WO1992002367A1

WO1992002367A1 - Method for the continuous production of composite flexible materials and plant for implementing the method

Info

Publication number: WO1992002367A1
Application number: PCT/EP1991/001363
Authority: WO
Inventors: Gabriele Melena
Original assignee: R.E.S. S.P.A.
Priority date: 1990-07-27
Filing date: 1991-07-19
Publication date: 1992-02-20
Also published as: EP0544691A1; IT9084140A1; AU8108091A; IT9084140A0; IT1242855B

Abstract

A method for the continuous production of flexible composite materials, comprising the steps of: spreading an adhesive (8) over the surface of at least one support (10); adding a cross-linking accelerator to the thus spread adhesive (8); bringing said support (10) into contact with another support (12) immediately before commencing the cross-linking of the adhesive (8); cross-linking the adhesive by applying heat at a temperature at least 30 °C higher than the spreading temperature; and applying compression to the two supports (10, 12) during the cross-linking of the adhesive.

Description

Method for the continuous production of composite flexible materials and plant for implementing the method

This invention relates to a method for the continuous production of composite flexible materials, in particular foamed tape for footwear and sportswear, and as trimming for automobile and general upholstery. The invention also relates to a plant for implementing the method.

Composite flexible materials are known, produced by bonding a natural or synthetic fabric to another natural or synthetic fabric, possibly of elastic foamed material (flexible polyurethane, PVC, EVA, etc.). In these known flexible materials the fabric performs a finishing function and limits the longitudinal and transverse elasticity of the composite material, whereas the foamed material gives the finished product the desired degree of comfort.

Various methods are currently used to bond the flexible materials together. One of these is "flame" bonding and consists of temporarily melting with a flame the surface or one of the two tapes to be bonded, so that on solidifying after being placed in contact with the other tape the two become securely joined together.

A drawback of this method is that it can be applied only to thermoplastic materials and can therefore not be used toi non-thermoplastic foams (polyurethane polyethers) or for EVA foam, which deforms permanently at 60ºC.

A further drawback is that the melting of the thermoplastic material produces harmfu l fumes der i v i ng from the thermal decomposit ion of the material itself.

Another known method is to wet-bond the two tapes with aqueous emulsions or spreadable 100% dry products. This method comprises depositing a cold, layer of aqueous emulsion on one of the two supports using a coating roller, then placing this upport against the other and finally evaporating the water using a heater roller.

The drawback of this method is that the product obtained is not finished byt requires curing for at least 24 hours before being fed to checking and/or used.

A further known method is to wet-glue the materials with resins dissolved in solvents.

The drawback of this method is that if the solvents are flammable the plant must be flameproof to protect it from possible fire. This is a real risk because of the presence of sparks due to the generation of electrostatic charges by the inevitable rubbing of the materials as they are brought into contact.

If however the solvents are non-flammable they are inevitably harmful, as they are of either chlorinated type (trichloroethane, methylene chloride etc.) or fluorinated type (freon).

In any event, whether flammable or non-flammable solvents are used it is always necessary to store the product after treatment to allow the adhesive to harden and cure.

It is also known to apply adhesives by spraying instead of spreading. This method however requires sprayable products, which have a lower viscosity and hence a lowersolids content, with consequent greater risk and greater environmental contamination.

This method also requires the treated product to be stored for the time required for the adhesive to harden.

According to the invention all these drawbacks are obviated by a method for the continuous production of flexible composite materials as described in claim 1.

To implement the method the invention propose a plant as described in claim 13.

A preferred embodiment of the invention is described hereinafter with reference to the accompanying drawing, which represents a schematic view of a plant for implementing the method of the invention.

As can be seen from the drawing, the method of the invention is implemented by a plant comprising a first coating station 1, a second additive application station 2, a

third bonding station 3 and a fourth cross-linking station 4.

