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
  • C08J9/16—Making expandable particles
  • C08J9/20—Making expandable particles by suspension polymerisation in the presence of the blowing agent
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F12/00—Homopolymers and 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
  • C08F12/02—Monomers containing only one unsaturated aliphatic radical
  • C08F12/04—Monomers containing only one unsaturated aliphatic radical containing one ring
  • C08F12/06—Hydrocarbons
  • C08F12/08—Styrene
• • 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
  • C08J9/0066—Use of inorganic compounding ingredients
• • 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
  • C08J2201/00—Foams characterised by the foaming process
  • C08J2201/02—Foams characterised by the foaming process characterised by mechanical pre- or post-treatments
  • C08J2201/034—Post-expanding of foam beads or sheets
• • 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
  • C08J2325/02—Homopolymers or copolymers of hydrocarbons
  • C08J2325/04—Homopolymers or copolymers of styrene
  • C08J2325/06—Polystyrene

Definitions

• the present invention relates to polystyrene beads.
• the invention relates to the production of expandable polystyrene beads with insulating properties.
• the invention relates to a method according to the preamble portion of claim 1 as well as expandable polystyrene beads according to the preamble of claim 16 and uses thereof.
• Polystyrene beads are traditionally produced by the suspension polymerisation of styrene, which involves the mechanical dispersion of styrene in water and polymerisation of the resultant monomer droplets by use of a monomer-soluble initiator. Styrene is kept in suspension by continuous agitation and the use of stabilisers. Polystyrene is obtained in the form of beads.
• Expanded articles have been used for some time, for example to improve the thermal insulation of buildings.
• these articles are prepared by either extrusion or moulding through the swelling of polymer beads.
• Additives can be used to improve the desired properties of the articles.
• hexabromocyclododecane is used in typically polystyrene building insulation, both extruded and expanded as a flame-retarding agent.
• Expanded polystyrene (EPS) is becoming increasingly common for use in such articles.
• EPS is a rigid and tough, closed-cell foam, generally made of pre-expanded polystyrene beads.
• Common uses of these EPS beads include moulded sheets for building insulation and packing material for cushioning fragile items. The latest advances in the technology related to these EPS beads concern improving the thermal insulation of the articles prepared from the beads.
• Athermanous particles such as graphite and carbon black, are incorporated into the polystyrene to produce what is known as grey EPS.
• grey EPS moulded articles is disclosed in EP 0 620 246.
• Athermanous material can be added directly to the
• the present invention relates to methods of producing polystyrene beads, wherein styrene monomers, and optionally co-monomers are subjected to a polymerisation reaction in the presence of athermanous material and a polymerisation initiator to produce polystyrene beads. It has been found in connection with the present invention that particularly good thermal insulation properties are obtained by incorporating into expandable polystyrene beads of athermanous carbon materials consisting predominantly of particles having an average particle size in the range of about 0.1 to 2.0 um, in particular about 0.5 to 1.9 um, advantageously 0.7 to 1.5 um.
• Athermanous particles of the indicated kind are, according to the present invention, carbon particles having a non-spherical form, preferably particles in the shape of cones, such as open or hollow cones.
• the preferred particles are formed by overlapping carbon layers.
• the athermanous material used in expandable polystyrene beads comprises carbon particles having a conical shape, in particular at least 1 %, suitably 10 %, for example at least 25 %, by weight of the carbon particles have the shape of cones, such as open cones.
• Disc-shaped particles are present to an extent of 99 % or less.
• the particles are formed by overlapping carbon layers. The particles have a largest dimension of less than 5 micrometers.
• Particles of the indicated kind can be produced by plasma torch processes, wherein a hydrocarbon composition is combusted using a plasma flow to form carbon particles.
• the expandable polystyrene particles or beads are characterised by what is stated in the characterising part of claim 15.
• Expanded polystyrene polymers are characterized by what is stated in claim 22.
• Particularly preferred expanded polystyrene polymers are characterized as being obtained by expanding polymer beads produced by a method according to any of claims 1 to 14, polystyrene particles according to claim 15 or expandable polystyrene particles according to any of claims 16 to 21.
