FR2510100A1 - Aluminium hydroxide organic fibre spray on insulating material - made from waste aluminium hydroxide sludge and waste paper pulp - Google Patents

Abstract

A spray on insulating material comprises a mixture of an organic fibrous material (15-25% cellulosic pulp from paper serap), a gel like amorphous aluminium hydroxide sludge (3-5%) and powder aluminium hydroxide (70-80%) which is formed by drying and pulverising the hydroxide sludge. The pH is preferably adjusted to 4-6 by adding H2SO4 or H3PO4 and the mixture is dried and disintegrated into fluffs. An organic adhesive is pref. blown with the material. Used for spraying onto building walls and ceilings as a sound and heat insulating layer. A cheap insulating material is formed by using waste aluminium hydroxide sludge from Al anodising processes.

Description

Sprayed insulation product based on aluminum hydroxide for the building and its preparation method
The present invention relates to an insulation product sprayed for the building or, more particularly, a product suitable for the building and to be used to form a thick layer for thermal and sound insulation of ceilings and walls by spraying it. with a spray gun as well as a method for the preparation of such an insulation product sprayed for the building.

 Needless to say, many modern buildings are fitted with thermal and sound insulation layers on walls, ceilings and floors in order to make living comfort as much as to save the energy necessary to regulate the temperature of the built space.

Big. A variety of insulation products are commonly used depending on the specific nature of the building and the location. For example, one of the most common methods of thermal and sound insulation in homes is to apply a layer of glass wool or a sheet of cellular plastic foam to the wall or other equivalent methods. .

 These materials used to date for the insulation of buildings from heat and noise have their own respective disadvantages not only in the characteristics and the implementation in the construction of the estimate but also in the colt. With regard to the use of the insulating material, there is a new requirement for a product allowing the formation of a thick insulating layer on the ceiling or the wall of a finished building or under construction by spraying with a sprayer.

 Various kinds of sprayed insulation products for the building industry are currently on the market. Many of these commercially available spray insulation products are made from cellulosic fibers. Unfortunately, none of them is entirely satisfactory, in particular, as regards the insufficient flammability or the property of retarding the spread of fire as an inevitable consequence of the use of organic fibrous product as well as the cost. Consequently, there was a strong desire to develop an inexpensive sprayed insulating product for the grade with excellent characteristics and workability.

 If we consider the problem of possible products that can be used as a component of such a sprayed insulation product for the building industry, the idea is that, if an otherwise uninteresting or rather harmful product such as an industrial residue can between used and treated in such a building material a double advantage can be obtained, the elimination of the harmful product and the profit obtained in the marketing of useful products in the building. Naturally, various attempts have been made for the production of construction materials using industrial residues, but unfortunately there are very few examples of commercial success.

The inventors also continued research developed to manufacture an insulation product sprayed for the building by using industrial residues which are otherwise uninteresting or harmful enough to cause pollution of the environment and they came to the conclusion that the sludge containing the aluminum hydroxide gel produced in large quantities in the aluminum processing industry is the most attractive product for such a purpose
The factories for the production of aluminum are clearly representative of the difficulties caused by the elimination of residues and give a general idea of the industries concerned with the serious problem of waste disposal in order to avoid pollution of the environment. As we know, the aluminum objects of recent years are rarely used in the form of rough objects obtained by extrusion, casting or other means of shaping, but almost always after a certain surface treatment,
The most widely used method of surface treatment of aluminum objects in the aluminum industry is, of course, surface anodization in which the surface of the aluminum object is electrolytically oxidized in a bath. electrolytic acid to be covered with a thin but dense layer of aluminum oxide and acquire increased chemical and physical stability as well as beauty. A problem in the anodization of aluminum objects is that a considerable amount of aluminum metallic is inevitably dissolved both in the alkaline cleaning solution for degreasing before anodization and in the acid solution for anodization and that the aluminum component thus contained in these solutions as well as in the water of the following washing the treatment is finally precipitated in the form of amorphous aluminum hydroxide when these solutions are mixed together and neutralized for elimination by sewage.

