JP2006257180A - Method for producing colored particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing in a short time a colored particle having a high hyperchromic property by dyeing a polymer particle having a very high degree of crosslinking. <P>SOLUTION: The method for producing the colored particle is characterized by dyeing in a supercritical fluid or a subcritical fluid a polymer particle obtained by polymerizing 60-100 pts.wt. of a crosslinkable monomer having two or more unsaturated double bonds and 0-40 pts.wt. of a non-crosslinkable monomer having one unsaturated double bond based on 100 pts.wt. of the total monomers. To use the colored particle as a spacer for a liquid crystal display element is a particularly preferable embodiment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing colored particles for dyeing specific polymer particles in a supercritical fluid or a subcritical fluid.

  Polymer particles obtained by polymerizing various monomers include extenders such as paints and inks, additives to cosmetics and pastes for ironing, spacers for laminated glass, gap materials for sensors, and liquid crystal display elements. It is used for various purposes such as spacers.

  Here, a spacer for a liquid crystal display element (hereinafter sometimes simply referred to as a spacer) is a liquid crystal display element for keeping a gap between two substrates sandwiched between two transparent electrode substrates constant. It is a gap material, and the transmission polarization is controlled while keeping the thickness of the liquid crystal layer constant. In order to achieve this object, the spacer is required to have a uniform particle size distribution, and at the same time, it needs a certain degree of hardness and compression recovery force after deformation. As a result, polymer particles used for spacer use are polymer particles having a very high degree of crosslinking, such as fine particles disclosed in Patent Document 1, for example.

  On the other hand, in the liquid crystal display element, the molecular orientation of the liquid crystal is controlled by the presence or absence of voltage, the transmitted light is rotated, and the transmitted light amount is controlled by combining the polarizing filter attached to the outer surface of the transparent electrode substrate. . For example, in a twisted nematic liquid crystal display device, a liquid crystal in a state in which no voltage is applied exhibits an optical rotation of 90 degrees, and this optical rotation is canceled when voltage is applied. Therefore, when two linearly polarizing plates are arranged so that their polarization axes are parallel, the image is in a bright state when voltage is applied, and in a dark state when the voltage is turned off. On the other hand, when the polarization axes are orthogonal, the image becomes dark when voltage is applied, and becomes bright when the voltage is turned off.

  In the dark part of the image, it is necessary to prevent light transmission as much as possible, thereby increasing the contrast between light and dark. However, normally, the polymer particles are transparent and non-rotatory, and naturally there is no liquid crystal in the portion where the spacer exists, so that even when the image is in a dark state, the spacer transmits a considerable amount of light. , Reduce the contrast of the image. For this reason, various light-shielding spacers colored black have been studied. However, since the polymer particles used for the spacer have a very high degree of crosslinking as described above, the usual dyeing method in which the dye is stirred in an aqueous solution in which the dye is dissolved or dispersed takes a very long time for dyeing, and the dark color. There was a limit in obtaining the colored particles.

  Patent Document 2 includes a mixing step in which resin particles and a dye are mixed in a supercritical fluid or a subcritical fluid, and a pressure reducing step in which the pressure is reduced after the mixing step, and the resin particles are in the supercritical fluid or A method for producing colored resin particles, which is a resin that does not dissolve in a subcritical fluid and whose dye is an oil-soluble dye, is disclosed. However, the resin particles dyed in the examples of the above-mentioned patent documents are all particles having a low degree of crosslinking, and in order to obtain dark colored particles from polymer particles having a very high degree of crosslinking such as used as a spacer. However, the above method was insufficient.

Japanese Patent Laid-Open No. 10-139830 JP 2004-161824 A

  The present invention has been made to solve the above-mentioned problems, and provides a method for dyeing polymer particles having a very high degree of crosslinking to produce colored particles having high darkness in a short time. It is the purpose.

  The above problem is that 60 to 100 parts by weight of a crosslinkable monomer having two or more unsaturated double bonds and one non-crosslinkable monomer having one unsaturated double bond with respect to 100 parts by weight of all monomers. It is solved by providing a method for producing colored particles, characterized in that polymer particles obtained by polymerizing 0 to 40 parts by weight are dyed in a supercritical fluid or a subcritical fluid.

  At this time, the crosslinkable monomer is preferably a (meth) acrylic acid ester monomer and / or a styrene monomer, and preferably has three or more unsaturated double bonds. Moreover, it is also preferable to superpose | polymerize using 0.1-10 weight part of polymerization initiators with respect to 100 weight part of all the monomers. At this time, the polymerization initiator is preferably a radical polymerization initiator composed of an organic peroxide or an azo compound.

