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Title:
ACRYLIC-CONTAINING FACING MATERIAL FOR BUILDINGS
Document Type and Number:
WIPO Patent Application WO/1993/007011
Kind Code:
A1
Abstract:
A synthetic facing material for use as a wall-facing material or as a roofing material comprises a mixture of high glass transition temperature acrylic, low glass transition temperature acrylic and filler material. The facing material remains flexible even at a low temperature and has a hard "brick-like" surface.

Inventors:
FITKIN ROSS (SE)
Application Number:
PCT/CA1992/000435
Publication Date:
April 15, 1993
Filing Date:
September 30, 1992
Export Citation:
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Assignee:
EUROTECH TECHNOLOGIES INC (CA)
International Classes:
B44F9/04; C08K3/00; C08K3/34; C08L33/12; E04D1/20; E04F13/18; (IPC1-7): B44F9/04; C08K3/00; E04F13/18
Foreign References:
GB2164340A1986-03-19
Other References:
Derwent Publications Ltd., London, GB; AN 92-196979 & JP,A,4 130 076 (KUBOTA CORP.) 1 May 1992
PATENT ABSTRACTS OF JAPAN 11 May 1985 & JP,A,60 000 865 ( TOA GOSEI KAGAKU KK ) 5 January 1985
PATENT ABSTRACTS OF JAPAN 20 May 1986 & JP,A,60 260 662 ( TOA GOSEI KAGAKU KOGYO KK ) 23 December 1985
PATENT ABSTRACTS OF JAPAN 17 January 1987 & JP,A,61 195 106 ( MITSUI TOATSU CHEM INC ) 29 August 1986
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Claims:
I CLAIM:
1. A facing material comprising (a) a mixture of a high glass transition temperature acrylic and a low glass transition temperature acrylic and (b) filler aggregate.
2. The facing material of claim 1 wherein the high glass transition temperature is greater than about 15°C and the low glass transition temperature is less than about 15°C.
3. The facing material of claim 1 wherein the high glass transition temperature is greater than about 20°C and the low glass transition temperature is less than about 0°C.
4. The facing material of claim 1 wherein the mixture of high and low glass transition temperature acrylics comprises from about 10 to about 90 wt% high glass transition temperature acrylic.
5. The facing material of claim 4 wherein the acrylic mixture contains from about 30 to about 50 wt% high glass transition temperature acrylic.
6. The facing material of claim 4 wherein the acrylic mixture comprises from about 50 to about 80 wt% high glass transition temperature acrylic.
7. The facing material of claim 1 wherein said filler aggregate substantially comprises sand having a diameter up to about 6 mm.
8. The facing material of claim 7 wherein said diameter is up to about 3 mm.
9. The facing material of claim 1 wherein said filler aggregate comprises from about 30 to about 85 wt% of said mixture.
10. The composition of claim 9 wherein said facing material comprises from about 70 to about 80 wt% filler aggregate.
11. A method for preparing a synthetic facing material comprising steps of: (a) mixing at least two acrylic resins, one of said acrylic resins having a glass transition temperature sufficiently high to provide a facing material having an abrasion resistant surface at high ambient temperatures and the second acrylic resin having a glass transition temperature sufficiently low to provide a facing material which remains flexible at low ambient temperatures; (b) combining said mixture of acrylic resins and filler aggregate; and (c) producing facing units from said combined mixture of step (b) and curing same.
12. The mixture of claim 11 wherein a monomeric plasticizer is added to said mixture of acrylic resins prior to step (b) and is substantially removed during said curing process.
13. The method of claim 12 wherein from about 0.1 to about 15 wt% plasticizer is added.
14. A synthetic facing material comprising (a) at least two acrylic resins, one of said acrylic resins having a glass transition temperature sufficiently high and the second having a glass transition temperature sufficiently low to produce a facing material having a minimum bending radius of at least 25 mm, without cracking, at the lowest ambient temperature where the facing material is to be installed and (b) filler aggregate.
15. The facing material of claim 14 wherein the high glass transition temperature is greater than about 15°C and the low glass transition temperature is less than about 15°C.
16. The facing material of claim 14 wherein the high glass transition temperature is greater than about 20°C and the low glass transition temperature is less than about 0°C.
17. The facing material of claim 14 wherein the mixture of acrylic resins comprises from about 10 to about 90 wt% high glass transition temperature acrylic.
18. The facing composition of claim 17 wherein said facing composition comprises from about 30 to about 85 wt% filler.
19. The facing composition of claim 18 wherein said filler aggregate substantially comprises sand having a diameter of up to about 6 mm.
20. The facing material of claim 19 wherein said sand has a diameter of up to about 3 mm.
21. The facing material of claim 20 wherein said facing material comprises from about 70 to about 80 wt% sand.
Description:
ACRYLIC-CONTAINING FACING MATERIAL FOR BUILDINGS

