Лако-красочные материалы — производство

Flooring adhesives are used for attaching floor coverings to a variety of substrates. The adhesives must develop a strong and durable bond between the floor covering and the substrate. They should not adversely affect coverings, supports and substrates, and after application, should remain odorless and have low emissions. Usually flooring adhesives are applied to the substrate by hand with trowels or sometimes rollers.

Recent environmental and occupational-health legislation has resulted in a major shift from organic solutions to aqueous emulsions of polymeric compounds [88], and the use of waterborne adhesives is accepted as the state-of-the-art for most floor covering installations. Waterborne flooring adhesives are often based on acrylic copol­ymers, vinyl acetate — acrylics, vinyl acetate — ethylene — acrylics, or styrene-butadiene rubber latex. They commonly contain natural (e. g., colophony and colophony esters) or synthetic resins (e. g., hydrocarbon resins) and inorganic fillers. In recent years the content of solvent has been reduced to below 5 wt %. The use of high-boiling solvents (glycol ethers, liquid hydrocarbons) has been adopted to some extent for the formu­lation of solvent-free flooring adhesives [89]. There is now a move to eliminate high- boiling substances and even traces of volatile contaminants from the adhesives [90]. Several European manufacturers have established a chamber test method to record VOC and to classify low-emission products for flooring [92], [203]. Today solvent-based products are only needed for special applications (e. g., water-sensitive substrates).

Linoleum Adhesives. Linoleum generally is laid with waterborne adhesives based on acrylic emulsions or SBR latex. They contain higher amounts of inert inorganic fillers, and natural and/or synthetic resin is used to accelerate initial tack. Linoleum adhesives have to set rapidly to avoid expansion or shrinkage of the covering. Two-component adhesives consisting of one polymer dispersion and a second cement preparation are available to adhere linoleum to nonabsorbent substrates.

Parquet adhesives can be cold — or hot-spread compositions. The former can be classified as waterborne, solvent-borne, or reactive. The first two types are commonly based on poly(vinyl acetate) emulsions in water or as solutions in organic solvents. Reactive systems are solvent-free two-pack polyurethane adhesives or epoxy resin adhesives. They are preferred for all parquet and wood types which are sensitive to water. All adhesives are required to show high cohesive strength but certain plasticity to absorb movements of the wood through shrinking and swelling in response to changes in atmospheric humidity without failure of the joint. Hot-spread adhesives, which are bituminous or tar-based, are increasingly being replaced by the cold-spread types.

Adhesives for Plastic Floor Covering. Solvent-free adhesives based on acrylic and vinyl acetate — ethylene — acrylic emulsions are used for bonding vinyl, synthetic rubber, and polyolefin flooring. Solvent-containing contact adhesives (rubber — or polychloro — prene-based) still are used for some applications (e. g., stairs). When water resistance is required, reactive polyurethane or epoxy resin adhesives are preferred to waterborne emulsions.

In addition to developing a certain minimum strength, the adhesives primarily have to meet demands on the dimensional stability of the covering.

Because of plasticizer migration between covering and adhesive joint, the adhesives for plastic floor coverings should be adjusted carefully in their composition. Plasticizers are commonly used for the production of coverings based on PVC.

Adhesives for Textile Floor Covering. The composition of waterborne adhesives for bonding wall-to-wall carpets is similar to that of linoleum adhesives. High initial tack (wet tack) and a resistance against carpet cleaners is required. Previously used solutions of polyfvinyl ethers) and rosin in mixtures of highly volatile solvents are still used for carpets that are extremely sensitive to water.

Conductive Adhesives. Conductive adhesives are available for bonding conductive floor coverings. The electrical properties are achieved by the addition of carbon fibers, carbon black, or graphite. Conductivity of a floor covering is sometimes required to avoid undesirable static charging.

Tile Adhesives. The thin-set process uses hydraulically hardening thin-set mortars based on cements, emulsion adhesives based on aqueous synthetic resin emulsions, which can be single-component ready to use tile adhesives or two-component adhesives consisting of modified aqueous emulsions and a cement-based compound, and reactive adhesives based on epoxy resins or polyurethanes.

Depending on the intended field of use, cement-based tile adhesives are modified with different amounts of redispersible synthetic resin powder such as со — or terpol — ymers based on vinyl acetate or acrylates. The recipe must be adjusted to the different types of tiles and natural stones. On account of the various types of tile adhesives corresponding standards may be found, for example in DIN, BSI, AFNOR (Association

Frangaise de Normalisation), UEAtc (Union Europeenne pour Г Agrement Technique dans la Construction) or as European Standards prepared by CEN.