JP2020094048A - Micro capsule - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microcapsule which can be produced without using formaldehyde and contains a large amount of an insect repellent.
SOLUTION: A polycondensate of an isocyanate compound and an amine compound is used as a constituent component of a wall material, an insect repellent is included in the wall material, and the isocyanate compound is polymethylene polyphenyl polyisocyanate and an isocyanate group. And a diisocyanate-modified product having a content of 20% by mass or more.
[Selection diagram] Figure 1

Description

The present invention relates to microcapsules.

As the insect repellent, N,N-diethyl-3-methylbenzamide (also known as N,N-diethyl-m-toluamide, which may be referred to as “DEET” in this specification), 1-(1- Methylpropoxycarbonyl)-2-(2-hydroxyethyl)piperidine (also known as icaridin) and the like are well known.
On the other hand, insect repellents are generally required to have long-lasting effects. Therefore, various studies have been made on microcapsules containing an insect repellent (in other words, microencapsulated insect repellent).

As microencapsulated insect repellents, those in which the wall material component of the microcapsule is melamine resin (see Patent Document 1) and the wall material component of the microcapsule is polyurea (see Patent Document 2) )It has been known.

Japanese Patent No. 2657263 JP-A-3-90682

However, when manufacturing microcapsules containing melamine resin as a wall material component, it is necessary to use an aqueous solution of formaldehyde (also known as formalin) as a raw material. On the other hand, both formaldehyde and formalin are used as pharmaceuticals in Japan. It is designated as a foreign play. That is, the microcapsules containing the melamine resin as the wall material component may contain formaldehyde, and therefore have a problem that the safety may be low.

In addition, in the case of microcapsules containing polyurea as a wall material component, it is difficult to increase the amount of the insect repellent encapsulated, and the insect repellent action is insufficient.

An object of the present invention is to provide a microcapsule that can be produced without using formaldehyde and that contains a large amount of an insect repellent.

The present invention, a polycondensation product of an isocyanate compound and an amine compound as a constituent of the wall material, the insect repellent is included in the wall material, the isocyanate compound, polymethylene polyphenyl polyisocyanate, an isocyanate group And a diisocyanate-modified product having a content of 20% by mass or more.
In the microcapsule of the present invention, it is preferable that the diisocyanate-modified product is one or more selected from the group consisting of a pentamethylene diisocyanate-modified product and a hexamethylene diisocyanate-modified product.

According to the present invention, it is possible to provide microcapsules which can be produced without using formaldehyde and contain a large amount of an insect repellent.

3 is imaging data of the microcapsules obtained in Example 1. 9 is imaging data of the product obtained in Comparative Example 1. 9 is imaging data of a product obtained in Comparative Example 2.

<< microcapsules >>
The microcapsule according to one embodiment of the present invention has a polycondensation product of an isocyanate compound and an amine compound as a constituent component of a wall material, an insect repellent is included in the wall material, and the isocyanate compound is polymethylene. It includes polyphenyl polyisocyanate (which may be referred to as "polymeric MDI" in the present specification) and a diisocyanate-modified product having an isocyanate group content of 20% by mass or more.

In the present specification, the “isocyanate compound” means a compound having an isocyanate group (—NCO).
In this specification, the modified isocyanate group in the diisocyanate modified product described later is not included in the isocyanate group.
In the present specification, the “content of the isocyanate group of the isocyanate compound” means the amount of the isocyanate group contained in one molecule of the isocyanate compound, and is calculated by the following formula.
[Content of isocyanate group in isocyanate compound (mass %)]=[amount of isocyanate group in 1 mol of isocyanate compound (mass part)]/[molecular weight of isocyanate compound]×100

In the present specification, unless otherwise specified, the mere description of “diisocyanate modified product” means the above-mentioned diisocyanate modified product having an NCO content of 20% by mass or more.

In the microcapsule of the present embodiment, the constituent component of the wall material (in this specification, may be abbreviated as “wall material component”) is the weight of the amine compound and the above-mentioned specific range of the isocyanate compound. It is a condensate, i.e. only a specific range of polyureas, or such polyureas are the major constituent. As described above, the microcapsule of the present embodiment does not use the melamine resin, which requires the use of formaldehyde, as a main constituent component of the wall material, and thus has high safety.
In the microcapsule of the present embodiment, the amount of the insect repellent contained therein is increased by selecting the polyurea in the specific range as described above.

<Wall materials, wall material components>
The wall material component (constituent component of the wall material) is a polycondensate of an isocyanate compound and an amine compound, and is an oligomer or a polymer (polyurea).
The wall material component has a film forming ability.
The wall material encloses an insect repellent as a core substance to form a microcapsule.

The thickness of the film or layer of the wall material is not particularly limited and may be, for example, 50 to 1000 nm.

[Isocyanate compound]
In this embodiment, the isocyanate compound contains a polymeric MDI and the diisocyanate-modified product.
The isocyanate compound may be mainly composed of the polymeric MDI and the modified diisocyanate, and may contain only the polymeric MDI and the modified diisocyanate, and within a range that does not impair the effects of the present invention, the polymeric MDI and the modified diisocyanate are included. Body and other isocyanates that do not correspond to any of these and have two or more isocyanate groups in one molecule (in this specification, may be abbreviated as “other isocyanate”) , May be included.
When only the polymeric MDI and the modified diisocyanate are used as the isocyanate compound, the wall material component is a structural unit derived from the isocyanate compound, and a structural unit derived from the polymeric MDI and a structural unit derived from the modified diisocyanate. And have only. On the other hand, when the polymeric compound MDI, the diisocyanate modified product, and the other isocyanate are used as the isocyanate compound, the wall material component has a structural unit derived from the polymeric compound MDI as a structural unit derived from the isocyanate compound, and It has a constitutional unit derived from a modified diisocyanate and a constitutional unit derived from the other isocyanate.

