阅读说明：本技术 环氧树脂、及包含其的环氧树脂组合物、以及使用了前述环氧树脂组合物的固化物 (Epoxy resin, epoxy resin composition containing same, and cured product using same ) 是由 杉本菜菜 林弘司 江原岳 于 2018-07-05 设计创作，主要内容包括：本发明提供一种环氧树脂,其特征在于,其是1,2,4-三羟基苯与表卤代醇的反应产物,前述环氧树脂包含环状化合物,所述环状化合物具有包含源自1,2,4-三羟基苯的1位及2位的氧原子作为构成原子的环状结构,前述环状化合物的含量相对于环氧树脂100g为0.003～0.070mol。该环氧树脂在液态下耐热分解性优异。(The present invention provides an epoxy resin which is a reaction product of 1,2, 4-trihydroxybenzene and epihalohydrin, the epoxy resin including a cyclic compound having a cyclic structure including oxygen atoms at the 1-position and the 2-position derived from 1,2, 4-trihydroxybenzene as constituent atoms, the content of the cyclic compound being 0.003 to 0.070mol based on 100g of the epoxy resin. The epoxy resin is excellent in thermal decomposition resistance in a liquid state.)

1. An epoxy resin which is the reaction product of 1,2, 4-trihydroxybenzene and epihalohydrin,

the epoxy resin includes a cyclic compound having a cyclic structure including oxygen atoms at positions 1 and 2 derived from 1,2, 4-trihydroxybenzene as constituent atoms,

the content of the cyclic compound is 0.003-0.070 mol relative to 100g of the epoxy resin.

2. The epoxy resin according to claim 1, which has an epoxy equivalent of 105 g/eq or more.

3. The epoxy resin according to claim 1 or 2, further comprising 1,2, 4-triglycidyl ether oxybenzene,

the content of the 1,2, 4-triglycidyl ether oxybenzene is more than 70%.

4. The epoxy resin according to any one of claims 1 to 3, further comprising an oligomer,

the oligomer content is 7.5% or less.

5. An epoxy resin composition comprising the epoxy resin as claimed in any one of claims 1 to 4 and a curing agent.

6. A cured product obtained by curing the epoxy resin composition according to claim 5.

Technical Field

The present invention relates to an epoxy resin, an epoxy resin composition containing the same, and a cured product using the epoxy resin composition.

Background

The epoxy resin is a curable resin which contains an epoxy group in a molecule and can be cured by forming a crosslinked network from the epoxy group. Cured products of epoxy resins have excellent mechanical strength, heat resistance, water resistance, insulation properties, and the like, and thus are widely used in applications such as matrices of fiber-reinforced composite materials, heat dissipation members, adhesives, paints, semiconductors, and printed circuit boards.

As such an epoxy resin, a diglycidyl ether of bisphenol a is widely used, but since it is 2-functional, its application to applications requiring heat resistance is limited. Therefore, epoxy resins having 3 or more functions have been studied.

For example, patent document 1 describes that an epihalohydrin ether of 1,2, 4-trihydroxybenzene is produced by reacting 1,2, 4-trihydroxybenzene (1,3, 4-benzenetriol) with an epihalohydrin in the presence of a catalyst, and then the epihalohydrin ether of 1,2, 4-trihydroxybenzene is reacted with an alkali metal compound, whereby a polyepoxy compound of 1,2, 4-triglycidyl ether oxybenzene can be obtained. Patent document 1 describes that the polyepoxy compound is excellent in heat resistance because it has 3 functions, is in a liquid state having a low viscosity at room temperature, and does not crystallize at low temperatures.

Disclosure of Invention

Problems to be solved by the invention

In recent years, miniaturization and high performance of products have been advanced in various applications of cured products of epoxy resins, and the epoxy resins are also required to have high performance.

Since the epoxy resin described in patent document 1 is 3-functional, it was found that a cured product thereof has a predetermined heat resistance, but has low thermal decomposition resistance.

From the viewpoint of improving the thermal decomposition resistance, it is considered to purify the triglycidyl group of 1,2, 4-triglycidyl ether oxybenzene, which is a product obtained from the epoxy resin described in patent document 1. However, it was found that the triglycidyl group of 1,2, 4-triglycidyl ether oxybenzene is a crystalline compound and has poor handling properties.

Accordingly, an object of the present invention is to provide an epoxy resin which is in a liquid state and has excellent thermal decomposition resistance of a cured product.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems. As a result, the present inventors have found that the above problems can be solved by controlling the content of a predetermined compound that can be contained in an epoxy resin obtained by oxidizing a 1,2, 4-trihydroxybenzene ring, and have completed the present invention.

