein the solvent -is selected from toluene and ethyl acetate.

12. A composite according to claim 5 or 6, wherein the polystyrene has rubber content in the layer of 6-10%.

13. A process for the manufacturing of the composite fabric according to claim 1, comprising the steps of-

i) providing non-woven and/or woven fabric comprising jute and optionally cotton and other fibrous material;

ii) impregnating the fabric with an emulsion or coating with an adhesive on one or hoth sides of the fabric;

iii) curing the impregnated fabric under heating ;

iv) cooling the fabric.

14. A process according to claim 13, wherein footwear accessories are obtained by cutting the fabric to desired shapes.

15. A process according to claim 13, wherein the impregnated fabric is subjected to a hot melt adhesive coating.

16. A process according to claim 13, wherein the composite obtained in sheet form is razed or brushed at the ends thereof.

17. A process according to claim 15, wherein the impregnated fabric is coated on one side with hot melt adhesive.

18. A process according to claim 15, wherein the impregnated fabric is coated on both sides with hot melt adhesive.

19. A process according to claim 15, wherein the impregnated fabric is provided with a coating of extruded film on the fabric.