Injection-moulded product

The RIM process was originally developed for the car industry for the production of bumpers, front ends, rear ends, fascia panels and instrument housings. At least one mass-produced American car has RIM body panels. For many of these products, however, a number of injection moulding products are competitive, including such diverse materials as polycarbonate/PBT blends and polypropylene/EPDM blends. In the shoe industry the RIM process has been used to make soling materials from semi-flexible polyurethane foams. 

One of the major innovations in recent years is the use of pulsed pressure through the gates to introduce and control the orientation of the structure (or fillers) in injection moulded products. A special manifold is attached to the machine nozzle as illustrated in Fig. 4.46. This diagram relates to the double live feed of melt although up to four pistons, capable of applying oscillating pressure may be used. 

In-mould labelling (IML) used for injection-moulded products and blow-moulded bottles is an alternative to self-adhesive or heat-transfer decoration, eliminating a finishing step. 

M. Bulters and A. Schepens, The Origin of the Surface Defect Slip-stick on Injection Moulded Products, Proc. Annu. Meet., American Institute of Chemical Engineering, Los Angeles, CA, 2000. 

Packaging, including foodservice, is easily the largest end use market for PLA with 70% of total consumption in 2005. Textile fibres account for an estimated 23% of total volumes. Other applications, with just 7% of total volumes, include speciality cards and sheet, agricultural products and a wide range of injection moulded products. 

Bomatic, Inc. has been a producer of plastic bottles and containers since 1969. The company serves the personal care, automotive, pharmaceutical, medical, lawn and garden, food, household cleaners, and industrial chemicals markets. Production capabilities include extrusion blow moulding and injection moulding products made from HDPE, PVC, LDPE, PET, PETG, polycarbonate, polystyrene, polypropylene, and polyurethane. 

Fitt, Italy s largest producer of PVC extruded and injection moulded products, recently presented a process for treating and using recycled post-use plastics from cables in the manufacture of pipe and moulded products. Tarkett Sommer, one of the world s largest PVC flooring manufacturers, processes almost 100,000 t/y of PVC at seven plants in Europe and is recycling about 8.4 tonnes of waste material a month. 

Today, PSM (HK) Co. Ltd. (a subsidiary of Engrowth Investments Limited incorporated in BVI) is one of the few companies which still use starch-filled plastics producing raw materials for injection moulded products usually for catering purposes [26]. 

Poly(butylene adipate-co-terephthalate) (PBAT) Some of its main applications are films (mulch, containers, bags), filaments, thermoformed and injection moulded products, and blown bottles. Two products in the market are Ecoflex (BASF, 14,000 t per year) and MaterBi (former EasterBio/Eastman, now Novamont, 15,0001 per year). For some applications, PBAT has a very low stiffness, and may be mixed with PITB or PEA, for example. It may also be mixed with thermoplastic starch [69, 71]. 

Protection from isocyanate vapours liberated during polyurethane manufacture is usually achieved by installing permanent exhaust ventilation units which either exhaust directly to the atmosphere or pass their exhaust fumes through scrubbers which extract the isocyanate vapour through a sodium carbonate spray tower before atmospheric exhaustion occurs. Continuous vertically positioned exhaust hoods are common where continuous conveyor lines are involved for localized extract situations, vertical down-draught or horizontal extract modes are much safer for operatives, being designed to remove all isocyanate vapour away from an operative s face and body. These latter situations apply particularly in the manufacture of cast-moulded and reaction-injection moulded products. 

LFA Douven, FPT Baaijens, HEH Meijer. The computation of properties of injection-moulded products. Progress in Polymer Science 20 403, 1995. 

An interesting application of this will be found in Chapter 3, where the plasticizer is used to control the Tg of PVC used in an injection-moulded product. 

We have now observed the importance of control of moulding conditions in the manufacture of two injection-moulded products. Next let us examine these process variables, and the way in which a modern machine gives control over them. In the account of the moulding of the support bracket and the film-spool end it became clear that control of injections, speed and pressure, were vital to the production of satisfactory mouldings. One other feature, not specifically discussed previously, but clearly also of vital importance, is the supply of consistent polymer melt delivered by the plasticizing unit at the specified rate. 

Tool design and manufacture is a very expensive business, and before a design is committed to it prototypes will usually be made and tested. They are made by machining from solid material of the same type as that proposed for the injection-moulded product, if available. Some care has to be exercised in results of tests on prototypes made in this way, because orientation of reinforcing fibres, or of polymer molecular chains in machined gears may be inconsistent with those in mouldings. 

Precipitated and 1-3 pm grades are used for rheological control in rotational moulded products and as extenders in injection moulded products. 

A. J. Vilela Pontes,Shrinkage and ejection forces in injection moulded products, Ph.D. thesis, Universidade do Minho,... 

Poly(butylene succinate) (PBS) is a commercially available, aUphatic polyester with mai interesting properties, including biodegradability melt processability, and thermal and chemical resistance [75-77]. PBS has excellent processability, so can be processed in the field of textiles into melt blow, multifilament, monofilament, flat, and split yam and also in the field of plasties into injection moulded products, thus being a promising pofymer for various potential applications [75]. 

Different polymer properties, that is the ability to form injection-moulded products, sheet, film, extruded products (tubes, fibres etc), all require different MWs. When the MW becomes greater than 10 then the polymer becomes difficult to process, since it will not melt and depolymerizes or decomposes when heated. These materials are fabricated by sintering (by applying pressure and heat). Examples include PTFE and ultra-high molecular weight PE (UHMWPE). 

The MW distribution (MWD) in chain polymers—particularly in polyolefins—also affects the properties, and therefore the application, of the polymer, e.g. broad MWD LDPE is used for extrusion products (films), whereas narrow MWD LDPE is used for injection-moulded products. Control of MWD can be achieved by catalyst and polymerization process conditions. 

These sort of aliphatic polyesters are claimed to have melting points above 90 C which give them suitable characteristics for commercial applications (i.e., films, injection moulded products) and the number average molecular weight (MW Mn) ranging from 45,000-65,000 D and MW ranging from 105,000-120,000 D. 

Table 3.5 Controlling shrinkage in injection-moulded products ...

The increase in the number of requirements made of injection moulded products has made it increasingly necessary to maintain a cavity filling balance in the mould, so that HR systems must match up to the following basic injection moulding principles ... 

BiopoF polymers are currently the only commercially available bacterially derived polyhydroxyalkanoates. The polymers can be processed on most types of conventional thermoplastic melt-processing equipment. Examples of product forms include a wide range of injection-moulded products and extrusion blow-moulded bottles. Foamed products can also be produced [60]. 

Ratto et al. (1999) has examined poly butylenes sueeinate adipate (PBSA) terpolymer/granular starch composites for blown films and showed they could produce good film tensile properties and control biodegradation with granular starch addition. Thermoplastic starch/cellulose fibre extrudates and injection moulded products were examined by Funke et al. (1998) and they showed a reduction in water adsorption with increasing fibre content. Work by Halley et al. (2001) examined the use of thermoplastic starch-polyester blends for use in mulch film applications noting excellent field performance and biodegradability for these materials. 

---