JP7782630B2 - Resin for glass laminates - Google Patents

Description

The present invention relates to a resin for glass laminates that uses a new ionomer.

Ethylene-based ionomers are resins that use ethylene-unsaturated carboxylic acid copolymers as the base resin and are intermolecularly bonded by metal ions such as sodium and zinc (Patent Document 1). They are characterized by their toughness, elasticity, flexibility, abrasion resistance, transparency, etc.
Currently, known commercially available ethylene-based ionomers include "Surlyn (registered trademark)," a sodium salt or zinc salt of ethylene-methacrylic acid copolymer developed by DuPont, and "Himilan (registered trademark)," sold by Mitsui-Dow 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 high-pressure radical polymerization. High-pressure radical polymerization has the advantage of being inexpensive and relatively free of select polar-group-containing monomers. However, the molecular structure of the polar-group-containing olefin copolymers produced by this high-pressure radical polymerization method, as shown in the image in Figure 1, has many irregular long-chain branches and short-chain branches, resulting in insufficient strength. Therefore, conventional commercially available ionomers using polar-group-containing olefin copolymers polymerized by high-pressure radical polymerization as the base resin have insufficient impact resistance.

Meanwhile, methods have been explored for producing polar group-containing olefin copolymers having a linear molecular structure, as shown in the image diagram in Figure 2, using a polymerization method that uses a catalyst. However, polar group-containing monomers generally act as catalyst poisons, making polymerization difficult. In fact, it has long been considered difficult to obtain polar group-containing olefin copolymers having the desired physical properties using an industrially inexpensive and stable method.
However, in recent years, a method has been proposed for industrially obtaining polar group-containing olefin copolymers having a substantially linear molecular structure at low cost and in a stable manner by using a new catalyst and a new production method developed by the present applicant and others.
The present applicants have reported that they have succeeded in producing a polar group-containing olefin copolymer, which serves as the base resin for ethylene-based ionomers, by producing a copolymer of ethylene and t-butyl acrylate using a late transition metal catalyst, modifying the resulting polar group-containing olefin copolymer by heat or acid treatment to form an ethylene-acrylic acid copolymer, and then reacting the copolymer with metal ions to produce a binary ionomer (Patent Document 2).

Ethylene-based ionomers are also used as resin layers in glass laminates, and applications include laminated glass interlayers and solar cell encapsulants. Laminated glass is made by bonding two or more glass sheets together via a resin interlayer. Laminated glass is used as automobile windshields, instrument monitor glass, and building glass. The use of an interlayer provides safety benefits, such as preventing glass cracking and scattering of broken glass fragments, due to the interlayer's flexibility and adhesion to the glass. For this reason, laminated glass interlayers are required to have transparency, impact resistance, and adhesion to the glass. Laminated glass using an ethylene-based ionomer interlayer is described in Patent Document 3 and Patent Document 4.

Solar cell encapsulant is a material that adheres to both the front and back surfaces of a power generation element, consisting of a solar cell and an interconnector, in a solar cell module to seal the element. The power generation element is adhered to the light-receiving layer and back surface layer of the solar cell module via this encapsulant. The light-receiving layer is generally a glass layer called a cover glass, and the back surface layer is a weather-resistant resin film. The encapsulant in a solar cell module is required to have high transparency so that incident light passing through the light-receiving layer can reach the solar cell without loss, and to protect the power generation element from external impacts. Patent Document 5 describes a solar cell encapsulant with improved adhesion achieved by adding a silane coupling agent to an ethylene-based ionomer.

U.S. Pat. No. 3,264,272 JP 2016-79408 A Japanese Patent Application Laid-Open No. 2018-193261 JP 2016-188158 A JP 2009-248377 A

As such, laminated glass interlayers and solar cell encapsulants are required to have high impact resistance, high transparency, and high adhesion to glass. Ionomers are one of the materials being investigated, and while Patent Documents 3 and 4 describe laminated glass in which adhesiveness is improved by adding a silane coupling agent to an ethylene-based ionomer, there have been no examples to date of improving adhesiveness by improving the ionomer resin alone, leaving room for improvement in terms of cost and productivity. Furthermore, impact resistance is still insufficient, and there are no examples of impact resistance being improved by improving the resin alone. Even with the ionomer described in Patent Document 5, there are no examples of improving adhesive strength with the resin alone, and impact resistance is still insufficient, and there are no examples of impact resistance being improved by improving the resin alone.

In light of the state of the art, the present application aims to provide a resin for glass laminates containing an ionomer that offers an excellent balance of impact resistance, transparency, and adhesion.

As a result of extensive investigations conducted by the present inventors to solve the above problems, they discovered that the use of a specific ionomer resin has a far superior effect than expected in terms of required physical properties such as impact resistance, transparency, and adhesiveness.
The ethylene-based ionomer described in Patent Document 2 is a novel ethylene-based ionomer that has not been seen before, in which the base 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 having a multi-branched molecular structure, and its unique characteristics and suitable applications were also unknown. The present invention is based on the discovery that a resin containing a substantially linear ethylene-based ionomer has an excellent effect in improving the physical properties required for a resin layer used in a glass laminate.

That is, the present invention is as shown in the following [1] to [13].
[1] A structural unit (A) derived from ethylene and/or an α-olefin having 3 to 20 carbon atoms;
a copolymer (P) containing, as an essential constituent unit, a structural unit (B) derived from a monomer having a carboxyl group and/or a dicarboxylic acid anhydride group, in which at least a portion of the carboxyl groups and/or dicarboxylic acid anhydride groups are converted to a metal-containing carboxylate salt containing at least one metal ion selected from Group 1, Group 2, or Group 12 of the Periodic Table;
The resin for glass laminates contains an ionomer characterized in that the phase angle δ at an absolute value of complex elastic modulus G ^* =0.1 MPa measured with a rotational rheometer is 50 degrees to 75 degrees.
[2] The resin for glass laminates according to [1], wherein the number of methyl branches of the copolymer (P) calculated by ^13C -NMR is 50 or less per 1,000 carbon atoms.
[3] The resin for glass laminates according to [1], wherein the number of methyl branches of the copolymer (P) calculated by ^13C -NMR is 5 or less per 1,000 carbon atoms.
[4] The resin for a glass laminate according to any one of [1] to [3], wherein the copolymer (P) contains the structural unit (B) in an amount of 2 to 20 mol %.
[5] The resin for a glass laminate according to any one of [1] to [4], wherein the structural unit (A) is a structural unit derived from ethylene.
[6] The resin for glass laminates according to any one of [1] to [5], wherein the copolymer (P) is produced using a transition metal catalyst containing a transition metal of Groups 8 to 11 of the periodic table.
[7] The resin for glass laminates according to [6], wherein the transition metal catalyst is a transition metal catalyst comprising a phosphorus sulfonic acid or phosphorus phenol ligand and nickel or palladium.
[8] A resin film for glass laminates, characterized by using the resin for glass laminates according to any one of [1] to [7] above.
[9] A resin film for glass interlayers, characterized by using the resin for glass laminates according to any one of [1] to [7] above.
[10] A resin film for a solar cell encapsulant, characterized by using the resin for a glass laminate according to any one of [1] to [7] above.
[11] A glass laminate characterized by being laminated with the resin film for glass laminates according to [8] above.
[12] Laminated glass characterized in that the resin film for glass interlayer film according to [9] above is laminated.
[13] A solar cell module characterized by laminating the resin film for solar cell encapsulant according to [10] above.

Resins for glass laminates containing the ionomer of the present invention, which has a substantially linear structure, have a superior balance of impact resistance, transparency, and adhesion compared to existing glass laminate resins made from polyethylene or ionomer resins.

FIG. 1 is an image of the molecular structure of a hyperbranched olefin copolymer polymerized by a high-pressure radical polymerization process. FIG. 1 is an image of the molecular structure of a linear olefin copolymer polymerized using a metal catalyst. FIG. 1 is a graph showing the relationship between tensile impact strength and adhesive strength to glass in Examples 1 to 10 and Comparative Examples 1 and 2.

