Patent Application
20240317984
The invention relates to a polymer composition comprising a high melt strength polypropylene and mixtures thereof, as well as to foam comprising said composition, a process for the preparation of said foam, articles prepared with said foam and the use of the composition to prepare articles.
Foamable polymer compositions are known in the art. These are used for the preparation of foams in many shapes, such as sheets, rods, tubes, profiles etc. The advantage of using foams is that they are lightweight, thereby reducing transportation costs and downgauging of the amount of material used.
For some applications, such as insulation tubes for pipes for hot water, steam or hot oil, it is important that the foam retains its mechanical properties at high temperatures. Foams having a higher temperature resistance are known, such as elastomer foamed by using AZO compounds and polyurethane foams, but said materials have a number of disadvantageous over polyolefins. For example, such materials can be less easily processed and recycled than polyolefins.
WO01/94092A1 discloses a polyolefin foam that is resistance to temperatures of about 105° C. or higher, so that said foams are suitable for e.g. use as insulation material for hot water and steam pipes. According to WO01/94092A1 such foam is produced by a process wherein a homogeneous mixture comprising one of more polyolefins, selected from polypropylenes and polyethylenes and a physical foaming agent and having a melt range as measured by means of scanning differential calorimetry, within the range of 120 to 160° C., is produced, which subsequently, optionally after cooling and granulating, is extruded. In the example of WO01/94092A1, a tubular insulation foam is produced containing from 30 to 65% by weight of Elenac 2426 F low density polyethylene and from 30 to 65% by weight of Lupolen 4261 AG high density polyethylene. However, the resistance of such foam is still too low for certain applications, depending on the heat of the fluid to be transported in the pipe. In addition, a higher heat resistance also provides for a bigger safety margin and may result in a longer life-time for the foam.
Since polypropylene has a higher melting temperature than polyethylene, high melt strength polypropylene foams are preferred over polyethylene foams for high temperature applications. However, as explained above, for some applications, an even better thermostability of the foam is desired.
Therefore, it is the object of the invention to provide foams having a higher thermostability (higher maximum service temperature).
This object is achieved by a polymer composition comprising A) a high melt strength polypropylene in an amount ≥30 wt % and ≤90 wt % based on the polymer composition B) an ethylene-based elastomer having a density ≥855 to ≤913 kg/m3, wherein the density is determined in accordance with ASTM D792 (2008), wherein the ethylene-based elastomer is present in the polymer composition in an amount ≥10 wt % and ≤49 wt % based on the polymer composition and
U.S. Pat. No. 5,929,129A discloses a foamable, crosslinkable extruded profile comprising a composition including a blend of non-silane-grafted polypropylene with silane-grafted, essentially linear polyolefin, wherein the polyolefin has a resin density in the range of about 0.86 g/cm3 to about 0.96 g/cm3, a melt index in the range of about 0.5 dg/min to about 100 dg/min, a molecular weight distribution in the range of from about 1.5 to about 3.5, and a composition distribution breadth index greater than about 45 percent. EP0963406A1 discloses a rheology-modified, substantially gel-free TPE composition comprising at least one elastomeric EAO polymer or EAO polymer blend and at least one high melting polymer selected from polypropylene homopolymers and propylene/ethylene copolymers, the composition having at least three of four characteristics, the characteristics being a STI ≥20 a MS ≥1.5 times that of the composition without rheology modification a ST ≥10° C. greater than that of the composition without rheology modification, and an UST limit ≥10° C. greater than that of the composition without rheology modification.
Surprisingly, it has been found that the addition of an ethylene-based copolymer (which has a lower melting temperature) to a polypropylene composition (which has a higher melting temperature than the ethylene-based copolymer) increases the maximum service temperature of the foams prepared from such composition. In addition, an increase in the maximum service temperature of the foams prepared from such composition may increase the life-time of the foams.
The FIGURE shows a set up for measurements of melt strength on a Göttfert Rheograph 6000 at a temperature of 200° C. in accordance with ISO standard 16790:2005.
Maximum service temperature is defined herein as the highest temperature at which the insulation product, when installed at a recommended thickness in a given application, continues to function with the specified limits of its performance as determined in accordance with EN14707 and Annex B (version October 2012).
In the context of the invention, with ‘foamed’ or ‘foam’ is meant that the shape has a lower density due to the presence of gas bubbles (such as air) as compared to the density of the same material without gas bubbles.
