WORLD INTELLECTUAL PROPERTY ORGANIZATION
`Intematlonal Bureau
`
`INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(51) International Patent Classification 7 3
`
`(11) International Publication Number:
`
`WO 00/02800
`
`B65D 90/06, F16L 59/02, F17C 3/04
`
`_
`,
`_
`(43) International Publication Date:
`
`20 January 2000 (20.01.00)
`
`(21) International Application Number:
`
`PCT/US99/15186
`
`(22) International Filing Date:
`
`6 July 1999 (06.07.99)
`
`(30) Priority Data:
`98112975.2
`
`13 July 1998 (13.o7.98)
`
`EP
`
`(71) Applicant (for all designated States except US): THE DOW
`CHEMICAL COMPANY [US/US]; 2030 Dow Center, Mid-
`land, MI 48674 (US).
`
`(81) Designated States: AE, AL, AM, AT, AU, AZ, BA, BB, BG,
`BR, BY, CA, CH, CN, CZ, DE, DK, EE, ES, FI, GB, GD,
`GE’ GH’ GM’ HR’ HU, ID, IL, IN, IS, JP, KE, KG, KR,
`KZ, LC, LK, LR, Ls, LT, LU, LV, MD, MG, MK, MN,
`MW, MX, NO, NZ, PL, PT, Ro, RU, SD, SE, SG, SI, SK,
`SL, TJ, TM, TR, TT, UA, UG, US, UZ, YU, ZA, zw,
`ARIPO patent (GH, GM, KE, Ls, MW, SD, sL, sz, UG,
`ZW), Eurasian patent (AM, AZ, BY, KG, KZ, MD, RU, TJ,
`TM), European patent (AT, BE, CH, CY, DE, DK, ES, Fl,
`FR, GB, GR, IE, IT, LU» Mcv NI“, PT» SE), OAPI patent
`(BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE,
`SN, TD. TG).
`
`(72) Inventors; and
`(75) Inventors/Applicants (for US only): BARRY, Russell, P. Published
`[GB/GB];
`Im Kleinfeld 38, D-77855 Gamshurst
`(DE).
`With international search report.
`WEIR, Kevin, W. [GB/GB];
`Im Unterfeld 13, D-77836
`Before the expiration of the time limit for amending the
`Greffern (DE).
`claims and to be republished in the event of the receipt of
`amendments.
`
`(74) Agent: HOWARD, Dan, R.; The Dow Chemical Company,
`Patent Dept., P.O. Box 1967, Midland, MI 48641-1967
`(US).
`
`(54) Title: PROPYLENE POLYMER FOAM FOR THERMAL INSULATION OF CONTAINERS
`
`3
`
`at
`
`(57) Abstract
`
`The invention relates to the use of a flexible polypropylene foam, comprising greater than 50 percent by weight of propylene
`monomeric units, for themlally insulating containers, especially temperature—controlled bulk tank transportation containers like for example
`IMO containers. Preferably the propylene polymer foam is a strand foam made of a resin comprising at least 20 percent of a high melt
`strength polypropylene and up to 20 percent of a homopolymer or copolymer of ethylene, each based on the total weight of the resin.
`
`Page 1 of 23
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`BOREALIS EXHIBIT 1049
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`Page 1 of 23
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`BOREALIS EXHIBIT 1049
`
`

`
`FOR THE PURPOSES OF INFORMATION ONLY
`
`Codes used to identify States party to the PCT on the front pages of pamphlets publishing international applications under the PCT.