• Articles, such as heat insulation boards, formed by polystyrene are characterized 28. Considerable benefits are reached with the aid of the present invention.
• the present invention provides expandable polymer beads that can be used to prepare foamed articles of low thermal conductivity.
• the present athermanous particles are producible by inexpensive methods, e.g. the plasma torch process mentioned above. Such methods give rise to particles of a narrow particle size distribution which will reduce the extent to which the particles need to be subjected to process steps such as classification.
• the particles give properties of thermal insulation equal to over even better than those of graphite.
• a material according to the present invention will achieve the same thermal conductivity as a conventional material at a significantly lower density (i.e. with a smaller consumption of material).
• the present technology comprises a method of producing expandable polystyrene beads or particles containing athermanous particles.
• beads and “particles” will be used interchangeably to designate polystyrene particles obtained by the herein described method.
• the method according to the present technology is based on polymerisation of styrene monomers which are subjected to polymerization in the presence of athermanous particles.
• the athermanous particles comprise carbon particles which exhibit a conical shape and formed by overlapping carbon layers, with a largest dimension of less than 5 micrometers.
• conical carbon particles comprise particles having the shape of hollow open cones.
• the athermanous particles comprise particles which have a generally disc-shaped form.
• the carbon particles are formed by overlapping carbon layers.
• the individual overlapping carbon layers have a thickness of up to 200 nm, in particular 100 nm or less. Preferably the thickness is 10 nm to 100 nm.
• the thicknesses of the layer is 100 to 200 nm.
• a typical thickness for this embodiment is about 150 nm, i.e. 150 ⁇ 25 nm. It would appear that overlapping carbon layers will assist in efficiently absorbing energy (photons).
• the athermanous particles can be produced by a plasma torch process, wherein a hydrocarbon composition is combusted using a plasma flow to form carbon black particles.
• a plasma torch process wherein a hydrocarbon composition is combusted using a plasma flow to form carbon black particles.
• a plasma torch process wherein a hydrocarbon composition is combusted using a plasma flow to form carbon black particles.
• One suitable process is described in W09842621 which discloses a high-yield method of producing carbon particles which comprise overlapping carbon layers.
• hydrocarbons are decomposed into carbon and hydrogen by plasma.
• a plasma arc is formed in a plasma generator which consists of tubular electrodes.
• the hydrocarbons are introduced into the decomposition reactor in the vicinity of the plasma arc zone by use of a nozzle which aligns the hydrocarbon spray in the axial direction of the reactor, and is designed in such a way that coarse drops are formed.
• a delay in the hydrocarbon evaporation enhances formation of particles.
• the process yields open carbon micro-cones with total disclination degrees 60 and/or 1200, corresponding to cone angles of respectively 112.9 and/or 83.6.
• the cones are closed in the apex.
• the conical domains represent at least 10% of the material.
• disc- or ring-shaped particles are formed.
• Athermanous additives primarily consisting of such particles.
• carbon particles having the shape of cones and discs form at least 10 %, in particular at least 50 %, preferably at least 75 %, advantageously at least 90 %, suitably 100 %, of the total weight of athermanous particles present in the polymerization suspension.
• the athermanous material used in the present expandable beads comprises carbon particles with a conical shape, the content of which is at least 1 %, suitably at least 10 %, for example at least 25 %, by weight of the total weight of carbon particles having overlapping carbon layers.
• Disc-shaped particles are present to an extent of up to 99 %, for example 25 to 90 % by the weight of the total weight of carbon particles having overlapping carbon layers.
• the carbon particles have a narrow particle size distribution.
• the particles exhibit a greatest dimension in the range of 0.5 to 2.0 micrometers, in particular 0.7 to 1.0 micrometers.
• a narrow distribution will enhance distribution of the particles within the polystyrene bead and assist in obtaining uniform properties. It would appear that absorption of incoming photons will be enhanced when the particles have a narrow particles size in the above indicated range of 0.5 to 2.0 micrometers, in particular 0.7 to 1.0 micrometers.
