JP7737870B2 - Vehicle wiring harness connector - Google Patents

Description

The present invention relates to a connector for a vehicle wire harness and a propylene-based resin composition.

Molded articles made from propylene-based resin compositions are widely used in a variety of fields where lightweight construction is required, such as vehicle and machine parts.

In recent years, the electrification of vehicles has been progressing, for example, from the perspective of reducing carbon dioxide emissions. Furthermore, the addition of functions and the use of electronics to improve automobile safety, comfort, and driving performance are also progressing.

Under these circumstances, the importance of wire harnesses, which transmit power from batteries and signals from information and communication devices, is increasing, and there is a demand for more stable transmission of power and signals. In addition, the number of wire harness connectors installed in each vehicle is also increasing.

For example, Patent Document 1 below discloses a connector for automobiles that contains polybutylene terephthalate resin and polyolefin resin.

Japanese Patent Application Publication No. 6-295761

For example, in order to reduce carbon dioxide emissions from automobiles and improve fuel efficiency, there is a demand for even lighter wire harness connectors. This has led to a desire to develop vehicle wire harness connectors that are primarily made of propylene polymers. However, vehicle wire harness connectors are required to have terminals that are inserted into the connector and firmly retained in place. In other words, vehicle wire harness connectors are required to be both lightweight and rigid (high flexural modulus).

The inventors conducted extensive research to solve the above problems and discovered that the above problems could be solved by using certain ingredients, leading to the completion of the present invention.

That is, the present invention provides the following [1] to [8].
[1] A propylene-based resin composition containing a propylene-based polymer having a weight average molecular weight of 500,000 to 1,000,000 in terms of polystyrene, determined by a GPC method, and a molecular weight distribution (weight average molecular weight/number average molecular weight) of 6 to 10,
A connector for a vehicle wire harness having one or more insertion portions and one or more lance portions provided so as to protrude from a wall surface defining the insertion portions, wherein the thickness of the lance portions is 1 mm or less.
[2] The melt flow rate of the propylene polymer measured under conditions of a temperature of 230°C and a load of 2.16 kgf is 0.1 to 15 g/10 min,
The connector for a vehicle wire harness according to [1], wherein the propylene-based polymer has an intrinsic viscosity of 1.5 dL/g or more.
[3] The connector for a vehicle wire harness according to [1] or [2], wherein the propylene-based resin composition further contains a nucleating agent and a hydrazide compound represented by the following formula (1):
(In the formula (1), _R1 and _R2 each independently represent an alkyl group having 1 to 8 carbon atoms.)
[4] The connector for a vehicle wire harness according to [3], wherein in the formula (1), R ₁ and R ₂ are tert-butyl groups.
[5] The connector for a vehicle wire harness according to [3] or [4], wherein the nucleating agent contains a compound represented by the following formula (C-1) or a compound represented by the following formula (C-2):
[6] The propylene-based polymer comprises a first propylene polymer component and a second propylene polymer component,
the first propylene polymer component has an intrinsic viscosity of 5 to 8 dL/g;
The connector for a vehicle wire harness according to any one of [1] to [5], wherein the second propylene polymer component has an intrinsic viscosity of 0.5 to 2 dL/g.
[7] A ratio of the first propylene polymer component to the entire propylene-based polymer is 10% by mass or more and 20% by mass or less,
The connector for a vehicle wire harness according to [6], wherein the second propylene polymer component accounts for 80% by mass or more and 90% by mass or less of the entire propylene-based polymer.
[8] A propylene polymer having a melt flow rate of 0.1 to 15 g/10 min and an intrinsic viscosity of 1.5 dL/g or more, measured under conditions of a temperature of 230°C and a load of 2.16 kgf;
A nucleating agent;
A propylene-based resin composition comprising a hydrazide compound represented by the following formula (1):
(In the formula (1), _R1 and _R2 each independently represent an alkyl group having 1 to 8 carbon atoms.)

The present invention provides a connector for a vehicle wire harness that contains a propylene-based polymer (propylene-based resin composition) that can achieve both lightweight and rigidity (high flexural modulus).

FIG. 1 is a diagram illustrating a configuration example of a connector of a vehicle wire harness. FIG. 2 is a diagram showing a cut end surface of the connector of the vehicle wire harness taken along the dashed line AA shown in FIG.

The following provides a detailed description of embodiments of the present invention. The present invention is not limited to the specific embodiments shown below. Note that the drawings merely show the shape, size, and arrangement of the components in a schematic manner to enable understanding of the invention, and each component may be modified as appropriate without departing from the spirit of the present invention.

1. Explanation of Terms Before describing the embodiments of the present invention, commonly used terms will be explained.

In this specification, the term "monomer unit" refers to a structural unit (residue) derived from a monomer contained in a polymer obtained by polymerizing a monomer.

As used herein, "α-olefin" refers to an olefin containing a carbon atom chain of three or more carbon atoms with a terminal (α-position) carbon-carbon double bond.

In this specification, the "intrinsic viscosity (unit: dL/g)" is a value measured at a temperature of 135°C using tetralin as a solvent by the following method.
Specifically, the intrinsic viscosity can be determined by an "extrapolation method" in which reduced viscosities are measured at a plurality of concentrations using an Ubbelohde viscometer, the reduced viscosities are plotted against the concentrations, and the concentrations are extrapolated to zero. More specifically, the intrinsic viscosity can be determined by the method described on page 491 of "Polymer Solutions, Polymer Experiments 11" (published by Kyoritsu Shuppan Co., Ltd. in 1982), in which reduced viscosities are measured at three concentrations of 0.1 g/dL, 0.2 g/dL, and 0.5 g/dL, the reduced viscosities are plotted against the concentrations, and the concentrations are extrapolated to zero.

In this specification, "melt flow rate (MFR)" means "melt mass flow rate" and is the melt flow rate measured in accordance with JIS K7210-1:2014 and K7210-2:2014 under conditions of a temperature of 230°C and a load of 2.16 kgf.

In this specification, unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass."

2. Propylene-Based Resin Composition The propylene-based resin composition according to an embodiment of the present invention contains a propylene-based polymer having a weight-average molecular weight of 500,000 to 1,000,000 in terms of polystyrene, as determined by a GPC method, and a molecular weight distribution (weight-average molecular weight/number-average molecular weight) of 6 to 10.

The components that can be contained in the propylene-based resin composition of this embodiment are described below.

(1) Component (A) Propylene-Based Polymer A propylene-based polymer is a polymer containing propylene units in an amount of more than 50% by mass relative to all constituent units (100% by mass). The propylene units in a propylene-based polymer are usually 100% by mass or less.

Examples of propylene-based polymers include propylene homopolymers and copolymers of propylene with other monomers that can copolymerize with propylene. The copolymers may be random copolymers or block copolymers.

Examples of other monomers that can be copolymerized with propylene include olefins other than propylene (e.g., ethylene, olefins having 4 or more carbon atoms).

Olefins with 4 or more carbon atoms may be linear or branched olefins. Olefins with 4 or more carbon atoms may also be olefins with a cyclic structure, such as α-olefins with a cyclic structure such as vinylcyclopropane and vinylcyclobutane.

Examples of olefins other than propylene that can be copolymerized with propylene include α-olefins other than propylene (e.g., ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, and 1-decene). Preferred olefins other than propylene that can be copolymerized with propylene are ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, and 1-decene, and more preferably ethylene, propylene, 1-butene, 1-hexene, and 1-octene.

The propylene-based resin composition of this embodiment may contain two or more types of component (A) propylene-based polymers as component (A).

The propylene-based resin composition of this embodiment may contain, as component (A) the propylene-based polymer, component (A-1) a propylene homopolymer in which only one type of propylene monomer is polymerized, or may contain a propylene-based polymer in which two or more types of monomers are polymerized in any combination and ratio.

Examples of component (A) propylene-based polymers include component (A-1) propylene homopolymers and random copolymers of propylene with other monomers copolymerizable therewith (hereinafter also referred to as propylene-based random copolymers).

When two or more propylene polymers are contained as component (A), examples of combinations of two or more propylene polymers include a combination of two or more propylene homopolymers differing in weight average molecular weight, etc., and a combination of polymer (I) and polymer (II) shown below.

