JP2024111724A - Adhesive polymer composition and laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive polymer composition having excellent adhesive strength and excellent heat resistance by which it is possible to maintain good adhesive strength even after being heated.

SOLUTION: An adhesive polymer composition includes a propylene-ethylene copolymer modified by at least one selected from the group consisting of a composition (A): a propylene-based polymer, a composition (B): an ethylene-based polymer whose density is 0.94-0.97 g/cm³, and a composition (C): an unsaturated carboxylic acid and a derivative thereof.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to an adhesive polymer composition and a laminate.

Polyolefin polymers have excellent moldability and chemical resistance and are widely used in various fields.
On the other hand, polyolefin-based polymers are inferior in gas barrier properties and mechanical strength, and therefore a method of laminating a layer made of a polyolefin-based polymer with a gas barrier layer made of polyamide or saponified ethylene-vinyl acetate copolymer (EVOH), which have excellent gas barrier properties, has been widely adopted.

When an adhesive layer is provided in the laminate to bond the gas barrier layer and the layer made of a polyolefin polymer, the adhesive layer is made of an adhesive polymer composition containing a polyolefin polymer modified with a polar group.

The basic layer structure of a laminate is a five-layer structure of "main material layer/adhesive layer/gas barrier layer/adhesive layer/main material layer," and from the standpoint of cost and hygiene, the mainstream structure uses a layer made of a polyolefin polymer as the main material layer.

As the polyolefin polymer used in the main material layer, for example, when the operating temperature range is from low temperatures below 0°C to around 100°C, ethylene polymers have generally been used. Also, in applications requiring high-temperature resistance such as retort processing, or applications requiring hardness, transparency, etc., propylene polymers have generally been used.

Usually, an adhesive layer made of an adhesive polymer composition containing an ethylene-based polymer modified with a polar group is used for the main material layer made of an ethylene-based polymer. Also, an adhesive layer made of an adhesive polymer composition containing a propylene-based polymer modified with a polar group is used for the main material layer made of a propylene-based polymer.

Among the above adhesive layers, the adhesive polymer composition containing a propylene-based polymer modified with a polar group has sufficiently good heat resistance and high rigidity, but improvement is desired in terms of adhesive strength.

In response to this, Patent Document 1 discloses an adhesive resin composition that contains specific amounts of polypropylene resin, high-density polyethylene, and modified propylene resin with a modification amount of 1% by mass or more. This is said to enable the production of a laminate that has excellent coextrusion moldability, interlayer adhesion, and strength.

JP 2019-210317 A

Adhesive polymer compositions containing propylene-based polymers may be exposed to high-temperature environments when used in coolant tubes, fuel parts, etc., or when deformed into a desired shape. In response to this, the present inventors have come to the realization that the adhesive resin composition described in Patent Document 1 has excellent adhesive strength, but does not have sufficient heat resistance, and has a problem in that the adhesiveness decreases, especially after being exposed to a high-temperature environment for a long period of time.

The present invention aims to provide an adhesive polymer composition with excellent heat resistance that has excellent adhesive strength and can maintain good adhesive strength even after heating, and a laminate having an adhesive layer made of the adhesive polymer composition.

As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by preparing an adhesive polymer composition that further contains an unsaturated carboxylic acid-modified propylene-ethylene copolymer in addition to a propylene-based polymer and an ethylene-based polymer having a density within a specific range, and have thus completed the present invention.
That is, the gist of the present invention is as follows.

A first aspect of the present invention is an adhesive polymer composition comprising the following components (A) to (C):
Component (A): A propylene-based polymer; Component (B): An ethylene-based polymer having a density of 0.94 g/ ^cm3 or more and 0.97 g/ ^cm3 or less; Component (C): A propylene-ethylene copolymer modified with at least one selected from the group consisting of unsaturated carboxylic acids and derivatives thereof.

Aspect 2 of the present invention is the adhesive polymer composition of aspect 1, in which component (C) is a propylene-ethylene copolymer modified with at least one of maleic acid and maleic anhydride.

Aspect 3 of the present invention is an adhesive polymer composition according to aspect 1 or aspect 2, in which the melt flow rate of component (A) measured according to JIS K 7210:2014 at a temperature of 230°C and a load of 21.2N is 0.1 to 50 g/10 min, and the melt flow rate of component (B) measured according to JIS K 7210:2014 at a temperature of 190°C and a load of 21.2N is 0.1 to 20 g/10 min.

In aspect 4 of the present invention, in the adhesive polymer composition according to any one of aspects 1 to 3, the modification amount of the component (C) is 0.5 mass% or more.

Aspect 5 of the present invention is an adhesive polymer composition according to any one of aspects 1 to 4, in which the propylene-ethylene copolymer in component (C) is a random copolymer or a block copolymer.

In aspect 6 of the present invention, in the adhesive polymer composition according to any one of aspects 1 to 5, the content of component (A) relative to the total of component (A) and component (B) is 51 to 75 mass%.

In aspect 7 of the present invention, in the adhesive polymer composition of aspect 6, the content of component (A) is 51 to 65 mass %.

In aspect 8 of the present invention, in the adhesive polymer composition according to any one of aspects 1 to 7, the content of component (C) is 0.5 to 15 parts by mass per 100 parts by mass of the total of component (A) and component (B).

Aspect 9 of the present invention is a laminate including an adhesive layer made of any one of the adhesive polymer compositions of aspects 1 to 8 and a gas barrier layer laminated together.

Aspect 10 of the present invention is the laminate of aspect 9, in which the gas barrier layer is a layer containing polyamide.

In aspect 11 of the present invention, the laminate of aspect 9 or aspect 10 is a hollow molded product.

In aspect 12 of the present invention, the hollow molded product, which is the laminate of aspect 11, is a tube.

Aspect 13 of the present invention includes a configuration in which the tube that is the laminate of aspect 12 is a coolant tube, and the gas barrier layer, the adhesive layer, and the polyolefin polymer layer are laminated in this order.

In aspect 14 of the present invention, in the laminate of aspect 13, the polyolefin polymer layer has a Duro D hardness of 25 to 70 as measured according to JIS K 6253:2006.

In aspect 15 of the present invention, the laminate of aspect 9 or aspect 10 is a sheet.

In aspect 16 of the present invention, any one of the laminates in aspects 9 to 14 is used in a fuel component.

The present invention provides an adhesive polymer composition having excellent adhesive strength and excellent heat resistance, which can maintain good adhesive strength even after heating. Therefore, a laminate having an adhesive layer made of the adhesive polymer composition is very useful in applications where it is deformed by heating or exposed to high-temperature environments, such as coolant tubes and fuel parts.

FIG. 1 is a schematic cross-sectional view showing the configuration of a coolant tube in this embodiment.

The following describes in detail the embodiments of the present invention, but the following embodiments are examples (representative examples) of the present invention, and the present invention is not limited to these. The present invention can be carried out in any modified form without departing from the gist of the present invention.
In this specification, when a numerical value or physical property value is enclosed before and after "~", the values before and after are included. In addition, in this specification, "mass%" and "weight%", and "parts by mass" and "parts by weight" are synonymous.

<Adhesive polymer composition>
The adhesive polymer composition according to this embodiment contains the following components (A) to (C).
Component (A): A propylene-based polymer; Component (B): An ethylene-based polymer having a density of 0.94 g/ ^cm3 or more and 0.97 g/ ^cm3 or less; Component (C): A group consisting of unsaturated carboxylic acids and derivatives thereof. Propylene-ethylene copolymer modified with at least one selected from

Component (A): Propylene-Based Polymer
The component (A) in this embodiment is a propylene-based polymer.
The propylene-based polymer is a component that imparts heat resistance and rigidity to the adhesive polymer composition according to the present embodiment, and is also a component that imparts adhesion and extrusion processability when the adhesive polymer composition is bonded to a propylene-based polymer layer as an adhesive layer.

Examples of the propylene-based polymer that is component (A) in this embodiment include propylene homopolymers and propylene-α-olefin copolymers. Among these, propylene homopolymers are preferred from the viewpoint of the balance between heat resistance and rigidity.

