KR20210043128A - 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 repeating unit structure is applied as a matrix, and a structural adhesive film and vehicle interior and exterior materials using the same.

Description

Structural adhesive composition, and structural adhesive film using the same, and automotive interior and exterior materials {STRUCTURAL ADHESIVE COMPOSITION, AND STRUCTURAL ADHESIVE FILM, INTERIOR AND EXTERIOR MATERIALS FOR AUTOMOBILE USING THE SAME}

The present invention relates to a structural adhesive composition capable of securing excellent reliability by suppressing a change in viscosity due to sedimentation of internal components even during long-term storage, and to a structural adhesive composition using the same, and to an interior and exterior material for automobiles.

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

In addition, the structural adhesive can not only bond dissimilar materials, but also relieve stress concentration on the bonding surface, block gas and moisture, and improve workability. Due to these advantages, it can be used in a variety of applications ranging from general-purpose industrial fields to high-performance applications in the automobile and aerospace industries.

Structural adhesives generally have a crosslinked structure based on a thermosetting resin, 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 therefore used in a wide range of industries. Epoxy resin is an intermediate (prepolymer) of thermosetting resin, and by reaction with a curing agent, it forms a three-dimensional network structure as a cured product of epoxy resin, thereby exhibiting inherent properties of epoxy.

Structural adhesives are used by adding various inorganic fillers to achieve the purpose of controlling thixotropy, controlling viscosity, improving impact resistance, and removing moisture. However, since these inorganic fillers are not dissolved in the adhesive composition but are present in a dispersed state, when stored for a long period of time, they gradually sink downwards, resulting in differences in viscosity and components between the upper and lower portions of the adhesive composition to satisfy optimal physical properties. There is a difficult limit.

Accordingly, even during long-term storage, there is a need for development of a structural adhesive composition capable of exhibiting stable dispersion characteristics and securing excellent reliability by suppressing changes in viscosity due to sedimentation of internal components.

The present invention is directed to providing a structural adhesive composition that exhibits stable dispersion characteristics by suppressing changes in viscosity due to sedimentation of internal components even during long-term storage and secures excellent reliability.

In addition, the present invention is to provide a structural adhesive film and automobile interior and exterior materials using the above 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 formula (1), and an epoxide group bonded to an end of the main chain; Epoxy curing agent; It provides a structural adhesive composition containing; and an inorganic filler.

[Formula 1]

In Formula 1, A is an n-valent polyvalent functional group, n is an integer of 3 or more, X is one of -O-, -S-, or -NR ₁ -, and R ₁ in X is hydrogen or 1 carbon atom It is an alkyl group of to 20.

In the present specification, there is also provided a structural adhesive film including a cured product of the structural adhesive composition.

In the present specification, a vehicle interior and exterior material including the structural adhesive film is also provided.

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

Unless expressly stated in the specification, terminology is only intended to refer to specific embodiments and is not intended to limit the present invention.

The singular forms used in the present specification also include plural forms unless the phrases clearly indicate the opposite meaning.

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

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, (co)polymer refers to all of a polymer or a copolymer, the polymer refers to a homopolymer composed of a single repeating unit, and the copolymer refers to a composite polymer containing two or more types of repeating units.

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

In the present specification, the term "substitution" means that other functional groups are bonded instead of a hydrogen atom 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 can be substituted, and when two or more are substituted , Two or more substituents may be the same or different from each other.

In the present specification, the term "substituted or unsubstituted" refers to deuterium; Halogen group; Cyano group; Nitro group; Hydroxy group; Carbonyl group; Ester group; Imide group; Amide group; Primary amino group; Carboxyl group; Sulfonic acid group; Sulfonamide group; Phosphine oxide group; Alkoxy group; Aryloxy group; Alkyl thioxy group; Arylthioxy group; Alkyl sulfoxy group; Arylsulfoxy group; Silyl group; Boron group; Alkyl group; Cycloalkyl group; Alkenyl group; Aryl group; Aralkyl group; Aralkenyl group; Alkylaryl group; Alkoxysilylalkyl group; Arylphosphine group; Or it means substituted or unsubstituted with one or more substituents selected from the group consisting of a heterocyclic group containing one or more of N, O, and S atoms, or substituted or unsubstituted with two or more substituents connected among the above-exemplified substituents. . For example, "a substituent to 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 to 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

Means a bond connected to another substituent, and a direct bond means 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 an aromatic.

