The glass edge Hot Melt sealant GSPK-D is developed for application at production of glass units as an outer
secondary sealant, to be applied after fastening glass with spacers. The Hot Melt technology includes heating of
the compound and extrusion of its melt through a replaceable head of extrusion machinery's metering gun.
The product is produced in form of black-coloured briquettes, each of them being of 7kg net weight,
poured into a paperboard demountable box. 3 pieces are packed into transportation boxes as shown on the picture right above.
This standard form of HotMelt's container of 7kg net weight has been worked out by a Moscow company in June, 2005, and now it is used for
packing in most cases (the second picture). If ordered, the Hotmelt may be poured into cylinders like the butyl sealant.
The well-known advantages of one-component Hot Melt
sealants are the following:
- No preliminary components intermixing; lower cost of the material and Hot Melt extrusion device;
- High adhesion to glass and to all types of spacers, not going down even in conditions of high humidity;
- Rapidity of the sealant’s work. The ready package can be transported in a very small period after the sealing
has been done (several minutes);
- Absence of vulcanisation of the material with ageing in package that could cause solidification and loss of
elastic and adhesion properties of the sealing;
- A long shelf-life of the material - as a cool substance it is chemically inert and does not perceive oxidative
ageing and ultraviolet radiation;
- Bionomically favourable technology of production and application without any solid waste products,
harmful outlet and gaseous exhausts.
These advantages are also mentioned and described more elaborately for example on the web-site of the insulated glazing company
having a 40 years experience in this field, Ulmke Metals, Birmingham, UK.
Some of the specified advantages can be explained from chemical points of view.
High adhesion to glass and spacers is certainly a key issue of the Hot Melt’s serviceability. The mechanism
of the adhesion processes is complicated enough, and the explanation of it is usually based on general colloidal
- chemical theories. In most cases it is considered that adhesion of substances is tangled up with forces of
electrochemical intermolecular interaction of an adhesive and substrate. So, it is easy to understand that
non-polar molecules of an adhesive (sealant) would not be capable to provide necessary interaction with
polar surfaces of substrate. Therefore the sealing compound should necessarily contain in its composition
some groups with charge displacement, which thus would be active and interact with the surface. It is considered
that adherence to silicate glass with very small coarseness of the surface is caused by activity of exposed
hydroxyl groups of the surface, which form connection with the charged groups of an adhesive due to forces
of electrostatic interaction. Composition of the GSPK-D sealant includes special resins having chains with
charge displacement mentioned above (containing so-called hetero-atoms), and that is the specific cause of
the material’s surface activity. If groups with charge displacement are not present, there is no adhesion
to develop. A simple example – one can try to stick melted polyethylene or any similar non-polar polymer to glass.
It is impossible, the polymer will just drop down.
Processes of ageing vulcanisation - the phenomenon almost imminent for double-component materials.
Cold vulcanisation results in an elastic substance to which all properties of rubber are peculiar, including ageing,
no wonder. Routinely, these processes are stopped by special additives; it is impossible however, to kill them
completely. Radical reactions of slow vulcanisation and crosslinking bonds formation result eventually in change
of material properties, i.e. its solidification. Oppositely, to Hot Melt compounds this problem is not peculiar,
since they are put from a melted condition, and the solidification means simple cooling down and the subsequent
development of adhesion bonds. In other words, the sealant is not vulcanised in bed at all and as it contains only
elastomers with a very small quantity of olefin bonds, its tendency to ageing is minimal. Despite of it, this material
contains special additives preventing ozone surface cracking, oxygen and ultraviolet ageing, i.e. the necessary
complex of stabilisers. Usually it is synthetic sterically hindered arene being a very active radical catcher.
These compounds are capable to interrupt any radical reaction in the beginning and to prevent its further development.
The brief description and physical properties of the GSPK-D material
Hot Melt glass edge sealant GSPK-D - application instructions