WO2019035382A1 - Hollow resin particles, heat-sensitive recording material, and method for producing hollow resin particles - Google Patents

Abstract

These hollow resin particles are hollow and comprise an urethane/urea resin, wherein: the urethane/urea resin is a reaction product of an urethane prepolymer having an isocyanate group and a chain-extending compound having an active hydrogen group; the urethane prepolymer is a reaction product of a polyisocyanate component and an active hydrogen group-containing component containing a carboxylic group; and at least one among the polyisocyanate component and the active hydrogen group-containing component contains a compound having a ring structure.

Description

Hollow resin particle, thermosensitive recording material, and method for producing hollow resin particle

The present invention relates to a hollow resin particle, a thermosensitive recording material, and a method of producing the hollow resin particle, and more specifically, a hollow resin particle, a thermosensitive recording material provided with a heat insulating layer containing the hollow resin particle, and a method of producing the hollow resin particle. About.

Conventionally, hollow resin particles are used in many fields such as thermosensitive recording materials such as thermosensitive recording paper and thermal transfer receiving paper, pesticides, medicines, perfumes, liquid crystals, adhesives and the like.

Such hollow resin particles are obtained, for example, by blending an aromatic isocyanate as a protective film-forming substance in a volatile solvent to obtain a dispersed phase, separately blending a dispersing agent in water to obtain a continuous phase, and then The dispersion phase is mixed and dispersed in this continuous phase to obtain a dispersion, and then the dispersion is reacted to obtain microcapsules containing a volatile solvent with a protective film-forming substance, and then volatilization The organic solvent is vaporized to make the inside of the microcapsule hollow (for example, see Patent Document 1 below).

Unexamined-Japanese-Patent No. 2006-326457

In such hollow resin particles, when the volume average particle diameter is too large, for example, when a resin containing hollow resin particles is applied to a substrate, the smoothness of the coating film is reduced. If the hollow resin particles have too small a volume average particle diameter, the absolute value of the thickness of the protective film decreases if the hollowness ratio is constant, so the particles are easily crushed and easily deformed, and as a heat insulating material In the case of using, it is inferior to heat insulation. Therefore, it is required to adjust the volume average particle diameter of the hollow resin particles.

On the other hand, in the manufacturing method of patent document 1, after mix | blending a protective film formation substance with a volatile solvent, it is made to disperse | distribute using a dispersing agent. However, in such a method, the dispersion becomes uneven and the distribution of the volume average particle diameter is broadened, so that it is difficult to adjust the volume average particle diameter.

The present invention provides a hollow resin particle that can be adjusted to a desired volume average particle size, a thermosensitive recording material provided with a heat insulating layer containing the hollow resin particle, and a method for producing hollow resin particles that can be adjusted to a desired volume average particle size. It is to do.

The present invention [1] is a hollow resin particle which is hollow inside and is made of a urethane-urea resin, and the urethane-urea resin is a chain extending compound having a urethane prepolymer having an isocyanate group and an active hydrogen group. And the urethane prepolymer is a reaction product of a polyisocyanate component and an active hydrogen group-containing component containing a carboxyl group, and is one of the polyisocyanate component and the active hydrogen group-containing component. At least one of them is a hollow resin particle containing a compound having a ring structure.

According to this hollow resin particle, since the urethane / urea resin has a carboxyl group, the volume average particle diameter of the hollow resin particle is adjusted.

In addition, since at least one of the polyisocyanate component and the active hydrogen group-containing component contains a compound having a ring structure, it is excellent in strength.

The hollow resin particle according to the above [1], wherein the active hydrogen group-containing component of the present invention [2] comprises a polyhydric alcohol, and a carboxyl group-containing active hydrogen compound having a carboxyl group and two active hydrogen groups. Contains.

According to this hollow resin particle, since the active hydrogen group-containing component contains a polyhydric alcohol and a carboxyl group-containing active hydrogen compound having a carboxyl group and two active hydrogen groups, the volume average particle diameter of the hollow resin particle is It is further adjusted, and the volume average particle diameter of the hollow resin particles can be further reduced.

The present invention [3] includes the hollow resin particles described in the above [2], wherein the polyhydric alcohol has a ring structure.

According to this hollow resin particle, since the polyhydric alcohol has a ring structure, it is excellent in strength.

The present invention [4] includes the hollow resin particles described in the above [3], wherein the polyhydric alcohol has an alicyclic structure and / or an aromatic ring structure.

According to this hollow resin particle, since the polyhydric alcohol has an alicyclic structure and / or an aromatic ring structure, it is excellent in strength.

The hollow resin according to the above [1], wherein the active hydrogen group-containing component does not contain a polyhydric alcohol but contains a carboxyl group-containing active hydrogen compound having a carboxyl group and two active hydrogen groups according to the present invention [5] Contains particles.

According to this hollow resin particle, since the active hydrogen group-containing component does not contain a polyhydric alcohol and contains a carboxyl group-containing active hydrogen compound having a carboxyl group and two active hydrogen groups, the volume average particle diameter of the hollow resin particle Has been adjusted.

The present invention [6] includes the hollow resin particles according to any one of the above [1] to [5], wherein the polyisocyanate component contains a polyisocyanate having a ring structure.

According to this hollow resin particle, since the polyisocyanate component contains the polyisocyanate having a ring structure, the strength is excellent.

The present invention [7] includes the hollow resin particles described in the above [6], wherein the polyisocyanate component contains a diisocyanate having a ring structure.

According to this hollow resin particle, since the polyisocyanate component contains diisocyanate having a ring structure, the particle diameter of the hollow resin particle can be controlled, and the strength is excellent.

This invention [8] contains the hollow resin particle as described in said [7] in which the said polyisocyanate component contains the diisocyanate which has alicyclic structure.

According to this hollow resin particle, since diisocyanate has an alicyclic structure, yellowing of the hollow resin particle can be suppressed while maintaining the strength.

The present invention [9] includes the hollow resin particles according to the above [8], wherein the diisocyanate contains a secondary isocyanate group.

According to this hollow resin particle, since the diisocyanate contains the secondary isocyanate group, the reactivity is low, the side reaction between the isocyanate group and water can be suppressed, and the particle diameter of the hollow resin particle can be controlled.

[10] The hollow resin particle according to any one of the above [1] to [9], wherein both the polyisocyanate component and the active hydrogen group-containing component contain a compound having a ring structure. It contains.

According to this hollow resin particle, since both the polyisocyanate component and the active hydrogen group-containing component contain a compound having a ring structure, the hollow resin particle is excellent in strength while suppressing yellowing.

The present invention [11] contains the hollow resin particles according to any one of the above [1] to [10], wherein the content of the isocyanate group of the urethane prepolymer is 10% by mass or more.

According to this hollow resin particle, since the content of the isocyanate group of the urethane prepolymer is 10% by mass or more, the strength is excellent.

The present invention [12] contains the hollow resin particles according to any one of the above [1] to [11], wherein the urethane / urea resin is crosslinked by a crosslinking agent.

According to this hollow resin particle, since the urethane / urea resin is crosslinked by the crosslinking agent, the strength is excellent.

The present invention [13] is selected from the group consisting of i) a silane coupling agent, ii) a compound having at least one of a carbodiimide group, an oxazoline group and an epoxy group, and iii) a melamine compound The hollow resin particles according to the above [12], which are at least one of the above.

According to this hollow resin particle, the urethane / urea resin is a group consisting of i) a silane coupling agent, ii) a compound having at least one of a carbodiimide group, an oxazoline group and an epoxy group, and iii) a melamine compound. Since it is crosslinked by at least one cross-linking agent selected from the above, the strength is excellent.

The present invention [14] is a hollow resin particle which is hollow inside and is composed of a urethane / urea resin having a carboxyl group and a ring structure.

According to this hollow resin particle, since the urethane / urea resin has a carboxyl group, the volume average particle diameter of the hollow resin particle is adjusted.

In addition, since the urethane / urea resin has a ring structure, it is excellent in strength.

The present invention [15] comprises a support layer, a heat insulation layer, and a thermosensitive recording layer in this order, and the heat insulation layer contains the hollow resin particles according to any one of the above [1] to [14]. It contains a thermosensitive recording material.

The present invention [16] comprises the steps of reacting a polyisocyanate component and an active hydrogen group-containing component containing a carboxyl group to obtain a urethane prepolymer having an isocyanate group, mixing the urethane prepolymer with a hydrophobic solvent. Preparing a mixed solution, adding water to the mixed solution, and obtaining a urethane prepolymer droplet containing the hydrophobic solvent by the urethane prepolymer, chain extension having the urethane prepolymer and an active hydrogen group A step of reacting the compound with the compound to obtain a resin particle comprising a urethane-urea resin containing the hydrophobic solvent, and removing the hydrophobic solvent contained in the resin particle to obtain the urethane-urea resin And the step of obtaining hollow resin particles having a hollow inside, wherein the polyisocyanate component and the active water are provided. Among the groups-containing component contains a compound having at least one is a ring structure, a manufacturing method of the hollow resin particles.