Preferably, the melt flow rate of the polymer composition is ≥0.50 and ≤8.0 g/10 min, preferably ≥0.70 and ≤5.0 g/10 min, more preferably ≥1.0 and ≤4.0 g/10 min as determined in accordance with ASTM D1238 (2013) at a temperature of 230° C. under a load of 2.16 kg.
Preferably, the high melt strength polypropylene composition has a lowest melting temperature T1 and wherein the ethylene-based elastomer has a highest melting temperature T2 and wherein T1 is at least 20° C. higher than T2 and wherein T1 is at most 105° C. higher than T2 and wherein T1 and T2 are measured using differential scanning calorimetry (DSC). Preferably, T1 is at least 40° C. higher than T2 and at most 70° C. higher than T2. More preferably, T1 is at least 450° C. higher than T2 and at most 65° C. higher than T2. Most preferably, T1 is at least 50° C. higher than T2 and at most 60° C. higher than T2.
In case the high melt strength polypropylene composition has more than one melting temperature, T1 is the lowest melting temperature measured using DSC. In case the ethylene-based elastomer has more than one melting temperature, T2 is the highest melting temperature measured using DSC.
High melt strength polypropylenes are available in the art. Typically such polypropylenes are branched polypropylene. A branched polypropylene differs from a linear polypropylene in that the polypropylene backbone has side chains, whereas a non-branched (linear) polypropylene does not have side chains on its backbone. There are different ways to achieve branching in polypropylenes. For example, branching can be achieved by using a specific catalyst, for example a specific single-site catalyst, or by chemical modification. EP 1892264 described the preparation of a branched polypropyleen obtained by the use of a specific catalyst. EP0879830 describes the preparation of a branched polypropylene by chemical modification.
WO2009/003930A1 discloses an irradiated polymer composition comprising at least one polyolefin resin and at least one non-phenolic stabilizer, wherein the irradiated polymer composition is produced by a process comprising mixing the polyolefin resin with the non-phenolic stabilizer and irradiating this mixture in a reduced oxygen environment. By using the process of WO2009/003930, branched polypropylenes can also be obtained.
Examples of commercially available high melt strength polypropylene include but are not limited to Daploy™ polypropylenes available from Borealis and Bourouge, e.g. Daploy™ WB 135HMS, Daploy™ 135HMS or Daploy™ WB260HMS.
In addition, a high melt strength polypropylene is available from SABIC as SABIC® PP UMS 561P as of 18 Feb. 2021.
Preferably, the high melt strength polypropylene is prepared by
Examples of non-phenolic stabilizers are known in the art and are for example disclosed on pages 37-60 of WO2009/003930A1, hereby incorporated by reference. Preferably, the non-phenolic stabilizer is chosen from the group of hindered amines.
More preferably, the non-phenolic stabilizer comprises at least one hindered amine selected from the group of Chimassorb® 944, Tinuvin® 622, Chimassorb® 2020, Chimassorb® 119, Tinuvin® 770, and mixtures thereof, separate or in combination with at least one hydroxylamine, nitrone, amine oxide, or benzofuranone selected from N,N-di(hydrogenated tallow)amine (Irgastab® FS-042), an N,N-di(alkyl)hydroxylamine produced by a direct oxidation of N,N-di(hydrogenated tallow)amine (Irgastab® FS-042), N-octadecyl-α-heptadecylnitrone, Genox™ EP, a di(C16-C18) alkyl methyl amine oxide, 3-(3,4-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one, Irganox® HP-136 (BFI), and mixtures thereof, and separate or in combination with at least one organic phosphite or phosphonite selected from tris(2,4-di-tert-butylphenyl) phosphite (Irgafos® 168). Even more preferably, the non-phenolic stabilizers of the present subject matter can include those described in U.S. Pat. Nos. 6,664,317 and 6,872,764, both of which are incorporated herein by reference in their entirety.
Preferably, the high melt strength polypropylene has a melt strength ≥10 cN and ≤100 cN, wherein the melt strength is determined in accordance with ISO 16790:2005 at a temperature of 200° C., using a cylindrical capillary having a length of 20 mm and a width of 2 mm, a starting velocity v0 of 9.8 mm/s and an acceleration of 6 mm/s2.