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

2) 4n+2 electrons must form a planar form 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 alkane and may be linear or branched, and the number of carbon atoms of the linear alkyl group is not particularly limited, but is preferably 1 to 20. Further, the branched chain alkyl group has 3 to 20 carbon atoms. 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, but are not limited thereto. 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, 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 phenyl group, a biphenyl group, or a terphenyl group, but the monocyclic aryl group 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 as described above.

In the present specification, the alkylene group is a divalent functional group derived from alkane, and the description of the above alkyl group 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 which a plurality of hydrogen atoms bonded to an arbitrary compound has been removed, and examples thereof include a divalent functional group, a trivalent functional group, and a tetravalent functional group. For example, a tetravalent functional group derived from cyclobutane refers to a residue in which any 4 hydrogen atoms bonded to cyclobutane have been removed.

In the present specification, a direct bond or a single bond means that no atom or group of atoms exists at the corresponding position and is connected by a bonding line. Specifically, it refers to a case where no separate atom exists in the portion represented by _{L 1} or 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 weight average molecular weight in terms of polystyrene measured by the GPC method, a commonly known analysis device, a detector such as a Refractive Index Detector, and a column for analysis can be used. Conditions, solvents, and flow rates can be applied. For a specific example of the measurement conditions, using a Viscotek measuring instrument using a Polymer Laboratories PLgel Mixed C + Mixed D mixed 300 mm length column, the evaluation temperature was 40 °C, and THF (tetrahydrofuran) was used as a solvent, and the flow rate At a rate of 1 mL/min, the 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 calculated 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.

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

1. Structural adhesive composition

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

[Formula 1]

In Formula 1, A is an n-valent polyvalent functional group, n is an integer of 3 or more, X is one of -O-, -S-, or -NR ₁ -, and R ₁ in X is hydrogen or 1 carbon atom It is an alkyl group of to 20.

As the present inventors contain an epoxy resin containing a main chain including a branched polyvalent repeating unit represented by Chemical Formula 1, and an epoxide group bonded to the end of the main chain, as in the structural adhesive composition of the embodiment, the epoxy resin As a matrix, it was confirmed through an experiment that the change in viscosity or composition change due to the sedimentation of the inorganic filler can be minimized by suppressing the separation of the inorganic filler dispersed therein to the outside of the matrix, and the invention was completed.

In particular, the epoxy resin containing the main chain including the branched polyvalent repeating unit represented by Chemical Formula 1, and the epoxide group bonded to the end of the main chain, compared to the epoxy resin containing the repeating unit of a linear structure that has been widely used in the past. , Even in the state of the liquid composition before thermal curing, it is possible to prevent the separation of the inorganic filler and 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 an end 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 Formula 1, so that the main chain of the epoxy resin forms a non-linear mesh-shaped binding chain, and the inorganic filler It can prevent separation and induce it to exist in a dispersed state within the epoxy resin matrix.

In Formula 1, A is an n-valent polyvalent 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 a direct bond or one of 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 It is one of the functional groups, and p is an integer of 3 or more.

Specifically, Z may be an aliphatic chain type p is a functional group, the aliphatic chain type p may be a functional group, 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 Functional groups represented by the following general formula 2-1 which are integers are mentioned.

[Formula 2-1]

In addition, Z may be a heterocyclic p may be a functional group, and the heterocyclic p may be a p-valent functional group derived from a heterocyclic compound having 3 to 20 carbon atoms, and p may be 3 or more, or 3 It is an integer of 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 A functional group represented by the following general formula 2-2 which is an integer of 3 may be mentioned.

[Formula 2-2]

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

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

More specifically, specific examples of the branched polyvalent repeating unit represented by Formula 1 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 bonded to each other by a mediating functional group represented by Chemical Formula 3.

[Formula 3]

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

The aromatic divalent organic group can be applied without limitation, without limitation, in bisphenol compounds widely used for synthesis of general aromatic epoxy resins. Examples of the aromatic divalent organic group include 2,2-bis (phenylene) propane in which the hydroxy groups at both ends are removed 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, and Ar ₁ is 2,2-bis(phenylene ) A functional group represented by the following formula 3-1, which is propane.

