Silane-modified polypropylene, silane-crosslinked polypropylene, silane-modified polypropylene composition, and molded body, crosslinked molded body, and three-dimensional network fiber assembly using these

Abstract

To provide: a silane modified polypropylene which enables formation of a silane cross-linked polypropylene excellent in flexibility, heat distortion resistance, and shape restorability and which exhibits preferable heat resistance and flow property for molding of a three-dimensional network fiber assembly; silane cross-linked polypropylene obtained by cross-linking of the silane modified polypropylene; a silane modified polypropylene composition, a molded body using these; a cross-linked molded body; and a three-dimensional network fiber assembly.SOLUTION: There is provided a silane modified polypropylene formed by silane modification of a raw material propylene-based polymer, where the raw material propylene-based polymer includes the following components (a) and (b) by a ratio of the component (a) of 35-95 mass% and the component (b) of 5-65 mass% with respect to 100 mass% of the total amount of the components (a) and (b), in which the component (a) is a propylene-based polymer in which a percentage content of an α-olefin unit is 10-30 mass%, and the component (b) is a propylene-based polymer in which a percentage content of the α-olefin unit is less than 10 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a silane-modified polypropylene, a silane-crosslinked polypropylene, a silane-modified polypropylene composition, and a molded article, a crosslinked molded article, and a three-dimensional network fiber assembly using these. [Background technology]

[0002] In recent years, furniture, pillows, bed mats, and other bedding using three-dimensional network fiber assemblies obtained by extrusion molding of thermoplastic resins into a loop shape as shock-absorbing materials such as cushioning materials have become increasingly popular.

[0003] This three-dimensional reticular fiber assembly is generally produced as follows: A thermoplastic resin such as polyethylene is melted in an extruder, and the molten resin is extruded through a die with multiple holes to form a strand. A water tank is provided below the die, and the strand flows down by gravity and lands in the tank. When the strand remains in the water, the resin solidifies due to cooling by the water, producing a three-dimensional reticular fiber assembly with looped entanglements (Patent Document 1). Examples of thermoplastic resins that have been considered for use in molding include ethylene-α-olefin copolymers, foamed polyurethane, and polyester.

[0004] In cushioning materials such as bedding that use three-dimensional reticular fiber aggregates made of thermoplastic resin, strain occurs in the compression and tension directions of the fibers due to load. If this strain occurs over a long period of time or repeatedly, the cushioning material does not recover to its original thickness and gradually collapses in the compression direction, resulting in a loss of cushioning properties, a phenomenon known as "setting-off." Setting-off becomes more pronounced at high temperatures, and it is known that when heated bedding such as electric blankets is used, problems such as partial deformation of the bedding occur. This is due to the thermoplastic resin that constitutes the three-dimensional reticular fiber aggregate flowing or plastically deforming under load at high temperatures.

[0005] Therefore, in order to improve the heat resistance, which is a major weakness of polyethylene resins, a polyethylene resin composition for three-dimensional network structures has been proposed, which contains a graft reaction product obtained by grafting an ethylenically unsaturated silane compound onto a specific ethylene-α-olefin copolymer polymerized by a metallocene catalyst, and a silanol condensation catalyst (Patent Document 2).

[0006] On the other hand, in order to provide a three-dimensional network fiber structure having better chemical resistance and less odor, it has been proposed to use a specific propylene-α-olefin copolymer instead of foamed polyurethane or polyester (Patent Document 3).Furthermore, in order to provide a three-dimensional network fiber structure having better chemical resistance, high heat resistance, and less odor, it has been proposed to use a polymer alloy containing a specific propylene polymer and a propylene homopolymer (Patent Document 4). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2012 / 035736 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-181117 [Patent Document 3] Patent No. 5873225 [Patent Document 4] Patent No. 5894716 Summary of the Invention [Problem to be solved by the invention]

[0008] The technology of Patent Document 2 is premised on the use of an ethylene-α-olefin copolymer with a low melting point in order to control the fusion strength of the extruded strands immediately after extrusion so that the extruded strands form a three-dimensional network fiber assembly. Furthermore, a specific ethylene-α-olefin copolymer with a relatively low molecular weight is used to obtain an appropriate strand diameter. As a result, it is difficult to ensure sufficient heat resistance, and shape retention at high temperatures is insufficient, resulting in problems such as settling and deformation.

[0009] On the other hand, the techniques of Patent Documents 3 and 4 have been found to have an effect of improving the resistance to settling and deformation at high temperatures, but have not yet achieved sufficient performance.

[0010] The present invention has been made in consideration of the above circumstances, and aims to provide a silane-modified polypropylene that enables the production of silane-crosslinked polypropylene with excellent flexibility, heat distortion resistance, and shape recovery, and that exhibits heat resistance and fluidity suitable for molding three-dimensional reticular fiber assemblies, a silane-crosslinked polypropylene obtained by crosslinking the silane-modified polypropylene, a silane-modified polypropylene composition, and molded articles, crosslinked molded articles, and three-dimensional reticular fiber assemblies using these.

[0011] In addition to the objectives stated here, the present invention can also be positioned as another objective of achieving effects that cannot be obtained by conventional technologies, which are derived from the various components shown in the detailed description of the invention described below. [Means for solving the problem]

[0012] As a result of extensive research conducted by the present inventors to achieve the above object, they discovered that silane-modified polypropylene, which contains a specific propylene polymer in a specific ratio and is silane-modified, has suitable fluidity and is excellent in heat resistance and shape retention, and that the use of this polypropylene makes it possible to realize a three-dimensional network fiber assembly that has good moldability and is excellent in flexibility, heat distortion resistance, and shape retention, and thus completed the present invention. That is, the present invention provides various specific embodiments as shown below.

[0013] [1] A silane-modified polypropylene obtained by silane-modifying a raw material propylene polymer, wherein the raw material propylene polymer contains the following components (a) and (b) in proportions of 35 to 95 mass% of component (a) and 5 to 65 mass% of component (b), relative to 100 mass% of the total of components (a) and (b): Component (a): a propylene polymer having an α-olefin unit content of 10 to 30% by mass Component (b): a propylene polymer having an α-olefin unit content of less than 10% by mass

[0014] [2] The silane-modified polypropylene according to [1], wherein the melting point of the component (a) measured under the following conditions is 110°C or lower. <Measurement conditions> Using a differential scanning calorimeter in accordance with JIS K7121 (2010), approximately 5 mg of component (a) is heated from 20°C to 200°C at a heating rate of 100°C / min, held at 200°C for 3 minutes, cooled to -10°C at a cooling rate of 10°C / min, and then heated to 200°C at a heating rate of 10°C / min. The melting point is determined as the temperature at the top of the melting peak.

[0015] [3] The silane-modified polypropylene according to [1] or [2], wherein the melting point of the component (b) measured under the following conditions exceeds 110°C. <Measurement conditions> Using a differential scanning calorimeter in accordance with JIS K7121 (2010), approximately 5 mg of component (b) is heated from 20°C to 200°C at a heating rate of 100°C / min, held at 200°C for 3 minutes, cooled to -10°C at a cooling rate of 10°C / min, and then heated to 200°C at a heating rate of 10°C / min. The melting point is determined as the temperature at the top of the melting peak.

[0016] [4] The silane-modified polypropylene according to any one of [1] to [3], wherein the α-olefins of the components (a) and (b) are both α-olefins having 2 to 10 carbon atoms, excluding propylene.

[0017] [5] The silane-modified polypropylene according to any one of [1] to [4], wherein the silane-modified moiety of the silane-modified polypropylene is a polymerized residue of an unsaturated silane compound represented by the following formula (1): R-Si(R')3 (1) (In the formula, R is an ethylenically unsaturated hydrocarbon group, and R' are each independently a hydrocarbon group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, and at least one of the R' is an alkoxy group having 1 to 10 carbon atoms.)

