WO2019058970A1

WO2019058970A1 - Epoxy resin, epoxy resin composition and cured product thereof

Info

Publication number: WO2019058970A1
Application number: PCT/JP2018/032894
Authority: WO
Inventors: 菜摘脇田; 達之熊野
Original assignee: 三菱瓦斯化学株式会社
Priority date: 2017-09-19
Filing date: 2018-09-05
Publication date: 2019-03-28
Also published as: TWI801416B; TW201920337A; JPWO2019058970A1; CN111032722A; CN111032722B; JP7216342B2

Abstract

Provided is an epoxy resin obtained by reacting epihalohydrin with a phenol-modified aromatic hydrocarbon-formaldehyde resin obtained by modifying an aromatic hydrocarbon formaldehyde resin with phenols, wherein the epoxy resin has a viscosity of 30,000 mPa·s or less at 25°C.

Description

Epoxy resin, epoxy resin composition and cured product thereof

The present invention relates to an epoxy resin, an epoxy resin composition and a cured product thereof.

In various products, an adhesive is used when joining parts. In general, adhesives have advantages and disadvantages in their performances such as adhesive strength and adhesion durability (performance of maintaining high adhesion for a long time) for each type. Under these circumstances, the adhesive is used in different types according to the application. For example, a flame retardant adhesive is used for electronic parts and OA equipment and fixtures, and a re-peelable type for masking tapes and surface protection films, etc. Adhesives are used.

Recently, the demand for high performance and high performance of adhesives has further increased, and it has adhesive power at normal temperature for heating in applications such as structural members, corrosion prevention of steel plates and resins, surface protection, etc. There is a need for adhesive compositions in which a curing reaction occurs and adhesive strength is increased.

For such problems, a thermosetting adhesive formed by blending an epoxy resin and a thermoplastic resin has been proposed. For example, Patent Document 1 proposes a thermosetting adhesive sheet formed of a thermosetting resin such as an epoxy resin and a thermoplastic resin such as a phenoxy resin and using an adhesive having normal temperature adhesiveness. There is. Moreover, in patent document 2, while it is a room temperature adhesiveness, the adhesive sheet which shows a favorable adhesive property by heat-hardening is proposed.

On the other hand, aromatic hydrocarbon formaldehyde resin, which is a type of thermoplastic resin, has adhesion of main resin such as epoxy resin, urethane resin, acrylic resin, etc. as non-reactive modifier and reactive modifier. It is widely used to improve properties. Specifically, an aromatic hydrocarbon formaldehyde resin is used as a tackifier for an adhesive or a pressure-sensitive adhesive, and is further used as a diluent for an epoxy resin or a plasticizer for a vinyl chloride resin. Patent Document 3 proposes a coating composition comprising an aromatic hydrocarbon formaldehyde resin, a predetermined bisphenol-type epoxy resin, a pigment, and an amine-based curing agent and having excellent adhesion and corrosion resistance, utilizing the above-mentioned properties. It is done.

On the other hand, epoxy resins derived from petroleum-based resins including aromatic hydrocarbon formaldehyde resins have been reported so far. For example, Patent Documents 4 and 5 propose epoxy resins obtained by reacting an aromatic hydrocarbon formaldehyde resin having a phenol skeleton with an epihalohydrin. Further, Patent Document 6 proposes an epoxy resin obtained by reacting an novolac type phenol resin obtained by reacting an aromatic hydrocarbon formaldehyde resin with a mixture of naphthol and phenol and an epihalohydrin.

JP-A-57-121079 Japanese Examined Patent Publication No. 01-031796 JP 09-020878 A JP, 2012-224706, A (patent 5716511) Unexamined-Japanese-Patent No. 2010-001487 (patent 5272963) JP, 2009-108147, A

However, the thermosetting adhesive sheet of Patent Document 1 is likely to cause phase separation between the thermosetting resin and the thermoplastic resin at the time of heat curing, and the adhesive properties after curing are not sufficient. Moreover, in the adhesive sheet of patent document 2, the process for making a solid resin compatible with a liquid epoxy resin on high temperature conditions is required, and it is inferior to productivity.

