Microcapsule, composition, and method for producing microcapsule

Abstract

To provide a microcapsule constituted by using a biodegradable material and having sufficient durability.SOLUTION: A microcapsule comprising a core substance encapsulated by a wall material, wherein a constituent component of the wall material is either one or both of polyurea and polyurethane, and the core substance is a lipophilic substance and a biodegradable resin having a melting point of 100 °C or lower and not corresponding to a polyol.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to microcapsules, compositions, and methods for making microcapsules. [Background technology]

[0002] In order to prolong the effectiveness of various chemicals such as insecticides, insect repellents, and fragrances, the chemicals are sometimes microencapsulated. For example, microcapsules in which a core substance, a fragrance, is encapsulated by a wall material are added to fabric softeners and are widely used.

[0003] On the other hand, marine pollution caused by microplastics has been increasing in recent years. For example, the wall material of microcapsules is usually made of plastic (synthetic resin), so the possibility that microcapsules could cause marine pollution has begun to be recognized as an issue. Therefore, studies are being conducted to construct part of the microcapsules from biodegradable materials.

[0004] Examples of microcapsules made using biodegradable materials include microcapsules whose wall material is biodegradable polycaprolactone (see Patent Document 1), microcapsules whose wall material is biodegradable polyurethane obtained by using polycaprolactone diol as a polyol compound and reacting it with a polyisocyanate compound (see Patent Documents 2 and 3), and microcapsules whose wall material is biodegradable polyurethane and biodegradable polyurea obtained by using polycaprolactone diol as a polyol compound and reacting it with a polyamine compound (see Patent Document 4). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-301357 [Patent Document 2] Japanese Patent Application Publication No. 9-173823 [Patent Document 3] International Publication No. 2020 / 195132 [Patent Document 4] Japanese Patent Application Laid-Open No. 2000-140617 Summary of the Invention [Problem to be solved by the invention]

[0006] However, although the microcapsules disclosed in Patent Documents 1 to 4 are constructed using biodegradable materials, the encapsulated core substance is easily released to the outside of the capsule in a short period of time, making it difficult to maintain the effect of the core substance for a long period of time, and there are problems in that the durability of the microcapsules is insufficient.

[0007] So far, we have taken the example of a microcapsule whose wall material is a biodegradable resin, but biodegradable materials can also be used for purposes other than wall materials. However, there are no known microcapsules made of biodegradable materials that are intended to improve their durability.

[0008] An object of the present invention is to provide a microcapsule that is made of a biodegradable material and has sufficient durability. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention employs the following configuration. [1] A microcapsule formed by encapsulating a core substance within a wall material, The wall material is made of either or both of polyurea and polyurethane, The microcapsules, wherein the core material is a lipophilic substance and a biodegradable resin that does not fall under the category of polyol and has a melting point of 100°C or less. [2] The microcapsules according to [1], wherein the polyurea is a polymer of a polyisocyanate compound and a polyamine compound derived from the polyisocyanate compound. [3] The microcapsules according to [1], wherein the polyurea is a polymer of a polyisocyanate compound and a chain polyamine compound. [4] The microcapsules according to any one of [1] to [3], wherein the lipophilic substance is one or more selected from the group consisting of essential oils and fragrances. [5] The microcapsules according to any one of [1] to [4], wherein the biodegradable resin is polycaprolactone.

[0010] [6] The polyisocyanate compound is an aliphatic polyisocyanate compound, The microcapsules according to [3], wherein the mass ratio of [the content (parts by mass) of the polyurea in the microcapsules]:[the content (parts by mass) of the biodegradable resin in the microcapsules] is 10:90 to 40:60. [7] The polyisocyanate compound is an aromatic polyisocyanate compound, The microcapsules according to [3], wherein the mass ratio of [the content (parts by mass) of the polyurea in the microcapsules]:[the content (parts by mass) of the biodegradable resin in the microcapsules] is 5:95 to 20:80. [8] The microcapsules according to [6] or [7], wherein the biodegradable resin is polycaprolactone.

[0011] [9] A composition containing the microcapsules according to any one of [1] to [8].

[10] A method for producing microcapsules, comprising the steps of: preparing an oil-based solution by mixing a lipophilic substance, a biodegradable resin that is not a polyol and has a melting point of 100°C or less, and a polyisocyanate compound; preparing an emulsion by mixing an emulsifier and the oil-based solution in the presence of water; and preparing microcapsules by carrying out a polymerization reaction between a polyamine compound and the polyisocyanate compound while heating the emulsion, wherein the polyamine compound is a polyamine compound generated from the polyisocyanate compound during or after the step of preparing the emulsion.

[11] A method for producing microcapsules, comprising the steps of: preparing an oil-based solution by mixing a lipophilic substance, a biodegradable resin that is not a polyol and has a melting point of 100°C or less, and a polyisocyanate compound; preparing an emulsion by mixing an emulsifier and the oil-based solution in the presence of water; and mixing the emulsion with a polyamine compound and carrying out a polymerization reaction while heating to produce microcapsules.

[0012]

[12] The method for producing microcapsules according to

[11] , wherein the polyamine compound is linear.

[13] The method for producing microcapsules according to any one of

[10] to

[12] , wherein the lipophilic substance is one or more selected from the group consisting of essential oils and fragrances.

[14] The method for producing microcapsules according to any one of

[10] to

[13] , wherein the biodegradable resin is polycaprolactone.

[15] The method for producing microcapsules according to any one of

[10] to

[14] , wherein the concentration of water in the reaction solution during the polymerization reaction is 62 mass % or less. [Effects of the Invention]

[0013] According to the present invention, there is provided a microcapsule that is made of a biodegradable material and has sufficient durability. [Brief explanation of the drawings]

[0014] [Figure 1] 1 shows optical microscope image data of a cross section of the microcapsules produced in Example 18. DETAILED DESCRIPTION OF THE INVENTION

[0015] <<Microcapsules>> A microcapsule according to one embodiment of the present invention is a microcapsule in which a core substance is encapsulated in a wall material, the constituent components of which are either or both of polyurea and polyurethane, and the core substance is a lipophilic substance and a biodegradable resin (sometimes simply referred to in this specification as "biodegradable resin") that does not fall under the category of polyol and has a melting point of 100°C or less. The microcapsules of this embodiment are constructed using the biodegradable resin. The wall material contains at least one of polyurea and polyurethane as a constituent component, and the biodegradable resin, in addition to the lipophilic substance, is encapsulated as a core substance. This configuration of the microcapsules of this embodiment prevents the lipophilic substance from being released to the outside of the capsule in a short period of time, and the microcapsules have sufficient durability.

[0016] <Evaluation of Microcapsule Durability (1)> The degree of durability of the microcapsules of this embodiment can be determined, for example, by preparing evaluation microcapsules that are identical to the microcapsules described above except that they contain a mixture of the lipophilic substance and a color developer instead of the lipophilic substance, storing these evaluation microcapsules stationary in the desired environment, and quantifying the amount of the color developer that has been released outside the capsules up to that point. Here, the target environment is, for example, an environment in which the microcapsules are added to the fabric softener or a liquid having a similar composition to the fabric softener, such as a diluted liquid of the fabric softener, in the case where the microcapsules are added to the fabric softener.

[0017] More specifically, after t hours (t is a positive number) from the start of static storage of the microcapsules for evaluation, a portion of the stored material is collected as a first sample, and insoluble matter in the first sample is removed as necessary. Acid is then added to the first sample to prepare a second sample for measurement. Next, the absorbance A of the second sample at a specific wavelength is measured. t The light measured here is the light originating from the color-developing agent, and the wavelength at which absorbance is measured is determined depending on the type of color-developing agent.t By measuring this, it is possible to quantify the amount of the developer released outside the evaluation microcapsules t hours after the start of static storage. A t may be measured only once, or, if necessary, may be measured two or more times by changing the static storage time (t).

[0018] Next, A t After measuring the absorbance A, all or almost all of the color developer contained in the original microcapsules is released to the outside of the evaluation microcapsules, and the absorbance A is measured in the same manner as above. z To do this, A t After measuring the absorbance A, the stored product is further heated and stored. The storage conditions can be set taking into consideration the types of microcapsules and color developer, etc., but typically, it is sufficient to store the product at 70°C or higher for 48 hours or more. Whether or not the entire amount or almost the entire amount of the color developer has been released to the outside of the evaluation microcapsules can be determined by finally measuring the absorbance A in the same manner as above using the stored product that has been heated and stored. x Measure A x This can be determined by checking that the clear rise in A has stopped and plateaued. x A z Let's say.

[0019] Next, the remaining core substance rate (1) in the microcapsules for evaluation after t hours from the start of static storage is calculated using the following formula (i). [Core substance remaining rate in evaluation microcapsules (1) (%)] = (1 - A t / A z )×100 (i) The method for producing the microcapsules for evaluation will be explained in detail later.

[0020] In the microcapsules of this embodiment, the core substance residual rate (1) at t=24 (one day of static storage) can be 40% or more. Such microcapsules are significantly superior in durability to conventional microcapsules made of biodegradable materials. In the microcapsules of this embodiment, the core substance residual rate (1) when t=24 can be, for example, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more. On the other hand, when t=24, the core substance remaining rate (1) is 100% or less.

[0021] In the microcapsules of this embodiment, the core substance remaining rate (1) at t=168 (seven days of static storage) can be, for example, 30% or more, 55% or more, 70% or more, 85% or more, 90% or more, or 95% or more. The durability of such microcapsules is particularly high. On the other hand, when t=168, the core substance remaining rate (1) is 100% or less.

[0022] <Evaluation of Microcapsule Durability (2)> The degree of durability of the microcapsules of this embodiment can be determined, for example, by using an evaluation dispersion containing microcapsules and water, storing the dispersion, and quantifying the amount of lipophilic substance encapsulated in the capsules before and after storage. Examples of the evaluation dispersion include a microcapsule dispersion obtained by production of microcapsules immediately after production, or a mixture of a microcapsule dispersion immediately after production and water.

[0023] More specifically, a portion of the dispersion for evaluation is collected as a third sample, and insoluble matter in the third sample is collected by filtration. If necessary, the insoluble matter is washed with water or the like, and then added to ethanol and stirred thoroughly to obtain an ethanol mixture. The supernatant is then collected from the ethanol mixture and analyzed by gas chromatography-mass spectrometry (GC-MS). The amount of lipophilic substance extracted from the insoluble matter, C0, is quantified. C0 corresponds to the amount of lipophilic substance encapsulated in the microcapsules in the dispersion for evaluation before static storage (initial stage).

[0024] The dispersion for evaluation after collecting the third sample is left standing and stored, and after t hours (t is a positive number) from the start of the standing storage, a part of the dispersion for evaluation is collected as a fourth sample, and the amount C of lipophilic substances extracted from the insoluble matter of this fourth sample is measured in the same manner as for the third sample. t Quantify C t corresponds to the amount of lipophilic substance contained in the microcapsules in the dispersion for evaluation t hours after the start of static storage. C t may be measured only once, or, if necessary, may be measured two or more times by changing the static storage time (t).

[0025] Next, the remaining core substance rate (2) in the microcapsules in the dispersion for evaluation after t hours from the start of static storage is calculated using the following formula (ii). [Core substance remaining rate in microcapsules (2) (%)] = C t / C0×100 (ii)

[0026] In the microcapsules of this embodiment, the core substance remaining rate (2) at t=24 (storage time of 1 day) can be 40% or more. Such microcapsules are significantly superior in durability to conventional microcapsules made of biodegradable materials. In the microcapsules of this embodiment, the core substance residual rate (2) when t=24 can be, for example, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more. On the other hand, when t=24, the core substance remaining rate (2) is 100% or less.

[0027] In the microcapsules of this embodiment, the core substance remaining rate (2) at t=168 (seven days of static storage) can be, for example, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, or 80% or more. The durability of such microcapsules is particularly high. On the other hand, when t=168, the core substance remaining rate (2) is 100% or less.

