KR102349081B1 - Structural adhesive composition, and structural adhesive film, interior and exterior materials for automobile using the same - Google Patents

Abstract

The present invention relates to a structural adhesive composition in which an epoxy resin having a branched structure repeating unit structure is applied as a matrix, and a structural adhesive film and automobile interior and exterior materials using the same.

Description

Structural adhesive composition, structural adhesive film using same, and automotive interior and exterior materials

The present invention relates to a structural adhesive composition capable of exhibiting stable dispersion characteristics by suppressing change in viscosity due to sedimentation of internal components even during long-term storage and securing excellent reliability, and structural adhesive film and automobile interior and exterior materials using the same.

Structural adhesives are capable of adhering high-strength materials such as metals and composites, and are a means of replacing conventional bonding techniques, for example, welding or mechanical bonding of fasteners such as rivets, nuts, and bolts, or improving adhesion.

In addition, the structural adhesive can relieve the stress concentration on the bonding surface as well as the bonding of dissimilar materials, block gas and moisture, and improve workability. Due to these advantages, it can be used for various purposes ranging from general-purpose industrial fields to high-performance applications in automobile and aerospace industries.

Structural adhesives generally have a crosslinked structure based on thermosetting resins, and epoxy resins are typically used. Epoxy resin has many excellent properties compared to other resins, such as adhesion to various substrates, heat resistance, chemical resistance, electrical properties, and mechanical properties, and is used in a wide range of industrial fields. Epoxy resin is an intermediate (prepolymer) of a thermosetting resin, and by reaction with a curing agent, a three-dimensional network structure is formed as a cured product of the epoxy resin, thereby exhibiting unique properties of epoxy.

Structural adhesives are used by adding various inorganic fillers to achieve the purpose of thixotropic control, viscosity control, impact resistance improvement, and moisture removal. However, these inorganic fillers are not dissolved in the adhesive composition, but exist in a dispersed state, and when stored for a long period of time, they gradually sink down, causing a difference in viscosity and components between the upper and lower parts of the adhesive composition to satisfy optimal physical properties. There are difficult limits.

Accordingly, even during long-term storage, there is a demand for the development of a structural adhesive composition that can suppress a change in viscosity due to sedimentation of internal components, exhibit stable dispersion characteristics, and secure excellent reliability.

The present invention relates to a structural adhesive composition capable of exhibiting stable dispersion characteristics by suppressing change in viscosity due to sedimentation of internal components even during long-term storage and securing excellent reliability.

In addition, the present invention is to provide a structural adhesive film and automobile interior and exterior materials using the structural adhesive composition.

In order to solve the above problems, in the present specification, an epoxy resin containing a main chain including a branched polyvalent repeating unit represented by the following Chemical Formula 1, and an epoxide group bonded to the terminal of the main chain; epoxy curing agent; and an inorganic filler; provides a structural adhesive composition comprising.

[Formula 1]

In Formula 1, A is an n-valent multivalent functional group, n is an integer of 3 or more, X is one of -O-, -S-, or -NR ₁ -, wherein R ₁ in X is hydrogen or carbon number 1 to 20 alkyl groups.

The present specification also provides a structural adhesive film comprising a cured product of the structural adhesive composition.

In the present specification, there is also provided an automobile interior and exterior material including the structural adhesive film.

Hereinafter, a structural adhesive composition according to a specific embodiment of the present invention, and a structural adhesive film and automobile interior and exterior materials using the same will be described in more detail.

Unless explicitly stated herein, terminology is for the purpose of referring to specific embodiments only, and is not intended to limit the present invention.

As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite.

As used herein, the meaning of 'comprising' specifies a particular characteristic, region, integer, step, operation, element and/or component, and other specific characteristic, region, integer, step, operation, element, component, and/or group. It does not exclude the existence or addition of

And, in the present specification, terms including ordinal numbers such as 'first' and 'second' are used for the purpose of distinguishing one component from other components, and are not limited by the ordinal number. For example, within the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

In the present specification, the (co)polymer is meant to include both polymers or copolymers, the polymer means a homopolymer consisting of a single repeating unit, and the copolymer means a composite polymer containing two or more kinds of repeating units.

In the present specification, examples of the substituent are described below, but is not limited thereto.

In the present specification, the term "substituted" means that other functional groups are bonded instead of hydrogen atoms in the compound, and the position to be substituted is not limited as long as the position at which the hydrogen atom is substituted, that is, the position where the substituent is substituted, is not limited, and when two or more substituted , two or more substituents may be the same as or different from each other.

As used herein, the term "substituted or unsubstituted" refers to deuterium; halogen group; cyano group; nitro group; hydroxyl group; carbonyl group; ester group; imid; amide group; primary amino group; carboxyl group; sulfonic acid group; sulfonamide group; a phosphine oxide group; alkoxy group; aryloxy group; alkyl thiooxy group; arylthioxy group; an alkyl sulfoxy group; arylsulfoxy group; silyl group; boron group; an alkyl group; cycloalkyl group; alkenyl group; aryl group; aralkyl group; aralkenyl group; an alkylaryl group; alkoxysilylalkyl group; an arylphosphine group; Or N, O, and S atom means that it is substituted or unsubstituted with one or more substituents selected from the group consisting of a heterocyclic group containing one or more, or substituted or unsubstituted, two or more of the above-exemplified substituents are linked. . For example, "a substituent in which two or more substituents are connected" may be a biphenyl group. That is, the biphenyl group may be an aryl group or may be interpreted as a substituent in which two phenyl groups are connected.