  The supercritical fluid or subcritical fluid preferably contains a cosolvent. At this time, it is preferable to contain 0.1 to 20% of at least one co-solvent selected from the group consisting of alcohol, ketone, ester and aromatic hydrocarbon. Moreover, it is preferable that the temperature of the said supercritical fluid or subcritical fluid at the time of dyeing is 31-250 degreeC, and a pressure is 5-50 MPa.

The average particle diameter of the colored particles is preferably 0.1 to 20 μm, and the initial elastic modulus S _{10 at} 20 ° C. is preferably 200 to 1400 MPa. In a preferred embodiment, the colored particles are liquid crystal display element spacers.

  According to the method for producing colored particles of the present invention, colored particles having high darkness can be produced in a short time from polymer particles having a very high degree of crosslinking. In particular, it is suitable for producing colored spacers for liquid crystal display elements.

  The present invention is a method for producing colored particles by dyeing polymer particles having a very high degree of crosslinking in a supercritical fluid or subcritical fluid. The polymer particles used in the present invention have 60 to 100 parts by weight of a crosslinkable monomer having two or more unsaturated double bonds and one unsaturated double bond with respect to 100 parts by weight of all monomers. It is a polymer particle obtained by polymerizing 0 to 40 parts by weight of a non-crosslinkable monomer. When the crosslinkable monomer is less than 60 parts by weight with respect to 100 parts by weight of all monomers, the degree of crosslinking of the resulting polymer particles is low. Therefore, even from polymer particles having a very high degree of crosslinking, it is not possible to obtain the benefit of the present invention that colored particles having high darkness can be produced in a short time. In particular, when used as a spacer, the strength of the particles decreases, so the hardness and the compression recovery force after deformation become insufficient, making it difficult to make the gap between the transparent substrates constant. The addition amount of the crosslinkable monomer is preferably 70 parts by weight or more, more preferably 80 parts by weight or more, and further preferably 90 parts by weight or more. Substantially all monomers may be crosslinkable monomers.

  The crosslinkable monomer is not particularly limited as long as it is a monomer having two or more unsaturated double bonds in the molecule. For example, (meth) acrylic acid ester monomers, styrene monomers, vinyl ester monomers, N-substituted (meth) acrylamide monomers having two or more unsaturated double bonds in the molecule And allyl compound monomers. (Meth) acrylic acid ester monomers include (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate and other (poly) oxyalkylene glycol di (meth) acrylate; pentaerythritol Di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, di Pentaerythritol hexa (meth) acrylate, tripentaerythritol hepta (meth) acrylate, tripentaerythritol octa (meth) acrylate; trimethylolpropane tri Examples include (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate; glycerol di (meth) acrylate, and glycerol tri (meth) acrylate. An example of the styrene monomer is divinylbenzene. Examples of the N-substituted (meth) acrylamide monomer include N, N′-methylenebis (meth) acrylamide. Examples of vinyl ester monomers include divinyl adipate and divinyl sebacate. Examples of the allyl compound monomer include diallyl phthalate, diallyl acrylamide, triallyl (iso) cyanurate, and triallyl trimellitate. In addition to the above, divinyl ether, 1,4-vinyloxybutane, divinyl sulfone and the like can be used. These crosslinkable monomers can be used alone or in admixture of two or more. Among these, (meth) acrylic acid ester monomers and / or styrene monomers are preferably used.

  The crosslinkable monomer preferably has 3 or more unsaturated double bonds. By using such a monomer, polymer particles having a higher degree of crosslinking can be obtained, and the benefit of using the present invention is increased. It is more preferable to have four or more. Examples of the crosslinkable monomer having three unsaturated double bonds include pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, triallyl (iso) cyanurate, triallyl trimellitate, and trimethylol. Examples include propane tri (meth) acrylate and glycerol tri (meth) acrylate. Examples of the crosslinkable monomer having 4 or more unsaturated double bonds include pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, and dipentaerythritol penta. Examples include (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaerythritol hepta (meth) acrylate, and tripentaerythritol octa (meth) acrylate. The crosslinkable monomer having three or more unsaturated double bonds can be used alone or in combination of two or more. Moreover, it can also be used together with what has two or more crosslinkable monomers which have three or more unsaturated double bonds. It is more preferable to contain 60 parts by weight or more of a crosslinkable monomer having 3 or more unsaturated double bonds with respect to 100 parts by weight of all monomers. More preferably, it is 80 weight part or more, Most preferably, it is 90 weight part or more.