The present invention provides a resin for glass laminates that uses an ionomer, characterized in that the base resin is a copolymer (P) in which 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 are essential structural units, and optionally further contains structural units (C) that are compounds having one or more carbon-carbon double bonds in their molecular structure, copolymerized, preferably randomly, in a substantially linear chain, and in which at least a portion of the carboxyl groups and/or dicarboxylic anhydride groups in structural units (B) have been converted to a metal-containing carboxylate salt containing at least one metal ion selected from Groups 1, 2, or 12 of the Periodic Table.

The ionomer according to the present invention, the resin for glass laminates using the ionomer, and their applications will be described in detail below. In this specification, "(meth)acrylic acid" means acrylic acid or methacrylic acid. In this specification, the term "to" indicating a range of values is used to mean that the values before and after the range are the lower and upper limits. In this specification, the term "copolymer" means a binary or higher copolymer containing at least one unit (A) and at least one unit (B).
In addition, in this specification, the term "ionomer" refers to an ionomer of a binary or higher copolymer that contains the structural unit (A) and a structural unit (B') in which at least a portion of the structural unit (B) has been converted to a metal-containing carboxylate, and that may further contain the structural unit (B).

1. Ionomer The ionomer of the present invention is characterized in that it uses as a base resin a copolymer (P) which contains, as essential structural 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 acid anhydride group, and optionally also contains, as a structural unit, a structural unit (C) which is a compound having one or more carbon-carbon double bonds in its molecular structure, and which is copolymerized, preferably randomly, in a substantially linear chain configuration, and in that at least a portion of the carboxyl groups and/or dicarboxylic acid anhydride groups of the structural units (B) are 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.

(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.
The α-olefins used in 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 or branched structure). The number of carbon atoms in 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 petroleum raw materials or ethylene derived from non-petroleum raw materials such as plant raw materials can be used.
The structural unit (A) may be of one type or of multiple types.
Examples of combinations of the two 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).
In terms of impact resistance, the structural unit (A) may be a structural unit derived from ethylene.

(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. Note that the structural unit (B) has the same structure as the structural unit derived from a monomer having a carboxyl group and/or a dicarboxylic anhydride group, but as will be described later in the production method, it does not necessarily have to be produced using a monomer having a carboxyl group and/or a dicarboxylic anhydride group.

Examples of structural units derived from 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 structural units derived from 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[6.2.1.1 ^3,6 . 0 ^2,7 ]dodec-9-ene-4,5-dicarboxylic anhydride, and 2,7-octadien-1-ylsuccinic anhydride.
As the structural unit derived from a monomer having a carboxyl group and/or a dicarboxylic acid anhydride group, from the viewpoint of industrial availability, preferred examples include acrylic acid, methacrylic acid, and 5-norbornene-2,3-dicarboxylic acid anhydride, and particularly acrylic acid.
The structural unit derived from a monomer having a carboxyl group and/or a dicarboxylic anhydride group may be of one type or of multiple types.

Note that the dicarboxylic anhydride group may react with moisture in the air to open the ring and convert a portion of it to a dicarboxylic acid, but the dicarboxylic anhydride group may be ring-opened as long as it does not deviate from the spirit of the present invention.

(3) Other structural units (C)
The copolymer (P) used in the present invention may be a binary copolymer consisting of only the structural unit (A) and the structural unit (B), or a multicomponent copolymer containing the structural unit (A), the structural unit (B), and a structural unit (C) other than these. Preferably, the copolymer is a multicomponent copolymer further containing a structural unit (C) other than the structural units represented by the structural units (A) and (B). Any monomer can be used as the monomer that provides the structural unit (C), as long as it is not included in the monomers that provide the structural unit (A) and the structural unit (B). The 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. Examples of the monomer that provides the structural unit (C) include acyclic monomers represented by the general formula (1) shown below and cyclic monomers represented by the general formula (2).
Compared to a binary copolymer consisting only of the structural unit (A) and the structural unit (B), the use of a ternary or higher multi-component copolymer containing the structural unit (C) as the base resin of an ionomer allows for more precise control of the physical properties of the ionomer resin. This is particularly advantageous because it allows for even greater improvement in impact resistance. The structural unit (C) may be based on one type of monomer, or may be a combination of two or more types of monomers.

・Acyclic monomers

[In 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 carbon skeleton of the hydrocarbon group, substituted alkoxy group, substituted ester group, alkoxy group, aryl group, ester group and silyl group for T ¹ to T ⁴ may have a branch, a ring and/or an unsaturated bond.
The lower limit of the number of carbon atoms in the hydrocarbon 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 substituted alkoxy groups 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 substituted ester groups 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 lower limit of the number of carbon atoms in the alkoxy groups 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 lower limit of the number of carbon atoms in the silyl group for ^T1 to ^T4 may be 3 or more, and the upper limit may be 18 or less, 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.

In the ionomer of the present invention, from the viewpoint of ease of production, ^T1 and ^T2 may be hydrogen atoms, ^T3 may be a hydrogen atom or a methyl group, or all of ^T1 to ^T3 may be hydrogen atoms.
From the viewpoint of impact resistance, ^T4 may also be an ester group having 2 to 20 carbon atoms.

Specific examples of the acyclic monomer include those in which T ⁴ is an ester group having 2 to 20 carbon atoms, including (meth)acrylic acid esters.
When ^T4 is an ester group having 2 to 20 carbon atoms, examples of the acyclic monomer include compounds 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 compounds represented by the structural formula: CH ₂ ═C(R ²¹ )CO ₂ (R ²² ) include compounds in which R ²¹ is a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms. Also included are acrylic acid esters in which R ²¹ is a hydrogen atom and methacrylic acid esters in which R ²¹ is a methyl group.
Specific examples of compounds represented by the structural formula CH ₂ ═C(R ²¹ )CO ₂ (R ²² ) 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 acyclic monomer may be of one type or of multiple types.

・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 together form a ring.]
Furthermore, n represents 0 or a positive integer, and when n is 2 or greater, 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 ], and tricyclo[4.3.0.1 ^2,5 ]dec-3-ene, and may also include 2-norbornene (NB) and tetracyclo[6.2.1.1 ^3,6 . 0 ^2,7 ]dodec-4-ene.

(4) Copolymer (P)
The copolymer (P) used in the present invention, which serves as the base resin for the ionomer, contains, as essential structural 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 optionally further contains an optional structural unit (C) other than (A) and (B), and these structural units are copolymerized, preferably randomly copolymerized, in a substantially linear chain. The term "substantially linear" refers to a state in which the copolymer is free of branches or has branched structures with a low frequency, allowing the copolymer to be considered linear. Specifically, this refers to a state in which the phase angle δ of the copolymer is 50 degrees or greater under the conditions described below.

The copolymer (P) according to the present invention must contain at least one type of the structural unit (A) and at least one type of the structural unit (B), and must contain at least two types of monomer units in total. It may also contain an arbitrary structural unit (C) other than the above-mentioned (A) and (B), but is preferably a multi-component copolymer containing such a structural unit (C).
The structural units and amounts of the structural units of the copolymer according to the present invention will be explained 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 (B) having a carboxyl group and/or a dicarboxylic anhydride group, and an arbitrary monomer (C) other than (A) and (B) 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 the total amount of structural units in the copolymer is taken as 100 mol %.

Amount of structural units of ethylene and/or α-olefin having 3 to 20 carbon atoms (A):
The structural unit amount of the structural unit (A) according to the present invention has a lower limit of 60.0 mol% or more, preferably 70.0 mol% or more, more preferably 80.0 mol% or more, even more preferably 85.0 mol% or more, still more preferably 90.0 mol% or more, and particularly preferably 92.0 mol% or more, and an upper limit selected from 97.9 mol% or less, preferably 97.5 mol% or less, more preferably 97.0 mol% or less, and even more preferably 96.5 mol% or less.
If the amount of structural units derived from ethylene and/or the α-olefin (A) having 3 to 20 carbon atoms is less than 60.0 mol%, the toughness of the copolymer will be inferior, and if it is more than 97.9 mol%, the crystallinity of the copolymer will be high, which may result in poor transparency.

