JP2018131388A - Thioether-containing isocyanate and curable resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curing agent which is cured at low temperature and is used for obtaining a curable resin composition excellent in flexibility, and adhesion and barrier property under high temperature atmosphere at 70°C or higher.SOLUTION: A thioether-containing isocyanate compound is a reactant of an isocyanate-containing compound having a (meth)acryloyl group and a tris-[3-mercapto alkynyloxy)ethyl]isocyanurate. Among substituents of a derivative of a cyanuric acid substituted with an alkylcarboxyethyl group in which three nitrogen atoms are substituted with a thiol group or a sulfide group, at least one substituent is substituted with the sulfide group, and a terminal of the sulfide group is an isocyanate group.SELECTED DRAWING: None

Description

  The present invention is a thioether-containing isocyanate suitably used as an epoxy resin curing agent such as a sealing material or a sealing material that requires a barrier property, its use as a curing agent, and curability containing a thioether-containing isocyanate as a curing agent. The present invention relates to a resin composition.

  Conventionally, an epoxy resin has been used for a sealing material or a sealing material because a cured product thereof has excellent barrier properties. However, the cured product of the epoxy resin is relatively hard, and its use is limited due to its high curing temperature. For example, it has been difficult to use an epoxy resin as a sealing material for a liquid crystal panel based on a film or a panel for organic EL.

  In order to improve the above problem, Patent Document 1 discloses a sealing material for a plastic substrate comprising an epoxy resin, a modified polymercapto derivative, a curing accelerator, an inorganic filler, a silane coupling agent, and rubbery polymer particles. It is disclosed. The sealing material is cured at a low temperature of 60 to 100 ° C. in order to cure the modified polymercapto derivative to the epoxy resin as a curing agent. However, in order to improve flexibility, it is necessary to add rubber-like polymer particles, and this rubber-like polymer particles are a cause of lowering adhesion and barrier properties in a high-temperature atmosphere (70 ° C. or higher).

  Conventionally, the reaction between a polymercapto compound and an isocyanate is known as a click reaction, and a cured resin can be obtained at a relatively low temperature. For example, Patent Document 2 describes that a cured product of pentaerythritol mercaptocarboxylic acid ester and a polyisocyanate compound is used for a plastic lens or the like. Although the resin composition is cured at a low temperature of 120 ° C., pentaerythritol mercaptocarboxylic acid ester has a relatively low molecular weight, and the cured product has low flexibility and barrier properties. When a polymercapto compound having a molecular weight higher than that of pentaerythritol mercaptocarboxylic acid ester is used, compatibility with the polyisocyanate compound is deteriorated, so that flexibility and barrier properties may also be lowered.

WO2001 / 098411 JP-A-2005-336104

  As described above, it is required to obtain a curable resin composition that is excellent in flexibility, adhesion in a high temperature atmosphere of 70 ° C. or higher, and barrier properties in addition to being cured at a low temperature.

  The subject of this invention is providing the hardening | curing agent used in order to obtain the curable resin composition which is excellent in the softness | flexibility, adhesiveness in high temperature atmosphere of 70 degreeC or more, and barrier property while hardening at low temperature. is there.

（式（１）において、
ａは１〜３の整数であり、
ｂは０〜２の整数であり、
ａ＋ｂ＝３であり、
Ｒ^１は、下記式（２）で表される３価の基であり、
Ｒ^２は、下記式（３）または下記式（４）で表される２価の基であり、
Ｒ^３は、炭素数２〜６のアルキレン基である。）

（式（２）において、
Ｒ^４は、−ＣＨ_２−、−ＣＨ_２ＣＨ_２−、または−ＣＨ_２ＣＨ（ＣＨ_３）−である。）

（式（３）において、Ｒ^５は水素原子またはメチル基である。）

（式（４）において、Ｒ^５は水素原子またはメチル基である。） The present invention is as follows.
(1) A thioether-containing isocyanate represented by the following formula (1).

(In Formula (1),
a is an integer of 1 to 3,
b is an integer of 0-2,
a + b = 3,
R ¹ is a trivalent group represented by the following formula (2),
R ² is a divalent group represented by the following formula (3) or the following formula (4),
R ³ is an alkylene group having 2 to 6 carbon atoms. )

(In Formula (2),
R ⁴ _{is, -CH 2 -, - CH 2} CH 2 -, or _-CH 2 CH (CH ₃₎ - is. )

(In Formula (3), R ⁵ is a hydrogen atom or a methyl group.)

