WO2021095749A1 - Polyamide particles and method for manufacturing the same - Google Patents

Polyamide particles and method for manufacturing the same Download PDF

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Publication number
WO2021095749A1
WO2021095749A1 PCT/JP2020/041996 JP2020041996W WO2021095749A1 WO 2021095749 A1 WO2021095749 A1 WO 2021095749A1 JP 2020041996 W JP2020041996 W JP 2020041996W WO 2021095749 A1 WO2021095749 A1 WO 2021095749A1
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Prior art keywords
polyamide
particles
polyamide particles
solvent
solution
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PCT/JP2020/041996
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French (fr)
Japanese (ja)
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崇士 正木
大輔 村野
渉 古川
義紀 鈴木
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株式会社クレハ
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
    • C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
    • C08G69/08—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from amino-carboxylic acids
    • C08G69/14—Lactams
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/12—Powdering or granulating
    • C08J3/14—Powdering or granulating by precipitation from solutions

Definitions

  • the present invention relates to polyamide particles and a method for producing the same.
  • Spherical resin fine particles have smooth slipperiness and are used in various products such as cosmetics and paints.
  • Polyamide fine particles can be mentioned as spherical resin fine particles used in cosmetics, but resins such as polyamide 6 and polyamide 12, which are mainly used at present, basically do not have biodegradability.
  • Polyamide 4 is conventionally known as a resin having biodegradability among polyamides, and a technique for introducing various functional groups in order to control the physical properties of polyamide 4 is known (for example, Patent Document 1). reference).
  • the biodegradable spherical resin fine particles spherical particles composed of polyamide 4 are known (see, for example, Patent Document 2).
  • the particles described in Patent Document 2 can be produced by a relatively simple method. Further, in the method for producing particles described in Patent Document 2, by setting the concentration of polyamide in the solution to about 1% by mass, spherical polyamide particles having a particle size of 5 to 10 ⁇ m suitable for cosmetic use are produced. be able to.
  • One aspect of the present invention is to provide spherical polyamide particles having a particle size of about several ⁇ m, which is produced by precipitation from a high-concentration polyamide solution.
  • the polyamide particles according to one aspect of the present invention are spherical polyamide particles composed of polyamide.
  • the polyamide has a main chain composed of repeating structural units having at least one alkylene group and a site constituting at least one amide bond, and a terminal group located at the end of the main chain.
  • the alkylene group has 1 or more and 4 or less carbon atoms
  • at least one of the terminal groups is an alkyl group having 8 or more carbon atoms.
  • the average particle size of the polyamide particles is about several ⁇ m, that is, 1 ⁇ m or more and 10 ⁇ m or less.
  • the method for producing polyamide particles according to one aspect of the present invention is a method for producing spherical polyamide particles composed of polyamide, and the average particles of the produced polyamide particles are average particles.
  • the diameter is 1 ⁇ m or more and 10 ⁇ m or less
  • the polyamide and the solvent are heated to dissolve the polyamide in the solvent, and the polyamide solution obtained by the dissolution step is mixed with water and cooled. It includes a cooling step of precipitating the polyamide.
  • the polyamide has a main chain composed of repeating structural units having at least one alkylene group and a site constituting at least one amide bond, and a terminal group located at the end of the main chain.
  • the alkylene group has 1 or more and 4 or less carbon atoms, and at least one of the terminal groups uses polyamide which is an alkyl group having 8 or more carbon atoms, and an alcohol-based solvent is used as the solvent.
  • spherical polyamide particles having a particle size of about several ⁇ m which is produced by precipitation from a high-concentration polyamide solution.
  • the polyamide particles according to the embodiment of the present invention are spherical polyamide particles composed of polyamide.
  • polyamide The "polyamide” in the present embodiment is a polymer compound having a structure represented by -CONH-. More specifically, the polyamide in the present embodiment is located at the end of a main chain composed of repeating structural units having at least one alkylene group and at least one site forming an amide bond. It has a terminal group to be used.
  • the main chain of polyamide is composed of at least two or more of the above structural units linked together.
  • the number of structural units constituting the main chain can be appropriately determined from the viewpoint of realizing the desired size and shape of the polyamide particles of the polyamide solution.
  • the number of alkylene groups in the above structural unit is 1 or more and 4 or less.
  • the number of the alkylene groups is preferably 1 or more and 3 or less, and more preferably 1 or more and 2 or less.
  • the number of alkylenes in the structural unit may be the same in any structural unit, and the structural unit of polyamide may include structural units having different numbers of alkylene groups.
  • the above-mentioned alkylene group may be linear or branched chain.
  • the carbon number of the alkylene group in the structural unit is not limited, but is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less, and 3 (that is, "polyamide 4"). ) Is more preferable.
  • the site constituting the amide bond may be contained in one structural unit so as to form one or more amide bonds.
  • the site having an amide bond may be "-CONH-" in one structural unit, or a pair of "-CO-" and "-NH-" located at each end of one structural unit. It may be.
  • the number of sites constituting the amide bond is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less, when counted as an amide bond in one structural unit. It is more preferably 2 or less.
  • the number of sites constituting the amide bond in the structural unit may be the same in any of the structural units, and the structural unit of polyamide may include structural units having different numbers of the sites. Good.
  • At least one of the terminal groups of the structural unit is an alkyl group having 8 or more carbon atoms.
