GB2165447A - Upholstery component - Google Patents

Abstract

An upholstery component for furniture and bedding which meets the requirements of B.S. 5852 Part 1 consists of a core around which is wrapped a flexible sheet of material that has been coated or impregnated with a flame retardant composition. A fabric cover is disposed over the flexible sheet, and the flame retardant composition upon being heated, gives off a gas so as to extinguish or inhibit combustion of the fabric cover. Thicknesses for the flexible sheet are disclosed.

Description

SPECIFICATION Upholstery Component This invention relates to an upholstery component and to the treatment of materials to increase the flame retardancy of such a component for use in furniture, mattresses and automotive seating and upholstery in general.

With the increasing use of synthetic materials in upholstered furniture and bedding there is a corresponding increase in the attention being paid to the flammability aspects of such furniture. There are two separate problems. Both the major components of furniture and bedding, namely the cover and filling material, have inherent deficiencies in their flammability behaviour.

The first problem concerns the upholstery cover material be it fabric or some other cover material. Most outer covers used either melt and expose the filling material to the ignition source or they themselves ignite and permit flame spread by propagating combustion themselves and igniting the upholstery filling as a consequence.

The second problem arises from the upholstery or bedding filling material be it polyurethane, latex foam rubber or rubberised coir fibre or some other material that will support and propagate combustion once ignited.

The most widely used upholstery filling material is polyurethane foam which is very economical in use and provides excellent comfort and upholstery seating properties in furniture and in bedding. However, it is relatively easy to ignite by a naked flame.

The flammability behaviour is, therefore, a composite one involving the upholstery filling material and also the upholstery cover material, the behaviour of each component contributing to the flammability behaviour of each composite construction.

In the United Kingdom, Furniture (Safety) Regulations were introduced in 1980 which require by31st December, 1982, all furniture to resist ignition by a smouldering cigarette when tested in accordance with BS 5852 Part 1. Soon it is expected that resistance to ignition by a match will be required (a butane gas flame is used of the same calorific value) when tested to the same British Standard test method.

Many current furniture filling cover combinations fail the cigarette test and also the butane gas test.

In the case of the cigarette test the requirements are that all smouldering, smoking or flaming must have ceased two minutes after the cigarette has gone out. Also the test is allowed to carry on for 60 minutes after placing the cigarette on the composite materials arranged on the test rig, and there must still be no smouldering,smoking or flaming afterthe60 minute period.

In the case of the butane gas test, the butane gas flame is applied for 20 seconds and there must be no smoking, smouldering or flaming two minutes after removal of the gas flame.

Several attempts have been made to deal with the problem of outer cover behaviour and failure to comply with the requirements of the 1980 Furnitur (Safety) Regulations. One technique which has been tried involves the treatment of the reverse side of the cover fabric to make it flame retardant, for example the application to the fabric of a PVC latex foam or laminate of a preformed PVC foam made such that the foam is adhered to the fabric. A PVC non-foam treatment has also been used. One disadvantage of such treatments to the fabrics is to impart unacceptable handle and feel to the fabric and reduced acceptancy by the consumer. Another disadvantage is the problem of handling and utilising fabrics by the furniture manufacturer. Fabric rolls so treated are bulkier and heavier so that for ease of handling the roli length may need to be reduced.

Another technique which has been tried has been to apply a flame retardant treatment to the upholstery filling material such as polyurethane foam. The disadvantage of this method is the problem of handling large numbers of cut foam pieces all of which require for example spraying or brushing with a flame retardant composition. If the flame retardant composition is water based then each treated part requires drying and/or curing. If the flame retardant composition is solvent based the same may apply.

Drying and/or curing is very costly and places a considerable restriction on the speed with which large numbers of treated upholstery fillings can be produced. In addition the degree of assurance that sufficient flame retardant composition has been applied in order to comply with the flammability requirements may be unacceptable. This technique would also be costly requiring drying and/or curing equipment to be installed by the upholstery fabricators and/or furniture or mattress manufacturer.

