JP7484495B2 - Ethylene-based ionomer for three-dimensional network structure and molded body thereof - Google Patents

Description

The present invention relates to an ethylene-based ionomer for three-dimensional network structures that uses a new ionomer and has an excellent balance of flexibility, elastic recovery, and moldability, and to a molded article made from the same.

Ethylene-based ionomers are resins that use ethylene-unsaturated carboxylic acid copolymers as a base resin and are intermolecularly bonded with metal ions such as sodium and zinc (Patent Document 1). They are characterized by their toughness, elasticity, flexibility, abrasion resistance, transparency, etc.
Currently, known ethylene-based ionomers available on the market include "Surlyn (registered trademark)", a sodium salt or zinc salt of ethylene-methacrylic acid copolymer developed by DuPont, and "Himilan (registered trademark)" sold by Dow Mitsui Polychemicals.

However, the ethylene-unsaturated carboxylic acid copolymers used as the base resins in these currently commercially available ethylene-based ionomers all use polar group-containing olefin copolymers obtained by polymerizing ethylene and polar group-containing monomers such as unsaturated carboxylic acids using a high-pressure radical polymerization method. The high-pressure radical polymerization method has the advantage that it can polymerize relatively any type of polar group-containing monomer at low cost. However, the molecular structure of the polar group-containing olefin copolymer produced by this high-pressure radical polymerization method has many irregular long-chain branches and short-chain branches, as shown in the image diagram in Figure 1, and has the disadvantage of being insufficient in terms of strength.

Meanwhile, methods have been sought for producing polar group-containing olefin copolymers having a linear molecular structure, as shown in the image diagram of FIG. 2, by using a polymerization method using a catalyst. However, polar group-containing monomers are generally catalyst poisons and are therefore difficult to polymerize. In fact, it has been considered difficult for many years to obtain polar group-containing olefin copolymers having desired physical properties in an industrially inexpensive and stable manner.
However, in recent years, a method has been proposed for industrially inexpensively and stably obtaining polar group-containing olefin copolymers having a substantially linear molecular structure by using a new catalyst and a new production method developed by the applicants of the present application, etc. For example, the applicants of the present application have reported that, as a method for producing a polar group-containing olefin copolymer that serves as a base resin for an ethylene-based ionomer, a copolymer of ethylene and t-butyl acrylate is produced using a late transition metal catalyst, the polar group-containing olefin copolymer obtained is modified into an ethylene-acrylic acid copolymer by heat or acid treatment, and then a binary ionomer is produced by reacting it with a metal ion (Patent Document 2).

This ethylene-based ionomer is a novel ethylene-based ionomer that has never been seen before, in that the base resin has a substantially linear molecular structure and also functions as an ionomer, and its physical properties are significantly different from those of conventional ethylene-based ionomers.

Furthermore, Patent Document 3 discloses a three-dimensional network structure that uses polyethylene with a specific swell ratio at a specific shear rate, is manufactured in a specific strand shape, and has the flexibility to follow the deformation of the bed.

U.S. Pat. No. 3,264,272 JP 2016-79408 A International Publication No. 2013/088736

As described in Patent Document 3, in recent years, three-dimensional network structures made of polyethylene have been widely used as bed mats and the like because of the advantages of being highly resilient and easy to turn over in, being breathable, and being hygienic because it can be washed with water. However, three-dimensional network structures made of polyethylene have a problem that they lack the resilience of rubber because the polyethylene material itself does not have sufficient elastic recovery, and it is difficult to obtain sufficient cushioning when the three-dimensional network structure is compressed by a person's weight. Therefore, a new material is required that has both flexibility and elastic recovery, and has moldability similar to that of polyethylene materials.
In view of the above-mentioned state of the prior art, the present application aims to provide an ethylene-based ionomer for a three-dimensional network structure having an excellent balance of flexibility, elastic recovery and moldability, and a three-dimensional network structure that is a molded product thereof.

As a result of extensive investigations conducted by the inventors to solve the above problems, they discovered that the use of a specific ethylene-based ionomer has an excellent effect in terms of the balance of flexibility, elastic recovery, and moldability as a material for three-dimensional network structures.
The ethylene-based ionomer described in Patent Document 2 is a novel ethylene-based ionomer that has not been seen before, in which the precursor resin has a substantially linear molecular structure and also functions as an ionomer, and its physical properties, etc. are significantly different from those of conventional ethylene-based ionomers, and its specific characteristics and suitable applications were also unknown. The present invention is based on the discovery that, although ethylene-based ionomers basically do not have high elastic recovery, by using a specific substantially linear ethylene-based ionomer, it is unexpectedly possible to obtain an excellent effect in terms of elastic recovery while maintaining flexibility and moldability.

That is, the aspects of the present invention are shown in 1. to 8. below.
1. The following characteristics (a) to (f):
(a) using a copolymer (P) containing, as essential constituent units, a structural unit (A) derived from ethylene and/or an α-olefin having 3 to 20 carbon atoms and a structural unit (B) derived from a monomer having a carboxyl group and/or a dicarboxylic anhydride group as a base resin;
(b) at least a part of the carboxyl groups and/or dicarboxylic anhydride groups in the structural unit (B) is converted to a metal-containing carboxylate containing at least one metal ion selected from Group 1, Group 2, or Group 12 of the Periodic Table;
(c) the phase angle δ at an absolute value of the complex modulus G ^* of 0.1 MPa measured by a rotational rheometer is 50 to 75 degrees;
(d) a melt flow rate (MFR) of 1 to 50 g/10 min at a temperature of 190° C. and a load of 2.16 kg;
(e) an elastic recovery rate in a tensile test of 65 to 100%; and (f) a tensile modulus of elasticity of 20 to 200 MPa;
The ethylene-based ionomer for three-dimensional network structures is an ionomer resin that satisfies the above requirements.
2.
The ethylene-based ionomer for a three-dimensional network structure according to 1. above, characterized in that the number of methyl branches of the copolymer (P) calculated by ¹³ C-NMR is 50 or less per 1,000 carbon atoms.
3.
The ethylene-based ionomer for a three-dimensional network structure according to 1. or 2., wherein the copolymer (P) contains 2 to 20 mol % of the structural unit (B) in the copolymer.
4.
4. The ethylene-based ionomer for a three-dimensional network structure according to any one of the above items 1 to 3, characterized in that the structural unit (A) is a structural unit derived from ethylene.
5.
The ethylene-based ionomer for a three-dimensional network structure according to any one of 1. to 4., characterized in that the copolymer (P) is produced using a transition metal catalyst containing a transition metal of Groups 8 to 11 of the periodic table.
6.
The ethylene-based ionomer for a three-dimensional network structure according to 5. above, characterized in that the transition metal catalyst is a transition metal catalyst comprising a phosphorus sulfonic acid or phosphorus phenol ligand and nickel or palladium.
7.
A molded article made of the ethylene-based ionomer according to any one of 1. to 6. above.
8.
7. The molded article according to the above 7., which is a three-dimensional network structure.

The present invention provides an ethylene-based ionomer with an excellent balance of flexibility, elastic recovery, and moldability, and a molded article made from the ionomer. The ionomer of the present invention, which has a substantially linear structure, is useful because it provides a three-dimensional network structure with superior flexibility and elastic recovery compared to conventional materials.

FIG. 1 is an image of the molecular structure of a hyperbranched olefin copolymer polymerized by a high-pressure radical polymerization process. FIG. 2 is an image of the molecular structure of a linear olefin copolymer polymerized using a metal catalyst.

The ionomer according to the present invention and its applications will be described in detail below.
In this specification, "(meth)acrylic acid" means acrylic acid or methacrylic acid. In addition, in this specification, the numerical range "to" is used to mean that the numerical range includes the numerical range before and after it as the lower and upper limits. In addition, in this specification, a copolymer means a binary or higher copolymer containing at least one type of unit (A) and at least one type of unit (B).
(1) Characteristic (a)
The ionomer of the present invention contains, as essential constituent units, structural units (A) derived from ethylene and/or an α-olefin having 3 to 20 carbon atoms, and structural units (B) derived from a monomer having a carboxyl group and/or a dicarboxylic anhydride group, and has as its base resin a copolymer (P) in which these are randomly copolymerized in a substantially linear manner.

(1-1) Structural unit (A)
The structural unit (A) is at least one structural unit selected from the group consisting of structural units derived from ethylene and structural units derived from an α-olefin having 3 to 20 carbon atoms.
Of these, the α-olefins related to the present invention are α-olefins having 3 to 20 carbon atoms and represented by the structural formula CH ₂ ═CHR ¹⁸ (R ¹⁸ is a hydrocarbon group having 1 to 18 carbon atoms, which may have a linear structure or may be branched). The number of carbon atoms of the α-olefin is more preferably 3 to 12.

Specific examples of the structural unit (A) include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 3-methyl-1-butene, and 4-methyl-1-pentene, and may be ethylene. As the ethylene, ethylene derived from a petroleum raw material or a non-petroleum raw material such as a plant raw material can be used.
The structural unit (A) may be of one type or of multiple types.
Combinations of the two types include ethylene-propylene, ethylene-1-butene, ethylene-1-hexene, ethylene-1-octene, propylene-1-butene, propylene-1-hexene, and propylene-1-octene.
Examples of combinations of the three include ethylene-propylene-1-butene, ethylene-propylene-1-hexene, ethylene-propylene-1-octene, propylene-1-butene-hexene, and propylene-1-butene-1-octene.

In the present invention, the structural unit (A) preferably contains ethylene as an essential component and may further contain one or more α-olefins having 3 to 20 carbon atoms, if necessary.
The amount of ethylene in the structural unit (A) may be 65 to 100 mol % or 70 to 100 mol % based on the total moles of the structural unit (A).

(1-2) Structural unit (B)
The structural unit (B) is a structural unit derived from a monomer having a carboxyl group and/or a dicarboxylic anhydride group.

Specific examples of monomers having a carboxyl group include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, norbornene dicarboxylic acid, and bicyclo[2,2,1]hept-2-ene-5,6-dicarboxylic acid.
Examples of monomers having a dicarboxylic acid anhydride group include unsaturated dicarboxylic acid anhydrides such as maleic anhydride, itaconic anhydride ^, citraconic anhydride ^, tetrahydrophthalic anhydride ^, 5-norbornene-2,3-dicarboxylic anhydride, 3,6-epoxy- ^{1,2,3,6 -} tetrahydrophthalic anhydride, ^tetracyclo [6.2.1.13,6.02,7]dodec-9-ene-4,5-dicarboxylic anhydride, and 2,7-octadien-1-ylsuccinic anhydride.
Specific compounds include acrylic acid, methacrylic acid, 5-norbornene-2,3-dicarboxylic anhydride, and in particular acrylic acid.
The monomer having a carboxyl group and/or a dicarboxylic anhydride group may be of one type or of multiple types.

In addition, the dicarboxylic anhydride group may react with moisture in the air to open the ring and become a dicarboxylic acid, but the dicarboxylic anhydride group may be ring-opened as long as it does not deviate from the gist of the present invention.

