KR101994355B1 - Structural epoxy adhesives composition - Google Patents

Abstract

(상기 화학식 1에서, R은 선형 또는 분지형의 탄소수 20 내지 50의 알킬렌기, 또는 선형 또는 분지형의 탄소수 20 내지 50의 알케닐렌기이며; Ar₁ 내지 Ar₄는 서로 독립적으로 탄소수 6 내지 30의 아릴렌기이며; a 및 b는 서로 독립적으로 1 내지 3의 정수이다.)The present invention relates to a structural epoxy adhesive composition comprising a fatty acid modified epoxy resin, a fatty acid unmodified epoxy resin, a polyurethane toughening agent and a core shell toughening agent satisfying the following formula (1).
[Chemical Formula 1]

(Wherein R is a linear or branched alkylene group having 20 to 50 carbon atoms or a linear or branched alkenylene group having 20 to 50 carbon atoms, Ar ₁ to Ar ₄ are each independently a group having 6 to 30 carbon atoms A and b are independently of each other an integer of 1 to 3.)

Description

TECHNICAL FIELD The present invention relates to a structural epoxy adhesive composition,

TECHNICAL FIELD The present invention relates to a structural epoxy adhesive composition, and more particularly, to a structural epoxy adhesive composition having excellent coating properties and heat resistance characteristics and excellent T-peel strength.

Epoxy resins are widely used in the adhesive, molding and coating industries due to their high mechanical properties and thermal and insulation properties. Despite the good mechanical properties of such epoxy resins, they are pointed out as a major disadvantage in industrial applications where high resistance to impacts is required due to brittle brittle properties such as glass.

In order to overcome this, recently, a rubber-based toughening agent is added to the epoxy resin or the rubber component is reacted and modified with the epoxy resin to improve the brittleness of the epoxy resin, but the effect is still insignificant. At this time, carboxyl-terminated butadiene acrylonitrile rubber (CTBN) is typically used as a rubber-based reinforcement agent, and an epoxy-modified reinforcing material is also widely used by reacting epoxy resin with CTBN.

Meanwhile, Thiodiphenyl epoxy resin (TDPE) is added to the adhesive composition in order to improve the thermal property of the adhesive. However, TDPE has a disadvantage in that the coating property is poor, and TDPE is added to the adhesive composition There is a problem that the thermal property is improved but the adhesive property is lowered.

Accordingly, there is a need to develop a structural adhesive composition that is excellent in heat resistance and coating properties and also has excellent adhesive properties.

A prior art related to this is Korean Patent Laid-Open No. 10-2010-0075961.

Korean Patent Publication No. 10-2010-0075961 (July 5, 2010)

It is an object of the present invention to provide a structural epoxy adhesive composition excellent in coating properties and heat resistance characteristics and excellent in T-peel strength.

One aspect of the present invention for achieving the above object is to provide a structural epoxy adhesive composition comprising a fatty acid-modified epoxy resin, a fatty acid-unmodified epoxy resin, a polyurethane-based toughening agent and a core- .

[Chemical Formula 1]

(Wherein R is a linear or branched alkylene group having 20 to 50 carbon atoms or a linear or branched alkenylene group having 20 to 50 carbon atoms, Ar ₁ to Ar ₄ are each independently a group having 6 to 30 carbon atoms A and b are independently of each other an integer of 1 to 3.)

In the above embodiment, more preferably, the fatty acid-modified epoxy resin may satisfy the following formula (2).

(2)

(Wherein R is a linear or branched alkylene group having 20 to 50 carbon atoms or a linear or branched alkenylene group having 20 to 50 carbon atoms, Ar ₁ to Ar ₄ are each independently a group having 6 to 30 carbon atoms Lt; / RTI >

In this embodiment, more preferably, R in formula (1) has a branched structure containing at least one branched chain or an alkenylene group having at least one unsaturated double bond And may have a mixed structure.

In the above embodiment, the fatty acid-modified epoxy resin may be a liquid resin.

