Microcapsule and method for producing same

Abstract

The microcapsule has a core-shell structure. A microcapsule is provided with a shell layer and a core layer encapsulated in the shell layer. The shell layer contains a urethane-urea resin. The urethane-urea resin contains a reaction product of a first polyisocyanate and an active hydrogen compound. The core layer contains a second polyisocyanate. The reactivity of the first polyisocyanate with the active hydrogen compound is higher than the reactivity of the second polyisocyanate with the active hydrogen compound.

Description

Technical Field

[0001] This invention relates to microcapsules and methods for manufacturing the same. Background Technology

[0002] Microcapsules containing isocyanate compounds are known in the past. Microcapsules, for example, contain a coating formed of a thermoplastic resin and an isocyanate compound contained within the coating. Such microcapsules are widely used, for example, as curing agents for resin compositions in the manufacture of cured resin products.

[0003] More specifically, isocyanate-containing microcapsules are known as microcapsules in which the coating is formed of a thermoplastic resin. Furthermore, the isocyanate compound is dissolved or dispersed in a hydrophobic organic compound that does not have polar functional groups. The isocyanate compound is contained within the coating. TAKENATE D-178N (trade name, manufactured by Mitsui Chemicals) is proposed as such an isocyanate compound. Additionally, a polymeric coating obtained by interfacial polymerization of an isocyanate compound (TAKENATE D-178N (trade name, manufactured by Mitsui Chemicals)) with diethylenetriamine in the presence of isoparaffin and ethyl acetate at 60°C is proposed (see, for example, Patent Document 1 (Example 3)).

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2006-061802 Summary of the Invention

[0005] The problem that the invention aims to solve On the other hand, from the viewpoint of obtaining resin-cured products with excellent mechanical properties, isocyanate-containing microcapsules require a sufficient amount of isocyanate groups. Furthermore, isocyanate-containing microcapsules require excellent storage stability.

[0006] However, the aforementioned isocyanate-containing microcapsules sometimes do not have a sufficient amount of isocyanate groups, and in addition, they sometimes do not have excellent storage stability.

[0007] This invention relates to microcapsules with excellent isocyanate group content and storage stability, and a method for manufacturing the same.

[0008] Methods for solving problems The present invention [1] includes microcapsules, which are microcapsules with a core-shell structure. The microcapsules have a shell and a core encapsulated in the shell. The shell contains urethane urea resin, the urethane urea resin contains a reaction product of a first polyisocyanate and an active hydrogen compound, and the core contains a second polyisocyanate. The reactivity of the first polyisocyanate with the active hydrogen compound is higher than that of the second polyisocyanate with the active hydrogen compound.

[0009] The present invention [2] comprises the microcapsules described in [1] above, wherein the aforementioned reactivity is in the order of the following formulas.

[0010] Aromatic polyisocyanates, aromatic aliphatic polyisocyanates > aliphatic polyisocyanates > alicyclic polyisocyanates without secondary isocyanate groups > alicyclic polyisocyanates containing secondary isocyanate groups The present invention [3] comprises the microcapsules described in [1] or [2] above, wherein the aforementioned active hydrogen compound contains an amino-containing compound.

[0011] The present invention [4] comprises microcapsules as described in any one of [1] to [3] above, wherein the average isocyanate base number of the first polyisocyanate is 2.5 or more, and the average isocyanate base number of the second polyisocyanate is 2.5 or more.

[0012] The present invention [5] comprises microcapsules as described in any one of [1] to [4] above, wherein the first polyisocyanate has an isocyanurate backbone and the second polyisocyanate has an isocyanurate backbone.

[0013] The present invention [6] comprises microcapsules as described in any one of [1] to [5] above, wherein the aforementioned first polyisocyanate has a hydrophilic group.

[0014] The present invention [7] comprises the microcapsules described above [6], wherein the aforementioned hydrophilic group of the first polyisocyanate has a nonionic group.

[0015] The present invention [8] comprises microcapsules as described in any one of [1] to [7] above, wherein the aforementioned second polyisocyanate does not have a hydrophilic group.

[0016] The present invention [9] includes a method for manufacturing microcapsules, the method being the method for manufacturing microcapsules according to any one of [1] to [8] above, comprising: a preparation step of preparing an isocyanate mixture containing the aforementioned first polyisocyanate and the aforementioned second polyisocyanate; and a reaction step of mixing the aforementioned isocyanate mixture with the aforementioned active hydrogen compound in the presence of a hydrophobic solvent with a ClogP value of 2.0 to 5.0, and performing interfacial polymerization of the aforementioned first polyisocyanate and the aforementioned active hydrogen compound in such a manner as to contain the aforementioned second polyisocyanate, thereby forming the aforementioned shell layer and a core layer encapsulated in the aforementioned shell layer.

[0017] The present invention

[10] includes a method for manufacturing microcapsules as described in [9] above, wherein, in the aforementioned reaction step, firstly, a mixture containing the aforementioned isocyanate mixture and the aforementioned hydrophobic solvent is added to an aqueous solution containing an emulsifier to prepare an O / W emulsion, and then, the aforementioned active hydrogen compound is added to the aforementioned O / W emulsion to allow the aforementioned first polyisocyanate to undergo interfacial polymerization with the aforementioned active hydrogen compound.

[0018] Invention Effects In the microcapsules of the present invention, the first and second polyisocyanates are selected based on their differences in reactivity with active hydrogen compounds. More specifically, the more reactive first polyisocyanate forms a shell containing a urethane urea resin. Furthermore, the less reactive second polyisocyanate is encapsulated (contained) within the shell as a core layer. Therefore, compared to the case where the first and second polyisocyanates are of the same type, the above-described microcapsules exhibit superior isocyanate group content and storage stability.

[0019] Furthermore, the microcapsule manufacturing method according to the present invention can efficiently obtain the above-mentioned microcapsules. Detailed Implementation

[0020] 1. Microcapsules Microcapsules have a core-shell structure. More specifically, microcapsules have a shell and a core encapsulated (included) within the shell.

[0021] (1) Shell [Carbamate-Urea Resin] The shell layer is a wall material containing the core layer described later. The shell layer contains urethane urea resin. The shell layer is preferably formed of urethane urea resin. The urethane urea resin is a thermoplastic resin having urethane groups and / or urea groups.

[0022] The urethane-urea resin is obtained by reacting a first polyisocyanate (shell polyisocyanate) with an active hydrogen compound. That is, the urethane-urea resin contains the reaction product of the first polyisocyanate and the active hydrogen compound.

[0023] [First Polyisocyanate] Examples of first-order polyisocyanates include polyisocyanate compounds. A polyisocyanate compound is an organic compound having two or more isocyanate groups in one molecule.

[0024] Examples of polyisocyanate compounds include aromatic polyisocyanates, aromatic aliphatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates.

[0025] Examples of aromatic polyisocyanates include aromatic polyisocyanate monomers and their derivatives. Examples of aromatic polyisocyanate monomers include aromatic diisocyanates. Examples of aromatic diisocyanates include diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), toluidine diisocyanate (TODI), terephthalic diisocyanate, and naphthalene diisocyanate (NDI). Examples of derivatives include modified aromatic polyisocyanate monomers. Examples of modified derivatives include urea diketone modified derivatives, isocyanurate modified derivatives, urea carbamate modified derivatives, polyol modified derivatives (adducts), biuret modified derivatives, urea modified derivatives, oxadiazine trione modified derivatives, and carbodiimide modified derivatives. These can be used alone or in combination of two or more.

[0026] Examples of aromatic aliphatic polyisocyanates include aromatic aliphatic polyisocyanate monomers and their derivatives. Examples of aromatic aliphatic polyisocyanate monomers include aromatic aliphatic diisocyanates. Examples of aromatic aliphatic diisocyanates include phenylene diisocyanate (XDI) and tetramethylphenylene diisocyanate (TMXDI). Various modified derivatives of the above can be used as derivatives. They can be used alone or in combination of two or more.

[0027] Examples of aliphatic polyisocyanates include chain-like aliphatic polyisocyanates. Examples of chain-like aliphatic polyisocyanates include chain-like aliphatic polyisocyanate monomers and their derivatives. Examples of chain-like aliphatic polyisocyanate monomers include chain-like aliphatic diisocyanates. Examples of chain-like aliphatic diisocyanates include ethylene diisocyanate, 1,3-propanediisocyanate, 1,4-butanediisocyanate, 1,5-pentanediisocyanate (PDI), and 1,6-hexamethylenediisocyanate (HDI). Various modified derivatives of the above can be included. They can be used alone or in combination of two or more.

[0028] Examples of alicyclic polyisocyanates include alicyclic polyisocyanates containing at least one secondary isocyanate group (alicyclic polyisocyanates containing a secondary isocyanate group) and alicyclic polyisocyanates not containing a secondary isocyanate group (alicyclic polyisocyanates not containing a secondary isocyanate group).

[0029] It should be noted that the order of the isocyanate group is defined by the number of carbon atoms bonded to the carbon atom directly bonded to the isocyanate group.