(1-3) Optional structural unit (C)
The copolymer (P) according to the present invention may contain an arbitrary structural unit (C) other than the structural units represented by the structural units (A) and (B). Any monomer can be used as the monomer providing the structural unit (C) as long as it is not the same as the monomer providing the structural unit (A) and the structural unit (B).
The arbitrary monomer that provides the structural unit (C) is not limited as long as it is a compound having one or more carbon-carbon double bonds in its molecular structure, and examples thereof include acyclic monomers (i) represented by general formula (1) and cyclic monomers (ii) represented by general formula (2).

(i) Acyclic monomers

[In the above general formula (1), T ¹ to T ³ each independently represent a substituent selected from the group consisting of a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a hydrocarbon group having 1 to 20 carbon atoms substituted with a hydroxyl group, a hydrocarbon group having 2 to 20 carbon atoms substituted with an alkoxy group having 1 to 20 carbon atoms; a hydrocarbon group having 3 to 20 carbon atoms substituted with an ester group having 2 to 20 carbon atoms, a hydrocarbon group having 1 to 20 carbon atoms substituted with a halogen atom; an alkoxy group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an ester group having 2 to 20 carbon atoms, a silyl group having 3 to 20 carbon atoms, a halogen atom, or a cyano group;
^T4 is a substituent selected from the group consisting of a hydrocarbon group having 1 to 20 carbon atoms substituted with a hydroxyl group, a hydrocarbon group having 2 to 20 carbon atoms substituted with an alkoxy group having 1 to 20 carbon atoms; a hydrocarbon group having 3 to 20 carbon atoms substituted with an ester group having 2 to 20 carbon atoms, a hydrocarbon group having 1 to 20 carbon atoms substituted with a halogen atom, an alkoxy group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an ester group having 2 to 20 carbon atoms, a silyl group having 3 to 20 carbon atoms, a halogen atom, or a cyano group.
The term "ester group" used herein means a hydrocarbyloxycarbonyl group.
Additionally, the term "silyl group" used herein means a tri(hydrocarbyl)silyl group.

In the ionomer of the present invention, T ¹ and T ² may be hydrogen atoms, T ³ may be a hydrogen atom or a methyl group, and T ⁴ may be an ester group having 2 to 20 carbon atoms.

The carbon skeleton of the hydrocarbon group, the hydrocarbon group substituted with an alkoxy group, the hydrocarbon group substituted with an ester group, the alkoxy group, the aryl group, the ester group and the silyl group for ^T1 to ^T4 may have a branch, a ring and/or an unsaturated bond.
The carbon number of the hydrocarbon group for T ¹ to T ⁴ may be 1 or more as long as the lower limit is 1, and may be 20 or less as the upper limit, or may be 10 or less.
The carbon number of the hydrocarbon group substituted with an alkoxy group for T ¹ to T ⁴ may be 1 or more as long as the lower limit is 1 or more, and may be 20 or less as the upper limit, or may be 10 or less.
The carbon number of the hydrocarbon group substituted with an ester group for T ¹ to T ⁴ may be 2 or more as the lower limit, and may be 20 or less as the upper limit, or may be 10 or less.
The lower limit of the number of carbon atoms in the alkoxy group for T ¹ to T ⁴ may be 1 or more, and the upper limit may be 20 or less, or may be 10 or less.
The lower limit of the number of carbon atoms in the aryl group for T ¹ to T ⁴ may be 6 or more, and the upper limit may be 20 or less, or may be 11 or less.
The lower limit of the number of carbon atoms in the ester group for T ¹ to T ⁴ may be 2 or more, and the upper limit may be 20 or less, or may be 10 or less.
The number of carbon atoms in the silyl group for ^T1 to ^T4 may be 3 or more as the lower limit, and 18 or less as the upper limit, or may be 12 or less. Examples of the silyl group include a trimethylsilyl group, a triethylsilyl group, a tri-n-propylsilyl group, a triisopropylsilyl group, a dimethylphenylsilyl group, a methyldiphenylsilyl group, and a triphenylsilyl group.

Specific examples of the acyclic monomer include acrylic esters such as (meth)acrylic esters and α-substituted acrylic esters.
The acrylic acid ester or α-substituted acrylic acid ester according to the present invention is a compound represented by the structural formula CH ₂ ═C(R ²¹ )CO ₂ (R ²² ). Here, R ²¹ is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, which may have a branch, a ring, and/or an unsaturated bond. R ²² is a hydrocarbon group having 1 to 20 carbon atoms, which may have a branch, a ring, and/or an unsaturated bond. Furthermore, R ²² may contain a heteroatom at any position.
Examples of the acrylic acid ester or α-substituted acrylic acid ester include an acrylic acid ester or α-substituted acrylic acid ester in which R ²¹ is a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, and an acrylic acid ester in which R ²¹ is a hydrogen atom or a methacrylic acid ester in which R ²¹ is a methyl group.
Specific examples of (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate, phenyl (meth)acrylate, toluyl (meth)acrylate, and benzyl (meth)acrylate.
Specific compounds include methyl acrylate, ethyl acrylate, n-butyl acrylate (nBA), isobutyl acrylate (iBA), t-butyl acrylate (tBA), and 2-ethylhexyl acrylate, and in particular may be n-butyl acrylate (nBA), isobutyl acrylate (iBA), and t-butyl acrylate (tBA).
The non-cyclic monomer may be of one type or of multiple types.

(ii) Cyclic monomers

[In general formula (2), R ¹ to R ¹² may be the same or different and are selected from the group consisting of a hydrogen atom, a halogen atom, and a hydrocarbon group having 1 to 20 carbon atoms; R ⁹ and R ¹⁰ , and R ¹¹ and R ¹² may each be bonded together to form a divalent organic group; and R ⁹ or R ¹⁰ and R ¹¹ or R ¹² may form a ring together.
Furthermore, n represents 0 or a positive integer, and when n is 2 or more, R ⁵ to R ⁸ may be the same or different in each repeating unit.]

Examples of the cyclic monomer include norbornene-based olefins, such as norbornene, vinylnorbornene, ethylidenenorbornene, norbornadiene, tetracyclododecene, tricyclo[4.3.0.1 ^2,5 ], tricyclo[4.3.0.1 ^2,5 ]dec-3-ene, and other compounds having a cyclic olefin skeleton, and may also include 2-norbornene (NB) and tetracyclo[6.2.1.1 ^3,6 .0 ^2,7 ]dodec-4-ene.

(1-4) Copolymer (P) that serves as the base resin for the ionomer
The copolymer (P) serving as the base resin of the ionomer used in the present invention is characterized in that it contains, as essential constituent units, structural units (A) derived from ethylene and/or an α-olefin having 3 to 20 carbon atoms and structural units (B) derived from a monomer having a carboxyl group and/or a dicarboxylic anhydride group, which are randomly copolymerized in a substantially linear manner.

The copolymer according to the present invention must contain at least one type of structural unit (A) and at least one type of structural unit (B), that is, at least two types of monomer units in total, and may also contain any other structural unit (C).
The structural units and the amounts of the structural units in the copolymer according to the present invention will be described below.
A structure derived from one molecule of each of ethylene and/or an α-olefin having 3 to 20 carbon atoms (A), a monomer having a carboxyl group and/or a dicarboxylic anhydride group (B), and an arbitrary monomer (C) is defined as one structural unit in the copolymer.
The amount of structural units is the ratio of each structural unit expressed in mol % when all structural units in the copolymer are taken as 100 mol %.

(i) Amount of structural units of ethylene and/or α-olefin having 3 to 20 carbon atoms (A):
The amount of the structural unit (A) according to the present invention is
The lower limit is 60.000 mol% or more, preferably 70.000 mol% or more, more preferably 80.000 mol% or more, even more preferably 85.000 mol% or more, still more preferably 90.000 mol% or more, particularly preferably 92.000 mol% or more;
The upper limit is selected from 97.999 mol% or less, preferably 97.990 mol% or less, more preferably 97.980 mol% or less, even more preferably 96.980 mol% or less, still more preferably 96.900 mol% or less, and particularly preferably 92.300 mol% or less.
From the viewpoint of good toughness of the copolymer, the amount of structural units derived from ethylene and/or an α-olefin (A) having 3 to 20 carbon atoms is preferably 60.000 mol % or more, and from the viewpoint of obtaining good transparency without increasing the crystallinity of the copolymer, it is preferably 97.999 mol % or less.

(ii) Amount of structural units of monomer (B) having a carboxyl group and/or a dicarboxylic anhydride group:
The amount of the structural unit (B) according to the present invention is
The lower limit is 2.0 mol% or more, preferably 2.9 mol% or more, and more preferably 5.1 mol% or more.
The upper limit is selected from 20.0 mol % or less, preferably 15.0 mol % or less, more preferably 10.0 mol % or less, further preferably 8.0 mol % or less, and particularly preferably 5.4 mol % or less.
From the viewpoint of good adhesion of the copolymer to different materials having high polarity, the amount of structural units derived from the monomer (B) having a carboxyl group and/or a dicarboxylic anhydride group is preferably 2.0 mol% or more, and from the viewpoint of good mechanical properties of the copolymer, the amount is preferably 20.0 mol% or less.
Furthermore, the monomer having a carboxyl group and/or a dicarboxylic anhydride group to be used may be used alone or in combination of two or more kinds.

(iii) Amount of structural units of optional monomer (C):
The amount of the structural unit (C) according to the present invention is
The lower limit is 0.001 mol% or more, preferably 0.010 mol% or more, more preferably 0.020 mol% or more, even more preferably 0.100 mol% or more, still more preferably 2.000 mol% or more, and particularly preferably 2.300 mol% or more.
The upper limit is selected from 20.000 mol % or less, preferably 15.000 mol % or less, more preferably 10.000 mol % or less, further preferably 5.000 mol % or less, and particularly preferably 2.900 mol % or less.
From the viewpoint of good flexibility of the copolymer, the amount of structural units derived from any monomer (C) is preferably 0.001 mol % or more, and from the viewpoint of good mechanical properties of the copolymer, it is preferably 20.000 mol % or less.
Furthermore, any of the monomers used may be used alone or in combination of two or more kinds.

(iv) Number of branches per 1,000 carbon atoms of the copolymer:
In the copolymer of the present invention, from the viewpoint of increasing the elastic modulus and obtaining sufficient mechanical properties, the number of methyl branches calculated by ¹³ C-NMR may be an upper limit of 50 or less, 5 or less, 1 or less, or 0.5 or less per 1,000 carbons, and the lower limit is not particularly limited, and the smaller the better. The number of ethyl branches may be an upper limit of 3.0 or less, 2.0 or less, 1.0 or less, or 0.5 or less per 1,000 carbons, and the lower limit is not particularly limited, and the smaller the better. Furthermore, the number of butyl branches may be an upper limit of 7.0 or less, 5.0 or less, 3.0 or less, or 0.5 or less per 1,000 carbons, and the lower limit is not particularly limited, and the smaller the better.