The polymer MDI and the modified diisocyanate form the wall material component that constitutes the microcapsule by a polycondensation reaction with the amine compound.
That is, more specifically, the wall material component has both a polycondensation structure of a polymeric MDI and an amine compound and a polycondensation structure of a diisocyanate modified product and an amine compound.
When the other isocyanate is used, the other isocyanate may form the wall material component by a polycondensation reaction with an amine compound. Therefore, the wall material component is the above-mentioned two types of polycondensation. In addition to the structure, it may have a polycondensation structure of the other isocyanate and amine compound. However, also in this case, the main component of the wall material component is the polycondensation structure of the polymeric MDI and the amine compound, and the polycondensation structure of the diisocyanate modified product and the amine compound.

(Polymeric MDI)
The polymeric MDI is represented by the following general formula (P1).

(In the formula, n is an integer of 0 or more.)

In general formula (P1), n may be an integer of 0 or more, and may be 0 to 100, for example.

The NCO content of the polymeric MDI can be appropriately adjusted, but is preferably 30 to 32% by mass, and more preferably 30.5 to 32% by mass.

The polymeric MDI is liquid at room temperature, and its viscosity at 25° C. is not particularly limited, but it is preferably 150 to 250 mPa·s.
In addition, in this specification, "normal temperature" means a temperature at which it is not particularly cooled or heated, that is, a normal temperature, and examples thereof include a temperature of 15 to 25°C.

There are plural types of polymeric MDI depending on the number of n.
The polymeric MDI used in forming the wall material component (in other words, the structural unit derived from the polymeric MDI contained in the wall material component) may be only one kind, or two or more kinds, or two or more kinds. If so, the combination and ratio thereof can be arbitrarily selected.

(Diisocyanate modified product)
The NCO content of the diisocyanate-modified product is 20% by mass or more.
The NCO content of the modified diisocyanate may be, for example, 22% by mass or more and 24% by mass or more in that microcapsules containing a large amount of the insect repellent can be produced more stably. ..

The upper limit of the NCO content of the diisocyanate-modified product is not particularly limited. For example, the NCO content of the diisocyanate-modified product may be 28% by mass or less in that microcapsules can be produced more stably.

The NCO content of the diisocyanate-modified product can be appropriately adjusted within a range set by any combination of the above-mentioned lower limit value and upper limit value. For example, in one embodiment, the NCO content may be any of 20 to 28% by mass, 22 to 28% by mass, and 24 to 28% by mass.

The diisocyanate-modified product is not particularly limited as long as its NCO content is 20% by mass or more.
The modified diisocyanate may be a modified product of an aliphatic diisocyanate or a modified product of an aromatic diisocyanate.
In the present specification, the “aliphatic diisocyanate” means a diisocyanate having an aliphatic group and not an aromatic group. Further, the "aromatic diisocyanate" has an aromatic group, and a diisocyanate having no aliphatic group, or a diisocyanate having both an aromatic group and an aliphatic group, that is, a diisocyanate having at least an aromatic group, Means

The aliphatic group in the aliphatic diisocyanate may be linear, branched or cyclic.
In the present specification, a cyclic aliphatic group may be referred to as an “aliphatic cyclic group”. The cyclic aliphatic group (aliphatic cyclic group) has a cyclic structure and may not have a chain structure (that is, a linear or branched chain structure), or a cyclic structure and a chain structure. It may have both structures, that is, at least a cyclic structure. The aliphatic cyclic group may be either monocyclic or polycyclic.
The aromatic group in the aromatic diisocyanate may be either monocyclic or polycyclic.

The modified diisocyanate is preferably an aliphatic diisocyanate modified product, and more preferably an aliphatic diisocyanate modified product having a linear aliphatic group.
Examples of such diisocyanate modified products include pentamethylene diisocyanate (sometimes abbreviated as "PDI" in this specification) modified product, hexamethylene diisocyanate (abbreviated as "HDI" in this specification). Modified) and the like.

Examples of the modified diisocyanate include a biuret modified product of diisocyanate, an isocyanurate modified product, and a trimethylolpropane adduct modified product (in the present specification, sometimes referred to as "TMP adduct modified product" or "TMP adduct product"). ), modified allophanate, and the like.
In addition, in this specification, for example, a “diisocyanate-biuret modified product” may be referred to as a “diisocyanate-biuret modified product”. The same applies to the other modified diisocyanates.

More specifically, examples of the diisocyanate-modified product include PDI isocyanurate-modified products, HDI biuret-modified products, and HDI isocyanurate-modified products.

The diisocyanate-modified product used in forming the wall material component (in other words, the structural unit derived from the diisocyanate-modified product contained in the wall material component) may be only one kind, or may be two or more kinds. When there are two or more kinds, their combination and ratio can be arbitrarily selected.

The diisocyanate-modified product used when forming the wall material component is preferably one or more selected from the group consisting of a PDI-modified product and an HDI-modified product, and is preferably a PDI isocyanurate-modified product or HDI-biuret-modified product. And one or more selected from the group consisting of HDI and isocyanurate-modified HDI.
In other words, the wall material component is, as the structural unit derived from the diisocyanate modified product, one or more selected from the group consisting of a structural unit derived from a PDI modified product and a structural unit derived from an HDI modified product. And a structural unit derived from a modified PDI isocyanurate, a structural unit derived from a modified HDI biuret, and a structural unit derived from a modified HDI isocyanurate, one selected from the group consisting of Or, it is more preferable to have two or more kinds.

(Other isocyanate)
The other isocyanate is not particularly limited as long as it has two or more isocyanate groups in one molecule and does not correspond to any of the polymeric MDI and the diisocyanate modified product.

In the wall material component, the ratio of the number of structural units derived from the other isocyanate to the total number of structural units derived from the polymeric MDI, structural units derived from the diisocyanate modified product, and structural units derived from the other isocyanate. ([Number of constituent units derived from the other isocyanate in the wall material component]/([Number of constituent units derived from polymeric MDI in the wall material component]+[Structural unit derived from the modified diisocyanate in the wall material component] Number]+[the number of structural units derived from the other isocyanate in the wall material component]×100) is preferably 10% or less, more preferably 5% or less, and 3% or less. More preferably, it is particularly preferably 1% or less, and when the ratio is not more than the upper limit value, microcapsules containing a larger amount of the insect repellent contained therein can be obtained.