[Chemical Formula 3-1]

Meanwhile, since the epoxy resin contains an epoxy functional group at the terminal, it may react with the epoxy curing agent during the curing process during the manufacturing process of the adhesive film described below.

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 a direct bond or one of 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 Formula 4 above.

For a more specific example of the functional group represented by Chemical Formula 4, in Chemical Formula 4, L ₅ and L ₆ are the same as each other, and are each independently an alkylene group having 1 carbon number, and Ar ₂ is 2,2-bis(phenylene ) A functional group represented by the following 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 Chemical Formula 1, it may have a higher molecular weight compared to the polyepoxy compound which has been widely used in the existing adhesive field.

This is because, as described later, the epoxy resin contains a combination of a polyepoxy compound and a branched compound containing three or more terminal groups selected from the group consisting of a hydroxy group, a thiol group, and an amino group.

As the weight average molecular weight of the epoxy resin is increased 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 state of the liquid composition before heat curing and to exist in a dispersed state in the epoxy resin matrix. It is 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 the affinity of the epoxy resin to the metal surface, resulting in a liquid composition state prior to thermal 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 end of the main chain together with the main chain including the branched polyvalent repeating unit represented by Chemical Formula 1, the equivalent of the terminal epoxide can be increased, thereby curing the adhesive composition. During the process, a high crosslinking density can be secured to realize excellent adhesion properties.

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 unwanted side reactions 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 terminal groups selected from the group consisting of a hydroxy group, a thiol group, and an amino group.

The polyepoxy compound is a compound containing two or more epoxide functional groups in a 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 a polyphenol 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, and is limited thereto. It does not become.

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, for example, oxalic acid, succinic acid, glutaric acid. , It may be a reaction product of terephthalic acid or a dimer 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 cresol novolac epoxy compound, phenol novolac epoxy compound, biphenyl type epoxy compound, triphenolmethane type epoxy compound, alkyl modified triphenolmethane type epoxy compound, naphthalene type epoxy compound, dicyclopentadiene type epoxy compound or dicyclo And polyfunctional epoxy compounds having three or more functional groups, such as a pentadiene-modified phenol-type epoxy compound, and one or more of them may be used in combination.

Meanwhile, a branched compound containing three or more terminal groups selected from the group consisting of a hydroxy 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 polyvalent functional group, n is an integer of 3 or more, Y is one of -OH, -SH, or -NHR ₁ , and R ₁ in Y is hydrogen, or having 1 to 20 carbon atoms. It is an alkyl group.

In Chemical Formula 5, the information on A, n, and R ₁ may include all the details described in Chemical Formula 1.

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.

[Chemical Formula 5-1]

[Chemical Formula 5-2]

The combination of a branched compound and a polyepoxy compound containing 3 or more terminal groups selected from the group consisting of a hydroxy group, a thiol group, and an amino group is, based on 100 parts by weight of the polyepoxy compound, the hydroxy group, the 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 a branched compound containing 3 or more terminal groups selected from the group consisting of groups and amino groups It can be combined with less than a part.

Accordingly, all of the 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 the branched compound containing 3 or more terminal groups selected from the group consisting of the hydroxy group, the thiol group, and the amino group is bonded too little to less than 10 parts by weight, the molecular weight of the epoxy resin is sufficiently increased. It is difficult.

In addition, when an excessive amount of a branched compound containing 3 or more terminal groups selected from the group consisting of a hydroxy group, a thiol group, and an amino group is excessively bonded in excess of 70 parts by weight, the branched compound is formed at the end of the epoxy resin. Since the terminal groups of the compound remain, the epoxy crosslinking density may decrease due to subsequent curing, and storage stability may decrease, such as an increase in the viscosity of the adhesive composition due to unwanted side reactions 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 while making a very partial reaction with the epoxy resin or not reacting at all.

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, and the specific type is epoxy Various compounds widely known in the resin field can be applied without limitation.

The epoxy curing agent may be included in an amount of 0.4 to 2 equivalents, or 0.8 to 1.2 equivalents, relative to the epoxy equivalent of the epoxy resin. If the content of the epoxy curing agent is less than 0.4 equivalent ratio, there is a concern that the amount of the less reactive epoxy resin increases during the curing process, resulting in a decrease in heat resistance or a high temperature or a long time process for curing the unreacted resin. In addition, when the content exceeds 2 equivalents, there is a concern that moisture absorption, storage stability, dielectric properties, and the like may increase due to the curing group of the epoxy curing agent remaining unreacted.