Method for measuring the amount of structural units derived from monomers having a carboxy group and/or a dicarboxylic anhydride group and non-cyclic monomers in the copolymer, and the number of branches:
The amount of structural units derived from the monomer having a carboxy group and/or a dicarboxylic anhydride group and the noncyclic monomer in the copolymer of the present invention, and the number of branches per 1,000 carbons can be determined using ¹³ C-NMR spectrum. ¹³ C-NMR is measured by the following method.

200 to 300 mg of a sample is placed in an NMR sample tube with an inner diameter of 10 mm together with 2.4 ml of a mixed solvent of o-dichlorobenzene (C ₆ H ₄ Cl ₂ ) and deuterated bromide benzene (C ₆ D ₅ Br) (C ₆ H ₄ Cl ₂ /C ₆ D ₅ Br = 2/1 (volume ratio)) and hexamethyldisiloxane, a chemical shift standard substance, and the tube is purged with nitrogen, sealed, and heated to dissolve to prepare a homogeneous solution to be used as the NMR measurement sample.
The NMR measurement is carried out at 120° C. using an AV400M NMR apparatus manufactured by Bruker Japan Ltd. equipped with a 10 mmφ cryoprobe.
¹³ C-NMR is measured by the inverse gate decoupling method at a sample temperature of 120° C., a pulse angle of 90°, a pulse interval of 51.5 seconds, and an accumulation number of 512 or more.
The chemical shifts are set to 1.98 ppm for the ¹³ C signal of hexamethyldisiloxane, and the chemical shifts of other ¹³ C signals are based on this.
In the obtained ^13C -NMR, signals specific to the monomers or branches of the multicomponent copolymer are identified and their intensities are compared, whereby the amount of structural units of each monomer in the copolymer and the number of branches can be analyzed. The positions of signals specific to the monomers or branches can be referred to publicly known materials, or can be independently identified depending on the sample. Such an analysis method is commonly known to those skilled in the art.

(v) Weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn):
The weight average molecular weight (Mw) of the copolymer according to the present invention is
The lower limit is usually 1,000 or more, preferably 6,000 or more,
The upper limit is usually 2,000,000 or less, preferably 1,500,000 or less, more preferably 1,000,000 or less, particularly preferably 800,000 or less, and most preferably 38,000 or less.
From the viewpoint of obtaining good physical properties such as mechanical strength and impact resistance of the copolymer, the Mw is preferably 1,000 or more, and from the viewpoint of obtaining good moldability of the copolymer due to an appropriate melt viscosity of the copolymer, the Mw is preferably 2,000,000 or less.

The ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the copolymer according to the present invention is usually in the range of 1.5 to 4.0, preferably 1.6 to 3.5, and more preferably 1.9 to 2.3. From the viewpoint of obtaining various good processabilities including molding of the copolymer, Mw/Mn is preferably 1.5 or more, and from the viewpoint of obtaining good mechanical properties of the copolymer, Mw/Mn is preferably 4.0 or less.
In the present invention, (Mw/Mn) may be expressed as a molecular weight distribution parameter.

The weight average molecular weight (Mw) and number average molecular weight (Mn) of the present invention are determined by gel permeation chromatography (GPC). The molecular weight distribution parameter (Mw/Mn) is calculated by determining the number average molecular weight (Mn) by gel permeation chromatography (GPC) and then calculating the ratio of Mw to Mn, Mw/Mn.

An example of the GPC measurement method according to the present invention is as follows.
(Measurement condition)
Model used: Waters 150C
Detector: FOXBORO MIRAN1A IR detector (measurement wavelength: 3.42 μm)
Measurement temperature: 140°C
Solvent: orthodichlorobenzene (ODCB)
Column: Showa Denko AD806M/S (3 columns)
Flow rate: 1.0 mL/min Injection volume: 0.2 mL
(Sample Preparation)
A 1 mg/mL solution of the sample is prepared using ODCB (containing 0.5 mg/mL BHT (2,6-di-t-butyl-4-methylphenol)), and dissolved at 140° C. for about 1 hour.
(Calculation of molecular weight (M))
The standard polystyrene method is used, and the conversion from retention volume to molecular weight is performed using a calibration curve of standard polystyrene that has been prepared in advance. The standard polystyrene used is, for example, Tosoh Corporation's (F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000) brand, Showa Denko's monodisperse polystyrene (S-7300, S-3900, S-1950, S-1460, S-1010, S-565, S-152, S-66.0, S-28.5, S-5.05, each 0.07 mg/mL solution), etc. A calibration curve is prepared by injecting 0.2 mL of a solution dissolved in ODCB (containing 0.5 mg/mL BHT) so that each is 0.5 mg/mL. The calibration curve is a cubic equation obtained by approximating the least squares method, or a quartic equation obtained by approximating the logarithm of the elution time and the molecular weight. The viscosity equation [η] = K × Mα used for conversion to molecular weight (M) uses the following values.
Polystyrene (PS): K=1.38×10 ⁻⁴ , α=0.7
Polyethylene (PE): K = 3.92 × 10 ^-4 , α = 0.733
Polypropylene (PP): K = 1.03 × 10 ^-4 , α = 0.78

(vi) Melting point (Tm, ° C.):
The melting point of the copolymer according to the present invention is indicated by the maximum peak temperature of the endothermic curve measured by a differential scanning calorimeter (DSC). When multiple peaks are shown in the endothermic curve obtained by DSC measurement, with heat flow (mW) on the vertical axis and temperature (°C) on the horizontal axis, the maximum peak temperature refers to the temperature of the peak with the maximum height from the baseline among the multiple peaks, and when there is only one peak, it refers to the temperature of that peak.
The melting point is preferably 50° C. to 140° C., more preferably 60° C. to 138° C., and most preferably 70° C. to 135° C. The lower limit of the melting point is determined from the viewpoint of good heat resistance, and the upper limit of the melting point is determined from the viewpoint of good adhesiveness.
In the present invention, the melting point can be determined from an absorption curve obtained by, for example, using a DSC (DSC7020) manufactured by SII Nanotechnology Inc., packing about 5.0 mg of a sample into an aluminum pan, heating the sample to 200° C. at 10° C./min, holding the sample isothermally at 200° C. for 5 minutes, lowering the sample to 20° C. at 10° C./min, holding the sample isothermally at 20° C. for 5 minutes, and then heating the sample again to 200° C. at 10° C./min.

(vii) Crystallinity (%):
In the copolymer of the present invention, the crystallinity observed by differential scanning calorimetry (DSC) is not particularly limited, but is preferably more than 0% and not more than 30%, more preferably more than 0% and not more than 25%, particularly preferably more than 5% and not more than 25%, and most preferably 5% or more and not more than 20%.
From the viewpoint of good toughness of the copolymer, the crystallinity is preferably more than 0%, and from the viewpoint of good transparency of the copolymer, the crystallinity is preferably 30% or less.
The degree of crystallinity is an index of transparency, and it can be determined that the lower the degree of crystallinity of a copolymer, the more excellent its transparency.
In the present invention, the degree of crystallinity can be determined, for example, by using a DSC (DSC7020) manufactured by SII Nanotechnology Inc., packing about 5.0 mg of a sample into an aluminum pan, heating it to 200° C. at 10° C./min, holding it isothermally at 200° C. for 5 minutes, lowering the temperature to 20° C. at 10° C./min, holding it isothermally at 20° C. for 5 minutes, and then heating it again to 200° C. at 10° C./min to determine the heat of fusion (ΔH) from the area of the melting endothermic peak obtained when the sample is heated, and dividing the heat of fusion by the heat of fusion of 293 J/g for a completely crystalline high density polyethylene (HDPE).

(viii) Molecular structure of the copolymer:
The molecular chain terminal of the copolymer according to the present invention may be a structural unit (A) of ethylene and/or an α-olefin having 3 to 20 carbon atoms, a structural unit (B) of a monomer having a carboxyl group and/or a dicarboxylic anhydride group, or a structural unit (C) of any monomer.

The copolymer according to the present invention may be a random copolymer, block copolymer, graft copolymer, etc., of a structural unit (A) of ethylene and/or an α-olefin having 3 to 20 carbon atoms, a structural unit (B) of a monomer having a carboxyl group and/or a dicarboxylic anhydride group, and a structural unit (C) of an arbitrary monomer. Among these, a random copolymer capable of containing a large amount of the structural unit (B) may be used.
An example of the molecular structure of a typical ternary copolymer (1) is shown below.

ランダム共重合体とは、上記に示した分子構造例（１）のエチレン及び／又は炭素数３～２０のα－オレフィンの構造単位（Ａ）とカルボキシル基及び／又はジカルボン酸無水物基を有するモノマーの構造単位（Ｂ）と任意のモノマーの構造単位（Ｃ）とが、ある任意の分子鎖中の位置においてそれぞれの構造単位を見出す確率が、その隣接する構造単位の種類と無関係な共重合体である。
上記のように、共重合体の分子構造例（１）は、エチレン及び／又は炭素数３～２０のα－オレフィンの構造単位（Ａ）とカルボキシル基及び／又はジカルボン酸無水物基を有するモノマーの構造単位（Ｂ）と任意のモノマーの構造単位（Ｃ）とが、ランダム共重合体を形成している。

A random copolymer is a copolymer in which the probability of finding the structural unit (A) of ethylene and/or an α-olefin having 3 to 20 carbon atoms, the structural unit (B) of a monomer having a carboxyl group and/or a dicarboxylic anhydride group, and the structural unit (C) of an arbitrary monomer at any position in a molecular chain of the above-mentioned molecular structure example (1) is independent of the type of the adjacent structural unit.
As described above, in the molecular structure example (1) of the copolymer, the structural unit (A) of ethylene and/or an α-olefin having 3 to 20 carbon atoms, the structural unit (B) of a monomer having a carboxyl group and/or a dicarboxylic anhydride group, and the structural unit (C) of an arbitrary monomer form a random copolymer.

For reference, the following molecular structure example (2) of a copolymer into which structural unit (B) of a monomer having a carboxyl group and/or a dicarboxylic anhydride group has been introduced by graft modification is also shown. A part of the copolymer in which structural unit (A) of ethylene and/or an α-olefin having 3 to 20 carbon atoms and structural unit (C) of any monomer are copolymerized is graft modified with structural unit (B) of a monomer having a carboxyl group and/or a dicarboxylic anhydride group.

While the random copolymerizability of a copolymer can be confirmed by various methods, methods for determining the random copolymerizability from the relationship between the comonomer content and melting point of the copolymer are described in detail in JP 2015-163691 A and JP 2016-079408 A. From the above documents, it can be determined that the randomness is low when the melting point (Tm, °C) of the copolymer is higher than -3.74 x [Z] + 130 (where [Z] is the comonomer content/mol%).

