WO2013080025A1

WO2013080025A1 - Building composite panel and manufacturing method thereof

Info

Publication number: WO2013080025A1
Application number: PCT/IB2012/002555
Authority: WO
Inventors: Andrea FONTANA DONATELLI
Original assignee: E-Comfort S.A.S. Di Fontana Donatelli Andrea & C.
Priority date: 2011-12-01
Filing date: 2012-11-26
Publication date: 2013-06-06
Also published as: ITMI20112197A1; WO2013080025A4

Abstract

A building composite panel is disclosed, adapted to be supported by a fixed structure and manufactured entirely by a cold operation, comprising an inner core of mineralized wood fibers, a first coating formed by a first fluid composition comprising a solution of crude clay in water, adapted to impregnate said mineralized wood fibers and naturally dried, and a second outer coating formed by a second thick composition comprising a mixture of binders and clay in water and again undergoing a natural drying operation. A method of manufacturing such a panel is also disclosed.

Description

BUILDING COMPOSITE PANEL AND MANUFACTURI G METHOD THEREOF

The present invention relates to a building composite panel to be used in structural elements such as partitions, inside walls, curtain walls of outside main walls, false ceilings, floor components and the like, said panel being constituded by the unique combination of mineralized wood fibers, crude clay and binders, conferring to the panel excellent structural characteristics superior to panels available on the market.

Panels of this kind presently available on the market and comprising compositions based on clay, which is however present only in small amounts, show the peculiar advantages of this material but at the same time suffer from its disadvantages, more particularly the poor mechanical strength .

Document JP-A-2001/026475 discloses a concrete panel, in which a panel of mineralized wood fibers is inserted, provided only for increasing its soundproofing properties. The possible use of several materials, such as clays among others, is disclosed, but only if required for manufacture lightening, indicating neither the quantity nor the manufacturing process. Calcium silicate contained in the concrete is used neither as clay binder nor as a coating, which on the contrary comprises the two concrete outer layers .

Document US-A-3549485 discloses a method of manufacturing a building rigid panel, comprising mineral fibers impregnated with clay casting and coated with carbonates. Mineral fibers have considerable differences in respect of wood fibers, as discussed hereinafter, are used in loose form and impregnated with clay, require compression to be transformed into a rigid panel and after an outer coating with carbonates, they must be baked at a high temperature, that clearly causes irreversible modifications of the characteristics of clay losing most of its advantageous properties .

On the contrary the panel of the present invention maintains or even enhances the characteristics arising from the presence of clay in its structure and at the same time overcomes the disadvantages of poor mechanical strength by adopting an inner core mainly comprising mineralized wood fibers, adapted to confer the desired mechanical strength.

The presence of said inner core of mineralized wood fibers according to the present invention, allows to attain high standards of final mechanical strength of said panel, which is expressed by its use like a traditional brick wall, conferring high resistance to impacts and tears and without incurring the risk of structural settlement, that on the contrary is typical of similar panels available on the market, where clay moreover is contained in clearly lower quantities. Such an inner core of the panel may be selected among those already available on the market, used in the building field and comprising mineralized wood fibers.

As it is known to the persons skilled in this art, wood fibers are milled and ground through mechanical treatments: thereafter the fibers are impregnated with several materials such as magnesite, cement or other materials causing mineralization, so as to confer to the fibers a strong cohesion and structural compactedness . In the magnesite adopting process, the panel pressure forming allows mineralization through absorption of mineral by the fibers. In the cement adopting process, preferably with Portland cement, the panel material is poured in molds and seasoned; in this case mineralization occurs by binder absorption. In both processes a panel drying stage follows the absorption stage .

The presence of a high amount of clay as main ingredient of the compositions impregnating and then coating sais core, warrants high standards of dwelling comfort, as it will be better explained hereinafter in accordance with the present invention .

To the specific characteristics of the building panel of the present invention, the intrinsic properties not only of clay but also of the mineralized wood fibers are added in a synergic and enhanced way, such as acoustic insulation and deadening of the internal rooms, hygroscopicity due to the clay high power of regulating the environment humidity, thermic inertia given by the high mass and the thermal capacity values of the used materials, the fire resistance of the materials which are classified as fireproofing according to the European regulations, the protection from electromagnetic fields to be ascribed to the mineralogical structure that not only is not emitting radiations, but contributes also to protect from external electromagnetic fields, the antistatic characteristics preventing formation of electrostatic charges and finally the lack of dependence from disgregating phenomena in time.