, 또는

는 다른 치환기에 연결되는 결합을 의미하고, 직접결합은 L 로 표시되는 부분에 별도의 원자가 존재하지 않은 경우를 의미한다. In this specification,

, or

denotes a bond connected to another substituent, and a direct bond denotes a case in which a separate atom does not exist in the portion represented by L .

In the present specification, aromatic is a characteristic that satisfies the Huckels Rule, and a case in which all of the following three conditions are satisfied according to the Huckels Rule may be defined as aromatic.

1) There must be 4n+2 electrons that are completely conjugated by empty p-orbitals, unsaturated bonds, unpaired electron pairs, etc.

2) 4n+2 electrons must form a planar isomer and form a ring structure.

3) All atoms of the ring must be able to participate in conjugation.

In the present specification, the alkyl group is a monovalent functional group derived from an alkane, and may be straight-chain or branched, and the number of carbon atoms in the straight-chain alkyl group is not particularly limited, but is preferably 1 to 20. In addition, the number of carbon atoms of the branched chain alkyl group is 3 to 20. Specific examples of the alkyl group include methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methyl-butyl, 1-ethyl-butyl, pentyl, n -pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl , n-heptyl, 1-methylhexyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 1-ethyl- propyl, 1,1-dimethyl-propyl, isohexyl, 2-methylpentyl, 4-methylhexyl, 5-methylhexyl, 2,6-dimethylheptan-4-yl, and the like. The alkyl group may be substituted or unsubstituted, and when substituted, examples of the substituent are as described above.

In the present specification, the aryl group is a monovalent functional group derived from arene, and is not particularly limited, but preferably has 6 to 20 carbon atoms, and may be a monocyclic aryl group or a polycyclic aryl group. The aryl group may be a monocyclic aryl group, such as a phenyl group, a biphenyl group, or a terphenyl group, but is not limited thereto. The polycyclic aryl group may be a naphthyl group, an anthracenyl group, a phenanthryl group, a pyrenyl group, a perylenyl group, a chrysenyl group, a fluorenyl group, and the like, but is not limited thereto. The aryl group may be substituted or unsubstituted, and when substituted, examples of the substituent are the same as described above.

In the present specification, the alkylene group is a divalent functional group derived from an alkane, and the description of the alkyl group described above may be applied, except that these are divalent functional groups. For example, as a linear or branched type, it may be a methylene group, an ethylene group, a propylene group, an isobutylene group, a sec-butylene group, a tert-butylene group, a pentylene group, a hexylene group, and the like. The alkylene group may be substituted or unsubstituted, and when substituted, examples of the substituent are as described above.

In the present specification, a multivalent functional group is a residue in a form in which a plurality of hydrogen atoms bonded to an arbitrary compound are removed, and may include, for example, a divalent functional group, a trivalent functional group, and a tetravalent functional group. For example, the tetravalent functional group derived from cyclobutane refers to a residue in which 4 hydrogen atoms bonded to cyclobutane are removed.

In the present specification, a direct bond or a single bond means that no atom or group of atoms is present at the corresponding position, and thus is connected by a bonding line. Specifically, it refers to a case in which a separate atom does not exist in the portion represented by _{L 1} and L _{2 in the formula.}

In this specification, the weight average molecular weight means the weight average molecular weight in terms of polystyrene measured by the GPC method. In the process of measuring the polystyrene equivalent weight average molecular weight measured by the GPC method, a commonly known analyzer, a detector such as a differential refraction detector, and a column for analysis may be used, and the temperature at which it is normally applied Conditions, solvents, and flow rates can be applied. As a specific example of the measurement conditions, using a Viscotek measurement instrument using a Polymer Laboratories PLgel Mixed C + Mixed D mixed 300 mm length column, the evaluation temperature is 40 ° C., THF (tetrahydrofuran) was used as a solvent, and the flow rate At a rate of 1 mL/min, a sample is prepared at a concentration of 10 mg/10 mL, and then supplied in an amount of 200 μL, and the value of Mw can be obtained using a calibration curve formed using a polystyrene standard. The molecular weight of the polystyrene standard was 371,100 / 96,000 / 21,810 / 4,910 / 1,280 of 5 types.

Hereinafter, the present invention will be described in more detail.

1. Structural Adhesive Composition

According to one embodiment of the invention, an epoxy resin containing a main chain including a branched polyvalent repeating unit represented by the following Chemical Formula 1, and an epoxide group bonded to the terminal of the main chain; epoxy curing agent; And an inorganic filler; structural adhesive composition comprising a may be provided.

