JP2024105744A - Thermoplastic epoxy resin, adhesive, modifier, and method for producing thermoplastic epoxy resin - Google Patents

Abstract

[Problem] To provide a thermoplastic epoxy resin, adhesive, modifier, and method for producing a thermoplastic epoxy resin that can be cured at a relatively low temperature and has excellent productivity. [Solution] The thermoplastic epoxy resin contains a reaction product of a bifunctional epoxy compound containing two glycidyl groups per molecule and a bifunctional thiol compound containing two mercapto groups per molecule, and the bifunctional thiol compound contains a hydrocarbon-based bifunctional thiol compound and/or an ether-based bifunctional thiol compound. [Selected Figure] None

Description

The present invention relates to a thermoplastic epoxy resin, an adhesive, a modifier, and a method for producing a thermoplastic epoxy resin.

Epoxy resins are, for example, the reaction product of an epoxy compound and a curing agent. Epoxy resins are usually three-dimensionally crosslinked thermosetting resins. Therefore, epoxy resins are widely used in various industrial fields where thermosetting properties are required.

On the other hand, depending on the field of use, epoxy resins may be required to have thermoplastic properties. For example, in the field of adhesives, epoxy resins with thermoplastic properties are required. The following thermally conductive thermoplastic adhesive composition has been proposed as such an epoxy resin.

That is, the thermally conductive thermoplastic adhesive composition contains a bisphenol A type epoxy resin as a bifunctional epoxy resin, ethylene glycol bisthioglycolate as a curing agent, and graphite. The thermally conductive thermoplastic adhesive composition is applied to polyethylene terephthalate and cured at 130°C. This results in a thermally conductive sheet (see, for example, Patent Document 1 (Example 3)).

JP 2011-184668 A

On the other hand, the above-mentioned thermally conductive thermoplastic adhesive composition has a relatively high curing temperature. Therefore, when curing the thermally conductive thermoplastic adhesive composition, the cost is relatively high and the productivity of the cured product is poor.

The present invention relates to a thermoplastic epoxy resin, adhesive, modifier, and method for producing a thermoplastic epoxy resin that can be cured at a relatively low temperature and has excellent productivity.

The present invention [1] includes a thermoplastic epoxy resin that includes a reaction product of a bifunctional epoxy compound containing two glycidyl groups per molecule and a bifunctional thiol compound containing two mercapto groups per molecule, the bifunctional thiol compound including at least one selected from the group consisting of a hydrocarbon-based bifunctional thiol compound, a hydroxyl group-containing bifunctional thiol compound, and an ether group-containing bifunctional thiol compound.

The present invention [2] includes an adhesive containing the thermoplastic epoxy resin described in [1] above.

The present invention [3] includes a modifier containing the thermoplastic epoxy resin described in [1] above.

The present invention [4] includes the modifier described in [3] above, which is an epoxy resin modifier obtained by the reaction of an epoxy compound and a curing agent.

The present invention [5] includes a method for producing a thermoplastic epoxy resin, which includes a reaction step of reacting a bifunctional epoxy compound containing two glycidyl groups per molecule with a bifunctional thiol compound containing two mercapto groups per molecule, the bifunctional thiol compound containing at least one selected from the group consisting of a hydrocarbon-based bifunctional thiol compound, a hydroxyl group-containing bifunctional thiol compound, and an ether group-containing bifunctional thiol compound, and the reaction temperature in the reaction step is 120°C or less.

In the thermoplastic epoxy resin, adhesive, modifier, and method for producing a thermoplastic epoxy resin of the present invention, a bifunctional epoxy compound containing two glycidyl groups in one molecule is reacted with a bifunctional thiol compound containing two mercapto groups in one molecule. As a result, a linear structure is formed in the reaction product, and the formation of a three-dimensional crosslinked structure is suppressed. As a result, excellent thermoplasticity is obtained.

Furthermore, in the thermoplastic epoxy resin, adhesive, modifier, and method for producing a thermoplastic epoxy resin of the present invention, the bifunctional thiol compound includes at least one selected from the group consisting of a hydrocarbon-based bifunctional thiol compound, a hydroxyl group-containing bifunctional thiol compound, and an ether group-containing bifunctional thiol compound. Therefore, the thermoplastic epoxy resin, adhesive, modifier, and method for producing a thermoplastic epoxy resin have excellent low-temperature curing properties and excellent productivity.