On the other hand, as in Patent Document 3, a coating composition obtained by mixing an aromatic hydrocarbon formaldehyde resin and an epoxy resin is required to further improve the adhesive strength.

Although the cured products of the epoxy resins of Patent Documents 4 to 6 are excellent in various physical properties such as flame retardancy and low hygroscopicity, further improvement in adhesion and adhesive strength is required. Moreover, since these epoxy resins are solid, their handleability is not sufficient.

Then, this invention is made | formed in view of the said situation, Comprising: It aims at providing the epoxy resin which can improve adhesiveness and a handleability, an epoxy resin composition, and its hardened | cured material.

As a result of intensive investigations, the present inventors have found that when the epihalohydrin is reacted with a specific phenols-modified aromatic hydrocarbon formaldehyde resin, an epoxy resin having a viscosity not higher than a specific value can be obtained, so that the above problems can be solved. The present invention has been completed.

That is, the present invention is as follows.
(1)
It is an epoxy resin obtained by reacting an epihalohydrin with a phenols-modified aromatic hydrocarbon formaldehyde resin obtained by modifying an aromatic hydrocarbon formaldehyde resin with phenols,
An epoxy resin having a viscosity of 30,000 mPa · s or less at 25 ° C.
(2)
The epoxy resin of (1) which has a viscosity of 100 mPa · s or more at 25 ° C.
(3)
Epoxy equivalent is 400 to 2000 g / eq. (1) or (2) epoxy resin.
(4)
An epoxy resin according to any one of (1) to (3), which has a weight average molecular weight of 300 to 1,000.
(5)
The epoxy resin according to any one of (1) to (4), wherein the weight average molecular weight of the phenols-modified aromatic hydrocarbon formaldehyde resin is 200 to 850.
(6)
The epoxy resin according to any one of (1) to (5), wherein the phenol-modified aromatic hydrocarbon formaldehyde resin contains a phenol-modified xylene formaldehyde resin.
(7)
The epoxy resin according to any one of (1) to (6), wherein the epihalohydrin is epichlorohydrin.
(8)
An epoxy resin composition comprising the epoxy resin of any one of (1) to (7) and a curing agent.
(9)
A cured product of the epoxy resin composition of (8).

According to the present invention, it is possible to provide an epoxy resin, an epoxy resin composition, and a cured product of the same, which can improve adhesion and handleability.

Hereinafter, modes for carrying out the present invention (hereinafter, simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for describing the present invention, and is not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of the gist of the present invention.

As used herein, the term "visco-adhesive" refers to a property having at least one of tackiness and adhesiveness.

[Epoxy resin]
The epoxy resin of the present embodiment is an epoxy resin obtained by reacting an epihalohydrin with a phenols-modified aromatic hydrocarbon formaldehyde resin (hereinafter, also simply referred to as a “phenols-modified resin”), and is 30, 30 at 25 ° C. It has a viscosity of 000 mPa · s or less. The epoxy resin of the present embodiment having the above-described configuration, for example, when reacted with a curing agent at normal temperature, the obtained cured product has excellent adhesion and is obtained by heating reaction with a curing agent. Bond strength of the cured product (heat cured product) is increased. This factor is that the viscosity of the epoxy resin of this embodiment is equal to or less than a specific value, the excellent flexibility (softness) which is an inherent characteristic of the aromatic hydrocarbon formaldehyde resin, and the heat which is a characteristic of the epoxy resin. Although it is thought that it is based on making balance and curability balance well, this invention is not limited at all by this factor. For this reason, the epoxy resin of this embodiment can be used suitably especially for adhesive agents. However, the epoxy resin of the present embodiment is not limited to the adhesive, and can be widely used, for example, in the fields of sealing material, connecting material, fixing material, information display (label, sticker, etc.) . In addition, since the epoxy resin of the present embodiment is in a liquid form at normal temperature, a process of dissolving it in a solvent for reaction with a curing agent becomes unnecessary, and the handling property is excellent. Furthermore, since it is not necessary to use a solvent, for example, it is possible to suppress the shrinkage of the cured product upon heat curing.

In addition, since the epoxy resin of the present embodiment has excellent flexibility and elongation in a cured form, it can follow, for example, the shape of a tacky-adhesive body, and has a sticky-adhesion having various shapes. It is applicable to the agent.