[Formula 1]

In Formula 1, A is an n-valent multivalent functional group, n is an integer of 3 or more, X is one of -O-, -S-, or -NR ₁ -, wherein R ₁ in X is hydrogen or carbon number 1 to 20 alkyl groups.

The present inventors have, as in the structural adhesive composition of the embodiment, a main chain including a branched polyvalent repeating unit represented by Formula 1, and an epoxy resin containing an epoxide group bonded to a terminal of the main chain, the epoxy resin As a matrix, it was confirmed through an experiment that it was possible to minimize the change in viscosity or composition due to sedimentation of the inorganic filler by inhibiting the inorganic filler dispersed therein from leaving the matrix, and the invention was completed.

In particular, the main chain including the branched polyvalent repeating unit represented by Formula 1, and the epoxy resin containing the epoxide group bonded to the terminal of the main chain, compared to the epoxy resin containing the repeating unit of the linear structure that has been widely used in the past , it is possible to prevent the separation of the inorganic filler even in the state of the liquid composition before heat curing and to induce it to exist in a dispersed state in the epoxy resin matrix.

Specifically, the structural adhesive composition may include a main chain including a branched polyvalent repeating unit represented by Formula 1, and an epoxy resin containing an epoxide group bonded to a terminal of the main chain.

The epoxy resin may include a branched polyvalent repeating unit represented by Formula 1 as a main chain. The main chain of the epoxy resin contains a large number of branched polyvalent repeating units represented by Chemical Formula 1, so that the main chain of the epoxy resin forms a non-linear, non-linear, network-type bonding chain, even in the state of the liquid composition before heat curing. It can prevent separation and induce it to exist in a dispersed state in the epoxy resin matrix.

In Formula 1, A is an n-valent multivalent functional group, and n may be an integer of 3 or more. More specifically, n may be 3 or more and 10 or less, or 3 or more and 5 or less, or 3 or more and 4 or less.

Specifically, A in Formula 1 may be a functional group represented by Formula 2 below.

[Formula 2]

In Formula 2, L ₁ and L ₂ are the same as or different from each other, and each independently represents one of a direct bond or an alkylene group having 1 to 20 carbon atoms, and Z is an aliphatic chain p is a functional group, or a heterocyclic p is one of the functional groups, and p is an integer of 3 or more.

Specifically, Z may be an aliphatic chain p-valent functional group, the aliphatic chain p-valent functional group may be a p-valent functional group derived from an alkene having 1 to 20 carbon atoms, and p is 3 or more, or 3 or more It is an integer of 10 or less, or 3 or more and 5 or less, or 3 or more and 4 or less.

For a more specific example, in Formula 2, L ₁ is an alkylene group having 1 carbon number, L ₂ is an alkylene group having 2 carbon atoms, Z is a trivalent functional group derived from normal propane having 3 carbon atoms, and p is 3 A functional group represented by the following Chemical Formula 2-1 which is an integer may be mentioned.

[Formula 2-1]

In addition, Z may be a heterocyclic p-valent functional group, the heterocyclic p-valent functional group may be a p-valent functional group derived from a heterocyclic compound having 3 to 20 carbon atoms, and p is 3 or more, or 3 It is an integer of 10 or more, or 3 or more and 5 or less, or 3 or more and 4 or less.

For a more specific example, in Formula 2, L ₁ is an alkylene group having 2 carbon atoms, L ₂ is an alkylene group having 2 carbon atoms, Z is a trivalent functional group derived from isocyanuric acid, and p is and a functional group represented by the following Chemical Formula 2-2, which is an integer of 3.

[Formula 2-2]

In Formula 1, X is one of -O-, -S-, or -NR ₁ -, wherein R ₁ in X is hydrogen or an alkyl group having 1 to 20 carbon atoms. In Chemical Formula 1, X may be an element derived from a hydroxyl group, a thiol group, or an amino group, respectively, and as a result of the hydroxyl group, a thiol group, or an amino group undergoing a ring-opening reaction with an epoxide functional group, as in Formula 1, X It may have a branched polyvalent repeating unit structure in which a functional group and a hydroxyl group represented by .

As such, as the hydroxyl group remains in the branched polyvalent repeating unit represented by Formula 1, the affinity for the metal surface of the epoxy resin including the branched polyvalent repeating unit represented by Formula 1 is improved, and the adhesion to the inorganic filler This is increased, and it can be induced to exist in a dispersed state in the epoxy resin matrix while preventing separation of the inorganic filler even in the state of the liquid composition before thermal curing.

More specifically, specific examples of the branched polyvalent repeating unit represented by Formula 1 may include a functional group represented by the following Formula 1-1 or a functional group represented by the following Formula 1-2.

[Formula 1-1]

[Formula 1-2]

Meanwhile, the main chain of the epoxy resin mediates crosslinking between the branched polyvalent repeating units, and may further include a mediating functional group represented by Formula 3 below. That is, two or more branched polyvalent repeating units included in the main chain of the epoxy resin may be mutually bonded to each other by an intermediate functional group represented by Chemical Formula 3 above.