  The crosslinkable monomer can be copolymerized with a non-crosslinkable monomer having one unsaturated double bond. The non-crosslinkable monomer can be used in an amount of 0 to 40 parts by weight with respect to 100 parts by weight of all monomers. When the said non-crosslinkable monomer exceeds 40 weight part, the crosslinking degree of the polymer particle obtained will fall. Therefore, even from polymer particles having a very high degree of crosslinking, it is not possible to obtain the benefit of the present invention that colored particles having high darkness can be produced in a short time. The amount is preferably 30 parts by weight or less, more preferably 20 parts by weight or less, and still more preferably 10 parts by weight or less. It is also possible to use substantially no non-crosslinkable monomer.

  The non-crosslinkable monomer is not particularly limited as long as it has only one unsaturated double bond in the molecule. For example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, (meth ) (Meth) acrylate monomers such as t-butyl acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, glycidyl (meth) acrylate; styrene, p -Styrene monomers such as (m-) methylstyrene, α-methylstyrene, styrenesulfonic acid; Unsaturated carboxylic acid ester monomers such as dimethyl fumarate, dimethyl maleate, dimethyl itaconate; fumaric acid, Unsaturated carboxylic acid monomers such as maleic acid, (meth) acrylic acid and itaconic acid; ethyl vinyl ether Alkyl vinyl ethers such as methyl vinyl ether; N- alkyl-substituted (meth) acrylamide, can be used as a mixture (meth) nitrile-based monomer such as acrylonitrile or the like alone or in combination.

  In the first step of the method for producing colored particles of the present invention, polymer particles are produced by polymerizing the above-mentioned monomers. A known method is used as the polymerization method, but aqueous suspension polymerization is preferred. The aqueous suspension polymerization is carried out at a temperature of 25 to 100 ° C., more preferably 50 to 90 ° C. with stirring in the presence of a dispersion stabilizer according to a conventional method. Examples of the dispersion stabilizer used include water-soluble polymers such as gelatin, starch, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl pyrrolidone, polyvinyl alkyl ether, and polyvinyl alcohol; barium sulfate, calcium sulfate, barium carbonate, calcium carbonate, magnesium carbonate, phosphoric acid Examples include poorly water-soluble inorganic salts such as calcium; various nonionic, anionic and cationic surfactants.

  In the polymerization, it is preferable to use 0.1 to 10 parts by weight of a polymerization initiator with respect to 100 parts by weight of all monomers. If the polymerization initiator is less than 0.1 parts by weight, the polymerization rate may be very slow. More preferably, it is 0.2 parts by weight or more. On the other hand, when the polymerization initiator exceeds 10 parts by weight, the strength of the polymer particles required for spacer use may not be sufficiently obtained. In addition, a runaway reaction may occur and the polymerization rate may not be sufficiently controlled. More preferably, it is 8 parts by weight or less.

  The polymerization initiator used is not particularly limited, but a radical polymerization initiator composed of an organic peroxide or an azo compound is preferably used. More preferably, the polymerization-initiating radical species after decomposition is oil-soluble. Examples of the organic peroxide include benzoyl peroxide, lauroyl peroxide, t-butylperoxy-2-ethylhexanoate, di-t-butyl peroxide, cumyl hydroperoxide, and the like. Examples of the azo compound include azobisisobutyronitrile, azobiscyclohexacarbonitrile, azobis (2,4-dimethylvaleronitrile), and the like. These polymerization initiators can be used alone or in admixture of two or more. Organic peroxides are more preferably used because polymer particles with a higher degree of crosslinking are often obtained than when azo compounds are used.

  When the polymer particles obtained by polymerization as described above are used as a spacer, it is desirable that the particle size distribution is narrow, and therefore classification is preferably performed before the dyeing treatment described below. Moreover, after performing the dyeing | staining process about a polymer particle, it is also possible to give classification operation. However, it is usually preferable from the viewpoint of production efficiency to perform classification operation in advance before the dyeing treatment and dye only the polymer particles having a required particle size. Examples of the particle classification method include a sieving method, a water spray method, and a wind force method.

  The polymer particles are dyed in a supercritical fluid or subcritical fluid. By dyeing in a supercritical fluid or subcritical fluid, the dye can easily enter the polymer particles having a very high degree of cross-linking, and the dye can be sufficiently dyed. Here, the supercritical fluid is a fluid that has become a supercritical state by raising the temperature and pressure from the critical point inherent to the substance. The sub-supercritical fluid is a fluid in a subcritical state in which at least one of temperature and pressure is lower than the critical point and the compressed gas and the compressed liquid coexist.