The thermoplastic epoxy resin of the present invention comprises a reaction product of a difunctional epoxy compound and a difunctional thiol compound. Preferably, the thermoplastic epoxy resin comprises a reaction product of a difunctional epoxy compound and a difunctional thiol compound.

A bifunctional epoxy compound is an epoxy compound that contains two glycidyl groups in one molecule. Bifunctional epoxy compounds are the main component in thermoplastic epoxy resins. Examples of bifunctional epoxy compounds include aromatic bifunctional epoxy compounds, hydrogenated aromatic bifunctional epoxy compounds, glycidyl ester type epoxy compounds, and glycidyl ether type epoxy compounds.

Examples of aromatic bifunctional epoxy compounds include bisphenol type epoxy compounds, biphenol type epoxy compounds, benzenediol type epoxy compounds, and diphenyldicyclopentadiene type epoxy compounds. Examples of bisphenol type epoxy compounds include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol Z diglycidyl ether, bisphenol S diglycidyl ether, bisphenol fluorene diglycidyl ether, and biscresol fluorene diglycidyl ether. Examples of biphenol type epoxy compounds include biphenol diglycidyl ether and tetramethylbiphenol diglycidyl ether. Examples of benzenediol type epoxy compounds include hydroquinone diglycidyl ether, methylhydroquinone diglycidyl ether, and resorcin diglycidyl ether. Examples of diphenyldicyclopentadiene type epoxy compounds include dihydroxyanthracene diglycidyl ether, hydroanthrahydroquinone diglycidyl ether, dihydroxynaphthalene diglycidyl ether, and bisnaphthol fluorene diglycidyl ether.

Hydrogenated aromatic difunctional epoxy compounds include, for example, difunctional epoxy compounds in which hydrogen is added to the aromatic ring of the aromatic difunctional epoxy compound.

An example of a glycidyl ester type epoxy compound is a reaction product of a known dicarboxylic acid and epichlorohydrin.

An example of a glycidyl ether type epoxy compound is a reaction product of a known dialcohol and epichlorohydrin.

The bifunctional epoxy compounds can be used alone or in combination of two or more kinds. From the viewpoints of mechanical properties and cost reduction, the bifunctional epoxy compounds are preferably aromatic bifunctional epoxy compounds, more preferably bisphenol type epoxy compounds, and even more preferably bisphenol A diglycidyl ether.

A bifunctional thiol compound is a thiol compound that contains two mercapto groups in one molecule. A bifunctional thiol compound is a curing agent in thermoplastic epoxy resins.

The bifunctional thiol compound includes at least one selected from the group consisting of a hydrocarbon-based bifunctional thiol compound, a hydroxyl group-containing bifunctional thiol compound, and an ether group-containing bifunctional thiol compound. Preferably, the bifunctional thiol compound includes at least one selected from the group consisting of a hydrocarbon-based bifunctional thiol compound, a hydroxyl group-containing bifunctional thiol compound, and an ether group-containing bifunctional thiol compound.

A hydrocarbon-based bifunctional thiol compound is a bifunctional thiol compound that has two mercapto groups in one molecule and the molecular skeleton other than the mercapto groups is made of hydrocarbon. In other words, a hydrocarbon-based bifunctional thiol compound does not contain a hydroxyl group, an ether bond, or an ester bond.

