JP2023128806A - Silane-modified polypropylene, silane-modified polypropylene composition, silane crosslinked polypropylene, and molding including the same, crosslinked molding, 3d network fiber aggregate, and crosslinked molding of 3d network fiber aggregate - Google Patents

Abstract

To provide a silane-modified polypropylene or the like that can achieve a molding or the like with excellent heat distortion resistance and flexibility.SOLUTION: A silane-modified polyolefin is formed by silane-modifying a polypropylene composition including polypropylene. The polypropylene composition includes a propylene homopolymer (a) with a melting point of 50°C or higher and lower than 130°C, a propylene copolymer (b) with a melting point of 130°C or higher and 180°C or lower, including a propylene unit of 51-92 mass% and an ethylene unit and/or α-olefin unit of 8-49 mass%. The content of the component (a) is 5-50 mass% and the content of the component (b) is 50-95 mass% relative to 100 mass% of the polypropylene composition.SELECTED DRAWING: None

Description

The present invention relates to a silane-modified polypropylene, a silane-modified polypropylene composition, a silane-crosslinked polypropylene, a molded article using these, a crosslinked molded article, a three-dimensional reticulated fiber aggregate, and a crosslinked molded article of the three-dimensional reticulated fiber aggregate.

BACKGROUND ART In recent years, furniture, pillows, bed mats, and other bedding that use three-dimensional reticular fiber aggregates obtained by extruding thermoplastic resin into loop shapes as cushioning materials have become popular.

This three-dimensional network fiber aggregate is generally manufactured as follows. That is, a thermoplastic resin such as polyethylene is melted in an extruder, and the molten resin is extruded from a die having a large number of holes to form a strand. A water tank is provided below the die, and the strands naturally flow down and land in the water tank. When the strands remain in the water, the resin solidifies due to cooling by the water, forming a three-dimensional network with loop-like entanglements. A fiber aggregate is manufactured (Patent Document 1). Ethylene/α-olefin copolymers, polyurethane foams, polyesters, and the like are being considered as thermoplastic resins for use in molding.

In cushioning materials such as bedding that use three-dimensional reticular fiber aggregates made of thermoplastic resin, strain occurs in the compressive and tensile directions of the fibers due to the load, and when this strain occurs for a long time or repeatedly, the fiber aggregates Cushioning materials have become a problem because they do not recover to their original thickness and gradually collapse in the direction of compression, resulting in a loss of cushioning properties. It is known that sagging becomes more noticeable at high temperatures, and when heated bedding such as electric blankets is used, problems such as deformation of part of the bedding occur. These are caused by the thermoplastic resin constituting the three-dimensional network fiber aggregate flowing or plastically deforming under load at high temperatures.

It is known that a specific propylene-based polymer is used to improve the heat resistance of a thermoplastic resin constituting a three-dimensional network fiber aggregate (Patent Document 2). Furthermore, a technique containing silane-modified polypropylene is also known (Patent Document 3).

International Publication No. 2012/035736 International Publication No. 2016/002941 JP2018-83867A

However, in bedding applications in the medical and nursing care fields, heat resistance against sterilization at high temperatures and shape retention during disinfection treatments are required, and the technologies of Patent Documents 2 and 3 are suitable for heat resistance, flexibility, and shape retention. There was room for improvement from this perspective.

The present invention has been made in view of the above circumstances, and provides a molded article, a crosslinked molded article, a three-dimensional reticulated fiber aggregate, and a crosslinked molded article of a three-dimensional reticulated fiber aggregate that have excellent heat deformation resistance and flexibility. It is an object of the present invention to provide viable silane-modified polypropylene, silane-crosslinked polypropylene, and silane-modified polypropylene compositions. Furthermore, it is an object of the present invention to provide a molded article, a crosslinked molded article, a three-dimensional reticulated fiber aggregate, and a crosslinked molded article of a three-dimensional reticulated fiber aggregate, which are excellent in heat deformation resistance and flexibility.

The purpose of the present invention is not limited to the purpose described here, but also includes effects derived from each configuration shown in the detailed description of the invention described later, which cannot be obtained by conventional techniques. It can be positioned for other purposes.

As a result of intensive research to achieve the above object, the present inventors have discovered a propylene homopolymer having a melting point of 50°C or more and less than 130°C, and a propylene homopolymer having a melting point of 130°C or more and 180°C or less, and a propylene unit. A silane-modified polypropylene composition containing a polypropylene blended with a propylene copolymer containing 51 to 92% by mass of 51 to 92% by mass and 8 to 49% by mass of ethylene units and/or α-olefin units at a specific blending ratio. The inventors have discovered that polypropylene can solve the above problems, and have completed the present invention. That is, the present invention provides various specific embodiments shown below.

[1] A silane-modified polypropylene obtained by silane-modifying a polypropylene composition containing polypropylene, in which the polypropylene composition comprises a propylene homopolymer (a) having a melting point of 50°C or more and less than 130°C, and a propylene homopolymer (a) having a melting point of 130°C or more. The polypropylene composition 100 contains a propylene copolymer (b) having a temperature of 180° C. or higher and containing 51 to 92% by mass of propylene units and 8 to 49% by mass of ethylene units and/or α-olefin units. A silane-modified polypropylene in which the content of component (a) is 5 to 50% by mass and the content of component (b) is 50 to 95% by mass.

[2] The silane-modified polypropylene according to [1], wherein the silane-modified site 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, R' is 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 R' is One is an alkoxy group having 1 to 10 carbon atoms.)

[3] The silane-modified polypropylene according to [1] or [2], which has a half-crystallization time of 30 minutes or more as measured by a differential scanning calorimeter (DSC).
[4] Any of [1] to [3] whose melt flow rate (MFR, measured according to JIS K7210 (1999) at a temperature of 230°C and a load of 2.16 kg) is 25 to 100 g/10 minutes. The silane-modified polypropylene according to item 1.
[5] A silane-modified polypropylene composition comprising the silane-modified polypropylene according to any one of [1] to [4] and a silanol condensation catalyst.
[6] A molded article obtained by molding the silane-modified polypropylene composition according to [5].
[7] A crosslinked molded article obtained by crosslinking the molded article according to [6].
[8] A three-dimensional network fiber aggregate formed by molding the silane-modified polypropylene composition according to [5].

[9] A crosslinked molded product of a three-dimensional reticular fiber aggregate obtained by crosslinking the three-dimensional reticular fiber aggregate according to [8].
[10] A silane-crosslinked polypropylene obtained by crosslinking the silane-modified polypropylene composition according to [5], wherein the silane-modified polypropylene has a melting point of 150°C or more and 180°C or less, and complies with JIS K 7171 (2008). A silane-crosslinked polypropylene having a flexural modulus of 150 MPa or less as measured by
[11] A crosslinked molded body of a three-dimensional network fiber aggregate made of the silane crosslinked polypropylene according to [10].
[12] A silane-crosslinked polypropylene obtained by crosslinking the silane-modified polypropylene composition according to [5].

According to the present invention, silane-modified polypropylene and silane-crosslinked polypropylene are capable of producing molded bodies, cross-linked molded bodies, three-dimensional reticular fiber aggregates, and cross-linked molded bodies of three-dimensional reticular fiber aggregates that have excellent heat deformation resistance and flexibility. , and a silane-modified polypropylene composition. Furthermore, it is possible to provide a molded article, a crosslinked molded article, a three-dimensional reticulated fiber aggregate, and a crosslinked molded article of a three-dimensional reticulated fiber aggregate, which are excellent in heat deformation resistance and flexibility using these.

