JP5953181B2 - Structural color developing composition and structural color developing film - Google Patents

Description

  The present invention relates to a structural color developing composition and a structural color developing film.

  It is known that a coating film in which particles having a uniform shape and size are regularly arranged three-dimensionally selectively reflects light in a specific wavelength region by Bragg reflection. In particular, when the particle interval is in the wavelength range of visible light, the structural color can be visually confirmed. This structural color has the feature that the hue changes depending on the viewing angle. In addition, structural colors exhibit color effects different from those of pigments and pigments, and because they do not fade, they are expected to be applied to coloring materials, photonic crystals, optical sensors, optical filters, etc. Methods for producing the body and coatings containing it have been studied.

  Patent Document 1 discloses a structural color coating film-forming coating composition mainly composed of acrylic resin core-shell particles. Patent Document 1 describes that when this coating composition is formed into a coating film, the core portion is regularly arranged in the shell portion, and the regular arrangement of the core portion exhibits a structural color. .

  Further, in Patent Document 2, a structural color display layer, which is composed of structural color particles and a matrix, is formed on the surface of a sheet-like structural color display layer support having an adhesive layer provided on the back surface. The structural color display material is disclosed, and it is described that it can be stored in a state of being wound in a roll shape.

JP 2009-249527 A JP 2011-104931 A

  However, in the coating film obtained from the coating composition described in Patent Document 1, sufficient flexibility may not be obtained, and problems such as cracking may occur when bent.

  Further, the structural color display layer described in Patent Document 2 requires a step of pouring a flexible resin serving as a stationary phase after arranging structural color fine particles in advance, so that the working efficiency is poor and the resin is poured. In this case, there is a problem that the arrangement of the coloring members is disturbed and the structural color is not clear. Furthermore, since the structural color display material is in the form of a sheet, its use is limited.

  INDUSTRIAL APPLICABILITY The present invention provides a structural color developing film that is excellent in flexibility and can maintain a clear structural color even when bent, and can easily form the structural color developing film on an object to be coated having various shapes. It is an object of the present invention to provide a composition for expressing a structural color.

  The present inventors made the shell part of the copolymer particles having a core-shell structure contain a resin crosslinked with a conjugated diene, and further set the number average particle diameter of the copolymer particles within a predetermined range. It has been found that a composition for expressing a structural color that solves the above-mentioned problems can be obtained by using the inside, and the present invention has been achieved.

That is, the present invention is as follows.
[1] A composition containing copolymer particles having a core-shell structure, which contains a resin (a) in which the shell portion of the copolymer particles is crosslinked with a conjugated diene, and the number of the copolymer particles A composition for expressing a structural color, having an average particle diameter of 0.05 μm or more and 1 μm or less, and a difference in refractive index between the core part and the shell part in the copolymer particles of 0.01 or more.
[2] The core part of the copolymer particle contains a resin (b-1) crosslinked with a crosslinkable monomer having two or more non-conjugated double bonds in one molecule, and the resin (B-1) includes a structural unit derived from the crosslinkable monomer in a proportion of 0.01% by mass or more and 6.2% by mass or less based on the total amount of the resin (b-1). [1] The structural color developing composition according to [1].
[3] The core part of the copolymer particles contains a resin (b-2) crosslinked with a conjugated diene, and the resin (b-2) is a structural unit derived from the conjugated diene. The composition for expressing a structural color according to the above [1], which is contained at a ratio of 0.01% by mass or more and 50% by mass or less based on the total amount of (b-2).
[4] The above [1] to [3], wherein the total amount of the shell part in the copolymer particles is a ratio of 30% by mass to 95% by mass based on the total amount of the copolymer particles. The composition for expression of structural color as described.
[5] The structural color developing composition according to any one of [1] to [4], further including a dispersion medium in which the copolymer particles are dispersed.
[6] A structural color developing film formed from the structural color developing composition according to any one of [1] to [5].
[7] The structural color developing film according to [6], including a matrix material containing the resin (a) and core particles derived from the core part dispersed in the matrix material.

  According to the present invention, a structural color developing film that is excellent in flexibility and can maintain a clear structural color even when bent, and the structural color developing film can be easily formed on an object to be coated in various shapes. A possible composition for expressing the structural color can be provided.

It is a schematic diagram which shows one aspect | mode of the structural color expression composition and structural color expression film | membrane of this invention.

  A preferred embodiment of the present invention will be described below.

(Copolymer particles)
The copolymer particles according to this embodiment have a core-shell structure. Here, “having a core-shell structure” can be rephrased as “having a core portion and a shell portion covering the core portion”.

  In this embodiment, the shell part of the copolymer particles is a resin crosslinked with a conjugated diene (hereinafter, sometimes referred to as “resin (a)”. In this specification, the resin includes a so-called rubber component). Containing. In this embodiment, the number average particle diameter of the copolymer particles is 0.05 μm or more and 1 μm or less, and the difference in refractive index between the core portion and the shell portion is 0.01 or more.

  In addition, the core part of the copolymer particle may be formed so as to cover the seed particle. That is, the copolymer particles may have seed particles, a core portion that covers the seed particles, and a shell portion that covers the core portion.

<Particle size, coefficient of variation>
In the present specification, the number average particle diameter is a number average particle diameter measured by a dynamic light scattering method, and can be measured by, for example, MICROTRAC UPA-150 manufactured by Nikkiso Co., Ltd.

  As described above, the number average particle diameter of the copolymer particles is 0.05 μm or more and 1 μm or less. In the structural color developing film formed of such copolymer particles, the light reflected by the regularly arranged core portions interferes and diffracts in accordance with the black reflection conditions, and a clear structural color is expressed. . The structural color developed in the structural color developing film changes depending on the number average particle diameter of the copolymer particles. That is, the structural color expressed in the structural color developing film can be adjusted by adjusting the number average particle diameter of the copolymer particles.