The propylene-based resin composition of this embodiment may contain component (A-2) a heterophasic propylene polymer material as component (A) the propylene-based polymer.

Here, component (A-2) heterophasic propylene polymer material refers to a material containing two or more types of propylene polymers, in which the two or more types of propylene polymers are not compatible with each other and form separate phases.

Examples of component (A-2) heterophasic propylene polymer materials include the combination of polymer (I) and polymer (II) below.

Here, polymer (I) is a polymer having more than 80% by mass and not more than 100% by mass of propylene units relative to the amount of all constituent units.

Polymer (II) is a copolymer of propylene units and at least one monomer unit selected from the group consisting of ethylene units and α-olefin units having 4 or more carbon atoms. Polymer (II) is preferably a polymer containing propylene units in an amount of more than 0% by mass and not more than 90% by mass, and more preferably a polymer containing propylene units in an amount of more than 0% by mass and not more than 80% by mass, based on the amount of all structural units.

Polymer (I) may be a propylene homopolymer or a copolymer of propylene and another monomer. Polymer (I) and polymer (II) may each consist of only one type of polymer, or may contain two or more types of polymers.

From the viewpoint of improving the rigidity and impact resistance of molded articles obtained by molding the propylene-based resin composition, it is preferable that the propylene-based polymer contains one or more materials selected from the group consisting of propylene homopolymers and heterophasic propylene polymer materials.

From the viewpoint of improving the rigidity of a molded article obtained by molding the propylene-based resin composition, the propylene-based polymer preferably has an isotactic pentad fraction (also referred to as [mmmm] fraction) measured by ^13C -NMR of 0.97 or more, more preferably 0.98 or more. The closer the isotactic pentad fraction of the propylene-based polymer is to 1, the higher the stereoregularity of the molecular structure of the propylene-based polymer and the higher the crystallinity of the propylene-based polymer. When the propylene-based polymer is a copolymer, the isotactic pentad fraction can be measured for the chain of propylene units in the copolymer.

From the viewpoint of improving the processability of the propylene resin composition during molding, the melt flow rate (MFR) of component (A) propylene polymer, measured at a temperature of 230°C and a load of 2.16 kgf, is preferably 0.1 g/10 min or more, more preferably 3 g/10 min or more, preferably 500 g/10 min or less, more preferably 100 g/10 min or less, even more preferably 15 g/10 min, and preferably 0.1 g/10 min to 15 g/10 min.

Component (A) propylene polymer can be produced, for example, by the following polymerization method using a polymerization catalyst.

Examples of polymerization catalysts include Ziegler-type catalyst systems; Ziegler-Natta-type catalyst systems; catalyst systems containing a Group 4 transition metal compound having a cyclopentadienyl ring and an alkylaluminoxane; catalyst systems containing a Group 4 transition metal compound having a cyclopentadienyl ring, a compound that reacts with the metal compound to form an ionic complex, and an organoaluminum compound; and catalyst systems in which catalyst components (e.g., a Group 4 transition metal compound having a cyclopentadienyl ring, a compound that forms an ionic complex, an organoaluminum compound, etc.) are supported and modified on inorganic particles (e.g., silica, clay minerals, etc.). Prepolymerization catalysts prepared by prepolymerizing monomers such as ethylene or α-olefins in the presence of such catalyst systems may also be used. An example of a Ziegler-Natta-type catalyst system is a catalyst system that uses a combination of a titanium-containing solid transition metal component and an organometallic component.

Examples of such catalyst systems include those described in JP-A-61-218606, JP-A-5-194685, JP-A-7-216017, JP-A-9-316147, JP-A-10-212319, and JP-A-2004-182981.

Examples of polymerization methods include bulk polymerization, solution polymerization, and gas-phase polymerization. Here, bulk polymerization refers to a method in which polymerization is carried out using a liquid olefin as the medium at the polymerization temperature. Solution polymerization refers to a method in which polymerization is carried out in an inert hydrocarbon solvent such as propane, butane, isobutane, pentane, hexane, heptane, or octane. Gas-phase polymerization refers to a method in which gaseous monomers are used as the medium and the gaseous monomers are polymerized in that medium.

Examples of polymerization methods for carrying out the polymerization method include batch polymerization, continuous polymerization, and combinations thereof. The polymerization method may also be a multi-stage method using multiple polymerization reactors connected in series.

The various conditions used in the polymerization method (polymerization temperature, polymerization pressure, monomer concentration, catalyst input amount, polymerization time, etc.) can be determined appropriately depending on the desired propylene-based polymer.

In the production of a propylene-based polymer, the resulting propylene-based polymer may be maintained at a temperature at which impurities such as residual solvent and oligomers can volatilize, but lower than the temperature at which the propylene-based polymer melts, to remove residual solvent contained in the resulting propylene-based polymer and ultra-low molecular weight oligomers produced as by-products during production. Examples of methods for removing impurities such as residual solvent and oligomers include the methods described in JP-A-55-75410 and JP-A-2565753.

From the viewpoint of improving the fluidity of the propylene-based resin composition when melted and the toughness of the molded article obtained by molding the propylene-based resin composition, the intrinsic viscosity [η] of component (A-1) propylene homopolymer is preferably 0.1 to 5 dL/g, more preferably 0.5 to 5 dL/g, and even more preferably 0.7 to 4 dL/g.

Furthermore, from the viewpoint of improving the fluidity of the propylene-based resin composition when melted and the toughness of molded articles containing the resin composition, the molecular weight distribution Mw/Mn of the propylene homopolymer is preferably 2 or more and less than 10, more preferably 3 to 8, and even more preferably 3 to 7. Here, Mw represents the weight-average molecular weight, and Mn represents the number-average molecular weight. The molecular weight distribution can be measured by gel permeation chromatography (GPC).

Examples of propylene-based random copolymers include a random copolymer containing propylene units and ethylene units (hereinafter also referred to as random polymer (1)); a random copolymer containing propylene units and α-olefin units having 4 or more carbon atoms (hereinafter also referred to as random polymer (2)); and a random copolymer containing propylene units, ethylene units, and α-olefin units having 4 or more carbon atoms (hereinafter also referred to as random polymer (3)).

The α-olefins having 4 or more carbon atoms that can constitute the propylene-based random copolymer are preferably α-olefins having 4 to 10 carbon atoms. Examples of α-olefins having 4 to 10 carbon atoms include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, and 1-decene, with 1-butene, 1-hexene, and 1-octene being preferred.

Examples of random copolymers (2) include propylene-1-butene random copolymers, propylene-1-hexene random copolymers, propylene-1-octene random copolymers, and propylene-1-decene random copolymers.

Examples of random copolymers (3) include propylene-ethylene-1-butene copolymer, propylene-ethylene-1-hexene copolymer, propylene-ethylene-1-octene copolymer, and propylene-ethylene-1-decene copolymer.

The content of ethylene units in random copolymer (1) is preferably 0.1 to 40% by mass.

The content of α-olefin units having 4 or more carbon atoms in the random copolymer (2) is preferably 0.1 to 40% by mass, more preferably 0.1 to 30% by mass, and even more preferably 2 to 15% by mass.

The total content of ethylene units and α-olefin units having 4 or more carbon atoms in the random copolymer (3) is preferably 0.1 to 40% by mass, more preferably 0.1 to 30% by mass, and even more preferably 2 to 15% by mass.

The propylene unit content in each of these random copolymers (1) to (3) is preferably 60 to 99.9% by mass.

As already explained, polymer (I) in component (A-2) the heterophasic propylene polymer material is a polymer containing more than 80% by mass and no more than 100% by mass of propylene units relative to the amount of all constituent units. The total content of monomer units other than propylene units in polymer (I), when the mass of polymer (I) is taken as 100% by mass, is typically no less than 0% by mass and no more than 20% by mass, and may be 0% by mass or no less than 0.01% by mass.

Examples of monomer units other than propylene units that may be contained in polymer (I) include ethylene units and α-olefin units having 4 or more carbon atoms.