Amount of structural units of the monomer (B) having a carboxyl group and/or a dicarboxylic anhydride group:
The structural unit amount of the structural unit (B) according to the present invention is selected from the group consisting of a lower limit of 2.0 mol% or more, preferably 2.9 mol% or more, and more preferably 5.1 mol% or more, and an upper limit of 20.0 mol% or less, preferably 15.0 mol% or less, more preferably 10.0 mol% or less, even more preferably 8.0 mol% or less, particularly preferably 6.0 mol% or less, and most preferably 5.6 mol% or less.
If the amount of structural units derived from the monomer (B) having a carboxyl group and/or a dicarboxylic anhydride group is less than 2.0 mol%, the copolymer may not have sufficient adhesion to different materials with high polarity, and if the amount is more than 20.0 mol%, the copolymer may not have sufficient mechanical properties.
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.

Amount of structural units of optional monomer (C):
When copolymer (P) contains structural units other than the structural units (A) and (B), the structural unit amount of the structural unit (C) according to the present invention has a lower limit of 0.001 mol% or more, preferably 0.010 mol% or more, more preferably 0.020 mol% or more, even more preferably 0.1 mol% or more, still more preferably 1.5 mol% or more, and particularly preferably 2.9 mol% or more, and an upper limit of 20.0 mol% or less, preferably 15.0 mol% or less, more preferably 10.0 mol% or less, even more preferably 5.0 mol% or less, and particularly preferably 2.9 mol% or less.
When the amount of the structural unit derived from the optional monomer (C) is within this range, the flexibility of the copolymer becomes more sufficient, and more satisfactory mechanical properties are obtained.
Furthermore, any of the monomers used may be used alone or in combination of two or more kinds.

Number of branches per 1,000 carbon atoms of copolymer (P):
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 ^13C -NMR per 1,000 carbon atoms may be an upper limit of 50 or less, 5.0 or less, 1.0 or less, or 0.5 or less, with no particular lower limit, the lower the better. The number of ethyl branches per 1,000 carbon atoms may be an upper limit of 3.0 or less, 2.0 or less, 1.0 or less, or 0.5 or less, with no particular lower limit, the lower the better. The number of butyl branches per 1,000 carbon atoms may be an upper limit of 7.0 or less, 5.0 or less, 3.0 or less, or 0.5 or less, with no particular lower limit, the lower the better.

Method for measuring the amount of structural units derived from monomers having a carboxy group and/or a dicarboxylic anhydride group and acyclic monomers in a 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 acyclic monomer in the copolymer of the present invention, and the number of branches per 1,000 carbon atoms can be determined using ^13C -NMR spectroscopy. ^13C -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 reference substance, and the tube is purged with nitrogen, then sealed and heated to dissolve, resulting in a homogeneous solution that is 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 C-NMR, signals specific to the monomers or branches contained in the copolymer are identified and their intensities are compared, whereby the amount of structural units of each monomer and the number of branches in the copolymer can be analyzed. The positions of the signals specific to the monomers or branches can be determined by reference to publicly known materials, or can be independently identified depending on the sample. Such analytical techniques are commonly known to those skilled in the art.

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 has a lower limit of usually 1,000 or more, preferably 6,000 or more, and more preferably 10,000 or more, and an upper limit of usually 2,000,000 or less, preferably 1,500,000 or less, further preferably 1,000,000 or less, particularly preferably 800,000 or less, and most preferably 100,000 or less.
If the Mw is less than 1,000, the copolymer will have insufficient physical properties such as mechanical strength and impact resistance, whereas if the Mw is more than 2,000,000, the copolymer will have an extremely high melt viscosity, which may make it difficult to mold the copolymer.

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. If Mw/Mn is less than 1.5, the copolymer may have insufficient processability, including molding, whereas if it exceeds 4.0, the copolymer may have poor mechanical properties.
In this specification, (Mw/Mn) may be referred to as the molecular weight distribution parameter.

The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the copolymer of the present invention are determined by gel permeation chromatography (GPC). Furthermore, 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 a GPC measurement method according to the present invention is as follows.
(Measurement conditions)
Model used: Waters 150C
Detector: FOXBORO MIRAN1A IR detector (measurement wavelength: 3.42 μm)
Measurement temperature: 140℃
Solvent: orthodichlorobenzene (ODCB)
Column: Showa Denko AD806M/S (3 columns)
Flow rate: 1.0mL/min Injection volume: 0.2mL
(Sample Preparation)
A 1 mg/mL solution of the sample is prepared using ODCB (containing 0.5 mg/mL of BHT (2,6-di-t-butyl-4-methylphenol)), and the sample is 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 prepared in advance using standard polystyrene. Examples of standard polystyrenes used include brands (F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000) manufactured by Tosoh Corporation, and monodisperse polystyrenes (S-7300, S-3900, S-1950, S-1460, S-1010, S-565, S-152, S-66.0, S-28.5, S-5.05, each in a 0.07 mg/mL solution) manufactured by Showa Denko K.K. A calibration curve is prepared by injecting 0.2 mL of a solution in which each of the polystyrenes is dissolved in ODCB (containing 0.5 mg/mL of BHT) to a concentration of 0.5 mg/mL. The calibration curve is a cubic equation obtained by approximating using the least squares method, or a quartic equation obtained by approximating the logarithm of the elution time and molecular weight. The following values are used for the viscosity equation [η] = K × Mα used to convert to molecular weight (M):
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

Melting point (Tm, ° C.):
The melting point of the copolymer according to the present invention is represented by the maximum peak temperature of the endothermic curve measured by a differential scanning calorimeter (DSC). When the endothermic curve obtained in the DSC measurement shows multiple peaks 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 greatest height from the baseline. When there is only one peak, the maximum peak temperature 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. If it is lower than this range, the heat resistance may be insufficient, and if it is higher than this range, the adhesiveness may be poor.
In the present invention, the melting point can be determined from the absorption curve obtained by using, for example, 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, cooling it 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.

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 7% or more and not more than 24%.
The crystallinity can be determined, for example, by determining the heat of fusion (ΔH) from the area of the melting endothermic peak obtained by DSC measurement using the same procedure as in the measurement of the melting point, and dividing the heat of fusion by the heat of fusion of 293 J/g for perfectly crystalline high-density polyethylene (HDPE).

・Molecular structure of 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 any structural unit (C) other than (A) and (B).

The copolymer according to the present invention may be a random copolymer, block copolymer, or graft copolymer 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 that can contain a large amount of the structural unit (B) may be used.
An example of the molecular structure of a general ternary copolymer (1) is shown below.
A random copolymer is a copolymer of 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, as shown in the molecular structure example (1) below, in which the probability of finding each structural unit at any position in a molecular chain is independent of the type of the adjacent structural unit.
As shown below, in the example molecular structure (1) of the copolymer, 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 form a random copolymer.

For reference, an example of a molecular structure (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. In this example, a part of a copolymer in which structural unit (A) of ethylene and/or an α-olefin having 3 to 20 carbon atoms and structural unit (C) of an arbitrary 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 copolymerization of a copolymer can be confirmed by various methods, methods for determining the random copolymerization from the relationship between the comonomer content and melting point of a copolymer are described in detail in JP 2015-163691 A and JP 2016-079408 A. From these documents, it can be determined that the randomness is low when the melting point (Tm, °C) of the copolymer is higher than -3.74 × [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 any monomer that satisfies the following formula (I):
50<Tm<-3.74×[Z]+130...(I)
If the melting point of the copolymer (Tm, °C) is higher than -3.74 × [Z] + 130 (°C), the random copolymerization property is low, and therefore mechanical properties such as impact strength may be poor. If the melting point is lower than 50°C, the heat resistance may be poor.

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 linear.
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, but the molecular structure can also be estimated from the complex modulus measured with a rotational rheometer, as described in, for example, JP 2010-150532 A.

