WO2025154480A1 - Emulsion adhesive composition, coating film, and bonded object - Google Patents

Abstract

An emulsion adhesive composition comprising an acid-modified polyolefin resin, an alcohol-soluble nylon resin, and an alcohol solvent, wherein the mass ratio of the acid-modified polyolefin resin to the alcohol-soluble nylon resin (acid-modified polyolefin resin)/(alcohol-soluble nylon resin) is 90/10 to 30/70 and the acid-modified polyolefin resin is dispersed in the alcohol solvent, and a coating film and a bonded object both obtained from or using the emulsion adhesive composition.

Description

Emulsion adhesive composition, coating film, and adhesive

This disclosure relates to emulsion adhesive compositions, coatings, and adhesives.

A glass sheet for an automobile window is integrated with a resin or rubber member that is interposed between the glass sheet and the vehicle body, seals the gap between the glass sheet and the vehicle body, and also has a decorative function, etc., as necessary. Members having such functions are called by various names such as molding, frame material, gasket, and molding, but in the present disclosure, they are all referred to as molding.
Conventionally, polyvinyl chloride (PVC) has been widely used as a molding material because of its excellent scratch resistance and moldability. However, in recent years, from the viewpoint of environmental protection, the use of thermoplastic elastomers (TPEs), such as thermoplastic polyolefins, has been proposed.

For example, Patent Document 1 describes an adhesive composition used for bonding a thermoplastic elastomer to a glass article, which is characterized by containing a chlorinated polyolefin, an epoxy group-containing compound, and a silane coupling agent.

Patent Document 2 also describes an aqueous dispersion that is characterized by containing an acid-modified polyolefin resin (A), a modified nylon resin (B), and an aqueous medium.

International Publication No. 2004/024843 JP 2009-286918 A

However, TPE has poor surface adhesion and polarity, making it difficult to bond to glass. As a result, adhesive compositions that have traditionally been used have not always been suitable for bonding glass to TPE. To solve this problem, chlorinated resins have been used in adhesive compositions, or two- or three-liquid compositions have been developed, as described in Patent Document 1.

An object of the present disclosure is to provide an emulsion adhesive composition that has excellent adhesion between a thermoplastic elastomer and glass.
Another problem to be solved by the present disclosure is to provide a coating film and an adhesive using the emulsion adhesive composition.

Specific means for solving the above problems include the following aspects.
<1> An emulsion adhesive composition which is a solution containing an acid-modified polyolefin resin, an alcohol-soluble nylon resin, and an alcohol, in which the mass ratio of the acid-modified polyolefin resin to the alcohol-soluble nylon resin (acid-modified polyolefin resin/alcohol-soluble nylon resin) is 90/10 to 30/70, and the acid-modified polyolefin resin is dispersed in an alcohol solvent.
<2> The emulsion adhesive composition according to <1>, wherein the resin solid content is 20 mass% or less.
<3> The emulsion adhesive composition according to <1> or <2>, further comprising water.
<4> The emulsion adhesive composition according to any one of <1> to <3>, further comprising a polymeric multifunctional silane coupling agent having two or more epoxy groups.
<5> The emulsion adhesive composition according to <4>, wherein a mass ratio of the total mass of the resin solid contents of the acid-modified polyolefin resin and the alcohol-soluble nylon resin to the polymer-type multifunctional silane coupling agent having two or more epoxy groups (acid-modified polyolefin resin + solvent-soluble nylon resin / polymer-type multifunctional silane coupling agent having two or more epoxy groups) is 100/0.5 to 100/10.
<6> The emulsion adhesive composition according to any one of <1> to <5>, wherein the acid-modified polyolefin resin is an acid-modified product of at least one resin selected from the group consisting of an ethylene-propylene copolymer, a propylene-butene copolymer, and an ethylene-propylene-butene copolymer.
<7> The emulsion adhesive composition according to any one of <1> to <6>, wherein the acid-modified polyolefin resin is an itaconic anhydride and/or maleic anhydride-modified polyolefin resin.
<8> The emulsion adhesive composition according to any one of <1> to <7>, wherein the melting point of the acid-modified polyolefin resin is 50°C to 135°C.
<9> The emulsion adhesive composition according to any one of <1> to <8>, wherein the alcohol-soluble nylon resin contains 20 mol % or more of piperazine when a total amount of diamine components constituting the alcohol-soluble nylon resin is taken as 100 mol %, and has an amine value of 1 mgKOH/g to 6 mgKOH/g and an acid value of 4 mgKOH/g to 10 mgKOH/g.
<10> The emulsion adhesive composition according to <4> or <5>, wherein the polymer-type polyfunctional silane coupling agent has an alkoxysilyl group and two or more epoxy groups and has a weight average molecular weight of 200 to 10,000.
<11> The emulsion adhesive composition according to any one of <1> to <10>, which is for use in automobile window panes.
<12> A coating film obtained by drying, or by drying and curing, the emulsion adhesive composition according to any one of <1> to <11>.
<13> An adhesive article having an adhesive layer obtained by drying and curing the emulsion adhesive composition according to any one of <1> to <11>.

According to the present disclosure, there is provided an emulsion adhesive composition that has excellent adhesion between a thermoplastic elastomer and glass.
The present disclosure also provides coatings and adhesives using the emulsion adhesive composition.

In the present disclosure, a numerical range expressed using "to" means a range that includes the numerical values before and after "to" as the lower and upper limits.
In the present disclosure, when a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified.
In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In the numerical ranges described in this disclosure, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.
In this disclosure, combinations of preferred aspects are more preferred aspects.
In the description of groups (atomic groups) in the present disclosure, a description without specifying whether substituted or unsubstituted encompasses both groups having no substituents and groups having a substituent.
In the present disclosure, unless otherwise specified, each component may be used alone or in combination of two or more types.

(Emulsion Adhesive Composition)
The emulsion adhesive composition according to the present disclosure (hereinafter also simply referred to as the "adhesive composition according to the present disclosure") contains an acid-modified polyolefin resin, an alcohol-soluble nylon resin, and an alcohol solvent, in which the mass ratio of the acid-modified polyolefin resin to the alcohol-soluble nylon resin (acid-modified polyolefin resin/alcohol-soluble nylon resin) is 90/10 to 30/70, and the acid-modified polyolefin resin is dispersed in the alcohol solvent.