That is, the present invention relates to an epoxy resin which is a reaction product of 1,2, 4-trihydroxybenzene and epihalohydrin. In this case, the epoxy resin contains a cyclic compound having a cyclic structure containing oxygen atoms at the 1-position and the 2-position derived from 1,2, 4-trihydroxybenzene as constituent atoms, and the content of the cyclic compound is 0.003 to 0.070mol based on 100g of the epoxy resin.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention provides an epoxy resin which is in a liquid state and a cured product of which has excellent thermal decomposition resistance.

Drawings

FIG. 1 is a drawing showing an epoxy resin produced in example 1¹³C NMR chart.

Detailed Description

Hereinafter, embodiments for carrying out the present invention will be described in detail.

< epoxy resin >

The epoxy resin of this embodiment is a reaction product of 1,2, 4-trihydroxybenzene and epihalohydrin.

When 1,2, 4-trihydroxybenzene is reacted with epihalohydrin, in general, the hydroxyl groups at the 1-, 2-, and 4-positions of 1,2, 4-trihydroxybenzene are glycidylated to obtain a triglycidyl ether (1,2, 4-triglycidyl ether oxybenzene). However, in addition to these, various reactions may be carried out, and as a result, the reaction product of 1,2, 4-trihydroxybenzene and epihalohydrin may contain various epoxy compounds. The physical properties of the epoxy resin as such a reaction product and the physical properties of a cured product thereof are affected by other compounds contained in the epoxy resin in addition to the triglycidyl ether of 1,2, 4-trihydroxybenzene.

In contrast, the epoxy resin of the present embodiment focuses on a predetermined cyclic compound that can be contained in the reaction product, and the content of the cyclic compound is controlled. From this, it was found that crystallization of the epoxy resin can be suppressed and the obtained cured product is excellent in thermal decomposition resistance.

[1,2, 4-Trihydroxybenzene ]

The 1,2, 4-trihydroxybenzene has a structure represented by the following chemical formula.

[ epihalohydrin ]

The epihalohydrin is not particularly limited, and epichlorohydrin, epibromohydrin, β -methylepichlorohydrin, β -methylepibromohydrin, and the like can be used alone or in combination of 2 or more.

The amount of epihalohydrin used is not particularly limited, but is preferably 1.2 to 20 moles, and more preferably 1.5 to 10 moles, based on 1 mole of the hydroxyl group of 1,2, 4-trihydroxybenzene. The amount of the epihalohydrin to be used is preferably 1.2 mol or more, because it becomes easy to control other compounds that may be contained in the epoxy resin. On the other hand, when the amount of the epihalohydrin to be used is 20 mol or less, it is preferable from the viewpoint of yield because the cost is low.

[ reaction ]

The reaction of 1,2, 4-trihydroxybenzene with epihalohydrin is not particularly limited, and can be carried out by a known method. In one embodiment, the aforementioned reaction comprises: a step (1) of reacting a mixture containing 1,2, 4-trihydroxybenzene and epihalohydrin in the presence of a quaternary onium salt and/or a basic compound, and a step (2) of ring-closing the reactant obtained in the step (1) in the presence of a basic compound.

(step (1))

The step (1) is a step of reacting a mixture containing 1,2, 4-trihydroxybenzene and epihalohydrin in the presence of a quaternary onium salt and/or a basic compound.

Mixture of

The mixture comprises 1,2, 4-trihydroxybenzene and epihalohydrin. Further, a reaction solvent and the like may be further contained as necessary.

1,2, 4-trihydroxybenzene and epihalohydrin

The 1,2, 4-trihydroxybenzene and the epihalohydrin are as described above, and therefore, the description thereof is omitted here.

Reaction solvent

The reaction solvent is not particularly limited, and examples thereof include alcohols such as methanol, ethanol, isopropanol, and butanol; ketones such as acetone and methyl ethyl ketone; ethers such as dioxane; dimethyl sulfone; dimethyl sulfoxide, and the like. These reaction solvents may be used alone, or 2 or more kinds may be used in combination.

When the reaction solvent is used, the amount of the reaction solvent added is preferably 5 to 150 parts, more preferably 7.5 to 100 parts, and still more preferably 10 to 50 parts, based on 100 parts of the epihalohydrin.

Quaternary onium salt

The quaternary onium salt has a function of promoting the reaction in the step (1) described later.

The quaternary onium salt is not particularly limited, and quaternary ammonium salts, quaternary phosphonium salts and the like can be mentioned.

The quaternary ammonium salt is not particularly limited, and examples thereof include tetramethylammonium cation, methyltriethylammonium cation, tetraethylammonium cation, tributylmethylammonium cation, tetrabutylammonium cation, phenyltrimethylammonium cation, benzyltrimethylammonium cation, phenyltriethylammonium cation, benzyltriethylammonium cation, chloride salts of benzyltributylammonium cation, tetramethylammonium cation, trimethylpropylammonium cation, tetraethylammonium cation, bromide salts of tetrabutylammonium cation, and the like.

