IE48742B1

IE48742B1 - Process for the treatment of non-woven fabric

Info

Publication number: IE48742B1
Application number: IE1109/79A
Authority: IE
Original assignee: Eurofloor Sa
Priority date: 1978-06-12
Filing date: 1979-08-08
Publication date: 1985-05-01
Also published as: IT1121384B; DK152226B; IE791109L; GB2023200B; ES481422A1; SE7905069L; DK242479A; DK152226C; BR7903799A; AU4777979A; NO154528B; CA1135568A; BE876811A; LU79799A1; NO154528C; IT7923466A0; DE2923542C2; AU523831B2; DE2923542A1; NL189720B

Abstract

A process for improving the physical properties of non-woven fabrics, particularly glass wool, for the purpose of rendering said fabrics more receptive to print comprises applying plastisol, having a Newtonian viscosity between 4 and 30 poise, to one surface of the non-woven material, and pressing the impregnated fabric with a roller against a cylinder heated to 130 and 180 DEG C. The impregnated side of the fabric is maintained in contact with the cylinder and at least partially covers said cylinder.

Description

The present invention relates to a process intended to improve the physical properties of non-woven fabrics, particularly glass wool, for the purpose of rendering said fabrics more receptive to print. The invention also extends to products obtained by this process.

Non-woven fabrics are generally used as backings for wall coverings, especially for floor coverings.

Less and less use is being made of asbestos for the construction of floor covering backings and efforts have therefore been made to replace asbestos by various other substances, among which glass wool is increasing in importance.

A usual method is to impregnate a sheet of non-woven fabric, usually of fibre glass, with a plastisol, with a double impregnation process in wnich one application is given to the reverse side in order to stop up the pores and the other to the front in order to obtain a perfectly smooth and non-porous surface, so that in a subsequent heliographic printing process the ink will not spread on the support. This double impregnation is generally performed in two successive steps.

After this double impregnation, which in fact is a front-and-back coating operation, the product is gelled in an oven through which the treated fabric is caused to circulate, in most cases continuously. 4-874-2 This process nevertheless suffers from certain drawbacks resulting from the fact that the coating of two surfaces of a sheet of non-woven material which is nevertheless not impregnated all through will frequently cause a certain quantity of air to be trapped in it. Subsequent heat treatments often cause the trapped air to expand under the effect of the heat and to form irregularities on the surface which render the product unsaleable.

The use of a gelling oven also considerably increases the size of the production lines, the said furnace being comparatively long and the output speed very limited.

The present invention thus intends to remedy the aforementioned drawbacks of the existing processes.

According to the present invention a non-woven fabric is impregnated all through by a simple and rapid method in which a plastisol having substantially a Newtonian viscosity, comprised between 4 and 30 poise, is applied at a temperature between 5 and 50°C to one single surface of the nonwoven fabric, whereafter the impregnated non-woven fabric is pressed by a pressure roller on a cylinder heated to between 130 and 180°C, the impregnated side of the non-woven fabric being in contact with the said cylinder and at least partially covering the said cylinder.

The said impregnated surface is the side on which the eventual heliographic printing will be carried out.

Under the conditions stated three results are observed which, occuring in combination, were totally unexpected, i.e, the plastisol is completely gelled without the impregnated fabric sticking to the roll, so that a good surface finish is obtained, the fabric is impregnated all through and the reverse side is pre-gelled and dry when leaving the cylinder.

After the cooling the resulting product undergoes heliographic printing and constitutes a semi-finished product serving as a base, particularly for the production of floor and other coverings.

The exact temperature for the treatment is chosen in accordance with the speed at which the product passes over the cylinder and with the diameter of the latter. A skilled operator will have no difficulty in selecting it in accordance with the installation available to him, which largely governs the speed at which the fabric moves and the diameter of the cylinder that can be used, as well as the appropriate temperature, by a series of tests performed in order to deter mine how to set the equipment in such a way that the fabric will be impregnated all through but will not stick to the roll.

When it passes over a cylinder of about 2 m in diameter at a speed of about 8 to 40 m/min, in such a manner that the material is in contact with approximately 75% of the outer perimeter of the roll, the best temperature will be of the order of 150°C.

In the usual present-day installations a temperature below 130°C prevents thorough impregnation, while if it is above the level indicated the fluidity will prove excessive, making it difficult to apply the plastisol satisfactorily and resulting in surface finishes which are unsuitable for a subsequent heliographic printing process.

The plastisol is of a type customarily employed for coatings. Within the viscosity range stated, i.e. 4-30 poise, preference is given to a viscosity of 6-15 poise, particularly to about 8 poise. The viscosity range can easily be obtained from commercial plastisol preparations, with the use of conventional dilution agents or, where necessary, thickening agents.

The rheological behaviour of the plastisol adopted may be substantially Newtonian, but slightly pseudo-plastic characteristics are nevertheless acceptable. A dilatant plastisol is however to be avoided.

When causing the material to pass over the heated cylinder, the non-impregnated surface is simultaneously pressed with a presser roller, preferably lined, with an elastic substance such as rubber.

It is noted that under these circumstances a pad of plastisol,which has the effect of creating an even film of this substance, forms upstream from the point of contact between the material and the heated cylinder. This provides a surface in the desired state, similar to that obtained in calendered films. A further unexpected effect, however, is that this pad of plastisol remains free of any thickening, which would make application impossible.

In practice the process can be carried out by the method described below by reference to a schematic diagram of a suitable installation for the purpose.