  In the present invention, the substance used as the supercritical fluid or subcritical fluid is not particularly limited, but is preferably a gas at normal temperature and pressure from the viewpoint of handling. Examples thereof include carbon dioxide and nitrogen. Among these, carbon dioxide is more preferably used because it is generally harmless and inexpensive, and also has a critical temperature around room temperature and can easily obtain a supercritical state. Carbon dioxide has a critical temperature of 31 ° C. and a critical pressure of 7.2 MPa.

  The polymer particles are dyed in the supercritical fluid or subcritical fluid described above, but the dye used is not particularly limited, and dyes such as disperse dyes, direct dyes, oil-soluble dyes, reactive dyes, and fibers. In this case, dyes generally used can be used. Further, like an oxidation dye, a colorless precursor compound may be a dye that undergoes a polymerization or condensation reaction on the surface or inside of particles by an oxidation reaction to have a hue. It is not always necessary for dye molecules to penetrate into the polymer particles by dyeing in the supercritical fluid or subcritical fluid, even if the dye molecules remain only on the particle surface. Good.

  The amount of the dye added is preferably 0.05 g / L or more per unit volume of the supercritical fluid or subcritical fluid. If it is less than 0.05 g / L, sufficient dyeing may not be performed. More preferably, it is 0.1 g / L or more, More preferably, it is 0.2 g / L, Most preferably, it is 0.5 g / L. Moreover, it is usually 100 g / L or less.

  Moreover, it is preferable to add 3-50 weight part of dyes with respect to 100 weight part of polymer particles. If the amount is less than 3 parts by weight, sufficient dyeing may not be performed. More preferably 5 parts by weight or more, and still more preferably 10 parts by weight or more. On the other hand, if the amount exceeds 50 parts by weight, a large amount of undyed dye may remain on the particles in the tank after the dyeing treatment. More preferably, it is 30 parts by weight or less.

  In addition, it is preferable that the supercritical fluid or the subcritical fluid contains a cosolvent. This is because the co-solvent contained in the supercritical fluid or subcritical fluid causes the polymer particles to swell and the polymer chain between the crosslinking points to spread, thereby making it easier for the dye to penetrate into the interior. In addition, depending on the dye, the solubility in a supercritical fluid or subcritical fluid may increase, and the polymer particles may be dyed efficiently.

At this time, the supercritical fluid or subcritical fluid preferably contains 0.1 to 20% of a cosolvent. If it is less than 0.1%, the effect of adding a co-solvent may not appear. More preferably, it is 0.2%, further preferably 0.5% or more, and particularly preferably 1% or more. On the other hand, if it exceeds 20%, the affinity of the dye to the supercritical fluid is increased, so that the affinity for the particles is relatively lowered, and the dyeability is rather lowered in some cases. In addition, the amount of the co-solvent remaining in the dyeing vessel after the dyeing treatment is increased, which may be undesirable from the viewpoint of working environment and complexity of the post-treatment. The co-solvent component tends to remain in the polymer particles, and when used as a spacer, the liquid crystal or the like may be adversely affected. More preferably, it is 15% or less, More preferably, it is 10% or less, Most preferably, it is 5% or less. In addition, "%" here refers to the ratio of the volume under normal pressure of the co-solvent charged into the container filled with the supercritical fluid or subcritical fluid to the volume of the supercritical fluid or subcritical fluid, 100 times,
[(Volume of added co-solvent) / (volume of supercritical fluid or subcritical fluid)] × 100 (1)
It is shown by. This value is defined as the content (%) of the co-solvent. Usually, the volume of the supercritical fluid or subcritical fluid corresponds to the volume of the container.

  The compound used as the co-solvent is not particularly limited, and alcohol, ether, ketone, ester, aliphatic hydrocarbon, aromatic hydrocarbon and the like can be used. Examples of the alcohol include alcohols having a total carbon number of 12 or less such as methanol, ethanol and isopropanol. Examples of ethers include diethyl ether, tetrahydrofuran, and dioxane, ketones include acetone, methyl ethyl ketone, and cyclohexanone, esters include ethyl acetate and methyl acetate, and aliphatic hydrocarbons include hexane, heptane, and octane. Examples of the hydrocarbon include benzene, toluene, xylene and the like. Among these, at least one selected from the group consisting of alcohol, ketone, ester and aromatic hydrocarbon is preferable. More preferably, it is at least one selected from the group consisting of ketones, esters and aromatic hydrocarbons. The co-solvent is preferably effective in swelling the polymer particles, and aromatic hydrocarbons are particularly preferably used because of their great effects.