(In Formula (4), R ⁵ is a hydrogen atom or a methyl group.)

(2) A liquid curing agent for epoxy resin, comprising the thioether-containing isocyanate of (1).

(3) A barrier property improver comprising the thioether-containing isocyanate of (1).

(4) containing the thioether-containing isocyanate of (1) and an amine compound having a weight average molecular weight of 90 to 700,
The cured resin composition, wherein the amine compound is blended in an amount of 0.01 to 20 parts by mass with respect to 100 parts by mass of the thioether-containing isocyanate.

(5) containing the thioether-containing isocyanate of (1), and a polyfunctional epoxy resin having a weight average molecular weight of 200 to 50,000,
5 to 3000 parts by mass of the polyfunctional epoxy resin is blended with 100 parts by mass of the thioether-containing isocyanate.

  Since the thioether-containing isocyanate of the present invention has an isocyanate group, it can react with a compound having a plurality of hydroxyl groups or mercapto groups at a low temperature of 20 to 80 ° C. to obtain a cured resin. Moreover, since the isocyanuric ring is the main skeleton, a flexible cured product can be obtained. Furthermore, by having the thioether group in the vicinity of the isocyanuric ring, the packing property of the isocyanuric ring is enhanced by the chemical attraction between the thioether groups, and the barrier property of the cured resin is enhanced.

  The thioether-containing isocyanate of the present invention can be designed to have both an isocyanate group and a mercapto group in one molecule (for example, in the formula (1), (a, b) = (1, 2) or ( 2, 1)). In this case, it becomes a cured resin alone by using a base such as amine as a catalyst. Since such a cured resin is a homopolymer, there is no compatibility problem, and a cured product having a uniform and high barrier property can be obtained.

  Furthermore, the thioether-containing isocyanate having both the isocyanate group and the mercapto group can be used as a curing agent for the epoxy resin. When used as a curing agent for an epoxy resin, it reacts at a low temperature, and a cured product that is softer and tougher than when cured with a single epoxy resin can be obtained, and the barrier properties are also improved. When an epoxy resin reacts with a mercapto group, a hydroxyl group is generated. Since this hydroxyl group reacts with an isocyanate group of a thioether group-containing isocyanate, a flexible and tough cured product is formed.

The IR spectrum of raw material a-1 is shown. The IR spectrum of raw material a-2 is shown. The IR spectrum of Synthesis Example A-1 is shown. The IR spectrum of Synthesis Example A-2 is shown. The IR spectrum of Synthesis Example A-3 is shown.

Embodiments that embody the present invention will be described in detail below.
<Thioether-containing isocyanate>
The thioether-containing isocyanate of the present invention is a compound represented by the formula (1).

In Formula (1), R ¹ is a trivalent group represented by Formula (2), R ² is a divalent group represented by Formula (3) or Formula (4), and R ³ is an alkylene group having 2 to 6 carbon atoms.

Examples of the alkylene group having 2 to 6 carbon atoms as R ³ include a linear alkylene group, an alkylene group having a side chain, and a cyclic alkylene group. Examples of the linear alkylene group include an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group. Examples of the alkylene group having a side chain include an isopropylene group and an isobutylene group. Examples of the cyclic alkylene group include a cyclobutylene group. R ³ is preferably an alkylene group having 2 to 4 carbon atoms, particularly preferably a linear alkylene group having 2 to 4 carbon atoms because the distance between the thioether group and the isocyanate group is appropriate and easily exhibits a barrier property. Most preferred is an ethylene group.

  A in the formula (1) is an integer of 1 to 3, and a + b = 3. When the compound of formula (1) is used as a liquid curing agent for an epoxy resin, a must be 1 or 2 because the number of —SH groups (= b) that react with the epoxy group needs to be 1 or more. . Furthermore, a = 1 is preferable when the cured resin is expected to have high barrier properties, and a = 2 is preferable when the cured resin is expected to have high flexibility.

  In the case where the compound of the formula (1) is used as a barrier property improver and no epoxy resin is blended at the same time, a is preferably 2 or 3. In particular, when it is used in combination with a compound having a plurality of mercapto groups or hydroxyl groups, a = 3 is preferable.

R ⁴ in the formula (2) is —CH ₂ — (methylene group), —CH ₂ CH ₂ — (ethylene group) or —CH ₂ CH (CH ₃ ) — (isopropylene group). These are selected because the distance between the thioether group and the isocyanate group is appropriate and the barrier property is easily exhibited. From this viewpoint, an ethylene group and an isopropylene group are particularly preferable.