Absolute value of complex elastic modulus G ^* = Phase angle δ at 0.1 MPa:
In the copolymer of the present invention, the phase angle δ at the absolute value of the complex modulus G ^* = 0.1 MPa measured with a rotational rheometer may have a lower limit of 50 degrees or more, 51 degrees or more, 54 degrees or more, 56 degrees or more, or 58 degrees or more, and an upper limit of 75 degrees or less, or 70 degrees or less.
More specifically, if the phase angle δ (G ^* = 0.1 MPa) at the absolute value of the complex modulus G ^* = 0.1 MPa measured using a rotational rheometer is 50 degrees or more, the molecular structure of the copolymer is a linear structure that contains no long chain branches at all, or a substantially linear structure that contains a small amount of long chain branches that does not affect the mechanical strength.
Furthermore, if the phase angle δ (G ^* = 0.1 MPa) at the absolute value of the complex modulus G ^* = 0.1 MPa measured using a rotational rheometer is lower than 50 degrees, the molecular structure of the copolymer will contain excessive long chain branches, resulting in poor mechanical strength.
The phase angle δ at the absolute value of the complex modulus G ^* = 0.1 MPa measured with a rotational rheometer is affected by both the molecular weight distribution and the long chain branching. However, for copolymers with Mw/Mn ≦ 4, more preferably Mw/Mn ≦ 3, it serves as an indicator of the amount of long chain branching, and the more long chain branches contained in the molecular structure, the smaller the δ(G ^* = 0.1 MPa) value. Note that if the Mw/Mn of a copolymer is 1.5 or more, the δ(G ^* = 0.1 MPa) value will not exceed 75 degrees even if the molecular structure does not contain long chain branches.

The complex elastic modulus is measured as follows.
The sample is placed in a 1.0 mm thick heat press mold and preheated for 5 minutes in a heat press at a surface temperature of 180 ° C. After repeated pressure and pressure reduction, residual gas in the molten resin is degassed, and the pressure is further increased to 4.9 MPa and held for 5 minutes. The sample is then transferred to a press at 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 the sample with a thickness of approximately 1.0 mm. The press plate made of the sample is processed into a circular shape with a diameter of 25 mm to serve as a sample. Dynamic viscoelasticity is measured under the following conditions in a nitrogen atmosphere using an ARES type rotational rheometer manufactured by Rheometrics as a measuring device for dynamic viscoelastic properties.
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 logG ^* of the absolute value G ^* (Pa) of the complex elastic modulus, and the value of δ (degrees) at the point corresponding to logG ^* = 5.0 is designated as δ (G ^* = 0.1 MPa). When there is no point corresponding to logG ^* = 5.0 among the measurement points, the δ value at logG ^* = 5.0 is determined by linear interpolation using two points around logG ^* = 5.0. In addition, when all measurement points are logG ^* < 5, the δ value at logG ^* = 5.0 is determined by extrapolating using the values of the three points from the largest logG ^* value using a quadratic curve.

- Regarding production of copolymer 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 linear.
Polymerization Catalyst The type of polymerization catalyst used in the production of 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 used.
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, transition metals of Groups 8 to 11 are preferred, transition metals of Group 10 are more preferred, and nickel (Ni) and palladium (Pd) are particularly preferred. 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 provided in a 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, any of the various transition metals 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 hydrogen or a hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom.
Each R ⁵⁵ independently represents hydrogen, 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 hydrogen 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, and 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.
Furthermore, R ⁵³ and L ¹ may be bonded to each other to form a ring.]

More preferably, the complex serving as the polymerization catalyst 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, any of the various transition metals 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 hydrogen or a hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom.
Each R ⁵⁵ independently represents hydrogen, 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 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 hydrogen 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, multiple groups appropriately selected from R ⁵⁸ to R ⁶¹ may be linked 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.
Furthermore, R ⁵³ and L ¹ may be bonded to each other to form a ring.]

Here, typical catalysts of transition metal compounds of Groups 5 to 11 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, WO2010-050256).
Furthermore, Drent catalysts are catalysts 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).

Copolymerization method:
The method for polymerizing the copolymer according to the present invention is not limited.
Examples of the polymerization method include slurry polymerization in which at least a portion of the produced polymer becomes a slurry in a medium, bulk polymerization in which liquefied monomer itself is used as a medium, gas phase polymerization carried out in vaporized monomer, and high pressure ionic polymerization in which at least a portion of the produced polymer is dissolved in monomer liquefied at high temperature and pressure.
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 chain transfer occurs simultaneously.
Furthermore, during 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 Nos. 2010-260913 and 2010-202647.

Method for introducing carboxyl groups and/or dicarboxylic anhydride groups into copolymers:
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, and the carboxyl group and/or the 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 having a functional group that generates a carboxyl group, and then introducing a carboxyl group and/or a dicarboxylic anhydride group by modification.

Methods for introducing carboxyl groups and/or dicarboxylic anhydride groups through modification include, for example, when introducing carboxylic acid, copolymerizing an acrylic acid ester as a precursor and then hydrolyzing it to convert it to carboxylic acid, or copolymerizing t-butyl acrylate as a precursor and then thermally decomposing it to convert it to carboxylic acid.

A conventionally known acid-base catalyst may be used as an additive for promoting the reaction during the hydrolysis or thermal decomposition. The acid-base catalyst is not particularly limited, and examples thereof include alkali metal or alkaline earth metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, alkali metal or alkaline earth metal carbonates such as sodium bicarbonate and sodium carbonate, solid acids such as montmorillonite, inorganic acids such as hydrochloric acid, nitric acid, and sulfuric acid, and organic acids such as formic acid, acetic acid, benzoic acid, citric acid, paratoluenesulfonic acid, trifluoroacetic acid, and trifluoromethanesulfonic acid.
From the viewpoint of reaction accelerating effect, cost, corrosion resistance of equipment, etc., sodium hydroxide, potassium hydroxide, sodium carbonate, trifluoroacetic acid, and paratoluenesulfonic acid are preferred, and trifluoroacetic acid and paratoluenesulfonic acid are more preferred.

(5) Ionomer The ionomer of the present invention is an ionomer in which at least a portion of the carboxyl groups and/or dicarboxylic anhydride groups of the structural unit (B) in the copolymer (P) is converted to a metal-containing carboxylate containing at least one metal ion selected from Groups 1, 2, or 12 of the periodic table, and has a phase angle δ of 50 to 75 degrees at an absolute value of complex modulus G ^* of 0.1 MPa measured with a rotational rheometer, and has a substantially linear structure. As described below, the ionomer is obtained by reacting an ionomer base resin with a metal salt, and during this process, a reaction that severs the molecular chain of the polymer does not usually occur. Therefore, structural parameters such as the molar ratio of comonomers, the degree of branching, and randomness are usually preserved between the ionomer base resin and the ionomer.

- Structure of the ionomer The ionomer of the present invention has a substantially linear structure, similar to the copolymer of the present invention, and is therefore characterized by a phase angle δ of 50 to 75 degrees at an absolute value of complex modulus G ^* = 0.1 MPa measured with a rotational rheometer.
If the phase angle δ (G ^* = 0.1 MPa) is lower than 50 degrees, the molecular structure of the ionomer contains excessive long chain branches, resulting in poor mechanical strength. Even if the molecular structure does not contain long chain branches, the δ (G ^* = 0.1 MPa) value will not exceed 75 degrees.
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.

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. If it is lower than this range, the heat resistance may be insufficient, and if it is higher than this range, the adhesiveness may be poor.
Of the ionomers related to the present invention, ionomers based on a binary copolymer consisting only of structural unit (A) and structural unit (B) have a melting point of 90°C or higher, preferably 95°C or higher, and more preferably 100°C or higher, while ionomers based on a ternary or higher multi-component copolymer have a melting point of less than 100°C, preferably less than 95°C, and more preferably less than 90°C.

Metal Ions The metal ions contained in the ionomer of the present invention are not particularly limited and may include metal ions used in conventionally known ionomers. Among these, metal ions are preferably metal ions of Group 1, 2, or 12 of the periodic table, more preferably 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⁺ . Particularly preferred are at least one selected from the group consisting of Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ca ²⁺ , and Zn ²⁺ , and even more preferably Na ⁺ and Zn ²⁺ .
Two or more of these metal ions may be mixed as needed.

