HMS PP foam sheet with good compressive strength and recovery rate

Abstract

The present invention relates to a foamed sheet comprising a polypropylene composition containing at least 85% by weight, e.g., 85 to 99.5% by weight, of a high melt strength polypropylene (HMS-PP) and 0.5 to 15% by weight of a nucleating agent (NA), the foamed sheet having a thickness of less than 0.5 mm or a thickness of 2.0 mm or more. The present invention further relates to a foamed material comprising the polypropylene composition, and to the use of the polypropylene composition containing at least 85% by weight, e.g., 85 to 99.5% by weight, of a high melt strength polypropylene (HMS-PP) and 0.5 to 15% by weight of a nucleating agent (NA), for producing a foamed material.

Description

[Technical field]

[0001] The present invention relates to a foamed sheet made of a polypropylene composition comprising at least 85% by weight, for example 85-99.5% by weight, of a high melt strength polypropylene (HMS-PP) and 0.5-15% by weight of a nucleating agent (NA), the foamed sheet having a thickness of less than 0.5 mm or a thickness of 2.0 mm or more. The present invention further relates to a foamed material made of the polypropylene composition, as well as the use of the polypropylene composition comprising at least 85% by weight, for example 85-99.5% by weight, of a high melt strength polypropylene (HMS-PP) and 0.5-15% by weight of a nucleating agent (NA) for producing a foamed material. [Background technology]

[0002] Foams of different thicknesses are used in a wide variety of applications. For example, thick foams are commonly used in packaging and in various applications such as automotive, building and construction. In packaging, foams are used to protect items during transportation, and in the field of building and construction applications, foams are typically used as flooring underlays and insulation materials. An exemplary application of thin foams is in loudspeaker membranes. Foams used in these applications must combine sufficient load-bearing capacity (measured as compressive or tensile strength) with good recovery after the load is released (measured as the average recovery rate after load exposure). Foams based on polystyrene and LDPE are commonly used in these applications. PS foams have good load-bearing capacity but poor foam recovery rate. On the other hand, LDPE-based foams have good recovery but poor load-bearing capacity. Summary of the Invention [Problem to be solved by the invention]

[0003] It is therefore an object of the present invention to develop a foam means which combines good load bearing capacity with excellent recovery properties. [Means for solving the problem]

[0004] To this end, in a first embodiment, the present invention provides a foamed sheet made of a polypropylene composition comprising, or preferably consisting of, at least 85 wt %, for example 85 to 99.5 wt %, of a high melt strength polypropylene (HMS-PP) and 0.5 to 15 wt % of a nucleating agent (NA), the foamed sheet having a thickness of less than 0.5 mm or a thickness of 2.0 mm or more.

[0005] In a second embodiment, the present invention comprises a polypropylene composition, satisfying the following relationships (I) and (II): Compressive strength at 25% compression / (foam density) 2 >0.018kPa / (kg / m 3 ) 2 (I) In the above formula (I), Compressive strength at 25% is the compressive strength determined at 25% without a precompression cycle [0] according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m 3 It is expressed in units, Compressive strength at 40% / (foam density) 2 >0.020kPa / (kg / m 3 ) 2 (II) In the above formula (II), Compressive strength at 40% is the compressive strength determined at 40% without a precompression cycle [0] according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m 3 It is expressed in units, and further having a recovery rate, as determined according to the method specified in the Examples herein, of at least 85%. A foam material is provided.

[0006] The foam sheets and foam materials of the present invention can be provided in different thicknesses. For example, thin foam sheets and foam materials can be used in some applications such as loudspeaker membranes, which usually require a thickness of less than 0.5 mm, whereas thick foam sheets and foam materials are typically used in applications such as flooring underlays and insulation materials, or automobiles, which usually require a thickness of 2.0 mm or more. The foam sheets and foam materials of the present invention surprisingly have good compressibility and at the same time good recovery, thereby overcoming the problems of polystyrene and LDPE-based foams outlined above.

[0007] The foamed sheet according to the first embodiment preferably satisfies the following relationship (I). Compressive strength at 25% / (foam density) 2 >0.018kPa / (kg / m 3 ) 2 (I) In the above formula (I), Compressive strength at 25% is the compressive strength determined at 25% without a precompression cycle [0] according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m 3 It is expressed in units.

[0008] The foamed sheet according to the first embodiment preferably satisfies the following relationship (II). Compressive strength at 40% / (foam density) 2 >0.020kPa / (kg / m 3 ) 2 (II) In the above formula (II), Compressive strength at 40% is the compressive strength determined at 40% without a precompression cycle [0] according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m 3 It is expressed in units.

[0009] The foam sheet according to the first embodiment preferably has a recovery rate, determined according to the method specified in the examples herein, of at least 85%.

[0010] More preferably, the foam sheet according to the first embodiment satisfies relationships (I) and (II) and has a recovery rate, determined according to the method specified in the examples herein, of at least 85%.

[0011] The foamed material according to the second embodiment is preferably in the form of a foamed sheet, the polypropylene composition comprising, preferably consisting of, at least 85 wt. %, for example 85-99.5 wt. %, of high melt strength polypropylene (HMS-PP) and 0.5-15 wt. % of a nucleating agent (NA), the foamed sheet having a thickness of less than 0.5 mm or a thickness of 2.0 mm or more.

[0012] Below, all embodiments of the present invention, including any preferred variations, are described unless expressly stated to the contrary. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] High Melt Strength Polypropylene (HMS-PP) High melt strength polypropylene is branched and therefore differs from linear polypropylene in that the polypropylene backbone extends into side chains whereas unbranched, i.e. linear polypropylene does not. The side chains have a significant effect on the rheology of polypropylene. Thus, linear polypropylene and high melt strength polypropylene can be clearly distinguished by their flow behavior under stress.

[0014] Branching can generally be achieved by using specific catalysts, i.e. specific single-site catalysts, or by chemical modification. For the preparation of branched polypropylene obtained by using specific catalysts, reference is made to EP 1 892 264. For branched polypropylene obtained by chemical modification, reference is made to EP 0 879 830 A1. In such cases, the branched polypropylene is also called high melt strength polypropylene. The high melt strength polypropylene (HMS-PP) according to the invention is obtained by chemical modification of polypropylene (PP) as described in more detail below. HMS-PP is commercially available from Borealis AG under the trade name Daploy™.

[0015] Therefore, in order to provide a resulting polypropylene composition with good shear thinning properties, the high melt strength polypropylene (HMS-PP) should have an F of greater than 25.0 cN. 30 Melt strength and v > 205mm / sec 30 It has melt extensibility, preferably F of more than 25.0 to 50.0 cN. 30 Melt strength and v of 205 to 300 mm / sec 30 It has melt extensibility. F 30 Melt strength and v 30 Melt extensibility is measured according to ISO 16790:2005.

[0016] In a preferred embodiment, the high melt strength polypropylene (HMS-PP) is (a) F of more than 25.0 to 45.0 cN, preferably more than 25.0 to 42.0 cN, and most preferably more than 25.0 cN to 40.0 cN 30 Melt strength, and (b) v of 210 to 300 mm / sec, more preferably 215 to 290 mm / sec, even more preferably 220 to 270 mm / sec, and most preferably 225 to 260 mm / sec 30 Melt Extensibility has.

[0017] In a particularly preferred embodiment, the high melt strength polypropylene (HMS-PP) has a F of greater than 25.0 to 45.0 cN. 30 Melt strength and v of 210~300mm / sec 30 Melt extensibility, e.g., F of 25.0 to 42.0 cN 30 Melt strength and v of 215~290mm / sec 30 Melt extensibility, or F of 25.0 to 40.0 cN 30 Melt strength and v of 220~270mm / sec 30 Melt extensibility, or F of 25.0 to 40.0 cN 30 Melt strength and v of 225-260mm / sec 30 It has melt extensibility.

[0018] Furthermore, the high melt strength polypropylene (HMS-PP) preferably has a melt flow rate MFR measured according to ISO 1133 of 15.0 g / 10 min or less, more preferably in the range of 0.5 to 15.0 g / 10 min, even more preferably in the range of 1.0 to 15.0 g / 10 min, for example in the range of 1.5 to 15.0 g / 10 min. 2 (230°C).

[0019] In a particularly preferred embodiment, the high melt strength polypropylene (HMS-PP) has a melt flow rate MFR measured according to ISO 1133 of 7.0 g / 10 min or less, preferably in the range of 0.5 to 7.0 g / 10 min, more preferably in the range of 0.5 to 6.5 g / 10 min, even more preferably in the range of 0.5 to 6.0 g / 10 min, even more preferably in the range of 1.0 to 6.0 g / 10 min, for example in the range of 1.5 to 5.0 g / 10 min. 2 (230°C).

[0020] Thus, in one particular embodiment, the high melt strength polypropylene (HMS-PP) is (a) a melt flow rate MFR of 15.0 g / 10 min or less, more preferably in the range of 0.5 to 15.0 g / 10 min, even more preferably in the range of 1.0 to 15.0 g / 10 min, for example in the range of 1.5 to 15.0 g / 10 min 2 (230°C), and (b) F of more than 25.0 cN, preferably more than 25.0 to 50.0 cN, more preferably more than 25.0 to 45.0 cN, even more preferably more than 25.0 to 42.0 cN, and most preferably more than 25.0 cN to 40.0 cN. 30 Melt strength, and (c) a v of greater than 205 mm / sec, preferably greater than 205 to 300 mm / sec, more preferably 210 to 300 mm / sec, even more preferably 215 to 290 mm / sec, even more preferably 220 to 270 mm / sec, and most preferably 225 to 260 mm / sec 30 Melt Extensibility has.