R ^{5 in} Formula (3) and Formula (4) is a hydrogen atom or a methyl group, and is preferably a methyl group from the viewpoint of the reactivity of the synthesis raw material.

<Liquid curing agent for epoxy resin>
The thioether-containing isocyanate of the present invention has a —SH group when a = 1 or 2 and can be particularly suitably used as a liquid curing agent for epoxy resins. When the thioether-containing isocyanate of the present invention is used as a curing agent, flexibility and adhesion in a high-temperature atmosphere of 70 ° C. or higher can be imparted to the epoxy resin.

  The epoxy resin in the present application is an organic compound having one or more epoxy groups (oxirane ring) in the molecule, and particularly preferably a polyfunctional epoxy resin having two or more epoxy groups in the molecule.

  The molecular weight of the polyfunctional epoxy resin is 200 to 50000, preferably 200 to 2000, more preferably 200 to 12000. Even if the molecular weight is less than 200, there is no problem with the adhesion, but the volatility of the polyfunctional epoxy resin tends to increase and the odor tends to increase. On the other hand, if the molecular weight is larger than 50000, the compatibility with the thioether group-containing isocyanate of the present application tends to be low, and the adhesion to the substrate tends to be reduced.

  The epoxy equivalent of the polyfunctional epoxy resin is 80 to 6000 g / mol, preferably 85 to 5500 g / mol, and more preferably 90 to 5000 g / mol. When the epoxy equivalent is less than 80 g / mol, there is a possibility that the epoxy group per unit volume becomes excessive and the flexibility becomes low. On the other hand, when the epoxy equivalent is larger than 6000 g / mol, the barrier property may be lowered because the epoxy group concentration is extremely low.

  Examples of the polyfunctional epoxy resin include a glycidyl ether type epoxy resin, a glycidyl ester type epoxy resin, a glycidyl amine type epoxy resin, or an oxidized type epoxy resin obtained by oxidizing a double bond of a double bond-containing compound with a peroxide. Etc. Among these, a glycidyl ether type epoxy resin and a glycidyl ester type epoxy resin are preferable because reactivity at room temperature is slow and usable time is long. In addition, a polyfunctional epoxy resin can also be used individually by 1 type, and 2 or more types can also be mixed and used for it.

[Glycidyl ether type epoxy resin]
As the glycidyl ether type epoxy resin, a reaction product of epichlorohydrin and a compound represented by the following general formula (5) is preferable.

C in the formula (5) is an integer of 2 to 30, R ⁶ is a hydrocarbon group having 2 to 200 carbon atoms (β1), ether oxygen having 2 to 300 carbon atoms (—O—) and hydrocarbon group only. A group consisting of (β2), an isocyanurate ring (β3), and a group (β4) consisting only of an isocyanurate ring and a hydrocarbon group.

Among the compounds represented by the general formula (5), the compound (β1-1) in which c is 2 to 20 and R ⁶ is a group consisting of a hydrocarbon group having 2 to 150 carbon atoms, or c is 2 to 20, and R ⁶ is a group consisting of only a hydrocarbon group having 2 to 150 carbon atoms and ether oxygen (—O—), and the compound (β2-1) has high solubility with other components. This is preferable. Examples of (β1-1) include alkylene diols having 2 to 10 carbon atoms, glycerin, pentaerythritol, trimethylolpropane, phenol novolac, and bisphenol A. Examples of (β2-1) include polyethylene glycol, polypropylene glycol, or dipentaerythritol.

The reaction between the epichlorohydrin and the compound represented by the general formula (5) is performed by adding chlorohydrin obtained by addition reaction of epichlorohydrin and the hydroxyl group of the compound represented by the general formula (5). Ring closure with a base such as sodium oxide provides an epoxy resin. The glycidyl ether type epoxy resin may be an epoxy resin obtained by ring-opening polymerization of a part of the epoxy group of the epoxy resin obtained after the ring-closing reaction.
A reaction product of epichlorohydrin and the compound represented by the general formula (5) has a structure represented by the following general formula (6).

C in the formula (6) is an integer of 2 to 30, R ⁶ is a hydrocarbon group having 2 to 200 carbon atoms (β1), ether oxygen having 2 to 300 carbon atoms (—O—) and hydrocarbon group only. A group (β2), an isocyanurate ring (β3), or a group (β4) consisting only of an isocyanurate ring and a hydrocarbon group.