  The Cv value (coefficient of variation) expressed as a percentage of the particle diameter standard deviation with respect to the number average particle diameter is preferably 30% or less. The Cv value is a value obtained by Cv [%] = (σ / D) × 100 (σ: standard deviation, D: average particle diameter), and the smaller this value, the more uniform the particle size. When the Cv value is 30% or less, a coating film in which the shell portion is closely packed can be formed, and a structural color developing film in which the core portion is more regularly arranged can be obtained.

<Refractive index>
The difference in refractive index between the core part and the shell part is the difference between the refractive index value of the resin component constituting the core part and the refractive index value of the resin component constituting the shell part. The refractive index value is measured with an Abbe refractometer. it can. When the difference in refractive index between the core portion and the shell portion is 0.01 or more, light transmission is suppressed in the structural color developing film, and sufficient visible light reflection occurs so that the structural color can be visually confirmed.

  The upper limit of the refractive index difference is not particularly limited, but generally the upper limit of the optical refractive index of the polymer resin is about 1.82, and the refractive index of air (or vacuum) is 1.0. The upper limit of the rate difference is considered to be 0.82. It is known that the relational expression of Gladstone / Dale represented by the following formula (1) holds for the refractive index n of the copolymer.

Wherein (1), ν _i denotes the volume fraction with respect to the entire copolymer polymer of the homopolymer of each monomer, n _i is the refractive index of the homopolymer of each monomer. In the present embodiment, it is possible to select a monomer used for manufacturing the resin constituting the core part and the shell part so that the difference in refractive index calculated by the formula (1) is 0.01 or more. it can.

  The difference in refractive index between the core part and the shell part is preferably 0.02 or more, more preferably 0.03 or more.

  As a technique for achieving the above refractive index difference, for example, the resin component constituting the core part is a resin obtained from 100% styrene monomer, and the resin component constituting the shell part is the styrene monomer. And a copolymer resin obtained from 20 to 50% by mass of an acrylic monomer having a lower refractive index than the homopolymer and 50 to 80% by mass of a conjugated diene monomer. Further, the resin component constituting the core portion is a resin obtained from 100% acrylic monomer, and the resin component constituting the shell portion is a styrene monomer having a higher homopolymer refractive index than the acrylic monomer. The above-described difference in refractive index can also be achieved by a technique of forming a copolymer resin obtained from 20 to 50% by mass of a monomer and 50 to 80% by mass of a conjugated diene monomer.

<Shell part>
The shell part of the copolymer particles contains a resin (a) crosslinked with a conjugated diene. When the shell portion contains the resin (a), a structural color developing film excellent in flexibility and flexibility can be obtained. Such a structural color developing film can be wound and stored, for example. It becomes possible.

  Examples of the conjugated diene include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, and chloroprene. Among these, 1,3-butadiene is preferable.

  The resin (a) preferably contains a structural unit derived from a conjugated diene at a ratio of 0.2% by mass or more and 60% by mass or less based on the total amount of the resin (a). The content of the structural unit derived from the conjugated diene is more preferably 0.6% by mass to 57% by mass, and still more preferably 0.8% by mass to 50% by mass.

  That is, the amount of the conjugated diene used in the production of the resin (a) is preferably 0.2% by mass or more and 60% by mass or less, more preferably 0.6% by mass or more and 57% by mass with respect to the total amount of the monomers. % Or less, and more preferably 0.8% by mass or more and 50% by mass or less.

  The resin component constituting the shell portion may contain components other than the resin (a). For example, the resin component may contain a copolymer obtained from a monoethylene monomer such as (meth) acrylic acid ester or styrene.

  The content of the resin (a) is preferably 70% by mass or more, and more preferably 90% by mass or more, based on the total amount of the resin components constituting the shell part. Moreover, the shell part may be comprised from resin (a) (namely, content of resin (a) may be 100 mass%).

<Core part>
The core part of the copolymer particles preferably contains a resin having a crosslinked structure (hereinafter sometimes referred to as “resin (b)”). In other words, the core part preferably contains a resin (b) crosslinked with a crosslinking agent.

  As the cross-linking agent, for example, a cross-linkable monomer having two or more non-conjugated double bonds in one molecule can be used.

Examples of such crosslinkable monomers include polyfunctional vinyl monomers such as divinylbenzene, divinylbiphenyl, and divinylnaphthalene; ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, tetramethylene glycol di (meth) ) Acrylate, 1,6-hexanediol di (meth) acrylate, 1,8-octanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate 1,12-dodecanediol di (meth) acrylate, 3-methyl-1,5-pentanediol di (meth) acrylate, 2,4-diethyl-1,5-pentanediol di (meth) acrylate, butylethylpropane Diol di (meth) acrylate, 3 Methyl-1,7-octanediol di (meth) acrylate, 2-methyl-1,8-octanediol di (meth) acrylate, an alkane diol di (meth) acrylates such as neopentyl glycol di (meth) acrylate;
Trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolpropane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, ethoxylated cyclohexanedimethanol di (meth) acrylate, ethoxylated bisphenol A Di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, propoxylated ethoxylated bisphenol A di (meth) acrylate, 1,1,1-trishydroxymethylethanedi (meth) acrylate, 1,1,1 -Trishydroxymethylethane tri (meth) acrylate, 1,1,1-trishydroxymethylpropane triacrylate, diallyl phthalate and its isomer, triallyl isocyanurate And polyfunctional (meth) acrylic acid ester acid derivatives derivatives thereof; and the like.