Embodiments of the present invention will be described in detail below, but the following embodiments are examples (representative examples) of the embodiments of the present invention, and the present invention is not limited thereto. The present invention can be modified and implemented as desired without departing from the spirit thereof.
In this specification, when "~" is used to express numerical values or physical property values before and after it, it is used to include the values before and after it. Furthermore, in this specification, "mass %" and "mass %" and "mass parts" and "weight parts" have the same meaning, respectively. Furthermore, the term (co)polymer includes both a homopolymer consisting of only one polymerization component and a copolymer consisting of two or more copolymerization components.

[Silane-modified polypropylene]
The silane-modified polypropylene of the present invention is a silane-modified polypropylene obtained by modifying a polypropylene composition containing polypropylene with silane.
[Polypropylene composition]
The polypropylene composition containing polypropylene to be subjected to silane modification according to the present invention includes a propylene homopolymer (a) (hereinafter sometimes referred to as "component (a)") and a propylene homopolymer (a) as the polypropylene. Contains a polymer (b) (hereinafter sometimes referred to as "component (b)").

(Component (a): Propylene homopolymer (a))
The propylene homopolymer (a) needs to have a melting point of 50° C. or higher and lower than 130° C., preferably 120° C. or lower, and more preferably 110° C. or lower, from the viewpoint of controlling the crystallization rate in a slow direction. More preferably, the temperature is 100°C or lower.
In addition, the propylene homopolymer (a) having a melting point (melting peak temperature) of 50 °C or more and less than 130 °C is a propylene homopolymer (a) having a melting peak temperature of 50 °C or more and less than 130 °C as measured by a differential scanning calorimeter (DSC). means propylene homopolymer.

The propylene homopolymer (a), which is a propylene homopolymer but has a low melting point, can be produced by a method of homopolymerizing propylene using a metallocene catalyst to produce a propylene homopolymer.

Examples of metallocene-based catalysts include JP-A-58-19309, JP-A-61-130314, JP-A-3-163088, JP-A-4-300887, JP-A-4-211694, and Special Publications. Transition metal compounds having one or two ligands such as a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, etc. as described in Publication No. 1-502036, and the like; Examples include catalysts obtained by combining a transition metal compound whose positions are geometrically controlled and a cocatalyst.

Among metallocene catalysts, it is preferable to use a transition metal compound in which the ligand forms a cross-linked structure through a cross-linking group, and in particular, a transition metal compound in which the ligand forms a cross-linked structure through two cross-linking groups. More preferred is a method using a metallocene catalyst obtained by combining a metal compound and a promoter. Examples of metallocene catalysts include substituted cyclopentadienyl groups, indenyl groups, substituted indenyl groups, heterocyclopentadienyl groups, substituted heterocyclopentadienyl groups, A compound in which two ligands selected from an enyl group, an amide group, a phosphide group, a hydrocarbon group, and a silicon-containing group are coordinated, and these two ligands are crosslinked by two types of crosslinking groups is created. Can be mentioned. Examples of this crosslinking group include a hydrocarbon group having 1 to 20 carbon atoms, a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, a germanium-containing group, a tin-containing group, -O-, -CO-, -S -,-SO₂-, -Se-, -NR -,-PR -, -P(O)R-, -BR - or -AlR- and the like. In addition, R Examples include a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, and a halogen-containing hydrocarbon group having 1 to 20 carbon atoms.
Propylene homopolymers produced using such metallocene catalysts have a higher stereoregularity than propylene homopolymers produced using commonly used Ziegler-Natta catalysts or metallocene catalysts. Due to its low melting point. It also has the characteristic that its crystallization rate is slow due to its low stereoregularity.

Examples of commercially available products of the propylene homopolymer (a) include "ELMODU (registered trademark)" manufactured by Idemitsu Kosan Co., Ltd. and the trade name "ELMODU S400".

The lower limit of the melt flow rate (MFR) of propylene homopolymer (a) measured in accordance with JIS K7210 (1999) at a temperature of 230°C and a load of 2.16 kg is determined by the moldability, especially for three-dimensional network fiber aggregates. , from the viewpoint of ease of forming a loop coil during molding of a crosslinked molded body of a three-dimensional network fiber aggregate, it is preferably 30 g/10 minutes or more, more preferably 40 g/10 minutes or more, and 50 g/10 minutes. More preferably, it is at least 1 minute. Similarly, from the viewpoint of loop coil formation, the upper limit is preferably 3000 g/10 minutes or less, more preferably 2900 g/10 minutes or less, and even more preferably 2800 g/10 minutes or less.

The lower limit of the density measured in accordance with JIS K7112 (1999) for propylene homopolymer (a) is determined from the viewpoint of flexibility of a molded article, especially a three-dimensional reticulated fiber aggregate, and a crosslinked molded article of a three-dimensional reticulated fiber aggregate. It is preferably 0.840 g/cm ³ or more, more preferably 0.850 g/cm ³ or more, and particularly preferably 0.860 g/cm ³ or more. The upper limit thereof is preferably 0.930 g/cm ³ or less, more preferably 0.910 g/cm ³ or less, and particularly preferably 0.890 g/cm ³ or less.

As the propylene homopolymer (a) suitable for the present invention, a commercially available product can be used, and one suitable for the above-mentioned properties can be selected from the "Elmodu (registered trademark)" series manufactured by Idemitsu Kosan Co., Ltd. Can be used.
The propylene homopolymer (a) may be composed of only one type, or may be composed of two or more types having different monomer unit compositions, physical properties, etc.

(Component (b): propylene copolymer (b))
The propylene copolymer (b) is a copolymer having propylene units, ethylene units and/or α-olefin units.
In this propylene copolymer (b), the content ratio of propylene units and ethylene units and/or α-olefin units is determined from the viewpoint of heat resistance and flexibility: 51 to 92% by mass of propylene units, 51% to 92% by mass of propylene units, 51% to 92% by mass of propylene units, 51% to 92% by mass of propylene units; 8 to 49% by mass of α-olefin units is required. By setting it within this range, heat resistance and flexibility can be improved.
Furthermore, the lower limit of the content of propylene units in the propylene copolymer (b) is more preferably 61% by mass or more from the viewpoint of heat resistance. From the viewpoint of heat resistance, the lower limit of the content of ethylene units and/or α-olefin units is more preferably 8.5% by mass or more, and even more preferably 9% by mass or more. Further, from the viewpoint of flexibility, the upper limit of the content of propylene units in the propylene copolymer (b) is more preferably 91% by mass or less. From the viewpoint of heat resistance, the upper limit of the content of ethylene units and/or α-olefin units is more preferably 40% by mass or less, and even more preferably 35% by mass or less.

Further, the melting point of the propylene copolymer (b) needs to be 130° C. or more and 180° C. or less from the viewpoint of heat resistance and flexibility. By setting it within this range, heat resistance and flexibility can be improved.
The lower limit of the melting point of the propylene copolymer (b) is preferably 135°C or higher, more preferably 140°C or higher from the viewpoint of heat resistance. On the other hand, from the viewpoint of reducing lumps during molding, since molding at a low temperature is effective, the melting point of the propylene copolymer (b) is preferably 175°C or lower, more preferably 170°C or lower.