According to this method for producing hollow resin particles, a urethane prepolymer having a carboxyl group and a chain extending compound having an active hydrogen group are reacted to obtain a resin particle comprising a urethane-urea resin containing a hydrophobic solvent. It has a process.

Therefore, the volume average particle diameter of the hollow resin particles can be adjusted.

In addition, since at least one of the polyisocyanate component and the active hydrogen group-containing component contains a compound having a ring structure, hollow resin particles excellent in strength can be obtained.

The hollow resin particles of the present invention are hollow resin particles composed of a urethane / urea resin, and the urethane / urea resin has a carboxyl group. Therefore, the volume average particle diameter of the hollow resin particles is adjusted. As a result, since the hollow resin particles can be prevented from becoming excessively large, for example, when the resin containing the hollow resin particles is applied to the substrate, the smoothness of the coating film is improved. Moreover, since this hollow resin particle can suppress becoming small too much, an internal space can be ensured and it is excellent in heat insulation.

The heat-sensitive recording material of the present invention is excellent in heat insulation since it comprises the heat insulating layer containing the hollow resin particles of the present invention.

In the method for producing hollow resin particles of the present invention, a urethane prepolymer having a carboxyl group is caused to react with a chain extending compound having an active hydrogen group to obtain a resin particle comprising a urethane-urea resin containing a hydrophobic solvent. It has a process. Therefore, the volume average particle diameter of the hollow resin particles can be adjusted.

FIG. 1 is a cross-sectional view showing an embodiment of the heat-sensitive recording material of the present invention.

The hollow resin particles are produced by reacting a polyisocyanate component and an active hydrogen group-containing component containing a carboxyl group to obtain a urethane prepolymer having an isocyanate group, mixing a urethane prepolymer and a hydrophobic solvent to obtain a mixed liquid Preparing a mixture, adding water to the mixture, and obtaining urethane prepolymer droplets containing a hydrophobic solvent from the urethane prepolymer, reacting the urethane prepolymer with a chain extending compound having an active hydrogen group And a step of obtaining resin particles comprising a urethane-urea resin containing a hydrophobic solvent, and removing the hydrophobic solvent contained in the resin particles to form a urethane-urea resin, wherein the hollow resin is hollow inside It can obtain by the manufacturing method provided with the process of obtaining particles.

In the step of reacting a polyisocyanate component and an active hydrogen group-containing component containing a carboxyl group to obtain a urethane prepolymer having an isocyanate group, an active hydrogen group-containing component containing a polyisocyanate component and a carboxyl group (hereinafter referred to as activity) And hydrogen group-containing component). This gives a urethane prepolymer.

The polyisocyanate component is an organic polyisocyanate compatible with a hydrophobic solvent (described later), and examples thereof include polyisocyanate having a ring structure and polyisocyanate having no ring structure.

The ring structure is a cyclic structure that forms a skeleton of a polyisocyanate monomer, and does not include a cyclic structure (such as an isocyanurate ring) formed by deriving a polyisocyanate monomer. As a ring structure, an alicyclic structure, an aromatic ring structure, etc. are mentioned, for example.

As polyisocyanate which has ring structure, the polyisocyanate monomer which has ring structure, the polyisocyanate derivative which has ring structure, etc. are mentioned, for example.

As a polyisocyanate monomer which has ring structure, the diisocyanate monomer which has ring structure is mentioned, for example.

Examples of diisocyanate monomers having a ring structure include alicyclic diisocyanates, aromatic diisocyanates, and araliphatic diisocyanates.

The alicyclic diisocyanate contains an alicyclic structure such as a cyclohexane ring and a bridged cyclohexane ring, and examples thereof include an alicyclic diisocyanate containing a secondary isocyanate group and an alicyclic diisocyanate containing no secondary isocyanate group. .

Alicyclic diisocyanates containing secondary isocyanate groups contain at least one secondary isocyanate group, for example cyclopentadiisocyanate (1,3- or 1,4-cyclopentadiisocyanate or mixtures thereof), cyclohexane diisocyanate A second having one cyclo ring such as (1,3- or 1,4-cyclohexane diisocyanate or a mixture thereof), methyl cyclohexane diisocyanate (methyl-2,4- or methyl-2,6-cyclohexane diisocyanate or a mixture thereof) Alicyclic Diisocyanates Containing High-Grade Isocyanate Groups, for example, methylene bis (cyclohexyl isocyanate) (4,4'- or 2,4'-methylene bis (cyclohexyl isocyanate) or mixtures thereof ₎ (H 12 _MDI) 2 two alicyclic diisocyanates containing two secondary isocyanate groups such as alicyclic diisocyanates containing secondary isocyanate groups having a cycloalkyl ring such as, for example, 3-isocyanatomethyl - And alicyclic diisocyanates which have one secondary isocyanate group and one primary isocyanate group, such as 3,5,5-trimethylcyclohexyl isocyanate (IPDI).

As an alicyclic diisocyanate which does not contain a secondary isocyanate group, for example, bis (isocyanatomethyl) cyclohexane (1,3- or 1,4-bis (isocyanatomethyl) cyclohexane or a mixture thereof) (H ₆ XDI) For example, bis (isocyanatoethyl) cyclohexane (1,3- or 1,4-bis (isocyanatoethyl) cyclohexane or mixtures thereof), bis (isocyanatomethyl) norbornane (2,5- or 2,6-bis) (Isocyanatomethyl) -bicyclo [2.2.1] heptane or a mixture thereof (NBDI) and the like.

The alicyclic diisocyanate is preferably an alicyclic diisocyanate containing a secondary isocyanate group, more preferably an alicyclic diisocyanate having both one secondary isocyanate group and one primary isocyanate group, and further Preferably, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI) is mentioned.

The secondary isocyanate group is an isocyanate group (> CH—NCO) directly bonded to a carbon atom (secondary carbon atom) having one hydrogen atom.

The primary isocyanate group is an isocyanate group (—CH ₂ —NCO) directly bonded to a carbon atom having two hydrogen atoms (primary carbon atom).

The aromatic diisocyanate contains an aromatic ring structure such as a benzene ring and a condensed ring, and, for example, tolylene diisocyanate (2,4- or 2,6-tolylene diisocyanate or a mixture thereof) (TDI), phenylene diisocyanate (m-, p-phenylene diisocyanate or mixtures thereof), 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate (NDI), diphenylmethane diisocyanate (4,4'-, 2, 4'- or 2, 2'-diphenylmethane) Diisocyanate or a mixture thereof) (MDI), 4,4'-toluidine diisocyanate (TODI), 4,4'-diphenylether diisocyanate and the like.

The araliphatic diisocyanate contains an aliphatic substituted aromatic ring such as alkyl-substituted benzene, for example, xylylene diisocyanate (1,3- or 1,4-xylylene diisocyanate or a mixture thereof) (XDI), tetramethyl xylylene diisocyanate (1,3- or 1,4-tetramethyl xylylene diisocyanate or a mixture thereof) (TMXDI), ω, ω′-diisocyanate-1,4-diethylbenzene and the like.

The polyisocyanate derivative having a ring structure is a derivative of the polyisocyanate monomer having a ring structure described above, for example, a polyisocyanate derivative having a bifunctional ring structure, a polyisocyanate having a polyfunctional ring structure Derivatives and the like can be mentioned.

As a polyisocyanate derivative having a bifunctional ring structure, for example, a dimer (for example, a uretdione derivative) of a diisocyanate monomer having the above ring structure, a bifunctional allophanate derivative (for example, the above ring structure) Biuret derivatives (such as allophanate derivatives formed by the reaction of a diisocyanate monomer with a monohydric alcohol), biuret derivatives (for example, the reaction of a diisocyanate monomer having the above ring structure with a monohydric amine) And the like), urea derivatives (eg, urea derivatives formed by reaction of a diisocyanate monomer having a ring structure described above with diamine), and oxadiazine trione derivatives (eg, a diisocyanate monomer having a ring structure described above) O generated by the reaction with carbon dioxide Sa-trione, etc.), carbodiimide derivatives (carbodiimide derivative produced by decarboxylation condensation reaction of a diisocyanate monomer having a ring structure as described above), and the like.

The polyisocyanate derivative having a polyfunctional ring structure has three or more isocyanate groups, and for example, a trimer of a diisocyanate monomer having the ring structure described above (eg, isocyanurate derivative, iminooxadiazine) Dione derivatives), multifunctional allophanate derivatives (eg, allophanate derivatives produced by reaction of a diisocyanate monomer having the above-described ring structure with a dihydric alcohol), etc.), polyfunctional biuret derivatives (eg, the above-mentioned) Biuret derivatives produced by the reaction of a diisocyanate monomer having a ring structure with a divalent amine and the like, polyfunctional polyol derivatives (eg, a diisocyanate monomer having the above ring structure, and trimethylolpropane etc.) Polyol induced by reaction with trihydric alcohol Body (alcohol adduct), etc.), uretonimine derivative (e.g., such as uretonimine derivative produced from the reaction of a diisocyanate monomer having the ring structures described above and carbodiimide derivative described above) can be mentioned.