[0021] In a particularly preferred embodiment, the high melt strength polypropylene (HMS-PP) is (a) A melt flow rate MFR of 7.0 g / 10 min or less, preferably in the range of 0.5 to 7.0 g / 10 min, more preferably in the range of 0.5 to 6.5 g / 10 min, even more preferably in the range of 0.5 to 6.0 g / 10 min, even more preferably in the range of 1.0 to 6.0 g / 10 min, for example in the range of 1.5 to 5.0 g / 10 min. 2 (230°C), and (b) F of more than 25.0 cN, preferably more than 25.0 to 50.0 cN, more preferably more than 25.0 to 45.0 cN, even more preferably more than 25.0 to 42.0 cN, and most preferably more than 25.0 cN to 40.0 cN. 30 Melt strength, and (c) a v of greater than 205 mm / sec, preferably greater than 205 to 300 mm / sec, more preferably 210 to 300 mm / sec, even more preferably 215 to 290 mm / sec, even more preferably 220 to 270 mm / sec, and most preferably 225 to 260 mm / sec 30 Melt Extensibility has.

[0022] Thus, in certain embodiments, the high melt strength polypropylene (HMS-PP) has a melt flow rate MFR in the range of 0.5 to 15.0 g / 10 min. 2 (230℃), F of 25.0 to 45.0cN 30 Melt strength and v of 210~300mm / sec30 Melt extensibility, e.g., melt flow rate (MFR) in the range of 1.0 to 15.0 g / 10 min 2 (230℃), F of 25.0 to 42.0cN 30 Melt strength and v of 215~290mm / sec 30 Melt extensibility, or melt flow rate (MFR) in the range of 1.0 to 15.0 g / 10 min 2 (230℃), F of 25.0 to 40.0cN 30 Melt strength and v of 220~270mm / sec 30 Melt extensibility, or melt flow rate (MFR) in the range of 1.5 to 15.0 g / 10 min 2 (230℃), F of 25.0 to 40.0cN 30 Melt strength and v of 225-260mm / sec 30 It has melt extensibility.

[0023] Thus, in another particular embodiment, the high melt strength polypropylene (HMS-PP) has a melt flow rate MFR in the range of 0.5 to 7.0 g / 10 min. 2 (230℃), F of 25.0 to 45.0cN 30 Melt strength and v of 210~300mm / sec 30 Melt extensibility, e.g., melt flow rate (MFR) in the range of 1.0 to 15.0 g / 10 min 2 (230℃), F of 25.0 to 42.0cN 30 Melt strength and v of 215~290mm / sec 30 Melt extensibility, or melt flow rate (MFR) in the range of 1.0 to 6.0 g / 10 min 2 (230℃), F of 25.0 to 40.0cN 30 Melt strength and v of 220~270mm / sec 30 Melt extensibility, or melt flow rate (MFR) in the range of 1.5 to 5.0 g / 10 min 2 (230℃), F of 25.0 to 40.0cN 30 Melt strength and v of 225-260mm / sec 30 It has melt extensibility.

[0024] Preferably, the high melt strength polypropylene (HMS-PP) has a melting point of at least 130° C., more preferably at least 135° C., and most preferably at least 140° C. The crystallization temperature is preferably at least 110° C., more preferably at least 120° C.

[0025] Furthermore, the high melt strength polypropylene (HMS-PP) can be a high melt strength random propylene copolymer (R-HMS-PP) or a high melt strength propylene homopolymer (H-HMS-PP), the latter being preferred.

[0026] For the purposes of the present invention, the expression "propylene homopolymer" refers to a polypropylene consisting essentially of propylene units, i.e. at least 97 mol%, preferably at least 98 mol%, more preferably at least 99 mol%, most preferably at least 99.8 mol%. In a preferred embodiment, only propylene units in the propylene homopolymer are detectable.

[0027] When the high melt strength polypropylene (HMS-PP) is a high melt strength random propylene copolymer (R-HMS-PP), it is a copolymerizable monomer with propylene, such as ethylene and / or C 4 ~C 12 α-olefins, in particular ethylene and / or C 4 ~C 10It comprises a comonomer such as an α-olefin, for example 1-butene and / or 1-hexene. Preferably, the high melt strength random propylene copolymer (R-HMS-PP) comprises, and in particular consists of, monomers copolymerizable with propylene from the group consisting of ethylene, 1-butene and 1-hexene. More specifically, the high melt strength random propylene copolymer (R-HMS-PP) comprises, apart from propylene, units derivable from ethylene and / or 1-butene. In a preferred embodiment, the high melt strength random propylene copolymer (R-HMS-PP) consists exclusively of units derivable from ethylene and propylene. The comonomer content in the high melt strength random propylene copolymer (R-HMS-PP) is preferably in the range of more than 0.2 to 10.0 mol %, even more preferably in the range of more than 0.5 to 7.0 mol %.

[0028] In this regard, it should be mentioned that the high melt strength polypropylene (HMS-PP), either the high melt strength propylene homopolymer (H-HMS-PP) or the high melt strength random propylene copolymer (R-HMS-PP), may contain additional unsaturated monomers different from the comonomers defined for the high melt strength random propylene copolymer (R-HMS-PP). In other words, the high melt strength propylene homopolymer (H-HMS-PP) or the high melt strength random propylene copolymer (R-HMS-PP) is a copolymer of propylene, ethylene and other C propylene copolymers, such as difunctional unsaturated monomers and / or polyfunctional unsaturated low molecular weight polymers as defined in detail below. 4 ~C 12 It may contain unsaturated units different from the α-olefins.The definition of homopolymers and copolymers in terms of high melt strength polypropylene (HMS-PP) therefore actually refers to unmodified polypropylene, i.e. polypropylene (PP), preferably linear polypropylene (1-PP), used to obtain the melt strength polypropylene (HMS-PP) by chemical modification, as defined in detail below.

[0029] Thus, in one preferred embodiment, the high melt strength polypropylene (HMS-PP) is (a) High melt strength polypropylene (HMS-PP), (i) propylene, and (ii) Difunctional unsaturated monomer(s) and / or polyfunctional unsaturated low molecular weight polymer(s) where the high melt strength propylene homopolymer (H-HMS-PP) unit is derived from or (b) High melt strength polypropylene (HMS-PP), (i) Propylene (ii) ethylene and / or C 4 ~C 12 α-olefins, such as 1-butene and / or 1-hexene, preferably ethylene, and (iii) Difunctional unsaturated monomer(s) and / or polyfunctional unsaturated low molecular weight polymer(s) In the case of high melt strength random propylene copolymer (R-HMS-PP) units derived from Includes.

[0030] "Difunctionally unsaturated" or "polyfunctionally unsaturated" as used above preferably means the presence of two or more non-aromatic double bonds, as for example in divinylbenzene or cyclopentadiene or polybutadiene. Preferably only such difunctional or polyfunctionally unsaturated compounds are used that can be polymerized with the aid of free radicals (see below). The unsaturated sites in the difunctional or polyfunctionally unsaturated compounds are in a chemical bond state that is not actually "unsaturated", since the double bonds are each used for covalent bonding to the polymer chain of unmodified polypropylene, i.e. polypropylene (PP), preferably linear polypropylene (l-PP).

[0031] The reaction of the preferably difunctional unsaturated monomers and / or polyfunctionally unsaturated low molecular weight polymers, synthesized from one and / or several unsaturated monomers, having a number average molecular weight (Mn) of less than or equal to 10000 g / mol, with unmodified polypropylene, i.e. with polypropylene (PP), preferably with linear polypropylene (1-PP), is carried out in the presence of a thermal free radical former, such as a decomposing free radical former, such as a thermally decomposing peroxide.

[0032] The difunctional unsaturated monomer is Divinyl compounds such as divinylaniline, m-divinylbenzene, p-divinylbenzene, divinylpentane and divinylpropane; Allyl compounds such as allyl acrylate, allyl methacrylate, allyl methyl maleate, and allyl vinyl ether; Dienes such as 1,3-butadiene, chloroprene, cyclohexadiene, cyclopentadiene, 2,3-dimethylbutadiene, heptadiene, hexadiene, isoprene, and 1,4-pentadiene; Aromatic and / or aliphatic bis(maleimide) bis(citraconimide) and mixtures of these unsaturated monomers may be also possible.

[0033] Particularly preferred difunctional unsaturated monomers are 1,3-butadiene, isoprene, dimethylbutadiene and divinylbenzene.

[0034] Polyfunctional unsaturated low molecular weight polymers, preferably having a number average molecular weight (Mn) of 10,000 g / mole or less, may be synthesized from one or more unsaturated monomers.

[0035] Examples of such low molecular weight polymers are: Polybutadienes, especially those with different microstructures in the polymer chain, i.e. 1,4-cis, 1,4-trans and 1,2-(vinyl) predominantly in the 1,2-(vinyl) configuration; Copolymer of butadiene and styrene with 1,2-(vinyl) in the polymer chain It is.

[0036] A preferred low molecular weight polymer is polybutadiene, especially polybutadiene having greater than 50.0 weight percent butadiene in the 1,2-(vinyl) configuration.

[0037] The high melt strength polypropylene (HMS-PP) may contain a plurality of difunctional unsaturated monomers and / or polyfunctional unsaturated low molecular weight polymers. Even more preferably, the amount of the difunctional unsaturated monomers and polyfunctional unsaturated low molecular weight polymers in the high melt strength polypropylene (HMS-PP) is 0.01 to 10.0% by weight based on said high melt strength polypropylene (HMS-PP).

[0038] In a preferred embodiment, the high melt strength polypropylene (HMS-PP) does not contain additives (A). Thus, if the polypropylene composition contains additives (A), these additives (A) are not introduced into the polypropylene composition during the production of the high melt strength polypropylene (HMS-PP).