  Hereinafter, the dyeing process operation will be described. In the present invention, the polymer particles are dyed in a supercritical fluid or subcritical fluid in a dyeing vessel. A high-pressure vessel that can withstand high pressure is used as the dyeing vessel.

  Polymer particles and dye are put into a dyeing vessel. Thereafter, the inside of the container is pressurized to the target pressure by, for example, sending the gas supplied from the gas cylinder to the dyeing container using a high-pressure pump. Further, the inside of the container is heated to a target temperature, and the inside of the dyeing process container is brought into a supercritical state or a subcritical state.

  When carbon dioxide is used as the supercritical fluid or subcritical fluid, the pressure of the supercritical fluid or subcritical fluid is preferably 5 to 50 MPa. When the pressure is less than 5 MPa, the dye does not easily enter the polymer particles having a high degree of cross-linking, and thus the dyeing may not be sufficiently performed. More preferably, it is 7 MPa or more, More preferably, it is 10 MPa or more, Most preferably, it is 15 MPa or more. On the other hand, when the pressure exceeds 50 MPa, the apparatus becomes large and may be disadvantageous in terms of energy. More preferably, it is 30 MPa or less.

  The temperature of the supercritical fluid or subcritical fluid is preferably 31 to 250 ° C. If it is less than 31 ° C., the fluid mobility is insufficient, and it is difficult for the dye to enter the polymer particles having a high degree of cross-linking, and the dyeing may not be sufficiently performed. In particular, in order to sufficiently dye polymer particles having a very high degree of crosslinking such as those used for spacers, the temperature is preferably 90 ° C. or higher, more preferably 110 ° C. or higher, and particularly preferably 130 ° C. or higher. On the other hand, if it exceeds 250 ° C., the polymer particles to be dyed may be deformed or start to decompose. In addition, when the obtained colored particles are used as a spacer, the strength may be lowered and uneven thickness of the liquid crystal layer may be caused. More preferably, it is 225 degrees C or less, More preferably, it is 200 degrees C or less.

  When performing the dyeing process, it is preferable to perform the process while stirring the inside of the container with a stirrer or the like. This is because the polymer particles may be uniformly and efficiently dyed by stirring. Moreover, although the dyeing | staining process time is suitably selected by the magnitude | size, quantity, etc. of a polymer particle, it is suitable that it is 5 to 240 minutes. If it is less than 5 minutes, the polymer particles may not be sufficiently dyed. More preferably, it is 30 minutes or more. On the other hand, if it exceeds 240 minutes, it may be undesirable from the viewpoint of processing efficiency. More preferably, it is 180 minutes or less.

  In the case of using a co-solvent, the co-solvent can be supplied by a co-solvent addition pump in parallel with the gas supply, or the co-solvent may be put in the dyeing vessel in advance.

  The supercritical fluid or subcritical fluid is maintained at the target pressure by the back pressure valve until the end of dyeing. After completion of dyeing, the valve is opened and the pressure vessel is depressurized, and then the colored particles are taken out. Thereafter, it is washed and dried as necessary.

It is preferred initial modulus _{S 10} at 20 ° C. of the resulting colored particles are 200～1400MPa. The initial elastic modulus S _{10 at} 20 ° C. (hereinafter may be simply referred to as initial elastic modulus S ₁₀ ) is a load-compression applied to one sample particle spread on the sample stage in the direction of the center of the particle. The elastic modulus is obtained by measuring the displacement and multiplying the stress S obtained from the load P at the initial 10% compression displacement of the particle diameter by 10 to convert it to 100% displacement. The initial modulus S ₁₀ is correlative with a crosslinking degree of the polymer particles, the initial elastic modulus S ₁₀ as the degree of crosslinking increases have also been to increase. If the initial elastic modulus S ₁₀ is less than 200 MPa, low degree of crosslinking of the polymer particles, it is sometimes impossible to sufficiently obtain the benefits of the present invention. When used as a spacer, it may be difficult to make the gap between the transparent substrates constant. More preferably, it is 300 MPa or more, More preferably, it is 500 MPa or more. On the other hand, when it exceeds 1400 MPa, when used as a spacer, the alignment film of the liquid crystal element or the TFT substrate may be damaged. More preferably, it is 1000 MPa or less, More preferably, it is 800 MPa or less.

