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Rohm and Haas announces powder coatings price increase
Additives for Polymers
Rohm and Haas announces powder coatings price increase In the USA, Morton Powder Coatings, a Rohm and Haas company, has announced a 4% price increase in nylon powder coating products, and a 3% price increase on all stock products. This increase is in response to rising costs of raw materials in areas, such as epoxy, polyester, nylon resins, pigments and additives, claims the company.
Contact: Rohm and Haas Co, 100 Independence Mall West, Philadelphia, PA 19106-2399, USA; tel: +1-215 592 3000,fax: +1-215 592 3377.
TECHNICAL BRIEFS Use of polyurethanes as charforming agents in PP intumescent formulations Polyolefinic materials are increasingly used in building, for flooring, and in electrical applications, in cables and wires. These applications require a high degree of flame 'retardancy'. The most practical approach to enhance fire-safety performance is to incorporate flame-retardant (FR) additives in the polymeric matrix. The use of intumescent additives allows both the fire properties and mechanical behaviour of the materials to be optimised. On heating, fire-retardant materials form foamed, cellular charred layers on their surface, which protect the underlying material from the action of the heat flux or flames. The mechanism is based on slowing up heat and mass transfer between the gas phase and the condensed phase. Polyols, such as pentaerythritol, were first used as carbonisation agents in association with ammonium phosphates in polymeric intumescent systems. Recently, polymers (which show a natural charring when heated) have been substituted for the polyols, because of the migration of the polyols throughout the material, and the easy hydrolysis of the products of their reaction with phosphate species (formation of phosphoric acid esters and of carbonised species) which takes place during the material processing and
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January 2001
subsequent diffusion (exudation) of a part of the additives throughout the polymeric matrix. A typical example is the use of polyamide-6 and a hybrid polyamide-6/clay nanocomposite which act as charring polymers in blends with different polymer matrices. The effect of using charring polymers in association with an acid source such as ammonium polyphosphate (APP) may result in an improvement of the compatibility between the different components, leading to a limitation of the APP exudation, that is, the blooming effect. The use of thermoplastic polyurethanes (TPU) as carbonisation agents in a polypropylene (PP) matrix has already been investigated by research work. This has revealed that small amounts of a PU associated with APP are able to promote char-formation during the combustion of PP. The FR performance and the thermal stability of an ethylene-polypropylene rubber (EPR)/TPU/ APP blend has also been previously studied. TPU/APP additives in EPR increase the values with a synergetic effect (limiting oxygen index (LOI) = 28 vol%) using a 1:3 TPU/APP ratio. Research work, the details of which appear in Polymer International (Vol. 49, pp. 1115-1124) compares the fire behaviour of PP and of several FR PP/TPU/APP materials. The influence of the chemical structure of TPU has been investigated by using two different TPU series which differ in the nature of the polyol used for their syntheses: polyols in the poly-addition process are either polyether or polyester polyols. Generally, a TPU synthesised from polyether shows a higher degree of phase separation and, as a consequence, its hard segment domains (diol + diisocyanate) also tend to be larger and more complex than those found in a polyesterbased TPU. Moreover, the influence of the hard segment content is studied in this work using different diol + diisocyanate/polyol ratios. The mechanical properties of the blends are then investigated, considering both performances and morphologies of the samples. The following steps of this work concern a blend selected from the series because of its good FR and mechanical properties. Its morphology is first studied and then an evaluation of the dynamic properties of this PP/TPU/APP system is reported. The measurement of the material expansion, using a
©2001 Elsevier Science
Rohm and Haas announces powder coatings price increase In the USA, Morton Powder Coatings, a Rohm and Haas company, has announced a 4% price increase in nylon powder coating products, and a 3% price increase on all stock products. This increase is in response to rising costs of raw materials in areas, such as epoxy, polyester, nylon resins, pigments and additives, claims the company.
Contact: Rohm and Haas Co, 100 Independence Mall West, Philadelphia, PA 19106-2399, USA; tel: +1-215 592 3000,fax: +1-215 592 3377.
TECHNICAL BRIEFS Use of polyurethanes as charforming agents in PP intumescent formulations Polyolefinic materials are increasingly used in building, for flooring, and in electrical applications, in cables and wires. These applications require a high degree of flame 'retardancy'. The most practical approach to enhance fire-safety performance is to incorporate flame-retardant (FR) additives in the polymeric matrix. The use of intumescent additives allows both the fire properties and mechanical behaviour of the materials to be optimised. On heating, fire-retardant materials form foamed, cellular charred layers on their surface, which protect the underlying material from the action of the heat flux or flames. The mechanism is based on slowing up heat and mass transfer between the gas phase and the condensed phase. Polyols, such as pentaerythritol, were first used as carbonisation agents in association with ammonium phosphates in polymeric intumescent systems. Recently, polymers (which show a natural charring when heated) have been substituted for the polyols, because of the migration of the polyols throughout the material, and the easy hydrolysis of the products of their reaction with phosphate species (formation of phosphoric acid esters and of carbonised species) which takes place during the material processing and
10
January 2001
subsequent diffusion (exudation) of a part of the additives throughout the polymeric matrix. A typical example is the use of polyamide-6 and a hybrid polyamide-6/clay nanocomposite which act as charring polymers in blends with different polymer matrices. The effect of using charring polymers in association with an acid source such as ammonium polyphosphate (APP) may result in an improvement of the compatibility between the different components, leading to a limitation of the APP exudation, that is, the blooming effect. The use of thermoplastic polyurethanes (TPU) as carbonisation agents in a polypropylene (PP) matrix has already been investigated by research work. This has revealed that small amounts of a PU associated with APP are able to promote char-formation during the combustion of PP. The FR performance and the thermal stability of an ethylene-polypropylene rubber (EPR)/TPU/ APP blend has also been previously studied. TPU/APP additives in EPR increase the values with a synergetic effect (limiting oxygen index (LOI) = 28 vol%) using a 1:3 TPU/APP ratio. Research work, the details of which appear in Polymer International (Vol. 49, pp. 1115-1124) compares the fire behaviour of PP and of several FR PP/TPU/APP materials. The influence of the chemical structure of TPU has been investigated by using two different TPU series which differ in the nature of the polyol used for their syntheses: polyols in the poly-addition process are either polyether or polyester polyols. Generally, a TPU synthesised from polyether shows a higher degree of phase separation and, as a consequence, its hard segment domains (diol + diisocyanate) also tend to be larger and more complex than those found in a polyesterbased TPU. Moreover, the influence of the hard segment content is studied in this work using different diol + diisocyanate/polyol ratios. The mechanical properties of the blends are then investigated, considering both performances and morphologies of the samples. The following steps of this work concern a blend selected from the series because of its good FR and mechanical properties. Its morphology is first studied and then an evaluation of the dynamic properties of this PP/TPU/APP system is reported. The measurement of the material expansion, using a
©2001 Elsevier Science