  A conjugated diene can also be used as the crosslinking agent. Conjugated dienes include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3- Examples thereof include pentadiene and 1,3-hexadiene.

  When the cross-linking agent is the cross-linkable monomer, the resin (b) contains 0.01% by mass or more and 6.2% by mass of structural units derived from the cross-linkable monomer based on the total amount of the resin (b). It is preferable to contain in the ratio of% or less. The content of the structural unit derived from the crosslinkable monomer is more preferably 0.05% by mass or more and 5.0% by mass or less, and further preferably 0.1% by mass or more and 4.0% by mass or less. .

  That is, the amount of the crosslinkable monomer used in the production of the resin (b) is preferably 0.01% by mass or more and 6.2% by mass or less, more preferably 0.05% by mass with respect to the total amount of the monomers. It is not less than 5.0% by mass and more preferably not less than 0.1% and not more than 4.0% by mass.

  When the crosslinking agent is a conjugated diene, the resin (b) contains a structural unit derived from the conjugated diene in a proportion of 0.01% by mass or more and 50% by mass or less based on the total amount of the resin (b). It is preferable. The content of the structural unit derived from the conjugated diene is more preferably 0.05% by mass or more and 30% by mass or less, and further preferably 0.1% by mass or more and 25% by mass or less.

  That is, the amount of the conjugated diene used in the production of the resin (b) is preferably 0.01% by mass or more and 50% by mass or less, more preferably 0.05% by mass or more and 30% by mass with respect to the total amount of the monomers. % Or less, and more preferably 0.1% by mass or more and 25% by mass or less.

  By adjusting the content depending on the type of the crosslinking agent as described above, the core particles in the structural color developing film are not easily affected by pressure or heating (for example, shape change due to pressure / heating). That is, by adjusting the content of the crosslinking agent as described above, it is possible to sufficiently suppress the shape change of the core particles due to pressure, heating, etc., thereby obtaining a structural color developing film having a beautiful structural color. Can do.

  The resin component constituting the core part may contain components other than the resin (b). For example, the resin component is a copolymer having no crosslinked structure, that is, a copolymer obtained from a monomer other than the crosslinking agent (crosslinkable monomer and conjugated diene) among the monomers exemplified herein. It may contain coalescence or the like.

  The content of the resin (b) is preferably 10% by mass or more, and more preferably 20% by mass or more, based on the total amount of the resin components constituting the core part. Moreover, the core part may be comprised from resin (b) (namely, content of resin (b) may be 100 mass%).

  The number average particle size of the core part is preferably 0.03 μm or more and 0.8 μm or less, and more preferably 0.05 μm or more and 0.7 μm or less. According to the core portion having such an average particle diameter, a better structural color is expressed.

  The Cv value (coefficient of variation) of the number average particle diameter of the core part is preferably 80% or less. When the Cv value of the core part is 80% or less, a better structural color is expressed.

<Core shell ratio>
The amount of the resin component constituting the shell part is preferably 30% by mass or more and 95% by mass or less, and preferably 40% by mass or more and 85% by mass or less, based on the total amount of the resin component constituting the copolymer particles. Is more preferable.

  When the amount of the resin component constituting the shell part is 30% by mass or more, the gap between the core parts regularly arranged at the time of manufacturing the structural color developing film can be easily filled and the core parts can be easily fixed. The structural color developing film can be formed without disturbing the above. Further, when the amount of the resin component constituting the shell part is 95% by mass or less, the core part can be arranged at an appropriate interval during the production of the structural color developing film. The incident light can be sufficiently reflected, and a beautiful structural color can be visually confirmed.

<Tg of core and shell>
The Tg (glass transition temperature) of the resin component constituting the core portion and the resin component constituting the shell portion is not particularly limited, but the Tg of the resin component constituting the shell portion is more than the Tg of the resin component constituting the core portion. Preferably it is low.

  For example, if the Tg of the resin component constituting the core part is a high Tg of 50 ° C. or more and the Tg of the resin component constituting the shell part is a low Tg of 40 ° C. or less, deformation or flow of the core part is caused. Since the shell part can be made to flow without being fixed, the core part can be fixed while the shape of the core part is maintained.

<Core part and shell part forming monomer>
The monomer for obtaining the resin constituting the core part and the shell part (hereinafter referred to as “resin-forming monomer”) is not particularly limited except for the conjugated diene for the resin (a) described above, It can select suitably so that the refractive index difference of a core part and a shell part may be 0.01 or more.

  One resin-forming monomer may be used alone, or two or more resin-forming monomers may be used in combination. Examples of the resin-forming monomer include a styrene monomer, an ethylenically unsaturated carboxylic acid monomer, an unsaturated carboxylic acid ester monomer, an unsaturated monomer having a hydroxyalkyl group, and a vinyl cyanide monomer. A monomer is mentioned.

  Examples of the styrenic monomer include styrene, α-methyl styrene, vinyl toluene, t-butyl styrene and the like. These may be used alone or in combination of two or more. Of these, styrene is preferred.

  Examples of the ethylenically unsaturated carboxylic acid monomer include mono- or dicarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid, and anhydrides thereof can also be used. These may be used alone or in combination of two or more. Among these, methacrylic acid is preferable.

  As unsaturated carboxylic acid ester monomers, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, glycidyl (meth) acrylate, dimethyl fumarate, diethyl fumarate Dimethyl maleate, diethyl maleate, dimethyl itaconate, monomethyl fumarate, monoethyl fumarate, 2-ethylhexyl acrylate and the like. These may be used alone or in combination of two or more. Among these, methyl methacrylate, 2-ethylhexyl acrylate, n-butyl acrylate, and glycidyl methacrylate are preferable.