[Glycidyl ester type epoxy resin]
The glycidyl ester type epoxy resin is a polymer or epi having a weight average molecular weight of 3000 to 20000 obtained by copolymerizing an epoxy group monomer such as glycidyl (meth) acrylate alone or with an alkyl (meth) acrylate having 4 to 25 carbon atoms. Reaction products of chlorohydrin and a compound represented by the following general formula (7).

D in the formula (7) is an integer of 2 to 8, and R ⁷ is a hydrocarbon group having 2 to 20 carbon atoms (β5), ether oxygen having 2 to 30 carbon atoms (—O—) and a hydrocarbon group only. A group (β6), an isocyanurate ring (β7), or a group (β8) consisting only of an isocyanurate ring and a hydrocarbon group.

  The reaction between epichlorohydrin and the compound represented by the general formula (7) is carried out by adding chlorohydrin obtained by addition reaction of epichlorohydrin and the carboxyl group of the compound represented by the general formula (7) to sodium hydroxide or the like. The glycidyl ester type epoxy resin can be obtained by ring closure with the above base. An epoxy resin obtained by ring-opening polymerization of a part of the epoxy group of the glycidyl ester type epoxy resin can also be used.

Among the compounds represented by the general formula (7), d is 2 to 4 and R ⁷ is a group composed of a hydrocarbon group having 2 to 10 carbon atoms, and the compound (β5-1), d is 2 It is 6, and ^{R 7} is a group consisting of only hydrocarbon groups and oxygen ethers having 2 to 30 carbon atoms (-O-) compound (β6-1), or r is 3, and ^{R 7} is A compound (β8-1), which is a group consisting only of an isocyanurate ring and a hydrocarbon group, is preferred because of its high solubility.

  Examples of (β5-1) include hydrophthalic acid and trimellitic acid. Examples of (β6-1) include a reaction product of pentaerythritol and trimellitic anhydride. Examples of (β8-1) include 1,3,5-tris (2-carboxyethyl) isocyanurate.

  A reaction product of epichlorohydrin and the compound represented by the general formula (7) has a structure represented by the following general formula (8).

D in Formula (8) is an integer of 2 to 8, R ⁷ is a hydrocarbon group having 2 to 20 carbon atoms (β5), ether oxygen having 2 to 30 carbon atoms (—O—) and hydrocarbon group only. A group (β6), an isocyanurate ring (β7), or a group (β8) consisting only of an isocyanurate ring and a hydrocarbon group.

  Moreover, when mix | blending the thioether containing isocyanate of this invention as a liquid hardening | curing agent for epoxy resins, it is preferable that the compounding quantity of an epoxy resin shall be 5-4000 mass parts with respect to 100 mass parts of thioether containing isocyanate. More preferably, it is set to ˜3000 parts by mass.

  The characteristics after curing the curable resin composition are strictly affected by the value of (thiol group number) / (epoxy group number) (hereinafter referred to as thiol / epoxy ratio) in the unit weight of the curable resin composition. . For example, when the thiol / epoxy ratio is in the range of 0.5 to 1.5, it is easy to form a dense cross-link, and to be a tough and highly cured product. On the other hand, if the thiol / (epoxy + ene) ratio is 0.1 or more and less than 0.5, or more than 1.5 and 2.0 or less, a flexible and sticky cured product can be obtained. If the thiol / (epoxy + ene) ratio is less than 0.1 or exceeds 2.0, the curability tends to deteriorate, and the adhesion and barrier properties tend to decrease.

<Barrier improver>
The thioether-containing isocyanate of the present invention is particularly suitable as a moisture-resistant barrier property improver for resins, and can impart barrier properties in a high-temperature and high-humidity atmosphere to epoxy resins. Such barrier properties can be evaluated by adhesion under high humidity and high temperature conditions described in Examples.

  Examples of such resins include compounds (= resins) having two or more functional groups in one molecule that react with —SH groups or isocyanate groups in addition to the epoxy resins listed above.

  As the functional group that reacts with the —SH group, a C═C bond is particularly preferable. A compound having two or more C═C bonds in one molecule is called a polyfunctional ene compound.

  Examples of the polyfunctional ene compound include polyfunctional (meth) acrylate, polyfunctional allyl, and polyfunctional vinyl ether. As a polyfunctional ene compound, only 1 type can also be used independently and 2 or more types can also be mixed and used.

The (meth) acrylate equivalent of the polyfunctional (meth) acrylate is preferably 80 to 400 g / mol.
The allyl equivalent of the polyfunctional allyl is preferably 80 to 200 g / mol.