Examples of the hydrocarbon bifunctional thiol compound include alkanedithiols, alkenedithiols, alkyneedithiols, cycloalkanedithiols, and aryldithiols. Examples of the alkanedithiols include alkanedithiols having 1 to 12 carbon atoms, more specifically, dimercaptomethane, 1,2-dimercaptoethane, 1,1-dimercaptoethane, 1,3-dimercaptopropane, 1,2-dimercaptopropane, 1,1-dimercaptopropane, 1,4-dimercaptobutane, 1,5-dimercaptopentane, 1,6-dimercaptohexane, 1,8-dimercaptooctane, 1,10-dimercaptodecane, and 1,12-dimercaptododecane. Examples of the alkene dithiol include alkene dithiol having 2 to 12 carbon atoms, more specifically, 1,2-dimercapto-2-ethylene, 1,3-dimercapto-2-propene, and 1,4-dimercapto-1-butene. Examples of the alkene dithiol include alkene dithiol having 2 to 12 carbon atoms, more specifically, 1,2-dimercapto-2-acetylene, 1,3-dimercapto-2-propylene, and 1,4-dimercapto-1-butyne. Examples of the cycloalkanedithiol include cycloalkanedithiol having 3 to 12 carbon atoms, more specifically, 1,4-dimercaptocycloalkane. Examples of the aryldithiol include aryldithiol having 6 to 12 carbon atoms, more specifically, 1,4-dimercaptobenzene and 1,5-dimercaptonaphthalene. These can be used alone or in combination of two or more types.

A hydroxyl group-containing bifunctional thiol compound is a bifunctional thiol compound that has two mercapto groups and one or more hydroxyl groups in one molecule, and the molecular skeleton other than the mercapto groups and hydroxyl groups is made of a hydrocarbon. In other words, a hydrocarbon-based bifunctional thiol compound does not contain an ether bond or an ester bond.

Examples of hydroxyl group-containing bifunctional thiol compounds include dimercaptoalcohols having 3 to 12 carbon atoms, more specifically 1,3-dimercapto-2-propanol, 1,4-dimercapto-2-butanol, and 1,4-dimercapto-3-butanol.

An ether group-containing bifunctional thiol compound is a bifunctional thiol compound that has two mercapto groups and one or more ether bonds in one molecule, and whose molecular backbone other than the mercapto groups and ether bonds is made of hydrocarbon. In other words, a hydrocarbon-based bifunctional thiol compound does not contain a hydroxyl group or an ester bond. Examples of ether bonds include -O- and -S- (thioether).

Examples of ether group-containing bifunctional thiol compounds include bis(2-mercaptoethyl) ether, bis(2-mercaptoethyl) thioether, bis(3-mercaptopropyl) ether, and bis(3-mercaptopropyl) thioether.

The bifunctional thiol compound may also have a heterocycle, if necessary. Examples of the heterocycle include 4- to 8-membered heterocycles.

These bifunctional thiol compounds can be used alone or in combination of two or more kinds. From the viewpoint of productivity, the bifunctional thiol compound is preferably a hydrocarbon-based bifunctional thiol compound, a hydroxyl group-containing bifunctional thiol compound, or an ether group-containing bifunctional thiol compound. More preferably, the bifunctional thiol compound is a hydrocarbon-based bifunctional thiol compound.

In addition, the bifunctional thiol compound may have an aromatic ring (a hydrocarbon aromatic ring and/or a heteroaromatic ring), but from the viewpoint of low-temperature curing properties, the bifunctional thiol compound preferably does not have an aromatic ring. Bifunctional thiol compounds that do not have an aromatic ring are more reactive than bifunctional thiol compounds that have an aromatic ring. Therefore, by using a bifunctional thiol compound that does not have an aromatic ring, it is possible to further improve low-temperature curing properties.

In the production of thermoplastic epoxy resins, the bifunctional epoxy compound and the bifunctional thiol compound are mixed together, and the glycidyl groups and mercapto groups are subjected to a curing reaction (reaction process).

In the curing reaction, the equivalent ratio of the mercapto group in the bifunctional thiol compound to the glycidyl group in the bifunctional epoxy compound (mercapto group/glycidyl group) is, for example, 0.8 or more, preferably 0.9 or more. Also, the equivalent ratio of the mercapto group in the bifunctional thiol compound to the glycidyl group in the bifunctional epoxy compound (mercapto group/glycidyl group) is, for example, 1.2 or less, preferably 1.1 or less.

The pressure conditions for the reaction may be normal pressure, elevated pressure, or reduced pressure. Normal pressure is preferred.

The bifunctional epoxy compound and the bifunctional thiol compound undergo a curing reaction at a relatively low temperature. Therefore, the reaction temperature is relatively low, for example, 0°C or higher, preferably 20°C or higher, and more preferably 50°C or higher. The reaction temperature is, for example, 120°C or lower, preferably 110°C or lower, more preferably 105°C or lower, and even more preferably 100°C or lower. If the reaction temperature is below the above upper limit, the thermoplastic epoxy resin has excellent low cost and productivity.