  Examples of unsaturated monomers having a hydroxyalkyl group include 2-hydroxymethyl acrylate, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, 3-chloro-2-hydroxy Examples thereof include propyl methacrylate, di- (ethylene glycol) maleate, di- (ethylene glycol) itaconate, 2-hydroxyethyl maleate, bis (2-hydroxyethyl) maleate, 2-hydroxyethyl methyl fumarate and the like. These may be used alone or in combination of two or more. Among these, 2-hydroxyethyl acrylate is preferable.

  Examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethylacrylonitrile, and the like. These may be used alone or in combination of two or more. Of these, acrylonitrile is preferred.

  In addition to the above, unsaturated carboxylic acid amide monomers such as acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N, N-dimethylacrylamide; fatty acid vinyl such as vinyl acetate and vinyl propionate Esters; basic monomers such as aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine; vinyl chloride; vinylidene chloride; Can be used.

  The same monomer may be used for the core part and the shell part as long as the refractive index difference between the core part and the shell part is 0.01 or more. Among the above monomers, from the viewpoint of film formability, the resin-forming monomer used for the core portion contains at least one selected from the group consisting of styrene, methyl methacrylate and divinylbenzene, and the shell portion The resin forming monomer to be used preferably contains at least one selected from the group consisting of 1,3-butadiene, n-butyl acrylate, methyl methacrylate and methacrylic acid. For example, the compounding ratio of the resin-forming monomer for forming the core part is 1 to 39% by mass of styrene, 1 to 39% by mass of methyl methacrylate, and 0.1 to 2% of divinylbenzene based on the total amount of the copolymer particles. It is preferable to set it as 0.1-10 mass% of the other monomer copolymerizable with these by mass%, The compounding ratio of the resin formation monomer for forming a shell part is the whole quantity of copolymer particle | grains. 1,3-butadiene 1 to 15% by mass, n-butyl acrylate 5 to 25% by mass, methyl methacrylate 1 to 20% by mass, methacrylic acid 1 to 10% by mass, and other monomers copolymerizable therewith It is preferable to set it as 5-20 mass% of a body. The (meth) acrylate means acrylate or methacrylate.

<Polymerization method and average particle size>
The copolymer particles can be prepared by, for example, emulsion polymerization using the resin-forming monomer or multistage polymerization of soap-free emulsion polymerization. Also, suitable seed particles can be used during emulsion polymerization. Ordinary emulsion polymerization can be used for the polymerization of the seed particles. For example, the average particle size of the copolymer particles can be adjusted to a uniform and appropriate coefficient of variation by appropriately selecting the type and size of seed particles, the type of emulsifier, and the type of initiator and using appropriate amounts. Here, the average particle diameter is the number average particle diameter.

(Method for producing copolymer particles)
Hereinafter, a method for producing copolymer particles will be described.
The copolymer particles can be produced by emulsion polymerization of the above-described resin-forming monomer (including a crosslinking agent). Appropriate seed particles can be used during the polymerization, and the seed particles can also be produced by a known emulsion polymerization. In addition, a known method can be employed for emulsion polymerization, and it can be carried out in an aqueous medium by appropriately using a molecular weight adjusting agent in addition to an emulsifier and a polymerization initiator.

<Emulsifier>
Examples of emulsifiers used include sodium dodecyl sulfate, sodium dodecyl benzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium dodecyl benzene sulfonate, sodium dodecyl diphenyl ether sulfonate, sodium laurate, dihexyl Sodium sulfosuccinate, potassium stearate, calcium oleate, dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, hexadecyl trimethyl ammonium bromide, dodecyl polyoxyethylene ether, hexadecyl polyoxyethylene ether, lauryl poly Oxyethylene ether Etc. The. These may be used alone or in combination of two or more. The amount of the emulsifier used is appropriately determined by a technique known to those skilled in the art according to the target particle size.

<Polymerization initiator>
Polymerization initiators include water-soluble polymerization initiators such as sodium persulfate, potassium persulfate, and ammonium persulfate; oil-soluble polymerization initiators such as benzoyl peroxide and lauryl peroxide; redox polymerization initiators in combination with reducing agents, etc. Can be mentioned. These can be used alone or in combination.

<Molecular weight regulator>
Adhesiveness to an object to be coated can be improved by adding a molecular weight adjusting agent as needed during the shell part polymerization of the copolymer particles to reduce the molecular weight. Examples of the molecular weight modifier include 3-chlorobenzenethiol, carbon tetrachloride, t-dodecyl mercaptan, n-hexyl mercaptan, octyl thioglycolate, α-methylstyrene dimer, and the like. Among these, t-dodecyl mercaptan is particularly preferable. The amount of the molecular weight modifier used is preferably 0 to 3 parts by mass with respect to the total amount of single monomers forming the copolymer particles from the viewpoint of film formability.

(Structural color expression composition)
The structural color developing composition according to this embodiment contains the copolymer particles.

  The structural color developing composition may further contain a dispersion medium in which the copolymer particles are dispersed. That is, the structural color developing composition may be a composition containing a dispersion medium and copolymer particles dispersed in the dispersion medium. The dispersion medium is preferably an aqueous solvent. For example, water or an aqueous solvent obtained by adding a hydrophilic solvent such as ethanol to water can be suitably used. The composition for expressing a structural color in which copolymer particles are dispersed in an aqueous solvent can also be referred to as latex.

  The structural color developing composition further contains a preservative, a surfactant, a film-forming aid, a thickener, a pH adjuster, a chelating agent, an ultraviolet absorber, an antioxidant, an emulsifier, and the like as necessary. It may be.

  The content of the copolymer particles in the structural color developing composition is preferably 90% by mass or more, more preferably 92% by mass or more, and 95% by mass or more based on the total amount of the solid content. More preferably.