Here, the stress S [MPa] is derived from the following equation (2) obtained by using the Hiramatsu equation {Nikko Journal 81, 1024 (1965)}. Thus, initial modulus S ₁₀ in the present invention, as shown in the following formula (3) obtained by converting the resulting stress S of 10 times to 100% displacement by the following formula (2).
S = 2.8P / πd ² (2)
(Where P: 10% compression displacement load [N], d: particle diameter [mm])
S ₁₀ = 10S (3)

  The average particle diameter of the obtained colored particles is preferably 0.1 to 20 μm. Usually, the polymer particles can be dyed more easily as the particle diameter is smaller. However, when the degree of cross-linking of the polymer particles is very high, even if the particles are small, it is difficult to perform sufficient dyeing, so that the utility of using the present invention is great. If it exceeds 20 μm, the degree of cross-linking of the polymer particles is very high, so that there are cases where sufficient dyeing cannot be performed. Also, when used as a spacer, it is sometimes not preferable because the gap between the substrates is designed to be 20 μm or less. More preferably, it is 15 micrometers or less, More preferably, it is 12 micrometers or less. On the other hand, if it is less than 0.1 μm, dyeing is easy even if the degree of cross-linking of the polymer particles is high, and the utility of using the present invention may decrease. Moreover, it becomes difficult to obtain polymer particles having a narrow particle size distribution, which may not be preferable for use as a spacer. More preferably, it is 0.2 μm or more, and further preferably 1.0 μm or more.

  The use of the colored particles obtained by the production method of the present invention is not particularly limited, but is an extender such as paints and inks, additives to cosmetics and pastes for ironing, spacers for laminated glass, gap materials for sensors, Examples include spacers for liquid crystal display elements. Among these, a liquid crystal display element spacer is a preferred embodiment. This is because the spacer for a liquid crystal display element requires a certain degree of hardness and a compression recovery force after deformation, and as a result, a very high degree of crosslinking is required. Therefore, the advantage of using the present invention is great.

  Hereinafter, the present invention will be described specifically by way of examples.

A method for measuring the average particle diameter, a method for measuring the initial elastic modulus S ₁₀ at 20 ° C., a method for evaluating the darkness of colored particles, and a method for producing polymer particles are described below.

[Measurement method of average particle size]
For measurement of the average particle size, a Coulter Multitizer II type measuring device manufactured by Beckman Coulter, Inc. was used. About 30,000 particles were measured to obtain an average particle size and standard deviation. At the time of use, it calibrated using the company standard particles.

[Initial elastic modulus S _{10 at} 20 ° C.]
Using a Shimadzu Corporation “Shimadzu Micro Compression Tester MCTM-200”, a sample particle spread on the sample stage was loaded in the center direction of the particle, the load-compression displacement was measured, and the initial particle diameter was measured. The load at the time of 10% compression displacement was measured. The measurement was performed at about 20 ° C., and the compression rate was 0.27 g / sec. This operation was performed for five different particles whose diameters were observed to be the average, and the average value was defined as the load P. The average particle diameter obtained by the measurement method shown above was used as the particle diameter d, and was substituted into the following formula (2) together with the load P to determine the stress S. In order to convert this value into 100% displacement, it was substituted by the following formula (3) and multiplied by ₁₀ to calculate the initial elastic modulus S10 at 20 ° C.
S = 2.8P / πd ² (2)
S ₁₀ = 10S (3)

[Evaluation method of darkness of coloring]
The obtained colored particles are sandwiched between a microscope slide glass and a cover glass, spread without gaps, and using a colorimeter manufactured by Kurabo Industries Co., Ltd. (AUCOLOR-NF), spectral reflectance every 10 nm in the range of 380 to 720 nm. After measuring, the total K / S value was calculated, and the darkness was evaluated. The total K / S value is a value obtained by summing up the K / S values at each measurement wavelength obtained using the Kubeluka-Munk equation. A larger total K / S value indicates a darker color. Further, in the case of the same dye, a proportional relationship is established between the dyeing amount and the total K / S value.

[Method for producing polymer particles]
P-1
Preliminary analysis of 0.1 g of monomethoxyhydroquinone, 2 g of benzoyl peroxide (Nippon Yushi Co., Ltd., recrystallized with acetone), and a commercial product A containing pentaerythritol tetraacrylate as a main component (high-performance liquid chromatograph) Each component that can be identified from the earliest is 4% by weight of pentaerythritol triacrylate, 75% by weight of pentaerythritol tetraacrylate, 2% by weight of dipentaerythritol hexaacrylate, 13% by weight of tripentaerythritol octaacrylate, and the rest Unknown) After mixing 150 g with sufficient stirring under air at 40-43 ° C., it was put into 850 g of a 5% aqueous solution of polyvinyl alcohol (GH-17 manufactured by Nippon Synthetic Chemical Co., Ltd., saponification degree 87%). And stirring into fine particles It was dispersed. Thereafter, the temperature was raised after replacing with nitrogen, and suspension polymerization was carried out at 80 ° C. for 5 hours. The obtained polymer particles were sufficiently washed with water, and then classified. Particles having an average particle size of 6.30 μm and a standard deviation of 0.19 μm were collected and dried to obtain polymer particles P-1. Initial modulus _{S 10} at 20 ° C. was 720 MPa.

