GB2107371A

GB2107371A - Bonded fibrous bodies

Info

Publication number: GB2107371A
Application number: GB08228397A
Authority: GB
Inventors: Erling Olsen
Original assignee: Rockwool International AS
Current assignee: Rockwool AS
Priority date: 1981-10-07
Filing date: 1982-10-05
Publication date: 1983-04-27
Also published as: FI823384A0; DE3236750A1; FR2514043A1; SE8205702D0; FI823384L; DK443481A; BE894626A; NO823298L; LU84411A1; GB2107371B; SE8205702L; CH659271A5; FR2514043B1; NL8203873A

Abstract

A porous body comprises fibres 1 bonded by a cured bonding agent 2. The fibres may be of mineral wool and the body may be a tile or slab suitable for outside insulation or facing of houses. After curing the bonding agent 2 a liquid binder composition containing a solvent is applied and initially saturates the interspaces 3 but is then dried to form a film 4 along the fibres leaving open pores 3 between the fibres. As a result the surface of the body is hard and strong even though the body remains porous and permeable to water vapour. <IMAGE>

Description

SPECIFICATION Bonded fibrous bodies The invention relates to surface reinforcement of porous tiles or other bodies, for example slabs or tiles of mineral wool.

It is known, from for instance Danish patent specification No. 97.863, to reinforce tiles of mineral wool with fibres made from glass, rock or slag, by applying a solution of a plastic binder. The used type of binders, however, tend to fill out the interspaces between the fibres in the porous tiles making the tiles moisture- and air-impermeable. The insulationand sound-absorption-properties of such tiles are thereby considerably reduced. The filling-out of the pores is adverse when the porous tiles are used as an outer facing for walls and roofs as such tiles must at least be open to diffusion of moisture.

The object of the present invention is to avoid the above drawbacks.

In the invention a surface reinforcement of porous bodies or tiles comprising fibres and a cured bonding agent, for example mineral fibres and a cured phenolic resin, and forming to some extent an elastic lattice with through-going interspaces between the fibres is characterised in that a binding composition is introduced into a surface layer of the porous body, the composition containing a solvent which is then evaporated to form a film of the binder on the individual fibres or bundles of fibres and their intersections in the porous body in such a way that the interspaces are open and through-going.

In particular, a method according to the invention of improving the properties of a porous body comprising fibres or fibre bundles that are bonded together by a cured bonding agent and that are separated by interconnecting spaces and that form a partially elastic structure comprises coating the fibres with binder without substantially blocking the interconnecting spaces by applying to the body a liquid composition containing binder and volatile solvent and then evaporating the solvent.

Although the invention can be applied to various fibre structures, such as products formed from cellulose fibres or from wood wool, the invention is of particular value when the fibres are mineral fibres and in particular when they are rock or slag wool fibres. The body is preferably a mineral wool article which may be a slab or tile. The invention is of particular value when the body is a mineral wool tile.

The mineral wool tile or other body to which the binder is applied may have been made by conventional methods and will comprise the fibres, or fibre bundles, bonded together by a cured binding agent, generally a cured phenolic resin. This bonded product can be regarded as having a partially elastic lattice structure but of course the structure can be wholly elastic. The amount of cured bonding agent is such that there are interconnecting spaces and the bonding agent is concentrated primarily at the intersections of the fibres or fibre bundles.

A porous body according to the invention comprises fibres, or fibre bundles, bonded by cured bonding agent and in this body the fibres, at least in the surface layer of the body, are also coated with a film of binder and there are interconnecting spaces through the body.

The reinforced porous bodies according to the invention are suitable as combined outer facing and insulation of houses. Such facings must have a hard surface, be permeable to diffusion of moisture, in combination with a good resistance to impacts and good tensile strength. Further, the bodies should be economical in manufacture and in mounting. The bodies according to the invention possess these qualities being mountable on existing facings by means of a cement or by mechanical means. One of their surfaces is hard and needs no further finishing.

If, however, another colour or surface structure is required, the hard surface is well suited for application of such finishes without special precautions as the surface of the bodies is suited for the application of current wall-paints or plastering.