The α-olefins having 4 or more carbon atoms that can constitute polymer (I) are preferably α-olefins having 4 to 10 carbon atoms, more preferably 1-butene, 1-hexene, and 1-octene, and even more preferably 1-butene.

Examples of polymer (I) include propylene homopolymer, propylene-ethylene copolymer, propylene-1-butene copolymer, propylene-1-hexene copolymer, propylene-1-octene copolymer, propylene-ethylene-1-butene copolymer, propylene-ethylene-1-hexene copolymer, and propylene-ethylene-1-octene copolymer.

Among these, propylene homopolymer, propylene-ethylene copolymer, propylene-1-butene copolymer, and propylene-ethylene-1-butene copolymer are preferred as polymer (I), and propylene homopolymer is more preferred from the viewpoint of improving the rigidity of the molded article obtained by molding the propylene-based resin composition.

As already explained, polymer (II) is a copolymer of propylene units and at least one monomer unit selected from the group consisting of ethylene units and α-olefin units having 4 or more carbon atoms.

The total content of ethylene units and α-olefin units having 4 or more carbon atoms in polymer (II) is preferably 20 to 80% by mass, and more preferably 20 to 60% by mass, when the mass of polymer (II) is taken as 100% by mass.

The α-olefin having 4 or more carbon atoms that can constitute polymer (II) is preferably an α-olefin having 4 to 10 carbon atoms, and examples thereof include the same α-olefins that can constitute polymer (I) as already described.

Examples of polymer (II) include propylene-ethylene copolymer, propylene-ethylene-1-butene copolymer, propylene-ethylene-1-hexene copolymer, propylene-ethylene-1-octene copolymer, propylene-ethylene-1-decene copolymer, propylene-1-butene copolymer, propylene-1-hexene copolymer, propylene-1-octene copolymer, and propylene-1-decene copolymer. Polymer (II) is preferably a propylene-ethylene copolymer, a propylene-1-butene copolymer, or a propylene-ethylene-1-butene copolymer, and more preferably a propylene-ethylene copolymer.

The content of polymer (II) in component (A-2) heterophasic propylene polymer material is preferably 1 to 50% by mass, more preferably 1 to 45% by mass, even more preferably 5 to 40% by mass, and particularly preferably 8 to 32% by mass, when the total mass of polymer (I) and polymer (II) is taken as 100% by mass.

Examples of the heterophasic propylene polymer material for component (A-2) include a polymer (I) that is a propylene homopolymer, a combination of a propylene homopolymer and a (propylene-ethylene) copolymer, a combination of a propylene homopolymer and a (propylene-ethylene-1-butene) copolymer, a combination of a propylene homopolymer and a (propylene-ethylene-1-hexene) copolymer, a combination of a propylene homopolymer and a (propylene-ethylene-1-octene) copolymer, a combination of a propylene homopolymer and a (propylene-1-butene) copolymer, a combination of a propylene homopolymer and a (propylene-1-hexene) copolymer, a combination of a propylene homopolymer and a (propylene-1-octene) copolymer, and a combination of a propylene homopolymer and a (propylene-1-decene) copolymer.

The heterophasic propylene polymer material may also be a combination in which polymer (I) is a polymer containing propylene units and monomer units other than propylene units. Listing the type of polymer (I) first and the type of polymer (II) second, specific examples of such heterophasic propylene polymer materials include a combination of a (propylene-ethylene) copolymer and a (propylene-ethylene) copolymer, a combination of a (propylene-ethylene) copolymer and a (propylene-ethylene-1-butene) copolymer, a combination of a (propylene-ethylene) copolymer and a (propylene-ethylene-1-hexene) copolymer, a combination of a (propylene-ethylene) copolymer and a (propylene-ethylene-1-octene) copolymer, and a combination of a (propylene-ethylene) copolymer and a (propylene-ethylene) copolymer. a combination of a (propylene-ethylene) copolymer and a (propylene-1-decene) copolymer, a combination of a (propylene-ethylene) copolymer and a (propylene-1-butene) copolymer, a combination of a (propylene-ethylene) copolymer and a (propylene-1-hexene) copolymer, a combination of a (propylene-ethylene) copolymer and a (propylene-1-octene) copolymer, a combination of a (propylene-ethylene) copolymer and a (propylene-1-decene) copolymer, a combination of a (propylene-1-butene) copolymer and a (propylene-ethylene) copolymer, a combination of a (propylene-1-butene) copolymer and a (propylene-ethylene-1-butene) copolymer a combination of a (propylene-1-butene) copolymer and a (propylene-ethylene-1-hexene) copolymer, a combination of a (propylene-1-butene) copolymer and a (propylene-ethylene-1-octene) copolymer, a combination of a (propylene-1-butene) copolymer and a (propylene-ethylene-1-decene) copolymer, a combination of a (propylene-1-butene) copolymer and a (propylene-1-butene) copolymer, a combination of a (propylene-1-butene) copolymer and a (propylene-1-hexene) copolymer, a combination of a (propylene-1-butene) copolymer and a (propylene-1-octene) copolymer Examples of such copolymers include a combination of a (propylene-1-butene) copolymer and a (propylene-1-decene) copolymer, a combination of a (propylene-1-hexene) copolymer and a (propylene-1-hexene) copolymer, a combination of a (propylene-1-hexene) copolymer and a (propylene-1-octene) copolymer, a combination of a (propylene-1-hexene) copolymer and a (propylene-1-decene) copolymer, a combination of a (propylene-1-octene) copolymer and a (propylene-1-octene) copolymer, and a combination of a (propylene-1-octene) copolymer and a (propylene-1-decene) copolymer.

Preferred examples of the heterophasic propylene polymer material (A-2) that can be included in the propylene-based resin composition of this embodiment include a combination of a propylene homopolymer and a (propylene-ethylene) copolymer, a combination of a propylene homopolymer and a (propylene-ethylene-1-butene) copolymer, a combination of a (propylene-ethylene) copolymer and a (propylene-ethylene) copolymer, a combination of a (propylene-ethylene) copolymer and a (propylene-ethylene-1-butene) copolymer, and a combination of a (propylene-1-butene) copolymer and a (propylene-1-butene) copolymer, with a combination of a propylene homopolymer and a (propylene-ethylene) copolymer being more preferable.

Heterophagic propylene polymer materials can be produced by multi-stage polymerization, which includes a first polymerization step to produce polymer (I) and a second polymerization step to produce polymer (II) in the presence of polymer (I) produced in the first step. The polymerization can be carried out using a catalyst system exemplified above as a catalyst that can be used in the production of propylene-based polymers.

The intrinsic viscosity of the propylene polymer (A) of this embodiment is typically less than 3 dL/g, 1 dL/g or more, preferably 1.5 dL/g or more, more preferably 1 dL/g or more but less than 3 dL/g, and even more preferably 1.5 dL/g or more but less than 3 dL/g, from the viewpoints of improving the fluidity and processability of the propylene resin composition, suppressing discoloration of the molded article, and achieving both rigidity and copper damage prevention performance.

In this embodiment, the polystyrene-equivalent weight average molecular weight of the propylene polymer (A) is typically 100,000 to 1,000,000, and preferably 500,000 to 1,000,000, from the viewpoint of improving the appearance and elongation properties of the molded article.

From the standpoint of moldability and mechanical properties, the molecular weight distribution (Mw/Mn) of component (A) propylene polymer is typically 10 or less, and preferably 3 to 10.

Here, Mw represents the weight-average molecular weight, and Mn represents the number-average molecular weight. The weight-average molecular weight, number-average molecular weight, and molecular weight distribution can be measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene.

When the propylene-based polymer is a polymer material composed of polymer (I) and polymer (II) formed by multi-stage polymerization, a portion of polymer (I) prepared in the first polymerization stage is extracted from the polymerization reactor and its intrinsic viscosity is determined, and the intrinsic viscosity of the propylene-based polymer finally obtained by multi-stage polymerization (hereinafter referred to as ([η] Total)) is determined. The intrinsic viscosity of the polymer formed in the second polymerization stage can be calculated using these intrinsic viscosity values and the content of each polymer.