Preferably, the high melt strength polypropylene has a melt strength ≥10 cN, preferably ≥20 cN, more preferably ≥30 cN, more preferably ≥40 cN, more preferably ≥45 cN. Even more preferably, the melt strength of the high melt strength polypropylene is ≥50 cN, more preferably ≥55 cN, even more preferably ≥60 cN, most preferably ≥65 cN and/or preferably the melt strength of the high melt strength polypropylene composition is ≤95 cN, for example ≤90 cN, for example ≤87 cN.
The melt strength of the high melt strength polypropylene is determined in accordance with ISO 16790:2005 at a temperature of 200° C., using a cylindrical capillary having a length of 20 mm and a width of 2 mm, a starting velocity v0 of 9.8 mm/s and an acceleration of 6 mm/s2.
With polypropylene as used herein is meant propylene homopolymer, a copolymer of propylene with an α-olefin or a heterophasic propylene copolymer.
Preferably, the high melt strength polypropylene is a polypropylene chosen from the group of propylene homopolymers and propylene copolymers comprising moieties derived from propylene and one or more comonomers chosen from the group of ethylene and alpha-olefins with ≥4 and ≤12 carbon atoms.
Preferably, the propylene copolymer comprises moieties derived from one or more comonomers chosen from the group of ethylene and alpha-olefins with ≥4 and ≤12 carbon atoms in an amount of ≤10 wt %, for example in an amount of ≥1.0 and ≤7.0 wt % based on the propylene copolymer, wherein the wt % is determined using 13C NMR. For example, the propylene copolymer comprises moieties derived from one or more comonomer chosen from the group of ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene and 1-dodecene, preferably moieties derived from ethylene.
Preferably, the melt flow rate of the high melt strength polypropylene is ≥0.50 and ≤8.0 g/10 min, preferably ≥0.70 and ≤5.0 g/10 min, more preferably ≥1.0 and ≤4.0 g/10 min as determined in accordance with ASTM D1238 (2013) at a temperature of 230° C. under a load of 2.16 kg.
Polypropylenes and the processes for the synthesis of polypropylenes are known. A propylene homopolymer is obtained by polymerizing propylene under suitable polymerization conditions. A propylene copolymer is obtained by copolymerizing propylene and one or more other comonomers, for example ethylene, under suitable polymerization conditions. The preparation of propylene homopolymers and copolymers is for example described in Moore, E. P. (1996) Polypropylene Handbook. Polymerization, Characterization, Properties, Processing, Applications, Hanser Publishers: New York.
Propylene homopolymers, propylene copolymers and heterophasic propylene copolymers can be made by any known polymerization technique as well as with any known polymerization catalyst system. Regarding the techniques, reference can be given to slurry, solution or gas phase polymerizations; regarding the catalyst system reference can be given to Ziegler-Natta, metallocene or single-site catalyst systems. All are, in themselves, known in the art.
Preferably, the high melt strength polypropylene has a VOC value as determined in accordance with VDA278 (2011-10) ≤250 μg/g, preferably a VOC value ≤50 μg/g and/or an FOG value as determined in accordance with VDA278 (2011-10)≤500 μg/g, preferably an FOG-value ≤100 μg/g.
Preferably, the high melt strength polypropylene has a melt flow rate ≥0.5 and ≤8.0 g/10 min, more preferably ≥0.7 and ≤5.0 g/10 min, most preferably ≥1.0 and ≤4.0 g/10 min as determined in accordance with ASTM D1238 (2013) at a temperature of 230° C. under a load of 2.16 kg.
The high melt strength polypropylene is present in the polymer composition in an amount ≥30 wt % and ≤90 wt % based on the polymer composition, preferably in an amount ≥40 wt % and ≤85 wt % based on the polymer composition, for example in an amount ≥50 wt % and ≤80 wt % based on the polymer composition.
The polymer composition may further comprise additives, such as for example flame retardants, pigments, lubricants, slip agents flow promoters, antistatic agents, processing stabilizers, long term stabilisers and/or UV stabilizers. The additives may be present in any desired amount to be determined by the man skilled in the art, but are preferably present ≥0.001 wt % and ≤5.0 wt %, more preferably ≥0.01 wt % and ≤4.0 wt %, even more preferably ≥0.01 wt % and ≤3.0 wt %, even more preferably ≥0.01 wt % and ≤2.0 wt % based on the polymer composition.
