JP2001192374A - New latently hardening agent and hardenable resin composition comprising the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition having moisture hardenability and excellent in storage stability and deep hardenability, and to provide a latently hardening agent capable of imparting excellent storage stability and deep hardenability to the resin composition. SOLUTION: This latently hardening agent is an oxazolidine represented by formula (1), wherein R1 and R3 are each methyl or ethyl; R2 is a 1-6C alkyl group; R1 is H, methyl or ethyl; and R5 is H or a 1-6C hydrocarbon group and this resin composition having moisture hardenability comprises a polyepoxy compound and the above oxazolidine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-pack type epoxy resin composition, and more particularly, to a moisture-curable resin composition having both good storage stability and deep curability, and a storage composition having good storage stability. The present invention relates to a novel latent curing agent which has a good deep curing effect and is useful as a curing agent for a moisture-curable resin composition.

[0002]

2. Description of the Related Art Various studies have been made on one-package of a moisture-curable resin composition such as an epoxy resin composition using a latent curing agent mainly composed of a ketimine compound. However, since the nitrogen atom of the imine part of the ketimine-based compound has high nucleophilicity, if it is sealed after mixing with an epoxy resin or the like, there is a problem in storage stability such as an increase in viscosity or gelation over time. Therefore, an invention aimed at improving storage stability is disclosed. For example, as a latent curing agent having good storage stability, a ketimine-based compound having a large steric hindrance around an imine portion has been proposed. However, a moisture-curable resin composition using such a ketimine-based compound as a latent curing agent can provide a good balance between storage stability and curing speed, but has insufficient deep curing properties. There is a problem that only a very thin cured film thickness can be obtained in a short period of time.

[0003]

On the other hand, oxazolidine may be used as a latent curing agent for the moisture-curable resin composition in order to enhance the deep curability of the moisture-curable resin composition. However, the conventionally known oxazolidine has a problem that although the moisture-curable resin composition has an improved deep curability, it lacks storage stability.

[0004] An object of the present invention is to solve the above-mentioned problems of the prior art, and is a one-pack type epoxy resin composition which is a moisture-curable resin composition having excellent storage stability and excellent deep-section curability. And to provide a novel latent curing agent which gives the moisture-curable resin composition good storage stability and excellent deep curability.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, oxazolidine used as a latent curing agent for a moisture-curable resin composition has been replaced with a predetermined sterically hindered oxazolidine. By doing
The present inventors have found that it is possible to exhibit excellent deep curability while maintaining good storage stability of a curable resin composition using the same, and completed the present invention.

That is, the oxazolidine of the present invention is an oxazolidine represented by the following formula (1).

Embedded image R ¹ : methyl group or ethyl group R ² : alkyl group having 1 to 6 carbon atoms R ³ : methyl group or ethyl group R ⁴ : hydrogen atom, methyl group or ethyl group R ⁵ : hydrogen atom or 1 to carbon atoms 6 hydrocarbon groups

Here, R ¹ is preferably a methyl group.

Further, the moisture-curable resin composition of the present invention comprises:
It comprises a polyepoxy compound having two or more epoxy groups in the molecule and the oxazolidine according to the present invention represented by the above formula (1).

Here, it is preferable that R ¹ is a methyl group.

The above-mentioned moisture-curable resin composition may further contain a ketimine compound synthesized from a ketone or aldehyde represented by the following formula (2) and a polyamine.

Embedded image R ⁶ : hydrogen atom or methyl group R ⁷ : alkyl group having 1 to 6 carbon atoms R ⁸ : methyl group or ethyl group R ⁹ : hydrogen atom, methyl group or ethyl group

The hydroxyl group contained in the skeleton of the polyepoxy compound is preferably 10 mol% or less. However, this includes the case where the skeleton of the polyepoxy compound does not contain a hydroxyl group.

Further, the latent curing agent of the present invention contains the oxazolidine of the present invention represented by the above formula (1), or contains the oxazolidine and the above ketimine compound. Is what you do.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <Oxazolidine> First, the oxazolidine of the present invention will be described. The oxazolidine of the present invention is a compound represented by the following formula (1).