Furthermore, when a polymer material consisting of polymer (I) and polymer (II) is produced by a method in which polymer (I) is obtained in an earlier polymerization step and polymer (II) is obtained in a later polymerization step, the procedures for measuring and calculating the content and intrinsic viscosity numbers ([η] Total, [η] I, [η] II) of each of polymer (I) and polymer (II) are as follows:

The intrinsic viscosity [η]II of polymer (II) can be calculated using the following formula from the intrinsic viscosity ([η]I) of polymer (I) obtained in the previous polymerization step, the intrinsic viscosity ([η]Total) of the final polymer after the subsequent polymerization step (i.e., a polymer composed of polymer (I) and polymer (II)) measured using the method described above, and the content of polymer (II) contained in the final polymer.

[η]II=([η]Total-[η]I×XI)/XII
[η] Total: intrinsic viscosity of the final polymer (unit: dL/g)
[η]I: Intrinsic viscosity of polymer (I) (unit: dL/g)
XI: mass ratio of polymer (I) to the final polymer. XII: mass ratio of polymer (II) to the final polymer. XI and XII can be determined from the mass balance during polymerization.

The intrinsic viscosity (hereinafter referred to as [η]I) of polymer (I) is preferably 1 to 10 dL/g, more preferably 2 to 10 dL/g, and even more preferably 5 to 8 dL/g.

The intrinsic viscosity of polymer (II) (hereinafter referred to as [η]II) is preferably 0.1 to 5 dL/g, more preferably 0.5 to 5 dL/g, and even more preferably 0.5 to 2 dL/g.

Furthermore, the ratio of [η]II to [η]I ([η]II/[η]I) is preferably 0.01 to 5, more preferably 0.05 to 2.5, and even more preferably 0.06 to 0.4.

The mass ratio XII of polymer (II) to the final polymer may be calculated from the following formula using the heat of crystalline fusion of polymer (I) and the final polymer, respectively.
XII=1-(ΔHf)T/(ΔHf)P
(ΔHf)T: Heat of fusion of the final polymer (polymer (I) and polymer (II)) (unit: cal/g)
(ΔHf)P: heat of fusion of polymer (I) (unit: cal/g)

Furthermore, the molecular weight distribution (Mw/Mn) of polymer (I) measured by GPC is preferably 1 or more and less than 10, more preferably 2 or more and less than 7, and even more preferably 3 or more and less than 5.

The content of the propylene polymer in the propylene resin composition of this embodiment is preferably 50% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, when the total amount of the propylene resin composition is taken as 100% by mass.

Here, particularly preferred examples of the structure of component (A) propylene-based polymer according to this embodiment will be described.

A particularly suitable propylene polymer component (A) in this embodiment is composed of a first propylene polymer component (a) and a second propylene polymer component (b) that has a different molecular weight than the first propylene polymer component (a).

Here, the first propylene polymer component (a) is preferably an isotactic propylene polymer. As the first propylene polymer component (a), a propylene homopolymer or a copolymer of propylene with ethylene or an α-olefin having 4 to 12 carbon atoms to the extent that crystallinity is not lost is particularly preferred. Examples of α-olefins include 1-butene, 4-methylpentene-1, 1-octene, and 1-hexene.

The content of monomers other than propylene is preferably 10% by mass or less if the monomer is ethylene, and preferably 30% by mass or less if the monomer is an α-olefin.

The first propylene polymer component (a) is preferably a crystalline propylene-based copolymer component selected from a propylene homopolymer, a random copolymer of propylene and 10% by mass or less of ethylene, a random copolymer of propylene and 30% by mass or less of an α-olefin having 4 to 12 carbon atoms, or a ternary random copolymer of propylene, 10% by mass or less of ethylene, and 30% by mass or less of an α-olefin having 4 to 12 carbon atoms. An even more preferred α-olefin is 1-butene. A particularly preferred first propylene polymer component (a) in terms of flexibility is a copolymer containing 1% by mass or more and 10% by mass or less of ethylene.

From the viewpoint of the melt strength of the propylene polymer, the intrinsic viscosity of the first propylene polymer component (a) is preferably 1 to 10 dL/g, more preferably 2 to 10 dL/g, and even more preferably 5 to 8 dL/g.

From the viewpoint of ensuring melt strength, fluidity, and elongation properties, the proportion of the first propylene polymer component (a) in the entire component (A) propylene polymer is typically 0.05% by mass or more and less than 25% by mass, preferably 0.3% by mass or more and less than 20% by mass, and more preferably 10% by mass or more and 20% by mass or less of the entire component (A) propylene polymer.

From the viewpoint of improving the melt strength, fluidity during melting, and rigidity, it is preferable that the amount of the first propylene polymer component (a) satisfies the following formula: When the amount of the first propylene polymer component (a) satisfies this formula, the melt strength, fluidity during melting, and rigidity of the molded article can be effectively improved.
Content (mass%) of first propylene polymer component (a) ≧400×EXP(−0.6×intrinsic viscosity (dL/g) of first propylene polymer component (a))

In the above formula (1), EXP(X) represents eX, and e represents the base of the natural logarithm.

In particular, from the viewpoint of the flowability of the propylene-based resin composition, it is preferable that the content of the first propylene polymer component (a) be as small as possible, provided that the requirements defined by the above formula are satisfied.

In this embodiment, the second propylene polymer component (b) is preferably a propylene-based polymer obtained by further continuous preparation following the preparation of the first propylene polymer component (a).

In other words, in the propylene polymer component (A) of this embodiment, simply blending a crystalline propylene polymer having an intrinsic viscosity of 5 dL/g or more with a propylene polymer having an intrinsic viscosity of less than 3 dL/g may not produce effects related to melt strength or may produce insufficient effects. Therefore, the second propylene polymer component (b) is preferably prepared by first preparing the first propylene polymer component (a) by polymerizing a propylene-based monomer in the presence of a stereoregular olefin polymerization catalyst, such as a Ziegler-Natta catalyst, and then subsequently polymerizing a propylene-based monomer in a different polymerization reaction vessel in the presence of the stereoregular olefin polymerization catalyst and the prepared first propylene polymer component (a).

From the viewpoint of ensuring melt strength, fluidity, and elongation properties, the proportion of the second propylene polymer component (b) in the entire propylene polymer component (A) is typically 75% by mass or more and less than 99.95% by mass, preferably 75% by mass or more and less than 99.7% by mass, and more preferably 80% by mass or more and 90% by mass or less of the entire propylene polymer.

From the viewpoint of improving the overall intrinsic viscosity, flowability, processability, and miscibility of the propylene polymer component (A), the second propylene polymer component (b) preferably has an intrinsic viscosity of 0.1 to 5 dL/g, more preferably 0.5 to 5 dL/g, and even more preferably 0.5 to 2 dL/g.

The intrinsic viscosity [η]b of the second propylene polymer component (b) can be calculated using the following formula:

[η]b=([η]T×100−[η]a×Wa)/Wb
[η]T: intrinsic viscosity of the entire propylene polymer [η]a: intrinsic viscosity of the first propylene polymer component (a) Wa: content (mass%) of the first propylene polymer component (a)
Wb: content (mass%) of the second propylene polymer component (b)

As the second propylene polymer component (b), an isotactic propylene polymer satisfying the above conditions is preferably used. Among these, propylene homopolymers, crystalline copolymers of propylene with ethylene and an α-olefin, and polymers in which an amorphous ethylene-α-olefin copolymer is dispersed in a crystalline propylene polymer are preferred. A particularly preferred second propylene polymer component (b) is a propylene homopolymer. From the viewpoint of ensuring crystallinity, examples of the second propylene polymer component (b) include random copolymers of propylene and 10% by mass or less of ethylene, random copolymers of propylene and 30% by mass or less of an α-olefin having 4 to 12 carbon atoms, and ternary random copolymers of propylene, 10% by mass or less of ethylene, and 30% by mass or less of an α-olefin having 4 to 12 carbon atoms. An even more preferred α-olefin is, for example, 1-butene.