The quaternary phosphonium salt is not particularly limited, and includes tetraethylphosphonium cation, tetrabutylphosphonium cation, methyltriphenylphosphonium cation, tetraphenylphosphonium cation, ethyltriphenylphosphonium cation, butyltriphenylphosphonium cation, and bromide salts of benzyltriphenylphosphonium cation.

Among these, as the quaternary onium salt, tetramethylammonium cation, benzyltrimethylammonium cation, chloride salt of benzyltriethylammonium cation, and bromide salt of tetrabutylammonium cation are preferably used.

The quaternary onium salts may be used alone or in combination of 2 or more.

The amount of the quaternary onium salt added is preferably 0.15 to 5% by mass, more preferably 0.18 to 3% by mass, based on the total mass of 1,2, 4-trihydroxybenzene and epihalohydrin. The amount of the quaternary onium salt added is preferably 0.18% by mass or more because the reaction in the step (1) can be appropriately carried out. On the other hand, the amount of the quaternary onium salt added is preferably 3% by mass or less because side reactions can be prevented or suppressed.

Basic compound

The basic compound also has a function of promoting the reaction in the step (1) described later, as in the case of the quaternary onium salt.

The basic compound is not particularly limited, and examples thereof include potassium hydroxide, sodium hydroxide, barium hydroxide, magnesium oxide, sodium carbonate, and potassium carbonate. Of these, potassium hydroxide and sodium hydroxide are preferably used. These basic compounds may be used alone, or 2 or more of them may be used in combination.

The amount of the basic compound added is not particularly limited, but is preferably 0.01 to 0.3 mol, and more preferably 0.02 to 0.2 mol, based on the number of moles of the phenolic hydroxyl group of 1,2, 4-trihydroxybenzene. When the amount of the basic compound added is 0.01 mol or more, the reaction in the step (2) described later can be appropriately performed, and therefore, it is preferable. On the other hand, the amount of the basic compound added is preferably 0.3 mol or less because side reactions can be prevented or suppressed.

The quaternary onium salt and the basic compound may be used alone or in combination.

Reaction in step (1)

The reaction in the step (1) is mainly carried out by reacting the hydroxyl group of 1,2, 4-trihydroxybenzene with epihalohydrin, thereby obtaining a tris (3-halo-2-hydroxypropyl ether) intermediate shown below.

In the above formula, "X" represents a halogen atom independently of each other. Further, "R" each independently represents a hydrogen atom or a methyl group.

The reaction temperature in the step (1) is not particularly limited, but is preferably 20 to 120 ℃, more preferably 30 to 110 ℃, and still more preferably 40 to 60 ℃. The reaction temperature in the step (1) is preferably 20 ℃ or higher because the reaction in the step (1) can be appropriately carried out. On the other hand, when the reaction temperature in the step (1) is 120 ℃ or lower, side reactions can be prevented or suppressed, and therefore, it is preferable.

Further, the reaction time in the step (1) is not particularly limited, but is preferably 0.5 hour or more, more preferably 1 to 50 hours, and further preferably 10 to 30 hours. When the reaction time in the step (1) is 0.5 hours or more, the reaction proceeds appropriately and side reactions can be prevented or suppressed, which is preferable.

(step (2))

The step (2) is a step of ring closure of the reactant obtained in the step (1) in the presence of a basic compound.

The reactant obtained in step (1)

The reactant obtained in step (1) contains the tris (3-halo-2-hydroxypropyl ether) intermediate obtained by the reaction of step 1. In addition, the 1 st by-product, unreacted 1,2, 4-trihydroxybenzene, unreacted epihalohydrin, a reaction solvent, impurities, and the like may be contained.

Basic compound

The basic compound has a function of promoting the ring-closure reaction by setting the reaction conditions in the step (2) to basic conditions.

The basic compound is not particularly limited, and examples thereof include potassium hydroxide, sodium hydroxide, barium hydroxide, magnesium hydroxide, sodium carbonate, and potassium carbonate. Of these, potassium hydroxide and sodium hydroxide are preferably used. These basic compounds may be used alone, or 2 or more of them may be used in combination.

The amount of the basic compound added is not particularly limited, but is preferably 0.8 to 1.5 moles, more preferably 0.9 to 1.3 moles, based on the number of moles of the phenolic hydroxyl group of 1,2, 4-trihydroxybenzene. When the amount of the basic compound added is 0.8 mol or more, the ring-closing reaction in the step (2) can be suitably performed, and therefore, it is preferable. On the other hand, the amount of the basic compound to be added is preferably 1.5 mol or less because side reactions can be prevented or suppressed. When the basic compound is used in the step (1), the above-mentioned amount is preferably added, including the amount used in the step (1).