[Amine compound]
The amine compound is not particularly limited as long as it has two or more amino groups in its molecule.
In the present specification, unless otherwise specified, the mere description of “amine compound” means such a compound having two or more amino groups.

The number of amino groups in the molecule of the amine compound is not particularly limited as long as it is 2 or more, but is preferably 2 to 6, more preferably 2 to 5, and 2 to It is more preferably 4, and particularly preferably 2 or 3.

The amine compound preferably has neither an isocyanate group nor a hydroxyl group, and more preferably has neither an isocyanate group nor a hydroxyl group.

The amine compound is preferably an organic polyamine compound.
The organic polyvalent amine compound may be linear, branched or cyclic, but is preferably linear or branched.

As preferred by the organic polyvalent amine compound, for example, aliphatic polyvalent amine compound having two or more hydrogen atoms of the aliphatic hydrocarbon (-H) is substituted with an amino group (-NH ₂₎ Structure NH-substituted aliphatic polyvalent having a structure in which one or more methylene groups (—CH ₂ —) of the aliphatic polyvalent amine compound are substituted with a group represented by the formula “—NH—” Examples thereof include amine compounds.

In the aliphatic polyvalent amine compound, the bonding position of the amino group is not particularly limited, and for example, it may be bonded to a carbon atom at the terminal portion of the main chain or side chain, or the non-terminal of the main chain or side chain. It may be bonded to some carbon atoms.
In the aliphatic polyvalent amine compound, it is preferable that two or more amino groups are not bonded to the same carbon atom.
In the present specification, the “main chain” means the one having the largest number of atoms forming the chain skeleton among the continuous chain skeletons present in the molecule. The “side chain” means one of the chain skeletons of one connection existing in the molecule, which does not correspond to the main chain.

The aliphatic polyvalent amine compound is preferably one in which an amino group is bonded to carbon atoms at least at one or both ends of the main chain, and an amino group is bonded to at least carbon atoms at both ends of the main chain. Are preferred, and examples thereof include an aliphatic diamine compound in which an amino group is bonded to carbon atoms at both ends of the main chain.

Preferred examples of the aliphatic polyvalent amine compound include 1,3-diaminopropane (NH ₂ —CH ₂ CH ₂ CH ₂ —NH ₂ ).

In the NH-substituted aliphatic polyvalent amine compound, the position of the methylene group substituted with the group represented by the formula "-NH-" is not particularly limited, but is adjacent to the carbon atom to which the amino group is bonded. It is preferably a methylene group which is not present.
In the NH-substituted aliphatic polyvalent amine compound, the number of methylene groups substituted with a group represented by the formula "-NH-" varies depending on the carbon number of the amine compound, and for example, 1 to 4 , 1 to 3, or 1 to 2 may be used.

As preferred by the NH substituted aliphatic polyvalent amine compound such as diethylenetriamine _{(NH 2 -CH 2 CH 2 -NH} -CH 2 CH 2 -NH 2), N, N'- bis (3-aminopropyl) ethylenediamine _{(NH 2 -CH 2 CH 2 CH} 2 -NH-CH 2 CH 2 -NH-CH 2 CH 2 CH 2 -NH 2) , and the like.

The amine compound used in forming the wall material component (in other words, the structural unit derived from the amine compound contained in the wall material component) may be only one kind, or may be two or more kinds. When there are more than one species, their combination and ratio can be arbitrarily selected.

The wall material component may include only a polycondensate of the isocyanate compound and an amine compound (polyurea), and within the range not impairing the effect of the present invention, the polycondensate and other Either or both of the oligomer and the polymer may be contained.

Each of the other oligomers and polymers contained in the wall material component may be only one kind, or may be two or more kinds, and in the case of two or more kinds, their combination and ratio are: It can be arbitrarily selected.

In the microcapsule, the ratio of the total content of the other oligomer and polymer in the wall material component to the total mass of the wall material component ([[total content of the other oligomer and polymer in the wall material component in the microcapsule [Amount (parts by mass)]/[total mass (parts by mass) of wall material components in microcapsules]×100) is preferably 5 mass% or less, more preferably 3 mass% or less, 1 It is particularly preferable that the content is not more than mass %.
In other words, in the microcapsule, the ratio of the content of the polycondensate in the wall material component to the total mass of the wall material component ([content of the polycondensate in the wall material component in the microcapsule (mass Part)]/[total mass (parts by mass) of the wall material component in the microcapsules]×100) is preferably 95% by mass or more, more preferably 97% by mass or more, and 99% by mass or more. Is particularly preferable.
When the ratio of these is within such a range, microcapsules containing a larger amount of the insect repellent included can be obtained.

<insect repellent>
The insect repellent can be arbitrarily selected according to the purpose and is not particularly limited.
The amount of the insect repellent dissolved in 1 L of water at any temperature of 15 to 25° C. is preferably 15 g or less, for example.

The insect repellent is preferably liquid at room temperature.

Examples of the insect repellent include N,N-diethyl-3-methylbenzamide (also known as N,N-diethyl-m-toluamide, DEET), 1-(1-methylpropoxycarbonyl)-2-(2-hydroxy). Ethyl)piperidine (alias: ikaridin) and the like.

In the microcapsule, the insect repellent contained in the wall material may be only one kind, or two or more kinds, and in the case of two or more kinds, their combination and ratio are , Can be arbitrarily selected.

The average particle size of the microcapsules is not particularly limited, but is preferably 3 μm or more, more preferably 4 μm or more, further preferably 5 μm or more, for example, 8 μm or more, and 10 μm or more. May be The microcapsules having the average particle diameter of not less than the lower limit value are advantageous in that the amount of the insect repellent contained therein is larger.

The upper limit of the average particle size of the microcapsules is not particularly limited. For example, the microcapsules having the average particle diameter of 16 μm or less can be manufactured more easily.

The average particle diameter of the microcapsules can be appropriately adjusted within the range set by any combination of the above lower limit and upper limit. For example, in one embodiment, the average particle size of the microcapsules is preferably 3 to 16 μm, more preferably 4 to 16 μm, even more preferably 5 to 16 μm, for example 8 to 16 μm. And 10 to 16 μm.