Preferably, the high melt strength polypropylene, the ethylene-based elastomer and the further polypropylene are present in an amount ≥85 wt %, preferably ≥90 wt % based on the polymer composition.
The polymer composition may further comprise a nucleating agent. A nucleating agent may be desired to increase the cell density and to modify the dynamics of bubble formation and growth. (Gendron, Thermoplastic foam Processing, 2005, page 209). The amount of nucleating agent may for example be ≥0.010 wt % and ≤5.0 wt %, for example ≥0.030 wt % and ≤4.0 wt %, for example ≥0.050 wt % and ≤3.0 wt %, preferably ≥0.10 wt % and ≤2.5 wt %, more preferably ≥0.30 wt % and ≤1.5 wt % based on the polymer composition, most preferably ≥0.50 wt % and ≤1.2 wt % based on the polymer composition.
Suitable nucleating agents include but are not limited to talc, silica and a mixture of sodium bicarbonate and citric acid. Other suitable nucleating agents include amides, for example azo dicarbonamide, amines and/or esters of a saturated or unsaturated aliphatic (C10-C34) carboxylic acid. Examples of suitable amides include fatty acid (bis)amides such as for example stearamide, caproamide, caprylamide, undecylamide, lauramide, myristamide, palmitamide, behenamide and arachidamide, hydroxystearamides and alkylenediyl-bis-alkanamides, preferably (C2-C32) alkylenediyl-bis-(C2-C32) alkanamides, such as for example ethylene bistearamide (EBS), butylene bistearamide, hexamethylene bistearamide, ethylene bisbehenamide and mixtures thereof. Suitable amines include or instance (C2-C18) alkylene diamines such as for example ethylene biscaproamine and hexamethylene biscaproamine. Preferred esters of a saturated or unsaturated aliphatic (C10-C34) carboxylic acid are the esters of an aliphatic (C16-C24) carboxylic acid. Preferably, the nucleating agent is chosen from the group of talc, sodium bicarbonate, citric acid, azodicarbonamide and mixtures thereof, more preferably the nucleating agent is talc.
For the preparation of the foam, it may be desired to use a cell stabilizer. Therefore, the invention also relates to a polymer composition of the invention further comprising a cell stabilizer. Cell stabilizers are permeability modifiers which retard the diffusion of for example hydrocarbons such as isobutane to create dimensionally stable foams. (Gendron, Thermoplastic foam Processing, 2005, pages 31 and 149) Preferred cell stabilizers include but are not limited to glycerol monostearate (GMS), glycerol monopalmitate (GMP), palmitides and/or amides. Suitable amides are for example stearyl stearamide, palmitide and/or stearamide. Suitable mixtures include for example a mixture comprising GMS and GMP or a mixture comprising stearamide and palmitamide. Preferably, in case a cell stabilizer is used, the cell stabilizer is glycerol monostearate or stearamide.
The amount of cell stabiliser to be added depends on desired cell size and the polymer composition used for the preparation of the foam. Generally, the cell stabiliser may be added in an amount ≥0.10 and ≤4.0 wt %.
Therefore, the polymer composition may further comprise a nucleating agent and/or a cell stabilizer.
Ethylene-based elastomers may be prepared using methods known in the art, for example by using a single site catalyst, i.e., a catalyst the transition metal components of which is an organometallic compound and at least one ligand of which has a cyclopentadienyl anion structure through which such ligand bondingly coordinates to the transition metal cation. This type of catalyst is also known as “metallocene” catalyst. Metallocene catalysts are for example described in U.S. Pat. Nos. 5,017,714 and 5,324,820. The elastomers may also be prepared using traditional types of heterogeneous multi-sited Ziegler-Natta catalysts.
Processes for the preparation of ethylene-based elastomers are known in the art, and include but are not limited to solution processes.
Preferably the ethylene-based elastomer is present in an amount ≥10 wt % and ≤49 wt %, for example in an amount ≥15 wt % and ≤47 wt % based on the polymer composition.
Preferably, the density of the ethylene-based elastomer is in the range from 865 to 905 kg/m3, preferably in the range from 895-905 kg/m3, wherein the density is determined in accordance with ASTM D792 (2008).