Since the epoxy resin of this embodiment is obtained using a phenols-modified aromatic hydrocarbon formaldehyde resin having a structure that is difficult to analyze and specify as a raw material, the epoxy resin is also specified by analyzing its structure It is difficult.

The viscosity at 25 ° C. of the epoxy resin of the present embodiment is as low as 30,000 mPa · s or less, and has a liquid form at normal temperature. The viscosity of the epoxy resin of the present embodiment is preferably 100 to 10,000 mPa · s, and more preferably 500 to 6,000 mPa · s, from the viewpoint of further improving adhesion and handling. preferable. When the viscosity at 25 ° C. is 100 mPa · s or more, dripping tends to be prevented, and when it is 30,000 mPa · s or less, the handling property is excellent.

The epoxy equivalent of the epoxy resin of this embodiment is 400 to 2000 g / eq. Is preferably 800 to 1900 g / eq. More preferably, it is 1000 to 1900 g / eq. It is further preferred that Epoxy equivalent is 400 g / eq. By being the above, it exists in the tendency which is further excellent in the handleability, and 2000 g / eq. By being the following, the further outstanding adhesiveness tends to be obtained, and when it is in the said range, adhesive property and a handleability can be improved with sufficient balance.

The weight average molecular weight of the epoxy resin of the present embodiment in gel permeation chromatography (GPC) in terms of polystyrene is preferably 300 to 1000, more preferably 300 to 900, and 400 to 800. Is more preferred. When the weight average molecular weight is 300 or more, the flexibility tends to be further improved, and when the weight average molecular weight is 1000 or less, the handleability tends to be further improved, and by being within the above range, Flexibility and handleability can be improved in a well-balanced manner.

The content of halogen in the epoxy resin of the present embodiment is preferably 2000 mass ppm or less, more preferably 1000 mass ppm or less, and still more preferably 750 mass ppm or less. The content of halogen can be measured by the method described in the examples.

[Phenols modified aromatic hydrocarbon formaldehyde resin]
In the present embodiment, the phenols-modified aromatic hydrocarbon formaldehyde resin refers to one obtained by modifying an aromatic hydrocarbon formaldehyde resin with phenols.

(Aromatic hydrocarbon formaldehyde resin)
The aromatic hydrocarbon formaldehyde resin of the present embodiment is obtained by reacting an aromatic hydrocarbon with formaldehyde. As an aromatic hydrocarbon, benzene, toluene, xylene, mesitylene, ethylbenzene, propylbenzene, decylbenzene, cyclohexylbenzene, biphenyl, methylbiphenyl, naphthalene, methylnaphthalene, dimethylnaphthalene, ethylnaphthalene, anthracene, methylanthracene, dimethylanthracene, At least one member selected from the group consisting of ethylanthracene and binaphthyl is mentioned, and from the viewpoint of being more excellent in tackiness, at least one member selected from the group consisting of xylene, toluene and mesitylene is preferable, and xylene is preferred. It is more preferable that That is, from the same viewpoint as described above, the aromatic hydrocarbon formaldehyde resin of the present embodiment is a xylene formaldehyde resin obtained by reacting xylene and formaldehyde, and a toluene formaldehyde resin obtained by reacting toluene and formaldehyde And at least one selected from mesitylene formaldehyde resins obtained by reacting mesitylene with formaldehyde, and more preferably xylene formaldehyde resin.

A commercial item may be used for the aromatic hydrocarbon formaldehyde resin of this embodiment, and you may prepare it by a well-known method. As a commercial item, for example, Fudot Co., Ltd. product "Nicanol Y-100" is mentioned. Examples of known methods include a method in which an aromatic hydrocarbon and formaldehyde are subjected to a condensation reaction in the presence of a catalyst by the method described in JP-B-37-5747 or the like.

(Phenols)
Examples of phenols include, but are not limited to, phenol, cresol (eg, ortho-cresol, meta-cresol, and para-cresol), xylenol (eg, 2,6-xylenol, 3,5-xylenol, 2,3-xylenol, 2 , 5-xylenol, 2,4-xylenol, and 3,4-xylenol), butylphenol (eg, p-tert-butylphenol), octylphenol, nonylphenol, cardanol, and at least one member selected from the group consisting of terpene phenols Is preferred.