The polyisocyanate derivative having a ring structure preferably includes a polyisocyanate derivative having a bifunctional ring structure.

The polyisocyanate having a ring structure can be used alone or in combination of two or more.

As a polyisocyanate which does not have ring structure, the polyisocyanate monomer which does not have ring structure, the polyisocyanate derivative which does not have ring structure, etc. are mentioned, for example.

As a polyisocyanate monomer which does not have ring structure, aliphatic polyisocyanate etc. are mentioned, for example.

Examples of aliphatic polyisocyanates include ethylene diisocyanate, trimethylene diisocyanate, 1,2-propylene diisocyanate, butylene diisocyanate (tetramethylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate ), 1,5-pentamethylene diisocyanate (PDI), 1,6-hexamethylene diisocyanate (HDI), 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methyl capate And aliphatic diisocyanates such as dodecamethylene diisocyanate.

The polyisocyanate derivative having no ring structure is the aforementioned derivative of the polyisocyanate monomer having no ring structure as described above.

The polyisocyanates having no ring structure can be used alone or in combination of two or more.

The polyisocyanate component preferably comprises a polyisocyanate having a ring structure. That is, the polyisocyanate component preferably contains a compound having a ring structure.

Specifically, the blending ratio of the polyisocyanate having a ring structure is, for example, 50% by mass or more, preferably 90% by mass or more, and more preferably 100% by mass, with respect to the polyisocyanate component.

When the polyisocyanate component contains a compound having a ring structure, the strength of the hollow resin particle is excellent.

More preferably, the polyisocyanate component includes a polyisocyanate monomer containing an alicyclic structure or a polyisocyanate derivative containing an alicyclic structure.

When the polyisocyanate component includes a polyisocyanate monomer having an alicyclic structure or a polyisocyanate derivative having an alicyclic structure, yellowing of the hollow resin particles can be suppressed.

In addition, more preferably, the polyisocyanate component includes a diisocyanate monomer having a ring structure or a polyisocyanate derivative having a bifunctional ring structure, and more preferably includes a diisocyanate monomer having a ring structure.

If the polyisocyanate component includes a diisocyanate monomer having a ring structure or a polyisocyanate derivative having a bifunctional ring structure, the diisocyanate monomer having a ring structure and the active hydrogen group-containing component (preferably a dihydric alcohol) The molecular weight of the urethane prepolymer can be easily adjusted by adjusting the compounding ratio to (described later), and the particle diameter of the hollow resin particles can be controlled.

Particularly preferably, the polyisocyanate component includes, among polyisocyanates having such a ring structure, a diisocyanate monomer containing an alicyclic structure (alicyclic diisocyanate).

When the polyisocyanate component contains an alicyclic diisocyanate, the particle diameter of the hollow resin particles can be controlled, yellowing of the hollow resin particles is suppressed, and the strength of the hollow resin particles is excellent.

Most preferably, the polyisocyanate component comprises, among such alicyclic diisocyanates, an alicyclic diisocyanate containing a secondary isocyanate group.

If the polyisocyanate component contains an alicyclic diisocyanate containing a secondary isocyanate group, the reactivity can be lowered, the side reaction between the isocyanate group and water can be suppressed, and the particle diameter of the hollow resin particle can be controlled.

As the active hydrogen group-containing component, for example, a carboxyl group-containing active hydrogen compound having a polyhydric alcohol as an optional component, a carboxyl group as an essential component and two active hydrogen groups (hereinafter referred to as a carboxyl group-containing active hydrogen compound) And the like.

Examples of polyhydric alcohols include polyhydric alcohols having a ring structure, and polyhydric alcohols having no ring structure.

Examples of polyhydric alcohols having a ring structure include dihydric alcohols having a ring structure.

As a dihydric alcohol which has ring structure, an alicyclic dihydric alcohol, an aromatic dihydric alcohol, an aromatic alicyclic dihydric alcohol etc. are mentioned, for example.

The alicyclic dihydric alcohol contains an alicyclic structure such as cyclohexane ring, bridged cyclohexane ring, etc., for example, cyclohexanediol (1,2- or 1,3- or 1,4-cyclohexanediol or a mixture thereof), cyclohexane Methanol (1,2- or 1,3- or 1,4-cyclohexanedimethanol or a mixture thereof), cyclohexanediethanol (1,2- or 1,3- or 1,4-cyclohexanediethanol or a mixture thereof), hydrogenation Bisphenol A, spiro glycol, isosorbide and the like.

The aromatic dihydric alcohol includes an aromatic ring structure such as a benzene ring and a condensed ring, and, for example, bisphenol A, an ethylene oxide adduct of bisphenol A, a propylene oxide adduct of bisphenol A, 2,2-bis (4-polyoxy) Propylene oxyphenyl) propane and the like can be mentioned.

The aromatic alicyclic dihydric alcohol contains an aliphatic substituted aromatic ring such as alkyl-substituted benzene, and examples thereof include xylene glycol, bishydroxyethoxybenzene, and bishydroxyethylene terephthalate.

The dihydric alcohol having a ring structure is preferably an alicyclic dihydric alcohol or an aromatic dihydric alcohol, more preferably cyclohexanediol, cyclohexanedimethanol or 2,2-bis (4-polyoxypropyleneoxyphenyl). And propane), more preferably 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol and 2,2-bis (4-polyoxypropyleneoxyphenyl) propane.

The dihydric alcohols having a ring structure can be used alone or in combination of two or more.

Examples of polyhydric alcohols having no ring structure include aliphatic polyhydric alcohols.

As aliphatic polyhydric alcohols, for example, ethylene glycol, propylene glycol (1,2- or 1,3-propanediol or a mixture thereof), butylene glycol (1,2- or 1,3- or 1,4-butylene) Glycol or mixtures thereof), 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,2,2-trimethylpentanediol, 3,3-di Alkane diols such as methylol heptane, for example, dihydric alcohols such as diethylene glycol, triethylene glycol, ether diols such as dipropylene glycol, for example trihydric alcohols such as glycerin, trimethylol propane, triisopropanolamine etc. Tetrahydric alcohols such as lamethylolmethane (pentaerythritol), diglycerin, for example, pentahydric alcohols such as xylitol, for example, hexahydric alcohols such as sorbitol, mannitol, allitol, iditol, dulcitol, altrytol, inositol, dipentaerythritol For example, heptahydric alcohols such as perseitol, for example, octahydric alcohols such as sucrose, etc., preferably dihydric alcohols, more preferably alkane diols, still more preferably ethylene glycol, butylene glycol, neopentyl Glycols are particularly preferably ethylene glycol, 1,4-butylene glycol, neopentyl glycol.

Polyhydric alcohols having no ring structure can be used alone or in combination of two or more.

The polyhydric alcohol preferably includes a polyhydric alcohol having a ring structure. That is, the polyhydric alcohol preferably has a ring structure, more preferably an alicyclic structure and / or an aromatic ring structure.

Specifically, the blending ratio of the polyhydric alcohol having a ring structure is, for example, 50% by mass or more, preferably 90% by mass or more, and more preferably 100% by mass, with respect to the polyhydric alcohol.

When the polyhydric alcohol has a ring structure (preferably, an alicyclic structure and / or an aromatic ring structure), the strength of the hollow resin particle is excellent.

The carboxyl group-containing active hydrogen compound is an organic compound having two active hydrogen groups (hydroxyl group, amino group etc.) and one carboxyl group.

In addition, the carboxyl group may form a salt by the neutralizing agent mentioned later.

As the carboxyl group-containing active hydrogen compound, for example, 2,2-dimethylolacetic acid, 2,2-dimethylollactic acid, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, dimethylolheptanoic acid, dimethylolol Nonanoic acid, 2,2-dimethylol butyric acid, 2,2-dimethylol valeric acid etc. are mentioned, Preferably, 2,2- dimethylol propionic acid is mentioned.

These carboxyl group-containing active hydrogen compounds can be used alone or in combination of two or more.

The active hydrogen group-containing component contains a polyhydric alcohol and a carboxyl group-containing active hydrogen compound (first active hydrogen group-containing component), or contains no carboxyl group and contains a carboxyl group-containing active hydrogen compound Second active hydrogen group-containing component).

The first active hydrogen group-containing component comprises a polyhydric alcohol and a carboxyl group-containing active hydrogen compound, and preferably comprises a polyhydric alcohol and a carboxyl group-containing active hydrogen compound.

The second active hydrogen group-containing component does not contain a polyhydric alcohol and contains a carboxyl group-containing active hydrogen compound, and preferably comprises a carboxyl group-containing active hydrogen compound.