[0018] [6] Density 0.850~0.930g / cm 3 The silane-modified polypropylene according to any one of [1] to [5], wherein

[0019] [7] The silane-modified polypropylene according to any one of [1] to [6], which has an MFR of 10 to 80 g / 10 min measured at 230°C under a load of 2.16 kg in accordance with JIS K7210 (1999).

[0020] [8] A silane-modified polypropylene composition comprising the silane-modified polypropylene according to any one of [1] to [7] and a silanol condensation catalyst.

[0021] [9] A molded article obtained by molding the silane-modified polypropylene composition according to [8].

[0022]

[10] A crosslinked molded article obtained by crosslinking the molded article according to [9].

[0023]

[11] The crosslinked molded article according to

[10] , which has a flexural modulus of 300 MPa or less as measured in accordance with JIS K7171 (2008).

[0024]

[12] A three-dimensional network fiber assembly obtained by molding the silane-modified polypropylene composition according to [9].

[0025]

[13] A crosslinked molded article obtained by crosslinking the three-dimensional reticular fiber assembly described in

[12] . [Effects of the Invention]

[0026] According to the present invention, it is possible to provide a silane-modified polypropylene that can be produced with excellent flexibility, heat distortion resistance, and shape recovery, and that exhibits heat resistance and fluidity suitable for molding three-dimensional reticular fiber assemblies, a silane-crosslinked polypropylene obtained by crosslinking the silane-modified polypropylene, a silane-modified polypropylene composition, and molded articles, crosslinked molded articles, and three-dimensional reticular fiber assemblies using these. DETAILED DESCRIPTION OF THE INVENTION

[0027] The following describes in detail the embodiments of the present invention, but the following embodiments are merely examples (representative examples) of the present invention and the present invention is not limited thereto. The present invention can be implemented by any modifications within the scope of the gist of the present invention. In this specification, when a numerical value or physical property value is enclosed before and after "~", the values ​​before and after the "~" are used to include the values ​​before and after the "~". In addition, in this specification, "mass %" and "wt %", and "parts by mass" and "parts by weight" are synonymous.

[0028] [Silane-modified polypropylene] The silane-modified polypropylene of the present invention is a silane-modified polypropylene obtained by silane-modifying a raw material propylene polymer, characterized in that the raw material propylene polymer contains the following components (a) and (b), with the component (a) accounting for 35 to 95 mass% and the component (b) accounting for 5 to 65 mass%, relative to 100 mass% of the total of the components (a) and (b), and in which a silane compound is grafted onto the raw material propylene polymer. Component (a): a propylene polymer having an α-olefin unit content of 10 to 30% by mass Component (b): a propylene polymer having an α-olefin unit content of less than 10% by mass

[0029] Hereinafter, a propylene-based polymer having an α-olefin unit content of 10 to 30 mass% as component (a) may be referred to as a "propylene-based polymer (a)," and a propylene-based polymer having an α-olefin unit content of less than 10 mass% as component (b) may be referred to as a "propylene-based polymer (b)."

[0030] <Propylene-based polymer (a)> The propylene polymer (a) of the component (a) is a propylene polymer having an α-olefin unit content of 10 to 30% by mass. When the α-olefin unit content of the propylene polymer (a) is 10% by mass or more, the crystallization rate of the strands during production of a three-dimensional reticular fiber assembly is slowed down, thereby improving the fusion strength of the strands and providing suitable flexibility when formed into a three-dimensional reticular fiber assembly. From the above viewpoints, the lower limit of the α-olefin unit content of the propylene polymer (a) is preferably 11% by mass or more, more preferably 12% by mass or more. On the other hand, when the α-olefin unit content of the propylene polymer (a) is 30% by mass or less, the crystallization rate of the strands can be appropriately maintained during the production of a three-dimensional reticular fiber assembly, while an increase in die swelling can be suppressed. From the above viewpoints, the upper limit of the α-olefin unit content of the propylene polymer (a) is preferably 29% by mass or less, more preferably 28% by mass or less.

[0031] The propylene polymer (a) is a copolymer of propylene units and α-olefin units other than propylene (however, the term "α-olefin" as used herein also includes ethylene). The propylene polymer (a) may also be a copolymer of propylene units, α-olefin units other than propylene, and monomer units other than α-olefin.

[0032] Examples of α-olefins other than propylene include, but are not limited to, ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-hexene, and 2,2,4-trimethyl-1-pentene. Among these, α-olefins having 2 to 10 carbon atoms other than propylene, i.e., ethylene and α-olefins having 4 to 10 carbon atoms, are preferred, and ethylene, 1-butene, 1-hexene, and 1-octene are more preferred. The propylene polymer (a) may contain only one type of α-olefin unit other than propylene, or may contain any two or more types.

[0033] Examples of the monomer other than α-olefin include one or more vinyl bond-containing monomers such as vinyl acetate, vinyl alcohol, (meth)acrylic acid, (meth)acrylic acid alkyl esters, styrene, and styrene derivatives (herein, "(meth)acrylic" refers to either or both of "acrylic" and "methacrylic"). However, from the viewpoint of die swelling when silane-modified polypropylene is obtained, the content of these other monomer units in the propylene polymer (a) is preferably 10% by mass or less, particularly 5% by mass or less, and most preferably 0% by mass (not included).

[0034] The propylene unit content of the propylene polymer (a) is preferably 70% by mass or more, particularly 72 to 88% by mass, including the case where the propylene polymer (a) contains a monomer unit other than an α-olefin.

[0035] The propylene polymer (a) may be a random copolymer or a block copolymer.

[0036] Specific examples of the propylene polymer (a) include propylene-ethylene copolymer, propylene-α-olefin copolymer having 4 to 20 carbon atoms, and propylene-ethylene-α-olefin copolymer having 4 to 20 carbon atoms.

[0037] The melting point of the propylene polymer (a) is preferably 110°C or lower, particularly preferably 109°C or lower, from the viewpoint of improving the fusion strength of the strands by slowing down the crystallization rate of the strands during production of the three-dimensional reticular fiber assembly. On the other hand, from the viewpoint of heat resistance when formed into the three-dimensional reticular fiber assembly, the melting point of the propylene polymer (a) is usually 60°C or higher, preferably 61°C or higher.

[0038] In the present invention, the melting points of the propylene polymers such as the propylene polymer (a) and the propylene polymer (b) described below are measured under the following measurement conditions. <Measurement conditions> Using a differential scanning calorimeter according to JIS K7121 (2010), approximately 5 mg of a propylene polymer is heated from 20°C to 200°C at a heating rate of 100°C / min, held at 200°C for 3 minutes, cooled to -10°C at a cooling rate of 10°C / min, and then heated to 200°C at a heating rate of 10°C / min. The melting point is determined as the temperature at the top of the melting peak.

[0039] The melt flow rate (MFR) of the propylene polymer (a), measured in accordance with JIS K7210 (1999) at a temperature of 230°C and a load of 2.16 kg, is preferably 0.5 g / 10 min or more, more preferably 1 g / 10 min or more, and is preferably 80 g / 10 min or less, more preferably 70 g / 10 min or less, from the viewpoint of ease of forming a loop coil when molding a three-dimensional network fiber assembly.

[0040] The density of the propylene polymer (a) measured according to JIS K7112 (1999) was 0.840 g / cm3 from the viewpoint of flexibility of the three-dimensional network fiber assembly. 3 It is preferable that the concentration is 0.850 g / cm or more. 3 More preferably, it is 0.940 g / cm or more. 3Preferably, it is 0.930 g / cm or less. 3 More preferably, it is:

[0041] As the propylene-based polymer (a) suitable for the present invention, commercially available products can be used, and those meeting the above-mentioned properties can be appropriately selected and used from the "Vistamax (registered trademark)" series manufactured by ExxonMobil Corporation, "Versify (registered trademark)" manufactured by The Dow Chemical Company, "Tafmer (registered trademark)" series manufactured by Mitsui Chemicals, Inc., and "Adflex (registered trademark)" series manufactured by LyondellBasell.