[0030] More specifically, when the carbon atom (C) directly bonded to the isocyanate group (-NCO) is bonded to one carbon atom, the isocyanate group is defined as a primary isocyanate group.

[0031] In addition, when the carbon atom (C) directly bonded to the isocyanate group (-NCO) is bonded to two carbon atoms, the isocyanate group is defined as a secondary isocyanate group.

[0032] In addition, when the carbon atom (C) directly bonded to the isocyanate group (-NCO) is bonded to three carbon atoms, the isocyanate group is defined as a tertiary isocyanate group.

[0033] As an alicyclic polyisocyanate containing a secondary isocyanate group, examples include polyisocyanates that contain only secondary isocyanate groups and do not contain primary or tertiary isocyanate groups as isocyanate groups. Furthermore, as an alicyclic polyisocyanate containing a secondary isocyanate group, examples include polyisocyanates that contain both primary and secondary isocyanate groups but do not contain tertiary isocyanate groups.

[0034] As alicyclic polyisocyanates containing a secondary isocyanate group, more specifically, examples include alicyclic polyisocyanate monomers containing a secondary isocyanate group and their derivatives. As alicyclic polyisocyanate monomers containing a secondary isocyanate group, examples include alicyclic diisocyanates containing a secondary isocyanate group. As alicyclic diisocyanates containing a secondary isocyanate group, examples include cyclohexane diisocyanate and methylene bis(cyclohexyl)isocyanate (H... 12 MDI), isophorone diisocyanate (IPDI), and norbornene diisocyanate (NBDI). Various modified derivatives of the above can be cited. They can be used alone or in combination of two or more.

[0035] As an alicyclic polyisocyanate that does not contain a secondary isocyanate group, examples include polyisocyanates that contain only a primary isocyanate group and do not contain secondary or tertiary isocyanate groups as isocyanate groups.

[0036] As alicyclic polyisocyanates without secondary isocyanate groups, more specifically, examples include alicyclic polyisocyanate monomers and their derivatives without secondary isocyanate groups. Examples of alicyclic polyisocyanate monomers without secondary isocyanate groups include alicyclic diisocyanates without secondary isocyanate groups. Examples of alicyclic diisocyanates without secondary isocyanate groups include bis(isocyanatomethyl)cyclohexane (H6XDI). Various modified derivatives described above can be used as derivatives. They can be used alone or in combination of two or more.

[0037] Polyisocyanate compounds can be used alone or in combination of two or more. Derivatives are preferred examples of polyisocyanate compounds.

[0038] That is, the polyisocyanate compound in the first polyisocyanate is preferably an aromatic polyisocyanate derivative, an aromatic aliphatic polyisocyanate derivative, an aliphatic polyisocyanate derivative, or an alicyclic polyisocyanate derivative.

[0039] As derivatives, isocyanurate-modified products and polyol-modified products (adducts) are preferred examples, and isocyanurate-modified products are more preferred examples.

[0040] In other words, the first polyisocyanate preferably has an isocyanurate backbone and / or a carbamate backbone, and more preferably has an isocyanurate backbone.

[0041] It should be noted that the types of polyisocyanates in the first polyisocyanate (shell polyisocyanate) are selected based on the types of polyisocyanates in the second polyisocyanate (nuclear polyisocyanate) described later, as detailed below.

[0042] Details regarding the selection of polyisocyanate compounds are described below.

[0043] [Hydrophilic group] The first polyisocyanate preferably has a hydrophilic group. If the first polyisocyanate has a hydrophilic group, microcapsules can be obtained more efficiently through interfacial polymerization as described later. Furthermore, if the first polyisocyanate has a hydrophilic group, the dispersibility of the microcapsules in water can be improved. Examples of hydrophilic groups include nonionic and ionic groups, with nonionic groups being preferred. That is, the first polyisocyanate preferably has a nonionic group and / or an ionic group, and more preferably a nonionic group.

[0044] More specifically, as the first polyisocyanate, a polyisocyanate containing a hydrophilic group is preferably provided. A polyisocyanate containing a hydrophilic group can be obtained, for example, by reacting the above-mentioned polyisocyanate compound with an active hydrogen compound containing a hydrophilic group (hereinafter, an active hydrogen compound containing a hydrophilic group).

[0045] Examples of active hydrogen compounds containing hydrophilic groups include active hydrogen compounds containing nonionic groups and active hydrogen compounds containing ionic groups.

[0046] An active hydrogen compound containing a nonionic group is an organic compound having at least one nonionic group and at least one active hydrogen group.

[0047] Examples of nonionic groups include monoterminated polyoxyethylene. That is, a nonionic group is defined as a polyoxyethylene whose monoterminus is blocked by an alkoxy group (e.g., an alkoxy group with 1 to 4 carbon atoms). Polyoxyethylene (i.e., polyoxyethylene glycol) whose monoterminus is not blocked but has hydroxyl groups at both ends are active hydrogen compounds (high molecular weight polyols) described later and are not included in compounds containing active hydrogen groups that contain nonionic groups.

[0048] Examples of active hydrogen groups include hydroxyl and amino groups, with hydroxyl being the preferred example.

[0049] More specifically, compounds containing nonionic groups and active hydrogen groups include mono-terminated (mono-terminated alkoxy-blocked) polyethylene oxide glycols and polyols containing nonionic side chains, with mono-terminated (mono-terminated alkoxy-blocked) polyethylene oxide glycols being preferred. More specifically, examples of mono-terminated (mono-terminated alkoxy-blocked) polyethylene oxide glycols include, for instance, polyethylene oxide methyl ether and polyethylene oxide ethyl ether. These can be used alone or in combination of two or more.

[0050] The number-average molecular weight (based on GPC measurements converted to polystyrene) of compounds containing nonionic groups and active hydrogen groups is, for example, 200 to 2000, preferably 400 to 1000.

[0051] An active hydrogen compound containing an ionic group is an organic compound having at least one ionic group and at least one active hydrogen group.

[0052] Examples of ionic groups include anionic and cationic groups, with anionic groups being preferred. Examples of anionic groups include carboxyl and sulfonyl groups, with carboxyl groups being preferred. That is, as an active hydrogen compound containing an ionic group, an active hydrogen compound containing a carboxyl group is preferred.

[0053] Examples of compounds containing a carboxyl group and an active hydrogen group include carboxyl-containing diols. Examples of carboxyl-containing diols include dihydroxyalkyl acids. Examples of dihydroxyalkyl acids include 2,2-dihydroxymethylacetic acid, 2,2-dihydroxymethyllactic acid, 2,2-dihydroxymethylpropionic acid (also known as dihydroxymethylpropionic acid), 2,2-dihydroxymethylbutyric acid, 2,2-dihydroxymethylbutyric acid, and 2,2-dihydroxymethylvalerate. These can be used alone or in combination of two or more.

[0054] As an active hydrogen compound containing a hydrophilic group, an active hydrogen compound containing a nonionic group is preferred, a single-terminal blocked (single-terminal alkoxy blocked) polyoxyethylene glycol is more preferred, and polyoxyethylene methyl ether is even more preferred.

[0055] There are no particular limitations on the method for obtaining polyisocyanates containing hydrophilic groups. For example, the above-mentioned polyisocyanate compound can be mixed with an active hydrogen compound containing hydrophilic groups and heated, with or without a known organic solvent.

[0056] The mixing ratio can be appropriately set within a range where the isocyanate groups of the polyisocyanate compound are excessive relative to the active hydrogen groups of the active hydrogen compound containing hydrophilic groups. For example, the lower limit of the isocyanate group equivalence ratio (isocyanate group / active hydrogen group) of the polyisocyanate compound relative to the active hydrogen groups of the active hydrogen compound containing hydrophilic groups is, for example, greater than 1.0, preferably 1.2 or more, more preferably 2.0 or more, and even more preferably 3.0 or more. The upper limit of the isocyanate group equivalence ratio (isocyanate group / active hydrogen group) of the polyisocyanate compound is not particularly limited, for example, it is 50 or less, preferably 20 or less.

[0057] For example, based on mass, the proportion of active hydrogen compound containing hydrophilic groups is, for example, 1 to 30 parts by mass, preferably 5 to 20 parts by mass, relative to 100 parts by mass of the polyisocyanate compound.

[0058] There are no particular restrictions on the reaction conditions, which can be appropriately set according to the purpose and application. For example, the reaction temperature is 20~200℃, preferably 40~100℃. The reaction time is 1~24 hours, preferably 3~12 hours.

[0059] Through the above reaction, as the reaction product of a polyisocyanate compound and an active hydrogen compound containing a hydrophilic group, a polyisocyanate containing a hydrophilic group can be obtained. The polyisocyanate containing the hydrophilic group is suitable for use as a primary polyisocyanate.

[0060] [Terminated isocyanate group] The first polyisocyanate preferably does not have a capped isocyanate group. A capped isocyanate group is an isocyanate group that is blocked by a known capping agent and can be regenerated by the departure of the capping agent. That is, preferably, the isocyanate group of the first polyisocyanate is not blocked by a capping agent. Specifically, as described below, when both the isocyanate groups of the first and second polyisocyanates are not blocked by a capping agent, microcapsules can be efficiently obtained by selecting the first and second polyisocyanates based on their differences in reactivity to active hydrogen compounds.