The vinyl ether equivalent of the polyfunctional vinyl ether is preferably 60 to 200 g / mol. The weight average molecular weight of the polyfunctional ene is preferably 100 to 1,000. Even if the weight average molecular weight of the polyfunctional ene is less than 100, there is no problem with the adhesion, but the volatility tends to increase and the odor tends to increase. On the other hand, when the weight average molecular weight is larger than 1,000, there is no problem with the adhesion, but the solubility in the thioether group-containing isocyanate of the present application may be lowered.

As a functional group that reacts with an isocyanate group, a hydroxyl group is particularly preferred. A compound having two or more hydroxyl groups in one molecule is called a polyfunctional alcohol.
The hydroxyl equivalent of the polyfunctional alcohol is preferably 60 to 600 g / mol.

  The weight average molecular weight of the polyfunctional alcohol is preferably 100 to 10,000. Even if the weight average molecular weight of the polyfunctional ene is less than 100, there is no problem with the adhesion, but the volatility tends to increase and the odor tends to increase. On the other hand, if the weight average molecular weight is greater than 10,000, there is no problem with the adhesion, but the solubility in the thioether group-containing isocyanate of the present application may be low.

<Amine compound>
The amine compound of the present invention is added to promote (catalyze) the reaction between the thioether group-containing isocyanate and various compounds (= resins). Examples of the amine compound include monofunctional amines and polyamines having a molecular weight of 90 to 700, preferably 100 to 600, more preferably 110 to 400 and having a plurality of amino groups. When the molecular weight of the amine compound is less than 90, not only the volatility of the amine is increased, causing odors and voids, but also the amine concentration at the time of heat curing is lowered, so that the crosslinking reaction is difficult to proceed and the adhesion is lowered. It becomes easy. When the molecular weight of the amine compound exceeds 700, the water resistance becomes low and the adhesion tends to be lowered.

  Monofunctional amines include primary amines, secondary amines, or tertiary amines. Examples of polyamines include primary amines, secondary amines, tertiary amines, and complex amines. A complex amine is an amine having two or more of a primary amino group, a secondary amino group, and a tertiary amino group. Examples of such complex amines include imidazoline compounds, imidazole compounds, N-substituted piperazine compounds, N, N-dimethylurea derivatives, and the like. In addition, an amine compound can also be used individually by 1 type, and 2 or more types can also be mixed and used for it.

  The amine compound may form a salt with an organic acid in advance in order to adjust the catalytic activity. Examples of the organic acid to be reacted in advance with the amine compound include aliphatic carboxylic acids such as stearic acid and 2-ethylhexanoic acid having 1 to 5 carbon atoms and 1 to 5 carboxyl groups in the molecule, and carboxyl groups having 1 to 20 carbon atoms. Examples thereof include aromatic carboxylic acids such as pyromellitic acid, trimellitic acid and benzoic acid having 1 to 10 groups in the molecule, or isocyanuric acid. Moreover, an amine compound may be mix | blended after forming an adduct with a polyfunctional epoxy resin in order to adjust catalyst activity.

[Imidazole compound]
Of the amine compounds, imidazole compounds are most suitable for achieving both storage stability and curing time at low temperatures. Further, an imidazole compound coated with a phenol resin or the like can also be used.
Specifically, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1,2-dimethylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methyl Imidazole, 1-benzyl-2-phenylimidazole, 2-ethyl-4-methylimidazole, 1- (2-cyanoethyl) -2-methylimidazole, 1- (2-cyanoethyl) -2-undecylimidazole, 1- ( 2-cyanoethyl) -2-ethyl-4-methylimidazole, 1- (2-cyanoethyl-2-phenylimidazole), 1- (2-cyanoethyl) -2-ethyl-4-methylimidazole, 2,3-dihydro-1H -Pyrrolo [1,2-a] benzimidazole, 2,4-diamino-6- [2- Methylimidazolyl- (1)] ethyl-s-triazine, 2,4-diamino-6- [2′-undecylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [ 2'-ethyl-4'-methylimidazolyl- (1 ')]-ethyl-s-triazine, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole It is done.

<Curing resin composition>
The cured resin composition of the present invention is
The thioether-containing isocyanate of the present invention, and an amine compound having a weight average molecular weight of 90 to 700,
The amine compound is blended in an amount of 0.01 to 20 parts by mass, preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the thioether-containing isocyanate.