`
`Albania
`Armenia
`Austria
`Australia
`Azerbaijan
`Bosnia and Herzegovina
`Barbados
`Belgium
`Burkina Faso
`Bulgaria
`Benin
`Brazil
`Belarus
`Canada
`Central African Republic
`Congo
`Switzerland
`Cote d’Ivoire
`Cameroon
`China
`Cuba
`Czech Republic
`Germany
`Denmark
`Estonia
`
`ES
`FI
`FR
`GA
`GB
`GE
`GH
`GN
`GR
`HU
`IE
`IL
`IS
`IT
`JP
`KE
`KG
`KP
`
`KR
`KZ
`LC
`LI
`LK
`LR
`
`Spain
`Finland
`France
`Gabon
`United Kingdom
`Georgia
`Ghana
`Guinea
`Greece
`Hungary
`Ireland
`Israel
`Iceland
`Italy
`Japan
`Kenya
`Kyrgyzstan
`Democratic People's
`Republic of Korea
`Republic of Korea
`Kazakstan
`Saint Lucia
`Liechtenstein
`Sri Lanka
`Liberia
`
`LS
`LT
`LU
`LV
`MC
`MD
`MG
`MK
`
`ML
`MN
`MR
`MW
`MX
`NE
`NL
`N0
`NZ
`PL
`PT
`R0
`RU
`SD
`SE
`SG
`
`Lesotho
`Lithuania
`Luxembourg
`Latvia
`Monaco
`Republic of Moldova
`Madagascar
`The former Yugoslav
`Republic of Macedonia
`Mali
`Mongolia
`Mauritania
`Malawi
`Mexico
`Niger
`Netherlands
`Norway
`New Zealand
`Poland
`Portugal
`Romania
`Russian Federation
`Sudan
`Sweden
`Singapore
`
`SI
`SK
`SN
`SZ
`TD
`'I‘G
`TJ
`TM
`TR
`TT
`UA
`UG
`US
`UZ
`VN
`YU
`ZW
`
`Slovenia
`Slovakia
`Senegal
`Swaziland
`Chad
`Togo
`Tajikistan
`Turkmenistan
`Turkey
`Trinidad and Tobago
`Ukraine
`Uganda
`United States of America
`Uzbekistan
`Viet Nam
`Yugoslavia
`Zimbabwe
`
`Page 2 of 23
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`

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`WO 00/02800
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`PCT/US99/15186
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`PROPYLENE POLYMER FOAM FOR THERMAL
`
`INSULATION OF CONTAINERS
`
`The present invention relates to the use of propylene polymer foam for
`
`thermal insulation of containers, especially bulk tank transportation containers. Bulk tank
`
`transportation containers are large vessels and usually classified as tank containers, swap
`
`tanks, road tanks, trailer tanks, and rail tank cars.
`
`Safe and efficient transportation of bulk liquids over long distances is a main
`
`concern of any kind of industry. Traditionally, bulk liquids are transported in drums holding
`
`several hundred liters. However, for movements crossing seas, large marine tank
`
`containers often with capacities of up to 26,000 liters or more have become an attractive
`
`alternative to the traditional transportation in drums. These tank containers are designed to
`
`prevent accidental damage and tampering compared to other methods of carrying bulk
`
`liquids, such as drums. As a result the risk of cargo loss or contamination is significantly
`
`reduced. Moreover, tank containers deliver time and labor savings. Since they are handled
`
`by using standard equipment, transfer at ports and terminals is simple and switching
`
`between road, rail and sea straightforward. The use of tank containers offers a safe and
`
`cost-effective method of moving bulk liquids, while using a recyclable resource. Tank
`
`containers carry a far greater payload for the equivalent space and shipping cost compared
`
`with a rectangular standard box container filled with palletized drums. Swap tanks, road
`
`tanks, tank trailers and rail tank cars have similar benefits for land movements across and
`
`between countries, offering more cost effective and safe movements.
`
`A tank container is basically a pressure vessel mounted in a frame. The
`
`pressure vessel has a cylindrical shape with its ends rounded.
`
`Its shell, generally denoted
`
`as "tank shell", is usually made of stainless steel. The function of the frame is to support and
`
`protect the tank as well as to facilitate the stowage, securement and handling by standard
`
`ISO (international Standards Organization) container equipment. The overall dimensions
`
`and corner castings conform to ISO container recommendations. When properly handled
`
`the frame is designed to cope with the stresses of a fully loaded tank.
`
`Other types of bulk tank transportation containers also comprise a mainly
`
`cylindrical vessel, optionally surrounded by an outer cladding.