The α-olefin forming the α-olefin unit of the propylene copolymer (b) includes 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, Examples include, but are not limited to, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-hexene, and 2,2,4-trimethyl-1-pentene. Among these, α-olefins having 4 to 10 carbon atoms, ie, α-olefins having 4 to 10 carbon atoms, are preferred, and 1-butene, 1-hexene, and 1-octene are more preferred. Only one type of these α-olefin units may be included, or any two or more types may be included.

The propylene copolymer (b) may contain monomer units other than propylene units, ethylene units, and α-olefin units (hereinafter referred to as "other monomer units"). , preferably contains one or more α-olefin units selected from propylene monomer and ethylene monomer, 1-butene monomer, 1-hexene monomer, 1-octene monomer, etc. It is preferable to do so.

Monomers forming the above-mentioned other monomer units (hereinafter sometimes referred to as "other monomers") include vinyl acetate, vinyl alcohol, (meth)acrylic acid, (meth)acrylic acid Examples include one or more vinyl bond-containing monomers such as alkyl esters, styrene, and styrene derivatives. However, from the viewpoint of heat resistance, the content of other monomer units in the propylene copolymer (b) is preferably 40% by mass or less, particularly 35% by mass or less.
Note that "(meth)acrylic" refers to one or both of "acrylic" and "methacrylic".

Specific examples of the propylene copolymer (b) include propylene/ethylene copolymer, propylene/α-olefin copolymer having 4 to 20 carbon atoms, and propylene/ethylene/α-olefin having 4 to 20 carbon atoms. Examples include propylene copolymers such as copolymers, and among these, propylene/ethylene copolymers and propylene/ethylene/butene copolymers are preferred.
Note that the propylene copolymer may be a propylene random copolymer or a propylene block copolymer.

The melt flow rate (MFR) of propylene copolymer (b) measured in accordance with JIS K7210 (1999) at a temperature of 230°C and a load of 2.16 kg is a measure of moldability, especially three-dimensional network fiber assembly. From the viewpoint of ease of forming a loop coil during molding of a crosslinked molded body and three-dimensional reticulated fiber aggregate, it is preferably 0.4 g/10 minutes or more, more preferably 0.5 g/10 minutes or more, and 80 g/10 minutes or more. The heating time is preferably 10 minutes or less, more preferably 70 g/10 minutes or less.

The density measured according to JIS K7112 (1999) of the propylene copolymer (b) is 0 from the viewpoint of the flexibility of the molded product, especially the three-dimensional reticular fiber aggregate, and the crosslinked molded product of the three-dimensional reticular fiber aggregate. It is preferably at least .840 g/cm ³ , more preferably at least 0.850 g/cm ³ , particularly preferably at least 0.860 g/cm ³ . The upper limit thereof is preferably 0.930 g/cm ³ or less, more preferably 0.910 g/cm ³ or less, and particularly preferably 0.890 g/cm ³ or less.

As the propylene copolymer (b) suitable for the present invention, commercially available products can be used, such as the "Zelas (registered trademark)" series manufactured by Mitsubishi Chemical Corporation and the "Tafmer (registered trademark)" manufactured by Mitsui Chemicals, Inc. ” series, Lyondell Basell's “Adflex (registered trademark)” series, etc., those that meet the above characteristics can be appropriately selected and used.

The propylene copolymer (b) may be composed of only one type, or may be composed of two or more types having different monomer unit compositions, physical properties, etc.

In the present invention, the melting points of the propylene homopolymer (a) and the propylene copolymer (b) can be measured under the following measurement conditions.
<Melting point measurement conditions>
Using a differential scanning calorimeter, in accordance with JIS K7121 (2010), approximately 5 mg of a sample was heated from 20°C to 200°C at a heating rate of 100°C/min, held at 200°C for 3 minutes, and then heated at a cooling rate of 10°C. The melting point is defined as the temperature at the top of the melting peak when the temperature is lowered to -10°C at a heating rate of 10°C/min and then raised to 200°C at a heating rate of 10°C/min. If multiple melting peaks are obtained, the maximum value is taken as the melting peak temperature of the sample.

[Blending ratio of polypropylene composition]
In the polypropylene composition according to the present invention, the content of the propylene homopolymer (a) is 5 to 50% by mass based on 100% by mass of the polypropylene composition. On the other hand, the content of the propylene copolymer (b) is 50 to 95% by mass based on 100% by mass of the polypropylene.

By setting the content of the propylene homopolymer (a) to 5% by mass or more, the crystallization retardation property that retards crystallization is increased, and the strands are bonded to each other in the molten state after landing in the water tank during molding. It becomes easier to entangle and melt and bond, and the three-dimensional reticular fiber aggregate and the crosslinked molded product of the three-dimensional reticular fiber aggregate tend to have excellent heat-resistant fusion bonding properties. From this point of view, the content of the propylene homopolymer (a) is more preferably 10% by mass or more, and even more preferably 15% by mass or more. On the other hand, from the viewpoint of heat resistance when formed into a crosslinked molded product, the content of the propylene homopolymer (a) is more preferably 50% by mass or less, even more preferably 45% by mass or less, and particularly preferably 40% by mass or less. .

In addition, by setting the content of the propylene copolymer (b) to 50% by mass or more, the crystallization retardation property that retards crystallization increases, and the strand remains in a molten state after landing in the water tank during molding. The strands become entangled and melt-bonded easily, and the three-dimensional reticular fiber aggregate and the crosslinked molded product of the three-dimensional reticular fiber aggregate tend to have excellent heat-resistant fusing properties. From such a viewpoint, the content of the propylene copolymer (b) is more preferably 55% by mass or more, and even more preferably 60% by mass or more. On the other hand, from the viewpoint of flexibility when formed into a crosslinked molded product, the content of the propylene copolymer (b) is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less. .

The total content of propylene homopolymer (a) and propylene copolymer (b) in 100% by mass of the polypropylene composition is 55% by mass or more from the viewpoint of heat fusion resistance, heat resistance and flexibility. It is preferably 60% by mass or more, more preferably 65% by mass or more, preferably 100% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less.
As mentioned above, the polypropylene composition may contain a propylene polymer other than the propylene homopolymer (a) and propylene copolymer (b) described above, as long as the effects of the present invention are not impaired. .

Propylene polymers other than the above-mentioned propylene homopolymer (a) and propylene copolymer (b) include propylene homopolymers with a melting point of 130°C or higher and 180°C or lower; , and a propylene copolymer containing more than 92% by mass and less than 99% by mass of propylene units, and 1% by mass or more and less than 8% by mass of ethylene units and/or α-olefin units (hereinafter referred to as propylene homopolymer ( Propylene polymers other than a) and propylene copolymer (b) may be referred to as "other propylene polymers").

(Other propylene polymers)
The other propylene-based polymer may be a propylene homopolymer or a copolymer of propylene and an α-olefin, and as an α-olefin having 2 to 20 carbon atoms (excluding 3) other than propylene to be copolymerized with propylene, , ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene , 4-methyl-1-pentene, 6-methyl-1-heptene and the like. Among these, ethylene, 1-butene, 1-hexene, and 1-octene are preferred as the α-olefin to be copolymerized with propylene.
The other propylene-based polymer may be a copolymer of propylene and one type of α-olefin, or a copolymer of a combination of two or more types of α-olefin.