  The thioether-containing isocyanate of the present invention can be used alone as a cured resin by using a base such as an amine as a catalyst. In this case, since it is a single substance, there is no compatibility problem, and a cured product having a uniform and high barrier property can be obtained.

<Epoxy cured resin composition>
The epoxy cured resin composition of the present invention is
The thioether-containing isocyanate of the present invention, and a polyfunctional epoxy resin having a weight average molecular weight of 200 to 50,000,
The polyfunctional epoxy resin is blended in an amount of 5 to 3000 parts by mass, preferably 10 to 3000 parts by mass, with respect to 100 parts by mass of the thioether-containing isocyanate. By curing such a composition, adhesion and barrier properties under a high-temperature atmosphere of 70 ° C. or higher can be particularly improved.

<Method for producing thioether-containing isocyanate>
For example, an isocyanate group-containing compound having a (meth) acryloyl group as represented by formula (9) (hereinafter referred to as (X) component) and a polythiol having a thiol group (—SH) represented by formula (10) A thioether-containing isocyanate represented by the formula (1) can be obtained by reacting a valent thiol compound (hereinafter referred to as (Y) component).
In the present specification, “(meth) acryloyl group” is a concept including both “methacryloyl group” and “acryloyl group”.

In Formula (9), R ³ is an alkylene group having 2 to 6 carbon atoms, and R ⁸ is a hydrogen atom or a methyl group.

In Formula (10), R ⁴ is —CH ₂ —, —CH ₂ CH ₂ —, or —CH ₂ CH (CH ₃ ) —.

  Preferred examples of the component (X) represented by the formula (9) include 2-isocyanatoethyl methacrylate.

  As the component (Y) represented by the formula (10), tris-[(3-mercaptopropionyloxy) -ethyl] -isocyanurate, tris-[(3-mercaptobutyryloxy) -ethyl]]-isocyanurate , Tris-[(3-mercaptobutyryloxy) -ethyl]]-isocyanurate.

  In order to produce the thioether-containing isocyanate of this embodiment, the component (X) and the component (Y) can be reacted at a temperature of 5 ° C. or higher, but are preferably reacted at 60 to 100 ° C. When the reaction is performed at 60 ° C. or higher, the reaction can be performed in a short time such as within 5 hours. Moreover, reaction with isocyanate and -SH group can be suppressed by making it react at 120 degrees C or less. From the viewpoint of suppressing the reaction between the isocyanate and the —SH group, the reaction is more preferably performed at 80 to 90 ° C. If a base catalyst and a radical generator are added, it can be made to react in a high yield in a shorter time.

  As the basic catalyst, amine-based basic catalysts are preferable, and primary, secondary or tertiary amines, or imidazole compounds can be used.

  For example, examples of the primary amine include methylamine, ethylamine, propylamine, butylamine, and ethylenediamine. Secondary amines include dimethylamine, diethylamine, dipropylamine, methylethylamine, diphenylamine and the like. Tertiary amines include trimethylamine, triethylamine, tripropylamine, triphenylamine, 1,8-diazabicyclo [5.4.0] undeca-aminomethyl) phenol, and the like.

  Examples of imidazole compounds include 1-methylimidazole, 1,2-dimethylimidazole, 1,4-dimethyl-2-ethylimidazole, imidazole analogues such as 1-phenylimidazole, 1-methyl-2-oxymethylimidazole, Alkyl derivatives such as 1-methyl-2-oxyethylimidazole, nitro and amino derivatives such as 1-methyl-4 (5) -nitroimidazole, 1,2-dimethyl-5 (4) -aminoimidazole, benzimidazole, 1 -Methylbenzimidazole, 1-methyl-benzylbenzimidazole and the like.

  As the radical generator, a peroxide or an azo compound is preferable. Examples of the peroxide include dibenzoyl peroxide, tert-butylperoxy-2-ethylhexanoate, and dilauroyl peroxide. Examples of the azo compound include azobis (iso-butyronitrile) and 2,2′-azobis (2-methylbutanenitrile).

  In this method for producing a thioether-containing isocyanate, the reaction can be allowed to proceed even without a solvent. However, when the viscosity is to be lowered, such as when the reaction is carried out at a low temperature, the reaction can be carried out by adding a solvent. In that case, the solvent which does not react with the carbon-carbon double bond of a (meth) acryloxy group or a thiol group, for example, ketones and esters, are preferable.