In one embodiment, the structural epoxy adhesive composition comprises 10 to 50 parts by weight of a polyurethane-based toughening agent and 20 to 60 parts by weight of a core-shell toughening agent, based on 100 parts by weight of a fatty acid-modified epoxy resin and a fatty acid- Wherein the weight ratio of the fatty acid-modified epoxy resin: fatty acid-unmodified epoxy resin may be 1 to 30: 99 to 70.

In the above embodiment, the structural epoxy adhesive composition may satisfy the following relational expression (1).

[Relation 1]

1.2 <S ₁ / S ₀ ≤ 2

Wherein S ₁ is the T-peel strength (N / 25 mm) of the structural epoxy adhesive composition comprising the fatty acid-modified epoxy resin, S ₀ is the structural epoxy adhesive composition comprising the fatty acid-modified epoxy resin (N / 25 mm) of the structural epoxy adhesive composition except for only the epoxy-modified fatty acid.

The structural epoxy adhesive composition according to the present invention can improve a coating property while maintaining a high thermal stability by including a liquid fatty acid modified epoxy resin modified with a fatty acid in a solid state sulfur-containing aromatic epoxy resin having poor application properties , Which has an advantage that it can have excellent T-peel strength.

Particularly, it is possible to further improve the T-peel strength by using a fatty acid-modified epoxy resin with improved thermal properties and coating properties, a polyurethane toughening agent and a core shell toughening agent, There are advantages.

Fig. 1 shows the T-peel strength measurement results of the epoxy epoxy composition prepared according to Examples 1 to 3 and Comparative Example 1. Fig.
Fig. 2 shows the result of superposition shear strength measurement of the epoxy epoxy composition prepared according to Examples 1 to 3 and Comparative Example 1. Fig.

The structural epoxy adhesive composition according to the present invention will now be described in detail with reference to the accompanying drawings. The following drawings are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the following drawings, but may be embodied in other forms, and the following drawings may be exaggerated in order to clarify the spirit of the present invention. Also, throughout the specification, like reference numerals designate like elements.

Hereinafter, the technical and scientific terms used herein will be understood by those skilled in the art without departing from the scope of the present invention. Descriptions of known functions and configurations that may be unnecessarily blurred are omitted.

Thiodiphenyl epoxy resin (TDPE) has higher thermal properties than diglycidylether of bisphenol A (DGEBA) by introducing sulfur (S) in the main chain, but has poor application properties There is a problem in that when the TDPE is added to the adhesive composition, the thermal properties are improved but the adhesive property is greatly deteriorated.

Accordingly, the present inventors have repeatedly made efforts to improve the coating properties while maintaining the thermal properties of TDPE. Thus, the present inventors have completed a structural epoxy adhesive composition capable of being used as a structural adhesive with excellent T-peel strength while satisfying the above object.

Specifically, the structural epoxy adhesive composition according to an embodiment of the present invention may include a fatty acid-modified epoxy resin, a fatty acid-unmodified epoxy resin, a polyurethane-based toughening agent, and a core-shell toughening agent.

[Chemical Formula 1]

(Wherein R is a linear or branched alkylene group having 20 to 50 carbon atoms or a linear or branched alkenylene group having 20 to 50 carbon atoms, Ar ₁ to Ar ₄ are each independently a group having 6 to 30 carbon atoms A and b are independently of each other an integer of 1 to 3.)

As described above, the structural epoxy adhesive composition according to the present invention includes a liquid fatty acid-modified epoxy resin modified with a fatty acid, which is a solid sulfur-containing aromatic epoxy resin having poor application properties, thereby improving the coating property while maintaining high thermal stability And it has an advantage that it can have an excellent T-peel strength.

Particularly, it is possible to further improve the T-peel strength by using a fatty acid-modified epoxy resin with improved thermal properties and coating properties, a polyurethane toughening agent and a core shell toughening agent, There are advantages.

First, in the structural epoxy adhesive composition according to an embodiment of the present invention, the most important component may be a fatty acid-modified epoxy resin, and when it is not added, the T-peel strength may be greatly reduced.

Preferably, the fatty acid-modified epoxy resin may satisfy the following formula (2), and by containing a smaller amount of sulfur (S), the coating properties can be greatly improved while maintaining excellent heat resistance.