Other propylene-based polymers include one or more α-olefins of 1% by mass or more but less than 8% by mass and more than 92% by mass of propylene but not more than 99% by mass of one or more α-olefins as structural units constituting the copolymer. A copolymer of these is preferred. By setting the α-olefin unit and propylene unit within this range, heat resistance when formed into a molded product can be maintained.

The density of the other propylene polymer is preferably 880 g/cm ³ or more and 965 g/cm ³ or less, more preferably 890 g/cm ³ or more and 960 g/cm ³ or less. By controlling the density of the other propylene-based polymers to be below the above upper limit, the rigidity of the crosslinked product obtained by crosslinking tends to be easily suppressed within a desired range, making it easier to maintain flexibility. When the density of the other propylene polymer is equal to or higher than the above lower limit, heat resistance tends to be easily maintained.

The MFR (230°C, load 2.16 kg) of other propylene polymers is not particularly limited, but is usually 0.5 to 30 g/10 minutes, preferably 0.8 to 20 g/10 minutes, more preferably 1 ~10g/10min. By setting the MFR to the lower limit value or more, it is possible to prevent the cohesive force alone from becoming strong and the homogeneous mixability with other components to become insufficient, and also to prevent the silane-modified polypropylene composition of the invention It is possible to prevent the energy load from becoming too large. In addition, by setting the MFR below the above upper limit, the fluidity of the silane-modified polypropylene composition of the present invention becomes too high (melt viscosity and melt tension decrease), resulting in a three-dimensional network shape, which is an index of moldability. Difficulty in forming a loop coil during molding of a crosslinked fiber aggregate can be suppressed.

As other propylene polymers, commercially available products can be used, such as the "Novatec (registered trademark)" series, "Wintech (registered trademark)" series manufactured by Nippon Polypro Co., Ltd., and the "Prime Polypro (registered trademark)" series manufactured by Prime Polymer Co., Ltd. (registered trademark) series etc., those that meet the above characteristics can be appropriately selected and used.

(Other materials)
In addition to the polypropylene described above, the polypropylene composition may contain other materials as long as the effects of the present invention are not impaired, but the total content of other materials in 100% by mass of the polypropylene composition is 45% by mass or less. It is preferably 35% by mass or less, more preferably 20% by mass or less, particularly preferably 15% by mass or less.
Other materials include the compounding agents described below.

[Compounding agent]
The polypropylene composition of the present invention may contain additives that are commonly used in resin compositions to the extent that they do not impair the effects of the present invention. Examples of such compounding agents include heat stabilizers, ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, crystal nucleating agents, rust preventives, viscosity modifiers, and pigments.

Specific examples of antioxidants include phenol-based, sulfur-based, and phosphorus-based antioxidants, but are not particularly limited thereto.
The amount of the antioxidant to be blended is not particularly limited, but is preferably 0 parts by weight, more preferably 0.1 to 1.0 parts by weight, based on 100 parts by weight of the polypropylene composition.

Specific examples of ultraviolet absorbers include 2-hydroxy-4-normal-octyloxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-4 - Benzophenones such as carboxybenzophenone and 2-hydroxy-4-N-octoxybenzophenone; 2-(2-hydroxy-3,5-di-t-butylphenyl)benzotriazole, 2-(2-hydroxy-5- Examples include benzotriarisoles such as (methylphenyl)benzotriazole; salicylic acid esters such as phenyl salicylate and p-octylphenyl salicylate, but are not particularly limited thereto.
The amount of the ultraviolet absorber to be blended is not particularly limited, but is preferably 0.01 to 1.0 parts by weight, more preferably 0.02 to 0.5 parts by weight, based on 100 parts by weight of silane-modified polypropylene.

The viscosity modifier is preferably a rubber compounding oil, specifically a paraffinic process oil. The blending amount of the viscosity modifier is preferably 0.5 to 5 parts by weight, more preferably 0.8 to 3 parts by weight, based on 100 parts by weight of silane-modified polypropylene.
Other materials may include known ethylene polymers.

[Silane-modified polypropylene]
The silane-modified polypropylene of the present invention is a silane-modified polypropylene obtained by modifying the polypropylene composition containing the above-mentioned polypropylene with silane.
Graft modification using a silane compound is suitable for silane modification. 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 site of the silane-modified polypropylene is a polymerized residue of an unsaturated silane compound represented by the following formula (1). It is preferable. That is, as the silane compound used for silane modification, an unsaturated silane compound represented by the following formula (1) is preferable.

R-Si(R') ₃ ...(1)
In the above formula (1), R is an ethylenically unsaturated hydrocarbon group, R' is independently a hydrocarbon group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, and R' is At least one of them is an alkoxy group having 1 to 10 carbon atoms. Note that R becomes a bonding site during graft introduction into polypropylene.

In the above formula (1), R is preferably an ethylenically unsaturated hydrocarbon group having 2 to 10 carbon atoms, more preferably an ethylenically unsaturated hydrocarbon group having 2 to 6 carbon atoms. Specifically, alkenyl groups such as a vinyl group, a propenyl group, a butenyl group, and a cyclohexenyl group can be mentioned.

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 a hydrocarbon group having 1 to 6 carbon atoms. 4 is an alkoxy group. Further, at least one of R' is preferably an alkoxy group having 1 to 6 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms.

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

In the above formula (1), at least one of the three R's is an alkoxy group, but preferably two or more R's are an alkoxy group, and all three R's are an alkoxy group. is more preferable.

As specific examples of unsaturated silane compounds, vinyltrialkoxysilanes represented by vinyltrimethoxysilane, vinyltriethoxysilane, propenyltrimethoxysilane, etc. are particularly preferred. This is because the ethylenically unsaturated hydrocarbon group facilitates silane modification of the raw material 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 raw material propylene polymer reacts with water in the presence of a silanol condensation catalyst and is hydrolyzed to generate silanol groups, and the silanol groups are dehydrated and condensed with each other. This causes a crosslinking reaction in which the silane-modified polypropylenes bond together. In addition, one type of unsaturated silane compound may be used alone, or two or more types may be used in an appropriate combination.

The content of constituent elements derived from silane compounds in silane-modified polypropylene is not particularly limited, but the total amount of silane-modified polypropylene should be determined from the viewpoints of viscosity during molding, handleability, heat resistance, heat deformation resistance, shape retention, etc. The amount is preferably 0.1 to 5.0% by mass. The content of the silane compound in the silane-modified polypropylene is more preferably 0.2% by mass or more, still more preferably 0.3% by mass or more, and more preferably 4.0% by mass or less, even more preferably is 3.0% by mass or less.
Note that the content of the silane compound in the silane-modified polypropylene is the mass ratio of the silane compound (unsaturated silane compound to be introduced) to the total amount of polypropylene before modification.

The silane-modified polypropylene of the present invention may be grafted with a compound other than the silane compound (unsaturated silane compound) (hereinafter also referred to as "other graft compound") to the extent that the effects of the present invention are not impaired. Examples of other graft compounds include 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; Examples include, but are not limited to, acid anhydrides.