The phenols-modified aromatic hydrocarbon formaldehyde resin of the present embodiment contains at least one selected from a phenols-modified xylene formaldehyde resin, a phenols-modified toluene formaldehyde resin, and a phenols-modified mesitylene formaldehyde resin from the viewpoint of flexibility. Is preferable, and it is more preferable to contain phenols modified | denatured xylene formaldehyde resin.

A commercial item may be used for the phenols modified aromatic hydrocarbon formaldehyde resin of this embodiment, and you may prepare it by a well-known method. As a commercial item, for example, Fudot Co., Ltd. product "Xystar P-15" is mentioned. As a known method, for example, as described in JP-A-2003-119234, JP-A-2007-297610, International Publication 2013-191012 etc., an aromatic hydrocarbon formaldehyde resin and a phenol compound are used as an acidic catalyst. It can be produced by condensation reaction below.

[Physical properties of phenol-modified aromatic hydrocarbon formaldehyde resin]
The hydroxyl value (OH value) of the phenols-modified aromatic hydrocarbon formaldehyde resin is preferably 40 to 150 mg KOH / g, more preferably 40 to 140 mg KOH / g, and 40 to 120 mg KOH / g. More preferable. When the hydroxyl value is 40 mg KOH / g or more, a more sufficient tackiness tends to be obtained, and when it is 150 mg KOH / g or less, the viscosity of the produced epoxy resin tends to be further reduced. . The hydroxyl value can be measured by the method according to JIS-K1557.

When the hydroxyl value of the phenols-modified aromatic hydrocarbon formaldehyde resin is in the above range, the resulting epoxy resin is liquefied, the characteristics as an epoxy resin (such as thermosetting), and the phenols-modified aromatic hydrocarbon formaldehyde It tends to be able to ensure the characteristics (flexibility etc.) of the resin in a well-balanced manner. When the liquid aromatic hydrocarbon formaldehyde resin is modified with phenols to increase the density of the phenolic hydroxyl group, the phenol modified aromatic hydrocarbon formaldehyde resin tends to be an insoluble and insoluble solid. As a result, the resulting epoxy resin also becomes solid and tends to lose its flexibility, which is an inherent property of aromatic hydrocarbon formaldehyde resins (especially xylene formaldehyde resins). On the other hand, it is necessary to have a certain amount of density of the phenolic hydroxyl group in the phenols-modified aromatic hydrocarbon formaldehyde resin from the viewpoint of securing characteristics (for example, thermosetting etc.) as the epoxy resin. For this reason, it is preferable that the hydroxyl value is in the above range from the viewpoint of securing in a well-balanced manner the characteristics (thermosetting property etc.) as liquefaction and epoxy resin and the properties (flexibility etc.) of aromatic hydrocarbon formaldehyde resin .

The weight average molecular weight of the phenol-modified aromatic hydrocarbon formaldehyde resin of the present embodiment in GPC is, in terms of polystyrene, preferably 200 to 850, more preferably 200 to 750, and 300 to 700. Is more preferred. When the weight average molecular weight is 200 or more, a flexible epoxy resin tends to be obtained, and when it is 850 or less, an epoxy resin having a still lower viscosity tends to be obtained.

The viscosity at 25 ° C. of the phenols-modified aromatic hydrocarbon formaldehyde resin of the present embodiment is preferably 100 to 30,000 mPa · s, more preferably 100 to 10,000 mPa · s, and 500 to 6 It is more preferable that it is 1,000 mPa · s. When the viscosity at 25 ° C. is 100 mPa · s or more, dripping of the obtained epoxy resin tends to be prevented, and when it is 30,000 mPa · s or less, the viscosity of the obtained epoxy resin is further lowered. It tends to be excellent in handleability.

[Epihalohydrin]
Examples of the epihalohydrin used in the present embodiment include epichlorohydrin, epibromohydrin, epiiodohydrin and the like, and among these, from the viewpoint of reactivity, epichlorohydrin is preferable.

