JP2005272689A - Methylhexamine condensed borate and novolak phenolic resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a methylhexamine condensed borate useful in various industrial fields including a curing agent for a novolak phenolic resin. <P>SOLUTION: The methylhexamine condensed borate is expressed by formula (1). Preferably the borate is a crystalline hexamine condensed borate. Especially, the hexamine condensed borate is produced by reacting 1 mol of hexamine with 2-10 mol of an inorganic boric acid compound in terms of boron. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a novel amine-condensed borate and a novolac-type phenolic resin composition containing the same.

The amine borate has been known for a long time, and there are several reports (see, for example, Patent Document 1 and Patent Document 2). In these patent documents, an amine borate aqueous solution obtained by reacting 1 to 3 mol of amine compound with 1 mol of boric acid is used as it is as a catalyst for producing a latex coagulant or α-alkylacrolein. . However, by using an excess amine compound, the yield of the produced amine borate is low, which is disadvantageous for the formation of an amine condensed borate having a condensed borate group. At that time, of course, until now, amine condensed borate having a polynuclear condensed borate group obtained by condensing several boric acids has not been known, and research on its usefulness has never been conducted.
On the other hand, hexamine is widely used as a curing agent for novolak-type phenolic resins. However, the obtained cured epoxy resin has a low glass transition temperature and has problems such as a safety problem in handling due to an amine-stimulated odor.
Until now, novolak-type phenol resins modified with boric acid have been proposed (see, for example, Patent Document 3). However, since one molecule of boric acid has three hydroxyl groups, a three-dimensional intermolecular bridge is formed by reaction with the hydroxyl group of the phenol resin, and the crosslink density becomes extremely high. Had the problem that it became brittle and the mechanical strength was inferior.
Japanese Patent Publication No.54-4377 JP-A-4-338355 JP-A 63-156814

  An object of the present invention is to provide a methylhexamine condensed borate useful in various industrial fields including a curing agent for a novolac type phenol resin.

  As a result of intensive studies to achieve the above object, the present inventors have synthesized crystalline methylhexamine condensed borate useful in many fields by reacting hexamine and boric acid and the structure. The present inventors have succeeded in identification and found that the obtained methylhexamine condensed borate is effective for imparting excellent heat resistance as a curing agent for novolak type phenolic resin, and completed the present invention. It was.

  That is, the present invention relates to a methylhexamine condensed borate represented by the following chemical formula (1).

また、本発明は、上記メチルヘキサミン縮合ホウ酸塩の硬化剤を含有するノボラック型フェノール樹脂組成物に関する。

The present invention also relates to a novolak type phenolic resin composition containing a curing agent for the above methylhexamine condensed borate.

  The methylhexamine condensed borate of the present invention has almost no amine-stimulating odor, has a property of being well soluble in water and organic solvents such as methanol, and is effectively used as a curing agent for novolak type phenol resins. The methylhexamine condensed borate gives a novolac type phenolic resin cured product having a high glass transition temperature while maintaining the curing properties of hexamine. Moreover, compared with the case where a boric-acid type compound is directly added to resin, boron content can be made high and it has the effect that the flame retardance of the hardened | cured material obtained for that reason improves.

The methylhexamine condensed borate of the present invention is obtained by reacting hexamine with an inorganic boric acid compound. As the inorganic boric acid compound, boric acid, boric acid ester, and partial polycondensate of boric acid ester are used. As typical examples of boric acid and boric acid ester, general formula (2)
B (OR) n (OH) 3-n (2)
(Wherein n is an integer from 0 to 3, R is an alkyl group of CmH2m + 1, and m is an integer from 1 to 10).

Specific examples of boric acid include, for example, orthoboric acid, metaboric acid, tetraboric acid, and mixtures thereof. Specific examples of boric acid esters include, for example, trimethyl borate, triethyl borate, Examples include tripropyl borate and tributyl borate. These boric acid and boric acid ester can be used alone or in combination of two or more. Moreover, those partial hydrolysates and partial polycondensates can also be used. Of these, boric acid is most preferably used.
The partial polycondensate can be obtained by a method in which the borate ester represented by the general formula (2) is mixed and stirred with water, a solvent, and, if necessary, an acid or a base catalyst.