When the target substrates are glass and polyvinyl chloride, conventional adhesive compositions that contain a polyamide resin as the main component and an alcohol solvent have already been used.
However, when the target substrate is glass and TPE, the adhesive composition has good adhesion to glass but does not have sufficient adhesion to TPE.
On the other hand, conventional adhesive compositions whose main components are an acid-modified polypropylene resin and an organic solvent are capable of adhering TPE, but have insufficient adhesion to glass and also have poor storage stability when the components are mixed together, making it necessary to make them into two-part or three-part adhesive compositions.
In view of the above circumstances, the present inventors conducted detailed studies and found that the emulsion adhesive composition according to the present disclosure is prepared by emulsifying an acid-modified polyolefin resin in an alcohol solvent to form an emulsion, and then mixing it with a polyamide, thereby producing a one-component adhesive composition that has excellent adhesion between thermoplastic elastomers and glass.

The emulsion adhesive composition disclosed herein is described in detail below.

<Acid-modified polyolefin resin>
The adhesive composition according to the present disclosure contains an acid-modified polyolefin resin.
Examples of the acid-modified polyolefin resin include polyolefin resins modified with α,β-unsaturated carboxylic acid or a derivative thereof.

The polyolefin resin is not particularly limited, but preferred examples include homopolymers or copolymers of olefins having 2 to 20 carbon atoms, preferably 2 to 6 carbon atoms, such as ethylene, propylene, butene, pentene, hexene, heptene, octene, and 4-methyl-1-pentene.
Among these, from the viewpoint of adhesiveness, the polyolefin resin is preferably a propylene homocopolymer or a propylene copolymer, more preferably at least one selected from the group consisting of an ethylene-propylene copolymer, a propylene-butene copolymer, and an ethylene-propylene-butene copolymer, and particularly preferably a propylene-butene copolymer.
From the viewpoint of adhesiveness, the copolymer preferably contains propylene in an amount of 50 mol % or more and 98 mol % or less based on the total monomers constituting the copolymer.
The acid-modified polyolefin resin may be used alone or in combination of two or more kinds.

Examples of α,β-unsaturated carboxylic acids or derivatives thereof include unsaturated polycarboxylic acids such as maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, aconitic acid, phthalic acid, trimellitic acid, and norbornene dicarboxylic acid, or derivatives thereof (e.g., acid anhydrides, acid halides, amides, imides, esters, etc.). Among these, itaconic anhydride and/or maleic anhydride are preferred in terms of the adhesiveness, handling properties, and cost of the acid-modified polyolefin resin. That is, the acid-modified polyolefin resin is preferably itaconic anhydride and/or maleic anhydride-modified polyolefin resin.
The α,β-unsaturated carboxylic acids and derivatives thereof may be used alone or in combination of two or more kinds.

From the viewpoint of adhesiveness, the graft mass of the α,β-unsaturated carboxylic acid and its derivative in the acid-modified polyolefin resin is preferably 0.1% by mass to 20% by mass, and more preferably 1% by mass to 10% by mass, based on 100% by mass of the acid-modified polyolefin resin.
The graft mass (mass %) of the α,β-unsaturated carboxylic acid and its derivatives can be measured by a known method, for example, alkali titration method or Fourier transform infrared spectroscopy.

From the viewpoints of adhesiveness and compatibility with alcohol-soluble nylon resins, the acid-modified polyolefin resin is preferably modified with a (meth)acrylic acid ester.
The (meth)acrylic acid ester is not particularly limited, but from the viewpoints of adhesion and compatibility with the alcohol-soluble nylon resin, a compound represented by the following formula (I) is preferred.
CH ₂ =CR ^1A COOR ^2A ...(I)
In formula (I), R ^1A represents a hydrogen atom or a methyl group, and R ^2A represents an alkyl group having 8 to 18 carbon atoms.

In formula (I), R ^1A is preferably a methyl group.
In formula (I), R ^2A is preferably an alkyl group having 8 to 16 carbon atoms, and is preferably a linear alkyl group.
The compound represented by formula (I) is preferably octyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, or stearyl (meth)acrylate.
In this specification, "(meth)acrylic" means acrylic and methacrylic.

From the viewpoints of adhesion and compatibility with the alcohol-soluble nylon resin, the graft mass of the (meth)acrylic acid ester in the acid-modified polyolefin resin is preferably 0.1% by mass to 30% by mass, and more preferably 1% by mass to 15% by mass, based on 100% by mass of the acid-modified polyolefin resin.
The graft mass (mass %) of the (meth)acrylic acid ester can be measured by a known method, for example, by Fourier transform infrared spectroscopy or ¹ H-NMR.

In the present disclosure, graft components other than α,β-unsaturated carboxylic acids and derivatives thereof, and (meth)acrylic acid esters can be used in combination depending on the purpose, within a range that does not impair the properties of the adhesive composition according to the present disclosure.
Examples of the graft component that can be used include (meth)acrylic acid, glycidyl (meth)acrylate, isocyanate-containing (meth)acrylic acid, and other copolymerizable unsaturated monomers such as styrene, cyclohexyl vinyl ether, and dicyclopentadiene. By using these monomers in combination, it is possible to further improve the adhesiveness and solubility in a solvent, as well as the graft rate of the α,β-unsaturated carboxylic acid and its derivatives, and the (meth)acrylic acid ester. It is preferable that the amount of these monomers used does not exceed the total amount of the grafts of the α,β-unsaturated carboxylic acid and its derivatives, and the (meth)acrylic acid ester.

The weight average molecular weight of the acid-modified polyolefin resin is not particularly limited, but is preferably from 15,000 to 200,000, and more preferably from 30,000 to 200,000. When it is in the above range, the adhesiveness is excellent and the solubility in alcohol is excellent.
The weight average molecular weight of the acid-modified polyolefin resin is measured by gel permeation chromatography (hereinafter also referred to as "GPC") and converted based on the molecular weight of polystyrene.