[0039] The high melt strength polypropylene (HMS-PP) more preferably has a low gel content, typically less than 1.00 wt.%, preferably less than 0.80 wt.%, more preferably less than 0.50 wt.%.

[0040] As mentioned above, high melt strength polypropylene (HMS-PP) may be obtained by treating polypropylene (PP), preferably linear polypropylene (l-PP), with a thermally degradable radical former. However, in such a case there is a high risk that the polypropylene (PP), preferably linear polypropylene (PP), will degrade, which is detrimental. Therefore, chemical modification is preferably achieved by additional use of difunctional unsaturated monomer(s) and / or polyfunctional unsaturated low molecular weight polymer(s) as chemically bonded crosslinking units. Suitable methods for obtaining high melt strength polypropylene (HMS-PP) are disclosed, for example, in EP 0787750, EP 0879830A1 and EP 0890612A2. All documents are hereby incorporated by reference. Thereby, the amount of thermally degradable radical former, preferably peroxide, is preferably in the range of 0.05 to 3.00% by weight based on the amount of polypropylene (PP). Typically, the thermally decomposable radical formers are added to polypropylene (PP), preferably to linear polypropylene (1-PP), together with the difunctional unsaturated monomer(s) and / or polyfunctional unsaturated low molecular weight polymer(s). However, it is also possible, but less preferred, to add the difunctional unsaturated monomer(s) and / or polyfunctional unsaturated low molecular weight polymer(s) first to the polypropylene (PP), preferably to the linear polypropylene (1-PP), followed by the thermally decomposable radical formers, or alternatively, to add the thermally decomposable radical formers first to the polypropylene (PP), preferably to the linear polypropylene (1-PP), followed by the difunctional unsaturated monomer(s) and / or polyfunctional unsaturated low molecular weight polymer(s).

[0041] For difunctional unsaturated monomers and / or polyfunctional unsaturated low molecular weight polymers used to make high melt strength polypropylene (HMS-PP), see the section above.

[0042] As mentioned above, the difunctionally unsaturated monomers and / or polyfunctionally unsaturated low molecular weight polymers are preferably used in the presence of a thermally decomposable free radical former.

[0043] Peroxides are the preferred thermally decomposable free radical formers. More preferably, the thermally decomposable free radical formers are selected from the group consisting of acyl peroxides, alkyl peroxides, hydroperoxides, peresters and peroxycarbonates.

[0044] The following peroxides are particularly preferred:

[0045] Acyl peroxides: benzoyl peroxide, 4-chlorobenzoyl peroxide, 3-methoxybenzoyl peroxide and / or methylbenzoyl peroxide.

[0046] Alkyl peroxides: allyl t-butyl peroxide, 2,2-bis(t-butylperoxybutane), 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(t-butylperoxy)valerate, diisopropylaminomethyl-t-amyl peroxide, dimethylaminomethyl-t-amyl peroxide, diethylaminomethyl-t-butyl peroxide, dimethylaminomethyl-t-butyl peroxide, 1,1-di-(t-amylperoxy)cyclohexane, t-amyl peroxide, t-butylcumyl peroxide, t-butyl peroxide and / or 1-hydroxybutyl n-butyl peroxide. Peresters and peroxycarbonates: butyl peracetate, cumyl peracetate, cumyl perpropionate, cyclohexyl peracetate, di-t-butyl peradipate, di-t-butyl perzelaate, di-t-butyl perglutarate, di-t-butyl perphthalate, di-t-butyl persebacate, 4-nitrocumyl perpropionate, 1-phenylethyl perbenzoate, phenylethyl nitroperbenzoate, t-butyl bicyclo-(2,2,1)heptane percarboxylate, t-butyl 4-carbomethoxyperbutyrate, t-butyl cyclobutane percarboxylate, t-butyl cyclohexylpercarboxylate, t-butyl cyclopentylpercarboxylate, t-butyl cyclopropanepercarboxylate, t-butyl dimethylpercinnamate, 2-(2,2-diphenyl vinyl) t-butyl perbenzoate, t-butyl 4-methoxyperbenzoate, t-butyl carboxycyclohexane, t-butyl pernaphthoate, t-butyl isopropyl percarbonate, t-butyl pertoluate, t-butyl 1-phenylcyclopropyl percarboxylate, t-butyl 2-propyl-2-perpentenoate, t-butyl 1-methylcyclopropyl percarboxylate, t-butyl 4-nitrophenyl peracetate, t-butyl nitrophenyl percarbamate, t-butyl N-succinimide percarboxylate, t-butyl percrotonate, t-butyl permaleate, t-butyl permethacrylate, t-butyl peroctanoate, t-butyl isopropyl percarbonate, t-butyl perisobutyrate, t-butyl peracrylate and / or t-butyl perpropionate.

[0047] Mixtures of these above-listed free radical formers are also contemplated.

[0048] A suitable HMS-PP is WB140HMS™ available from Borealis AG.

[0049] Polypropylene (PP) As mentioned above, high melt strength polypropylene (HMS-PP) is a modified polypropylene obtained by reacting polypropylene (PP) with a thermally decomposable free radical former and, optionally, with difunctional unsaturated monomer(s) and / or polyfunctional unsaturated low molecular weight polymer(s). The polypropylene (PP) is preferably linear polypropylene (l-PP).

[0050] Polypropylene (PP), preferably linear polypropylene (l-PP), has a melt flow rate MFR, measured according to ISO 1133, in the range of 0.1 to 45.0 g / 10 min, for example 0.1 to 40.0 g / 10 min or 0.1 to 35.0 g / 10 min. 2 (230°C), more preferably 0.1 to 30.0 g / 10 min, even more preferably 0.1 to 28.0 g / 10 min, and even more preferably 0.1 to 25.0 g / 10 min. 2 (230°C).

[0051] High melt strength polypropylene (HMS-PP) differs from the polypropylene (PP) used in its production in that the main chain of the high melt strength polypropylene (HMS-PP) extends to side chains, whereas the starting material, i.e., polypropylene (PP), including the preferred linear polypropylene (l-PP), does not or hardly extends to side chains. The side chains have a significant effect on the rheology of polypropylene. Thus, the starting material, i.e., polypropylene (PP), and the resulting high melt strength polypropylene (HMS-PP) can be clearly distinguished by their flow behavior under stress.

[0052] Moreover, as mentioned above, the polypropylene (PP) is preferably linear polypropylene (l-PP). The same considerations apply to the polypropylene (PP') discussed in detail below, which in a preferred embodiment is also linear polypropylene (l-PP'). Thus, throughout the present invention, the term "linear polypropylene" indicates that the linear polypropylene does not exhibit or exhibits almost no branching structure. Due to the absence of branching, the linear polypropylene, i.e., linear polypropylene (l-PP) and linear polypropylene (l-PP'), preferably has a low v 30 Melt extensibility and / or low F 30 Characterized by melt strength.

[0053] Therefore, linear polypropylene (l-PP) is (a) F of less than 30.0 cN, preferably less than 30.0 cN, preferably less than 27.0 cN, more preferably in the range of 1.0 to less than 30.0 cN, even more preferably in the range of 1.5 to less than 30.0 cN, even more preferably in the range of 2.0 to less than 27.0 cN, and even more preferably in the range of 2.5 to less than 27.0 cN. 30 Melt strength, and (b) v less than 220 mm / sec, preferably less than 210 mm / sec, more preferably in the range of 80 to 200 mm / sec, and most preferably in the range of 100 to 200 mm / sec 30 Melt Extensibility It is preferred that the compound has the formula:

[0054] In other words, linear polypropylene (l-PP) has an F of less than 30.0 cN. 30 Melt strength and v less than 220mm / sec 30 Melt extensibility, preferably F less than 27.0 cN 30 Melt strength and v less than 210mm / sec 30 Melt extensibility, more preferably F in the range of 1.0 to less than 30.0 cN 30 Melt strength and v in the range of 80-200 mm / sec 30 Melt extensibility, even more preferably in the range of F of 1.5 to less than 30.0 cN 30Melt strength and v in the range of 100-200 mm / sec 30 Melt extensibility, even more preferably in the range of 2.0 to less than 27.0 cN 30 Melt strength and v in the range of 100-200 mm / sec 30 Melt extensibility, e.g., F in the range of 2.5 to less than 27.0 cN 30 It is preferred that it has melt strength.

[0055] Thus, in one particular embodiment, the linear polypropylene (l-PP) is (a) a melt flow rate MFR measured according to ISO 1133 in the range of 0.1 to 45.0 g / 10 min, for example 0.1 to 40.0 g / 10 min or 0.1 to 35.0 g / 10 min, more preferably 0.1 to 30.0 g / 10 min, even more preferably 0.1 to 28.0 g / 10 min, and even more preferably 0.1 to 25.0 g / 10 min. 2 (230°C), and (b) F of less than 30.0 cN, preferably less than 27.0 cN, more preferably in the range of 1.0 to less than 30.0 cN, even more preferably in the range of 1.5 to less than 30.0 cN, even more preferably in the range of 2.0 to less than 27.0 cN, and even more preferably in the range of 2.5 to less than 27.0 cN. 30 Melt strength, and (c) v less than 220 mm / sec, preferably less than 210 mm / sec, more preferably in the range of 80 to 200 mm / sec, and most preferably in the range of 100 to 200 mm / sec 30 Melt Extensibility has.