Examples of the propylene-α-olefin copolymer include propylene-based (co)polymers such as propylene-ethylene copolymer, propylene-butene copolymer, propylene-ethylene-hexene copolymer, propylene-ethylene-octene copolymer, propylene-butene-hexene copolymer, propylene-butene-octene copolymer, and propylene-hexene-octene copolymer. Examples of the above copolymers include random copolymers and block copolymers.
In this specification, the term "(co)polymer" is a general term for homopolymers and copolymers, and the term "propylene-based polymer" is a general term for propylene homopolymers and propylene copolymers.

In this embodiment, the propylene-based polymer of component (A) may be used alone, or two or more types having different compositions, physical properties, etc. may be used in combination. When two or more types are used in combination, the combination may be a combination of polymers having different structures, etc., such as a combination of a propylene-based random copolymer and a propylene-based block polymer.

In the present embodiment, the propylene unit content in the propylene polymer of component (A) is preferably 80 to 100 mol %. From the viewpoint of heat resistance, the content is preferably 80 mol % or more, and more preferably 85 mol % or more. The upper limit of the content is not particularly limited and may be 100 mol %. The content of 100 mol % means that the propylene polymer of component (A) is a propylene homopolymer.
In addition, the term "unit" in this specification means a monomer unit contained in a copolymer. For example, a "propylene unit" in a propylene-based polymer means a monomer unit based on propylene. Similarly, a monomer unit based on ethylene is called an "ethylene unit."

The propylene-based polymer of component (A) in the present embodiment may be either a produced product or a commercially available product. When the propylene-based polymer is produced, it is produced by a conventionally known method.
Examples of methods for producing the propylene polymer include known methods such as a batch method, a gas phase method, and a slurry method using a catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst.

The flexural modulus of the propylene-based polymer, which is component (A) in this embodiment, is preferably 800 to 2000 MPa, more preferably 1000 to 1800 MPa. From the viewpoint of rigidity, the flexural modulus is preferably 800 MPa or more, more preferably 1000 MPa or more. For the same reason, the flexural modulus is preferably 2000 MPa or less, more preferably 1800 MPa or less.
In this specification, the flexural modulus is a value measured in accordance with JIS K 7171:1994.

The melt flow rate (MFR) of the propylene polymer, which is component (A) in this embodiment, is not particularly limited, but is preferably 0.1 to 50 g/10 min, more preferably 0.3 to 20 g/10 min, and even more preferably 0.5 to 5 g/10 min. Here, from the viewpoint of reducing the energy load during production and the processability of the molded product, the MFR is preferably 0.1 g/10 min or more, more preferably 0.3 g/10 min or more, and even more preferably 0.5 g/10 min or more. From the same viewpoint, the MFR is preferably 50 g/10 min or less, more preferably 20 g/10 min or less, and even more preferably 5 g/10 min or less.
In this specification, the melt flow rate (MFR) of the propylene-based polymer of component (A) is a value measured in accordance with JIS K 7210:2014 under conditions of a temperature of 230°C, a load of 21.2 N, and a time of 10 minutes.

In one embodiment of the propylene-based polymer, which is component (A) in this embodiment, the propylene-based polymer preferably has a propylene unit content of 80 to 100 mol %, a flexural modulus of 800 to 2000 MPa, and a melt flow rate (MFR) of 0.1 to 50 g/10 min, and more preferably satisfies both of these.

Component (B): Ethylene-Based Polymer
The component (B) in this embodiment is an ethylene polymer having a density of 0.94 g/cm ³ or more and 0.97 g/cm ³ or less, and is an ethylene polymer generally called high density polyethylene.
The ethylene polymer is a component for imparting adhesiveness and mechanical strength to the adhesive polymer composition according to this embodiment.

Examples of the ethylene polymer of component (B) in this embodiment include ethylene homopolymers and ethylene-α-olefin copolymers.
Examples of the ethylene-α-olefin copolymer include ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-propylene-butene copolymer, ethylene-propylene-hexene copolymer, ethylene-propylene-octene copolymer, ethylene-butene-hexene copolymer, ethylene-butene-octene copolymer, and ethylene-hexene-octene copolymer. The above copolymer is preferably a random copolymer or a block copolymer. Among these, ethylene-butene copolymer and ethylene-hexene copolymer are preferred, and ethylene-butene random copolymer, ethylene-butene block copolymer, ethylene-hexene random copolymer, and ethylene-hexene block copolymer are more preferred.

In this embodiment, the ethylene polymer of component (B) may be used alone or in combination with two or more polymers having different compositions, physical properties, etc.

In this embodiment, the content of ethylene units in the ethylene-based polymer of component (B) is preferably 80 to 100 mol%. From the viewpoint of heat resistance, the content is preferably 80 mol% or more, and more preferably 90 mol% or more. There is no particular upper limit to the content, and it may be 100 mol%, i.e., an ethylene homopolymer, but in the case of an ethylene-α-olefin copolymer, it is more preferably 99.9 mol% or less.

When the adhesive polymer composition according to this embodiment contains a copolymer containing propylene and ethylene as monomer units, whether it is a propylene-based polymer (component (A)) or an ethylene-based polymer (component (B)) is determined by the content of propylene units and the content of ethylene units in the copolymer.

That is, when the content of propylene units in a copolymer is greater than the content of ethylene units, the copolymer is classified as a propylene-based polymer of component (A). When the content of ethylene units in a copolymer is greater than the content of propylene units, the copolymer is classified as an ethylene-based polymer, and when the density of the copolymer is 0.94 g/ ^cm3 or more and 0.97 g/ ^cm3 or less, the copolymer is classified as an ethylene-based polymer of component (B).

Furthermore, when the copolymer is a ternary or higher copolymer, if the content of propylene units among the monomer units in the copolymer is the highest, the copolymer is classified as a propylene-based copolymer of component (A).Similarly, if the content of ethylene units is the highest, the copolymer is classified as an ethylene-based copolymer, and if the density is 0.94 g/ ^cm3 or more and 0.97 g/ ^cm3 or less, the copolymer is classified as an ethylene-based polymer of component (B).

The ethylene-based polymer of component (B) in this embodiment may be a commercially available product or may be produced. When the ethylene-based polymer is produced, it is produced by a conventionally known method.
Examples of methods for producing ethylene polymers include a method using a chromium catalyst, a method using a Ziegler-Natta catalyst to polymerize in a solvent, and a method of polymerizing in a gas phase. As for the polymerization method, a method in which polymerization is performed in a single stage or a multistage polymerization can be selected. By selecting the polymerization method, the molecular weight distribution can be adjusted.

The density of the ethylene polymer which is component (B) in this embodiment is 0.94 to 0.97 g/cm ³ , preferably 0.94 to 0.965 g/cm ³ , and more preferably 0.945 to 0.96 g/cm ^3. From the viewpoints of rigidity and heat resistance, the density is preferably 0.94 g/cm ³ or more, and more preferably 0.945 g/cm ³ or more. From the viewpoint of adhesiveness, the density is preferably 0.97 g/cm ³ or less, more preferably 0.965 g/cm ³ or less, and even more preferably 0.96 g/cm ³ or less.
In this specification, the density is a value measured by an underwater displacement method in accordance with JIS K 7112:1999.

The melt flow rate (MFR) of the ethylene polymer, which is component (B) in this embodiment, is not particularly limited, but is preferably 0.1 to 20 g/10 min, more preferably 0.1 to 10 g/10 min, and even more preferably 0.1 to 5 g/10 min. Here, from the viewpoint of the appearance when molded and the maintenance of the fine dispersion of component (B), the above MFR is preferably 0.1 g/10 min or more. From the same viewpoint, the above MFR is preferably 20 g/10 min or less, more preferably 10 g/10 min or less, and even more preferably 5 g/10 min or less.
In this specification, the melt flow rate (MFR) of the ethylene polymer of component (B) is a value measured in accordance with JIS K 7210:2014 under conditions of a temperature of 190°C, a load of 21.2 N, and a time of 10 minutes.

In addition to the melt flow rate (MFR) of the ethylene polymer, which is component (B), being within the above range, the melt flow rate (MFR) of the propylene polymer, which is component (A), is preferably 0.1 to 50 g/10 min, more preferably 0.3 to 20 g/10 min, and even more preferably 0.5 to 5 g/10 min.