It is an object of the present invention to overcome the above disadvantage such that the normal fabrics currently used can continue to be used by the furniture manufacturer without the application of any flame retardant treatment to the fabric and without the application of any flame retardant treatment to the individual cut shapes of filling material such as polyurethane form with subsequent lengthy drying and/or curing processes.

According to the present invention there is provided an upholstery component for furniture, bedding and the like comprising a core or filling, a sheet of flexible wrapping material wrapped around at least a part of said core or filling and a fabric cover over said sheet of flexible material, said sheet of flexible wrapping material having been treated prior to assembly in the component with a flame retardant composition adapted upon heating to give off a gas so as to extinguish or inhibit combustion of said fabric cover.

The present invention may be concerned with the impregnation of materials already generally used in the construction of furniture and bedding such that normal fabrication methods can be continued to be used by the foam converter and the furniture and bedding manufacturer.

The invention provides substantial indirect protection to the outer cover in contrast to currently known practices for protecting the upholstery filling material.

Materials which can be used as the sheet of flexible wrapping material include foams such as polyurethane foam polyester foam, fabrics and fibres. After treatment with a flame retardant they can be supplied to the converter or furniture or mattress manufacturer ready for use in the normal way for fabricating, for example, seats, chair backs, arm rests, head rests, mattress cores and so on. The core or filling may be the same or different material to the flexible sheet. For example many cushions are wrapped with a layer of polyurethane foam which may have a thickness of about 25 mm and of different characteristics to the main foam filling material in order to provide the comfort properties required by the upholstery designer in the final upholstered furniture.

The flexible sheet material may be impregmated with the flame retardant composition either fully or partially or on the surface only. It is known that foams can be partially or wholly impregnated with a flame retardant material which offers flame retardancy protection to the upholstery core filling material such as polyurethane foam for example. No protection, however, is offered to the cover. In contrast the present invention indirectly protects the outer cover. In the case of thick wrappings only a surface treatment or impregnation for a few millimetres is generally required. In the case of thin wrapping the whole thickness may be impregnated so that the impregnated wrapping possesses the desired characteristics required by the upholstery designers.The resultant product surface treated or partially or wholly impregnated with a suitable flame retardant material can then be supplied to the upholstery converter or the furniture or mattress manufacturer who can then use the product in the normal way with no changes being made to their standard methods. Since the wrap is pre-made, the problems of applying the flame retardant material followed by drying and/or curing by the converter or furniture or bedding manufacturer are eliminated.

It is also current practice for foam cushions, backrests and the like to have a core or filling, for example, of polyurethane foam encased in a knitted stockinette to ease the insertion of the foam filling into the outer fabric cover. Sometimes the polyurethane foam is first wrapped with a fibre batting for example of polyester or acrylic or some other suitable fibre and the knitted stockinette is then applied over the fibre wrapping. It is preferable that the stockinette possesses a four way stretch. Treatment of the stockinette fabric with a suitable flame retardant treatment results in no changes having to be made by the converter or furniture manufacturer to their methods and processes since the stockinette is supplied ready for use.

It is well known that fabrics are treated with a flame retardant material to protect the foam core but yet offer no protection to the outer cover, e.g. "PROBAN" (Registered Trade Mark) treated cotton woven fabric specified by the DOE/PSA. The use of a stretch stockinette fabric treated in accordance with the invention provides protection for the outer cover.

Fibre as described above can be used as a wrapping without stockinette. The fibre wrapping may comprise a twin layer consisting of for example acrylic or polyester fibre with an upper or outer facing fibre layer of inherently flame retardant fibre such as "CORDILAN", the surface of the latter being treated for example by spraying with a suitable flame retardant material. The resultantfibrewrapping can be used in the normal way by the converter or upholstery furniture manufacturer.

As in the case of foam and fabric wrapping, the treatment to the fibre gives protection to the outer cover from ignition by flame ignition sources such as butane gas flames.