The copolymer according to the present invention, which is a random copolymer, preferably has a melting point (Tm, ° C.) measured by differential scanning calorimetry (DSC) and a total content [Z] (mol %) of the structural unit (B) of the monomer having a carboxyl group and/or a dicarboxylic anhydride group and the structural unit (C) of an arbitrary monomer, which satisfy the following formula (I):
50<Tm<-3.74×[Z]+130... (I)
The melting point (Tm, °C) of the copolymer is preferably −3.74 × [Z] + 130 (°C) or less from the viewpoint of enhancing random copolymerization and obtaining good mechanical properties such as impact strength, and the melting point is preferably 50°C or higher from the viewpoint of obtaining good heat resistance.
Furthermore, the copolymer according to the present invention is preferably produced in the presence of a transition metal catalyst, from the viewpoint of making the molecular structure of the copolymer into a linear chain.
It is known that the molecular structure of the copolymer varies depending on the production method, such as polymerization by a high-pressure radical polymerization process or polymerization using a metal catalyst.
The difference in molecular structure can be controlled by selecting the production method. However, for example, as described in JP2010-150532A, the molecular structure can also be estimated from the complex modulus measured by a rotational rheometer [see (3-1) below].
(2) Characteristic (b)
The structural unit (B) has a characteristic that at least a portion of the carboxyl groups and/or dicarboxylic anhydride groups is converted to a metal-containing carboxylate containing at least one metal ion selected from Groups 1, 2, or 12 of the Periodic Table.
(2-1) Metal Ion Examples of the metal ion of the carboxylate group include monovalent or divalent metal ions of a group selected from the group consisting of Groups 1, 2, and 12 of the periodic table, specifically, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and zinc (Zn) ions. Among these, at least one selected from the group consisting of Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , Cs ⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , and Zn ²⁺ is more preferred, and Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ca ²⁺ , and Zn ²⁺ are particularly preferred. More preferably, from the viewpoint of ease of handling, sodium (Na ⁺ ) or zinc (Zn ²⁺ ) ions are used.
The carboxylate group can be obtained, for example, by hydrolyzing or thermolyzing the ester groups of the copolymer, or by reacting the ester groups with a compound containing a metal ion of Group 1, Group 2, or Group 12 of the periodic table while hydrolyzing or thermolyzing the ester groups, thereby converting the ester group portion of the copolymer into a metal-containing carboxylate.
The metal ions may be of one type or of multiple types.

The content of the metal ions is preferably an amount that neutralizes at least a part or all of the carboxyl groups and/or dicarboxylic anhydride groups in the copolymer as the base resin, and the preferred degree of neutralization (average degree of neutralization) is 5 to 95 mol%, more preferably 10 to 90 mol%, and even more preferably 20 to 80 mol%.
The degree of neutralization can be determined from the ratio of the total molar amount of the valence×mol amount of the metal ion to the total molar amount of the carboxy groups that may be contained in the carboxy groups and/or dicarboxylic anhydride groups in the copolymer.
Since the dicarboxylic anhydride group opens its ring to form a dicarboxylic acid when forming a carboxylate, the total molar amount of the carboxyl groups is calculated assuming that there are 2 mol of carboxyl groups per mol of the dicarboxylic anhydride group. Also, assuming that 1 mol of a divalent metal ion such as Zn2 ⁺ can form a salt with 2 mol of carboxyl groups, the total molar amount of molecules with a degree of neutralization is calculated by 2 x mol amount.
A high degree of neutralization results in an ionomer with high tensile strength and tensile stress at break, and low tensile strain at break, but the melt flow rate (MFR) of the ionomer tends to be low. On the other hand, a low degree of neutralization results in an ionomer with a moderate MFR, but with a low tensile modulus and tensile stress at break, and high tensile strain at break.
The degree of neutralization can be calculated from the amount of carboxyl groups and/or dicarboxylic anhydride groups and the molar ratio of the added metal ions.
(3) Property (c)
(3-1)
This is a characteristic regarding the phase angle δ when the absolute value of the complex elastic modulus G ^* is 0.1 MPa. More specifically, this is a characteristic in which the phase angle δ when the absolute value of the complex elastic modulus G ^* is 0.1 MPa, as measured by a rotational rheometer, is 50 to 75 degrees.
The phase angle δ at an absolute value of 0.1 MPa of the complex modulus G ^* measured by a rotational rheometer is affected by both the molecular weight distribution and long chain branching. However, it is an index of the amount of long chain branching only for copolymers with Mw/Mn≦4, more preferably Mw/Mn≦3, and the more long chain branches contained in the molecular structure, the smaller the value of δ (|G ^* |=0.1 MPa).
When the Mw/Mn of the copolymer is 1.5 or more, the δ(|G ^* |=0.1 MPa) value does not exceed 75 degrees even if the molecular structure does not contain long chain branches.
More specifically, when the phase angle δ (|G ^* |=0.1 MPa) at an absolute value of 0.1 MPa of the complex modulus G ^* measured by a rotational rheometer is 50 degrees or more, the molecular structure of the copolymer is substantially a linear structure, i.e., a linear structure containing no long chain branches at all, or a structure containing a small amount of long chain branches that does not affect the mechanical strength.
Furthermore, when the phase angle δ (|G ^* | = 0.1 MPa) at an absolute value of 0.1 MPa of the complex modulus G ^* measured by a rotational rheometer is lower than 50 degrees, the molecular structure of the copolymer contains excessive long chain branches, and the mechanical strength is inferior.
In the ionomer of the present invention, from the viewpoint of improving the mechanical strength, the lower limit of the phase angle δ is preferably 51 degrees or more, more preferably 54 degrees or more, even more preferably 56 degrees or more, and still more preferably 58 degrees or more. The upper limit is not particularly limited, and the closer to 75 degrees the better, and it may be 70 degrees or less.

(3-2)
The method for measuring the complex elastic modulus is as follows.
The sample is placed in a 1.0 mm thick mold for hot pressing, preheated for 5 minutes in a hot press machine with a surface temperature of 180 ° C., and then repeatedly pressurized and depressurized to remove residual gas in the molten resin, and then pressurized at 4.9 MPa and held for 5 minutes. The sample is then transferred to a press machine with a surface temperature of 25 ° C., and cooled by holding at a pressure of 4.9 MPa for 3 minutes to create a press plate made of a sample with a thickness of about 1.0 mm. The press plate made of the sample is processed into a circular shape with a diameter of 25 mm to form a sample, and a Rheometrics ARES type rotational rheometer is used as a measuring device for dynamic viscoelastic properties to measure dynamic viscoelasticity under the following conditions in a nitrogen atmosphere.
Plate: φ25mm parallel plate Temperature: 160℃
Distortion: 10%
Measurement angular frequency range: 1.0×10 ⁻² to 1.0×10 ² rad/s
Measurement interval: 5 points/decade
The phase angle δ is plotted against the common logarithm log|G ^* | of the absolute value (Pa) of the complex elastic modulus G ^* , and the value of δ (degrees) at the point corresponding to log|G ^* |=5.0 is taken as δ (|G ^* |=0.1 MPa). When there is no point corresponding to log|G ^* |=5.0 among the measurement points, the δ value at log|G ^* |=5.0 is obtained by linear interpolation using two points around log|G ^* |=5.0. In addition, when all the measurement points are log|G ^* |<5, the δ value at log|G ^* |=5.0 is obtained by extrapolating the δ value using a quadratic curve using the values of the three points with the largest log|G ^* | value.

(4) Characteristics (d) to (f)
(4-1) Characteristic (d)
In the ionomer of the present invention, the melt flow rate (MFR) at a temperature of 190° C. and a load of 2.16 kg is 1 to 50 g/10 min, and preferably 2 to 20 g/10 min.
If the MFR is 50 g/10 min or more, the molecular weight decreases, the drawdown increases, and molding becomes difficult, whereas if the MFR is less than 1 g/10 min, the extrusion load becomes too large, making molding difficult.
The MFR can be increased or decreased by adjusting the molecular weight of the base copolymer (P).
(4-2) Property (e)

The ionomer of the present invention has an elastic recovery rate in a tensile test [see Example (8) below] of 65 to 100%. If the elastic recovery rate in a tensile test is less than 65%, the cushioning properties of the three-dimensional network structure may decrease.

(4-3) Characteristic (f)
In the ionomer of the present invention, the tensile modulus is 20 to 200 MPa, preferably 20 to 120 MPa.
If the tensile modulus exceeds 200 MPa, the sleeping comfort may be too hard when used as a bed mattress, whereas an ionomer with a tensile modulus of less than 20 MPa is difficult to manufacture.
(4-4) Others: Melting point of ionomer (Tm, °C)
The melting point (Tm, °C) of the ionomer according to the present invention is preferably 50° C. to 140° C., more preferably 60° C. to 138° C., and most preferably 70° C. to 135° C. From the viewpoint of good heat resistance, it is 50° C. or higher, and from the viewpoint of good adhesion, it is 140° C. or lower.
Of the ionomers related to the present invention, ionomers based on a binary copolymer consisting of only the structural unit (A) and the structural unit (B) preferably have a melting point of 90° C. or higher, more preferably 95° C. or higher, and even more preferably 100° C. or higher. Ionomers based on a ternary or higher multicomponent copolymer preferably have a melting point of less than 100° C., more preferably less than 95° C., and even more preferably less than 90° C.

Crystallinity (%):
In the ionomer of the present invention, the crystallinity observed by differential scanning calorimetry (DSC) is not particularly limited, but is preferably more than 0% and not more than 30%, more preferably more than 0% and not more than 25%, particularly preferably more than 5% and not more than 25%, and most preferably 7% or more and not more than 24%.
From the viewpoint of good toughness of the ionomer, the crystallinity is preferably more than 0%, and from the viewpoint of good transparency of the copolymer, the crystallinity is preferably 30% or less. Note that the crystallinity is an index of transparency, and it can be judged that the lower the crystallinity of the ionomer, the more excellent its transparency.
(5) Method for Producing Ionomer (5-1) Polymerization Catalyst The type of polymerization catalyst used for producing the copolymer of the present invention is not particularly limited as long as it is capable of copolymerizing the structural unit (A), the structural unit (B), and the optional structural unit (C). For example, a Group 5 to 11 transition metal compound having a chelating ligand can be mentioned.
Specific examples of preferred transition metals include vanadium atoms, niobium atoms, tantalum atoms, chromium atoms, molybdenum atoms, tungsten atoms, manganese atoms, iron atoms, platinum atoms, ruthenium atoms, cobalt atoms, rhodium atoms, nickel atoms, palladium atoms, and copper atoms. Among these, preferred are transition metals in Groups 8 to 11, more preferred are transition metals in Group 10, and particularly preferred are nickel (Ni) and palladium (Pd). These metals may be used alone or in combination.
Chelating ligands have at least two atoms selected from the group consisting of P, N, O, and S, and include ligands that are bidentate or multidentate, and are electronically neutral or anionic. Exemplary chelating ligand structures are given in the review by Brookhart et al. (Chem. Rev., 2000, 100, 1169).
The chelating ligand preferably includes a bidentate anionic P, O ligand. Examples of the bidentate anionic P, O ligand include phosphorus sulfonic acid, phosphorus carboxylic acid, phosphorus phenol, and phosphorus enolate. Other examples of the chelating ligand include a bidentate anionic N, O ligand. Examples of the bidentate anionic N, O ligand include salicylaldiminate and pyridine carboxylic acid. Other examples of the chelating ligand include a diimine ligand, a diphenoxide ligand, and a diamide ligand.