• the polymerisation is typically carried out in the presence of a radical initiator or initiators, typically 1 to 4 initiators being used.
• the athermanous particles are incorporated into the polystyrene beads during the polymerization of monomers optionally together with comonomers.
• comonomers include acrylonitrile and polybutadiene and potentially other vinyl- comonomers.
• the addition of the athermanous particles to the polymerisation mixture results in the production of a grey material (in the following also called expandable polystyrene, EPS).
• EPS expandable polystyrene
• the grey EPS has a considerably lower conductivity than the corresponding white EPS.
• Polystyrene beads containing athermanous particles can be produced, for example, by bulk or suspension polymerization.
• polymerisation is carried out in a static mixer.
• the polymerisation is carried out in a liquid phase into which the styrene monomers are suspended.
• the liquid phase is an aqueous phase.
• the athermanous particles can be introduced in one or several dosages.
• polymerised is subjected to polymerisation in the presence of a polymerisation initiator.
• the athermanous particles are then introduced into the polymerization mixture by means of a premix which contains a second portion of the monomers which are to be polymerised and the athermanous particles and any further additives.
• the remaining portion of the monomers to be polymerised is suspended in a liquid phase to form a suspension and is subjected to a polymerisation reaction in the presence of a polymerisation initiator to produce expandable polystyrene beads.
• the premix is added when the polymerisation reaction has reached a preselected conversion rate and the polymerisation is continued in order to produce EPS beads.
• the athermanous particles for example in the form of a premix are added at a conversion rate of 0.1 to 70.0 %, in particular about 1 to 50.0 %, especially about 10.0 to 30.0 %, calculated from the total mass of the styrene monomer.
• the athermanous particles for example in the form of a premix are added over a time period smaller than that needed for increasing the conversion rate of the polymerisation by at least 10 % units, preferably over a time period corresponding to the time needed for increasing the conversion rate by 10 to 30 % units.
• the content of athermanous particles in the expandable polystyrene beads is typically 0.1 to 15 parts by weight, for example 1 to 10, or 2 to 5, parts by weight, based on 100 parts by weight of styrene.
• the polymerization mixture can be supplemented with other additives or auxiliary agents, such as a (polymeric) fire-retarding agent.
• the flame retarding agent is selected from the group of organo- chlorines, organobromines, and brominated polymeric compounds.
• auxiliary agents are added in an amount of 0.01 to 5.0 %, in particular 0.05 to 4.0 %, preferably about 0.1 to 3.0 %, advantageously 0.2 to 2.0 % by total mass, of the styrene monomer.
• a method for producing expandable polystyrene beads in which styrene monomers are polymerised in a suspension at a first temperature in the range of about 75 to 110 °C until a preselected degree of conversion has been reached.
• a premix of monomer and athermanous particles is added to the suspension.
• the suspension is heated to a second, higher temperature during the addition of the blowing agent.
• the temperature of the suspension is then optionally raised to a third temperature higher than the second temperature. Polymerisation is continued until a preselected final conversion degree has been reached.
• the polymerisation is continued to a conversion rate of at least 95 %, calculated from the styrene monomer and in a preferred embodiment the EPS beads are recovered from the liquid phase.
• a blowing agents is added during the implementation of the process or afterwards.
• the blowing agent typically comprises a hydrocarbon, such as an aliphatic hydrocarbon having 3 to 10 carbon atoms. Typical examples of such hydrocarbons comprise C 3 to C 6 aliphatics and isomers thereof. Specific examples are propane, butane, pentane and hexane and isomers thereof, such as isobutane, isopentane and isohexane.
• the blowing agent is added in amounts of about 0.1 to about 15 parts by weight, typically 1 to 10 parts by weight, per 100 parts by weight of styrene.
• Polymerisation can be carried out also in the presence of additives selected from the group of emulsifiers, preferably stabilizers, more preferably fillers e.g. talc, as well as combinations thereof, each additive providing its own additional property to the produced EPS beads e.g. making the beads more stable.