[Method of producing epoxy resin]
Hereinafter, the manufacturing method of the epoxy resin of this embodiment is demonstrated in detail. The epoxy resin of the present embodiment is obtained by reacting a phenols-modified aromatic hydrocarbon formaldehyde resin with an epihalohydrin.

The amount of epihalohydrin used is preferably 0.8 to 10.0 mol from the viewpoint of the yield of the epoxy resin obtained, relative to 1 mol of hydroxyl groups of the phenols-modified aromatic hydrocarbon formaldehyde resin, and it is preferably 0. More preferably, it is 9 to 8.0 mol.

The reaction of the phenols-modified aromatic hydrocarbon formaldehyde resin with the epihalohydrin is carried out, for example, in the presence of an alkali metal hydroxide. The alkali metal hydroxide is not particularly limited, and includes, for example, sodium hydroxide and / or potassium hydroxide. These alkali metal hydroxides may be used alone or in combination of two or more. Among these, sodium hydroxide is preferable from the viewpoint of economy. The amount of the alkali metal hydroxide used is not particularly limited, but from 2 to 50 parts by mass with respect to 100 parts by mass of the phenols-modified aromatic hydrocarbon formaldehyde resin from the viewpoint of obtaining the effect of completing the ring closure reaction. It is preferably 3 to 30 parts by mass. The alkali metal hydroxide may be charged at once into the reaction system, or may be charged successively.

The method of reaction is not particularly limited, and for example, after dissolving phenols-modified aromatic hydrocarbon formaldehyde resin in an excess of epihalohydrin, in the presence of an alkali metal hydroxide such as sodium hydroxide, at 60 to 120 ° C. The reaction may be for 0.5 to 10 hours.

In the reaction of the phenols-modified aromatic hydrocarbon formaldehyde resin and the epihalohydrin, if necessary, a solvent inert to the reaction may be used. Inert solvents include, for example, hydrocarbons such as heptane and toluene, and alcohols such as ethanol, propanol, isopropyl alcohol, and butanol. These solvents can be used alone or in combination of two or more.

[Epoxy resin composition]
The epoxy resin composition of the present embodiment contains the epoxy resin of the present embodiment and a curing agent, and may further contain other epoxy resin, a curing accelerator, and the like as long as the effects of the present invention are not impaired. It does not have to be included.

There is no restriction | limiting in particular as a curing agent used by this invention, Generally what is generally known as an epoxy resin curing agent can be used. For example, an amine curing agent, an acid anhydride curing agent, a phenol curing agent and the like can be mentioned.

The amine-based curing agent is not particularly limited as long as it is a curing agent having an active hydrogen derived from an amino group capable of reacting with the glycidyl group contained in the epoxy resin of the present embodiment. Ethylene diamine, diethylene triamine and the like); aliphatic polyamine compounds containing an aromatic ring (for example, xylylene diamine and the like); alicyclic polyamine compounds (for example, mensene diamine and the like). These polyamine compounds may be mixed without being modified, or may be mixed after being subjected to modification such as amide modification by reaction with a compound containing a carboxyl group.

The acid anhydride-based curing agent is not particularly limited. For example, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, dodecenyl succinic anhydride, polyadipic anhydride Etc.

The phenolic curing agent is not particularly limited. For example, bisphenol A, bisphenol F, 4,4'-dihydroxydiphenylmethane, bisphenol A novolac, o-cresol novolac, xylenol novolac, hydroquinone, resorcinone, catechol, 1,6 And dihydroxynaphthalene and 2,6-dihydroxynaphthalene.

The curing agents listed above may be used alone or in combination of two or more. When combining two or more, those content ratios may also be arbitrary. Moreover, it is 5.0-15.0 mass with respect to 100 mass parts of total amounts of the epoxy resin of this embodiment and other epoxy resins (When it does not contain other epoxy resins, 100 mass parts of epoxy resins of this embodiment) It may be a part grade.