Moreover, as the panel of the present invention combines the above mentioned easy assembling by conventional screws, dowels and anchors with a considerable lightness, the operators are eased by exploiting the enhanced laying rapidity and possible reuse in view of the nondestructive dismantling of the panel. Finally it is to be noted the allowed transpiration of the panel, due to the absence of barriers to moisture or steam passage through the panel, this being essential to avoid presence and growth of mildew.

It has to be pointed out that the building panel of the present invention, in spite of the characterizing high mechanical strength, cannot be used alone as a load bearing structural element of any building portion like partitions, inside walls, curtain walls of outside main walls, false ceilings or floor components. Indeed for these applications the panel of the present invention must be supported by metal and/or wooden material structures, to which the panel may be fixed by simple screws, dowels or anchors suitable for the relevant application or alternatively the panel may be applied directly to existing structures made of the most common building materials.

Object of the present invention therefore is the manufacture of a rigid panel with high performance, adapted to be used in the building field, using one of the most eco- friendly materials, namely crude clay. Thus the object is to obtain a panel of crude clay having high mechanical strength in respect of the expected use, and for this reason it is important to select a grade of clay having properties of little shrinkage during the drying stage.

The production process must take into account and overcome the difficulty of keeping clay aggregate during the drying stage, where it is known that clay is prone to formation of crazings and crackings even to such an extent to prevent its use, as well as of obtaining an end product with excellent mechanical strength.

Crude clay is a material that keeps its intrinsic properties when naturally dried.

Therefore when used also in the panel coating, crude clay confers a remarkable environmental activity and a substantial difference in comparison with other materials. Said properties comprise the following characteristics:

1) It is very hygroscopic.

2) The damping effect allows to control the environmental noise (deadening) and to reduce sound transmission (acoustic insulation) .

3) It is incombustible and heat does not cause particular chemical reactions.

4) It is antiseptic and antibacterial.

5) Since clay is a colloid, it has a great capacity of absorbing and neutralizing odor, smoke and many harmful substances, contributing to eliminate bacteria and mildew, thus keeping environment very healthy. 6) It has antistatic characteristics: it is not electrostatically charged and does not undergo degradation in time causing disgregative phenomena. In view of this property, crude clay reduces formation and circulation of dust, contributing to prevent disorders of the respiratory tract (asthma) and allergies.

7) Use of crude clay better meets the criteria of environmental sustainability .

Since the outer coating of the panel according to the present invention consists of a composition of clay and silicates as binders, said coating confers also an extraordinary enhancement of mechanical strength in addition to the above mentioned characteristics.

The whole production cycle must take place as a cold natural drying operation, so that clay keeps unaltered its important properties in the environment of use, that would be damaged by a baking stage as disclosed in the previously discussed document US-A-3549485.

The most suitable material for the above mentioned inner core of the panel consists of mineralized wood fibers that, besides the excellent characteristics of mechanical strength, enhances the already high acoustic dampening and fireproofing properties of clay, as well as the possibility to use a material allowing to the end product to meet the criteria of environmental sustainability.

Mineralization is a process making the wood fibers extremely strong besides refractory as well as water and frost resistant.

From a technical point of view wood fibers have considerable differences in respect of the mineral ones used in the above mentioned document US-A-3549485:

a) As the thermal capacity of the wood fibers (2100 J/KgK) is much higher than the capacity of the mineral fibers (800 J/KgK), this allows a higher thermal storage and consequently a thermal inertia and phase displacement both much bigger,

b) Microporosity and elasticity of wood fibers allow to attain a very high efficiency of acoustic absorption. The high characteristics of internal deadening of the material, matched with the substantial panel stiffness and the macroporosity given by the interstices inside the panel, allow to attain a better response even for low frequency sounds .