  When producing the methylhexamine condensed borate of the present invention, the reaction product obtained from the reaction of hexamine and an inorganic boric acid compound is subsequently dissolved in a mixed solvent of ethanol and water and allowed to stand at a low temperature. Thus, crystalline powders of various sizes can be obtained. FIG. 1 shows an X-ray diffraction pattern of the crystalline powder synthesized and isolated by the above method using boric acid as the inorganic boric acid compound. In addition, X-ray structural analysis and boron content were measured using large crystal grains. As a result of the X-ray structural analysis, it was revealed that it was a single crystal of a polynuclear condensed borate represented by the formula (1) having a crystal structure as shown in FIG. Further, when the simulation of the powder X-ray diffraction pattern was performed using the obtained crystal structure, the result (FIG. 3) well matched the X-ray diffraction pattern (FIG. 1) of the crystalline powder, and the crystallinity It was shown that the powder was a polynuclear condensed borate represented by the formula (1) in FIG. Furthermore, when the boron content of the crystalline powder was measured, it almost coincided with the theoretical value of the boron content of the methylhexamine condensed borate represented by the formula (1). From these facts, it was concluded that the crystalline powder (including single crystal) synthesized and isolated by the above method is a methylhexamine condensed borate represented by the formula (1). In FIG. 2, C is a carbon atom, N is a nitrogen atom, B is a boron atom, and O is an oxygen atom.

  The synthesis and isolation of the methylhexamine condensed borate in the present invention can be performed, for example, as follows. That is, boric acid and hexamine are dissolved in water, and the reaction is performed under heating, for example, at 40 to 100 ° C. for 2 to 10 hours. Subsequently, the reaction product obtained by distilling off water with an evaporator was repeatedly washed several times in the order of N, N-dimethylformamide and acetone, and then the powder obtained by vacuum drying was continuously used with water and ethanol. Crystals containing single crystals of various sizes are precipitated by dissolving in a mixed solvent (for example, water: ethanol = 70: 30 mass ratio) and allowing to stand at a low temperature (−6 ° C.). Subsequently, the precipitated crystals are collected by filtration, and further dried in vacuum to obtain a white methylhexamine condensed borate represented by the formula (1).

  In the present invention, as a synthesis condition of the methylhexamine condensed borate represented by the formula (1), the molar ratio of hexamine and the inorganic boric acid compound is extremely important. It has been clarified that increasing the ratio of the inorganic borate compound facilitates the formation of polynuclear condensed borate and increases the yield of methylhexamine condensed borate. Specifically, 2 to 10 mol is preferable, more preferably 3 to 8 mol, and particularly preferably 4 to 6 mol per mol of hexamine as boric acid or an inorganic boric acid compound per mol of boron atom. Is a mole.

  In the present invention, as a synthesis solvent for methylhexamine condensed borate, a solvent capable of dissolving at least one of boric acid or hexamine is required. For example, lower alcohols such as methanol, ethanol and isopropanol, N, N-dimethylformamide, N-methylpyrrolidone, N, N-dimethylacetamide, dimethyl sulfoxide, water and the like can be mentioned, and these can be used alone or in combination of two or more. Can be used. Of these, water is particularly preferably used. The amount of the solvent used is preferably such that the solvent is 300 to 1500 parts by mass with respect to 100 parts by mass in total of the boric acid compound and hexamine.

  The methylhexamine condensed borate in the present invention is a solid white powder having almost no irritating odor peculiar to hexamine, and shows a property of being well soluble in water or an organic solvent such as methanol. It has also been found that it can be used effectively as a curing agent for novolak-type phenolic resins, particularly for the purpose of imparting heat resistance. The methylhexamine condensed borate (curing agent) is preferably 8 to 80 parts by mass, more preferably 10 to 60 parts by mass, and particularly preferably 15 to 45 parts by mass with respect to 100 parts by mass of the novolac type phenol resin. Used in

  Here, as the novolak-type phenol resin, a normal novolak-type phenol resin obtained by a reaction between a phenol compound and an aldehyde compound is used. Specifically, a monovalent phenolic compound such as phenol, naphthol, or bisphenol A is used. Or divalent phenolic compounds such as resorcin and xylenol, or trivalent phenolic compounds such as pyrogallol and hydroxyhydroquinone, and derivatives of these phenolic compounds such as alkyl, carboxyl, halogen, and amine alone or in combination of two or more thereof A phenolic compound consisting of a mixture of the above and an aliphatic aldehyde such as formaldehyde and acetaldehyde, or an aldehyde compound of aromatic aldehyde such as benzaldehyde and furfural in a predetermined molar ratio, and hydrochloric acid, sulfuric acid, It is a known novolak type phenol resin obtained by reacting under an acidic catalyst such as acid or phosphoric acid.