The curing accelerator is not particularly limited, but, for example, high melting point dispersion type latent accelerators such as dicyandiamide, amine addition type accelerator in which amine is added to epoxy resin etc .; imidazole type, phosphorus type, phosphine type accelerator The microcapsule type latent accelerator which surface-coated with the polymer; Amine salt type latent hardening accelerator etc. are mentioned. The content of these curing accelerators is not particularly limited as long as the effects of the present invention are not impaired. For example, it is about 0.1 to 2.0 parts by mass with respect to 100 parts by mass of the epoxy resin. May be

Other epoxy resins may be any of epoxy resins derived from alicyclic alcohols, epoxy resins derived from aromatic alcohols (phenols), and alicyclic epoxy resins. Specifically, an epoxy resin having a glycidyl ether moiety derived from bisphenol A type, an epoxy resin having a glycidyl ether moiety derived from bisphenol F type, a cycloaliphatic epoxy resin having an epoxycyclohexyl ring in the molecule Etc. Among these, an epoxy resin having a glycidyl ether moiety derived from bisphenol A type is particularly preferable from the viewpoint of viscosity and availability. When the epoxy resin composition of the present embodiment contains another epoxy resin, the content of the other epoxy resin may be about 30 to 200 parts by mass with respect to 100 parts by mass of the epoxy resin of the present embodiment. .

The compounding amount of the total of the epoxy resin of the present embodiment and the other epoxy resin in the epoxy resin composition of the present embodiment is 0.3 to 1.5 as a ratio of epoxy equivalent of the epoxy resin to active hydrogen equivalent of the curing agent. Is preferably, and more preferably 0.4 to 1.2. When the amount of the epoxy resin is in the above range, the degree of crosslinking of the cured product can be made to a sufficient degree.

In the epoxy resin composition of the present embodiment, a filler, a modifying component such as a plasticizer, a reactive or non-reactive diluent, a dispersant, or the like depending on the use, as long as the effects of the embodiment of the present invention are not impaired. A fluid preparation component such as a modification imparting agent, a component such as a pigment, and an additive such as a repelling inhibitor, a leveling agent, an antifoaming agent, and an ultraviolet absorber can be used.

The cured product of the epoxy resin composition of the present embodiment can be obtained by various known methods, and may be cured at normal temperature or may be cured by heating. In the case of curing at normal temperature, the curing time may be about 1 day to 5 days. The heating conditions may be appropriately selected according to the epoxy resin, each component in the composition containing the resin, and the content of the resin and each component, and preferably 90 to 150 ° C. to 60 ° C. to 120 ° C. It is selected in the range of minutes, more preferably in the range of 100 minutes to 140 minutes at 70 to 90.degree.

The present invention will be described in more detail by the following Examples and Comparative Examples, but the present invention is not limited by the following Examples. In addition, the evaluation method employ | adopted by the present Example and the comparative example is as follows.

<Epoxy equivalent>
The epoxy equivalent of the epoxy resin was measured in accordance with JIS-K7236.

<Halogen content>
A 0.5 g sample was weighed in an Erlenmeyer flask, and 20 mL of 1 N KOH was added and completely dissolved. Thereafter, a cooling pipe was attached to the Erlenmeyer flask, and the mixture was boiled under reflux for 1 hour in an oil bath. 1N KOH was prepared by previously weighing 56.1 g of potassium hydroxide in a 1 L measuring flask and dissolving it in a mixed solution of 500 mL of ethanol and 500 mL of dioxane. Then, the Erlenmeyer flask was cooled and 12 mL of acetic acid was added. Then, titration was performed with a potentiometric titrator using a 0.001 N silver nitrate standard solution. The content of hydrolyzable halogen in the sample was calculated by the following equation.
Hydrolyzable halogen content (ppm) = ((A−B) × 35.5 × N × F × 1000) / W
In the above formula, A: amount of 0.001 N silver nitrate standard solution required for titration of sample (mL), B: amount of 0.001 N silver nitrate standard solution needed for titration of blank test (mL), N: silver nitrate standard solution Normality, F: titer of silver nitrate standard solution, W: sample amount (g).

<Viscosity>
It measured according to JISK6833 using a rotational viscometer.