In this embodiment, component (A) propylene polymer can be prepared using a stereoregular olefin polymerization catalyst. A preferred stereoregular olefin polymerization catalyst is one containing, for example, Ti, Mg, and a halogen as essential components. The first propylene polymer component (a) can be prepared by employing a catalyst system and conditions that provide a polymerization rate during monomer polymerization of 2,000 g or more per 1 g of catalyst per hour. Here, "1 g of catalyst" refers to 1 g of a solid catalyst containing, as essential components, Ti, Mg, and a halogen.

Specific examples of suitable catalysts include catalysts (solid catalyst components) manufactured by the manufacturing method described in JP-A-2003-105020.

Methods that can be used to prepare the first propylene polymer component (a) include, for example, solvent polymerization using an inert solvent such as a hydrocarbon, such as hexane, heptane, octane, decane, cyclohexane, methylcyclohexane, benzene, toluene, or xylene; bulk polymerization using a liquid monomer as a solvent; and gas-phase polymerization carried out in gaseous monomer. Among these, bulk polymerization and gas-phase polymerization are preferred because of the ease of post-treatment.

The polymerization temperature for the first propylene polymer component (a) is typically 20 to 150°C, and preferably 35 to 95°C. Polymerization within this temperature range is preferred from the viewpoint of improving productivity and also from the viewpoint of achieving the desired quantitative ratio between the first propylene polymer component (a) and the second propylene polymer component (b).

The polymerization rate during polymerization of the first propylene polymer component (a) is preferably 2,000 g or more per 1 g of catalyst and per hour using a preparation method that increases production efficiency, suppresses a decrease in heat resistance and coloration due to catalyst residue in the polymer, and eliminates the need for catalyst removal.

As already explained, the second propylene polymer component (b) is preferably prepared by preparing the first propylene polymer component (a) in a first-stage polymerization reactor and then polymerizing it in a second-stage polymerization reactor. Solvent polymerization, bulk polymerization, gas-phase polymerization, or a combination of these polymerization methods can be used. Bulk polymerization, gas-phase polymerization, or a combination of these polymerization methods are particularly preferred, as they can increase polymerization activity and facilitate post-treatment.

From the viewpoint of improving production efficiency and achieving a favorable quantitative ratio between the first propylene polymer component (a) and the second propylene polymer component (b), the polymerization rate in the preparation of the second propylene polymer component (b) is preferably adjusted by the polymerization conditions so that it is at least twice the polymerization rate in the preparation of the first propylene polymer component (a) per gram of catalyst per hour, and more preferably at least three times the polymerization rate in the preparation of the first propylene polymer component (a). The polymerization temperature in this case may be the same as or different from the polymerization temperature of the first propylene polymer component (a). The polymerization temperature in the preparation of the second propylene polymer component (b) is typically 20 to 150°C, preferably 35 to 95°C.

(2) Component (B) Hydrazide Compound In the present embodiment, the propylene-based resin composition may further contain component (B) a hydrazide compound.

In this embodiment, component (B) the hydrazide compound functions as a metal deactivator (copper inhibitor) and is added to prevent deterioration of the molded article molded from the propylene-based resin composition of this embodiment, which is caused by contact between the molded article and metal at the electrical contact points of a connector in a wire harness, for example.

In this embodiment, a hydrazide compound refers to a phenyl or phenol compound containing one or more groups represented by -C(=O)-NH-.

Specific examples of hydrazide compounds that can be suitably used in this embodiment are hydrazide compounds represented by the following formula (1):

In the formula (1), R ₁ and R ₂ each independently represent an alkyl group having 1 to 8 carbon atoms.

In this specification, an "alkyl group" may have a substituent. Unless otherwise specified, an "alkyl group" may be linear, branched, or cyclic. The number of carbon atoms in an alkyl group, not including the number of carbon atoms in the substituent, is typically 1 to 10, preferably 1 to 8, and more preferably 1 to 4.

Specific examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isoamyl, 2-ethylbutyl, n-hexyl, cyclohexyl, n-heptyl, cyclohexylmethyl, cyclohexylethyl, n-octyl, 2-ethylhexyl, 3-n-propylheptyl, adamantyl, n-decyl, 3,7-dimethyloctyl, and 2-ethyloctyl.

Specific examples of substituted alkyls include methyl and tert-butyl groups.

It is preferable that _R1 and _R2 are each independently a methyl group and a tert-butyl group, and from the viewpoint of suppressing coloration of the molded body and achieving both rigidity and copper damage prevention performance, it is more preferable that _R1 and _R2 are a tert-butyl group.

In other words, in this embodiment, it is preferable to use 2',3-bis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]propionohydrazide, which is hydrazide compound (B-1) represented by the following formula (B-1), as the hydrazide compound component (B).

As the hydrazide compound (B-1), for example, the commercially available product "IRGANOX MD1024" manufactured by BASF Japan Ltd. can be used.

In the propylene-based resin composition of this embodiment, the blending amount (content) of the hydrazide compound represented by formula (1) is typically 0.01 to 10 parts by mass, preferably 0.05 to 1.0 part by mass, and more preferably 0.05 to 0.5 part by mass, per 100 parts by mass of the propylene-based polymer (component (A)), from the viewpoints of effectively suppressing deterioration of the molded article due to metal and reducing costs.

By using the above compound as component (B), the hydrazide compound, deterioration of the molded article due to contact with metal can be effectively suppressed, and the melt strength, fluidity during melting, and rigidity of the molded article of the propylene-based resin composition can be improved.

(3) Component (C) Nucleating Agent In the present embodiment, the propylene-based resin composition may further contain component (C) a nucleating agent.

In this embodiment, component (C) the nucleating agent is a component added to promote the crystallization of polypropylene.

As component (C), the nucleating agent, any suitable conventionally known nucleating agent can be used. Examples of nucleating agents include sorbitol-based nucleating agents, metal phosphate ester-based nucleating agents, metal carboxylate-based nucleating agents, and rosin-based nucleating agents. An example of a metal carboxylate-based nucleating agent is aluminum hydroxy-di(p-tert-butylbenzoate).

The nucleating agent, hydroxy-di(p-tert-butylbenzoate)aluminum, can be, for example, the commercially available product "AL-PTBBA" manufactured by Japan Chemtech Co., Ltd.

In the propylene-based resin composition of this embodiment, it is preferable to use a metal salt represented by the following formula (2) as the nucleating agent (component (C)).

In formula (2), M ₁ and M ₂ each independently represent a sodium atom or a hydrogen atom, and at least one of M ₁ and M ₂ is a sodium atom;
R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₂ , and R ₁₃ are each independently a group selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 9 carbon atoms, an alkyleneoxy group having 1 to 9 carbon atoms, an amino group, an alkylamino group having 1 to 9 carbon atoms, a halogen atom, and a phenyl group. When two or more groups among R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₂ , and R ₁₃ are alkyl groups, these groups may be bonded to each other to form a hydrocarbon ring.

In this embodiment, from the viewpoint of improving the rigidity of a molded article obtained by molding the propylene-based resin composition, it is preferable to use disodium bicyclo(2,2,1)heptane-2,3-dicarboxylate (nucleating agent (C-1)) represented by the following formula (C-1) or calcium 1,2-cyclohexanedicarboxylate (nucleating agent (C-2)) represented by the following formula (C-2) as the metal salt serving as the nucleating agent (component (C)). In other words, it is preferable that the propylene-based resin composition of this embodiment contains, as a nucleating agent, a compound represented by the following formula (C-1) or a compound represented by the following formula (C-2).

Commercially available products can also be used as the metal salt nucleating agent for component (C). An example of a commercially available nucleating agent (C-1) is HPN-68L (trade name, manufactured by Milliken). An example of a commercially available nucleating agent (C-2) is HPN-20E (trade name, manufactured by Milliken).

In this embodiment, the amount of nucleating agent added is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and preferably 3 parts by mass or less, more preferably 1 part by mass or less, and preferably 0.05 to 1 part by mass, relative to 100 parts by mass of the propylene-based polymer (component (A)) already described).

Using the above compound as component (C) as a nucleating agent can improve the degree of crystallization of the propylene polymer contained in the propylene resin composition, thereby improving the rigidity of the molded article.

(4) Optional Components The propylene-based resin composition of the present embodiment may contain further optional components in addition to the components already described above.