When the active hydrogen group-containing component contains a carboxyl group-containing active hydrogen compound, the volume average particle diameter of the hollow resin particles can be adjusted.

In addition, when the active hydrogen group-containing component contains a polyhydric alcohol together with the carboxyl group-containing active hydrogen compound, the compatibility of the hydrophobic solvent described later is enhanced, and the volume average particle diameter of the hollow resin particles can be further adjusted. The volume average particle diameter of the hollow resin particles can be further reduced.

In the present invention, at least one of the polyisocyanate component and the active hydrogen group-containing component contains a compound having a ring structure.

Specifically, as the urethane prepolymer formulation, the polyisocyanate component contains a compound having a ring structure, and the active hydrogen group-containing component does not contain a compound having a ring structure (first formulation), and the polyisocyanate component Formulations (second formulation) in which the active hydrogen group-containing component does not contain a compound having a ring structure and the active hydrogen group-containing component contains a compound having a ring structure, and both the polyisocyanate component and the active hydrogen group-containing component have a ring structure The prescription (3rd prescription) containing a compound is mentioned.

That is, as a urethane prepolymer formulation, a formulation in which both the polyisocyanate component and the active hydrogen group-containing component do not contain a compound having a ring structure is not included in the present invention.

More specifically, the first formulation contains a polyisocyanate having a ring structure and a carboxyl group-containing active hydrogen compound having no ring structure, and preferably, a polyisocyanate having a ring structure and no ring structure A polyhydric alcohol and a carboxyl group-containing active hydrogen compound having no ring structure are included.

The second formulation contains a polyisocyanate having no ring structure, a polyhydric alcohol having a ring structure, and a carboxyl group-containing active hydrogen compound, and preferably a polyisocyanate having no ring structure and a ring structure. And a carboxyl group-containing active hydrogen compound having no ring structure.

The third formulation contains a polyisocyanate having a ring structure, a polyhydric alcohol having a ring structure, and a carboxyl group-containing active hydrogen compound, and preferably, a polyisocyanate having a ring structure and a poly ring having a ring structure. And a carboxyl group-containing active hydrogen compound having no ring structure.

When at least one of the polyisocyanate component and the active hydrogen group-containing component contains a compound having a ring structure, the strength of the hollow resin particle is excellent.

Among these formulations, preferably, formulations in which the polyisocyanate component contains a compound having a ring structure (that is, the first formulation, the third formulation) can be mentioned.

If the polyisocyanate component contains a compound having a ring structure, the strength of the hollow resin particles is further enhanced.

Among these formulations, more preferably, formulations containing a compound in which both the polyisocyanate component and the active hydrogen group-containing component have a ring structure (that is, the third formulation) are mentioned.

If both the polyisocyanate component and the active hydrogen group-containing component contain a compound having a ring structure, the strength of the hollow resin particle can be further improved.

And, in order to make the polyisocyanate component and the active hydrogen group-containing component react, the polyisocyanate component and the active hydrogen group-containing component should have an excess of the equivalent ratio of the isocyanate group to the active hydrogen group (NCO / active hydrogen group) The ratio is, for example, 1.25 or more, preferably 1.55 or more, and for example, 21.2 or less, preferably 2.85 or less.

As reaction conditions, under atmospheric pressure, the reaction temperature is, for example, 40 ° C. or more, preferably 60 ° C. or more, and for example, 100 ° C. or less. The reaction time is, for example, 1 hour or more, and for example, 24 hours or less.

In this reaction, for example, an amine-based, tin-based or lead-based urethanization catalyst may be added, if necessary, and after completion of the reaction, unreacted poly as required. The isocyanate component can also be removed, for example, by known removal means such as distillation or extraction.

By this, the molecular terminal of the reaction product (i.e., urethane prepolymer) becomes an isocyanate group. Preferably, both ends of the main chain of the reaction product are isocyanate groups.

In order for both ends of the main chain of the reaction product to be isocyanate groups, preferably, a diisocyanate, a carboxyl group-containing active hydrogen compound, and, if necessary, a dihydric alcohol are reacted.

The urethane prepolymer may have an isocyanate group in the side chain (other than the molecular end).

The content (in terms of solid content) of the isocyanate group of the urethane prepolymer is, for example, 5% by mass or more, preferably 10% by mass or more, and for example, 35% by mass or less, preferably 20% by mass or less It is.

The content of isocyanate group can be measured by n-dibutylamine method according to JIS K-1603 using a potentiometric titrator.

If the content of the isocyanate group of the urethane prepolymer is the above lower limit or more, the volume average particle diameter of the hollow resin particles can be adjusted, and the strength of the hollow resin particles is excellent.

As the reaction method, for example, known polymerization methods such as bulk polymerization and solution polymerization can be mentioned, and preferably, solution polymerization can be mentioned.

In solution polymerization, a polyisocyanate component and an active hydrogen group-containing component are mixed in a solvent and polymerized, for example, under a nitrogen atmosphere.

As the solvent, esters such as ethyl acetate and butyl acetate, ether esters such as propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate, aromatic hydrocarbons such as benzene, toluene and xylene, hexane and 2-ethylhexyl And aliphatic hydrocarbons such as cyclohexane and methylcyclohexane, preferably esters, aromatic hydrocarbons and aliphatic hydrocarbons, and more preferably ethyl acetate, xylene, cyclohexane and methyl. Cyclohexane is mentioned.

The solvents can be used alone or in combination of two or more.

When the polyisocyanate component and the active hydrogen group-containing component are reacted in a solvent, the solid content concentration of the urethane prepolymer in the solvent is, for example, 50% by mass or more, preferably 70% by mass or more. Also, for example, 90% by mass or less.

In such a case, the urethane prepolymer can be used in the next step as the reaction liquid containing the solvent.

Next, the urethane prepolymer and the hydrophobic solvent are mixed to prepare a mixed solution, water is added to the mixed solution, and urethane prepolymer droplets containing the hydrophobic solvent are obtained by the urethane prepolymer in the step of urethane The prepolymer and the hydrophobic solvent are mixed to prepare a mixture, and water is added to the mixture. Thus, urethane prepolymer droplets containing a hydrophobic solvent are obtained by the urethane prepolymer.

Specifically, first, a urethane prepolymer and a hydrophobic solvent are mixed to prepare a mixed solution.

As the hydrophobic solvent, the same solvents as those described above can be mentioned.

The blending ratio of the hydrophobic solvent (the total amount of the solvent of the reaction solution and the hydrophobic solvent when used as the reaction solution) is, for example, 150 parts by mass or more, preferably, 100 parts by mass of the urethane prepolymer. It is 200 parts by mass or more, and for example, 600 parts by mass or less.

Moreover, a crosslinking agent can also be mix | blended with the liquid mixture as needed.

When a crosslinking agent is blended in the liquid mixture, the urethane / urea resin (described later) is crosslinked by the crosslinking agent, so the strength of the hollow resin particles is excellent.

Examples of the crosslinking agent include silane coupling agents, for example, compounds having at least one of a carbodiimide group, an oxazoline group, and an epoxy group, such as a melamine compound.

As a silane coupling agent, for example, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) Epoxy group-containing silane coupling agents such as ethyltrimethoxysilane, for example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N Amino group-containing silane coupling agents such as -2- (aminoethyl) -3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, for example, 3-acryl Roxypropyltrimethoxysilane, 3-methane (Meth) acrylic group-containing silane coupling agents such as chloroxypropyl triethoxysilane, for example, cyanate group-containing silane coupling agents such as 3-isocyanatopropyltriethoxysilane, for example, 3-mercaptopropyltrimethoxysilane Mercapto group-containing silane coupling agents, and the like.

As a compound which has at least one among a carbodiimide group, an oxazoline group, and an epoxy group, a carbodiimide type crosslinking agent, an oxazoline type crosslinking agent, an epoxy type crosslinking agent etc. are mentioned, for example.

Examples of the melamine compound include alkylated melamine resins such as methylated melamine resins and butylated melamine resins.

The crosslinking agent is preferably at least one selected from the group consisting of i) a silane coupling agent, ii) a compound having at least one of a carbodiimide group, an oxazoline group and an epoxy group, iii) a melamine compound It can be mentioned.

If the crosslinking agent is at least one selected from the group consisting of i) a silane coupling agent, ii) a compound having at least one of a carbodiimide group, an oxazoline group and an epoxy group, iii) a melamine compound, a urethane -Since the urea resin (described later) is crosslinked by the above crosslinking agent, the strength of the hollow resin particles is excellent.

Further, as the crosslinking agent, more preferably, a silane coupling agent, more preferably, an incyanate group-containing silane coupling agent, a mercapto group-containing silane coupling agent, more preferably, 3-isocyanatopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane is mentioned.

These crosslinking agents can be used alone or in combination of two or more.

The blending ratio of the crosslinking agent is, for example, 1 part by mass or more, preferably 5 parts by mass or more, and for example, 30 parts by mass or less with respect to 100 parts by mass of the urethane prepolymer.