Embedded image R ¹ : methyl group or ethyl group R ² : alkyl group having 1 to 6 carbon atoms R ³ : methyl group or ethyl group R ⁴ : hydrogen atom, methyl group or ethyl group R ⁵ : hydrogen atom or 1 to 6 carbon atoms Hydrocarbon Group Since the oxazolidine of the present invention has a bulky group around the nitrogen in the heterocycle, the nitrogen in the heterocycle is protected by steric hindrance of the substituent, and its basicity is greatly weakened. For this reason, the moisture-curable resin composition using the oxazolidine of the present invention as a latent curing agent is particularly excellent in storage stability. Further, the moisture-curable resin composition using the oxazolidine of the present invention as a latent curing agent has a long so-called tack-free time, and can lengthen the time required for water necessary for hydrolysis of oxazolidine to penetrate into the inside of the coated surface. it can. For this reason, it is very excellent in the deep part curability, and the cured film thickness can be easily increased. Therefore,
The oxazolidine of the present invention can be suitably used as a latent curing agent for a moisture-curable resin composition such as a one-pack type epoxy resin composition.

The oxazolidine of the present invention has the above formula (1)
It is a compound represented by these. Here, carbon number 1 representing R ²
Examples of the alkyl groups 6 to 6 include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group.

A hydrogen atom representing R ⁵ or a carbon atom having 1 carbon atom
Among the hydrocarbon groups having 1 to 6 carbon atoms, the hydrocarbon group having 1 to 6 carbon atoms includes an alkyl group having 1 to 6 carbon atoms, for example, a methyl group,
Ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group,
Pentyl group, isopentyl group, neopentyl group, ter
t-pentyl, 1-methylbutyl, 2-methylbutyl, 1,2-dimethylpropyl, hexyl, isohexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 1,1 -Dimethylbutyl group, 1,2-dimethylbutyl group, 2,2-dimethylbutyl group, 1,3-dimethylbutyl group, 2,3-dimethylbutyl group, 3,3-dimethylbutyl group, 1-ethylbutyl group, Alkyl groups such as a 2-ethylbutyl group, a 1,1,2-trimethylpropyl group, a 1,2,2-trimethylpropyl group, a 1-ethyl-1-methylpropyl group, and a 1-ethyl-2-methylpropyl group; And an alkylene group corresponding to each of the above alkyl groups.

The oxazolidine of the present invention is preferably a compound in which R ¹ is a methyl group, from the viewpoint of further improving the curing speed of a curable resin composition using the oxazolidine of the present invention as a latent curing agent, On the other hand, from the viewpoint of accelerating the hydrolysis of oxazolidine,
Compounds in which ² , R ³ and R ⁵ are methyl groups and R ⁴ is a hydrogen atom are preferred.

The oxazolidine of the present invention has the following formula (3)
Can be obtained by reacting a ketone represented by the formula with an amino alcohol represented by the following formula (4).

Embedded image The description of R ^{1 to} R ^{5 is} the same as that described in the above formula (1). The synthesis can be obtained, for example, by reacting the ketone and the amino alcohol in the absence of a solvent or in the presence of a solvent such as benzene, toluene, and xylene by heating to reflux and removing elimination water by azeotropic distillation. Can be.

<Moisture-curable resin composition> Next, the moisture-curable resin composition of the present invention will be described. The moisture-curable resin composition of the present invention is a composition containing a polyepoxy compound having two or more epoxy groups in a molecule and a predetermined oxazolidine having high steric hindrance, and has excellent storage stability and deep curing. It is a composition having excellent properties.