[0056] Therefore, in one particular embodiment, the polypropylene (PP) has a melt flow rate MFR of 0.1 to 45.0 g / 10 min. 2 (230℃), F less than 30.0cN 30 Melt strength and v less than 220mm / sec 30 Melt extensibility, preferably a melt flow rate (MFR) in the range of 0.1 to 40.0 g / 10 min 2 (230℃), F less than 30.0cN 30 Melt strength and v less than 210mm / sec 30Melt extensibility, preferably a melt flow rate (MFR) in the range of 0.1 to 35.0 g / 10 min 2 (230℃), F in the range of 1.0 to less than 30.0cN 30 Melt strength and v in the range of 80-200 mm / sec 30 Melt extensibility, and even more preferably a melt flow rate MFR in the range of 0.1 to 30.0 g / 10 min 2 (230℃), F in the range of 1.5 to less than 30.0cN 30 Melt strength and v in the range of 100-200 mm / sec 30 Melt extensibility, even more preferably a melt flow rate MFR in the range of 0.1 to 28.0 g / 10 min 2 (230℃), F in the range of 2.0 to less than 27.0cN 30 Melt strength and v in the range of 100-200 mm / sec 30 Melt extensibility, e.g., melt flow rate (MFR) in the range of 0.1 to 25.0 g / 10 min 2 (230℃), F in the range of 2.5 to less than 27.0cN 30 Melt strength and v in the range of 100-200 mm / sec 30 It is a linear polypropylene (l-PP) that has melt extensibility.

[0057] Preferably, the polypropylene (PP), preferably linear polypropylene (1-PP), has a melting point of at least 140°C, more preferably at least 150°C, even more preferably at least 158°C.

[0058] Polypropylene (PP), preferably linear polypropylene (l-PP), can be produced in known manner, for example by using single-site or Ziegler-Natta catalysts. Polypropylene (PP), preferably linear polypropylene (l-PP), can be a propylene homopolymer (H-PP), preferably a linear propylene homopolymer (lH-PP), or a propylene copolymer (R-PP), preferably a linear propylene copolymer (lR-PP). With regard to the comonomer content and type of comonomer, reference is made to the information provided above for the high melt strength random propylene copolymer (R-HMS-PP). Preferably, the polypropylene (PP) is a linear polypropylene (l-PP). Even more preferably, the polypropylene (PP) is a linear propylene homopolymer (lH-PP). Thus, the melt flow rate MFR 2 (230℃), melting point, F 30 Melt strength, v 30 All information provided regarding melt extensibility and particle size (particle size) and particle size distribution, respectively, applies specifically to linear propylene homopolymer (lH-PP).

[0059] In a preferred embodiment, the polypropylene (PP), preferably the linear polypropylene (1-PP), does not contain additives (A). Thus, if the polypropylene composition contains additives (A), these additives (A) are preferably not introduced into the polypropylene composition during the production of the high melt strength polypropylene (HMS-PP).

[0060] Nucleating Agent (NA) The polypropylene composition (PC) further comprises one or more, preferably one, nucleating agent.

[0061] In general, it is understood that the polypropylene composition (PC) can include any nucleating agent typically used in the products prepared and known to those skilled in the art.

[0062] For example, suitable nucleating agents include phosphorus-based nucleating agents, such as phosphorus mono-, bis- or tetraphenyl esters, or organic alpha nucleating agents (alpha nucleating agents) selected from the group of phosphate ester metal salts represented by the formula: [ka] In the above formula, R1 is oxygen, sulfur, or a hydrocarbon group of 1 to 10 carbon atoms, R2 and R3 are each hydrogen, or a hydrocarbon or hydrocarbon group having 1 to 10 carbon atoms, R2 and R3 may be the same or different from each other, two of R2, two of R3, or R2 and R3 may be bonded to form a ring, M is a monovalent to trivalent metal atom, n is an integer of 1 to 3, and m is either 0 or 1, with the proviso that n>m.

[0063] Preferred examples of the α-nucleating agent represented by the above formula include: Sodium-2,2'-methylene-bis(4,6-di-tert-butyl-phenyl)phosphate, Sodium-2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)-phosphate, Lithium-2,2'-methylene-bis(4,6-di-tert-butylphenyl)phosphate, Lithium-2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)phosphate, Sodium-2,2'-ethylidene-bis(4-i-propyl-6-tert-butylphenyl)phosphate Lithium-2,2'-methylene-bis(4-methyl-6-tert-butylphenyl)phosphate, Lithium-2,2'-methylene-bis(4-ethyl-6-tert-butylphenyl)phosphate, Calcium bis[2,2'-thiobis(4-methyl-6-tert-butyl-phenyl)-phosphate], Calcium bis[2,2'-thiobis(4-ethyl-6-tert-butylphenyl)phosphate], Calcium bis[2,2'-thiobis(4,6-di-tert-butylphenyl)phosphate], Magnesium bis[2,2'-thiobis(4,6-di-tert-butylphenyl)phosphate], Magnesium bis[2,2'-thiobis(4-t-octylphenyl)phosphate], Sodium-2,2'-butylidene-bis(4,6-dimethylphenyl)phosphate, Sodium-2,2'-butylidene-bis(4,6-di-tert-butyl-phenyl)-phosphate, Sodium-2,2'-t-octylmethylene-bis(4,6-dimethyl-phenyl)-phosphate, Sodium-2,2'-t-octylmethylene-bis(4,6-di-tert-butylphenyl)-phosphate, Calcium bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl)-phosphate], Magnesium bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl)-phosphate], barium bis[2,2'-methylene-bis(4,6-di-tert-butylphenyl)-phosphate], Sodium-2,2'-methylene-bis(4-methyl-6-tert-butylphenyl)-phosphate, Sodium-2,2'-methylene-bis(4-ethyl-6-tert-butylphenyl)phosphate, Sodium (4,4'-dimethyl-5,6'-di-tert-butyl-2,2'-biphenyl) phosphate, Calcium bis-[(4,4'-dimethyl-6,6'-di-tert-butyl-2,2'-biphenyl)phosphate], Sodium-2,2'-ethylidene-bis(4-m-butyl-6-tert-butyl-phenyl)phosphate Sodium-2,2'-methylene-bis-(4,6-dimethylphenyl)-phosphate, Sodium-2,2'-methylene-bis(4,6-di-t-ethyl-phenyl)phosphate, Potassium-2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)-phosphate, Calcium bis[2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)-phosphate], Magnesium bis[2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)-phosphate] barium bis[2,2'-ethylidene-bis-(4,6-di-tert-butylphenyl)-phosphate], Aluminum hydroxy-bis[2,2'-methylene-bis(4,6-di-tert-butyl-phenyl)phosphate], Aluminum tris[2,2'-ethylidene-bis(4,6-di-tert-butylphenyl)-phosphate] Examples include:

[0064] The second group of phosphorus-based nucleating agents includes, for example, aluminum-hydroxy-bis[2,4,8,10-tetrakis(1,1-dimethylethyl)-6-hydroxy-12H-dibenzo-[d,g]-dioxa-phoshocin-6-oxidato] and its blends with Li myristate or Li stearate.

[0065] Sorbitol-based nucleating agents such as optionally substituted dibenzylidene sorbitol (e.g., 1,3:2,4 dibenzylidene sorbitol, 1,3:2,4 di(methylbenzylidene) sorbitol, 1,3:2,4 di(ethylbenzylidene) sorbitol, 1,3:2,4 bis(3,4-dimethylbenzylidene) sorbitol, etc.) or pine rosin can also be used as a nucleating agent.

[0066] Further suitable alpha nucleating agents are polymeric nucleating agents selected from the group consisting of vinylcycloalkane polymers and vinylalkane polymers. Nucleation with these polymeric nucleating agents is achieved by special reactor techniques in which the catalyst is prepolymerized with a monomer such as, for example, vinylcyclohexane (VCH), or by blending a propylene polymer with a vinyl(cyclo)alkane polymer. These methods are described in more detail, for example, in EP 0316187 A2 and WO 99 / 24479, the disclosures of which are incorporated herein by reference.

[0067] In addition, suitable alpha-nucleating agents for the polyolefin composition of the present invention are, for example, the nucleating agents described in Macromolecules 2005, 38, 3688-3695, the disclosure of which is incorporated herein by reference.

[0068] Nucleating agents such as ADK NA-11 (methylene-bis(4,6-di-t-butylphenyl)phosphate sodium salt) and ADK NA-21 (aluminum hydroxy-bis[2,4,8,10-tetrakis(1,1-dimethylethyl)-6-hydroxy-12H-dibenzo-[d,g]-dioxa-phosphocin-6-oxidato]) are also suitable and are commercially available from Asahi Denka Kogyo Co. Millad 3988 (3,4-dimethylbenzylidene sorbitol), Millad 3905, and Millad 3940 available from Milliken & Company are other examples of nucleating agents that may be utilized in the present invention.

[0069] Further commercially available alpha nucleating agents which can be used in the compositions of the invention are, for example, Irgaclear XT 386 (N-[3,5-bis-(2,2-dimethyl-propionylamino)-phenyl]-2,2-dimethylpropionamide) from Ciba Specialty Chemicals, Hyperform HPN-68L and Hyperform HPN-20E from Milliken & Company.

[0070] Nonitol-based nucleating agents are also suitable, such as 1,2,3-trideoxy-4,6:5,7-bis-O-((4-propylphenyl)methylene)nonitol (CAS number 882073-43-0, e.g. Millad NX8000, supplier Milliken).

[0071] Further suitable nucleating agents are the chemical blowing agents available from Clariant under the trade name "Hydrocerol".

[0072] Talc is a further suitable nucleating agent.

[0073] Talc is particularly preferred. In a preferred embodiment, talc is the only nucleating agent present in the polypropylene composition (PC).

