Bonded inorganic and fibrous material building product

A building product comprises a mineral filler and glass fiber bonded together by a polyester resin. A film or layer of a weather resistant fluoroplastic material is attached to a face of the building product by pressing the film or layer into contact with the face during curing of the resin in a mold. A method of manufacturing a building product as above is also described.

BACKGROUND OF THE INVENTION 
The invention relates to building products and more particularly to 
building products of the kind comprising an inorganic material and a 
fibrous material bonded together by a resin. 
One of the problems with such materials is that they may be subject to 
attack by the weather and as a result may suffer loss of some of their 
properties such as color, surface finish, etc. 
SUMMARY OF THE INVENTION 
It is an object of the invention to avoid or reduce this loss of property. 
Accordingly the invention provides a building product of the kind described 
having on one face a film or layer of a weather resistant fluoroplastic 
material which film or layer has been attached to the product by pressing 
the film or layer into contact with the product during the curing of the 
resin. 
Preferably the fluoroplastic material is polyvinylidenefluoride or 
polyvinylfluoride or a fluorohalocarbon. 
The plastic material may be one that has one side treated for adherability 
and the other side treated to be readily releasable from a mold. 
Preferably the product contains as a homogeneous mixture by weight from 12% 
to 30% polyester resin, from 2% to 15% glass fiber and from 62% to 86% of 
a finely divided mineral filler. 
The invention further provides a method of manufacturing a building product 
which comprises pressing a film or a sheet of a weather resistant 
fluoroplastic material onto a face of a building material of the kind 
described during curing of the resin in a mold.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The material is basically manufactured according to our earlier United 
States patent specifications Nos. 3,670,063 and 3,853,442 the disclosure 
of which is hereby referred to. Hence the material is constituted by a 
mineral filler, a polyester resin and glass fibers. By making use of the 
present invention the ranges of the three constituents may be as follows: 
Finely divided mineral filler 62% to 82% by weight. 
Resin 12% to 32% by weight. 
Glass fibers 2% to 15% by weight. 
A film of fluoroplastic material is then attached to the building material. 
The film may be of polyvinylfluoride, polyvinylidenefluoride, or of one of 
the flurohalocarbons FEP, ETFE and E-CTPE but is preferably the 
polyvinylfluoride sold by Dupont under the Trade Name TEDLAR. The film is 
provided with one side treated for adherability and the other side heat 
sealable or releasable. 
The film can be attached in either of two ways. 
A sheet of the film can be introduced into the mold in which the uncured 
material manufactured according to patent No. 3,853,442 is to be 
introduced. The curing then takes place using heat and pressure and during 
this time the film, which has its adhesive side towards the material, 
adheres to the material. 
Alternatively the film may replace one or both of the films on the feed 
rolls 13 and 18 shown in FIG. 5 of patent No. 3,853,442. The film is thus 
rolled together with the material and then the film and the material are 
cured together in a mold as before. 
It has been found that the building material coated with the film has 
increased weather resistance.