Preferably, the ethylene-based elastomer is produced using a metallocene catalyst. Preferably, the ethylene-based elastomer comprises moieties derived from ethylene and moieties derived from one or more of 1-butene, 1-hexene and 1-octene, for example 1-octene. For example, the ethylene-based elastomer may comprise ≥5.0 and ≤20.0 wt % of moieties derived from one or more of 1-butene, 1-hexene and 1-octene, preferably derived from one or more of 1-hexene and 1-octene, more preferably derived from 1-octene. Preferably, the ethylene-based elastomer comprises ≥5.0 and ≤20.0 wt % of moieties derived from 1-hexene or 1-octene. Ethylene-based elastomers are commercially available. Examples of commercially available ethylene-1-octene copolymers include but are not limited to ethylene-1-octene sold under the name SABIC® COHERE, SABIC® FORTIFY or SABIC® SUPEER.
Preferably, the melt flow rate of the ethylene-based elastomer is ≥0.30 and ≤8.0 g/10 min, preferably ≥0.50 and ≤6.0 g/10 min, more preferably ≥0.70 and ≤5.0 as determined in accordance with ASTM D1238 (2013) at a temperature of 190° C. under a load of 2.16 kg.
In one embodiment, the polymer composition further comprises a further polypropylene, preferably a further polypropylene in an amount of ≥10 wt % and ≤40 wt % based on the polymer composition.
The further polypropylene can be a propylene homopolymer, a propylene copolymer, for example a copolymer of propylene with an α-olefin as described herein or a heterophasic propylene copolymer, for example a heterophasic propylene copolymer as described herein.
Preferably, the melt flow rate of the further polypropylene is ≥0.3 and ≤8.0 g/10 min, more preferably ≥0.5 and ≤6.0 g/10 min, for example ≥0.7 and ≤5.0 g/10 min as determined in accordance with ASTM D1238 (2013) at a temperature of 230° C. under a load of 2.16 kg.
In another aspect, the invention relates to a foam comprising the polymer composition of the invention. Preferably, the polymer composition is present in the foam in an amount ≥95 wt % based on the foam. For example, the polymer composition is present in the foam in an amount ≥96 wt %, ≥97 wt %, ≥98 wt %, ≥99 wt %, ≥99.5 wt % based on the foam. Preferably, the foam consists of the polymer composition of the invention.
The polymer composition may further comprise a nucleating agent and/or a cell stabilizer.
The polymer composition may further comprise a nucleating agent. A nucleating agent may be desired to increase the cell density and to modify the dynamics of bubble formation and growth. (Gendron, Thermoplastic foam Processing, 2005, page 209).
The amount of nucleating agent may for example be ≥0.010 wt % and ≤5.0 wt %, for example ≥0.030 wt % and ≤4.0 wt %, for example ≥0.050 wt % and ≤3.0 wt %, preferably ≥0.10 wt % and ≤2.5 wt %, more preferably ≥0.30 wt % and ≤1.5 wt % based on the polymer composition, most preferably ≥0.50 wt % and ≤1.2 wt % based on the polymer composition. Suitable nucleating agents include but are not limited to talc, silica and a mixture of sodium bicarbonate and citric acid. Other suitable nucleating agents include amides, for example azo dicarbonamide, amines and/or esters of a saturated or unsaturated aliphatic (C10-C34) carboxylic acid. Examples of suitable amides include fatty acid (bis)amides such as for example stearamide, caproamide, caprylamide, undecylamide, lauramide, myristamide, palmitamide, behenamide and arachidamide, hydroxystearamides and alkylenediyl-bis-alkanamides, preferably (C2-C32) alkylenediyl-bis-(C2-C32) alkanamides, such as for example ethylene bistearamide (EBS), butylene bistearamide, hexamethylene bistearamide, ethylene bisbehenamide and mixtures thereof. Suitable amines include or instance (C2-C18) alkylene diamines such as for example ethylene biscaproamine and hexamethylene biscaproamine. Preferred esters of a saturated or unsaturated aliphatic (C10-C34) carboxylic acid are the esters of an aliphatic (C16-C24) carboxylic acid. Preferably, the nucleating agent is chosen from the group of talc, sodium bicarbonate, citric acid, azodicarbonamide and mixtures thereof, more preferably, the nucleating agent is talc.
