GB2144079A

GB2144079A - Carpet underlay

Info

Publication number: GB2144079A
Application number: GB08419392A
Authority: GB
Inventors: John Brian Aldridge
Original assignee: BRITISH VITA
Current assignee: BRITISH VITA
Priority date: 1983-07-29
Filing date: 1984-07-30
Publication date: 1985-02-27
Also published as: GB8320525D0; GB2144079B; GB8419392D0

Abstract

The invention provides a low cost underlay which is a good thermal insulator and which comprises a bonded foamed plastics crumb having a protective porous layer bonded to its upper surface and a metal or metallised film bonded to its under surface.

Description

SPECIFICATION Carpet underlay This invention relates to floor covering material and more particularly floor covering material intended to serve as an underlay for a carpet or other surface covering.

With the increasing cost of energy greater attention is being paid to heat losses from buildings. As a result it has been observed that as much as 20% of the heat lost from a building is lost through the floor. This heat loss can be reduced by covering the floor with a carpet and underlay but it is to be observed that the original purpose of such floor coverings was not that of thermal insulation but rather to provide a pleasant surface to walk on. More recently it has been appreciated that floor covering and in particular underlay can be used for thermal insulation.

As a result there are now a number of different kinds of underlay available which are constructed from resilient material usually synthetic plastics or rubber. These known underlays generally provide greater thermal insulation in proportion to increasing thickness but that in turn leads to increased cost.

The present invention has for its object the provision of a carpet underlay which is both cheap and a good thermal insulator.

According to the invention there is provided a carpet underlay comprising a resilient layer having a protective, porous material bonded to the upper surface and a metal or metallised film bonded to the under surface.

The underlay of the invention must essentially be used with the metal or metallised layer lowermost. Quite surprisingly it has been discovered that there is a considerable improvement in thermal insulation with the underlay used in this way as compared with use of the underlay with the metal or metallised layer uppermost. The improved thermal insulation obtained from the underlay of the invention is such that a conventional underlay of considerably greater thickness would be needed to obtain an equivalent effect.

The main body of the underlay is, as stated, of resilient material which is preferably of bonded foamed plastics crumb. The term "Crumb" is used to mean particles of plastics of random shape and size and distribution but generally in the size range 1.0 mm-0.1 mm. The crumb is bonded together with a suitable medium in the form of a sheet. Such reconstituted sheets of foam crumb and methods of making them are well known. In the present invention it is preferred to use an open cell polyurethane crumb but it is to be understood that any plastics crumb can be used. Aithough crumb is preferred any other cellular plastics or rubber material can be used.

The upper surface of the reconstituted crumb layer is preferably protected by a loosely woven layer of, for example, hessian or polypropylene. The woven layer is bonded or held to the reconstituted crumb layer by any suitable means. A convenient way of bonding the woven layer to the reconstituted crumb layer is by applying an adhesive to a thin porous, plastics sheet, for example, of polyether, and then placing the sheet over the woven layer so that it bonds to the woven layer and also bonds to the reconstituted crumb layer through the interstices of the woven layer. The method of bonding can be applied to other kinds of protective layer, for example, a porous non-woven material.

The lower surface of the reconstituted crumb layer is covered by a metal or metallised sheet.

The metal is preferably aluminium. It is preferred to employ a plastics sheet metallised on one side thereof, the other side being bonded to the reconstituted crumb layer, for example by a suitable adhesive.

In the past the use of metal or metallised sheet in floor coverings has not been favoured because of static build up. No such problem has been identified with the present invention.

A carpet underlay of the invention having a reconstituted crumb layer of nominal 8.0 mm thickness was tested in accordance with British Standard 4745. The two plate method was used, in which the material was shielded from ambient.

Test 1-Metallised film to cold plate Test 2-Metallised film to hot plate Test 3-Without metallised film, but with exposed foam facing cold plate Thickness of samples = 0.90 cm.

Test: 1 2 3 Thermal Resistance (TOG) = 2.10 1.97 1.94 Thermal Resistance Km2/W = 0.210 0.197 0.194 The results indicate an increased thermal resistance of 8% when the metallised film is next to the cold surface.

To calculate the effect of insulation on the U-Value (Thermal Transmittance), typical U Value for ground floors are as follows: (1) Ventilated board and joint floor = 1.988 w/m2k (2) Concrete laid on ground = 1.136 w/m2k (3) Concrete laid on ground, with board or woodblock surface = 0.85179 w/m2k Using formula: H = A(t-to) Heat lost in R+dl+d2 watts/hr K1 K2 where k = thermal conductivity d = thickness of material A = area of floor t 8 to = temperatures H = heat lost R = resistance of air film associated with floor N.B. (assume R remains constant for floor surface regardless of material type.

Heat loss values obtained for a 3 m X 4 m area of floor: (1) Concrete floor only for temperature difference of 150C H = 3 x 4 (15 C) R = 0.2072 m2K/W + 0.15M (thickness of concrete) 1.0097 (K value of concrete) H = 180 = 506 WATTS .2072 + 0.1486 (2) Concrete floor + metallised foam underlay H = 12 x15 R = 0.2072 + 0.1486 + 0.210 (value of underlay) H = 180 Heat lost in watts 0.5658 = 318 WATTS (3) Concrete floor + metallised foam underlay + carpet with mean tog value of 2.0 (R = 0.20 km2/w) H H = 180 = 235 WATTS 0.2072 + 0.1486 + .210 + .200 Therefore the quantity of heat saved as a precentage of heat lost through uncovered concrete floor is: : Underlay only % heat loss saving = 37.158 (watts/hr) Underlay + carpet % heat loss saving = 53.55% (watts/hr) A further advantage of the invention is that it tends to prevent the build up of condensation at the interface between the carpet and underlay. The presence of moisture at the said interface is a common phenomenon with some latex underlays. The moisture has the effect of damaging the latex causing it to crumble and stick to the floor. To deal with that it is common practice to cover a floor with an interlay, such as paper. By using the present invention an interlay is not required.

Claims

1. A carpet underlay comprising a resilient layer having a protective porous material bonded to the upper surface and a metal or metallised film bonded to the under surface.

2. A carpet underlay as claimed in Claim 1, wherein the resilient material comprises bonded foamed plastics crumb.

3. A carpet underlay as claimed in Claim 2, wherein the crumb comprises particles of the sizr range 1.0 mm to 0.1 mm.

4. A carpet underlay as claimed in Claim 2 or Claim 3 wherein the crumb is an open cell polyurethane crumb.

5. A carpet underlay as claimed in any preceding claim, wherein the protective porous material is a loosely woven layer.

6. A carpet underlay as claimed in any preceding claim, wherein the protective porous material is bonded to the resilient layer by a thin porous plastic sheet having adhesive applied thereto laid over said protective porous layer so that said sheet bonds to the protective porous layer and to the resilient layer through the interstices of the protective porous layer.

7. A carpet underlay as claimed in any preceding claim, wherein the metal or metallised film comprises aluminium.

8. A carpet underlay substantially as described herein.