In addition, as described later, the crosslinking agent may be added after reacting the urethane prepolymer with the chain extending compound having an active hydrogen group.

Moreover, when mix | blending a crosslinking agent to a liquid mixture, a crosslinking catalyst can also be mix | blended as needed.

The crosslinking catalyst may, for example, be a triethylamine neutralized product of p-toluenesulfonic acid or an amine salt of an organic acid such as a triethylamine neutralized product of dodecylbenzenesulfonic acid, and in particular, when the crosslinking agent is a melamine compound, Preferably, the triethylamine neutralization thing of dodecylbenzenesulfonic acid is mentioned.

These crosslinking catalysts can be used alone or in combination of two or more.

The blending ratio of the crosslinking catalyst is, for example, 1 part by mass or more, preferably 4 parts by mass or more, and for example, 20 parts by mass or less with respect to 100 parts by mass of the urethane prepolymer.

Further, as described later, the crosslinking catalyst may be added after the reaction of the urethane prepolymer and the chain extending compound having an active hydrogen group.

Subsequently, water is added to the mixed solution collectively or in portions.

When the reactivity of the urethane prepolymer is high, the temperature of the mixture is adjusted to, for example, 20 ° C. or less, if necessary.

At this time, the hydrophobic solvent is dispersed in water, while the molecular skeleton of the urethane prepolymer has an affinity for the hydrophobic solvent, and the carboxyl group has an affinity for water. Therefore, the urethane prepolymer has water and a hydrophobic solvent. Intervene between

In particular, urethane prepolymers encapsulate hydrophobic solvents in water.

Thus, urethane prepolymer droplets containing a hydrophobic solvent are obtained by the urethane prepolymer.

Such urethane prepolymer droplets are dispersed in water. That is, an aqueous dispersion containing urethane prepolymer droplets is obtained.

Since the urethane prepolymer has a carboxyl group, the urethane prepolymer droplets are easily dispersed by mixing with water, without separately adding a dispersant.

Further, as described above, in the case of the phase inversion emulsification method in which water is added to the mixed solution, the volume average particle diameter of the hollow resin particles can be adjusted as compared with the normal phase emulsification method in which the mixed solution is added to water.

Then, in the step of reacting the urethane prepolymer with a chain extending compound having an active hydrogen group to obtain resin particles comprising a urethane-urea resin containing a hydrophobic solvent, the urethane prepolymer and the active hydrogen group are contained. A chain extending compound (hereinafter referred to as a chain extending compound) is reacted. Thus, resin particles made of a urethane-urea resin containing a hydrophobic solvent are obtained.

As a chain extending compound, for example, water, for example, a compound having two or more (preferably two) active hydrogen groups such as an amino group and a hydroxyl group can be mentioned.

Examples of chain extending compounds include amino group-containing compounds and hydroxyl group-containing compounds.

As the amino group-containing compound, for example, aromatic polyamines, araliphatic polyamines, alicyclic polyamines, aliphatic polyamines, amino alcohols, polyoxyethylene group-containing polyamines, primary amino groups, or primary amino groups And alkoxysilyl compounds having a secondary amino group, hydrazine or derivatives thereof.

Examples of aromatic polyamines include aromatic diamines such as 4,4'-diphenylmethanediamine and tolylenediamine.

The araliphatic polyamines include, for example, araliphatic diamines such as xylylene diamine (1,3- or 1,4-xylylene diamine or a mixture thereof).

Examples of alicyclic polyamines include 3-aminomethyl-3,5,5-trimethylcyclohexylamine (alias: isophorone diamine), 4,4'-dicyclohexylmethanediamine, 2,5 (2,6) -bis ( Aminomethyl) bicyclo [2.2.1] heptane, 1,4-cyclohexanediamine, 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- and 1,4-bis (aminomethyl) cyclohexane and mixtures thereof And alicyclic diamines.

Examples of aliphatic polyamines include ethylenediamine, propylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexamethylenediamine, and 1,8-octamethylenediamine. Aliphatic diamines such as 1,12-dodecamethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 1,2-diaminoethane, 1,2-diaminopropane, 1,3-diaminopentane and the like.

Examples of amino alcohol include 2-((2-aminoethyl) amino) ethanol (alias: N- (2-aminoethyl) ethanolamine), 2-((2-aminoethyl) amino) -1-methylpropanol (Alias: N- (2-aminoethyl) isopropanolamine) and the like.

Examples of polyoxyethylene group-containing polyamines include polyoxyalkylene ether diamines such as polyoxyethylene ether diamine.

As the alkoxysilyl compound having a primary amino group or a primary amino group and a secondary amino group, for example, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ Alkoxysilyl compounds having a primary amino group such as -aminopropyltrimethoxysilane, N-β (aminoethyl) γ -aminopropyltrimethoxysilane (alias: N-2- (aminoethyl) -3-aminopropyl tri) Methoxysilane), N-β (aminoethyl) γ-aminopropyltriethoxysilane (alias: N-2- (aminoethyl) -3-aminopropyltriethoxysilane), N-β (aminoethyl) γ-aminopropyl Methyldimethoxysilane (alias: N-2- (aminoethyl) -3-aminopropylmethyldi Primary amino groups and secondary ones such as toxisilane), N-β (aminoethyl) γ-aminopropylmethyldiethoxysilane (alias: N-2- (aminoethyl) -3-aminopropylmethyldiethoxysilane) The alkoxy silyl compound etc. which have an amino group are mentioned.

Examples of hydrazine or its derivative include hydrazine (including hydrate), succinic acid dihydrazide, adipic acid dihydrazide and the like.

As an amino group containing compound, Preferably, a hydrazine is mentioned, More preferably, a hydrazine monohydrate is mentioned.

Examples of the hydroxyl group-containing compound include ethylene glycol, propylene glycol, 1,3-propanediol, butylene glycol (1,2- or 1,3- or 1,4-butylene glycol), 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,2,2-trimethylpentanediol, 3,3-dimethylolheptane, alkane (C7-20) diol, 1, 3- or 1,4-cyclohexanedimethanol and mixtures thereof, 1,3- or 1,4-cyclohexanediol and mixtures thereof, hydrogenated bisphenol A, 1,4-dihydroxy-2-butene, 2,6- Dimethyl-1-octene-3,8-diol, bisphenol A, die Glycol, triethylene glycol, a dihydric alcohol such as dipropylene glycol.

These chain extending compounds can be used alone or in combination of two or more.

As a chain extending compound, preferably, an amino group-containing compound is mentioned.

In this reaction, specifically, a chain extending compound is added to water in which urethane prepolymer droplets are dispersed, and stirred.

Specifically, the equivalent ratio (isocyanate group / active hydrogen group) of the isocyanate group of the urethane prepolymer to the active hydrogen group of the chain extending compound is, for example, 0.50 or more, preferably 0.67 or more, or, for example, The chain extending compound is added so as to be 1.43 or less, preferably 1.35 or less.

In this reaction, if necessary, a neutralizing agent, a dispersant such as sodium polyacrylate and the like are blended, and heating and stirring are carried out as necessary.

The neutralizing agent is formulated to neutralize the carboxyl group, and examples thereof include tertiary amines.

Examples of tertiary amines include tertiary amines such as trimethylamine, triethylamine, tripropylamine, tributylamine, N, N-dimethylcyclohexylamine, N-methylmorpholine, N-ethylmorpholine, N-methylpiperidine or N-ethylpiperidine. Monoamines, for example, tertiary diamines such as 1,3-bis- (dimethylamino) -propane, 1,4-bis- (dimethylamino) -butane, N, N'-dimethylpiperazine and the like can be mentioned.

The compounding ratio of the neutralizing agent is, for example, 0.02 mol or more and, for example, 1 mol or less with respect to 1 mol of the urethane prepolymer.

The compounding ratio of the dispersant is, for example, 1 part by mass or more, preferably 5 parts by mass or more, and for example, 20 parts by mass or less with respect to 100 parts by mass of the urethane prepolymer.

The heating temperature is, for example, 10 ° C. or more, and for example, 80 ° C. or less.

The heating (stirring) time is, for example, 1 hour or more, and for example, 24 hours or less.

When the chain extending compound is water, the urethane prepolymer and the hydrophobic solvent are mixed, water is added to the mixed solution, and if necessary, the urethane prepolymer is heated and stirred under the above conditions. React with the chain extending compound.

In this reaction, the urethane prepolymer and the chain extending compound are interfacially polymerized at the interface between the hydrophobic solvent and water. That is, the urethane prepolymer on the surface of the urethane prepolymer droplet reacts with the chain extending compound.

Therefore, by this reaction, resin particles composed of a urethane-urea resin containing a hydrophobic solvent can be obtained.

Such resin particles are dispersed in water.

The urethane / urea resin is a polymer containing a urethane group and / or a urea group.

