Parquet bonding

Figure 2-7. Ordered networks. 0, Adamantane as an example of a cage polymer (type 0) I, Cyclized and dehydrogenated l,2-poly(butadiene) as an example of a ladder or double-strand polymer (type 1) 2, graphite as a layer or parquet polymer (type 2). ( ) Carbon-to-hydrogen bonds (— and =) carbon-to-carbon bonds.

Once the different parts are bonded, these materials come back to their normal condition. Wood and paper shrink if they are allowed to dry in a dry atmosphere, for instance when a piece of furniture or a parquet is put in a dry house with heating during winter, the wood shrinks, the shrinking may reach up to 2 mm per metre. 

SikaBond -66 AT is a universal assembly adhesive for construction as it is a phthalate-free PUR-Hybrid adhesive with good bonding and compatibility to polystyrene insulation. An application is described in Section 6.8.8 entitled Bonding of Parquet/Timber Floors . Its mechanical properties are summarised in Fig. 82, along with those of Sikaflex -20. 

The volume changes due to swelling and shrinking are accompanied by movement, which causes considerable shear stress in the adhesive layer and the substrate. The adhesive must follow the swelling of the wood reliably and in such a way that the wood not only remains undamaged but that a shear-resistant bond is formed between the parquet floor and the substrate. 

An even distribution of stress in the bonded adhesive area is necessary to ensure a durable bond and to take full advantage of the material properties. Conventional rigid bonding, however, causes stress peaks at the edges of parquet boards. Elastic adhesives, on the other hand, transmit forces over the whole bonding surface. 

These adhesives are therefore particularly suitable for large-surface bonding applications such as parquet floor laying. The high shear forces are absorbed and at the same time the substrate is not exposed to undue risk of damage. Theory shows that low-modulus elastic adhesives can ensure a shear-resistant bond of the parquet flooring to the substrate. 

Both tests simulate ageing behaviour under extreme conditions. This does not mean that parquet floors bonded with rigid adhesives will necessarily show this joint gap pattern. Both tests, however, highlight the improvements that can be achieved by the use of elastic adhesives for bonding parquet floorings. 

Amino resins are manufactured throughout the industrialized world for a variety of applications. Adhesives represent by far the largest market. Large amounts of simple urea-formaldehyde resin adhesives are used to bond plywood and particleboard, also known as chipboard, flakeboard, or waferboard. More complex adhesive formulations are used to make laminated wood beams, parquet flooring and interior flush doors, and for furniture assembly. 

Some reactive polyurethane adhesives such as one- and two-component ones are particularly suitable for wood bonding. They are currently being used for the bonding of parquets and other wood flooring, mainly because of their strength and resistance. They are also being used for bonding of heavy duty rubber floor in commercial areas with heavy foot traffic [24]. 

Floors of any type are placed almost exclusively by bonding technology. Therefore, solvent contact adhesives, dispersion adhesives, and pressure-sensitive adhesives are widely used for this application. For bonding parquet, the following types of adhesives are mainly used... 

With elastic polyurethane adhesives, almost all construction materials are laminated together, such as concrete, wood, ceramics, plastic, and metal. Thus, completely new design possibilities arise. When bonding steps, parquet, or tiles, two advantages come into play, namely, the impact sound insulation and the background-balancing property of the adhesive (Brunner 1996). 

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