[Formula 3]

In Formula 3, L ₃ and L ₄ are the same as or different from each other, and each independently represents one of a direct bond or an alkylene group having 1 to 20 carbon atoms, and Ar is an aromatic divalent organic group.

The aromatic divalent organic group may be applied without limitation to a functional group in which hydroxyl groups at both ends are removed from bisphenol compounds widely used in the synthesis of general aromatic epoxy resins. Examples of the aromatic divalent organic group include 2,2-bis(phenylene)propane obtained by removing hydroxyl groups at both terminals from 2,2-bis(4-hydroxyphenyl)propane.

For a more specific example of the functional group represented by Formula 3, in Formula 3, L ₃ and L ₄ are the same as each other, each independently an alkylene group having 1 carbon number, Ar ₁ is 2,2-bis(phenylene) ) a functional group represented by the following Chemical Formula 3-1, which is propane.

[Formula 3-1]

On the other hand, since the epoxy resin contains an epoxy functional group at the terminal, it can react with the epoxy curing agent during the curing process during the manufacturing process of the adhesive film to be described later.

Specifically, the epoxy resin is bonded to the branched polyvalent repeating unit, and may further include a terminal functional group represented by the following formula (4).

[Formula 4]

In Formula 4, L ₅ and L ₆ are the same as or different from each other, and each independently represents one of a direct bond or an alkylene group having 1 to 20 carbon atoms, and Ar is an aromatic divalent organic group.

That is, the epoxy resin is bonded to the branched polyvalent repeating unit, and may contain an epoxide group bonded to the terminal of the main chain through the terminal functional group represented by Chemical Formula 4 above.

For a more specific example of the functional group represented by Formula 4, in Formula 4, L ₅ and L ₆ are the same as each other, each independently an alkylene group having 1 carbon number, and Ar ₂ is 2,2-bis(phenylene) ) a functional group represented by the following Chemical Formula 4-1, which is propane.

[Formula 4-1]

The weight average molecular weight of the epoxy resin may be 2000 g/mol or more and 100000 g/mol or less. Since the epoxy resin includes a main chain including a branched polyvalent repeating unit represented by Formula 1, it may have a higher molecular weight than a polyepoxy compound widely used in the existing adhesive field.

This is because, as will be described later, the epoxy resin contains a combination of a branched compound containing three or more at least one terminal group selected from the group consisting of a hydroxyl group, a thiol group, and an amino group and a polyepoxy compound.

As the weight average molecular weight of the epoxy resin increases to 2000 g/mol or more and 100000 g/mol or less, it is possible to prevent the separation of the inorganic filler even in the liquid composition state before heat curing and to exist in a dispersed state in the epoxy resin matrix. advantageous to induce

On the other hand, when the weight average molecular weight of the epoxy resin is excessively reduced to less than 2000 g/mol, the adhesion to the inorganic filler is significantly reduced due to the decrease in affinity of the epoxy resin to the metal surface, so that the liquid composition state before heat curing There may be a problem in that the viscosity deviation increases due to sedimentation due to the separation of the inorganic filler.

The epoxy equivalent of the epoxy resin may be 200 g/eq or more and 6000 g/eq or less. As the epoxy resin contains an epoxide group bonded to the terminal of the main chain together with the main chain including the branched polyvalent repeating unit represented by Chemical Formula 1, the equivalent weight of the terminal epoxide can be increased, thereby curing the adhesive composition Excellent adhesion properties can be realized by securing high crosslinking density during the process.

On the other hand, when the epoxy equivalent of the epoxy resin is excessively increased to more than 6000 g/eq, adhesive properties may decrease due to a decrease in crosslinking density during the curing process of the adhesive composition.

In addition, when the epoxy equivalent of the epoxy resin is excessively reduced to less than 200 g/eq, storage stability may decrease, such as an increase in viscosity of the adhesive composition due to an unwanted side reaction during long-term storage of the adhesive composition.

The epoxy resin may include a combination of a polyepoxy compound and a branched compound containing three or more one or more terminal groups selected from the group consisting of a hydroxyl group, a thiol group, and an amino group.

The polyepoxy compound is a compound containing two or more epoxide functional groups in the molecular structure, and may be a saturated, unsaturated, cyclic or acyclic, aliphatic, alicyclic, aromatic or heterocyclic polyepoxy compound.

As a specific example, the polyepoxy compound may include polyglycidyl ether. It can be prepared by reacting epichlorohydrin or epibromohydrin with polyphenols in the presence of an alkali. The polyphenol is bisphenol A (bis(4-hydroxyphenyl)-2,2-propane), bisphenol F (bis(4-hydroxyphenyl)methane), bis(4-hydroxyphenyl)-1,1- It may be any one selected from the group consisting of isobutane, 4,4'-dihydroxybenzophenone, bis(4-hydroxyphenyl)-1,1-ethane and 1,5-hydroxynaphthalene, limited thereto it is not going to be

Another example of the polyepoxy compound is a polyglycidyl ester of a polycarboxylic acid, for example glycidol or epichlorohydrin and an aliphatic or aromatic polycarboxylic acid, specifically, oxalic acid, succinic acid, glutaric acid , terephthalic acid or a reaction product of a dimeric fatty acid. Another example of the polyepoxy compound may be an olefinically unsaturated cycloaliphatic compound or one derived from natural oils and fats.