The molecular weight distribution (Mw/Mn) of the ethylene polymer which is component (B) in this embodiment is preferably 3 to 20, and more preferably 5 to 19. From the viewpoints of adhesive strength and processability, the molecular weight distribution is preferably 3 or more, and more preferably 5 or more. From the same viewpoint, the molecular weight distribution is preferably 20 or less, and more preferably 19 or less.
In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) in the molecular weight distribution of the ethylene polymer, which is the component (B), are values measured by gel permeation chromatography (GPC) in terms of polystyrene, and the molecular weight distribution (Mw/Mn) is calculated as the ratio of the measured Mw and Mn.

In one aspect of the ethylene-based polymer which is component (B) in this embodiment, it is preferable that the density is 0.94 to 0.97 g/cm ³ and that the content of ethylene units in the ethylene-based polymer is 80 to 100 mol %. Furthermore, it is more preferable that the melt flow rate (MFR) is 0.1 to 20 g/10 min and/or the molecular weight distribution (Mw/Mn) is 3 to 20, and it is even more preferable that the both are satisfied.

Component (C): Modified propylene-ethylene copolymer
Component (C) in this embodiment is a propylene-ethylene copolymer modified with at least one selected from the group consisting of unsaturated carboxylic acids and derivatives thereof (hereinafter, may be simply referred to as a "modified propylene-ethylene copolymer").

The modified propylene-ethylene copolymer is a component that contributes to the adhesiveness of the adhesive polymer composition according to this embodiment, and it has been found that it contributes to good adhesion, as well as good adhesion after heating.
The adhesive polymer composition used in the adhesive layer generally swells when heated and shrinks when cooled, and it is believed that repeated heating and cooling will cause a decrease in adhesiveness due to the difference in swelling and shrinking behavior between the adhesive layer and the adherend layer. In contrast, it is believed that the adhesive polymer composition according to the present embodiment contains the modified propylene-ethylene copolymer of component (C) and thus has improved compliance with the swelling and shrinking behavior, and can maintain good adhesive strength even after heating.

In this embodiment, the modified propylene-ethylene copolymer of component (C) is preferably a random copolymer or a block copolymer, and from the viewpoint of more suitably exerting the effects of component (C), a random copolymer is more preferable.

In this embodiment, the modified propylene-ethylene copolymer of component (C) may be used alone, or two or more types of copolymers with different monomer compositions, physical properties, types of unsaturated carboxylic acid components used in graft modification, or amounts of modification may be used in combination.

The melt flow rate (MFR) of the modified propylene-ethylene copolymer, which is component (C) in this embodiment, is not particularly limited, but is preferably 0.1 to 150 g/10 min, more preferably 0.1 to 100 g/10 min, and even more preferably 0.1 to 50 g/10 min. From the viewpoint of adhesiveness, the MFR is preferably 150 g/10 min or less, more preferably 100 g/10 min or less, and even more preferably 50 g/10 min or less. There is no particular limit to the lower limit of the MFR, but from the viewpoint of general manufacturability, it is usually 0.1 g/10 min or more.
In this specification, the melt flow rate (MFR) of the modified propylene-ethylene copolymer, which is component (C), is a value measured in accordance with JIS K 7210:2014 under conditions of a temperature of 180°C, a load of 21.2 N, and a time of 10 minutes.

The main component of the monomer units of the propylene-ethylene copolymer before modification (hereinafter sometimes referred to as the "raw polypropylene"), which is the raw material of the modified propylene-ethylene copolymer of component (C) in this embodiment, is propylene, and further, ethylene is also considered to be a monomer unit.
In addition, when the raw material polypropylene is a ternary or higher copolymer, an α-olefin other than propylene and ethylene may be used as a monomer unit. Examples of the α-olefin other than propylene and ethylene include 1-butene, 1-pentene, 1-hexene, and 4-methyl-1-pentene.
From the viewpoint of compatibility with components (A) and (B), the raw polypropylene used as the raw material for component (C) is preferably a binary copolymer of propylene and ethylene.

Only one type of raw polypropylene may be used as the raw material for component (C), or two or more types with different compositions, physical properties, etc. may be used in combination.

The term "main component" as used herein means that the content of propylene units in the raw material polypropylene is 50 mol % or more, and the content is preferably 80 to 99.9 mol %, and more preferably 85 to 99.5 mol %.
Here, the content may be 50 mol% or more, but from the viewpoint of compatibility with component (A), the content is preferably 80 mol% or more, more preferably 85 mol% or more, and from the viewpoint of adhesiveness after heat treatment, the content is preferably 99.9 mol% or less, more preferably 99.5 mol% or less.

The content of ethylene units in the raw polypropylene used as the raw material for component (C) is preferably 0.1 to 20 mol %, and more preferably 0.1 to 15 mol %, regardless of whether the raw polypropylene is a binary copolymer of propylene and ethylene or a ternary or higher copolymer in which an α-olefin is also a monomer unit.
From the viewpoint of adhesion after heat treatment, the content is preferably 0.1 mol% or more, and more preferably 0.1 mol% or more. From the viewpoint of compatibility with component (A), the content is preferably 20 mol% or less, and more preferably 15 mol% or less.

The propylene unit content and ethylene unit content in the raw polypropylene used to make component (C) can be considered to be approximately the same as the propylene unit content and ethylene unit content in the modified propylene-ethylene copolymer, which is component (C) after modification. However, in reality, molecular cleavage occurs at the propylene units during modification, so the propylene unit content and ethylene unit content are presumed to change before and after modification, and will not be exactly the same.

There are no restrictions on the stereoregularity of the raw polypropylene used to produce component (C), and the propylene chain may be isotactic, syndiotactic, atactic, stereoblock, etc. Among these, the propylene chain is preferably isotactic.

The raw polypropylene used as the raw material of component (C) may be either a manufactured product or a commercially available product. When the raw polypropylene is manufactured, it is manufactured by a conventionally known method.
In producing the raw material polypropylene, a known catalyst can be appropriately used for the polymerization. As described above, the polymerization form is preferably random copolymerization or block copolymerization.

The melt flow rate (MFR) of the raw polypropylene used as the raw material for component (C) is not particularly limited, but is preferably 0.1 to 100 g/10 min, more preferably 0.1 to 50 g/10 min, and even more preferably 0.1 to 20 g/10 min. From the viewpoint of modification, the MFR is preferably 100 g/10 min or less, more preferably 50 g/10 min or less, and even more preferably 20 g/10 min or less. There is no particular lower limit for the MFR, but from the viewpoint of general manufacturability, it is usually 0.1 g/10 min or more.
In this specification, the melt flow rate (MFR) of the raw material polypropylene is a value measured in accordance with JIS K 7210:2014 under conditions of a temperature of 230°C, a load of 21.2 N, and a time of 10 minutes.

The modified propylene-ethylene copolymer of component (C) in this embodiment is a copolymer in which the raw material polypropylene is modified with at least one selected from the group consisting of unsaturated carboxylic acids and derivatives thereof (hereinafter, sometimes referred to as an "unsaturated carboxylic acid component").
The unsaturated carboxylic acid component may be used alone or in combination of two or more thereof. Furthermore, vinyl silanes such as vinyltrimethoxysilane may be used in combination with the unsaturated carboxylic acid component.

As the unsaturated carboxylic acid used for modification, α,β-ethylenically unsaturated carboxylic acids are preferred, such as acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, tetrahydrofumaric acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, and Nadic acid TM (endo cis-bicyclo[2,2,1]hept-5-ene-2,3 dicarboxylic acid).

Examples of derivatives of unsaturated carboxylic acids used for modification include acid anhydrides and carboxylates of the above unsaturated carboxylic acids, and may also include derivatives such as acid halides, amides, and imides. Of these derivatives, acid anhydrides are preferred.

Among these, component (C) in this embodiment is preferably a propylene-ethylene copolymer modified with at least one of maleic acid and maleic anhydride, and even more preferably a propylene-ethylene copolymer modified with maleic anhydride.

The method for modifying the raw material polypropylene with the unsaturated carboxylic acid component is not particularly limited, but examples thereof include a melt modification method and a solution modification method.
The melt modification method includes a method in which raw material polypropylene and an unsaturated carboxylic acid component are mixed in advance, if necessary, with a radical generator, and then melt-kneaded in a kneader to cause a reaction. Another embodiment of the melt modification method includes a method in which a mixture of a radical generator and an unsaturated carboxylic acid component is added to raw material polypropylene molten in a kneader from a charging port and caused to react.