[0074] The particle size d50 of the nucleating agent, for example talc, is in the range of 1 μm to 30 μm, preferably in the range of 2 μm to 25 μm, more preferably in the range of 5 μm to 20 μm, and most preferably in the range of 5 μm to 15 μm.

[0075] Additive (A) The additive (A) can be any additive useful in the technical field of high melt strength polypropylene (HMS-PP) and its applications.The additive (A) used in the polypropylene composition of the present invention, and therefore in the form of the additive mixture (AM), can include, but is not limited to, stabilizers, such as antioxidants (e.g., highly hindered phenols, phosphites / phosphonites, sulfur-containing antioxidants, alkyl radical scavengers, aromatic amines, hindered amine stabilizers, or blends thereof), metal deactivators (e.g., Irganox MD 1024), or UV stabilizers (e.g., hindered amine light stabilizers). Other typical additives are modifiers such as antistatic or antifogging agents (e.g. ethoxylated amines and amides, or glycerol esters), acid scavengers, adhesion agents (cling agents, e.g. polyisobutene), lubricants and resins (ionomer waxes, PE waxes and ethylene copolymer waxes, Fischer-Tropsch waxes, montan waxes, fluorinated compounds, or paraffin waxes), and slip and antiblocking agents (e.g. Ca stearate, erucamide, oleamide, talc, natural and synthetic silica, or zeolites). Preferably, additive (A) is selected from the group consisting of antioxidants (e.g., highly hindered phenols, phosphites / phosphonites, sulfur-containing antioxidants, alkyl radical scavengers, aromatic amines, hindered amine stabilizers, or blends thereof), metal deactivators (e.g., Irganox MD 1024), UV stabilizers (e.g., hindered amine light stabilizers), antistatic or antifog agents (e.g., ethoxylated amines and amides, or glycerol esters), acid scavengers, adhesion agents (e.g., polyisobutene), lubricants and resins (ionomer waxes, PE waxes and ethylene copolymer waxes, Fischer-Tropsch waxes, montan waxes, fluorine-based compounds, or paraffin waxes), slip agents (e.g., Ca stearate), antiblocking agents (e.g., erucamide, oleamide, talc, natural and synthetic silica, or zeolites), and mixtures thereof.

[0076] A preferred additive is a slip agent, such as calcium stearate.

[0077] As outlined above, additive (A) does not include nucleating agents.

[0078] Typically, the total amount of additive (A) is 15 wt% or less, more preferably 10 wt% or less, for example in the range of 0.1 to 10 wt%, preferably 0.1 to 5 wt%, more preferably 0.2 to 1 wt%, based on the total weight of the polypropylene composition.

[0079] Polypropylene Composition In a first embodiment, as outlined above, the foam sheet comprises a polypropylene composition comprising at least 85 wt.%, for example 85-99.5 wt.%, of a high melt strength polypropylene (HMS-PP) and 0.5-15 wt.% of a nucleating agent (NA).

[0080] For example, the foam sheet comprises a polypropylene composition comprising at least 85% by weight, such as 85-99.5% by weight, of high melt strength polypropylene (HMS-PP) and 0.5-15% by weight of a nucleating agent (NA).

[0081] Preferably, the polypropylene composition according to the first embodiment is 85 to 95% by weight, preferably 87.5 to 92.5% by weight, of the high melt strength polypropylene (HMS-PP); 5.0 to 15% by weight, preferably 7.5 to 12.5% ​​by weight, of the nucleating agent (NA); and preferably consists of:

[0082] For example, the polypropylene composition according to the first embodiment is 85 to 95% by weight, preferably 87.5 to 92.5% by weight, of high melt strength polypropylene (HMS-PP); 5.0 to 15 wt. %, preferably 7.5 to 12.5 wt. %, of a nucleating agent (NA); Additive (A) in the range of up to 15% by weight, preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, and most preferably 0.2 to 1% by weight. and preferably consists of:

[0083] In the second embodiment, preferably the polypropylene composition comprises: At least 85% by weight, for example 85 to 99.5% by weight, more preferably 85 to 95% by weight, even more preferably 87.5 to 92.5% by weight, of high melt strength polypropylene (HMS-PP); 0.5 to 15% by weight, more preferably 5.0 to 15% by weight, even more preferably 7.5 to 12.5% ​​by weight of a nucleating agent (NA); and preferably consists of:

[0084] For example, the polypropylene composition is At least 85% by weight, for example 85 to 99.5% by weight, more preferably 85 to 95% by weight, even more preferably 87.5 to 92.5% by weight, of high melt strength polypropylene (HMS-PP); 0.5 to 15 wt. %, more preferably 5.0 to 15 wt. %, even more preferably 7.5 to 12.5 wt. % of a nucleating agent (NA); Additive (A) in the range of up to 15% by weight, preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, and most preferably 0.2 to 1% by weight. and preferably consists of:

[0085] In a preferred embodiment, the polypropylene composition comprises: At least 85% by weight, for example 85 to 99.5% by weight, more preferably 85 to 95% by weight, even more preferably 87.5 to 92.5% by weight, of high melt strength polypropylene (HMS-PP); 0.5-15% by weight, more preferably 5.0-15% by weight, even more preferably 7.5-12.5% ​​by weight of talc as a nucleating agent (NA); and preferably consists of:

[0086] For example, the polypropylene composition is At least 85% by weight, for example 85 to 99.5% by weight, more preferably 85 to 95% by weight, even more preferably 87.5 to 92.5% by weight, of high melt strength polypropylene (HMS-PP); 0.5 to 15% by weight, more preferably 5.0 to 15% by weight, even more preferably 7.5 to 12.5% ​​by weight of talc as a nucleating agent (NA); Additive (A) in the range of up to 15% by weight, preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, and most preferably 0.2 to 1% by weight. and preferably consists of: Unless otherwise stated, it is understood that all amounts are based on the total weight of the polypropylene composition.

[0087] In the following preferred features of the polypropylene composition according to all embodiments of the present invention are described.

[0088] In a preferred variant, other than the high melt strength polypropylene (HMS-PP), the other polymers are only present in a total amount not exceeding 5 wt.-%, more preferably not exceeding 2 wt.-%, even more preferably not exceeding 1 wt.-%, based on the total weight of the polymeric materials present in the polypropylene composition.

[0089] As mentioned above, high melt strength polypropylene (HMS-PP) is the major part of the polypropylene composition. Therefore, it is preferred that the final polypropylene composition exhibits similar rheological behavior as the high melt strength polypropylene (HMS-PP).

[0090] Therefore, in order to provide a resulting polypropylene composition with good shear thinning properties, the polypropylene composition preferably has an F of greater than 25.0 cN. 30 Melt strength and v > 205mm / sec 30 It has melt extensibility, preferably F of more than 25.0 to 50.0 cN. 30 Melt strength and v of 205 to 300 mm / sec 30It has melt extensibility. F 30 Melt strength and v 30 Melt extensibility is measured according to ISO 16790:2005.

[0091] In a preferred embodiment, the polypropylene composition comprises (a) F of more than 25.0 to 45.0 cN, preferably more than 25.0 to 42.0 cN, and most preferably more than 25.0 cN to 40.0 cN 30 Melt strength, and (b) v of more than 210 to 300 mm / sec, more preferably 215 to 290 mm / sec, even more preferably 220 to 270 mm / sec, and most preferably 225 to 260 mm / sec 30 Melt Extensibility has.

[0092] In a particularly preferred embodiment, the polypropylene composition has an F of more than 25.0 to 45.0 cN. 30 Melt strength and v of 215~290mm / sec 30 Melt extensibility, e.g., F of 25.0 to 42.0 cN 30 Melt strength and v of 215~290mm / sec 30 Melt extensibility, or F of 25.0 to 40.0 cN 30 Melt strength and v of 220~270mm / sec 30 Melt extensibility, or F of 25.0 to 40.0 cN 30 Melt strength and v of 225-260mm / sec 30 It has melt extensibility.

[0093] Further, the polypropylene composition has a melt flow rate MFR measured according to ISO 1133 of 15.0 g / 10 min or less, more preferably in the range of 0.5 to 15.0 g / 10 min, even more preferably in the range of 1.0 to 15.0 g / 10 min, for example in the range of 1.5 to 15.0 g / 10 min. 2 (230°C).

[0094] In a particularly preferred embodiment, the polypropylene composition has a melt flow rate MFR measured according to ISO 1133 of 7.0 g / 10 min or less, preferably in the range of 0.5 to 7.0 g / 10 min, more preferably in the range of 0.5 to 6.5 g / 10 min, even more preferably in the range of 0.5 to 6.0 g / 10 min, even more preferably in the range of 1.0 to 6.0 g / 10 min, for example in the range of 1.5 to 5.0 g / 10 min. 2 (230°C).

[0095] Thus, in one particular embodiment, the polypropylene composition comprises: (a) a melt flow rate MFR of 15.0 g / 10 min or less, more preferably in the range of 0.5 to 15.0 g / 10 min, even more preferably in the range of 1.0 to 15.0 g / 10 min, for example in the range of 1.5 to 15.0 g / 10 min 2 (230℃), (b) F of more than 25.0 to 45.0 cN, preferably more than 25.0 to 42.0 cN, and most preferably more than 25.0 to 40.0 cN 30 Melt strength, and (c) v of more than 210 to 300 mm / sec, more preferably 215 to 290 mm / sec, even more preferably 220 to 270 mm / sec, and most preferably 225 to 260 mm / sec 30 Melt Extensibility has.