[0028] <Evaluation of biodegradability of biodegradable resin in microcapsules> The degree of biodegradability of the biodegradable resin contained in the microcapsules of this embodiment can be determined by the biodegradability of the resin component, calculated using a known method, such as a method in accordance with "OECD 301F" or a method with some of the conditions modified, for the resin component obtained by removing the lipophilic substance from the microcapsules. In the microcapsules of this embodiment, for example, as described below in the examples, when a biodegradation test is conducted for 60 days at a temperature of 22°C using a BOD measuring device, the biodegradability after 60 days can be 40% or more, for example, 45% or more, 50% or more, or 55% or more. In the microcapsules of this embodiment, even if the degree of biodegradation after 60 days is less than 40%, it is possible to promote the biodegradation of the biodegradable resin by extending the treatment time.

[0029] ◇Wall materials The wall material is composed of one or both of polyurea and polyurethane, i.e., the wall material contains at least one of polyurea and polyurethane.

[0030] <Polyurea> The polyurea, which is a component of the wall material, is not particularly limited as long as it is an oligomer or polymer having a bond represented by the formula "-NH-C(=O)-NH-" (urea bond). The polyurea is obtained by polymerizing a polyisocyanate compound having two or more isocyanate groups (-N=C=O) in one molecule with a polyamine compound having two or more amino groups (-NH2) in one molecule.

[0031] [Polyisocyanate compounds] The polyisocyanate compound is not particularly limited as long as it has two or more isocyanate groups in one molecule, but it is preferable that it does not have an amino group or a hydroxyl group, and more preferable that it does not have either an amino group or a hydroxyl group.

[0032] The number of isocyanate groups that the polyisocyanate compound has in one molecule is not particularly limited as long as it is 2 or more, and may be, for example, 10 or more. However, in terms of not having excessive reactivity and stabilizing the reactivity with the reactants (the polyamine compound and the polyol compound described below), the number is preferably 2 to 5, and more preferably 2 to 4.

[0033] Examples of the polyisocyanate compound include an organic polyvalent isocyanate compound and its trimethylolpropane adduct, a derivative of the organic polyvalent isocyanate compound (provided that the isocyanate group is not substituted) and its trimethylolpropane adduct, etc. In this specification, the trimethylolpropane adduct may also be referred to as a trimethylolpropane adduct.

[0034] In this specification, when a structure in which one or more hydrogen atoms in a certain compound are substituted with a group other than a hydrogen atom is assumed, the compound having such a substituted structure is referred to as a "derivative" of the above-mentioned specific compound. In this specification, unless otherwise specified, the term "group" includes not only an atomic group formed by bonding multiple atoms but also a single atom.

[0035] The organic polyisocyanate compounds can be classified into aliphatic polyisocyanate compounds (aliphatic polyisocyanate compounds) that have an aliphatic hydrocarbon group but do not have an aromatic hydrocarbon, and aromatic polyisocyanate compounds (aromatic polyisocyanate compounds) that may or may not have an aliphatic hydrocarbon group but do have an aromatic hydrocarbon.

[0036] Examples of the aromatic polyisocyanate compound include tolylene diisocyanates such as tolylene-2,4-diisocyanate and tolylene-2,6-diisocyanate; xylylene diisocyanates such as xylylene-1,3-diisocyanate and xylylene-1,4-diisocyanate; diphenylmethane diisocyanates such as 4,4'-diphenylmethane diisocyanate (also known as methylene diphenyl 4,4'-diisocyanate) and 2,4'-diphenylmethane diisocyanate; 4,4'-diisocyanato-3,3'-dimethylbiphenyl (also known as o-tolidine diisocyanate); and polymethylene polyphenyl polyisocyanate (sometimes referred to as "polymeric MDI" in this specification). Examples of the aliphatic polyisocyanate compound include hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, and 1,3-bis(isocyanatomethyl)cyclohexane.

[0037] The polymeric MDI is represented by the following general formula (P1).

[0038] [ka] (wherein n is an integer of 0 or more).

[0039] In the general formula (P1), n ​​may be an integer of 0 or more, for example, 0-300. The NCO content of the polymeric MDI can be adjusted appropriately and may be, for example, 30 to 33 mass %. Polymeric MDI is liquid at room temperature, and its viscosity at 25° C. is not particularly limited and may be, for example, 150 to 250 mPa·s.

[0040] In this specification, "room temperature" means a temperature that is neither particularly cold nor hot, that is, an ordinary temperature, and examples thereof include temperatures of 15 to 25°C.

[0041] In microcapsules using the aliphatic polyisocyanate compound, the biodegradability of the biodegradable resin tends to be higher than in microcapsules using the aromatic polyisocyanate compound.

[0042] When the polyisocyanate compound is an aliphatic polyisocyanate compound, the mass ratio of [the content (parts by mass) of the polyurea in the microcapsules]:[the content (parts by mass) of the biodegradable resin in the microcapsules] is preferably 10:90 to 40:60, and may be, for example, any of 20:80 to 40:60, 30:70 to 40:60, 10:90 to 30:70, and 10:90 to 20:80. The biodegradability of the biodegradable resin in such microcapsules is higher.

[0043] When the polyisocyanate compound is an aromatic polyisocyanate compound, the mass ratio of [the content (parts by mass) of the polyurea in the microcapsules]:[the content (parts by mass) of the biodegradable resin in the microcapsules] is preferably 5:95 to 20:80, and may be, for example, any of 10:90 to 20:80, 15:85 to 20:80, 5:95 to 15:85, and 5:95 to 10:90. The biodegradability of the biodegradable resin in such microcapsules is higher.

[0044] The components used in forming the polyurea (in other words, the structural units of the polyurea derived from the polyisocyanate compound) may be one type only or two or more types, and when two or more types are used, the combination and ratio thereof can be selected arbitrarily.

[0045] [Polyamine compounds] The polyamine compound used to form the polyurea is not particularly limited as long as it has two or more amino groups in one molecule, but it is preferable that it does not have an isocyanate group or a hydroxyl group, and more preferable that it does not have either an isocyanate group or a hydroxyl group.

[0046] The number of amino groups that the polyamine compound has in one molecule is not particularly limited as long as it is two or more, but is preferably 2 to 6, more preferably 2 to 5, even more preferably 2 to 4, and particularly preferably 2 or 3.

[0047] The polyamine compound is preferably an organic polyamine compound. Examples of the organic polyamine compound include an aliphatic polyamine compound having a structure in which two or more hydrogen atoms (-H) in an aliphatic hydrocarbon are substituted with amino groups (-NH2); an NH-substituted aliphatic polyamine compound having a structure in which one or more methylene groups (-CH2-) in the aliphatic polyamine compound are substituted with imino groups (-NH-); and an aromatic polyamine compound having a structure in which two or more hydrogen atoms in an aromatic hydrocarbon are substituted with amino groups. The aromatic hydrocarbon may have an aliphatic hydrocarbon group (that is, may have both an aromatic cyclic group and an aliphatic hydrocarbon group), or may not have an aliphatic hydrocarbon group. When the aromatic hydrocarbon has the aliphatic hydrocarbon group, the organic polyvalent amine compound may be any of the following: an aromatic polyvalent amine compound having a structure in which, in the aromatic hydrocarbon, one or more hydrogen atoms in the aromatic cyclic group are substituted with amino groups and one or more hydrogen atoms in the aliphatic hydrocarbon group are substituted with amino groups; an aromatic polyvalent amine compound having a structure in which two or more hydrogen atoms in the aromatic cyclic group are substituted with amino groups and no hydrogen atoms in the aliphatic hydrocarbon group are substituted with amino groups; and an aromatic polyvalent amine compound having a structure in which two or more hydrogen atoms in the aliphatic hydrocarbon group are substituted with amino groups and no hydrogen atoms in the aromatic cyclic group are substituted with amino groups. When the aromatic polyamine compound has an aliphatic hydrocarbon group, examples of the organic polyamine compound include NH-substituted aromatic polyamine compounds having a structure in which one or more methylene groups in the aliphatic hydrocarbon group are substituted with imino groups.

[0048] The number of imino groups that the NH-substituted aliphatic polyamine compound and the NH-substituted aromatic polyamine compound have in one molecule is not particularly limited as long as it is 1 or more, but is preferably 1 to 3, and more preferably 2 or 3.

[0049] Examples of the aliphatic polyamine compounds include N,N'-bis(3-aminopropyl)ethylenediamine (BAEA), diethylenetriamine (DETA), 1,3-diaminopropane (DAP), 1,3-bis(aminomethyl)cyclohexane, and 4,4'-methylenebis(cyclohexylamine) (MCA). Examples of the aromatic polyamine compounds include p-xylylenediamine (XDA).

[0050] The polyamine compound also includes a hydrolyzate of the polyisocyanate compound. Such a polyamine compound is a compound in which two or more isocyanate groups (-N=C=O) in the polyisocyanate compound react with water to remove carbon dioxide, converting the isocyanate groups to amino groups (-NH2), and is derived from the polyisocyanate compound. Such polyamine compounds derived from polyisocyanate compounds may include both those that fall under the polyamine compounds described above and those that do not.

[0051] When a hydrolysate of the polyisocyanate compound is used as the polyamine compound, it is not necessary to prepare the polyamine compound in advance, as will be described later, and polyurea can be formed by a simplified method. In other words, from the viewpoint of ease of production of microcapsules, the polyurea is preferably a polymer of a polyisocyanate compound and a polyamine compound derived from the polyisocyanate compound.

[0052] Among the polyamine compounds, the aliphatic polyvalent amine compounds may be linear, branched, or cyclic. When the polyamine compounds are cyclic, they may have only a cyclic structure, or may have both a cyclic structure and a chain structure (either a linear structure or a branched structure, or both). In the aliphatic polyamine compound, the bonding position of the amino group (in other words, the substitution position of a hydrogen atom with an amino group in the aliphatic hydrocarbon) is not particularly limited.

[0053] In terms of increasing the durability of the microcapsules, the aliphatic polyamine compound is preferably chain-shaped (linear or branched), regardless of whether or not the methylene group is substituted with an imino group, and is more preferably linear. The reason for this is unclear, but it is presumed that a chain-shaped (particularly linear) aliphatic polyamine compound has a less bulky structure than a cyclic aliphatic polyamine compound, and is more likely to approach the polyisocyanate compound, the reaction target, and form polyurea. Furthermore, it is presumed that the formed polyurea chains also easily approach each other. As a result, the polyurea chains gather together at a high density in the wall material, increasing the strength of the wall material. It is presumed that the release of the core substance to the outside of the capsule in a short period of time during storage of the microcapsules is strongly suppressed, resulting in increased durability of the microcapsules.

[0054] Examples of the chain (straight-chain) aliphatic polyamine compounds include N,N'-bis(3-aminopropyl)ethylenediamine (BAEA), diethylenetriamine (DETA), 1,3-diaminopropane (DAP), and 1,3-bis(aminomethyl)cyclohexane.

[0055] In order to improve the durability of the microcapsules, the aliphatic polyamine compound preferably has an imino group in addition to an amino group, and more preferably has a chain structure and has an imino group in addition to an amino group. Examples of such aliphatic polyamine compounds having an imino group include N,N'-bis(3-aminopropyl)ethylenediamine and diethylenetriamine.

[0056] Among the polyamine compounds, the aromatic polyvalent amine compounds preferably have a structure in which, in an aromatic hydrocarbon having both an aromatic cyclic group and an aliphatic hydrocarbon group, one or more hydrogen atoms in the aliphatic hydrocarbon group are substituted with amino groups, in order to increase the durability of the microcapsules, and more preferably have a structure in which two or more hydrogen atoms in the aliphatic hydrocarbon group are substituted with amino groups and no hydrogen atoms in the aromatic cyclic group are substituted with amino groups.