<Weight average molecular weight>
The weight average molecular weight (Mw) in terms of polystyrene was determined by GPC analysis. The equipment and the like used for the analysis and the analysis conditions were as follows.
Device: Shodex GPC-101 (product name of Showa Denko KK)
Column: Shodex KF-801 × 2, KF-802.5, KF-803L
Eluent: tetrahydrofuran Flow rate: 1.0 ml / min.
Column temperature: 40 ° C
Detector: RI (differential refraction detector)

<Tensile shear adhesive strength and cohesive failure rate>
The tensile shear adhesive strength (MPa) employed a 1.6 × 25 × 100 mm aluminum plate as a test piece, and conducted a test at an applied area of 25 × 10 mm and a tensile speed of 2 mm / min. After measuring the shear bond strength (MPa), the fracture state of each sample was visually observed to determine the cohesive failure rate of the cured product. The adhesion performance was evaluated based on the following evaluation criteria based on the obtained cohesive failure rate. The higher the cohesive failure rate, the higher the reliability of the adhesion performance.
A: 100% cohesive failure rate
B: Cohesive failure rate 70% to less than 100% C: Cohesive failure rate 30% to less than 70% D: Cohesive failure rate 1% to less than 30% E: Cohesive failure rate 0%

<Flexibility>
In accordance with JIS K5600-5-1, a steel plate having a cured film formed on a core rod was wound and evaluated based on the following criteria.
○: 2 mm diameter core rod with no cracking or peeling in the cured film ×: 32 mm diameter core rod with cracking or peeling in the cured film

<Adhesiveness>
A cross cut test was conducted in accordance with JIS K5600-5-6, and evaluated based on the following criteria.
○: no peeling of the coating is observed :: peeling of the coating is partially observed ×: the coating is almost peeled off

<Growth rate>
After curing the epoxy resin composition under the curing conditions shown in Table 1, test pieces are prepared, and in accordance with JIS K7161, a tensile speed of 5 mm / min. The elongation rate was measured by

Example 1
In a round-bottomed flask with an internal volume of 500 mL equipped with a stirrer, thermometer, and dropping funnel, a phenol-modified aromatic hydrocarbon formaldehyde resin (a xylene resin manufactured by Fudoh Co., Ltd., “Zystar P-15 (OH number 47 mg KOH / g , Weight average molecular weight (Mw) 474) ") 100 g of epichlorohydrin and 40 g of isopropyl alcohol are charged, heated to 40 ° C. and uniformly dissolved, and then 8.0 g of 50% by mass aqueous solution of sodium hydroxide Was dripped over 30 minutes. After completion of the dropwise addition, the temperature was raised and maintained at 60 ° C. for 1 hour to complete the reaction, and the by-product salt and excess sodium hydroxide were removed by water washing. The product was then distilled off excess epichlorohydrin and isopropanol under reduced pressure to give a crude epoxy resin. The crude epoxy resin was dissolved in 150 g of methyl isobutyl ketone, 0.6 g of a 50% by mass aqueous solution of sodium hydroxide was added, and the mixture was reacted again at a temperature of 65 ° C. for 2 hours. Thereafter, an aqueous solution of monobasic sodium phosphate was added to the reaction solution to neutralize excess sodium hydroxide, and then washed with water to remove by-product salts. Subsequently, methyl isobutyl ketone was completely removed under reduced pressure to obtain the desired epoxy resin A. The epoxy equivalent of the obtained epoxy resin A was 1805 g / eq. The chlorine content in the epoxy resin A was 97 mass ppm, the viscosity at 25 ° C. was 3980 mPa · s, and the weight average molecular weight was 492.

Example 2
Phenolics-modified aromatic hydrocarbon formaldehyde resin (Fude Co., Ltd. xylene resin, “Zystar P-15”), phenols-modified aromatic hydrocarbon formaldehyde resin (Fudoh Co., Ltd. xylene resin, “Zystar P -20 "(OH number 86 mg KOH / g, weight average molecular weight (Mw) 485) 100 g was used, the preparation amount of epichlorohydrin was changed from 48 g to 88 g, 50 mass% sodium hydroxide at the first time Example 1 and Example 1 except that the amount of dropwise addition of the aqueous solution was changed from 8.0 g to 14.8 g, and that of the second 50 mass% sodium hydroxide aqueous solution was changed from 0.6 g to 1.1 g. In the same manner, an epoxy resin B was obtained, and in the obtained epoxy resin B, the epoxy equivalent is 1193 g / eq. The chlorine content is 740 mass ppm, and a viscosity at 25 ° C., a 4790mPa · s, a weight average molecular weight was 700.