[0042] The raw material propylene polymer may contain only one type of propylene polymer (a), or may contain two or more types of propylene polymer (a) that differ in monomer unit composition, physical properties, etc.

[0043] <Propylene polymer (b)> The propylene polymer (b) of the component (b) is a propylene polymer having an α-olefin unit content of less than 10% by mass. When the α-olefin unit content of the propylene polymer (b) is less than 10% by mass, the heat resistance temperature of the three-dimensional reticular fiber assembly can be increased. From the above viewpoints, the upper limit of the α-olefin unit content of the propylene polymer (b) is preferably 9% by mass or less, more preferably 8% by mass or less.

[0044] Examples of the propylene polymer (b) include a propylene homopolymer, a copolymer of a propylene unit and an α-olefin unit other than propylene (however, the term "α-olefin" as used herein also includes ethylene), and a copolymer of a propylene unit, an α-olefin unit other than propylene, and a monomer unit other than an α-olefin.

[0045] Examples of α-olefins other than propylene include, but are not limited to, ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-hexene, and 2,2,4-trimethyl-1-pentene. Among these, α-olefins having 2 to 10 carbon atoms other than propylene, i.e., ethylene and α-olefins having 4 to 10 carbon atoms, are preferred, and ethylene, 1-butene, 1-hexene, and 1-octene are more preferred. The propylene polymer (b) may contain only one type of α-olefin unit other than propylene, or may contain any two or more types.

[0046] Examples of the monomer other than α-olefin include one or more vinyl bond-containing monomers such as vinyl acetate, vinyl alcohol, (meth)acrylic acid, (meth)acrylic acid alkyl esters, styrene, and styrene derivatives (herein, "(meth)acrylic" refers to either or both of "acrylic" and "methacrylic"). However, from the viewpoint of die swelling when silane-modified polypropylene is obtained, the content of these other monomer units in the propylene polymer (b) is preferably 10% by mass or less, particularly 5% by mass or less, and most preferably 0% by mass (not included).

[0047] The propylene unit content of the propylene polymer (b) is preferably 90% by mass or more, particularly 92 to 100% by mass, including the case where the propylene polymer (b) contains a monomer unit other than an α-olefin.

[0048] The propylene polymer (b) may be a random copolymer or a block copolymer.

[0049] Specific examples of the propylene polymer (b) include propylene homopolymer, propylene-ethylene copolymer, propylene-C4-20 α-olefin copolymer, and propylene-ethylene-C4-20 α-olefin copolymer.

[0050] From the viewpoint of the heat resistance of the three-dimensional reticular fiber assembly, the melting point of the propylene polymer (b) is preferably more than 110° C., more preferably not less than 120° C. On the other hand, since molding at a lower temperature is effective in reducing lumps during molding of the three-dimensional reticular fiber assembly, the melting point of the propylene polymer (b) is usually not more than 170° C., preferably not more than 165° C. In the present invention, the melting point of the propylene polymer (b) is measured under the same measurement conditions as those for the melting point of the propylene polymer (a).

[0051] The melt flow rate (MFR) of the propylene polymer (b), measured in accordance with JIS K7210 (1999) at a temperature of 230°C and a load of 2.16 kg, is preferably 0.5 g / 10 min or more, more preferably 1 g / 10 min or more, and is preferably 80 g / 10 min or less, more preferably 70 g / 10 min or less, from the viewpoint of ease of forming a loop coil when molding a three-dimensional network fiber assembly.

[0052] The density of the propylene polymer (b) measured according to JIS K7112 (1999) was 0.840 g / cm3 from the viewpoint of flexibility of the three-dimensional network fiber assembly. 3 It is preferable that the concentration is 0.850 g / cm or more. 3 More preferably, it is 0.940 g / cm or more. 3 Preferably, it is 0.930 g / cm or less. 3 More preferably, it is:

[0053] As the propylene-based polymer (b) suitable for the present invention, commercially available products can be used, and a product meeting the above-mentioned properties can be appropriately selected from the "Zelas (registered trademark)" series manufactured by Mitsubishi Chemical Corporation, the "Novatec (registered trademark)" series manufactured by Japan Polypropylene Corporation, the "Prime Polypropylene (registered trademark)" series manufactured by Prime Polymer Co., Ltd., and the like.

[0054] The raw material propylene polymer may contain only one type of propylene polymer (b), or may contain two or more types of propylene polymer (b) having different monomer unit compositions, physical properties, and the like.

[0055] <Raw material propylene polymer> The raw propylene polymer according to the present invention contains propylene polymer (a) and propylene polymer (b) in proportions of 35 to 95% by mass of propylene polymer (a) and 5 to 65% by mass of propylene polymer (b), with the total of these being 100% by mass. When the raw propylene polymer contains propylene polymer (a) in an amount of 35% by mass or more and propylene polymer (b) in an amount of 65% by mass or less, it is easy to control the hardness to a suitable level when forming a three-dimensional network fiber aggregate. From the above viewpoints, the lower limit of the content of propylene polymer (a) in the raw propylene polymer is preferably 40% by mass or more, more preferably 45% by mass or more, and the upper limit of the content of propylene polymer (b) is preferably 60% by mass or less, more preferably 55% by mass or less. On the other hand, when the content of propylene polymer (a) in the raw material propylene polymer is 95% by mass or less and the content of propylene polymer (b) is 5% by mass or more, when silane-modified polypropylene is obtained, the crystallization rate of the strands can be controlled to a level suitable for forming a three-dimensional network structure, facilitating the production of a three-dimensional network structure. From the above viewpoints, the upper limit of the content of propylene polymer (a) in the raw material propylene polymer is preferably 65% ​​by mass or less, more preferably 60% by mass or less, and the lower limit of the content of propylene polymer (b) is preferably 35% by mass or more, more preferably 40% by mass or more.

[0056] Generally, in a propylene copolymer containing α-olefin units, as the content ratio of α-olefin units increases, the molecular weight of the polymer increases upon crosslinking, resulting in increases in die swell and melt tension and improvements in compression set properties. However, in order to obtain a good three-dimensional reticular fiber assembly in the production of a three-dimensional reticular fiber assembly, appropriate die swell and melt tension are required, so in the raw material propylene polymer for producing silane-modified polypropylene, it is important to select the content ratio of the propylene polymer (a) and the propylene polymer (b) shown above.

[0057] The content of propylene units in the raw propylene polymer including the propylene polymer (a) and the propylene polymer (b) is preferably 74 to 99 mass%, more preferably 77 to 97 mass%, even more preferably 80 to 95 mass%, particularly preferably 83 to 993 mass%, and especially preferably 86 to 92 mass%, relative to 100 mass% of the raw propylene polymer, from the viewpoints of cushioning properties, heat resistance, and shape retention of the resulting three-dimensional network fiber assembly, etc. On the other hand, for the same reasons, the total content of α-olefin units other than propylene units and monomer units other than α-olefins in the raw propylene polymer is preferably 1 to 26 mass%, more preferably 3 to 23 mass%, even more preferably 5 to 20 mass%, particularly preferably 7 to 17 mass%, and especially preferably 8 to 14 mass%, relative to 100 mass% of the raw propylene polymer.

[0058] The density of the raw material propylene polymer (measured according to JIS K7112 (1999)) is not particularly limited, but is preferably 0.850 to 0.930 g / cm from the viewpoints of cushioning properties, heat resistance, and heat deformation resistance. 3 is preferably 0.860 to 0.925 g / cm 3 , more preferably 0.870 to 0.920 g / cm 3 is.