`
`Tank containers, as well as other bulk tank transportation containers, conform
`
`to the advisory and mandatory requirements of internationally recognized codes; in
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`-1-
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`particular, tank containers must adhere to the codes of the International Maritime
`Organization (IMO). For that reason, the above-described tank containers are generally
`
`denoted as "IMO tanks" or "lMO tank containers".
`
`In order to protect the carried liquids from undesirable fluctuations in
`
`temperature most bulk tank transportation containers are insulated. As some of the
`transported products must be heated during loading, unloading and during transportation (for
`example, molten chocolate) bulk tank transportation containers also comprise a heating
`system such as electrical or steam heating. From an economical standpoint it is reasonable
`to design many bulk tank transportation containers with a heating system. This gives the
`tank the flexibility to carry both cargoes that require heating during loading, discharge and/or
`
`transportation, and cargoes which do not require heat input. The more costly alternative
`would be to own or lease both treatable and nonheatable bulk tank transportation containers.
`
`This alternative would also reduce the vessel utilization rate. For IMO tank containers, the
`
`most efficient and widespread heating system is steam heating usually consisting of a series
`
`of steam channels on the outside of the lower half of the tank.
`
`In case of IMO tank containers the insulation is arranged around the pressure
`
`vessel and covered by an outer cladding usually made of glass-reinforced plastic resin or
`
`marine grade aluminum. The insulation of steam heatable IMO tank containers must, as a
`
`matter of fact, at least withstand the operating temperatures of the pressurized steam.
`
`It is pointed to the fact that
`Generally, temperature resistance of up to 130°C is required.
`even for the insulation of non-heated tanks, for example, tanks carrying refrigerated liquids,
`
`a temperature resistant insulation material is desirable as steam cleaning might then be
`
`Insulation materials fulfilling the temperature resistance
`employed with these tanks.
`requirement and which are used in the art include expanded polyurethane, expanded
`polyisocyanurate, mineral wool and glass wool, as well as combinations of said expanded
`polymers with mineral wool and/or glass wool. For other types of bulk tank transportation
`containers, expanded polystyrene is also used as insulation material, but should be used
`
`only for moderately heated (up to 70°C) tanks due to the lower temperature resistance of
`
`EPS foam.
`
`Expanded polyurethane and expanded polyisocyanurate are both rigid foams
`
`which cannot be bent around the cylindrical shell of the pressure vessel.
`
`in order to be
`
`adapted to the cylindrical share, these rigid foams must be cut in single blocks which are
`then arranged on the shell of the pressure vessel and held in place by for example,
`-2-
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`tightening straps or adhesive. Alternatively, rigid foams are fabricated to enable the fitting to
`
`the curved surfaces.
`
`In many cases this involves fabricating a curved section from a larger
`
`block, which is highly wasteful and expensive. These curved segments are fragile leading to
`
`an additional waste and cost. Another technique it to cut grooves into flat rigid foam boards
`
`to bend the boards. Again this is costly, the boards are fragile and breakage occurs leading
`
`to further wastage. Furthermore, the fabrication of the rigid foams and later handling and
`
`installation generates significant levels of irritant dust.
`
`Injected polyurethane technology
`
`used to insulate tanks has other problems. The foam sticks to the inner tank and outer
`
`cladding, making maintenance of the tank more difficult. Problems can arise too due to the
`
`differential expansion of the tank shell and outside cladding, particularly when the tank is
`
`being heated and/or cleaned.
`
`Polyurethane foam does not have sufficient heat resistance alone and hence,
`
`a costly double layer comprising a heat resistant lagging of mineral wool or glass wool and a
`
`second lagging of high compressive strength polyurethane foam blocks is often used.
`
`In
`
`case the insulation material is expanded polyisocyanurate it is often used as 1-piece being
`
`grooved or it is fabricated into curved segments fitting the cylindrical shell of the pressure
`
`vessel exactly. Both rigid foam alternatives are very expensive implying the afore-mentioned
`
`drawbacks. Moreover, the friable nature of the expanded foams can lead to extensive wear
`
`from vibrations caused during transportation.