(2)

(Wherein R is a linear or branched alkylene group having 20 to 50 carbon atoms or a linear or branched alkenylene group having 20 to 50 carbon atoms, Ar ₁ to Ar ₄ are each independently a group having 6 to 30 carbon atoms Lt; / RTI &gt;

The arylene group is an organic radical derived from aromatic hydrocarbons by removal of two hydrogens and is a single or fused ring system containing 1 to 7, preferably 1 or 3, ring atoms in each ring And includes a form in which a plurality of arylene are connected by a single bond. Specific examples of the arylene group include aromatic groups such as phenylene, naphthylene, biphenylene, triphenylene, fluorene, phenanthrene, anthracene, and pyrene.

More preferably, the structural epoxy composition according to one embodiment of the present invention may include an epoxy resin modified using a fatty acid having a branched structure, an unsaturated structure, or a mixed structure thereof in order to secure more excellent application properties have. As such, when the epoxy resin is modified with a fatty acid having a branched structure, an unsaturated structure, or a mixed structure thereof, the fatty acid-modified epoxy resin has a liquid phase so that the structural epoxy composition has excellent coating properties, This can also significantly increase the T-peel strength.

As a specific example, in the fatty acid-modified epoxy resin, R in the formula (1) may have a branched structure including at least one branched chain, more specifically, one to four, more preferably two And may have a branched structure including four side chains. As the number of side chains in the fatty acid-modified epoxy resin increases, the fatty acid-modified epoxy resin may become liquid phase more easily and the effect of improving the coating property may be excellent.

In addition, R in the above formula (1) may be an alkenylene group containing at least one unsaturated double bond, more specifically, an alkenyl group containing one to fifteen, more preferably two to eight unsaturated double bonds Lt; / RTI &gt; As the number of unsaturated double bond increases, the epoxy resin modified with fatty acid can be more easily formed into a liquid phase, and the effect of improving the application property can be excellent.

As mentioned above, the fatty acid-modified epoxy resin according to an embodiment of the present invention may be a liquid resin. Unsaturated fatty acid-modified epoxy resin to which sulfur (S) is introduced in the main chain exhibits high thermal properties, but exhibits a solid phase which does not dissolve well in the structural epoxy adhesive composition, Accordingly, the epoxy resin modified with a fatty acid can be easily mixed into a structural epoxy adhesive composition as a liquid phase, and thus the coating properties are greatly improved. In addition, since the coating property is excellent, when the adhesive is used as a structural adhesive, the adhesive property of the entire bonding portion is excellent and the T-peel strength can be remarkably improved.

As a specific example, the fatty acid-modified epoxy resin having a liquid phase may have a viscosity of 10,000 to 8,000,000 cP at 25 ° C, preferably 20,000 to 100,000 cP at 25 ° C, more preferably 25 RTI ID = 0.0 &gt; 25 C &lt; / RTI &gt; to 50,000 cP. Within this range, the effect of improving the coating properties of the structural epoxy adhesive composition may be particularly good, but this is only a non-limiting example and is not limited by the above numerical range.

In one embodiment of the present invention, the fatty acid unmodified epoxy resin refers to a pure epoxy resin which is not modified with a fatty acid, unlike the epoxy resin of the formula (1) or (2) It can be used without limitation. Specifically, for example, the fatty acid-unmodified epoxy resin may be an aliphatic compound, an alicyclic compound, an aromatic compound, or a heterocyclic compound, but may contain an aromatic group in the molecule in order to secure a higher adhesive force. More specifically, for example, the fatty acid unmodified epoxy resin usable in the present invention may be any one or more of bisphenol A type, bisphenol E type, bisphenol F type, bisphenol M type, bisphenol S type and bisphenol H type, Epoxy resin, glycidyl ether-based epoxy resin, glycidylamine-based epoxy resin, phenol novolak-type epoxy resin, and cresol novolak-type epoxy resin, and the like, preferably T - In view of maximizing the peel strength, the fatty acid-unmodified epoxy resin may be at least one selected from bisphenol A epoxy resin and bisphenol F epoxy resin.