FIELD OF THE INVENTION This invention relates to thin flexible facing material produced in individual units which simulate the required decorative finish. The material may be utilized as a wall-facing material and accordingly simulate brick, stone or the like. Alternately, the facing material may be utilized for roofing simulating tile, shingle or the like. BACKGROUND TO THE INVENTION

A wide variety of wall-facing materials and roofing materials have been available, and in use, for a long time. Efforts have been made to simulate the look and feel of brick, stone and other cementitious or clay based products. Products of this sort have been produced from plastics, asphalt, clay (e.g. sliced brick), and cement. These materials have been specifically designed for either interior or exterior use and have one or more disadvantages.

One disadvantage is that in order to resist cracking, such as may result as a new building settles, the facing material must be thick. For example, bricks are about 4 inches thick and stone varies from 3 to 5 inches thick. A further disadvantage is that rigid materials cannot bend around irregularities which may be found in a substrate or be bent to conform to a contoured substrate effectively. Rigid materials must be specifically manufactured to enable the installer to install these products around various radii. Further, by virtue of the complexity of the application methods, the installation is usually undertaken by skilled tradesmen such as bricklayers, carpenters, siding installers and stone masons. The use of skilled tradesmen significantly increases the construction cost and prohibits the use of such building materials by do-it-yourself installers.

A further disadvantage is that construction costs are in proportion to the volume of raw material used. Thus, thicker facing materials, such as brick or stone, are proportionally more expensive than thinner facings of equal composition. In addition, thinner facings conserve space when used in place of standard bricks which are about 4 inches thick. Thus, the use of a thinner facing material on the construction of an interior or an exterior wall will maximize interior floor space. Further, a thinner facing will minimize the weight of a wall or roof and thus minimize the support structure required to bear such load. In the past, synthetic facing materials have been developed. These materials have various disadvantages. Germany Utility Model No. 78 29 601 disclosed a facing material manufactured from an acrylic resin dispersion compound and a filler comprising quartz sand and mineral foam granulate. German Application No. 30 45 747.7 discloses that the acrylic resin dispersion facing fillets of German Utility Model No. 78 29 601 had problems of elasticity and the allowable bending radius. The German application proposed a synthetic facing material comprising a plastic polymer made from vinyl alcohol esters with low fatty acids, a softener mixture comprising a high boiling phthalate and a lower boiling ether, fillers and granulation material. These materials contain a complex mixture of chemicals. Further, the finished product included volatile components which are undesirable for interior applications. SUMMARY OF THE INVENTION It is an object of the present invention to provide a simplified composition for synthetic facing materials. It is a further object of the present invention to provide a composition which does not contain volatile compounds so that the resultant facing material may be used on exterior or interior use.

It is a further object of the instant invention to provide a facing material which has the "look and feel" of brick. It is also an object of the present invention to provide a synthetic wall-facing material which will not harden and become subject to cracking with age. It is a further object of the instant invention to provide a synthetic wall-facing material which will maintain its flexibility even at low temperatures.

In accordance with the present invention, a facing material comprises (a) a mixture of high glass transition temperature acrylic resin and a low glass transition temperature acrylic resin and (b) aggregate filler. With respect to the former acrylic, the glass transition temperature may be greater than 15°C and preferably is greater than 20°C. With respect to the latter acrylic, the glass transition temperature may be less than 15°C and preferably less than 0°C.

The mixture of acrylic resins may comprise from about 10 to about 90 wt% acrylic resin having a high glass transition temperature. If the facing material is to be used in the construction of a wall-facing material, the acrylic resin mixture preferably comprises from about 30 to about 50 wt% high glass transition temperature acrylic resin and, more preferably, about 40 wt%. If the material is to be utilized in the construction of a roofing material, the facing composition preferably comprises from about 50 to about 80 wt% high glass transition temperature acrylic resin and, more preferably, about 70 wt%.