[0057] The polyamine compound used when forming the polyurea (in other words, the structural units of the polyurea derived from the polyamine compound) may be one type or two or more types, and when two or more types are used, the combination and ratio thereof can be selected arbitrarily.

[0058] When comparing chain aliphatic polyamine compounds with aromatic polyamine compounds, the chain aliphatic polyamine compounds are preferred as the polyamine compounds in terms of increasing the durability of the microcapsules. The reason for this is not clear, but it is presumed to be the same as the reason why chain aliphatic polyamine compounds are preferred over cyclic aliphatic polyamine compounds, as explained above.

[0059] In order to improve the durability of the microcapsules, the polyamine compound is preferably one or more selected from the group consisting of the aliphatic polyamine compounds and NH-substituted aliphatic polyamine compounds, and is more preferably a chain-like compound regardless of whether or not a methylene group is substituted with an imino group. That is, the polyurea is more preferably a polymer of a polyisocyanate compound and a chain-like polyamine compound.

[0060] When the wall material is a polyurea, which is a polymer of an aliphatic polyisocyanate compound and a polyamine compound, and the mass ratio of the polyurea content (parts by mass) of the microcapsules to the biodegradable resin content (parts by mass) of the microcapsules is within the above-mentioned range of 10:90 to 40:60, the polyamine compound is preferably linear. The biodegradability of the biodegradable resin in such microcapsules is higher.

[0061] When the wall material is a polyurea, which is a polymer of an aromatic polyisocyanate compound and a polyamine compound, and the mass ratio of the polyurea content (parts by mass) in the microcapsules to the biodegradable resin content (parts by mass) in the microcapsules is within the above-mentioned range of 5:95 to 20:80, the polyamine compound is preferably linear. The biodegradability of the biodegradable resin in such microcapsules is higher.

[0062] The wall material may be made of one type of polyurea or two or more types, and when two or more types are used, the combination and ratio thereof can be selected arbitrarily. In this specification, when the combinations of all the structural units of the polyurea (in other words, the combinations of all the polyisocyanate compounds and all the polyamine compounds used to form the polyurea) are the same, these polyureas are considered to be of the same type.

[0063] <Polyurethane> The polyurethane, which is a component of the wall material, is not particularly limited as long as it is an oligomer or polymer having a bond represented by the formula "-NH-C(=O)-O-" (urethane bond). The polyurethane is obtained by polymerizing a polyisocyanate compound having two or more isocyanate groups (-N=C=O) in one molecule with a polyol compound having two or more hydroxyl groups (-OH) in one molecule.

[0064] [Polyisocyanate compounds] The polyisocyanate compound used to form the polyurethane may be the same as the polyisocyanate compound used to form the polyurea, as explained above.

[0065] The polyisocyanate compound used when forming the polyurethane (in other words, the structural units of the polyurethane derived from the polyisocyanate compound) may be one type or two or more types, and when two or more types are used, the combination and ratio thereof can be selected arbitrarily.

[0066] Further detailed description of the polyisocyanate compound used to form the polyurethane will be omitted.

[0067] [Polyol compounds] The polyol compound is not particularly limited as long as it has two or more hydroxyl groups in one molecule, but it is preferable that it does not have an isocyanate group or an amino group, and more preferable that it does not have either an isocyanate group or an amino group.

[0068] The number of hydroxyl groups that the polyol compound has in one molecule is not particularly limited as long as it is two or more, but is preferably 2 to 6, more preferably 2 to 5, even more preferably 2 to 4, and particularly preferably 2 or 3.

[0069] Examples of the polyol compound include organic polyhydric hydroxy compounds. Examples of the organic polyhydroxy compound include alkylene glycols such as ethylene glycol, propylene glycol, and 1,4-butanediol.

[0070] The polyol compound used in forming the polyurethane (in other words, the structural units of the polyurethane derived from the polyol compound) may be one type or two or more types, and when two or more types are used, the combination and ratio thereof can be selected arbitrarily.

[0071] The polyurethane constituting the wall material may be one type only, or two or more types, and when two or more types are used, the combination and ratio thereof can be selected arbitrarily. In this specification, when the combinations of all of the structural units of a polyurethane (in other words, the combinations of all of the polyisocyanate compounds and all of the polyol compounds used to form the polyurethane) are the same, these polyurethanes are considered to be of the same type.

[0072] <Other wall material compositions> The wall material may or may not contain, in addition to either or both of polyurea and polyurethane, other components that do not fall into the category of either polyurea or polyurethane. That is, the wall material may be composed of at least one of polyurea and polyurethane, and may further contain the other components that are optional components.

[0073] The other components constituting the wall material can be selected arbitrarily depending on the purpose, and are not particularly limited.

[0074] The other components constituting the wall material may be one type only, or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

[0075] In the wall material, the ratio of the total amount of polyurea and polyurethane to the total amount of the constituent components of the wall material (([amount of polyurea in the wall material (parts by mass)] + [amount of polyurethane in the wall material (parts by mass)]) / [total amount of constituent components of the wall material (parts by mass)] × 100) is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, and may be, for example, either 95% by mass or more or 97% by mass or more. The higher this ratio, the greater the durability of the microcapsules. On the other hand, the proportion is 100% by mass or less. Here, if polyurethane is not a constituent component of the wall material (the wall material does not contain polyurethane), the amount of polyurethane in the wall material is 0 parts by mass, and if polyurea is not a constituent component of the wall material (the wall material does not contain polyurea), the amount of polyurea in the wall material is 0 parts by mass.

[0076] ◇Core substance The microcapsules of this embodiment contain, as the core substance, a biodegradable resin that does not fall under the category of polyol and has a melting point of 100° C. or less, and a lipophilic substance, enclosed by a wall material.

[0077] <Biodegradable resins with a melting point of 100°C or less that do not fall under the category of polyols> In the microcapsules of this embodiment, the biodegradable resin inhibits the release of the lipophilic substance to the outside of the capsule in a short period of time. The biodegradable resin is not particularly limited as long as it does not fall under the category of polyol and has a melting point of 100° C. or less.

[0078] The reason why the melting point of the biodegradable resin contained in the microcapsules of this embodiment is 100°C or below is that when producing the microcapsules, the biodegradable resin needs to be melted in the presence of water, and the boiling point of water at normal pressure is 100°C.

[0079] The reason why polyols are excluded from the biodegradable resins having a melting point of 100° C. or less that are encapsulated in the microcapsules of this embodiment is that the durability of the microcapsules is reduced when polyols are used. The reason for this is presumably that during the production of microcapsules, a portion of the polyol reacts with a polyisocyanate compound to form polyurethane, which then becomes a constituent component of the wall material. Such polyurethane is biodegradable, and it is presumed that the durability of microcapsules using biodegradable polyurethane as a constituent component of the wall material is insufficient. For example, as explained above, the durability of microcapsules using polyurea or polyurethane obtained using polycaprolactone diol as a constituent component of the wall material is insufficient.

[0080] Examples of the polyol, which is a biodegradable resin having a melting point of 100° C. or less, include polycaprolactone diol.

[0081] In this specification, unless otherwise specified, the term "biodegradable resin" refers to the above-mentioned biodegradable resin that does not fall under the category of polyol and has a melting point of 100°C or less.

[0082] The biodegradable resin encapsulated in the wall material may be one type only, or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

[0083] The melting point of the biodegradable resin may be, for example, any one of 90° C. or lower, 80° C. or lower, and 70° C. or lower. The lower the melting point of the biodegradable resin, the easier it is to produce microcapsules. On the other hand, the lower limit of the melting point of the biodegradable resin is not particularly limited as long as it does not impair the effects of the present invention. For example, biodegradable resins with a melting point of 50°C or higher are easily available. Furthermore, considering the use of microcapsules, there is a good chance that the microcapsules will be placed in a temperature environment of about 50°C during use. Therefore, if the melting point of the biodegradable resin is 50°C or higher, the retention effect of the lipophilic substance by the biodegradable resin will be enhanced, and the effect of suppressing the release of the lipophilic substance to the outside of the capsule in a short period of time will be further enhanced.

[0084] The weight average molecular weight of the biodegradable resin may be, for example, either 3,000 to 50,000 or 5,000 to 30,000.

[0085] In this specification, not only in the case of the biodegradable resin, but also in other cases, the weight average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC) unless otherwise specified.

[0086] Examples of the biodegradable resin include polyesters such as polycaprolactone (PCL), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), and polyethylene succinate (PES).

[0087] The biodegradable resin is preferably either or both of polycaprolactone and polybutylene succinate, and more preferably polycaprolactone, because it is relatively easy to obtain and the durability of the microcapsules is increased. Commercially available polycaprolactone products include those manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., and commercially available polybutylene succinate products include those manufactured by Mitsubishi Chemical Corporation.

[0088] When the wall material is a polyurea, which is a polymer of an aliphatic polyisocyanate compound and a polyamine compound, and the mass ratio of the polyurea content (parts by mass) of the microcapsules to the biodegradable resin content (parts by mass) of the microcapsules is within the above-mentioned range of 10:90 to 40:60, the biodegradable resin is preferably one or more selected from the group consisting of polycaprolactone, polybutylene succinate, polybutylene succinate adipate, and polyethylene succinate, more preferably either or both of polycaprolactone and polybutylene succinate, and even more preferably polycaprolactone. The biodegradability of the biodegradable resin in such microcapsules is higher.

[0089] When the wall material is a polyurea, which is a polymer of an aromatic polyisocyanate compound and a polyamine compound, and the mass ratio of the polyurea content (parts by mass) of the microcapsules to the biodegradable resin content (parts by mass) of the microcapsules is within the above-mentioned range of 5:95 to 20:80, the biodegradable resin is preferably one or more selected from the group consisting of polycaprolactone, polybutylene succinate, polybutylene succinate adipate, and polyethylene succinate, more preferably either or both of polycaprolactone and polybutylene succinate, and even more preferably polycaprolactone. The biodegradability of the biodegradable resin in such microcapsules is higher.

[0090] <Lipophilic substances> In the microcapsules of this embodiment, the lipophilic substance is the main component for achieving the desired effect, and by being gradually released to the outside of the capsule, the effect can be maintained for a long period of time.

[0091] The lipophilic substance has an SP value (solubility parameter) of 7 to 12 (cal / cm 3 ) 1 / 2In this specification, the "SP value" is a value calculated by the Fedors calculation method. The SP value of the lipophilic substance is, for example, 7 to 10.5 (cal / cm 3 ) 1 / 2 , 7-9 (cal / cm 3 ) 1 / 2 , 8.5 to 12 (cal / cm 3 ) 1 / 2 , 10-12 (cal / cm 3 ) 1 / 2 , and 8.5 to 10.5 (cal / cm 3 ) 1 / 2 It may be either of the following.

[0092] The lipophilic substance encapsulated by the wall material may be one kind or two or more kinds, and when there are two or more kinds, the combination and ratio thereof can be selected arbitrarily.

[0093] Preferred examples of the lipophilic substance include essential oils, perfumes, insect repellents, antibacterial agents, deodorants, and dyes. For example, the essential oils are usually mixtures of two or more lipophilic substances.

[0094] Examples of essential oils include lavender oil (main components: linalool (SP value 10), linalyl acetate (SP value 8.5)), tea tree oil (main components: terpinen-4-ol (SP value 10.9), γ-terpinene (SP value 8.5)), and cypress oil (main components: α-pinene (SP value 9), δ-cadinol (SP value 10.7)).

[0095] Examples of the fragrance include floral fragrances such as rose fragrance; fruit fragrances such as apple fragrance; fragrances that give a refreshing feeling such as menthol; and the like.

[0096] The lipophilic substance is preferably one or more selected from the group consisting of essential oils and fragrances. Essential oils and fragrances are particularly suitable for applications where their effects must be maintained for a long period of time, and are also more preferred core substances in terms of combination with the biodegradable resin to obtain the effect of improving the durability of the microcapsules.