All the above described wrappings which are currently used in an untreated form by the converter or the furniture manufacturer can be supplied in a treated form and used in the same way as the untreated materials by the user.

The use of the treated wrapping materials enables the 1980 Furniture (Safety) Regulations to be complied with for furniture constructed using the treated versions of already used materials. Approximately 60% of currently produced upholstery filling materials are catered for by this method. Other wrapping materials as well as those specifically mentioned herein can be used in the invention.

The thickness of the wrapping is not restricted to any particular value. The thickness is selected to achieve the desired comfort level. Likewise the choice of the core or filling is not restricted to polyurethane foam and may be a material of any desired density and hardness selected at the discretion of the upholsterer to meet his requirements. The depth of penetration of the impregnant may also vary for example between the thickness of a sprayed on layer to total impregnation. Where the wrapping is that, for example, above 6 to 15 mm coating partial impregnation may be adequate. Thinner wrappings, for example from 1.5 to 12 mm, preferably from 3 to 6 mm, may be completey impregnated. The impregnant mixture is chosen so as to meet the test requirements for protecting the cover fabric without impairing the performance of the upholstery component. That is to say its comfort, softness, resilience and soon.

The wrapping can be used loose or preferably adhered to the upholstery filling material. The extent of treatment of the wrapping will also depend on the nature of the outer cover used in the manufacture of the furniture. Usually 20 to 750 g/m2 dry deposit is required to obtain compliance to the Regulations in accordance with the BS 5852 Part 1 test method.

The invention will now be further described in the following examples involving treatment to currently used materials to protect the outer cover material without the need to apply any treatment to currently used cover fabrics which consequently continue to be used unaltered.

EXAMPLE 1 A 25 mm thick flexible polyurethane foam in sheet form of 30 kg/m3 density and 7-10 kg hardness by the BS 3667 test method was impregnated to a depth of 2 mm using a specially formulated flame retardant latex mixture of the following composition: Total Amount Amount Ingredient Solids % (PBW-Dry) (PBW-Wet) 1. Polydene 33/004 50 100 200 2. Timinox 66 10 15.2 3 Methocel (Regd. Trade Mark) J20 MS 100 0.5 0.5 4. Ammonia - - 0.6 The mixture was sprayed onto the surface of the polyurethane foam and a roller was used to cause the latex to penetrate the foam. The latex mix was applied to one side of the polyurethane foam only. The weight applied was 250 gm/m2. The treated foam was passed through an oven at 80"C to effect drying.

Curing may be employed in the alternative case of the use of a self-reactive PVdc flame retardant composition. The partially impregnated polyurethane foam in sheet or roll form was allowed to cool on emerging from the oven. Other methods of treatment may be used such as foaming, roller coating, brushing, etc.

A seat cushion and backrest were constructed by cutting standard flexible polyurethane foam to size and wrapping with partially impregnated polyurethane foam using the standard methods involving normally used adhesives to adhere the wrapping to the foam core. The dimensions of the seat and back cushion were as required by the test method BS 5852 Part 1.

A flat woven propylene cover fabric of weight 460 gm/m2 was used to cover the thus prepared upholstery foam core and the test conducted using a butane gas flame (same calorific value as a match) as ignition source according to BS 5852 Part 1 test method.

An identical construction was prepared except that the 25 mm wrap was untreated.

The burn test results were as follows; Note; in the case of the partially impregnated wrapping the treated side was positioned so that it came in contact with the upholstery fabric cover material.

Time Untreated Wrap Treated Wrap 0 butane gas flame applied butane gas flame applied 20 sec butane gas flame removed butane gas flame removed 65 sec fabric melted away foam ignited char barrier formed on foam fabric melted but did not ignite 90 sec foam ignited. Cover continuing to no smoke no flame no smouldering melt and spread flame. Full conflagration in progress.

The test results clearly show that as expected the untreated polyurethane foam wrap fails to protect cover fabric from ignition and surface spread of flame and a fail result has to be recorded. In contrast the partially impregnated polyurethane foam wrapping successfully complies with the test requirements and provides resistance to ignition and surface spread of flame of the cover fabric.