・Neutralization degree (mol%)
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 polymer, 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 10 to 80 mol%.
The degree of neutralization can be determined from the ratio of the total molar amount of the valence × mol amount of metal ions to the total molar amount of carboxy groups that may be contained in the carboxy groups and/or dicarboxylic anhydride groups in the copolymer.
Since dicarboxylic anhydride groups undergo ring-opening to form dicarboxylic acids when forming carboxylates, the total molar amount of carboxy groups is calculated assuming that 2 mol of carboxy groups exist per mol of dicarboxylic anhydride groups. Also, assuming that 1 mol of a divalent metal ion such as Zn2 ⁺ can form a salt with 2 mol of carboxy 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 tends to result in a low melt flow rate (MFR).On the other hand, a low degree of neutralization results in an ionomer with an appropriate MFR, but tends to result in a low tensile modulus and tensile stress at break and high tensile strain at break.

Haze (%)
The ethylene-based ionomer resin of the present invention preferably has a haze value (%) of 25% or less, more preferably 20% or less, as measured in accordance with JIS K 7136-2000. A haze (%) of 25% or less provides a molded article with better transparency, making it preferable for applications requiring transparency, such as window glass and solar cell modules.

Tensile impact strength (kJ/m ² )
The ethylene-based ionomer resin of the present invention has a tensile impact strength, as measured with reference to Method B of JIS K 7160-1996, of preferably 700 kJ/ ^m2 or more, more preferably 720 kJ/ ^m2 or more, even more preferably 800 kJ/ ^m2 or more, and particularly preferably 1000 kJ/ ^m2 or more, in terms of sufficient impact resistance.

・Adhesive strength (N/10mm)
The ethylene-based ionomer resin of the present invention preferably has an adhesive strength of 2.0 N/10 mm or more, more preferably 2.3 N/10 mm or more, even more preferably 2.5 N/10 mm or more, and still more preferably 3.0 N/10 mm or more, in order to ensure sufficient adhesive strength as measured by a tensile tester described below.

- Method for producing ionomer The ionomer of the present invention may be obtained by a conversion step in which a copolymer of ethylene and/or an α-olefin having 3 to 20 carbon atoms/unsaturated carboxylic acid, obtained by the method for introducing carboxyl groups and/or dicarboxylic anhydride groups into the copolymer as described above, is treated with a metal salt containing at least one metal ion selected from Group 1, Group 2, or Group 12 of the periodic table to convert the copolymer into a metal-containing carboxylate. Alternatively, the ionomer of the present invention may be obtained by a heat conversion step in which an ethylene and/or an α-olefin having 3 to 20 carbon atoms/unsaturated carboxylic acid ester copolymer is heated to convert at least a portion of the ester groups in the copolymer into a metal-containing carboxylate containing at least one metal ion selected from Group 1, Group 2, or Group 12 of the periodic table.

When ionomers are produced after introducing carboxyl groups and/or dicarboxylic anhydride groups into a polymer, the production method is, for example, as follows. That is, a metal ion source is prepared by kneading, optionally with heating, a metal salt with a substance that captures metal ions, such as ethylene/methacrylic acid (MAA) copolymer, and then adding the metal ion source to the ionomer base resin in an amount that achieves the desired degree of neutralization, followed by kneading.

In addition, the thermal conversion step may involve (i) heating an ethylene and/or C3-20 α-olefin/unsaturated carboxylic acid ester copolymer and hydrolyzing or thermodecomposing it to form an ethylene and/or C3-20 α-olefin/unsaturated carboxylic acid copolymer, and then reacting the copolymer with a compound containing a metal ion of Group 1, 2, or 12 of the periodic table to convert the carboxylic acid in the copolymer into the metal-containing carboxylate. Also, (ii) heating an ethylene and/or C3-20 α-olefin/unsaturated carboxylic acid ester copolymer and hydrolyzing or thermodecomposing the ester groups in the copolymer while reacting the copolymer with a compound containing a metal ion of Group 1, 2, or 12 of the periodic table to convert the ester group moieties in the copolymer into the metal-containing carboxylate.

The metal ion-containing compound may be an oxide, hydroxide, carbonate, bicarbonate, acetate, formate, etc. of a metal of Group 1, 2, or 12 of the periodic table.
The compound containing a metal ion 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 masterbatch 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 progress of the reaction, it is preferable to prepare a masterbatch and then supply it to the reaction system.

Furthermore, the reaction with the metal ion-containing compound may be carried out by melt-kneading using various types of equipment such as a vented extruder, a Banbury mixer, or a roll mill, and the reaction may be carried out batchwise or continuously. Since the reaction can be carried out smoothly by discharging water and carbon dioxide gas by-produced in 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 vented 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 C3-20 α-olefin/unsaturated carboxylic acid ester copolymer is heated may be any temperature at which the ester is converted to a carboxylic acid. If the heating temperature is too low, the ester will not be converted to a carboxylic acid, while if the heating temperature is too high, decarbonylation or decomposition of the copolymer may occur. 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 factors such as the heating temperature and the reactivity of the ester group, but is typically between 1 minute and 50 hours, more preferably between 2 minutes and 30 hours, even more preferably between 2 minutes and 10 hours, even more preferably between 2 minutes and 3 hours, and particularly preferably between 3 minutes and 2 hours.

In the above process, there are no particular restrictions on the reaction atmosphere, but it is generally preferable to carry out the process under a stream of inert gas. Examples of inert gases that can be used include nitrogen, argon, and carbon dioxide. Small amounts of oxygen or air may be present.

There are no particular restrictions on the reactor used in the above process, provided that the method allows for substantially uniform stirring of the copolymer. A glass vessel or autoclave (AC) equipped with a stirrer may be used, or any conventional 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.

Whether metal ions have been introduced into an ionomer-based resin and it has become an ionomer can be confirmed by measuring the IR spectrum of the resulting resin and examining the decrease in the peak derived from the carbonyl group of the carboxylic acid (dimer). Similarly, the degree of neutralization can be confirmed by calculating it from the molar ratio mentioned above, as well as examining the decrease in the peak derived from the carbonyl group of the carboxylic acid (dimer) and the increase in the peak derived from the carbonyl group of the carboxylate salt group.

2. Resin Film for Glass Laminate and Glass Laminate The ionomer according to the present invention can be used in a resin film constituting at least one layer of a glass laminate. A "glass laminate" refers to a laminate having a multilayer structure of two or more layers, at least one of which is glass. Therefore, the glass laminate according to the present invention is a structure having at least one glass layer and one resin layer containing the ionomer according to the present invention (hereinafter, this layer may also be referred to as an "ionomer resin layer"). Preferably, the glass layer and the ionomer resin layer are in direct contact. Materials used for the other layers can be freely selected by those skilled in the art depending on the intended use of the glass laminate.

The resin film for glass laminates of the present invention is a film containing the resin for glass laminates containing the ionomer. Here, the term "film" generally refers to a structure having a thickness that is negligible relative to its area, but in the present invention, the term "film" is used to include not only films (generally 250 μm thick or less) and sheets in the narrow sense, but also plate-like objects. Furthermore, regardless of the flexibility of the film, there are no particular restrictions as long as it is rigid and has a specific shape, as long as it can be used to form a laminate. The surface of the film can have any shape, such as a rectangle, circle, or triangle.

The resin film for glass laminates may consist solely of the ionomer, but may also contain additives such as antioxidants, UV absorbers, light stabilizers, flame retardants, dyes, pigments, plasticizers, antistatic agents, inorganic particles, fluorescent agents, heat absorbers, heat reflectors, modified silicone oil as an adhesion adjuster, moisture-resistant agents, and antiblocking agents, as needed. Furthermore, other resins may be included to provide effects such as UV and infrared absorption, soundproofing, and moisture prevention, as long as the effects of the present invention are not impaired. Those skilled in the art can freely select the resins that can be used depending on the intended use of the laminate.

The resin film for glass laminates itself may also have multiple layers. That is, it may have a single-layer structure consisting of only an ionomer resin layer, or a multi-layer structure in which the ionomer resin layer is laminated with other layers (one or more). As an additional layer, an adhesive layer containing a resin that exhibits adhesion to glass, such as a polyvinyl acetal resin, may be provided, although this is not necessarily required.

The material, manufacturing method, and layer thickness of the glass layers can be freely designed depending on the application. When a glass laminate has multiple glass layers, each layer may be made of the same material or different materials. As described above, a glass laminate is a structure having at least one ionomer resin layer and one glass layer, but the glass laminate may also have a structure in which glass layers and ionomer resin layers are alternately laminated. An adhesive layer may be provided between each glass layer and the ionomer resin layer, or other layers may be provided depending on the application of the glass laminate. Furthermore, the glass layer does not have to be the outermost layer in the laminate, and further layers made of other materials may be laminated thereon.

