June 1990 Additives for Polwners

Colouring of polyurethanes

There are several methods of cleaning an ovation ABS process line in readiness for a new colour. The most common cleaning methods involve the use of a purging agent and the temporary adjustment of procose conditions. A purging agent will clean the equipment faster than if the old colour was left to pass through of its own accord. Typically, polystyrene or a special acrylic purging agent are fed into the hopper after the last of the shots of old material.

The higher viscosity of the special purging agent will effkctively push the older coloured mat&al through.

There are three basic types of colourant, which differ in the type of carrier used for the pigment& The first conaif& of a large amount of pigment blended directly with Magnum AE3S, and is generally mixed with natural polymer in a ratio of 15. The second comprises a large amount of pigment blended with a universal carrier (which must be tested for compatibility with Al%), mixed in let-down ratios in the order of 150 to 1:lOO. The third type is a liquid colourant, which con~iste of a high concentration of pigmenta in a liquid plasticizer. E3y meane of a simple peristaltic pump this liquid colourant is fed onto the

BCIWW through a small tube in the hopm throat. Typical concen~~o~ are l-25%.

Ilomtreant, @owPla3tlcs), 199~ (Spring), 3

This paper, originally pro~ntod at the “Fblyurethanes World Congress 1987,” discusses polymer-bound colouranta developed specifically for polyurethane sy&ems. These colouranta have low v&o&y, are non-settling, and are easy to handle, and land themselves well to automatic colour delivery syeteme. To date, an estimated 200 million pounds of ~l~~~e foam has been coloured in the US using these polymer-bound products.

J. Cell. Pi?&., 1989,2cr; (Mar./Apr.), 103-116

Degradable plastics Warner-Lambert Co. (USA), a pharmaceutical manufacturer, has introduced a developmental degradable plastics material wholly derived from starch. It is trade-named Novon, and whereas in currant commercial starch-based degradable plastice, the starch content is only about 6%, this mat&al usee starch as the base material. Its potential is in the rn~~a~~ of extruded products, etc. Starch derived from potatoes or corn is “destructured” to change its form by taking Borne cry&alMty out of the branched polymer segments.

Mod Plast. Ink, 1990,2Q (Apr.), 25-26

RdIlfOrced In the first part of this paper (KzuW8to~ 1989, 79, (2k$, polypropylene for motor ~334-~34~~ the reasons were given for the increased u8e of vehicles interior fittings tailored reinforced ~1~~~1~~ in motor vehicle interiors.

01990 Elsevier Sciince Fubl~~e~ Ltd. 3

Additives for Polvmers June 1990

Effectiveness of nucleating agents in polypropylene moulding compwnds

wle plastics and health risks

Smoke suppressant for Pufoams

Surface treatment of fire retardants

The most important features regarding design and processing were also discussed. In this second part, ~~en~tio~ for surface decoration of remforced polypropylene, as well a8 typical applications in the vehicle interior are presented.

Kumtstoffi 1990,8i& (Mar.), 342-347

Nucleators (nucleating agents) are often still chosen empirically. Frequently, the mode of operation of a nucleator and its interaction with other additives can be understood only through ~~~-level tests. It is shown by the example of nucleated and non-nucleated polypropylenes of different ~m~i~on that with the aid of d3ferential calorimetric measurements of crystallization behaviour, it is possible to obtain quickly and reliably information about the effectiveness and thermal stability of nucleators.

Ku.nststoff;e; 1994 @ (Mar.), 330-334

The Packaging Distributors Association in the UK has called for safety checks on degradable plastics packaging because it fears that plastics containing additives may become toxic, and should not be used until their safety has been proved.

In a recently issued statement, the PDA says that the health risks “far outweigh any possible environmental benefit” and that ‘recycling offers the best policy option for the future.”

The PDA says that its claims have the support of several associations and federations, including the British Flastics Federation (BIT) and the B&aging and Films Assooiation WA).

An additive for minimizing smoke and toxic gas emission from burning polyurethane foams, developed by Ciba-Geigy, is said to provide a low-cost route to safer flexible foams for furnishing and similar applications. CM undisclosed composition, the additive can be incorporated during manufacture into toluene diisocyanate (TDI) based RJR foams at a level of 10-150/b.

ln NBS smoke chamber tests, formulations containing the additive evolved less than 50!% of the smoke of untreated controls, and resulted in significant increases in unburnt c&r, and decreases in the liquid melt produced.

Mod Plaet. In&, 1990, PQ (Apr.), 61

Surface treatment of fire retardants of the hydrated inorganic compound type is critical in de&mining their effects on system properties. Martinswerk GmbH, W. Germany has developed a new treatment claimed to enhanoe me&a&al properties of ATH

4