Examples of the polyepoxy compound used in the present invention include glycidyl ether type epoxy resin of bisphenol A and derivatives thereof, glycidyl ether type epoxy resin of glycerin, glycidyl ether type epoxy resin of polyalkylene oxide, and glycidyl of phenol novolak. It has a polyether structure such as an ether type epoxy resin, a glycidyl ester type epoxy resin of dimer acid, and a glycidyl ether type epoxy resin of bisphenol F, and has at least two epoxy groups in the molecule.
Polyepoxy compound having a polyester structure such as a glycidyl ester type epoxy compound such as a urethane-modified epoxy compound;
A compound having (R—S _X ) — as a repeating unit and having an epoxy group at a molecular terminal, wherein R is an alkylene group having 2 to 8 carbon atoms that contains or does not contain an oxygen atom in a main chain;
Polyepoxy compounds having a polysulfide structure in which x is 1 to 3 can be exemplified. If necessary, a monofunctional epoxy compound such as phenol glycidyl ether may be used in combination. Among them, a glycidyl ether type epoxy resin of bisphenol A can be suitably used as a general-purpose epoxy resin. Further, in order to further improve the storage stability of the resin composition according to the present invention, the hydroxyl group contained in the skeleton of the polyepoxy compound used in the present invention is preferably 10 mol% or less, and 0 mo
More preferably, it is 1% to 8 mol%. Within this range, the storage stability of the resin composition is further improved. Here, the hydroxyl group contained in the skeleton of the polyepoxy compound, in addition to the hydroxyl group generated by the opening of the epoxy ring during the synthesis of the polyepoxy compound, the hydroxyl group that is present because the raw material polyol remains unreacted Mean both. Note that “the hydroxyl group contained in the skeleton of the polyepoxy compound is 10 mol% or less” includes the case where the skeleton of the polyepoxy compound does not contain a hydroxyl group.

Further, the moisture-curable resin composition of the present invention comprises:
The latent curing agent contains the oxazolidine of the present invention represented by the above formula (1). In the present invention,
The oxazolidine used as a latent curing agent,
As described in the oxazolidine according to the present invention,
Since the composition has a bulky group around nitrogen in the heterocycle, the composition of the present invention is excellent in storage stability and has good deep curability.

The oxazolidine used in the present invention is a compound represented by the above formula (1), a description of R ¹ to R ⁵ , a description of a preferred embodiment, and a formula (1)
The description of the method for producing the compound represented by is the same as that described for the oxazolidine according to the present invention.

In the moisture-curable resin composition of the present invention,
The oxazolidine content is preferably such that the molar ratio of epoxy group / oxazolidine ring is from 0.5 to 10, preferably 1 to 10.
-6 is more preferable. This is because storage stability and deep curability are good in this range.

The moisture-curable resin composition of the present invention may further contain a ketimine compound synthesized from a ketone or aldehyde represented by the following formula (2) and a polyamine in order to shorten the surface curing time.

Embedded image R ⁶ : hydrogen atom or methyl group R ⁷ : alkyl group having 1 to 6 carbon atoms R ⁸ : methyl group or ethyl group R ⁹ : hydrogen atom, methyl group or ethyl group Ketone used in the synthesis of the above ketimine compound Alternatively, the aldehyde is a ketone or aldehyde having a steric hindrance having a substituent at the α-position. The ketone having a substituent at the α-position is a ketone having a substituent at the α-position counted from the carbonyl group, and a ketimine compound synthesized using such a ketone is used in combination as a latent curing agent. The curing rate of the composition of the present invention can be increased while maintaining good storage stability and deep curability.

The ketone or aldehyde used in the synthesis of the ketimine compound includes a compound represented by the above formula (2). Here, as the alkyl group having 1 to 6 carbon atoms representing R ⁷ , for example, a methyl group,
Examples thereof include an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. Specific examples of the ketone include methyl isopropyl ketone and methyl t-butyl ketone.