As described above, the silane-modified polypropylene of the present invention can be produced by graft-introducing a silane compound to polypropylene and silane-modifying it. The silane modification method can be performed according to a known method and is not particularly limited. For example, solution modification, melt modification, solid phase modification by irradiation with electron beams or ionizing radiation, and modification in a supercritical fluid are preferably used. Among these, melt modification with excellent equipment and cost competitiveness is more preferred, and melt kneading modification using an extruder with excellent continuous productivity is even more preferred. Examples of devices used for melt-kneading modification include a single screw extruder, a twin screw extruder, a Banbury mixer, and a roll mixer. Among these, single-screw extruders and twin-screw extruders are preferred because of their excellent continuous productivity.

Generally, the graft introduction of a silane compound into polypropylene can be carried out by a graft polymerization reaction in which the carbon-hydrogen bonds of polypropylene are cleaved to generate carbon radicals, and an unsaturated functional group is added to the carbon radicals. As a source for generating carbon radicals, in addition to the above-mentioned electron beam or ionizing radiation, it is also possible to use a high temperature method or a radical generator such as an organic or inorganic peroxide. From the viewpoint of cost and operability, it is preferable to use an organic peroxide.

The radical generator used in producing the silane-modified polypropylene of the present invention is not particularly limited, but examples include organic radical generators included in the group of hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxy esters, and ketone peroxides. Examples include oxides and azo compounds.

Specifically, the hydroperoxide group includes cumene hydroperoxide and tert-butyl hydroperoxide. Examples of the dialkyl peroxide group include dicumyl peroxide, ditertiary butyl peroxide, 2,5-dimethyl-2,5-ditertiary butyl peroxyhexane, and 2,5-dimethyl-2,5-ditertiary butyl peroxide. Examples include hexin-3. Examples of the diacyl peroxide group include lauryl peroxide and benzoyl peroxide. Examples of the peroxy ester group include tertiary peroxy acetate, tertiary butyl peroxybenzoate, and tertiary butyl peroxy isopropyl carbonate. The ketone peroxide group includes cyclohexanone peroxide. Examples of the azo compound include azobisisobutyronitrile and methylazoisobutyrate. These radical generators may be used alone or in an appropriate combination of two or more.

In the melt-kneading modification operation using a commonly used extruder, polypropylene, a silane compound to be grafted (e.g., an unsaturated silane compound), and a radical generator such as an organic peroxide are mixed as necessary. Then, the mixture is blended and put into a kneader or extruder, extruded while being heated, melted and kneaded, and the molten resin coming out of the die is cooled in a water tank or the like to obtain silane-modified polypropylene.

The blending ratio of the polypropylene and the silane compound to be grafted (for example, an unsaturated silane compound) may be appropriately set depending on the desired introduction ratio of the silane compound, and is not particularly limited. From the viewpoint of obtaining the desired amount of silane modification and reducing residual unreacted materials, the blending ratio of the silane compound is preferably 0.3 to 10 parts by mass, more preferably 0.5 parts by mass, relative to 100 parts by mass of polypropylene. ~5 parts by mass.

In addition, the amount of the radical generator to be blended as necessary can be adjusted appropriately and is not particularly limited, but in the case of organic peroxides, it is possible to obtain the desired amount of silane modification and to obtain the resulting silane modification amount. From the viewpoint of suppressing the deterioration of polypropylene, etc., the blending ratio of the organic peroxide is preferably 0.001 to 10 parts by mass, more preferably 0.01 parts by mass, per 100 parts by mass of the silane compound (for example, an unsaturated silane compound). ~5 parts by mass.
Further, as the melt extrusion modification conditions, for example, when using a single screw extruder or a twin screw extruder, it is preferable to extrude at a temperature of about 150 to 300°C.

[Physical properties]
[Half crystallization time]
The half-crystallization time of the silane-modified polypropylene of the present invention as measured by a differential scanning calorimeter (DSC) is preferably 30 minutes or more.
Approximately 5 mg of the sample was heated from 30°C to 230°C at a heating rate of 100°C/min in a nitrogen atmosphere using a differential scanning calorimeter manufactured by Hitachi High-Tech Co., Ltd., trade name "DSC7000X". After holding for 10 minutes, the temperature was lowered to 125°C at a cooling rate of 100°C/min, and then held at 125°C for 40 minutes. Using the thermogram measured, the half crystallization time (min.) was calculated from the time to reach 50% enthalpy. was calculated. A larger value indicates higher crystallization retardation.

The half-crystallization time can be controlled by the content of the propylene homopolymer (a) in 100% by mass of propylene, and by setting the content to 5% by mass or more, the crystallization retardation that retards crystallization increases. Due to the increased crystallization retardation, the strands become entangled and melt-bonded easily in the molten state after they land in the water tank during molding, making it easier to form three-dimensional reticular fiber aggregates and cross-linked three-dimensional reticular fiber aggregates. The body tends to have excellent heat-resistant fusion properties.

The melting point of the silane-modified polypropylene of the present invention is 150°C or higher. When the melting point is equal to or higher than the above lower limit, heat resistance is high, and it becomes easy to produce a product having good heat resistance in the resulting crosslinked molded product and the like. In addition, by setting the melting point to the above lower limit or higher, it tends to be less likely to sag 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 180°C or lower.
From the above viewpoint, the melting point of the silane-modified polypropylene of the present invention is preferably 155°C or higher, more preferably 160°C or higher.

The melting point of silane-modified polypropylene is determined by heating approximately 5 mg of a sample from 20°C to 200°C at a heating rate of 100°C/min for 3 minutes at 200°C using a differential scanning calorimeter according to JIS K7121 (2010). After holding, the temperature was lowered to -10°C at a cooling rate of 10°C/min, and then the extrapolated peak end point (°C) was calculated from the thermogram measured when the temperature was raised to 200°C at a heating rate of 10°C/min. The melting point is used.

The melt flow rate (MFR, measured at a temperature of 230°C and a load of 2.16 kg according to JIS K7210 (1999)) of the silane-modified polypropylene of the present invention is not particularly limited, but is preferably 15 g/10 minutes or more, More preferably 20 g/10 minutes or more, still more preferably 25 g/10 minutes or more, preferably 100 g/10 minutes or less, more preferably 90 g/10 minutes or less, even more preferably 80 g/10 minutes or less. When the MFR is equal to or higher than the above lower limit, the die swell and melt tension are low, making it difficult to increase the strand diameter, making it easy to form loops along the sides of the resulting three-dimensional reticular fiber aggregate, resulting in a good rebound feeling. It tends to be easier to create products with Moreover, when MFR is below the said upper limit, when extrusion-molding a plurality of strands, the discharge of a strand tends to be stable, and the plurality of strands tend to be difficult to curl up and form a hardened resin mass. In addition, loop formation and fusion of the strands are stable, the strand diameter tends to be uniform, the resulting three-dimensional reticular fiber aggregate has good uniformity, and the performance and quality of the product tend to be improved.

The density of the silane-modified polypropylene of the present invention is measured in accordance with JIS K7112 (1999) using a press-molded sheet-like test piece with a thickness of 2 mm. The density of the silane-modified polypropylene of the present invention is not particularly limited, but from the viewpoint of flexibility when made into a three-dimensional reticular fiber aggregate or a crosslinked molded product of a three-dimensional reticular fiber aggregate, the density is 0.850 g/cm ³ or more. Preferably, more preferably 0.855 g/cm ³ or more, still more preferably 0.860 g/cm ^{3 or more, preferably 0.930 g/cm 3 or} less, more preferably 0.925 g/cm ³ or less, even more preferably It is 0.920 g/cm ³ or less.