For the above mixing, a Henschel mixer, a ribbon blender, a V-type blender or the like is usually used.
For melt kneading, a single-screw or twin-screw extruder, a roll, a Banbury mixer, a kneader, a Brabender mixer, or the like is usually used.

Examples of solution modification methods include adding an unsaturated carboxylic acid component and a radical generator to a solution of raw material polypropylene dissolved in an organic solvent, and reacting the mixture at a temperature of usually 60 to 350°C, preferably 80 to 190°C, for usually 0.5 to 15 hours, preferably 1 to 10 hours.

The radical generator used in the modification reaction is not particularly limited, but examples of the radical generator that can be used include organic peroxides and organic peresters such as benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(peroxybenzoate)hexyne-3, lauroyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butyl perbenzoate, tert-butyl perisobutyrate, tert-butyl perpivalate, and cumyl perpivalate, as well as azo compounds such as azobisisobutyronitrile and dimethylazoisobutyrate.

The radical generator can be appropriately selected depending on the type and MFR of the raw material polypropylene, the type of unsaturated carboxylic acid component, and the reaction conditions. Only one type of radical generator may be used, or two or more types may be used in combination.

The amount of the radical generator is not limited, but is preferably 0.001 to 10 parts by mass, and more preferably 0.005 to 7 parts by mass, per 100 parts by mass of raw polypropylene. Here, from the viewpoint of suppressing the risk of the molecular cleavage effect of the radicals becoming too high, resulting in a significant decrease in molecular weight and thus adversely affecting physical properties and adhesiveness, the amount is preferably 10 parts by mass or less, and more preferably 7 parts by mass or less. Also, from the viewpoint of realizing appropriate reactivity and good graft modification, the amount is preferably 0.001 parts by mass or more, and more preferably 0.005 parts by mass or more.

After the above modification reaction, a process may be carried out to remove unreacted unsaturated carboxylic acid components. The method for this process is not particularly limited, but an example is a process in which the modified propylene-ethylene copolymer after the modification reaction is placed in a storage tank that has a structure that allows gas to be blown in from the bottom of the device, the device is heated to about 100°C using a heater or thermal oil, and an inert gas such as nitrogen or air is blown in from the bottom of the device for 6 to 24 hours.

In the present embodiment, the amount of modification (graft ratio) by the unsaturated carboxylic acid component in the modified propylene-ethylene copolymer of component (C) is preferably 0.5% by mass or more, more preferably 0.5 to 2.0% by mass, and even more preferably 0.7 to 1.5% by mass. From the viewpoint of obtaining sufficient adhesiveness in the adhesive polymer composition according to the present embodiment, the amount of modification is preferably 0.5% by mass or more, and more preferably 0.7% by mass or more. Furthermore, from the viewpoint of obtaining good thermal stability and adhesiveness in the adhesive polymer composition, as well as good compatibility with other components, the amount of modification is preferably 2.0% by mass or less, and more preferably 1.5% by mass or less.

In this specification, the modification amount (graft ratio) means the content of unsaturated carboxylic acid and its derivatives grafted to the raw material polypropylene, i.e., the propylene-ethylene copolymer before modification, which is obtained by measurement using an infrared spectrometer.
Specifically, the modified propylene-ethylene copolymer (C) is press-molded into a sheet having a thickness of about 100 μm, and the absorption characteristic of the unsaturated carboxylic acid component in the sample is measured. The absorption characteristic of the unsaturated carboxylic acid component can be the carbonyl characteristic absorption at 1,900 to 1,600 cm ^-1 (C═O stretching vibration band).
The graft ratio can also be determined from a calibration curve prepared in advance by the above method.

In addition, in the case of modification with an unsaturated carboxylic acid component, not all of the added unsaturated carboxylic acid component is subjected to the reaction, and the unsaturated carboxylic acid component that has not reacted with the raw material polypropylene may remain in the modified propylene-ethylene random copolymer. However, the above modification amount (graft ratio) in this specification means the value measured by the above method.

<Content of Components (A) to (C)>
The adhesive polymer composition according to this embodiment contains the above-mentioned components (A) to (C) as essential components.

The content of component (A) relative to the total of components (A) and (B) is preferably 51 to 75 mass%, more preferably 51 to 70 mass%, even more preferably 51 to 65 mass%, even more preferably 52 to 65 mass%, and particularly preferably 53 to 65 mass%. That is, the content of component (B) relative to the total of components (A) and (B) is preferably 25 to 49 mass%, more preferably 30 to 48 mass%, and even more preferably 35 to 47 mass%.
From the viewpoints of maintaining heat resistance and rigidity and ensuring adhesion when bonding to a base layer made of a propylene-based polymer, the content of the component (A) is preferably 51 mass% or more, more preferably 52 mass% or more, and even more preferably 53 mass% or more, and the content of the component (B) is preferably 49 mass%, more preferably 48 mass% or less, and even more preferably 47 mass% or less.
From the viewpoint of ensuring adhesion when bonding to a base layer or a gas barrier layer made of an ethylene-based polymer, the content of the component (A) is preferably 75% by mass or less, more preferably 70% by mass or less, and even more preferably 65% by mass or less, and the content of the component (B) is preferably 25% by mass or more, more preferably 30% by mass or more, and even more preferably 35% by mass or more.

The content of component (C) relative to 100 parts by mass of the total of components (A) and (B) is preferably 0.5 to 15 parts by mass, and more preferably 2 to 12 parts by mass. From the viewpoint of obtaining sufficient adhesion, the content is preferably 0.5 parts by mass or more, and more preferably 2 parts by mass or more. Also, from the viewpoints of processability, prevention of the occurrence of burns and resin, prevention of moisture absorption, and handling, the content is preferably 15 parts by mass or less, and more preferably 12 parts by mass or less.

As the content ratio of components (A) to (C), for example, it is more preferable that the content of component (A) is 51 to 75 mass% and the content of component (B) is 25 to 49 mass% relative to the total of components (A) and (B), and that the content of component (C) is 0.5 to 15 mass parts relative to 100 mass parts of the total of components (A) and (B). Further preferred aspects of the above contents of components (A) and (B) and the content of component (C) are the same as the preferred aspects of the content or content of each component.

The total content of components (A) to (C) in the adhesive polymer composition according to this embodiment is preferably 70 to 100% by mass, more preferably 75 to 100% by mass, and even more preferably 80 to 100% by mass. From the viewpoint of effectively obtaining the effects of including components (A) to (C), the total content is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more. There is no particular upper limit, and the upper limit may be 100% by mass or less, that is, the adhesive polymer composition according to this embodiment may consist only of components (A) to (C).

Other Ingredients
In addition to the above components (A) to (C), the adhesive polymer composition according to this embodiment may contain other optional additives, resins, etc. (hereinafter, may be referred to as "other components") according to various purposes, within a range that does not significantly impair the effects of the present invention. However, since tackifiers may cause smoke generation during molding, leaching into oil, and reduced heat resistance, it is preferable that the adhesive polymer composition according to this embodiment does not contain a tackifier. This means that the content of the tackifier in the adhesive polymer composition is 5 mass% or less.
The other components may be contained alone or in any combination and ratio of two or more kinds.

Among the other components, additives can be auxiliary additives generally used in polyolefins. Specific examples include process oils, neutralizing agents, processing aids, plasticizers, crystal nucleating agents, impact modifiers, flame retardants, flame retardant assistants, crosslinking agents, crosslinking assistants, antistatic agents, lubricants, fillers, compatibilizers, heat stabilizers, weather stabilizers (antioxidants, light stabilizers, UV absorbers, etc.), anti-fog agents, slip agents, anti-blocking agents, antibacterial agents, carbon black, colorants (pigments, dyes, etc.), etc.

Among the additives, flame retardants are roughly classified into halogen-based flame retardants and non-halogen-based flame retardants, with the non-halogen-based flame retardants being preferred.
Specific examples of non-halogen flame retardants include metal hydroxides, phosphorus-based flame retardants, nitrogen-containing compound (melamine-based, guanidine-based) flame retardants, and inorganic compound (borate, molybdenum compound) flame retardants.

Additives such as heat stabilizers and antioxidants include, for example, hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, and alkali metal halides.