In addition, the melting point of the acid-modified polyolefin resin as measured by a differential scanning calorimeter (hereinafter also referred to as "DSC") is preferably 50°C to 135°C, more preferably 50°C to 90°C, and particularly preferably 60°C to 85°C, from the viewpoints of adhesiveness and liquid stability.

The acid-modified polyolefin resin is a resin in which a polyolefin resin (A) is graft-modified with an α,β-unsaturated carboxylic acid or a derivative thereof (B) and a (meth)acrylic acid ester (C) represented by the formula (I), and the graft masses of the α,β-unsaturated carboxylic acid or a derivative thereof (B) and the (meth)acrylic acid ester (C) represented by the formula (I) in the acid-modified polyolefin resin are preferably 0.3% by mass to 1.2% by mass and 0.5% by mass to 3.6% by mass, respectively, and the weight average molecular weight of the acid-modified polyolefin resin is preferably 82,000 to 20,000.
Preferred examples of the polyolefin resin (A), the α,β-unsaturated carboxylic acid or a derivative thereof (B), and the (meth)acrylic acid ester (C) represented by the formula (I) include the above-mentioned polyolefin resin, the α,β-unsaturated carboxylic acid or a derivative thereof, and the (meth)acrylic acid ester represented by the formula (I), respectively.

Acid-modified polyolefin resins can be obtained, for example, by graft polymerization of α,β-unsaturated carboxylic acid or its derivative, and (meth)acrylic acid ester onto polyolefin resin. Modified polyolefin resins can be synthesized by known methods, and a radical generator, described below, may be used during production. Examples include a solution method in which polyolefin resin is heated and dissolved in a solvent such as toluene, and α,β-unsaturated carboxylic acid or its derivative, and (meth)acrylic acid ester are added, and a melt method in which α,β-unsaturated carboxylic acid or its derivative, (meth)acrylic acid ester, and radical generator are added together with molten polyolefin resin using a Banbury mixer, kneader, extruder, etc. Each component may be added all at once or successively.

Depending on the purpose of use, the acid-modified polyolefin resin can further contain reaction aids to improve the grafting efficiency of the unsaturated carboxylic acid, stabilizers to adjust the resin stability, radical initiators to promote the reaction, etc.

Examples of the reaction aid include styrene, o-methylstyrene, p-methylstyrene, α-methylstyrene, divinylbenzene, hexadiene, and dicyclopentadiene.
Stabilizers include hydroquinone, benzoquinone, nitrosophenyl hydroxy compounds, and the like.
As the radical initiator, known ones can be used. For example, it is preferable to use an organic peroxide such as benzoyl peroxide, dicumyl peroxide, lauroyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, or cumene hydroperoxide.

<Alcohol-soluble nylon resin>
The adhesive composition according to the present disclosure includes an alcohol-soluble nylon resin.
The alcohol-soluble nylon resin used in the present disclosure is a nylon resin that dissolves in an alcohol solvent and is preferably a nylon resin that is solid at 25°C.
In the present disclosure, the alcohol-soluble nylon resin dissolves preferably in an amount of 1 g or more, more preferably 5 g or more, and particularly preferably 10 g or more in 100 g of an alcohol-based solvent (e.g., ethanol) at 25°C.
Alcohol-soluble nylon resins can be synthesized by dehydration condensation reactions of various dicarboxylic acids and diamines, self-condensation of aminocarboxylic acids, ring-opening polymerization of intramolecular cyclic compounds of aminocarboxylic acids, and combinations of these reactions.

The alcohol-soluble nylon resin used in the present disclosure preferably contains piperazine as a constituent component, which provides superior adhesiveness.
The content of piperazine in the alcohol-soluble nylon resin is preferably 20 mol % or more, and more preferably 40 mol % to 100 mol %, when the total amount of the diamine components constituting the alcohol-soluble nylon resin is taken as 100 mol %.

Diamine compounds other than piperazine that are used in the synthesis of alcohol-soluble nylon resin include, but are not limited to, ethylenediamine, tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, p-diaminomethylcyclohexane, bis(p-aminocyclohexyl)methane, m-xylenediamine, and isophoronediamine.

Dicarboxylic acids used in synthesizing alcohol-soluble nylon resin include, but are not limited to, adipic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, dimer acid, isophthalic acid, terephthalic acid, and sodium 5-sulfoisophthalate. From the viewpoint of solubility in alcohol, it is preferable to use all or part of dicarboxylic acids with relatively low crystallinity, such as azelaic acid, undecanedioic acid, and dimer acid.

Aminocarboxylic acids used in the synthesis of alcohol-soluble nylon resin include 11-aminoundecanoic acid, 12-aminododecanoic acid, 4-aminomethylbenzoic acid, 4-aminomethylcyclohexanecarboxylic acid, etc., and intramolecular cyclic compounds of aminocarboxylic acids include, but are not limited to, β-lactam, ε-caprolactam, laurinlactam, α-pyrrolidone, α-piperidone, etc.

Also, alcohol-soluble nylon resins can be preferably used that have been made by introducing N-alkoxymethyl groups, which are formed by adding formalin and alcohol to the polyamide bonds in the alcohol-soluble nylon resins. The introduction of N-alkoxymethyl groups contributes to lowering the melting point, increasing flexibility, and improving solubility, and the introduction rate is determined according to the purpose.

The amine value of the alcohol-soluble nylon resin is preferably 1 mgKOH/g to 6 mgKOH/g from the viewpoints of adhesiveness and curability.
From the viewpoints of adhesiveness and curability, the acid value of the alcohol-soluble nylon resin is preferably 4 mgKOH/g to 10 mgKOH/g.
The amine value of an alcohol-soluble nylon resin means the number of milligrams of KOH equivalent to hydrochloric acid required to neutralize the amine present in 1 g of the resin, and the acid value means the number of milligrams of KOH required to neutralize the acid present in 1 g of the resin.