[Silane-modified polypropylene composition]
The silane-modified polypropylene composition of the present invention is a composition containing at least the silane-modified polypropylene of the present invention described above and a silanol condensation catalyst.

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

The metal organic acid salts include dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, stannous acetate, stannous octoate, cobalt naphthenate, lead octylate, lead naphthenate, and octylic acid. Examples include, but are not limited to, zinc, zinc caprylate, iron 2-ethylhexanoate, iron octylate, iron stearate, and the like.
Examples of the titanate include, but are not limited to, tetrabutyl titanate, tetranonyl titanate, bis(acetylacetonitrile) di-isopropyl titanate, and the like.

Examples of the organic amine include ethylamine, dibutylamine, hexylamine, triethanolamine, dimethylsawyaamine, tetramethylguanidine, pyridine, and the like, but are not particularly limited thereto.
Examples of the ammonium salt include ammonium carbonate and tetramethylammonium hydroxide, but are not particularly limited thereto.
Examples of the phosphonium salt include tetramethylphosphonium hydroxide, but are not particularly limited thereto.
Examples of the inorganic acids and organic acids include sulfonic acid compounds such as sulfuric acid, hydrochloric acid, acetic acid, stearic acid, maleic acid, toluenesulfonic acid, and alkylnaphthylsulfonic acid, but are not particularly limited thereto. Examples of inorganic acid esters include, but are not limited to, phosphoric acid esters.

Among these, preferred are metal organic acid salts, sulfonic acid compounds, and phosphoric acid esters, and more preferred are tin metal carboxylates, such as dioctyltin dilaurate, alkylnaphthylsulfonic acid, and ethylhexyl phosphate. Note that the silanol condensation catalyst may be used alone or in an appropriate combination of two or more.

The content of the silanol condensation catalyst in the silane-modified polypropylene composition of the present invention is not particularly limited, but it suppresses early crosslinking during molding of the molded article before crosslinking, and promotes the crosslinking reaction during the production of silane crosslinked polypropylene. From the viewpoint of improving the heat resistance of the obtained three-dimensional network fiber aggregate, etc., the amount is preferably 0.01 to 0.5 parts by mass, more preferably 0.03 to 0.5 parts by mass, per 100 parts by mass of silane-modified polypropylene. 3 parts by mass.

Note that the silanol condensation catalyst is preferably used as a silanol condensation catalyst-containing masterbatch in which a resin and the silanol condensation catalyst are blended. Examples of resins that can be used in this silanol condensation catalyst-containing masterbatch include homopolypropylene, which is a polymer of propylene, propylene, and α-olefins such as ethylene or butene, hexene, and octene (excluding propylene). and ethylene copolymers. Among these, homopolypropylene and propylene/ethylene copolymerization are preferred from the viewpoint of heat resistance, flexibility, etc. Here, 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 addition, in the masterbatch of the silanol condensation catalyst, only one type of these polypropylenes may be used alone, or two or more types may be used in an appropriate combination.

When using a silanol condensation catalyst as a silanol condensation catalyst-containing masterbatch containing a resin and a silanol condensation catalyst, there is no particular restriction on the content of the silanol condensation catalyst in the masterbatch, but it is usually 0.1 to 5.0. It is preferable to set it to about mass %. Note that a commercial product can be used as the silanol condensation catalyst-containing masterbatch, and for example, "PZ010" manufactured by Mitsubishi Chemical Corporation can be used.

[Other ingredients]
The silane-modified polypropylene composition of the present invention contains, in addition to the above-mentioned silane-modified polypropylene and silanol condensation catalyst, various additives and resins other than silane-modified polypropylene (polypropylene in the masterbatch containing the silanol condensation catalyst, (including resins other than polypropylene in the silanol condensation catalyst-containing masterbatch) may be contained within a range that does not impair the effects of the present invention. For example, it may contain the above-mentioned compounding agents that can be blended into the silane-modified polypropylene of the present invention.

When the silane-modified polypropylene composition of the present invention contains components other than the above-mentioned silane-modified polypropylene and silanol condensation catalyst, in order to fully obtain the effects of containing the silane-modified polypropylene and silanol condensation catalyst, the other components The content is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, based on 100 parts by weight of silane-modified polypropylene.

Specific examples of other components include thermoplastic solid resins other than polyolefins, solid rubbers, liquid resins, softeners, plasticizers, and the like. These can also be used as tackifiers to improve adhesiveness or compatibility. For example, rosin and its derivatives, terpene resins and petroleum resins and their derivatives, alkyd resins, alkylphenol resins, terpenephenol resins, coumaron indene resins, synthetic terpene resins, alkylene resins, polyisobutylene, polybutadiene, polybutene, isobutylene and butadiene combinations. It may contain polymers, mineral oils, process oils, pine oil, anthracene oil, pine oil, plasticizers, animal and vegetable oils, polymerized oils, and the like.

[Silane crosslinked polypropylene]
The silane-modified polypropylene composition of the present invention can be exposed to a water-containing atmosphere to allow a crosslinking reaction between silanol groups to proceed, resulting in a silane-crosslinked polypropylene. The method of exposing to the water-containing atmosphere is not particularly limited, and various conditions can be adopted. Examples include a method of leaving the product in air containing moisture, a method of blowing air containing water vapor, a method of immersing the product in a water bath, and a method of spraying hot water in a mist.

Specifically, in the silane-modified polypropylene composition of the present invention, a hydrolyzable alkoxy group derived from a silane compound (for example, an unsaturated silane compound) grafted into the silane-modified polypropylene is dissolved in water in the presence of a silanol condensation catalyst. A silanol group is generated by reacting with the polypropylene and hydrolyzing it, and the silanol groups are further dehydrated and condensed with each other, whereby a crosslinking reaction progresses, and the silane-modified polypropylenes are bonded to each other to produce a silane-crosslinked polypropylene.

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

[Molded product/crosslinked molded product]
Before the above-mentioned 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 (uncrosslinked) molded body. . Then, by exposing the obtained (uncrosslinked) molded product to a water-containing atmosphere, a crosslinking reaction between the silanol groups is allowed to proceed, and a crosslinked molded product (silane crosslinked polypropylene molded product) can be obtained.

[Three-dimensional network fiber aggregate and crosslinked molded product thereof]
A three-dimensional reticular fiber aggregate can be obtained by extrusion molding the silane-modified polypropylene composition of the present invention into strands, then heat-sealing the strands together, and then cooling with water. For example, a silane-modified polypropylene composition can be molded into a three-dimensional network fiber aggregate using a manufacturing apparatus and a molding method as described in International Publication No. 2012/035736. The three-dimensional reticulated fiber aggregate thus obtained is preferably exposed to a water atmosphere as described above and used as a crosslinked three-dimensional reticulated molded product.

Molded products using ethylene copolymers such as ethylene/α-olefin copolymers still have problems with heat resistance, and although improvements were seen by using specific propylene polymers or silane-modified polypropylene. However, heat resistance that can withstand sterilization at high temperatures has not yet been achieved. The silane-modified polypropylene composition of the present invention can be molded without crosslinking during molding, so it can efficiently form three-dimensional reticular fiber aggregates that require special moldability such as loopability and thermal adhesion immediately after molding. Can be molded. Furthermore, it is possible to achieve both heat resistance and flexibility, and by using this composition, the problem of sagging even under load at high temperatures is greatly improved, and a three-dimensional reticular fiber aggregate that exhibits excellent cushioning properties is created. can be provided.