Specifically, when the chain extending compound is water or an amino group-containing compound, the isocyanate group of the urethane prepolymer reacts with water or the amino group of the amino group-containing compound to form a urea bond. Is formed to obtain a urea resin (this is also a urethane-urea resin (described later) in consideration of the urethane group in the urethane polymer).

When the chain extending compound is a hydroxyl group-containing compound, the isocyanate group of the urethane prepolymer reacts with the hydroxyl group of the hydroxyl group-containing compound to form a urethane bond, whereby a urethane resin is obtained.

When the chain extending compound is water or an amino group-containing compound and a hydroxyl group-containing compound, the isocyanate group of the urethane prepolymer reacts with water or the amino group of the amino group-containing compound to cause urea While the bond is formed, the isocyanate group of the urethane prepolymer and the hydroxyl group of the hydroxyl group-containing compound react to form a urethane bond, whereby a urethane-urea resin is obtained.

That is, the urethane-urea resin contains a reaction product of a urethane prepolymer and a chain extending compound, and preferably comprises a reaction product of a urethane prepolymer and a chain extending compound.

When the urethane / urea resin contains a reaction product of a urethane prepolymer and a chain extending compound, the urethane / urea resin can contain a hydrophobic solvent.

In the resin particles, the content of the carboxyl group relative to the total amount of the urethane / urea resin and the hydrophobic solvent is, for example, 0.074% by mass or more, preferably 0.15% by mass or more, more preferably 0.22% by mass Or more, for example, 2.5% by mass or less, preferably 1.25% by mass or less, more preferably 0.58% by mass or less, still more preferably 0.44% by mass or less, particularly preferably And 0.37% by mass or less.

If the content of the above-mentioned carboxyl group is above the above lower limit and below the above upper limit, the particle diameter of the hollow resin particle can be adjusted.

Next, in the step of removing the hydrophobic solvent contained in the resin particles to obtain hollow resin particles made of urethane / urea resin and having a hollow inside, the hydrophobic solvent contained in the resin particles is removed. . As a result, hollow resin particles made of urethane / urea resin and having a hollow inside are obtained.

In order to remove the hydrophobic solvent contained in the resin particles, the aqueous dispersion in which the resin particles composed of the urethane-urea resin containing the hydrophobic solvent are dispersed in water is depressurized to form the urethane-urea resin. The contained hydrophobic solvent is vaporized and replaced with water. As a result, the inside of the resin particle becomes hollow.

Thereby, the hollow resin particle which consists of urethane * urea resin and whose inside is hollow is obtained.

Such hollow resin particles are dispersed in water.

This urethane-urea resin has a carboxyl group. Specifically, the urethane-urea resin has a carboxyl group derived from a carboxyl group-containing active hydrogen compound.

The content of the carboxyl group in the urethane / urea resin is 0.3% by mass or more, preferably 0.6% by mass or more, more preferably 0.89% by mass or more, and 10% by mass or less, Preferably, it is 5% by mass or less, more preferably 2.3% by mass or less, still more preferably 1.75% by mass or less, and particularly preferably 1.47% by mass or less.

If the content of the carboxyl group in the urethane / urea resin is equal to or more than the above lower limit and less than or equal to the above upper limit, the volume average particle diameter of the hollow resin particles can be adjusted.

In addition, content of the carboxyl group in urethane * urea resin can be calculated from preparation amount.

In the obtained hollow resin particles, since the urethane / urea resin has a carboxyl group, the volume average particle diameter of the hollow resin particles is adjusted. Specifically, the active hydrogen group-containing component is an active hydrogen group-containing component. If the component is the first active hydrogen group-containing component, it is, for example, 0.5 μm or more, preferably 1 μm or more, and for example, 10 μm or less, preferably 5 μm or less, and an active hydrogen group-containing component However, if the active hydrogen group-containing component is the second active hydrogen group-containing component, it is 0.5 μm or more, preferably 1 μm or more, and for example, 30 μm or less, preferably 20 μm or less.

In addition, the measuring method of volume average particle diameter is explained in full detail by the Example mentioned later.

When the volume average particle diameter of the hollow resin particles is equal to or less than the above upper limit, for example, when a resin containing the hollow resin particles is applied to a substrate, the smoothness of the coating film is improved.

If the volume average particle diameter of the hollow resin particles is equal to or more than the above lower limit, the heat insulating property is excellent.

In addition, in the method for producing hollow resin particles, the urethane prepolymer has a carboxyl group, so that it can be dispersed stably. Therefore, the volume average particle diameter of the hollow resin particles can be adjusted.

The hollow resin particles are hollow inside. And since this hollow resin particle is adjusted in the volume average particle diameter of the hollow resin particle, even if the hollow resin particle is hollow inside, the strength is excellent and the internal space can be enlarged. Excellent in heat insulation.

The volume hollow ratio of the hollow resin particles is, for example, 30% or more, preferably 60% or more, and for example, 95% or less, preferably 85% or less.

If the volume hollow ratio of the hollow resin particles is equal to or less than the above upper limit, the strength is excellent.

If the volume hollow ratio of the hollow resin particles is equal to or more than the above lower limit, the heat insulating property is excellent.

In addition, the measuring method of volume hollow ratio is explained in full detail by the Example mentioned later.

In addition, this urethane / urea resin has a ring structure. Specifically, the urethane-urea resin has a ring structure derived from at least one of a polyisocyanate component and an active hydrogen group-containing component.

In the obtained hollow resin particles, since the urethane / urea resin has a ring structure, the strength is excellent.

That is, such hollow resin particles are hollow inside and are made of a urethane / urea resin having a carboxyl group and a ring structure.

Therefore, the volume average particle diameter of the hollow resin particles is adjusted, and the strength is excellent.

In addition, a fragrance, a dye, a heat storage material, a drug, an ultraviolet absorber, an inorganic pigment, and the like can be incorporated in the hollow resin particles (hollow part).

In the above description, the urethane prepolymer and the hydrophobic solvent are mixed to prepare a liquid mixture, water is added to the liquid mixture, and the urethane prepolymer droplets containing the hydrophobic solvent with the urethane prepolymer are prepared. In the step of obtaining, although the urethane prepolymer is dispersed without blending the dispersant, the dispersant may be blended to disperse the urethane prepolymer.

In the above description, the urethane prepolymer and the hydrophobic solvent are mixed to prepare a liquid mixture, water is added to the liquid mixture, and the urethane prepolymer droplets containing the hydrophobic solvent by the urethane prepolymer are prepared. In the step of obtaining, water may be added to the mixed solution (phase inversion emulsification method), but the mixed solution may be added to water (normal phase emulsification method).

Such hollow resin particles can be used, for example, in the fields of thermosensitive recording materials, agricultural chemicals, medicines, perfumes, liquid crystals, adhesives and the like, and in particular, they can be suitably used for thermosensitive recording materials.

Therefore, in the heat-sensitive recording material provided with the support layer, the heat insulating layer, and the heat-sensitive recording layer in order, it is preferable that the hollow resin particles be contained in the heat insulating layer.

Specifically, in FIG. 1, the thermosensitive recording material 1 includes a support layer 2, a heat insulating layer 3 and a thermosensitive recording layer 4 in order.

The heat-sensitive recording material 1 is a material that changes color by heat, and examples thereof include a heat-sensitive recording paper and a thermal transfer receiving paper.

Examples of the support layer 2 include paper and plastic sheets. The thickness of the support layer 2 is appropriately set in accordance with the purpose and application.

The heat insulating layer 3 is a layer that prevents the dissipation of heat given from the thermal head to cause the thermal recording layer 4 to develop color.

The heat insulation layer 3 contains the above-mentioned hollow resin particles and a binder resin such as polyvinyl alcohol, polyacrylamide, styrene / butadiene emulsion, acrylic emulsion and the like. The thickness of the heat insulating layer 3 is appropriately set according to the purpose and application.

The thermosensitive recording layer 4 contains the above-described binder resin, a dye, and a developer.

Examples of the dye include known basic organic dyes such as fluoran organic dyes, triallylmethane organic dyes, and phenoxy azine organic dyes.

The developer is not particularly limited, and examples thereof include known developers such as phenolic compounds and aromatic carboxylic acids.

The thickness of the thermosensitive recording layer 4 is appropriately set in accordance with the purpose and application.

In order to manufacture the thermosensitive recording material 1, first, the heat insulating layer 3 is formed on the support layer 2.

In order to form the heat insulation layer 3, a mixture of hollow resin particles and a binder resin is applied by a known coating method such as curtain coating method, roll coating method, blade coating method and the like, and then dried.

Next, the heat sensitive recording layer 4 is formed on the heat insulating layer 3.

In order to form the thermosensitive recording layer 4, a mixture of the above-mentioned binder resin, dye and developer is applied by a known coating method such as curtain coating, roll coating or blade coating, and thereafter ,dry.

Thereby, the thermosensitive recording material 1 is obtained.

And in such a thermosensitive recording material 1, the heat insulation layer 3 contains the above-mentioned hollow resin particles. Therefore, the heat-sensitive recording material 1 is excellent in heat insulation.