[0096] In a particularly preferred variant of this embodiment, the polypropylene composition has a melt flow rate MFR measured according to ISO 1133 of 7.0 g / 10 min or less, preferably in the range of 0.5 to 7.0 g / 10 min, more preferably in the range of 0.5 to 6.5 g / 10 min, even more preferably in the range of 0.5 to 6.0 g / 10 min, even more preferably in the range of 1.0 to 6.0 g / 10 min, for example in the range of 1.5 to 5.0 g / 10 min. 2 (230°C).

[0097] Thus, in a particular embodiment, the polypropylene composition has a melt flow rate MFR in the range of 0.5 to 15.0 g / 10 min. 2 (230℃), F of 25.0 to 45.0cN30 Melt strength and v of 215~290mm / sec 30 Melt extensibility, e.g., melt flow rate (MFR) in the range of 1.0 to 15.0 g / 10 min 2 (230℃), F of 25.0 to 42.0cN 30 Melt strength and v of 215~290mm / sec 30 Melt extensibility, or melt flow rate (MFR) in the range of 1.0 to 15.0 g / 10 min 2 (230℃), F of 25.0 to 40.0cN 30 Melt strength and v of 220~270mm / sec 30 Melt extensibility, or melt flow rate (MFR) in the range of 1.0 to 15.0 g / 10 min 2 (230℃), F of 25.0 to 40.0cN 30 Melt strength and v of 225-260mm / sec 30 It has melt extensibility.

[0098] In a particularly preferred variant of this embodiment, the polypropylene composition has a melt flow rate MFR measured according to ISO 1133 of 7.0 g / 10 min or less, preferably in the range of 0.5 to 7.0 g / 10 min, more preferably in the range of 0.5 to 6.5 g / 10 min, even more preferably in the range of 0.5 to 6.0 g / 10 min, even more preferably in the range of 1.0 to 6.0 g / 10 min, such as in the range of 1.5 to 5.0 g / 10 min, or such as in the range of 1.0 to 5.0 g / 10 min. 2 (230°C).

[0099] Foam Sheet As outlined above, in a first embodiment, the foam sheet comprises a polypropylene composition comprising at least 85 wt.%, for example 85-99.5 wt.%, high melt strength polypropylene (HMS-PP) and 0.5-15 wt.% nucleating agent (NA), the foam sheet having a thickness of less than 0.5 mm or a thickness of 2.0 mm or more.

[0100] In one embodiment, the foam sheet comprises a polypropylene composition comprising at least 85 wt. %, for example 85-99.5 wt. %, of a high melt strength polypropylene (HMS-PP) and 0.5-15 wt. % of a nucleating agent (NA), the foam sheet having a thickness of less than 0.5 mm or a thickness of 2.0 mm or more.

[0101] The foam sheet may be in the form of a thin foam sheet, preferably having a thickness of 0.1 to 0.5 mm, more preferably 0.3 to 0.5 mm, or a thick foam sheet, preferably having a thickness of 2.0 to 10 mm, more preferably 2.0 to 7.0 mm.

[0102] Preferably, the foam sheet has a compressibility of 50 to 350 kg / m 3 , more preferably 75 to 325 kg / m 3 has a density of

[0103] When the foamed sheet has a thickness of less than 0.5 mm, preferably 0.1 mm to 0.5 mm, more preferably 0.3 to 0.5 mm, the foamed sheet preferably has a compressibility of 50 to 350 kg / m 3 , more preferably 75 to 325 kg / m 3 has a density of

[0104] When the foamed sheet has a thickness of 2.0 mm or more, preferably 2.0 to 10 mm, more preferably 2.0 to 7.0 mm, the foamed sheet preferably has a compressibility of 50 to 350 kg / m 3 , more preferably 75 to 325 kg / m 3 has a density of

[0105] The foam sheet is further characterized by its surface roughness, which is typically less than 3.5 μm, preferably less than 2.5 μm, and most preferably less than 1.5 μm.

[0106] In one embodiment, the foamed sheet may be present as an extrusion laminated or extrusion coated sheet. Those skilled in the art are familiar with extrusion laminated or extrusion coated sheets and methods for preparing such sheets, so no further information is necessary.

[0107] The foamed sheet preferably satisfies the following relationship (I): Compressive strength at 25% / (foam density) 2 >0.018kPa / (kg / m 3 ) 2 (I) More preferably, the following relationship (Ia) is satisfied: Compressive strength at 25% / (foam density) 2 >0.019kPa / (kg / m 3 ) 2 (Ia) In the above formula (I) and formula (Ia), Compressive strength at 25% is the compressive strength determined at 25% without a precompression cycle [0] according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m 3 It is expressed in units.

[0108] The foamed sheet preferably satisfies the following relationship (II): Compressive strength at 40% / (foam density) 2 >0.023kPa / (kg / m 3 ) 2 (II) More preferably, the following relationship (IIa) is satisfied: Compressive strength at 40% / (foam density) 2 >0.020kPa / (kg / m 3 ) 2 (IIa) In the above formula (II) and formula (IIa), Compressive strength at 40% is the compressive strength determined at 40% without a precompression cycle [0] according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m 3 It is expressed in units.

[0109] The foam sheet preferably meets, and preferably has, a recovery percentage, determined according to the method specified in the Examples herein, of at least 85%.

[0110] More preferably, the foam sheet satisfies relationships (I) and (II) and has a recovery percentage determined according to the method specified in the Examples herein of at least 85%, and even more preferably, the foam sheet satisfies relationships (Ia) and (IIa) and has a recovery percentage determined according to the method specified in the Examples herein of at least 85%.

[0111] Preferably, the entire polymer portion present in the foam sheet consists of the high melt strength polypropylene (HMS-PP).

[0112] The foam sheet may be a packaging foam, a thermal insulation or flooring underlayment, a sandwich composite having a PP foam core layer, or a foam sheet for use in automobiles.

[0113] The preferred features of the polypropylene composition are also preferred features of the foamed sheet according to the present invention.

[0114] Foam products As outlined above, in a second embodiment, the present invention relates to a foamed material consisting of a polypropylene composition and satisfying the following relationships (I) and (II): Compressive strength at 25% compression / (foam density) 2 >0.018kPa / (kg / m 3 ) 2 (I) In the above formula (I), Compressive strength at 25% is the compressive strength determined at 25% without a precompression cycle [0] according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m 3 It is expressed in units, Compressive strength at 40% / (foam density) 2 >0.020kPa / (kg / m 3 ) 2 (II) In the above formula (II), Compressive strength at 40% is the compressive strength determined at 40% without a precompression cycle [0] according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m 3 It is expressed in units, and further having a recovery rate, determined according to the method specified in the Examples herein, of at least 85%; More preferably, the foam material satisfies the following relationship (Ia) and relationship (IIa): Compressive strength at 25% / (foam density) 2 >0.019kPa / (kg / m 3 ) 2 (Ia) In the above formula (Ia), Compressive strength at 25% is the compressive strength determined at 25% without a precompression cycle [0] according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m 3 It is expressed in units, Compressive strength at 40% / (foam density) 2 >0.020kPa / (kg / m 3 ) 2 (IIa) In the above formula (IIa), Compressive strength at 40% is the compressive strength determined at 40% without a precompression cycle [0] according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m 3 It is expressed in units, having a recovery rate determined according to the method specified in the Examples herein of at least 85%. A foam material is provided.

[0115] The foam material may be in the form of a flat sheet.

[0116] Preferably, the foam has a compressibility of 50 to 350 kg / m 3 , more preferably 75 to 325 kg / m 3 has a density of

[0117] Preferably, the entire polymer portion present in the foam sheet consists of the high melt strength polypropylene (HMS-PP).

[0118] The foamed material is preferably in the form of a foamed sheet, the polypropylene composition comprising, preferably consisting of, at least 85% by weight of high melt strength polypropylene (HMS-PP) and 0.5-15% by weight of a nucleating agent (NA), said foamed sheet having a thickness of less than 0.5 mm or a thickness of 2.0 mm or more. Preferred features of this variant are given above under "Foamed Sheet".

[0119] The foam material may be a packaging foam, a thermal insulation or flooring underlayment, a sandwich composite with a PP foam core layer, or a foam used in automobiles.

[0120] The preferred features of the polypropylene composition are also preferred features of the foamed material according to the present invention.

[0121] use The present invention further relates to the use of a polypropylene composition comprising, preferably consisting of, at least 85% by weight, for example 85-99.5% by weight of high melt strength polypropylene (HMS-PP) and 0.5-15% by weight of a nucleating agent (NA), for producing a foamed material which satisfies the following relationships (I) and / or (II): Compressive strength at 25% / (foam density) 2 >0.018kPa / (kg / m3 ) 2 (I) In the above formula (I), Compressive strength at 25% is the compressive strength determined at 25% without a precompression cycle [0] according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m 3 It is expressed in units, Compressive strength at 40% / (foam density) 2 >0.020kPa / (kg / m 3 ) 2 (I) In the above formula (I), Compressive strength at 40% is the compressive strength determined at 40% without a precompression cycle [0] according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m 3 Expressed in units Regarding use.

[0122] Preferably, the foam material has a recovery, determined according to the method specified in the Examples herein, of at least 85%.

[0123] Preferably the foam is a packaging foam, insulation foam, flooring underlayment, or foam used in automobiles.

[0124] The preferred features of the polypropylene compositions and the foam sheets and foam materials according to the invention are also preferred features of the uses according to the invention. EXAMPLES

[0125] A.Measurement method The following definitions and determination methods of terms apply to the above general description of the invention and the following examples, unless otherwise defined.

[0126] MFR The MFR of polypropylene was determined according to ISO 1133 under a load of 2.16 kg and at a temperature of 230°C.

[0127] Polymer Density Density was measured according to ISO 1183-1-Method A (2004). Sample preparation is performed by compression molding according to ISO 1872-2:2007.

