HMS PP foam board with good compressive strength and recovery rate

Abstract

The present invention relates to a foamed sheet consisting 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) wherein the foamed sheet has a thickness of less than 0.5 mm or above 2.0 mm. The invention also relates to a foamed material consisting 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), and to the use of a polypropylene composition for the production of a foamed material. The invention also relates to a foamed material consisting 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).

Description

[0001] This application is a divisional application of the invention patent application filed on June 24, 2021, with application number 202180043386.2 (international application number PCT / EP2021 / 067331) entitled "HMS PP foam board with good compressive strength and recovery rate". Technical Field

[0002] This invention relates to a foamed board made of a polypropylene composition comprising at least 85% by weight, for example 85-99.5% by weight, high melt strength polypropylene (HMS-PP) and 0.5-15% by weight, a nucleating agent (NA), wherein the thickness of the foamed board is less than 0.5 mm or greater than 2.0 mm. The invention also relates to a foamed material made of a polypropylene composition, and the application of this polypropylene composition in the production of foamed materials, the polypropylene composition comprising at least 85% by weight, for example 85-99.5% by weight, high melt strength polypropylene (HMS-PP) and 0.5-15% by weight, a nucleating agent (NA). Background Technology

[0003] Foams of varying thicknesses are used in a wide variety of applications. For example, thick foams are commonly used in packaging and various applications such as automotive, construction, and building. When used in packaging, foam protects goods during transport, while in construction and building applications, foam is often used as flooring lining and filler material. An exemplary application of thin foam is speaker diaphragms. The foams used in these applications require sufficient load-bearing capacity (measured by compressive or tensile strength) and good recovery rate after the load is removed (measured by average recovery rate after load). Polystyrene and LDPE-based foams are commonly used in these applications. PS foam has excellent load-bearing capacity, but its recovery rate is poor. On the other hand, LDPE-based foam has good recovery rate, but its load-bearing capacity is insufficient. Therefore, the objective of this invention is to develop a foam solution with good load-bearing capacity and excellent recovery rate. Summary of the Invention

[0004] Therefore, in a first embodiment of the present invention, a foamed board made of a polypropylene composition is provided, the polypropylene composition preferably containing at least 85% by weight, for example 85 to 99.5% by weight of high melt strength polypropylene (HMS-PP) and 0.5 to 15% by weight of nucleating agent (NA), wherein the thickness of the foamed board is less than 0.5 mm or more than 2.0 mm.

[0005] In a second embodiment, the present invention provides a foaming material composed of a polypropylene composition that satisfies the following relationships (I) and (II).

[0006] Compressive strength at 25% compression / (foam density)2 > 0.018 kPa / (kg / m 3 ) 2 (I)

[0007] The compressive strength at 25% compression is the compressive strength measured according to ISO 3386-1 without pre-compression cycles [0] at 25% compression, in kPa.

[0008] Foam density is the density of foam as determined according to ISO 845, and the unit is kg / m³. 3 ;

[0009] Compressive strength at 40% compression / (foam density) 2 > 0.020 kPa / (kg / m 3 ) 2 (II)

[0010] The compressive strength at 40% compression is the compressive strength measured at 40% compression without pre-compression cycle [0] according to ISO 3386-1, and the unit is kPa.

[0011] Foam density is the density of foam as determined according to ISO 845, and the unit is kg / m³. 3 ,

[0012] The foamed material also has a recovery rate of at least 85%, as determined by the method described in the embodiments of this specification.

[0013] The foamed boards and foamed materials of this invention are available in various thicknesses. For example, thin foamed boards and foamed materials can be used in a variety of applications, such as speaker diaphragms which typically require a thickness of less than 0.5 mm, while thick foamed boards and foamed materials are typically used in flooring substrates and insulation materials, automotive, and other applications that typically require a thickness of 2.0 mm or more. The foamed boards and foamed materials of this invention surprisingly exhibit good compressibility and good resilience, thereby overcoming the problems of polystyrene and LDPE-based foams as described above.

[0014] The foamed board of the first embodiment preferably satisfies the following relationship (I):

[0015] Compressive strength at 25% compression / (foam density) 2 > 0.018 kPa / (kg / m 3 ) 2 (I)

[0016] The compressive strength at 25% compression is the compressive strength measured at 25% compression without pre-compression cycles according to ISO 3386-1 [0], and the unit is kPa.

[0017] Foam density is the density of foam as determined according to ISO 845, and the unit is kg / m³. 3 .

[0018] The foamed board of the first embodiment preferably satisfies the following relationship (II):

[0019] Compressive strength at 40% compression / (foam density) 2 > 0.020 kPa / (kg / m 3 ) 2 (II)

[0020] The compressive strength at 40% compression is the compressive strength measured at 40% compression without pre-compression cycles according to ISO 3386-1 [0], and the unit is kPa.

[0021] Foam density is the density of foam as determined according to ISO 845, and the unit is kg / m³. 3 ,

[0022] The foamed board also exhibits a recovery rate of at least 85%, as determined by the methods described in the embodiments of this specification.

[0023] More preferably, the foamed board of the first embodiment satisfies relations (I) and (II) and has a recovery rate of at least 85% as measured by the method described in the embodiments of this specification.

[0024] The foaming material in the second embodiment is preferably in the form of a foamed board, wherein the polypropylene composition preferably contains at least 85% by weight, for example 85 to 99.5% by weight of high melt strength polypropylene (HMS-PP) and 0.5 to 15% by weight of nucleating agent (NA), and the thickness of the foamed board is less than 0.5 mm or more than 2.0 mm.

[0025] The following describes all embodiments of the invention, including various preferred variations, unless otherwise expressly stated to the contrary.

[0026] High melt strength polypropylene (HMS-PP)

[0027] High melt strength polypropylene is branched; therefore, unlike linear polypropylene, the main chain of polypropylene encompasses the side chains, while unbranched polypropylene (such as linear polypropylene) does not. The side chains have a significant impact on the rheological properties of polypropylene. Therefore, linear polypropylene and high melt strength polypropylene can be clearly distinguished by their flow behavior under stress.

[0028] Branching can typically be achieved by using specific catalysts, i.e., specific unit-site catalysts, or through chemical modification. For methods of preparing branched polypropylene using specific catalysts, see EP 1 892 264. For obtaining branched polypropylene through chemical modification, see EP 0 8798 30 A1. In this case, branched polypropylene is also referred to as high melt strength polypropylene. The high melt strength polypropylene (HMS-PP) of this invention is obtained by chemically modified polypropylene (PP) as described in detail below. HMS-PP is available from Borealis AG under the trade name Daploy™.

[0029] Therefore, high melt strength polypropylene (HMS-PP) has an F value greater than 25.0 cN. 30 Melt strength and v greater than 205 mm / s 30 The melt elongation is preferably 25.0~50.0 cN of F. 30 Melt strength and v = 205~300 mm / s 30 Melt elongation is used to provide polypropylene compositions with good shear thinning properties. F 30 Melt strength and v 30 Melt elongation was measured according to ISO 16790:2005.

[0030] In a preferred embodiment, high melt strength polypropylene (HMS-PP) has

[0031] (a) F 30 The melt strength is 25.0~45.0 cN, preferably 25.0~42.0 cN, and most preferably 25.0~40.0 cN; and

[0032] (b)v 30 The melt elongation is 210~300 mm / s, more preferably 215~290 mm / s, even more preferably 220~270 mm / s, and most preferably 225~260 mm / s.

[0033] In a particularly preferred embodiment, high melt strength polypropylene (HMS-PP) has an FN of 25.0~45.0 cN. 30 Melt strength and v = 210~300 mm / s 30 Melt elongation, for example, F30 The melt strength is 25.0~42.0 cN and v. 30 Melt elongation is 215~290 mm / s, or F 30 The melt strength is 25.0~40.0 cN and v. 30 Melt elongation is 220~270 mm / s, or F 30 The melt strength is 25.0~40.0 cN and v. 30 The melt elongation is 220~260 mm / s.

[0034] Furthermore, preferably, the high melt strength polypropylene (HMS-PP) has a melt flow rate MFR2 (230°C) (measured according to ISO 1133) of not more than 15.0 g / 10 min, more preferably in the range of 0.5 to 15.0 g / 10 min, and particularly preferably 1.0 to 15.0 g / 10 min, such as 1.5 to 15.0 g / 10 min.

[0035] In a particularly preferred embodiment, the melt flow rate MFR2 (230°C) of the high melt strength polypropylene (HMS-PP) (measured according to ISO 1133) is not more than 7.0 g / 10 min, preferably 0.5 to 7.0 g / 10 min, more preferably 0.5 to 6.5 g / 10 min, even more preferably 0.5 to 6.0 g / 10 min, and especially preferably 1.0 to 6.0 g / 10 min, such as 1.5 to 5.0 g / 10 min.

[0036] Therefore, in one specific embodiment, high melt strength polypropylene (HMS-PP) has

[0037] (a) The melt flow rate MFR2 (230°C) does not exceed 15.0 g / 10 min, more preferably in the range of 0.5 to 15.0 g / 10 min, particularly preferably 1.0 to 15.0 g / 10 min, such as 1.5 to 15.0 g / 10 min; and

[0038] (b) F 30 The melt strength is greater than 25.0 cN, preferably 25.0~50.0 cN, more preferably 25.0~45.0 cN, even more preferably 25.0~42.0 cN, and most preferably 25.0~40.0 cN; and

[0039] (c)v 30 The melt elongation is greater than 205 mm / s, preferably greater than 205 mm / s to 300 mm / s, more preferably 210 to 300 mm / s, even more preferably 215 to 290 mm / s, further preferably 220 to 270 mm / s, and most preferably 225 to 260 mm / s.