The one single drawing attached illustrates a suitable installation for the impregnation of a composite backing con10 sisting of any kind of base to which a sheet of glass fibre is applied.

The drawing shows a composite backing 1, consisting of a base and a sheet of glass and conveyed to an applicator roll 3 rotating in a tank containing a plastisol. The surface formed by the sheet of glass is in contact with the applicator roll and is supplied with a suitable quantity of the plastisol.

After this application the film of plastisol applied is smoothed on a return roll by means of an air knife 6 for 2o the emission of a thin film of air. The surplus plastisol is collected by a plate 7 integral with the tank 4 and returned to this latter.

The composite backing impregnated in this manner then passes to a heated cylinder 10 to which it is applied by cau25 sing it to pass between the said roll and a rubber-covered presser roller 12. A conventional device -is used for the pur48742 pose of ensuring even application, at adjustable pressure, of the presser roll 12 to the roll 10.

The plastisol-coated surface of the backing is applied to the cylinder 10 in such a way as to cover about 75-80% of the perimeter of the latter, as already indicated, the roll being heated, for example, to a temperature of the order of 150°C.

After passing over the roil the support can be detached from the latter without difficulty and is taken up by a return roll 15, from which it goes to a heliographic printing press, not shown in the drawing.

Among the piastisol compositions which can be used, mention may be made of the following: PVC 100 Stabilizing agent 2 Mixture of plasticizer of the phthalate type 60-120 Charge of crystalline dolomite 30-200 Ti02: 0-15 (preferably 2) The sheet of glass may be a conventional product such as a sheet of glass wool treated in such a way as to render it compatible with the PVC such as described in French Patent No 2.295.836, P.1, line 15.

In particular, a sheet of glass of the Schilller or AhlstrSm type can be used, possibly pre-treated, on a compact or foamable PVC support.

The invention will be described in greater detail by reference to a preferred method of carrying it out, this serving solely as illustration and having no limitative effect.

A composite backing consisting of a base of 280 g/m of 2 PVC covered with 60 g/m of glass wool is given an applica2 tion, at the rate of 500 g/m , of a plastisol of the follo10 wing composition: PVC 100.

Stabilizer 2.

Mixture of plasticizer of the phthalate type 90.

Charge of crystalline dolomite 35.

Ti02: 2.5.

The coating operation by the aid of the plastisol can be carried out in the type of installation described in conjunction with the accompanying drawing, but use can also be made of a coating roll, a coating device of the scraper type, a reverse roll or an equivalent coating device enabling the coating substance to be proportioned in the desired quantity.

The backing thus impregnated is conveyed onto a gelling cylinder 10, such as that shown in the attached diagram, passing under a presser roller 12, regulating the pressure to between 0 and 200 kg and preferably to 40 kg per linear metre.

The roll is heated to 150°C, and under these conditions a support is obtained which can be used for the production of wall coverings or decorative coverings but of which the main purpose is that of floor coverings. This support contains no air occlusions, of which the drawbacks have been mentioned farther back.

The good results obtained by the method of the invention are believed to be due to the selection of a plastisol being substantially Newtonian which undergoes a pressing by the effect of the pressure roller, thus forming a pad which remains free of thickening, i.e. a pad which is continuously renewed under production, the fresh material being fed being substantially equal to the material which is used in the operation.

This renewal prevents the gelling of the pad of plastisol by the heating effect of the cylinder.

It should be noted that a plastisol must be selected which will suitably impregnate the fibres. A dilatant plastisol should be avoided because it would cause a thickening of the pad.

Although a description has been given of practical examples and suitable installation for the performance of the invention, numerous variants are open to the man of the art and that the invention is not limited to the said examples or to the equipment illustrated.

In particular, for example, the treatment according to the invention can be applied to a sheet of fibre glass alone or to a composite product consisting of a sheet of fibre glass on a base, whether foamable or not48743 Furthermore, the non-woven fabric may consist of a material of a different nature from fibre glass.

Claims

1. A process for the treatment of a non-woven fabric wherein a plastisol having substantially Newtonian viscosity, of 4 to 30 poise, is applied at a 5 temperature between 5 and 50°C to one single surface of the non-woven fabric, whereafter the impregnated non-woven fabric is pressed by a pressure roller on a cylinder heated to between 130 and 180°C, the impregnated side of the nonwoven fabric being in contact with the said cylinder 10.

2. A process in accordance with claim 1, wherein a printing operation is carried out on the impregnated surface.

3. A process in accordance with claim 1, wherein the cylinder is heated to a temperature of approximately 150°C for a speed of movement of the non-woven fabric of 8-40 m/min for 15 a cylinder diameter of approximately 2m, the material being in contact with 75% of the outer periphery of the roll.

4. A process in accordance with claim 1, wherein the viscosity of the plastisol is between 6 and 15 poise.

5. A process in accordance with claim 1, wherein the 20 viscosity is approximately 8 poise.

6. A process in accordance with claim 1, wherein the material passes over the heated cylinder while the non48742 impregnated surface is simultaneously pressed with a pressure roller lined with an elastic substance.

7. A product obtained by the process described in any one of claims 1 - 6. 5

8. A product in accordance with claim 7, wherein the non-woven fabric consists of a sheet of glass fibre.

9. A product in accordance with claim 7, wherein the non-woven fabric consists of a sheet of glass fibre applied to a base, whether or not foamable.

10. 10. A product in accordance with claim 7, wherein the plastisol used is a foamable PVC plastisol.

11. A process substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.