The amorphous aluminum hydroxide thus precipitated usually forms a slurry in the form of a gel containing considerable quantities of impurities coming from several stages of the manufacture of aluminum such as sulphates, for example aluminum sulphate, aluminum hydroxysulphate, sodium sulfate and the like, and sodium aluminate. Aluminum hydroxide mud in the form of a gel contains large volumes, for example 70 to 90% by weight, of water but is difficult to filter so that treating such a product is extremely difficult. the only way used to date to remove such a gel of aluminum hydroxide gel is to reject it in a land of spreading or in the ocean in the form of gel as it is
Naturally, such a method of removing residues is not really acceptable, even leaving aside the problem of the high cost of transporting such an aqueous product to the spreading ground or to the ocean. land filled with such mud in the form of gel will have a naturally low resistance leading to underuse of the land. The discharge of mud into the ocean is also regulated to prevent pollution of the water.

Thus removing the residue from the aluminum hydroxide mud in gel form has been the most annoying problem in the aluminum manufacturing industry.

 It is therefore an object of the present invention to provide a new sprayed insulation product for the building with good implementation and showing excellent characteristics of heat and noise insulation as well as flame retardancy or resistance to the spread of fire at the same time as providing a method of removing the residue of gel aluminum hydroxide mud produced in large quantities in the aluminum industry and resulting in it at a remarkably low price .of the product obtained from the sprayed insulating material.

 The sprayed insulation product of the present invention is a disintegrated downy product of a desiccated mixture comprising a gel of aluminum hydroxide in gel, an organic product whose fibers are entangled by the mud of aluminum hydroxide in gel and a powdered aluminum hydroxide obtained by drying and spraying the aluminum hydroxide mud in gel.

 The sprayed insulation product for the building of the present invention described above is made first by mixing the aluminum hydroxide slurry gel and the organic fibrous product to form a mixture which is then weakly acidified to a pH 4 to 6 by adding a small amount of an inorganic acid and the weakly acidic mixture thus obtained is then added to the powdered aluminum hydroxide prepared separately. The mixture thus prepared is dried and broken up into flakes so as to be sprayed with a spray gun.

As emerges from the above description, the inyentated sprayed insulating product consists of an amorphous aluminum hydroxide and an organic fibrous product as essential components. However, it is necessary in the present invention that the aluminum hydroxide component is added to the organic fibrous product partially in the form of aluminum hydroxide slurry gel containing batten and partially in the form of dry powder prepared in advance in drying and spraying mud 0 Aluminum hydroxide powder must be added to the mixture of gel aluminum hydroxide mud and organic fibrous product
The proportion by weight of these components, that is to say of organic fibrous product, of aluminum hydroxide in gel in the mud and of aluminum hydroxide in powder, is naturally determined according to various parameters including the characteristics for the finished product of the sprayed insulation product. Typical percentages of these proportions are, for example, 15 to 25% of fibrous product, 3 to 5% of aluminum hydroxide mud in gel calculated as dry product and 70 to 80% of hydroxide powdery aluminum.

 Various kinds of organic fibrous products are suitable for use in the present invention, they include fluff of cotton, wool and other synthetic fibers obtained in fiber processing factories such as spinning and weaving plants, wood pulp and the like. The fibers are preferably as long as possible. The most preferred product, given the remarkable low price and the availability in large quantities, is, however, a regenerated cellulosic pbte obtained by reducing paper into small pieces in the form of flakes.

 First the organic fibrous product is mixed with the aluminum hydroxide mud in gel. When difficulties are encountered in uniformly mixing these products, given their proportion, it is possible to add certain volumes of water to facilitate mixing. In this mixture with the organic fibrous product, aluminum hydroxide amorphous in the gel mud coagulates and intertwines the fibers of the organic fibrous product serving as a bonding agent for the fibers. It has been unexpectedly discovered that the speed of this coagulation of amorphous aluminum hydroxide depends essentially on the pH value of the aqueous portion of the mixture; for example, the pH of the slurry mixed with the organic fibrous product usually ranges from 6 to 7 such that coagulation of amorphous aluminum hydroxide occurs prematurely and the fibers of organic fibrous products are only partially entangled with coagulated aluminum hydroxide.