[0059] The melt flow rate (MFR, measured in accordance with JIS K7210 (1999) at a temperature of 230°C and a load of 2.16 kg) of the raw material propylene polymer is not particularly limited, but is preferably 1 to 60 g / 10 min, more preferably 2 to 59 g / 10 min, and even more preferably 3 to 58 g / 10 min. When the MFR of the raw material propylene polymer is not more than the above upper limit, the melt tension during molding of the three-dimensional reticular fiber assembly is not too low, the strands are not easily stretched, and a stable molded product tends to be easily obtained. When the MFR of the raw material propylene polymer is not less than the above lower limit, when the three-dimensional reticular fiber assembly is formed, the melt tension is not too high, which results in an excessive increase in strand diameter, making it difficult for the molten strands to deform and for loop formation to become difficult, and a stable molded product tends to be easily obtained.

[0060] <Other propylene polymers> The raw material propylene polymer according to the present invention may contain a propylene polymer other than the above-mentioned propylene polymer (a) and propylene polymer (b) in a range that satisfies the preferred content of propylene units in the raw material propylene polymer.

[0061] Other propylene-based polymers include propylene-based polymers having an α-olefin unit content of more than 30 mass% but not more than 50 mass% (here, examples of the α-olefin unit include those exemplified as the α-olefin units contained in the propylene-based polymer (a) and the propylene-based polymer (b)), and copolymers of propylene with a monomer other than an α-olefin (here, examples of the monomer other than an α-olefin include those exemplified as the monomer other than an α-olefin contained in the propylene-based polymer (a) and the propylene-based polymer (b)).

[0062] Other commercially available propylene polymers include the "ELMODU (registered trademark)" series manufactured by Idemitsu Kosan Co., Ltd.

[0063] The raw material propylene polymer may contain only one type of other propylene polymer, or may contain two or more types of other propylene polymers having different monomer unit compositions, physical properties, etc.

[0064] When the raw material propylene polymer contains other propylene polymers, the content of the other propylene polymers is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of the total of the propylene polymer (a) and the propylene polymer (b).

[0065] <Silane modification> The silane-modified polypropylene of the present invention is obtained by grafting a silane compound onto the above-mentioned raw material propylene polymer. The silane compound to be grafted is not particularly limited as long as it is a silane compound having an alkoxy group, but the silane-modified moiety of the silane-modified polypropylene of the present invention is preferably a polymer residue of an unsaturated silane compound represented by the following formula (1):

[0066] R-Si(R')3 (1) In the above formula (1), R is an ethylenically unsaturated hydrocarbon group, and R' are each independently a hydrocarbon group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, and at least one of the R' is an alkoxy group having 1 to 10 carbon atoms. R serves as a bonding site during graft introduction into a propylene-based polymer.

[0067] In the above formula (1), R is preferably an ethylenically unsaturated hydrocarbon group having 2 to 10 carbon atoms, and more preferably an ethylenically unsaturated hydrocarbon group having 2 to 6 carbon atoms. Specific examples include alkenyl groups such as vinyl, propenyl, butenyl, and cyclohexenyl.

[0068] In the above formula (1), R' is preferably a hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, more preferably a hydrocarbon group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. Furthermore, at least one of the R' is preferably an alkoxy group having 1 to 6 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms.

[0069] In the above formula (1), the hydrocarbon group having 1 to 10 carbon atoms represented by R' may be any of an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group, but is preferably an aliphatic hydrocarbon group. Furthermore, the alkoxy group having 1 to 10 carbon atoms represented by R' may be any of linear, branched, and cyclic, but is preferably linear or branched. Specific examples of the hydrocarbon group represented by R' include alkyl groups such as methyl, ethyl, isopropyl, t-butyl, n-butyl, i-butyl, and cyclohexyl, and aryl groups such as phenyl, but are not limited to these. Specific examples of the alkoxy group represented by R' include methoxy, ethoxy, isopropoxy, and β-methoxyethoxy.

[0070] In the above formula (1), at least one of the three R' is an alkoxy group, but it is preferable that two or more R' are alkoxy groups, and it is more preferable that all three R' are alkoxy groups.

[0071] As the unsaturated silane compound, vinyltrialkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, and propenyltrimethoxysilane are particularly preferred. This is because the ethylenically unsaturated hydrocarbon group facilitates silane modification of the starting propylene polymer, and the three alkoxy groups allow the crosslinking reaction described below to occur. That is, the alkoxy group of the alkoxysilane grafted onto the starting propylene polymer reacts with water in the presence of a silanol condensation catalyst to hydrolyze and generate silanol groups, and these silanol groups undergo dehydration condensation, resulting in a crosslinking reaction in which silane-modified polypropylenes are bonded together. The unsaturated silane compound may be used alone or in combination of two or more.

[0072] The content of the silane compound in the silane-modified polypropylene (the amount of the unsaturated silane compound introduced into the raw propylene polymer) is not particularly limited, but is preferably 0.1 to 5.0% by mass relative to the total amount of silane-modified polypropylene from the viewpoints of viscosity during molding, handleability, heat resistance, heat distortion resistance, shape retention, etc. The content of the silane compound in the silane-modified polypropylene is more preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, and is more preferably 4.0% by mass or less, even more preferably 3.0% by mass or less. The content of the silane compound is the mass ratio of the silane compound (unsaturated silane compound to be introduced) to the total amount of the raw material propylene-based polymer before modification. The content can also be confirmed by heating and burning a sample to turn it into inhes, fusing the ash with an alkali, dissolving it in pure water, and quantifying it using ICP atomic emission spectrometry using a high-frequency plasma atomic emission spectrometer.

[0073] The silane-modified polypropylene of the present invention may be grafted with a compound other than a silane compound (unsaturated silane compound) (hereinafter also referred to as "other graft compound"), as long as the effects of the present invention are not impaired. Examples of other graft compounds include, but are not limited to, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, and isocrotonic acid, and acid anhydrides thereof.

[0074] As described above, the silane-modified polypropylene of the present invention can be produced by grafting a silane compound onto a raw propylene polymer to silane-modify it. The silane modification method can be carried out according to known techniques and is not particularly limited. For example, solution modification, melt modification, solid-phase modification by irradiation with an electron beam or ionizing radiation, and modification in a supercritical fluid are preferably used. Among these, melt modification, which is superior in terms of equipment and cost competitiveness, is more preferred, and melt-kneading modification using an extruder, which is superior in continuous productivity, is even more preferred. Examples of devices used for melt-kneading modification include single-screw extruders, twin-screw extruders, Banbury mixers, and roll mixers. Among these, single-screw extruders and twin-screw extruders, which are superior in continuous productivity, are preferred.

[0075] Generally, grafting of a silane compound onto a propylene-based polymer can be carried out by a graft polymerization reaction in which a carbon-hydrogen bond of the propylene-based polymer is cleaved to generate a carbon radical, to which an unsaturated functional group is added. The carbon radical can be generated by using an electron beam or ionizing radiation as described above, or by using a high temperature or a radical generator such as an organic or inorganic peroxide. From the viewpoints of cost and operability, it is preferable to use an organic peroxide.

[0076] The radical generator used in producing the silane-modified polypropylene of the present invention is not particularly limited, but examples thereof include hydroperoxides, dialkyl peroxides, diacyl peroxides, organic peroxides belonging to the groups of peroxy esters and ketone peroxides, and azo compounds.

[0077] Specifically, examples of the hydroperoxide group include cumene hydroperoxide and tertiary butyl hydroperoxide. Examples of the dialkyl peroxide group include dicumyl peroxide, ditertiary butyl peroxide, 2,5-dimethyl-2,5-ditertiary butylperoxyhexane, and 2,5-dimethyl-2,5-ditertiary butylperoxyhexyne-3. Examples of the diacyl peroxide group include lauryl peroxide and benzoyl peroxide. Examples of the peroxy ester group include tertiary peroxyacetate, tertiary butyl peroxybenzoate, and tertiary butyl peroxyisopropyl carbonate. Examples of the ketone peroxide group include cyclohexanone peroxide. Examples of the azo compound include azobisisobutyronitrile and methyl azoisobutyrate. These radical generators may be used alone or in combination of two or more.