In addition, it is used for the synthesis of the above ketimine compound.
Although there is no particular limitation on the polyamine used, the curing speed
Aliphatic polyamines are preferred in that they are fast. example
For example, 2,5-dimethyl-2,5-hexamethylene diamine
, Mensendiamine, 1,4-bis (2-amino-2
-Methylpropyl) piperazine, propylene at both ends of the molecule
Glyco with an amino group bonded to a branched carbon
(PPG) (for example, a gel manufactured by San Techno Chemical Co., Ltd.)
Farmin D230, Jeffamine D400, etc.),
Ethylenediamine, propylenediamine, butylene dia
Min, diethylene triamine, triethylene tetrami
, Tetraethylenepentamine, pentaethylenehexa
Min, hexamethylenediamine, trimethylhexamethyl
Diamine, N-aminoethylpiperazine, 1,2-
Diaminopropane, iminobispropylamine, methyl
Iminobispropylamine, H_TwoN (CH_TwoCH _TwoO)
_Two(CH_Two)_TwoNH_Two(Product name manufactured by Sun Techno Chemical Co., Ltd.
Amine nitrogen such as Jeffamine EDR148)
Diamine having a polyether skeleton to which a len group is bonded, 1,5
-Diamino-2-methylpentane (Dupont di
MPMD manufactured by Japan Corporation, meta-xylylenediamine (MX
DA), polyamidoamine (X200 manufactured by Sanwa Chemical Co., Ltd.)
0), isophoronediamine, 1,3-bisaminomethyl
Cyclohexane (1,3 BAC manufactured by Mitsubishi Gas Chemical Company), 1
-Cyclohexylamino-3-aminopropane, 3-a
Minomethyl-3,3,5-trimethyl-cyclohexyl
Amine, dimethyleneamine with norbornane skeleton (Mitsui Chemicals
(NBDA manufactured by Gakusha). Among these
However, 1,3-bisaminomethylcyclohexane (1,
3BAC), dimethyleneamine having a norbornane skeleton (N
BDA), meta-xylylenediamine (MXDA),
Farmin EDR148 (trade name), polyamidoamine
Is preferred.

As the ketimine compound, methyl isopropyl ketone (MIPK) or methyl t-butyl ketone (MT) is used from the viewpoint of enhancing the storage stability and curability of the resin composition of the present invention by using the ketimine compound in combination.
BK) and Jeffamine EDR148 (trade name: dimethyleneamine having a polyether skeleton), methyl isopropyl ketone (MIPK) or methyl t-butyl ketone (MTBK), and 1,3-bisaminomethylcyclohexane ( 1,3BAC), methyl isopropyl ketone (MIPK) or methyl t-butyl ketone (MTBK) and dimethyleneamine having a norbornane skeleton (trade name: NBDA), methyl isopropyl ketone (MIPK) Or those obtained from methyl t-butyl ketone (MTBK) and meta-xylylenediamine (MXDA), such as methyl isopropyl ketone (MIPK) or methyl t-butyl ketone (MTBK), and polyamidoamine (trade name: X2000). The result obtained and the like. Among these, in particular, MIPK or MTBK,
Obtained from NBDA, MIPK and 1,3 BAC
And so on exhibit excellent curability. Further, those obtained from MIPK or MTBK and X2000 exhibit excellent adhesion to a wet surface.

The above-mentioned ketimine compound is obtained by reacting the above-mentioned ketone and polyamine in the absence of a solvent or in the presence of a solvent such as benzene, toluene or xylene by heating to reflux and removing elimination water by azeotropic distillation. Can be

In the resin composition of the present invention, the content of the ketimine compound is preferably such that the molar ratio of epoxy group / imino group in the ketimine compound is 0.5 to 5,
1-3 are more preferable. Within this range, the composition of the present invention can have good storage stability and curability, while maintaining good deep curability.

The composition of the present invention may optionally contain a curing accelerator. Phosphorous esters are effective as a curing accelerator. This is because phosphites do not thicken or otherwise adversely affect the composition of the present invention during storage. Examples of phosphites used as a curing accelerator include triphenyl phosphite,
Tris (nonylphenyl) phosphite, triethyl phosphite, tributyl phosphite, tris (2-ethylhexyl) phosphite, tridecyl phosphite, tris (tridecyl) phosphite, diphenyl mono (2-ethylhexyl) phosphite, diphenyl monodecyl Phosphite, diphenyl mono (tridecyl)
Phosphite, tetraphenyldipropylene glycol diphosphite, tetraphenyltetra (tridecyl)
Pentaerythritol tetraphosphite, trilauryl trithiophosphite, bis (tridecyl) pentaerythritol diphosphite, bis (nonylphenyl)
Triesters such as pentaerythritol diphosphite, tristearyl phosphite, distearyl pentaerythritol diphosphite, tris (2,4-di-t-butylphenyl) phosphite, hydrogenated bisphenol A and pentaerythritol phosphite polymer Is mentioned. Further, di- or mono-esters obtained by partially hydrolyzing these triesters are also exemplified. Among them, tetraphenyltetra (tridecyl) pentaerythritol tetraphosphite, bis (tridecyl) pentaerythritol diphosphite,
Bis (nonylphenyl) pentaerythritol diphosphite, distearylpentaerythritol diphosphite, hydrogenated bisphenol A / pentaerythritol phosphite polymer, etc. have particularly high accelerating effects and are preferably used.