The method for measuring the amine value of the alcohol-soluble nylon resin in the present disclosure is as follows.
3 g of alcohol-soluble nylon resin is dissolved in a mixed solution of 20 mL of 1-butanol and 20 mL of toluene, and an automatic titrator "AT-510" manufactured by Kyoto Electronics Manufacturing Co., Ltd. is used with an "APB-510-01B" manufactured by Kyoto Electronics Manufacturing Co., Ltd. connected as a burette. Potentiometric titration is performed using a 0.1 mol/L 2-propanol hydrochloric acid solution as the titration reagent, and the mg of hydrochloric acid and the equivalent amount of KOH per 1 g of resin is calculated.

The method for measuring the acid value of the alcohol-soluble nylon resin in the present disclosure is as follows.
1 g of alcohol-soluble nylon resin is dissolved in 40 mL of benzyl alcohol, and an automatic titrator "AT-510" manufactured by Kyoto Electronics Manufacturing Co., Ltd. is connected to an "APB-510-20B" manufactured by Kyoto Electronics Manufacturing Co., Ltd. as a buret and used. Potentiometric titration is performed using a 0.01 mol/L benzyl alcohol-based KOH solution as the titration reagent, and the number of mg of KOH per 1 g of resin is calculated.

Alcohol-soluble nylon resin can be synthesized in a single batch without solvent through dehydration condensation reaction, dealcoholization reaction, ring-opening polymerization reaction, etc. In this case, water can be added in advance along with the raw material monomers, and the dehydration reaction can be carried out while distilling off the water. This reaction can be carried out either under normal pressure or under reduced pressure. The molecular weight and amine value of the nylon resin can be adjusted by adjusting the ratio of diamine and dicarboxylic acid added when synthesizing the nylon resin, the reaction time, and the degree of reduced pressure.

The adhesive composition according to the present disclosure has a mass ratio of the acid-modified polyolefin resin to the alcohol-soluble nylon resin (acid-modified polyolefin resin/alcohol-soluble nylon resin) of 90/10 to 30/70, and from the viewpoint of adhesion, it is preferably 70/30 to 30/70, and more preferably 60/40 to 40/60.

The total content of the acid-modified polyolefin resin and the alcohol-soluble nylon resin in the adhesive composition according to the present disclosure is, from the viewpoint of adhesion, preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass to 100% by mass, based on the total solid content of the adhesive composition.

From the viewpoint of liquid stability, the resin solids content in the adhesive composition according to the present disclosure is preferably 30 mass % or less, more preferably 20 mass % or less, even more preferably 1 mass % to 20 mass %, and particularly preferably 3 mass % to 15 mass %, relative to the total mass of the adhesive composition.
The resin solids include the acid-modified polyolefin resin, the alcohol-soluble nylon resin, and a polymer-type polyfunctional silane coupling agent, which will be described later.

<Alcohol Solvent>
The adhesive composition according to the present disclosure includes an alcohol solvent.
From the viewpoint of liquid stability, the adhesive composition according to the present disclosure is preferably a solution of the acid-modified polyolefin resin and the alcohol-soluble nylon resin in a solvent containing an alcohol solvent.
From the viewpoint of solubility, the alcohol solvent is preferably an alcohol having one hydroxyl group.
From the viewpoint of solubility, the alcohol solvent is preferably an alcohol having 1 to 4 carbon atoms, and more preferably an alcohol having 1 to 3 carbon atoms.
Specific examples of the alcohol solvent include methanol, ethanol, n-propanol, isopropanol, n-butanol, and 2-butanol.
Among these, from the viewpoint of solubility, the alcohol solvent is preferably at least one selected from the group consisting of methanol, ethanol, n-propanol, and isopropanol, and more preferably ethanol.

The alcohol solvent may be used alone or in combination of two or more kinds.
From the viewpoint of liquid stability, the solids content in the adhesive composition according to the present disclosure is preferably 30 mass % or less, more preferably 20 mass % or less, even more preferably 1 mass % to 20 mass %, and particularly preferably 3 mass % to 15 mass %, relative to the total mass of the adhesive composition.

From the viewpoint of liquid stability, the content of the alcohol solvent in the adhesive composition according to the present disclosure is preferably 50% by mass or more, more preferably 60% by mass to 99% by mass, even more preferably 65% by mass to 97% by mass, and particularly preferably 70% by mass to 95% by mass, based on the total mass of the adhesive composition.

<Water>
From the viewpoint of liquid stability, the adhesive composition according to the present disclosure preferably further contains water.
Moreover, from the viewpoint of liquid stability, the adhesive composition according to the present disclosure is preferably a solution of a solvent containing an alcohol solvent and water, and more preferably a solution of an alcohol solvent and water.
In the method for producing an adhesive composition according to the present disclosure, since it is preferable to use an emulsion (water-based emulsion) of the acid-modified polyolefin resin as a raw material, the adhesive composition according to the present disclosure preferably contains not only an alcohol solvent but also water. That is, the adhesive composition according to the present disclosure may contain a mixed solvent of alcohol and water.

From the viewpoint of liquid stability, the water content in the adhesive composition according to the present disclosure is preferably 1 mass % to 40 mass %, more preferably 2 mass % to 30 mass %, even more preferably 3 mass % to 25 mass %, and particularly preferably 4 mass % to 20 mass %, relative to the total mass of the adhesive composition.
The water content is preferably 5% by mass to 70% by mass, more preferably 10% by mass to 50% by mass, and particularly preferably 10% by mass to 40% by mass, based on the total amount of the acid-modified polyolefin and water.

By mixing an emulsion of acid-modified polyolefin resin (especially a water-based emulsion) with alcohol and then dissolving alcohol-soluble nylon resin in it, an emulsion can be created in which the solution containing the acid-modified polyolefin is dispersed in the solvent as fine droplets. This makes it possible to obtain a one-component adhesive composition that has excellent adhesion between thermoplastic elastomers and glass.

From the viewpoint of liquid stability, the total content of the alcohol solvent and water in the adhesive composition according to the present disclosure is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 80% by mass to 99% by mass, and particularly preferably 85% by mass to 97% by mass, based on the total mass of the adhesive composition.