The reaction time is not particularly limited, but is, for example, 0.5 hours or more, and preferably 1 hour or more. The reaction time is, for example, 5 hours or less, and preferably 3 hours or less. If the reaction time is within the above range, the thermoplastic epoxy resin has excellent low cost and productivity.

In the curing reaction, a known curing accelerator can be added as necessary. Examples of the curing accelerator include alkali metal hydroxides, tertiary amine compounds, quaternary ammonium compounds, tertiary phosphine compounds, quaternary phosphonium compounds, and imidazole compounds. These can be used alone or in combination of two or more types. The amount of the curing accelerator added is appropriately set depending on the purpose and application.

In the curing reaction, a known solvent can be added as necessary. Examples of the solvent include ketones, esters, ethers, amides, and glycol ethers. These can be used alone or in combination of two or more. Ketones and glycol ethers are preferred. The amount of solvent added is appropriately set depending on the purpose and application.

As a result, a thermoplastic epoxy resin is obtained as the reaction product. More specifically, in the above method, a bifunctional epoxy compound reacts with a bifunctional thiol compound. In other words, bifunctional compounds react with each other. As a result, a linear structure is formed in the reaction product, and the formation of a three-dimensional crosslinked structure is suppressed. As a result, an epoxy resin having thermoplastic properties is obtained.

In addition, in the reaction between a bifunctional epoxy compound and a bifunctional thiol compound, a hydroxyl group is produced as a by-product. In addition, the bifunctional thiol compound may contain a hydroxyl group. In such a case, in addition to the bifunctional mercapto group, the hydroxyl group may react with the glycidyl group to form a three-dimensional crosslinked structure.

However, the reactivity of hydroxyl groups with glycidyl groups is much lower than that of mercapto groups with glycidyl groups. Therefore, mercapto groups react preferentially with glycidyl groups. As a result, a linear structure is formed, and the formation of a three-dimensional crosslinked structure is suppressed, resulting in the formation of a linear structure. Therefore, a thermoplastic epoxy resin is obtained as the reaction product of a bifunctional epoxy compound and a bifunctional thiol compound.

The above thermoplastic epoxy resin is obtained as a reaction product of a bifunctional epoxy compound and a bifunctional thiol compound, and therefore has excellent solubility and/or dispersibility in a solvent. Therefore, the above thermoplastic epoxy resin can be obtained as a solution and/or dispersion in the above solvent, and has excellent handleability.

When the thermoplastic epoxy resin is obtained as a solution and/or dispersion in the above-mentioned solvent, the above-mentioned solvent can be removed by a known method as necessary to obtain a solid thermoplastic epoxy resin. The above-mentioned solvent can also be added to the solid thermoplastic epoxy resin to obtain a solution and/or dispersion of the thermoplastic epoxy resin. Furthermore, the above-mentioned solvent can also be added to the solution and/or dispersion of the thermoplastic epoxy resin to adjust the solid content concentration. From the viewpoint of adjusting the viscosity and improving the handleability, the thermoplastic epoxy resin is preferably prepared as a solution and/or dispersion.

The solids concentration of the thermoplastic epoxy resin solution and/or dispersion is, for example, 1 mass% or more, preferably 5 mass% or more, and more preferably 10 mass% or more. The solids concentration of the thermoplastic epoxy resin solution and/or dispersion is, for example, 70 mass% or less, preferably 60 mass% or less, and more preferably 50 mass% or less.

In such a thermoplastic epoxy resin and its manufacturing method, a bifunctional epoxy compound containing two glycidyl groups in one molecule is reacted with a bifunctional thiol compound containing two mercapto groups in one molecule. As a result, a linear structure is formed in the reaction product, and the formation of a three-dimensional crosslinked structure is suppressed. As a result, the thermoplastic epoxy resin has excellent thermoplasticity.

In addition, in the above-mentioned thermoplastic epoxy resin and its manufacturing method, the bifunctional thiol compound includes at least one selected from the group consisting of a hydrocarbon-based bifunctional thiol compound, a hydroxyl group-containing bifunctional thiol compound, and an ether group-containing bifunctional thiol compound. Therefore, the thermoplastic epoxy resin has excellent low-temperature curing properties and excellent productivity.