Specific examples of the polyepoxy compound include a bifunctional epoxy compound such as a bisphenol A epoxy compound or a bisphenol F epoxy compound; or a cresol novolak epoxy compound, a phenol novolac epoxy compound, a biphenyl type epoxy compound, a triphenolmethane type epoxy compound, an alkyl-modified triphenolmethane type epoxy compound, a naphthalene type epoxy compound, a dicyclopentadiene type epoxy compound, or a dicyclo and polyfunctional epoxy compounds having three or more functional groups, such as pentadiene-modified phenol-type epoxy compounds, and one or more of them may be mixed and used.

On the other hand, the branched compound containing three or more of one or more terminal groups selected from the group consisting of a hydroxyl group, a thiol group, and an amino group may be represented by the following formula (5).

[Formula 5]

In Formula 5, A is an n-valent multivalent functional group, n is an integer of 3 or more, Y is one of -OH, -SH, or -NHR ₁ , wherein R ₁ in Y is hydrogen, or having 1 to 20 carbon atoms is an alkyl group.

In Formula 5, the contents of A, n, and R ₁ may include all of the contents described above in Formula 1 above.

More specifically, specific examples of the branched compound represented by Formula 5 include a compound represented by the following Formula 5-1 or a compound represented by the following Formula 5-2.

[Formula 5-1]

[Formula 5-2]

The combination of a branched compound containing three or more at least one terminal group selected from the group consisting of a hydroxyl group, a thiol group, and an amino group and a polyepoxy compound is, based on 100 parts by weight of the polyepoxy compound, the hydroxyl group, thiol 10 parts by weight or more and 70 parts by weight or less, or 20 parts by weight or more and 60 parts by weight or less, or 30 parts by weight or more and 50 parts by weight of the branched compound containing three or more at least one terminal group selected from the group consisting of a group and an amino group. It can be combined under parts.

Accordingly, all terminal groups of the branched compound may react with the epoxide group of the polyepoxy compound, and the epoxide group may be included at the end of the main chain of the epoxy resin.

On the other hand, when too little of the branched compound containing three or more one or more terminal groups selected from the group consisting of a hydroxyl group, a thiol group, and an amino group is combined with less than 10 parts by weight, the molecular weight of the epoxy resin is sufficiently increased. it's difficult.

In addition, when the branched compound containing three or more one or more terminal groups selected from the group consisting of a hydroxy group, a thiol group, and an amino group is excessively bonded to more than 70 parts by weight, the branched compound is added to the terminal of the epoxy resin. The end group of the compound may remain, so that the epoxy crosslinking density may decrease due to subsequent curing, and storage stability may decrease such as an increase in viscosity of the adhesive composition due to an unwanted side reaction during long-term storage of the adhesive composition.

Meanwhile, the structural adhesive composition may include an epoxy curing agent. The epoxy curing agent may be dispersed in a matrix containing the epoxy resin in the structural adhesive composition. That is, the epoxy curing agent may be independently dispersed in the adhesive composition with a little or no reaction with the epoxy resin.

The epoxy curing agent may include at least one selected from the group consisting of an amine-based curing agent, an acid anhydride-based curing agent, a phenol-based curing agent, an imidazole-based curing agent, a phosphorus curing agent, and a dicyandiamide-based curing agent, the specific type of which is epoxy Various compounds widely known in the field of resins can be applied without limitation.

The epoxy curing agent may be included in an amount of 0.4 equivalent ratio to 2 equivalent ratio, or 0.8 equivalent ratio to 1.2 equivalent ratio compared to the epoxy equivalent ratio of the epoxy resin. If the content of the epoxy curing agent is less than 0.4 equivalent ratio, the amount of the non-reacting epoxy resin increases during the curing process, and there is a fear that heat resistance may be lowered or a high temperature or long-term process may be required for curing the unreacted resin. In addition, when the content exceeds 2 equivalent ratio, there is a fear that moisture absorption, storage stability, dielectric properties, etc. may increase due to the curing group of the unreacted remaining epoxy curing agent.

The structural adhesive composition may include an inorganic filler. The inorganic filler may be dispersed in a matrix containing the epoxy resin in the structural adhesive composition.

The inorganic filler may include at least one selected from the group consisting of silica, aluminum hydroxide, calcium carbonate, magnesium hydroxide, aluminum oxide, talc, and aluminum nitride.

The inorganic filler as described above may have an average particle diameter of 0.001 μm to 50 μm, or 0.005 μm to 50 μm. If the average particle diameter is less than 0.001 μm, there is a risk that the filler may agglomerate or have poor appearance in the adhesive layer. There is a risk of deterioration.

The inorganic filler may be included in an amount of 10 parts by weight or more and 500 parts by weight or less, or 100 parts by weight or more and 300 parts by weight or less based on 100 parts by weight of the epoxy resin. If the content is less than 10 parts by weight, there is a fear that the effect of improving heat resistance and handleability due to the addition of the filler may be deteriorated, and if it exceeds 500 parts by weight, there is a fear that workability and adhesion to the substrate may be reduced.