In the above description, the thermosensitive recording material 1 is composed of the support layer 2, the heat insulating layer 3 and the thermosensitive recording layer 4. For example, between the support layer 2 and the heat insulating layer 3, the heat insulating layer 3 and the thermosensitive recording layer An intermediate layer (not shown) may be interposed between them and 4.

In addition, an overcoat layer (not shown) may be disposed on the thermosensitive recording layer 4. In such a case, the heat-sensitive recording material 1 sequentially includes a support layer 2, a heat insulating layer 3, a heat-sensitive recording layer 4, and an overcoat layer (not shown).

Also, a back coat layer (not shown) may be disposed under the support layer 2. In such a case, the thermosensitive recording material 1 includes a backcoat layer (not shown), a support layer 2, a heat insulation layer 3, and a thermosensitive recording layer 4 in this order.

The heat-sensitive recording material 1 can also be provided with both the above-mentioned overcoat layer (not shown) and the above-mentioned backcoat layer (not shown). In such a case, the thermosensitive recording material 1 comprises a backcoat layer (not shown), a support layer 2, a heat insulating layer 3, a thermosensitive recording layer 4 and an overcoat layer (not shown) in this order. .

Specific numerical values such as blending ratios (content ratios), physical property values, parameters, etc. used in the following description are the blending ratios (content ratios) corresponding to those described in the above-mentioned "embodiments for carrying out the invention" ), Physical property values, parameters, etc. may be substituted for the upper limit (numerical values defined as “below”, “less than”) or lower limit (numerical values defined as “above”, “exceed”), etc. it can. Moreover, unless there is particular mention in the following description, "part" and "%" are mass references.

1. Details of Components and Apparatus Each component used in each synthesis example, each example and each comparative example is described below.
IPDI: 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate H ₆ XDI: 1,3-bis (isocyanatomethyl) cyclohexane XDI: 1,3-xylylene diisocyanate HDI: 1,6-hexamethylene diisocyanate D-170N: isocyanurate derivative of HDI CHDM: 1,4-cyclohexanedimethanol BA-P2M: 2,2-bis (4-polyoxypropyleneoxyphenyl) propane NPG: neopentyl glycol EG: ethylene glycol 1,4- BG: 1,4-butylene glycol TMP: trimethylolpropane DMPA: 2, 2-dimethylol propionic acid EA: ethyl acetate MCH: methylcyclohexane CH: cyclohexane XY: xylene TEA: triethylamine Size 530: Polyacrylic acid soda KBE-9007: 3-isocyanatopropyltriethoxysilane, Shin-Etsu Chemical KBM-803: 3-mercaptopropyltrimethoxysilane, Shin-Etsu Chemical Co., Ltd. Cymel 325: methylated melamine resin, allnex company Uvan 225: butylated melamine resin, Mitsui Chemicals, Inc. 2. Preparation of Urethane Prepolymer Synthesis Example 1
Add 15.0 parts by mass of CHDM, 3.8 parts by mass of DMPA and 20.0 parts by mass of EA as a solvent to a glass flask equipped with an electromagnetic induction stirrer, a reflux condenser, and a nitrogen introduction pipe, and raise to 40 ° C under stirring. It warmed. Next, 61.2 parts by mass of IPDI was added, and reaction was performed at 70 to 80 ° C. in a nitrogen atmosphere until the isocyanate group concentration became 12.0% or less, to obtain a urethane prepolymer. The solid concentration was 79.1%, and the NCO group concentration was 11.8%.

Synthesis Examples 2 to 13, 15, 16
A urethane prepolymer was obtained in the same manner as in Synthesis Example 1 except that the formulation was changed according to the description in Table 1.

In Synthesis Example 10, XDI was added dropwise over about 1 hour, and the reaction was performed at 50 to 60 ° C. in a nitrogen atmosphere until the NCO group concentration became 12.0% or less.

In addition, in Synthesis Example 12, HDI was added dropwise over about 1 hour, and reaction was performed at 50 to 60 ° C. in a nitrogen atmosphere until the NCO group concentration became 12.0% or less.

Synthesis example 14
In a flask equipped with an electromagnetic induction stirrer and reflux cooling, 48.2 parts by mass of D-170N, 1.8 parts by mass of glycolic acid, and 50.0 parts by mass of EA were placed. Subsequently, the urethane prepolymer was obtained by heating and stirring at 50 ° C. for 1 hour and further at 80 ° C. for 12 hours. The solid content concentration was 50.2%, and the isocyanate group concentration was 11.4%.
3. Production of hollow resin particles Example 1
A mixed solution was prepared by mixing 75.0 parts by mass of the urethane prepolymer obtained in Synthesis Example 1, 55.0 parts by mass of EA, 70.0 parts of MCH, and 2.2 parts by mass of TEA. Next, 240.0 parts by mass of distilled water was added to the mixture in three portions and added every 10 minutes while stirring the mixture at 1000 rpm using a TK homomixer (sawtooth type) manufactured by Tokushu Kika Kogyo Co., Ltd. . As a result, an aqueous dispersion containing urethane prepolymer droplets containing EA and MCH was obtained by the urethane prepolymer.

Next, 5.4 parts by mass of hydrazine monohydrate is added to water in which urethane prepolymer droplets are dispersed, and the mixture is stirred at room temperature for 2 hours, and then 8.22 parts by mass of Poise 530 is added and further added. Stir for 30 minutes. Thereafter, the aqueous dispersion was transferred to a flask equipped with a stirrer and reflux cooling, and stirred at 45 ° C. for 3 hours. Thus, an aqueous dispersion containing resin particles composed of a urea resin (urethane-urea resin) containing EA and MCH was obtained.

Thereafter, the aqueous dispersion was depressurized, and EA and MCH contained in the resin particles were distilled off to obtain an aqueous dispersion containing hollow resin particles.

Examples 2 to 20, Comparative Examples 1 to 4
The procedure of Example 1 was repeated except that the formulation was changed as described in Tables 2 to 4, to obtain an aqueous dispersion containing hollow resin particles.

In Examples 2 to 20 and Comparative Examples 1, 2 and 4, a crosslinking agent was blended together with the urethane prepolymer to prepare a liquid mixture.

In Example 15, distilled water was added while the temperature of the mixture was adjusted to 20 ° C. or less.

In Example 16, distilled water was added while the temperature of the mixture was adjusted to 10 ° C. or less.

In Example 17, distilled water was added while adjusting the temperature of the mixture to 15 ° C. or lower.

In Example 19 and Example 20, after adding Poise 530 and stirring for 30 minutes, 9.0 parts by mass of triethylamine neutralized product of dodecylbenzenesulfonic acid is added, and the mixture is stirred for 30 minutes, and then an aqueous dispersion The solution was transferred to a flask with a stirrer and reflux cooling.

Moreover, in the comparative example 1, distilled water was added, adjusting the temperature of the liquid mixture to 15 degrees C or less.

Moreover, in the comparative example 2, distilled water was added, adjusting the temperature of the liquid mixture to 15 degrees C or less.

Moreover, in the comparative example 3, distilled water was added, adjusting the temperature of the liquid mixture to 15 degrees C or less.

Comparative example 5 (external emulsifying prescription)
A mixed solution was prepared by mixing 20.0 parts by mass of D-170N, 20.0 parts by mass of propylene glycol monomethyl ether acetate, and 60.0 parts by mass of XY. Subsequently, 6.0 parts by mass of polyvinyl pyrrolidone (PVP) as a dispersant was dissolved in 296 parts by mass of distilled water while stirring at 1000 rpm using a TK homomixer (sawtooth type) manufactured by Tokushu Kika Kogyo Co., Ltd. The mixture was added and stirred for 5 minutes. Then, this was transferred to a flask with a stirrer and reflux cooling, and 16 parts by mass of a 5% aqueous solution of disodium hydrogen phosphate and 2.5 parts by mass of hydrazine monohydrate were added and stirred at room temperature. A large amount of aggregates was generated.
4. Evaluation (volume average particle diameter)
The volume average particle diameter of the hollow resin particle was measured about the hollow resin particle of each Example and each comparative example. Specifically, 1 g of a sample and 10 g of distilled water are collected in a 30 mL glass sample bottle and stirred for 5 minutes with a magnetic stirrer, and then using a particle size analyzer Microtrac HRA (manufactured by Nikkiso Co., Ltd.), particle size under the following conditions Distribution measurements were performed.

Particle Transparency = Transp
Spherical Particles = Yes
Particle Refractive Index = 1.50
Fluid Refractive Index = 1.333
The results are shown in Tables 2 to 4.

The particle size of 50 hollow resin particles chosen at random was measured about the obtained aggregate about the comparative example 5 with the optical microscope.