Among additives, fillers are broadly classified into organic fillers and inorganic fillers.
Examples of organic fillers include naturally occurring polymers such as starch, cellulose fine particles, wood flour, soybean pulp, rice husks, and bran, as well as modified products of these.
Examples of inorganic fillers include talc, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, glass balloons, carbon black, zinc oxide, antimony trioxide, zeolite, metal fibers, metal whiskers, ceramic whiskers, potassium titanate, boron nitride, graphite, and carbon fibers.

When these additives are used, the total content of them in the adhesive polymer composition according to the present embodiment is preferably 0.01 to 5 mass%, more preferably 0.1 to 2 mass%, and the total content is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, and is preferably 5 mass% or less, more preferably 2 mass% or less.
When the adhesive polymer composition according to the present embodiment is used as a master batch, the content of the above additives can be 2 to 50 times, preferably 3 to 30 times, the above range.

Among the other components, specific examples of resins include polyphenylene ether resins; polycarbonate resins; polyamide resins such as nylon 66 and nylon 11; polyester resins such as polyethylene terephthalate and polybutylene terephthalate, styrene resins such as polystyrene, and acrylic/methacrylic resins such as polymethyl methacrylate resins. These may be used alone or in combination of two or more.

When the adhesive polymer composition according to this embodiment contains these resins, the total content per 100 parts by mass of the total of component (A) and component (B) is preferably 10 parts by mass or less.

<<Method for producing adhesive polymer composition>>
The adhesive polymer composition according to this embodiment is obtained by blending components (A) to (C) with other components that are added as necessary.
The compounding method is not particularly limited, but examples thereof include a melting method, a solution method, a suspension dispersion method, etc., and from a practical standpoint, the melting method is preferred, and the melt kneading method is more preferred.

In the melt kneading, for example, powdery or granular components (A) to (C) and other components added as necessary are uniformly mixed in a predetermined blending ratio and kneaded.
The order in which the components are mixed and kneaded is not particularly limited, and may be, for example, a method in which components (A) to (C) and other components used as needed are mixed together and kneaded, or a method in which components (A) to (C) and a portion of other components used as needed are mixed in advance, and then the remaining components are mixed together and kneaded.

For mixing, for example, a Henschel mixer, a ribbon blender, a V-type blender, or the like can be used.
The kneading can be carried out using a common kneading machine such as a Banbury mixer, a kneader, a roll, or a multi-screw kneading extruder such as a single-screw or twin-screw kneading extruder.

The melt-kneading temperature is usually 100°C to 300°C, preferably 120°C to 280°C, and more preferably 150°C to 250°C. Here, the above temperature is preferably 100°C or higher, more preferably 120°C or higher, and even more preferably 150°C or higher, and is preferably 300°C or lower, more preferably 280°C or lower, and even more preferably 250°C or lower.

Properties of Adhesive Polymer Composition
・MFR
The adhesive polymer composition according to the present embodiment preferably has a melt flow rate (MFR) of 0.2 to 10 g/10 min, more preferably 0.5 to 5 g/10 min. Here, from the viewpoint of easily maintaining a good viscosity balance with other resins when the adhesive polymer composition is co-extruded as an adhesive layer and suppressing the variation in thickness of each layer constituting the obtained laminate, the MFR is preferably 0.2 g/10 min or more, more preferably 0.5 g/10 min or more, and is preferably 10 g/10 min or less, more preferably 5 g/10 min or less.
Furthermore, when the adhesive polymer composition according to the present embodiment is used as an adhesive layer, particularly in extrusion molding for forming a laminate such as a sheet, a pipe, a tube, or a coolant tube, the MFR is particularly preferably 0.5 to 3 g/10 min. That is, it is more preferably 0.5 g/10 min or more, and particularly preferably 3 g/10 min or less.
In this specification, the melt flow rate (MFR) of the adhesive polymer composition is a value measured in accordance with JIS K 7210:2014 under conditions of a temperature of 230°C, a load of 21.2 N, and a time of 10 minutes.

<Laminate>
The laminate according to this embodiment includes an adhesive layer made of an adhesive polymer composition. The adhesive polymer composition here can be one described in the above "Adhesive polymer composition", and the preferred embodiments are the same. The adhesive layer has excellent heat resistance and strength, so that a laminate having good adhesion to other layers constituting the laminate and excellent heat resistance can be obtained.

The laminate according to this embodiment preferably includes a configuration in which the adhesive layer and the gas barrier layer are laminated, and it is more preferable that the adhesive layer and the gas barrier layer are in direct contact with each other.
The laminate according to the present embodiment also preferably includes a configuration in which the adhesive layer and the polyolefin-based polymer layer are laminated, and it is more preferable that the adhesive layer and the polyolefin-based polymer layer are in direct contact with each other.
Furthermore, the laminate according to the present embodiment preferably includes a configuration in which a gas barrier layer, the adhesive layer, and a polyolefin-based polymer layer are laminated in this order, and it is more preferable that at least one of the adhesive layer and the gas barrier layer and the adhesive layer and the polyolefin-based polymer layer is in direct contact with each other, and it is even more preferable that both are in direct contact with each other. That is, it is even more preferable that the gas barrier layer is in direct contact with one main surface of the adhesive layer, and the polyolefin-based polymer layer is in direct contact with the other main surface of the adhesive layer.
The polyolefin polymer layer will be described later, and is a layer made of a polyolefin polymer, preferably a layer made of a propylene polymer, ethylene polymer, or the like.

One embodiment of the laminate according to the present embodiment is a five-layer laminate in which polyolefin-based polymer layers are laminated on both sides of a gas barrier layer via adhesive layers made of an adhesive polymer composition, which means a layer structure of "polyolefin-based polymer layer/adhesive layer made of adhesive polymer composition/gas barrier layer/adhesive layer made of adhesive polymer composition/polyolefin-based polymer layer."
Here, the two polyolefin-based polymer layers may be the same or different, and the two adhesive layers made of adhesive polymer compositions may also be the same or different.

At least one of the two polyolefin-based polymer layers is preferably a propylene-based polymer layer, and more preferably both of the two polyolefin-based polymer layers are propylene-based polymer layers. At least one of the two polyolefin-based polymer layers may be an ethylene-based polymer layer, and both of the two polyolefin-based polymer layers may be ethylene-based polymer layers.

One aspect of the laminate according to this embodiment may be an asymmetric laminate structure. Specific examples include a laminate having multiple gas barrier layers, and a laminate having a gas barrier layer on at least one of the inner and outer layers.

The total thickness of the laminate according to this embodiment is not particularly limited and is appropriately determined depending on the application, the type of adherend layer, and the like. The thickness is preferably 200 to 5000 μm, for example, or may be 500 to 5000 μm, or may be 30 to 200 μm. When the laminate is a coolant tube, the thickness is preferably 500 to 5000 μm. Furthermore, when the laminate is a sheet, the thickness is preferably 30 to 200 μm.

The adhesive strength of the laminate according to this embodiment can be evaluated by a T-peel test. Specifically, as shown in the Examples section below, a test piece cut to a predetermined width (5 mm width in the Examples below) is used, and the interface whose strength is to be measured is peeled off with a cutter or the like, and the peel strength is measured by peeling it off at a predetermined speed (50 mm/min in the Examples below) at 23°C using a general tensile tester in the T-peel method, and this peel strength is taken as the adhesive strength of the laminate. The interface to be measured refers to the interface between the adhesive layer and the layer with the smallest peel strength from the polyolefin polymer layer or gas barrier layer.

Although it depends on the application, the adhesive strength of the laminate measured by the above T-peel peel test is preferably 0.15 N/mm or more, and more preferably 0.25 N/mm or more.

The laminate according to this embodiment can maintain good adhesive strength even after being heated. As an indicator of this, if the rate of decrease in adhesive strength measured after subjecting the laminate to heat treatment at 100°C for 2000 hours compared to the adhesive strength before heat treatment is 30% or less, it can be judged to have excellent heat resistance, and it is preferable that the rate of decrease is 15% or less, and the smaller the rate, the more preferable.