Reaction in step (2)

The reaction in the step (2) is a glycidylation reaction mainly using a 3-halo-2-hydroxypropyl ether group of a tris (3-halo-2-hydroxypropyl ether) intermediate under an alkaline condition, thereby obtaining a triglycidyl group of 1,2, 4-trihydroxybenzene as shown below.

In the above formula, "R" represents a hydrogen atom or a methyl group, respectively.

The reaction temperature in the step (2) is not particularly limited, but is preferably 30 to 120 ℃ and more preferably 25 to 80 ℃.

The reaction pressure in the step (2) is preferably normal pressure (1atm (760 mmHg)). When the reaction pressure in the step (2) is reduced to a pressure lower than 1atm, the ring-closure reaction of the epoxidation reaction tends to be easily progressed by removing the water content in the system, and the cyclic structure tends to increase.

The reaction time in the step (2) is not particularly limited, but is preferably 0.5 to 4 hours, more preferably 1 to 3 hours.

In order to appropriately progress the reaction in the step (2), a further purification step may be used.

[ reaction product ]

The reaction product contains a cyclic compound having a cyclic structure containing oxygen atoms at the 1-and 2-positions derived from 1,2, 4-trihydroxybenzene as constituent atoms. In addition, 1,2, 4-triglycidyl ether oxybenzene (also referred to as "triglycidyl group of 1,2, 4-trihydroxybenzene" in the present specification) is usually contained. Further, oligomers, other glycidyl groups, solvents, other compounds, and the like may be further contained.

In one embodiment, the reaction product contains a triglycidyl matrix of 1,2, 4-trihydroxybenzene, and thus the epoxy resin can have high physical properties. Specifically, the triglycidyl matrix of 1,2, 4-trihydroxybenzene has 3 glycidyl groups. Therefore, the degree of crosslinking is increased, and a cured product having excellent heat resistance can be obtained. In addition, 2 glycidyl groups were adjacent to the triglycidyl group of 1,2, 4-trihydroxybenzene. The adjacent glycidyl groups are densely packed (packing) during the crosslinking reaction, and a cured product having an excellent elastic modulus is obtained.

In one embodiment, the cyclic compound, oligomer, and the like contained in the reaction product are obtained as a result of a side reaction of the glycidylation reaction of 1,2, 4-trihydroxybenzene, and as described above, the cyclic compound, oligomer, and the like may affect the physical properties of the epoxy resin and the physical properties of a cured product thereof. In this case, the side reaction can be controlled by adjusting the reaction conditions, and thus the content of the cyclic compound, the oligomer, and the like can be controlled as well as the content of the triglycidyl group of 1,2, 4-trihydroxybenzene.

For example, in the step (1), the intermediate tris (3-halo-2-hydroxypropyl ether) is obtained as described above, and depending on the reaction conditions, a side reaction occurs in which a part of the 3-halo-2-hydroxypropyl ether group is ring-closed, thereby producing an intermediate having a glycidyl group and a hydroxyl group. In this case, the intermediate obtained by the side reaction generates a cyclic compound when it reacts intramolecularly, and generates an oligomer when it reacts intermolecularly. Therefore, in the step (1), the amount of the cyclic compound or oligomer tends to be controllable by controlling the side reaction to produce the intermediate having a glycidyl group and a hydroxyl group. For example, when the step (1) is carried out under high temperature conditions, a side reaction for forming a glycidyl group is promoted, and the amount of cyclic compounds and oligomers in the obtained reaction product may be high. On the other hand, when the step (1) is carried out under low temperature conditions, the reaction for forming glycidyl groups is relatively suppressed, and the amount of cyclic compounds and oligomers in the obtained reaction product may be low. In addition, when the step (1) is performed in a short time, a large amount of unreacted hydroxyl groups are present and react with the glycidyl groups formed in the step (2), and thus the amount of cyclic compounds and oligomers in the reaction product may be high.

In addition, in the step (2), as described above, the triglycidyl group of 1,2, 4-trihydroxybenzene is obtained from the intermediate tris (3-halo-2-hydroxypropyl ether). In addition, in the step (2), since an intermediate having a glycidyl group and a hydroxyl group is present in the system during the reaction, a side reaction occurs depending on the reaction conditions, and a cyclic compound or an oligomer is produced. Therefore, when the content of the intermediate having a glycidyl group and a hydroxyl group in the reaction process in the step (2) is controlled, the amount of the cyclic compound or oligomer generated by the side reaction tends to be controlled. For example, when the reaction in step (2) is carried out under reduced pressure, water in the system is removed, and as a result, the glycidylation reaction is promoted, and the content ratio of the intermediate having a glycidyl group and a hydroxyl group becomes high. Thus, the possibility of side reactions increases, and the amount of cyclic compounds and oligomers in the obtained reaction product becomes high. On the other hand, when the step (2) is carried out under normal pressure, the reaction rate of the glycidylation reaction becomes slow, and as a result, the content ratio of the intermediate having a glycidyl group and a hydroxyl group becomes low. This reduces the possibility of side reactions, and the amount of cyclic compounds and oligomers in the reaction product obtained may be low.