  Further, the solid content in the structural color developing composition can be appropriately adjusted according to the type of the object to be coated, the desired thickness of the structural color developing film, and the like. For example, the solid content can be 5 to 65% by mass based on the total amount of the structural color developing composition, and can also be 30 to 60% by mass.

(Structural color expression film)
FIG. 1B is a schematic view showing one embodiment of a structural color developing film according to this embodiment. The structural color expression coating film 200 is a coating film obtained using the copolymer particles 100 shown in FIG. 1A, and is dispersed in the matrix material 11 containing the resin (a) and the matrix material 11. Core particles 21.

  The matrix material 11 is formed by deforming (for example, melting and flowing) the shell portion 10 of the copolymer particle 100. The matrix material 11 is made of a resin component constituting the shell portion 10 and holds regularly arranged core particles 21. The core particles 21 are particles derived from the core portion 20 of the structural color developing resin 100, and are regularly arranged in the matrix material 11.

  The thickness of the structural color developing film is not particularly limited, but is preferably 10 μm to 1000 μm.

  The structural color developing film can be formed by, for example, applying a structural color developing composition to an object to be coated and then performing a treatment such as heating as necessary to deform the shell portion of the copolymer particles. it can. When the structural color developing composition contains a dispersion medium, for example, after applying to the object to be coated, drying and heating can be performed to deform, melt or flow the shell portion to obtain a structural color developing film. . In addition, when the glass transition temperature of the shell part of the copolymer particles is room temperature or lower, heating is not necessarily required, and the dispersion medium is dried at room temperature after applying the structural color developing composition to the object to be coated. It can also be removed to obtain a structural color developing film.

  The structural color developing composition can form a coating film by various commonly used coating methods such as bar coater coating, spin coating, dip coating, applicator coating, and spray coating.

  For example, in the case of applicator coating, the composition for expressing the structural color is concentrated to a solid content of 40% by mass or more (preferably 40 to 65% by mass), applied to the object to be coated, and dried under appropriate conditions (necessary) Accordingly, a structural color developing film can be obtained by drying and heating. In the case of spray coating, the composition for expressing the structural color is applied to the object to be coated with a solid content of 20 to 60% by mass, and dried under appropriate conditions (drying and heating as necessary) to express the structural color. A membrane can be obtained.

  Conditions for drying and heating the coating film of the structural color developing composition can be appropriately selected according to the solid content concentration of the structural color developing composition, the coating method of the structural color developing composition, and the like.

Drying and heating can be performed separately or simultaneously. The heating conditions may be any conditions as long as the resin component constituting the shell portion can be melted to fill the gaps between the copolymer particles. For example, the heating temperature is preferably equal to or higher than the glass transition temperature of the resin component constituting the shell portion (hereinafter sometimes referred to as “T ₁ ”). In addition, the heating temperature is preferably T ₁ + 150 ° C. or less, and more preferably T ₁ + 130 ° C. or less, from the viewpoint of sufficiently suppressing the shape change of the core part.

<To be painted>
The article to be coated on which the structural color developing composition is applied is not limited. For example, paper, a SUS board, an acrylic board, and an electrodeposition board are mentioned. In particular, if the object to be coated is painted black in advance, extra scattered light that occurs when light is incident can be excluded, and only reflected light can be received, so that the structural color looks clearer.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  Hereinafter, the contents of the present invention will be specifically described with reference to examples. In addition, all the mass parts were made into the solid content conversion value.

<Preparation of composition for expression of structural color>
In an eggplant flask, 100 parts by mass of the latex (solid content: 18 ± 2% by mass) obtained in Examples and Comparative Examples was added, 0.45 parts by mass of an emulsifier was added, and 0.7 parts by mass of potassium hydroxide was added while stirring. Added to adjust pH 6-8. Next, 0.06 parts by mass of an antifoaming agent was added, and then concentrated to a solid content of 43 ± 2% by mass using a rotary evaporator to obtain a structural color developing composition.

<Coating method: applicator coating>
The concentrate adjusted to a solid content of 43 ± 2% by mass by the above-described method was applied to an about 0.2 mm film using an applicator on a black-coated electrodeposition plate. After coating, a structural color developing film was obtained by heating and drying at 55 ° C. and RH 75% for 40 minutes.

(Evaluation method)
<Measurement of refractive index>
The refractive index difference was defined as a difference in refractive index value measured by an Abbe refractometer after separately polymerizing the resins constituting the core portion and the shell portion.

<Method of measuring reflected light>
The reflectance and color of the structural color developing film were measured using a Macbeth colorimeter (CE-741GL) manufactured by Sakata Inx. The light receiving angle was 45 °, the incident angle was −30 °, and the wavelength range was 360 to 750 nm. The color is a color obtained by converting the reflection peak wavelength obtained by measurement into a color system.

