WO2016117298A1 - Crystalline polymorphism of inclusion compound, curable composition containing same, and cured product - Google Patents

Abstract

Provided is a novel crystalline polymorphism of an inclusion compound (molar ratio 1:1) comprising 5-hydroxyisophthalic acid and 2-ethyl-4-methyl imidazole. A novel crystalline polymorphism of an inclusion compound (molar ratio 1:1) comprising 5-hydroxyisophthalic acid and 2-ethyl-4-methyl imidazole can be obtained by recrystallizing crystals obtained using conventional methods, said inclusion compound having refraction peaks at diffraction angles (2θ) of 14.68º, 16.96º, 20.36º, 23.48º, 25.92º, 26.52º, 27.84º, and 29.56º, in a powder X-ray diffraction pattern measured using a CuKα ray.

Description

Crystalline polymorph of inclusion compound, curable composition containing the same, and cured product

The present invention relates to a novel crystal polymorph of an inclusion compound, a curable composition containing the same, and a cured product. This application claims priority to Japanese Patent Application No. 2015-8063 filed on January 19, 2015, the contents of which are incorporated herein by reference.

Epoxy resins are used in a wide range of applications such as paints, electronic materials, adhesives and the like because their cured products have excellent performance in terms of mechanical properties, electrical properties, thermal properties, and the like.

In recent years, especially in electronic materials, there is a need for a one-component curing composition that achieves both storage stability at room temperature and below and short-term curing, so a latent curing agent or latent curing mixed with an epoxy resin is required. Various accelerators have been developed.

For example, in Patent Document 1, when an inclusion compound containing at least an isophthalic acid compound and an imidazole compound is used as a curing catalyst, curing of the epoxy resin composition at a low temperature is suppressed and one-component stability is improved. It is described that the resin is effectively cured by heat treatment.

Further, Patent Document 2 discloses 5-hydroxyisophthalic acid (hereinafter sometimes abbreviated as HIPA) and 2-ethyl-4-methylimidazole (hereinafter abbreviated as 2E4MZ) as a curing catalyst for the epoxy resin composition for prepreg. Are included) in a molar ratio of 1: 1.

WO2008 / 074427 Pamphlet JP 2013-213168 A

None of the clathrate compounds obtained in the above-mentioned patent documents describes the crystal polymorphism, and the storage stability of the epoxy resin composition containing the clathrate compound was not sufficient. An object of the present invention is to provide a novel crystal polymorph of an inclusion compound of 5-hydroxyisophthalic acid and 2-ethyl-4-methylimidazole.

As a result of intensive studies to solve the above problems, the present inventors have found that a new clathrate compound (hereinafter, referred to as “crystal clathrate compound”) is obtained by recrystallizing a conventional clathrate compound (hereinafter sometimes abbreviated as crystal A). Has been found to give an epoxy resin composition having more excellent one-component stability, and has led to the completion of the present invention.

That is, the present invention
(1) Powder X-ray diffraction measured by CuKα rays, which is a crystalline polymorph of an inclusion compound (molar ratio 1: 1) consisting of 5-hydroxyisophthalic acid and 2-ethyl-4-methylimidazole In the pattern at diffraction angles (2θ) of 14.68 °, 16.96 °, 20.36 °, 23.48 °, 25.92 °, 26.52 °, 27.84 ° and 29.56 °. A polymorph with crystallographic peaks,
(2) In powder X-ray diffraction patterns measured with CuKα rays, diffraction angles of 16.32 °, 18.56 °, 21.84 °, 22.52 °, 23.84 ° and 27.56 ° ( (1) includes a step of recrystallizing a crystal of an inclusion compound (molar ratio 1: 1) comprising 5-hydroxyisophthalic acid and 2-ethyl-4-methylimidazole having a diffraction peak at 2θ). And (3) from an alcohol solution or suspension containing 5-hydroxyisophthalic acid and 2-ethyl-4-methylimidazole, 5-hydroxyisophthalic acid and 2-ethyl-4- The present invention relates to a method for producing a crystalline polymorph according to (1), which comprises a step of crystallizing an inclusion compound (molar ratio 1: 1) comprising methylimidazole.

further,
(4) Curing agent for epoxy resin or curing accelerator for epoxy resin containing the crystal polymorph as described in (1), and (5) Epoxy resin and curing agent for epoxy resin or epoxy resin as described in (4) The present invention relates to a curable composition containing a curing accelerator and a cured product thereof.