In addition, the fatty acid-unmodified epoxy resin according to an embodiment of the present invention may contain at least two epoxy functional groups per molecule or repeating unit, specifically epoxy equivalents of 100 to 300 g / eq, 150 to 250 g / eq, and more preferably 170 to 210 g / eq. When applied to structural epoxy adhesive compositions in such a range, the cured density increases and the cured product can have excellent mechanical strength and chemical resistance. However, this is only an example of the preferred epoxy equivalent of the fatty acid-unmodified epoxy resin, and the present invention is not necessarily limited thereto.

In one example of the present invention, the polyurethane-based toughening agent may be used to increase impact strength and T-peel strength in application to a structural epoxy adhesive composition, and is not limited as long as it is commonly used in the related art In order to effectively improve the impact strength and T-peel strength, specifically, for example, a polyol compound having a molecular weight of 1,000 to 3,000 g / mol and a polyisocyanate compound are reacted using a tin catalyst, And capped with the same phenolic capping agent. Here, the polyol compound may be specifically a polyether diol, and the polyisocyanate compound may be an alicyclic diisocyanate compound such as isophorone diisocyanate.

In one embodiment of the present invention, the core-shell type toughening agent is used to further increase the elasticity and T-peel strength. The core-shell type toughening agent is not limited as long as it is usually used in the field. For example, acrylic rubber, silicone rubber, urethane rubber, styrene-butadiene rubber, and butadiene rubber can be selected. It is not necessary that the core portion and the shell portion are made of the same kind of rubber. The core portion may be a silicone rubber, the shell portion may be an acrylic rubber or the core portion butadiene rubber, and the shell portion may be made of acrylic rubber. In production, it can be produced by well-known methods such as emulsion polymerization, suspension polymerization, micro suspension polymerization and the like. The core-shell type toughening agent is preferably spherical or substantially spherical in that it does not agglomerate well. The average particle diameter may be 0.01 to 20 탆, preferably 0.1 to 5 탆, although not limited thereto. Preferably, from the viewpoint of effectively improving the elasticity and T-peel strength, the core-shell type toughening agent may be such that 20 to 30% by weight of core shell particles having a polybutadiene core are dispersed in bisphenol A-based epoxy resin.

On the other hand, in order to ensure excellent T-peel strength of the structural epoxy adhesive composition, it is preferable to appropriately adjust the content of each component. Specifically, for example, the structural epoxy adhesive composition comprises 10 to 50 parts by weight of a polyurethane-based toughening agent and 20 to 60 parts by weight of a core-shell type toughening agent, based on 100 parts by weight of a fatty acid-modified epoxy resin and a fatty acid- And more preferably 25 to 40 parts by weight of a polyurethane-based toughening agent and 30 to 50 parts by weight of a core-shell type toughening agent, based on 100 parts by weight of a fatty acid-modified epoxy resin and a fatty acid-unmodified epoxy resin.

At this time, the content of the fatty acid-modified epoxy resin contained in the fatty acid-modified epoxy resin and the fatty acid-unmodified epoxy resin is particularly important. If the content of the fatty acid-modified epoxy resin is too small, the effect of improving the T-peel strength may be insignificant. If the content of the fatty acid-modified epoxy resin is too large, the T-peel strength may be lowered. Preferably, the weight ratio of the fatty acid-modified epoxy resin: fatty acid-unmodified epoxy resin may be 1 to 30:99 to 70, more preferably the weight ratio of the fatty acid-modified epoxy resin: fatty acid unmodified epoxy resin is 5 To 20: 95 to 80, and particularly preferably, the weight ratio of the fatty acid-modified epoxy resin: fatty acid-unmodified epoxy resin may be 10: 15 to 90: 85. The T-peel strength maximized in this range can be secured.

Specifically, the structural epoxy adhesive composition according to one example of the present invention may have a T-peel strength satisfying the following relational expression 1, and specifically, for example, 250 to 350 N / 25 mm, preferably 270 to 350 And may have a T-peel strength of N / 25 mm. As described above, the T-peel strength is very excellent and can be utilized as a structural adhesive.

[Relation 1]

1.2 <S ₁ / S ₀ ≤ 2

Wherein S ₁ is the T-peel strength (N / 25 mm) of the structural epoxy adhesive composition comprising the fatty acid-modified epoxy resin, S ₀ is the structural epoxy adhesive composition comprising the fatty acid-modified epoxy resin (N / 25 mm) of the structural epoxy adhesive composition except for only the epoxy-modified fatty acid.