In the present specification, the “average particle diameter” means the median diameter of the volume particle size distribution of the particles, which is measured using a particle size distribution meter, unless otherwise specified.

The degree of inclusion of the insect repellent in the microcapsules can be determined by, for example, the inclusion rate of the insect repellent in the microcapsules calculated by the following formula.
[Encapsulation rate of insect repellent in microcapsules (% by mass)] = [Content of insect repellent in microcapsules (parts by mass)]/[Amount of insect repellent used in manufacturing microcapsules (parts by mass)] x 100

The inclusion rate of the insect repellent in the microcapsules may be, for example, preferably 75% by mass or more, more preferably 80% by mass or more, and 82.5% by mass or more, and 85% by mass or more. It may be.
The encapsulation rate of the insect repellent in the microcapsules may be, for example, preferably 90% by mass or more, more preferably 94% by mass or more.

The upper limit of the inclusion rate is 100% by mass. For example, the microcapsule having the encapsulation rate of 98% by mass or less can be more easily manufactured, and the encapsulation rate may be 93% by mass or less.

Usually, in a microcapsule containing a large amount of core substance, its shape is close to a true sphere, and its particle diameter (average particle diameter) is relatively large. The microcapsule of the present embodiment has such characteristics and contains a large amount of the insect repellent which is the core substance.
For example, the shape of the microcapsules can be observed by using a scanning electron microscope (SEM).

<<Method of manufacturing microcapsules>>
The microcapsules can be produced by subjecting the isocyanate compound and the amine compound to a polycondensation reaction in the presence of an insect repellent.

In the present embodiment, a microcapsule containing a large amount of an insect repellent is obtained by selecting a combination of the polymeric MDI and the modified diisocyanate as the reaction target of the amine compound, that is, the isocyanate compound. ..
Polymeric MDI has a relatively high reactivity with an amine compound and can be used for forming a wall material component, but it easily reacts with an unintended component, for example, a compound having a hydroxyl group (—OH) or the like. easy. Examples of such compounds include emulsifiers. Therefore, when the majority of the isocyanate compound is polymeric MDI or when the isocyanate compound is polymeric MDI alone, side reactions during the polycondensation reaction are not suppressed, and the target microcapsules are hardly or not obtained at all.
On the other hand, in the present embodiment, in addition to the polymeric MDI, the reactivity of the isocyanate compound and the amine compound is adjusted by using the modified diisocyanate having lower reactivity than the polymeric MDI, and as a result, It is speculated that the target microcapsules can be obtained in high yield.

At the time of polycondensation reaction, you may use the other component which does not correspond to any of the said isocyanate compound (Polymeric MDI, the said diisocyanate modified body, the said other isocyanate), and the said amine compound.
Examples of the other components include solvents and emulsifiers.
For example, polycondensation can be carried out as interfacial polycondensation by carrying out the polycondensation reaction in the coexistence of water and the hydrophobic component.

Among the other components, examples of the solvent include water and organic solvents.
The organic solvent may be either a hydrophilic solvent or a hydrophobic solvent, but is preferably a hydrophobic solvent.
Examples of the hydrophobic solvent include alcohols, amides, nitriles, ketones, esters, ethers, hydrocarbons, halogenated hydrocarbons, phenols (compounds having a phenolic hydroxyl group), carbon sulfide, carboxylic acid and the like.

Among the above-mentioned other components, known emulsifiers can be mentioned.
Examples of the emulsifier include polyvinyl alcohol, carboxymethyl cellulose, ethyl cellulose, methyl cellulose, casein, gum arabic, gelatin, funnel oil, sodium benzenesulfonate, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, polyoxyethylene sulfate, Examples thereof include ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, and poly(meth)acrylic acid.
In this specification, the term “(meth)acrylic acid” includes both “acrylic acid” and “methacrylic acid”.

The emulsifier is preferably polyvinyl alcohol from the viewpoint that the emulsified state of the reaction solution during the polycondensation reaction is better and the microcapsules can be produced more easily.

The insect repellent used in the polycondensation reaction, the polymeric MDI, the diisocyanate modified product, the other isocyanate, the amine compound, and the other component may each be only one kind, or two or more kinds. It may be present, and in the case of two or more kinds, their combination and ratio can be arbitrarily selected.

During the polycondensation reaction, the total amount of the polymeric MDI and the modified diisocyanate used is, for example, preferably 20 to 55 parts by mass, more preferably 25 to 50 parts by mass, relative to 100 parts by mass of the insect repellent used. More preferably, it may be 30 to 45 parts by mass. When the total amount used is at least the lower limit value, microcapsules containing a large amount of the insect repellent can be produced more stably. When the total amount used is less than or equal to the upper limit value, it is possible to more stably produce microcapsules containing a large amount of insect repellent while suppressing excessive use of the polymeric MDI or the diisocyanate-modified product.
Further, in the polycondensation reaction, the total amount of the polymeric MDI and the modified diisocyanate is, for example, preferably 20 to 60 parts by mass, more preferably 25 to 55 parts by mass, relative to 100 parts by mass of the insect repellent. It may be part by mass. When the upper limit of the total amount used is relatively large, microcapsules containing a larger amount of the insect repellent can be produced.

During the polycondensation reaction, the ratio of the amount of the modified diisocyanate used to the amount of the polymeric MDI used is preferably 100 to 450% by mass, more preferably 140 to 400% by mass, and 180 to It is more preferably 350% by mass. When the ratio is within such a range, microcapsules containing a large amount of the insect repellent can be more stably produced.

In the polycondensation reaction, the total amount of the polymeric MDI and the diisocyanate modified product and the amount of the amine compound used are as follows: [moles of amino group in amine compound]: [polymeric MDI and diisocyanate modified product] The total molar number of isocyanate groups] is preferably 10:90 to 60:40, and more preferably 20:80 to 40:60. When the number of moles of amino groups in the amine compound is set to be smaller than the total number of moles of isocyanate groups in the polymeric MDI and the modified diisocyanate, higher quality microcapsules can be obtained.

