Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/16—Nitrogen-containing compounds
  • C08K5/34—Heterocyclic compounds having nitrogen in the ring
  • C08K5/3467—Heterocyclic compounds having nitrogen in the ring having more than two nitrogen atoms in the ring
  • C08K5/3477—Six-membered rings
  • C08K5/3492—Triazines
  • C08K5/34928—Salts
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/20—Oxides; Hydroxides
  • C08K3/22—Oxides; Hydroxides of metals
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/32—Phosphorus-containing compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/38—Boron-containing compounds

Definitions

• the present invention relates to a flame retardant polyolefin blend and a process for the preparation thereof.
• the blends of this invention neither drip nor glow when ignited and pass UL94 V- 0 test with low emission of nontoxic fumes.
• Background of the Invention The concept of fire-retardancy is remarkably old. Herodotus, the Greek Historian, in 484-431 BC recorded that the Egyptians imparted fire-resistance to wood by soaking it in a solution of alum (potassium aluminum sulfate). Vitruvius in the 1 st Century BC described some military applications of fire retardant materials such as plaster of clay reinforced with hair.
• Wild was issued a British patent in 1735 for his process of treating wood with a mixture of alum, ferrous sulfate and borax (sodium tetra borate decahydrate). And Gay-Lussac in 1821 showed that a solution of ammonium phosphate, ammonium chloride and borax acts as a fire retardant for wood.
• the key ingredients are the elements from Group HI (B and Al) of the periodic table. Even at the beginning of the 21 st Century, with so much of research activity for better fire retardants, the most effective elements are still found in Group: 111 (B and Al), V (N , P and Sb) and VII (Cl and Br).
• FR flame retardant
• Certain compounds such as melamine (2,4,5-triamino- 1,3,5-triazine) and its derivatives are also found to be effective flame-retardants, because of their ability to employ various modes of flame retardant action.
• the growing interest for melamine based flame retardants is further more driven by the particular advantages these products offer over existing flame retardants: cost effective, low smoke density and toxicity, low corrosion and safe handling.
• melamine and/or its derivatives when used in conjunction with an inorganic hydroxide was found to impart flame retardancy to the polyolefms.
• Inorganic non-halogen FR compounds such as zinc borate; ammonium phosphate and organic phosphorous-based chemicals are also being used for providing flame resistivity to polymers.
• US Patent 3,936,416 (1976) issued to Brady described a process for preparing no burning, no dripping, char-forming polypropylene composition with melamine pyrophosphate dipentacrythritol and other systems.
• US Patent 4,010,137 (1977) granted to Brady again illustrates phosphorus containing flame retardant along with melamine for synthetic resins.
• the present invention provides a fire-resistant polyolefin blend comprising a polyolefin and melamine or it's derivative along with a melt flow improver and having melt flow index in the range: 2 - 15g/10 min. when tested according to ASTM D1238.
• the base polymer of the polyolefin blend is a homopolymer of propylene or ethylene, or a block or a random copolymer of ethylene and propylene and is present in a concentration range of from 30 to 88 wt.%.
• the blend comprises of (i) a polyolefin base polymer (ii) melamine or its derivative (iii) a flame retardant and (iv) a compatibilizer.
• the polyolefin base polymer is selected from an isotactic or syndiotactic polypropylene homopolymer or a blend of the two; said melamine derivative is selected from melamine cyanurate or melamine phosphate; said flame retardant is selected from magnesium hydroxide and/or aluminum trihydroxide, zinc borate and ammonium phosphate and said compatibilizer comprises a maleic anhydride grafted polypropylene (MAH-g-PP) or a suitable organo silane.
• MAH-g-PP maleic anhydride grafted polypropylene
• said polyolefin polymer has a melt flow index in the range of 12 to 40 g/10 min. when tested at 230°C at 2.16 kg load (according to ASTM D1238).
• said melamine or its derivative is present in the concentration range of 10 to 50wt %.
• said flame retardant preferably an inorganic hydroxide, is present in the concentration range of 2 to lOwt %.
• the blend additionally includes a processing aid such as a fluoroelastomer in the concentration range of 1 to 2wt %.
• the blend additionally includes an antioxidant, preferably trinonyl phenylphosphites, in a concentration range of 0-3 wt %.
• an antioxidant preferably trinonyl phenylphosphites.
• This invention also provides a process for preparation of polypropylene blends with melamine and/or its derivatives along with other ingredients extruded in a twin screw extruder or a Buss co-kneader all together or in separate batches, wherein for example, twin screw extruder temperature is maintained in the range: 180 - 250°C and the screws are rotated at a speed of: 50 - 100 rpm.
• the FR blends qualify the flame retardancy test, UL94 V-0.
• polyolefin polymer received in the form of granules/spheri-beads, after adequately adding the stabilizers and anti-oxidants after polymerization in the plant.
• polyolefin is used to refer to polypropylene homopolymer, polyethylene (such as low density polyethylene, LDPE, high density polyethylene, HDPE) and reactor copolymers (both random and block copolymers) of propylene and ethylene.