Meanwhile, the structural epoxy adhesive composition according to an example of the present invention may further include a curing agent. The curing agent is used for curing the structural epoxy adhesive composition and can be used without limitation as long as it is known in the art. In order to prepare a one-part adhesive, a latent curing agent which is solid at room temperature and can react with the epoxy group It is good to do.

Specifically, for example, an anhydride-based curing agent, a phenol-based curing agent, a dicyandiamide-based curing agent, an amine-based curing agent, and the like can be used as the curing agent. These may be used alone or in combination of two or more. An amine-based curing agent can be preferably used in view of suitability for a one-part adhesive composition.

Examples of the acid anhydride-based curing agent include phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylnadonic acid anhydride, glutaric acid anhydride, Hydroxycarboxylic anhydride, hydrophthalic anhydride, and methyltetrahydrophthalic anhydride. More specifically, it may be, for example, methylhexahydrophthalic acid, but is not limited thereto.

Examples of the phenolic curing agent include phenol resins such as formaldehyde condensation type resol-type phenol resin, non formaldehyde condensation type phenol resin, novolac-type phenol resin, novolac-type phenol formaldehyde resin and polyhydroxystyrene resin; Resol type phenol resins such as aniline-modified resole resin and melamine-modified resol resin; Novolac-type phenolic resins such as phenol novolac resins, cresol novolac resins, tert-butylphenol novolac resins, nonylphenol novolak resins and naphthol novolak resins; Special phenolic resins such as dicyclopentadiene-modified phenolic resins, terpene-modified phenolic resins, triphenolmethane-type resins, phenol aralkyl resins having phenylene skeleton or diphenylene skeleton, and naphthol aralkyl resins; And polyhydroxystyrene resins such as poly (p-hydroxystyrene).

Examples of the amine curing agent include aliphatic amines, aliphatic polyamines, aromatic polyamines, polyamide polyamines, modified aromatic amines, and mixtures thereof. The aliphatic amines include dicyandiamine, diethylenetriamine, triethylenetetraamine, di Aminopropylamine, ethylaminopropylamine, mentantiamine, N-aminoethylpiperazine, m-xylylenediamine and isophorone diamine, and the modified aromatic amine is 4,4-diaminodiphenylmethane, m-phenylene Diamine, and diaminodiphenylsulfone, or a mixture of two or more thereof.

At this time, the amount of the curing agent used is preferably 0.5 to 1.5 equivalents, more preferably 0.7 to 1.2 equivalents, based on 1 equivalent of the epoxy group in the epoxy resin (fatty acid modified and unmodified epoxy resin), with an activator reactive with the epoxy group in the curing agent Can be used. In this range, the curing rate is appropriate and an excellent shear strength can be ensured.

In addition, the structural epoxy adhesive composition according to an exemplary embodiment of the present invention may further include a curing accelerator, a filler, or a mixture thereof.

In one embodiment of the present invention, the curing accelerator is used in combination with a curing agent to control the curing rate. The curing accelerator may be any one or a mixture of two or more selected from imidazole accelerators, urea accelerators, and tertiary amine accelerators. But it is not limited thereto.

Specific examples thereof include 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 2-ethyl-4-methylimidazole, (2'-methylimidazolyl- (1 ')] - ethyl-s-triazine, 2,4-diamino-6- [2'- undecylimidazolyl- 3-heptadecylimidazole, 2-phenylimidazole, 2-phenylimidazoline, 1,2-dimethylimidazole, 1-cyanoethyl Imidazole-based accelerators such as 1-cyanoethyl-2-ethyl-4-methylimidazole or 1-cyanoethyl-2-undecylimidazole; N, N-dimethylurea (hereinafter referred to as "mononurone"), 3-phenyl-1,1-dimethylurea (referred to as " Urea-based accelerators such as dimethylurea (referred to as &quot; diuron &quot;) and the like; Tertiary amine-based accelerators such as benzyldimethylamine, triethanolamine, triethylenediamine, dimethylaminoethanol or tri (dimethylaminomethyl) phenol may be used alone or in admixture of two or more.