[0040] In a particularly preferred embodiment, high melt strength polypropylene (HMS-PP) has

[0041] (a) The melt flow rate MFR2 (230°C) does not exceed 7.0 g / 10 min, 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, particularly preferably in the range of 1.0 to 6.0 g / 10 min, such as 1.5 to 5.0 g / 10 min; and

[0042] (b) F 30 The melt strength is greater than 25.0 cN, preferably greater than 25.0 cN to 50.0 cN, more preferably greater than 25.0 cN to 45.0 cN, even more preferably greater than 25.0 cN to 42.0 cN, and most preferably greater than 25.0 cN to 40.0 cN; and

[0043] (c)v 30 The melt elongation is greater than 205 mm / s, preferably greater than 205 mm / s to 300 mm / s, more preferably 210 to 300 mm / s, even more preferably 215 to 290 mm / s, further preferably 220 to 270 mm / s, and most preferably 225 to 260 mm / s.

[0044] Therefore, in one specific embodiment, the melt flow rate MFR2 (230°C) of the high melt strength polypropylene (HMS-PP) is in the range of 0.5~15.0 g / 10 min, F 30 Melt strength is greater than 25.0 cN~45.0 cN, v 30 Melt elongation is 210~300 mm / s, and if the melt flow rate MFR2 (230°C) is in the range of 1.0~15.0 g / 10 min, F 30 Melt strength is 25.0~42.0 cN, v 30 Melt elongation is in the range of 215~290 mm / s, or melt flow rate MFR2 (230°C) is in the range of 1.0~15.0 g / 10 min, F 30 Melt strength is greater than 25.0 cN to 40.0 cN, v 30 Melt elongation is 220~270 mm / s, or melt flow rate MFR2 (230°C) is in the range of 1.5~15.0 g / 10 min, F 30 Melt strength is greater than 25.0 cN to 40.0 cN, v 30 The melt elongation is 225~260 mm / s.

[0045] Therefore, in another specific embodiment, the melt flow rate MFR2 (230°C) of the high melt strength polypropylene (HMS-PP) is in the range of 0.5~7.0 g / 10 min, F 30 Melt strength is greater than 25.0 cN~45.0 cN, v 30 Melt elongation is 210~300 mm / s, and if the melt flow rate MFR2 (230°C) is in the range of 1.0~15.0 g / 10 min, F 30 Melt strength is greater than 25.0 cN to 42.0 cN, v 30 Melt elongation is in the range of 215~290 mm / s, or melt flow rate MFR2 (230°C) is in the range of 1.0~6.0 g / 10 min, F 30 Melt strength is greater than 25.0 cN to 40.0 cN, v 30 Melt elongation is 220~270 mm / s, or melt flow rate MFR2 (230°C) is in the range of 1.5~5.0 g / 10 min, F 30 Melt strength is greater than 25.0 cN to 40.0 cN, v 30 Melt elongation is 225~260 mm / s.

[0046] 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.

[0047] In addition, high melt strength polypropylene (HMS-PP) can be either a high melt strength random propylene copolymer (R-HMS-PP) or a high melt strength propylene homopolymer (H-HMS-PP), with the latter being preferred.

[0048] According to the intent of the present invention, the term "propylene homopolymer" refers to a polypropylene that is substantially, i.e., at least 97 mol%, preferably at least 98 mol%, more preferably at least 99 mol%, and most preferably at least 99.8 mol% composed of propylene units. In a preferred embodiment, only propylene units are detectable in the propylene homopolymer.

[0049] If high melt strength polypropylene (HMS-PP) is a high melt strength random propylene copolymer (R-HMS-PP), it contains monomers that can be copolymerized with propylene, such as ethylene and / or C4-C. 12 Comonomers such as α-olefins, especially ethylene and / or C4-C 10α-Olefins, such as 1-butene and / or 1-hexene. Preferred high melt strength random propylene copolymers (R-HMS-PP) comprise, in particular, comonomers selected from ethylene, 1-butene, and 1-hexene that can be copolymerized with propylene. More specifically, the high melt strength random propylene copolymers (R-HMS-PP) comprise, in addition to propylene, units derived from ethylene and / or 1-butene. In a preferred embodiment, the high melt strength random propylene copolymers (R-HMS-PP) consist only of ethylene-derived units and propylene. The content of comonomers in the high melt strength random propylene copolymers (R-HMS-PP) is preferably in the range of greater than 0.2 mol% to 10.0 mol%, more preferably in the range of greater than 0.5 mol% to 7.0 mol%.

[0050] In this regard, it should be mentioned that high melt strength polypropylene (HMS-PP), which is a high melt strength homopolymer of propylene (H-HMS-PP) or a high melt strength random propylene copolymer of propylene (R-HMS-PP), may contain additional unsaturated monomers different from the comonomers defined in the high melt strength random propylene copolymer of propylene (R-HMS-PP). In other words, high melt strength propylene homopolymer (H-HMS-PP) or high melt strength random propylene copolymer of propylene (R-HMS-PP) may contain unsaturated monomers, such as difunctional unsaturated monomers and / or polyfunctional unsaturated low molecular weight polymers as defined in detail below, which are different from propylene, ethylene and other C4-C... 12 α-olefins. Therefore, the definition of homopolymers and copolymers of high melt strength polypropylene (HMS-PP) actually refers to unmodified polypropylene, that is, a type of polypropylene (PP), preferably linear polypropylene (l-PP), used to obtain high melt strength polypropylene (HMS-PP) through chemical modification, as detailed below.

[0051] Therefore, in a preferred embodiment, the high melt strength polypropylene (HMS-PP) comprises:

[0052] (a) If it is a high melt strength propylene homopolymer (H-HMS-PP), its unit originates from

[0053] (i) Propylene and

[0054] (ii) Difunctional unsaturated monomers and / or polyfunctional unsaturated low molecular weight polymers,

[0055] or

[0056] (b) If it is a high melt strength random propylene copolymer (R-HMS-PP), its units are derived from

[0057] (i) Propylene

[0058] (ii) Ethylene and / or C4-C 12 α-olefins, such as 1-butene and / or 1-hexene, preferably ethylene, and

[0059] (iii) Difunctional unsaturated monomers and / or polyfunctional unsaturated low molecular weight polymers,

[0060] The terms "bifunctionally unsaturated" or "multifunctionally unsaturated" as used above preferably refer to compounds containing two or more non-aromatic double bonds, such as divinylbenzene, cyclopentadiene, or polybutadiene. Using only such bifunctional or multifunctional unsaturated compounds, polymerization is preferably achievable with the assistance of free radicals (see below). The unsaturated sites in bifunctional or multifunctional unsaturated compounds are not actually "unsaturated" in their chemical bonding state because each double bond is used as a covalent bond with the polymer chain of unmodified polypropylene, i.e., polypropylene (PP), preferably linear polypropylene (l-PP).

[0061] The reaction of one and / or more unsaturated monomers with unmodified polypropylene, i.e., polypropylene (PP), preferably linear polypropylene (l-PP), to synthesize difunctional unsaturated monomers and / or polyfunctional unsaturated low molecular weight polymers (preferably having a number average molecular weight (Mn) ≤ 10000 g / mol) is carried out in the presence of a thermal free radical forming agent (e.g., a decomposition free radical forming agent, such as a thermally decomposable peroxide).

[0062] Difunctional unsaturated monomers can be:

[0063] (1) Divinyl compounds, such as divinylaniline, m-divinylbenzene, p-divinylbenzene, divinylpentane and divinylpropane;

[0064] (2) Allyl compounds, such as allyl acrylate, allyl methacrylate, allyl methyl maleate and allyl vinyl ether;

[0065] (3) Dienes, such as 1,3-butadiene, chlorobutene, cyclohexadiene, cyclopentadiene, 2,3-dimethylbutadiene, heptaadiene, hexadiene, isoprene and 1,4-pentadiene;

[0066] (4) A mixture of aromatic and / or aliphatic bis(maleimide) bis(citronimide) and these unsaturated monomers.

[0067] The particularly preferred difunctional unsaturated monomers are 1,3-butadiene, isoprene, dimethylbutadiene, and divinylbenzene.

[0068] The multifunctional unsaturated low molecular weight polymer preferably has a number average molecular weight (Mn) ≤ 10000 g / mol and can be synthesized from one or more unsaturated monomers.

[0069] Examples of such low molecular weight polymers include:

[0070] (1) Polybutadiene, especially polymers with different microstructures on the polymer chain, namely, 1,4-cis, 1,4-trans and 1,2-(vinyl) with the 1,2-(vinyl) configuration being the most common.

[0071] (2) A copolymer of butadiene and styrene, with 1,2-(vinyl) on its polymer chain.

[0072] Preferred low molecular weight polymers are polybutadiene, especially polybutadiene with a 1,2-(vinyl) configuration containing more than 50.0% by weight.

[0073] High melt strength polypropylene (HMS-PP) may contain one or more difunctional unsaturated monomers and / or polyfunctional unsaturated low molecular weight polymers. In high melt strength polypropylene (HMS-PP), the total content of the difunctional unsaturated monomer and the polyfunctional unsaturated low molecular weight polymer is particularly preferably 0.01 to 10.0% by weight of the high melt strength polypropylene (HMS-PP).