• the copolymer granules are dehumidified at 80 (+/-) 5°C for two hours, in an oven, preferably, with an air circulation facility.
• melt blending is to uniformly disperse melamine or melamine derivative and other additives throughout the polymer matrix. This is achieved by means of a twin-screw extruder, or a Buss co-kneader with a specially designed screw profile that facilitates intimate mixing of the ingredients.
• PO polyolefin
• melamine/melamine derivative metal hydroxide
• fluoroelastomer fluoroelastomer
• a compatibilizer a compatibilizer
• PO 30-88 wt%
• melamine/melamine derivative 10-50wt %
• metal hydroxide 2-10 wt%
• MAH-g-PP maleic anhydride - grafted - polypropylene
• organo silane compatibilizer 0-10wt% all together 100% by weight, and in addition other additives viz.
• a Buss co-kneader or a co- rotating twin screw extruder with a preferred screw profile that would enhance intimate mixing of ingredients was used under the following conditions: temperature range: 180-250 °C, screw speed: 50-100 rpm, residence time: 2-5 min.
• the extrudates were dipped in circulating cold water and later chopped into granules of length 2-4 mm.
• the extrudates granules were dried and were injection molded into ASTM standard test specimens for evaluating various performance properties such as burning test, tensile, flexural, Izod impact, heat deflection temperature etc.
• the dried granules were also used to measure melt flow index, thermal stability (using thermo gravimetric analyzer).
• Computer controlled injection molding machine was used with temperature profile (with four heating zones) in the temperature range: 180 - 230°C, injection pressure (applied in six stages): 15-125 kg/cm 2 , injection time (in six stage): 2.5 - 5.0 sec, with screw speed (in two stages) in the range: 80-100 rpm.
• Standard test specimens were used for evaluating various performance properties of the compounds following the ASTM standard test methods.
• Melamine based flame retardants are growing in their popularity as end-use customers discover their virtues, which includes low smoke and toxic gas evolution in fire situations, low corrosion to metals such as those used in extruders and molding machines and low corrosion to metal contacts or wires in electrical and electronic applications. These virtues of melamine-based flame-retardants are inherent in their flame retarding mechanism: multiple actions such as endothermic decomposition and reactions in the solid and gas phases in fire situations. These nitrogen based environment friendly flame-retardants also offer a way to reuse/recycle the polyolefin blends. The present invention will now be illustrated with reference to the following non-restrictive Examples.
• Example - 1 Dried granules of polypropylene homopolymer (50-75 wt %) were mixed with dry melamine or melamine based compound, in the concentration range: 20-40 wt % and metal hydroxide in the concentration range: 2-10 wt% in a high-speed sigma- mixer.
• the dry mixture was extruded in a Buss co-kneader with a preferred screw profile.
• the extrusion was carried out with the extruder operating in the temperature range: 150 -215°C with screw rotating at 60 rpm.
• the extrudate strands (say Blend-A) were dipped in a trough of water that was circulated in order to keep them cool.
• Blend-A The dry granules of Blend-A were injection molded to get ASTM standard test specimens using FRK-85, Klockner-Windsor injection molding machine under the molding conditions given below in Table -I.
• Table -I Typical injection molding condition for preparing ASTM test specimens No. Processing Parameter Units Typical Value 1. Injection pressure kg/cm 2 70-120 2. Temperature maintained °C 150-230 3. Injection time sec. 3-10
• Example-2 Pre-dried granules of copolymer of propylene and ethylene (PPCP) (50-80 wt%), melamine/ melamine derivative (20-45 wt%) and Aluminum tri-hydroxide (0-5 wt%) were mixed in a high-speed sigma mixer along with other additives viz. processing aid and antioxidants.
• the entire dry blended mixture was melt extruded in a Buss co-kneader as described in Example-1, using similar extrusion conditions and the granules of this blend (say Blend-B) were later injection molded on a Klockner- Windsor machine (FRK-85), under identical conditions described previously.
• the injection molded ASTM test specimens were used to evaluate the performance properties of the Blend-B given in Table-Ill. Table -IE. Typical properties of Blend-B
• Example-3 Dried granules of PPCP (50-70wt.%) were mixed with dried melamine (20-40 wt.%) and Aluminum tri hydrate (5-10 wt.%).To this mixture was added MAH-g-PP (2-5 wt.%), processing aid, antioxidants and other additives mentioned above. The ingredients were mixed thoroughly in a high speed Sigma mixer and extruded in a similar fashion as described in Example-1, on a Buss co-kneader. The extrudate strands (say Blend-C) was granulated following the same procedure as in the previous experiment. ASTM standard test specimens were prepared using the same injection- molding machine under identical conditions described earlier. The typical properties of Blend-C are given in Table-IV.

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• 2003
  • 2003-11-21 WO PCT/IN2003/000365 patent/WO2005049716A1/en not_active Application Discontinuation
  • 2003-11-21 AU AU2003304555A patent/AU2003304555A1/en not_active Abandoned
  • 2003-11-21 EP EP03808345A patent/EP1687367A1/de not_active Withdrawn

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