The glass laminate can be manufactured by any method known to those skilled in the art. A flat glass layer and an ionomer resin layer may be manufactured separately and then bonded together, or the ionomer resin may be uniformly applied to the glass layer and then cured.
The glass laminate of the present invention may be combined with another plate-like body to provide a hollow layer therebetween. That is, by placing the glass laminate of the present invention and the other plate-like body opposite each other with a certain gap between them, sealing the edges and optionally evacuating, a gas layer or a vacuum layer can be provided in the structure.

3. Resin Film for Glass Interlayer, Laminated Glass The resin for glass laminate of the present invention can be suitably used as a resin film for glass interlayer. That is, the resin film for glass interlayer is positioned between two glass layers to form a laminate of at least three layers. Preferably, the resin film for glass interlayer is in contact with the glass layer on at least one side, more preferably on both sides. In order for the resin for glass interlayer to be effective in preventing cracking of the glass and scattering of glass fragments when broken, the adhesive strength measured under the conditions described below is preferably 2.0 N/10 mm or more, more preferably 2.3 N/10 mm or more, even more preferably 2.5 N/10 mm or more, and even more preferably 3.0 N/10 mm or more. One aspect of the present invention is laminated glass using the resin for glass laminate containing the ionomer as a resin film for glass interlayer. The laminated glass of the present invention can be used as laminated glass for window glass, automobile windshield, monitor glass, building glass, security glass, and the like.

The resin film for glass interlayers of the present invention may have a single-layer structure consisting of only an ionomer resin layer, or a multilayer structure in which the ionomer resin layer is laminated with other layers (one or more layers).

The other layers are not particularly limited, but examples include layers containing thermoplastic resins other than ionomer resins, such as polyvinyl acetal resin, ethylene-vinyl acetate copolymer resin, ethylene-acrylic copolymer resin, polyurethane resin, polyurethane resin containing elemental sulfur, polyvinyl alcohol resin, vinyl chloride resin, and polyethylene terephthalate resin. Among these, layers containing polyvinyl acetal resin are preferred, as they exhibit excellent adhesion to glass when used in combination with a plasticizer, and by incorporating various additives, a resin film that can perform a variety of functions can be obtained.

Laminated glass is a laminate with a structure of at least three layers, consisting of two glass layers sandwiching a resin film (ionomer resin layer) for use as a glass interlayer. Laminated glass may also have a structure in which glass layers and ionomer resin layers are alternately laminated.

4. Resin Film for Solar Cell Encapsulant and Solar Cell Module The resin for glass laminate of the present invention can be suitably used as a resin film for solar cell encapsulant.

The resin film for a solar cell encapsulant of the present invention may contain additives such as a light stabilizer, an ultraviolet absorber, and a silane coupling agent, if necessary.
As the light stabilizer, it is preferable to blend a hindered amine light stabilizer. The hindered amine light stabilizer captures radical species harmful to the polymer and prevents the generation of new radicals. There are many types of hindered amine light stabilizers, ranging from low molecular weight to high molecular weight compounds, and any conventionally known compound can be used without any particular limitation.
Examples of ultraviolet absorbers include various types such as benzophenone-based, benzotriazole-based, triazine-based, and salicylic acid ester-based.
Examples of silane coupling agents include vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and 3-acryloxypropyltrimethoxysilane, and they can be used mainly for the purpose of improving the adhesive strength between the upper protective material of the solar cell and the solar cell element.

In addition, other optional additional components may be blended as long as they do not significantly impair the objectives of the present invention. Examples of such optional components include antioxidants, crystal nucleating agents, clarifying agents, lubricants, colorants, dispersants, fillers, and fluorescent brighteners, which are commonly used in polyolefin resin materials.

The resin film for solar cell encapsulant of the present invention can be used to fabricate a solar cell module by fixing a solar cell element together with upper and lower protective materials. Examples of such solar cell modules include those configured in such a way that the solar cell element is sandwiched between encapsulants on both sides, such as upper transparent protective material/encapsulant/solar cell element/encapsulant/lower protective material; those configured in which an encapsulant and upper transparent protective material are formed on a solar cell element formed on the inner surface of a lower substrate protective material; and those configured in which an encapsulant and lower protective material are formed on a solar cell element formed on the inner surface of an upper transparent protective material, such as an amorphous solar cell element formed by sputtering on a fluororesin-based transparent protective material.

As mentioned above, the resin for glass laminates of the present invention and its uses have been explained using specific examples, but the resin for glass laminates of the present invention, and the film and glass laminate made therefrom, are not limited to the specific examples given above. Those skilled in the art can design, modify, improve, etc. as appropriate within the scope of the present invention.

EXAMPLES The present invention will be explained 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 shown below. In the tables, "no data" means not measured, and "not detected" means below the detection limit.

<Measurement and Evaluation>
(1) Measurement of the phase angle δ (G ^* = 0.1 MPa) at the absolute value of the complex modulus G ^* = 0.1 MPa 1) Sample preparation and measurement The sample was placed in a 1.0 mm thick heat press mold and preheated for 5 minutes in a heat press at a surface temperature of 180 ° C. After that, the residual gas in the molten resin was degassed by repeatedly applying pressure and depressurizing, and then pressurized to 4.9 MPa and held for 5 minutes. Then, the sample was transferred to a press at a surface temperature of 25 ° C. and cooled by holding at a pressure of 4.9 MPa for 3 minutes to produce a pressed plate made of a sample with a thickness of approximately 1.0 mm. The pressed plate made of the sample was processed into a circular shape with a diameter of 25 mm to serve as a sample. Using an ARES type rotational rheometer manufactured by Rheometrics as a measuring device for dynamic viscoelastic properties, 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 logG ^* of the absolute value G ^* (Pa) of the complex elastic modulus, and the value of δ (degrees) at the point corresponding to logG ^* = 5.0 was taken as δ (G ^* = 0.1 MPa). When there was no point corresponding to logG ^* = 5.0 among the measurement points, the δ value at logG ^* = 5.0 was determined by linear interpolation using two points around logG ^* = 5.0. In addition, when all measurement points were logG ^* < 5, the δ value at logG ^* = 5.0 was determined by extrapolating using the values of the three points from the largest logG ^* value using a quadratic curve.

(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, obtained 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 If the sample contained a carboxylic acid group, it was subjected to an esterification treatment, such as methyl esterification using diazomethane or trimethylsilyl (TMS) diazomethane, before being used for measurement. If the sample contained a carboxylic acid salt group, it was treated with an acid to modify the carboxylic acid salt group to a carboxylic acid group, and then subjected to the above-mentioned esterification treatment 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 HT-806M high-temperature GPC columns manufactured by Showa Denko were connected to a Waters Alliance GPCV2000 model, and measurements were carried out using o-dichlorobenzene as the 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) manufactured by Showa Denko, n-eicosane, and n-tetracontane, measured under the same conditions as above, and the elution time and the logarithm of the molecular weight were approximated by a quartic equation. The polystyrene molecular weight (M _PS ) and polyethylene molecular weight (M _PE ) were converted using the following equation:
M _PE =0.468×M _PS

(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 21.18 N (=2.16 kg).

(4) 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 Inc. under the following measurement conditions.
Approximately 5.0 mg of the sample was placed 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 again heated at 10°C/min. The maximum peak temperature in the absorption curve obtained during this period 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 then divided by the heat of fusion of 293 J/g for perfectly crystalline high-density polyethylene (HDPE) to determine the degree of crystallinity (%).