The amount of the other component used in the polycondensation reaction can be appropriately adjusted depending on the type.
For example, when the other component is a solvent, the amount of the other component (solvent) used is the total amount of the insect repellent, the polymeric MDI, the modified diisocyanate, the other isocyanate, and the amine compound. The amount is preferably 100 to 250 parts by mass with respect to 100 parts by mass, and may be, for example, 100 to 210 parts by mass or 100 to 170 parts by mass.

For example, when the other component is an emulsifier, the amount of the emulsifier used is 4 to 100 parts by mass based on 100 parts by mass of the total amount of the polymeric MDI, the diisocyanate modified product, the other isocyanate, and the amine compound. The amount is preferably 25 parts by mass, more preferably 7 to 20 parts by mass, and may be, for example, 10 to 15 parts by mass. When the amount used is at least the lower limit, the emulsified state of the reaction liquid during the polycondensation reaction becomes better. When the amount used is equal to or less than the upper limit value, excessive use of the emulsifier is suppressed.

For example, when the other component is a component that does not correspond to any of the solvent and the emulsifier, the amount of the other component used is such that the insect repellent, the polymeric MDI, the modified diisocyanate, and the other It is preferably 10 parts by mass or less, for example, 5 parts by mass or less, and 1 part by mass or less, based on 100 parts by mass in total of the isocyanate and the amine compound.

The temperature at which the polycondensation reaction is performed (that is, the reaction temperature) is not particularly limited, but is preferably 60 to 110°C, more preferably 65 to 100°C, and particularly preferably 70 to 90°C. preferable.

The time for carrying out the polycondensation reaction (that is, the reaction time) is preferably 0.5 to 5 hours, more preferably 1 to 4 hours, and particularly preferably 1.5 to 3 hours.

After the polycondensation reaction, for example, the microcapsules are obtained as a dispersion such as an aqueous dispersion.

The obtained microcapsules may be used as it is for the intended purpose, or may be subjected to post-treatment, purification, etc. by a known method as necessary, and then used for the intended purpose. It may be removed and then used for the intended purpose.

When the solvent other than water is used during the polycondensation reaction, in the obtained microcapsules, the wall material may include this solvent in addition to the insect repellent. In addition to the insect repellent and the solvent, the wall material may include other components depending on the conditions of the polycondensation reaction.

The solvent and other components included in the wall material may be only one kind, or may be two or more kinds, and in the case of two or more kinds, their combination and ratio are: It can be arbitrarily selected.

The amount of the insect repellent, the solvent, and other components included in the microcapsules can be adjusted depending on the production conditions of the microcapsules.

The rotation speed of the stirring means during the polycondensation reaction (in other words, the stirring speed of the reaction solution) may be, for example, 300 to 900 rpm or 400 to 700 rpm.
For example, when the amount of the insect repellent used in the polycondensation reaction is 50 to 200 g, such a stirring speed is particularly suitable. However, the amount of insect repellent used is not limited to these.

As an example of a more specific method for producing microcapsules, for example, a second solution containing polymeric MDI, the diisocyanate modified product, and an insect repellent is added to a first solution containing water and an emulsifier. Then, a step of obtaining an emulsion (which may be abbreviated as “emulsification step” in the present specification) and a third solution containing water and an amine compound are added to the emulsion to carry out a polycondensation reaction. And a production method (in the present specification, may be referred to as “production method (I)”) having a step of performing (sometimes abbreviated as “polycondensation step” in the present specification). .. However, the manufacturing method of the microcapsules is not limited to this manufacturing method (I).
The manufacturing method (I) will be described below.

<Emulsification process>
In the emulsification step of the production method (I), the second solution is added to the first solution to obtain an emulsion.

[First solution]
The first solution contains water and an emulsifier, and, in a range that does not impair the effects of the present invention, optionally contains water and the other component that does not correspond to any of the emulsifiers. May be.

The emulsifier and other components used in the preparation of the first solution may each be only one kind, or may be two or more kinds, and in the case of two or more kinds, their combination and ratio are: It can be arbitrarily selected.

The ratio of the content of the emulsifier to the total mass of the first solution (that is, the concentration of the emulsifier of the first solution) is not particularly limited, but is preferably 1 to 15% by mass, and 2 to 8% by mass. Is more preferable.

When the first solution contains the other component, the content of the other component can be appropriately adjusted depending on the purpose.

The first solution is obtained by blending water, an emulsifier, and, if necessary, the above-mentioned other components.
The first solution is preferably prepared by adding an emulsifier to water. When the other component is used, the addition timing and the addition target can be appropriately adjusted depending on the type of the other component.
At the time of preparing the first solution, for example, after all components are mixed, the mixture is heated and stirred at preferably 80 to 100° C., preferably 0.5 to 3 hours, and then cooled to room temperature such as 27° C. or lower. Thus, the first solution may be prepared.

[Second solution]
The second solution contains a polymeric MDI, the diisocyanate modified product, an insect repellent, and, if necessary, the other isocyanate, within a range that does not impair the effects of the present invention. The other component which does not correspond to any of the components (polymeric MDI, the modified diisocyanate, the insect repellent, the other isocyanate) may be contained.

The polymeric MDI, the diisocyanate modified product, the insect repellent, the other isocyanate, and the other components used in the preparation of the second solution may each be only one kind or may be two or more kinds. When there are two or more kinds, their combination and ratio can be arbitrarily selected.

In the production method (I), in the second solution, the total content of the polymeric MDI and the modified diisocyanate is, for example, preferably 20 to 55 parts by mass, more preferably 100 parts by mass of the content of the insect repellent. May be 25 to 50 parts by mass, more preferably 30 to 45 parts by mass.
In the production method (I), the total content of the polymeric MDI and the modified diisocyanate in the second solution is, for example, preferably 20 to 60 parts by mass, relative to 100 parts by mass of the insect repellent content. More preferably, it may be 25 to 55 parts by mass.

In the production method (I), the ratio of the content of the modified diisocyanate to the content of the polymeric MDI in the second solution is preferably 100 to 450% by mass, and 140 to 400% by mass. Is more preferable, and 180 to 350 mass% is further preferable.

Examples of the other component in the second solution include a solvent.
By using the solvent, the solubility of the contained component in the second solution can be adjusted.
Examples of the solvent in the second solution include water and organic solvents, and the organic solvent is the same as that described above.