[0078] In a melt-kneading modification operation using a commonly used extruder, a raw material propylene polymer, a precursor compound of the silane compound to be grafted (e.g., an unsaturated silane compound), and, if necessary, a radical generator such as an organic peroxide are mixed and blended, and the mixture is fed into a kneader or extruder, and extruded while being heated, melt-kneaded, and the molten resin emerging from a die is cooled in a water tank or the like to obtain a silane-modified polypropylene.

[0079] The blending ratio of the starting propylene polymer to the precursor compound of the silane compound to be grafted (for example, an unsaturated silane compound) is not particularly limited and may be appropriately set depending on the desired introduction ratio of the silane compound. From the viewpoints of obtaining a desired silane modification amount and reducing the amount of unreacted material remaining, the blending ratio of the precursor compound of the silane compound is preferably 0.3 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the starting propylene polymer.

[0080] The amount of radical generator used, which is blended as needed, can be adjusted appropriately and is not particularly limited. In the case of organic peroxides, however, from the viewpoints of obtaining the desired amount of silane modification and suppressing deterioration of the resulting silane-modified polypropylene, the blending ratio of the organic peroxide is preferably 0.001 to 10 parts by mass, more preferably 0.01 to 5 parts by mass, per 100 parts by mass of the precursor compound of the silane compound (e.g., an unsaturated silane compound).

[0081] As for the melt extrusion modification conditions, when using, for example, a single screw extruder or a twin screw extruder, it is preferable to extrude at a temperature of about 150 to 300°C.

[0082] <Combined ingredients> The silane-modified polypropylene of the present invention may contain additives commonly used in resin compositions, as long as the effects of the present invention are not impaired. Examples of such additives include heat stabilizers, ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, crystal nucleating agents, rust inhibitors, viscosity modifiers, and pigments.

[0083] Specific examples of antioxidants include, but are not limited to, phenol-based, sulfur-based, and phosphorus-based antioxidants. The amount of the antioxidant to be added is not particularly limited, but is preferably 0.01 to 2.0 parts by mass, and more preferably 0.1 to 1.0 part by mass, relative to 100 parts by mass of the silane-modified polypropylene.

[0084] Specific examples of ultraviolet absorbers include benzophenone-based ones such as 2-hydroxy-4-normal-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4-carboxybenzophenone, and 2-hydroxy-4-N-octoxybenzophenone; benzotriazole-based ones such as 2-(2-hydroxy-3,5-di-t-butylphenyl)benzotriazole and 2-(2-hydroxy-5-methylphenyl)benzotriazole; and salicylic acid ester-based ones such as phenyl salicylate and p-octylphenyl salicylate, but are not particularly limited to these. The amount of the ultraviolet absorber to be added is not particularly limited, but is preferably 0.01 to 1.0 part by mass, and more preferably 0.02 to 0.5 part by mass, relative to 100 parts by mass of the silane-modified polypropylene.

[0085] As the viscosity modifier, rubber compounding oil, specifically paraffinic process oil, is preferred. The amount of the viscosity modifier to be added is preferably 0.5 to 5 parts by mass, more preferably 0.8 to 3 parts by mass, based on 100 parts by mass of the silane-modified polypropylene.

[0086] <Physical properties> The melting point of the silane-modified polypropylene of the present invention is not particularly limited, but is preferably 120°C or higher, more preferably 125°C or higher, and even more preferably 130°C or higher. When the melting point is above the above lower limit, heat resistance is high, and the resulting three-dimensional network fiber assembly makes it easier to produce products with good heat resistance. Furthermore, by setting the melting point above the above lower limit, settling tends to be less likely to occur when used at high temperatures. On the other hand, the upper limit of the melting point of the silane-modified polypropylene of the present invention is not particularly limited, but is usually 165°C or lower. The melting point of the silane-modified polypropylene was measured using a differential scanning calorimeter in accordance with JIS K7121 (2010), by heating approximately 5 mg of a sample from 20°C to 200°C at a heating rate of 100°C / min, holding at 200°C for 3 minutes, then cooling to -10°C at a cooling rate of 10°C / min, and then heating to 200°C at a heating rate of 10°C / min. The extrapolated peak end point (°C) was calculated from the thermogram measured when the sample was heated to 200°C using the differential scanning calorimeter.

[0087] The melt flow rate (MFR, measured in accordance with JIS K7210 (1999) at 230°C and a load of 2.16 kg) of the silane-modified polypropylene of the present invention is not particularly limited, but is preferably 10 g / 10 min or more, more preferably 11 g / 10 min or more, even more preferably 12 g / 10 min or more, and is preferably 80 g / 10 min or less, more preferably 79 g / 10 min or less, and even more preferably 78 g / 10 min or less. If the MFR is above the lower limit, die swelling and melt tension are low, making it difficult for the strand diameter to increase. This makes it easier for loops to form along the sides of the resulting three-dimensional network fiber aggregate, and tends to facilitate the production of products with good resilience. On the other hand, if the MFR is below the upper limit, when multiple strands are extrusion-molded, the extrusion of the strands tends to be stable, making it difficult for the multiple strands to curl up and form a solidified resin mass. Furthermore, loop formation and strand fusion are stable, strand diameter tends to be uniform, the resulting three-dimensional reticular fiber aggregate tends to have good uniformity, and the performance and quality of the product tends to be improved.

[0088] The die swell ratio of the silane-modified polypropylene of the present invention is not particularly limited, but the lower limit is preferably 0.40 or more, more preferably 0.42 or more, and even more preferably 0.44 or more. On the other hand, the upper limit is preferably 0.70 or less, more preferably 0.68 or less, and even more preferably 0.66 or less. When the die swell ratio of the silane-modified polypropylene is equal to or less than the above upper limit, the strand swell during the formation of a three-dimensional network structure can be prevented from becoming thicker than the desired wire diameter, and a loop coil tends to be easily formed. On the other hand, when the die swell ratio is equal to or more than the above lower limit, the strand diameter can be controlled so as not to become too thin, and the durability of the three-dimensional network fiber aggregate tends to be easily maintained.

[0089] The die swell ratio of silane-modified polypropylene is a value measured and calculated in accordance with 4.7.2 of JIS K 7199. Specifically, when silane-modified polypropylene is extruded at a rate of 10 mm / min from a die with a die temperature of 210°C and passed through a die with a diameter of D (mm) (measured at room temperature), the extrudate has a diameter Da (mm) (measured at room temperature), and the die swell ratio Sa is calculated using the following formula (2): Sa=Da / D (2)

[0090] The density of the silane-modified polypropylene of the present invention is measured using a press-molded sheet-like test piece having a thickness of 2 mm in accordance with JIS K7112 (1999). The density of the silane-modified polypropylene of the present invention is not particularly limited, but is preferably 0.850 g / cm from the viewpoint of flexibility when made into a three-dimensional network fiber assembly. 3 More preferably, 0.855 g / cm 3 More preferably, 0.860 g / cm 3 or more, 0.930 g / cm 3 Preferably, it is equal to or less than 0.925 g / cm 3 or less, more preferably 0.920 g / cm 3 The following is the result.

[0091] [Silane-modified polypropylene composition] The silane-modified polypropylene composition of the present invention contains at least the above-mentioned silane-modified polypropylene of the present invention and a silanol condensation catalyst.

[0092] <Silanol condensation catalyst> The silanol condensation catalyst used here includes one or more compounds selected from the group consisting of metal organic acid salts, titanates, borates, organic amines, ammonium salts, phosphonium salts, inorganic and organic acids, and inorganic acid esters.