[0061] [Physical Properties of the First Polyisocyanate] From the viewpoint of storage stability of microcapsules, the average isocyanate base number of the first polyisocyanate is, for example, 2.0 to 6.0, preferably 2.5 to 4.0, and more preferably 3.0 to 3.5.

[0062] More specifically, from the viewpoint of the storage stability of the microcapsules, the lower limit of the average isocyanate content of the first polyisocyanate is, for example, 2.0 or more, preferably 2.5 or more, and more preferably 3.0 or more. Furthermore, more specifically, from the viewpoint of the storage stability of the microcapsules, the upper limit of the average isocyanate content of the first polyisocyanate is, for example, 6.0 or less, preferably 4.0 or less, and more preferably 3.5 or less.

[0063] It should be noted that the average number of isocyanate groups can be calculated from the number average molecular weight and the isocyanate group content according to the following formula.

[0064] Average number of isocyanate groups = Number average molecular weight × Isocyanate group content (converted to solid component, mass%) / 4200 The isocyanate group content of the first polyisocyanate (based on solid components) is, for example, 5 to 30% by mass, preferably 10 to 20% by mass. It should be noted that the isocyanate group content is determined using a potentiometric titrator according to the di-n-butylamine method specified in JIS K-1556 (2006).

[0065] The number-average molecular weight of the first polyisocyanate is, for example, 500 to 1500, preferably 600 to 1200. It should be noted that the number-average molecular weight is the molecular weight converted to polyethylene oxide based on gel permeation chromatography (GPC). The conditions for determining the number-average molecular weight can be followed according to the examples described later.

[0066] The first polyisocyanate can also be dissolved and / or dispersed in organic solvents. That is, solutions and / or dispersions of the first polyisocyanate can also be used. Examples of organic solvents include hydrophobic solvents described later.

[0067] In the solution and / or dispersion of the first polyisocyanate, the concentration of the solid component is, for example, 20 to 90% by mass, preferably 40 to 85% by mass, and more preferably 60 to 80% by mass.

[0068] [Active hydrogen compounds] An active hydrogen compound is an organic compound having two or more active hydrogen groups in one molecule. Examples of active hydrogen groups include hydroxyl and amino groups. Examples of active hydrogen compounds include active hydrogen compounds other than those containing hydrophilic groups (i.e., active hydrogen compounds that do not have the aforementioned nonionic and ionic groups). More specifically, examples of active hydrogen compounds include compounds containing hydroxyl groups, compounds containing amino groups, and compounds containing both hydroxyl and amino groups.

[0069] A hydroxyl-containing compound is an organic compound that has two or more hydroxyl groups in one molecule and no amino group. Examples of hydroxyl-containing compounds include polyols, and more specifically, low molecular weight polyols and high molecular weight polyols.

[0070] Low molecular weight polyols are organic compounds having two or more hydroxyl groups in one molecule and a relatively low molecular weight. The molecular weight of low molecular weight polyols is, for example, 40 or more and less than 400, preferably 300 or less. Examples of low molecular weight polyols include diols, triols, and alcohols with four or more hydroxyl groups. Examples of diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentanediol, diethylene glycol, triethylene glycol, and dipropylene glycol. Examples of triols include glycerol and trimethylolpropane. Examples of alcohols with four or more hydroxyl groups include pentaerythritol and diglycerol.

[0071] In addition, low molecular weight polyols include polymers obtained by addition polymerization of di- to tetrahydric alcohols with epoxides (C2-3) in a manner with a number average molecular weight of less than 400. These can be used alone or in combination of two or more.

[0072] High molecular weight polyols are organic compounds with two or more hydroxyl groups and a high molecular weight. The number-average molecular weight of high molecular weight polyols is, for example, 400 or more, preferably 500 or more, and for example, 20,000 or less. It should be noted that the number-average molecular weight can be calculated using known methods based on the hydroxyl equivalent and the average number of hydroxyl groups. Furthermore, the number-average molecular weight can be determined using gel permeation chromatography in the form of molecular weight converted to polystyrene (the same applies below).

[0073] Examples of high molecular weight polyols include polyether polyols, polyester polyols, polycarbonate polyols, polyurethane polyols, epoxy polyols, vegetable oil polyols, polyolefin polyols, acrylic polyols, and vinyl monomer-modified polyols. They can be used alone or in combination of two or more.

[0074] Amino-containing compounds are organic compounds having two or more amino groups in one molecule and lacking a hydroxyl group. Examples of amino-containing compounds include polyamines, and more specifically, aromatic polyamines, aromatic aliphatic polyamines, alicyclic polyamines, aliphatic polyamines, and polyoxyethylene polyamines. Examples of aromatic polyamines include 4,4'-diphenylmethanediamine and toluenediamine. Examples of aromatic aliphatic polyamines include m-phenylenediamine (m-XDA) and p-phenylenediamine (p-XDA). Examples of alicyclic polyamines include 3-aminomethyl-3,5,5-trimethylcyclohexylamine (also known as isophorone diamine, IPDA), 4,4'-dicyclohexylmethane diamine, 2,5-bis(aminomethyl)bicyclo[2.2.1]heptane, 2,6-bis(aminomethyl)bicyclo[2.2.1]heptane, 1,4-cyclohexane diamine, 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, bis-(4-aminocyclohexyl)methane, diaminocyclohexane, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, 1,3-bis(aminomethyl)cyclohexane (1,3-H6XDA), and 1,4-bis(aminomethyl)cyclohexane (1,4-H6XDA). Examples of aliphatic polyamines include ethylenediamine (EDA), 1,2-propanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, hydrazine, hydrazine hydrate (HYD hydrate), diethylenetriamine (DETA), triethylenetetramine, tetraethylenepentamine, 1,2-diaminoethane, 1,2-diaminopropane, and 1,3-diaminopentane. Examples of polyoxyalkylene-containing polyamines include polyoxyalkylene ether diamines. Examples of polyoxyethylene ether diamines include polyoxyethylene ether diamines. These can be used alone or in combination of two or more.

[0075] Compounds possessing both hydroxyl and amino groups are organic compounds having one or more hydroxyl and one or more amino groups in one molecule. Examples of compounds possessing both hydroxyl and amino groups include amino alcohols. Examples of amino alcohols include 2-((2-aminoethyl)amino)ethanol (AEA) and 2-((2-aminoethyl)amino)-1-methylpropanol. 2-((2-aminoethyl)amino)ethanol (AEA) is preferred. They can be used alone or in combination of two or more.

[0076] They can be used alone or in combination of two or more. As active hydrogen compounds, amino-containing compounds are preferred, aliphatic polyamines are more preferred, and diethylenetriamine (DETA) is even more preferred. That is, the active hydrogen compound preferably contains an amino-containing compound, more preferably an aliphatic polyamine, even more preferably diethylenetriamine, and particularly preferably formed from diethylenetriamine.

[0077] [Manufacturing method of urethane-urea resin] The urethane-urea resin can be obtained by reacting the above-mentioned first polyisocyanate with the above-mentioned active hydrogen compound in a prescribed ratio. From the viewpoint of efficiently obtaining microcapsules, the urethane-urea resin is preferably obtained by interfacial polymerization. It should be noted that the details of the method for obtaining the urethane-urea resin are described below.

[0078] (2) Core layer The core layer is the core material encapsulated (included) within the aforementioned shell layer. The core layer contains a second polyisocyanate (nuclear polyisocyanate). The core layer is preferably formed from the second polyisocyanate.

[0079] [Second polyisocyanate] Examples of second polyisocyanates include the polyisocyanate compounds described above. More specifically, examples of second polyisocyanates include the aromatic polyisocyanates, aromatic aliphatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates described above.

[0080] Polyisocyanate compounds can be used alone or in combination of two or more. Derivatives are preferred examples of polyisocyanate compounds.

[0081] That is, the polyisocyanate compounds in the second polyisocyanate are preferably aromatic polyisocyanate derivatives, aromatic aliphatic polyisocyanate derivatives, aliphatic polyisocyanate derivatives and alicyclic polyisocyanate derivatives.

[0082] As derivatives, isocyanurate-modified products and polyol-modified products (adducts) are preferred examples, and isocyanurate-modified products are more preferred examples.

[0083] In other words, the second polyisocyanate preferably has an isocyanurate backbone and / or a carbamate backbone, and more preferably has an isocyanurate backbone.

[0084] It should be noted that the types of polyisocyanates in the second polyisocyanate (nuclear polyisocyanate) are selected based on the types of polyisocyanates in the first polyisocyanate (shell polyisocyanate) mentioned above, as detailed below. Details regarding the selection of polyisocyanate compounds are described below.