When a triester is used among these phosphites, the amount thereof is 0.005 mol% or more, preferably 0.005 mol% to 1%, based on the epoxy group of the polyepoxy compound. 0.0 mol%
It is. When the content is within this range, there is a tendency that the storage stability of the composition is not deteriorated while having the effect as an accelerator. Further, the composition of the present invention may contain an accelerator other than the phosphite as the accelerator.

The composition of the present invention may optionally use a silane coupling agent. By containing a silane coupling agent, it is possible to obtain a resin composition that is excellent in balance between storage stability and curing speed, and also excellent in adhesion to a wet surface. The silane coupling agent is not particularly limited, and a conventionally known silane coupling agent can be used. For example, chloropropyltrimethoxysilane, trimethoxyvinylsilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) Silane, γ-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane and the like. Among these, trimethoxyvinylsilane and 3-glycidoxypropyltrimethoxysilane are particularly excellent in the effect of improving the adhesion to a wet surface,
Since it is further general-purpose, it is preferably used.

The content of these silane coupling agents is preferably from 0.1 to 20 parts by weight, more preferably from 0.5 to 10 parts by weight, based on 100 parts by weight of the polyepoxy compound. When the content is within the above range, the adhesiveness to the wet surface is preferably high because the shear stress at the time of fracture is high and the fracture rate of the base material is almost 100%.

The composition of the present invention may contain calcium carbonate as long as the object of the present invention is not impaired. In particular, by containing the surface-treated calcium carbonate, the viscosity can be adjusted, and good initial thixotropy and storage stability can be obtained. As such calcium carbonate, conventionally known surface-treated calcium carbonate surface-treated with a fatty acid, a resin acid, or a fatty acid ester can be used. Specifically, as calcium carbonate surface-treated with fatty acids, as Calfine 200 (manufactured by Maruo Calcium Co.), Whiten 305 (heavy calcium carbonate, manufactured by Shiraishi Calcium Co.), and calcium carbonate surface-treated with fatty acid ester And Sealets 200 (manufactured by Maruo Calcium Co., Ltd.) are preferably used.

The addition amount of calcium carbonate is preferably from 30 to 200 parts by weight, more preferably from 50 to 150 parts by weight, per 100 parts by weight of the polyepoxy compound. If it is within this range, the viscosity does not become too high, and appropriate initial thixotropy and workability tend to be obtained.

The composition of the present invention may contain, besides the above-mentioned compounds, other additives such as a filler, a plasticizer, a thixotropy-imparting agent, as long as the object of the present invention is not impaired.
A pigment, a dye, an antioxidant, an antioxidant, an antistatic agent, a flame retardant, an adhesion promoter, a dispersant, a solvent, and the like may be blended.

The filler which can be used in the present invention includes various forms of organic or inorganic fillers, such as fumed silica, calcined silica, precipitated silica, pulverized silica, fused silica; diatomaceous earth; Zinc, titanium oxide,
Barium oxide, magnesium oxide; calcium carbonate, magnesium carbonate, zinc carbonate; limestone clay, kaolin clay, calcined clay; or carbon black, or a fatty acid, resin acid, or fatty acid ester-treated product thereof.