The clathrate compound comprising HIPA and 2E4MZ of the present invention is a novel crystalline polymorph, and the epoxy resin composition containing the clathrate compound of the present invention is compared with the epoxy resin composition containing the conventional clathrate compound. In terms of one-component stability.

2 is a powder X-ray diffraction pattern (sometimes referred to as XRD) of the clathrate compound obtained in Example 1. FIG. FIG. 2 is a graph showing the results of thermogravimetry / differential scanning calorimetry (sometimes referred to as TG-DSC) of the clathrate compound obtained in Example 1. 3 is a configuration diagram of crystals drawn based on the result of X-ray crystal structure analysis of the clathrate compound obtained in Example 1. FIG. 2 is a powder X-ray diffraction pattern (sometimes referred to as XRD) of the clathrate compound obtained in Comparative Example 1. FIG. FIG. 4 is a diagram showing the results of measuring TG-DSC of the clathrate compound obtained in Comparative Example 1. 2 is a configuration diagram of crystals drawn based on the results of X-ray crystal structure analysis of an inclusion compound obtained in Comparative Example 1. FIG. It is a figure which shows the result of having performed the differential scanning calorimetry (it may be called DSC) of the epoxy resin composition obtained in Example 10 and Comparative Examples 2-3.

The inclusion compound comprising HIPA of the present invention and 2E4MZ (HIPA: 2E4MZ is 1: 1 in molar ratio) has diffraction angles (2θ) of 14.68 °, 16.96 °, 20.36 ° in powder X-ray diffraction. , 23.48 °, 25.92 °, 26.52 °, 27.84 ° and 29.56 °.

Here, an inclusion compound is a compound composed of two or more chemical species that can exist stably alone, and one of these chemical species creates a molecular-scale space, and the shape and dimensions in that space. Is a compound having a specific crystal structure by incorporating (inclusion) the other chemical species with the first requirement that The chemical species on the side that provides the space is called the host, and the chemical species on the side of the inclusion is called the guest. The host and guest are bonded by an interaction other than a covalent bond such as a hydrogen bond, van der Waals force, or ionic bond. It can be said that an ionic crystal or salt structure is formed in the case of an ion-binding clathrate compound.

The crystal B of the present invention can be obtained, for example, by recrystallizing the crystal A obtained by the method described in Patent Document 2 in a solvent. Crystal A or the like may be completely dissolved in a solvent, or a solution obtained by partially dissolving the crystal A may be used. Preferred examples of the solvent used for recrystallization include alcohols having 1 to 4 carbon atoms. Specific examples of such alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2 -Methyl-1-propanol, 2-butanol, 2-methyl-2-propanol and the like can be exemplified, and methanol can be preferably exemplified. The temperature at which the crystals A and the like are dissolved is not particularly limited and may be any temperature as long as it is in the range of room temperature to the boiling point of the solvent. The method of recrystallization is not particularly limited, and specifically, a method of dissolving by heating and then cooling, a method of dissolving in a solvent and gradually distilling off the solvent to precipitate crystals, Examples thereof include a method of adding a poor solvent, a method of combining these, and the like. Among them, a method of precipitating crystals by gradually distilling the solvent to a saturation concentration or less after dissolving the crystals is preferable. After the crystals are precipitated, the target crystals B are obtained by filtering and drying.