[0085] [Hydrophilic group] The second polyisocyanate preferably does not have hydrophilic groups. If the second polyisocyanate does not have hydrophilic groups, microcapsules can be obtained more efficiently through interfacial polymerization as described later. More preferably, the first polyisocyanate has hydrophilic groups and the second polyisocyanate does not have hydrophilic groups. If the first polyisocyanate has hydrophilic groups and the second polyisocyanate does not have hydrophilic groups, microcapsules can be obtained particularly efficiently.

[0086] In other words, from the viewpoint of microcapsule productivity, a polyisocyanate that does not contain hydrophilic groups is preferred as the second polyisocyanate. The polyisocyanate without hydrophilic groups is the aforementioned polyisocyanate compound.

[0087] [Terminated isocyanate group] The second polyisocyanate preferably does not have a capped isocyanate group. That is, the isocyanate group of the second polyisocyanate is preferably not blocked by a capping agent. As described above, when the isocyanate group of both the first and second polyisocyanates is not blocked by a capping agent, microcapsules can be obtained efficiently by selecting the first and second polyisocyanates based on their differences in reactivity with active hydrogen compounds. Furthermore, when the isocyanate group of the second capped isocyanate is not blocked by a capping agent, the microcapsules can be suitable for use as a curing agent for resin compositions.

[0088] [Physical Properties of the Second Polyisocyanate] From the viewpoint of storage stability of microcapsules, the average isocyanate base number of the second polyisocyanate is, for example, 2.0 to 6.0, preferably 2.5 to 4.0, and more preferably 3.0 to 3.5.

[0089] More specifically, from the viewpoint of the storage stability of the microcapsules, the lower limit of the average isocyanate content of the second polyisocyanate is, for example, 2.0 or more, preferably 2.5 or more, and more preferably 3.0 or more. Furthermore, more specifically, from the viewpoint of the storage stability of the microcapsules, the upper limit of the average isocyanate content of the second polyisocyanate is, for example, 6.0 or less, preferably 4.0 or less, and more preferably 3.5 or less.

[0090] It should be noted that the average number of isocyanate groups can be calculated from the number average molecular weight and the isocyanate group content according to the following formula.

[0091] Average number of isocyanate groups = Number average molecular weight × Isocyanate group content (converted to solid component, mass%) / 4200 The isocyanate group content (based on solid components) of the second polyisocyanate is, for example, 5 to 30% by mass, preferably 10 to 20% by mass. It should be noted that the isocyanate group content is determined using a potentiometric titrator according to the di-n-butylamine method specified in JIS K-1556 (2006).

[0092] The number-average molecular weight of the second polyisocyanate is, for example, 400 to 1000, preferably 500 to 800. It should be noted that the number-average molecular weight is the molecular weight converted to polyethylene oxide based on gel permeation chromatography (GPC). The determination conditions for the number-average molecular weight can be followed according to the examples described later.

[0093] The second polyisocyanate can also be dissolved and / or dispersed in organic solvents. That is, solutions and / or dispersions of the second polyisocyanate can also be used. Examples of organic solvents include hydrophobic solvents described later.

[0094] In the solution and / or dispersion of the second polyisocyanate, the concentration of the solid component is, for example, 20 to 90% by mass, preferably 40 to 85% by mass, and more preferably 60 to 80% by mass.

[0095] (3) Core-shell structure Microcapsules have a core-shell structure. That is, microcapsules are core-shell particles.

[0096] The core-shell structure can be formed, for example, by selecting a first polyisocyanate and a second polyisocyanate and interfacially polymerizing the first polyisocyanate with an active hydrogen compound in a manner that includes the second polyisocyanate (described later).

[0097] Furthermore, in order to obtain microcapsules with excellent isocyanate group content and storage stability, the first polyisocyanate (shell isocyanate) and the second polyisocyanate (nucleus isocyanate) were selected based on their differences in reactivity with active hydrogen compounds.

[0098] More specifically, the first polyisocyanate and the second polyisocyanate are each selected in such a way that the first polyisocyanate is more reactive with active hydrogen compounds than the second polyisocyanate is reactive with active hydrogen compounds.

[0099] Hereinafter, reactivity refers to the ease with which the isocyanate group reacts with an active hydrogen group. Reactivity is classified according to the type of polyisocyanate compound.

[0100] More specifically, the reactivity of polyisocyanate compounds follows the order of the following formulas.

[0101] Aromatic polyisocyanates, aromatic aliphatic polyisocyanates > aliphatic polyisocyanates > alicyclic polyisocyanates without secondary isocyanate groups > alicyclic polyisocyanates containing secondary isocyanate groups In other words, the type of modifier and the presence or absence of hydrophilic groups in polyisocyanate compounds have little effect on reactivity. Reactivity is mainly determined by the presence or absence of aromatic groups, aromatic aliphatic groups, and alicyclic groups, as well as the order of the isocyanate group.

[0102] More specifically, among the aforementioned polyisocyanate compounds, aromatic polyisocyanates and aromatic aliphatic polyisocyanates exhibit higher reactivity compared to other polyisocyanate compounds (aliphatic polyisocyanates, alicyclic polyisocyanates without secondary isocyanate groups, and alicyclic polyisocyanates containing secondary isocyanate groups).

[0103] That is, aromatic polyisocyanates and aromatic aliphatic polyisocyanates react with active hydrogen compounds at a faster rate than other polyisocyanate compounds (aliphatic polyisocyanates, alicyclic polyisocyanates without secondary isocyanate groups, and alicyclic polyisocyanates with secondary isocyanate groups) react with active hydrogen compounds.

[0104] Therefore, for example, when using at least one of the group consisting of aliphatic polyisocyanates, alicyclic polyisocyanates without secondary isocyanate groups, and alicyclic polyisocyanates containing secondary isocyanate groups as the second polyisocyanate (core polyisocyanate, core material), a polyisocyanate compound with higher reactivity (i.e., aromatic polyisocyanates and / or aromatic aliphatic polyisocyanates) and / or a polyisocyanate containing hydrophilic groups as the first polyisocyanate (shell polyisocyanate).

[0105] In addition, aliphatic polyisocyanates have higher reactivity compared to alicyclic polyisocyanates without secondary isocyanate groups and alicyclic polyisocyanates containing secondary isocyanate groups.

[0106] That is, aromatic polyisocyanates, aromatic aliphatic polyisocyanates, and aliphatic polyisocyanates react with active hydrogen compounds at a faster rate than other polyisocyanate compounds (alicyclic polyisocyanates without secondary isocyanate groups and alicyclic polyisocyanates with secondary isocyanate groups) react with active hydrogen compounds.

[0107] Therefore, for example, when using an alicyclic polyisocyanate without a secondary isocyanate group and / or an alicyclic polyisocyanate containing a secondary isocyanate group as the second polyisocyanate (core polyisocyanate, core material), a polyisocyanate compound with higher reactivity (i.e., at least one selected from the group consisting of aromatic polyisocyanates, aromatic aliphatic polyisocyanates and aliphatic polyisocyanates) and / or a polyisocyanate containing a hydrophilic group is used as the first polyisocyanate (shell polyisocyanate).

[0108] In addition, alicyclic polyisocyanates without secondary isocyanate groups have higher reactivity compared to alicyclic polyisocyanates containing secondary isocyanate groups.

[0109] That is, aromatic polyisocyanates, aromatic aliphatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates without secondary isocyanate groups react with active hydrogen compounds at a higher rate than alicyclic polyisocyanates containing secondary isocyanate groups react with active hydrogen compounds.

[0110] Therefore, for example, when an alicyclic polyisocyanate containing a secondary isocyanate group is selected as the second polyisocyanate (core polyisocyanate, core material), a polyisocyanate compound with higher reactivity (i.e., at least one selected from the group consisting of aromatic polyisocyanates, aromatic aliphatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates without a secondary isocyanate group) and / or a polyisocyanate containing a hydrophilic group is used as the first polyisocyanate (shell polyisocyanate).

[0111] As described above, the polyisocyanate compound selected as the first polyisocyanate (shell polyisocyanate) has a higher reactivity than the second polyisocyanate (nuclear polyisocyanate).

[0112] If polyisocyanate compounds are selected in this way, the first polyisocyanate (shell polyisocyanate) is more reactive than the second polyisocyanate (nuclear polyisocyanate).

[0113] Furthermore, a first polyisocyanate with high reactivity forms the shell, and a second polyisocyanate with low reactivity is encapsulated (included) within the shell to serve as the core layer. This allows for the efficient manufacture of microcapsules with a core-shell structure. Additionally, the resulting microcapsules exhibit excellent storage stability.

[0114] 2. Methods for manufacturing microcapsules As a method for manufacturing the aforementioned microcapsules, interfacial polymerization is preferred. The method for manufacturing the aforementioned microcapsules will be described in detail below.

[0115] (1) Preparation process In this method, for example, a mixture of isocyanates containing a first polyisocyanate and a second polyisocyanate is first prepared.

[0116] More specifically, in this method, a first polyisocyanate and a second polyisocyanate are selected based on the reactivity described above. Then, the first polyisocyanate and the second polyisocyanate are mixed to obtain an isocyanate mixture.