An outside facing and insulation may be mounted with the bodies according to the invention for approximately half the price of a traditional outside insulation, for example as described in the specification to European Patent No. 17.969. Further, the weight of the facing according to the invention will be substantially less than the known facing systems.

The invention will be described with reference to the drawing.

Figure 1 shows schematically fibres with a bonding agent without the binding composition, Figure 2 shows the fibres according to Figure 1 with the solution of binding agent, and Figure 3 shows the same fibres after drying of the composition.

The drawings show the fibres in one plane, but the fibres are in fact placed in a 3-dimensional lattice.

Figure 1 shows schematically and enlarged some fibres 1 in a section of a porous mineral wool tile.

The fibres are bonded together at their intersections 2 by means of a bonding agent, for example a cured phenolic resin, interspaces 3 being formed between the fibres.

In Figure 2 the same section is shown as in Figure 1, but a liquid solution or emulsion of a binding composition has been applied as indicated with dots. The liquid composition fills out the interspaces 3. The liquid binder contains a volatile solvent. This evaporates from the binding composition and the composition shrinks around the fibres 1, as shown schematically in Figure 3. The composition forms a continuous film 4 on the fibres leaving the interspaces 3 open and through-going, whereby the mineral wool tile becomes permeable to watervapour and air. The physical drying step results in a big reduction in volume.

The dried binding composition 4 is present as a film that reinforces the fibres preventing binding and fracture of the fibres. Also the intersections are made stronger, thereby increasing the tensile strength.

The compressive and the tensile strength and the stiffness are increased and there is a hardening of the surface without substantially changing the porosity.

Some of the fibres may be placed in close relationship in so-called fibre bundles. The binding composition will then enclose the fibre bundles.

The liquid composition applied to the porous tile may comprise an emulsion or a solution of a binder.

The binder may for example be latex, polyvinylacetate, polyvinylchloride/vinylether or copolymerisates, for example of styrene/butadiene or vinyltoluene/acrylester. Latex is preferred. The binder may be dissolved or emulsified in a solvent such as an aromatic solvent, an alifate, an ester or a ketone.

Suitable aromatic solvents are xylene and toluene.

To the binding composition several substances may be added to improve the properties of the reinforced product. These substances may be pigments, fire-retarding agents or plasticisers. If chlorinated paraffins are used as a plasticiser, cracking during the drying is minimised.

The liquid binding composition may be applied by means of conventional varnishing equipment or by dipping in a container with liquid binding composition. Depending on the amount of solvent in the composition, the speed and depth of penetration and porosity may be controlled. The liquid binder may penetrate throughout the thickness of the tile if desired. The binder may contain nearly 100 per cent volatile solvent.

The reinforced mineral wool tile may be produced from mineral wool slabs of different thicknesses or densities and may be used for other purposes than the one mentioned above.

In outsidefacingsforhouses normally an application of binding composition of 5 litres per sq. metre is sufficient corresponding to a penetration depth of 10 mm.

Claims

1. A porous body comprising fibres, or fibre bundles, bonded by a cured bonding agent and in which the fibres, at least in the surface layer of the body, are also coated with a film of binder and in which there are interconnecting spaces through the body.

2. A porous body according to claim 1 in the form of a bonded slab or tile of mineral wool in which the fibres in the surface layer at least are also coated with the film of the binder.

3. A method of improving the properties of a porous body comprising fibres orfibre bundles that are bonded together by a cured bonding agent and that are separated by interconnecting spaces and that form a partially elastic lattice, the method comprising coating the fibres, in the surface layer at least of the body, with a binder without substantially blocking the interconnecting spaces by applying to the body a liquid composition containing binder and volatile solvent and then evaporating the solvent.

4. A method according to claim 3 in which the liquid composition comprises latex.

5. A method according to claim 3 or claim 4 in which the solvent is an aromatic solvent.

6. A method according to any of claims 3 to 5 in which the porous body is a slab or tile of mineral wool.

7. A method according to claim 6 in which the cured binding agent is a cured phenolic resin.

8. A method according to claim 3 substantially as herein described with reference to any of the accompanying drawings.