  Ketones used as solvents are functional groups such as carbon-carbon double bonds and carbon-carbon double bonds that react with thiol groups, thiol groups, epoxy groups, isocyanate groups, carboxyl groups, sulfonyl groups, nitrile groups, and halogen atoms. Must not contain groups. Examples of the ketones that do not contain the functional group include acetone, methyl ethyl ketone, methyl isobutyl ketone, and methyl isopropyl ketone. Of these, ketones having a boiling point of 80 ° C. or higher are preferable because the reaction temperature can be kept high.

  Esters used as solvents include carbon-carbon double bonds and carbon-carbon double bonds that react with thiol groups, thiol groups, epoxy groups, isocyanate groups, carboxyl groups, sulfonyl groups, nitrile groups, halogen atoms, and other functional groups. Must not contain groups. Examples of ketones that do not contain the above functional group include ethyl acetate, butyl acetate, ethyl benzoate, and propylene glycol acetate. Of these, esters having a boiling point of 80 ° C. or higher are preferable because the reaction temperature can be kept high.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

(Synthesis Examples A-1 to A-3)
First, in Synthesis Examples A-1 to A-3, thioether-containing isocyanates (synthesis products A-1 to A-3) were synthesized using the following components a-1 and a-2. The a-1 component and a-2 component used are as follows. The viscosity at 25 ° C. of each component was measured using an R-type viscometer manufactured by Toki Sangyo Co., Ltd.

<Multivalent thiol compound>
a-1: Tris-[(3-mercaptopropionyloxy) -ethyl] -isocyanurate. The structure is shown below (viscosity 5.4 Pa · s, temperature: 25 ° C.).

<Isocyanate-containing acrylate>
a-2: 2-isocyanatoethyl methacrylate. The structure is shown below (viscosity 1.4 mPa · s, temperature 25 ° C.).

[Synthesis of thioether-containing isocyanate]
Into a three-necked flask equipped with a thermometer, a stirrer, and a dropping pump, the a-1 component was charged according to the following Table 1, and after raising the temperature to 60 ° C., the a-2 component was added dropwise over 1 hour. After completion of dropping, the mixture was further stirred at 60 ° C. for 2 hours for reaction. Table 1 shows the viscosity of the mixture before and after the reaction. The viscosity was measured under the following conditions using an R-type viscometer manufactured by Toki Sangyo Co., Ltd.
(Before reaction)
Rotor used: 1 ° 34 '× R24
Measurement range: 0.1 mPa · s to 103.7 Pa · s
(After reaction)
Rotor used: 3 ° x R14
Measurement range: 5.002 to 1000 Pa · s

  Since the viscosities of the products obtained in Synthesis Examples A-1 to A-3 were all higher than the viscosities of a-1 and a-2, which are the raw materials, it was found that the raw materials were reacted.

[Infrared absorption spectrum analysis (IR)]
The obtained composite was subjected to infrared absorption spectrum analysis (IR) under the following conditions. IR spectra of raw materials a-1 and a-2 and products A-1 to A-3 are shown in FIGS.

Model: TravelIR, manufactured by SENSIR (USA)
Cell: Expanded on Ge, decomposed; 8 cm −1, cumulative number: 32 times

Peak around 1635 cm ^-1 and 950 cm ^-1 of the material a-1 is a peak derived from C = C. Since the products of Synthesis Examples A-1 to A-3 did not have the above peak, it was found that C = C of a-2 reacted with -SH of a-1. In addition, the products of Synthesis Examples A-1 to A-3 have a peak in the vicinity of 2270 cm ⁻¹ . This is a peak derived from an isocyanate group, and it was found that the isocyanate group did not react.

(Examples 2-1 to 2-4, Comparative examples 2-1 to 2-2)
In Examples 2-1 to 2-4, the following performance was evaluated for the mixture of the composites A-1 to A-2 and the amine compounds B-1 to B-4. The results are shown in Table 2. Moreover, the following performance was evaluated with respect to the mixture of a-1 and 2 which are a raw material, and amine compound B-1 as a comparative example. The results are shown in Table 3.

<B component>
B-1: Tris (2-ethylhexyl) amine (Mw: 353.7)
B-2: Aniline (Mw: 93.1)
B-3: DBU (diazabicycloundecene, Mw: 152.2)
B-4: 2-Phenylimidazole (Mw: 144.2)

[Flexibility evaluation]
A 25 mm wide PET film (A4300, manufactured by Toyobo Co., Ltd., thickness 50 μm) was used as a base material, and each sample was coated on the base material with a bar coater to a thickness of 30 μm. A test piece was prepared by heating for a period of time to form a cured film on each substrate. The test piece was folded so that the cured film coating surface was a mountain, and the crease was crushed with a rubber roller. Then, after returning the crease of the test piece to the original state, the cured film coating surface of the portion that was the crease was visually observed. Those with cracks or whitening were marked with x, and others were marked with ◯. Furthermore, what was not cracked or whitened even if folding was repeated 5 times was marked with ◎. The results are shown in Tables 2 and 3.