In addition, by exposing this three-dimensional reticulated fiber aggregate to a water-containing atmosphere, a crosslinking reaction between silanol groups is allowed to proceed, resulting in a crosslinked molded product of the three-dimensional reticulated fiber aggregate, that is, a crosslinked three-dimensional reticulated fiber. It can be an aggregate.

[Physical properties of silane cross-linked polypropylene]
The test pieces used for evaluating the physical properties of the silane-crosslinked polypropylene of the present invention listed below are specifically manufactured by the method described in the Examples section below.
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 80 mm, and a width of 10 mm.

The lower limit of the flexural modulus of the silane-crosslinked polypropylene of the present invention is preferably 30 MPa or more, more preferably 35 MPa or more, still more preferably 40 MPa or more. On the other hand, the upper limit of the flexural modulus of the silane-crosslinked polypropylene of the present invention is preferably 150 MPa or less, more preferably 120 MPa or less, still more preferably 90 MPa or less. When the flexural modulus is equal to or higher than the above lower limit, the resulting three-dimensional reticular fiber aggregate tends to have sufficient strength to withstand the load and is less prone to sagging. Furthermore, when the bending modulus is less than or equal to the above upper limit value, the resulting three-dimensional reticular fiber aggregate tends to have sufficient flexibility for use.

[Method for manufacturing crosslinked molded body]
The crosslinked molded article of the present invention includes a step of obtaining a silane-modified polypropylene obtained by silane-modifying a polypropylene composition containing the above-mentioned components (a) and (b), and a step of obtaining a silane-modified polypropylene containing the silane-modified polypropylene and a silanol condensation catalyst. It is obtained by a method for producing a crosslinked molded body, which includes the steps of obtaining a composition, molding the silane-modified polypropylene composition to obtain a molded body, and crosslinking the molded body to obtain a crosslinked molded body.

[Method for producing crosslinked molded product of three-dimensional reticular fiber aggregate]
The crosslinked molded product of the three-dimensional reticular fiber aggregate of the present invention is produced by a step of obtaining a silane-modified polypropylene by silane-modifying a polypropylene composition containing the above-mentioned component (a) and component (b), and a step of obtaining a silane-modified polypropylene by silanol condensation with the silane-modified polypropylene. a step of obtaining a silane-modified polypropylene composition containing a catalyst, a step of obtaining a three-dimensional network fiber aggregate by solidifying the strands obtained by extrusion molding the silane-modified polypropylene composition in a thermally fused state; It is obtained by a method for producing a crosslinked molded body of a three-dimensional reticular fiber aggregate, which comprises a step of crosslinking the three-dimensional reticular fiber aggregate to obtain a crosslinked molded body of the three-dimensional reticular fiber aggregate.

[Application]
The uses of the silane-modified polypropylene, silane-modified polypropylene composition, and silane-crosslinked polypropylene of the present invention are not particularly limited. For example, it can be suitably used as a cushioning material for furniture, bedding such as bed mats and pillows, and seats for vehicles such as vehicles and ships. In addition, when applied to these uses, it is preferable to use the above-mentioned three-dimensional network fiber aggregate. This three-dimensional network fiber aggregate can also be used as a laminate with other materials, if necessary. However, as described above, the shape of the molded product is not limited to the three-dimensional network fiber aggregate, and can be molded into a predetermined shape depending on the application.

EXAMPLES Hereinafter, the present invention will be specifically explained using examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. In addition, the values of various manufacturing conditions and evaluation results in the following examples have the meaning of preferable upper or lower limits in the embodiments of the present invention, and the preferable ranges are different from the above-mentioned upper or lower limits. , it may be a range defined by the values of the following examples or a combination of values of the examples.

[material]
The raw materials used in Examples and Comparative Examples are shown below.
[Polypropylene resin]
・a-1: Elmodu (registered trademark) S400 (manufactured by Idemitsu Kosan Co., Ltd., propylene homopolymer, MFR: 2600 g/10 minutes (230° C., 2.16 kg load), density: 0.87 g/cm ³ ), Melting point: 80°C was used.

・b-1: Tafmer (registered trademark) PN-2060 (manufactured by Mitsui Chemicals, Inc., propylene/ethylene/butene copolymer, propylene units: 84% by mass, α-olefin units: 16% by mass, MFR: 6g/ 10 minutes (230°C, 2.16kg load), density: 0.87g/cm ³ ), melting point: 162°C.

(Other polypropylene resins)
・PP-1: Novatec PP (registered trademark) MA3Q (manufactured by Nippon Polypro Co., Ltd., propylene homopolymer, MFR: 11 g/10 minutes (230°C, 2.16 kg load), density: 0.90 g, melting point: 160 °C was used.

・PP-2: Adflex (registered trademark) V109F (manufactured by Lyondell Basell, propylene/ethylene copolymer, propylene units: 93% by mass, α-olefin units: 7% by mass, MFR: 12g/10 minutes (230 ° C., 2.16 kg load), density: 0.88 g/cm ³ ), and melting point: 142°C.

・PP-3: Novatec (registered trademark) EG8B (manufactured by Nippon Polypro Co., Ltd., propylene/ethylene copolymer, propylene units: 97% by mass, α-olefin units: 3% by mass, MFR: 0.8 g/10 minutes (230°C, 2.16kg load), density: 0.90g/cm ³ ), and melting point: 143°C.

[Materials other than polypropylene]
・PE-1: Engage (registered trademark) 8100 (manufactured by Dow Chemical Company, ethylene-octene copolymer (mainly composed of ethylene units), MFR: 1 g / 10 minutes (190 ° C., 2.16 kg load), density :0.87g/cm ³ ) was used.

・PE-2: Engage (registered trademark) XLT8677 (manufactured by Dow Chemical Company, ethylene-octene copolymer (mainly composed of ethylene units), MFR: 0.5 g / 10 minutes (190 ° C., 2.16 kg load) , density: 0.87 g/cm ³ ) was used.

[Catalyst masterbatch (MB)]
・Catalyst MB: PZ010 (manufactured by Mitsubishi Chemical Corporation, homopolypropylene containing tin catalyst (dioctyltin dilaurate), MFR of homopolypropylene: 16 g/10 minutes (230°C, 2.16 kg load), linear low-density polyethylene Density: 0.90 g/cm ³ ) was used.

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

[Measurement of polypropylene and silane-modified polypropylene]
[Melting point]
Using a differential scanning calorimeter, trade name "DSC6220" manufactured by Hitachi High-Tech Science Co., Ltd., approximately 5 mg of sample was heated from 20 to 200 °C at a heating rate of 100 °C/min in accordance with JIS K7121 (2010). After holding at 200°C for 3 minutes, the temperature was lowered to -10°C at a cooling rate of 10°C/min, and then the temperature was raised to 200°C at a heating rate of 10°C/min. The extrapolated peak was obtained from the thermogram measured. The end point (°C) was calculated and taken as the melting point. Note that the melting point is an index of heat resistance.

[Melt flow rate (MFR)]
It was measured at 230° C. and a load of 2.16 kg in accordance with JIS K7210 (1999). Note that MFR is an index of moldability.

[density]
Measurements were made in accordance with JIS K7112 (1999) using a 2 mm thick sheet-like test piece obtained by press-molding silane-modified polypropylene. Note that the density is an index of moldability.