EXAMPLE 2 A 4 mm thick polyurethane foam sheet of density 15 kg/m3 was soaked in the flame retardant mixture as described in Example 1 to give a 330 g/m2 treatment level and used as an interliner between the polyurethane foam filling material and the outer cover which was a standard acrylic fabric cover of weight 355 g/m2 used in this example.

On testing the composite to BS 5852 using the butane gas ignition source applied for 20 seconds a pass result was obtained since no smouldering, smoking or flaming was apparent 2 minutes after removing the butane gas flame. An identical construction made without the presence of the interliner burnt out to destruction and failed the test requirements.

EXAMPLE 3 A sample of lightweight knitted cotton (stockinette) with fourway stretch properties was impregnated with the flame retardant mix depicted in Example 1 and dried to a final dry weight of 180 g in an oven at 135"C. The impregnated stockinette was used to cover a conventional polyurethane foam upholstery filling material and the outer cover was an acrylic pile cover fabric as used in Example 2.

On testing to BS 5852 Part 1 using the butane gas ignition source described therein there was no flaming, smouldering or smoking 2 minutes after removing the ignition source such that the test requirements of the Furniture (Safety) Regulations were complied with.

An identical construction using non-flame retardant untreated stockinette the composite construction burned to completion thus failing the test.

The use of the treated stockinette gave protection to the outer cover used in this example and resisted ignition from the butane gas flame.

EXAMPLE 4 A spray application of the mix depicted in Example 1 was applied to the surface of the fibre wadding of a fibre wrap material at a coverage rate of 250 g/m2.

On testing a composite construction of standard polyurethane foam upholstery core material, fibre wrap as prepared above and outer cover of acrylic pile on cotton base as used in Example 2, a pass result was obtained to BS 5852 Part 1 using the butane gas ignition source. The outer fabric did not continue to burn 2 minutes after removing the butane gas ignition source.

Without the application of the flame retardant spray material the outer cover continued to burn and spread flame but the foam core was protected by the presence of the CORDILAN fabric. A fail result had to be recorded.

Claims (14)

1. An upholstery component for furniture, bedding and the like comprising a core or filling, a sheet of flexible wrapping material having a thickness less than 25 mm and a fabric cover over said sheet of flexible material, said sheet of flexible material having been treated prior to assembly in the component with a flame retardant composition adapted upon heating to give off a gas so as to extinguish or inhibit combustion of said fabric cover.

2. An upholstery component as claimed in Claim 1, wherein the sheet of flexible material has a thickness of 6 mmto 15 mm.

3. An upholstery component as claimed in Claim 1, wherein the sheet of flexible material has a thickness of 1.5 mm to 12 mm.

4. An upholstery component as claimed in Claim 3, wherein the sheet of flexible material has a thickness of 3 mm to 6 mm.

5. An upholstery component as claimed in any preceding Claim, wherein the sheet of flexible material is made of foam material.

6. An upholstery component as claimed in Claim 5, wherein the foam material is a polyurethane or polyester.

7. An upholstery component as claimed in any of Claims 1 to 5, wherein the sheet of flexible material is made of fabric or fibres.

8. An upholstery component as claimed in any preceding Claim, wherein the core is made of the same material as the sheet.

9. An upholstery component as claimed in any of Claims 1 to 7, wherein the core is made of a different material to the flexible sheet.

10 An upholstery component as claimed in Claim 3 or 4, wherein the flexible sheet is fully impregnated with the flame retardant composition.

11. An upholstery component as claimed in any of Claims 1 to 9, wherein the flexible sheet is partially impregnated with the flame retardant composition.

12. An upholstery component as claimed in any of Claims 1 to 9, wherein the surface of the sheet of flexible material is coated with the flame retardant composition.

13. An upholstery component as claimed in any preceding claim, wherein the flexible sheet is caused to adhere to the core.

14. An upholstery component substantially as hereinbefore described with reference to any of the accompanying Examples.