[0128] Comonomer content in polypropylene Comonomer content can be quantitatively determined by methods well known in the art. 13 The chromaticity is determined by quantitative Fourier transform infrared spectroscopy (FTIR) after fundamental assignments calibrated by C nuclear magnetic resonance (NMR) spectroscopy. Thin films are pressed to a thickness of 250 µm and spectra are recorded in transmission mode. Specifically, the ethylene content of the polypropylene-co-ethylene copolymer is 720-722 and 730-733 cm -1 The propylene-1-butene copolymer is determined using the baseline corrected peak area of ​​the quantitative band found at 767 cm -1 Quantitative results are obtained based on reference to film thickness.

[0129] Melting temperature (T m ) and heat of fusion (H f ), crystallization temperature (T c ) and heat of crystallization (H c ): Melting temperature T m and crystallization temperature T c was measured on a TA Instruments Q2000 Differential Scanning Calorimetry (DSC) according to ISO 11357 / 3 on 5-10 mg samples. Crystallization and melting temperatures were obtained in heat / cool / heat cycles at a scan rate of 10 °C / min between 30 °C and 225 °C. The melting and crystallization temperatures were taken as the endothermic and exothermic peaks in the cooling cycle and the second heating cycle, respectively.

[0130] MFR 2(230℃) is measured in accordance with ISO1133 (230℃, 2.16kg load).

[0131] F 30 Melt strength and v 30 Melt Extensibility The tests described herein are in accordance with ISO16790:2005. The strain hardening behavior is determined by the method described in the article "Rheotens-Mastercurves and Drawability of Polymer Melts", MH Wagner, Polymer Engineering and Sense, Vol. 36, pp. 925-935, the contents of which are incorporated by reference. The strain hardening behavior of polymers is analyzed by a Rheotens apparatus (product of Goettfert, Siemensstr. 2, 74711 Buchen, Germany), in which a strand of melt is elongated by being pulled down with a defined acceleration.

[0132] Rheotens experiments simulate industrial spinning and extrusion processes. In principle, the melt is squeezed or extruded through a round die and the resulting strand is drawn off. The stress on the extrudate is recorded as a function of the melt properties and the measured parameters (among others the ratio of the power and the drawing speed, practically a measure of the elongation rate). For the results shown below, the material was extruded using a laboratory extruder HAAKE Polylab system and a gear pump with a cylindrical die (L / D=6.0 / 2.0 mm). The gear pump was pre-adjusted to give a strand extrusion speed of 5 mm / s and the melt temperature was set at 200 °C. The spin line length between the die and the Rheotens wheel was 80 mm. At the start of the experiment, the winding speed of the Rheotens wheel was adjusted to the speed of the extruded polymer strand (zero pulling force). The experiment was then started by slowly increasing the winding speed of the Rheotens wheel until the polymer filament broke. The acceleration of the wheel was kept small enough so that the pulling force was measured in a quasi-steady state. The acceleration of the pulled melt strand is 120 mm / s 2 The Rheotens was operated in conjunction with the PC program "EXTENS", a real-time data acquisition program that displays and stores the measured data of the pull force and the drawdown speed. The end points of the Rheotens curve (force vs. pulley speed) were determined by the F 30 Melt strength and drawability values ​​were reported.

[0133] Gel Content Approximately 2 g of polymer (m p ) was weighed and placed in a weighed metal mesh (m p+m The polymer in the mesh is extracted with boiling xylene in a Soxhlet apparatus for 5 h. The eluent is then replaced with fresh xylene and boiling is continued for another hour. The mesh is then dried and weighed again (m XHU+m ).m XHU+m -m m =m XHU The mass of the hot xylene insoluble matter obtained by the formula (m XHU) to the weight of the polymer (m p ) in relation to the proportion of xylene insolubles m XHU / m p get.

[0134] Polymer Particle Size / Particle Size Distribution A gradient test was performed on the polymer samples. The sieve analysis used a nested column of sieves with wire mesh screens of the following sizes: >20 μm, >32 μm, >63 μm, >100 μm, >125 μm, >160 μm, >200 μm, >250 μm, >315 μm, >400 μm, >500 μm, >710 μm, >1 mm, >1.4 mm, >2 mm, >2.8 mm. The sample was poured onto the top sieve with the largest sieve openings. Each lower sieve in the column has smaller openings than the one above (see sizes shown above). There is a tray at the bottom. The column was placed in a mechanical shaker. The shaker rocks the column. After the shaking was completed, the weight of the material on each sieve was measured. The weight of the sample on each sieve was then divided by the total weight to calculate the percentage retained on each sieve.

[0135] Nucleating agent particle size Median particle size d 50 is calculated from particle size distribution [mass percent] determined by gravitational liquid sedimentation according to ISO 13317-3 using a Sedigraph 5100 (Micromeritics Corporation).

[0136] Foam Density This was measured according to ISO 845 using an analytical semi-micro precision balance from Switzerland PRECISA Gravimetrics AG, Switzerland.

[0137] Foam Cell Size Diameter The cell size diameter of the foams was measured using an optical microscope of a Tawain CBS stereomicroscope. The test methods used are as follows: 1. Cut strips of foam material along the cross direction (CD) and machine direction (MD). 2. Hold the foam material in a flat clamp and use a razor blade to cut a thin slice. 3. Focus the microscope at 100x and adjust the illumination onto the foam material. 4. Take measurements of the length and width of each unique cell in the CD and MD orientations and record the values. 5. Count the number of unique cells measured and record the value. 6. Take cell wall thickness measurements across 3-4 tangents to the entire length of each unique cell in the CD and MD orientations and record the values. 7. Take three full strip thickness measurements starting from the bottom of the first measurement cell group, working to the center of the cell group, and then to the top of the cell group. 8. Take a total length measurement from the lowest full cell to the highest full cell. 9. Move the microscope field so that the bottom of the topmost incomplete cell touches the bottom of the screen. 10. Repeat steps 4-9 for each new unique cell until approximately 0.200 inches (~0.51 cm) to 0.800 inches (~2.0 cm) of the strip has been measured. Be sure to ensure that overall lengths and cell compositions do not overlap. Each overall length measurement after the first is taken from the top of the previous best full cell to the top of the current best full cell.

[0138] Surface roughness of foam This was measured using a Mitutoyo, Japan, portable surface roughness tester, model SJ-310. This surface roughness tester (also known as a surface profilometer) is a contact type surface roughness tester. The roughness determination is fully automated and performed via the included software.

[0139] Compressive strength Compressive strength at 25% and 40% is determined according to ISO 3386-1 at 25% without precompression cycle [0].

[0140] Recovery rate The percent recovery is measured on a test specimen with an area of ​​50x5mm. The test specimen was cut and stacked to a height of 6 layers. The initial thickness of the stacked specimen was measured and then compressed to 50% of its thickness in a Zwick Universal Testing Machine with a preload of 10N at a constant speed of 50mm / min. The test was carried out in a normal laboratory environment set at 23±5°C and 50±5% RH. The load was immediately removed and the specimen was allowed to recover for 5 minutes. The final thickness was then remeasured. The percent recovery was calculated according to the following formula: Recovery rate (%) = (final thickness x 100) / initial thickness

[0141] Open cell content Open cell content was determined according to ASTM D6226.

[0142] Tensile strength and elongation Tensile strength and elongation in the machine direction (MD) and cross direction (CD) were determined according to ISO 1798.

[0143] Maximum bending force, bending strain at maximum force, bending modulus, bending toughness The maximum bending force, bending strain at maximum force, flexural modulus, and flexural toughness in the machine direction (MD) and transverse direction (CD) were determined according to ISO 178.

[0144] Water absorption rate Water absorption (weight gain) was determined according to ASTM D1056.

[0145] thermal stability Thermal stability was determined according to ASTM D3575 suffix S by exposure to 70° C. for 24 hours.

[0146] Invention Example 1 (IE1) The foam sheet was prepared as follows. 1. Daploy™ WB140HMS from Borealis AG (MFR measured according to ISO 1133 of 2.1 g / 10 min) 2(230°C), F determined according to ISO16790:2005 at 36cN 30 Melt strength, measured according to ISO16790:2005 at 230mm / sec 30 The melt extensible (HMS-PP) and talc are dry blended in a weight ratio of 90:10 Daploy™ WB140HMS / talc. 2. The blend from the first step is fed into a first single screw extruder from Pitac Taiwan (screw diameter 90 mm; L / D ratio 26). The extruder is operated at a temperature of 200°C (five heating zones: 150°C; 200°C; 200°C; 200°C) to melt the polymer. 3. 3 wt. % liquid butane (as a blowing agent) based on the total weight of the blend is injected into the last section of the first single screw extruder, thereby obtaining a molten blend. 4. Pass the molten blend through a second single screw extruder from Pitac Taiwan (screw diameter 120 mm; L / D ratio 34), which cools the molten blend to 160° C. at the end of the second single screw extruder. 5. The melt blend of the fourth step is passed through an extrusion die located at the end of the second extruder. Upon exiting the extruder, the melt blend is subjected to a sudden pressure drop to atmospheric pressure, causing the blowing agent in the melt blend to expand, thereby achieving foaming and resulting in a foam structure. The foam structure is then cooled in a cooling drum at a temperature below 100°C, thereby resulting in a foam structure of 95.5 kg / m 3 A foam sheet having a density of 1.0 g / cm and a thickness of 3.0 mm is obtained.

[0147] Invention Example 2 (IE2) The density of the foam sheet in step 5 is 200.6 kg / m 3 The procedure of Example 1 was repeated except for the following.