The filler may comprise any of those known in the art including sand, talc, clay, barites, calcium carbonates, mixed silicates, aluminium hydrate, quartz flours, perlite and recycled organic material such as recycled rubber. The facing material may comprise from about 30 to about 85 wt% aggregate filler. Preferably, the filler essentially comprises sand. The sand may have a particle size up to about 6 mm and preferably, the sand has a particle size up to about

3 mm. The sand may comprise from about 30 to about 85% by weight of the facing composition, preferably from about 70 to about 80%, and more preferably, about 75%.

The facing material may be prepared by: (a) mixing at least two acrylic resins, one of said acrylic resins having a glass transition temperature sufficiently high and the second acrylic resin having a glass transition temperature sufficiently low to provide a facing material having a minimum bending radius of at least 25 mm at low temperatures;

(b) blending said mixture of acrylic resins and filler;

(c) preparing facing units from said mixture of acrylic resins and filler and curing same.

In a further embodiment, a monomeric softener may be added to the mixture to facilitate the preparation of the facing material. Preferably, the softener is added to the mixture of acrylic resins prior to blending said acrylic resins with said filler. The softener is essentially removed and preferably completely removed, from the facing material during the curing process.

A synthetic facing material prepared according to the instant invention retains its flexibility, even at low temperatures, as the facing material ages. Further, the product has a hard exterior surface so that it has the "look and feel" of brick, tile and similar building products. The composition may be easily prepared and is light-weight so that it may be easily lifted in sheet form and installed by a do-it-yourself installer as referred to in copending application filed concurrently herewith.

The substance and advantages of the invention may be more completely and fully understood by means of the following description of the preferred embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The facing material of the instant invention comprises a mixture of at least two acrylic resins and aggregate filler. Acrylic resins may be classified by their glass transition temperature (Tg) . The mixture of acrylic resins comprises at least two acrylic resins, one of the acrylic resins having a glass transition temperature sufficiently high to provide a resultant facing material having an abrasion resistant surface at high temperatures, the second having a glass transition temperature sufficiently low to provide a resultant facing material which remains flexible at low temperatures. Preferably, the facing material has a minimum bending radius of at least 25 mm at low temperatures (such as -15°C) and, more preferably, at least 50 mm at -25°C.

The high glass transition temperature acrylic results in a very hard, weather resistant surface for the facing material. The high glass transition temperature may be greater than at least about 15°C and, preferably, greater than about 20°C. The high glass transition temperature is selected so that, even at the highest ambient temperature where the product is to be installed, the facing material will have a hard exterior surface. The low glass transition temperature acrylic provides the flexibility to the facing material. The low glass transition temperature is selected so that the facing material will remain flexible in use. Accordingly, the low glass transition temperature is selected so that the facing material will remain flexible, without cracking, at the lowest ambient temperature where the product is to be installed. The low glass transition temperature may be less than about 15°C and, preferably, less than about 0°C.

It has surprisingly been found that when a high glass transition temperature acrylic and a low glass transition temperature acrylic are mixed in the composition of the instant invention, that the resulting

facing material displays the properties of both the high glass transition temperature acrylic and the low glass transition temperature acrylic. The fact that each of the high glass transition temperature acrylic and the low glass transition temperature acrylic do not counteract the properties of the other acrylic results in a facing material having a hard, weather resistant surface which has a "brick-like" feel while maintaining the flexibility required for the installation and durability of the facing material.

Preferably, the acrylic is a polymethyl methacrylate. However, other polyacrylic esters may be utilized. The acrylic may be self-crosslinking in composition or a crosslinking agent, such as zinc oxide or glyoxal, may be added. Preferably, the amount of crosslinking agent is sufficient to fully crosslink the polymers so as to obtain maximum weatherability characteristics.

The mixture of acrylics may comprise from about 10 to about 90 wt% high glass transition temperature acrylic. If the facing material is to be used as a wall- facing material, the acrylic mixture preferably comprises from about 30 to about 50 wt%, and more preferably, about 40 wt% high glass transition temperature acrylic. If the facing material is to be used as a roofing material, then the acrylic mixture preferably comprises from about 50 to about 80 wt%, and more preferably, about 70 wt% high glass transition temperature acrylic.