P-2
2 g of benzoyl peroxide (Nippon Yushi Co., Ltd., recrystallized with acetone) and 150 g of test chemical divinylbenzene grade 1 (Wako Pure Chemical Industries, Ltd.) were mixed with sufficient stirring under air at 40 to 43 ° C. Thereafter, the solution was put into 850 g of a 5% aqueous solution of polyvinyl alcohol (GH-17 manufactured by Nippon Synthetic Chemical Co., Ltd., saponification degree 87%), and dispersed into fine particles by stirring. Thereafter, the temperature was raised after replacing with nitrogen, and suspension polymerization was carried out at 80 ° C. for 5 hours. The obtained polymer particles were sufficiently washed with water, and then classified. Particles having an average particle diameter of 6.00 μm and a standard deviation of 0.17 μm were collected and dried to obtain polymer particles P-2. Initial modulus _{S 10} at 20 ° C. was 500 MPa.

Example 1
The polymer particles P-1 were dyed using the dyeing apparatus 1 shown in FIG. The dyeing apparatus 1 includes a carbon dioxide gas cylinder 2 that contains carbon dioxide, a high-pressure pump 3 that boosts carbon dioxide, a pump head cooler 4, a co-solvent tank 5, a co-solvent addition pump 6 for adding a co-solvent, a high-pressure vessel (capacity) 50 ml) 10, a pressure gauge 11, a back pressure valve 12, and a thermostatic chamber 13. In addition, stop valves 7, 8, 9 for the path are provided. Along with 0.3 g of polymer particles P-1, 0.05 g of Disperse Black FL-98 (manufactured by Nishino Kinryo Co., Ltd.) as a dye and 1 ml of xylene as a cosolvent were charged into a high-pressure vessel 10. After putting the high-pressure vessel 10 into the thermostatic chamber 13 heated to 150 ° C., carbon dioxide supplied from the carbon dioxide gas cylinder 2 was sent to the high-pressure vessel 10 by the high-pressure pump 3 and pressurized to 25 MPa. Here, the volume, temperature and pressure in the high-pressure vessel 10 can be regarded as the volume, temperature and pressure of the internal supercritical fluid. Also, the amount of dye added per unit volume of the supercritical fluid is calculated to be 1 g / L, and the cosolvent content is calculated to be 2%. The inside of the high-pressure vessel 10 was stirred with a stirrer 14 and treated for 120 minutes. The pressurized high-pressure carbon dioxide gas was held by the back pressure valve 12 so that the high-pressure vessel 10 became 25 MPa until the end of the dyeing process. After completion of the dyeing process, the stop valve 9 was opened and the dyed polymer particles were taken out. The obtained colored particles were dark black, and the darkness was evaluated. As a result, the total K / S value was determined to be 861. When the average particle diameter of the colored particles was measured, it was 6.37 μm, and when the initial elastic modulus S ₁₀ at 20 ° C. was measured, it was 685 MPa.

Examples 2-5
The polymer particles P-1 were dyed in the same manner as in Example 1 except that the temperature of the supercritical fluid was changed as shown in Table 1. The resulting colored particles were dyed darker black as the temperature increased. The evaluation results of dark color are summarized in Table 1 and FIG. Further, Table 1 shows the measurement results of the initial modulus S ₁₀ in average particle diameter and 20 ° C..

Examples 6-8
The polymer particles P-1 were dyed in the same manner as in Example 1 except that the content of the co-solvent was changed as shown in Table 1. The obtained colored particles were dyed dark black as the cosolvent content increased to 2%, and were most intensely dyed at 2%. The evaluation results of dark color are summarized in Table 1 and FIG. Further, Table 1 shows the measurement results of the initial modulus S ₁₀ in average particle diameter and 20 ° C..

Example 9
The polymer particles P-1 were dyed in the same manner as in Example 1 except that the pressure of the supercritical fluid was 15 MPa. The obtained colored particles, dark color of the evaluation results, showing the initial elastic modulus S ₁₀ measurements of the average particle diameter and 20 ° C. Table 1.

Example 10
The polymer particles P-2 were dyed in the same manner as in Example 1 except that P-2 was used instead of P-1 as the polymer particles. The obtained colored particles were dark black, and when the darkness was evaluated, the total K / S value was determined to be 770. Measurement results of the initial modulus S ₁₀ shown in Table 1 in the average particle diameter and 20 ° C..