[0117] The mixing ratio of the first polyisocyanate and the second polyisocyanate can be appropriately selected based on the purpose and application. For example, relative to 100 parts by weight of the second polyisocyanate (nuclear polyisocyanate), the first polyisocyanate (shell polyisocyanate) is, for example, 50 to 1000 parts by weight, preferably 100 to 500 parts by weight.

[0118] (2) Reaction process Next, in the method, the isocyanate mixture is mixed with an active hydrogen compound in the presence of a hydrophobic solvent with a ClogP value of 2.0 to 5.0, and the first polyisocyanate and the active hydrogen compound are interfacially polymerized in such a way that a second polyisocyanate is contained, to form a shell and a core layer encapsulated in the shell.

[0119] More specifically, in this method, for example, the above-mentioned isocyanate mixture is mixed with a hydrophobic solvent with a ClogP value of 2.0 to 5.0. That is, a mixture containing the isocyanate mixture and the hydrophobic solvent is obtained (hereinafter referred to as the isocyanate mixture).

[0120] Hydrophobic solvents are defined as solvents with a ClogP value of 2.0 or higher. It should be noted that the ClogP value is the logarithm of the n-octanol / water partition coefficient (P), a parameter indicating the degree of hydrophobicity or hydrophilicity. The ClogP value is calculated based on the chemical structural formula using ChemDraw (Perkin Elmer, ver. 22.2.0).

[0121] From the viewpoint of microcapsule productivity, the hydrophobic solvent contains a hydrophobic solvent with a ClogP value of 2.0 to 5.0. Examples of hydrophobic solvents with a ClogP value of 2.0 to 5.0 include toluene (ClogP value 2.6), xylene (ClogP value 3.1), trimethylbenzene (ClogP value 3.6), hexane (ClogP value 3.9), and methylcyclohexane (ClogP value 3.9). These can be used alone or in combination of two or more. Preferably, a hydrophobic solvent with a ClogP value of 2.5 to 4.0 is used; more preferably, a hydrophobic solvent with a ClogP value of 3.0 to 4.0 is used; and even more preferably, a hydrophobic solvent with a ClogP value of 3.0 to 3.5 is used.

[0122] More specifically, the lower limit of the ClogP value of the hydrophobic solvent is, for example, 5.0 or less, preferably 4.0 or less, and more preferably 3.5 or less. If the ClogP value of the hydrophobic solvent is below the upper limit mentioned above, the aggregation of the oil phase can be suppressed, and the O / W emulsion described later (described later) can be obtained efficiently, and microcapsules can be obtained with good productivity.

[0123] Furthermore, the upper limit of the ClogP value of the hydrophobic solvent is, for example, 2.0 or more, preferably 2.5 or more, and more preferably 3.0 or more. If the ClogP value of the hydrophobic solvent is above the aforementioned lower limit, the miscibility between the aqueous phase and the oil phase can be suppressed, and the O / W emulsion described later (described later) can be obtained efficiently, and microcapsules can be obtained with good productivity.

[0124] Xylene, trimethylbenzene, hexane and methylcyclohexane are preferred hydrophobic solvents, with xylene being a more preferred solvent.

[0125] There are no particular limitations on the mixing ratio of the isocyanate mixture and the hydrophobic solvent, which can be set according to the purpose and application. For example, relative to 100 parts by mass of the total solid components of the first polyisocyanate and the second polyisocyanate, the hydrophobic solvent is, for example, 50 to 500 parts by mass, preferably 100 to 200 parts by mass.

[0126] In addition, in this method, an aqueous solution containing an emulsifier (hereinafter referred to as an emulsifier aqueous solution) is prepared separately from the above isocyanate mixture.

[0127] Examples of emulsifiers include known surfactants, and more specifically, anionic emulsifiers, cationic emulsifiers, nonionic emulsifiers, and amphoteric emulsifiers. Anionic emulsifiers are preferred. Examples of anionic emulsifiers include alkylbenzene sulfonate metal salts (e.g., dodecylbenzene sulfonate metal salt), alkyl diphenyl ether sulfonate metal salts, alkyl naphthalene sulfonate metal salts, dialkyl sulfosuccinate metal salts, polyoxyethylene styrene ether ammonium sulfate, polyoxyethylene styrene ether ammonium sulfate, lignin sulfonate metal salts, and lignin sulfonate metal salts. Examples of metal salts include sodium salts, potassium salts, and magnesium salts. They can be used alone or in combination of two or more.

[0128] There are no particular limitations on the method for preparing the emulsifier aqueous solution. For example, the emulsifier can be added to water to dissolve it. The amount of emulsifier added can be appropriately set according to the purpose and use. For example, the amount (total) of emulsifier added is, for example, 0.1 to 20 parts by mass relative to 100 parts by mass of water, preferably 1 to 10 parts by mass.

[0129] An aqueous emulsion may contain additives in addition to the emulsifier. Examples of additives include dispersants and defoamers.

[0130] Examples of dispersing agents include protective colloids, and more specifically, polyvinyl alcohol, cellulose, gelatin and dextrin.

[0131] They can be used alone or in combination of two or more. Polyvinyl alcohol is preferred as a dispersing agent. There are no particular restrictions on the amount and timing of addition of the dispersing agent, which can be appropriately set according to the purpose and application.

[0132] Examples of defoamers include silicone-based and fluorinated defoamers. They can be used alone or in combination of two or more. Silicone-based defoamers are preferred as dispersing agents. There are no particular restrictions on the amount and timing of defoamer addition; they can be appropriately set according to the purpose and application.

[0133] Emulsifier aqueous solutions may also contain other additives (additives other than dispersants and defoamers). Examples of other additives include pH adjusters, pH buffers, antifreeze agents, heat stabilizers, light stabilizers, and antioxidants. They can be used alone or in combination of two or more. There are no particular restrictions on the amount or timing of addition of other additives; they can be appropriately determined according to the purpose and application.

[0134] Next, in this method, the above-mentioned isocyanate mixture (i.e., a mixture containing an isocyanate mixture and a hydrophobic solvent) is added to an aqueous emulsifier solution to prepare an O / W emulsion.

[0135] More specifically, an isocyanate mixture (oil phase) is added dropwise and mixed into an aqueous emulsion (aqueous phase), dispersing the isocyanate particles (oil droplets) in the water. This prepares an O / W emulsion (oil-in-water emulsion).

[0136] There are no particular limitations on the amount and rate of addition of the isocyanate mixture to the emulsifier aqueous solution; they can be appropriately set within the range that allows for the preparation of O / W emulsions.

[0137] For example, relative to 100 parts by mass of water in the emulsifier aqueous solution, the amount of isocyanate mixture (the total amount of the first isocyanate, the second isocyanate, and the hydrophobic solvent) is, for example, 0.1 to 100 parts by mass, preferably 1 to 50 parts by mass, and more preferably 5 to 30 parts by mass. Furthermore, the dripping time is, for example, 1 to 10 hours, preferably 1 to 5 hours. Additionally, the mixing time is, for example, 1 to 10 hours, preferably 3 to 8 hours.

[0138] Next, in this method, an active hydrogen compound is added to the above O / W emulsion, and the first polyisocyanate and the active hydrogen compound undergo interfacial polymerization at the surface of the particles (oil droplets) of the isocyanate mixture (i.e., the water-oil interface).

[0139] More specifically, in this method, an aqueous solution containing active hydrogen compounds (hereinafter referred to as the aqueous solution of active hydrogen compounds) is prepared separately from the above O / W emulsion.

[0140] There are no particular limitations on the method for preparing an aqueous solution of an active hydrogen compound. For example, the active hydrogen compound is added to and mixed in water to dissolve it. The amount of active hydrogen compound added can be appropriately set according to the purpose and use. For example, the amount (total) of active hydrogen compound added is, for example, 0.1 to 20 parts by mass relative to 100 parts by mass of water, preferably 1 to 10 parts by mass.

[0141] Next, in this method, an aqueous solution of an active hydrogen compound is added to the above O / W emulsion, and they are mixed.

[0142] The amount of active hydrogen compound added in the aqueous solution can be adjusted based on, for example, the ratio of isocyanate groups of the first polyisocyanate contained in the O / W emulsion to the active hydrogen groups of the active hydrogen compound contained in the aqueous solution.

[0143] More specifically, the lower limit of the equivalence ratio (active hydrogen group / isocyanate group) of the active hydrogen compound to the isocyanate group of the first polyisocyanate is, for example, greater than 1.0, preferably 1.2 or more, more preferably 2.0 or more, and even more preferably 3.0 or more. It should be noted that the upper limit of the equivalence ratio (active hydrogen group / isocyanate group) of the active hydrogen compound to the isocyanate group of the first polyisocyanate is not particularly limited, for example, it is 50 or less, preferably 20 or less.

[0144] Therefore, by mixing the O / W emulsion with the aqueous solution of the active hydrogen compound, the isocyanate mixture in the O / W emulsion is mixed with the active hydrogen compound in the aqueous solution of the active hydrogen compound.

