For the solvent-based adhesives, the bonding substances which are also called binding agents are dispersed in an organic solvent. When the solvent evaporates, the adhesive changes from liquid to its final solid form and the pure bonding substance remains.
The function of the relatively highly volatile solvents is to ensure that the binding agents stays liquid and can therefore be processed easily while facilitating an easy transportation.
In addition to this essential function, the solvents also influence key adhesive characteristics such as adhesion, dwell time or open time by promoting the wetting of the substrate or by biting the substrate surface depending on how fast they evaporate.
PRODUCT SERIES, PROPERTIES AND APPLICATION
CR Adhesives
Basis : Polychloroprene rubber
Properties :
Chloroprene rubber (CR) adhesives are characterised by an immediate initial strength which provides a major benefit in applications with fast downline processing or for when vertical surfaces have to be bonded.
To ensure the highest possible initial strength, the dwell time should be long enough until the adhesive layer is dry to the touch.
The bond is formed immediately as soon as the two substrates coated with a touch-dry film of CR adhesive (also called contact adhesive) are then shortly pressed together with high pressure. The adhesive will keep its ability to form a bond upon contact for a limited time after the solvents have evaporated.
In many cases, completely dry adhesive films can be reactivated with solvents or by heat.
CR (Polychloroprene Rubber) adhesives provide the following benefits:
- Many different applications
- Very high initial strength
- Wide range of adhesion to different materials
- High heat resistance.
Packaging : Liquid, bucket, hobbock, drum, IBC
Brand : Senta, Jowat
SC Adhesives
Basis : Styrene copolymer rubber
Properties :
Solvent-borne adhesives based on styrene copolymers (often also called SBS or SIS adhesives) are generally applied with spray guns, and are characterised by a good spraying performance and a relatively high solids content.
For this group of adhesives, one or both substrates can be coated.
A major part of the solvents already evaporate during spraying which leads to a huge increase in the viscosity of the adhesive.
These adhesives are therefore often used for bonding very porous substrates.
Even when applied in thinnest layers, SC adhesives have comparatively a very high contact tack during their open time. Joining the substrates while there is still a small amount of solvent in the adhesive ensures a proper wetting of the bonding partner and a fast build-up of initial strength even with low pressure.
After all solvents have evaporated, there should be no residual tack.
The bonded substrates then can be covered with fabrics or other materials, for instance in the production of mattresses and upholstery furniture.
SC (Styrene copolymer rubber) adhesives provide the following benefits:
- High initial strength
- Excellent tack
- Good adhesion to many substrates
- Long open time depending on the formulation
- High solids content possible
- High content of renewable raw materials
- Often economical adhesive group
- Easy handling due to application by spraying.
Packaging : Liquid, bucket, hobbock, drum, IBC
Brand : Sentatac, Jowatac
PU Adhesives
Basis : Polyurethane
Properties :
Solvent-borne contact adhesives based on polyurethane (PU or PUR) are characterised by resistance to plasticisers and good adhesion to the most different materials (except bare metal).
Therefore they are used for bonding soft PVC to each other as well as to many other materials.
Similar to CR adhesives, they can also be reactivated by heat (e.g. in vacuum deep-drawing methods for the lamination of formed parts with flexible top layers).
To achieve good heat and plasticiser resistances, the adhesive is usually mixed with 3-7 % crosslinking agent before processing. he immediate strength is built up by physical hardening while the final strength is achieved by chemical crosslinking after approximately 3-5 days.
PU (Polyurethane) adhesives provide the following benefits:
- Very soft adhesive seam
- High heat resistance and good resistance to plasticisers when mixed with crosslinking agent
- Very good ageing resistance of the adhesive.
Packaging : Liquid, bucket, hobbock, drum, IBC
Brand : Senta, Jowat