The structure of the metal complex obtained from the chelating ligand is represented by the following structural formula (a) or (b), in which an arylphosphine compound, an arylarsine compound, or an arylantimony compound, which may have a substituent, is coordinated.

[In the structural formula (a) and the structural formula (b),
M represents a transition metal belonging to any of Groups 5 to 11 of the periodic table of the elements, that is, various transition metals as described above.
X ¹ represents oxygen, sulfur, -SO ₃ - or -CO ₂ -.
^Y1 represents carbon or silicon.
n represents an integer of 0 or 1.
^E1 represents phosphorus, arsenic or antimony.
R ⁵³ and R ⁵⁴ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom.
Each R ⁵⁵ independently represents hydrogen, a halogen, or a hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom.
R ⁵⁶ and R ⁵⁷ are each independently hydrogen, halogen, a hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom, OR ⁵² , CO ₂ R ⁵² , CO ₂ M', C(O)N(R ⁵¹ ) ₂ , C(O)R ⁵² , SR ⁵² , SO ₂ R ⁵² , SOR ⁵² , OSO ₂ R ⁵² , P(O)(OR ⁵² ) _2-y (R ⁵¹ ) _y , CN, NHR ⁵² , N(R ⁵² ) ₂ , Si(OR ⁵¹ ) _3-x (R ⁵¹ ) _x , OSi(OR ⁵¹ ) _3-x (R ⁵¹ ) _x , NO ₂ , SO ₃ M', PO ₃ M' ₂ , P(O)(OR ⁵² ) ₂ M′ or an epoxy-containing group.
R ⁵¹ represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms.
R ⁵² represents a hydrocarbon group having 1 to 20 carbon atoms.
M′ represents an alkali metal, an alkaline earth metal, ammonium, a quaternary ammonium or a phosphonium; x represents an integer of 0 to 3; and y represents an integer of 0 to 2.
R ⁵⁶ and R ⁵⁷ may be bonded to each other to form an alicyclic ring, an aromatic ring, or a heterocyclic ring containing a heteroatom selected from oxygen, nitrogen, or sulfur, in which case the ring has 5 to 8 members and may or may not have a substituent on the ring.
^L1 represents a ligand coordinated to M.
In addition, R ⁵³ and L ¹ may be bonded to each other to form a ring.
More preferably, it is a transition metal complex represented by the following structural formula (c).

[In structural formula (c),
M represents a transition metal belonging to any of Groups 5 to 11 of the periodic table of the elements, that is, various transition metals as described above.
X ¹ represents oxygen, sulfur, -SO ₃ - or -CO ₂ -.
^Y1 represents carbon or silicon.
n represents an integer of 0 or 1.
^E1 represents phosphorus, arsenic or antimony.
R ⁵³ and R ⁵⁴ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom.
Each R ⁵⁵ independently represents hydrogen, a halogen, or a hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom.
R ⁵⁸ , R ⁵⁹ , R ⁶⁰ and R ⁶¹ each independently represent hydrogen, a halogen, a hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom, OR ⁵² , CO ₂ R ⁵² , CO ₂ M', C(O)N(R ⁵¹ ) ₂ , C(O)R ⁵² , SR ⁵² , SO ₂ R ⁵² , SOR ⁵² , OSO ₂ R ⁵² , P(O)(OR ⁵² ) _2-y (R ⁵¹ ) _y , CN, NHR ⁵² , N(R ⁵² ) ₂ , Si(OR ⁵¹ ) _3-x (R ⁵¹ ) _x , OSi(OR ⁵¹ ) _3-x (R ⁵¹ ) _x , NO ₂ , SO ₃ M', PO ₃ M' ₂ , P(O)(OR ⁵² ) ₂ represents M' or an epoxy-containing group.
R ⁵¹ represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms.
R ⁵² represents a hydrocarbon group having 1 to 20 carbon atoms.
M′ represents an alkali metal, an alkaline earth metal, ammonium, a quaternary ammonium or a phosphonium; x represents an integer of 0 to 3; and y represents an integer of 0 to 2.
In addition, a plurality of groups appropriately selected from R ⁵⁸ to R ⁶¹ may be bonded to each other to form an alicyclic ring, an aromatic ring, or a heterocyclic ring containing a heteroatom selected from oxygen, nitrogen, or sulfur, in which case the number of ring members is 5 to 8, and the ring may or may not have a substituent.
^L1 represents a ligand coordinated to M.
In addition, R ⁵³ and L ¹ may be bonded to each other to form a ring.

Here, typical examples of catalysts of Group 5 to 11 transition metal compounds having a chelating ligand include so-called SHOP catalysts and Drent catalysts.
The SHOP catalyst is a catalyst in which a phosphorus-based ligand having an aryl group which may have a substituent is coordinated to nickel metal (see, for example, WO 2010/050256).
Further, the Drent catalyst is a catalyst in which a phosphorus-based ligand having an aryl group which may have a substituent is coordinated to palladium metal (see, for example, JP-A-2010-202647).

(5-2) Polymerization method for copolymer:
Examples of the polymerization method include slurry polymerization in which at least a part of the produced polymer becomes a slurry in a medium, bulk polymerization in which liquefied monomer itself is the medium, gas phase polymerization in vaporized monomer, and high pressure ionic polymerization in which at least a part of the produced polymer is dissolved in monomer liquefied at high temperature and high pressure, etc. However, from the viewpoint of making the molecular structure linear, it is preferable that the polymer is produced in the presence of a transition metal catalyst.
The polymerization method may be any of batch polymerization, semi-batch polymerization, and continuous polymerization.
Furthermore, living polymerization may be carried out, or polymerization may be carried out while simultaneously causing chain transfer.
Furthermore, during the polymerization, a so-called chain shuttling agent (CSA) may be used in combination to carry out a chain shuttling reaction or coordinate chain transfer polymerization (CCTP).
Specific manufacturing processes and conditions are disclosed in, for example, Japanese Patent Application Laid-Open No. 2010-260913 and Japanese Patent Application Laid-Open No. 2010-202647.

(5-3) Method for introducing carboxyl groups and/or dicarboxylic anhydride groups into copolymers:
(i)
The method for introducing a carboxyl group and/or a dicarboxylic anhydride group into the copolymer according to the present invention is not particularly limited. A carboxyl group and/or a dicarboxylic anhydride group can be introduced by various methods within the scope of the present invention.
Examples of methods for introducing a carboxyl group and/or a dicarboxylic anhydride group include a method of directly copolymerizing a comonomer having a carboxyl group and/or a dicarboxylic anhydride group, and a method of copolymerizing another monomer and then introducing a carboxyl group and/or a dicarboxylic anhydride group by modification.

Methods for introducing carboxyl groups and/or dicarboxylic anhydride groups by modification include, for example, when introducing carboxylic acid, a method in which an acrylic ester is copolymerized and then hydrolyzed to convert it to a carboxylic acid, or a method in which t-butyl acrylate is copolymerized and then thermally decomposed to convert it to a carboxylic acid.

As an additive for promoting the reaction during the hydrolysis or thermal decomposition, a conventionally known acid/base catalyst may be used. The acid/base catalyst is not particularly limited, but examples of the acid/base catalyst that can be appropriately used include, for example, hydroxides of alkali metals or alkaline earth metals such as sodium hydroxide, potassium hydroxide, or lithium hydroxide, alkali metals such as sodium hydrogencarbonate or sodium carbonate, carbonates of alkaline earth metals, solid acids such as montmorillonite, inorganic acids such as hydrochloric acid, nitric acid, or sulfuric acid, and organic acids such as formic acid, acetic acid, benzoic acid, citric acid, paratoluenesulfonic acid, trifluoroacetic acid, or trifluoromethanesulfonic acid.
From the viewpoints of reaction promotion effect, cost, equipment corrosivity, etc., sodium hydroxide, potassium hydroxide, sodium carbonate, paratoluenesulfonic acid, and trifluoroacetic acid are preferred, and paratoluenesulfonic acid and trifluoroacetic acid are more preferred.
(ii)
However, the ionomer according to the present invention is preferably obtained by a heat conversion step in which an ethylene and/or C2-20 α-olefin/unsaturated carboxylic acid ester copolymer is heated to convert at least a part of the ester groups in the copolymer into a metal-containing carboxylate salt containing at least one metal ion selected from Groups 1, 2, and 12 of the periodic table.

In addition, in the heat conversion step,
(a) An ethylene and/or a-olefin having 2 to 20 carbon atoms/unsaturated carboxylic acid ester copolymer may be heated to hydrolyze or pyrolyze the ethylene and/or a-olefin having 2 to 20 carbon atoms/unsaturated carboxylic acid copolymer, and then reacted with a compound containing a metal ion of Group 1, Group 2, or Group 12 of the periodic table to convert the carboxylic acid in the ethylene and/or a-olefin having 2 to 20 carbon atoms/unsaturated carboxylic acid copolymer into the metal-containing carboxylate;
(b) An ethylene and/or C2-20 α-olefin/unsaturated carboxylic acid ester copolymer may be heated to hydrolyze or thermodecompose the ester groups of the copolymer, while reacting the copolymer with a compound containing a metal ion of Group 1, Group 2, or Group 12 of the periodic table, thereby converting the ester group moiety in the ethylene and/or C2-20 α-olefin/unsaturated carboxylic acid ester copolymer into the metal-containing carboxylate.

Additionally, the metal ion containing compound may be an oxide, hydroxide, carbonate, bicarbonate, acetate, formate, etc., of a metal from Group 1, 2, or 12 of the Periodic Table.
The compound containing metal ions may be supplied to the reaction system in the form of particles or fine powder, or may be dissolved or dispersed in water or an organic solvent and then supplied to the reaction system, or a master batch may be prepared using an ethylene/unsaturated carboxylic acid copolymer or an olefin copolymer as a base polymer and then supplied to the reaction system. In order to ensure smooth reaction, it is preferable to prepare a master batch and supply it to the reaction system.

Furthermore, the reaction with the compound containing metal ions may be carried out by melt kneading using various types of equipment such as a vent extruder, a Banbury mixer, a roll mill, etc., and the reaction may be a batch or continuous method. Since the reaction can be carried out smoothly by discharging water and carbon dioxide gas by-produced by the reaction using a degassing device, it is preferable to carry out the reaction continuously using an extruder equipped with a degassing device such as a vent extruder.
In the reaction with the compound containing metal ions, a small amount of water may be injected to promote the reaction.