<Evaluation of color>
The impression of color development of the structural color developing film was evaluated according to the following evaluation criteria.
A: The color is beautiful and the color is strong B: The color can be clearly identified C: The color can be identified relatively D: The paint film is pure white or transparent and the hue cannot be confirmed

<Evaluation of film formability>
The film formability of the structural color developing film was evaluated by visual observation and scratching with a nail. The evaluation criteria are as follows.
A: A uniform coating film is formed, and even if scratched with a nail, the coating film does not peel off B: A uniform coating film is formed, but when scratched with a nail, the coating film peels off C: Partially cracked Yes, the film peels off when scratched with a nail D: There are many fine cracks in the whole, and the film peels off just by touching

<Winding experiment>
A structural color developing film having a size of 50 mm × 100 mm and a thickness of 0.2 mm was prepared using the structural color developing composition, wound around a cylinder having a diameter of 380 mm, and the surface state of the structural color developing film was visually evaluated. The evaluation criteria are as follows.
A: Smooth surface B: Small cracks on the surface C: Large cracks on the surface D: Unbreakable

Example 1
In a reactor, 296 parts by mass of water, 0.01 part by mass of sodium dodecyl diphenyl ether sulfonate, 0.01 part by mass of sodium dihexyl sulfosuccinate, 0.16 part by mass of seed particles (polystyrene particles having a particle diameter of 35 nm) are charged and mixed. The mixture was heated to about 80 ° C. To this solution, liquid mixture 1 consisting of 34.6 parts by mass of styrene, 14.6 parts by mass of methyl methacrylate and 0.3 part by mass of divinylbenzene was added over 140 minutes, and at the same time, 65.9 parts by mass of water and sodium hydroxide were added. A mixed solution 2 consisting of 0.07 parts by mass, 0.001 part by mass of sodium dihexylsulfosuccinate and 0.46 parts by mass of sodium persulfate was added over 200 minutes to obtain core particles. When 30 minutes had elapsed after the addition of the mixed liquid 1, a small amount of the formed core particles was collected, and the particle diameter was measured.

  Immediately after the addition of the mixed liquid 2, 8.1 parts by mass of 1,3-butadiene, 7.1 parts by mass of methyl methacrylate, 16.3 parts by mass of 2-hydroxyethyl acrylate, 10.2 parts by mass of butyl acrylate, methacrylic acid 2 8 parts by mass, 6.1 parts by mass of 2-ethylhexyl acrylate, and 0.2 parts by mass of t-dodecyl mercaptan were added over 100 minutes. Simultaneously, 47.6 parts by mass of water and 0. A mixed solution 4 consisting of 04 parts by mass, 0.001 part by mass of the above sodium dihexyl sulfosuccinate and 0.33 part by mass of sodium persulfate was added over 120 minutes.

  After completion of the addition, the temperature was raised to 95 ° C. over 30 minutes with stirring, held for 1 hour, and then cooled to room temperature to obtain a latex containing copolymer particles. The mass% of the shell part with respect to the total mass of the monomers forming the copolymer particles was 51% by mass.

  The resulting copolymer particles had a particle size of 337 nm and a coefficient of variation of 12%. Moreover, the particle diameter of only the core part was 257 nm. The refractive index was 1.56 for the core and 1.48 for the shell, and the difference was 0.08. The structural color-expressing film obtained from the copolymer particles showed a yellow-orange structural color, had a uniform surface, was difficult to peel off even when scratched with a nail, and had good winding properties.

(Example 2)
The composition of the liquid mixture 1 of Example 1 is 35 parts by mass of styrene, 13.5 parts by mass of methyl methacrylate, 1.5 parts by mass of ethylene glycol dimethacrylate, the composition of the liquid mixture 3 is 12 parts by mass of 1,3-butadiene, methyl In the same manner as in Example 1, except for changing to 15 parts by weight of methacrylate, 10 parts by weight of methacrylic acid, 10 parts by weight of ethyl hexyl acrylate, 3 parts by weight of glycidyl methacrylate, and 0.2 parts by weight of t-dodecyl mercaptan. A latex containing coalesced particles was obtained. The mass% of the shell part with respect to the total mass of the monomers forming the copolymer particles was 50% by mass.

  The resulting copolymer particles had a particle size of 329 nm and a coefficient of variation of 15%. Moreover, the particle diameter of only the core part was 256 nm. The refractive index was 1.56 for the core and 1.51 for the shell, and the difference was 0.05. The structural color-expressing film obtained from the copolymer particles showed a yellow structural color, had a uniform surface, and slightly peeled off with a nail, but had good winding properties.

Example 3
The seed amount of Example 1 is 0.21 parts by mass, and the composition of the mixed solution 1 is 31.4 parts by mass of styrene, 12 parts by mass of methyl methacrylate, 6 parts by mass of 1,3-butadiene, and 0.2 of 2-hydroxyethyl acrylate. The composition of the liquid mixture 3 is 2.5 parts by mass of 1,3-butadiene, 26 parts by mass of methyl methacrylate, 6.5 parts by mass of methacrylic acid, 13.9 parts by mass of ethyl hexyl acrylate, 1.5 parts by mass of acrylic acid. The latex containing the copolymer particles was obtained in the same manner as in Example 1 except that the content was changed to 0.2 parts by mass of t-dodecyl mercaptan. The mass% of the shell part with respect to the total mass of the monomers forming the copolymer particles was 50% by mass.

  The resulting copolymer particles had a particle size of 289 nm and a coefficient of variation of 16%. Moreover, the particle diameter of only the core part was 229 nm. The refractive index was 1.56 for the core and 1.51 for the shell, and the difference was 0.08. The structural color developing film obtained from the copolymer particles showed a blue structural color, the surface was uniform, and it was slightly peeled off by the nail, but the winding property was good.

Example 4
The composition of the liquid mixture 1 of Example 1 is 42 parts by mass of styrene, 17.7 parts by mass of methyl methacrylate, 0.3 part by mass of divinylbenzene, the composition of the liquid mixture 3 is 1.6 parts by mass of 1,3-butadiene, methyl 14 parts by weight of methacrylate, 9.8 parts by weight of 2-hydroxyethyl acrylate, 24.3 parts by weight of butyl acrylate, 7.2 parts by weight of methacrylic acid, 3 parts by weight of glycidyl methacrylate, 0.2 parts by weight of t-dodecyl mercaptan A latex containing copolymer particles was obtained in the same manner as in Example 1 except that. The mass% of the shell part with respect to the total mass of the monomers forming the copolymer particles was 50% by mass.