[Adhesion evaluation]
JIS K5600-5-6: Adhesiveness was evaluated by a mechanical property-adhesiveness (cross-cut method) test method of the coating film.
Using alkali-free glass (OA-10, manufactured by Nippon Electric Glass Co., Ltd., thickness 0.7 mm) as a base material, each sample was coated on the base material with a bar coater to a thickness of 100 μm, and 80 ° C. And heated for 3 hours to form a cured film on each substrate to prepare a test piece. The evaluation criteria were ○ where no peeling occurred and × otherwise. The results are shown in Tables 2 and 3.

[Barrier property evaluation]
JIS K5600-5-6: Mechanical properties of the coating film-Adhesion (cross-cut method) The barrier property was evaluated according to the adhesion state by the test method.
Using a non-alkali glass (OA-10, manufactured by Nippon Electric Glass Co., Ltd., thickness 0.7 mm) as a base material, each sample was coated on the base material with a bar coater to a thickness of 300 μm, and 80 ° C. And heated for 3 hours to form a cured film on each substrate to prepare test pieces. Further, the test piece was left in an atmosphere of 85 ° C. × 85% RH for 1000 hours to evaluate the adhesion. The evaluation criteria were ○ where no peeling occurred and × otherwise. Furthermore, what was not peeled at all even if the test piece was left in an atmosphere of 85 ° C. × 85% RH for 3000 hours was marked with “◎”. The results are shown in Tables 2 and 3.
The cured film having low barrier properties is permeable to moisture and accumulates between the cured film and the base material, so that the adhesion decreases.

  From Table 2, it was found that all the mixtures of Examples 2-1 to 4 were cured at 80 ° C. for 3 hours, and the cured films had flexibility, adhesion, and barrier properties. A cured film is obtained by the reaction between the thiol group and the isocyanate group of the composite A-1 or A-2.

(Examples 3-1 to 3-9, Comparative examples 3-1 to 3-7)
As Examples 3-1 to 3-9, the performance was evaluated for a mixture having the composition shown in Table 4. Evaluation items are the same as those in Examples 2-1 to 2-4. The results are shown in Table 4. Moreover, performance was evaluated with respect to the mixture of the composition shown in Table 5 as Comparative Examples 3-1 to 3-7. Evaluation items are the same as those in Examples 2-1 to 2-4. The results are shown in Table 5.

From Table 4, it turned out that the cured film has a softness | flexibility, adhesiveness, and barrier property (moisture barrier property in 85 degreeC) in all the Examples. Moreover, it turned out that the cured film of the mixture which does not contain thioether containing isocyanate has no barrier property uniformly from the comparative example. Moreover, in each comparative example except comparative example 3-3, it turned out that a softness | flexibility is also low.

Claims (5)

The thioether containing isocyanate represented by following formula (1).

(In Formula (1),
a is an integer of 1 to 3,
b is an integer of 0-2,
a + b = 3,
R ¹ is a trivalent group represented by the following formula (2),
R ² is a divalent group represented by the following formula (3) or the following formula (4),
R ³ is an alkylene group having 2 to 6 carbon atoms. )

(In Formula (2),
R ⁴ _{is, -CH 2 -, - CH 2} CH 2 -, or _-CH 2 CH (CH ₃₎ - is. )

(In Formula (3), R ⁵ is a hydrogen atom or a methyl group.)

(In Formula (4), R ⁵ is a hydrogen atom or a methyl group.)
  A liquid curing agent for epoxy resin, comprising the thioether-containing isocyanate according to claim 1.   A barrier property improver comprising the thioether-containing isocyanate according to claim 1. The thioether-containing isocyanate according to claim 1, and an amine compound having a weight average molecular weight of 90 to 700,
A curable resin composition comprising 0.01 to 20 parts by mass of the amine compound based on 100 parts by mass of the thioether-containing isocyanate. The thioether-containing isocyanate according to claim 1, and a polyfunctional epoxy resin having a weight average molecular weight of 200 to 50,000,
5 to 3000 parts by mass of the polyfunctional epoxy resin is blended with 100 parts by mass of the thioether-containing isocyanate.

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