[0097] In the microcapsules, the ratio of the content of the lipophilic substance to the total content of the biodegradable resin and the lipophilic substance ([content of lipophilic substance in microcapsules (parts by mass)] / ([content of biodegradable resin in microcapsules having a melting point of 100°C or less that does not correspond to polyol (parts by mass)]+[content of lipophilic substance in microcapsules (parts by mass)])×100) is preferably 25 to 75% by mass, and may be, for example, any of 25 to 65% by mass and 25 to 55% by mass, any of 35 to 75% by mass and 45 to 75% by mass, or any of 35 to 65% by mass and 45 to 55% by mass. The higher this ratio, the higher the effect attributable to the lipophilic substance in the microcapsules. The lower this ratio, the higher the durability of the microcapsules. The closer this ratio is to 50% by mass, the higher both the effect attributable to the lipophilic substance in the microcapsules and the durability of the microcapsules will be. The ratio of the content of the lipophilic substance to the total content of the biodegradable resin and the lipophilic substance in the microcapsules is generally synonymous with the ratio of the amount of the lipophilic substance encapsulated in the wall material to the total amount of the biodegradable resin and the lipophilic substance encapsulated in the wall material.

[0098] In the microcapsules, the total content of the biodegradable resin and the lipophilic substance is preferably 1 to 18 times by mass, more preferably 1.5 to 17 times by mass, and may be 1.5 to 15 times by mass, relative to the total content of the polyurea and polyurethane. For example, it may be any of 1.5 to 12 times by mass, 1.5 to 9 times by mass, and 1.5 to 6 times by mass, or any of 3 to 17 times by mass, 5 to 17 times by mass, and 7 to 17 times by mass, or any of 3 to 15 times by mass, 5 to 15 times by mass, and 7 to 15 times by mass, or any of 3 to 12 times by mass, and 5 to 9 times by mass. The above-mentioned multiple of the total content of the biodegradable resin and the lipophilic substance relative to the total content of the polyurea and polyurethane in the microcapsules is generally synonymous with the multiple of the total amount (parts by mass) of the biodegradable resin and the lipophilic substance contained in the wall material relative to the total amount (parts by mass) of the polyurea and polyurethane in the wall material in the microcapsules.

[0099] <Other components of the core substance> In addition to the biodegradable resin and lipophilic substance, the wall material may or may not contain other components that do not fall into either the biodegradable resin or the lipophilic substance.

[0100] The other component enclosed in the wall material (core substance) can be selected arbitrarily depending on the purpose, and is not particularly limited.

[0101] The other component encapsulated in the wall material (core substance) may be one type only or two or more types, and when there are two or more types, the combination and ratio thereof can be selected arbitrarily.

[0102] The ratio of the total amount (parts by mass) of the biodegradable resin and the lipophilic substance to the total amount (parts by mass) of components other than the solvent contained in the wall material (((amount (parts by mass) of biodegradable resin (parts by mass) that is not a polyol and has a melting point of 100°C or less contained in the wall material)] + [amount (parts by mass) of the lipophilic substance contained in the wall material)]) / [total amount (parts by mass) of components other than the solvent contained in the wall material)] × 100) is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, and may be, for example, either 95% by mass or more or 97% by mass or more. The higher this ratio, the greater both the effect attributable to the lipophilic substance in the microcapsules and the durability of the microcapsules. On the other hand, the proportion is 100% by mass or less. Here, a solvent is a component that is liquid at room temperature and normal pressure and is used to dissolve any of the manufacturing raw materials or to improve the dispersibility of any of the manufacturing raw materials during the production of microcapsules.

[0103] ◇Other structures of microcapsules The average particle size of the microcapsules is not particularly limited, but is preferably 1 to 100 μm, and more preferably 5 to 50 μm. The average particle size of the microcapsules can be adjusted, for example, by adjusting the types of components constituting the wall material, the type of core substance, or the stirring conditions of the reaction solution during the polymerization reaction to form the wall material.

[0104] In this specification, unless otherwise specified, the term "average particle size" refers to the median diameter of the volume particle size distribution of particles measured using a particle size distribution analyzer.

[0105] ◇An example of a microcapsule An example of a preferred microcapsule of this embodiment is a microcapsule configured by encapsulating a core substance within a wall material, The wall material is made of either or both of polyurea and polyurethane, the core substance is a lipophilic substance and a biodegradable resin that does not fall under the category of polyol and has a melting point of 100°C or less, the polyurea is a polymer of a polyisocyanate compound and a chain polyamine compound, The lipophilic substance is one or more selected from the group consisting of essential oils and fragrances, Examples of the microcapsules include those in which the biodegradable resin is polyester. In such microcapsules, the biodegradable resin is preferably polycaprolactone.

[0106] Another preferred example of the microcapsule of this embodiment is a microcapsule configured by encapsulating a core substance within a wall material, The wall material is made of either or both of polyurea and polyurethane, the core substance is a lipophilic substance and a biodegradable resin that does not fall under the category of polyol and has a melting point of 100°C or less, the polyurea is a polymer of a polyisocyanate compound and a polyamine compound derived from the polyisocyanate compound, The lipophilic substance is one or more selected from the group consisting of essential oils and fragrances, Examples of the microcapsules include those in which the biodegradable resin is polyester. In such microcapsules, the biodegradable resin is preferably polycaprolactone.

[0107] Still another example of a preferred microcapsule of this embodiment is a microcapsule configured by encapsulating a core substance within a wall material, The wall material is made of polyurea or polyurea and polyurethane, the core substance is a lipophilic substance and a biodegradable resin that does not fall under the category of polyol and has a melting point of 100°C or less, the polyurea is a polymer of a polyisocyanate compound and a chain polyamine compound, the polyisocyanate compound is an aliphatic polyisocyanate compound, Examples of microcapsules include those in which the mass ratio of [content (parts by mass) of the polyurea in the microcapsules]:[content (parts by mass) of the biodegradable resin in the microcapsules] is 10:90 to 40:60. In such microcapsules, the biodegradable resin is preferably polycaprolactone. In such microcapsules, the lipophilic substance is preferably one or more selected from the group consisting of essential oils and fragrances.

[0108] Still another example of a preferred microcapsule of this embodiment is a microcapsule configured by encapsulating a core substance within a wall material, The wall material is made of polyurea or polyurea and polyurethane, the core substance is a lipophilic substance and a biodegradable resin that does not fall under the category of polyol and has a melting point of 100°C or less, the polyurea is a polymer of a polyisocyanate compound and a chain polyamine compound, the polyisocyanate compound is an aromatic polyisocyanate compound, Examples of microcapsules include those in which the mass ratio of [content (parts by mass) of the polyurea in the microcapsules]:[content (parts by mass) of the biodegradable resin in the microcapsules] is 5:95 to 20:80. In such microcapsules, the biodegradable resin is preferably polycaprolactone. In such microcapsules, the lipophilic substance is preferably one or more selected from the group consisting of essential oils and fragrances.

[0109] <<Microcapsule manufacturing method (manufacturing method (1))>> A method for producing microcapsules according to one embodiment of the present invention includes the steps of: preparing an oil-based solution by mixing a lipophilic substance, a biodegradable resin that does not fall under the category of polyol and has a melting point of 100°C or less, and a polyisocyanate compound (sometimes referred to herein as "oil-based solution preparation step (1)"); a step of preparing an emulsion by mixing an emulsifier and the oil-based solution in the presence of water (sometimes referred to in this specification as an "emulsification step (1)"); and a step of preparing microcapsules by mixing the emulsion with a polyamine compound and carrying out a polymerization reaction while heating (sometimes referred to in this specification as "encapsulation step (1)"). (In this specification, this production method is sometimes referred to as "production method (1)"). The manufacturing method (1) is an embodiment of a method for manufacturing microcapsules according to one embodiment of the present invention, in which the wall material is polyurea.

[0110] <Oil-based solution preparation process (1)> In the oil-based solution preparation step (1), the lipophilic substance, the biodegradable resin, and a polyisocyanate compound are mixed together to prepare an oil-based solution. The oil-based solution has a higher affinity for oil than for water.

[0111] In the oil-based solution preparation step (1), other components that do not fall into any of the categories of the biodegradable resin, the lipophilic substance, and the polyisocyanate compound may or may not be mixed (blended).

[0112] The biodegradable resin, lipophilic substance, polyisocyanate compound, and other components used in the oil-based solution preparation step (1) are all as described above. The other components used in this step are either or both of the other components contained in the wall material described above and the other components encapsulated in the wall material.

[0113] The biodegradable resin, lipophilic substance, polyisocyanate compound, and other components used in the oil-based solution preparation step (1) may each be one type or two or more types, and when two or more types are used, the combination and ratio thereof can be selected arbitrarily.

[0114] The lipophilic substance used in the oil-based solution preparation step (1) is preferably one or more selected from the group consisting of essential oils and fragrances. The biodegradable resin used in the oil-based solution preparation step (1) is preferably either or both of polycaprolactone and polybutylene succinate, and more preferably polycaprolactone.

[0115] In the oil-based solution preparation step (1), the order in which the above-mentioned raw materials are mixed is not particularly limited. When other components are used in this step, the target and timing of their addition can be adjusted as appropriate.

[0116] In the oil-based solution preparation step (1), the biodegradable resin is preferably heated to melt it and then mixed with other raw materials.

[0117] In the oil-based solution preparation step (1), it is preferable to prepare the oil-based solution by, for example, heating the biodegradable resin to melt it in advance, mixing the melted biodegradable resin with the lipophilic substance, cooling the mixture obtained, and mixing the cooled mixture with a polyisocyanate compound.

[0118] The heating temperature when the biodegradable resin is heated and melted can be adjusted appropriately depending on the type of biodegradable resin, but is usually preferably 60 to 95° C., and may be, for example, any of 60 to 75° C., 70 to 85° C., and 80 to 95° C. When the heating temperature is equal to or higher than the lower limit, the biodegradable resin can be melted in a shorter time, and when the heating temperature is equal to or lower than the upper limit, excessive heating can be avoided.

[0119] The temperature of the mixture of the biodegradable resin and the lipophilic substance when mixed with the polyisocyanate compound is not particularly limited, but is preferably 30 to 60°C.

[0120] In the oil-based solution preparation step (1), it is preferable that the ratio of the amount of the lipophilic substance to the total amount of the biodegradable resin and the lipophilic substance is the same as the ratio of the amount of the lipophilic substance to the total amount of the biodegradable resin and the lipophilic substance in the above-mentioned microcapsules.

[0121] In the oil-based solution preparation step (1), the amount of polyisocyanate compound is preferably a blending amount that satisfies the multiple of the total content of the biodegradable resin and the lipophilic substance relative to the total content of polyurea and polyurethane in the above-mentioned microcapsules (however, here the content of polyurethane is 0 parts by mass).

[0122] In the oil-based solution preparation step (1), the mixture obtained by blending all of the above-mentioned raw materials is preferably stirred at normal temperature such as room temperature.

[0123] The method for mixing the biodegradable resin, the lipophilic substance, the polyisocyanate compound, and, if necessary, other components, and the method for further stirring the mixture obtained thereby are not particularly limited, and examples thereof include a method in which mixing or stirring is performed by rotating a stirring (rotating) means such as a stirring bar or a stirring blade.

[0124] <Emulsification process (1)> In the emulsification step (1), an emulsifier and the oil-based solution are mixed in the presence of water to prepare an emulsion.

[0125] In the emulsification step (1), other components that do not fall into any of the categories of water, emulsifier, and oil-based solution may or may not be mixed (blended).

[0126] The other components used in the emulsification step (1) are either or both of the other components contained in the wall material described above and the other components encapsulated in the wall material.

[0127] The emulsifier, the oil-based solution, and the other components used in the emulsification step (1) may each be one type or two or more types, and when two or more types are used, the combination and ratio thereof can be selected arbitrarily.