When the second solution contains the other isocyanate or the other component, the content of these components can be appropriately adjusted according to the purpose.

The second solution is obtained by blending the polymeric MDI, the diisocyanate modified product, the insect repellent, the other isocyanate as necessary, and the other component as necessary.
When the insect repellent is liquid at room temperature, the second solution is an insect repellent, a polymeric MDI, the diisocyanate modified product, and optionally the other isocyanate, and optionally other components, It is preferable to prepare by adding.
When preparing the second solution, for example, from the mixing of the raw materials (polymeric MDI, the above-mentioned diisocyanate modified product, insect repellent, other isocyanates, other components) to stirring after mixing all the components, preferably 15 It can be done at ~28°C. The stirring time after mixing all the components may be, for example, 1 to 60 minutes.

In the emulsification step, when the second solution is added to the first solution, the second solution may be added all at once or may be added dropwise.

In the emulsification step, for example, the initial stage of adding the second solution to the first solution to the stirring after the addition can be performed preferably at 15 to 28°C. The stirring time after adding the second solution to the first solution may be, for example, 1 to 60 minutes.

In the emulsification step, by adding the second solution to the first solution, and stirring the resulting mixed solution, when the emulsion is obtained, by adjusting the stirring speed of the mixed solution, The particle size (average particle size) of the capsule can be adjusted. More specifically, the slower the stirring speed, the larger the particle size of the microcapsules, and the faster the stirring speed, the smaller the particle size of the microcapsules.

The stirring speed of the mixed liquid (in other words, the rotation speed of the stirring means) when obtaining the emulsion may be, for example, 300 to 1000 rpm or 400 to 800 rpm.
For example, when the amount of the insect repellent used during emulsification is 50 to 200 g, such a stirring speed is particularly suitable. However, the amount of insect repellent used is not limited to these.

<Polycondensation process>
In the polycondensation step, the polycondensation reaction is performed by adding the third solution to the emulsion obtained in the emulsification step.

[Third solution]
The third solution contains water and an amine compound, and may contain other components other than water as needed, as long as the effects of the present invention are not impaired.

The amine compound and other components used in the preparation of the third solution may be only one kind, or may be two or more kinds, and in the case of two or more kinds, their combination and ratio are , Can be arbitrarily selected.

The ratio of the content of the amine compound to the total mass of the third solution (that is, the concentration of the amine compound in the third solution) is not particularly limited, but is preferably 5 to 40% by mass, and 10 to 30% by mass. More preferably, it is mass %.

In the production method (I), the amount of the emulsifier in the first solution, the amount of the polymeric MDI and the modified diisocyanate in the second solution, and the amount of the amine compound in the third solution are described above. The amounts of the first solution, the second solution, and the third solution to be used may be adjusted so as to be related to each other.

When the third solution contains the other component, the content of the other component can be appropriately adjusted according to the purpose.

The third solution is obtained by blending water, an amine compound and, if necessary, the above-mentioned other components.
The third solution may be prepared, for example, by adding water to the amine compound or may be prepared by adding the amine compound to water. When the other component is used, the addition timing and the addition target can be appropriately adjusted depending on the type of the other component.
When preparing the third solution, the third solution may be prepared, for example, by mixing all the components and then stirring at 15 to 28° C., preferably for 1 to 60 minutes.

In the polycondensation step, when the third solution is added to the emulsion, the third solution may be added all at once or may be added dropwise.

In the production method (I), in the polycondensation step, the reaction temperature, the reaction time, and the stirring rate of the reaction solution are the reaction temperature, the reaction time, and the reaction solution when the polycondensation reaction described above is performed. It is preferable to set the stirring speed.

In the production method (I), the microcapsule is obtained as an aqueous dispersion by performing the polycondensation step.

The microcapsule of the present embodiment has a sustained release property of gradually releasing the encapsulated insect repellent to the outside with the passage of time regardless of the manufacturing method. Therefore, the microcapsule can sustain the action of the insect repellent for a long period of time.

The microcapsules are suitable as an insect repellent, for example.
For example, a liquid insect repellent can be obtained by preparing a liquid composition containing the microcapsules or using the product of the polycondensation reaction obtained by the above-mentioned production method as it is. Furthermore, a layered (for example, film-shaped) insect repellent can be obtained by applying these liquid insect repellents and drying.
Moreover, a solid insect repellent such as a sheet is obtained by preparing a resin composition containing the microcapsules and molding the resin composition.

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the examples described below.

<Insect repellent, isocyanate compound, amine compound>
The insect repellents, isocyanate compounds and amine compounds used in the production of microcapsules are shown below.

[Example 1]
<<Production of microcapsules>>
To the distilled water (174.4 g), add polyvinyl alcohol ("JP-24" manufactured by Nippon Vine & Poval Co., Ltd.) (5.6 g), stir at 90°C for 1 hour to prepare a solution, and cool it to 25°C. By doing so, an aqueous polyvinyl alcohol solution (corresponding to the first solution) was obtained.
Separately, the isocyanate (b)-1 (10 g) and the diisocyanate modified product (c)-1 (25 g) were added to the insect repellent (a)-1 (100 g), and these were stirred at 25° C. A mixed solution (corresponding to the second solution) in which all the components were dissolved was obtained.
Separately, distilled water (30 g) was added to diethylenetriamine (7.5 g), and the mixture was stirred at 25° C. to obtain a diethylenetriamine aqueous solution (corresponding to the third solution).
The total amount of the mixed solution was added to the total amount of the polyvinyl alcohol aqueous solution, and the anchor blade was rotated for 3 minutes at 25° C. and a rotation speed of 700 rpm to stir the mixture to obtain an emulsion (corresponding to the emulsification step). ..
Interfacial polycondensation was performed by adding the total amount of the diethylenetriamine aqueous solution to the total amount of the obtained emulsion and rotating the anchor blade at 80° C. at a rotation speed of 500 rpm for 2 hours and stirring the reaction liquid ( Corresponding to the polycondensation step).
From the above, a polycondensation product of diethylenetriamine and modified MDI and HDI-biuret was used as the wall material component, and microcapsules containing DEET as the core substance (insect repellent) in the wall material were obtained as an aqueous dispersion. It was

<<Evaluation of microcapsules>>
<Average particle size>
The microcapsule aqueous dispersion obtained above was coated on a wood free paper and dried at 105° C. for 90 seconds. Then, using a scanning electron microscope (manufactured by JEOL Ltd.), the coated and dried portions were observed at a magnification of 2000 times to confirm that the desired microcapsules were obtained. Imaging data of the microcapsule acquired at this time is shown in FIG.
Further, the average particle size of the obtained microcapsules was measured using an electrical detection zone type particle size distribution meter (“Multisizer 3” manufactured by Beckman Coulter, Inc.). The results are shown in Table 5.