The crystal B of the present invention can also be obtained by crystallization by mixing about 1 mol of HIPA and about 1 mol of 2E4MZ in a solvent, heating and then cooling. Examples of the solvent used for crystallization include alcohols having 1 to 4 carbon atoms exemplified above, and methanol is particularly preferable. HIPA and 2E4MZ are dissolved or suspended in a solvent, but both are preferably dissolved in the solvent. When dissolved in a solvent, the entire amount does not need to be dissolved in the solvent, and at least a part of the amount only needs to be dissolved in the solvent.
The method of mixing HIPA, 2E4MZ and the solvent is not particularly limited, but HIPA and 2E4MZ may be added simultaneously to the solvent, 2E4MZ may be added to the mixture of HIPA and the solvent, and a mixture of the solvent and 2E4MZ. HIPA may be added. Among them, a method of adding a 2E4MZ solution dissolved in the above solvent dropwise to a mixture of HIPA and a solvent is preferable. The heating temperature may be around the boiling point of the solvent to be used, and it is preferably heated to reflux. Heating may be performed from the time of mixing HIPA, 2E4MZ, and the solvent, or after mixing.
In the step after heating, crystals may be precipitated by simply stopping the heating, but it is preferable to leave at room temperature overnight after heating. After the crystals are precipitated, the target crystals B are obtained by filtering and drying.

The structure of the clathrate compound obtained can be confirmed by known analytical means such as NMR, solid NMR spectrum, infrared absorption spectrum (IR), mass spectrum, X-ray diffraction (XRD) pattern, X-ray structure analysis. The composition of the clathrate compound obtained can be confirmed by thermal analysis, 1H-NMR spectrum, high performance liquid chromatography (HPLC), TG-DSC, elemental analysis or the like.

The curable composition of the present invention is a composition containing an epoxy resin and crystal B as a curing agent or a curing accelerator.

As the epoxy resin, an epoxy resin having two or more epoxy groups in one molecule (hereinafter also referred to as “polyfunctional epoxy resin”) is preferably used. Here, the epoxy resin means a prepolymer before curing, and includes monomers and oligomers.
In particular,
At least one phenolic compound selected from the group consisting of phenol compounds such as phenol, cresol, xylenol, resorcin, catechol, bisphenol A, bisphenol F, and naphthol compounds such as α-naphthol, β-naphthol, and dihydroxynaphthalene; Novolak type epoxy resins such as phenol novolak type epoxy resins and orthocresol novolak type epoxy resins obtained by epoxidizing novolak resins obtained by condensation or cocondensation with aliphatic aldehyde compounds such as acetaldehyde and propionaldehyde in the presence of an acidic catalyst ;
A triphenylmethane type epoxy resin obtained by epoxidizing a triphenylmethane type phenol resin obtained by condensation or cocondensation of the phenolic compound with an aromatic aldehyde compound such as benzaldehyde or salicylaldehyde under an acidic catalyst;
A copolymerization type epoxy resin obtained by epoxidizing a novolak resin obtained by cocondensation of the above phenol compound and naphthol compound with an aldehyde compound under an acidic catalyst;
Diphenylmethane type epoxy resins which are diglycidyl ethers such as bisphenol A and bisphenol F;
A biphenyl type epoxy resin which is a diglycidyl ether of an alkyl-substituted or unsubstituted biphenol;
A stilbene type epoxy resin which is a diglycidyl ether of a stilbene phenol compound;
A sulfur atom-containing epoxy resin which is a diglycidyl ether such as bisphenol S;
Epoxy resins that are glycidyl ethers of alcohols such as butanediol, polyethylene glycol, polypropylene glycol;
Glycidyl ester type epoxy resin of polyvalent carboxylic acid compounds such as phthalic acid, isophthalic acid and tetrahydrophthalic acid;
A glycidylamine type epoxy resin in which active hydrogen bonded to a nitrogen atom such as aniline, diaminodiphenylmethane, isocyanuric acid or the like is substituted with a glycidyl group;
A dicyclopentadiene type epoxy resin obtained by epoxidizing a co-condensation resin of dicyclopentadiene and a phenol compound;
Vinylcyclohexene diepoxide obtained by epoxidizing an olefin bond in the molecule, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 2- (3,4-epoxy) cyclohexyl-5,5-spiro ( 3,4-epoxy) cycloaliphatic epoxy resins such as cyclohexane-m-dioxane;
Glycidyl ether of paraxylylene-modified phenolic resin;
Glycidyl ether of metaxylylene-modified phenolic resin;
Glycidyl ether of terpene-modified phenolic resin;
Glycidyl ether of dicyclopentadiene-modified phenolic resin;
Glycidyl ether of cyclopentadiene modified phenolic resin;
Glycidyl ether of polycyclic aromatic ring-modified phenolic resin;
A naphthalene type epoxy resin which is a glycidyl ether of a naphthalene ring-containing phenol resin;
Halogenated phenol novolac epoxy resin;
Hydroquinone type epoxy resin;
Trimethylolpropane type epoxy resin;
A linear aliphatic epoxy resin obtained by oxidizing an olefinic bond with a peracid such as peracetic acid;
Diphenylmethane type epoxy resin;
And an aralkyl type epoxy resin which is an epoxidized product of an aralkyl type phenol resin such as a phenol aralkyl resin and a naphthol aralkyl resin. These may be used alone or in combination of two or more.