<Adhesive layer>
As described above, the adhesive layer in the laminate according to this embodiment can be a layer made of the composition described in the above <Adhesive polymer composition>.
The thickness of the adhesive layer is not particularly limited and is appropriately determined depending on the application, the type of the adherend layer, etc. The thickness is, for example, preferably 1 to 500 μm, more preferably 2 to 300 μm, even more preferably 3 to 200 μm, and may be 10 to 500 μm. Here, the thickness is preferably 1 μm or more, more preferably 2 μm or more, even more preferably 3 μm or more, and may be 10 μm or more. The thickness is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less.
Furthermore, although details will be described later, when the laminate according to this embodiment is a coolant tube, the thickness of the adhesive layer is preferably 10 to 500 μm.

Gas barrier layer
The gas barrier layer in the laminate according to this embodiment is a layer that has low permeability to gases such as oxygen, nitrogen, carbon dioxide, etc. For the gas barrier layer, a conventionally known polymer having a barrier property can be used.
Examples of polymers having barrier properties include polyamide, ethylene-vinyl alcohol copolymer, polyphthalamide, etc. The gas barrier layer can impart mechanical strength, heat resistance, and other resistance properties to the laminate in addition to gas barrier properties. From this viewpoint, the gas barrier layer is preferably a layer containing polyamide.

Ethylene-vinyl alcohol copolymer, which is a polymer having barrier properties, is usually obtained by saponifying ethylene-vinyl acetate copolymer.
The saponification degree of the ethylene-vinyl alcohol copolymer in this embodiment is preferably 95% or more, more preferably 95 to 100%. From the viewpoint of maintaining good gas permeability resistance, the saponification degree is preferably 95% or more, and the upper limit is not particularly limited and may be 100%.

In this embodiment, the ethylene unit content in the ethylene-vinyl alcohol copolymer is preferably 20 to 50 mol %. From the viewpoints of maintaining good gas permeability resistance, suppressing thermal decomposition, and facilitating melt molding, as well as from the viewpoints of stretchability and water resistance, the ethylene unit content is preferably 20 mol % or more, and 50 mol % or less.

In this embodiment, the ethylene-vinyl alcohol copolymer preferably has a degree of saponification of 95% or more, and the content of ethylene units in the copolymer is preferably 20 to 50 mol%.

Examples of polyamides, which are polymers having barrier properties, include polymers of lactams such as ε-caprolactam and ω-laurolactam; polymers of aminocarboxylic acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid; polycondensates of diamines such as aliphatic diamines such as hexamethylenediamine, decamethylenediamine, dodecamethylenediamine, and 2,2,4- or 2,4,4-trimethylhexamethylenediamine; alicyclic diamines such as 1,3- or 1,4-bis(aminomethyl)cyclohexane and bis(p-aminocyclohexylmethane); and aromatic diamines such as m- or p-xylylenediamine, and polycondensates of dicarboxylic acids such as aliphatic dicarboxylic acids such as adipic acid, suberic acid, and sebacic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, and copolymers thereof.
More specifically, examples of the polyamide include polyamide 6, polyamide 9, polyamide 9T, polyamide 11, polyamide 12, polyamide 66, polyamide 610, polyamide 611, polyamide 612, polyamide 6T, polyamide 6I, and polyamide MXD6. Of these, polyamide 6, polyamide 11, polyamide 12, and polyamide MXD6 are preferred.

The thickness of the gas barrier layer is not particularly limited, and is appropriately determined depending on the application, the type of resin, the required characteristics, and the like. The thickness is, for example, preferably 2 to 3000 μm, more preferably 2 to 1000 μm, even more preferably 2 to 700 μm, even more preferably 3 to 600 μm, and may be 100 to 3000 μm. Here, the thickness is preferably 2 μm or more, more preferably 3 μm or more, and may be 100 μm or more. The thickness is preferably 3000 μm or less, preferably 1000 μm or less, more preferably 700 μm or less, and even more preferably 600 μm or less.
Furthermore, although details will be described later, when the laminate according to this embodiment is a coolant tube, the thickness of the gas barrier layer is preferably 100 to 3000 μm.

The gas barrier layer in this embodiment may contain the adhesive polymer composition in this embodiment or its constituent components, and may also contain other components that may be contained in the adhesive polymer composition, to the extent that the purpose of the gas barrier layer is not impaired.

<Polyolefin-based polymer layer>
The polyolefin-based polymer layer in the laminate according to the present embodiment is a layer made of a polyolefin-based polymer. Examples of the polyolefin-based polymer layer include a propylene-based polymer layer and an ethylene-based polymer layer.

Propylene-Based Polymer Layer When the polyolefin-based polymer layer in the present embodiment is a propylene-based polymer layer, the propylene-based polymer constituting the layer preferably has a propylene unit content of 50 mol % or more.
Examples of such propylene-based polymers include propylene homopolymers, propylene-ethylene random copolymers, propylene-butene random copolymers, propylene-ethylene-hexene random copolymers, propylene-ethylene-octene random copolymers, propylene-butene-hexene random copolymers, propylene-butene-octene random copolymers, propylene-hexene-octene random copolymers, and propylene-ethylene block copolymers.

Among the above, propylene homopolymers, propylene-ethylene random copolymers, propylene-butene random copolymers, propylene-ethylene-hexene random copolymers, propylene-ethylene-octene random copolymers, propylene-butene-hexene random copolymers, and propylene-butene-octene random copolymers having a melt flow rate (MFR) of 0.1 to 30 g/10 min are more preferred, and propylene homopolymers, propylene-ethylene random copolymers, and propylene-butene random copolymers having an MFR of 0.1 to 30 g/10 min are particularly preferred.
In this specification, the melt flow rate (MFR) of the propylene-based polymer is a value measured in accordance with JIS K 7210:2014 under conditions of a temperature of 230° C., a load of 21.2 N, and a time of 10 minutes.

The thickness of the propylene-based polymer layer is not particularly limited and is appropriately determined depending on the application, the type of resin, the required characteristics, and the like. The thickness is, for example, preferably 20 to 5000 μm, more preferably 30 to 4000 μm, and may be 100 to 1100 μm. Here, the thickness is preferably 20 μm or more, more preferably 30 μm or more, and may be 100 μm or more. The thickness is preferably 5000 μm or less, more preferably 4000 μm or less, and may be 1100 μm or less.
Furthermore, although details will be described later, when the laminate according to this embodiment is a coolant tube, the thickness of the propylene-based polymer layer is preferably 100 to 1100 μm.

Ethylene-Based Polymer Layer When the polyolefin-based polymer layer in this embodiment is an ethylene-based polymer layer, the ethylene-based polymer constituting it preferably has an ethylene unit content of 50 mol % or more.
Examples of such ethylene polymers include linear low density polyethylene, high density polyethylene, ultra-high molecular weight polyethylene, high pressure low density polyethylene, medium density polyethylene, and ethylene elastomers.

Among the above, low-density polyethylene or high-density polyethylene having a melt flow rate (MFR) of 0.1 to 30 g/10 min is particularly preferred.
In this specification, the melt flow rate (MFR) of the ethylene polymer is a value measured in accordance with JIS K 7210:2014 under conditions of a temperature of 190°C, a load of 21.2 N, and a time of 10 minutes.

The thickness of the ethylene-based polymer layer is not particularly limited and is appropriately determined depending on the application, the type of resin, the required properties, and the like. The thickness is, for example, preferably 20 to 5000 μm, more preferably 30 to 4000 μm, and may be 100 to 1100 μm. Here, the thickness is preferably 20 μm or more, more preferably 30 μm or more, and may be 100 μm or more. The thickness is preferably 5000 μm or less, more preferably 4000 μm or less, and may be 1100 μm or less.
Although details will be described later, when the laminate according to this embodiment is a coolant tube, the thickness of the ethylene-based polymer layer is preferably 100 to 1100 μm.

The polyolefin polymer layer in this embodiment may contain the adhesive polymer composition in this embodiment or its constituent components, and may also contain other components that may be contained in the adhesive polymer composition, to the extent that the purpose of the layer is not impaired.

Other Layers
The laminate according to this embodiment may further include other layers in addition to the polyolefin polymer layer, adhesive layer, and gas barrier layer.
The other layers are not particularly limited, and examples thereof include resin layers made of styrene-based resins such as polycarbonate resins, polystyrene (GPPS), high impact polystyrene (HIPS), and styrene-acrylonitrile graft copolymers (ABS resins), and other thermoplastic resin layers such as olefin-based polymers other than propylene-based resins and polyethylene-based resins, cyclic polyolefin-based resins, polyphenylene ether-based resins, polyoxymethylene-based resins such as polyoxymethylene homopolymers and polyoxymethylene copolymers, and acrylic/methacrylic resins such as polymethyl methacrylate-based resins.