`
`Compression resistance of the insulation material is another important feature
`
`in order to avoid damage of the outer cladding when for instance personnel walk thereon
`
`during maintenance. An insulation made solely of mineral wool or glass wool is
`
`disadvantageous since mineral wool and glass wool both lack the required compression
`
`resistance and impact resistance and do not maintain the outer circular shape of the
`
`container in the course of time.
`
`in view of the insufficient compression resistance of mineral
`
`wool or glass wool, it is necessary to employ strips of high compression strength foam
`
`plastic material to support the cladding.
`
`Although the expected lifetime of bulk tank transportation containers is about
`
`20 years they are re-clad after about 10 years including removal and renewal of the
`
`insulation. The replacement of the insulation material is necessary since all types of
`
`insulation materials currently used in bulk tank transportation containers can absorb
`
`significant amounts of water resulting in a undesirable increase in weight and reduction of
`
`thermal insulation properties. The entry of water and other liquids into the insulation will
`
`-3-
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`always occur even if the outer cladding is undamaged, for example, from water vapor
`
`transmission and rain or sea water, or from cargo spills around the inlets, outlets, and man
`
`hole covers, which can all pass between the cladding joints. Water will also get in via
`
`corroded steam lines and from condensation on the inner tank shell. Hence, a fully
`
`waterproof seal of the insulation from the environment by the cladding is not practicable.
`
`Removing the used water-saturated insulation material(s) is an unpleasant and difficult job
`
`since the material(s) can deteriorate and become very brittle over the years and partly
`
`adhere to the shell of bulk tank transportation containers. The insulation material(s) must be
`
`disposed of, as recycling of thermosetting polymers and inorganic material is difficult.
`
`Additional to low water absorbency it would also be desirable to have an insulation material
`
`which would allow drainage of any water away from the vessel surface.
`
`It is thus the object of the present invention to provide a single layer of
`
`recyclable material for thermal insulation of containers, especially bulk tank transportation
`
`containers, that is easy to apply and remove avoiding the generation of dust and that is heat
`
`resistant up to 130°C.
`
`The object is met by the use of a flexible propylene polymer foam, comprising
`
`greater than 50 percent by weight of propylene monomeric units, for thermally insulating
`
`containers.
`
`The invention also relates to a propylene polymer foam preferably used which
`
`is a propylene polymer strand foam made of a resin comprising at least 20 percent of a high-
`
`melt strength polypropylene and up to 20 percent of a homopolymer or copolymer of
`
`ethylene, each based on the total weight of the resin.
`
`The flexible propylene polymer foam preferably has the shape of a plank that
`
`can be readily wrapped around round transportation containers. Within the meaning of the
`
`present invention the term "plank" refers to foam planks having a thickness of at least 10
`
`mm. Preferably the thickness ranges from 10 to 200 mm, more preferably from 20 to 100
`
`mm. For the insulation of IMO tanks the propylene polymer foam plank preferably has a
`
`thickness of about 50 mm. The desired thickness may also be reached by molding together
`
`several thinner foam sheets.
`
`If used for IMO tank containers the propylene polymer foam plank preferably
`
`has a width of about 550 mm, said width fitting between the strengthening rings of a
`
`standard pressure vessel of an IMO tank container. The length of the sheet depends on the
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`number of single sheets that are wrapped around the cylindrical pressure vessel and
`
`arranged side-by-side to cover the whole circumference. Three sheets have proved to be
`
`advantageous resulting in a length of each sheet of about 2750 mm. Longer and shorter
`
`sheets are, of course, also possible but are more difficult to handle.
`
`The propylene polymer foam of the present invention can withstand
`
`temperatures of up to 130°C; in preferred embodiments heat resistance of up to 150°C can
`
`be reached depending on the composition of the resin from which the propylene polymer
`
`foam is made. The heat resistance properties make the propylene polymer foam especially
`
`suitable for the insulation of most temperature-controlled bulk tank transportation
`
`containers. Nevertheless, the propylene polymer foam is also useful for insulation of
`
`non—temperature-controlled containers.