[0093] Examples of metal organic acid salts include, but are not limited to, dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, stannous acetate, stannous octoate, cobalt naphthenate, lead octoate, lead naphthenate, zinc octoate, zinc caprylate, iron 2-ethylhexanoate, iron octoate, and iron stearate. Examples of titanates include, but are not limited to, tetrabutyl titanate, tetranonyl titanate, and bis(acetylacetonitrile)diisopropyl titanate. Examples of organic amines include, but are not limited to, ethylamine, dibutylamine, hexylamine, triethanolamine, dimethyl soya amine, tetramethylguanidine, and pyridine. Examples of ammonium salts include, but are not limited to, ammonium carbonate and tetramethylammonium hydroxide. Examples of phosphonium salts include, but are not limited to, tetramethylphosphonium hydroxide. Examples of inorganic and organic acids include, but are not limited to, sulfonic acids such as sulfuric acid, hydrochloric acid, acetic acid, stearic acid, maleic acid, toluenesulfonic acid, and alkylnaphthylsulfonic acid. Examples of inorganic acid esters include, but are not limited to, phosphate esters.

[0094] Among these, preferred are metal organic acid salts, sulfonic acids, and phosphates, and more preferred are metal carboxylates of tin, such as dioctyltin dilaurate, alkylnaphthylsulfonic acids, and ethylhexyl phosphates.The silanol condensation catalysts may be used alone or in appropriate combination of two or more.

[0095] The content of the silanol condensation catalyst in the silane-modified polypropylene composition of the present invention is not particularly limited, but from the viewpoints of suppressing premature crosslinking during molding of a molded article before crosslinking, promoting the crosslinking reaction during production of the silane-crosslinked polypropylene, and improving the heat resistance of the resulting three-dimensional network fiber assembly, etc., the content is preferably 0.01 to 0.5 parts by mass, and more preferably 0.03 to 0.3 parts by mass, per 100 parts by mass of the silane-modified polypropylene.

[0096] The silanol condensation catalyst is preferably used as a silanol condensation catalyst-containing masterbatch, which is a blend of polypropylene and the silanol condensation catalyst. Examples of polypropylene that can be used in this silanol condensation catalyst-containing masterbatch include homopolypropylene, which is a polymer of propylene, and copolymers of propylene with ethylene or α-olefins such as butene, hexene, and octene (excluding propylene). Among these, homopolypropylene and propylene-ethylene copolymers are preferred from the viewpoints of heat resistance, flexibility, and the like. The propylene-ethylene copolymer is preferably a copolymer of 60 to 98% by mass of propylene and 2 to 40% by mass of ethylene. In the silanol condensation catalyst masterbatch, only one of these polypropylenes may be used alone, or two or more may be used in appropriate combination.

[0097] When the silanol condensation catalyst is used as a silanol condensation catalyst-containing masterbatch in which polypropylene and the silanol condensation catalyst are blended, the content of the silanol condensation catalyst in the masterbatch is not particularly limited, but is usually preferably about 0.1 to 5.0 mass%. Note that a commercially available product can be used as the silanol condensation catalyst-containing masterbatch, for example, "PZ010" manufactured by Mitsubishi Chemical Corporation.

[0098] <Other ingredients> In addition to the silane-modified polypropylene and silanol condensation catalyst described above, the silane-modified polypropylene composition of the present invention may contain, as other components, various additives, resins other than the silane-modified polypropylene, and resins other than the polypropylene in the silanol condensation catalyst-containing masterbatch, etc., within a range that does not impair the effects of the present invention. For example, the silane-modified polypropylene composition may contain the above-mentioned compounding agents that can be compounded with the silane-modified polypropylene of the present invention.

[0099] Specific examples of other components include thermoplastic solid resins other than polypropylene, solid rubber, liquid resins, softeners, plasticizers, etc. These can also be used as tackifiers to improve adhesion or compatibility, etc. For example, rosin and its derivatives, terpene resins, petroleum resins and their derivatives, alkyd resins, alkylphenol resins, terpene phenol resins, coumarone-indene resins, synthetic terpene resins, alkylene resins, polyisobutylene, polybutadiene, polybutene, copolymers of isobutylene and butadiene, mineral oil, process oil, pine oil, anthracene oil, pine root oil, plasticizers, animal and vegetable oils, polymerized oils, etc.

[0100] [Silane-crosslinked polypropylene] The silane-modified polypropylene composition of the present invention can be exposed to a water-containing atmosphere to promote a crosslinking reaction between silanol groups, thereby producing a silane-crosslinked polypropylene (hereinafter, sometimes referred to as "the silane-crosslinked polypropylene of the present invention"). Various conditions can be used for the method of exposing to a water-containing atmosphere, and there are no particular limitations. Examples of the method include leaving the composition in moist air, blowing air containing water vapor onto the composition, immersing the composition in a water bath, and spraying warm water in a mist.

[0101] More specifically, in the silane-modified polypropylene composition of the present invention, hydrolyzable alkoxy groups derived from a silane compound (e.g., an unsaturated silane compound) grafted onto the silane-modified polypropylene react with water in the presence of a silanol condensation catalyst and are hydrolyzed to generate silanol groups, which then undergo dehydration condensation with each other, causing a crosslinking reaction to proceed, resulting in bonding of the silane-modified polypropylenes to generate silane-crosslinked polypropylene.

[0102] The crosslinking conditions are determined by the conditions for exposure to a water-containing atmosphere and are not particularly limited, but are usually preferably a temperature range of 20 to 130°C and a time range of 10 minutes to 1 week, more preferably a temperature range of 20 to 130°C and a time range of 1 hour to 160 hours. When using air containing moisture, the relative humidity may be adjusted appropriately within the range of 1 to 100%.

[0103] [Molded object / Crosslinked molded object] Before the crosslinking treatment, the silane-modified polypropylene composition of the present invention can be molded into a predetermined shape by various molding methods such as extrusion molding, injection molding, press molding, etc. to obtain a (non-crosslinked) molded article. The obtained (non-crosslinked) molded article can then be exposed to a water-containing atmosphere to promote the crosslinking reaction between silanol groups, thereby obtaining a crosslinked molded article (silane-crosslinked polypropylene molded article).

[0104] [Three-dimensional network fiber assembly] The silane-modified polypropylene composition of the present invention can be extruded to form strands (molded articles), and then these strands can be heat-fused together and cooled with water to form a three-dimensional reticular fiber assembly. For example, the silane-modified polypropylene composition can be molded into a three-dimensional reticular fiber assembly using a manufacturing apparatus and molding method such as those described in International Publication No. 2012 / 035736. The three-dimensional reticular fiber assembly thus obtained is preferably exposed to a water atmosphere as described above and used as a silane-crosslinked three-dimensional reticular molded article.

[0105] The silane-modified polypropylene composition of the present invention can be molded without crosslinking during molding, and therefore can be efficiently molded into three-dimensional reticular fiber assemblies that require special moldability, such as loopability immediately after molding and thermal adhesion. Moreover, the resulting molded articles have improved heat resistance, a major issue with ethylene-based copolymers such as ethylene-α-olefin copolymers, and the problem of settling even under load at high temperatures is greatly alleviated, making it possible to provide three-dimensional reticular fiber assemblies that exhibit excellent cushioning properties.

[0106] [Physical properties of silane-crosslinked polypropylene] The test pieces used to evaluate the physical properties of the silane-crosslinked polypropylene of the present invention are specifically produced by the method described in the Examples section below.