<<Method for manufacturing laminate>>
The method for producing the laminate according to the present embodiment (hereinafter, sometimes referred to as "primary processing") can employ various conventionally known methods. For example, there can be mentioned blow molding using a co-extrusion method in which individual molten resins melted in an extruder are supplied to a multi-layer die and laminated in the die, pipe extrusion molding, tube extrusion molding, film molding using a T-die molding, and sheet molding.

Hereinafter, the method will be described in detail using the sheet coextrusion method as an example.
The polymers or compositions constituting each of the above layers are prepared in advance by melt kneading or dry blending. Then, they are extruded by a single-screw or twin-screw extrusion method, and merged in a feed block or multi-manifold die to form a laminate structure. Then, they are extruded from a die of a predetermined shape, cooled, and wound up by a winder if they are in a sheet shape.

The extrusion temperature in the co-extrusion method is appropriately selected depending on the properties of the resins in each layer constituting the laminate, but it is generally preferable to keep the temperature at 300° C. or less.
The sheet take-up speed (m/h) may be appropriately set depending on the desired sheet thickness.
The extrusion rate (g/h) of the base material of the extruder may be appropriately selected depending on the type of the material used, the thickness of each layer of the desired sheet, and the like.
The cooling method can be a conventional method, for example, a method of cooling by casting onto a roll, a method of cooling with an air knife, a method of cooling in water through a sizer, etc.

<<Applications of the laminate>>
In the laminate according to the present embodiment, when the gas barrier layer or the polyolefin polymer layer is laminated with the adhesive layer, the laminate is made of thermoplastic resins, and therefore the laminate has excellent secondary processability such as thermoforming. Therefore, the laminate can be subjected to secondary processing such as stretching and thermoforming.
The laminate according to the present embodiment can be subjected to secondary processing and processed into various shapes depending on the application. The laminate according to the present embodiment is preferably formed into, for example, a hollow molded product or a sheet. The hollow molded product is preferably a tube, and the tube may be a coolant tube.

The adhesive polymer composition constituting the adhesive layer in the laminate according to the present embodiment has excellent adhesion to the gas barrier polymer layer, and is also excellent in heat resistance and rigidity, so that the laminate according to the present embodiment exhibits excellent adhesive strength characteristics, and further has excellent strength, heat resistance, gas barrier properties, etc.
Therefore, the laminate according to the present embodiment can be suitably used for general food packaging, storage containers for medicines, etc., fuel parts such as fuel tanks, fuel tubes, and coolant tubes, and is particularly preferably used for fuel parts. Note that the laminate according to the present embodiment can be processed into any shape in addition to the above-mentioned hollow molded product or sheet depending on the application.

Coolant Tube A case in which the laminate according to the present embodiment is a coolant tube will be described with reference to FIG. 1, however, the coolant tube according to the present embodiment is not limited to this.

1 is a schematic cross-sectional view showing the configuration of a coolant tube, which has a laminated structure in which a gas barrier layer 1, an adhesive layer 2, and a polyolefin-based polymer layer 3 are laminated in this order from the outer layer side.
As described above, the gas barrier layer 1 is preferably a layer containing polyamide from the viewpoint of imparting durability such as mechanical strength and heat resistance in addition to imparting gas barrier properties. The adhesive layer 2 is preferably a layer made of the adhesive polymer composition in this embodiment, and the polyolefin-based polymer layer 3 is preferably a polyolefin-based polymer layer. More preferred aspects of each layer are as described above, but the polyolefin-based polymer layer that becomes the polymer layer 3 is more preferably a propylene-based polymer layer from the viewpoint of imparting flexibility, heat resistance, and mechanical strength to the coolant tube that is the laminate.

Although FIG. 1 shows a three-layer coolant tube, it may have four or more layers, and when it has five layers, it may have the layer structure of "polyolefin-based polymer layer/adhesive layer made of adhesive polymer composition/gas barrier layer/adhesive layer made of adhesive polymer composition/polyolefin-based polymer layer" as described above.
In addition, an asymmetric laminate structure may be used, in which a plurality of gas barrier layers are arranged, or a gas barrier layer may be arranged on at least one of the inner layer and the outer layer.

When the polyolefin-based polymer layer of the coolant tube in this embodiment is a polyolefin-based polymer layer, the Duro D hardness of the polyolefin-based polymer layer is preferably 25 to 70, more preferably 25 to 65. From the viewpoint of mechanical strength, the Duro D hardness is preferably 25 or more. Moreover, from the viewpoint of imparting flexibility, the Duro D hardness is preferably 70 or less, more preferably 65 or less.
In this specification, the Duro D hardness of the polyolefin polymer layer is a value measured based on JIS K 6253:2006.

In this embodiment, the total thickness of the laminate constituting the coolant tube is preferably 0.5 to 5 mm, and more preferably 0.6 to 4 mm. From the viewpoint of mechanical strength, the total thickness is preferably 0.5 mm or more, and more preferably 0.6 mm or more. From the viewpoint of tube shaping, the total thickness is preferably 5 mm or less, and more preferably 4 mm or less.

In this embodiment, the thickness of the gas barrier layer constituting the coolant tube is preferably 0.1 to 3.0 mm, and more preferably 0.2 to 2 mm. From the viewpoint of mechanical strength, the thickness of the gas barrier layer is preferably 0.1 mm or more, and more preferably 0.2 mm or more. From the viewpoint of tube shaping, the thickness of the gas barrier layer is preferably 1.0 mm or less, and more preferably 3.0 mm or less.

In this embodiment, the thickness of the adhesive layer constituting the coolant tube is preferably 0.01 to 0.5 mm, and more preferably 0.05 to 0.4 mm. From the viewpoint of adhesion, the thickness of the adhesive layer is preferably 0.01 mm or more, and more preferably 0.05 mm or more. From the viewpoint of flexibility, the thickness of the adhesive layer is preferably 0.5 mm or less, and more preferably 0.4 mm or less.

In this embodiment, the thickness of the polyolefin-based polymer layer constituting the coolant tube is preferably 0.1 to 1.1 mm, and more preferably 0.15 to 1.0 mm. From the viewpoint of coolant resistance, the thickness of the polyolefin-based polymer layer is preferably 0.1 mm or more, and more preferably 0.15 mm or more. From the viewpoint of tube shaping, the thickness of the polyolefin-based polymer layer is preferably 1.1 mm or less, and more preferably 1.0 mm or less.

In this embodiment, it is preferable that the layers constituting the coolant tube have a gas barrier layer thickness of 0.1 to 3.0 mm, an adhesive layer thickness of 0.01 to 0.5 mm, and a polyolefin polymer layer thickness of 0.1 to 1.1 mm.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not deviate from the gist of the invention. Note that the various manufacturing conditions and evaluation result values in the following examples are meant as preferred upper or lower limit values in the embodiments of the present invention, and the preferred range may be a range defined by a combination of the above-mentioned upper or lower limit values and the values of the following examples or values between the examples.

[raw materials]
In the following examples, the following raw materials were used:

<Component (A)>
A-1: Propylene-based polymer, propylene homopolymer MFR (230°C, load 21.2N): 0.8g/10min, flexural modulus: 1260MPa
A-2: Propylene-based polymer, propylene homopolymer, MFR (230°C, load 21.2N): 0.8g/10min, flexural modulus: 1300MPa

<Component (B)>
B-1: High density polyethylene, ethylene-butene copolymer, MFR (190° C., load 21.2 N): 0.3 g/10 min, density: 0.954 g/cm ³ , Mw/Mn: 17.4, butene unit content: 0.3 mol %
B-2: High density polyethylene, ethylene-butene copolymer, MFR (190° C., load 21.2 N): 0.5 g/10 min, density: 0.954 g/cm ³ , Mw/Mn: 7.2, butene unit content: 0.2 mol %

<Component (C)>
C-1: Modified propylene-ethylene copolymer (production method)
100 parts by mass of propylene-ethylene random copolymer (density: 0.89 g/cm ³ , MFR (230° C., load 21.2 N): 6 g/10 min), 1.5 parts by mass of maleic anhydride (manufactured by Wako Pure Chemical Industries, Ltd.), and 0.3 parts by mass of organic peroxide (manufactured by NOF Corp., Perhexa 25B) were dry blended and mixed. The resulting mixture was then melt-kneaded and pelletized using a twin-screw extruder (D=30 mmφ, L/D=32, manufactured by Nippon Steel Corporation, TEX30) at a temperature of 240° C., a screw rotation speed of 300 rpm, and an extrusion rate of 10 kg/h. This resulted in a propylene-ethylene random copolymer C-1 modified with maleic anhydride having a modification amount of 0.9% by mass.