  The resulting copolymer particles had a particle size of 367 nm and a coefficient of variation of 13%. The particle size of only the core part was 277 nm. The refractive index was 1.56 for the core and 1.46 for the shell, and the difference was 0.1. The coating film showed a red structural color, the surface was uniform, did not peel off even when scratched with a nail, and the take-up property was good although the surface slightly cracked.

(Example 5)
A latex containing copolymer particles was obtained in the same manner as in Example 4 except that the mass% ratio 50:50 between the mixed liquid 1 and the mixed liquid 3 in Example 4 was 71:29.

  The resulting copolymer particles had a particle size of 365 nm and a coefficient of variation of 12%. The particle size of only the core part was 323 nm. The refractive index was 1.56 for the core and 1.46 for the shell, and the difference was 0.1. The structural color developing film obtained from the copolymer particles showed a red structural color. The surface was uniform, but it peeled off with a nail, and the winding property was good although the surface was slightly cracked.

(Example 6)
A latex containing copolymer particles was obtained in the same manner as in Example 4 except that the mass% ratio 50:50 between the mixed liquid 1 and the mixed liquid 3 in Example 4 was set to 40:60.

  The resulting copolymer particles had a particle size of 368 nm and a coefficient of variation of 12%. The particle size of only the core part was 267 nm. The refractive index was 1.56 for the core and 1.46 for the shell, and the difference was 0.1. The structural color-expressing film obtained from the copolymer particles has a red-orange structural color, the surface is uniform, does not peel even if scratched with a nail, and the winding property is good although the surface slightly cracks. It was.

(Example 7)
A latex containing copolymer particles was obtained in the same manner as in Example 4 except that the mass ratio 50:50 of the mixed liquid 1 and the mixed liquid 3 in Example 4 was set to 4:96.

  The resulting copolymer particles had a particle size of 365 nm and a coefficient of variation of 14%. The particle size of only the core part was 135 nm. The refractive index was 1.56 for the core and 1.46 for the shell, and the difference was 0.1. The structural color-expressing film obtained from the copolymer particles showed a yellow-green structural color, the surface was uniform, did not peel off even when scratched with a nail, and the winding property was good.

(Example 8)
A latex containing copolymer particles was obtained in the same manner as in Example 1 except that the seed amount in Example 1 was changed to 0.33 parts by mass. The mass% of the shell part with respect to the total mass of the monomers forming the copolymer particles was 50% by mass.

  The resulting copolymer particles had a particle size of 216 nm and a coefficient of variation of 12%. The particle size of only the core part was 163 nm. The refractive index was 1.56 for the core and 1.48 for the shell, and the difference was 0.08. The structural color developing film obtained from the copolymer particles showed a blue-purple structural color, the surface was uniform, did not peel off even when scratched with a nail, and the winding property was good.

Example 9
The seed amount of Example 1 is 0.28 parts by mass, the composition of the mixture 1 is 35.5 parts by mass of styrene, 12.5 parts by mass of methyl methacrylate, 2 parts by mass of divinylbenzene, and the composition of the mixture 3 is 1, To 26 parts by mass of 3-butadiene, 11 parts by mass of methyl methacrylate, 3 parts by mass of 2-hydroxyethyl acrylate, 5 parts by mass of butyl acrylate, 3 parts by mass of methacrylic acid, 2 parts by mass of glycidyl methacrylate, 0.2 parts by mass of t-dodecyl mercaptan A latex containing copolymer particles was obtained in the same manner as in Example 1 except that each was changed. The mass% of the shell part with respect to the total mass of the monomers forming the copolymer particles was 50% by mass.

  The resulting copolymer particles had a particle size of 228 nm and a coefficient of variation of 15%. The particle size of only the core part was 181 nm. The refractive index was 1.56 for the core and 1.50 for the shell, and the difference was 0.06. The structural color-expressing film obtained from the copolymer particles showed a blue structural color, and the surface was uniform and did not peel even when scratched with a nail, and the winding property was good.

(Example 10)
The composition of the liquid mixture 1 of Example 9 is 36.9 parts by mass of styrene, 12.5 parts by mass of methyl methacrylate, 0.6 parts by mass of divinylbenzene, and the composition of the liquid mixture 3 is 0.25 parts by mass of 1,3-butadiene. , 19.8 parts by weight of methyl methacrylate, 6 parts by weight of 2-hydroxyethyl acrylate, 15 parts by weight of butyl acrylate, 6 parts by weight of methacrylic acid, 3 parts by weight of glycidyl methacrylate, 0.2 parts by weight of t-dodecyl mercaptan Produced latex containing copolymer particles in the same manner as in Example 9. The mass% of the shell part with respect to the total mass of the monomers forming the copolymer particles was 50% by mass.

  The resulting copolymer particles had a particle size of 230 nm and a coefficient of variation of 13%. The particle size of only the core part was 183 nm. The refractive index was 1.57 for the core and 1.48 for the shell, and the difference was 0.09. The structural color developing film obtained from the copolymer particles showed a blue structural color, the surface was uniform, it was peeled off with a nail, and the winding property was cracked.

(Example 11)
Latex containing copolymer particles in the same manner as in Example 1 except that the composition of the liquid mixture 1 of Example 1 was changed to styrene 34.0, methyl methacrylate 12.2 parts by mass, and divinylbenzene 3.2 parts by mass. Got. The mass% of the shell part with respect to the total mass of the monomers forming the copolymer particles was 51% by mass.