Since such thermoplastic epoxy resins (cured products) have thermoplastic properties, they can be molded into any shape by heating, and are suitable for use in a variety of fields. There are no particular limitations on the fields in which thermoplastic epoxy resins are used, but examples include the adhesives field, paint field, electrical and electronic materials field, semiconductor materials field, insulating materials field, coating field, and film field, and preferably the adhesives field.

The thermoplastic epoxy resin is preferably used as an adhesive. The adhesive contains the above-mentioned thermoplastic epoxy resin, and preferably consists of the above-mentioned thermoplastic epoxy resin. Examples of the adhesive include a liquid adhesive and a film adhesive, and preferably a film adhesive.

The film-like adhesive is, for example, a hot melt adhesive. That is, when using a thermoplastic epoxy resin as a film-like adhesive, the thermoplastic epoxy resin is first molded into a film. Next, the thermoplastic epoxy resin film is heated and melted while in contact with the object to be adhered. The molten thermoplastic epoxy resin is then dried and hardened. This allows the object to be adhered by the thermoplastic epoxy resin.

Thermoplastic epoxy resins are also used as resin modifiers. Examples of resins to be modified (resins to be modified) include resins that contain compounds capable of reacting with hydroxyl groups (hydroxyl group-reactive compounds) as raw material components.

That is, as described above, the thermoplastic epoxy resin contains free hydroxyl groups. More specifically, as described above, hydroxyl groups are by-produced by the reaction of a bifunctional epoxy compound with a bifunctional thiol compound. Also, the bifunctional thiol compound may contain hydroxyl groups. However, the reactivity of hydroxyl groups with glycidyl groups is lower than the reactivity of mercapto groups with glycidyl groups. Therefore, mercapto groups react preferentially with glycidyl groups. As a result, the thermoplastic epoxy resin contains hydroxyl groups that remain unreacted with glycidyl groups.

Therefore, when the raw material components of the resin to be modified contain a hydroxyl group-reactive compound, adding a thermoplastic epoxy resin to the raw material components allows a reaction between a portion of the raw material components and the thermoplastic epoxy resin, and the resin to be modified can be modified by the thermoplastic epoxy resin.

Examples of compounds that can react with hydroxyl groups include epoxy compounds, acrylic ester compounds, isocyanate compounds, and acid anhydride compounds.

To modify a resin to be modified with a thermoplastic epoxy resin, for example, the above-mentioned thermoplastic epoxy resin is blended with the raw material components of the resin to be modified, and the raw material components are reacted. The blending ratio of the thermoplastic epoxy resin and the reaction conditions are appropriately set according to the type of resin to be modified.

For example, the amount of thermoplastic epoxy resin to be mixed per 100 parts by mass of the resin to be modified is, for example, 20 parts by mass or less, preferably 10 parts by mass or less. In addition, although there is no particular lower limit, the amount of thermoplastic epoxy resin to be mixed per 100 parts by mass of the resin to be modified is, for example, 0.1 parts by mass or more.

For example, when the raw material components of the resin to be modified contain an epoxy compound, the reaction temperature is, for example, 0°C or higher, preferably 20°C or higher, and more preferably 50°C or higher. The reaction temperature is, for example, 120°C or lower, preferably 110°C or lower, more preferably 105°C or lower, and even more preferably 100°C or lower.

In these reactions, a curing accelerator can be added as necessary. The curing accelerator is appropriately selected depending on the type of curable compound. For example, when the curable compound is an epoxy compound, the curing accelerator may be any of the above-mentioned curing accelerators.

Resins modified with thermoplastic epoxy resins are suitable for use in a variety of industrial fields, without any particular limitations. Examples of such fields include adhesives, paints, electrical and electronic materials, semiconductor materials, insulating materials, coatings, and films.

Next, the present invention will be described based on examples and comparative examples, but the present invention is not limited to the following examples. Note that "parts" and "%" are by mass unless otherwise specified. In addition, the specific numerical values of the compounding ratio (content ratio), physical property values, parameters, etc. used in the following description can be replaced with the upper limit value (a numerical value defined as "equal to or less than") or lower limit value (a numerical value defined as "equal to or more than" or "exceeding") of the corresponding compounding ratio (content ratio), physical property value, parameter, etc. described in the above "Form for carrying out the invention".