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 possibility that the filler may be aggregated or poor appearance in the adhesive layer, and if it exceeds 50 µm, the protrusion of the filler to the surface of the adhesion layer, damage to the chip during thermal compression, or the effect of improving adhesion 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 concern that the heat resistance and handling property improvement effect due to the addition of the filler may be deteriorated, and if it exceeds 500 parts by weight, workability and adhesion to the substrate may be lowered.

Meanwhile, the structural adhesive composition may have a viscosity variation rate of 10% or less, or 1% or more and 10% or less, according to the following equation, with respect to the structural adhesive composition stored at room temperature for one month.

[Equation]

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

In the above equation, the upper sample refers to a structural adhesive composition taken from an upper area 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 area that is 10% or less of the total height of the structural adhesive composition contained in the container. It means the structural adhesive composition taken from.

If the viscosity deviation rate according to the above equation is excessively increased to more than 10%, the difference in viscosity or composition between the upper and lower portions of the structural adhesive composition occurs as the sedimentation of the inorganic filler under the structural adhesive composition during long-term storage occurs. Reliability may decrease.

In addition, the structural adhesive composition may be used by dissolving or dispersing it in an organic solvent, if necessary. 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 And glycol monobutyl ether acetate. 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 desiccant, a rust inhibitor, a toughening agent, or a coupling agent. The curing accelerator may play a role of accelerating 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 content. If the content is less than 0.01 parts by weight, heat resistance or adhesive strength may be lowered, and if it exceeds 30 parts by weight, a curing reaction occurs too rapidly or storage stability is deteriorated.

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 concern that the effect of improving adhesion may be deteriorated, and if it exceeds 50 parts by weight, voids may occur or heat resistance may be lowered.

2. Structural adhesive film

According to another embodiment of the invention, a structural adhesive film including a cured product of the structural adhesive composition of the embodiment may be provided. The cured product means a material obtained through the curing process of the structural adhesive composition of the embodiment. The contents of the structural adhesive composition include all the contents described above in the embodiment.

Although the thickness of the structural adhesive film is not largely limited, for example, it can be freely adjusted within the range of 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 predetermined value.

The example of the method of manufacturing the structural adhesive film of the other embodiment is not largely limited, for example, forming a coating film by applying the structural adhesive composition of the embodiment to the adhesive surface (step 1); A method including the step of curing the coating film by heat treatment (step 2) 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, flexo printing, inkjet, hot roll lamination or lamination press method may be used.

The step of curing 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. Automobile interior and exterior materials

According to another embodiment of the present invention, a vehicle interior and exterior material including the structural adhesive film of the other embodiment may be provided. The contents of the structural adhesive film include all the contents described above in the other embodiments.

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

The two or more different structures may be the same material or different materials, and various materials such as metals, alloys, and plastics may be used without limitation.

Although the specific types of the interior and exterior materials of the vehicle are not largely limited, for example, a dash, a cowl, a roof rail, a floor, a body side, and a wheel house. house), trunk, and the like.

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

The invention will be described in more detail in the following examples. However, the following examples are merely illustrative of the present invention, and the contents of the present invention are not limited by the following examples.

<Example: Preparation of structural adhesive composition>

Example 1

(1) Preparation of epoxy resin

Bisphenol A diglycidyl ether (YD-128, Kukdo Chemical) 71.90 g, and trimethylolpropane tris (3-mercaptopropionate) [Trimethylolpropane tris(3-mercaptopropionate), TMMP] 28.10 g were added thereto, and 120 glycidyl ether (YD-128, Kukdo Chemical) was added thereto. 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

Epoxy resin 34.2 g obtained in (1) of Example 1, urethane toughening agent DY965 (Huntzman) 13.67 g, KR818 (Kukdo Chemical, CTBN modified epoxy) 20.50 g, epoxy curing agent Technicure D-10 (A&C Catalyst, Dicyandi Amide) 2.13 g, silane coupling agent A-187 (GE Toshiba Silicon, γ-glycidoxypropyltrimethoxysilane) 0.1 g, curing accelerator Omicure U-52 (CVC Thermoset specialties, substituted urea) 0.48 g, surfactant ( BYK W996, BYK) 0.55g, calcium carbonate (Omiyacarb 10-CN, Omiya) 16.75g, desiccant (Uniox, Yooyoung Material) 4.10g, Fumed silica (TS720, CABOT) 4.10g, 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 An epoxy resin and a structural adhesive composition were prepared in the same manner as in Example 1, except that 28.10 g of [2-(3-mercaptopropionyloxy)ethyl] isocyanurate) 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