The blending ratio of the crystal B contained in the curable composition of the present invention may be the same as the amount that 2E4MZ is normally contained in the epoxy resin composition in terms of 2E4MZ contained in the crystal, Specifically, the range of 0.1 to 10 parts by weight is preferable with respect to 100 parts by weight of the epoxy resin contained in the composition, and the range of 1 to 5 parts by weight is more preferable.

If necessary, the curable composition of the present invention may contain other curing agents, other curing accelerators, plasticizers, organic solvents, reactive diluents, extenders, fillers, reinforcing agents, pigments, flame retardants. Various additives such as an agent, a thickener and a release agent can be blended.

The curable composition of the present invention and the cured product thereof are used in applications such as adhesives, semiconductor encapsulants, laminated boards for printed wiring boards, varnishes, powder paints, casting materials, inks, fiber reinforced composite materials, etc. It can be preferably used.

The curable composition of the present invention can be obtained by directly mixing the epoxy resin, the crystal B, and an additive blended as necessary, or mixing them in a solvent. Mixing may be performed by heating to about 60 to 100 ° C. so that a sufficient mixed state is formed. The mixing means is not particularly limited, and for example, a planetary stirrer, an extruder, a homogenizer, a mechanochemical stirrer, two rolls, a Banbury mixer and the like are preferably used.

The cured product can be obtained by heat-treating the curable composition, and examples thereof include a cured film obtained by painting or coating the composition on a substrate. The heat treatment can be performed at 50 to 250 ° C. for 15 minutes to 50 hours, preferably at 60 to 200 ° C. for 2 to 24 hours. The composition can be painted or coated by a known method.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the examples.

[Analysis method]
<Powder X-ray diffraction (XRD)>
The crystal was filled in the sample filling portion of the glass test plate, and measurement was performed under the following conditions using a powder X-ray diffractometer (Ultima IV, manufactured by Rigaku Corporation).
X-ray source: Cu, 40 kV-40 mA
Measurement method: Concentration method Filter: Kβ filter Scan speed: 5 ° / min <X-ray crystal structure analysis>
X-ray crystal structure analysis of crystal A was performed using an imaging plate single crystal X-ray structure analyzer (R-AXIS RAPID, manufactured by Rigaku Corporation) at an X-ray source CuKα (λ = 0.71075 mm) at −150 ° C. And measured.
X-ray crystal structure analysis of crystal B was measured at 30-100 ° C. using an X-ray source CuKα (λ = 0.10773Å) using a desktop single crystal X-ray structure analyzer (XtaLAB mini, manufactured by Rigaku Corporation). Went.