The temperature at which the ethylene and/or C2-20 α-olefin/unsaturated carboxylic acid ester copolymer is heated may be any temperature at which the ester becomes a carboxylic acid. If the heating temperature is too low, the ester will not be converted to a carboxylic acid, and if the heating temperature is too high, decarbonylation and decomposition of the copolymer will proceed. Therefore, the heating temperature in the present invention is preferably in the range of 80°C to 350°C, more preferably 100°C to 340°C, even more preferably 150°C to 330°C, and even more preferably 200°C to 320°C.

The reaction time varies depending on the heating temperature and the reactivity of the ester group portion, but is usually 1 minute to 50 hours, more preferably 2 minutes to 30 hours, even more preferably 2 minutes to 10 hours, even more preferably 2 minutes to 3 hours, and particularly preferably 3 minutes to 2 hours.

In the above steps, the reaction atmosphere is not particularly limited, but it is generally preferable to carry out the steps under a flow of inert gas. Examples of inert gases that can be used include nitrogen, argon, and carbon dioxide atmospheres, and the inclusion of small amounts of oxygen or air is acceptable.

There are no particular limitations on the reactor used in the above steps, but any method that can substantially uniformly stir the copolymer may be used. A glass vessel or autoclave (AC) equipped with a stirrer may be used, or any conventionally known kneading machine such as a Brabender plastograph, a single-screw or twin-screw extruder, a high-intensity screw-type kneader, a Banbury mixer, a kneader, or a roll may be used.

(6) Additives The ionomer according to the present invention may contain additives such as conventionally known antioxidants, ultraviolet absorbers, lubricants, antistatic agents, colorants, pigments, crosslinking agents, foaming agents, nucleating agents, flame retardants, conductive materials, and fillers, as long as the additives do not deviate from the spirit and scope of the present invention.
(7) Molded Article The ethylene-based ionomer for a three-dimensional network structure of the present invention means an ethylene-based ionomer having properties suitable for molding a three-dimensional network structure, and since it has good moldability, it can be used to produce molded articles in various forms using any known molding method. In particular, molding into a three-dimensional network structure is preferable because it can take advantage of the characteristics of the ionomer of the present invention, such as an excellent balance between flexibility, elastic recovery, and moldability, but the use is not necessarily limited to molding of a three-dimensional network structure.
Here, the three-dimensional network structure refers to a network structure made of thermoplastic resin as a raw material or main raw material, in which a plurality of linear bodies are randomly entangled and partially thermally bonded. It is used for applications such as impact absorbing materials, cushioning materials, and sound absorbing building materials, and is suitable for use in cushions, sofas, beds, etc.
For details of the method for producing such a three-dimensional network structure, reference can be made to, for example, WO 2006/068120 and WO 01/68967.

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.
The physical properties in the examples and comparative examples were measured and evaluated by the methods described below.
In the table, "no data" means not measured, and "not detected" means below the detection limit.

<Measurement and Evaluation>
(1) Measurement of phase angle δ (|G ^* | = 0.1 MPa) at absolute value of complex modulus G ^* of 0.1 MPa 1) Preparation and measurement of sample The sample was placed in a 1.0 mm thick heat press mold, preheated for 5 minutes in a heat press machine with a surface temperature of 180 ° C., and then repeatedly pressurized and depressurized to degas the residual gas in the molten resin, and further pressurized at 4.9 MPa and held for 5 minutes. Then, it was transferred to a press machine with a surface temperature of 25 ° C. and cooled by holding it at a pressure of 4.9 MPa for 3 minutes to produce a press plate made of a sample with a thickness of about 1.0 mm. The press plate made of the sample was processed into a circle with a diameter of 25 mm to serve as a sample, and a Rheometrics ARES type rotational rheometer was used as a measuring device for dynamic viscoelastic properties, and dynamic viscoelasticity was measured under the following conditions in a nitrogen atmosphere.
Plate: φ25mm (diameter) parallel plate Temperature: 160℃
Distortion: 10%
Measurement angular frequency range: 1.0×10 ⁻² to 1.0×10 ² rad/s
Measurement interval: 5 points/decade
The phase angle δ was plotted against the common logarithm log|G ^* | of the absolute value (Pa) of the complex elastic modulus G ^* , and the value of δ (degrees) at the point corresponding to log|G ^* |=5.0 was taken as δ (|G ^* |=0.1 MPa). When there was no point corresponding to log|G ^* |=5.0 among the measurement points, the δ value at log|G ^* |=5.0 was obtained by linear interpolation using two points around log|G ^* |=5.0. In addition, when all the measurement points were log|G ^* |<5, the δ value at log|G ^* |=5.0 was extrapolated using a quadratic curve using the values of the three points from the largest log|G ^* | value.

(2) Measurement of weight average molecular weight (Mw) and molecular weight distribution parameter (Mw/Mn) The weight average molecular weight (Mw) was determined by gel permeation chromatography (GPC). The molecular weight distribution parameter (Mw/Mn) was calculated from the ratio of Mw to Mn, Mw/Mn, by determining the number average molecular weight (Mn) by gel permeation chromatography (GPC).
The measurements were carried out according to the following procedures and conditions.

1) Sample pretreatment When a sample contains a carboxylic acid group, the sample is subjected to an esterification treatment such as methyl esterification using diazomethane, tetramethylsilane (TMS) diazomethane, etc., before being used for measurement. When a sample contains a carboxylate group, the sample is subjected to an acid treatment to modify the carboxylate group to a carboxylic acid group, and then the above-mentioned esterification treatment is performed before being used for measurement.

2) Preparation of sample solution 3 mg of sample and 3 mL of o-dichlorobenzene were weighed into a 4 mL vial, and the vial was capped with a screw cap and a Teflon (registered trademark) septum, and then shaken for 2 hours at 150°C using a Senshu Scientific SSC-7300 high-temperature shaker. After shaking, it was visually confirmed that there were no insoluble components.

3) Measurement One Showdex HT-G and two Showa Denko high temperature GPC columns HT-806M were connected to a Waters Alliance GPCV2000 model, and measurements were performed using o-dichlorobenzene as an eluent at a temperature of 145° C. and a flow rate of 1.0 mL/min.

4) Calibration curve The column was calibrated using monodisperse polystyrene (S-7300, S-3900, S-1950, S-1460, S-1010, S-565, S-152, S-66.0, S-28.5, S-5.05, each 0.07 mg/ml solution), n-eicosane and n-tetracontane manufactured by Showa Denko under the same conditions as above, and the elution time and the logarithm of the molecular weight were approximated by a fourth-order equation. The polystyrene molecular weight (M _PS ) and the polyethylene molecular weight (M _PE ) were converted using the following equation.
_MPE = 0.468 × _MPS

(3) Melt flow rate (MFR)
The MFR was measured in accordance with Table 1-Condition 7 of JIS K-7210 (1999) at a temperature of 190° C. and a load of 2.16 kg.

(4) Tensile Modulus of Elasticity A sample was prepared into a sheet having a thickness of 1 mm by the method described in JIS K7151 (1995) (cooling method A), and this was punched out to prepare a small 5B-type test piece described in JIS K7162 (1994). A tensile test was carried out at a temperature of 23° C. in accordance with JIS K7161 (1994) to measure the tensile modulus of elasticity. The test speed was 10 mm/min.

(5) Melting point and crystallinity The melting point is indicated by the peak temperature of the endothermic curve measured by a differential scanning calorimeter (DSC). The measurement was performed using a DSC (DSC7020) manufactured by SII Nano Technology Co., Ltd. under the following measurement conditions.
About 5.0 mg of the sample was packed in an aluminum pan, heated to 200° C. at 10° C./min, held at 200° C. for 5 minutes, and then cooled to 30° C. at 10° C./min. After holding at 30° C. for 5 minutes, the sample was heated again at 10° C./min. The maximum peak temperature in the absorption curve was taken as the melting point Tm, and the heat of fusion (ΔH) was calculated from the area of the melting endothermic peak. The heat of fusion was divided by the heat of fusion of 293 J/g for a completely crystalline high density polyethylene (HDPE) to calculate the crystallinity (%).

(6) Measurement of the structural unit amount and the number of methyl branches per 1,000 carbon atoms of a monomer having a carboxyl group and/or a dicarboxylic anhydride group, and an arbitrary monomer 1) When a carboxylate group was contained in the sample, the sample was subjected to an acid treatment to modify the carboxylate group to a carboxylate group before use in the measurement.

2) Method for measuring the amount of structural units derived from monomers having a carboxy group and/or a dicarboxylic anhydride group, and non-cyclic monomers, and the number of branches per 1,000 carbons The amount of structural units derived from monomers having a carboxy group and/or a dicarboxylic anhydride group, and non-cyclic monomers in the multicomponent copolymer of the present invention, and the number of branches per 1,000 carbons, can be determined using ¹³ C-NMR spectrum. ¹³ C-NMR was measured by the following method.
200 to 300 mg of the sample was placed in an NMR sample tube with an inner diameter of 10 mm together with 2.4 ml of a mixed solvent of o-dichlorobenzene (C ₆ H ₄ Cl ₂ ) and deuterated bromide benzene (C ₆ D ₅ Br) (C ₆ H ₄ Cl ₂ /C ₆ D ₅ Br = 2/1 (volume ratio)) and hexamethyldisiloxane as a chemical shift standard substance, and the tube was purged with nitrogen, sealed, and heated to dissolve to prepare a homogeneous solution for use as an NMR measurement sample.
The NMR measurement was carried out at 120° C. using an AV400M NMR apparatus (Bruker Japan) equipped with a 10 mmφ cryoprobe.
¹³ C-NMR was measured by the inverse gate decoupling method at a sample temperature of 120° C., a pulse angle of 90°, a pulse interval of 51.5 seconds, and an accumulation number of 512 or more.
The chemical shifts were set to 1.98 ppm for the ¹³ C signal of hexamethyldisiloxane, and the chemical shifts of other ¹³ C signals were based on this.

1) Sample pretreatment When a sample contains a carboxylate group, the sample was subjected to an acid treatment to convert the carboxylate group into a carboxyl group before measurement. When a sample contains a carboxyl group, an esterification treatment such as methyl esterification using diazomethane or trimethylsilyl (TMS) diazomethane may be appropriately performed.