1. Raw materials (Component A) Main component: Bisphenol A type epoxy compound (product name jER828, manufactured by Mitsubishi Chemical Corporation, epoxy compound, bisphenol A diglycidyl ether, functional group number 2)

(Component B) Curing agent (1) 1,3-dimercapto-2-propanol (manufactured by Asahi Chemical Industry Co., Ltd., DMP, thiol compound, hydroxyl group-containing bifunctional thiol compound, functional group number 2)
(2) 1,4-Dimercaptobenzene (manufactured by Asahi Chemical Industry Co., Ltd., 1,4-DMB, thiol compound, hydrocarbon-based bifunctional thiol compound, number of functional groups: 2)
(3) Bis(2-mercaptoethyl)ether (Tokyo Chemical Industry Co., Ltd., BMEE, thiol compound, ether group-containing bifunctional thiol compound, number of functional groups: 2)
(4) Pentaerythritol tetrakis(3-mercaptopropionate) (Tokyo Chemical Industry Co., Ltd., PE-TMPA, thiol compound, number of functional groups: 4)
(5) Bisphenol A (Nacalai Tesque, Bis-A, polyol compound, functional group number 2)

(Component C) Curing accelerator (1) Amine adduct type curing accelerator (product name Amicure PN-23, manufactured by Ajinomoto Fine-Techno Co., Ltd., PN-23)
(2) Triphenylphosphine (TPP, manufactured by Wako Pure Chemical Industries, Ltd.)

2. Thermoplastic epoxy resin Example 1, Example 3 and Comparative Example 1
Components A, B, and C were mixed according to the recipe shown in Table 1. The equivalent ratio of the mercapto group in the bifunctional thiol compound to the glycidyl group in the bifunctional epoxy compound (mercapto group/glycidyl group) was 1.0.

The resulting mixture was then poured into a mold (thickness 3 mm) and heated at 50°C for 1 hour, and then heated at 80°C for 1 hour. This resulted in a thermoplastic epoxy resin (thickness 3 mm).

As described below, in Comparative Example 1, a thermosetting epoxy resin was obtained instead of a thermoplastic epoxy resin.

Example 2
Components A, B, and C were mixed according to the recipe shown in Table 1. The equivalent ratio of the mercapto group in the bifunctional thiol compound to the glycidyl group in the bifunctional epoxy compound (mercapto group/glycidyl group) was 1.0.

The resulting mixture was then poured into a mold (thickness 3 mm) and heated at 80°C for 1 hour, and then heated at 120°C for 2 hours. This resulted in a thermoplastic epoxy resin (thickness 3 mm).

Comparative Example 2
Components A, B, and C were mixed based on the recipe in Table 1. The resulting mixture was then poured into a mold (thickness 3 mm) and heated at 120°C for 30 minutes, and then heated at 150°C for 5 hours. This resulted in a thermoplastic epoxy resin (thickness 3 mm). In Comparative Example 1, components A, B, and C did not react under the same temperature conditions as in Example 1.

<Evaluation>
(1) Solubility Cyclohexanone or ethylene glycol monomethyl was added to an epoxy resin test piece (30 mm x 10 mm x 3 mm) so that the solid content was 30% by mass, and the epoxy resin was dissolved at room temperature. After that, the degree of undissolved epoxy resin was visually observed. The evaluation criteria are as follows.
○: No residual dissolution was observed.
△: A small amount of undissolved material was observed.
×: Almost no dissolution.

3. Adhesive The thermoplastic epoxy resin obtained in each Example and Comparative Example was sandwiched between two aluminum plates. The gap between the aluminum plates was then adjusted to 1 mm using a spacer. The aluminum plate and the thermoplastic epoxy resin were then fixed together and heated in a hot air drying oven at 150°C for 60 minutes. It was then confirmed that the temperature of the thermoplastic epoxy resin had returned to room temperature. This resulted in a film-like adhesive (thickness 1 mm) made of thermoplastic epoxy resin.