[0107] The flexural modulus of the silane-crosslinked polypropylene of the present invention can be measured in accordance with JIS K7171 (2008) using an injection-molded test piece having a thickness of 4 mm, a length of 800 mm and a width of 10 mm. The flexural modulus of the silane-crosslinked polypropylene of the present invention is not particularly limited, but is preferably 30 MPa or more, more preferably 40 MPa or more, even more preferably 50 MPa or more, and is preferably 300 MPa or less, more preferably 290 MPa or less, even more preferably 280 MPa or less. When the flexural modulus is equal to or greater than the above-mentioned lower limit, the resulting three-dimensional reticular fiber assembly tends to have sufficient strength to withstand loads and is less likely to become sagging. When the flexural modulus is equal to or less than the above-mentioned upper limit, the resulting three-dimensional reticular fiber assembly tends to have sufficient flexibility for use.

[0108] The compression set of the silane-crosslinked polypropylene of the present invention was determined by punching out an injection-molded sheet having a thickness of 2 mm into a 30 mm diameter circle, stacking six of these sheets, compressing them by 25% using a spacer, heat-treating them at a test temperature of 70°C for 22 hours, releasing the compression, and leaving them in a thermostatic chamber at 23°C and 50% RH for 30 minutes. The thickness was then measured, and the compression set (CS: unit: %) was calculated. The compression set of the silane-crosslinked polypropylene of the present invention is not particularly limited, but is preferably 60% or less, more preferably 59% or less, and even more preferably 58% or less. Having a compression set below the upper limit of the above range results in excellent heat distortion resistance and shape recovery, and the resulting three-dimensional network fiber assembly is less likely to suffer from settling. There is no particular limit on the lower limit of the compression set.

[0109] [Application] The applications of the silane-modified polypropylene, silane-modified polypropylene composition, and silane-crosslinked polypropylene of the present invention are not particularly limited. For example, they can be suitably used as cushioning materials for furniture, bedding such as bed mats and pillows, and seats for vehicles such as cars and ships. When applied to these applications, they are preferably used as the three-dimensional reticular fiber assembly described above. This three-dimensional reticular fiber assembly can also be used as a laminate with other materials as necessary. However, as mentioned above, the shape of the molded product is not limited to the three-dimensional reticular fiber assembly, and it can be molded into a predetermined shape depending on the application. [Example]

[0110] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples as long as it does not depart from the gist of the invention. Furthermore, the values ​​of various production conditions and evaluation results in the following examples are meant as preferred upper or lower limit values ​​in the embodiments of the present invention, and preferred ranges may be defined by combining the above-mentioned upper or lower limit values ​​with the values ​​in the following examples or values ​​between the examples.

[0111] [Raw materials] The raw materials used in the examples and comparative examples are shown below. The density and MFR of the raw material propylene polymer to be subjected to silane modification are approximately equal to the values ​​calculated by proportional calculation from the densities, MFRs and blending ratios of the propylene polymer (a) and the propylene polymer (b) blended into the raw material propylene polymer.

[0112] <Propylene-based polymer (a)> PP-a1: Vistamax (registered trademark) 6202 (manufactured by ExxonMobil Corporation, propylene-ethylene copolymer, MFR: 20 g / 10 min (230 °C, 2.16 kg load), density: 0.86 g / cm 3 , melting point: 102°C, ethylene unit content: 15% by mass

[0113] PP-a2: TAFMER (registered trademark) PN-2060 (Mitsui Chemicals, Inc., propylene-ethylene-butene copolymer, MFR: 6.0 g / 10 min (230°C, 2.16 kg load), density: 0.87 g / cm 3 Melting point: 160°C, α-olefin unit (ethylene unit + butene unit) content: 16% by mass

[0114] PP-a3: Adflex (registered trademark) V-109F (manufactured by LyondellBasell, propylene-ethylene copolymer, MFR: 12 g / 10 min (230°C, 2.16 kg load), density: 0.88 g / cm 3 , melting point: 142°C, ethylene unit content: 14% by mass

[0115] <Propylene polymer (b)> PP-b1: ZELAS (registered trademark) 7055 (manufactured by Mitsubishi Chemical Corporation, propylene-ethylene copolymer, MFR: 7.0 g / 10 min (230 °C, 2.16 kg load), density: 0.89 g / cm 3 , melting point: 160°C, ethylene unit content: 7% by mass

[0116] PP-b2: Novatec PP (registered trademark) MG03BD (Japan Polypropylene Corporation, propylene-ethylene copolymer, MFR: 30 g / 10 min (230 °C, 2.16 kg load), density: 0.90 g / cm 3 , melting point: 155°C, ethylene unit content: 2% by mass

[0117] PP-b3: Novatec (registered trademark) MA3Q (Japan Polypropylene Corporation, propylene homopolymer, MFR: 11 g / 10 min (230 °C, 2.16 kg load), density: 0.90 g / cm 3 , melting point: 160℃)

[0118] <Other olefin polymers> EP-c1: TAFMER (registered trademark) P-0275 (manufactured by Mitsui Chemicals, Inc., ethylene-propylene copolymer, MFR: 2.9 g / 10 min (190°C, 2.16 kg load), density: 0.86 g / cm 3 , ethylene unit content: 71% by mass, melting point: 24°C)

[0119] <Catalyst Masterbatch (MB)> Catalyst MB: PZ010 (Mitsubishi Chemical Corporation, tin catalyst (dioctyltin dilaurate)-containing homopolypropylene (MFR: 16 g / 10 min (230 °C, 2.16 kg load), density: 0.90 g / cm 3 ), dioctyltin dilaurate content: 1% by mass) was used.

[0120] [Measurement and evaluation method] The methods for measuring and evaluating various physical properties and characteristics are as follows:

[0121] [Measurement of silane-modified polypropylene] <Melting point> Using a differential scanning calorimeter manufactured by Hitachi High-Tech Science Corporation, product name "DSC6220," approximately 5 mg of sample was heated from 20°C to 200°C at a heating rate of 100°C / min in accordance with JIS K7121 (2010), and then held at 200°C for 3 minutes. After that, the sample was cooled to -10°C at a cooling rate of 10°C / min, and then heated to 200°C at a heating rate of 10°C / min. The extrapolated peak end point (°C) was calculated from the thermogram measured at this time, and this was taken as the melting point.

[0122] <Melt flow rate (MFR)> Measured at 230°C and 2.16 kg load in accordance with JIS K7210 (1999). Ta.

[0123] <Die swell ratio> The values ​​used were measured and calculated in accordance with 4.7.2 of JIS K 7199. Specifically, the silane-modified polypropylene was extruded at a rate of 10 mm / min from a die set at a die temperature of 210°C, and the extrudate obtained when passed through a die with a diameter D (mm) (measured at room temperature) had a diameter Da (mm) (measured at room temperature). The die swell ratio Sa was calculated using the following formula (2): Sa=Da / D (2)

[0124] <density> Measurements were carried out in accordance with JIS K7112 (1999) using a 2 mm thick sheet-shaped test piece obtained by press-molding silane-modified polypropylene.

[0125] [Evaluation of silane-crosslinked polypropylene] <Flexural modulus> Measurements were carried out in accordance with JIS K7171 (2008) using injection-molded silane-crosslinked test pieces measuring 4 mm in thickness, 800 mm in length, and 10 mm in width.

[0126] <Compression set> An injection-molded silane-crosslinked sheet-like molded article with a thickness of 2 mm was punched out into a circle with a diameter of 30 mm, and six of these were stacked on top of each other. In accordance with JIS K6262 (2013), they were compressed 25% using spacers and heat-treated at a test temperature of 70°C for 22 hours. After releasing the compression, they were left in a thermostatic chamber at 23°C and 50% RH for 30 minutes, after which the thickness was measured and the compression set (CS: unit: %) was calculated. The lower the compression set value, the better.