The content of each component in the reaction product can be controlled by various methods. For example, the reaction can be controlled by adjusting the amount of 1,2, 4-trihydroxybenzene added, the type and amount of epihalohydrin added, the type and amount of quaternary onium salt and basic compound added, the reaction temperature, the reaction pressure, the reaction time, and the like in the step (1). The reaction may be controlled by addition or removal of a raw material, a product, or the like in the step (1). Further, the reaction can be controlled by adjusting the type and amount of the basic compound added, the reaction temperature, the reaction pressure, the reaction time, the reaction rate, and the like in the step (2). The reaction can be controlled by adding or removing the product or the like in the step (2). As a result, the content of each component in the reaction product can be controlled.

(1,2, 4-Triglycidyloxybenzene (triglycidyl radical of 1,2, 4-Trihydroxybenzene))

The 1,2, 4-triglycidyl ether oxybenzene has the following structure.

In the above formula, "R" represents a hydrogen atom or a methyl group, respectively.

The content of the 1,2, 4-triglycidyl phenoxybenzene is preferably 70% or more, more preferably 77% or more, still more preferably 79% or more, and particularly preferably 79 to 90%. In the present specification, the "content of 1,2, 4-triglycidyl ether oxybenzene" refers to an area ratio in Gel Permeation Chromatography (GPC) measurement, and more specifically, refers to a ratio of an area occupied by 1,2, 4-triglycidyl ether oxybenzene in a GPC chart obtained by GPC measurement of a reaction product (area ratio in GPC measurement). The GPC measurement method described in examples was used for the measurement method.

(Cyclic Compound)

The cyclic compound has a cyclic structure containing oxygen atoms at the 1-position and the 2-position derived from 1,2, 4-trihydroxybenzene as constituent atoms. By containing a predetermined amount (0.003 to 0.070mol per 100g of the epoxy resin) of the cyclic compound, crystallization of the epoxy resin can be suppressed, and the workability can be improved. Further, a cured product having excellent mechanical properties (such as flexural strength, flexural modulus, flexural strain, toughness (bending), tensile strength, tensile modulus, elongation, and toughness (tensile)) can be obtained as compared with a cured product containing substantially no cyclic compound.

Specific cyclic compounds are not particularly limited, and examples thereof include the following compounds, and compounds obtained by further reacting the above compounds with an epihalohydrin.

In the above formula, "R" represents a hydrogen atom or a methyl group, respectively.

The cyclic compound may be contained alone, or 2 or more kinds may be contained in combination.

The content of the cyclic compound is 0.003 to 0.070mol, preferably 0.003 to 0.060mol, more preferably 0.010 to 0.060mol, further preferably 0.030 to 0.060mol, and particularly preferably 0.050 to 0.060mol, based on 100g of the epoxy resin. When the content of the cyclic compound exceeds 0.070mol, the resulting cured product cannot have an appropriate thermal decomposition resistance. On the other hand, when the content of the cyclic compound is less than 0.003mol, the epoxy resin is crystallized. Further, mechanical properties (such as bending strength, bending modulus, bending strain, toughness (bending), tensile strength, tensile modulus, elongation, and toughness (tensile)) tend to be low. In the present specification, the "content of cyclic compound" is a value measured by the method described in examples. In addition, when 2 or more cyclic compounds are contained, "the content of the cyclic compound" means the total content thereof.

The content of the cyclic compound can be adjusted by controlling the reaction as described above. The content of the cyclic compound can be adjusted by appropriately adjusting the amount of 1,2, 4-trihydroxybenzene added, the type and amount of epihalohydrin added, the type and amount of quaternary onium salt, the amount of basic compound added, the reaction temperature, the reaction pressure, the reaction time, and the like in the step (1). The addition or removal of the raw materials, products, and the like in the step (1) may be performed. Further, the reaction can be carried out by appropriately adjusting the type and amount of the basic compound, the reaction temperature, the reaction pressure, the reaction time, the reaction rate, and the like in the step (2). The addition or removal of the product of step (2) may be performed.