The curing accelerator may be used in an amount of 0.001 to 5 parts by weight, more preferably 0.01 to 3 parts by weight, more preferably 0.1 to 1.5 parts by weight, based on 100 parts by weight of the epoxy resin (fatty acid modified and unmodified epoxy resin) Parts by weight. Sufficient curing acceleration effect can be exhibited within the above range, and discoloration may not occur.

 In one embodiment of the invention, the filler is used to improve mechanical strength, thermal dimensional stability and moisture resistance, and specifically includes, for example, quartz, limestone, mica, calcium carbonate, magnesium carbonate, hydrotalcite, Inorganic fillers such as aluminum, aluminum nitride, boron nitride, silicon nitride, magnesium hydroxide, calcium hydroxide, wollastonite, bentonite, silica, alumina, titanium oxide, barium sulfate, calcium sulfate, talc or glass fiber. The filler may be used in an amount of 5 to 40 parts by weight, more preferably 10 to 35 parts by weight, and more preferably 15 to 30 parts by weight, based on 100 parts by weight of the epoxy resin (fatty acid modified and unmodified epoxy resin).

In addition to this, in one embodiment of the present invention, optionally one or more other additives may additionally be contained. For example, optional additives may include additives such as stabilizers, surfactants, flow modifiers, pigments or dyes, quenchers, deagglomerators, flame retardants, curing initiators, cure inhibitors, wetting agents, colorants, thermal plasticizers, processing aids, , A fluorescent compound, a UV stabilizer, an antioxidant, a release agent, and a mixture thereof. The optional additives may be used in a range that does not impair the physical properties of the structural epoxy adhesive composition of the present invention.

Hereinafter, the structural epoxy adhesive composition according to the present invention will be described in more detail by way of examples. It should be understood, however, that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Also, the singular forms as used in the specification and the appended claims are intended to include the plural forms as well, unless the context clearly indicates otherwise. In addition, the unit of the additives not specifically described in the specification may be% by weight.

[Synthesis Example 1] Production of fatty acid-modified TDPE (Di-TDPE)

80 g (0.24 mol) of thiodiphenyl epoxy resin, 18 g / eq of epoxy equivalent and 34 g (0.06 mol) of Di-FA (dimeric fatty acid) 0.4 g of oligo triphenylphosphine was added. Thereafter, the reaction was conducted at 130 ° C for 40 minutes and then cooled to room temperature.

The epoxy equivalent weight (EEW) of the mixture before the reaction was 253 g / eq. The epoxy equivalent of the product after the reaction was 329 g / eq, indicating that the epoxy group was reduced by the reaction of the fatty acid and the epoxy resin. At this time, the epoxy equivalent was calculated by the titration method according to ASTM D 1652. The reactants resulting from the reaction were a mixture of pure TDPE and Di-TDPE in a ratio of 1: 1, and the solid TDPE at room temperature (about 25 ° C) was mixed with the synthesized Di-TDPE And it was found to be present as a solution in the solution.

The above obtained product is an epoxy resin mixed with 40 g of Di-TDPE (65% by weight) in which 74 g of unreacted TDPE (35% by weight) is produced, and the calculated equivalent weight of different epoxy resins is calculated. The epoxy equivalence {EEW = 100 / (35/182) + (65/610)} is 334 g / eq, which is comparable to the EEW value 329 g / eq calculated by the titration method Able to know.

[Examples 1 to 3 and Comparative Example 1]

Structural epoxy adhesive compositions were prepared with the compositions listed in Table 1 below, wherein the content of each component was reported in weight percent.