`
`Flexibility is another important property of the present propylene polymer
`
`foam. The propylene polymer foam is flexible enough so that a sheet with a thickness of 50
`
`mm can be bent to fit the curvature of a standard IMO tank pressure vessel having a
`
`diameter of about 2.4 m.
`
`The propylene polymer foam according to the present invention is
`
`thermoplastic resulting in at least two advantageous properties. Firstly, the foam is heat or
`
`hot-air weldable which means that single planks of propylene polymer foam may be welded
`
`together to enhance the overall insulation performance (thermal bridges are avoided) and to
`
`avert the entry of water or spilled cargo onto the steel tank shell. Secondly, used propylene
`
`polymer foam, for example, from scrap containers, way easily be recycled reducing the
`
`amount of waste material.
`
`Besides recycling the propylene polymer foam, it is sometimes possible to
`
`reuse the complete foam planks from bulk tank transportation containers which have been
`
`removed for maintenance of the pressure vessel.
`
`The propylene polymer foam according to the present invention has a low
`
`friability and can be handled and worked without the generation of irritating dust.
`
`The propylene polymer foam has the compression resistance required for the
`
`insulation of ‘bulk tank transportation containers which means that personnel can walk on top
`
`of the outer cladding arranged around the insulation.
`
`It provides form and impact resistance
`
`and, as the propylene polymer foam has a temperature resistance exceeding 130°C it can
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`be used as the single insulation material in one lagging process. Thus, the need for high
`
`compression strength material strips to support the cladding is eliminated.
`
`Propylene polymers have a very low chloride ion content, preferably not more
`
`than 25 ppm. More preferably, chloride ion contents of less than 10 ppm should be used
`
`when the insulation is in contact with stainless steel tank shells. Stainless steel is
`
`susceptible to corrosion and stress cracking caused by chloride ions. As propylene
`
`polymers have a lower chloride content than polyurethane, polyisocyanurate, mineral wool,
`
`and glass wool typically used as insulation, the working life of the pressure vessel of a bulk
`
`tank transportation container can be extended by using propylene polymer foam for
`
`insulation.
`
`The propylene polymer foam may be prepared according to any known
`
`process for the production of expanded or extruded polyolefin polymers. Typically extrusion
`
`processes are generally characterized by feeding, into an extruder, a propylene polymer
`
`resin optionally adding a nucleating agent, melting and plasticizing the propylene polymer
`
`resin thereafter feeding a volatile foaming agent, uniformly mixing the materials, and then
`
`extruding the mixture to a low pressure zone while cooling it and forming a propylene
`
`polymer foam product. Corresponding processes are described in U.S. Patent 5,527,573,
`
`U.S. Patent 5,567,744, and U.S. Patent 5,348,795.
`
`Preferably, the propylene polymer foam is prepared by the strand foam
`
`process (also denoted as "coalesced foam process" or "coalesced strand foam process")
`
`which is disclosed in U.S. Patent 4,824,720, as well as in the above-cited patents. Said
`
`method provides a foam structure comprising a plurality of coalesced extruded strands or
`
`profiles by extrusion foaming of a molten thermoplastic composition utilizing a die containing
`
`a multiplicity of orifices. The orifices are arranged such that the contact between adjacent
`
`streams of the molten extrudate occurs during the foaming process and the contacting
`
`surfaces adhere to one another with sufficient adhesion to result in a unitary structure. The
`
`individual strands of coalesced propylene polymer foam should remain adhered into a
`
`unitary structure to prevent strand delamination under stress encountered in preparing,
`
`shaping, and using the foam.
`
`Another suitable process for making a foam of the present invention is an
`
`accumulating process as described in U.S. Patent 4,323,528.
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`Although the extrusion process, especially the strand foam process is
`
`preferred other methods of preparing the propylene polymer foam may be employed,
`
`including the bead foam process comprising impregnating propylene polymer resin beads
`
`with a blowing agent, preblowing said beads and finally molding them into the desired shape
`
`for example, a sheet or plank (for example described in WO 96/10600), and a lamination
`
`process comprising gluing sheets into a sandwich structure as, for example, described in DE
`
`44 21 016 A1.