[0074] In a preferred embodiment, the high melt strength polypropylene (HMS-PP) is free of additive (A). Therefore, if the polypropylene composition of the present invention contains additive (A), these additives (A) are not introduced into the polypropylene composition during the manufacture of high melt strength polypropylene (HMS-PP).

[0075] Further preferred high melt strength polypropylene (HMS-PP) has a low gel content, typically less than 1.00% by weight, preferably less than 0.80% by weight, and more preferably less than 0.50% by weight.

[0076] As described above, high melt strength polypropylene (HMS-PP) can be obtained by treating polypropylene (PP) (preferably linear polypropylene (l-PP)) with a thermally decomposable free radical forming agent. However, in this case, there is a higher risk that the polypropylene (PP) (preferably linear polypropylene (l-PP)) will degrade, which is harmful. Therefore, it is preferable to chemically modify the polypropylene (PP) by additionally using difunctional unsaturated monomers and / or polyfunctional unsaturated low molecular weight polymers as chemically bonded bridging units. A suitable method for obtaining high melt strength polypropylene (HMS-PP) is disclosed, for example, in EP 0 787 750, EP 0 879830 A1 and EP 0 890 612 A2. The contents of all these documents are incorporated herein by reference. Therefore, the amount of thermally decomposable free radical forming agent (preferably peroxide) is preferably in the range of 0.05 to 3.00% by weight, based on the amount of polypropylene (PP). Typically, a thermally decomposable radical forming agent and a difunctional unsaturated monomer and / or a polyfunctional unsaturated low molecular weight polymer are added together to polypropylene (PP) (preferably linear polypropylene (l-PP)). However, it is also possible, but not preferred, to first add the difunctional unsaturated monomer and / or the polyfunctional unsaturated low molecular weight polymer to polypropylene (PP) (preferably linear polypropylene (l-PP)) and then add the thermally decomposable radical forming agent to polypropylene (PP), or conversely, to first add the thermally decomposable radical forming agent to polypropylene (PP) (preferably linear polypropylene (l-PP)) and then add the difunctional unsaturated monomer and / or the polyfunctional unsaturated low molecular weight polymer.

[0077] For information on difunctional unsaturated monomers and / or polyfunctional unsaturated low molecular weight polymers used in the manufacture of high melt strength polypropylene (HMS-PP), refer to the previous section.

[0078] As described above, it is preferable to use difunctional unsaturated monomers and / or polyfunctional unsaturated low molecular weight polymers in the presence of thermally decomposable free radical forming agents.

[0079] Peroxides are preferred thermally decomposable free radical forming agents. More preferred thermally decomposable free radical forming agents are selected from acyl peroxides, alkyl peroxides, hydrogen peroxide, peroxy esters, and peroxy carbonates.

[0080] The following peroxides are particularly preferred:

[0081] Acyl peroxides: benzoyl peroxide, 4-chlorobenzoyl peroxide, 3-methoxybenzoyl peroxide and / or methylbenzoyl peroxide.

[0082] Alkyl peroxides: allyl tert-butyl peroxide, 2,2-bis(tert-butyl peroxide butane), 1,1-bis(tert-butyl peroxide)-3,3,5-trimethylcyclohexane, 4,4-bis(tert-butyl peroxide)valerate n-butyl ester, diisopropylaminomethyl tert-amyl peroxide, dimethylaminomethyl tert-amyl peroxide, diethylaminomethyl tert-amyl peroxide, dimethylaminomethyl tert-butyl peroxide, 1,1-di-(tert-amyl peroxide)cyclohexane, tert-amyl peroxide, tert-butyl isopropylbenzene peroxide, tert-butyl peroxide and / or 1-hydroxybutyl n-butyl peroxide.

[0083] Peroxyesters and peroxycarbonates: Butyl peracetate, cumyl peracetate, cumyl perpropionate, cyclohexyl peracetate, di-tert-butyl peradiate, di-tert-butyl perazelate, di-tert-butyl perglutarate, di-tert-butyl perphthalate, di-tert-butyl persediment, 4-nitropentyl perpropionate, 1-phenylethyl perbenzoate, phenethyl nitrobenzoate, di-tert-butylbicyclo(2,2,l)heptane percarboxylic acid, methyl perbutyrate-tert-butyl perbutate, tert-butylcyclobutane percarboxylic acid, tert-butylcyclohexyl percarboxylic acid, tert-butylcyclopentyl percarboxylic acid, tert-butylcyclopropyl percarboxylic acid, dimethyl percinnamic acid-tert-butyl, 2-(2,2-diphenylvinyl)peracetate tert-butyl benzoate, tert-butyl perbenzoate, tert-butyl perbenzoate, tert-butyl carboxycyclohexane, tert-butyl pernaphthalate, tert-butyl peroxyisopropyl carbonate, tert-butyl pertoluate, tert-butyl pertoluate, tert-butyl 1-phenylcyclopropyl percarboxylate, tert-butyl 2-propylperpenten-2-olate, tert-butyl 1-methylcyclopropyl percarboxylate, tert-butyl 4-nitrophenylperacetic acid, tert-butyl nitrophenylperoxycarbamate, tert-butyl persuccinimide percarboxylate, tert-butyl percrotonate, tert-butyl permaleate, tert-butyl permethacrylate, tert-butyl peroctanoate, tert-butyl perisopropyl carbonate, tert-butyl perisobutyrate, tert-butyl peracrylate, and / or tert-butyl perpropionate.

[0084] Mixtures of these free radical forming agents have also been envisioned.

[0085] The suitable HMS-PP is WB140HMS™, commercially available from Borealis AG.

[0086] Polypropylene (PP)

[0087] As previously mentioned, high melt strength polypropylene (HMS-PP) is a modified polypropylene obtained by reacting polypropylene (PP) with a thermally decomposable free radical forming agent, and optionally with difunctional unsaturated monomers and / or polyfunctional unsaturated low molecular weight polymers. The polypropylene (PP) is preferably linear polypropylene (l-PP).

[0088] Preferably, the melt flow rate MFR2 (230°C) of the polypropylene (PP) (preferably linear polypropylene (l-PP)) as measured according to ISO 1133 is in the range of 0.1 to 45.0 g / 10 min, such as 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 especially preferably 0.1 to 25.0 g / 10 min.

[0089] The difference between high melt strength polypropylene (HMS-PP) and the polypropylene (PP) used to manufacture it lies in the fact that the backbone (main chain) of HMS-PP includes side chains, while the starting material, i.e., polypropylene (PP) including the preferred linear polypropylene (l-PP), does not include or substantially does not include side chains. Side chains have a significant impact on the rheological properties of polypropylene. Therefore, the flow behavior under stress can clearly distinguish between the starting material, i.e., polypropylene (PP), and the resulting high melt strength polypropylene (HMS-PP).

[0090] Furthermore, as previously mentioned, the polypropylene (PP) is preferably linear polypropylene (l-PP). The same applies to the polypropylene (PP') discussed in detail below, which in the preferred embodiment is also linear polypropylene (l-PP'). Therefore, in this invention, the term "linear polypropylene" refers to linear polypropylene with no branching structure or substantially no branching structure. Due to the lack of branching, linear polypropylene, i.e., linear polypropylene (l-PP) and linear polypropylene (l-PP'), are preferably made with low v 30 Melt elongation and / or low F 30 The melt strength was characterized.

[0091] Therefore, preferably, linear polypropylene (l-PP) has the following characteristics:

[0092] (a) F 30 The melt strength is less than 30.0 cN, preferably less than 27.0 cN, more preferably between 1.0 cN and less than 30.0 cN, even more preferably between 1.5 cN and less than 30.0 cN, particularly preferably between 2.0 cN and less than 27.0 cN, especially preferably between 2.5 cN and less than 27.0 cN; and

[0093] (b)v 30 The melt elongation is less than 220 mm / s, preferably less than 210 mm / s, more preferably between 80 and 200 mm / s, and most preferably between 100 and 200 mm / s.

[0094] In other words, preferably, the F of linear polypropylene (l-PP) 30Melt strength less than 30.0 cN and v 30 Melt elongation less than 220 mm / s, preferably F 30 Melt strength less than 27.0 cN and v 30 Melt elongation less than 210 mm / s, preferably F 30 Melt strength is between 1.0 cN and less than 30.0 cN and v 30 The melt elongation is between 80 and 200 mm / s, with F being further preferred. 30 Melt strength is between 1.5 cN and less than 30.0 cN and v 30 Melt elongation of 100~200 mm / s is preferred, especially F. 30 Melt strength is between 2.0 cN and less than 27.0 cN and v 30 Melt elongation is 100~200 mm / s, such as F 30 Melt strength is between 2.5 cN and less than 27.0 cN.

[0095] Therefore, in one specific embodiment, linear polypropylene (l-PP) has:

[0096] (a) The melt flow rate MFR2 (230°C), measured according to ISO 1133, is in the range of 0.1 to 45.0 g / 10 min, such as 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 particularly preferably 0.1 to 25.0 g / 10 min; and

[0097] (b) F 30 The melt strength is less than 30.0 cN, preferably less than 27.0 cN, more preferably between 1.0 cN and less than 30.0 cN, further preferably between 1.5 cN and less than 30.0 cN, particularly preferably between 2.0 cN and less than 27.0 cN, and most preferably between 2.5 cN and less than 27.0 cN; and

[0098] (c)v 30 The melt elongation is less than 220 mm / s, preferably less than 210 mm / s, more preferably between 80 and 200 mm / s, and even more preferably between 100 and 200 mm / s.