The results are shown in Tables 2 to 4.
(Shape and volume hollowness)
The shape of the hollow resin particles was observed for the hollow resin particles of each Example and each Comparative Example, and the volume hollow ratio was measured. Specifically, an aqueous dispersion containing hollow resin particles was coated on an aluminum foil and dried at 40 ° C. for 12 hours or more to obtain a coating. Then, the coating film was immersed in liquid nitrogen for freezing, and then cut rapidly, and the obtained cut surface was observed with an electron microscope. The particle diameter and the diameter of the hollow portion of ten randomly selected hollow resin particles were measured, and the hollow ratio was calculated. The average value of the obtained hollow ratios was taken as the volume hollow ratio of the hollow resin particles.

In Comparative Example 1, when the cut surface was observed, although it could be confirmed that the particles were hollow, they were crushed and the hollow percentage could not be evaluated.

The results are shown in Tables 2 to 4.
(Particle size distribution)
The particle size distribution of the hollow resin particles was measured for the hollow resin particles of the examples and the comparative examples.

When the peak top particle diameter of the main peak is A, based on the data of the integrated distribution of particle diameters (volume basis) obtained from particle diameter measurement by the particle size analyzer micro track HRA, A-0.5A to A + 0. The proportion of hollow resin particles belonging to the range of 5A was determined.

The superiority and inferiority were evaluated according to the following criteria for particle size distribution. The results are shown in Tables 2 to 4.
◎: 60% or more ○: 30% or more and less than 60% ×: 30% or less (strength evaluation)
(Measurement with a scanning electron microscope)
The strength of the hollow resin particles was measured for the hollow resin particles of each example and each comparative example. Specifically, an aqueous dispersion containing hollow resin particles was coated on an aluminum foil in a thickness of 20 to 30 μm, and dried at 40 ° C. for 12 hours or more to obtain a coated film. The surface of the obtained coating film and the cut surface of the coating film were observed with a scanning electron microscope at a magnification of 2000 times. The cut surface of the coated film was obtained by immersing the coated film in liquid nitrogen and freezing it and then rapidly cutting it.

The superiority and inferiority were evaluated according to the following criteria regarding the strength. The results are shown in Tables 2 to 4.
:: All particles on the surface maintain their shape, cross-sections keep voids ○: Some particles on the surface are concaved, cross-sections keep voids △: All particles on the surface are dented, cross-sections keep voids × All particles on the surface are concaved and the cross section can not maintain the void (the Calender test)
The strength of the hollow resin particles was measured for the hollow resin particles of each example and each comparative example. Specifically, an aqueous dispersion containing hollow resin particles adjusted to 10% nonvolatile content with distilled water is applied on one side of a commercially available coated paper (basis weight 74 g / m ² ) and the applied amount after drying is 2 g / m ² It applied so that it might become, and it was made to dry at 80 degreeC by air dryer system for 1 minute, the layer (hollow resin particle layer) containing a hollow resin particle was provided, and the coated paper in which the hollow resin particle was coated was obtained. . This coated paper was subjected to a calendering process using a calendering apparatus ("Tabletop calendering single plate type" manufactured by Yuri Roll Co., Ltd.) at room temperature, a linear pressure of 200 kg / cm, and a processing speed of 2 m / min. The surface on the hollow resin particle layer side of the coated paper after calendering and the cut surface of the hollow resin particle layer were observed with a scanning electron microscope at a magnification of 2000 times. The cut surface of the hollow resin particle layer was obtained by immersing the coated paper in liquid nitrogen to freeze it and then rapidly cutting it.

The superiority and inferiority were evaluated according to the following criteria regarding the strength. The results are shown in Tables 2 to 4.
○: surface particles maintain shape ×: all surface particles are crushed

5. Discussion In Examples 1 to 20 in which the urethane prepolymer has a carboxyl group, it can be seen that the volume average particle diameter can be adjusted to 1.2 μm or more and 18 μm or less.

On the other hand, Comparative Example 5 (external emulsifying formulation) in which an HDI isocyanurate derivative having no carboxyl group is dispersed using a dispersing agent (polyvinylpyrrolidone (PVP)), the dispersion becomes nonuniform, and a large amount of aggregates is produced. Occurred to Therefore, it can be seen that the volume average particle diameter of the hollow resin particles could not be adjusted.

Moreover, the particle diameter of the hollow resin particle of Examples 1 to 20 in which a diisocyanate, a carboxyl group-containing active hydrogen compound having two active hydrogen groups and one carboxyl group at the same time, and optionally a dihydric alcohol are reacted It can be seen that the distribution was 30% or more, and the particle diameter of the hollow resin particles could be accurately controlled.

On the other hand, in Comparative Example 3 in which HDI isocyanurate derivative (trifunctional) is reacted with glycolic acid having one active hydrogen group and one carboxyl group, the particle size distribution of the hollow resin particles is less than 30%. It can be seen that the particle diameter of the hollow resin particles could not be controlled with high accuracy.

Examples 1 to 20 in which at least one of the polyisocyanate component and the active hydrogen group-containing component contains a compound having a ring structure are compounds in which both the polyisocyanate component and the active hydrogen group-containing component have a ring structure It is understood that the strength is superior to Comparative Examples 1 to 4 which do not contain.

Although the above invention is provided as an exemplary embodiment of the present invention, this is merely an example and should not be interpreted in a limited manner. Variations of the invention that are apparent to those skilled in the art are within the scope of the following claims.

The hollow resin particles and the method for producing hollow resin particles according to the present invention can be used in the fields of thermosensitive recording materials, agrochemicals, medicines, perfumes, liquid crystals, adhesives, etc., and particularly preferably used for thermosensitive recording materials. it can.

The heat-sensitive recording material of the present invention is suitably used in the production of heat-sensitive recording paper, thermal transfer receiving paper and the like.

Claims (16)

1. Hollow resin particles which are hollow inside and made of urethane / urea resin,
   The urethane / urea resin is a reaction product of a urethane prepolymer having an isocyanate group and a chain extending compound having an active hydrogen group,
   The urethane prepolymer is a reaction product of a polyisocyanate component and an active hydrogen group-containing component containing a carboxyl group,
   A hollow resin particle, wherein at least one of the polyisocyanate component and the active hydrogen group-containing component contains a compound having a ring structure.
2. The hollow resin particle according to claim 1, wherein the active hydrogen group-containing component comprises a polyhydric alcohol and a carboxyl group-containing active hydrogen compound having a carboxyl group and two active hydrogen groups.
3. The hollow resin particle according to claim 2, wherein the polyhydric alcohol has a ring structure.
4. The hollow resin particle according to claim 3, wherein the polyhydric alcohol has an alicyclic structure and / or an aromatic ring structure.
5. The hollow resin particle according to claim 1, wherein the active hydrogen group-containing component does not contain a polyhydric alcohol but contains a carboxyl group-containing active hydrogen compound having a carboxyl group and two active hydrogen groups.
6. The hollow resin particle according to claim 1, wherein the polyisocyanate component contains a polyisocyanate having a ring structure.
7. The hollow resin particle according to claim 6, wherein the polyisocyanate component comprises diisocyanate having a ring structure.
8. The hollow resin particle according to claim 7, wherein the polyisocyanate component comprises diisocyanate having an alicyclic structure.
9. The hollow resin particle according to claim 8, wherein the diisocyanate contains a secondary isocyanate group.
10. The hollow resin particle according to claim 1, wherein both the polyisocyanate component and the active hydrogen group-containing component contain a compound having a ring structure.
11. The hollow resin particle according to claim 1, wherein the content of the isocyanate group of the urethane prepolymer is 10% by mass or more.
12. The hollow resin particle according to claim 1, wherein the urethane-urea resin is crosslinked by a crosslinking agent.
13. The crosslinking agent is at least one selected from the group consisting of i) a silane coupling agent, ii) a compound having at least one of a carbodiimide group, an oxazoline group, and an epoxy group, and iii) a melamine compound The hollow resin particle according to claim 12, characterized in that.
14. Hollow resin particle, characterized in that the inside is hollow and made of a urethane-urea resin having a carboxyl group and a ring structure.
15. A support layer, a heat insulation layer, and a heat sensitive recording layer in order;
    A heat-sensitive recording material, wherein the heat insulating layer contains the hollow resin particles according to claim 1.
16. Reacting the polyisocyanate component with an active hydrogen group-containing component containing a carboxyl group to obtain a urethane prepolymer having an isocyanate group,
    Mixing the urethane prepolymer and the hydrophobic solvent to prepare a mixture, adding water to the mixture, and obtaining urethane prepolymer droplets containing the hydrophobic solvent from the urethane prepolymer;
    A step of reacting the urethane prepolymer with a chain extending compound having an active hydrogen group to obtain resin particles composed of a urethane-urea resin containing the hydrophobic solvent;
    Removing the hydrophobic solvent contained in the resin particles to obtain hollow resin particles made of the urethane / urea resin and having a hollow inside;
    A method for producing a hollow resin particle, wherein at least one of the polyisocyanate component and the active hydrogen group-containing component contains a compound having a ring structure.

Images