<Silane coupling agent>
From the viewpoints of adhesion and adhesive strength, the adhesive composition according to the present disclosure preferably further contains a silane coupling agent, more preferably further contains a silane coupling agent having an epoxy group, and particularly preferably further contains a polymeric multifunctional silane coupling agent having two or more epoxy groups.
As the silane coupling agent, any known silane coupling agent can be used, but from the viewpoint of adhesive strength, one having an epoxy group is preferred, and one having two or more epoxy groups is more preferred.

From the viewpoint of adhesiveness and adhesive strength, the silane coupling agent is preferably a polymer-type polyfunctional silane coupling agent.
The polymer-type polyfunctional silane coupling agent is a polymer-type silane coupling agent having an alkoxysilyl group and two or more reactive functional groups other than the alkoxysilyl group (for example, an epoxy group, an amino group, etc.).
Among the polymer-type polyfunctional silane coupling agents, a polymer-type polyfunctional silane coupling agent having two or more epoxy groups is preferred from the viewpoint of adhesive strength.
From the viewpoint of adhesive strength, the polymer-type polyfunctional silane coupling agent preferably has an alkoxysilyl group and two or more epoxy groups and has a weight average molecular weight of 200 to 10,000.

Examples of the polymer-type polyfunctional silane coupling agent having two or more epoxy groups include compounds represented by the following formula (1) or the following formula (2).
In formula (1), R ¹ to R ³ each independently represent a hydrogen atom, a glycidyl group, or an alkoxysilyl group represented by the following formula (3), at least one of R ¹ to R ³ is an alkoxysilyl group represented by the following formula (3), and at least two of R ¹ to R ³ are glycidyl groups. a represents an integer of 1 to 100, preferably an integer of 1 to 40, and more preferably an integer of 1 to 30.
In formula (2), R ⁴ to R ⁶ each independently represent a hydrogen atom, a glycidyl group, or an alkoxysilyl group represented by the following formula (3), and at least one of R ⁴ to R ⁶ is an alkoxysilyl group represented by the following formula (3), and at least two of R ⁴ to R ⁶ are glycidyl groups. b represents an integer of 4 to 10, preferably an integer of 4 to 8, and more preferably 4 or 5. c represents an integer of 0 to 10, preferably an integer of 0 to 8, and more preferably an integer of 0 to 5. d represents an integer of 0 to 10, preferably an integer of 0 to 8, and more preferably an integer of 0 to 5. e represents an integer of 0 to 10, preferably an integer of 0 to 8, and more preferably an integer of 0 to 5.
In formula (3), R ⁷ represents an alkyl group having 1 to 6 carbon atoms, X represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 1 to 3.

In the compound represented by formula (1), the molar ratio MC/MD of the glycidyl group MC to the alkoxysilyl group MD is preferably 0.02 to 100, more preferably 0.05 to 50, and even more preferably 0.1 to 10.
In the compound represented by formula (2), the molar ratio ME/MF of the glycidyl group ME to the alkoxysilyl group MF is preferably 0.1-9, and more preferably 0.2-5.

The epoxy equivalent of the polymer-type polyfunctional silane coupling agent (the mass of a resin containing one equivalent of an epoxy group) is preferably 100 to 500, more preferably 100 to 400, and even more preferably 100 to 300, from the viewpoint of adhesive strength.
The epoxy equivalent can be determined in accordance with JIS K 7236:2009.
The weight average molecular weight of the polymer-type multifunctional silane coupling agent is preferably 200 to 10,000, and more preferably 300 to 8,000. Here, the weight average molecular weight of the polymer-type multifunctional silane coupling agent is a value measured by gel permeation chromatography (GPC) using standard polystyrene.

Specific examples of polymer-type multifunctional silane coupling agents having two or more epoxy groups include X-12-981S and X-12-984S manufactured by Shin-Etsu Chemical Co., Ltd.

The content of the silane coupling agent in the adhesive composition according to the present disclosure, preferably the content of a polymeric polyfunctional silane coupling agent having two or more epoxy groups, is preferably 0.5% by mass to 20% by mass, more preferably 1.0% by mass to 10% by mass, and particularly preferably 1.0% by mass to 8.0% by mass, based on the total solid content of the adhesive composition, from the viewpoint of adhesion and adhesive strength.

<Other ingredients>
The adhesive composition according to the present disclosure may contain other components in addition to those described above.
As the other components, known additives can be used, such as extender pigments, coloring pigments, dyes, antioxidants, plasticizers, lubricants, flame retardants, antistatic agents, ultraviolet absorbers, fillers, surfactants, thickeners, etc. Such additives can be added during or after dissolving the raw materials in alcohol.

Examples of antioxidants include phenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate, and tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, sulfur-based antioxidants such as dilauryl-3,3'-thiodipropionate and dimyristyl-3,3'-dithiopropionate, and phosphorus-based antioxidants such as trisnonylphenyl phosphite and tris(2,4-di-t-butylphenyl)phosphite.

Examples of ultraviolet absorbers include benzotriazole-based ultraviolet absorbers such as 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 2-[(2'-hydroxy-3',5'-bis(α,α-dimethylbenzyl)phenyl]-benzotriazole, benzophenone-based ultraviolet absorbers such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, and 2-hydroxy-4-n-octylbenzophenone, and phenyl salicylate. Examples include salicylate-based UV absorbers, cyanoacrylate-based UV absorbers such as ethyl-2-cyano-3,3-diphenylacrylate, oxalic anilide-based UV absorbers such as 2-ethoxy-2'-ethyl oxalic acid bisanilide, and hindered amine-based UV absorbers such as bis[2,2,6,6-tetramethyl-4-piperidine]sebacate and bis[N-methyl-2,2,6,6-tetramethyl-4-piperidinyl]sebacate.