<Encapsulation rate of insect repellent>
Distilled water was added to the microcapsule aqueous dispersion (1 g) obtained above to make a total amount of 100 g to obtain a diluted solution.
The obtained diluted solution was filtered using a membrane filter having a pore size of 0.2 μm, and the microcapsules were separated by filtration.
The obtained filtrate was analyzed by high performance liquid chromatography (HPLC) to detect a peak corresponding to the insect repellent (a)-1.
Separately, using the same measuring device, a plurality of insect repellent (a)-1 solutions having known concentrations are analyzed by HPLC, and the concentration of the insect repellent (a)-1 and the insect repellent (a)-1 are analyzed. The intensity of the peak corresponding to 1 was obtained, and a calibration curve for the insect repellent (a)-1 was prepared from these data.
The amount of insect repellent (a)-1 in the filtrate was calculated using the above analytical data of the filtrate and this calibration curve, and from the amount of this insect repellent (a)-1 , The total amount of the non-encapsulated insect repellent (a)-1 in the microcapsule aqueous dispersion obtained above was calculated, and the value and the insect repellent (a)-1 at the time of interfacial polycondensation were calculated. The amount of the microcapsules included in the insect repellent was calculated from the amount used. Further, the encapsulation rate of the insect repellent in the microcapsules was calculated from the encapsulation amount using the above formula. The results are shown in Table 5.

<<Production and evaluation of microcapsules>>
[Examples 2 to 3]
Microcapsules were produced and evaluated in the same manner as in Example 1 except that the kinds of amine compounds were changed as shown in Table 5. The results are shown in Table 5.

[Example 4]
Microcapsules were produced and evaluated in the same manner as in Example 1 except that the rotation speed of the anchor blade when obtaining the emulsion (when performing the emulsification step) was set to 500 rpm instead of 700 rpm. The results are shown in Table 5.

[Examples 5 to 6]
Microcapsules were produced in the same manner as in Example 1 except that both the amount of isocyanate (b)-1 and the amount of amine compound (d)-1 were set as shown in Table 5. Was manufactured and evaluated. The results are shown in Table 5.

[Example 7]
By the same method as in Example 1, except that both the blending amount of the diisocyanate-modified product (c)-1 and the blending amount of the amine compound (d)-1 were as shown in Table 5, Microcapsules were manufactured and evaluated. The results are shown in Table 5.

[Examples 8 to 9]
Microcapsules were produced and evaluated in the same manner as in Example 1 except that the types of the modified diisocyanate were changed as shown in Table 5. The results are shown in Table 5.

[Example 10]
Microcapsules were produced and evaluated in the same manner as in Example 1 except that the insect repellent (a)-2 was used in place of the insect repellent (a)-1. The results are shown in Table 5.

[Example 11]
Example 1 except that the compounding amount of the isocyanate (b)-1, the type and compounding amount of the diisocyanate modified product, and the compounding amount of the amine compound (d)-1 were all as shown in Table 5. Microcapsules were produced and evaluated in the same manner as in the above. The results are shown in Table 5.

[Example 12]
All of the types of insect repellent, the amount of isocyanate (b)-1, the amount and amount of modified diisocyanate, and the amount of amine compound (d)-1 were set as shown in Table 5. Microcapsules were produced and evaluated in the same manner as in Example 1 except for the above points. The results are shown in Table 5.

[Comparative Example 1]
Microcapsules were prepared in the same manner as in Example 1 except that the compounding amount of isocyanate (b)-1 was 35 g instead of 10 g, and that diisocyanate-modified product (c)-1 was not used. Attempted to manufacture and evaluate. That is, in this comparative example, the isocyanate (b)-1 (35 g) was added to the insect repellent (a)-1 (100 g) and the components were dissolved by stirring at 25°C. After obtaining the mixed solution, an attempt was made to manufacture and evaluate microcapsules by the same method as in Example 1 except that the total amount of the mixed solution was added to the total amount of the polyvinyl alcohol aqueous solution. The results are shown in Table 5. In addition, at this time, the imaging data of the product obtained by the same method as in the case of the first embodiment is shown in FIG. In Table 5, "-" in the column of "raw material for producing microcapsules" means that the component is not blended. In addition, the description of "-" in the column of "evaluation result of microcapsule" means that the item has not been evaluated.

[Comparative example 2]
Microcapsules were prepared in the same manner as in Example 1, except that the compounding amount of the diisocyanate-modified product (c)-1 was 40 g instead of 25 g, and that the isocyanate (b)-1 was not used. Attempted to manufacture and evaluate. That is, in this comparative example, the diisocyanate modified product (c)-1 (40 g) was added to the insect repellent (a)-1 (100 g), and the components were dissolved by stirring at 25°C. After obtaining the mixed solution, the production and evaluation of microcapsules were tried in the same manner as in Example 1 except that the total amount of the mixed solution was added to the total amount of the polyvinyl alcohol aqueous solution. The results are shown in Table 5. Further, at this time, the imaging data of the product obtained by the same method as in the case of the first embodiment is shown in FIG.

[Comparative Example 3]
An attempt was made to produce and evaluate microcapsules by the same method as in Example 1 except that the diisocyanate modified product (c)-3 (15 g) was used instead of the isocyanate (b)-1 (10 g). .. In other words, in this comparative example, the isocyanate (b)-1 was not used, and the diisocyanate modified product (c)-3 (15 g) was used in combination with the diisocyanate modified product (c)-1 (25 g). The production and evaluation of microcapsules were tried by the same method as in Example 1 except for. The results are shown in Table 5.