[0145] Then, at the surface of the oil droplets in the O / W emulsion (oil / water interface), the first polyisocyanate in the isocyanate mixture reacts with an active hydrogen compound (carbamate ureation reaction).

[0146] More specifically, the isocyanate mixture contains both a first polyisocyanate and a second polyisocyanate. Therefore, if the isocyanate mixture is mixed with an active hydrogen compound, both the first and second polyisocyanates can react with the active hydrogen compound.

[0147] On the other hand, the first and second polyisocyanates can be selected based on the aforementioned differences in reactivity. That is, the first polyisocyanate is more reactive with active hydrogen compounds than the second polyisocyanate.

[0148] Therefore, when the isocyanate mixture is mixed with the active hydrogen compound, the reaction of the first polyisocyanate with the active hydrogen compound proceeds more rapidly than the reaction of the second polyisocyanate with the active hydrogen compound.

[0149] As a result, a carbamate-urea resin, which is the reaction product of the first polyisocyanate and the active hydrogen compound, forms a shell on the surface of the O / W emulsion droplets. Additionally, a second polyisocyanate is contained within the shell in an unreacted state.

[0150] That is, a core layer containing a second polyisocyanate is encapsulated in a shell layer containing urethane urea resin, forming a core-shell structure.

[0151] As described above, by mixing the isocyanate mixture with an active hydrogen compound, the first polyisocyanate and the active hydrogen compound are interfacially polymerized in a manner that incorporates a second polyisocyanate. Furthermore, a shell layer containing a urethane urea resin is formed, and a core layer containing the second polyisocyanate is simultaneously formed and encapsulated (included) within the shell layer.

[0152] As a result, microcapsules with a core-shell structure can be obtained with good productivity. Furthermore, due to the aforementioned difference in reactivity, the shell containing urethane-urea resin can more firmly encapsulate the second polyisocyanate. Therefore, the aforementioned microcapsules exhibit excellent isocyanate group content and storage stability.

[0153] 3. Effects In the aforementioned microcapsules, the first and second polyisocyanates are selected based on their differences in reactivity with active hydrogen compounds. More specifically, the more reactive first polyisocyanate forms a shell containing a urethane urea resin. Furthermore, the less reactive second polyisocyanate is encapsulated (contained) within the shell as a core layer. Therefore, compared to cases where, for example, the first and second polyisocyanates are of the same type, the aforementioned microcapsules exhibit superior isocyanate group content and storage stability.

[0154] Furthermore, the microcapsules described above can be obtained efficiently using the aforementioned microcapsule manufacturing method.

[0155] Example Next, the present invention will be described based on embodiments and comparative examples, but the present invention is not limited to the following embodiments. It should be noted that unless otherwise specified, "part" and "%" are based on mass. In addition, the specific numerical values ​​of mixing ratios (including ratios), physical property values, parameters, etc. used in the following description can be replaced with the corresponding upper limit values ​​(values ​​defined in the form of "less than" or "less than") or lower limit values ​​(values ​​defined in the form of "above" or "greater than") of the mixing ratios (including ratios), physical property values, parameters, etc., described in the "Specific Embodiments" above.

[0156] 1. First polyisocyanate Synthesis Example 1: Polyisocyanate A1 (MePEG modified from XDI isocyanurate) (1) Polyisocyanate compounds (polyisocyanate P1) In a reactor equipped with a thermometer, stirrer, nitrogen inlet pipe, and condenser, 100 parts by mass of 1,3-phenylene dimethyl ether diisocyanate (m-XDI, manufactured by Mitsui Chemicals), 0.025 parts by mass of an antioxidant (2,6-di(tert-butyl)-4-methylphenol, BHT, hindered phenolic antioxidant), and 0.05 parts by mass of a co-catalyst (tetraphenyl dipropylene glycol diphosphite, organic phosphite, trade name: JPP-100, manufactured by Johoku Chemical Industry Co., Ltd.) were added to the reactor under a nitrogen atmosphere. Next, 1.96 parts by mass of 1,3-butanediol were added to the reactor. The 1,3-phenylene dimethyl ether diisocyanate and 1,3-butanediol were then subjected to a carbamate reaction at 80°C for 2 hours to obtain a carbamate reaction product. The isocyanate group content of the reaction product was 44.7% by mass. It should be noted that the isocyanate group content was determined using a potentiometric titrator according to the di-n-butylamine method specified in JIS K-1556 (2006).

[0157] Next, a 37% by mass solution of tetrabutylammonium hydroxide (TBAOH) was added to the carbamate reaction product as an isocyanurate esterification catalyst. It should be noted that the amount of solid tetrabutylammonium hydroxide (TBAOH) added was 0.015 parts by mass.

[0158] Next, the carbamate reaction product containing the isocyanurate esterification catalyst was heated to obtain an isocyanurate esterification reaction product containing phenylene diisocyanate (hereinafter referred to as XDI isocyanurate). It should be noted that the initial reaction temperature was 60°C and the highest temperature reached was 70°C.

[0159] Then, the isocyanurate esterification reaction product is passed into a thin-film distillation apparatus (temperature 150℃, vacuum degree 50Pa) to remove unreacted phenylene diisocyanate and purify XDI isocyanurate.

[0160] Next, XDI isocyanurate was diluted with xylene to obtain a xylene solution of XDI isocyanurate (hereinafter referred to as polyisocyanate P1).

[0161] The solid component concentration of polyisocyanate P1 is 75% by mass, and the isocyanate group content (based on solid component) is 14.0% by mass.

[0162] (2) MePEG modified product (polyisocyanate A1) 1000 parts by mass of polyisocyanate P1 and 132.4 parts by mass of MePEG400 (polyoxyethylene methyl ether with a number average molecular weight of 400) were added to a 2L reactor equipped with a stirrer, thermometer, condenser, and nitrogen inlet pipe at room temperature (25°C). Then, 44.1 parts by mass of xylene (solvent) were added to the reactor, and the XDI isocyanurate and MePEG400 were subjected to a carbamate reaction at 80°C for 6 hours to obtain a MePEG-modified XDI isocyanurate. A xylene solution of the MePEG-modified XDI isocyanurate was also obtained (hereinafter referred to as polyisocyanate A1). It should be noted that the equivalent ratio (NCO / OH) of the isocyanate groups of polyisocyanate P1 to the hydroxyl groups of MePEG400 is 10.1.

[0163] The solid component concentration of polyisocyanate A1 is 75% by mass, and the MePEG modified XDI isocyanurate has an isocyanurate backbone.

[0164] The isocyanate group content (xylene solution basis) of polyisocyanate A1 is 11.1% by mass. In addition, the solid component conversion value of the isocyanate group content is 14.8% by mass.

[0165] In addition, the number-average molecular weight of the MePEG-modified XDI isocyanurate was determined by gel permeation chromatography (GPC) under the following conditions. The number-average molecular weight was 840.

[0166] Instrument used: HLC-8020 (manufactured by TOSOH) Using columns: Connect G1000HXL, G2000HXL, and G3000HXL (these are trade names manufactured by TOSOH) in series. Sample concentration: 0.3% by mass, THF solution Sample injection volume: 100 μL Eluent: Tetrahydrofuran Flow rate of eluent: 0.8 ml / min Column temperature: 40℃ Test method: Differential refractive index Standard substance: Polyethylene oxide (manufactured by TOSOH, trade name: TSK Polyethylene Oxide Standard) The average isocyanate base number (based on solid content) was calculated using the following formula. The average isocyanate base number (based on solid content) of the MePEG modified XDI isocyanurate was 3.0.

[0167] Average number of isocyanate groups = Number average molecular weight × Isocyanate group content (converted to solid component, mass%) / 4200 Synthesis Example 2: Polyisocyanate A2 (MePEG modified from TDI adduct) (1) Polyisocyanate compounds (polyisocyanate P2) TAKENATE D-103 (trade name, trimethylolpropane (TMP) adduct of toluene diisocyanate (TDI), solid content 75% by mass, solvent: ethyl acetate, manufactured by Mitsui Chemicals) was subjected to reduced pressure treatment at 50°C and 50 Pa to remove ethyl acetate.

[0168] Thus, the trimethylolpropane adduct of toluene diisocyanate (hereinafter referred to as the TDI adduct) was obtained. The TDI adduct was diluted with xylene to obtain a xylene solution of the TDI adduct (hereinafter referred to as polyisocyanate P2).

[0169] The solid component concentration of polyisocyanate P2 is 75% by mass, and the isocyanate group content (xylene solution basis) is 13.0% by mass.

[0170] (2) MePEG modified product (polyisocyanate A2) Following the method described in Synthesis Example 1, 1000 parts by mass of polyisocyanate P2, 132.4 parts by mass of MePEG400, and 44.1 parts by mass of xylene were mixed to obtain a MePEG-modified TDI adduct. Additionally, a xylene solution of the MePEG-modified TDI adduct was obtained (hereinafter referred to as polyisocyanate A2).

[0171] The solid component concentration of polyisocyanate A2 is 75% by mass, and the MePEG modified TDI adduct has a carbamate backbone.