The plasticizers usable in the present invention include dioctyl phthalate (DOP), dibutyl phthalate (DBP); dioctyl adipate, isodecyl succinate; diethylene glycol dibenzoate, pentaerythritol ester; butyl oleate, acetyl ricinoleic acid Methyl; tricresyl phosphate, trioctyl phosphate; propylene glycol adipate polyester, butylene glycol adipate polyester, and the like are used. These plasticizers may be used alone or in combination of two or more.

The thixotropic agents that can be used in the present invention include Aerosil (Nippon Aerosil Co., Ltd.)
) And Disparon (manufactured by Kusumoto Kasei Co., Ltd.). As the antistatic agent, quaternary ammonium salts,
Alternatively, hydrophilic compounds such as polyglycol and ethylene oxide derivatives can be mentioned.

The pigments that can be used in the present invention include inorganic pigments and organic pigments. Examples of the inorganic pigments include titanium dioxide, zinc oxide, ultramarine, red iron, lithopone, lead, cadmium, iron, cobalt, aluminum, and the like. Hydrochloride, sulfate and the like can be mentioned. Examples of the organic pigment that can be used in the present invention include an azo pigment and a copper phthalocyanine pigment.

Examples of the antioxidants which can be used in the present invention include compounds such as hindered phenols. Antioxidants that can be used in the present invention include:
Butylhydroxytoluene (BHT), butylhydroxyanisole (BHA) and the like can be mentioned. Examples of the flame retardant that can be used in the present invention include chloroalkyl phosphate, dimethyl methylphosphonate, bromine / phosphorus compound, ammonium polyphosphate, nempentyl bromide-polyether, and brominated polyether. Examples of the adhesion-imparting agent that can be used in the present invention include a terpene resin, a phenol resin, a terpene-phenol resin, a rosin resin, and a xylene resin.

The method for producing the composition of the present invention is not particularly limited, but preferably, the above-mentioned components are reduced under reduced pressure.
Alternatively, the composition may be sufficiently kneaded under a nitrogen atmosphere using a stirring device such as a mixing mixer and uniformly dispersed to obtain a composition.

The moisture-curable resin composition according to the present invention has good storage stability and excellent deep curability, so that it can be suitably used for adhesives, sealing agents, paints and the like. Although the moisture-curable resin composition according to the present invention is intended for a one-pack type epoxy resin composition, when the composition is used, the moisture-curable resin composition of the present invention is used as a two-pack type epoxy resin. It is also possible to use it as a composition.

Next, the latent curing agent of the present invention will be described. The latent curing agent of the present invention contains the oxazolidine of the present invention represented by the above formula (1). The latent curing agent of the present invention contains an oxazolidine having a bulky group around the nitrogen in the heterocyclic ring as described above, thereby providing a composition with good storage stability and deep curing property. Useful as an agent. The description of the oxazolidine used in the latent curing agent of the present invention is the same as the description of the oxazolidine according to the present invention described above.

The latent curing agent of the present invention may further contain the above-mentioned ketimine compound which can be used in the moisture-curable resin composition of the present invention. By further containing a ketimine compound having a high steric hindrance as described above, the latent curing agent of the present invention not only provides the composition with good storage stability and deep curability, but also increases the curing speed of the composition. It can be suitably used as a latent curing agent for improving. The description of the ketimine compound used in the latent curing agent of the present invention is the same as the description of oxazolidine used in the moisture-curable resin composition according to the present invention. Further, the ketimine compound contained in the latent curing agent of the present invention, from the viewpoint of accelerating the curing rate while providing good storage stability and deep curability to the composition using the latent curing agent of the present invention. Is preferably 5 to 90 parts by weight based on 100 parts by weight of the latent curing agent. Further, the latent curing agent of the present invention may be used in combination with other known latent curing agents.

[0045]

EXAMPLES <Preparation of moisture-curable resin composition> Moisture-curable resin compositions shown in Table 1 were obtained by using the following raw materials in amounts shown in Table 1.

