METHOD OF FORMING CARPETING

Abstract: A method of forming a carpet comprising applying an adhesive to a backing material (1) via a perforated roller (3). As the roller (3) is passed over the backing material (1) adhesive is displaced out through the perforations in the roller (3) onto the backing material (1). Once the adhesive has been applied to the backing material (1) the backing material (1) is secured to the back surface of a pre-coated textile substrate layer.

Description: METHOD OF FORMING CARPETING TECHNICAL FIELD This invention relates to a method of bonding a backing material layer to a substrate layer in the manufacture of carpeting. BACKGROUND ART In the manufacture of so-called secondary backed carpeting comprising a tufted fabric substrate having a back surface to which is bonded a backing material, such as woven jute or polypropylene, it is usual to pre-coat the back surface and then to apply areas or spots of adhesive to one side of the backing material and then to press this side onto the pre-coated substrate surface while the adhesive and the pre-coat are still wet thereby to bond the layers together. The pre-coat may be a latex foam which collapses on application and acts to hold the tufts of the fabric layer in position and provides a coherent surface to which the backing material can be more readily bonded. GB 2172851A describes apparatus (the "said apparatus") for applying a coating material to a surface which comprises a transfer member in the form of a roller having a perforated outer wall, a guide arrangement for moving a surface to be coated in contact with or in close proximity to the roller, a feed arrangement for feeding fluent coating material to the perforated roller to be deposited therefrom onto the surface and an abutment for the coating material within the perforated roller, the feed arrangement being arranged to supply said fluent coating material to the outside of said perforated outer wall so that it forms a well of such material between the said surface and the said abutment throughout the perforated wall. GB 2172851A describes the use of the said apparatus for forming a coating layer having a desired flat or embossed patterned surface on an uneven surface such as the back surface of a tufted fabric layer of carpeting. GB 2212076A describes the use of the said apparatus to apply a pre-coat to a textile substrate. More particularly, the application describes a method of forming a flexible laminate by bonding a backing layer to a pre-coated textile substrate, said method comprising the steps of: moving the substrate with a guide arrangement relative to a rotatable transfer roller so that a back surface of the substrate is in contact with or in close proximity to the roller; feeding fluent settable coating material to the roller to be deposited therefrom onto the said back surface of the substrate; causing or allowing the deposited coating material to set so as to form a pre-coat on said back surface; and bonding a backing layer to said pre-coated back surface, characterised in that said transfer roller is a hollow perforated roller containing an internal doctor member; the fluent coating material is fed to the roller so as to form a well of the material between and freely in contact with the back surface and the doctor member through the perforated wall of the roller; and the spacing of the roller relative to the substrate and the pressure of the doctor member relative to the perforated wall of the roller are adjusted to give a desired .hickness or density of the pre-coat. GB 2220872 A describes the use of perforated roller apparatus for bonding a backing layer to a preferably pre-coated textile substrate in the manufacture of secondary backed carpeting. More particularly, the application describes a method of bonding a backing material layer to a substrate layer in the manufacture of carpeting wherein discrete areas of adhesive are applied to one side of one of said layers and said side is pressed into contact with the other of said layers thereby to cause said layers to be bonded together, characterised in that said discrete areas of adhesive are applied to said one side of said one layer with apparatus comprising a roller having a perforated outer wall, the said one layer being moved in contact with or in close proximity to the roller, fluent adhesive material being provided in the interior of the perforated roller, and the roller being moved relative to an abutment which is in contact with or in close proximity to the inner surface of the roller so that said adhesive material is displaced through the perforated wall of the roller and is deposited therefrom onto the said one layer. The methods of GB 2212076A and GB 2220872A are effective and advantageous in the context of conventional secondary backed tufted carpeting where the tufts run as a series of parallel, closely spaced, straight rows. In this case, the pre-coating technique gives rise to a coherent surface layer which facilitates good adhesion with spots of adhesive on the backing material. However, there has been a trend towards the introduction of so-called graphics style carpeting. This carpeting has differently configured rows of tufts aimed at producing interesting patterns. The rows may be of random, or pre-defined pattern giving an irregular or zig-zag or similar structure on the back of the tufted substrate. With this arrangement, two problems arise in relation to the attachment of backing material. First, with regard to the application of a pre-coat layer it is difficult to achieve a relatively even, coherent back surface without unduly adversely affecting flexibility. That is, due to the presence of a range of small and large gaps or holes between the tufts, it is difficult to fill all gaps or holes adequately without applying large quantities of pre-coat material which could undesirably increase the weight of the carpeting and impart undue rigidity or give rise to a 'biscuit' structure. Second, due to the irregular nature of the holes or gaps, the spots of adhesive on the backing material may coincide with depressions in the back of the textile substrate thereby reducing the strength of the adhesive bonding. An object of the present invention is to provide an improved method of forming secondary-backed carpeting which is suitable for use in the context of irregular or non-linear tuft patterns. DISCLOSURE OF INVENTION According to the invention therefore there is provided a method of bonding a backing material layer to a textile substrate layer in the manufacture of carpeting wherein a back surface of the substrate layer is pre-coated, adhesive is applied to one side of the backing material layer and said side is pressed in;o contact with the said pre-coated back surface thereby to cause the layers to be bonded together, characterised in that said adhesive is applied to said one side of the backing material layer by means of apparatus comprising a roller having a perforated outer wall, the said backing material layer being moved in contact with or in close proximity to the roller, fluent adhesive material being provided in the interior of the perforated roller, and the roller being moved relative to an abutment which is in contact with or in close proximity to the inner surface of the roller so that said adhesive material is displaced through the perforated roller and i eposited therefrom onto the backing material layer in the form of a thin film. With this arrangement, due to the use of a thin film of adhesive material it is possible to achieve secure attachment to the textile substrate layer, even if such substrate layer has an irregular or non-linear configurations of tufts, and without requiring the presence of an unduly heavy pre-coat layer. The backing material layer may comprise a woven jute or polypropylene layer or any other suitable material. The adhesive material may be of any suitable nature but preferably - o - comprises a fluent latex material. With regard to the pre-coat this may be a foamed material, particularly a foamed latex material and this may be applied with a perforated roller e.g. as described in GB 2212076A and/or GB 2220872A, or in any other suitable manner. If desired, a relatively low density pre-coat (achieved by a relatively high degree of foaming) can be used, e.g. using a conventional application screen. In this way, filling of irregular gaps or holes without giving an unduly heavy or rigid structure, and adequate bonding is ensured, notwithstanding the light nature of the pre-coat, due to the use of the thin film of material. Alternatively, a thinner layer of a higher density pre-coat can be applied using the perforated roller technique of the above mentioned prior patent applications, adequate bonding again being ensured by virtue of the thin film. Suitable materials for the pre-coat and the adhesive, are discussed in detail in the aforementioned prior applications to which reference is made for further information. A suitable structure for the perforated roller apparatus is also described in detail in the prior applications to which reference is made for further information. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described further by way of example only and with reference to the accompanying drawing which is a diagrammatic perspective view of one form of apparatus used in the performance of the method of the invention. s The apparatus illustrated comprises a perforated roller 3 having 40 mesh (300 micron) perforations and an internal squeegee blade 4 of 0.2mm x 3.5cm low pressure spring steel. An adhesive latex formulation is fed from a reservoir 5 into the roller to form a well 6 between end plates 8 adjacent the squeegee blade 4. The formulation comprises styrene butadiene latex (Dow 891) thickened with sodium polyacrylate (Texigel SPA 12) to give a viscosity of 8-9,000 cps (Brookfield RVT spindle 4 speed 20). The pressure of the squeegee 4 was adjusted so that the latex just came out of the roller perforations or screen. Woven polypropylene backing material 1 was then passed under the screen on a support roller 2 to give a smooth continuous thin film coating without appreciable penetration of the fabric or filling in of the interstices of the woven fabric. The weight applied was approximately 50 gms of dry latex per square metre of fabric corresponding to a film thickness of about 0.05mm. The coated backing material was then applied to a pre-coated tufted fabric and the coating materials were then dried. Delamination tests showed delamination strengths of better than 12kg per 50cm width compared with 2-4kg in the case of conventionally bonded carpeting. Smooth, even coatings were achieved and running speeds of 2-15 metres/min were possible without problems. Similar results were obtained using jute in place of the polypropylene. in a variation of the above test procedure, 0.5 % of soap Empicol LX28 was added to the latex. The latex was then fed to the screen at 700gms/litre density and processed as before. On woven polypropylene the weight reduced to 38gms dry latex per square metre but the delamination strength was still of the order of 12kg per 50 cm width. if desired the procedure can be applied at the rear of the machine to save energy and minimise tension problems. It is of course to be understood that the invention is not intended to be restricted to the details of the above example.