Bisphenol A diglycidyl ether as an epoxy resin (YD-128, Kukdo Chemical, weight average molecular weight 340.42 g/mol, epoxy equivalent 170 g/eq) 33.84 g, urethane toughening agent 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 by the following method, 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 for 1 month at room temperature using a constant temperature reflux system at 25±0.2°C, the structural use contained in the container The structural adhesive composition collected from the lower area of 10% or less of the total height of the adhesive composition was sampled as a lower sample, and the structural adhesive composition collected from the upper area of 90% or more of the total height of the structural adhesive composition contained in the container was collected as an upper sample.

And, for each of the lower and upper samples, a Rheometer MCR302 model (Anton Paar) was used as a rotation viscometer test method for a non-Newton material according to ASTM D 2196, and a silicone oil of brookfield was used as a standard material. 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 the difference between the viscosity of the upper sample and the viscosity of the lower sample) / (the average value of the difference between the viscosity of the upper sample and the viscosity of the lower sample)} * 100

○: Excellent stability over time as the viscosity deviation rate is less than 10% after storage at room temperature for 1 month

X: After storage at room temperature for 1 month, the viscosity deviation rate exceeds 10%, resulting in poor stability over time.

2. Adhesion strength

The structural adhesive composition obtained in the above Examples and Comparative Examples was applied to a specimen for measuring the adhesive shear strength of a steel plate, followed by heat curing at 180° C. for 1 hour. After heating and curing, the adhesive shear strength 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 1 month storage at room temperature 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, the structural adhesive composition of the Example using the branch-type epoxy resin as the binder resin has excellent adhesive strength equal to or higher than that of the Comparative Example, while the viscosity deviation ratio during long-term storage was significantly reduced compared to the Comparative Example. It showed stability over time.

Claims (15)

An epoxy resin containing a main chain including a branched polyvalent repeating unit represented by the following formula (1) and an epoxide group bonded to the terminal of the main chain;
Epoxy curing agent; And
Inorganic filler; containing, structural adhesive composition:
[Formula 1]

In Chemical Formula 1,
A is an n-valent polyvalent functional group,
n is an integer of 3 or more,
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.
The method of claim 1,
The epoxy curing agent and the inorganic filler are dispersed in the matrix containing the epoxy resin, structural adhesive composition.
The method of claim 1,
With respect to the structural adhesive composition stored at room temperature for one month, the viscosity deviation rate according to the following equation is 10% or less, structural adhesive composition:
[Equation]
Viscosity deviation rate (%) = {(absolute value of the difference between the viscosity of the upper sample and the viscosity of the lower sample) / (the average value of the difference between the viscosity of the upper sample and the viscosity of the lower sample)} * 100.
The method of claim 1,
A in Formula 1 is a functional group represented by the following Formula 2, structural adhesive composition:
[Formula 2]

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

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

.
The method of claim 1,
The main chain of the epoxy resin is
The structural adhesive composition, which mediates the crosslinking between the branched polyvalent repeating units, and further comprises a mediating functional group represented by the following Formula 3:
[Formula 3]

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

In Chemical Formula 4,
L ₅ and L ₆ are the same as or different from each other, and each independently a direct bond or one of an alkylene group having 1 to 20 carbon atoms,
Ar is an aromatic divalent organic group.
The method of claim 1,
The weight average molecular weight of the epoxy resin is 2000 g / mol or more and 100000 g / mol or less, structural adhesive composition.
The method of claim 1,
The epoxy equivalent of the epoxy resin is 200 g / eq or more and 6000 g / eq or less, structural adhesive composition.
The method of claim 1,
The epoxy resin comprises a combination of a polyepoxy compound and a branched compound containing three or more terminal groups selected from the group consisting of a hydroxy group, a thiol group, and an amino group.
The method of 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.
The method of claim 1,
The inorganic filler comprises 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.
Automobile interior and exterior materials comprising the structural adhesive film of claim 14.