Examples of flame retardants include bromine-based flame retardants such as tetrabromobisphenol A, hexabromobenzene, decabromodiphenyl ether, hexabromocyclododecane, bis(pentabromophenyl)ethane, and bis(tetrabromophthalimide)ethane; aromatic phosphate ester-based flame retardants such as triphenyl phosphate, 2-ethylhexyl diphenyl phosphate, and cresyl diphenyl phosphate; aromatic condensed phosphate esters such as 1,3-phenylene bis(diphenyl phosphate), 1,3-phenylene bis(dixylenyl)phosphate, and bisphenol A bis(diphenyl phosphate); halogen-containing phosphate ester-based flame retardants such as tris(dichloropropyl)phosphate; red phosphorus-based flame retardants such as red phosphorus; inorganic flame retardants such as aluminum hydroxide, magnesium hydroxide, and antimony trioxide; silicon-based flame retardants; and boron-based flame retardants.

Examples of fillers include calcium carbonate, titanium oxide, zinc oxide, talc, calcium carbonate, carbon black, silica, copper powder, aluminum powder, silver powder, etc.

<Method of producing adhesive composition>
The method for producing the adhesive composition according to the present disclosure is not particularly limited, but from the viewpoints of ease of preparation of the adhesive composition and liquid stability, it is preferable that the method includes a step of mixing an acid-modified polyolefin resin emulsion with an alcohol solvent to obtain a mixture, and a step of adding an alcohol-soluble nylon resin to the mixture.
From the viewpoints of ease of preparation of the adhesive composition and liquid stability, the acid-modified polyolefin resin emulsion is preferably an aqueous emulsion of an acid-modified polyolefin resin.
The method for preparing the aqueous emulsion of acid-modified polyolefin resin is not particularly limited, but a suitable method is to dissolve the aqueous emulsion of acid-modified polyolefin resin in an organic solvent such as toluene, add a basic compound such as an amine compound and a surfactant, add water to cause phase inversion emulsification, remove the organic solvent by reducing pressure, and adjust the solid content concentration with water. The following is an example of materials used to prepare the aqueous emulsion of acid-modified polyolefin resin. These materials may be included in the adhesive composition as they are.

The organic solvent is preferably one in which the acid-modified polyolefin dissolves. Specific examples of organic solvents include aromatic organic solvents such as toluene and xylene, aliphatic organic solvents such as n-hexane, alicyclic organic solvents such as cyclohexane, methylcyclohexane, and ethylcyclohexane, ketone organic solvents such as acetone and methyl ethyl ketone, alcohol organic solvents such as methanol and ethanol, ester organic solvents such as ethyl acetate and butyl acetate, and propylene glycol ether organic solvents such as propylene glycol methyl ether, propylene glycol ethyl ether, and propylene glycol t-butyl ether.

Basic compounds such as amine compounds include, for example, ammonia, methylamine, ethylamine, dimethylamine, diethylamine, triethylamine, propylamine, isopropylamine, dipropylamine, isobutylamine, hexylamine, octylamine, ethanolamine, propanolamine, diethanolamine, N-methyldiethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N,N-dibutylethanolamine, 2-dimethylamino-2-methyl-1-propanol, 2-amino-2-methyl-1-propanol, 1-propanol, 2-aminoethanol, 2-dimethylaminoethanol, 2-diethylaminoethanol, 3-ethoxypropylamine, 3-diethylaminopropylamine, sec-butylamine, propylamine, n-butylamine, 2-methoxyethylamine, 3-methoxypropylamine, 2,2-dimethoxyethylamine, monoethanolamine, morpholine, N-methylmorpholine, N-ethylmorpholine, piperazines, pyrrole, pyridine, sodium hydroxide, potassium hydroxide, magnesium hydroxide and other alkali metal compounds. Among these, from the viewpoint of ease of emulsification and dispersion, morpholine, N,N-dimethylethanolamine, N,N-diethylethanolamine, and 2-amino-2-methyl-1-propanol are preferred.

The boiling point of the basic compound at normal pressure is preferably 200°C or less. If the boiling point exceeds 200°C, for example, when the modified polyolefin resin water dispersion composition is used as a coating film, it may be difficult to remove the basic compound by the drying treatment in the water removal process, and the water resistance and moisture resistance of the coating film, particularly when dried at low temperatures, and the adhesion to substrates such as non-polar resin molded products, may deteriorate.

The basic compound such as an amine compound may be a single basic compound or a combination of two or more basic compounds. In the latter case, the mixing ratio of each compound is not particularly limited.

The adhesive composition may contain a basic compound, particularly an amine compound. The content of the basic compound, particularly the amine compound, is not particularly limited, but may be, for example, within the range of 0.1 parts by mass to 10 parts by mass per 100 parts by mass of the acid-modified polyolefin.

Surfactants include nonionic surfactants (emulsifiers), anionic surfactants (emulsifiers), and cationic surfactants (emulsifiers), as shown below.

Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene derivatives, polyoxyethylene fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene polyhydric alcohol fatty acid esters, polyoxyethylene polyoxypropylene polyols, sorbitan fatty acid esters, polyoxyethylene hydrogenated castor oil, polyoxyalkylene polycyclic phenyl ethers, polyoxyethylene alkylamines, polyoxyalkylene alkylamines, alkyl alkanolamides, polyalkylene glycol (meth)acrylates, etc.

Examples of anionic surfactants include alkyl sulfate ester salts, polyoxyethylene alkyl ether sulfate salts, alkylbenzene sulfonates, α-olefin sulfonates, methyl taurates, sulfosuccinates, ether sulfonates, ether carboxylates, fatty acid salts, naphthalenesulfonate-formaldehyde condensates, alkylamine salts, quaternary ammonium salts, alkyl betaines, and alkylamine oxides.

The adhesive composition according to the present disclosure may contain a surfactant. The amount of surfactant is not particularly limited, but is preferably 1 to 20 parts by mass, and more preferably 1 to 10 parts by mass, per 100 parts by mass of the acid-modified polyolefin.

<Application>
The adhesive composition according to the present disclosure has excellent adhesion between a thermoplastic elastomer and glass, and can therefore be suitably used in applications in which the two are bonded together.
Since the adhesive composition according to the present disclosure has the above-mentioned properties, it can be used as an adhesive for automobiles and vehicles (bullet trains and electric trains), ships, aircraft, architecture, civil engineering, electronics, the aerospace industry, and other industrial products.