[0046] General-purpose epoxy resin: EP4100E, OH-free epoxy resin manufactured by Asahi Denka Kogyo: DER332, manufactured by Dow Chemical Japan, hydroxyl group contained in skeleton: 0 mol% Oxazolidine 1: Formula (5) below Oxazolidine 2: Formula (6) ketimine 1: Equation (7) below

Embedded image

<Deep Curability Test and Surface Curing Time> In order to examine the deep curability of the moisture-curable resin composition thus adjusted, each moisture-curable resin composition was placed in a 1 cm-high polypropylene cup-shaped container. The product was put into the upper limit, and left for 7 days in an environment at a temperature of 20 ° C. and a relative humidity of 55%. The time when the tack on the surface of the coating film disappeared during the standing was defined as the surface hardening time, and the measurement results are shown in Table 2. The cured film thickness after 7 days was measured, and the results are shown in Table 2.

<Storage Stability Test> In order to examine the storage stability of each of the above-mentioned moisture-curable resin compositions, the compositions were left in a sealed container at 70 ° C. for one day. Table 2 shows the thickening ratio after one day when the viscosity of the composition immediately after preparation was set to 1.

[0049]

As shown in Table 2, Comparative Example 1, which contains only ketimine 1 as a latent curing agent, has good storage stability, but has poor deep curability and cannot obtain a thick film. Also, as a latent curing agent, oxazolidine 2 which does not have so high steric hindrance around nitrogen in the heterocycle
It can be seen that Comparative Example 2 using No. 1 has good deep-section curability, but has very poor storage stability. On the other hand, all of Examples 1 to 3 using the oxazolidine of the present invention were excellent in deep part curability, and a cured film thickness of 5 mm could be obtained in one week. Moreover, it turns out that Examples 1-3 are excellent also in the storage stability compared with Comparative Example 2 using oxazolidine with small steric hindrance. In addition, since the thickening ratio of Example 2 is very low, the storage stability can be further improved by using a compound in which the OH group contained in the skeleton is 10 mol% or less as the polyepoxy compound. We can see that we can do it. Also, from Example 3, it was found that the use of ketimine 1 in combination with the oxazolidine of the present invention increased the surface curing rate, and also showed that storage stability could be improved while maintaining good deep-section curability. Understand.

The oxazolidine and moisture-curable resin composition of the present invention have been described above. However, the present invention is not limited to the above-described examples, and various improvements and modifications can be made without departing from the gist of the present invention. Of course it is good.

[0052]

According to the oxazolidine of the present invention, by using this oxazolidine as a latent curing agent for a curable resin composition, the composition has excellent storage stability and excellent deep-section curability. Can be
Further, according to the moisture-curable resin composition of the present invention, since a predetermined oxazolidine is used as a latent curing agent, storage stability, excellent deep-section curability, and a desired cured film thickness can be obtained. , Adhesives, sealants, paints and the like.

Claims (7)

[Claims] An oxazolidine represented by the following formula (1). Embedded image R ¹ : methyl group or ethyl group R ² : alkyl group having 1 to 6 carbon atoms R ³ : methyl group or ethyl group R ⁴ : hydrogen atom, methyl group or ethyl group R ⁵ : hydrogen atom or 1 to 6 carbon atoms Hydrocarbon group 2. The oxazolidine according to claim 1, wherein said R ¹ is a methyl group. 3. A moisture-curable resin composition comprising: a polyepoxy compound having two or more epoxy groups in a molecule; and the oxazolidine according to claim 1. 4. The moisture-curable resin composition according to claim 3, wherein said R ¹ is a methyl group. 5. The moisture-curable resin composition according to claim 3, further comprising a ketimine compound synthesized from a ketone or aldehyde represented by the following formula (2) and a polyamine. Moisture curable resin composition. Embedded image R ⁶ : hydrogen atom or methyl group R ⁷ : alkyl group having 1 to 6 carbon atoms R ⁸ : methyl group or ethyl group R ⁹ : hydrogen atom, methyl group or ethyl group 6. The moisture-curable resin composition according to claim 3, wherein the hydroxyl group contained in the skeleton of the polyepoxy compound is 10 mol% or less. 7. A latent curing agent comprising the oxazolidine according to claim 1 or 2, or comprising the oxazolidine and the ketimine compound according to claim 5.