`
`The term "propylene polymer" within the meaning of the present invention
`
`includes propylene homopolymers (polypropylene) and copolymers of propylene and
`
`copolymerizable ethylenically unsaturated comonomers. The propylene polymer material
`
`may further include non-propylenic polymers. The propylene polymer material may be
`
`comprised solely of one or more propylene homopolymers, one or more propylene
`
`copolymers, a blend of one or more of each of propylene homopolymers and copolymers, or
`
`blends of any of the foregoing with a non-propylenic polymer. Regardless of composition,
`
`the propylene polymer material comprises at least greater than 50 and preferably at least 80
`
`weight percent of propylene monomeric units.
`
`Suitable monoethylenically unsaturated comonomers include olefins.
`
`vinylacetate, methylacrylate, ethylacrylate, methyl methacrylate, acrylic acid, itaconic acid,
`
`maleic acid, and maleic anhydride. The propylene copolymer preferably comprises about 20
`
`percent or less by weight of the ethylenically unsaturated comonomer.
`
`Suitable non-propylenic polymers incorporatable in the propylene polymer
`
`material include high, medium, low, and linear density polyethylenes, polybutene-1,
`
`ethylene-acrylic acid polymer, ethylene-vinyl acetate copolymer, ethylene-propylene rubbery
`
`styrene-butadiene, rubbery ethylene-ethyl acrylate copolymer, and ionomer, as well as other
`
`copolymers comprising ethylene.
`
`Particularly useful propylene copolymers are those copolymers of propylene
`
`and one or more non-propylenic olefins. Propylene copolymers include random and block
`
`copolymers of propylene and an olefin selected from ethylene, C,-C101-olefins, and C,-Cw
`
`dienes. Propylene copolymers also include random terpolymers of propylene and 1-olefins
`
`selected from ethylene and C,-C8 1-olefins.
`
`ln terpolymers having both ethylene and C,-C8
`
`1-olefins, the ethylene content is preferably 20 percent or less by weight. The C,-Cm
`
`1-olefins include the linear and branched C,-Cw 1-olefins such as‘, for example,
`
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`1~butene, isobutylene, 1—pentene, 3-methyl-1-butene, 1-hexane, 3,4-eimethyl-1-butene,
`
`1-heptene, 3-methyl-1-hexane. Examples of C,-Cw dienes include 1,3-butadiene,
`
`1,4-pentadiene, isoprene, 1,5-hexadiene, 2,3-dimethyl-1,3-hexadiene.
`
`Also, as used herein, the propylene polymer material preferably has a melt
`
`flow rate of between 0.05 and 50 and more preferably between 0.1 and 10 according to
`
`ASTM D1238 Condition L.
`
`The preferred propylene polymer resins for the present invention are those
`
`polypropylene resins which are branched or lightly cross-linked polymer materials.
`
`Branching (or light cross-linking) may be obtained by those methods generally known in the
`
`art, such as chemical or irradiation branching/light cross-linking. One such resin which is
`
`prepared as a branched/lightly cross-linked polypropylene resin prior to using the
`
`polypropylene resin to prepare a finished polypropylene resin product and the method of
`
`preparing such a polypropylene resin is described in U.S. Patent 4,916,198. Another
`
`method to prepare branched/lightly cross-linked polypropylene resin is to introduce chemical
`
`compounds into the extruder, along with a polypropylene resin and allow the
`
`branching/lightly cross-linking reaction to take place in the extruder. U.S. Patent 4,714,716
`
`illustrates this method.
`
`Suitable branching/cross-linking agents for use in extrusion reactions have
`
`been found to include azido and vinyl functional silanes, organic peroxides and
`
`multifunctional vinyl monomers.