(oligomer)

The reaction product may comprise oligomers. In the present specification, the term "oligomer" refers to a compound obtained by reacting 1,2, 4-trihydroxybenzene or a derivative thereof with each other. Thus, the oligomer can be said to have a structure having a plurality of 1,2, 4-trihydroxybenzene skeletons.

The oligomer is not particularly limited, and includes oligomers obtained by reacting 1 or 2 or more species of the tris (3-halo-2-hydroxypropyl ether) intermediate, the bis (3-halo-2-hydroxypropyl ether) intermediate, and the mono (3-halo-2-hydroxypropyl ether) intermediate obtained in the above-mentioned step (1); and oligomers obtained by reacting 2 or more functional epoxy compounds such as 1,2, 4-triglycidyl ether oxybenzene with 2 or more functional polyhydric phenols such as 1,2, 4-trihydroxybenzene.

The above-mentioned oligomer may be contained alone, or may be contained in combination of 2 or more.

The content of the oligomer is preferably 7.5% or less, more preferably 4.5% or less, further preferably 4.0% or less, and particularly preferably 0.05 to 3.0%. When the content of the oligomer is 7.5% or less, the viscosity of the epoxy resin may be lowered and the elongation of the obtained cured product may be improved, which is preferable. The "oligomer content" refers to an area ratio in Gel Permeation Chromatography (GPC) measurement, and more specifically, refers to a ratio of an area occupied by an oligomer in a GPC chart obtained by GPC measurement of a reaction product (area ratio in GPC measurement). The GPC measurement method described in examples was used for the measurement method. In the case where 2 or more oligomers are contained, the "content of oligomers" means the total content thereof.

The adjustment of the content of the oligomer can be carried out by appropriately adjusting the amount of the 1,2, 4-trihydroxybenzene added, the kind and amount of the epihalohydrin added, the kind and amount of the quaternary onium salt, the alkali compound added, the reaction temperature, the reaction pressure, the reaction time, and the like in the step (1), as in the case of the cyclic compound. The addition or removal of the raw materials, products, and the like in the step (1) may be performed. Further, the reaction can be carried out by appropriately adjusting the reaction temperature, the reaction pressure, the reaction time, and the like in the step (2).

(other glycidyl group)

The reaction product may contain other glycidyl groups. The other glycidyl group-containing compound is a compound having a glycidyl group other than 1,2, 4-triglycidyl ether oxybenzene, cyclic compounds, and oligomers.

Examples of the other glycidyl group include a diglycidyl group of 1,2, 4-trihydroxybenzene, a monoglycidyl group of 1,2, 4-trihydroxybenzene, and derivatives thereof, which are represented by the following structures. In this case, the "derivative" refers to a compound obtained by reacting the glycidyl group of the diglycidyl radical of 1,2, 4-trihydroxybenzene and the glycidyl group of the monoglycidyl radical of 1,2, 4-trihydroxybenzene with epihalohydrin through a ring-opening addition reaction.

In the above formula, "X" represents a halogen atom independently of each other. Further, "R" each independently represents a hydrogen atom or a methyl group.

The other glycidyl groups may be contained alone or in combination of 2 or more.

(solvent)

The solvent is not particularly limited, and examples thereof include water, a solvent and the like which can be intentionally added in a purification step and the like, in addition to the above-mentioned reaction solvent.

The content of the solvent is preferably 5 parts by mass or less, and more preferably 1 part by mass or less, per 100 parts by mass of the solid content of the epoxy resin. In the present specification, the "solid content of the epoxy resin" refers to the total mass of components other than the solvent in the epoxy resin. Therefore, when the epoxy resin does not contain a solvent, the entire mass of the epoxy resin is consistent with the solid content.

(other Compounds)

The other compounds are not particularly limited, and include compounds other than the product produced by the reaction of 1,2, 4-trihydroxybenzene with epihalohydrin. Specifically, there may be mentioned unreacted 1,2, 4-trihydroxybenzene, unreacted epihalohydrin, unreacted quaternary onium salt, unreacted basic compound, and compounds derived therefrom (by-products and the like).

In general, the content of other compounds tends to be low because of control of reaction conditions and purification.

The content of the other compound is preferably 5% by mass or less, more preferably 0.05 to 5% by mass, based on the solid content of the epoxy resin.

[ constitution of epoxy resin ]

The epoxy resin of the present embodiment is the reaction product described above.

The epoxy equivalent of the epoxy resin is preferably 105 g/equivalent or more, more preferably 105 g/equivalent or more and less than 125 g/equivalent, and further preferably 105 to 120 g/equivalent. An epoxy equivalent of 105 g/equivalent or more is preferable because mechanical properties such as flexural toughness and tensile strength can be improved. In the present specification, the value of "epoxy equivalent" is a value measured by the method described in examples.