• additives selected from the group of emulsifiers, preferably stabilizers, more preferably fillers e.g. talc, as well as combinations thereof, each additive providing its own additional property to the produced EPS beads e.g. making the beads more stable.
• co monomers varies depending on the quality of the resultant polystyrene beads.
• polymerization can be carried out in the presence of up to 40 % by weight of ethylenically unsaturated monomer.
• Athermanous particles In addition to the present athermanous particles other athermanous particles can also be added. Such particles are typically selected from the group of carbon black particles, graphite, graphene and other carbon-based materials.
• the concentration of the athermanous particles in the beads is typically 0.01 to 20 %, in particular 0.1 to 15 %, preferably about 1 to 7.5 %, advantageously 3 to 5 %, by weight of the polystyrene polymer.
• Foamed polystyrene articles can be made from the beads.
• the foamed articles exhibit excellent thermal insulation properties.
• the foamed articles comprise insulating boards and panels composed of expanded polystyrene beads. The production of expanded product from polystyrene beads is well-known in the art.
• the exapandable beads are heated, for example by using a heat transfer medium such as steam, to a temperature high enough to soften the beads, preferably to a temperature above the glass transition point of polystyrene.
• a heat transfer medium such as steam
• the temperature is in excess of 95 °C, in particular 100 °C or higher.
• the heating will cause the blowing agent to boil and while the blowing agent is evaporated off the beads, swelling of the beads is achieved and porous particles created, which can molded together to form articles, such as panels, sheets and boards, by using traditional shape or block mo lding methods .
• the concentration of the athermanous particles is 0.01 to 20 % calculated from the total mass of the polymerized styrene.
• the insulating board composed of expanded polystyrene beads comprises athermanous particles in a concentration of 0.1 to 15.0 %, preferably 1.0 to 10.0 %, advantageously 3.0 to 6.0 % by total mass of the polymerized styrene.
• the board comprises 0.01 to 5.0 %, preferably 0.05 to 4.0 % more preferably 0.1 to 3.0 %, advantageously 0.2 to 2.0 %, calculated from the total mass of the styrene, other auxiliary components, such as emulsifiers, stabilizers, fillers, such as talc, carbon black, graphite particles, fire retardants, for example hexabromocyclododecane or brominated polymeric fire retardants, as well as combinations thereof.
• the thermal conductivity of an insulating board according to the present invention, composed of expanded polystyrene beads is, measured at a density of about 15 kg/m 3 , i.e. roughly 15 ⁇ 2 kg/m 3 , 0.027 to 0.035 W/(m K).
• the expression "about 15 kg/m 3 is used include a 10 to 20 % variation of the exact value, thus about 15 kg/m 3 can be interpreted as being typically 15 ⁇ 2 kg/m 3 .
• the present expanded styrene polymers typically have a thermal conductivity which is 0.031 W/(m K) or lower.
• the following non-limiting examples illustrate the invention Example 1
• the mixture was kept for 315 min at 90°C and then 2.85 g of pig skin gelatine was added. Altogether the mixture was kept at 90°C for 320 min whereafter it was heated to 120°C within 2h. While heating to 120°C 152 g of pentane was added. The mixture was kept at 120°C for 2h where after it was cooled down to 37°C within 90 min.
• the reaction mixture was removed from the autoclave and the polystyrene beads were washed thoroughly with water.
• the beads were sieved and the sizes from 0.8 mm to 1.4 mm were pre-expanded to 15 kg/m 3 from which 50 mm thick sample plate was moulded. The thermal conductivity was determined from this sample plate.
• Example 1 As Example 1 but the used athermanous material was Graphite, SFG6 from TimCal.
• Example 1 As Example 1 but 95 g of XPB-550 was used. In addition, the sample plate was molded using beads that were pre-expanded to 19 kg/m3.

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• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)

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• 2013
  • 2013-10-04 WO PCT/FI2013/050965 patent/WO2015049413A1/en active Application Filing
  • 2013-10-04 EP EP13785894.0A patent/EP3052557A1/de not_active Withdrawn

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