(5) Method for measuring the amount of structural units derived from monomers having a carboxy group and/or a dicarboxylic anhydride group, and acyclic monomers, and the number of branches per 1,000 carbon atoms The amount of structural units derived from monomers having a carboxy group and/or a dicarboxylic anhydride group, and acyclic monomers in the copolymer of the present invention, and the number of branches per 1,000 carbon atoms can be determined using ^13C -NMR spectroscopy. ^13C -NMR was measured by the following method.
200 to 300 mg of 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, a chemical shift reference substance. The tube was purged with nitrogen, then sealed, and heated to dissolve the sample into a homogeneous solution, which was used as the NMR measurement sample.
The NMR measurement was carried out at 120° C. using an AV400M NMR apparatus manufactured by Bruker Japan Co., Ltd. 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 shift of ^{the 13} C signal of hexamethyldisiloxane was set to 1.98 ppm, and the chemical shifts of other ¹³ C signals were referenced to this.

1) Sample Pretreatment: When a sample contained a carboxylate group, the sample was subjected to an acid treatment to modify the carboxylate group to a carboxyl group before measurement. When a sample contained 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 acyclic monomers <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) × 100/[I(tBA) + I(E)]
Here, I(tBA) and I(E) are quantities expressed by the following formulas, respectively.
I(tBA)=I _{79.6 to 78.8}
I(E)=(I _180.0~135.0 +I _120.0~5.0 -I(tBA)×7)/2

<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 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 using the following formula.
Total amount of tBA (mol%) = I(tBA) × 100/[I(tBA) + I(iBA) + I(E)]
Total amount of iBA (mol%) = I (iBA) × 100 / [I (tBA) + I (iBA) + I (E)]
Here, I(tBA), I(iBA), and I(E) are quantities expressed by the following formulas, respectively.
I(tBA)=I _{79.6 to 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)×7−I(tBA)×7)/2

<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 according to 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 expressed by the following formulas, respectively.
I(tBA)=I _{79.6 to 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

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

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

The number of branches per 1,000 carbon atoms can be 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 can be 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) × 1,000 / I (total)
Here, I(total), I(B1), I(B2), and I(B4) are quantities expressed by the following formulas.
I (total) = I _{180.0 ~ 135.0} + I _{120.0 ~ 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 ~ 13.7} - I _{32.2 ~ 32.0}
Here, I represents the integrated intensity, and the subscript of I represents the range of chemical shifts. For example, I _180.0-135.0 represents the integrated intensity of the ¹³ C signal detected between 180.0 ppm and 135.0 ppm.
The attribution was made with reference to the non-patent literature Macromolecules 1984, 17, 1756-1761 and Macromolecules 1979, 12, 41.
When the number of branches is indicated by "<0.1" including an inequality sign, this means that the branch is present as a structural unit in the copolymer but in an amount of less than 0.1 mol % taking into account significant figures. Furthermore, "not detected" means below the detection limit.

(6) Infrared absorption spectrum A sample was melted at 180° C. for 3 minutes and compression molded to prepare a film with 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 integration: 16 to 512 times Resolution: 4.0cm ^-1
Measurement wavelength: 5000-500cm ^-1

(7) Tensile Impact Strength 1) Method for Preparing Tensile Impact Strength Test Samples The sample was placed in a 1 mm thick heated press mold and preheated for 5 minutes in a heat press at a surface temperature of 180 ° C. The sample was melted and degassed by repeatedly applying pressure and decompression, and the residual gas in the sample was then degassed. It was then pressurized to 4.9 MPa and held for 5 minutes. Then, under a pressure of 4.9 MPa, the sample was gradually cooled at a rate of 10 ° C./min. When the temperature had dropped to near room temperature, the molded plate was removed from the mold. The resulting molded plate was conditioned for 48 hours or more in an environment of 23 ± 2 ° C. and 50 ± 5 ° C. humidity. A test piece having the shape of ASTM D1822 Type-S was punched out from the conditioned press plate to prepare a tensile impact strength test sample.

2) Tensile impact strength test conditions Using the above test specimens, the tensile impact strength was measured with reference to Method B of JIS K 7160-1996. Note that the only difference from JIS K 7160-1996 was the shape of the test specimen. Other measurement conditions, etc., were the same as those in JIS K 7160-1996.

(8) Haze 1) Method for preparing a press plate of a sample The sample was placed in a heat press mold with dimensions of 50 mm x 60 mm and a thickness of 0.5 mm, and preheated for 5 minutes in a heat press at a surface temperature of 180°C. Residual gas in the sample was degassed by repeatedly applying pressure and depressurizing pressure, and the sample was then pressurized to 4.9 MPa and held for 3 minutes. The sample was then transferred to a press at a surface temperature of 25°C and cooled by holding the pressure at 4.9 MPa for 3 minutes to produce a press plate with a thickness of approximately 0.5 mm.
2) Haze Measurement Conditions Using the above test specimen, the haze was measured in accordance with JIS K 7136-2000.

(9) Glass Adhesion Strength The glass adhesion strength was measured by vacuum laminating a sample processed into a press plate and a float glass plate to prepare a laminate, and then conducting a peel test. The methods for preparing the press plate and the laminate and the method for measuring the adhesive strength will be explained below.

1) Method for preparing a press plate for a sample The sample was placed in a heat press mold with dimensions of 50 mm x 60 mm and a thickness of 0.5 mm, preheated for 5 minutes in a heat press at a surface temperature of 180 ° C., and then degassed by repeatedly applying pressure and depressurizing the sample to remove residual gas. The sample was then pressurized to 4.9 MPa and held for 3 minutes. The sample was then transferred to a press at a surface temperature of 25 ° C. and cooled by holding the pressure at 4.9 MPa for 3 minutes to produce a press plate with a thickness of approximately 0.5 mm.

2) Glass Sheet Preparation Method Commercially available float glass sheets manufactured by the float process were used as glass sheets. In the float process, molten glass is poured onto molten tin and cooled and solidified on the molten tin to obtain highly smooth glass sheets. The lower surface of float glass sheets manufactured by this float process, i.e., the surface that was in contact with the molten tin (hereinafter referred to as the bottom surface), contains tin and is characterized by a higher amount of silanol groups than the surface that was not in contact with the molten tin (hereinafter referred to as the top surface). Furthermore, because silanol groups in glass have the property of adsorbing hydrocarbon-based substances present in the atmosphere, it is desirable to clean the glass sheets used in the adhesion test immediately before the test. Based on the above, in the present invention, 2.5 mm thick float glass sheets were washed with a neutral detergent before the test, dried at 70°C, and cut to dimensions of 50 mm x 60 mm. The top surface was then bonded to a sample press plate.

3) Manufacturing method of laminate of sample and plate glass Using a vacuum laminator (manufactured by NPC Corporation), the top surfaces of the press plate and the plate glass were laminated together at a heating temperature of 180°C for 10 minutes, and then sandwiched between two aluminum plates and quenched for 3 minutes to obtain a two-type, two-layer laminate. A 10 mm wide slit was made in the sheet portion of this laminate to prepare a test specimen.

4) Method for measuring adhesive strength of laminate The laminate obtained by the laminate manufacturing method was used as a test piece, and peeled at a take-up speed of 50 mm/min using a Tensilon (manufactured by Toyo Seiki Co., Ltd.) tensile tester, and the maximum stress was determined as the adhesive strength (N/10 mm).

<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). According to Example 1 of WO 2010/050256, a nickel complex (B-27DM/Ni) was synthesized in which B-27DM and Ni(COD) ₂ were reacted in a 1:1 ratio using bis(1,5-cyclooctadiene)nickel(0) (referred to as Ni(COD) ₂ ).

(Production Example 1): Production of ionomer-based resin precursor
An ethylene/tBu acrylate/norbornene copolymer was produced using a transition metal complex (B-27DM/Ni complex). The copolymer was produced with reference to Production Example 1 or Production Example 3 described in JP 2016-79408 A. The production conditions and production results, which were appropriately changed, such as the type and amount of metal catalyst, the amount of trioctylaluminum (TNOA), the amount of toluene, the type and amount of comonomer, the ethylene partial pressure, the polymerization temperature, and the polymerization time, are shown in Table 1, and the physical properties of the resulting copolymer are shown in Table 2.

<(Resin 1): Production of Ionomer-Based Resin-1>
In a 500 ml separable flask, 40 g of the copolymer obtained in Production Example 1, 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 reached 5 or higher. The solvent was distilled off from the remaining solution under reduced pressure, and the solution was dried to a constant weight.
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.
This confirmed the decomposition of t-Bu ester and the production of carboxylic acid, yielding ionomer base resin 1. The physical properties of the resulting resin are shown in Table 3.