On the other hand, the structural adhesive composition may have a viscosity deviation rate of 10% or less, or 1% or more and 10% or less according to the following formula with respect to the structural adhesive composition stored at room temperature for one month.

[Equation]

Viscosity deviation rate (%) = {(absolute value of difference between upper sample viscosity and lower sample viscosity) / (average value of difference between upper sample viscosity and lower sample viscosity)} * 100

In the above formula, the upper sample means a structural adhesive composition taken from an upper region that is 90% or more of the total height of the structural adhesive composition contained in the container, and the lower sample is a lower region that is 10% or less of the total height of the structural adhesive composition contained in the container Structural adhesive composition collected from

When the viscosity deviation rate according to the above formula is excessively increased to more than 10%, the difference in viscosity or composition between the upper and lower parts of the structural adhesive composition occurs as the inorganic filler proceeds to the lower part of the structural adhesive composition during long-term storage. Reliability may be reduced.

In addition, the structural adhesive composition may be used by dissolving or dispersing in an organic solvent as needed. Specific examples of the organic solvent include toluene, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone , N-ethylpyrrolidone, N-vinylpyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, γ-butyrolactone, 3-methoxy-N,N-dimethylpropane Amide, 3-ethoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, 1,3-dimethyl-imidazolidinone, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone , methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether Acetate, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether, ethylene glycol monopropyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monoisopropyl ether acetate, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate; and the like. These may be used alone or may be used in combination.

In addition, the structural adhesive composition may further include a curing accelerator, a surfactant, a moisture absorbent, a rust inhibitor, a toughening agent, or a coupling agent. The curing accelerator may serve to accelerate the curing reaction, and examples thereof include one or more types of imidazole compounds, triphenylphosphine (TPP), or tertiary amines.

Examples of the imidazole compound include 2-methylimidazole (2MZ), 2-ethyl-4-methyl imidazole (2E4MZ), 2-phenyl imidazole (2PZ), 1-cyanoethyl-2-phenyl imidazole (2PZ-CN), 2-undecyl imidazole (C11Z), 2-heptadecyl imidazole (C17Z), and 1-cyanoethyl-2-phenyl imidazole trimetalate (2PZ-CNS). .

In addition, the curing accelerator may be included in an amount of 0.01 parts by weight to 30 parts by weight, or 0.01 parts by weight to 10 parts by weight, or 0.1 parts by weight to 1 part by weight based on 100 parts by weight of the epoxy curing agent. If the content is less than 0.01 parts by weight, there is a fear that heat resistance or adhesion may be lowered, and if it exceeds 30 parts by weight, the curing reaction occurs too rapidly or storage stability is reduced.

Examples of the coupling agent include, but are not limited to, one or more types of a silane-based coupling agent, a titanium-based coupling agent, and an aluminum-based coupling agent.

The coupling agent may be included in an amount of 0.01 parts by weight to 50 parts by weight, or 0.1 parts by weight to 15 parts by weight based on 100 parts by weight of the structural adhesive composition. If the content is less than 0.01 parts by weight, there is a fear that the effect of improving the adhesion may be deteriorated, and if it exceeds 50 parts by weight, there is a possibility that voids may occur or heat resistance may decrease.

2. Structural adhesive film

According to another embodiment of the invention, there may be provided a structural adhesive film comprising a cured product of the structural adhesive composition of the embodiment. The cured product means a material obtained through a curing process of the structural adhesive composition of the embodiment. The content of the structural adhesive composition includes all of the content described above in the one embodiment.

The thickness of the structural adhesive film is not particularly limited, but can be freely adjusted within the range of, for example, 0.01 μm to 1 m. When the thickness of the structural adhesive film increases or decreases by a specific value, physical properties measured in the structural adhesive film may also change by a specific value.

Although the example of the method for manufacturing the structural adhesive film of the other embodiment is not particularly limited, for example, forming a coating film by applying the structural adhesive composition of the one embodiment to the adhesive surface (step 1); A method including a step (step 2) of curing the coating film by heat treatment may be used.

A method of applying the structural adhesive composition of the embodiment to the adhesive surface is not particularly limited, and for example, a method such as screen printing, offset printing, flexographic printing, inkjet, hot roll lamination or lamination press method may be used.

The curing of the coating film by heat treatment may be performed by a heating means such as a hot plate, a hot air circulation furnace, or an infrared furnace, and may be performed at a temperature of 50 °C to 200 °C.

3. Automotive interior and exterior materials

According to another embodiment of the invention, there may be provided an interior and exterior material for a vehicle including the structural adhesive film of the other embodiment. The content of the structural adhesive film includes all of the content described above in the other embodiments.

More specifically, the automobile interior and exterior material includes a bonding body of two or more different structures, and the structural adhesive film is located on the bonding surface of the structure, so that two or more different structures can be bonded through the structural adhesive film. .

