Description of Invention

This invention relates to a method of making a laminant.

According to a first aspect of the invention we provide a method of making a laminant comprising laminating together with a bonding agent, a first layer comprising paper, and a second layer comprising fibre reinforcement or paper, and subsequently treating the laminant by one of laterally compressing, corrugating, creping or embossing the laminant.

A laminant made according to the first aspect of invention is suitable for use in many applications, in particular as a protective packing material and as a backing for a carpet underlay.

It has been proposed for example in GB patent 1422940 to make a backing for a carpet underlay by reinforcing a creped paper sheet with stitches of textile material which render the creped paper inextensible.

In British patent 1419948 an alternative arrangement is described comprising a woven or non-woven mat of reinforcement which is bonded to a creped paper sheet.

In each of these prior proposals, the rigidity of the reinforcement negates the innate flexibility which the creped paper might otherwise provide. Particularly with backings which include stitches of textile material, splitting of the backing is common when the underlay becomes stretched during the carpet fitting process, or when subjected to high loading.

Thus the creped paper provides only a cosmetic effect and the rigidity of the reinforcement does not enhance the overall performance of the underlay when the backing is bonded to an elastomeric or other base layer of the underlay.

Particularly where the second layer comprises fibre reinforcement the laminant may be used as a backing for a carpet underlay.

Thus a backing for a carpet underlay is provided in which the backing acts rather like a spring, the reinforcement providing a dampening system. Hence movements of the backing relative to the elastomeric or equivalent base layer can

therefore be accommodated during bonding while improved load distribution characteristics are obtained in the finished product. Hence the backing is less prone to splitting.

Particularly, where the second layer of the laminant is paper, the laminant is ideal for use as a packaging material.

According to a second aspect of the invention we provide a method of making a carpet underlay comprising laminating together with a bonding agent, a backing made by a method according to the first aspect of the invention and a base layer of crumbed, cellular or foamed elastomeric material or the equivalent.

According to a third aspect of the invention we provide a backing for a carpet underlay being a laminant comprising a first layer comprising paper and a second layer comprising fibre reinforcement, laminated together by a bonding agent, the laminant having been treated subsequently to lamination by one of subjecting the laminant to lateral compression, corrugating, creping or embossing.

According to a fourth aspect of the invention we provide a carpet underlay comprising a crumbed, cellular or foamed base layer or the equivalent, having secured thereto a backing, the backing comprising a laminant comprising a first layer of paper treated by one of lateral compression, corrugating, creping or embossing, and a second layer comprising a reinforcing mat comprising randomly aligned short fibres bonded to the first layer by a bonding agent.

According to a fifth aspect of the invention, we provide packaging material comprising a laminant made by the method of the first aspect of the invention.

The invention will now be described with reference to the accompanying drawings in which:

FIGURE 1 is an illustrative cross section of a first embodiment of a laminant for use in making a backing for a carpet underlay in accordance with the invention;

FIGURE 2 is an illustrative cross sectional view through a second embodiment of a laminant for use in making a backing for a carpet underlay, in accordance with the invention;

FIGURE 3 is an illustrative cross section of a first embodiment of a laminant for use as a packaging material in accordance with the invention;

FIGURE 4 is an illustrative cross section view through a second embodiment of a laminant for use as a packaging material in accordance with the invention.

Referring to figure 1, thereds shown a laminant 10 for use in making a backing of a carpet underlay, in accordance with the invention.

The laminant 10 comprises a first layer 11 bonded to a second layer 12 by a suitable bonding agent such as an adhesive which is indicated at 13.

In this example, the laminant 10 comprises only the two layers 11 and 12 and the adhesive 13.

The first layer 11 comprises paper having a base weight typically of between 40 and 60 grams per square metre, but in an alternative arrangement, could have a base weight anywhere in the range 20 to 200 grams per square metre.

The paper layer 11 may be 100% virgin paper, or may be in part, or even entirely, recycled paper. The paper layer 11 may be bleached, unbleached or even coloured, as desired.

The second layer 12 is a layer of fibre reinforcement comprising either a mat of randomly arranged short fibres, or cloth being woven or unwoven. Any suitable fibres of low extensivity (by which we mean being extensible by less than 30% of their unextended length) and high strength may be used and typical examples are natural fibres such as cotton or wool, or synthetic fibres such as polyester, nylon, fibreglass, polypropylene, or even carbon fibres or a mixture of two or more of any of these. In an alternative arrangement the second layer 12 could comprise paper, either the same as that comprising the first layer or of a different form.

The second layer 12 is bonded to the paper layer by means of preferably a non-thermoplastic adhesive such as ENA or PNA. However in some instances, depending upon the kind(s) of fibres of the layer 12, and the nature of the layer 12 i.e. whether the layer 12 is a mat or cloth, a pressure sensitive adhesive may be used.

In some applications, even a thermoplastic adhesive such as Atatic Polypropylene may be suitable.

The laminant 10 may be made by feeding a web of paper 11 and a web of reinforcement 12 from respective rolls to a laminating station where adhesive is applied to at least one of the webs, the webs then being brought together for example between pinch rolls. The adhesive is then cured or permitted to cure as appropriate.