[0128] In the emulsification step (1), the order in which the above-mentioned raw materials are mixed is not particularly limited. When other components are used in this step, the target and timing of their addition can be adjusted as appropriate.

[0129] In the emulsification step (1), it is preferable to mix the aqueous emulsifier solution with the oil-based solution, and it is more preferable to add the oil-based solution to the aqueous emulsifier solution.

[0130] The concentration of the emulsifier in the aqueous emulsifier solution is not particularly limited, but is preferably 1 to 10% by mass. In this embodiment, the "emulsifier concentration in the aqueous emulsifier solution" means "the ratio of the content (parts by mass) of the emulsifier in the aqueous emulsifier solution to the total mass (parts by mass) of the aqueous emulsifier solution."

[0131] The emulsifier may be a known one and is not particularly limited. Preferred emulsifiers include, for example, polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), ethyl cellulose, methyl cellulose, casein, gum arabic, gelatin, turmeric oil, alkylbenzenesulfonates such as sodium benzenesulfonate and sodium dodecylbenzenesulfonate, polyoxyethylene sulfate, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, and poly(meth)acrylic acid.

[0132] In this specification, the term "(meth)acrylic acid" is a concept that encompasses both "acrylic acid" and "methacrylic acid."

[0133] In the emulsification step (1), the amount of the emulsifier to be added is preferably 0.2 to 2 times by mass the amount of the polyisocyanate compound in the oil-based solution.

[0134] In the emulsification step (1), the emulsifier and the oil-based solution are mixed and emulsified by a mixing method that may be the same as the mixing method in the oil-based solution preparation step (1) described above. The rotation speed of the stirring (rotation) means during emulsification may be, for example, any one of 1000 to 10000 rpm, 2000 to 8000 rpm, 2000 to 4500 rpm, and 4500 to 8000 rpm. The emulsification temperature may be, for example, either 30 to 50°C or 30 to 40°C. The emulsification time may be, for example, either 2 to 20 minutes or 2 to 10 minutes.

[0135] <Encapsulation process (1)> In the encapsulation step (1), the emulsion and a polyamine compound are mixed and polymerized under heating to produce microcapsules. By carrying out this step, the desired microcapsules can be obtained.

[0136] In the encapsulation step (1), other components that do not fall into either the emulsion or the polyamine compound may or may not be mixed (blended).

[0137] The polyamine compound and other components used in the encapsulation step (1) are both as described above. The other components used in this step are either or both of the other components contained in the wall material described above and the other components encapsulated in the wall material.

[0138] The mixture of the emulsion and the polyamine compound to be heated in the encapsulation step (1) is also an emulsion, regardless of whether or not the other components are further mixed therein.

[0139] The emulsion, polyamine compound, and other components used in the encapsulation step (1) may each be one type or two or more types, and when two or more types are used, the combination and ratio thereof can be selected arbitrarily.

[0140] The polyamine compound used in the encapsulation step (1) is preferably one or more selected from the group consisting of the aliphatic polyamine compounds and NH-substituted aliphatic polyamine compounds, and is more preferably linear, regardless of whether or not methylene groups are substituted with imino groups.

[0141] In the encapsulation step (1), the order in which the above-mentioned raw materials are mixed is not particularly limited. When other components are used in this step, the target and timing of their addition can be adjusted as appropriate.

[0142] In the encapsulation step (1), it is preferable to add a polyamine compound to the emulsion.

[0143] In the encapsulation step (1), the mixing (stirring) method for mixing the emulsion and the polyamine compound and carrying out the polymerization reaction may be, for example, the same as the mixing (stirring) method in the oil-based solution preparation step (1) described above.

[0144] When carrying out the polymerization reaction, the heating temperature of the mixture of the emulsion and the polyamine compound is not particularly limited as long as the reaction proceeds normally, but is preferably 65 to 90°C, more preferably 75 to 85°C. The heating time of the mixture during the polymerization reaction is not particularly limited as long as the reaction proceeds normally, but is preferably 1 to 5 hours, more preferably 1.5 to 3 hours.

[0145] In the encapsulation step (1), the amount of polyamine compound is preferably a blending amount that satisfies the multiple of the total content of the biodegradable resin and the lipophilic substance relative to the total content of polyurea and polyurethane in the above-mentioned microcapsules (where the content of polyurethane is 0 parts by mass).

[0146] In the encapsulation step (1), the reaction solution during the polymerization reaction contains at least water derived from the emulsion. The water concentration in the reaction solution during the polymerization reaction in the encapsulation step (1) may be, for example, 75% by mass or less, preferably 62% by mass or less, and may be either 56% by mass or less or 50% by mass or less. The lower the water concentration, the higher the durability of the microcapsules. On the other hand, in terms of improving the handleability of the reaction liquid, the concentration of water is preferably 40% by mass or more.

[0147] In this specification, the water concentration in the reaction liquid during the polymerization reaction, not limited to the case of the encapsulation step (1), means "the ratio of the water content (parts by mass) in the reaction liquid to the total mass of the reaction liquid."

[0148] In the encapsulation step (1), after the polymerization reaction, a dispersion containing microcapsules (for example, an aqueous dispersion using water as a dispersion medium) is obtained. The microcapsules obtained by production method (1) may be used as a dispersion (e.g., an aqueous dispersion) as it is, or the dispersion obtained after performing known post-treatments, purification, etc. may be used as it is, or the dispersion may be used as a single microcapsule (dried product) by removing the dispersion medium after performing known post-treatments, purification, etc. as necessary.

[0149] <<Microcapsule manufacturing method (manufacturing method (2))>> A method for producing microcapsules according to one embodiment of the present invention includes the steps of: preparing an oil-based solution by mixing a lipophilic substance, a biodegradable resin that does not fall under the category of polyol and has a melting point of 100°C or less, and a polyisocyanate compound (sometimes referred to herein as "oil-based solution preparation step (2)"); a step of preparing an emulsion by mixing an emulsifier and the oil-based solution in the presence of water (sometimes referred to as "emulsification step (2)" in this specification); a step of producing microcapsules by carrying out a polymerization reaction between a polyamine compound and the polyisocyanate compound while heating the emulsion (sometimes referred to in this specification as an “encapsulation step (2)”), The polyamine compound is a polyamine compound produced from the polyisocyanate compound in the step of producing the emulsion or thereafter (in this specification, this production method may be referred to as "production method (2)"). The manufacturing method (2) is also an embodiment of the manufacturing method for the microcapsules according to the embodiment of the present invention described above, in which the wall material is polyurea.

[0150] <Oil-based solution preparation process (2)> The oil-based solution preparation step (2) is the same as the oil-based solution preparation step (1) described above. For example, the lipophilic substance used in the oil-based solution preparation step (2) is preferably one or more selected from the group consisting of essential oils and fragrances. The biodegradable resin used in the oil-based solution preparation step (2) is preferably either or both of polycaprolactone and polybutylene succinate, and more preferably polycaprolactone. Further detailed explanation of the oil-based solution preparation step (2) will be omitted.

[0151] <Emulsification process (2)> In the emulsification step (2), an emulsifier and the oil-based solution are mixed in the presence of water to prepare an emulsion. In the emulsification step (2), some polyisocyanate compounds may be hydrolyzed by the coexisting water to convert isocyanate groups (-N=C=O) to amino groups (-NH2). In such cases, a polyamine compound derived from the polyisocyanate compound is produced in which the number of carbon atoms is reduced by the number of isocyanate groups converted to amino groups. Whether or not isocyanate groups can be converted to amino groups depends, for example, on the type of polyisocyanate compound and the conditions of the emulsification step (2). That is, the emulsion prepared in the emulsification step (2) may or may not contain a polyamine compound derived from the polyisocyanate compound in addition to the polyisocyanate compound.

[0152] In order to produce the polyamine compound or increase the amount of the polyamine compound produced in the emulsification step (2), the emulsification conditions may be adjusted to promote hydrolysis of the polyisocyanate compound, for example, by increasing the emulsification temperature or lengthening the emulsification time compared to those in the emulsification step (1). Since the rate of conversion of an isocyanate group to an amino group is usually slow, it is preferable to adjust the emulsification conditions when producing a polyamine compound from a polyisocyanate compound.

[0153] The emulsification step (2) may be the same as the emulsification step (1) described above, except that the emulsification conditions may be different as described above.

[0154] <Encapsulation process (2)> In the encapsulation step (2), the emulsion is heated while a polymerization reaction between the polyamine compound and the polyisocyanate compound is carried out to produce microcapsules. By carrying out this step, the desired microcapsules can be obtained.

[0155] In the encapsulation step (2), a portion of the polyisocyanate compound can be hydrolyzed by the water coexisting therewith, thereby converting the isocyanate groups to amino groups. Since the polyisocyanate compound coexists with water for a longer period of time in the encapsulation step (2) than in the emulsification step (2), unless a special method for promoting the hydrolysis of the polyisocyanate compound in the emulsification step (2) is employed, typically most or all of the polyamine compound that reacts with the polyisocyanate compound will be one that has been produced from the polyisocyanate compound in the steps subsequent to the emulsification step (2), such as the encapsulation step (2).

[0156] Thus, in the case of the production method (2), the polyamine compound that reacts with the polyisocyanate compound in the encapsulation step (2) is a polyamine compound produced from the polyisocyanate compound in the emulsification step (2) or after the emulsification step (2). From the viewpoint of simplifying the entire production method (2), it is preferable to react (polymerize) the polyamine compound produced from the polyisocyanate compound after the emulsification step (2) with the polyisocyanate compound in the encapsulation step (2).

[0157] In the encapsulation step (2), it is preferable that other polyamine compounds than the polyamine compound produced from the polyisocyanate compound are not polymerized with the polyisocyanate compound. To achieve this, it is preferable that the other polyamine compounds are not used in the production method (2), for example, by not mixing the emulsion obtained in the emulsification step (2) with the other polyamine compounds in the encapsulation step (2).

[0158] The encapsulation step (2) may be the same as the encapsulation step (1) described above, except that what is heated to carry out the polymerization reaction is not a mixture (compound) of the emulsion, the polyamine compound, and, if necessary, the other components, but an emulsion containing the above-mentioned polyisocyanate compound and a polyamine compound derived from the polyisocyanate compound. The encapsulation step (2) may be the same as the encapsulation step (1) described above, except that the polyamine compound used in the polymerization reaction is not a separately added compound, but one having a different structure. More specifically, it is as follows.

[0159] For example, in the encapsulation step (2), other components that do not fall under the category of the emulsion may or may not be mixed (blended), and the other components may be either or both of the other components contained in the wall material described above and the other components encapsulated in the wall material.

[0160] For example, in the encapsulation step (2), the content (parts by mass) of the polyamine compound is preferably a content that satisfies the multiple of the total content of the biodegradable resin and the lipophilic substance relative to the total content of the polyurea and polyurethane in the above-mentioned microcapsules (however, in this case, the content of polyurethane is 0 parts by mass).

[0161] For example, in the encapsulation step (2), the reaction solution during the polymerization reaction contains at least water derived from the emulsion. The water concentration in the reaction solution during the polymerization reaction in the encapsulation step (2) may be, for example, 75% by mass or less, preferably 62% by mass or less, and may be either 56% by mass or less or 50% by mass or less. The lower the water concentration, the higher the durability of the microcapsules. On the other hand, in terms of improving the handleability of the reaction liquid, the concentration of water is preferably 40% by mass or more.

[0162] For example, the emulsion and the other components used in the encapsulation step (2) may each be one type or two or more types, and if two or more types are used, the combination and ratio thereof can be selected arbitrarily.

[0163] For example, in the encapsulation step (2), after the polymerization reaction, a dispersion containing microcapsules (for example, an aqueous dispersion using water as a dispersion medium) is obtained. The microcapsules obtained by production method (2) may be used as a dispersion (e.g., an aqueous dispersion) as it is, or the dispersion obtained after performing known post-treatments, purification, etc. may be used as it is, or after performing known post-treatments, purification, etc. as necessary, the dispersion medium may be removed and the microcapsules may be used as a single substance (dried product).