  The resulting copolymer particles had a particle size of 338 nm and a coefficient of variation of 13%. The particle size of only the core part was 256 nm. The refractive index was 1.56 for the core and 1.48 for the shell, and the difference was 0.08. The structural color-expressing film obtained from the copolymer particles showed a yellow-orange structural color, had a uniform surface, hardly peeled off even when scratched with a nail, and had good winding properties.

(Comparative Example 1)
In soap-free polymerization, particles of 805 nm are prepared with the same composition as the liquid mixture 1 of Example 1, and the shell is polymerized with the same composition as the liquid mixture 3 of Example 1 using it as a core to contain copolymer particles To get latex. The mass% of the shell part with respect to the total mass of the monomers forming the copolymer particles was 51% by mass.

  The resulting copolymer particles had a particle size of 1014 nm and a coefficient of variation of 13%. The refractive index was 1.56 for the core and 1.48 for the shell, and the difference was 0.08. The structural color-expressing film obtained from the copolymer particles was pure white and did not exhibit a structural color, had a uniform surface, did not peel even when scratched with a nail, and had good winding properties.

(Comparative Example 2)
The mass% ratio 50:50 of the liquid mixture 1 and the liquid mixture 3 of Example 3 was set to 70:30, and the composition of the liquid mixture 3 was 20 parts by mass of methyl methacrylate, 2.4 parts by mass of butyl acrylate, 6 parts by mass of methacrylic acid, Contains copolymer particles in the same manner as in Example 3 except that 6 parts by mass of 2-ethylhexyl acrylate, 1.8 parts by mass of glycidyl methacrylate, 1.8 parts by mass of acrylic acid, and 0.2 parts by mass of t-dodecyl mercaptan are used. To get latex.

  The resulting copolymer particles had a particle size of 287 nm and a coefficient of variation of 12%. The particle size of only the core part was 254 nm. The refractive index was 1.56 for the core and 1.48 for the shell, and the difference was 0.08. The structural color developing film obtained from the copolymer particles was yellowish green, and there were many large cracks on the surface. When touched with a finger, the coating film was cracked and the winding was poor.

(Comparative Example 3)
The composition of the liquid mixture 1 and the liquid mixture 3 of Example 9 was changed to 19.5 parts by mass of methyl methacrylate, 0.5 part by mass of 1,3-butadiene, 6 parts by mass of 2-hydroxyethyl acrylate, 15 parts by mass of butyl acrylate, methacrylic acid. A latex containing copolymer particles was obtained in the same manner as in Example 9, except that 6 parts by mass of acid, 3 parts by mass of glycidyl methacrylate, and 0.2 parts by mass of t-dodecyl mercaptan were used. The mass% of the shell part with respect to the total mass of the monomers forming the copolymer particles was 50% by mass.

  The resulting copolymer particles had a particle size of 233 nm and a coefficient of variation of 12%. The particle size of only the core part was 185 nm. The refractive index was 1.48 for both the core part and the shell part, and the difference was zero. The structural color-expressing film obtained from the copolymer particles is transparent and does not show a structural color, and the surface is uniform, but the coating film peels off when scratched with a nail, and the winding property is good although the surface slightly cracks. there were.

  Tables 1 to 3 show the evaluation results of the copolymer particles and the structural color-expressing films obtained in the examples and comparative examples.

  The copolymer particles of the present invention have a characteristic that the resulting structural color developing film is resistant to bending and tensile stress. Compared with the conventional method in which spherical particles are arranged on the adhesive and the binder resin is poured from there and cured, the core part is fixed with the shell part. Therefore, it is possible to form a coating film that expresses a structural color with one liquid without disturbing the arrangement of the core portions, and it is possible to directly apply to various objects to be coated. Further, unlike a colorant that absorbs light such as a dye, it has a characteristic that it is difficult to fade because it is a physical color. Utilizing the characteristics as described above, it can be applied to exteriors of cars and buildings, optical films, optical sensors, and the like.

DESCRIPTION OF SYMBOLS 10 ... Shell part, 11 ... Matrix material, 20 ... Core part, 21 ... Core particle, 100 ... Copolymer particle, 200 ... Structural color expression film | membrane.

Claims (6)

A composition for forming a structural color film containing copolymer particles having a core-shell structure,
Containing a resin (a) in which the shell part of the copolymer particles is crosslinked with a conjugated diene;
The number average particle size of the copolymer particles is 0.05 μm or more and 1 μm or less,
The difference in refractive index between the core part and the shell part in the copolymer particles is 0.03 or more.
A structural color developing film forming composition, wherein the structural color developing film contains a matrix material containing the resin (a) and core particles derived from the core portion dispersed in the matrix material . The core part of the copolymer particles contains a resin (b-1) cross-linked with a cross-linkable monomer having two or more non-conjugated double bonds in one molecule,
The resin (b-1) contains a structural unit derived from the crosslinkable monomer at a ratio of 0.01% by mass to 6.2% by mass based on the total amount of the resin (b-1). The composition for forming a structural color developing film according to claim 1. The core part of the copolymer particles contains a resin (b-2) crosslinked with a conjugated diene,
The said resin (b-2) contains the structural unit derived from the said conjugated diene in the ratio of 0.01 mass% or more and 50 mass% or less on the basis of the whole quantity of the said resin (b-2). A composition for forming a structural color developing film . 4. The structural color according to claim 1, wherein the total amount of the shell part in the copolymer particles is a ratio of 30% by mass or more and 95% by mass or less based on the total amount of the copolymer particles. Composition for expression film formation . The structural color developing film forming composition according to any one of claims 1 to 4, further comprising a dispersion medium for dispersing the copolymer particles. A film-formed product of the structural color developing film-forming composition according to any one of claims 1 to 5 ,
A structural color developing film comprising a matrix material containing the resin (a) and core particles derived from the core portion dispersed in the matrix material .

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