`
`When the propylene polymer foam is prepared by the strand foam process it
`
`is preferred to use at least 20 weight percent of a high-melt strength (HMS) polypropylene
`
`which is a branched polypropylene and up to 20 weight percent of a homopolymer or
`
`copolymer of ethylene. The following blend of three different polymers is especially
`
`preferred: a high viscous polypropylene homopolymer used for blow-molding, preferably
`
`having a melt flow index of from 0.2 to 0.3, an HMS polypropylene, and a homopolymer or
`
`copolymer of ethylene (for example, ethylene-octane copolymer or ethylene-propylene
`
`copolymer) to enhance adhesion between the extruded strands. The blendpreferably
`
`comprises 40 to 60 weight percent of the high viscous polypropylene, 20 to 50 weight
`
`percent of the HMS polypropylene, and 1 to 20 weight percent of the homopolymer or
`
`copolymer of ethylene.
`
`it is also possible to add various additives such as inorganic fillers,
`
`pigments, antioxidants, acid scavengers, ultraviolet absorbers, flame retardants, processing
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`aids, and extrusion aids.
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`in a preferred embodiment one or more antioxidants are used in an
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`amount of from 0.1 to 3 parts by weight per hundred parts by weight of the polymer resin.
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`0.1 to 1 parts by weight are even more preferred and about 0.6 parts by weight are most
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`preferred. The use of antioxidants is desirable to avoid embrittlement of the propylene
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`polymer at higher temperatures over a period of time. The preferred antioxidants are
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`phenol-type or phosphite-type antioxidants or a combination of both.
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`In addition, a nucleating agent may be added in order to control the size of
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`foam cells. Preferred nucleating agents include inorganic substances such as calcium
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`carbonate, talc, clay, titanium oxide, silica, barium sulfate, diatomaceous earth, mixtures of
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`citric acid and sodium bicarbonate, talc being most preferred. The amount of nucleating
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`agent employed may range from 0.01 to 5 parts by weight per hundred parts by weight of the
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`polymer resin. The preferred range is from 0.1 to 3 parts by weight.
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`Suitable blowing agents useful in making the foams of the present invention
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`include volatile organic blowing agents, inorganic blowing agents, and chemical blowing
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`agents. Organic blowing agents include aliphatic hydrocarbons having 1 to 9 carbon atoms
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`and halogenated aliphatic hydrocarbons, having 1 to 4 carbon atoms. Aliphatic
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`hydrocarbons include methane, ethane, propane, e-butane, isobutane, n-pentane,
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`isopentane, and neopentane. Among halogenated hydrocarbons, fluorinated hydrocarbons
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`are preferred. Examples of fluorinated hydrocarbon include methyl fluoride,
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`perfluoromethane, ethyl fluoride, 1,1-difluoroethane, 1,1,1-trifluoroethane (HFC-143a),
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`1,1,1,2-tetrafluoroethane (HFC-134a), pentafluoroethane, perfluoroethane,
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`2,2-difluoropropane, 1,1,1trifluoropropane, perfluoropropane, perfluorobutane,and
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`perfluorocyclobutane. Partially halogenated chlorocarbons and chlorofluorocarbons for use
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`in this invention include methyl chloride, methylene chloride, ethyl chloride,
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`1,1,1-trichloroethane, 1 ,1-dichloro—1—fluoroethane (HCFC-141 b), 1-chloro-1,1-difluoroethane
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`(HCFC-142b), 1,1-dichloro—2,2,2-trifluoroethane (HCFC-123) and 1-chloro-1,2,2,2-
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`tetrafluoroethane (HCFC-124). Inorganic blowing agents include carbon dioxide, nitrogen,
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`argon, water, air, nitrogen, and helium. Chemical blowing agents include azodicarbonamide,
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`azodiisobutyronitrile, benzene-sulfonhydrazide, 4,4-oxybenzene sulfonyl-semicarbazide, p--
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`toluene sulfonyl semicarbazide, barium azodicarboxylate, N,N'-dimethyl-
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`N,N‘-dinitrosoterephthalamide, and trihydrazino triazine. For the strand foam process
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`isobutane, carbon dioxide or water or combinations thereof are the preferred blowing agents.
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`The amount of blowing agent incorporated into the polymer melt to make a
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`foam-forming polymer gel is from 0.2 to 5.0 preferably from 0.5 to 3.0, and most preferably
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`from 1.0 to 2.50 moles per kg polymer.