[0164] <<Microcapsule manufacturing method (manufacturing method (3))>> A method for producing microcapsules of the present embodiment in which the wall material is polyurethane includes the steps of: preparing an oil-based solution by mixing a lipophilic substance, a biodegradable resin that does not fall under the category of polyol and has a melting point of 100°C or less, and a polyisocyanate compound (sometimes referred to in this specification as an "oil-based solution preparation step (3)"); a step of preparing an emulsion by mixing an emulsifier and the oil-based solution in the presence of water (sometimes referred to in this specification as an "emulsification step (3)"); and a step of preparing microcapsules by mixing the emulsion with a polyol compound and carrying out a polymerization reaction while heating (sometimes referred to in this specification as "encapsulation step (3)"). (In this specification, this production method is sometimes referred to as "production method (3)").

[0165] The production method (3) may be the same as the production method (1) described above, except that the polyol compound is used instead of the polyamine compound.

[0166] The oil-based solution preparation step (3) is the same as the oil-based solution preparation step (1) described above. The emulsification step (3) is the same as the above-mentioned emulsification step (1).

[0167] The polyol compound used in the encapsulation step (3) is the one described above.

[0168] <<Microcapsule manufacturing method (manufacturing method (4) and manufacturing method (5))>> Among the microcapsules of this embodiment, microcapsules whose wall material is polyurea and polyurethane can be produced by the same production method as the above-mentioned production method (1) (this production method may be referred to herein as "production method (4)") except that a polyamine compound and a polyol compound are used in combination in the encapsulation step (1), or by the same production method as the above-mentioned production method (2) (this production method may be referred to herein as "production method (5)") except that an emulsion and a polyol compound are mixed together in the encapsulation step (2) before the polymerization reaction is carried out.

[0169] That is, the production method (4) includes a step of preparing an oil-based solution by mixing a lipophilic substance, a biodegradable resin that does not fall under the category of polyol and has a melting point of 100°C or less, and a polyisocyanate compound; preparing an emulsion by mixing an emulsifier with the oil-based solution in the presence of water; and mixing the emulsion with a polyamine compound and a polyol compound, and carrying out a polymerization reaction while heating to prepare microcapsules.

[0170] The production method (5) includes a step of preparing an oil-based solution by mixing a lipophilic substance, a biodegradable resin that does not fall under the category of polyol and has a melting point of 100°C or less, and a polyisocyanate compound; preparing an emulsion by mixing an emulsifier with the oil-based solution in the presence of water; and a step of carrying out a polymerization reaction between a polyamine compound or a polyol compound and the polyisocyanate compound while heating the emulsion to produce microcapsules, The polyamine compound is a polyamine compound produced from the polyisocyanate compound in the step of producing the emulsion or thereafter.

[0171] In the production methods (4) and (5), the amount of polyol compound used may be adjusted appropriately taking into consideration the amount of polyurethane in the desired wall material.

[0172] <<Composition>> A composition according to one embodiment of the present invention contains the microcapsules according to one embodiment of the present invention described above. The composition of the present embodiment can be used as a final product itself, or can be used as a raw material for obtaining a final product. The form of the composition of the present embodiment can be selected arbitrarily depending on the purpose.

[0173] The composition may or may not contain other components in addition to the microcapsules, but it is preferable that the composition contains other components in order to improve the versatility of the composition.

[0174] The other components contained in the composition can be selected arbitrarily depending on the purpose and are not particularly limited.

[0175] The microcapsules and other components contained in the composition may each be of one type or two or more types, and when two or more types are contained, the combination and ratio thereof can be selected arbitrarily.

[0176] For example, the composition (ie, resin composition) containing, as the other component, a resin of a type different from the constituent material of the wall material in the microcapsules is suitable as a molding material for forming a molded article. The resin is preferably a thermoplastic resin. In the resin composition, the content of the microcapsules relative to the total mass of the resin composition is preferably 10 to 90 mass%, and may be, for example, any one of 40 to 90 mass%, 70 to 90 mass%, 10 to 60 mass%, 10 to 30 mass%, and 40 to 60 mass%. The resin composition can be produced by, for example, blending the microcapsules, the resin, and, if necessary, other components other than the resin, and can be produced in the same manner as in the case of known resin compositions, except for the use of these specific raw materials. The microcapsules may be blended alone, or may be blended as a mixture of the dispersion or the like in the final state at the time of production.

[0177] The molded article may be, for example, a film, sheet, plate, rod, block, sphere, cylinder, irregular shape, or a composite shape combining two or more of these shapes. The surface of the molded article may be either flat or curved (convex or concave).

[0178] For example, the composition (that is, the liquid composition) containing a surfactant, particularly a cationic surfactant, and water as the other components is suitable as a fabric softener. In the liquid composition, the content of the microcapsules relative to the total mass of the liquid composition is preferably 0.01 to 10% by mass, and more preferably 0.1 to 5% by mass. The liquid composition can be produced by, for example, blending the microcapsules, the surfactant, water, and, if necessary, other components, and can be produced in the same manner as known liquid compositions, except for the use of these specific raw materials. The microcapsules may be blended alone, or may be blended as a mixture of the dispersion or the like in the final state at the time of production.

[0179] <<Composite material>> Both the microcapsules and the composition may be composite materials with other additional components. The composite material may include, for example, a material including a substrate and the microcapsules or composition provided somewhere on the substrate. The material of the substrate can be appropriately selected from known materials such as resin, metal, paper, and wood depending on the purpose. The shape of the substrate may be the same as that of the molded product. [Example]

[0180] The present invention will be described in more detail below with reference to specific examples, although the present invention is not limited to the examples shown below.

[0181] The various raw materials used in the following examples and comparative examples are shown below. [Polyisocyanate compound (a)] (a)-1: Trimethylolpropane adduct of tolylene-2,4-diisocyanate ("Takenate (registered trademark) D-103" manufactured by Mitsui Chemicals, Inc.) (a)-2: Trimethylolpropane adduct of xylylene-1,3-diisocyanate ("Takenate (registered trademark) D-110N" manufactured by Mitsui Chemicals, Inc.) (a)-3: Trimethylolpropane adduct of 1,3-bis(isocyanatomethyl)cyclohexane ("Takenate (registered trademark) D-120N" manufactured by Mitsui Chemicals, Inc.) (a)-4: Polymeric MDI ("Millionate MR-200" manufactured by Tosoh Corporation, NCO content 31.3% by mass) (a)-5: Trimethylolpropane adduct of hexamethylene diisocyanate ("Takenate (registered trademark) D-160N" manufactured by Mitsui Chemicals, Inc.) [Polyamine compound (b)] (b)-1: N,N'-bis(3-aminopropyl)ethylenediamine (BAEA, manufactured by Tokyo Chemical Industry Co., Ltd.) (b)-2: Diethylenetriamine (DETA, manufactured by Tokyo Chemical Industry Co., Ltd.) (b)-3: 1,3-diaminopropane (DAP, manufactured by Tokyo Chemical Industry Co., Ltd.) (b)-4: 4,4'-methylenebis(cyclohexylamine) (MCA, manufactured by Tokyo Chemical Industry Co., Ltd.) (b)-5: p-xylylenediamine (XDA, manufactured by Tokyo Chemical Industry Co., Ltd.) [Biodegradable resin (c) with a melting point of 100°C or less] (c)-1: Polycaprolactone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., melting point 60°C, weight-average molecular weight approximately 10,000) [Lipophilic substance (d)] (d)-1: Lavender oil (ASH AROMA, SP value 9.3, main components: linalool (SP value 10), linalyl acetate (SP value 8.5)) (d)-2: Tea tree oil (manufactured by Air Green, SP value 9.7, main components: terpinen-4-ol (SP value 10.9), γ-terpinene (SP value 8.5)) (d)-3: Hinoki cypress oil (manufactured by Seikatsu no Ki Co., Ltd., SP value 9.9, main components: α-pinene (SP value 9), δ-cadinol (SP value 10.7)) [Emulsifier (e)] (e)-1: Polyvinyl alcohol (PVA, "JP-24" manufactured by Nippon Vinyl Acetate & Poval Co., Ltd., saponification degree: 87-89) (e)-2: Polyvinyl alcohol (PVA, Kuraray Co., Ltd. "Kuraray Poval (registered trademark) 5-88") [Other biodegradable resins (c0)] (c0)-1: Polycaprolactone diol (Daicel Corporation "PLACCEL240", melting point 48 to 58°C)

[0182] [Example 1] <<Production of Microcapsules (Production Method (2))>> Biodegradable resin (c)-1 (15 g) was heated to 70 to 80° C. and melted. The entire amount of the melted biodegradable resin (c)-1 was mixed with the lipophilic substance (d)-1 (15 g) and stirred until the mixture became homogeneous. The resulting mixture was allowed to cool at room temperature until its temperature reached 35°C. The entire amount of the stirred product after cooling was mixed with polyisocyanate compound (a)-1 (3.1 g) at room temperature, and the mixture was stirred until it became homogeneous, thereby preparing an oil-based solution (oil-based solution preparation step). The entire amount of the oil-based solution was added to an aqueous solution (120 g) containing emulsifier (e)-1 at a concentration of 4% by mass, and the resulting mixture was stirred at 3,500 rpm and 40°C for 5 minutes using an emulsifier (manufactured by Primix Corporation) to produce an emulsion (emulsification step). This emulsion was stirred at room temperature for 2 hours while being heated to 80°C, and a polymerization reaction between the polyamine compound produced from the polyisocyanate compound and the polyisocyanate compound was carried out to produce microcapsules composed of a polyurea-based wall material encapsulating a biodegradable resin (c)-1 and a lipophilic substance (d)-1 as core materials, and a dispersion containing these microcapsules was obtained (encapsulation step). The water concentration in the reaction solution during the polymerization reaction was 71% by mass.

[0183] <<Evaluation of Microcapsules>> <Evaluation of Microcapsule Durability (1)> [Production of microcapsules for evaluation (production method (2))] A color developer (6'-(diethylamino)-1',3'-dimethylspiro[isobenzofuran-1(3H),9'-(9H)xanthene]-3-one, CAS No.: 21934-68-9, "ORANGE300" manufactured by Fukui Yamada Chemical Co., Ltd. (0.45 g) was added to lipophilic substance (d)-1 (15 g), and the mixture was heated to 80°C to dissolve. The entire amount of the resulting solution was used in place of lipophilic substance (d)-1 (15 g), and a dispersion for evaluation containing microcapsules for evaluation was obtained in the same manner as for the microcapsules described above. These microcapsules for evaluation contained biodegradable resin (c)-1 as a core material, lipophilic substance (d)-1, and the color developer.

[0184] [Evaluation of Microcapsule Durability (1)] A fabric softener (Kao Corporation's "IROKA Naked Lily Scent," liquid at room temperature) (88.2 g), the dispersion for evaluation, and distilled water were mixed to a total weight of 100 g. The amounts of the dispersion for evaluation and distilled water used were adjusted so that the ratio of the amount of color developer in the microcapsules for evaluation to the total weight of the mixture (100 g) was 0.2 mass %. More specifically, the fabric softener (88.2 g), the dispersion for evaluation (2.0 g), and distilled water (9.8 g) were mixed.