[0099] Therefore, in one specific embodiment, the polypropylene (PP) is a linear polypropylene (l-PP) with a melt flow rate MFR2 (230°C) of 0.1~45.0 g / 10 min, F 30 Melt strength less than 30.0 cN and v 30The melt elongation is less than 220 mm / s, and the preferred melt flow rate MFR2 (230°C) is 0.1~40.0 g / 10 min. 30 Melt strength less than 30.0 cN and v 30 The melt elongation is less than 210 mm / s, and more preferably the melt flow rate MFR2 (230°C) is 0.1~35.0 g / 10 min. 30 Melt strength is between 1.0 cN and less than 30.0 cN and v 30 The melt elongation is 80~200 mm / s, and the melt flow rate MFR2 (230°C) is particularly preferred to be 0.1~30.0 g / 10 min. 30 Melt strength is between 1.5 and 30.0 cN and v. 30 The melt elongation is 100~200 mm / s, but a further preferred melt flow rate MFR2 (230°C) is 0.1~28.0 g / 10 min. 30 Melt strength is between 2.0 cN and less than 27.0 cN and v 30 Melt elongation is 100~200 mm / s, and melt flow rate MFR2 (230°C) is 0.1~25.0 g / 10 min, F 30 Melt strength is between 2.5 cN and less than 27.0 cN and v 30 The melt elongation is 100~200mm / s.

[0100] Preferably, the melting point of the polypropylene (PP) (preferably linear polypropylene (l-PP)) is at least 140°C, more preferably at least 150°C, and even more preferably at least 158°C.

[0101] Polypropylene (PP) (preferably linear polypropylene (1-PP)) can be produced in known ways, for example by using a unit point catalyst or a Ziegler-Natta catalyst. Polypropylene (PP) (preferably linear polypropylene (1-PP)) can be a propylene homopolymer (H-PP) (preferably linear propylene homopolymer (1-H-PP)) or a propylene copolymer (R-PP) (preferably linear propylene copolymer (1-R-PP)). The content and type of comonomers are referenced to the information above regarding high melt strength random propylene copolymers (R-HMS-PP). Preferably, the polypropylene (PP) is linear polypropylene (1-PP). More preferably, the polypropylene (PP) is linear propylene homopolymer (1-H-PP). Therefore, all information regarding melt flow rate MFR2 (230°C), melting point, and F... 30 Melt strength, v 30 Information on melt extensibility, particle size, and particle size distribution is particularly applicable to linear propylene homopolymers (1-H-PP).

[0102] In a preferred embodiment, the polypropylene (PP) (preferably linear polypropylene (l-PP)) is free of additive (A). Therefore, if the polypropylene composition of the present invention contains additive (A), these additives (A) are not introduced into the polypropylene composition during the manufacture of high melt strength polypropylene (HMS-PP).

[0103] Nucleating agent (NA)

[0104] The polypropylene composition (PC) also contains one or more nucleating agents, preferably one nucleating agent.

[0105] Generally, it should be noted that the polypropylene composition (PC) may contain any nucleating agent known to those skilled in the art and commonly used in the product to be prepared.

[0106] For example, suitable nucleating agents include organic α-nucleating agents selected from phosphorus-based nucleating agents, such as mono-, di-, or tetraphenyl phosphate esters or metal salts of phosphate esters, as shown in the following formula:

[0107] (1)

[0108] Where R1 is oxygen, sulfur, or a hydrocarbon group with 1 to 10 carbon atoms; R2 and R3 are hydrogen or hydrocarbons or hydrocarbon groups with 1 to 10 carbon atoms, respectively; R2 and R3 can be the same or different from each other, two R2, two R3, or R2 and R3 can be combined to form a ring, M is a monovalent to trivalent metal atom; n is an integer from 1 to 3, m is 0 or 1, and n > m.

[0109] Preferred examples of α-nucleating agents represented by the above formula include:

[0110] Sodium 2,2'-methylene bis(4,6-di-tert-butylphenyl) phosphate,

[0111] Sodium 2,2'-ethylene bis(4,6-di-tert-butylphenyl) phosphate,

[0112] Lithium 2,2'-methylene bis(4,6-di-tert-butylphenyl) phosphate,

[0113] Lithium 2,2'-ethylene bis(4,6-di-tert-butylphenyl) phosphate,

[0114] Sodium 2,2'-ethylene bis(4-isopropyl-6-tert-butylphenyl) phosphate,

[0115] Lithium 2,2'-methylene bis(4-methyl-6-tert-butylphenyl) phosphate,

[0116] Lithium 2,2'-methylene bis(4-ethyl-6-tert-butylphenyl) phosphate,

[0117] Calcium bis[2,2'-thiobis(4-methyl-6-tert-butylphenyl)phosphate]

[0118] Calcium bis[2,2'-thiobis(4-ethyl-6-tert-butylphenyl)phosphate]

[0119] Calcium bis[2,2'-thiobis(4,6-di-tert-butylphenyl)phosphate]

[0120] Magnesium bis[2,2'-thiobis(4,6-di-tert-butylphenyl)phosphate]

[0121] Magnesium bis[2,2'-thiobis(4-tert-octylphenyl)phosphate]

[0122] Sodium 2,2'-Butylenebis(4,6-dimethylphenyl)phosphate,

[0123] Sodium 2,2'-Butylidene bis(4,6-di-tert-butylphenyl) phosphate,

[0124] Sodium 2,2'-tert-octylmethylene bis(4,6-dimethylphenyl) phosphate,

[0125] Sodium 2,2'-tert-octylmethylene bis(4,6-di-tert-butylphenyl) phosphate,

[0126] Calcium bis[2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate]

[0127] Magnesium bis[2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate]

[0128] Barium bis[2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate]

[0129] Sodium 2,2'-methylenebis(4-methyl-6-tert-butylphenyl) phosphate,

[0130] Sodium 2,2'-methylene bis(4-ethyl-6-tert-butylphenyl) phosphate,

[0131] Sodium (4,4'-dimethyl-5,6'-di-tert-butyl-2,2'-biphenyl) phosphate

[0132] Calcium bis[(4,4'-dimethyl-6,6'-di-tert-butyl-2,2'-biphenyl)phosphate]

[0133] Sodium 2,2'-ethylene bis(4-m-butyl-6-tert-butylphenyl) phosphate,

[0134] Sodium 2,2'-methylenebis(4,6-dimethylphenyl)phosphate,

[0135] Sodium 2,2'-methylene bis(4,6-di-t-ethylphenyl) phosphate,

[0136] Potassium 2,2'-Ethylene bis(4,6-di-tert-butylphenyl) phosphate,

[0137] Calcium bis[2,2'-ethylidene bis(4,6-di-tert-butylphenyl)phosphate]

[0138] Magnesium bis[2,2'-ethylidene bis(4,6-di-tert-butylphenyl)phosphate]

[0139] Barium bis[2,2'-ethylidene bis(4,6-di-tert-butylphenyl)phosphate]

[0140] bis[2,2'-methylenebis(4,6-di-tert-butylphenyl)phosphate]hydroxyaluminum,

[0141] Tris[2,2'-Ethylenebis(4,6-di-tert-butylphenyl)phosphate]aluminum.

[0142] The second group of phosphorus-based nucleating agents includes, for example, bis[2,4,8,10-tetra(l,l-dimethylethyl)-6-hydroxy-12H-dibenzo-[d,g]-dioxane-octyl phosphate]hydroxyaluminum and its blends with lithium myristate or lithium stearate.

[0143] In addition, sorbitol-based nucleating agents, such as dibenzyl sorbitol that can be substituted in any way, such as 1,3:2,4-dibenzyl sorbitol, 1,3:2,4-di(methylbenzyl)sorbitol, 1,3:2,4-di(ethylbenzyl)sorbitol, 1,3:2,4-di(3,4-dimethylbenzyl)sorbitol, or rosin, can be used as nucleating agents.

[0144] Furthermore, suitable α-nucleating agents are polymeric nucleating agents selected from vinylcycloalkane polymers and vinylalkane polymers. Nucleation using these polymeric nucleating agents is accomplished through specialized reaction techniques, wherein the catalyst is prepolymerized with a comonomer (such as vinylcyclohexane (VCH)), or by blending a propylene polymer with a vinyl(cyclo)alkane polymer. These methods are described in detail in EP 0 316 187 A2 and WO 99 / 24479, etc., the contents of which are incorporated herein by reference.

[0145] In addition to the nucleating agents described above, α-nucleating agents suitable for the polyolefin compositions of the present invention are described, for example, in (Macromolecules 2005, 38, 3688-3695), the disclosure of which is incorporated herein by reference.

[0146] Nucleating agents such as ADK NA-11 (sodium methylene-bis(4,6-di-butylphenyl)phosphate) and ADK NA-21 (containing bis[2,4,8,10-tetra(l,l-dimethylethyl)-6-hydroxy-12H-dibenzo-[d,g]-dioxane-octyl phosphate]hydroxyaluminum) are suitable and are available from Asahi Denka Kokai Co., Ltd. Millad 3988 (3,4-dimethylbenzyl sorbitol), Millad 3905, and Millad 3940, available from Milliken & Company, are other examples of nucleating agents that can be used in this invention.

[0147] Other commercially available α-nucleating agents that can be used in the compositions of this invention include, for example, Irgaclear XT 386 (N-[3,5-bis-(2,2-dimethylpropionamide)-phenyl]-2,2-dimethylpropionamide) from Ciba Specialty Chemicals, and Hyperform HPN-68L and Hyperform HPN-20E from Milliken & Company.