[Comparative Example 4]
Production and evaluation of microcapsules were attempted by the same method as in Example 1 except that isocyanate (b)-2 was used instead of isocyanate (b)-1. The results are shown in Table 5.

[Comparative Example 5]
The production and evaluation of microcapsules were tried in the same manner as in Example 1 except that the diisocyanate-modified product (c)-1 was used in place of the diisocyanate-modified product (c)-1. The results are shown in Table 5.

[Reference Example 1]
Example 1 except that the compounding amount of the isocyanate (b)-1, the type and compounding amount of the diisocyanate modified product, and the compounding amount of the amine compound (d)-1 were all as shown in Table 5. The microcapsules were manufactured and evaluated by the same method as in the above. The results are shown in Table 5.

As is clear from the above results, in Examples 1 to 12, microcapsules having an insect repellent encapsulation rate of 80% by mass or more (80 to 98% by mass) and a large amount of insect repellent encapsulation were obtained. It was
As shown in FIG. 1, in Example 1, spherical microcapsules were stably obtained, the average particle diameter of the microcapsules was 7.5 μm, and the microcapsules were sufficiently large. Although not shown in the drawings, also in Examples 2 to 12, the same microcapsules as in Example 1 were obtained. In Examples 1 to 12, the average particle size of the microcapsules was 6.9 μm or more (6.9 to 13.8 μm).

In Examples 1 to 12, the wall material component of the microcapsules was polyurea, formaldehyde was not used during the production of the microcapsules, and microcapsules with high safety were obtained. Further, this wall material component was obtained by polycondensing a polymeric MDI and the above-mentioned diisocyanate modified product as an isocyanate compound, and these and an amine compound. The content of isocyanate groups in the diisocyanate-modified product is 20.7% by mass or more (20.7 to 25.0% by mass), and the content of isocyanate groups in the polymeric MDI is 31.3% by mass. there were.

In Examples 1 to 12, the total amount of use of the polymeric MDI and the modified diisocyanate (total amount of use) was 32.5 to 54.1 parts by weight per 100 parts by weight of the amount of insect repellent (the amount of use). there were.

Among them, in Examples 11 to 12, the encapsulation rate of the insect repellent was 95% by mass or more (95 to 98% by mass), and microcapsules having a remarkably large amount of entrapment of the insect repellent were obtained.
The total amount of use of the polymeric MDI and the modified diisocyanate (total amount of use) was 54.1 parts by weight in Examples 11 to 12 per 100 parts by weight of the insect repellent (the amount of use). 10 to 32.5 to 40 parts by mass, which is significantly higher in Examples 11 to 12, which means that the amount of the insect repellent included in the microcapsules of Examples 11 to 12 is remarkable. It was presumed to be the most common reason.

In Examples 1 to 12, aqueous dispersions of microcapsules having good properties were obtained after the polycondensation step.

On the other hand, in Comparative Examples 1 to 5, the intended spherical microcapsules could not be obtained. Therefore, it was not possible to determine the average particle size of the microcapsules. On the other hand, as a result of calculating the entrapment ratio of the product insect repellent by the same method as in Example 1, it was 65% by mass or less (28 to 65% by mass), and the entrapment amount of the insect repellent was also small.

In Comparative Example 1, as shown in FIG. 2, the wall material had an irregular shape and a gel shape. In Comparative Example 1, the diisocyanate modified product is not used, and therefore, the polycondensation reaction does not normally proceed during the formation of the wall material, and not only the polymeric MDI and the amine compound but also other components such as polyvinyl alcohol, It was estimated that the polycondensation reaction had occurred.

In Comparative Example 2, as shown in FIG. 3, some spherical products were recognized, and most of the wall materials had an irregular shape as in Comparative Example 1. In Comparative Example 2, since the polymeric MDI was not used, it was presumed that the polycondensation reaction did not proceed normally during the formation of the wall material, and the encapsulation did not proceed sufficiently.

In Comparative Example 3, two kinds of the diisocyanate modified products having different NCO contents were used in combination, but like the case of Comparative Example 2, the polymeric MDI was not used. Therefore, it was estimated that the polycondensation reaction did not proceed normally during the formation of the wall material, and the encapsulation did not proceed sufficiently.

In Comparative Example 4, the isocyanate and the diisocyanate-modified product were used in combination, but the isocyanate was not the polymeric MDI (the polymeric MDI was not used). Therefore, it was estimated that the polycondensation reaction did not proceed normally during the formation of the wall material, and the encapsulation did not proceed sufficiently.

In Comparative Example 5, the polymeric MDI and the isocyanate modified product were used in combination, but the isocyanate modified product was another diisocyanate modified product other than the diisocyanate modified product (the diisocyanate modified product was not used). Therefore, it was estimated that the polycondensation reaction did not proceed normally during the formation of the wall material, and the encapsulation did not proceed sufficiently.

In Reference Example 1, the reaction liquid gelled immediately after the start of the polycondensation reaction, and the encapsulation did not proceed. Therefore, it was not possible to determine the average particle size of the microcapsules and the entrapment rate of the product insect repellent.
In Reference Example 1, the polymeric MDI and the diisocyanate modified product were used in combination, but the total amount of the polymeric MDI and the diisocyanate modified product (total compounding amount) was 70 with respect to 100 parts by mass of the insect repellent (compounding amount). It was estimated that the cause of gelation was that the total amount used was too large.

INDUSTRIAL APPLICABILITY The present invention can be used as an insect repellent having a long-lasting insect repellent action.

Claims (2)

A polycondensate of an isocyanate compound and an amine compound is used as a constituent component of the wall material, and the wall material contains an insect repellent,
A microcapsule in which the isocyanate compound contains polymethylene polyphenyl polyisocyanate and a diisocyanate-modified product having an isocyanate group content of 20% by mass or more. The microcapsule according to claim 1, wherein the modified diisocyanate is one kind or two or more kinds selected from the group consisting of a modified pentamethylene diisocyanate and a modified hexamethylene diisocyanate.