The viscosity of the epoxy resin at 25 ℃ is not particularly limited, but is preferably 1500 to 5000 mPas, more preferably 2000 to 4500 mPas. The epoxy resin is preferably one having a viscosity of 1500mPa · s or more at 25 ℃ because sagging at the time of molding can be suppressed. On the other hand, an epoxy resin having a viscosity of 5000 mPas or less at 25 ℃ is preferable because it is excellent in impregnation property. In the present specification, the value of "viscosity of epoxy resin at 25 ℃" is a value measured by the method described in examples.

The adjustment of the components and physical properties in the epoxy resin can be performed by controlling the reaction, by controlling the purification step, or by adding another component. In this case, it is preferable to adjust the content of the epoxy resin component by controlling the reaction from the viewpoint of efficiently producing the epoxy resin.

< epoxy resin composition >

According to one aspect of the present invention, an epoxy resin composition is provided. The epoxy resin composition comprises the epoxy resin and a curing agent. The epoxy resin composition may further contain other epoxy resins, other resins, a curing accelerator, an organic solvent, additives, and the like as needed.

[ epoxy resin ]

The epoxy resin can be the above epoxy resin, and therefore, the description thereof is omitted here.

The content of the epoxy resin is preferably 30 to 99% by mass, more preferably 40 to 97% by mass, based on the solid content of the resin composition. When the content of the epoxy resin is 30% by mass or more, the performance of the epoxy resin is easily exhibited, and therefore, it is preferable. On the other hand, when the content of the epoxy resin is 99% by mass or less, the curing agent is preferably selected from a wide range of options. In the present specification, the term "solid content of the resin composition" refers to the total mass of components in the composition excluding a solvent described later. Therefore, when the resin composition does not contain a solvent, the entire mass of the composition is equal to the solid content.

[ other epoxy resins ]

The other epoxy resins are not particularly limited, and bisphenol epoxy resins such as bisphenol a epoxy resin and bisphenol F epoxy resin; biphenyl type epoxy resins such as biphenyl type epoxy resin and tetramethylbiphenyl type epoxy resin; novolac-type epoxy resins such as phenol novolac-type epoxy resin, cresol novolac-type epoxy resin, bisphenol a novolac-type epoxy resin, and biphenol novolac-type epoxy resin; triphenylmethane type epoxy resins; tetraphenylethane type epoxy resins; dicyclopentadiene-phenol addition reaction type epoxy resin; a phenol aralkyl type epoxy resin; naphthol novolac type epoxy resins, naphthol aralkyl type epoxy resins, naphthol-phenol co-condensed novolac type epoxy resins, naphthol-cresol co-condensed novolac type epoxy resins, diglycidyl ether oxynaphthalene, phosphorus atom-containing epoxy resins, and the like.

The other epoxy resins mentioned above may be used alone, or 2 or more kinds may be used in combination.

[ other resins ]

The other resin means a resin other than epoxy resin. The other resin may be a thermosetting resin or a thermoplastic resin. Specific examples of the other resin are not particularly limited, and examples thereof include polycarbonate resins, polyphenylene ether resins, polyethylene terephthalate resins, polybutylene terephthalate resins, polyethylene resins, polypropylene resins, polyimide resins, polyamideimide resins, polyetherimide resins, polyethersulfone resins, polyketone resins, polyetherketone resins, polyetheretherketone resins, and phenolic resins. These other resins may be used alone, or 2 or more of them may be used in combination.

[ curing agent ]

The curing agent is not particularly limited, and examples thereof include amine compounds, amide compounds, acid anhydride compounds, and phenol compounds.

Examples of the amine compound include ethylenediamine, diaminopropane, diaminobutane, diethylenetriamine, triethylenetetramine, 1, 4-cyclohexanediamine, isophoronediamine, diaminodicyclohexylmethane, diaminodiphenylmethane, diaminodiphenylsulfone, phenylenediamine (phenylenediamine), imidazole, BF 3-amine complex, dicyandiamide, guanidine derivative, and the like.

Examples of the amide compound include polyamide resins synthesized from a dimer of linolenic acid and ethylenediamine.

Examples of the acid anhydride compound include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride.

Examples of the phenol compound include a phenol novolac resin, a cresol novolac resin, an aromatic hydrocarbon formaldehyde resin-modified phenol resin, a dicyclopentadiene phenol addition-type resin, a phenol aralkyl resin, an α -naphthol aralkyl resin, a β -naphthol aralkyl resin, a biphenyl aralkyl resin, a trishydroxyphenylmethane resin, a tetrahydroxyphenylethane resin, a naphthol novolac resin, a naphthol-phenol co-condensed novolac resin, a naphthol-cresol co-condensed novolac resin, and an aminotriazine-modified phenol resin which is a copolymer of an amino group-containing triazine compound (melamine, benzoguanamine, etc.) and a phenol (phenol, cresol, etc.) and formaldehyde.