[Half crystallization time]
Approximately 5 mg of the sample was heated from 30°C to 230°C at a heating rate of 100°C/min in a nitrogen atmosphere using a differential scanning calorimeter manufactured by Hitachi High-Tech Co., Ltd., trade name "DSC7000X". After holding for 10 minutes, the temperature was lowered to 125°C at a cooling rate of 100°C/min, and then held at 125°C for 40 minutes. Using the thermogram measured, the half crystallization time (min.) was calculated from the time to reach 50% enthalpy. was calculated. A larger value indicates higher crystallization retardation. Note that the half crystallization time is an index of crystallization retardation.

[Evaluation of silane crosslinked polypropylene]
[Bending elastic modulus]
The measurement was performed using an injection molded test piece having a thickness of 4 mm, a length of 80 mm, and a width of 10 mm in accordance with JIS K7171 (2008). Note that the flexural modulus is an index of flexibility.

[Example 1]
20 parts by mass of a-1, 60 parts by mass of b-1, 20 parts by mass of other PP-1, 1.0 parts by mass of vinyltrimethoxysilane (VTMOS), which is an unsaturated silane compound as alkoxysilane, and radical generation. 0.01 parts by mass of dicumyl peroxide, which is an organic peroxide, was stirred in a blender. After that, the strands were put into a single screw extruder (manufactured by IKG, PMS50) set at a temperature of 200°C, and the strands that came out of the nozzle were cooled and solidified in a water tank, and then cut into pellets. , silane-modified polypropylene was obtained. The melting point, half crystallization time, MFR, and density of the obtained silane-modified polypropylene were measured according to the measurement and evaluation methods described above. The results are shown in Table 1.

To 100 parts by mass of the silane-modified polypropylene obtained above, 5 parts by mass of PZ010 was added as catalyst MB to obtain a silane-modified polypropylene composition. This was put into an injection molding machine and molded into a sheet with a thickness of 4 mm or 2 mm at 200°C. This sheet-like molded product was left in a constant temperature and humidity chamber at 85° C. and 85% RH for 16 hours to obtain a sheet-like molded product made of silane-crosslinked polypropylene. Using the obtained sheet-like molded body, the flexural modulus was measured according to the measurement and evaluation method described above. The results are shown in Table 1.

[Comparative Examples 1 to 3]
Sheet-like molded bodies made of silane-modified polypropylene and silane-crosslinked polypropylene of Comparative Examples 1 to 3 were produced in the same manner as in Example 1, except that the raw material composition was as shown in Table 1, and evaluation measurements were performed. The results are shown in Table 1.

The above results reveal the following.
The silane-modified polypropylene of Example 1 had excellent heat resistance. In addition, the silane-crosslinked polypropylene using the silane-modified polypropylene of Example 1 has a bending elastic modulus, which is an index of flexibility, which indicates sufficient flexibility to be used as a crosslinked molded product of a three-dimensional network fiber aggregate. there were. Furthermore, since the MFR and density are appropriate, the moldability into a three-dimensional reticular fiber aggregate is good, and excellent cushioning properties can be expected. Furthermore, since it has an excellent half-crystallization time, which is an index of crystallization retardation, it can be expected to have excellent heat-resistant fusion properties.

The silane-modified polypropylene of Comparative Example 1 and the silane-modified polypropylene of Comparative Example 2 had excellent heat resistance but poor flexibility. In addition, although the MFR and density are suitable in terms of formability into a three-dimensional network fiber aggregate, the half crystallization time is inferior, and the silane-modified polypropylene of Comparative Example 1 and the silane-modified polypropylene of Comparative Example 2 It is thought that the heat fusion resistance of silane crosslinked polypropylene using modified polypropylene is inferior.
The silane-modified polypropylene of Comparative Example 3 had low heat resistance and did not have sufficient flexibility. Furthermore, it is thought that the MFR is low and the strand diameter becomes thick when molding a three-dimensional reticular fiber aggregate, making it impossible to obtain a molded product with a good appearance.

From the above, it was shown that the silane-modified polypropylene of the present invention has excellent heat resistance, crystallization retardation, and moldability, and the silane-crosslinked polypropylene obtained by crosslinking this silane-modified polypropylene has excellent flexibility. It is also believed that the silane-crosslinked polypropylene obtained by crosslinking this silane-modified polypropylene has excellent heat-resistant fusion bonding properties for molded articles, especially for three-dimensional network fiber aggregates.

The silane-modified polypropylene of the present invention has excellent heat resistance and crystallization retardation during mattress molding, so it has high heat-resistant fusion properties even under high-temperature conditions, and is used in long-term high-temperature environments such as disinfection and sterilization of medical and nursing care mattresses. It is possible to provide silane crosslinked polypropylene with excellent heat deformation resistance and shape recovery properties, which can also be used in For this reason, the silane-modified polypropylene and silane-modified polypropylene composition of the present invention, as well as molded products, crosslinked molded products, and three-dimensional reticulated fiber aggregates using the same, are suitable for use in furniture, bed mats, bedding such as pillows, etc. ; It can be widely and effectively used as a constituent material of cushioning materials for vehicles, marine seats, etc.

Claims (12)

A silane-modified polypropylene obtained by silane-modifying a polypropylene composition containing polypropylene,
The polypropylene composition is a propylene homopolymer (a) having a melting point of 50°C or more and less than 130°C;
A propylene-based copolymer (b) having a melting point of 130° C. or more and 180° C. or less and containing 51 to 92% by mass of propylene units and 8 to 49% by mass of ethylene units and/or α-olefin units,
A silane-modified polypropylene in which the content of component (a) is 5 to 50% by mass and the content of component (b) is 50 to 95% by mass based on 100% by mass of the polypropylene composition. The silane-modified polypropylene according to claim 1, wherein the silane-modified site 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, R' is 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 R' is One is an alkoxy group having 1 to 10 carbon atoms.) The silane-modified polypropylene according to claim 1 or 2, having a half crystallization time of 30 minutes or more as measured by differential scanning calorimetry (DSC). According to any one of claims 1 to 3, the melt flow rate (MFR, measured according to JIS K7210 (1999) at a temperature of 230°C and a load of 2.16 kg) is 25 to 100 g/10 minutes. of silane-modified polypropylene. A silane-modified polypropylene composition comprising the silane-modified polypropylene according to any one of claims 1 to 4 and a silanol condensation catalyst. A molded article obtained by molding the silane-modified polypropylene composition according to claim 5. A crosslinked molded article obtained by crosslinking the molded article according to claim 6. A three-dimensional network fiber aggregate formed by molding the silane-modified polypropylene composition according to claim 5. A crosslinked molded product of a three-dimensional reticulated fiber aggregate obtained by crosslinking the three-dimensional reticulated fiber aggregate according to claim 8. A silane-crosslinked polypropylene obtained by crosslinking the silane-modified polypropylene composition according to claim 5,
The melting point of the silane-modified polypropylene is 150°C or more and 180°C or less,
Silane-crosslinked polypropylene whose flexural modulus is 150 MPa or less as measured in accordance with JIS K 7171 (2008). A crosslinked molded article of a three-dimensional network fiber aggregate made of the silane crosslinked polypropylene according to claim 10. A silane-crosslinked polypropylene obtained by crosslinking the silane-modified polypropylene composition according to claim 5.