Glossary
additive: any substance added to polymers to improve or modify one or more properties.
antiblock: an additive incorporated in or applied to plastic films to prevent the unintentional adherence during production, storage or use
antioxidant: an additive that inhibits or retards oxidation during production, processing, storage and use
antistatic agent: an additive which imparts a degree of electrical conductivity to plastics, allowing for the dissipation of static electricity.
calcium carbonate: widely used inorganic filler (calcite, chalk, marble and limestone)
carbon black: the most widely used black pigment, also acting as a UV stabiliser in plastics.
carrier: an inert polymer in which the active ingredients of a masterbatch are compounded
chalking: a dry, chalk-like appearance or deposit on the surface of a plastic
clarifier: an additive added to semi-crystalline polymers to modify their crystalline structure by providing sites for initiation of crystallisation, enhancing clarity, hardness, and tensile strength
compatibility: a state in which a component of an admixture in plastics will not exude, bloom, or separate
compound: the intimate admixing of a polymer or polymers with other ingredients such as fillers, plasticisers, catalysts and colorants
copolymer: a polymer derived from more than one species of monomer
cross-linking: the process of multiple intermolecular bonding between polymeric chains
density: weight per unit volume of a substance, usually reported in g/cc or kg/m³.
die: a steel block containing an orifice through which plastic material is extruded, thus shaping it to the desired form.
discoloration: a colour change which involves either lightening or darkening and/or change in hue
dispersion: a heterogeneous system in which a finely divided material is distributed homogeneously in an other material
dye: a colorant, usually transparent, which is soluble in the application medium
extender: an inert substance added to a polymer to reduce its cost
extruder: a machine for the continuous shaping of a moulding material through a die in the form of strands, films, fibres, pipes, sheets, profiles, etc.
filler: a solid, relatively inert, material added to a plastic in order to modify its strength, permanence, working properties, or other qualities or reduce their cost
film: a thin plane product of arbitrarily limited thickness, in which the thickness is very small in proportion to length and width
flame retardant: an additive which renders a polymer fire-resistant
flexography: a printing method in which a liquid ink is applied to a raised photopolymer or rubber plate (stereo) in contact with an inking (anilox) roller. the plate rotates and transfers the image to the surface of the substrate.
fluorescent colorant: a colorant that absorbs light as particular portions of the colour spectrum, re-emitting this light energy at much lower frequencies or longer wavelengths.
gloss: the degree to which a surface approaches perfect optical smoothness in its capacity to reflect light gravure printing: a printing process by which the depressions in an engraved roll are filled with ink, the excess being wiped off by a doctor blade. ink remaining in the depressions is deposited on a flexible film as it passes between the engraved roll and the back-up roll
haze: a cloudy appearance within or on the surface of a plastic
kLy: kilo-Langley is a unit of incident radiation energy (1 kLy = 1 kcal cm-2)
light fastness: resistance to colour changes due to exposure to light without direct atmospheric effects
lubricant: an additive which facilitates processing or prevents sticking of a plastic formulation
masterbatch: a masterbatch is a concentrate of colorants or additives properly dispersed into a carrier polymer, which is then blended into the natural polymer to be coloured or modified
MFI: (melt flow index) the weight of polymer melt in grams forced through an orifice by a specified weight load in 10 min at a specified temperature.
migration: the transfer, usually undesirable, of a material from a plastic body to a contacting solid or liquid
monomer: a compound consisting of molecules each of which can provide one or more constitutional units
opacity: the property of an object to obstruct the penetration of light
pellet: a granule of a preformed moulding material having relatively uniform dimensions in a given lot, used as a feedstock in moulding and extrusion operations
pigment: substance consisting of particles that are practically insoluble in the application medium, used chiefly as a colouring material.
plastic: a material containing a high polymer as an essential ingredient and which at some stage in its processing into a finished product can be shaped by flow
plasticiser: a substance of low or negligible volatility incorporated in a plastic to lower its softening range and to increase its workability, flexibility or extensibility
plate out: the undesirable deposition of additives or pigments on machinery during processing of plastics.
polymer: a substance composed of molecules characterised by the multiple repetition of one or more species of constitutional units (monomers) linked with each other in such amounts that provide a set of properties that do not vary markedly with the addition or rem
polyolefins: the class of polymers made by polymerising relatively simple olefins
polypropylene: a tough, lightweight, rigid plastic made by the polymerisation of propylene gas
premix: an admixture of resin and additives in powder form, usually prepared by the processor shortly before use
reducer: a liquid system whose sole function is to reduce solids concentration, viscosity and colour strength of an ink or paint system
resin: any polymer which may be incorporated in a plastic material, ink or paint system
rigidity: the property of materials to withstand failure in extensional, impact or flexural stress
slip additive: a substance which tends to make surfaces slippery i.e. reduce the coefficient of friction.
solvent: the liquid carrier of an ink or paint systems where resins and additives are dissolved and/or suspended
solvent retention: incomplete evaporation of the volatile fraction of an ink or paint system during application
stabiliser: a substance used in the formulation of plastics to assist in maintaining the properties of the material at or near their initial values during processing and service life
suspension: a dispersion of a solid into a liquid
titanium dioxide: a white pigment available in two crystalline forms, rutile and anatase, the former being the most widely used white and opacifying pigment in thermoplastics, printing inks and paints.
UV absorber: an additive which protects materials by absorbing UV radiation.
UV stabiliser: additive which stabilises organic materials against UV radiation.
varnish: a liquid system whose sole function is to reduce pigment concentration in an ink or paint system
warpage: dimensional distortion of a plastic object after moulding or other fabrication
weathering: the process of material ageing (usually degradation) due to direct outdoor exposure
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