Comparative Example 1
Phenolic aromatic hydrocarbon formaldehyde resin (Fudot Co., Ltd. xylene resin, “Zystar GP-” in place of phenol-modified aromatic hydrocarbon formaldehyde resin (Fuido Co., Ltd. xylene resin, “Zystar P-15”) 100 (OH number 289 mg KOH / g), weight average molecular weight (Mw 1022 ′ ′) 39 g was used, the preparation amount of epichlorohydrin was changed from 48 g to 114 g, 50 mass% sodium hydroxide at the first time Example 1 and Example 1 except that the dropping amount of the aqueous solution was changed from 8.0 g to 24.7 g, and the dropping amount of the second 50 mass% sodium hydroxide aqueous solution was changed from 0.6 g to 1.4 g Epoxy resin C was obtained in the same manner. The epoxy equivalent of the obtained epoxy resin C is 272 g / eq. The chlorine content in the epoxy resin C was 728 ppm by mass, solid at 25 ° C., and the weight average molecular weight was 1622.

Examples 3 to 5 and Comparative Examples 2 to 4
Epoxy resins AC obtained in Examples 1 and 2 and Comparative Example 1 as epoxy resins, bisphenol A type epoxy resin (Mitsubishi Chemical Corporation product "Epicoat 828"), Daicel product "Celoxide 2012 P", Thermoplastic resin A (Fudot Co., Ltd. product “Zystar P-15”, ie, phenols modified aromatic hydrocarbon formaldehyde resin used in Example 1), curing agent (Mitsubishi Gas Chemical Co., Ltd. product “metaxylene diamine” Each epoxy resin composition was mix | blended in the ratio (the number in a table is a mass part) shown in following Table 1 using each. In Comparative Example 4, when mixing the solid epoxy resin C and the low-viscosity celoxide 2021 P, there is a problem in the handling property since a process of heating to 130 ° C. to be compatible is necessary. Using these epoxy resin compositions, curing was performed under the curing conditions shown in Table 1, and the above-described evaluation tests were performed. The results are shown in Table 1.

In Comparative Example 2 using an epoxy resin ("Epicoat 828") generally used for adhesives, the shear strength was reduced as compared with Examples 3 and 4. This is presumed to be due to the fact that Comparative Example 2 does not have an aromatic ring nucleus (xylene nucleus) derived from a phenols-modified aromatic hydrocarbon formaldehyde resin, and the flexibility is insufficient. The present invention is not limited at all by this assumption. Further, in Comparative Example 3 in which a phenol-modified xylene resin which was not epoxidized was used, and Comparative Example 4 in which a solid epoxy resin C was used, the adhesive strength was not sufficient as compared with Examples 2 and 3.

This application is based on Japanese Patent Application (Japanese Patent Application No. 2017-178810) filed on September 19, 2017, the contents of which are incorporated herein by reference.

Claims

It is an epoxy resin obtained by reacting an epihalohydrin with a phenols-modified aromatic hydrocarbon formaldehyde resin obtained by modifying an aromatic hydrocarbon formaldehyde resin with phenols,
An epoxy resin having a viscosity of 30,000 mPa · s or less at 25 ° C.
The epoxy resin according to claim 1, having a viscosity of 100 mPa · s or more at 25 ° C.
Epoxy equivalent is 400 to 2000 g / eq. The epoxy resin according to claim 1 or 2, which is
The epoxy resin according to any one of claims 1 to 3, which has a weight average molecular weight of 300 to 1,000.
The epoxy resin according to any one of claims 1 to 4, wherein the weight average molecular weight of the phenols-modified aromatic hydrocarbon formaldehyde resin is 200 to 850.
The epoxy resin according to any one of claims 1 to 5, wherein the phenols-modified aromatic hydrocarbon formaldehyde resin contains a phenols-modified xylene formaldehyde resin.
The epoxy resin according to any one of claims 1 to 6, wherein the epihalohydrin is epichlorohydrin.
An epoxy resin composition comprising the epoxy resin according to any one of claims 1 to 7 and a curing agent.
A cured product of the epoxy resin composition according to claim 8.