Of these, amine compounds and phenol compounds are preferably used, and diaminodiphenyl sulfone, phenol novolac resins, cresol novolac resins, phenol aralkyl resins, α -naphthol aralkyl resins, β -naphthol aralkyl resins, biphenyl aralkyl resins, and aminotriazine-modified phenol resins are more preferably used.

The cured products can be used alone, or in combination of 2 or more.

The content of the curing agent is preferably 1 to 70% by mass, more preferably 3 to 60% by mass, based on the solid content of the resin composition. When the content of the curing agent is 1% by mass or more, the selection of the curing agent is wide, and therefore, the content is preferable. On the other hand, a content of the curing agent of 70% by mass or less is preferable because the performance of the epoxy resin is easily exhibited.

[ curing accelerators ]

The curing accelerator has a function of accelerating curing. This can shorten the reaction time, prevent or reduce the generation of unreacted epoxy compounds, and the like.

The curing accelerator is not particularly limited, and examples thereof include phosphorus compounds, tertiary amines, imidazoles, organic acid metal salts, lewis acids, amine complexes, urea derivatives, and the like. Of these, imidazoles are preferably used. These curing accelerators may be used alone or in combination of 2 or more.

The content of the curing accelerator is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, based on the solid content of the epoxy resin composition. The content of the curing accelerator is preferably 0.1% by mass or more because curing can be accelerated. On the other hand, a content of the curing accelerator of 10% by mass or less is preferable because the pot life can be extended.

[ organic solvent ]

The organic solvent has a function of adjusting the viscosity of the epoxy resin composition. This improves the impregnation into the base material.

The organic solvent is not particularly limited, and ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; acetates such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, carbitol acetate, diethylene glycol monoethyl ether acetate, and propylene glycol monomethyl ether acetate; alcohols such as isopropyl alcohol, butyl alcohol, cellosolve, and butyl carbitol; aromatic hydrocarbons such as toluene and xylene; amides such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone. Among these, alcohols and ketones are preferably used, and butanol and methyl ethyl ketone are more preferably used. These solvents may be used alone, or 2 or more kinds may be used in combination.

The content of the organic solvent is preferably 10 to 60 parts by mass, and more preferably 20 to 50 parts by mass, per 100 parts by mass of the solid content of the epoxy resin composition. The content of the organic solvent is preferably 10 parts by mass or more because the viscosity can be reduced. On the other hand, the content of the organic solvent is preferably 60 parts by mass or less because nonvolatile components can be reduced.

[ additives ]

The additives that can be contained in the epoxy resin composition are not particularly limited, and examples thereof include inorganic fillers, reinforcing fibers, flame retardants, mold release agents, pigments, antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, conductivity imparting agents, and the like. These additives may be used alone, or 2 or more of them may be used in combination.

[ use ]

In one embodiment, the epoxy resin composition is applicable to applications such as fiber-reinforced composite materials, heat dissipation members, adhesives, paints, semiconductors, and printed circuit boards.

< cured product >

According to an aspect of the present invention, a cured product is provided. The cured product is obtained by curing the epoxy resin composition. The cured product has high thermal decomposition resistance.

The shape of the cured product is not particularly limited, and may be a sheet shape or a shape in which the cured product is impregnated with another material (a fibrous reinforcing material or the like).

The glass transition temperature (Tg) of the cured product is not particularly limited, but is preferably 160 to 350 ℃, more preferably 200 to 300 ℃, still more preferably 220 to 275 ℃, and particularly preferably 240 to 250 ℃. A glass transition temperature (Tg) of 160 ℃ or higher is preferable because heat resistance can be improved. On the other hand, a glass transition temperature (Tg) of 350 ℃ or lower is preferable because it is excellent in toughness. In the present specification, the value of "glass transition temperature (Tg)" is a value measured by the method described in examples.

The heat loss rate of the cured product at 300 ℃ is preferably 1.2% or less, more preferably 1.0% or less, further preferably 0.75% or less, particularly preferably 0.5% or less, and most preferably 0.001 to 0.5%. When the heat loss rate of the cured product is 1.2% or less, the thermal decomposition resistance is high, and the influence of volatilization of the cyclic compound is small, and the like, and therefore, it is preferable. In the present specification, the value of "heat loss rate" is a value measured by the method described in examples.

The curing temperature of the epoxy resin composition is preferably 50 to 250 ℃, and more preferably 70 to 200 ℃. The curing temperature is preferably 50 ℃ or higher because the curing reaction proceeds rapidly. On the other hand, when the curing temperature is 250 ℃ or lower, energy required for curing can be suppressed, and therefore, it is preferable.