 Accordingly, the inventors have conducted research to find a way to obtain a reliable and reproducible intermingled state of the fibers and have come to the discovery that the satisfactory intermingling state is obtained when the pH of the mixture of the organic fibrous product and the aluminum hydroxide mud in gel is adjusted to a weakly acidic region from 4 to 6 or, preferably, from 4 to 5.5 by adding a small amount of an acid. The acid used for this purpose is not particularly limiting, but sulfuric acid and phosphoric acid are preferred. In such a weakly acidified medium, the coagulation of the amorphous aluminum hydroxide in gel is somewhat delayed by so that the coagulation which derives therefrom takes place only after the fibers have been sufficiently fused with amorphous aluminum hydroxide.

 When the intertwined state of the organic fibers is established in the mixture as described above, the powdery aluminum hydroxide is added to them and the whole is well mixed, This powdery aluminum hydroxide is, as this is mentioned above, obtained by drying and powdering the slurry in the form of an amorphous aluminum hydroxide gel. The sludge can be dried in the open air but it is recommended to accelerate the drying by heating when the energy cost for heating is not too high as in the use of waste heat. amorphous alumina thus dried is then reduced to powder by means of a suitable grinding machine such as ball mills, hammer mills and the like.

 It is preferable that the powdered aluminum hydroxide passes through suitable mesh screens to remove the abnormally large particles in order to ensure good processing of the mixture and excellent characteristics of the sprayed insulating product of the invention. The preferable particle size distribution is obtained by eliminating coarse particles that do not pass through a 100 mesh screen in Tyler's standard mesh series (0.147mm mesh). The best results are obtained when the powdered aluminum hydroxide does not actually contain any coarse particles having a diameter exceeding 10 μm.

When the conditions described above are met, the resulting mixture of the organic fibrous product, aluminum hydroxide mud gel and powdered aluminum hydroxide has improved filterability and strip permeability properties. such that it is relatively easily dried and subsequently broken down into flakes. The dried mixture prepared as described above is easily broken down into flakes by the use of a suitable machine such as a coiling machine and used as a sprayed insulation product according to the present invention.
When the sprayed insulating product of the invention is used for insulating ceilings, the material is sprayed as it is in the attic using an air gun so that the product is deposited on the ceiling according to the invention. thickness desired.The layer thus formed by the product of the invention has good stability due to the particular structure formed by powdered aluminum hydroxide trapped in the network of organic fibers which in turn are entangled by the gel amorphous aluminum hydroxide serving as adhesives Despite the use of the organic fibrous product as reinforcement material, the sprayed insulating material of the invention has great properties of flammability and resistance to the propagation of fire due to the presence a large amount of aluminum hydroxide which is explained by the fact that powdered aluminum hydroxide is widely used as a fire retardant in various kinds of plastic materials Obviously, the coefficient of thermal conductivity of the insulating product of the invention is low enough to allow good thermal insulation although this depends on the degree of compactness of the insulating layer0 For example, the coefficient of thermal conductivity of a layer formed of a typical material of the invention, packed to have a density of 0.78 g / cm3 is 0.066 kcal / mh0C.

 As described above, the insulating product sprayed as it is when the insulating layer formed with the product of the invention is on the ceiling. It is desirable, however, that the sprayed product of the invention be sprayed or sent together with an adhesive agent when the insulating layer is to be formed on a vertical wall or on the sloping surface of the ceiling in order to prevent the detachment of the surface of the first insulating layer formed due to the bonding power of the adhesive. The blower nozzle for performing such mixed insufflation is provided so that the insulating product of the invention is sprayed out of the central opening nozzle while the adhesive is sprayed through the openings surrounding the central opening so that the product of the invention hits the wall and is deposited there entrained by the adhesive.

 Various kinds of adhesives are suitable for the purpose pursued, but acrylic adhesives and ethylene-vinyl acetate copolymers are preferred. These adhesives are preferably used in the form of an aqueous emulsion since the use of organic solvents is very undesirable in a building because of the danger of fire or explosion as well as for the health of workers. The amount of adhesive relative to the insulating product of the invention must be carefully controlled since no satisfactory bonding effect is obtained with too small a quantity of adhesive while the use of an amount of excess adhesive leads to the consolidation of the insulating layer with an increased coefficient of thermal conductivity.