  In the present invention, as the solvent for the novolac type phenolic resin composition using the methylhexamine condensed borate of the formula (1), a novolac type phenolic resin and an organic solvent capable of uniformly dissolving the methylhexamine condensed borate are used. Is done. Examples thereof include lower alcohols having about 1 to 6 carbon atoms such as methanol, ethanol and isopropanol, organic solvents such as acetone, methyl ethyl ketone, cyclohexanone, chloroform, benzene, toluene and xylene alone or a mixed solvent thereof.

In the present invention, the organic solvent is removed from the solution in which the novolak-type phenol resin and the methylhexamine condensed borate of the formula (1) are uniformly dissolved in the organic solvent containing the lower alcohol, and the obtained solid is pulverized. A powdery thermosetting novolac-type phenol resin composition can be produced.
The removal of the organic solvent in the solution-like thermosetting novolak type phenolic resin composition can be performed by a conventional method using a hot air dryer, a freeze dryer, a vacuum dryer or the like. It is preferable to remove the organic solvent by heating the thermosetting novolac type phenolic resin composition in a temperature range of 25 ° C. to 80 ° C. under reduced pressure. The pulverization can be carried out by a known and commonly used method. Preferably, the pulverization is performed to an average particle size of 300 μm or less, and the obtained powder is further dried at a temperature of 25 to 80 ° C. under reduced pressure.

  The above-mentioned powdery thermosetting novolak type phenolic resin composition is compression-molded under heating, and is optionally cured by further heat treatment to obtain a heat-resistant cured product. The molding temperature is usually 80 ° C to 200 ° C.

  The composition of the above-mentioned curing agent composed of methylhexamine condensed borate and novolak type phenol resin includes other curing agents such as amine borate and hexamine, curing aid, inorganic filler, fiber reinforcement, bone Materials, colorants and the like can be added.

  The methylhexamine condensed borate of the present invention is particularly useful as a curing agent for novolak type phenolic resins.

Next, the present invention will be specifically described with reference to examples.
In the following examples, JNM-LA-300 manufactured by JEOL Ltd. was used for nuclear magnetic resonance spectrum (NMR) measurement. ¹¹ B-NMR spectrum was based on boric acid peak in heavy water.
Fourier transform infrared absorption spectrum (FT-IR) is used JASCO Corp. FT / IR-550, was measured in a range of 4000cm ^-1 ~400cm ^-1.
The single crystal structure analyzer RASA-5R manufactured by Rigaku Corporation was used for the crystal structure analysis of the single crystal.
The X-ray diffraction apparatus RINT ULTIMA ⁺ manufactured by Rigaku Corporation was used for the measurement of powder X-ray diffraction.
The boron content was measured by ICP using an Optima 3300DV manufactured by Perkn Elmer, and quantified by a calibration curve prepared in advance using boric acid.
The following reagents were used for the examples of the present invention.
(1) Hexamine: Wako Pure Chemical Industries, Ltd., reagent grade
(2) Boric acid: Wako Pure Chemical Industries, Ltd., reagent grade
(3) Novolac type phenolic resin
IH1225: Dainippon Ink & Chemicals, Inc.
(4) Solvent
N, N-dimethylformamide (DMF): Wako Pure Chemical Industries, reagent grade Acetone: Wako Pure Chemical Industries, reagent grade 1 Hexane: Wako Pure Chemical Industries, reagent grade 1 Methanol: Wako Pure Yakuhin Kogyo Co., Ltd., reagent special grade Ethanol: Wako Pure Chemical Industries, Ltd., reagent special grade Chloroform: Wako Pure Chemical Industries, Ltd., reagent special grade

(Example 1)
Hexamine 17 g (0.121 mol) was added to a solution of boric acid 60 g (0.971 mol) in distilled water 300 g, stirred and dissolved, and then reacted at 100 ° C. for 4 hours (molar ratio: boric acid / hexamine). = 8). Subsequently, water was distilled off with an evaporator, and DMF was added to the concentrated solution to precipitate a precipitate. The white solid recovered by filtration was washed with acetone and then vacuum dried at 50 ° C. for 2 hours to obtain 40.6 g of a powder.
Crystals were precipitated by allowing a uniform transparent solution prepared by dissolving 10 g of the above powder in a mixed solution of 69 g of water and 26.5 g of ethanol to stand at a low temperature of −6 ° C. for 2 days. The obtained crystals were collected by filtration and vacuum dried at 70 ° C. for 5 hours to obtain 4.6 g of crystalline powder (1a) containing large crystal grains. The X-ray diffraction pattern of the crystalline powder (1a) is shown in FIG. Further, as a result of X-ray structural analysis of the obtained large crystal grains, results consistent with the structure of the methylhexamine condensed borate represented by the chemical structural formula (1) (FIG. 2) were obtained. Further, when an X-ray diffraction pattern was simulated using the obtained crystal structure, the result (FIG. 3) coincided with the powder X-ray diffraction pattern (FIG. 1) of (1a). Further, the boron content of (1a) almost coincided with the theoretical value of the boron content of methylhexamine condensed borate represented by the formula (1). From these results, it was concluded that the obtained crystalline powder (1a) was a polynuclear condensed borate (methylhexamine condensed borate) represented by the formula (1). The analysis results and FT-IR spectrum of the methylhexamine condensed borate (1a) are shown in Table 1, Table 2, and FIG.