Examples of such optional ingredients include neutralizing agents, antioxidants, inorganic fillers, flame retardants, elastomers, antioxidants, ultraviolet absorbers, lubricants, antistatic agents, antiblocking agents, processing aids, organic peroxides, colorants (e.g., inorganic pigments, organic pigments), pigment dispersants, foaming agents, foam nucleating agents, plasticizers, crosslinking agents, crosslinking aids, brightness enhancers, antibacterial agents, light diffusing agents, and molecular weight modifiers.

The propylene-based resin composition of this embodiment may contain one of these optional components alone, or may contain two or more optional components in any combination and ratio.

(i) Neutralizing Agent In the present embodiment, any suitable conventionally known antioxidant can be used as the neutralizing agent. Two or more neutralizing agents may be used in combination.

Specific examples of neutralizing agents include hydrotalcite and calcium stearate. In this embodiment, calcium stearate (e.g., manufactured by Sakai Chemical Industry Co., Ltd.) is preferably used as the neutralizing agent.

When the propylene-based resin composition of this embodiment contains a neutralizing agent, the content of the neutralizing agent in the propylene-based resin composition is typically 0 parts by mass or more, preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, and preferably 0.5 parts by mass or less, and more preferably 0.1 parts by mass or less, based on 100 parts by mass of the total amount of component (A) propylene polymer contained in the propylene-based resin composition. Setting the neutralizing agent content in this manner effectively suppresses discoloration of a molded article obtained by molding the propylene-based resin composition, and improves rigidity and copper damage prevention performance.

(ii) Antioxidant In the present embodiment, any suitable antioxidant known in the art can be used as the antioxidant. Two or more types of antioxidants may be used in combination.

Specific examples of suitable antioxidants include phenol-based antioxidants (e.g., Sumilizer GA80 (Sumitomo Chemical Co., Ltd.)), sulfur-based antioxidants (e.g., Sumilizer TPM (Sumitomo Chemical Co., Ltd.)), and phosphorus-based antioxidants (e.g., SONGNOX 6260 (Songwon Chemical Co., Ltd.)).

When the propylene-based resin composition of this embodiment contains an antioxidant, the content of the antioxidant in the propylene-based resin composition is typically 0 parts by mass or more, preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, preferably 1 part by mass or less, more preferably 0.5 parts by mass or less, and even more preferably 0.3 parts by mass or less, relative to 100 parts by mass of the total amount of component (A) propylene polymer contained in the propylene-based resin composition. Setting the antioxidant content in this manner can effectively suppress discoloration of a molded article obtained by molding the propylene-based resin composition, and can improve rigidity and copper damage prevention performance.

(iii) Inorganic Filler The propylene-based resin composition according to this embodiment may further contain an inorganic filler from the viewpoint of improving mechanical properties, electrical properties, and the like.

Examples of inorganic fillers include (i) fibrous inorganic fillers and (ii) non-fibrous inorganic fillers. Two or more types of inorganic fillers may be used in combination. Specific examples are described below.

(i) Fibrous Inorganic Filler In the present embodiment, the fibrous inorganic filler preferably has an average fiber diameter of 0.2 μm to 20 μm, an average fiber length of 5 μm to 200 μm, and an aspect ratio of 10 to 30. From the viewpoint of improving the rigidity of the molded body and improving the appearance of the molded body, it is more preferable that the average fiber diameter is 0.3 μm to 10 μm, the average fiber length is 7 μm to 150 μm, and the aspect ratio is 12 to 25.

The average fiber diameter and average fiber length of a fibrous inorganic filler are the average values of the fiber diameter and fiber length measured by randomly selecting 50 or more fibers from an image of the fibrous inorganic filler obtained, for example, by electron microscopy, and the aspect ratio can be calculated using these average values.

Examples of fibrous inorganic fillers include fibrous magnesium oxysulfate, potassium titanate fiber, magnesium hydroxide fiber, aluminum borate fiber, calcium silicate fiber, calcium carbonate fiber, carbon fiber, glass fiber, and metal fiber. Of these, it is preferable to use fibrous magnesium oxysulfate and calcium silicate fiber.

The fibrous inorganic filler can be used as is, or it can be surface-treated with, for example, a silane coupling agent or a metal salt of a higher fatty acid to improve interfacial adhesion and dispersibility.

Examples of higher fatty acid metal salts used for surface treatment include calcium stearate, magnesium stearate, and zinc stearate.

In this embodiment, examples of the form of the fibrous inorganic filler include powder, flake, and granule. In this embodiment, any of the above forms of fibrous inorganic filler can be used. Because of its ease of handling, it is preferable to use a granular fibrous inorganic filler.

(ii) Non-fibrous inorganic filler Examples of non-fibrous inorganic fillers include talc, mica, calcium carbonate, barium sulfate, magnesium carbonate, clay, alumina, silica, calcium sulfate, silica sand, carbon black, titanium oxide, magnesium hydroxide, zeolite, molybdenum, diatomaceous earth, sericite, shirasu, calcium hydroxide, calcium sulfite, sodium sulfate, bentonite, graphite, etc. From the viewpoints of improving the impact strength and improving the appearance of the molded body, it is preferable to use talc.

The average particle diameter of the non-fibrous inorganic filler is preferably 10 μm or less, and more preferably 5 μm or less. Here, the average particle diameter of the non-fibrous inorganic filler can be determined as the 50% equivalent particle diameter D50 from the integral distribution curve obtained by suspending the non-fibrous inorganic filler in a dispersant such as water or alcohol and subjecting the suspension obtained to a sieve size reduction method using a centrifugal sedimentation particle size distribution analyzer.

The non-fibrous inorganic filler may be used as is, or its surface may be treated with a silane coupling agent, titanium coupling agent, or surfactant to improve interfacial adhesion and dispersibility. Examples of surfactants include higher fatty acids, higher fatty acid esters, higher fatty acid amides, and higher fatty acid salts.

The fibrous inorganic filler can be used as is, or it can be surface-treated with a silane coupling agent or a metal salt of a higher fatty acid to improve interfacial adhesion and dispersibility.

3. Properties of Propylene-Based Resin Compositions (1) Melt Flow Rate (MRF)
The melt flow rate of the propylene-based resin composition of this embodiment at a temperature of 230° C. and a load of 2.16 kgf is preferably 0.1 g/10 min or more from the viewpoint of improving the molding processability of the propylene-based resin composition.

4. Method for Producing Propylene-Based Resin Composition The propylene-based resin composition of this embodiment can be produced by melt-kneading the components already described as raw materials. The temperature during melt-kneading may be 180°C or higher, 180 to 300°C, or 180 to 250°C.

Examples of production apparatuses used in melt-kneading to produce the propylene-based resin composition of this embodiment include a Banbury mixer, a single-screw extruder, and a twin-screw co-rotating extruder.

The order in which the raw materials are mixed is not particularly limited. For example, all raw materials may be mixed by adding them all at once to the manufacturing equipment, or some of the selected components may be mixed and then the resulting mixture may be mixed with the other components.

The properties of the propylene-based resin composition of this embodiment are not particularly limited. The propylene-based resin composition of this embodiment can be in the form of, for example, a strand (filament), a sheet, a plate, or a pellet. A pellet-shaped composition can be produced, for example, by forming a strand of the propylene-based resin composition and then cutting it to an appropriate length.

From the perspective of improving the moldability of the propylene-based resin composition and increasing the production stability of molded articles, it is preferable that the propylene-based resin composition be in the form of pellets with a length of approximately 1 to 50 mm before being molded into a molded article.

The propylene-based resin composition of this embodiment can effectively suppress discoloration of the molded article, and can achieve both the rigidity and copper damage prevention performance required when the molded article is applied to a connector for a vehicle wire harness, particularly.It can also provide a connector for a vehicle wire harness that is both lightweight and rigid.

5. Molded Article The propylene-based resin composition of the present embodiment can be suitably used as a material for forming a molded article. The propylene-based resin composition of the present embodiment is particularly preferably used as a material for injection molding.

Below, an example will be described in which the propylene-based resin composition of this embodiment is used as an injection molding material to produce an injection-molded article.

