Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
  • C08J9/0014—Use of organic additives
  • C08J9/0023—Use of organic additives containing oxygen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2325/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Derivatives of such polymers

Definitions

• This, invention relates to improved expandable and expanded alkenyl aromatic polymer particles and methods for preparing these expandable and expanded particles.
• Alkenyl aromatic polymer particles or beads which are expandable or expanded, are known to be highly desirable for a number of uses.
• One highly desirable use is protection in packaging articles for shipping.
• Another use for the expandable alkenyl aromatic polymer particles is as molding material.
• expanded alkenyl aromatic polymer particles are highly desirable, they suffer from a substantial and significant problem of the high cost of shipping in the expanded state due to their very low bulk density. It is therefore generally desirable to ship a product having a maximum bulk density, as an expandable alkenyl aromatic polymer particle, and to subsequently expand the particle at or near the point of use into the desired form such as expanded alkenyl aromatic polymer packaging particles or expanded and molded alkenyl aromatic polymer foamed objects.
• blowing agent used to prepare the expandable and expanded alkenyl aromatic polymer particles, especially if the blowing agent is a blowing agent which 5 is believed to cause damage to the earth's atmospheric laye .
• the present invention provides expandable particles comprising an alkenyl aromatic polymer, a 0 volatile fluid blowing agent and a density modifier in an amount from 0.005 percent to 0.5 percent by weight of the total mixture.
• the present invention provides also expanded particles comprising an alkenyl aromatic polymer and a density modifier in an amount from 0.005 5 percent to 0.5 percent by weight of the total mixture.
• alkenyl aromatic polymer being a polymer or copolymer having in chemically combined form at least 50 percent by weight styrene.
• the expandable particles of the present invention are thermoplastic resinous materials containing a density modifier and a blowing agent.
• the expanded particles of the present invention are the
• thermoplastic resinous materials containing a density modifier.
• the present invention provides expandable and expanded alkenyl aromatic polymer particles with the e - term alkenyl aromatic polymer including polymers or copolymers having in chemically combined form at least 50 percent by weight of at least one alkenyl aromatic compound having the general formula
• Ar represents an aromatic hydrocarbon radical or an aromatic halohydrocarbon radical of the benzene _,,- series and R is hydrogen or the methyl radical.
• alkenyl aromatic resins examples include the solid homopolymers of styrene, ⁇ -methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, ar-ethylstyrene, ar-vinylxylene, ar-chlorostyrene, or ar-bromostyrene; and the solid copolymers of two or more of such alkenyl aromatic compounds with minor amounts of other readily polymerizable olefinic compounds such as divinylbenzene, methylmethacrylate or acrylonitrile.
• the alkenyl aromatic polymer is polystyrene having an weight-average molecular weight (M w ) of 100,000 to 300,000.
• the volatile fluid foaming agents can be gases such as carbon dioxide, a saturated aliphatic hydrocarbon such as butane, isobutane, pentane, isopentane, neopentane, hexane, heptane or mixtures of one or more aliphatic hydrocarbons having a molecular weight of at least 65 and a boiling point not higher than 95° centigrade (C) at 760 millimeters absolute pressure.
• Other suitable fluid foaming agents are those halogenated hydrocarbons generally known in the art.
• the volatile fluid foaming agent usually is employed in amounts corresponding to from 5 to 15 percent of the weight of the total formulation. After expansion the volatile fluid blowing agent may .or may not be retained in the expanded alkenyl aromatic polymer particle.
• alkenyl aromatic polymer/blowing agent mixture other additives which are known in the art such as fire retardants, stabilizers, fillers, anti-static agents and colorants. Also those materials known as "cell-size control additives" may be incorporated into the alkenyl aromatic polymer/blowing agent mixture for use in the production of uniform extruded foam prior to extrusion from a die.
• expandable alkenyl aromatic polymer particles produced may be in any form, particularly preferred are those forms suitable for packaging or dunnage purposes and those forms which after expansion are suitable for molding purposes.
• the present invention requires the inclusion of a density modifier in a heat-plastified alkenyl aromatic polymer/blowing agent mixture in an amount of from 0.005 weight percent to 0.5 weight percent by total mixture weight.
• the preferred ranges are from 0.01 to 0.3 weight percent by total mixture weight.
• the "density modifier” is defined as a compound providing thermal stability for the alkenyl aromatic polymer at extrusion and expansion conditions and which is also a liquid plasticizer at expansion conditions.
• density modifiers include, but are not limited to, octadecyl 3»5-di-tert-butyl-4-hydroxyhydrocinnamate and ethylene bis(oxyethylene) bis(3-tert-butyl-4-hydroxy-5- methylhydrocinnamate) .
• CFC-11 is trichlorofluoromethane.
• Blowing Agent 8.8 percent (80 percent/20 percent CFC-11 /Pentane - weight percents based on weight of blowing agent mixture)
• the Example formulation differs only in the octadecyl 3»5-di-tert-butyl-4-hydroxyhydrocinnamate being present in an amount of about 0.2 percent and the reduced amount of about 8.8 percent blowing agent, instead of 10.1 percent to 10.3 percent blowing agent as is in the Comparative Example.
• After producing these expandable polystyrene particles these samples are then expanded in an atmospheric steam chamber for controlled periods of time at a temperature generally ranging from about 85°C to about 105°C, preferably about 100°C.
• the expansion scheme will consist of a 3 minute exposure followed by a 24 hour aging time at room conditions, then a second 3 minute exposure followed by a second 24 hour aging time, and then a third 1-1/2 minute exposure and a third 24 hour aging time. After this third aging period the bulk densities of the expanded polystyrene particles are measured. This expansion scheme is followed to produce expanded polystyrene particles.
• the Comparative Example expanded polystyrene particle bulk densities range from 0.28 to 0.33 pounds per cubic foot (4.5-5.3 kg/m ⁇ ).
• the Example expanded polystyrene particles of the present invention have a bulk density of about 0.26 pounds per cubic foot (4.2 g/ ⁇ -3).
• blowing agent The ability to maintain an equivalent density with a decreased amount of blowing agent is found to be a result solely from the inclusion of the octadecyl 3»5- di-tert-butyl-4-hydroxyhydrooinnamate in an amount of about 0.2 percent, as stated in the Example into the expandable polystyrene particle formulation. Generally a blowing agent decrease will produce an expanded polystyrene particle of higher density than when less blowing agent is included, not a lower density.

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Emergency Medicine (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)

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• 1989
  • 1989-06-13 JP JP50863189A patent/JPH04500225A/ja active Pending
  • 1989-06-13 WO PCT/US1989/002576 patent/WO1990002151A1/en not_active Application Discontinuation
  • 1989-06-13 EP EP19890909362 patent/EP0430998A4/en not_active Withdrawn

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