Claims: CLAIMS 1. A method of bonding a backing material layer to a textile substrate layer in the manufacture of carpeting wherein a back surface of the substrate layer is pre-coated, adhesive is applied to one side of the backing material layer and said side is pressed into contact with the said pre-coated back surface thereby to cause the layers to be bonded together, characterised in that said adhesive is applied to said one side of the back^σ material layer by means of apparatus comprising a roller having a perf o. „ted outer wall, the said backing material layer being moved in contact with or in close proximity to the roller, fluent adhesive material being provided in the interior of the perforated roller, and the roller being moved relative to an abutment which is in contact with or in close proximity to the inner surface of the roller so that said adhesive material is displaced through the perforated roller and is deposited therefrom onto the backing material layer in the form of a thin film. 2. A method of bonding a backing material as claimed in claim 1, characterised in that the backing material layer comprises at least one of a woven jute or polypropylene layer. 3. A method of bonding a backing material as claimed in claim 1 or claim 2, characterised in that the adhesive material comprises a fluent latex. 4. A method of bonding a backing material as claimed in claim 1, claim 2 or claim 3, characterised in that the pre-coated material comprises foamed material. 5. A method of bonding a backing material as claimed in claim 4, characterised in that the foamed material comprises a foamed latex material. 6. A method of bonding a backing material as claimed in any preceding claim, characterised in that the pre-coated material is applied with a perforated roller.

Inventors: HALLWORTH GERALD, HALLWORTH, GERALD
Applicants: DOW CHEMICAL CO, THE DOW CHEMICAL COMPANY
Application year: 1991
Main classification: D06N7
IPC codes: A47G27, B05D1, B32B38, D06N7