C'-1: Modified propylene homopolymer (production method)
5 kg of powder of propylene homopolymer (density: 0.90 g/cm ³ , MFR (230° C., load 21.2 N): 10 g/10 min) and 500 g of maleic anhydride were dissolved in 6 L of chlorobenzene at 130° C. Next, a chlorobenzene solution of dicumyl peroxide (200 g/400 L) was added to this solution. The reaction was continued for another 8 hours at 130° C., and then cooled to 40° C. to precipitate a resin. The precipitated resin was filtered, washed repeatedly with acetone, and dried under reduced pressure at 90° C. to obtain a propylene homopolymer C'-1 modified with maleic anhydride having a modification amount of 2.2% by mass.

[Example 1-1, Example 1-2, and Comparative Example 1-1]
The components described in the above [Raw Materials] were dry blended and mixed in the amounts shown in Table 1. The resulting mixtures were melt-kneaded using a single-screw extruder (diameter 40 mmφ, L/D=32) at a set temperature of 210° C., a screw rotation speed of 60 rpm, and an extrusion rate of 20 kg/h, and pellet-shaped adhesive polymer compositions were obtained by strand cutting.
The MFR (230° C., load 21.2 N) of the obtained adhesive polymer composition was as shown in Table 1. In addition, in the "Adhesive polymer composition (parts by mass)" in Table 1, the component marked with "-" means that the component was not added.

[Example 2-1, Example 2-2, and Comparative Example 2-1]
Laminates each having an adhesive layer made of the adhesive polymer composition of Example 1-1, Example 1-2, and Comparative Example 1-1 were obtained by the following procedure.
The polyolefin polymer layer was a propylene polymer layer, which was a polyolefin polymer layer, and was made of polypropylene "Novatec PP EG7F" (MFR (230°C, load 21.2N): 1.3g/10min) manufactured by Japan Polypropylene Corporation.
The gas barrier layer was made of polyamide 12 (nylon 12) (Grilamid L25W20X, manufactured by EMS).
For the adhesive layer, as described above, the adhesive polymer compositions of Example 1-1, Example 1-2 and Comparative Example 1-1 were used, respectively.

First, a 3-kind, 5-layer bottle (volume: 500 mL, thickness: about 3.5 mm) was obtained using a multi-layer blow molding machine. The extruders for each layer in the multi-layer blow molding machine were 65 mmφ for the propylene-based polymer layer, 40 mmφ for the gas barrier layer, and 40 mmφ for the adhesive layer, and a 200 mm diameter round die (lip opening: 5 mm) was used.
The three-kind, five-layer structure was polyolefin polymer layer/adhesive layer/gas barrier layer/adhesive layer/polyolefin polymer layer, and the thicknesses of each layer were 1.5/0.1/0.1/0.1/1.5 (mm) in that order.
The molding temperatures were 220°C for the gas barrier layer, 230°C for the adhesive layer, 220°C for the polyolefin polymer layer, and 220°C for the die temperature. The extrusion rate was about 30 kg/h, the bottle cooling time was 2 minutes, and the die temperature was 15°C.

[Evaluation: Adhesive strength]
The laminates obtained above were each cut into a 7 mm-wide strip in the extrusion direction to prepare test pieces. The test pieces were subjected to a T-peel test at a speed of 50 mm/min in an atmosphere of 23° C. to measure the peel strength, and the measured value was regarded as the adhesive strength of the laminate.
The results are shown in Table 1 under "Adhesive strength (before heat resistance test)". If the strength is 0.15 N/mm or more, the adhesive strength can be evaluated as excellent, and if it is 0.25 N/mm or more, the adhesive strength can be evaluated as very excellent.

[Evaluation: Heat resistance]
Test pieces were cut out in the same manner as in the above [Evaluation: Adhesive strength], and were then placed in a precision oven and subjected to a heat treatment for 2000 hours at 100° C. After the heat treatment, a T-peel test was performed on the test pieces in an atmosphere of 23° C. at a speed of 50 mm/min to measure the peel strength, and the value was taken as the adhesive strength of the laminate.
The results are shown in Table 1 under "Adhesive strength (after heat resistance test)". With regard to this strength, if the rate of decrease in adhesive strength after heat treatment relative to the adhesive strength before heat treatment is 30% or less, the strength can be evaluated as having excellent heat resistance, and if the rate of decrease is 15% or less, the strength can be evaluated as having very excellent heat resistance.

The results in Table 1 show that the adhesive layer in Comparative Example 2-1, which used a modified propylene homocopolymer as component (C), had an adhesive strength after heating that was reduced to nearly half of the adhesive strength before heating, resulting in issues with heat resistance.

In contrast, when the adhesive polymer composition according to the present embodiment, which uses a modified propylene-ethylene copolymer as component (C), is used as an adhesive layer, it has excellent adhesive strength and can maintain good adhesive strength even after heating, and it has been found to have excellent heat resistance.

For component (B), B-1 was used in the examples and B-2 in the comparative examples, but B-1 and B-2 are both high-density polyethylenes with almost the same MFR, density, butene unit content, etc. If these physical property values are similar, it can be said that they have similar molecular weights and similar polymer structures, so even if B-2 is used as component (B) in the examples or B-1 is used as component (B) in the comparative examples, it can be said that the evaluation results of adhesive strength and heat resistance do not change significantly.

1 Gas barrier layer 2 Adhesive layer 3 Polyolefin polymer layer

Claims (16)

An adhesive polymer composition comprising the following components (A) to (C):
Component (A): A propylene-based polymer; Component (B): An ethylene-based polymer having a density of 0.94 g/ ^cm3 or more and 0.97 g/ ^cm3 or less; Component (C): A propylene-ethylene copolymer modified with at least one selected from the group consisting of unsaturated carboxylic acids and derivatives thereof. The adhesive polymer composition according to claim 1, wherein the component (C) is a propylene-ethylene copolymer modified with at least one of maleic acid and maleic anhydride. The component (A) has a melt flow rate of 0.1 to 50 g/10 min, measured in accordance with JIS K 7210:2014 at a temperature of 230° C. and a load of 21.2 N; and
The adhesive polymer composition according to claim 1, wherein the component (B) has a melt flow rate of 0.1 to 20 g/10 min, as measured at a temperature of 190° C. and a load of 21.2 N according to JIS K 7210:2014. The adhesive polymer composition according to claim 1, wherein the amount of modification in component (C) is 0.5% by mass or more. The adhesive polymer composition according to claim 1, wherein the propylene-ethylene copolymer in component (C) is a random copolymer or a block copolymer. The adhesive polymer composition according to claim 1, wherein the content of component (A) relative to the total of component (A) and component (B) is 51 to 75 mass%. The adhesive polymer composition according to claim 6, wherein the content of component (A) is 51 to 65 mass%. The adhesive polymer composition according to claim 1, wherein the content of component (C) is 0.5 to 15 parts by mass per 100 parts by mass of the total of components (A) and (B). A laminate comprising an adhesive layer made of the adhesive polymer composition according to any one of claims 1 to 8 and a gas barrier layer. The laminate according to claim 9, wherein the gas barrier layer is a layer containing polyamide. The laminate according to claim 9, which is a hollow molded product. The laminate according to claim 11, wherein the hollow molded article is a tube. the tube is a coolant tube,
The laminate according to claim 12 , comprising a configuration in which the gas barrier layer, the adhesive layer, and the polyolefin-based polymer layer are laminated in this order. The laminate according to claim 13, wherein the polyolefin polymer layer has a Duro D hardness of 25 to 70 as measured according to JIS K 6253:2006. The laminate according to claim 9, which is a sheet. The laminate according to claim 9, which is used in a fuel component.

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