[0172] The isocyanate group content (xylene solution basis) of polyisocyanate A2 is 10.3% by mass. In addition, the solid component conversion value of isocyanate group content is 13.7% by mass.

[0173] In addition, the number-average molecular weight of the MePEG-modified TDI adduct was determined by gel permeation chromatography (GPC) under the above conditions. The number-average molecular weight was 937.

[0174] The average isocyanate base number (based on solid components) was calculated using the above formula. The average isocyanate base number (based on solid components) of the MePEG-modified TDI adduct was 3.1.

[0175] Synthesis Example 3: Polyisocyanate A3 (MePEG modified XDI adduct) (1) Polyisocyanate compounds (polyisocyanate P3) TAKENATE D-110N (trade name, trimethylolpropane (TMP) adduct of diphenylene diisocyanate, solid content 75% by mass, solvent: ethyl acetate, manufactured by Mitsui Chemicals) was subjected to reduced pressure treatment at 50°C and 50 Pa to remove ethyl acetate.

[0176] Thus, a trimethylolpropane adduct of phenylene diisocyanate (hereinafter referred to as the XDI adduct) was obtained. The XDI adduct was diluted with xylene to obtain a xylene solution of the XDI adduct (hereinafter referred to as polyisocyanate P3).

[0177] The solid component concentration of polyisocyanate P3 is 75% by mass, and the isocyanate group content (xylene solution basis) is 11.5% by mass.

[0178] (2) MePEG modified product (polyisocyanate A3) Following the method described in Synthesis Example 1, 1000 parts by mass of polyisocyanate P3, 132.4 parts by mass of MePEG400, and 44.1 parts by mass of xylene were mixed to obtain a MePEG-modified XDI adduct. Additionally, a xylene solution of the MePEG-modified XDI adduct was obtained (hereinafter referred to as polyisocyanate A3).

[0179] The solid component concentration of polyisocyanate A3 is 75% by mass, and the MePEG modified XDI adduct has a carbamate backbone.

[0180] The isocyanate group content (xylene solution basis) of polyisocyanate A3 is 8.9% by mass. In addition, the solid component conversion value of isocyanate group content is 11.9% by mass.

[0181] In addition, the number-average molecular weight of the MePEG-modified XDI adduct was determined by gel permeation chromatography (GPC) under the above conditions. The number-average molecular weight was 1083.

[0182] The average isocyanate base number (based on solid components) was calculated using the above formula. The average isocyanate base number (based on solid components) of the MePEG-modified XDI adduct was 3.1.

[0183] Synthesis Example 4: Polyisocyanate A4 (MePEG modified from HDI isocyanurate) (1) Polyisocyanate compounds (polyisocyanate P4) TAKENATE D-170N (trade name, isocyanurate of 1,6-hexamethylene diisocyanate, solid component 100% by mass, manufactured by Mitsui Chemicals) (hereinafter referred to as HDI isocyanurate) was diluted with xylene to obtain a xylene solution of HDI isocyanurate (hereinafter referred to as polyisocyanate P4).

[0184] The solid component concentration of polyisocyanate P4 is 75% by mass, and the isocyanate group content (xylene solution basis) is 15.5% by mass.

[0185] (2) MePEG modified product (polyisocyanate A4) Following the method described in Synthesis Example 1, 1000 parts by mass of polyisocyanate P4, 132.4 parts by mass of MePEG400, and 44.1 parts by mass of xylene were mixed to obtain a MePEG-modified HDI isocyanurate. Additionally, a xylene solution of the MePEG-modified HDI isocyanurate (hereinafter referred to as polyisocyanate A4) was obtained.

[0186] The solid component concentration of polyisocyanate A4 is 75% by mass, and the MePEG modified HDI isocyanurate has an isocyanurate backbone.

[0187] The isocyanate group content (xylene solution basis) of polyisocyanate A4 is 12.5% ​​by mass. In addition, the solid component conversion value of the isocyanate group content is 16.7% by mass.

[0188] In addition, the number-average molecular weight of the MePEG-modified HDI isocyanurate was determined by gel permeation chromatography (GPC) under the above conditions. The number-average molecular weight was 884.

[0189] The average isocyanate base number (based on solid components) was calculated using the above formula. The average isocyanate base number (based on solid components) of the MePEG modified HDI isocyanurate is 3.5.

[0190] Synthesis Example 5: Polyisocyanate A5 (MePEG modified from HDI urea carbamate) (1) Polyisocyanate compounds (polyisocyanate P5) A xylene solution of HDI urea carbamate (hereinafter referred to as polyisocyanate P5) was prepared by diluting TAKENATE D-178NL (urea carbamate of 1,6-hexamethylene diisocyanate, 100% by mass solid content, manufactured by Mitsui Chemicals) with xylene.

[0191] The solid component concentration of polyisocyanate P5 is 75% by mass, and the isocyanate group content (xylene solution basis) is 14.4% by mass.

[0192] (2) MePEG modified product (polyisocyanate A5) Following the method described in Synthesis Example 1, 1000 parts by mass of polyisocyanate P5, 132.4 parts by mass of MePEG400, and 44.1 parts by mass of xylene were mixed to obtain a MePEG-modified HDI urea carbamate. Additionally, a xylene solution of the MePEG-modified HDI urea carbamate (hereinafter referred to as polyisocyanate A5) was obtained.

[0193] The solid component concentration of polyisocyanate A5 is 75% by mass, and the MePEG modified HDI urea carbamate has a urea carbamate backbone.

[0194] The isocyanate group content (xylene solution basis) of polyisocyanate A5 is 11.5% by mass. In addition, the solid component conversion value of the isocyanate group content is 15.3% by mass.

[0195] In addition, the number-average molecular weight of the MePEG-modified HDI urethane was determined by gel permeation chromatography (GPC) under the above conditions. The number-average molecular weight was 555.

[0196] The average isocyanate base number (based on solid content) was calculated using the above formula. The average isocyanate base number (based on solid content) of the MePEG modified HDI urea carbamate was 2.0.

[0197] Synthesis Example 8: Polyisocyanate A8 (TDI adduct) As polyisocyanate A8, TAKENATE D-103 (trade name, trimethylolpropane (TMP) adduct of toluene diisocyanate (TDI), solid content 75% by mass, solvent: ethyl acetate, manufactured by Mitsui Chemicals Co., Ltd.) was used.

[0198] In addition, the number-average molecular weight of the TDI adduct was determined using gel permeation chromatography (GPC) under the above conditions. The number-average molecular weight was 877.

[0199] The average isocyanate base number (based on solid components) was calculated using the above formula. The average isocyanate base number (based on solid components) of the TDI adduct is 3.6.

[0200] 2. Second polyisocyanate Synthesis Example 6: Polyisocyanate compound (polyisocyanate A6) 2000 parts by mass of 1,6-hexamethylene diisocyanate (HDI, manufactured by TOSOH) and 3.2 parts by mass of isobutanol were added to a four-necked flask equipped with a stirrer, thermometer, reflux tube, and nitrogen inlet tube. The mixture was subjected to a carbamate reaction at 80°C for 2 hours to obtain the carbamate reaction product. It should be noted that the isocyanate group equivalence ratio (NCO / OH) of 1,6-hexamethylene diisocyanate to the hydroxyl group of isobutanol is 600.

[0201] Next, DABCO-TMR (N-(2-hydroxypropyl)-N,N,N-trimethylammonium-2-ethylhexanoate, manufactured by Air Products and Chemicals, Inc.) was added as an isocyanurate esterification catalyst to the urethane esterification reaction product. It should be noted that the amount added was 0.52 parts by weight.

[0202] Next, the carbamate reaction product containing the isocyanurate esterification catalyst was heated to obtain an isocyanurate esterification reaction product containing 1,6-hexamethylene diisocyanate (hereinafter referred to as HDI isocyanurate). It should be noted that the reaction temperature was 80~86℃ and the reaction time was 2 hours.

[0203] Furthermore, by measuring the isocyanate group content of the isocyanurate esterification reaction product, it was confirmed that 10% of the isocyanate group content (residual isocyanate groups after urethane esterification) in the carbamate esterification reaction product was converted. The reaction was then terminated by adding 0.60 parts by weight of o-toluenesulfonic acid.

[0204] Then, the isocyanurate esterification reaction product is passed into a thin-film distillation apparatus (temperature 140℃, vacuum degree 50Pa) to remove unreacted 1,6-hexamethylene diisocyanate.

[0205] The resulting reaction solution was distilled using a thin-film distillation apparatus (temperature 140℃, vacuum degree 50Pa) to remove unreacted 1,6-hexamethylene diisocyanate and purify HDI isocyanurate.

[0206] Next, HDI isocyanurate was diluted with xylene to obtain a xylene solution of HDI isocyanurate (hereinafter referred to as polyisocyanate A6).

[0207] The solid component concentration of polyisocyanate A6 is 75% by mass, and the isocyanate group content (xylene solution basis) is 17.0% by mass. In addition, the solid component conversion value of isocyanate group content is 22.7% by mass.