[0148] Nonitol is a nucleating agent, such as 1,2,3-trideoxy-4,6:5,7-bis-O-(4-propylphenyl)methylene nonitol (CAS-no. 882073-43-0, e.g. Millad NX8000, supplier: Milliken).

[0149] Another suitable nucleating agent is the chemical foaming agent Hydrocerol (trade name), which is available from Clariant Chemicals.

[0150] Talc is another suitable nucleating agent.

[0151] Talc is particularly preferred. In one preferred embodiment, talc is the sole nucleating agent in the polypropylene composition (PC).

[0152] The particle size d of nucleating agents (such as talc) 50 The micrometer size is between 1 and 30 μm, preferably 2 to 25 μm, more preferably 5 to 20 μm, and most preferably 5 to 15 μm.

[0153] Additive (A)

[0154] Additive (A) can be any useful additive in the technical field of high melt strength polypropylene (HMS-PP) and its applications. Therefore, additive (A) used in the polypropylene compositions of the present invention, and thus in the form of additive mixtures (AM), includes, but is not limited to, antioxidants (e.g., sterically hindered phenols, phosphites / phosphonates, sulfur-containing antioxidants, alkyl radical scavengers, aromatic amines, hindered amine stabilizers, or mixtures thereof), metal passivators (e.g., Irganox MD 1024), or UV stabilizers (e.g., hindered amine light stabilizers), etc. Other typical additives are modifiers such as antistatic agents or antifogging agents (e.g., ethoxyamines and amides, or glyceryl esters), acid scavengers, binders (e.g., polyisobutylene), lubricants and resins (ionomer waxes, PE- and ethylene copolymer waxes, Fischer-Tropsch waxes, montan waxes, fluorinated compounds, or paraffin waxes), as well as slip removers and anti-clogging agents (e.g., calcium stearate, crude amides, oleamides, talc, natural silica and synthetic silica or zeolites) and mixtures thereof.

[0155] Preferred additives are slippers, such as calcium stearate.

[0156] As previously stated, Additive (A) does not contain nucleating agents.

[0157] Typically, the total amount of additive (A) is 15% by weight or less, more preferably 10% by weight or less, such as 0.1 to 10% by weight, preferably 0.1 to 5% by weight, and more preferably 0.2 to 1% by weight, based on the total weight of the polypropylene composition.

[0158] Polypropylene composition

[0159] In the first embodiment, as described above, the foamed board is composed of a polypropylene composition containing at least 85% by weight, for example 85 to 99.5% by weight of high melt strength polypropylene (HMS-PP) and 0.5 to 15% by weight of nucleating agent (NA).

[0160] For example, the foamed board is composed of a polypropylene composition, wherein the polypropylene polymer consists of at least 85% by weight, for example 85 to 99.5% by weight, high melt strength polypropylene (HMS-PP) and 0.5 to 15% by weight, nucleating agent (NA).

[0161] Preferably, the polypropylene composition of the first embodiment comprises, and preferably consists of, the following components:

[0162] - 85~95% by weight, preferably 87.5~92.5% by weight, of high melt strength polypropylene (HMS-PP); and

[0163] - 5.0~15% by weight, preferably 7.5~12.5% ​​by weight of nucleating agent (NA).

[0164] For example, the polypropylene composition of the first embodiment comprises, and preferably consists of, the following components:

[0165] - 85~95% by weight, preferably 87.5~92.5% by weight, of high melt strength polypropylene (HMS-PP); and

[0166] - 5.0~15% by weight, preferably 7.5~12.5% ​​by weight, of nucleating agent (NA); and

[0167] - Additive (A) of 15% by weight or less, preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, and most preferably 0.2 to 1% by weight.

[0168] In a second embodiment, preferably, the polypropylene composition comprises, and is preferably composed of, the following components:

[0169] - At least 85% by weight, for example 85-99.5% by weight, more preferably 85-95% by weight, and even more preferably 87.5-92.5% by weight of high melt strength polypropylene (HMS-PP); and

[0170] - 0.5 to 15% by weight, more preferably 5.0 to 15% by weight, and even more preferably 7.5 to 12.5% ​​by weight of nucleating agent (NA).

[0171] For example, the polypropylene composition comprises, and preferably consists of, the following components:

[0172] - At least 85% by weight, for example 85 to 99.5% by weight, more preferably 85 to 95% by weight, and even more preferably 87.5 to 92.5% by weight of high melt strength polypropylene (HMS-PP); and

[0173] - 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 nucleating agent (NA); and

[0174] - Additive (A) of 15% by weight or less, preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, and most preferably 0.2 to 1% by weight.

[0175] In a preferred embodiment, the polypropylene composition comprises, and preferably consists of, the following components:

[0176] - At least 85% by weight, for example 85 to 99.5% by weight, more preferably 85 to 95% by weight, and even more preferably 87.5 to 92.5% by weight of high melt strength polypropylene (HMS-PP) and

[0177] - 0.5 to 15% by weight, more preferably 5.0 to 15% by weight, and even more preferably 7.5 to 12.5% ​​by weight of talc as nucleating agent (NA).

[0178] For example, the polypropylene composition comprises, and preferably consists of, the following components:

[0179] - At least 85% by weight, for example 85 to 99.5% by weight, more preferably 85 to 95% by weight, and even more preferably 87.5 to 92.5% by weight of high melt strength polypropylene (HMS-PP); and

[0180] - 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 nucleating agent (NA); and

[0181] - Additive (A) of 15% by weight or less, preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight, and most preferably 0.2 to 1% by weight.

[0182] It is worth noting that, unless otherwise stated, all contents are based on the total weight of the polypropylene composition.

[0183] The preferred features of the polypropylene compositions of all embodiments of the present invention are described below.

[0184] In a preferred variation, the total amount of polymers other than high melt strength polypropylene (HMS-PP) is only 5% by weight or less, more preferably 2% by weight or less, and even more preferably 1% by weight or less, based on the total weight of polymer materials in the polypropylene composition.

[0185] As previously mentioned, high melt strength polypropylene (HMS-PP) is the main component of the polypropylene composition of the present invention. Therefore, it is preferable that the final polypropylene composition exhibits rheological behavior similar to that of high melt strength polypropylene (HMS-PP).

[0186] Therefore, the polypropylene composition preferably has F 30 Melt strength greater than 25.0 cN and v 30 Melt elongation greater than 205 mm / s, preferably F 30 Melt strength is greater than 25.0 cN to 50.0 cN and v 30 Melt elongation greater than 205~300 mm / s is used to provide polypropylene compositions with good shear thinning properties. 30 Melt strength and v 30 Melt elongation was measured according to ISO 16790:2005.

[0187] In a preferred embodiment, the polypropylene composition has:

[0188] (a) F 30 The melt strength is greater than 25.0 cN to 45.0 cN, preferably greater than 25.0 cN to 42.0 cN, and most preferably greater than 25.0 cN to 40.0 cN; and

[0189] (b)v 30 The melt elongation is greater than 210 mm / s to 300 mm / s, more preferably 215 to 290 mm / s, even more preferably 220 to 270 mm / s, and most preferably 225 to 260 mm / s.

[0190] In a particularly preferred embodiment, the polypropylene composition has an F content greater than 25.0 cN to 45.0 cN. 30 Melt strength and v = 215~290 mm / s 30 Melt elongation, for example, F 30 Melt strength is greater than 25.0 cN to 42.0 cN and v 30 Melt elongation is 215~290 mm / s, or F 30 Melt strength is greater than 25.0 cN to 40.0 cN and v 30 Melt elongation is 220~270 mm / s, or F 30 Melt strength is greater than 25.0 cN to 40.0 cN and v 30 The melt elongation is 220~260 mm / s.

[0191] Furthermore, preferably, the polypropylene composition has a melt flow rate MFR2 (230°C) (measured according to ISO 1133) of not more than 15.0 g / 10 min, more preferably in the range of 0.5 to 15.0 g / 10 min, and particularly preferably 1.0 to 15.0 g / 10 min, such as 1.5 to 15.0 g / 10 min.

[0192] In a particularly preferred embodiment, the melt flow rate MFR2 (230°C) of the polypropylene composition (measured according to ISO 1133) is not more than 7.0 g / 10 min, preferably 0.5 to 7.0 g / 10 min, more preferably 0.5 to 6.5 g / 10 min, even more preferably 0.5 to 6.0 g / 10 min, and especially preferably 1.0 to 6.0 g / 10 min, such as 1.5 to 5.0 g / 10 min.

[0193] Therefore, in one specific embodiment, the polypropylene composition has:

[0194] (a) The melt flow rate MFR2 (230°C) is not more than 15.0 g / 10 min, more preferably in the range of 0.5 to 15.0 g / 10 min, and especially preferably 1.0 to 15.0 g / 10 min, such as 1.5 to 15.0 g / 10 min;

[0195] (b) F 30 The melt strength is greater than 25.0 cN to 45.0 cN, preferably greater than 25.0 cN to 42.0 cN, and most preferably greater than 25.0 cN to 40.0 cN; and

[0196] (c)v 30 The melt elongation is 210~300 mm / s, more preferably 215~290 mm / s, especially preferably 220~270 mm / s, and most preferably 225~260 mm / s.