The following examples illustrate the invention by giving further details
Example t
In a container were introduced 20 kg of a gel of aluminum hydroxide in gel containing approximately 4 kg of amorphous aluminum hydroxide and 20 kg of a regenerated leg obtained by beating newspaper into small pieces and the pH of the mixture was adjusted to 4.5 by adding a small amount of sulfuric acid to an additional volume of water to facilitate mixing. The cellulosic fibers of the center pulp under the action of the aluminum hydroxide contained in the mud while continuing to mix.

On the other hand, a powdery aluminum hydroxide was prepared by drying the same gel aluminum hydroxide slurry as that used above and pulverizing the dried product using a ball mill and then sieving to have a particle size distribution passing through a 200 mesh screen (0.074 mm void) 0
The mixture of cellulose pulp and mud was then added to 76 kg of powdered aluminum hydroxide and well mixed. The mixture was dried in an oven with hot air circulation at 800C and then disintegrated into flakes by a wiggle mill.

 The flaky product prepared above was sent by a wind tunnel into the attic of a building to settle and form a layer of about 10-15 mm thick on the ceiling panel. The diaper was enough. tear resistance and the density and the thermal conductivity coefficient of the layer were approximately 0.2-0.4 gXcm3 and 0.04-0.06 kcal / m.h00C, respectively.

example 2
The flaky product prepared in Example 1 was sprayed by a blower on a vertical wall together with an aqueous emulsion of an adhesive acrylic resin diluted to a solid content of $ 20 by weight using a blower equipped of a gun with two nozzles. The spray rate of the adhesive was about 15-30% by weight calculated as a solid relative to the amount of flaky product sent.

 The layer formed on the wall was approximately 10-15 mm thick after complete drying and posed no risk of falling. The density and the coefficient of thermal conductivity of the insulating layer thus formed and desiccated were approximately 0.2-0.4 g / cm3 and 0.04-0.06 kcal / m.h, DC, respectively.

Claims (5)

 1. Insulating product to be sprayed for the building, characterized in that it comprises an organic fibrous product, an amorphous aluminum hydroxide mud in the form of a gel causing the fibrous product to intermingle and hydro- aluminum oxide powder which is a dried and powdered product of a slurry of aluminum hydroxide in gel form and uniformly mixed with the organic fibrous product intermingled with amorphous aluminum hydroxide.  2. Insulating product to be sprayed for the building according to claim 1 characterized in that it comprises from 15 to 25 Vo by weight of the organic fibrous product, from 3 to 5 ffi by weight of the amorphous aluminum hydroxide mud in the form of a dried gel and from 70 to 80% by weight of powdered aluminum hydroxide.  3. Insulating spray product according to claim 1 characterized in that the organic fibrous product is a cellulose pulp of fibers obtained from paper torn into small pieces.  4. A method of manufacturing an insulating product to be sprayed for the building, characterized in that it comprises t (a) mixing an organic fibrous product with an amorphous aluminum hydroxide mud in the form of a gel ( b) adjusting the pH of the mixture of the organic fibrous product and the amorphous aluminum hydroxide mud in the form of a gel between 4 and 6 by addition of an acid; (c) adding a powdered aluminum hydroxide which is a dried and sprayed product of an amorphous aluminum hydroxide mud in gel form to the mixture of the organic fibrous product and the hydroxide mud amorphous aluminum in gel form; (d) drying the mixture obtained in phase (c); (e) disintegration of the dried flake mixture  5. Method according to claim 4 characterized in that the amounts of the organic fibrous product, of the amorphous aluminum hydroxide mud in the form of gel and of aluminum hydroxide powder in the mixture are respectively from 15 to 25% by weight for the first, from 3 to 5% by weight for the second in the dry state and from 70 to 80% by weight for the third  6o A method according to claim 4 characterized in that the organic fibrous product is a cellulosic pbte of fibers obtained from paper torn into small pieces0  7. Method according to claim 4 characterized in that the acid used in phase (d) is sulfuric acid or phosphoric acid.