The adhesive composition according to the present disclosure can be used as an adhesive composition that is applied to objects to be adhered, such as interior and exterior parts of automobiles. In particular, the adhesive composition according to the present disclosure can improve the adhesion between glass members, such as automobile window glass, and resin members, and can therefore be suitably used as a window sealant.
That is, the adhesive composition according to the present disclosure can be particularly suitably used as an adhesive composition for automobile window glass.

(Coatings and adhesives)
The coating film according to the present disclosure is a coating film formed by drying the adhesive composition according to the present disclosure, or by drying and curing the adhesive composition.
The adhesive product according to the present disclosure is an adhesive product having an adhesive layer formed by drying and curing the adhesive composition according to the present disclosure.
After forming a coating film using the adhesive composition according to the present disclosure, the coating film is dried and the organic solvent is volatilized to produce a dried coating film, i.e., an adherend.
The drying temperature of the coating film is not particularly limited, and from the viewpoint of workability, it is preferably 30° C. to 100° C. In order to obtain strong adhesion between the two members to be bonded, a method such as pressure bonding at a temperature of 80° C. or higher can be applied.

The adhesive according to the present disclosure preferably has the adhesive layer between a thermoplastic elastomer member and a glass member.
The thermoplastic elastomer is not particularly limited, but examples thereof include styrene elastomers, olefin elastomers, polyester elastomers, urethane elastomers, and amide elastomers.
The glass is not particularly limited, but examples thereof include soda glass, quartz glass, lead glass, borosilicate glass, and crystallized glass.
The thickness of the adhesive layer is not particularly limited, but is preferably 0.5 μm to 20 μm, and more preferably 1 μm to 10 μm.

The present disclosure will be explained in more detail below with reference to examples, but the present disclosure is not limited to the following examples as long as it does not deviate from the gist of the disclosure. Unless otherwise specified, "%" is based on mass.

Synthesis Example 1: Preparation of acid-modified polyolefin resin emulsion
In a four-neck flask equipped with a stirrer, a cooling tube, a thermometer, and a funnel, 100 g of maleic anhydride [MAH] modified polyolefin resin (weight average molecular weight 150,000, melting point (Tm) = 70 ° C., MAH graft amount = 2% to 5%) of propylene-butene random copolymer [P-B] (propylene component 70 mol%, butene component 30 mol%), 80 g of toluene, and 4 g of morpholine were added, and 10 g of Emulgen 109P (nonionic surfactant, manufactured by Kao Corporation) was added, and the mixture was kneaded for 60 minutes at a flask temperature of 95 ° C. Then, 290 g of deionized water at 90 ° C. was added over 60 minutes. Subsequently, a portion of the toluene was removed under reduced pressure, and the mixture was cooled to room temperature while stirring, and an acid-modified polyolefin resin emulsion was obtained in which the solid content was adjusted to 30 mass% with deionized water.

<Synthesis Example 2: Preparation of alcohol-soluble nylon resin>
A flask equipped with a stirrer, a reflux dehydration device, and a distillation tube was charged with 47 parts by mass of azelaic acid, 215 parts by mass of dodecanedioic acid, 100 parts by mass of piperazine, 63 parts by mass of 11-aminoundecanoic acid, and 120 parts by mass of distilled water. The temperature was raised to 120°C to distill off water, and then the temperature was raised to 240°C at a rate of 20°C/hour. The reaction was continued for 3 hours, and it was confirmed that the amine value reached the target range, to obtain an alcohol-soluble nylon resin. The amine value at that time was 2.5 mgKOH/g, and the acid value was 7.2 mgKOH/g.

<Synthesis Example 3>
Each component was charged according to the charge amounts in Table 1, and reacted in the same manner as in Synthesis Example 2 to obtain an alcohol-soluble nylon resin. The amine value and acid value of the obtained alcohol-soluble nylon resin are shown in Table 1.

Synthesis Example 4: Preparation of non-emulsion acid-modified polyolefin resin
A twin-screw extruder having a screw length L and screw diameter D ratio L/D=42 and a screw diameter φ=58 mm was charged with 100 parts by mass of a propylene-ethylene-α-olefin copolymer (propylene component 72 mol%, ethylene component 7 mol%, butene component 21 mol%, weight average molecular weight 120,000, Tm=100°C), 1.5 parts by mass of maleic anhydride, 4 parts by mass of lauryl methacrylate, and 1.5 parts by mass of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane. The reaction was carried out with a residence time of 10 minutes and a barrel temperature of 180°C (first barrel to seventh barrel), and degassing was carried out in the seventh barrel to remove the remaining unreacted material. The weight average molecular weight of the obtained acid-modified polyolefin resin was 92,000, Tm=90°C, the graft mass of maleic anhydride was 1.1% by mass, and the graft mass of lauryl methacrylate was 3.6% by mass. The carboxy group content was 22.4 mmol/100 g. The graft mass of unsaturated polycarboxylic acid such as maleic anhydride and its derivatives was measured by alkali titration, and the graft mass of lauryl methacrylate was measured by ¹ H-NMR.

Example 1
A flask equipped with a stirrer, a cooling tube, and a thermometer was charged with 100 g of the acid-modified polyolefin resin emulsion obtained in Synthesis Example 1 and 476.9 g of ethanol, and then 30.36 g of the alcohol-soluble nylon resin obtained in Synthesis Example 2 was added thereto. The flask temperature was raised to 30°C to 50°C, and the mixture was stirred for 90 minutes to dissolve the alcohol-soluble nylon resin, thereby obtaining an emulsion adhesive composition with an acid-modified polyolefin resin/alcohol-soluble nylon resin mass ratio of 5/5.

Example 2
An emulsion adhesive composition was obtained by adding 1.2 g of a silane coupling agent X-12-984S (a polymer-type multifunctional silane coupling agent having two or more epoxy groups, manufactured by Shin-Etsu Chemical Co., Ltd.) to 607.3 g of the acid-modified polyolefin resin/alcohol-soluble nylon resin solution obtained in Example 1.

(Examples 3 to 14 and Comparative Examples 1 to 7)
The components were charged in the ratios shown in Table 2 or Table 3, and an (emulsion) adhesive composition was obtained in the same manner as in Example 1 or 2.