[0197] In a particularly preferred variant of this embodiment, the melt flow rate MFR2 (230°C) of the polypropylene composition (measured according to ISO 1133) is not more than 7.0 g / 10 min, preferably 0.5 to 7.0 g / 10 min, more preferably 0.5 to 6.5 g / 10 min, even more preferably 0.5 to 6.0 g / 10 min, particularly preferably 1.0 to 6.0 g / 10 min, such as 1.5 to 5.0 g / 10 min.

[0198] Therefore, in one specific embodiment, the melt flow rate MFR2 (230°C) of the polypropylene composition is in the range of 0.5~15.0 g / 10 min, F 30 Melt strength is greater than 25.0 cN~45.0 cN, v 30 Melt elongation is 215~290 mm / s, and if the melt flow rate MFR2 (230°C) is in the range of 1.0~15.0 g / 10 min, F 30 Melt strength is greater than 25.0 cN to 42.0 cN, v 30 Melt elongation is in the range of 215~290 mm / s, or melt flow rate MFR2 (230°C) is in the range of 1.0~15.0 g / 10 min, F 30 Melt strength is greater than 25.0 cN to 40.0 cN, v 30 Melt elongation is 220~270 mm / s, or melt flow rate MFR2 (230°C) is in the range of 1.5~15.0 g / 10 min, F 30 Melt strength is greater than 25.0 cN to 40.0 cN, v 30 The melt elongation is 225~260 mm / s.

[0199] In a particularly preferred variant of this embodiment, the melt flow rate MFR2 (230°C) of the polypropylene composition (measured according to ISO 1133) is not more than 7.0 g / 10 min, preferably 0.5 to 7.0 g / 10 min, more preferably 0.5 to 6.5 g / 10 min, even more preferably 0.5 to 6.0 g / 10 min, and especially preferably 1.0 to 6.0 g / 10 min, such as 1.5 to 5.0 g / 10 min, or 1.0 to 5.0 g / 10 min.

[0200] foam board

[0201] As previously described, in the first embodiment, the foamed board is composed of a polypropylene composition containing 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 nucleating agent (NA), and the thickness of the foamed board is less than 0.5 mm or more than 2.0 mm.

[0202] In one embodiment, the foamed board is composed of a polypropylene composition containing 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), and the thickness of the foamed board is less than 0.5 mm or more than 2.0 mm.

[0203] The foam board can be in the form of a thin foam board, preferably with a thickness of 0.1 to 0.5 mm, more preferably 0.3 to 0.5 mm. Optionally, the foam board can be in the form of a thick foam board, preferably with a thickness of 2.0 to 10 mm, more preferably 2.0 to 7.0 mm.

[0204] Preferably, the density of the foamed board is 50~350 kg / m³. 3 More preferably 75~325kg / m 3 .

[0205] If the thickness of the foamed board is less than 0.5 mm, preferably 0.1~0.5 mm, more preferably 0.3~0.5 mm, the density of the foamed board is preferably 50~350 kg / m³. 3 More preferably 75~325kg / m 3 .

[0206] If the thickness of the foamed board is 2.0 mm or more, preferably 2.0~10 mm, more preferably 2.0~7.0 mm, the density of the foamed board is preferably 50~350 kg / m³. 3 More preferably 75~325kg / m 3 .

[0207] Furthermore, the foamed board is also characterized by its surface roughness. Typically, the surface roughness is less than 3.5 μm, preferably less than 2.5 μm, and most preferably less than 1.5 μm.

[0208] In one embodiment, the foamed board can exist as an extruded laminate or an extruded coated sheet. Skilled personnel are very familiar with extruded laminates or extruded coated sheets, and how such boards are prepared, so no further information is required.

[0209] The foamed board preferably satisfies the following relationship (I):

[0210] Compressive strength at 25% compression / (foam density) 2 > 0.018 kPa / (kg / m 3 ) 2 (I)

[0211] More preferably, the following relation (Ia) is satisfied:

[0212] Compressive strength at 25% compression / (foam density) 2 > 0.019 kPa / (kg / m 3 ) 2 (Ia)

[0213] The compressive strength at 25% compression is the compressive strength measured at 25% compression without pre-compression cycle [0] according to ISO 3386-1, and the unit is kPa; the foam density is the foam density measured according to ISO 845, and the unit is kg / m³. 3 .

[0214] The foamed board preferably satisfies the following relationship (II):

[0215] Compressive strength at 40% compression / (foam density) 2 > 0.023 kPa / (kg / m 3 ) 2 (II)

[0216] More preferably, the following relation (IIa) is satisfied:

[0217] Compressive strength at 40% compression / (foam density) 2 > 0.020 kPa / (kg / m 3 ) 2 (IIa)

[0218] The compressive strength at 40% compression is the compressive strength measured at 40% without pre-compression cycles [0] according to ISO 3386-1, in kPa; the foam density is the foam density measured according to ISO 845, in kg / m³.3 .

[0219] The foamed board preferably has a recovery rate of at least 85%, as determined by the method described in the embodiments of this specification.

[0220] More preferably, the foamed board satisfies equations (I) and (II) and has a recovery rate of at least 85% as determined by the method described in the examples herein. More preferably, the foamed board satisfies equations (Ia) and (IIa) and has a recovery rate of at least 85% as determined by the method described in the embodiments of this specification.

[0221] Preferably, the polymer portion of the foamed board is entirely composed of high melt strength polypropylene (HMS-PP).

[0222] Foamed boards can be packaging foam, insulation material or flooring lining, sandwich composite material containing a PP foam core layer, or foamed boards used in automobiles.

[0223] The preferred characteristics of the polypropylene composition are also the preferred characteristics of the foamed board of the present invention.

[0224] Foam products

[0225] As described above, in the second embodiment, the present invention provides a foaming material composed of a polypropylene composition, which satisfies the following relationships (I) and (II):

[0226] Compressive strength at 25% compression / (foam density) 2 > 0.018 kPa / (kg / m 3 ) 2 (I)

[0227] The compressive strength at 25% compression is the compressive strength measured at 25% compression without pre-compression cycle [0] according to ISO 3386-1, and the unit is kPa; the foam density is the foam density measured according to ISO 845, and the unit is kg / m³. 3 .

[0228] Compressive strength at 40% compression / (foam density) 2 > 0.020 kPa / (kg / m 3 ) 2 (II)

[0229] The compressive strength at 40% compression is the compressive strength measured at 40% compression without pre-compression cycle [0] according to ISO 3386-1, and the unit is kPa;

[0230] Foam density is the density of foam as determined according to ISO 845, and the unit is kg / m³. 3;

[0231] The recovery rate of the foamed material, as determined by the method described in the embodiments of this application, is at least 85%.

[0232] More preferably, the foamed material meets the requirements.

[0233] - The following relation (Ia):

[0234] Compressive strength at 25% compression / (foam density) 2 > 0.019 kPa / (kg / m 3 ) 2 (Ia)

[0235] The compressive strength at 25% compression is the compressive strength measured at 25% compression without pre-compression cycle [0] according to ISO 3386-1, and the unit is kPa;

[0236] Foam density is the density of foam as determined according to ISO 845, and the unit is kg / m³. 3 .

[0237] - The following relation (IIa):

[0238] Compressive strength at 40% compression / (foam density) 2 > 0.020 kPa / (kg / m 3 ) 2 (IIa)

[0239] The compressive strength at 40% compression is the compressive strength measured at 40% compression without pre-compression cycle [0] according to ISO 3386-1, and the unit is kPa;

[0240] Foam density is the density of foam as determined according to ISO 845, and the unit is kg / m³. 3 ;and

[0241] The recovery rate of the foamed material, as determined by the method described in the embodiments of this application, is at least 85%.

[0242] Foamed materials can be in the form of flat sheets.

[0243] Preferably, the density of the foam product is 50~350 kg / m³. 3 More preferably 75~325kg / m 3 .

[0244] Preferably, the polymer portion of the foamed board is entirely composed of high melt strength polypropylene (HMS-PP).

[0245] The foamed material is preferably in the form of a foamed board, wherein the polypropylene composition comprises and preferably consists of at least 85% by weight of high melt strength polypropylene (HMS-PP) and 0.5 to 15% by weight of a nucleating agent (NA), and the thickness of the foamed board is less than 0.5 mm or more than 2.0 mm.

[0246] The preferred features of this variation are given in the aforementioned "foamed board" section.

[0247] Foamed materials can be packaging foam, insulation materials or flooring linings, sandwich composite materials containing a PP foam core layer, or foams used in automobiles.

[0248] The preferred characteristics of the polypropylene composition are also the preferred characteristics of the foaming material of the present invention.

[0249] application

[0250] The present invention also relates to the use of polypropylene compositions in the production of foamed materials that satisfy the following relationships (I) and / or (II), the polypropylene composition comprising and preferably consisting of at least 85% by weight, for example 85 to 99.5% by weight, high melt strength polypropylene (HMS-PP) and 0.5 to 15% by weight, nucleating agent (NA).

[0251] Compressive strength at 25% compression / (foam density) 2 > 0.018 kPa / (kg / m 3 ) 2 (I)

[0252] The compressive strength at 25% compression is the compressive strength measured at 25% compression without pre-compression cycle [0] according to ISO 3386-1, and the unit is kPa;

[0253] Foam density is the density of foam as determined according to ISO 845, and the unit is kg / m³. 3 .