<Ionomers 1 to 4: Production of Ionomers-1>
1) Preparation of Zn Ion Supply Source 21.8 g of ethylene/methacrylic acid (MAA) copolymer (manufactured by Mitsui-Dow Polychemicals Co., Ltd., brand: Nucrel (registered trademark) N1050H), 18 g of zinc oxide, and 0.2 g of zinc stearate were charged into a Labo Plastomill: Roller Mixer R60 model manufactured by Toyo Seiki Co., Ltd., equipped with a small mixer having a capacity of 60 ml, and the mixture was kneaded at 180°C and 40 rpm for 3 minutes to prepare a Zn ion supply source.

2): Preparation of ionomer 40 g of Resin 1 was placed in a Labo Plastomill (Roller Mixer R60) manufactured by Toyo Seiki Co., Ltd., equipped with a 60 ml small mixer, and dissolved by kneading at 160°C and 40 rpm for 3 minutes. Thereafter, a Zn ion source was added so as to achieve the desired degree of neutralization, and kneading was continued for 5 minutes at 250°C and 40 rpm.
In the IR spectrum of the obtained resin, the peak near 1700 cm ^-1 derived from the carbonyl group of the carboxylic acid (dimer) was reduced, and the peak near 1560 cm ^-1 derived from the carbonyl group of the carboxylate salt group was increased. The reduction in the peak near 1700 cm ^-1 derived from the carbonyl group of the carboxylic acid (dimer) confirmed that an ionomer with the desired degree of neutralization had been produced. The physical properties of the obtained ionomer are shown in Tables 4 and 5.

Comparative Example 1: E/MAA-based binary ionomer An ionomer resin (HIMILAN® HIM1706, manufactured by Dow Mitsui Polychemicals Co., Ltd.) which is a copolymer of ethylene, methacrylic acid, and zinc methacrylate and produced by a high-pressure radical process was used as a reference ionomer. The physical properties are shown in Tables 4 and 5.

Comparative Example 2: E/MAA-based binary ionomer An ionomer resin (HIMILAN® HIM1707, manufactured by Dow Mitsui Polychemicals Co., Ltd.) which is a copolymer of ethylene, methacrylic acid, and zinc methacrylate and produced by a high-pressure radical process was used as a reference ionomer. The physical properties are shown in Tables 4 and 5.

<Discussion of the results of Examples and Comparative Examples>
Since Comparative Examples 1 and 2 are ionomers composed of a base resin produced by a high-pressure radical method and a metal ion source, their molecular structures have many long-chain branches, and the phase angle δ at the absolute value of the complex modulus G ^* = 0.1 MPa is less than 50°. On the other hand, Examples 1 to 10 are ionomers composed of a base resin produced using a specific transition metal catalyst and a metal ion, so their molecular structures are substantially linear, and the phase angle δ (G ^* = 0.1 MPa) is 50° or more.
The measurement results shown in Table 5 show that the resin layer in the laminate examples of the present invention is firmly bonded to the glass layer and has high transparency and tensile impact strength. Comparative Examples 1 and 4, and Comparative Examples 2 and 7 are existing ionomers with equivalent acid contents and degrees of neutralization, but the comparative examples have inferior adhesive strength and tensile impact strength compared to the examples, although they have equivalent transparency.
This indicates that the ionomer of the present invention, which has a phase angle δ (G ^* =0.1 MPa) of 50° or more, has a relatively better balance of transparency, adhesive strength, and tensile impact strength than conventional ionomers.

[Ionomer Composition, Degree of Neutralization, and Metal Ion Species in the Present Invention]
Examples 1 to 10 are ionomers with different base resin compositions, degrees of neutralization, and metal ion species, but all of them satisfy the desired transparency (haze), desired adhesive performance (adhesive strength), and desired strength (tensile impact strength), and have superior adhesive strength and tensile impact strength to those of Comparative Examples 1 and 2, which are existing ionomers.
As shown in Figure 3, this indicates that the multi-component ionomer of the present invention, which has a phase angle δ (G ^* = 0.1 MPa) of 50° or more, has a relatively excellent balance of transparency, adhesive strength, and tensile impact strength, regardless of the degree of neutralization.
In the present invention, the desired haze is at least 25% or less, and preferably 20% or less; the desired adhesive strength is preferably 2.0 N/10 mm or more, more preferably 2.3 N/10 mm or more, even more preferably 2.5 N/10 mm or more, and still more preferably 3.0 N/10 mm or more; and the desired tensile impact strength is preferably 700 kJ/ ^m2 or more, more preferably 720 kJ/ ^m2 or more, even more preferably 800 kJ/ ^m2 or more, and particularly preferably 1000 kJ/ ^m2 or more.

Comparing these examples and comparative examples, it was found that the ionomer of the present invention, due to its distinctive molecular structure, exhibits an excellent balance of transparency, adhesion, and impact resistance not found in conventional ionomers.

By using glass laminate resins containing the ionomer of the present invention, it is expected that laminated glass interlayers and solar cell module encapsulants can be obtained that have excellent adhesion and impact resistance while maintaining the same level of transparency as glass laminate resins containing conventional ionomers. In the case of laminated glass, it is expected that safety will be improved while maintaining visibility, making it highly useful for automotive glass and architectural glass. In the case of solar cell modules, it is expected that durability will be improved without reducing conversion efficiency.

Claims (7)

a copolymer (P) comprising, as essential structural 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 acid anhydride group, in which the structural unit amount of the structural units (A) is 96.5 mol % or less, and at least a portion of the carboxyl groups and/or dicarboxylic acid anhydride groups are 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,
A resin for glass laminates containing an ionomer characterized in that the phase angle δ at the absolute value of the complex elastic modulus G ^* = 0.1 MPa measured with a rotational rheometer is 50 degrees to 75 degrees, and the glass adhesive strength measured according to the following method is 2.0 N/10 mm or more.
1) Sample press plate adjustment method
The ionomer sample was placed in a heat press mold with dimensions of 50 mm x 60 mm and a thickness of 0.5 mm, preheated for 5 minutes in a heat press at a surface temperature of 180°C, and then degassed by repeatedly applying and depressurizing pressure to remove residual gas from the sample. The sample was then further pressurized to 4.9 MPa and held for 3 minutes. The sample was then transferred to a press at a surface temperature of 25°C and cooled by holding at a pressure of 4.9 MPa for 3 minutes to produce a pressed plate with a thickness of approximately 0.5 mm.
2) How to adjust the glass plate
The glass plate used was a commercially available float glass plate manufactured by the float process. Immediately before the test, the 2.5 mm thick float glass plate was washed with a neutral detergent, dried at 70°C, and cut to a size of 50 mm x 60 mm. The top surface of the glass plate was then bonded to the press plate of the sample.
3) Manufacturing method of laminate of sample and glass plate
Using a vacuum laminator, the top surfaces of the press plate and the glass plate were laminated together at a heating temperature of 180°C for 10 minutes, then sandwiched between two aluminum plates and quenched for 3 minutes to obtain a two-layer, two-kind laminate. A 10 mm wide slit was made in the sheet portion of this laminate to prepare a test specimen.
4) Method for measuring adhesive strength of laminate
The laminate obtained by the laminate manufacturing method is used as a test piece, and is peeled off at a take-up speed of 50 mm/min using a Tensilon tensile tester, and the maximum stress is determined as the glass adhesive strength (N/10 mm). 2. The resin for glass laminates 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. 2. The resin for glass laminates according to claim 1, wherein the number of methyl branches of the copolymer (P) calculated by ¹³ C-NMR is 5 or less per 1,000 carbon atoms. The resin for glass laminates according to any one of claims 1 to 3, wherein the copolymer (P) contains 2 to 20 mol% of the structural unit (B) in the copolymer. The resin for glass laminates according to any one of claims 1 to 4, characterized in that the structural unit (A) is a structural unit derived from ethylene. The resin for glass laminates according to any one of claims 1 to 5, characterized in that the copolymer (P) is produced using a transition metal catalyst containing a transition metal from Groups 8 to 11 of the periodic table. The resin for glass laminates according to claim 6, 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.