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- Practical Guide -
Page 107 of 153
Note: They may be coated, impregnated or otherwise converted, during or after their manufacture, without
necessarily losing their identity as paper. In conventional paper making processes, the fluid medium is
water; new developments, however, include the use of air and other fluids.
2.1.7 Board: Generic term applied to certain types of paper frequently characterised by their
relatively high rigidity.
Note1: In the generic sense the name "paper" can be used to describe both paper and board as defined.
Note 2: For some purposes, materials of a grammage of less than 225 g/mē are considered to be paper, and
materials of a grammage of 225 g/mē or above are considered to be board. However, distinction
between paper and board is primarily made on the basis of the characteristics of the material and, in
some cases, its use. Many materials of a grammage of less than 225 g/mē, such as certain grades of
folding box board and corrugated raw materials, are generally referred to as "board" and many materials
of a grammage greater than 225 g/mē, such as certain grades of blotting paper, felt and drawing paper,
are generally referred to as "paper".
2.1.8 Binder: Material that holds the pigment particles, in a pigment coating, together and fixes
them to the surface of the paper or board.
2.1.9 Dispersion: Mixture of particles distributed in a vehicle. The particles can be in the form of
hard aggregates or be flocculated, or both conditions could exist together.
2.1.10
Emulsion
: Mixture of two mutually insoluble liquids in which one liquid is finely dispersed
as droplets in the other.
2.1.11
Paraffin wax
: Mixtures of high-boiling hydrocarbons derived from petroleum, solid at room
temperature with a melting range from approximately 40-60oC.
2.1.12
Layer
: Continuous thickness of a material covering the surface of a substrate, forming a
multi-component structure.
2.2
P
ROCESSES
2.2.1 Coating: Process by which one, or more, continuous layers of a material, in fluid or molten
form, is applied to the surface of an existing material.
2.2.1.1
Solvent coating
: Process by which a solution or dispersion of a polymeric material and
additives, in an appropriate volatile solvent, is applied in one or more steps onto the moving
web of the substrate. The film is formed by evaporation of the solvent.
Note:
This process is also known under the name of lacquering or lacquer coating.
2.2.1.2
Dispersion or emulsion coating
: Process by which an aqueous dispersion or emulsion and
additives are applied in one or more steps onto the moving web of the substrate. The film is
formed by evaporation of water.
Note:
Wax is a common additive.
2.2.1.3
Solvent free coating
: Process by which monomers or prepolymers in liquid form, with or
without reaction agents, is applied onto the moving web of the substrate. The polymer is
formed by a chemical reaction (curing) initiated by catalysis, radiation (ultraviolet or infra red
radiation, heat), electron beam, high frequency, water, steam or high temperature.