2) Calculation of the amount of structural units derived from monomers having a carboxy group and/or a dicarboxylic anhydride group, and non-cyclic monomers <Ethylene/t-butyl acrylate (E/tBA)>
The quaternary carbon signal of the t-butyl acrylate group of tBA is detected at 79.6 to 78.8 in the ¹³ C-NMR spectrum. Using these signal intensities, the amount of comonomer was calculated from the following formula.
Total amount of tBA (mol%) = I(tBA) x 100/[I(tBA) + I(E)]
Here, I(tBA) and I(E) are quantities represented by the following formulas.
I(tBA)=I _79.6-78.8
I(E) = (I _180.0-135.0 + I _120.0-5.0 - I(tBA) x 7) / 2

<Ethylene/t-butyl acrylate/n-butyl acrylate
(E/tBA/nBA)>
The quaternary carbon signal of the t-butyl acrylate group of tBA is detected at 79.6 to 78.8 ppm in the ¹³ C-NMR spectrum, and the methylene signal of the butoxy group of nBA is detected at 64.1 to 63.4 ppm. Using these signal intensities, the amount of comonomer was calculated from the following formula.
Total amount of tBA (mol%) = I(tBA) x 100/[I(tBA) + I(nBA) + I(E)]
Total amount of nBA (mol%) = I(nBA) x 100/[I(tBA) + I(nBA) + I(E)]
Here, I(tBA), I(nBA), and I(E) are quantities represented by the following formulas, respectively.
I(tBA)=I _79.6-78.8
I(nBA)=I _64.1-63.4
I(E) = (I _180.0-135.0 + I _120.0-5.0 - I(nBA) x 7 - I(tBA) x 7) / 2

<Ethylene/t-butyl acrylate/i-butyl acrylate
(E/tBA/iBA)>
The quaternary carbon signal of the t-butyl acrylate group of tBA is detected at 79.6 to 78.8 ppm in the ¹³ C-NMR spectrum, the methylene signal of the isobutoxy group of iBA is detected at 70.5 to 69.8 ppm, and the methyl signal of the isobutoxy group is detected at 19.5 to 18.9 ppm. Using these signal intensities, the amount of comonomer was calculated from the following formula.
Total amount of tBA (mol%)=I(tBA)×100/[I(tBA)+I(iBA)+I(E)]
Total amount of iBA (mol%) = I(iBA) x 100 / [I(tBA) + I(iBA) + I(E)]
Here, I(tBA), I(iBA), and I(E) are quantities represented by the following formulas, respectively.
I(tBA)=I _79.6-78.8
I(iBA) = (I _70.5-69.8 + I _19.5-18.9 ) / 3
I(E) = (I _180.0-135.0 + I _120.0-5.0 - I(iBA) x 7 - I(tBA) x 7) / 2

<Ethylene/t-butyl acrylate/2-norbornene (E/tBA/NB)>
The quaternary carbon signal of the t-butyl acrylate group of tBA is detected at 79.6 to 78.8 ppm in the ¹³ C-NMR spectrum, and the methine carbon signal of NB is detected at 41.9 to 41.1 ppm. Using these signal intensities, the amount of comonomer was calculated from the following formula.
Total amount of tBA (mol%)=I(tBA)×100/[I(tBA)+I(NB)+I(E)]
Total amount of NB (mol%)=I(NB)×100/[I(tBA)+I(NB)+I(E)]
Here, I(tBA), I(NB), and I(E) are quantities represented by the following formulas, respectively.
I(tBA)=I _79.6-78.8
I(NB)=(I _41.9-41.1 )/2
I(E) = (I _180.0-135.0 + I _120.0-5.0 - I(NB) x 7 - I(tBA) x 7) / 2

When the amount of structural units of each monomer is indicated by "<0.1" including an inequality sign, this means that it is present as a structural unit in the multicomponent copolymer, but the amount is less than 0.1 mol%, taking into account significant digits.

3) Calculation of the number of branches per 1,000 carbons Multicomponent copolymers include isolated types in which a branch exists singly in the main chain, and composite types (face-to-face types in which branches face each other via the main chain, branched-branch types in which branches exist within a branched chain, and chain types).
The following is an example of the structure of an ethyl branch: In the example of the facing type, R represents an alkyl group.

The number of branches per 1,000 carbons is calculated by substituting either I(B1), I(B2), or I(B4) below into the I (branch) term in the following formula. B1 represents methyl branches, B2 represents ethyl branches, and B4 represents butyl branches. The number of methyl branches is calculated using I(B1), the number of ethyl branches using I(B2), and the number of butyl branches using I(B4).
Number of branches (per 1,000 carbons) = I (branches) x 1000/I (total)
Here, I(total), I(B1), I(B2), and I(B4) are quantities expressed by the following formulas.
I (total) = I _{180.0 to 135.0} + I _{120.0 to 5.0}
I(B1) = (I _20.0-19.8 + I _33.2-33.1 + I _37.5-37.3 ) / 4
I(B2) = I _8.6-7.6 + I _11.8-10.5
I (B4) = I _{14.3 to 13.7} - I _{32.2 to 32.0}
Here, I is the integrated intensity, and the subscript number of I indicates the range of chemical shifts. For example, I _180.0-135.0 indicates the integrated intensity of the ¹³ C signal detected between 180.0 ppm and 135.0 ppm.
The attribution was based on the non-patent literature Macromolecules 1984, 17, 1756-1761 and Macromolecules 1979, 12, 41.
In addition, when each branch number is indicated by "<0.1" including an inequality sign, it means that it is present as a structural unit in the multi-component copolymer, but the amount is less than 0.1 mol% taking into account significant figures. In addition, "not detected" means that it is below the detection limit.

(7) Infrared Absorption Spectrum The sample was melted at 180° C. for 3 minutes and compression molded to prepare a film having a thickness of about 50 μm. This film was analyzed by Fourier transform infrared spectroscopy to obtain an infrared absorption spectrum.
Product name: FT/IR-6100 manufactured by JASCO Corporation Measurement method: Transmission method Detector: TGS (Triglycine sulfate)
Number of times of accumulation: 16 to 512 times Resolution: 4.0 cm ^-1
Measurement wavelength: 5000 to 500 cm ^-1

(8) Elastic recovery rate 1) Method for preparing test pieces for samples A sheet having a thickness of 1 mm was prepared as a sample by the method described in JIS K7151 (1995) (cooling method A), and this was punched out to prepare a small 5B type test piece described in JIS K7162 (1994).
2) Elastic recovery rate measurement method The initial grip distance of the tensile tester Tensilon RTG-1250 (manufactured by A & D Co., Ltd.) was set to 21 mm as A, a 5B-type small test piece was attached, and marks were made on the top and bottom of the test piece. The grip movement amount was set to B, and the tester was raised at a speed of 10 mm/min until B reached about 24 mm, then stopped and held in that state for 1 minute. Thereafter, the lower grip was released and the test piece was allowed to contract for 3 minutes. The test piece was removed from the tester, and the distance between the marks on the top and bottom of the test piece before the grips were raised was set as the grip distance C after the test, and C (mm) was measured. The elastic recovery rate was calculated from the above A, B, and C using the following formula.
Elastic recovery rate (%) = [{1 - (after-test gripper distance C - initial gripper distance A) / gripper movement amount B)] x 100
The test conditions were a temperature of 23° C. and a relative humidity of 50% RH.

<Synthesis of metal complexes>

(1) Synthesis of B-27DM/Ni Complex The B-27DM/Ni complex was prepared according to Synthesis Example 4 described in WO 2010/050256, using the following 2-bis(2,6-dimethoxyphenyl)phosphano-6-pentafluorophenylphenol ligand (B-27DM). A nickel complex (B-27DM/Ni) was synthesized in which B-27DM and Ni(COD) ₂ reacted in a 1:1 ratio using bis(1,5-cyclooctadiene)nickel(0) (referred to as Ni(COD) ₂ ) in accordance with Example 1 of WO 2010/050256.

以下のスキームに従って配位子Ｂ－４２３を合成した。
なお、以降の化学式中、－ＯＭＯＭとはメトキシメトキシ基（－ＯＣＨ_２ＯＣＨ_３）を表す。 (2) Synthesis of B-423/Ni complex 1) Synthesis of ligand B-423: 2-bis(2,6-dimethoxyphenyl)phosphano-6-(2,6-diisopropylphenyl)phenol

Ligand B-423 was synthesized according to the following scheme.
In the following chemical formulas, --OMOM represents a methoxymethoxy group (--OCH ₂ OCH ₃ ).

(i) Synthesis of Compound 2 Compound 2 was synthesized according to Synthesis Example 1(1) of WO 2010/050256.

(ii) Synthesis of Compound 3 To a solution of compound 2 (2.64 g, 10.0 mmol) in THF (5.0 ml) was added iso-PrMgCl (2 M, 5.25 ml) at 0° C. The reaction mixture was stirred at 25° C. for 1 hour, and then PCl ₃ (618 mg, 4.50 mmol) was added at −78° C.
The reaction mixture was warmed to 25° C. over 3 hours to give a yellow suspension. The solvent was removed under reduced pressure to give a yellow solid. This mixture was used in the next reaction without purification.

(iii) Synthesis of Compound 5 To a solution of compound 4 (30 g, 220 mmol) in THF (250 ml) was added n-BuLi (2.5 M, 96 ml) at 0° C., and the mixture was stirred for 1 hour at 30° C. To this solution was added B(O ⁱ Pr) ₃ (123 g, 651 mmol) at −78° C., and the mixture was stirred for 2 hours at 30° C. to obtain a white suspension.
Hydrochloric acid (1M) was added to adjust the pH to 6-7, and the organic layer was concentrated to give a mixture.
The resulting mixture was washed with petroleum ether (80 ml) to give 26 g of compound 5.

(iv) Synthesis of Compound 7 Compound 5 (5.00 g, 27.5 mmol), compound 6 (4.42 g, 18.3 mmol), Pd ₂ (dba) ₃ (168 mg, 0.183 mmol), s-Phos (2-Dicyclohexylphosphino-2',6'-dimethoxybiphenyl) (376 mg, 0.916 mmol), and K ₃ PO ₄ (7.35 g, 34.6 mmol) were weighed into a reaction vessel, and toluene (40 ml) was added. This solution was reacted at 110°C for 12 hours to obtain a black suspension.
Water (50 ml) was added, and the mixture was extracted with ethyl acetate (55 ml x 3).
The organic layer was washed with brine (20 ml) and dried over Na ₂ SO ₄ .
The organic layer was filtered, the solvent was distilled off under reduced pressure, and the residue was purified by a silica gel column to obtain 1.3 g of compound 7 as an oily substance.

(v) Synthesis of Compound 8 To a solution of Compound 7 (6.5 g, 22 mmol) obtained by repeating the above step (iv) in THF (40 ml), n-BuLi (2.5 M, 9.15 ml) was added dropwise at 0° C., the temperature was raised to 30° C., and the mixture was stirred for 1 hour. This reaction solution was cooled to −78° C., CuCN (2.1 g, 23 mmol) was added, and the mixture was stirred at 30° C. for 1 hour.
The reaction solution was cooled to −78° C., and a solution of compound 3 (6.7 g, 20 mmol) obtained by repeating the above step (ii) in THF (40 ml) was added thereto, followed by stirring at 30° C. for 12 hours to obtain a white suspension.
To the suspension was added H ₂ O (50 ml) resulting in a white precipitate.
The white precipitate was collected by filtration and dissolved in dichloromethane (20 ml), and aqueous ammonia (80 ml) was added thereto and stirred for 3 hours.
The product was extracted with dichloromethane (50 ml x 3), dehydrated _{with Na2SO4} , and concentrated to obtain a yellow oily substance, which was purified by a silica gel column to obtain 2.9 g of compound 8.