The two or more different structures may be of the same material or different materials, and various materials such as metal, alloy, and plastic may be used without limitation.

Specific types of the interior and exterior materials of the vehicle are not particularly limited, but for example, a dash, a cowl, a roof rail, a floor, a body side, and a wheel house. house), and a trunk.

According to the present invention, even during long-term storage, a change in viscosity due to sedimentation of internal components is suppressed to exhibit stable dispersion characteristics and to secure excellent reliability, and a structural adhesive film and automobile interior and exterior materials using the same can be provided. .

The invention is described in more detail in the following examples. However, the following examples only illustrate the present invention, and the content of the present invention is not limited by the following examples.

<Example: Preparation of Structural Adhesive Composition>

Example 1

(1) Preparation of epoxy resin

71.90 g of bisphenol A diglycidyl ether (YD-128, Kukdo Chemical), and 28.10 g of trimethylolpropane tris(3-mercaptopropionate) [Trimethylolpropane tris(3-mercaptopropionate), TMMP], 120 At a reaction temperature of °C, it was reacted for 2 hours to obtain an epoxy resin. As a result, the weight average molecular weight of the polymerized epoxy resin was 50,000 g/mol, and the epoxy equivalent was 473 g/eq.

(2) Preparation of structural adhesive composition

34.2 g of the epoxy resin obtained in (1) of Example 1, 13.67 g of urethane toughener DY965 (Huntsman), 20.50 g of KR818 (Kukdo Chemical, CTBN-modified epoxy), Technicure D-10 (A&C Catalyst, dicyandi) amide) 2.13 g, silane coupling agent A-187 (GE Toshiba Silicone, γ-glycidoxypropyltrimethoxysilane) 0.1 g, curing accelerator Omicure U-52 (CVC Thermoset specialties, substituted urea) 0.48 g, surfactant ( BYK W996, BYK) 0.55 g, calcium carbonate (Omiyacarb 10-CN, Omiya) 16.75 g, desiccant (Uniox, swimming material) 4.10 g, fumed silica (TS720, CABOT) 4.10 g, and rust inhibitor (Halox SW-111, AFCONA) ) 3.42 g was stirred and mixed to prepare a structural adhesive composition.

Example 2

Instead of 28.10 g of trimethylolpropane tris(3-mercaptopropionate) [Trimethylolpropane tris(3-mercaptopropionate), TMMP], tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate (Tris [2-(3-mercaptopropionyloxy)ethyl] isocyanurate), an epoxy resin and a structural adhesive composition were prepared in the same manner as in Example 1, except that 28.10 g was added. As a result, the weight average molecular weight of the polymerized epoxy resin was 45,000 g/mol, and the epoxy equivalent was 381 g/eq.

<Comparative Example: Preparation of Structural Adhesive Composition>

Comparative Example 1

Epoxy resin bisphenol A diglycidyl ether (YD-128, Kukdo Chemical, weight average molecular weight 340.42 g/mol, epoxy equivalent 170 g/eq) 33.84 g, urethane toughener DY965 (Huntsman) 13.54 g, KR818 (Kukdo) Chemical, CTBN-modified epoxy) 20.30 g, epoxy curing agent Technicure D-10 (A&C Catalyst, dicyandiamide) 3.09 g was stirred and mixed to prepare a structural adhesive composition.

Comparative Example 2

Except for using 2.13 g of trimethylolpropane tris(3-mercaptopropionate) [Trimethylolpropane tris(3-mercaptopropionate), TMMP] instead of 2.13 g of Technicure D-10 (A&C Catalyst, dicyandiamide) as an epoxy curing agent A structural adhesive composition was prepared in the same manner as in Comparative Example 1.

<Experimental Example: Measurement of Physical Properties of Structural Adhesive Composition>

For the structural adhesive compositions obtained in Examples and Comparative Examples, physical properties were measured in the following manner, and the results are shown in Table 1.

1. Stability over time

After storing the container containing the structural adhesive composition (solid content: 100%, solvent: none) obtained in the above Examples and Comparative Examples using a constant temperature reflux system at 25±0.2° C. at room temperature for 1 month, the structural use contained in the container The structural adhesive composition collected from the lower region of 10% or less of the total height of the adhesive composition was taken as the lower sample, and the structural adhesive composition collected from the upper region of 90% or more of the total height of the structural adhesive composition contained in the container was collected as the upper sample.

And, for each of the lower sample and the upper sample, the Rheometer MCR302 model (Anton Paar) was used as the rotational viscometer test method of non-Newtonian materials of ASTM D 2196, and brookfield's silicone oil was used as a standard material 5000 Using a number of standard solutions having a viscosity range of cps to 100000 cps, the viscosity was measured with spindle PP25 (diameter 25mm), 2.4 s ^-1 (s: shear rate), and the unit is cps (mPa.s). was used.

Thereafter, the viscosity deviation rate was calculated by the following equation and the stability over time was evaluated under the following criteria.