For the preparation of the foam, it may be desired to use a cell stabilizer. Cell stabilizers are permeability modifiers which retard the diffusion of for example hydrocarbons such as isobutane to create dimensionally stable foams. (Gendron, Thermoplastic foam Processing, 2005, pages 31 and 149) Preferred cell stabilizers include but are not limited to glycerol monostearate (GMS), glycerol monopalmitate (GMP), palmitides and/or amides. Suitable amides are for example stearyl stearamide, palmitide and/or stearamide. Suitable mixtures include for example a mixture comprising GMS and GMP or a mixture comprising stearamide and palmitamide. Preferably, in case a cell stabilizer is used, the cell stabilizer is glycerol monostearate or stearamide.
The amount of cell stabilizer to be added depends on desired cell size and the polymer composition used for the preparation of the foamed sheet. Generally, the cell stabiliser may be added in an amount ≥0.10 and ≤3.0 wt % relative to the polymer composition.
Preferably, the density of the foam is ≤650 kg/m3 and ≥10 kg/m3, preferably ≤500 kg/m3 and ≥15 kg/m3, for example ≤300 kg/m3 and ≥15 kg/m3, for example ≤100 kg/m3 and ≥15 kg/m3, for example ≤50 kg/m3 and ≥20 kg/m3, wherein the density is determined according to ISO 845 (2006).
Preferably, the foam has an open cell content of ≤15.0%, preferably ≤12.0%, more preferably ≤10.0%, even more preferably ≤7.0%, even more preferably ≤5.0%, even more preferably ≤4.0%, even more preferably ≤3.0%, even more preferably ≤2.0%, wherein the open cell content is determined according to ASTM D6226-10.
Processes for the preparation of polypropylene foams and foamed sheets are within the knowledge of the person skilled in the art. In such a process, a melt of a composition of the high melt strength polypropylene mixed with a gaseous or liquid blowing agent is suddenly expanded through a pressure drop. Continuous foaming processes as well as discontinuous processes may be applied. In a continuous foaming process, the polymer composition is melted and laden with gas in an extruder under pressures typically above 20 bar before being extruded through a die where the pressure drop causes the formation of a foam. The mechanism of foaming polypropylene in such foam extrusion process is explained, for example, in H. E. Naguib, C. B. Park, N. Reichelt, Fundamental foaming mechanisms governing the volume expansion of extruded polypropylene foams, Journal of Applied Polymer Science, 91, 2661-2668 (2004). Processes for foaming are outlined in S. T. Lee, Foam Extrusion, Technomic Publishing (2000). In a discontinuous foaming process, the polypropylene composition (micro-)pellets are laden with foaming agent under pressure and heated below melting temperature before the pressure in the autoclave is suddenly relaxed. The dissolved foaming agent forms bubbles and creates a foam structure.
Examples of foaming processes include but are not limited to extrusion processes, injection molding processes, a blow-molding processes, autoclave processes and rotomolding processes.
In another aspect, the invention relates to a process for the preparation of the foam of the invention. In particular, the invention relates to a process for the preparation of the foam of the invention, comprising the sequential steps of:
The amount of blowing agent for example depends on the desired density and the polymer composition used. For example, the blowing agent may be used in an amount ≥0.10 wt % and ≤20 wt % based on the polymer composition.
Examples of suitable physical blowing agents include, but are not limited to isobutane, CO2, pentane, butane, nitrogen and/or a fluorohydrocarbon. Preferably, the physical blowing agent is isobutane and/or CO2, most preferably isobutane.
Examples of suitable chemical blowing agents include, but are not limited to citric acid or a citric acid-based material (e.g. mixtures of citric acid and sodium bicarbonate) and azo dicarbonamide. Such chemical blowing agents are for example commercially available from Clariant Corporation under for example the name Hydrocerol™ CF-40E™ or Hydrocerol™ CF-05E™.
In case foamed sheets are prepared, these may be stretched monoaxially or biaxially using a manner known per se.
Therefore, the invention also relates to a process for the preparation of the foamed sheet of the invention, comprising the sequential steps of:
The invention also relates to the foamed sheet of the invention, which foamed sheet is stretched in at least one direction, for example the invention relates to the foamed sheet of the invention, wherein the foamed sheet is monoaxially stretched (for example in the machine direction) or for example, the invention relates to the foamed sheet of the invention wherein the foamed sheet is biaxially stretched, for example in both the machine direction (MD) and in the transverse direction (MD). As is known to the person skilled in the art, the stretching in MD and TD may be carried out simultaneously, or in consecutive steps.