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`The present foam may be closed-cell or open-cell. Preferably, the present
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`foam is from 10 to 80 and most preferably from 10 to 60 percent open-cell according to
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`ASTM D2856-A. Some open-cell content is preferred in the present foam because an open-
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`cell foam is more dimensionally stable than a corresponding closed-cell foam. The open-cell
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`content also increases flexibility and reduces cure time.
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`The present foam has preferably the density of from 9 to 65 kg/ma, more
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`preferably from 9 to 48 kg/m‘‘, especially preferably from 9 to 32 kg/m3 and most preferably
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`from 9 to 24 kg/m°. The lighter propylene polymer foams are especially useful for the
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`insulation of transportation containers like IMO tanks as light insulation material can save a
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`significant amount on the tare weight of the container. The low weight of the most preferred
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`propylene polymer foam is a major advantage over currently used insulation materials for
`IMO tanks such as mineral wool (density of 35 to 80 kg/m”) and
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`polyurethane/polyisocyanurate (density of 35 to 45 kg/ma).
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`The propylene polymer foam preferably has an average cell size of from 0.05
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`to 3.0 mm, more preferably from 0.1 to 1.5 mm and most preferably from 0.2 to 0.8 mm
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`according to ASTM D3576. Small cells are preferred since they increase the insulation
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`performance of the foam and decrease the water absorption of the foam. The low water
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`absorption properties are a further significant advantage over currently used insulation
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`materials for bulk tank transportation containers such as mineral wool, glass wool,
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`polyurethane, and polyisocyanurate which all absorb undesirable levels of water. Low water
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`absorption means that the foam will maintain its weight and insulation performance through
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`the vessels useful life. The replacement of the foam after a certain period of time will thus
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`become unnecessary.
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`The water absorption of the propylene polymer foam is preferably not more
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`than 1.5 percent by volume.
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`The thermal conductivity (X) of the propylene polymer foam is preferably not
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`greater than 0.040 W/mK and more preferably not greater than 0.037 W/mK when measured
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`at a mean temperature of 10°C.
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`Propylene polymer foam planks prepared according to the strand foam
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`process consist of individual coalesced strands, each strand being surrounded by a skin.
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`This skin confers low water absorbency to the propylene polymer foam irrespective of its
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`open-cell content and cell size. The strands further result in elongated grooves arranged
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`parallel on the surface of the plank in direction of the strands.
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`if the propylene polymer foam
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`plank is bent along the direction of the strands and wrapped around the cylindrical shell of a
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`pressure vessel of a bulk tank transportation container, the grooves will serve to drain any
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`water from the vessel (for example, water resulting from condensation on the vessel of
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`refrigerated tank containers). Propylene polymer strand foam planks bent perpendicular to
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`the strand direction and used lengthwise will not have said draining effect.
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`Although the propylene polymer foam of the present invention is well adapted
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`to insulate IMO tanks it can be used for thermal insulation of any container, preferably
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`temperature-controlled container due to the heat resistance of the propylene polymer foam
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`or any transportation container due to the low weight of the propylene polymer foam, and
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`more preferably any temperature-controlled bulk tank transportation containers for road, rail
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`and ship, for example, swap tanks (tank containers similar to IMO tank containers but with a
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`larger pressure vessel protruding beyond the ISO frame), road tanks; large cylindrical
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`vessels fixed to a truck chassis, trailer tanks; large cylindrical vessels mounted on a truck
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`trailer chassis, and rail tank cars; large cylindrical vessels mounted on rolling stock.
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`Using the propylene polymer foam for thermal insulation of IMO tank
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`containers planks with the desired shape (550 by 2750 by 50 mm) are first cut by hand to
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`create recesses for inlets, outlets, and steam pipes. Three planks (or more or less if smaller
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`or larger planks are used) are circumferentially applied side-by-side to the shell of the
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`pressure vessel between two reinforcing ribs. The planks are held by tightening straps,
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`clips, adhesives or any other suitable fastening means and the adjacent foam edges can be
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`welded together using hot air. Finally, the outer cladding is applied to the tank.
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`The present invention also encomp