[0148] Invention Example 3 (IE3) The density of the foam sheet in step 5 is 285.5 kg / m 3 The procedure of Example 1 was repeated except for the following.

[0149] Comparative example 1 (CE1) A polyethylene foam sheet was prepared as follows. 1. LD 1925 AS (LDPE) from Tasnee, Plastron GMS 50 (GMS) from Plastron SAS, and talc are dry blended in a weight ratio of 95:3:2 LDPE / GMS / talc. 2. The blend from the first step is fed into a Pitac Taiwan first single screw extruder (screw diameter 90 mm; L / D ratio 26). The extruder is operated at a temperature of 185°C (5 heating zones: 150°C; 165°C; 175°C; 185°C; 185°C) to melt the polymer. 3. 8 wt % liquid butane (as a blowing agent) based on the total weight of the blend is injected into the last section of the first single screw extruder, thereby obtaining a molten blend. 4. Pass the molten blend through a second single screw extruder from Pitac Taiwan (screw diameter 120 mm; L / D ratio 34), whereby the molten blend is cooled to 100° C. at the end of the second single screw extruder. 5. The melt blend of the fourth step is passed through an extrusion die located at the end of the second extruder. Upon exiting the extruder, the melt blend is subjected to a sudden pressure drop to atmospheric pressure, causing the blowing agent in the melt blend to expand, thereby achieving foaming and resulting in a foam structure. The foam structure is then cooled in a cooling drum at a temperature below 100°C, thereby resulting in a foam structure of 30.6 kg / m 3 A foam sheet is obtained having a density of 1.0 and a thickness of 13 mm.

[0150] Comparative Example 2 (CE2) The sheet thickness is 3 mm and the density of the foam material is 14.4 kg / m 3 The procedure of Comparative Example 1 was repeated, except that:

[0151] Comparative Example 3 (CE3) A polystyrene foam sheet was prepared as follows. 1. Ineos' Styrolution PS 168N / L (GPPS) and talc are dry blended in a weight ratio of 98:2 Styrolution PS 168N / L / talc. 2. The blend from the first step is fed into a Pitac Taiwan first single screw extruder (screw diameter 90 mm; L / D ratio 26). The extruder is operated at a temperature of 200°C (5 heating zones: 150°C; 200°C; 200°C; 200°C) to melt the polymer. 3. 8 wt % liquid butane (as a blowing agent) based on the total weight of the blend is injected into the last section of the first single screw extruder, thereby obtaining a molten blend. 4. Pass the molten blend through a second single screw extruder from Pitac Taiwan (screw diameter 120 mm; L / D ratio 34), which cools the molten blend to 110° C. at the end of the second single screw extruder. 5. The melt blend of the fourth step is passed through an extrusion die located at the end of the second extruder. Upon exiting the extruder, the melt blend is subjected to a sudden pressure drop to atmospheric pressure, causing the blowing agent in the melt blend to expand, thereby achieving foaming and resulting in a foam structure. The foam structure is then cooled in a cooling drum at a temperature below 100°C, thereby producing a foam structure of 52.6 kg / m 3 A foam sheet is obtained having a density of 1000 and a thickness of 3 mm.

[0152] Comparative Example 4 (CE4) The sheet thickness is 5 mm and the density of the foam material is 72.2 kg / m 3 The procedure of Comparative Example 3 was repeated, except that:

[0153] The results for invention examples IE1, IE2 and IE3 and comparative examples CE1, CE2, CE3 and CE4 are shown in Table 1 below.

[0154] [Table 1]

[0155] As can be seen from Table 1 above, the HMS-PP foam samples of the present invention show excellent load-bearing capacity comparable to that of PS foam, as represented by comparable tensile and compressive strengths. Moreover, all samples have a density typically achieved for the corresponding type of foam prepared. However, PS foam has a low recovery rate, whereas the HMS-PP foam of the present invention shows excellent recovery rate, which is comparable to that of PE foam. However, PE foam does not have the load-bearing capacity (measured as compressive or tensile strength) of the foam of the present invention (or PS foam). Thus, the HMS-PP foam of the present invention has a unique combination of properties.

Claims

1. A foamed sheet made of a polypropylene composition comprising 87.5-92.5 wt. % of a high melt strength polypropylene (HMS-PP) and 7.5-12.5 wt. % of a nucleating agent (NA), the foamed sheet having a thickness of 2.0-7.0 mm and a compressibility of 75-325 kg / m ３ A foam sheet having a foam density of

2. The following relationship (I) is satisfied: Compressive strength at 25% / (foam density) ２ >0.018kPa / (kg / m ３ ) ２ (I) In the relationship (I), Compressive strength at 25% is the compressive strength determined at 25% without a pre-compression cycle according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m ３ Expressed in units The foamed sheet according to claim 1 .

3. The following relationship (II) is satisfied: Compressive strength at 40% / (foam density) ２ >0.020kPa / (kg / m ３ ) ２ (II) In the relationship (II), Compressive strength at 40% is the compressive strength determined at 40% without a pre-compression cycle according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m ３ Expressed in units The foamed sheet according to claim 1 or 2.

4. 4. The foamed sheet according to claim 1, wherein the recovery rate defined by the following relationship (III) is 85% or more, the initial thickness is the thickness of an initial sample, and the final thickness is the thickness of a final sample obtained after applying a preload of 10 N to the initial sample at a constant speed of 50 mm / min, removing the preload, and allowing the sample to recover for 5 minutes. Recovery rate (%) = (final thickness (mm) / initial thickness (mm)) x 100 (III)

5. The foamed sheet according to any one of claims 1 to 4, wherein the nucleating agent (NA) is talc.

6. The high melt strength polypropylene (HMS-PP) has a F of greater than 25.0 cN. ３０ Melt strength and / or v of greater than 205 mm / sec ３０ The F has melt extensibility. ３０ Melt strength and the v ３０ 6. The foamed sheet of claim 1, wherein the melt extensibility is determined according to ISO 16790:2005.

7. The foamed sheet according to any one of claims 1 to 6, wherein the entire polymer portion present in the foamed sheet is made of the high melt strength polypropylene (HMS-PP).

8. 8. The foam sheet of any one of claims 1 to 7 which is a packaging foam, insulation, flooring underlay, or a sandwich composite having a PP foam core layer.

9. A foamed material comprising a polypropylene composition and satisfying the following relationships (I) and (II): the polypropylene composition comprises 87.5-92.5 wt.% high melt strength polypropylene (HMS-PP) and 7.5-12.5 wt.% nucleating agent (NA); The foam material has a thickness of 2.0 to 7.0 mm and a weight per unit area of ​​75 to 325 kg / m ３ and having a foam density of Compressive strength at 25% compression / (foam density) ２ >0.018kPa / (kg / m ３ ) ２ (I) In the relationship (I), Compressive strength at 25% is the compressive strength determined at 25% without a pre-compression cycle according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m ３ It is expressed in units, Compressive strength at 40% / (foam density) ２ >0.020kPa / (kg / m ３ ) ２ (II) In the relationship (II), Compressive strength at 40% is the compressive strength determined at 40% without a pre-compression cycle according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m ３ It is expressed in units, A foam material having a recovery rate defined by the following relationship (III) of 85% or more, wherein the initial thickness below is the thickness of an initial sample, and the final thickness below is the thickness of a final sample obtained after applying a preload of 10 N to the initial sample at a constant speed of 50 mm / min, removing the preload, and allowing the sample to recover for 5 minutes. Recovery rate (%) = (final thickness (mm) / initial thickness (mm)) x 100 (III)

10. 10. The foam material according to claim 9, wherein the nucleating agent (NA) is talc.

11. The high melt strength polypropylene (HMS-PP) has a F of greater than 25.0 cN. ３０ Melt strength and / or v of greater than 205 mm / sec ３０ The F has melt extensibility. ３０ Melt strength and the v ３０ 11. The foam material of claim 9 or claim 10, wherein the melt extensibility is determined according to ISO 16790:2005.

12. The foamed material according to any one of claims 9 to 10, wherein the entire polymer portion present in the foamed material consists of the high melt strength polypropylene (HMS-PP).

13. 13. The foam material of any one of claims 9 to 12, which is a packaging foam, insulation or flooring underlay, a sandwich composite having a PP foam core layer.

14. 2.0 to 7.0 mm thickness and 75 to 325 kg / m ３ % of a polypropylene composition comprising 87.5-92.5% high melt strength polypropylene (HMS-PP) and 7.5-12.5 wt. % of a nucleating agent (NA) for producing a foamed material having a foam density of 0.01 to 0.05% and satisfying the following relationships (I) and / or (II): Compressive strength at 25% / (foam density) ２ >0.018kPa / (kg / m ３ ) ２ (I) In the relationship (I), Compressive strength at 25% is the compressive strength determined at 25% without a pre-compression cycle according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m ３ It is expressed in units, Compressive strength at 40% / (foam density) ２ >0.020kPa / (kg / m ３ ) ２ (II) In the relationship (II), Compressive strength at 40% is the compressive strength determined at 40% without a pre-compression cycle according to ISO 3386-1, expressed in kPa; Foam density is the density of the foam determined according to ISO 845, kg / m ３ Expressed in units use.

15. The foamed material has a recovery rate of 85% or more as defined by the following relationship (III), the initial thickness below is the thickness of an initial sample, and the final thickness below is the thickness of a final sample obtained after applying a preload of 10 N to the initial sample at a constant speed of 50 mm / min, removing the preload and allowing the sample to recover for 5 minutes. Recovery rate (%) = (final thickness (mm) / initial thickness (mm)) x 100 (III) 16. The use of claim 14 or claim 15, wherein the foam material is a packaging foam, insulation material, flooring underlay, or a foam for use in automobiles.

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