The coating station 1 comprises a plurality of deviation rollers 5, a roller 6 for transferring 100% dry polyurethane adhesive and a distributor blade 7, which with the surface of the transfer roller 6 forms a type of tray for containing the adhesive 8 and spreads a uniform layer of adhesive over the surface of the roller 6 downstream of said blade 7. The quantity of adhesive spread over the surface of the roller 6 can be adjusted either by adjusting the distance of the blade 7 from said roller or by varying the speed of rotation of the roller, or by varying the distance between it and the roller 9 on which the tape 10 to be coated rests.

The additive application station 2 comprises a series of sprayers 11 which spary an accelerator additive onto the tape 10 already coated with adhesive.

The bonding station 3 comprises two separate feed lines for the material to be bonded, ie a feed line for a continuous tape 12, for example of fabric, arriving directly from a feeder, not shown on the drawing, and a feed line for the continuous polyurethane polyether tape 10, which arrives from a separate feeder after passing through the coating station 1 and additive application station 2. The bonding station 3, which lies a certain distance from the coating station 1 and additive application station 2, but immediately upstream of the cross-linking station 4, consists substantially of a roller 13 about which the two tapes 10 and 12 pass simultaneously.

The cross-linking station 4 comprises a pair of largediameter cylinders 14 provided with a system for heating their lateral surface to a temperature at least 30ºC higher than the cross-linking temperature of the polyurethane adhesive, and generally 70-100ºC. The surfaces of the two cylinders 14 are preferably heated by circulating a fluid at controlled temperature. Each cylinder 14 is supported by support rollers 14, one of which is motorized to rotate the corresponding cylinder 14 at a peripheral speed equal to that of the other cylinder.

The cross-linking station 4 also comprises for each cylinder 14 an endless band 16 passing about idle deviation rollers 17 and arranged to exert a certain pressure on the composite tape under formation, this being interposed between said endless band 16 and the surface of the corresponding cylinder 14.

To maintain the temperature in the cross-linking station 4 as constant as possible while at the same time reducing energy consumption, the two heating cylinders 14 are housed

in a single casing 19 which delimits the cross-linking station 4.

The method of the invention is as follows:

the fabric tape 12 reaches the bonding roller 13, at which the polyether tape 10 also arrives. This latter has previously passed through the coating station 1 in which it has received a uniform layer of polyurethane adhesive on that surface to be bonded to the fabric tape 12, and has further received the accelerator additive on this adhesive layer.

As the two tapes 10 and 12 pass about the bonding roller 13 they become provisionally bonded at ambient temperature, ie at a temperature lower than the cross-linking temperature of the polyurethane adhesive.

The composite tape 18 thus formed then enters the crosslinking station 4, where the prolonged time for which it remains in contact with the heating surface of the two cylinders 14 and the pressure exerted on it by the bands 16 result in cross-liking of the adhesive and intimate stable bonding of the two tapes 10 and 12, to thus form the composite material.

From the aforegoing it is apparent that the method according to the invention is very advantageous in that:

- it enables flexible composite materials to be produced with excellent bearing capacity, indeformability, resistance to separation and long life at low cost;

- it uses adhesives free of both flammable and non-flammable solvents;

- it enables high production rates to be attained;

- it can use differente types of adhesive; and

- it enables immediately usable products to be produced.

Composite tapes can also be formed of more than two layers, either by passing the layers through independent coating stations 1 and additive application stations 2 and then bonding them together in single pass, or by bonding the composite two-layer tape 18 leaving the cross-linking station 4 to further tapes.

Claims

C L A I M S

1. A method for the continuous production of flexible composite materials, characterised by:

- spreading an adhesive (8) over the surface of at least one support (10);

- adding a cross-linking accelerator to the thus spread adhesive (8);

- bringing said support (10) into contact with another support (12) immediately before commencing the crosslinking of the adhesive (8);

- cross- 1 inking the adhesive by applying heat at a temperature at least 30°C higher than the spreading temperature; and

- applying compression to the two supports (10,12) during the cross-linking of the adhesive.

2. A method as claimed in claim 1, characterised in that the adhesive is spread over the support (10) by passing said support about a coating roller (6), the surface of which has been previously coated with said adhesive layer.