(Example 2)
After adding 34 g (0.242 mol) of hexamine to a solution of 30 g (0.485 mol) of boric acid in 300 g of distilled water, stirring and dissolving, the mixture was reacted at 100 ° C. for 4 hours (molar ratio: boric acid / hexamine). = 2). Subsequently, water was distilled off with an evaporator, and the obtained white solid was washed with DMF, chloroform, and acetone in this order. Further, 24.2 g of powder was obtained by vacuum drying at 50 ° C. for 2 hours. Subsequently, 10 g of the obtained powder is dissolved in a mixed solution of 94.3 g of water and 30 g of ethanol and allowed to stand at a low temperature of −6 ° C. The supernatant solution from which the precipitated powder had been removed was further allowed to stand at a low temperature of −30 ° C. for 2 days to precipitate crystals. The obtained crystals were collected by filtration and vacuum dried at 70 ° C. for 5 hours to obtain 1.9 g of crystalline powder (2a). X-ray structural analysis and boron content measurement showed that (2a) was the same methylhexamine condensed borate as (1a).

  In the following examples and comparative examples, the glass transition temperature (Tg) and the storage elastic modulus (E ′) were measured using a solid dynamic viscoelasticity measuring device (DMA-200 manufactured by Seiko Electronics Co., Ltd.), with a measurement frequency of 1 Hz, The temperature was measured at 2 ° C / min. The glass transition temperature was tan δ peak temperature (tan δ max).

(Example 3 and Comparative Example 1)
While stirring a solution of 28 g of methylhexamine condensed borate (1a) obtained in Example 1 in 300 g of methanol, 100 g of IH1225 was gradually added and dissolved. The obtained uniform transparent solution was poured into a tray, and solvent casting was performed at 25 ° C. in the air for 8 hours. Subsequently, after vacuum drying at 25 ° C. for 12 hours, the sample was pulverized to a size of 180 μm or less to obtain a thermosetting novolac-type phenol resin composition powder.
Next, a cured product of a film-like or plate-like phenolic resin composition was produced by hot pressing the powdery curable novolak-type phenolic resin composition at 150 ° C. The press sample was subsequently heat treated at 150 ° C. for 1 hour and 180 ° C. for 1 hour. The obtained cured product was transparent. Moreover, there was no crack or wrinkle, and a good surface morphology was shown.
Dynamic viscoelasticity measurement (frequency = 1 Hz) was performed using a cured product test piece having a width of 10 mm and a thickness of 1 mm. The storage elastic modulus (E ′) of the obtained Comparative Example 1 rapidly decreased to 145.2 ° C., whereas E ′ of the cured phenol resin of Example 3 hardly decreased to 300 ° C. Further, the glass transition temperature of the cured product obtained in Example 3 is much higher than that of Comparative Example 1. It can be seen that the heat resistance of the novolak-type phenol resin cured product using methylhexamine condensed borate as a curing agent is greatly improved. The results are shown in Table 3.

1 is a powder X-ray diffraction pattern diagram of the crystalline powder (1a) obtained in Example 1. FIG. Crystal structure of methylhexamine condensed borate (1a). The simulation figure of the powder X-ray diffraction pattern from the crystal structure of methylhexamine condensed borate. FT-IR spectrum of methylhexamine condensed borate (1a).

Claims (6)

Hexamine condensed borate represented by the following chemical formula (1).

2. The hexamine condensed borate according to claim 1, which is crystalline. 3. The hexamine condensed borate according to claim 1, which is obtained by reacting 2 to 10 mol of an inorganic boric acid compound in terms of boron with respect to 1 mol of hexamine. 4. The hexamine condensed borate according to claim 3, wherein the inorganic boric acid compound is boric acid or / and a borate ester. The hardening | curing agent for novolak-type phenol resins which consists of a hexamine condensed borate as described in any one of Claims 1-4. A novolac phenolic resin composition comprising a novolac phenolic resin and the curing agent according to claim 5.

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