The panels consisting of mineralized wood fibers, coated with Portland cement and bound under pressure, constitute a stable, uniform, resistant, compact and durable structure with high resistance to perforation and impact.

The manufacturing method as a first stage, provides for impregnation of the panels with a solution containing about 35% to 40% by weight of water and 60% to 65% by weight of clay, forming a first fluid composition, wherein the solution may penetrate as most as possible inside the interstices of the panel made of mineralized wood fibers and then the panel is caused to be naturally dried.

The obtained product is coated, preferably by a spreading operation, with a mixture containing about 30% to 35% by weight of water, 13% to 14% by weight of potassium or sodium silicate as a binder, 25% to 30% by weight of clay and 25% to 30% of kaolin, forming a second thick and pasty composition. The so coated panel is again sent to a natural drying stage, and at the end of this stage the final product is obtained.

As methods for carrying out impregnation of panels with the first fluid composition, the inner core is preferably dipped into the composition, but other methods may also be used, such as injection of the composition into the inner core, otherwise casting and pressing the composition in the inner core.

It is to be emphasized that for the above mentioned percentage values of the components, deviations of some percent points in excess and/or defect, may be possible, according to the actual contents, thus the real physical properties, of each adopted component, such as the clay type and the purity level of the silicates.

Indeed clay may be selected among those present in the group comprising kaolins, illites or earthenware, while the binders may be replaced or combined with other preferred binding elements. More particularly the silicates may be replaced partially or wholly with carbonates, preferably calcium carbonate and to the binders a small quantity of chamotte may be added, a mixture used for manufacturing refractory articles, comprising brick powder, clay and silicon rich sand, as aggregate to sensibly reduce shrinkage in the drying stage.

It is to be noted that many variations, modifications, additions and/or substitutions of elements may be made to the panel and method of the present invention, where only a preferred embodiment was described as an explicative non limiting example, without departing however from its protection scope, as defined in the appended claims.

Claims

1. A building composite panel, adapted to be supported by a fixed structure and manufactured entirely by a cold operation, comprising an inner core of mineralized wood fibers, a first coating formed by a first fluid composition comprising a solution of crude clay in water, adapted to impregnate said mineralized wood fibers and naturally dried, and a second outer coating formed by a second thick composition comprising a mixture of binders and clay in water and again undergoing a natural drying operation.

2. The composite panel of claim 1, wherein the wood fibers are mineralized with Portland cement.

3. The composite panel of claim 1, wherein the wood fibers are mineralized with magnesite.

4. The composite panel of claim 1, wherein the first fluid composition comprises a solution containing about 35% to 40% by weight of water and 60% to 65% by weight of clay adapted to penetrate in the interstices of the mineralized wood fibers.

5. The composite panel of claim 4, wherein the said clay is selected from the group comprising kaolins, illites and earthenware.

6. The composite panel of claim 1, wherein the mixture constituting the second thick composition contains about 30% to 35% by weight of water, 13% to 14% by weight of potassium or sodium silicate as a binder, 25% to 30% by weight of clay and 25% to 30% by weight of kaolin.

7. The composite panel of claim 6, wherein the sodium or potassium silicate used as a binder in the second composition, is replaced entirely or partially by other silicates or carbonates , preferably calcium carbonate.

8. The composite panel of claim 6 or 7, wherein a small percentage of chamotte is added to the binder, as inert sensibly reducing the shrinkage in the drying stage.

9. The composite panel of preceding claims, wherein the total amount of clay contained in the first and second coating composition, is equal to at least 70% of the overall weight of the dry compositions.

10. A method of manufacturing a composite panel according to the preceding claims, comprising the following steps :

a. preparation of the inner core of mineralized wood fibers;

b. application on said inner core of the first fluid composition impregnating the fibers and forming a first coating layer;

c. natural drying of the so impregnated and coated inner core;

d. application of the second thick composition forming a second layer of external coating; and e. natural drying completing the finished panel.

11. The method of claim 10, wherein the application of the first fluid composition is carried out by dipping the inner core into said composition.

12. The method of claim 10, wherein the application of the first fluid composition is carried out by injection into the inner core.

13. The method of claim 10, wherein the application of the first fluid composition is carried out by casting or pressing on the inner core.