The injection-molded article is a molded article obtained by molding the propylene-based resin composition of this embodiment. Injection-molded articles generally have excellent dimensional stability.

Injection-molded articles can be produced by injection molding. Examples of injection molding methods include injection foam molding, supercritical injection foam molding, ultra-high-speed injection molding, injection compression molding, gas-assisted injection molding, sandwich molding, sandwich foam molding, and insert-outsert molding.

The molded article (injection molded article) of this embodiment can be produced by the above-described manufacturing method in any suitable shape and dimensions depending on the application.

The injection-molded article of this embodiment is preferably used, for example, as a material for vehicle-related components, particularly as an interior or exterior material for automobiles, as a material for home appliances, and as a container, and is more preferably used as a material for vehicle-related components. Examples of material applications for vehicle-related components include interior and exterior parts for automobiles, such as door trims, pillars, instrument panels, and bumpers.

The injection-molded article of this embodiment has low colorability, good rigidity and copper damage prevention performance, and is able to achieve both lightweight and rigidity, making it particularly suitable for use in wire harness connectors, which are vehicle-related components.

Here, an example of the configuration of a connector for a vehicle wire harness of this embodiment to which the propylene-based resin composition of this embodiment can be suitably applied will be described with reference to the drawings.

Figure 1 is a diagram showing a schematic configuration example of a connector for a vehicle wire harness. Figure 2 is a diagram showing a schematic cut end surface of the connector for a vehicle wire harness cut at the position of the dashed line A-A shown in Figure 1.

As shown in Figures 1 and 2, the connector 10 of the vehicle wire harness is provided with one or more insertion portions 10a.

The insertion sections 10a extend in a direction perpendicular to the thickness direction and are configured as through-holes arranged parallel to one another. In this configuration example, the shapes of the cut end surfaces when the multiple insertion sections 10a are cut in a direction perpendicular to the extension direction are identical to one another.

As shown in FIG. 2, the connector 10 of the vehicle wire harness is provided with one or more lance portions 12. In the illustrated example, one lance portion 12 is provided for each insertion portion 10a, which is a through hole, but two or more lance portions 12 may be provided for each insertion portion 10a, or even only some of the multiple insertion portions 10a.

In the illustrated example, the lance portion 12 is provided so as to protrude in a wedge shape from the wall surface defining the insertion portion 10a, which is a through hole, in the vertical direction, which is perpendicular to the extension direction of the insertion portion 10a.

In the connector 10 for a vehicle wire harness of this embodiment, the height 12b, including the maximum height 12a in a direction perpendicular to the wall surface defining the insertion portion 10a of the lance portion 12, i.e., the thickness of the lance portion 12, is preferably 2 mm or less, more preferably 1.5 mm or less, from the viewpoint of connector miniaturization and high-speed moldability; and from the viewpoint of mechanical strength, it is preferably 0.2 mm or more, more preferably 0.4 mm or more, preferably in the range of 0.2 mm to 1.5 mm, and preferably in the range of 0.4 mm to 1.0 mm.

As shown in Figure 2, at least a portion of the terminal portion 20 is shaped to correspond to the shape of the lance portion 12 and fit into the lance portion 12, allowing the terminal portion 20 to be removably secured to the insertion portion 10a, i.e., the connector 10 of the vehicle wire harness. In other words, in this configuration example, the shape has a recess that can fit into and lock onto the lance portion 12.

By having the connector 10 and terminal portion 20 of the vehicle wire harness configured as described above, the terminal portion 20 is removably fixed to the connector 10 of the vehicle wire harness, and the connector 10 of the vehicle wire harness and the terminal portion 20 are electrically connected.

The components used in the examples and comparative examples are shown below.
(1) Component (A) Propylene-Based Polymer (A-1) Propylene-Based Polymer (Component (A-1))
A propylene homopolymer (polypropylene), component (A-1), was prepared using the polymerization catalyst described in Example 1 of JP-A-11-228629 in accordance with the polymerization method and polymerization conditions described in Example 1.

Specifically, the first step was carried out by continuously supplying liquid propylene, triethylaluminum, tert-butyl-n-propyldimethoxysilane, and a polymerization catalyst to a first stainless steel reactor to polymerize the first propylene polymer component (a).

Next, without deactivating the polymerization catalyst, the polymerization catalyst and the first propylene polymer component (a) were transferred to a second reaction vessel connected in series to the first reaction vessel, and a second step was carried out in which a second propylene polymer component (b) having a molecular weight different from that of the first propylene polymer component (a) was polymerized while further supplying propylene and hydrogen.

The intrinsic viscosity [η]b of the second propylene polymer component (b) was calculated by the following formula based on the intrinsic viscosities [η]a and [η]T determined as above.
Formula: [η]b=([η]T×100−[η]a×Wa)/Wb

During the ceremony,
[η]T represents the intrinsic viscosity of component (A-1) propylene homopolymer,
[η]a represents the intrinsic viscosity of the first component (a),
Wa represents the content (mass%) of the first propylene polymer component (a),
Wb represents the content (mass%) of the second propylene polymer component (b).

In this way, component (A-1) propylene polymer was obtained, which was a propylene homopolymer composed of 19% by mass of a first propylene polymer component (a) having an intrinsic viscosity [η]a of 7.1 dL/g and 81% by mass of a second propylene polymer component (b) having an intrinsic viscosity [η]b of 0.76 dL/g. The physical properties of the resulting component (A-1) propylene polymer were as follows:

Melt flow rate (230°C, load 2.16 kgf): 11.5 g/10 min Weight average molecular weight (Mw) 530,000, number average molecular weight (Mn) 58,000, molecular weight distribution (Mw/Mn) 9.1, intrinsic viscosity [η]T: 1.94 dL/g

(A-2) Propylene-based polymer (component (A-2))
A resin powder, propylene homopolymer (A-2), was produced by gas phase polymerization using a solid catalyst component produced by the method described in JP 2003-105020 A. The resulting propylene homopolymer had a melt flow rate (230°C, load 2.16 kgf): 0.5 g/10 min, a weight average molecular weight (Mw) of 730,000, a number average molecular weight (Mn) of 190,000, a molecular weight distribution (Mw/Mn) of 3.8, and an intrinsic viscosity [η]T of 2.96 dL/g.

(A-3) Propylene-based polymer (component (A-3))
A resin powder, propylene homopolymer (A-3), was produced by gas phase polymerization using a solid catalyst component produced by the method described in JP 2003-105020 A. The resulting propylene homopolymer had a melt flow rate (230°C, load 2.16 kgf): 120 g/10 min, a weight average molecular weight (Mw) of 180,000, a number average molecular weight (Mn) of 49,000, a molecular weight distribution (Mw/Mn) of 3.8, and an intrinsic viscosity [η]T of 0.93 dL/g.

(A-4) Propylene-based polymer (component (A-4))
A resin powder, propylene homopolymer (A-4), was produced by gas phase polymerization using a solid catalyst component produced by the method described in JP 2003-105020 A. The resulting propylene homopolymer had a melt flow rate (230°C, load 2.16 kgf): 8.0 g/10 min, a weight average molecular weight (Mw) of 365,000, a number average molecular weight (Mn) of 105,000, a molecular weight distribution (Mw/Mn) of 3.5, and an intrinsic viscosity [η]T of 1.61 dL/g.

(2) Component (B) Hydrazide Compound As the component (B) hydrazide compound, 2',3-bis[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]propionohydrazide (manufactured by BASF Japan, IRGANOX MD1024), which is hydrazide compound (B-1) represented by the following formula (B-1), and 2-hydroxy-N-1H-1,2,4-triazol-3-yl-benzamide (manufactured by ADEKA CORPORATION, Adeka STAB CDA-1M), which is hydrazide compound (B-2) represented by the following formula, were used.

(3) Component (C) Nucleating Agent As the nucleating agent for component (C), a nucleating agent (C-1) (manufactured by Milliken, Hyperform HPN-68L), which is a compound represented by the following formula (C-1), and a nucleating agent (C-2) (manufactured by Milliken, Hyperform HPN-20E), which is a compound represented by the following formula (C-2), were used.