[Equation]

Viscosity deviation rate (%) = {(absolute value of difference between upper sample viscosity and lower sample viscosity) / (average value of difference between upper sample viscosity and lower sample viscosity)} * 100

○: After storage for 1 month at room temperature, the viscosity deviation rate is less than 10%, resulting in excellent stability over time

X: After storage for one month at room temperature, the viscosity deviation rate exceeds 10%, resulting in poor stability over time

2. Adhesive strength

Structural adhesive compositions obtained in Examples and Comparative Examples were applied to a specimen for measuring adhesive shear strength made of a steel plate and heat-cured at 180° C. for 1 hour. Adhesive shear strength after heat curing was measured through UTM (universal tester).

Experimental Example Measurement Results of Examples and Comparative Examples division Example 1 Example 2 Comparative Example 1 Comparative Example 2 Viscosity deviation rate before storage at room temperature for 1 month One% 0.9% 1.1% One% Viscosity deviation rate after storage at room temperature for 1 month 5% 8% 18% gelled (not measurable) stability over time ○ ○ X X Adhesive shear strength (MPa) 21.74 22.03 20.45 21.28

As shown in Table 1 above, the structural adhesive composition of Examples using the branched epoxy resin as the binder resin has excellent adhesive strength equal to or higher than that of Comparative Examples, and the viscosity deviation rate during long-term storage is significantly reduced compared to Comparative Examples. showed stability over time.

Claims (15)

an epoxy resin containing a main chain including a branched polyvalent repeating unit represented by the following Chemical Formula 1, and an epoxide group bonded to a terminal of the main chain;
epoxy curing agent; and
Inorganic filler; Structural adhesive composition comprising:
[Formula 1]

In Formula 1,
A is an n-valent polyvalent functional group,
n is an integer greater than or equal to 3,
X is one of -O-, -S-, or -NR ₁ -;
In X, R ₁ is hydrogen or an alkyl group having 1 to 20 carbon atoms.
According to claim 1,
A structural adhesive composition in which the epoxy curing agent and the inorganic filler are dispersed in a matrix containing the epoxy resin.
According to claim 1,
With respect to the structural adhesive composition stored for one month at room temperature, the viscosity deviation rate according to the following formula is 10% or less, the structural adhesive composition:
[Equation]
Viscosity deviation (%) = {(absolute value of difference between upper sample viscosity and lower sample viscosity) / (average value of difference between upper sample viscosity and lower sample viscosity)} * 100.
According to claim 1,
A of Formula 1 is a functional group represented by the following Formula 2, Structural adhesive composition:
[Formula 2]

In the above formula (2),
L ₁ and L ₂ are the same as or different from each other, and each independently represents one of a direct bond or an alkylene group having 1 to 20 carbon atoms,
Z is an aliphatic chain p-valent functional group, or a heterocyclic p-valent functional group,
p is an integer greater than or equal to 3;
5. The method of claim 4,
The aliphatic chain p-valent functional group comprises a functional group represented by the following Chemical Formula 2-1, structural adhesive composition:
[Formula 2-1]

.
5. The method of claim 4,
The heterocyclic p-valent functional group comprises a functional group represented by the following formula 2-2, structural adhesive composition:
[Formula 2-2]

.
According to claim 1,
The main chain of the epoxy resin is
Mediating the crosslinking between the branched polyvalent repeating units, and further comprising a mediating functional group represented by the following formula (3), structural adhesive composition:
[Formula 3]

In Formula 3,
L ₃ and L ₄ are the same as or different from each other, and each independently represents one of a direct bond or an alkylene group having 1 to 20 carbon atoms,
Ar is an aromatic divalent organic group.
According to claim 1,
The epoxy resin
Structural adhesive composition, which is bonded to the branched polyvalent repeating unit and further comprises a terminal functional group represented by the following formula (4):
[Formula 4]

In the above formula (4),
L ₅ and L ₆ are the same as or different from each other, and each independently represents one of a direct bond or an alkylene group having 1 to 20 carbon atoms,
Ar is an aromatic divalent organic group.
According to claim 1,
The weight average molecular weight of the epoxy resin is 2000 g/mol or more and 100000 g/mol or less, a structural adhesive composition.
According to claim 1,
The epoxy equivalent of the epoxy resin is 200 g / eq or more and 6000 g / eq or less, the structural adhesive composition.
According to claim 1,
The epoxy resin is a structural adhesive composition comprising a combination of a polyepoxy compound and a branched compound containing three or more at least one terminal group selected from the group consisting of a hydroxyl group, a thiol group, and an amino group.
According to claim 1,
The epoxy curing agent comprises at least one selected from the group consisting of an amine-based curing agent, an acid anhydride-based curing agent, a phenol-based curing agent, an imidazole-based curing agent, a phosphorus curing agent, and a dicyandiamide-based curing agent.
According to claim 1,
The inorganic filler is a structural adhesive composition comprising at least one selected from the group consisting of silica, aluminum hydroxide, calcium carbonate, magnesium hydroxide, aluminum oxide, talc, and aluminum nitride.
A structural adhesive film comprising a cured product of the structural adhesive composition of claim 1 .
An automobile interior and exterior material comprising the structural adhesive film of claim 14 .