What Is An Aluminum Composite Material

Composite panels, initially designed for building applications – facing and reconstruction of old buildings (minimal load on the foundation and walls) – have become very popular in advertising production in recent years. These materials are two layers of thin, pre-painted aluminum sheet, between which there is a polymer (polyethylene, polypropylene, polyurethane, polystyrene) or refractory mineral filler. The layers are joined together by a technology that provides the finished product with high resistance to delamination. The outer surface of composite materials, in addition to the paint layer, can have a lacquer anticorrosive coating, which increases wear resistance. The article is produced in the form of the continuous tape,

Composite panels have high rigidity, impact resistance, pressure resistance and wind loads and at the same time lightweight (composites 3 to 4 times lighter than steel sheets and 1.5 to 2 times aluminum rolled products).

Multilayer Material

The production process provides the multilayer material with precise planar characteristics and homogeneity of the application of the surface inking and protective layers. Staining and varnishing depending on the purpose of the panels can be made by different compositions - based on polyesters or polyfluorinated compounds - fluorocarbons (polyvinylidene fluoride PVDF, less often polytetrafluoroethylene PTFE)

Galvanic Techniques

Groups can be painted and varnished on one or both sides and are executed in the broadest color range, as well as with a surface that imitates natural stone, brick, plaster, wood. The effect of a noble metal on the surface of an aluminum composite is most often achieved by galvanic techniques. Composites are conditionally divided into materials for street and interior use. The former include panels with thicker aluminum layers and a fluorocarbon coating.

Materials for internal tasks have aluminum layers of lesser thickness; on their surface is applied mainly polyester coating, in street conditions behaving less stable compared to fluorocarbon.

 In addition to physical and mechanical properties, chemical inertness of the surface and aesthetic advantages, the popularity of composite materials undoubtedly ensures the ease of modification of the shape of the sheet and the production of broken and curved planes allowing the manufacture of a wide variety of products with a minimum number of fastening elements. Panels can be mounted vertically, horizontally or in an inclined position without deformations and sagging.

Composite materials can be operated in a wide temperature range – from -50 ° to +80 ° С.

Areas of application: wall and balcony fences, ceiling structures, canopies and awnings, exterior and interior lining, large advertising carriers – billboards and placards, signs, columns, steles, tablets, volumetric letters, registration of gas stations, shops, stadiums, exhibition construction.

Compositions And Properties Of Composite Building Materials

The main component of composite materials is a binder that under the influence of hardeners or water passes from a liquid or dough to a solid state. For the production of KCM, a large group of inorganic and organic binders is used, chosen by operating conditions and product requirements. The greatest application is found on materials based on cement, gypsum, lime, bitumen and polymer binders. In some areas of construction, composites based on liquid glass, magnesian and sulfuric binders are promising.

The intensification of construction is accompanied by the continuous search for perfect KCM. An example of such a search can serve the work of recent years to improve the properties of concrete with the help of polymers. They are made on polymer binders in a mixture with chemically stable fillers and fillers without the participation of metallic components. By the form of the binder phenol-formaldehyde, furan, polyester, epoxy, urea, polyurethane, acetone-formaldehyde, polymethylmethacrylate, polyethylene and other polymer concrete are distinguished, as well as numerous varieties of composites on modified and combined resins.

Domestic and world practice shows that polymer concrete is often used in construction on epoxy, polyester and urea resins. Of the wide variety of epoxy resins manufactured by our industry, the most famous applications for the production of polymer concrete are epoxy diseases, which are the condensation products of epichlorohydrin with diphenylpropane in an alkaline medium. Depending on the quantitative ratio of the components entering into the polycondensation reaction, epoxy resins with a linear structure and different relative molecular weights are obtained, ranging from 340 to 4290. As this index increases, their viscosity increases and the reactivity decreases.

The conversion of solid epoxy resins to a liquid state is carried out with solvents or elevated temperatures. In the technology of polymer concrete, the use of solid epoxy resins is not efficient, since in one case the enzymes lower the density of the composites, while in the other, high temperatures are required – about 50-155 ° C, depending on the relative molecular weight of the resin. From this point of view, liquid resins of ED-16, ED-20, ED-22 and their compounds with rubbers, furan, and other resins are more suitable. The transition of epoxy resins to the non-melting and insoluble state is carried out under the action of hardeners, which facilitate the connection of linear resin molecules to the spatial formations in place of epoxy and hydroxyl groups. Curing is carried out with the help of ion-type catalysts (tertiary amines, piperidine, dimethylaminomethlphenol, antimony chloride, fluoride or other compounds) or crosslinking reagents (polyethylene polyamines, ethylenediamine, m-phenylene diamine, methylenedianiline, p-xylidenediamine, etc.). For the cold curing of epoxy resins, polyethylene polyamine, hexamethylenediamine, hexomethylenediamine bottoms remain predominantly used. In the manufacture of polymer concrete products in conditions of 100% humidity and under water, the aminophenol hardener AF-2 and aminoplast ASF-10 are preferred.

Unsaturated Polyesters

It should be noted the high activity of amine curing agents and the low viability of epoxy compositions healed by them. Accelerated curing creates specific difficulties in the manufacture of construction products, which is primarily characteristic for low-filled structures, for example, polymer concrete floors. In this regard, the development and application of new hardeners that enhance the viability of epoxy polymer concrete without deteriorating their physical and technical parameters is an urgent task.

In the production of polyester polymer concrete, unsaturated polyestermaleate and polyester acrylate resins are used. Saturated polyester resins, cured at elevated temperatures and pressures, are not used for the preparation of polymer concrete. Unsaturated resins are solutions of unsaturated polyesters with a molecular weight of 700-3000 in monomers or oligomers capable of copolymerizing with these polyesters. As a monomer, styrene is used more often, methyl methacrylate, acrylonitrile, diallyl phthalate and other monomers are more often used. Curing of resins is made by initiators and accelerators of hardening, which are typically used in normal conditions for a two-component system consisting of an initiator for hardening of isopropylbenzene hydroperoxide (hyperemia) and a throttle – 10%. The solution of cobalt naphthenate in styrene (with the curing of the PN-1 resin, the optimal amount of hysteresis is 3-4%, and cobalt naphthenate 6-8%). More rarely, as initiators of hardening, benzoyl peroxides, cyclohexanone, methyl ethyl ketoxime are used, and accelerators are vanadium pentoxide, dimethylaniline, and diethylaniline.

Methods have been developed for curing polyester resins using three- and four-component systems. Due to the explosive reaction occurring during the mixing of hyperemesis and cobalt naphthenate, the components of the initiating system are introduced into the resin alternately. To exclude this shortcoming, studies are carried out to optimize the compositions and to select non-explosive hardeners. In the works, the possibility of curing polyester resins with zinc dust as a one-component system, as well as methods consisting of non-explosive initiators – caprolactam and accelerators – lead gland, lead-manganic drier or aerosol was studied. The most promising curing agents for polyester resins are dispersed materials that can be incorporated into the resin in a mixture of fillers.