Example 1 Example 2 Example 3 Comparative Example 1 Di-TDPE 3.06 6.12 9.19 0 Epoxy resin 43.20 40.14 37.07 46.26 Polyurethane-based toughening agent 14.99 14.99 14.99 14.99 Core Shell Type 19.98 19.98 19.98 19.98 Hardener 6.41 6.41 6.41 6.41 Filler 11.99 11.99 11.99 11.99 Reaction promoter 0.37 0.37 0.37 0.37

In Table 1, EPIKOTE 828 (EEW: 187 g / eq) manufactured by MOMENTIVE Co., Ltd. was used as the epoxy resin, 80 g of polytetrahydrofuran having a number average molecular weight of 2000 g / mol and 10 g of isophorone diisocyanate Was reacted with a dibutyltin dilaurate catalyst at 80 ° C for 30 minutes and then reacted with 20 g of risorcinol. The core shell type toughening agent was MX-156 manufactured by KANEKA. A mixture of limestone: quartz in a weight ratio of 1: 1 was used as the filler, and the reaction accelerator was 3-phenyl-1,1-dimethyl (1-ethylhexyl) Urea was used.

[Property evaluation]

1) T-peel strength (N / 25 mm): The T-peel strength test specimen was prepared by forming a bonding portion of 25 x 241 mm on two metal plates (SPRC440, 25 x 305 mm) And then cured at 180 ° C for 20 minutes. The T-peel strength was measured by pulling the adherend at 254 mm / min according to ASTM D-1876 standard with a universal testing machine (UTM, universal testing machine).

The measurement results are shown in Fig. The T-peel strength of Di-TDPE was measured to be 298.15 N / 25㎜ in Example 2 (10 phr). The softness characteristics of Di-TDPE modified with fatty acids complemented the embrittlement of the epoxy, indicating high T-peel strength.

2) Lap shear strength (MPa): The superposed shear strength test specimens were prepared by bonding 25 × 12.7 mm of adhesive to 2 metal plates (SPRC440, 25 × 100 × 1.6 mm) And cured for 20 minutes. The superposition shear strength was measured by pulling the adherend at a speed of 1.3 mm / min according to ASTM D-1002 standard with a universal testing machine (UTM, universal material testing machine).

The measurement results are shown in Fig. As a result of measuring the shear strength of Di-TDPE, the maximum value of 30.38 ㎫ was obtained in Example 2 (10 phr). Also, the soft properties of Di-TDPE modified with fatty acids compensate the brittleness of epoxy and show high shear strength.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the above description does not limit the scope of the present invention, which is defined by the limitations of the following claims.

Claims (8)

A structural epoxy adhesive composition comprising a fatty acid modified epoxy resin, a fatty acid unmodified epoxy resin, a polyurethane toughening agent, and a core shell toughening agent, which is liquid at normal temperature and satisfies the following formula (1).
[Chemical Formula 1]

(Wherein R is a linear or branched alkenylene group having 20 to 50 carbon atoms containing at least one unsaturated double bond, Ar ₁ to Ar ₄ are each independently a group having 6 to 30 carbon atoms And a and b are independently of each other an integer of 1 to 3.) The method according to claim 1,
Wherein the fatty acid-modified epoxy resin satisfies the following formula (2).
(2)

Wherein R is a linear or branched alkenylene group having 20 to 50 carbon atoms, which contains at least one unsaturated double bond, Ar ₁ to Ar ₄ each independently represent an alkylene group having 6 to 30 carbon atoms Lt; / RTI &gt; The method according to claim 1,
Wherein R in Formula 1 has a branched structure comprising at least one branched chain. delete delete The method according to claim 1,
Wherein the structural epoxy adhesive composition comprises 10 to 50 parts by weight of a polyurethane based toughening agent and 20 to 60 parts by weight of a core-shell type toughening agent, based on 100 parts by weight of a fatty acid-modified epoxy resin and a fatty acid- . The method according to claim 6,
Wherein the weight ratio of the fatty acid-modified epoxy resin: fatty acid-unmodified epoxy resin is 1 to 30: 99 to 70. The method according to claim 1,
Wherein the structural epoxy adhesive composition satisfies the following relational expression (1): &quot; (1) &quot;
[Relation 1]
1.2 <S ₁ / S ₀ ≤ 2
Wherein S ₁ is the T-peel strength (N / 25 mm) of the structural epoxy adhesive composition comprising the fatty acid-modified epoxy resin, S ₀ is the structural epoxy adhesive composition comprising the fatty acid-modified epoxy resin (N / 25 mm) of the structural epoxy adhesive composition except for only the epoxy-modified fatty acid.

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