Alternatively, the laminant 10 may be made by feeding a web of paper 11 from a roll, to a laminating station where adhesive is applied. Randomly aligned short fibres are then deposited onto the adhesive. The laminant 10 might then be subjected to light pressure e.g. from a nip roll, and the adhesive allowed to cure or cured, as appropriate.

Next the laminant 10 is subjected to treatment to give the laminant 10 a damped springy property. Such treatment may in one example comprise lateral compression of the laminant 10, for example to form the laminant 10 into a concertina type configuration in one or preferably more than one lateral direction of the laminant 10 i.e. longitudinally and/or transversely of the extent of the laminant 10. Thus the lateral dimension of the laminant 10 in the or each direction of compression may be reduced typically by about 10 to 20%.

Alternatively, such treatment may comprise corrugating the laminant so as to reduce the laminant dimensionally typically by about 10-20%, preferably in more than one lateral direction.

Further alternatively, such treatment may in another example comprise creping, which involves applying the laminant 10 to a creping roller and removing the laminant 10 so that the laminant becomes crinkled or ridged, preferably again

so as to reduce the laminant dimensionally typically by about 10 to 20%, preferably in every lateral direction.

Yet further alternatively, treatment of the laminant 10 may comprise embossing the laminant 10 in such a manner that subsequent to embossing, the laminant 10 is laterally extensible in, preferably every lateral direction, or at least one lateral direction, by about 10 to 20%.

In each case, the treated laminant 10 is extensible in at least one lateral direction, preferably all lateral directions, for example as a consequence of the backing when laminated to a base layer as hereinafter described, being subjected to weight, as a carpet above the backing, is walked upon, and the backing and base layer return to their original unextended state, when the weight is removed.

The backing thus provided is bonded by a suitable adhesive or otherwise, to a base layer comprising a crumbed cellular or foamed elastomeric material or equivalent, which may itself be ridged or wrinkled, to provide a carpet underlay.

Referring to figure 2, a laminant 20 is shown, which comprises two layers 21 and 22 of paper, and an intermediate reinforcing layer 23, each of the paper layers 21 and 22 being bonded to the intermediate reinforcing layer 23, by adhesive as indicated at 24.

The paper layers 21 and 22 may be the same as layer 11 in the embodiment of figure 1, although preferably having a base weight of between 35 and 45 grams per square metre, although the layers 21 and 22 may each have a base weight of between 20 and 100 grams per square metre if desired.

The layers 21 and 22 need not be of identical base weights, and nor need they be of the same kinds of paper. For example, the layer 21, which may be the uppermost layer of the carpet underlay, may be of unbleached paper, whereas layer 22 may be a bleached paper of a different base weight to paper 21.

The adhesive 24 may be of the same constituency as adhesive 13 described in the embodiment of figure 1.

The layer 23 of reinforcement may be of the same or similar construction to the reinforcing layer 12 described with reference to figure 1.

After the laminant 20 has been made, for example by feeding webs of paper 21,22, from two separate rolls along with a web of reinforcing layer 23 to a laminating station and applying adhesive to at least one of each of the layers 21 and 22 and/or the reinforcing layer 23, the laminant 20 may be treated by creping, corrugating, lateral compression or embossing. The backing thus produced may then be used to make a carpet underlay by adhering with adhesive or otherwise bonding the backing to a base layer comprising crumbed, cellular or foamed elastomeric material or its equivalent.

If desired, instead of laminating the layers of laminant 10 or 20 together using adhesive 13,24, as described above, the reinforcing layer 12 or 23 may contain another bonding agent which may be activated when the layers are compressed together at the lamination station, or by the application of heat, or any other bonding agent may be used to bond the layers of the laminant 10 or 20 together.

Referring to figure 3, there is shown a laminant 30 for use as a packaging material, in accordance with the invention.

The laminant 30 comprises a first layer 31, bonded to a second layer

32 by a suitable bonding agent e.g. an adhesive which is indicated at 33. In this example, the laminant 30 comprises only the two layers 31 and 32 and the adhesive 33. The first layer 31 comprises paper, and the second layer 12 comprises a layer of fibre reinforcement or a second layer of paper. The adhesive

33 or other bonding agent may be any of the previously described forms.

The laminant 30 is made as described above for the laminant 10.

Referring to figure 4, a laminant 40 is shown, which comprises two layers 41 and 42 of paper, and an intermediate layer 43 comprising either fibre reinforcement and paper. Each of the paper layers 41 and 42 is bonded to the intermediate layer 43 by adhesive as indicated at 44.

The layers 41, 42 and 43 may take any of the forms previously described and the adhesive 44 may be of the same constituency as adhesive 13 described in the embodiment of figure 1. The laminant 40 is made as described for the laminant 20 of figure 2.

The laminants 30 and 40 are suitable for use as a packaging material, and in particular for use in a packaging system such as described in co-pending GB patent Application No. 9322889.8.

The features disclosed in the foregoing description, the accompanying drawings or the following claims, expressed in their specific forms or in terms or means for performing the desired function, or a method or process for attaining the disclosed result, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.