<Thermogravimetry / Differential Scanning Calorimetry (TG-DSC)>
Using a thermogravimetric measurement device (product name: TGA-DSC1, manufactured by METTLER TOLEDO), about 3 mg of crystal was placed in an aluminum container, and under a nitrogen purge (nitrogen flow rate 50 mL / min) The measurement was performed at a temperature range of 30 to 500 ° C./min.

<Differential scanning calorimetry (DSC)>
Using a differential scanning calorimeter (product name: DSC1, manufactured by METTLER TOLEDO), about 8 mg of crystal was placed in an aluminum container, and under a nitrogen purge (nitrogen flow rate: 50 mL / min) The measurement was carried out in the temperature range of 30 ° C. to 350 ° C. per minute.

[Example 1] to [Example 5]
To the flask, 3.04 g (16.7 mmol) of HIPA and the amount of solvent shown in Table 1 were added and stirred. To this, 1.84 g (16.7 mmol) of 2E4MZ (product name: 2E4MZ, manufactured by Shikoku Kasei Kogyo Co., Ltd.) dissolved in a small amount of solvent in advance was added dropwise at room temperature, followed by heating and refluxing for 3 hours while stirring. . After cooling, filtration and drying were performed to obtain an inclusion compound having a molar ratio (HIPA: 2E4MZ) = 1: 1.

The XRD and TG-DSC of the clathrate compound obtained in Example 1 were measured, and the results are shown in FIGS. 1 and 2, respectively. From FIG. 1, the clathrate compound has diffraction angles (2θ) of 14.68 °, 16.96 °, 20.36 °, 23.48 °, 25.92 °, 26.52 °, 27.84 ° and It was found to be a crystal polymorph (crystal B) having a characteristic diffraction peak at 29.56 °. The release temperature of 2E4MZ was found to be 189 ° C. The same measurement results were obtained for Examples 2 to 5. The crystal was subjected to X-ray structural analysis to identify its three-dimensional structure. The obtained crystal data is shown in Table 2, and the three-dimensional arrangement of crystals drawn based on the crystal data is shown in FIG.

[Comparative Example 1]
According to the method described in Patent Document 2, an inclusion compound of HIPA and 2E4MZ was produced to obtain an inclusion compound. The XRD and TG-DSC of the resulting clathrate were measured, and the results are shown in FIGS. 4 and 5, respectively. According to FIG. 4, the clathrate compound has diffraction peaks characteristic at diffraction angles (2θ): 16.32 °, 18.56 °, 21.84 °, 22.52 °, 23.84 ° and 27.56 °. Was a crystalline polymorph (crystal A). Further, from the results of FIG. 5, it was found that the release temperature of 2E4MZ was 173 ° C. The crystal was subjected to X-ray structural analysis to identify its three-dimensional structure. The obtained crystal data is shown in Table 3, and the steric arrangement of crystals drawn based on the crystal data is shown in FIG.
From the above results, it was found that the clathrate compounds obtained in Example 1 and Comparative Example 1 were different crystal polymorphs.

[Example 6]
To the flask, 11.3 g (103 mmol) of 2E4MZ and 40 ml of methanol were added and stirred. 18.7 g (103 mmol) of HIPA was added thereto, and the mixture was refluxed with heating for 3 hours while stirring. After cooling, filtration and drying were performed to obtain 24.3 g of an inclusion compound at a recovery rate of 81%. The XRD and TG-DSC of the resulting clathrate were measured, and the same results as in Example 1 were obtained.

[Example 7]
In a beaker, 30 g (0.1 mol) of the clathrate crystal obtained in Comparative Example 1 and 40 ml of methanol were added, and the crystal was completely dissolved while heating. Thereafter, the mixture was cooled to room temperature, crystals were precipitated and filtered to obtain 25 g of an inclusion compound at a recovery rate of 83%. The XRD and TG-DSC of the resulting clathrate were measured, and the same results as in Example 1 were obtained.