[0254] Compressive strength at 40% compression / (foam density) 2 > 0.020 kPa / (kg / m 3 ) 2 (II)

[0255] The compressive strength at 40% compression is the compressive strength measured at 40% compression without pre-compression cycle [0] according to ISO 3386-1, and the unit is kPa;

[0256] Foam density is the density of foam as determined according to ISO 845, and the unit is kg / m³. 3 .

[0257] Preferably, the recovery rate of the foamed material, as determined by the method described in the embodiments of this application, is at least 85%.

[0258] Preferably, the foaming material can be packaging foam, insulation material or floor lining, or foam for automobiles.

[0259] The preferred features of the polypropylene composition, foamed board, and foamed material of the present invention are also preferred features for the application of the present invention. Example

[0260] Measurement methods

[0261] Unless otherwise specified, the definitions of the following terms and measurement methods apply to the general description of the present invention above, and equally to the following embodiments.

[0262] MFR

[0263] The MFR of polypropylene was determined according to ISO 1133 at a load of 2.16 kg and a temperature of 230 °C.

[0264] Polymer density

[0265] Density was measured according to ISO 1183-1—Method A (2004). Samples were prepared by compression molding according to ISO 1872-2:2007.

[0266] Comonomer content in polypropylene

[0267] After basic attribution calibration by quantitative 13C nuclear magnetic resonance (NMR) in a manner known in the art, the comonomer content was determined by quantitative Fourier transform infrared spectroscopy (FTIR). The film was pressed to a thickness of 250 μm, and the spectrum was recorded in transmission mode.

[0268] Specifically, the ethylene content in the polypropylene-co-ethylene copolymer is determined by adjusting the concentration of ethylene in the 720-722 cm⁻¹ column. -1 and 730~733cm -1 The baseline-corrected peak area of ​​the quantitative absorption band at 767 cm⁻¹ was used for determination. Propylene-1-butene copolymer was measured at 767 cm⁻¹. -1 The absorption peak at the specified location was evaluated. Quantitative results were obtained based on the film thickness.

[0269] Melting point temperature (T) m ), heat of fusion (H) f ), crystallization temperature (T) c ) and heat of crystallization (H c According to ISO 11357 / 3, the melting point temperature T of a 5-10 mg sample was measured using a TA Instruments Q2000 differential scanning calorimeter (DSC).m and crystallization temperature T c .

[0270] Crystallization and melting temperatures were measured at a scan rate of 10°C / min between 30 and 225°C during hot / cold / hot cycling. The melting and crystallization temperatures were used as the absorption and exothermic peaks in the self-cooling and second heating cycles, respectively.

[0271] MFR2 (230°C) was measured according to ISO 1133 (230°C, 2.16 kg load).

[0272] Melt strength F 30 and melt elongation v 30

[0273] The tests described herein are in accordance with ISO 16790:2005.

[0274] The strain hardening behavior was determined by the method described in the paper "Rheotens-Mastercurves and Drawability of PolymerMelts", MH Wagner, Polymer Engineering and Sience, Vol. 36, pages 925-935. The contents of that paper are incorporated herein by reference. The strain hardening behavior of the polymer was analyzed using a rheometer (Rheotens apparatus, manufacturer: Gottfert, Siemensstr. 2, 74711 Buchen, Germany), in which the melt strands were stretched downwards at a specified acceleration.

[0275] Rheological testing simulates the industrial spinning and extrusion process. Generally, the melt is pressed or extruded through a die, and the resulting strands are then drawn out. Stress on the extrudate is recorded as a function of melt properties and measurement parameters (particularly the ratio between output and draw speeds, essentially a measurement of elongation). For the results shown below, the material was extruded using a laboratory extruder, the 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 a strand extrusion rate of 5 mm / s, and the melt temperature was set to 200°C. The length of the spun yarn between the die and the rheological wheel was 80 mm. At the start of the test, the take-up speed of the rheological wheel was adjusted to the speed of the extruded polymer filament (with zero tensile force); then the take-up speed of the rheological wheel was slowly increased until the polymer filament broke, thus initiating the experiment. The acceleration of the rheological wheel was sufficiently small to allow for the measurement of tensile force under quasi-steady-state conditions. The acceleration of pulling down the melt strand was 120 mm / s. 2The rheometer works in conjunction with the PC program EXTENS. This is a real-time data acquisition program that displays and stores the measured data of tensile force and pull-down speed. The endpoints of the rheological curve (force versus pulley speed) are considered as F. 30 Melt strength and tensile properties.

[0276] gel content

[0277] Approximately 2g of polymer (m p Weigh it, place it in a metal sieve, and weigh it again (m). p+m The polymer in the mesh strainer was placed in a Soxhlet apparatus and extracted with boiling xylene for 5 hours. The eluent was then replaced with fresh xylene, and the extraction was repeated for 1 hour. Subsequently, the mesh strainer was dried and weighed again (m). XHU+m According to m XHU+m -m m =m XHU The mass of heat-insoluble xylene obtained by the formula (m) XHU ) and polymer mass (m p The relationship between xylene and heat-insoluble matter m was obtained. XHU / m p The score.

[0278] Particle size / polymer particle size distribution

[0279] Grading sieving tests were performed on the polymer samples. Sieving analysis was performed using nested sieve columns with wire mesh sieves. The sieve aperture sizes were as follows: > 20 pm, > 32 pm, > 63 pm, > 100 pm, > 125 pm, > 160 pm, > 200 pm, > 250 pm, > 315 pm, > 400 pm, > 500 pm, > 710 pm, > 1 mm, > 1.4 mm, > 2 mm, > 2.8 mm. The samples were poured into the top sieve with the largest aperture. The lower sieve apertures in the column were smaller than those above them (see dimensions shown above). The bottom was the receiver. The column was placed in a mechanical vibrator, which shook the column. After vibration, the material on each sieve was weighed. The weight of the sample on each sieve was then divided by the total weight to obtain the weight percentage of the material retained on each sieve.

[0280] particle size of nucleating agent

[0281] Median particle size d 50 Calculated from particle size distribution (mass percentage), which was determined according to ISO 13317-3 using a Sedigraph 5100 (manufacturer: Micromeritics Corporation) by gravity liquid sedimentation.

[0282] Foam density

[0283] The foam density was measured according to ISO 845 using an analytical and semi-micro precision balance (manufacturer: Switzerland PRECISA Gravimetrics AG, Switzerland).

[0284] Foam pore size

[0285] The pore size of the foam was determined using an optical microscope from a China Tawain CBS stereoscopic microscope.

[0286] The measurement method used is as follows:

[0287] 1. Cut a strip of foam material along the transverse (CD) and longitudinal (MD) directions.

[0288] 2. Clamp the foam material with flat pliers and shave it off precisely with a razor blade.

[0289] 3. Use a 100× focusing microscope and adjust the illumination of the foam material.

[0290] 4. Measure the length and width of each unique cell in the CD and MD directions and record the values.

[0291] 5. Count the individual bubbles that have been measured and record the values.

[0292] 6. In the CD and MD directions, measure the wall thickness of each individual bubble along the entire length of 3-4 tangents from one side to the other, and record the values.

[0293] 7. Starting from the bottom of the first bubble group to be measured, measure the thickness of the entire strip three times, from the middle of the bubble group to the top of the bubble group.

[0294] 8. Measure the total length from the lowest complete cell to the highest complete cell.

[0295] 9. Move the microscope field of view so that the bottom of the topmost incomplete bubble touches the bottom of the lens.

[0296] 10. Repeat steps 4-9 for each new individual cell until approximately 0.200" to 0.800" of the material strip has been measured. Ensure that the total length and cell composition do not overlap. Each subsequent total length measurement is taken from the top of the previous highest complete cell to the top of the current highest complete cell.

[0297] Surface roughness of foam

[0298] The measurements were performed using an SJ-310 portable surface roughness measuring instrument (manufactured by Mitutoyo, Japan). This surface roughness measuring instrument (also known as a profilometer) is a contact-type surface roughness measuring instrument. Roughness determination is fully automated and operates through built-in software.

[0299] compressive strength

[0300] The compressive strength at 25% compression and 40% compression is the compressive strength determined at 25% compression without pre-compression cycle [0] according to ISO 3386-1.

[0301] recovery rate

[0302] Recovery rate was determined on samples with an area of ​​50 × 5 mm, which were cut and stacked in 6 layers. The initial thickness of the folded specimen was measured, and then the specimen was compressed to 50% of its thickness using a Zwick Universal Testing Machine at a constant speed of 50 mm / min with a preload of 10 N. The test was performed in a general laboratory environment set at 23 ± 5°C and 50 ± 5% RH. The load was immediately removed, the sample was allowed to recover for 5 minutes, and then the final thickness was measured again. The percentage recovery rate (%) was calculated using the following formula:

[0303] Recovery rate (%) = (Final thickness × 100) / Initial thickness

[0304] Opening ratio

[0305] The porosity was determined according to ASTM D6226.

[0306] Tensile strength and elongation

[0307] Tensile strength and elongation were determined in the longitudinal (MD) and transverse (CD) directions according to ISO 1798.

[0308] Maximum flexural force, maximum flexural strain under stress, flexural E-modulus, flexural toughness

[0309] According to ISO 178, the maximum flexural force, maximum stressed flexural strain, flexural E modulus, and flexural toughness were determined in the longitudinal (MD) and transverse (CD) directions.

[0310] Water absorption rate

[0311] The water absorption rate (weight gain) was determined according to ASTM D1056.

[0312] thermal stability

[0313] Thermal stability was determined by exposure to 70°C for 24 hours, according to ASTM D3575 suffix S.