The draw ratio in MD may for example be ≥1.1 and ≤7.0, for example ≥1.1 and ≤3.0. The draw ratio in transverse direction may for example be ≥1.1 and ≤7.0, for example ≥1.1 and ≤3.0.
The foams of the invention can suitable be used for the preparation of articles. Examples of articles comprising the foams of the invention include but are not limited to pipes, films, sheets, profiles, rods, planks or tubes. Preferably, the article is an insulation article, for example a pipe insulation article, for example a pipe insulation tube.
In another aspect, the invention relates to the use of the polymer composition of the invention for the preparation of a foam.
It is noted that the invention relates to the subject-matter defined in the independent claims alone or in combination with any possible combinations of features described herein, preferred in particular are those combinations of features that are present in the claims. It will therefore be appreciated that all combinations of features relating to the compositions according to the invention; all combinations of features relating to the processes according to the invention and all combinations of features relating to the compositions according to the invention and features relating to the processes according to the invention are described herein.
It is further noted that the term ‘comprising’ does not exclude the presence of other elements. However, it is also to be understood that a description on a product/composition comprising certain components also discloses a product/composition consisting of these components. The product/composition consisting of these components may be advantageous in that it offers a simpler, more economical process for the preparation of the product/composition. Similarly, it is also to be understood that a description on a process comprising certain steps also discloses a process consisting of these steps. The process consisting of these steps may be advantageous in that it offers a simpler, more economical process.
The invention is now elucidated by way of the following examples, without however being limited thereto.
The melting temperature of the polymers was measured using a differential scanning calorimeter (DSC, TA Instruments Q20) on the second heating cycle using a heating rate of 10° C./min and a cooling rate of 10° C./min and a temperature range of −40 to 200° C.
Melt strength was measured according to ISO standard 16790:2005. Melt strength is defined as the maximum (draw-down) force (in cN) by which a molten thread can be drawn before it breaks, e.g. during a Rheotens measurement. Measurements were done on a Gottfert Rheograph 6000 at a temperature of 200° C. with a setup like shown in FIG. 1 of ISO standard 16790:2005. The rheometer has an oven with a diameter of 12 mm. A capillary of 20 mm length and 2 mm width was used. The entrance angle of the capillary was 180° (flat). The piston in the rheometer moved with a velocity of 0.272 mm/s to obtain an exit velocity v0, of 9.8 mm/s. After filling the rheometer, the melt was held in the rheometer for 5 minutes, to stabilize the temperature and fully melt the polymer. The strand that exits the capillary was drawn with a Rheotens II from Goettfert with an acceleration of 6 mm/s2 until breakage occurred. The distance between the exit of the capillary and the uptake wheels of the Rheotens II (=draw length) was 100 mm.
The pressure required to push the melted polymer through the capillary, the maximum drawing force (=Melt strength) and the maximum draw ratio at breakage were recorded.
The melt flow rate of the polymers was determined in accordance with ASTM D1238 (2013) at a temperature of 190° C. (MFR190) or 230° C. (MFR230) under a load of 2.16 kg.
The density of the polymers was determined in accordance with ASTM D792 (2008).
Density of the foam (kg/m3) is the apparent overall density and was determined according to ISO 845:2006.
The open cell content was determined by using a Quantachrome Pentapyc 5200e gas pycnometer using a method based on ASTM D6226-10. The volume from the external dimensions of the sample was determined by using the Archimedes' principle by immersing the sample in water. It was assumed that the uptake of water by the sample can be neglected. After drying the sample from adhering water, the sample volume (VSPEC) was determined by the pycnometer according ASTM D6226-10 at different pressures.
All applied pressures were below 0.1 bar to minimize compression of the foam.
Where:
The sample volume of the foam was plotted against the applied pressures (0.090 bar; 0.075 bar, 0.060 bar, 0.045 bar, 0.035 bar, 0.020 bar and 0.010 bar). A straight line was fit through the measurement points, using linear regression. The interception of the linear regression line with the Y-axis at p=0 bar is the volume (VSPEC_0) used in equation below.