Example 11
The polymer particles P-2 were dyed by the same method as in Example 10 except that the temperature of the supercritical fluid was 100 ° C. The obtained colored particles, dark color of the evaluation results, showing the initial elastic modulus S ₁₀ measurements of the average particle diameter and 20 ° C. Table 1.

Comparative Example 1
In a high-pressure vessel containing 30 ml of water, 0.3 g of polymer particles P-1 and 0.05 g of dye were charged. The high-pressure vessel was heated to 150 ° C., and the inside of the vessel was stirred with a stirrer to carry out a dyeing treatment. After completion of the dyeing process, the high-pressure vessel was cooled to room temperature, and the dyed polymer particles were taken out. The obtained colored particles were hardly dyed with light blue, and when the dark color was evaluated, the total K / S value was 73. The average particle diameter of the colored particles was measured to be 6.32 μm, and the initial elastic modulus S ₁₀ at 20 ° C. was measured to be 715 MPa.

As Table 1 and FIG. 2 showed, it turned out that colored particles with high darkness are obtained, so that the temperature of a supercritical fluid is high (Examples 1-5). Similar results were obtained for polymer particles P-2 (Examples 10 and 11). It was also found that colored particles with high darkness can be obtained as the pressure of the supercritical fluid increases (Example 9). Comparing the results, it can be said that temperature has a greater effect on darkness than pressure. On the other hand, as shown in Table 1 and FIG. 3, as the content of the co-solvent increases, colored particles with high darkness tend to be obtained, but at 3%, no further effect can be obtained. It was understood (Examples 6-8). On the other hand, it was found that when the dyeing treatment was performed in water, the polymer particles were hardly dyed (Comparative Example 1). From the above, it can be said that colored particles with high darkness can be obtained in a short time from polymer particles having a very high degree of crosslinking by dyeing in a supercritical fluid. Further, as the polymer particles are stained in the dark, tends initial modulus S ₁₀ decreases with the particle size increases were observed.

FIG. 1 is a process flow diagram of the staining apparatus used in Example 1. FIG. 2 is a graph plotting the total K / S value of the obtained colored particles against the temperature of the supercritical fluid. FIG. 3 is a graph plotting the total K / S value of the obtained colored particles against the content of the co-solvent.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dyeing device 2 Carbon dioxide gas cylinder 3 High pressure pump 4 Pump head cooler 5 Cosolvent tank 6 Cosolvent addition pump 7, 8, 9 Stop valve 10 High pressure vessel 11 Pressure gauge 12 Back pressure valve 13 Constant temperature bath 14 Stirrer

Claims (11)

60 to 100 parts by weight of a crosslinkable monomer having two or more unsaturated double bonds and 0 to 40 weights of a non-crosslinkable monomer having one unsaturated double bond with respect to 100 parts by weight of all monomers. A method for producing colored particles, characterized in that polymer particles obtained by polymerizing a part are dyed in a supercritical fluid or a subcritical fluid. The method for producing colored particles according to claim 1, wherein the crosslinkable monomer is a (meth) acrylic acid ester monomer and / or a styrene monomer. The method for producing colored particles according to claim 1 or 2, wherein the crosslinkable monomer has three or more unsaturated double bonds. The manufacturing method of the colored particle in any one of Claims 1-3 superposed | polymerized using 0.1-10 weight part of polymerization initiators with respect to 100 weight part of all the monomers. The method for producing colored particles according to claim 4, wherein the polymerization initiator is a radical polymerization initiator composed of an organic peroxide or an azo compound. The method for producing colored particles according to claim 1, wherein the supercritical fluid or subcritical fluid contains a cosolvent. The colored particles according to claim 1, wherein the supercritical fluid or subcritical fluid contains 0.1 to 20% of at least one co-solvent selected from the group consisting of alcohol, ketone, ester and aromatic hydrocarbon. Manufacturing method. The method for producing colored particles according to any one of claims 1 to 7, wherein the temperature of the supercritical fluid or subcritical fluid when dyeing is 31 to 250 ° C and the pressure is 5 to 50 MPa. The method for producing colored particles according to claim 1, wherein the colored particles have an average particle diameter of 0.1 to 20 μm. The method for producing colored particles according to claim 1, wherein the colored particles have an initial elastic modulus S ₁₀ at 20 ° C. of 200 to 1400 MPa. The method for producing colored particles according to claim 1, wherein the colored particles are a spacer for a liquid crystal display element.

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