(vi) Synthesis of B-423 To a solution of compound 8 (2.9 g, 4.8 mmol) in dichloromethane (20 ml) was added HCl/ethyl acetate (4 M, 50 ml) at 0° C., and the mixture was stirred at 30° C. for 2 hours to obtain a pale yellow solution.
The solvent was removed under reduced pressure, and dichloromethane (50 ml) was added.
Washing with saturated aqueous _NaHCO3 solution (100 ml) gave 2.5 g of B-423.
The NMR assignment values of the obtained ligand B-423 are shown below.
[NMR]
^1H NMR ( _CDCl3 , δ, ppm): 7.49 (t, 1H), 7.33 (t, 1H), 7.22 (m, 4H), 6.93 (d, 1H), 6.81 (t, 1H), 6.49 (dd, 4H), 6.46 (br, 1H), 3.56 (s, 12H), 2.63 (sept, 2H), 1.05 (d, 6H), 1.04 (d, 6H);
^31P NMR ( _CDCl3 , δ, ppm): -61.6 (s).

2) Synthesis of B-423/Ni Complex The B-423/Ni complex was synthesized using the B-423 ligand and bisacetylacetonate nickel(II) [referred to as Ni(acac) ₂ ] in accordance with Example 1 of WO 2010/050256, in which B-423 and Ni(acac) ₂ reacted in a 1:1 ratio to synthesize a nickel complex (B-423/Ni).

(Production Examples 1 and 2): Production of ionomer base resin precursor
Using a transition metal complex (B-27DM/Ni complex or B-423/Ni complex), an ethylene/t-butyl acrylate/i-butyl acrylate copolymer and an ethylene/t-butyl acrylate/2-norbornene copolymer were produced. With reference to Production Example 1 or Production Example 3 described in JP 2016-79408 A, the copolymer was produced in dry toluene in the presence of tri-n-octylaluminum (TNOA) and a metal complex species (catalyst). As appropriately changed production conditions, the metal complex species (catalyst), the amount of metal complex, the amount of tri-n-octylaluminum (TNOA), the amount of toluene, the type of comonomer 1, and the type of comonomer 2 are shown in Table 1; the amount of comonomer 1, the amount of comonomer 2, the ethylene partial pressure, the polymerization temperature, and the polymerization time are shown in Table 2. The production results are also shown in Table 3.

Furthermore, the contents of comonomers 1 and 2 and the physical properties of the copolymer obtained are shown in Tables 4 and 5. In Tables 4 and 5, base resin precursor 1 refers to the copolymer obtained by Production Example 1, and base resin precursor 2 refers to the base resin precursor obtained by Production Example 2. However, "not detected" in the tables means below the detection limit.

(Production Examples 3 and 4): Production of Ionomer Base Resin
In a 500 ml separable flask, 40 g of the obtained base resin precursor 1 or 2 (copolymer of Production Example 1 or 2), 0.8 g of paratoluenesulfonic acid monohydrate, and 185 ml of toluene were added and stirred at 105 ° C. for 4 hours. 185 ml of ion-exchanged water was added, stirred, and allowed to stand, and then the aqueous layer was extracted. Thereafter, the addition and extraction of ion-exchanged water was repeated until the pH of the extracted aqueous layer became 5 or more. The solvent was removed from the remaining solution by distillation under reduced pressure, and the solution was dried until it reached a constant weight. Base resin 1 (Production Example 3) was obtained from base resin precursor 1, and base resin 2 (Production Example 4) was obtained from base resin precursor 2.
In the IR spectrum of the obtained resin, the disappearance of the peak at around 850 cm ⁻¹ due to the tBu group, the decrease of the peak at around 1730 cm ⁻¹ due to the carbonyl group of the ester, and the increase of the peak at around 1700 cm ⁻¹ due to the carbonyl group of the carboxylic acid (dimer) were observed.
As a result, decomposition of t-butyl ester and generation of carboxylic acid were confirmed, and ionomer base resins 1 and 2 were obtained. The physical properties of the obtained resins are shown in Tables 6 to 8. Here, E in the tables means ethylene, AA means acrylic acid monomer unit, NB means 2-norbornene monomer unit, and iBA means i-butyl acrylate monomer unit. However, "not detected" in the tables means below the detection limit.

<Production Examples 5 and 6): Production of ionomer>
1) Preparation of Na ion supply source 22 g of ethylene/methacrylic acid (MAA) copolymer (manufactured by Dow Mitsui Polychemical Co., Ltd., brand: Nucrel N1050H) and 18 g of sodium carbonate were added to a Labo Plastomill: Roller Mixer R60 type manufactured by Toyo Seiki Co., Ltd. equipped with a small mixer with a capacity of 60 ml, and the mixture was kneaded at 180° C. and 40 rpm for 3 minutes to prepare a Na ion supply source.

2) Preparation of Zn ion source 21.8 g of ethylene/methacrylic acid (MAA) copolymer (manufactured by Dow Mitsui Polychemical Co., Ltd., brand: Nucrel N1050H), 18 g of zinc oxide, and 0.2 g of zinc stearate were added to a Labo Plastomill: Roller Mixer R60 type manufactured by Toyo Seiki Co., Ltd. equipped with a small mixer with a capacity of 60 ml, and kneaded at 180° C. and 40 rpm for 3 minutes to prepare a Zn ion source.

3) Preparation of ionomer 40 g of base resin 1 or 2 was added to a Labo Plastomill (Roller Mixer R60 type) manufactured by Toyo Seiki Co., Ltd., equipped with a small mixer with a capacity of 60 ml, and dissolved by kneading for 3 minutes at 160° C. and 40 rpm. Thereafter, a Na ion source or a Zn ion source was added so as to achieve a desired degree of neutralization, and kneading was performed for 5 minutes at 250° C. and 40 rpm.
In the IR spectrum of the obtained resin, the peak at about 1700 cm ^-1 derived from the carbonyl group of the carboxylic acid (dimer) was decreased, and the peak at about 1560 cm ^-1 derived from the carbonyl group of the carboxylate salt group was increased. It was confirmed that an ionomer with the desired degree of neutralization had been produced from the decrease in the peak at about 1700 cm ^-1 derived from the carbonyl group of the carboxylic acid (dimer).
Ionomer Example 1 was obtained from base resin 1 (Production Example 5), and ionomer Example 2 was obtained from base resin 2 (Production Example 6).
The physical properties of the obtained ionomer are shown in Tables 9 and 10.

(Comparative product 1): Ethylene/methacrylic acid (E/MAA)-based binary ionomer An ionomer resin (HIMILAN HIM1555, manufactured by Dow Mitsui Polychemical Co., Ltd.), which is a copolymer of ethylene, methacrylic acid, and sodium methacrylate and produced by a high-pressure radical process, was used as a reference ionomer. The physical properties are shown in Tables 9 and 10.

(Comparative product 2): Polyethylene manufactured by Japan Polyethylene Co., Ltd., brand: KS560T, was used as a reference polyethylene. The physical properties are shown in Tables 9 and 10.

(Comparative product 3): Polyethylene manufactured by Japan Polyethylene Co., Ltd., brand: KF360T, was used as the reference polyethylene. The physical properties are shown in Tables 9 and 10.
In the table, E means ethylene, AA means acrylic acid monomer unit, NB means 2-norbornene monomer unit, iBA means i-butyl acrylate monomer unit, and MAA means methacrylic acid monomer unit.
Also, Na ⁺ /(M)AA is the number of moles of sodium ions per mole of (meth)acrylic acid monomer unit expressed as a percentage.
In addition, 2×Zn ²⁺ /(M)AA is the number of moles of zinc ions (divalent) in terms of monovalent form per mole of (meth)acrylic acid monomer units, i.e., twice the number of moles of zinc ions (divalent) expressed as a percentage.

<Consideration of the results of the Examples and Comparative Examples>
[evaluation]
As described above, from the results shown in Table 10, when comparing ionomer examples 1-2 and comparison examples 1-3, the comparison examples, ethylene-based ionomer (comparison example 1) and polyethylene (comparison examples 2-3), have a poorer balance of flexibility and elastic recovery than the ethylene-based ionomer examples 1-2.
Furthermore, from the results shown in Table 10, it was confirmed that, compared with comparison products 1 to 3, embodiment products 1 and 2, which are ethylene-based ionomers for three-dimensional network structures according to the present invention, have a good balance of flexibility, elastic recovery, and moldability.

According to the present invention, it is possible to provide a molded article, particularly a three-dimensional network structure, made of an ethylene-based ionomer that is suitable for use as a bed mat or the like.
That is, a molded article using the ethylene-based ionomer of the present invention has an excellent balance between flexibility and elastic recovery, and is therefore of great industrial utility.

Claims (8)

The following characteristics (a) to (f):
(a) a copolymer (P) containing, as essential constituent units, a structural unit (A) derived from ethylene and/or an α-olefin having 3 to 20 carbon atoms and a structural unit (B) derived from a monomer having a carboxyl group and/or a dicarboxylic anhydride group, wherein the structural unit (A) essentially contains ethylene, is used as a base resin;
(b) at least a part of the carboxyl groups and/or dicarboxylic anhydride groups in the structural unit (B) is converted to a metal-containing carboxylate containing at least one metal ion selected from Group 1, Group 2, or Group 12 of the Periodic Table;
(c) the phase angle δ at an absolute value of 0.1 MPa of the complex modulus G ^* measured by a rotational rheometer is 50 to 75 degrees;
(d) a melt flow rate (MFR) of 1 to 50 g/10 min at a temperature of 190° C. and a load of 2.16 kg;
(e) an elastic recovery rate in a tensile test of 65 to 100%; and (f) a tensile modulus of elasticity of 20 to 200 MPa;
The ethylene-based ionomer for three-dimensional network structures is an ionomer resin that satisfies the above requirements. The ethylene-based ionomer for a three-dimensional network structure according to claim 1, wherein the number of methyl branches of the copolymer (P) calculated by ¹³ C-NMR is 50 or less per 1,000 carbon atoms. The ethylene-based ionomer for three-dimensional network structures according to claim 1 or 2, characterized in that the copolymer (P) contains 2 to 20 mol % of the structural unit (B) in the copolymer. The ethylene-based ionomer for three-dimensional network structures according to any one of claims 1 to 3, characterized in that the structural unit (A) is a structural unit derived from ethylene. The ethylene-based ionomer for three-dimensional network structures according to any one of claims 1 to 4, characterized in that the copolymer (P) is produced using a transition metal catalyst containing a transition metal of groups 8 to 11 of the periodic table. The ethylene-based ionomer for three-dimensional network structures according to claim 5, characterized in that the transition metal catalyst is a transition metal catalyst consisting of a phosphorus sulfonic acid or phosphorus phenol ligand and nickel or palladium. A molded article made of an ethylene-based ionomer according to any one of claims 1 to 6. The molded body according to claim 7, wherein the molded body is a three-dimensional network structure.