The open cell content Vopen (%) was calculated using the following formula:
Where:
The maximum service temperature was determined in accordance with EN14707 and Annex B (version October 2012). To this end, the foam samples were subjected to a temperature increase at a rate of 50° C./min and maintained for a period of 72 hours at the temperatures specified in Table 2 below and the thickness of the samples was recorded after having maintained the samples at the specified temperature for a period of 72 hours. The deviation of the thickness of the sample as compared to the initial thickness at 23° C. was plotted against the temperatures and the measurement points were connected. The temperature at which the plot did not show a deviation of the thickness of the sample as compared to the original thickness of the sample was recorded as the maximum service temperature.
The outside and inside diameter the extruded pipes were measured without applying any pressure to the pipe (nor on the inside nor on the outside).
POP is an ethylene-octene-copolymer commercially available from SABIC as SABIC® COHERE 8102. It is an ethylene-based elastomer and is an ethylene-octene copolymer produced via a solution polymerization process using a metallocene catalyst and has a melt flow rate MFR190 of 1.0 g/10 min, a density of 902 kg/m3 and a melting temperature (Tm) of 100° C.
PPUMS is a is a long chain branched propylene homopolymer which is commercially available from SABIC as SABIC® PPUMS 561P as of 18 Feb. 2021, having a melt flow rate MFR230 of 2.5 g/10 min and a melt strength of 71 cN. The melting temperature of PP-UMS is 162° C.
hPP is a linear propylene homopolymer, commercially available from SABIC as SABIC® PP 525P having a melt flow rate MFR230 of 3.0 g/10 min, a Tm of 165° C. and a density of 905 kg/m3.
AS is a Atmer™ 7300 50% MB, which is a 50% concentrate in polyethylene contains an anti-static agent and which is commercially available from Croda.
Talc is POLYBATCH® FPE 50 T, which is a 50% masterbatch of talcum in polyethylene and which is commercially available fom LyondellBasell.
PS is Irganox® B225 is a blend of 50 wt % Irgafos® 168 (an organic phosphite of low volatility) and 50 wt % Irganox 1010 (hindered phenolic antioxidant) and is a processing and long term thermal stabilizer system; it is commercially available from BASF.
Polyolefin foam tubes were prepared from the materials listed above, in weight % as indicated in the below Table 1. To this end, the materials and additives were fed into the feed hopper of a 30 mm twin screw extruder with a length of 40D and an additional meltcooler with oil as heat-transfer medium. Additionally, the extruder was equipped with a short static mixer for the well defined temperature mix of the melt and a 8 mm×4.5 mm tube die. After the material mixture was melted at a temperate of 215° C., 7 wt % isobutane based on the composition used was injected into the molten material mixture and admixed therewith, after which the mixture was cooled down to a temperature of 153° C. to obtain additional melt strength. Finally, the mixture was extruded through the die orifice at a die-pressure of 19.5 bar, thereby producing a hollow foam tube. A die of 8 mm with a 4.5 mm thorn was used creating an annular shaped opening. Upon emerging from the die orifice, the foam tube was expanded and fully shaped and cooled before at a distance of several meters and drawn by a pull off-unit. The polyolefin foams were processed with an output of 20 kg/h.
The thickness of the foams thus prepared was measured at different temperatures in accordance with EN14707 and Annex B (version October 2020) and the results are shown in
As can be seen from the above results, the foams prepared from the compositions of the invention have a higher maximum service temperature than the comparative examples. The use of a further propylene, for example a propylene homopolymer increases the maximum service temperature even further. This makes the compositions of the invention very suitable for applications for which a higher maximum service temperature is required, such as foams used for insulation of pipe used for transporting high temperature fluids, such as hot water or oil; or gas.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21157928.9 | Feb 2021 | EP | regional |
| 21157932.1 | Feb 2021 | EP | regional |
| 21157935.4 | Feb 2021 | EP | regional |
| 21157966.9 | Feb 2021 | EP | regional |
| 21157969.3 | Feb 2021 | EP | regional |
This application is a National Stage application of PCT/EP2022/054075, filed Feb. 18, 2022, which claims the benefit of European Application No. 21157928.9, filed Feb. 18, 2021, European Application No. 21157932.1, filed Feb. 18, 2021, European Application No. 21157935.4, filed Feb. 18, 2021, European Application No. 21157966.9, filed Feb. 18, 2021, European Application No. 21157969.3, filed Feb. 18, 2021, all of which are incorporated by reference in their entirety herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/054075 | 2/18/2022 | WO |