3. A method as claimed in claim 2, characterised in that the adhesive layer (8) to be transferred to the support (10) is spread, over the surface of the coating roller (6) by forming between the surface of said roller (6) and a transverse blade (7) a tray for containing said liquid adhesive and rotating said roller (6) to distribute the adhesive over its surface in the required quantity.

4. A method as claimed in claim 3, characterised in that the quantity of adhesive (8) to be spread is adjusted by varying the distance between said blade (7) and said roller (6).

5. A method as claimed in claim 3, characterised in that the quantity of adhesive (8) to be spread is adjusted by varying the speed of rotation of said roller (6).

6. A method as claimed in claim 3, characterised in that the quantity of adhesive (8) to be spread is adjusted by varying the pressure of said roller (6) against the bearing roller (9) for the support (10;.

7. A method as claimed in claim 1, characterised in that the two provisionally bonded supports (10,12) are fed forward in contact with at least one cylinder (14) of heated surface, to thus heat the two supports and cause them to adhere together for the entire time necessary for cross-linking of the adhesive (8) to take place.

8. A method as claimed in claim 4, characterised in that mutual adhesion of the two supports (10,12) during crosslinking of the adhesive (8) is facilitated by compressing the composite tape under formation (18) against the surface of the cylinder (14) by means of a band (16) which is applied to said cylinder (14) external to said composite tape (18).

9. A method as claimed in one or more of claims 1 to 8, characterised by using a polyurethane adhesive.

10. A method as claimed in claim 9, characterised by using a 100% dry polyurethane adhesive.

11. A method for producing composite materials formed from more than two supports, characterised by simultaneously bonding together the various supports as claimed in one or more of claims 1 to 10.

12. A method for producing composite materials formed from more than two substrates, characterised in that at least one of the two substrates is a composite tape produced as claimed in one or more of claims 1 to I0.

13. A plant for implementing the method claimed in claim 1, characterised by comprising:

- a coating station (1) in which a layer of adhesive (8) is spread over a surface of at least one of the two supports (10,12) to be bonded;

- a station (2) in which a cross-linking accelerator is applied to the spread layer of adhesive (8);

- a bonding station (3) at which the two supports (10,12), at least one of which is coated with adesive plus additive (8), arrive along differente paths to be made to adhere to each other; and

- a cross-linking station (4) in which the two bonded supports (10,12) are kept adhering to each other under pressure while at the same time being heated to a temperature at least 30°C higher than the spreading temperature of said adhesive.

14. A plant as claimed in claim 13, characterised in that the coating station (1) comprises a roller (6) forming with a distributor blade (7) a tray for containing the liquid adhesive (8), the support (10) to be coated with the adhesive layer (8) contacting said roller downstream of said tray.

15. A plant as claimed in claim 14, characterised in that the distributor blade (7) is provided with members for varying the distance of its lower edge from the surface of the roller (6).

16. A plant as claimed in claim 14, characterised in that the roller (6) is provided with a regulator for adjusting its speed of rotation.

17. A plant as claimed in claim 14, characterised in that the roller (6) is associated with means for controlling its pressure against the support (10).

18. A plant as claimed in claim 13, characterised in that the additive application station comprises a bar of nozzles (1) which face that surface of the support (10) coated with the adhesive (8), and which are arranged to spray the crosslinking acceleration additive thereon.

19. A plant as claimed in claim 13, characterised in that the bonding station (3) comprises at least one roller (13) about which the two supports (10,12) pass.

20. A plant as claimed in claim 13, characterised in that the cross-linking station (4) comprises at least one rotating cylinder (14), against the heatnng surface of which there is made to adhere the composite tape originating from the bonding station (3).

21 A plant as claimed in claim 20, characterised by comprising and endless band (16) passing about deviation rollers (17) and adhering to the lateral surface of the cylinder (14) to press against its heating surface the composite tape (18) formed from the two bonded supports

(10, 12).

22. A plant as claimed in claim 13, characterised in that the cross-linking station (4) is enclosed within a casing

(19).