[0185] The resulting mixture was then stored at 23°C. After 24 hours and 168 hours from the start of the static storage, a first sample (3.5 mL) was collected from the mixed solution and filtered using a syringe filter. Furthermore, acetic acid (0.3 mL) was added to the filtered first sample (3 mL) to prepare a second sample. The second sample was placed in a disposable cell, and the absorbance A of the second sample at a wavelength of 500 nm was measured using an ultraviolet-visible absorption spectrophotometer (JASCO Corporation, "V-770"). 24 and A 168 was measured. Furthermore, the mixture after 168 hours of static storage was stored at a temperature of 80°C for 72 hours, and a first sample (3.5 mL) was collected from the mixture after static storage under this heated condition. Thereafter, the first sample was filtered and a second sample was prepared in the same manner as above, and the absorbance A of this second sample at a wavelength of 500 nm was measured. Z was measured. Then, according to the formula (i), A 24 and A Z The remaining core material rate (1) in the evaluation microcapsules after 24 hours of static storage was calculated from the above data. 168 and A Z The core substance remaining rate (1) in the evaluation microcapsules after 168 hours of static storage was calculated from the above data. The results are shown in the column "Core substance remaining rate (1) (%)" in Table 1.

[0186] <Measurement of the average particle size of microcapsules> The average particle size of the microcapsules was measured using a particle size distribution analyzer (Malvern Instruments' "Mastersizer 3000") and the dispersion containing the microcapsules obtained above. The results are shown in Table 1.

[0187] <<Production of Microcapsules (Production Method (2)) and Evaluation>> [Examples 2 to 3] Microcapsules were produced and evaluated in the same manner as in Example 1, except that the amount of polyisocyanate compound (a)-1 used was 6.2 g (Example 2) or 9.3 g (Example 3) instead of 3.1 g. The results are shown in Table 1.

[0188] [Example 4] <<Production of Microcapsules (Production Method (1))>> An oil-based solution was prepared in the same manner as in Example 1 (oil-based solution preparation step). The entire amount of the oil-based solution was added to an aqueous solution (120 g) containing emulsifier (e)-1 at a concentration of 4% by mass, and the resulting mixture was stirred by a rotary means using an emulsifier (manufactured by Primix Corporation) at a rotation speed of 3500 rpm and 35°C for 5 minutes to produce an emulsion (emulsification step). At room temperature, polyamine compound (b)-1 (0.8 g) was added to the entire amount of this emulsion, and the resulting mixture was stirred for 2 hours while being heated at 80°C to carry out a polymerization reaction, thereby producing microcapsules, and a dispersion containing these microcapsules was obtained (encapsulation process).

[0189] <<Evaluation of Microcapsules>> The obtained microcapsules were evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0190] <<Production of Microcapsules (Production Method (1)) and Evaluation>> [Examples 5 to 8] Microcapsules were produced and evaluated in the same manner as in Example 4, except that polyamine compound (b)-2 (0.5 g) (Example 5), polyamine compound (b)-3 (0.4 g) (Example 6), polyamine compound (b)-4 (1 g) (Example 7), or polyamine compound (b)-5 (0.7 g) (Example 8) was used instead of polyamine compound (b)-1 (0.8 g). The results are shown in Table 1 or Table 2.

[0191] [Examples 9 to 10] Microcapsules were produced and evaluated in the same manner as in Example 4, except that the amount of polyisocyanate compound (a)-1 used was changed from 3.1 g to 6.2 g (Example 9) or 9.3 g (Example 10), and the amount of polyamine compound (b)-1 used was changed from 0.8 g to 1.7 g (Example 9) or 2.5 g (Example 10). The results are shown in Table 2.

[0192] [Examples 11 to 13] Microcapsules were produced and evaluated in the same manner as in Example 4, except that polyisocyanate compound (a)-2 (10.5 g) (Example 11), polyisocyanate compound (a)-3 (11 g) (Example 12), or polyisocyanate compound (a)-4 (1.3 g) (Example 13) was used instead of polyisocyanate compound (a)-1 (3.1 g). The results are shown in Table 2.

[0193] [Examples 14 to 15] Microcapsules were produced and evaluated in the same manner as in Example 10, except that lipophilic substance (d)-2 (15 g) (Example 14) or lipophilic substance (d)-3 (15 g) (Example 15) was used instead of lipophilic substance (d)-1 (15 g). The results are shown in Table 2 or Table 3.

[0194] [Examples 16 to 18] Instead of the aqueous solution (120 g) containing emulsifier (e)-1 at a concentration of 4% by mass, an aqueous solution (80 g) containing emulsifier (e)-1 at a concentration of 6.4% by mass (Example 16), an aqueous solution (60 g) containing emulsifier (e)-2 at a concentration of 8% by mass (Example 17), or an aqueous solution (40 g) containing emulsifier (e)-2 at a concentration of 8% by mass (Example 18) was used. Microcapsules were produced and evaluated in the same manner as in Example 10. The water concentration in the reaction solution during the polymerization reaction was 61.5% by mass (Example 16), 54% by mass (Example 17), or 45% by mass (Example 18). The results are shown in Table 3.

[0195] Furthermore, in Example 18, the cut surfaces of the microcapsules were observed according to the following procedure. That is, the microcapsules in the obtained dispersion were filtered and dried to be extracted. The obtained microcapsules were embedded in a resin, and then the microcapsules together with the resin were cross-sectioned using an ultramicrotome to form a cut surface on the microcapsules. The cross-sections of the microcapsules were observed using an optical microscope (Olympus BX53M) with epi-illumination at 1500x magnification. As a result, most of the internal space of the microcapsules was filled with a solid material, which was presumed to be biodegradable resin (c)-1. The cross-sections of the solid material were uniform immediately after formation, but the area of ​​a white region reflecting light increased over time. These white regions were presumed to be lipophilic substance (d)-1 oozing out of the solid material. In other words, the microcapsules obtained above contained one core material, the solid biodegradable resin (c)-1, and the other core material, the lipophilic substance (d)-1, in the form of minute droplets, highly dispersed within the solid biodegradable resin (c)-1. It was presumed that the biodegradable resin (c)-1 and lipophilic substance (d)-1 in this state were encapsulated within a wall material composed of polyurea. The image data of the cross section of the microcapsule obtained at this time is shown in FIG.

[0196] <<Production and evaluation of comparative microcapsules>> [Comparative Example 1] Biodegradable resin (c)-1 (15 g) was heated to 70 to 80° C. and melted. The entire amount of the melted biodegradable resin (c)-1 was mixed with lipophilic substance (d)-1 (15 g) and stirred until the mixture became homogeneous, thereby preparing an oil-based solution. The entire amount of the oil-based solution was added to an aqueous solution (120 g) containing emulsifier (e)-1 at a concentration of 4% by mass, and the resulting mixture was stirred by a rotary means using an emulsifier (manufactured by Primix Corporation) at a rotation speed of 6,500 rpm and 50°C for 5 minutes to produce an emulsion. This emulsion was stirred at room temperature for 30 minutes while being rapidly cooled in an ice bath to precipitate biodegradable resin (c)-1. As a result, comparative microcapsules were obtained, each having a wall material containing biodegradable resin (c)-1 as a constituent component and a lipophilic substance (d)-1 encapsulated as a core substance. These microcapsules were evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0197] Comparative Example 2 Comparative microcapsules were produced and evaluated in the same manner as in Example 3, except that biodegradable resin (c)-1 (15 g) was replaced with another biodegradable resin (c0)-1 (15 g). The results are shown in Table 3.

[0198] [Table 1]

[0199] [Table 2]

[0200] [Table 3]

[0201] As is clear from the above results, in the microcapsules of Examples 1 to 18, the core substance residual rate (1) after 24 hours was 47.3% or more (47.3 to 99.5%), and the microcapsules of Examples 1 to 18 were made using biodegradable resin (c)-1 and had sufficient durability.

[0202] The core substance remaining rate (1) of the microcapsules after 168 hours was 3.4% or more (3.4 to 99.1%) in Examples 1 to 18.

[0203] A comparison of Examples 4 to 6 with Examples 7 and 8 revealed that when the polyamine compound (b) was chain-like, the core substance residual rate (1) tended to be higher both after 24 hours and after 168 hours (especially after 168 hours) than when the polyamine compound (b) had a cyclic structure.

[0204] Furthermore, when the polyamine compound (b) is chain-like, Examples 4 to 6 showed that the greater the total number of amino groups (-NH2) and imino groups (-NH-) in one molecule of the polyamine compound (b) (number of imino groups), the higher the core substance residual rate (1) both after 24 hours and after 168 hours.

[0205] From Examples 4, 9 and 10, it was observed that the greater the amount of polyisocyanate compound (a) and polyamine compound (b) used, the higher the core substance residual rate (1) was, both after 24 hours and after 168 hours.

[0206] It was confirmed from Examples 10 to 13 that there was no significant change in the core substance remaining rate (1) (durability of the microcapsules) after 24 hours even when the type of polyisocyanate compound (a) was different. However, the core substance remaining rate (1) after 168 hours of the microcapsules was higher in Examples 10 to 12 than in Example 13. In Example 13, foaming was observed in the reaction solution during the polymerization reaction, and it was presumed that polyisocyanate compound (a)-4 was highly reactive and part of it decomposed during the polymerization reaction.

[0207] From Examples 10, 14 and 15, it was confirmed that even if the type of lipophilic substance (d) was different, there was no significant change in the core substance residual rate (1) of the microcapsules after 24 hours or 168 hours.

[0208] From Examples 10 and 16 to 18, it was observed that the lower the water concentration during the polymerization reaction, the higher the core substance remaining rate (1) of the microcapsules both after 24 hours and after 168 hours. In particular, in Examples 16 to 18, the core substance remaining rate (1) was high, and the water concentration was 71 mass % in Example 10, but 61.5 mass % or less (45 to 61.5 mass %) in Examples 16 to 18.

[0209] It was confirmed from Examples 1 to 18 that microcapsules having sufficient durability could be obtained by either production method (1) or (2). A comparison of Examples 1 to 3 with Examples 4, 9, and 10 showed that production method (1) tended to produce microcapsules with higher durability than production method (2).

[0210] The core substance remaining rate (1) of the microcapsules after 24 hours was 86.2% or more (86.2 to 99.5%) in Examples 4, 5, and 9 to 18, which was higher than the previous figure. This indicates that the durability of the microcapsules tends to be higher by adopting manufacturing method (1) and selecting a chain compound having an imino group in addition to an amino group as the polyamine compound (b).

[0211] The core substance remaining rate (1) of the microcapsules after 168 hours was 31.8% or more (31.8 to 99.1%) in Examples 4 to 6 and 9 to 18, which was higher than the previous figure. This indicates that the use of manufacturing method (1) and the selection of a chain compound as polyamine compound (b) tended to increase the durability of the microcapsules over a longer period of time. Furthermore, the use of a compound having an imino group in addition to an amino group as the chain polyamine compound (b) further enhanced this tendency. For example, the core substance remaining rate (1) of the microcapsules after 168 hours was 58.7% or more (58.7 to 99.1%) in Examples 4 to 5 and 9 to 18.

[0212] In Examples 1 to 18, the average particle size of the microcapsules was 11.5 to 16.1 μm.

[0213] On the other hand, in Comparative Example 1, microcapsules were produced, but their durability was insufficient. In Comparative Example 1, the core substance remaining rate (1) of the microcapsules after 24 hours was already 0%, so the core substance remaining rate (1) after 168 hours was not calculated. In the microcapsules of Comparative Example 1, the wall material was neither polyurea nor polyurethane.

[0214] In Comparative Example 2, microcapsules were also produced, but their durability was insufficient. In Comparative Example 2, another biodegradable resin (c0)-1 (polycaprolactone diol) was used as the biodegradable resin to be encapsulated in the wall material. However, a portion of this resin reacted with the polyisocyanate compound (a)-1 to form polyurethane, which, together with the polyurea formed by the reaction of the polyisocyanate compound (a)-1 with the polyamine compound derived therefrom, constituted the wall material, presumably making it easier for the core substance to be released outside the capsule.