The resulting (emulsion) adhesive composition was subjected to various tests using the methods described below.

<Production of Glass Plate (Test Piece) with Thermoplastic Elastomer Molding (TPV)>
A glass plate measuring 25 mm in length, 150 mm in width, and 5 mm in thickness was prepared, and the (emulsion) adhesive composition was applied so that the adhesive layer would have a thickness of about 1 μm to 10 μm after drying, and then the plate was dried by blowing air to prepare a glass plate on which an adhesive layer was formed.
An olefin-based thermoplastic elastomer material (Santoprene 121-58W175, ExxonMobil) was insert molded onto the glass plate on which the adhesive layer was formed, to obtain a glass plate with a thermoplastic elastomer molding. The molding temperature was 210°C. An initial peel strength test and a moisture resistance test were performed using each of the glass plates with a thermoplastic elastomer molding (test pieces) obtained above, to measure the adhesive strength. The results are shown in Tables 2 and 3.

Each of the obtained test pieces was left at room temperature (25° C., hereinafter the same) for 24 hours, and then a 90° peel test was performed at room temperature in accordance with the floating roller peel test specified in JIS K 6854 at a crosshead moving speed of 50 mm/min, to measure the initial peel strength (N/mm) and to confirm the fracture mode after the measurement.
After the test, the test pieces were visually inspected to confirm the form of fracture.

2. Moisture Resistance Test Each test piece was left at room temperature for 24 hours, then left at 80°C and 80% RH for 24 hours, and then left at room temperature for another 24 hours. A 90° peel test was then performed in accordance with JIS K 6854, and the peel strength after moisture resistance (moisture resistance test, N/mm) was measured, and the fracture mode after the measurement was confirmed.
After the test, the test pieces were visually inspected to confirm the form of fracture.

3. Liquid Stability Test The prepared (emulsion) adhesive composition was allowed to stand at room temperature for 2 weeks, and the appearance of the liquid was then visually inspected.
The presence or absence of liquid separation and resin settling was evaluated as A, B, or C.
A: No separation of liquid or settling of resin is observed.
B: Slight separation of liquid or settling of resin was observed.
C: Separation of liquid and/or settling of resin was observed.

In Tables 2 and 3, Synthesis Example 1 represents the resin solid content in the emulsion obtained in Synthesis Example 1, and Synthesis Examples 2 to 4 represent the resins obtained in Synthesis Examples 2 to 4, respectively.
In addition, CF in Tables 2 and 3 represents cohesive failure, which is failure within the adhesive layer, and AF represents interfacial failure, which is failure at the bonding interface between the adhesive layer and the adherend. Cohesive failure indicates excellent adhesion, and interfacial failure indicates insufficient adhesion.

Details of the abbreviations listed in Table 2 are shown below.
X-12-981S: Polymer-type multifunctional silane coupling agent having two or more epoxy groups (manufactured by Shin-Etsu Chemical Co., Ltd.)
KBM-403: 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)

As shown in Tables 2 and 3, the emulsion adhesive compositions of Examples 1 to 14 had superior adhesion between thermoplastic elastomer and glass compared to the adhesive compositions of Comparative Examples 1 to 6. Comparative Example 7 could not be evaluated because it was not possible to maintain a homogeneous state as a solution.
Furthermore, as shown in Tables 2 and 3, the emulsion adhesive compositions of Examples 1 to 13 also had excellent liquid stability.

The disclosure of Japanese Patent Application No. 2024-6299, filed on January 18, 2024, is incorporated herein by reference in its entirety.
All publications, patent applications, and technical standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.

Claims (13)

An acid-modified polyolefin resin;
An alcohol-soluble nylon resin;
and an alcohol solvent,
a mass ratio of the acid-modified polyolefin resin to the alcohol-soluble nylon resin (acid-modified polyolefin resin/alcohol-soluble nylon resin) is 90/10 to 30/70;
An emulsion adhesive composition, in which the acid-modified polyolefin resin is dispersed in an alcohol solvent. The emulsion adhesive composition according to claim 1, wherein the resin solids content is 20% by mass or less. The emulsion adhesive composition of claim 1 further comprising water. The emulsion adhesive composition according to claim 1, further comprising a polymeric multifunctional silane coupling agent having two or more epoxy groups. The emulsion adhesive composition according to claim 4, wherein the mass ratio of the total mass of the resin solids of the acid-modified polyolefin resin and the alcohol-soluble nylon resin to the polymer-type multifunctional silane coupling agent having two or more epoxy groups (acid-modified polyolefin resin + solvent-soluble nylon resin/polymer-type multifunctional silane coupling agent having two or more epoxy groups) is 100/0.5 to 100/10. The emulsion adhesive composition according to claim 1, wherein the acid-modified polyolefin resin is an acid-modified product of at least one resin selected from the group consisting of ethylene-propylene copolymer, propylene-butene copolymer, and ethylene-propylene-butene copolymer. The emulsion adhesive composition according to claim 1, wherein the acid-modified polyolefin resin is an itaconic anhydride and/or maleic anhydride-modified polyolefin resin. The emulsion adhesive composition according to claim 1, wherein the melting point of the acid-modified polyolefin resin is 50°C to 135°C. The emulsion adhesive composition according to claim 1, wherein the alcohol-soluble nylon resin contains 20 mol % or more of piperazine when the total amount of the diamine components constituting the alcohol-soluble nylon resin is taken as 100 mol %, and has an amine value of 1 mgKOH/g to 6 mgKOH/g and an acid value of 4 mgKOH/g to 10 mgKOH/g. The emulsion adhesive composition according to claim 4, wherein the polymeric polyfunctional silane coupling agent has an alkoxysilyl group and two or more epoxy groups and has a weight average molecular weight of 200 to 10,000. The emulsion adhesive composition according to claim 1, which is for use on automobile window glass. A coating film formed by drying, or by drying and curing, the emulsion adhesive composition according to any one of claims 1 to 11. An adhesive having an adhesive layer formed by drying and curing the emulsion adhesive composition according to any one of claims 1 to 11.