The aggregate filler may be any of those known in the art. Talc, clay, barites, calcium carbonates, mixed silicates, aluminium hydrate, sands, quartz flours and perlite may be used as filler. Further, recycled rubber may also be incorporated in the facing material. This provides an economic way to utilize waste rubber products. Preferably, the filler substantially comprises sand which may have a diameter up to about 6 mm and, preferably, up to about 3 mm. The facing material may

comprise from about 30 to about 85, more preferably from about 70 to about 80 and, most preferably, about 75 wt% filler.

While the facing material may be fabricated with any desired thickness, it has been found that a thickness of from about 3 to about 10 mm is preferred to achieve a balance of economy, flexibility and aesthetics. Preferably, the thickness is about 5 mm. The production of a thin facing material allows these materials to be used in conjunction with exterior insulation finishing systems. The product is light-weight having a weight of about 1.5 lbs/ft 2 compared to conventional sliced brick facing which weighs about 6 lbs/ft 2 . The facing material is sufficiently thick that, when shaped in the form of brick or stone, the facing material may be pointed to produce a wall which has the appearance of a brick wall.

The facing material is prepared by mixing the acrylic resins. Subsequently, the acrylic resins and aggregate filler are combined together. This combined mixture is then placed into a mould or extruded into a continuous sheet or a plurality of facing units and cured. During manufacturing, a plasticizer may be added to the mixture to facilitate processing. The plasticizer is substantially evaporated during the curing process so as to produce a product which is essentially free of, and preferably effectively free of, plasticizer. From about 0.1 to about 15%, more preferably from about 0.5 to about 5 and, most preferably, about 1% plasticizer may be added. The plasticizer may be any of those known in the art. Examples of suitable monomeric plasticizers are texanol and butyl carbitol acetate.

Standard modifying additives may be incorporated into the compound for manufacturing purposes and specific properties in the finished facing units. These additives may include defoamers, wetting agents, rheology modifiers, mildewcides and biocides.

As will be appreciated by those skilled in th art, the facing material may be prepared in any desire shape and texture. The facing composition is relativel viscous prior to curing and may be given any desired texture by brushing, rolling, embossing or similar techniques. Thickeners may be added to the mixture to further enhance the ability of the compound to be textured. Colouring can be accomplished through the addition of standard pigments in powder or liquid form. The use of liquid pigments is advantageous as it easily creates colour variations in each facing unit so as to enhance the similarity of the facing material to actual brick or stone. A number of other techniques to produce colour variations which may be utilized include the addition of a different colour base composition on top of the facing material in the final stages of moulding or extrusion, spraying the cured facing material with a weatherable coating, such as enamel or lacquer, and the use of rubber granules as a portion of the filler resulting in blue/black streaking.

The facing material prepared according to the instant invention has good weather resistance and maintains its flexibility, even at low temperatures. Facing material produced from a 40:60 high Tg:low Tg acrylic mixture, under accelerated weathering for 1500 hours has shown no detrimental effect on the combined properties of the two acrylics. Further, after cooling the facing material down to -15°C, the facing material has retained its flexibility and maintained a bending radius of 50 mm without cracking.

EXAMPLE 1

A facing material was prepared from the following materials:

Component Acronal DS 6041

Acronal 296 D

Lumiten EL

Texanol

Glyoxal Nopcocide N-96

Pigment

Sand .

The mixture was prepared by first mixing the acrylics, the antifoaming agent and the coalescent (softener). This mixture was placed in a mortar mixer. The crosslinking agent and the mildewcide were then added to the mixer together with pigment. The mixture was then mixed at about 100 rpin for about 5 minutes to ensure thorough blending of the ingredients. The sand was then slowly added to the mixer as it was running. After all the sand was added, mixing continued for about 10-15 minutes, until the mixture had a smooth consistency. The material was then poured into moulds of the desired shape. The moulds were removed and the facing units were cured for at least 3 days at about 30°C and low humidity.

After curing, the individual facing units had good permanent flexibility. The units had a minimum bending radius of 25 mm at -15°C. The product had excellent water resistance and crack bridging potential The units display good cold temperature flexibility and excellent abrasion resistance. The facing material contains no temperature sensitive (volatile) ingredients and is cost effectively used as a siding material, even on affordable housing projects.

In addition, the facing units were exposed to accelerated weathering by treatment for 1,500 hours in a QUV accelerated weatherometer. After treatment, the facing units showed only slight colour fading. EXAMPLE 2

A roofing material was prepared from the following materials according to the steps used in Example 1:

.

The material was less flexible than that produced in Example 1. Otherwise, the materials prepared in Examples 1 and 2 had properties which were similar.