Details of the nucleating agents (C-1) and (C-2) are as follows:
(i) Nucleating Agent (C-1)
Chemical name of the main component: Disodium (1R,2R,3S,4S)-bicyclo[2.2.1
] Heptane-2,3-dicarboxylate Content of main component: 80% by mass

(ii) Nucleating Agent (C-2)
Chemical name of main ingredient: 1,2-cyclohexanedicarboxylic acid calcium salt CAS Reg. No.: 491589-22-1
Content of main component: 66% by mass
Chemical name of secondary ingredient: Zinc stearate CAS Reg. No.: 557-05-1
Content of auxiliary components: 34% by mass
Average particle size: 2.6 μm (measured using a laser diffraction particle size distribution analyzer (HELOS (trade name) manufactured by Sympatec))

(4) Neutralizing Agent Calcium stearate (manufactured by Sakai Chemical Industry Co., Ltd.) was used as the neutralizing agent. The CAS number is as follows:
CAS. 1592-23-0

(5) Antioxidants The following (i) to (iii) were used as antioxidants (CAS numbers are given):
(i) Sumilizer GA80 (manufactured by Sumitomo Chemical Co., Ltd.)
CAS. 90498-90-1
(ii) SONGNOX 6260 (manufactured by Songwon)
CAS. 26741-53-7
(iii) Sumilizer TPM (Sumitomo Chemical Co., Ltd.)
CAS. 16545-54-3

[Example 1]
100 parts by mass of component (A-1) propylene-based polymer, 0.1 parts by mass of hydrazide compound (B-1), 0.2 parts by mass of nucleating agent (C-1), 0.05 parts by mass of calcium stearate, 0.1 parts by mass of antioxidants Sumilizer GA80, 0.05 parts by mass of SONGNOX 6260, and 0.2 parts by mass of Sumilizer TPM were weighed and uniformly mixed. The mixture was then introduced into the most upstream raw material inlet of a twin-screw kneader "TEX44αII" manufactured by The Japan Steel Works, Ltd., and melt-kneaded under conditions of a cylinder temperature of 230°C, a discharge rate of 50 kg/hour, and a screw rotation speed of 200 rpm to obtain pelletized propylene-based resin composition (a1). The materials used are also shown in Table 1 below. Note that all values in Table 1 represent parts by mass.

Next, the propylene-based resin composition (a1) was evaluated using the following measurement methods.

(1) Melt flow rate (MFR, unit: g/10 min)
The melt flow rate (MFR) was measured at 230° C. under a load of 21 N in accordance with ASTM D1238.

(2) Color (appearance: visual evaluation)
The pelletized propylene-based resin composition prepared as described above was fed into a mold cavity through the gate of an injection molding machine and injection-molded to obtain a plate-shaped molded product measuring 90 mm (width) × 150 mm (length) × 1 mm (thickness). The injection molding machine used and the injection molding conditions are as follows:
Injection molding machine: Toshiba Corporation, IS100EN (mold clamping force 100 tons, cylinder diameter 36 mm)
Mold cavity shape: rectangular parallelepiped of 90 mm (width) x 150 mm (length) x 1 mm (thickness) Gate: one gate opening in the center of the surface defining the 90 mm (width) of the mold cavity Cylinder temperature: 240°C
Mold temperature: 50°C
Injection speed: 27mm/sec

The appearance (surface color) of the obtained flat-plate-shaped molded body was evaluated visually. A white surface was evaluated as good (○), and a pale yellow surface was evaluated as poor (×). The results are shown in Table 1 below.

(3) Weight average molecular weight (Mw), number average molecular weight (Mn), molecular weight distribution (Mw/Mn)
The polystyrene-equivalent weight-average molecular weight, number-average molecular weight, and molecular weight distribution were measured using the following method. Tetrahydrofuran was used as the solvent, and the sample solution concentration was adjusted to 0.5 mg/mL. Two GPC columns, Plus Pore Series Poly Pore 7.5 mm ID x 300 mm (Agilent Technologies), were connected in series. The mobile phase was tetrahydrofuran, and the flow rate was 1 mL/min. The column oven temperature was set to 35°C, and a differential refractive index detector was used as the detector (RID cell temperature: 35°C). The sample solution injection volume was 100 μL. PStQuick Kit-H (Tosoh Corporation) was used as the calibration standard for the GPC column.

(4) 1 mmt flexural modulus (unit: MPa) and flexural strength (unit: MPa)
ASTM D790-Type 4 dumbbells were punched out from the 90 x 150 x 1 mm plate-shaped molded product obtained as described above, and the flexural modulus and flexural strength at 23°C were measured in accordance with ASTM D790. The results are shown in Table 1 below.

[Example 2]
A pellet-shaped propylene-based resin composition was prepared in the same manner as in Example 1, except that the nucleating agent (C-2) was used instead of the nucleating agent (C-1), and a molded article was evaluated. The results are shown in Table 1 below.

[Example 3]
A pellet-shaped propylene-based resin composition was prepared in the same manner as in Example 1, except that the hydrazide compound (B-1) and the nucleating agent (C-1) were not used, and a molded product was evaluated. The results are shown in Table 1 below.

[Comparative Examples 1 to 3]
Pellets of propylene-based resin compositions were prepared and molded articles were evaluated in the same manner as in Example 3, except that the propylene-based polymers were used in the proportions shown in Table 1. The results are shown in Table 1 below.

10 Connector of vehicle wire harness 10a Insertion portion 12 Lance portion 12a Maximum height 12b Height 20 Terminal portion

Claims (8)

The propylene-based resin composition includes a propylene-based polymer having a weight average molecular weight of 500,000 to 1,000,000 in terms of polystyrene, determined by a GPC method , and a molecular weight distribution (weight average molecular weight/number average molecular weight) of 6 to 10, and a hydrazide compound which is a phenyl or phenol compound containing one or more groups represented by -C(=O)-NH- ,
A connector for a vehicle wire harness having one or more insertion portions and one or more lance portions provided so as to protrude from a wall surface defining the insertion portions, wherein the thickness of the lance portions is 1 mm or less. the melt flow rate of the propylene polymer measured under conditions of a temperature of 230°C and a load of 2.16 kgf is 0.1 to 15 g/10 min,
2. The connector for a vehicle wire harness according to claim 1, wherein the propylene-based polymer has an intrinsic viscosity of 1.5 dL/g or more. 3. The connector for a vehicle wire harness according to claim 1, wherein the propylene-based resin composition further contains a nucleating agent , and the hydrazide compound is a hydrazide compound represented by the following formula (1):
(In the formula (1), _R1 and _R2 each independently represent an alkyl group having 1 to 8 carbon atoms.) The connector for a vehicle wire harness according to claim 3, wherein in the formula (1), R ₁ and R ₂ are tert-butyl groups. The connector of the vehicle wire harness according to claim 3 or 4, wherein the nucleating agent comprises a compound represented by the following formula (C-1) or a compound represented by the following formula (C-2):
the propylene-based polymer comprises a first propylene polymer component and a second propylene polymer component;
the first propylene polymer component has an intrinsic viscosity of 5 to 8 dL/g;
The connector for a vehicle wire harness according to any one of claims 1 to 5, wherein the second propylene polymer component has an intrinsic viscosity of 0.5 to 2 dL/g. the proportion of the first propylene polymer component in the entire propylene-based polymer is 10% by mass or more and 20% by mass or less,
7. The connector for a vehicle wire harness according to claim 6, wherein the second propylene polymer component accounts for 80% by mass or more and 90% by mass or less of the entire propylene-based polymer. a propylene polymer having a weight average molecular weight of 500,000 to 1,000,000 in terms of polystyrene, determined by a GPC method, a molecular weight distribution (weight average molecular weight/number average molecular weight) of 6 to 10, a melt flow rate of 0.1 to 15 g/10 min, measured under conditions of a temperature of 230°C and a load of 2.16 kgf, and an intrinsic viscosity of 1.5 dL/g or more;
A nucleating agent;
A propylene-based resin composition comprising a hydrazide compound represented by the following formula (1):
(In the formula (1), _R1 and _R2 each independently represent an alkyl group having 1 to 8 carbon atoms.)