[0314] Invention Embodiment 1 (IE1)

[0315] The foam board is prepared as follows:

[0316] 1. Add Daploy™ WB 140HMS (MFR2 (230°C) according to ISO 1133, 2.1 g / 10 min, and F according to ISO 16790:2005) to the solution. 30 The melt strength is 36 cN, according to ISO 16790:2005 v 30 The melt elongation was 230 mm / s (HMS-PP, manufactured by Borealis AG) and talc were dry-mixed at a weight ratio of 90:10 for Daploy™ WB 140HMS / talc.

[0317] 2. The mixture obtained in step one is fed into the first single-screw extruder (manufactured by Pitac in Taiwan, China) (screw diameter 90mm; L / D ratio 26). The extruder is operated at 200°C (5 heating zones: 150°C; 200°C; 200°C; 200°C; 200°C) to melt the polymer;

[0318] 3. Liquid butane (as a foaming agent) accounting for 3% by weight of the total weight of the mixture is injected into the last section of the first single-screw extruder to obtain a melted mixture;

[0319] 4. Pass the molten mixture through a second single-screw extruder (2 nd The single screw extruder (manufactured by Pitac in Taiwan, China) (screw diameter 120mm; L / D ratio 34) cools the melt mixture to 160°C at the end of the second single screw extruder.

[0320] 5. The molten mixture obtained in step four is passed through an extrusion die placed at the end of the second extruder. Upon exiting the extruder, the molten mixture is exposed to atmospheric pressure due to a sudden pressure drop, causing the foaming agent in the molten mixture to expand, thus completing foaming and producing a foam structure. The foam structure is then cooled in a cooling roller at a temperature below 100°C to obtain a density of 95.5 kg / m³. 3 Foamed board with a thickness of 3.0mm.

[0321] Embodiment 2 of the Invention (IE2)

[0322] Repeat the steps of Embodiment 1 of the invention, but the density of the foamed board in step 5 is 200.6 kg / m³. 3 .

[0323] Invention Embodiment 3 (IE3)

[0324] Repeat the steps of Embodiment 1 of the invention, but the density of the foamed board in step 5 is 285.5 kg / m³. 3 .

[0325] Comparative Example 1 (CE1)

[0326] The preparation of polyethylene foam boards is as follows:

[0327] 1. LD 1925 AS (LDPE, manufacturer: Tasnee), Plastron GMS 50 (GMS, manufacturer: Plastron) and talc are dry-mixed at a weight ratio of LDPE / GMS / talc of 95:3:2.

[0328] 2. The mixture obtained in the first step is fed into the first single-screw extruder (1 st A single screw extruder, manufactured by Pitac in Taiwan, China (screw diameter 90mm; L / D ratio 26). The extruder operates at 185°C (5 heating zones: 150°C; 165°C; 175°C; 185°C; 185°C) to melt the polymer;

[0329] 3. Liquid butane (as a foaming agent) accounting for 8% by weight of the total weight of the mixture is injected into the last section of the first single-screw extruder to obtain a melt mixture;

[0330] 4. Pass the molten mixture through a second single-screw extruder (2 nd The single screw extruder (manufactured by Pitac in Taiwan, China) (screw diameter 120mm; L / D ratio 34) cools the melt mixture to 100°C at the end of the second single screw extruder.

[0331] 5. The molten mixture obtained in step four is passed through an extrusion die placed at the end of the second extruder. Upon exiting the extruder, the molten mixture is exposed to atmospheric pressure due to a sudden pressure drop, causing the foaming agent in the molten mixture to expand, thus completing foaming and producing a foam structure. The foam structure is then cooled in a cooling roller at a temperature below 100°C to obtain a density of 30.6 kg / m³. 3 Foamed board with a thickness of 13mm.

[0332] Comparative Example 2 (CE2)

[0333] Repeat the steps of Comparative Example 1, but with a foam board thickness of 3 mm and a foam material density of 14.4 kg / m³. 3 .

[0334] Comparative Example 3 (CE3)

[0335] The preparation of polystyrene foam boards is as follows:

[0336] 1. Dry mix Styrolution PS 168N / L (GPPS, manufacturer: Ineos) and talc at a weight ratio of 98:2.

[0337] 2. The mixture obtained in the first step is fed into the first single-screw extruder (1 st A single screw extruder, manufactured by Pitac in Taiwan, China (screw diameter 90mm; L / D ratio 26). The extruder operates at 200°C (5 heating zones: 150°C; 200°C; 200°C; 200°C; 200°C) to melt the polymer;

[0338] 3. Liquid butane (as a foaming agent) accounting for 8% by weight of the total weight of the mixture is injected into the last section of the first single-screw extruder to obtain a melt mixture;

[0339] 4. Pass the molten mixture through a second single-screw extruder (2 nd The single screw extruder (manufactured by Pitac in Taiwan, China) (screw diameter 120mm; L / D ratio 34) cools the melt mixture to 110°C at the end of the second single screw extruder.

[0340] 5. The molten mixture obtained in step four is passed through an extrusion die placed at the end of the second extruder. Upon exiting the extruder, the molten mixture is exposed to atmospheric pressure due to a sudden pressure drop, causing the foaming agent in the molten mixture to expand, thus completing foaming and producing a foam structure. The foam structure is then cooled in a cooling roller at a temperature below 100°C to obtain a density of 52.6 kg / m³. 3 Foamed board with a thickness of 3mm.

[0341] Comparative Example 4 (CE4)

[0342] Repeat the steps of Comparative Example 3, but with a foam board thickness of 5 mm and a foam material density of 72.2 kg / m³. 3 .

[0343] The results of embodiments IE1, IE2, and IE3 and comparative examples CE1, CE2, CE3, and CE4 are shown in Table 1 below.

[0344] Table 1 Results of the Invention Embodiments and Comparative Examples

[0345]

[0346] As shown in Table 1, the HMS-PP foam samples of the present invention exhibit excellent load-bearing capacity, comparable to that of PS foam, as expressed by comparable tensile and compressive strengths. Furthermore, all samples possess the density typically achievable for the corresponding type of foam. However, PS foam exhibits a lower recovery rate, while the HMS-PP foam of the present invention demonstrates a good recovery rate, comparable to that of PE foam. However, PE foam does not possess the load-bearing capacity (measured by compressive or tensile strength) of the foam of the present invention (i.e., PS foam). Therefore, the HMS-PP foam of the present invention possesses unique comprehensive properties.

Claims

1. A foamed sheet consisting of a polypropylene composition, characterized in that, The polypropylene composition comprises 85 to 95 wt% of a high melt strength polypropylene, HMS-PP, and 5.0 to 15 wt% of a nucleating agent (NA), the foamed sheet having a thickness of 2.0 to 7.0 mm, a density of 75 to 325 kg / m 3 ; The foamed sheet satisfies the following relationship (I): Compressive strength at 25% compression / (foam density) 2 > 0.018 kPa / (kg / m 3 ) 2 (I) wherein the compressive strength at 25% compression is the compressive strength at 25% compression measured according to ISO 3386-1 without a pre-compression cycle [0] in kPa, Foam density is the density of the foam determined according to ISO 845 in kg / m3 3 ; The foamed sheet also satisfies the following relationship (II): Compressive strength at 40% compression / (foam density) 2 > 0.020 kPa / (kg / m 3 ) 2 (I) wherein the compressive strength at 40% compression is the compressive strength at 40% compression measured according to ISO 3386-1 without a pre-compression cycle [0] in kPa, Foam density is the density of the foam determined according to ISO 845 in kg / m3 3 .

2. The foamed sheet according to claim 1, characterized by The nucleating agent (NA) is talc.

3. The foamed sheet according to claim 1, characterized by F 30 melt strength greater than 25.0 cN and / or a v 30 melt extensibility greater than 205 mm / s, wherein the F 30 melt strength and the v 30 melt extensibility are each determined according to ISO 16790:2005.

4. The foamed sheet according to claim 1, characterized by The polymer fraction present in the foamed sheet consists entirely of high melt strength polypropylene (HMS-PP).

5. The foamed sheet according to claim 1, characterized by The foamed sheet is a packaging foam, an insulation material or a floor underlay, a sandwich composite with a core layer of PP foam.

6. Use of a polypropylene composition comprising 85 to 95 wt% of a high melt strength polypropylene (HMS-PP) and 5.0 to 15 wt% of a nucleating agent (NA) in the production of a foamed sheet having a thickness of 2.0 to 7.0 mm and a density of 75 to 325 kg / m3. 3 and satisfying the following relation (I) and / or (II): 0.5 < (Df) < 1.5 (I) 0.5 < (Df) < 1.5 (II) wherein Df is the foaming degree of the foamed sheet. Compressive strength at 25% compression / (foam density) 2 > 0.018 kPa / (kg / m 3 ) 2 (I) wherein, The compressive strength at 25% compression is the compressive strength at 25% compression measured according to ISO 3386-1 without a pre-compression cycle [0] in kPa, Foam density is the density of the foam determined according to ISO 845 in kg / m3 3 , Compressive strength at 40% compression / (foam density) 2 > 0.020 kPa / (kg / m 3 ) 2 (II) wherein the compressive strength at 40% compression is the compressive strength at 40% compression measured according to ISO 3386-1 without a pre-compression cycle [0] in kPa, Foam density is the density of the foam determined according to ISO 845 in kg / m3 3 .

7. Use according to claim 6, characterized in that, The application is a packaging foam, an insulation material or a floor underlay, or a foam for use in automotive vehicles.

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