[Example 8]
In a beaker, 30 g (0.1 mol) of the clathrate crystal obtained in Comparative Example 1 and 240 ml of methanol were added to completely dissolve the crystal. The mixture was allowed to stand at room temperature as it was, methanol was slowly evaporated, and crystals were precipitated to obtain clathrate compound crystals (crystal B). The XRD and TG-DSC of the resulting clathrate were measured, and the same results as in Example 1 were obtained.

[Example 9]
In a beaker, 3.04 g (16.7 mmol) of HIPA, 1.84 g (16.7 mmol) of 2E4MZ and methanol were added to completely dissolve the crystals. The mixture was allowed to stand at room temperature under open conditions, methanol was slowly evaporated, crystals were precipitated, and filtered to obtain an inclusion compound. The XRD and TG-DSC of the resulting clathrate were measured, and the same results as in Example 1 were obtained.

[Example 10] and [Comparative Example 2] to [Comparative Example 3]
In the blending ratio shown in Table 4, a curing agent was mixed with the epoxy resin so as to be 4 phr with respect to the epoxy resin in terms of 2E4MZ to obtain an epoxy resin composition.

＊１：ビスフェノールＡ型エポキシ樹脂（製品名：エポトート（登録商標）　ＹＤ－１２８、新日鉄住金化学（株）製、エポキシ当量１８４－１９４ｇ／ｅｑ）

* 1: Bisphenol A type epoxy resin (Product name: Epototo (registered trademark) YD-128, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., epoxy equivalent 184-194 g / eq)

The obtained epoxy resin composition was stored at 40 ° C., and the storage stability was evaluated by measuring the number of days until the solidification was visually confirmed. The results are shown in Table 5. Furthermore, the DSC of the epoxy resin composition was measured. Table 5 shows the curing start temperature and the peak temperature of the reaction heat, and FIG. 7 shows the DSC chart.

From the results of Table 5, when crystal B is used as a curing agent, the number of days until solidification of the epoxy resin composition is extended and the curing start temperature and reaction are compared with the case where the inclusion compound of crystal A and 2E4MZ are used. Since the peak temperature of heat rose, it was found that the stability of one liquid was improved.

Claims (5)

In a crystal polymorph of an inclusion compound (molar ratio 1: 1) consisting of 5-hydroxyisophthalic acid and 2-ethyl-4-methylimidazole, and in a powder X-ray diffraction pattern measured by CuKα ray, Diffraction peaks at diffraction angles (2θ) of 14.68 °, 16.96 °, 20.36 °, 23.48 °, 25.92 °, 26.52 °, 27.84 ° and 29.56 °. Crystal polymorph having. In powder X-ray diffraction patterns measured with CuKα rays, at diffraction angles (2θ) of 16.32 °, 18.56 °, 21.84 °, 22.52 °, 23.84 ° and 27.56 ° The crystal according to claim 1, comprising a step of recrystallizing a crystal of an inclusion compound (molar ratio 1: 1) comprising 5-hydroxyisophthalic acid and 2-ethyl-4-methylimidazole having a diffraction peak. Polymorph manufacturing method. From an alcohol solution or suspension containing 5-hydroxyisophthalic acid and 2-ethyl-4-methylimidazole, an inclusion compound composed of 5-hydroxyisophthalic acid and 2-ethyl-4-methylimidazole (molar ratio 1: The method for producing a crystalline polymorph according to claim 1, comprising a step of crystallizing 1). A curing agent for epoxy resins or a curing accelerator for epoxy resins containing the crystal polymorph according to claim 1. A curable composition containing an epoxy resin and the epoxy resin curing agent or epoxy resin curing accelerator according to claim 4, and a cured product thereof.

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