[0127] [Examples and Comparative Examples] [Example 1] 60 parts by mass of PP-a1, 40 parts by mass of PP-b1, 1.0 part by mass of vinyltrimethoxysilane (VTMOS), an unsaturated silane compound used as a silane precursor, and 0.01 part of di-tertiary butyl peroxide, an organic peroxide used as a radical generator, were mixed in a blender. The mixture was then fed into a single-screw extruder (IKG Corporation, PMS50) set at 200°C. The strand emerging from the nozzle was cooled and solidified in a water bath and then cut into pellets to obtain silane-modified polypropylene A. The melting point, MFR, die swell ratio, and density of the resulting silane-modified polypropylene A were measured according to the measurement and evaluation methods described above. The results are shown in Table 1. The density of the raw material propylene polymer for silane-modified polypropylene A is 0.87 (= 0.86 × 0.6 + 0.89 × 0.4) g / cm 3 The MFR is calculated to be 14.8 (= 20 × 0.6 + 7.0 × 0.4) g / 10 min.

[0128] Silane-modified polypropylene composition A was obtained by adding 5 parts by mass of PZ010 as catalyst MB to 100 parts by mass of the silane-modified polypropylene A obtained above. This was placed in an injection molding machine and molded into a 4 mm or 2 mm thick sheet at 200°C. This sheet was left in a thermo-hygrostat at 85°C and 85% RH for 16 hours to obtain a sheet containing silane-crosslinked polypropylene A. The flexural modulus and compression set of the obtained sheet were measured according to the measurement and evaluation methods described above. The results are shown in Table 1.

[0129] [Examples 2 to 6, Comparative Examples 1 to 5] Sheet-like molded articles containing silane-modified polypropylenes B to K and silane-crosslinked polypropylenes B to K were produced and evaluated in the same manner as in Example 1, except that the raw material compositions were as shown in Table 1. The results are shown in Table 1.

[0130] [Table 1]

[0131] The above results reveal the following:

[0132] The silane-modified polypropylenes A to F of Examples 1 to 6 have appropriate MFR and density and small die swell ratios, and therefore are easily moldable into a three-dimensional network fiber assembly, and are expected to have excellent cushioning properties. The silane-crosslinked polypropylenes A to F of Examples 1 to 6 had small compression set at 70°C, which is an index of heat distortion resistance and shape recovery. In addition, the flexural modulus, which is an index of flexibility, was a value indicating sufficient flexibility for use as a three-dimensional network fiber assembly.

[0133] The silane-crosslinked polypropylene G of Comparative Example 1, which did not use the propylene-based polymer (a) as the raw material propylene-based polymer, had a good compression set at 70°C. However, since the MFR of the silane-modified polypropylene G was low and the die swelling ratio was large, it is presumed that the moldability into a three-dimensional reticular fiber aggregate was poor. The silane-crosslinked polypropylene H of Comparative Example 2, which used only the propylene polymer (a) as the raw material propylene polymer, had a large compression set and was poor in heat distortion resistance and shape recovery. This is thought to result in residual distortion, which is likely to cause settling when made into a three-dimensional network fiber assembly. The silane-crosslinked polypropylenes I to K of Comparative Examples 3 to 6, in which the content of propylene polymer (a) in the raw material propylene polymer was low or in which only propylene polymer (b) was used, showed large compression set and poor heat distortion resistance and shape recovery. This likely led to residual distortion, which may cause settling when formed into a three-dimensional reticular fiber assembly. Furthermore, the flexural modulus, which is an index of flexibility, was too hard for use as a three-dimensional reticular fiber assembly.

[0134] From the above, it has been shown that the silane-modified polypropylene of the present invention has favorable MFR, melting point, die swell ratio, and density, and therefore has excellent moldability for three-dimensional reticular fiber aggregates, and that the silane-crosslinked polypropylene obtained by crosslinking this silane-modified polypropylene also has excellent flexibility, heat distortion resistance, and shape recovery. [Industrial Applicability]

[0135] The silane-modified polypropylene of the present invention has excellent heat resistance and fluidity suitable for molding a three-dimensional reticular fiber assembly. Therefore, by producing a three-dimensional reticular fiber assembly using this silane-modified polypropylene, it is possible to obtain a three-dimensional reticular fiber assembly that has low compression set even under heated conditions, is resistant to sagging or deformation due to use of electric bedding such as electric blankets, and has excellent heat distortion resistance and shape recovery. Therefore, the silane-modified polypropylene and silane-modified polypropylene composition of the present invention, as well as molded articles, crosslinked molded articles, and three-dimensional reticular fiber assemblies using them, can be widely and effectively used as constituent materials for, for example, bedding such as furniture, bed mats, and pillows; and cushioning materials for vehicle and marine seats.

Claims

1. A silane-modified polypropylene obtained by silane-modifying a raw material propylene-based polymer, wherein the raw material propylene-based polymer contains the following components (a) and (b), with the component (a) being 35 to 65% by mass and the component (b) being 35 to 65% by mass, relative to 100% by mass of the total of the components (a) and (b): Component (a): a propylene-based polymer having an α-olefin unit content of 10 to 30% by mass Component (b): a propylene polymer having an α-olefin unit content of less than 10% by mass (However, the "α-olefin" in the above components (a) and (b) means "ethylene or an α-olefin having 4 or more carbon atoms.")

2. The silane-modified polypropylene according to claim 1, wherein the melting point of the component (a) measured under the following conditions is 110°C or lower. <Measurement conditions> Using a differential scanning calorimeter in accordance with JIS K7121 (2010), approximately 5 mg of component (a) is heated from 20°C to 200°C at a heating rate of 100°C / min, held at 200°C for 3 minutes, cooled to -10°C at a cooling rate of 10°C / min, and then heated to 200°C at a heating rate of 10°C / min. The melting point is determined as the temperature at the top of the melting peak.

3. The silane-modified polypropylene according to claim 1 or 2, wherein the component (b) has a melting point of more than 110°C as measured under the following conditions: <Measurement conditions> Using a differential scanning calorimeter in accordance with JIS K7121 (2010), approximately 5 mg of component (b) is heated from 20°C to 200°C at a heating rate of 100°C / min, held at 200°C for 3 minutes, cooled to -10°C at a cooling rate of 10°C / min, and then heated to 200°C at a heating rate of 10°C / min. The melting point is determined as the temperature at the top of the melting peak.

4. The silane-modified polypropylene according to any one of claims 1 to 3, wherein the α-olefins of the components (a) and (b) are both α-olefins having 2 to 10 carbon atoms excluding propylene.

5. The silane-modified polypropylene according to any one of claims 1 to 4, wherein the silane-modified moiety of the silane-modified polypropylene is a polymerized residue of an unsaturated silane compound represented by the following formula (1): R-Si(R’) ３ ・・・(1) (In the formula, R is an ethylenically unsaturated hydrocarbon group, and R' are each independently a hydrocarbon group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, and at least one of the R' is an alkoxy group having 1 to 10 carbon atoms.)

6. Density is 0.850 to 0.930 g / cm ３ The silane-modified polypropylene according to any one of claims 1 to 5,

7. The silane-modified polypropylene according to any one of claims 1 to 6, which has an MFR of 10 to 80 g / 10 min measured at 230°C under a load of 2.16 kg in accordance with JIS K7210 (1999).

8. A silane-modified polypropylene composition comprising the silane-modified polypropylene according to any one of claims 1 to 7 and a silanol condensation catalyst.

9. A molded article obtained by molding the silane-modified polypropylene composition according to claim 8.

10. A crosslinked molded article obtained by crosslinking the molded article according to claim 9.

11. The crosslinked molded article according to claim 10, having a flexural modulus measured in accordance with JIS K7171 (2008) of 300 MPa or less.

12. A three-dimensional network fiber assembly obtained by molding the silane-modified polypropylene composition according to claim 8.

13. A crosslinked molded article obtained by crosslinking the three-dimensional reticular fiber assembly according to claim 12.

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