[0208] In addition, the number-average molecular weight of HDI isocyanurate was determined using gel permeation chromatography (GPC) under the above conditions. The number-average molecular weight was 682.

[0209] The average isocyanate base number (based on solid components) was calculated using the above formula. The average isocyanate base number (based on solid components) of HDI isocyanurate is 3.7.

[0210] Synthesis Example 7: Polyisocyanate compound (Polyisocyanate A7) Instead of 1,6-hexamethylene diisocyanate, 1,5-pentanediisocyanate (PDI, manufactured by Mitsui Chemicals) was used. Otherwise, using the same method as in Synthesis Example 6, an isocyanurate esterification reaction product containing 1,5-pentanediisocyanate (hereinafter referred to as PDI isocyanurate) was obtained.

[0211] In addition, PDI isocyanurate was purified using the same method as in Synthesis Example 6, and further diluted with xylene to obtain a xylene solution of PDI isocyanurate (hereinafter referred to as polyisocyanate A7).

[0212] The solid component concentration of polyisocyanate A7 is 75% by mass, and the isocyanate group content (xylene solution basis) is 18.8% by mass. In addition, the solid component conversion value of isocyanate group content is 25.1% by mass.

[0213] In addition, the number-average molecular weight of PDI isocyanurate was determined by gel permeation chromatography (GPC) under the above conditions. The number-average molecular weight was 681.

[0214] The average isocyanate base number (based on solid components) was calculated using the above formula. The average isocyanate base number (based on solid components) of HDI isocyanurate is 4.1.

[0215] 3. Microcapsules Examples 1-9 and Comparative Examples 1-4 According to the formulations shown in Tables 1 to 3, the first polyisocyanate, the second polyisocyanate, and the solvent were added to a flask equipped with a stirrer, thermometer, condenser, and nitrogen inlet tube. The contents of the flask were then stirred at 25°C for 30 minutes to obtain an isocyanate mixture.

[0216] On the other hand, according to the formulations shown in Tables 1 to 3, sodium dodecylbenzenesulfonate (emulsifier, DDBSNa), polyvinyl alcohol (protective colloid, PVA) and defoamer (trade name BYK-028, silicone defoamer, manufactured by BYK) are dissolved in distilled water to obtain an aqueous emulsifier solution.

[0217] Next, the emulsifier aqueous solution was cooled to 10°C and stirred at 4000 rpm using a homogenizer. Then, the above-mentioned isocyanate mixture was slowly added to the stirred emulsifier aqueous solution to obtain an O / W emulsion. The O / W emulsion was stirred for 5 minutes.

[0218] Then, according to the formulations shown in Tables 1-3, an aqueous solution of diethylenetriamine (active hydrogen compound) was added dropwise to the O / W emulsion in small increments over 1 hour, and the mixture was then stirred for 4 hours. This allowed the first polyisocyanate and the active hydrogen compound to undergo interfacial polymerization at the oil / water interface. The result was a dispersion of microcapsules. The microcapsules had a core-shell structure comprising a shell layer formed by the reaction product of the first polyisocyanate and the active hydrogen compound (urethane urea resin), and a core layer formed by the second polyisocyanate.

[0219] Next, the microcapsules were separated from the dispersion by vacuum filtration. Then, the microcapsules were dried at 40°C for 24 hours.

[0220] It should be noted that in Examples 1-9 and Comparative Examples 2-4, the first polyisocyanate was reacted with the active hydrogen compound at 10°C.

[0221] On the other hand, in Comparative Example 1, the first polyisocyanate was reacted with an active hydrogen compound at 60°C.

[0222] 4. Evaluation (1) Initial isocyanate group content The microcapsules and dimethylformamide (solvent) were mixed for 30 minutes to dissolve the second polyisocyanate within the microcapsules into the solvent, thus obtaining the sample. The content of isocyanate groups within the microcapsules (initial isocyanate group content) was determined using the sample. It should be noted that the isocyanate group content was determined using a potentiometric titrator according to the di-n-butylamine method specified in JIS K-1556 (2006).

[0223] (2) Dispersibility and storage stability The microcapsules were dispersed in distilled water using a magnetic stirrer (1000 rpm) to obtain a dispersion of the microcapsules. It should be noted that the concentration of the solid component of the microcapsules in the dispersion was 10% by mass.

[0224] Next, a dispersion was prepared, and after 30 minutes, the dispersion was dried to obtain the non-volatile component. Then, FT-IR (transmission method) was performed on the non-volatile component to determine the absorption peak (2260 cm⁻¹) caused by the stretching vibration of the isocyanate group. -1 (height).

[0225] Dispersibility is evaluated based on the appearance of the microcapsule dispersion. The evaluation criteria are described below.

[0226] In addition, after 7 days of preparation, the dispersion was dried to obtain the non-volatile component. Then, FT-IR analysis was performed on the non-volatile component to determine the absorption peak (2260 cm⁻¹) caused by the stretching vibration of the isocyanate groups. -1 (height).

[0227] Then, the rate of change in the isocyanate group content is calculated using the following formula.

[0228] Change rate of isocyanate group content (%) = Absorption peak height after 7 days / Absorption peak height after 30 minutes Storage stability is evaluated based on the rate of change in isocyanate group content. The evaluation criteria are described below.

[0229] [Dispersion] ○: No precipitate and / or solid matter adhesion was observed.

[0230] ×: Precipitation and / or adhesion of solid matter were observed.

[0231] [Storage Stability] ○: The isocyanate group content is over 70%.

[0232] △: The isocyanate group content is more than 50% and less than 70%.

[0233] ×: Isocyanate group content is less than 50%.

[0234] 5. Discussion In each embodiment, microcapsules with relatively excellent isocyanate group content and storage stability were obtained.

[0235] On the other hand, in Comparative Example 1, a sufficient isocyanate group content could not be obtained. Furthermore, in Comparative Example 2, sufficient storage stability could not be obtained. Additionally, in Comparative Example 3, a sufficient isocyanate group content could not be obtained. Furthermore, in Comparative Example 4, the isocyanate mixture separated, the O / W emulsion dispersion was insufficient, and microcapsules could not be obtained.

[0236] [Table 1] [Table 2] [Table 3] The following details the abbreviations used in the table.

[0237] PVA: Polyvinyl alcohol DDBSNa: Sodium Decylbenzenesulfonate BYK-028: Silicone-based defoamer, trade name BYK-028, manufactured by BYK. It should be noted that the above-described invention is provided as an example embodiment of the present invention, but it is merely an example and not intended to be limiting. Modifications of the present invention that will be apparent to those skilled in the art are included in the appended claims.

[0238] Industrial availability The microcapsules and their manufacturing method of the present invention are suitable for use as curing agents for resin compositions.

Claims

1. Microcapsules, which are microcapsules with a core-shell structure. The microcapsule has a shell and a core layer encapsulated in the shell. The shell contains urethane urea resin. The urethane-urea resin contains the reaction product of a first polyisocyanate and an active hydrogen compound. The core layer contains a second polyisocyanate. The first polyisocyanate is more reactive with the active hydrogen compound than the second polyisocyanate is.

2. The microcapsule as described in claim 1, wherein, The reactivity is in the following order: Aromatic polyisocyanates, aromatic aliphatic polyisocyanates > aliphatic polyisocyanates > alicyclic polyisocyanates without secondary isocyanate groups > alicyclic polyisocyanates with secondary isocyanate groups.

3. The microcapsule as described in claim 1, wherein, The active hydrogen compound contains an amino-containing compound.

4. The microcapsule as described in claim 1, wherein, The average isocyanate base number of the first polyisocyanate is 2.5 or higher. The average isocyanate base number of the second polyisocyanate is 2.5 or higher.

5. The microcapsule as described in claim 1, wherein, The first polyisocyanate has an isocyanurate backbone. The second polyisocyanate has an isocyanurate backbone.

6. The microcapsule of claim 1, wherein, The first polyisocyanate has a hydrophilic group.

7. The microcapsule of claim 6, wherein, The hydrophilic group of the first polyisocyanate has a nonionic group.

8. The microcapsule of claim 1, wherein, The second polyisocyanate does not have hydrophilic groups.

9. A method for manufacturing microcapsules, comprising the method for manufacturing microcapsules according to any one of claims 1 to 8, the method comprising: The preparation process involves preparing an isocyanate mixture containing the first polyisocyanate and the second polyisocyanate; and In the reaction process, the isocyanate mixture is mixed with the active hydrogen compound in the presence of a hydrophobic solvent with a ClogP value of 2.0 to 5.0, and the first polyisocyanate and the active hydrogen compound are interfacially polymerized in a manner that includes the second polyisocyanate, to form the shell layer and the core layer encapsulated in the shell layer.

10. The method for manufacturing microcapsules as described in claim 9, wherein, In the reaction process First, an O / W emulsion is prepared by adding a mixture containing the isocyanate mixture and the hydrophobic solvent to an aqueous solution containing an emulsifier. Next, the active hydrogen compound is added to the O / W emulsion to allow the first polyisocyanate to undergo interfacial polymerization with the active hydrogen compound.

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