[0215] [Example 19] <<Production of Microcapsules (Production Method (1))>> Biodegradable resin (c)-1 (15 g) was heated to 70 to 80° C. and melted. The entire amount of the melted biodegradable resin (c)-1 was mixed with the lipophilic substance (d)-1 (15 g) and stirred until the mixture became homogeneous. The resulting mixture was allowed to cool at room temperature until its temperature reached 35°C. The entire amount of the stirred product after cooling was mixed with polyisocyanate compound (a)-5 (2.9 g) at room temperature, and the mixture was stirred until it became homogeneous, thereby preparing an oil-based solution (oil-based solution preparation step). The entire amount of the oil-based solution was added to an aqueous solution (120 g) containing emulsifier (e)-1 at a concentration of 4% by mass, and the resulting mixture was stirred at 7000 rpm and 35°C for 5 minutes using an emulsifier (manufactured by Primix Corporation) to produce an emulsion (emulsification step). At room temperature, polyamine compound (b)-1 (0.8 g) was added to the entire amount of this emulsion, and the resulting mixture was stirred for 2 hours while being heated at 80°C to carry out a polymerization reaction, thereby producing microcapsules, and a dispersion containing these microcapsules was obtained (encapsulation process).

[0216] <<Evaluation of Microcapsules>> <Evaluation of Microcapsule Durability (2)> The dispersion containing the microcapsules obtained above was mixed with distilled water to a total amount of 100 g. The amounts of the dispersion and distilled water used were adjusted so that the ratio of the amount of lipophilic substance (d)-1 in the dispersion to the total mass (100 g) of the mixture was 0.2 mass %.

[0217] Next, three samples (5 mL) were immediately collected from the resulting mixture, and the third sample was filtered using a membrane filter to collect the insoluble matter in the third sample. This insoluble matter was presumed to be microcapsules from which the core substance had not been released. The insoluble matter was then washed with distilled water. The membrane filter after washing the insoluble matter was immersed in ethanol (20 mL) and irradiated with ultrasound in this state to obtain an ethanol mixture. The supernatant was collected from the resulting ethanol mixture and analyzed using a gas chromatograph mass spectrometer (JEOL Ltd., "JMS-Q1500GC") to quantify the amount of lipophilic substance (d)-1 extracted from the insoluble matter, C0.

[0218] Next, the mixture after collecting the third sample was left to stand at a temperature of 23° C. After 24 hours and 168 hours from the start of the standing, fourth samples (5 mL) were collected from the mixture, and the amount C of lipophilic substance (d)-1 extracted from the insoluble matter was measured for these fourth samples in the same manner as for the third sample. 24 and C 168 was quantified. Then, according to the formula (ii), C 24 From C0 and C1, the remaining core substance rate (2) in the evaluation microcapsules after 24 hours of static storage was calculated, and C 168 The core substance remaining rate (2) in the evaluation microcapsules after 168 hours of static storage was calculated from C0 and C0. The results are shown in the column "Core substance remaining rate (2) (%)" in Table 4.

[0219] <Evaluation of biodegradability of biodegradable resins> The resulting dispersion containing the microcapsules was filtered using a membrane filter, and the insoluble matter (microcapsules) was collected on the membrane filter. The insoluble matter was washed multiple times with distilled water to remove water-soluble components. Ethanol was added to the washed insoluble matter, and the lipophilic substance (d)-1 was extracted from the insoluble matter into ethanol by further irradiating it with ultrasound. The remaining resin component (the resin component that constituted the microcapsules) was dried at room temperature. An inoculum was prepared by adding an inoculum preparation (BI-CHEM BOD Seed, manufactured by Kanto Chemical Co., Ltd.) to water collected from a river. This inoculum and the dried material obtained above were placed in a bottle to construct a BOD meter (OxiTop-IDS A12, manufactured by WTW Co., Ltd.), and a measuring head equipped with a pressure sensor was attached to construct the BOD meter. This BOD meter was then stored at 22°C for 60 days while stirring the contents. The BOD value was then measured, and the degree of biodegradation of the resin component was calculated. The results are shown in Table 4 in the column "Biodegradability after 60 days (%)." The test for calculating the biodegradability of biodegradable resins is similar to the biodegradability test in accordance with OECD 301F, except that the microbial concentration may be outside the specified range.

[0220] <Measurement of the average particle size of microcapsules> Using the dispersion liquid containing the microcapsules obtained above, the average particle size of the microcapsules was measured in the same manner as in Example 1. The results are shown in Table 4.

[0221] <<Production of Microcapsules (Production Method (1)) and Evaluation>> [Example 20] Microcapsules were produced and evaluated in the same manner as in Example 19, except that the amount of polyisocyanate compound (a)-5 used was changed from 2.9 g to 8.2 g, and the amount of polyamine compound (b)-1 used was changed from 0.8 g to 2.2 g. The results are shown in Table 4.

[0222] [Example 21] Microcapsules were produced and evaluated in the same manner as in Example 19, except that polyisocyanate compound (a)-1 (1.4 g) was used instead of polyisocyanate compound (a)-5 (2.9 g) and the amount of polyamine compound (b)-1 used was changed from 0.8 g to 0.4 g. The results are shown in Table 4. Furthermore, in this example, the above-mentioned "Evaluation of Microcapsule Durability (1)" was also carried out. The results are shown in Table 4 in the column "Core Substance Residual Rate (1) (%)".

[0223] [Example 22] Microcapsules were produced and evaluated in the same manner as in Example 19, except that polyisocyanate compound (a)-1 (2.8 g) was used instead of polyisocyanate compound (a)-5 (2.9 g). The results are shown in Table 4.

[0224] <<Evaluation of biodegradability of biodegradable resins>> [Example 18] The microcapsules obtained in Example 18 were additionally evaluated for biodegradability of the biodegradable resin in the same manner as in Example 19. The results are shown in Table 4.

[0225] [Table 4]

[0226] As is clear from the above results, in the microcapsules of Examples 19 to 22, the core substance residual rate (2) after 24 hours was 63.7% or more (63.7 to 85%), and the microcapsules of Examples 19 to 22 were made using biodegradable resin (c)-1 and had sufficient durability.

[0227] The core substance remaining rate (2) of the microcapsules after 168 hours was 41.5% or more (41.5 to 64.7%) in Examples 19 to 22.

[0228] In Example 21, the core substance residual ratios (2) after 24 hours and 168 hours were lower than the core substance residual ratios (1) after 24 hours and 168 hours, respectively, and it was presumed that this trend was not limited to Example 21 but also applied to other Examples. Therefore, in Examples 19, 20, and 22, in which the core substance residual ratios (2) after 24 hours and 168 hours were all higher than Example 21, the core substance residual ratios (1) after 24 hours and 168 hours were higher than the core substance residual ratio (2) of 41.5% after 168 hours in Example 21, and it was determined that the durability of the microcapsules was relatively high. The core substance remaining ratios (1) after 24 hours and 168 hours in Example 21 were within the ranges of the core substance remaining ratios (1) after 24 hours and 168 hours in Examples 1 to 18, respectively.

[0229] In Examples 19 to 22, the average particle size of the microcapsules was 13.4 to 18.5 μm, and in Examples 1 to 22, the average particle size of the microcapsules was 11.5 to 18.5 μm.

[0230] In the microcapsules of Examples 19 to 22, the biodegradability of the resin component after 60 days was 42.5% or more (42.5 to 58.7%), which indicated that the biodegradability of the resin component was high and that the biodegradation of the biodegradable resin (c) progressed well. Furthermore, when the biodegradability of a resin component known to be highly biodegradable was checked separately after 60 days, it was found to be approximately 40%.

[0231] In particular, Examples 19-20 tended to have a higher degree of biodegradability after 60 days than Examples 21-22. The polyisocyanate compound (a) used in the microcapsules of Examples 19 and 20 was an aliphatic polyisocyanate compound, whereas in the microcapsules of Examples 21 and 22 it was an aromatic polyisocyanate compound. The mass ratio of [polyurea content (parts by mass) in the microcapsules]:[biodegradable resin (c) content (parts by mass) in the microcapsules] was 16.3:83.7 to 35.7:64.3 in the microcapsules of Examples 19 and 20, and 8.7:91.3 to 16:84 in the microcapsules of Examples 21 and 22.

[0232] In the microcapsules of Example 18, the degree of biodegradation of the resin component after 60 days was low, but the biodegradability of the resin component was confirmed. [Industrial Applicability]

[0233] The present invention can be used as microcapsules that encapsulate lipophilic substances such as insecticides, insect repellents, and fragrances as core materials, and is suitable, for example, as microcapsules for imparting fragrance to fabric softeners.

Claims

1. A microcapsule formed by encapsulating a core substance in a wall material, The wall material is made of either or both of polyurea and polyurethane, The microcapsules, wherein the core material is a lipophilic substance and a biodegradable resin that does not fall under the category of polyol and has a melting point of 100°C or less.

2. 2. The microcapsule according to claim 1, wherein the polyurea is a polymer of a polyisocyanate compound and a polyamine compound derived from the polyisocyanate compound.

3. 2. The microcapsule according to claim 1, wherein the polyurea is a polymer of a polyisocyanate compound and a chain polyamine compound.

4. The microcapsule according to any one of claims 1 to 3, wherein the lipophilic substance is one or more selected from the group consisting of essential oils and fragrances.

5. The microcapsules according to any one of claims 1 to 3, wherein the biodegradable resin is polycaprolactone.

6. The microcapsule according to claim 4, wherein the biodegradable resin is polycaprolactone.

7. the polyisocyanate compound is an aliphatic polyisocyanate compound, The mass ratio of [content (parts by mass) of the polyurea in the microcapsules]: [content (parts by mass) of the biodegradable resin in the microcapsules] is 10:90 to 40:

60. The microcapsules according to claim 3.

8. The microcapsule according to claim 7, wherein the biodegradable resin is polycaprolactone.

9. the polyisocyanate compound is an aromatic polyisocyanate compound, The mass ratio of [content (parts by mass) of the polyurea in the microcapsules]: [content (parts by mass) of the biodegradable resin in the microcapsules] is 5:95 to 20:

80. The microcapsules according to claim 3.

10. The microcapsule according to claim 9, wherein the biodegradable resin is polycaprolactone.

11. A composition comprising the microcapsules of claim 1, 2, 3, 7, 8, 9 or 10.

12. A step of preparing an oil-based solution by mixing a lipophilic substance, a biodegradable resin that does not fall under the category of polyol and has a melting point of 100°C or less, and a polyisocyanate compound; preparing an emulsion by mixing an emulsifier with the oil-based solution in the presence of water; and a step of carrying out a polymerization reaction between the polyamine compound and the polyisocyanate compound while heating the emulsion to produce microcapsules, The method for producing microcapsules, wherein the polyamine compound is a polyamine compound produced from the polyisocyanate compound in the step of producing the emulsion or thereafter.

13. A step of preparing an oil-based solution by mixing a lipophilic substance, a biodegradable resin that does not fall under the category of polyol and has a melting point of 100°C or less, and a polyisocyanate compound; preparing an emulsion by mixing an emulsifier with the oil-based solution in the presence of water; and mixing the emulsion with a polyamine compound and carrying out a polymerization reaction while heating to produce microcapsules.

14. The method for producing microcapsules according to claim 13, wherein the polyamine compound is linear.

15. The method for producing microcapsules according to any one of claims 12 to 14, wherein the lipophilic substance is one or more selected from the group consisting of essential oils and fragrances.

16. The method for producing microcapsules according to any one of claims 12 to 14, wherein the biodegradable resin is polycaprolactone.

17. The method for producing microcapsules according to claim 15, wherein the biodegradable resin is polycaprolactone.

18. The method for producing microcapsules according to any one of claims 12 to 14, wherein the concentration of water in the reaction solution during the polymerization reaction is 62 mass% or less.

19. The method for producing microcapsules according to claim 15, wherein the concentration of water in the reaction solution during the polymerization reaction is 62% by mass or less.

20. The method for producing microcapsules according to claim 16, wherein the concentration of water in the reaction solution during the polymerization reaction is 62% by mass or less.

21. The method for producing microcapsules according to claim 17, wherein the concentration of water in the reaction solution during the polymerization reaction is 62% by mass or less.

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