<Evaluation>

(1) Thermoplasticity The epoxy resins of Examples 1 to 3 and Comparative Example 2 were judged to have thermoplasticity because they could be molded into a film by the above method. On the other hand, the epoxy resin of Comparative Example 1 was judged not to have thermoplasticity because it could not be molded into a film by the above method.
(2) Adhesion Two aluminum plates (thickness 1.5 mm x width 25 mm x length 100 mm, A1050P) were prepared. Next, the adhesive portion of each aluminum plate (width 25 mm x length 12.5 mm) was blasted. Next, a film made of a thermoplastic epoxy resin was placed on the adhesive portion of one of the aluminum plates, and the aluminum plate was bonded to the other aluminum plate. After that, the aluminum plate and the film were fixed, heated at 150°C for 60 minutes in a hot air drying oven, and allowed to cool to room temperature. This resulted in a test piece.

The test pieces were pulled in the tensile direction (180°) at a tensile speed of 5 mm/min using a universal material testing machine (Shimadzu Corporation AGS-X) to measure the maximum load. The adhesive strength (MPa) was then calculated based on the maximum load and the adhesive area. This test was conducted in accordance with JIS K 6850 (1999).

4. Modifier (Component D) Hydroxyl group reactive compound (1) Bisphenol A type epoxy compound (product name jER828, manufactured by Mitsubishi Chemical Corporation, epoxy compound, functional group number 2)
(2) 4-Methylcyclohexane-1,2-dicarboxylic anhydride (acid anhydride, MCDA)

(Component E) Modifier (1) Thermoplastic epoxy resin of Example 3 (BMEE828)

(Component F) Curing Accelerator (1) N,N'-Dimethylbenzylamine (DMBA)

Examples 4 to 5 and Comparative Example 3
Components D, E, and F were mixed based on the recipe in Table 2. The mixture obtained was then poured into a mold (thickness 3 mm) and heated at 50°C for 1 hour, and then heated at 80°C for 1 hour. This resulted in a resin (thickness 3 mm) modified with a thermoplastic epoxy resin. In Comparative Example 3, component E was not blended.

<Evaluation>
(1) Fracture toughness value The fracture toughness value of the resin test piece (60 mm x 10 mm x 3 mm) obtained in each Example and Comparative Example was measured using a universal material testing machine (AGS-X manufactured by Shimadzu Corporation). The measurement was performed in accordance with the three-point bending method of ASTM D5043-93. The measurement conditions were a support distance of 40 mm and a loading rate of 1 mm/min. The critical stress intensity factor (K _1C ) calculated by the fracture toughness test was used as the fracture toughness value.

(2) Flexural strength and flexural modulus The flexural strength and flexural modulus of the resin test pieces (60 mm x 10 mm x 3 mm) obtained in each Example and Comparative Example were measured using a universal material testing machine (AGS-X manufactured by Shimadzu Corporation). The measurements were performed in accordance with the three-point bending test of JIS K-6911 (2006). The measurement conditions were a support distance of 48 mm and a loading speed of 1.5 mm/min.

Claims (5)

a bifunctional epoxy compound containing two glycidyl groups in one molecule;
It includes a reaction product with a bifunctional thiol compound containing two mercapto groups in one molecule,
The thermoplastic epoxy resin, wherein the bifunctional thiol compound includes at least one selected from the group consisting of a hydrocarbon-based bifunctional thiol compound, a hydroxyl group-containing bifunctional thiol compound, and an ether group-containing bifunctional thiol compound. An adhesive comprising the thermoplastic epoxy resin according to claim 1. A modifier comprising the thermoplastic epoxy resin according to claim 1. The modifier according to claim 3, which is an epoxy resin modifier obtained by the reaction of an epoxy compound and a curing agent. The method includes a reaction step of reacting a bifunctional epoxy compound containing two glycidyl groups in one molecule with a bifunctional thiol compound containing two mercapto groups in one molecule,
the bifunctional thiol compound includes at least one selected from the group consisting of a hydrocarbon-based bifunctional thiol compound, a hydroxyl group-containing bifunctional thiol compound, and an ether group-containing bifunctional thiol compound;
The method for producing a thermoplastic epoxy resin, wherein the reaction temperature in the reaction step is 120° C. or lower.