(Fundamentals of Modern Manufacturing: Materials, Processes, and Systems, Mikell P. Groover, p. 274)
3) Masterbatch (new-better) (material)
Dry Masterbatch
A masrerbatch, otherwise known as a colour concentrate, is intended for dilution with
uncolored (‘virgin’ or ‘natural’) polymer prior to conversion. Loadings of 20-50% are
common in the industry, the balance being made up of other colorants, universal or
polymer-specific carriers and various additives, such as antistatic or flame retarding agents.
Typical metal pigment masterbatch concentrations are 1-5% wlw on polymer, the exact
level being heavily dependent on the pigment's particle size, density and concentration in
the masterlvatch.
Mastcrbarch is divided into dry and liquid types. The latter is small in relation to the
former. As entry barriers were low and distribution tended to be localised, there were
until recently a large number of masterbatch makers, over 200 in Europe alone. More
recently that number has reduced through acquisitions by the major players. Pan-
European converters are increasingly looking for pan-European suppliers who can
provide a local supply, technical support and innovation via local subsidiaries. The
total Western European masterbatch marltet in 1996 was estimated at 550,000 tonnes,
worth around £1 billion, the maiority being white and black . The metallic pigmented
sector probably accounts for less than 1% of the total, but is growing rapidly. So also
is masterbatch in general, mostly at the expense of compound. Masterhatch coloration
of previously difficult polymers such as acrylonitrile-butadiene-styrene (ABS) has become
much more reliable.
Liquid Masterbatch
As the name implies, liquid masterbatch consists of colorants and optionally additives,
incorporated in liquid carriers to give a fairly viscous pre-dispersion. The carrier, which
is incorporated in the polymer, is often a plasticiser.
Liquid masterbatclt is added to the polymer by dosing pumps. Given suitable equipment,
the technique allows very accurate addition levels and a high level of dispersion. Early
drawbacks in clean down l the displacement of a (coloured) polymer from the equipment
by using another polymer or else allowing it to run out) and colour change have also
been largely overcome.
Metal pigments present some difficulties, due to the combination of particle size and
density. These conspire to induce settling in transit and in delivery lines. Nevertheless,
lighter flake pigments such as aluminium are successfully used in smaller particle sizes.
(Metallic pigments in polymers, Ian Wheeler, Rapra Technology Limited, 1999, page: 59-60)
Masterbatch: (old)
There are three states of aggregation - gaseous, liquid, and solid. Gaseous colorants are not known; consequently either a liquid or a solid color preperation can be chosen for the coloring of plastics. There are two possibilities for a solid color preparation, either a powdery or a granulated form, the latter known as a masterbach.
A masterbach is today the most preferred type of preparation, well documented by the large volume of sales.
A masterbach consists of:
- Polymer as carrier
- Colorants
- Dispersing agent
- If necessary; additives such as stabilizers, nucleating agents, antisatic agents, lubrications, and so forth
(Müller, A., Coloring of Plastics: Fundamentals, colorants, preparations, p. 37,38)
4) Synthetic Rubber (new-better) (material)
Although synthetic elastomers use a number of monomers identical to those
of plastics for their synthesis, such as ethylene, propylene, butadiene and
styrene, they are different in their physical properties, synthesis processes
and transformations.
The main qualities desired in an elastomer are high elasticity, high tensile
strength, low energy dissipation by hysteresis, good abrasion resistance, good
ageing behavior, and good resistance to chemical degradation.
Any polymer substance which, after being stretched to at least twice its
initial dimension, can rapidly recover its initial size after the release of the
stretching force, satisfies the definition of an elastomer. However. very few
polymers, if any, actually correspond to this definition in the raw state. The
macromolecules which form a viscous mass slide over each other under the
effect of a stretching force. If this force is removed. the substance in fact
does not return to its initial state. The insoluble three-dimensional network
which meets the definition of the rubbery state is obtained by a chemical
reaction: vulcanization. This operation is generally conducted by the addition
of chemical substances such as sulfur. Since most synthetic elastomers are
unsaturated compounds, the sulfur is added to the a of the double bond. but
the unsaturation is not eliminated. This change is irreversible, and this char-
acteristic is related to the transformation undergone by thermosetting polymers
.
(
Synthetic rubbers:
processes and economic data, Jean-Pierre Arlie, 1992, page: 3)
Syntetic Rubber (Synthetic Rubber) (28,04 20,43) (old)
Today, the tonnage of synthetic rubbers is more than three times that of natural rubber. Development of these synthetic materials was motivated largely by the world wars when NR was difficult to obtain. The most important of the synthetics is styrene-butadiene rubber (SBR), a copolymer of butadiene and styrene. As with most other polymers, the predominant raw material fofr the synthetic rubbers is petroleum. Only the synthetic rubbers of greatest commercial importance are discussed here. Market share data are for total volume of natural and synthetic rubbers. About 10% of total volume of rubber production is reclaimed; thus, total tonnages do not sum to 100%.
(Fundamentals of Modern Manufacturing: Materials, Processes, and Systems, Yazar: Mikell P. Groover, Page 178-179)
5) Natural Rubber(new-better) (material)
As IS WELL KNOWN, natural rubber was the only polymer from which rubber
products could be made until the first synthetic rubber, Neoprene, was
invented and became commercialized in the 1930s. Natural rubber was the
only polymer used in large ticket items such as tires until the Second World
War. When the natural rubber supply was cut off in the early 1940s, the
mainstay synthetic, SBR (Styrene Butadiene Rubber) was developed and
cormnercialized.
Natural rubber is an agricultural product. Tests to determine the so
called "quality" of natural rubber parallel the increased sophistication and
growth of the rubber industry. Tests were developed to distinguish good
from bad. These tests, however, were mostly used internally by large com-
panies to assist in product development. In other words, they were the tools
that compounders used and had little commercial impact because natural
rubber was bought and sold only against visual standards. The introduction
of the technically specified rubber (TSR) concept by Malaysia in the late 19603
dianged the commercial aspect of natural rubber. ASTM tests became im-
portant, and were referenced in commercial purchase contracts. Referee lab-
oratories were established on most continents. Also up to the 1970s there
were 22 official grades of natural rubber, mostly differentiated by different
production and packing methods. All of them were visually inspected to de-
termine conformance to requirements. Table 3.1 describes some of the more
commonly used grades. All the ribbed smoked sheets are visually graded to-
day and the purchase contracts stipulate accordingly.
(
Basic rubber testing:
selecting methods for a rubber test program, John S. Dick, 2003, page: 61,62)
Natural Rubber (28,04 20,25) (old)Natural rubber occurs as a latex that may be tapped or removed from the rubber bearing plant or tree. The latex is subsequently coagulated and the precipitated material collected. Originally, natural rubber was harvested in its wild state from South America, especially from Hevea brasileanus trees. The Hevea tree is not a unique source of rubber. Mant other plants from the South American regions produce rubbery as well as plastic materials. It is very possible that the hull balls obtained by Columbus and the conQuistadors did not derive from Hevea. Most efforts toward commercially producing natural rubber from other plants have focused on the Guayule bushes of the Mexican desert.(Rubber processing: technology, materials, principles, Yazar: James lindsay White)
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