  • the alkyl group may be a linear alkyl group or a branched alkyl group.
  • the number of carbon atoms in the alkyl group of the terminal group can be appropriately determined from the viewpoint of forming particles of an appropriate size and shape by, for example, the granulation method described later.
  • the number of carbon atoms in the alkyl group of the terminal group may be 8 or more, 10 or more, 12 or more, 24 or less, and 20 or less. , 16 or less.
  • the weight average molecular weight (Mw) of the above-mentioned polyamide can be appropriately determined within the range in which the effect of the present embodiment can be obtained. If the Mw of the polyamide is too small, the amount of the polyamide particles dissolved in the solvent increases, so that the polyamide particles may not grow to a sufficient size by the granulation method described later, and the mechanical properties and heat resistance of the polyamide particles are deteriorated. May be inadequate. If the Mw of the polyamide is too large, the solubility in a solvent becomes insufficient, and the viscosity of the solution may be improved, so that the productivity of the polyamide particles may be lowered.
  • the Mw of the polyamide may be appropriately determined from these viewpoints, and may be, for example, 10,000 or more, 20,000 or more, or 30,000 or more. Further, from the above viewpoint, the Mw of the polyamide may be 800,000 or less, 600,000 or less, 300,000 or less, 200,000 or less, 100, It may be 000 or less.
  • the Mw of the polyamide can be obtained by a known technique such as gel permeation chromatography (GPC).
  • the above-mentioned polyamide may be a commercially available product or a synthetic product according to a known technique.
  • the above-mentioned terminal group and other group can be appropriately introduced into the molecular structure of polyamide by utilizing the technique described in Patent Document 1, for example.
  • the polyamide can be synthesized in the presence of a basic catalyst by polymerizing an organic compound having an appropriate lactam structure such as pyrrolidone by a ring-opening reaction using a specific ester compound as a polymerization initiator.
  • the specific ester compound as the polymerization initiator is, for example, the above-mentioned ester compound of a fatty acid having an alkyl group having a terminal group and a secondary alcohol.
  • the above-mentioned polyamide may be a commercially available product or a synthetic product according to a known technique, and preferred methods for producing the polyamide in the present embodiment include the following methods.
  • This preferred production method includes a step of polymerizing a monomer having a lactam structure using a fatty acid ester having a long-chain alkyl group having 8 or more and 24 or less carbon atoms as a polymerization initiator.
  • polymerization initiators include isopropyl myristate, isopropyl palmitate and isopropyl laurate. From the viewpoint of the shape of the granulated particles, the polymerization initiator is particularly preferably isopropyl myristate.
  • the polyamide particles of this embodiment are spherical. Whether or not the polyamide particles are spherical can be confirmed by observing the appearance or by a parameter indicating the degree of circularity.
  • the sphericity of the polyamide particles of the present embodiment is preferably 0.9 or more from the viewpoint of imparting sufficient slipperiness to the polyamide particles.
  • the sphericity can be obtained from the following equation (1).
  • n is the number of polyamide particles measured, and the minor axis and the major axis are the minimum and maximum diameters of the observed polyamide particles, respectively.
  • the sphericity of the polyamide particles of this embodiment can be measured by, for example, particle image analysis. It is preferable to measure the minor axis and the major axis of the polyamide particles from an optical micrograph or a scanning electron micrograph of the polyamide particles from the viewpoint of accurately measuring the sphericity.
  • the maximum value of sphericity is 1, and the larger the value, the closer the shape of the polyamide particles is to spheres.
  • the sphericity of the polyamide particles of the present embodiment is preferably 0.9 or more, and most preferably 1.0, from the viewpoint of slipperiness.
  • the sphericity may be appropriately determined according to the use of the polyamide particles, and may be less than 0.9 depending on the use.
  • the above sphericity can be achieved by a method of cooling a mixture of hot water and polyamide to precipitate polyamide particles, as described later. Further, the above-mentioned sphericity can be achieved by, for example, a spheroidizing treatment in which amorphous particles of polyamide are heat-treated by a pulverization method.
  • the average particle size of the polyamide particles of the present embodiment is 1 ⁇ m or more and 10 ⁇ m or less, more preferably 1 ⁇ m or more and 5 ⁇ m or less.
  • the average particle size of the polyamide particles in the present embodiment is obtained as the volume average particle size from the particle size measurement by the laser diffraction method.
  • the average particle size of the polyamide particles can be appropriately determined from the above range according to the use of the polyamide particles.
  • the polyamide particles of the present embodiment may further contain one or more other components as long as the effects of the present embodiment can be obtained.
  • the other components include composite components such as inorganic particles and fragrances.
  • Polyamide 4 or polyamide 3 is known to be biodegradable, and the polyamide particles of this embodiment are also biodegradable. Biodegradability means that it is degraded by microorganisms in soil or sea.
  • the polyamide particles of the present embodiment have a decomposition rate (decomposition degree) of at least two stages or more. Specifically, the decomposition rate is low in the initial stage of decomposition (for example, 0 to 7 days after the start of the biodegradability test described below), and 14 to 28 days after the start of the biodegradability test described below. The decomposition rate increases on the day). Polyamide particles having such decomposition characteristics have the effect of being slow to decompose during use, maintaining their physical properties, and rapidly decomposing after use.
  • the decomposition rate (%) of the polyamide particles is determined by the biodegradability test (activated sludge decomposition test) of JIS K 6950 and the elapsed time and BOD (Biochemical Oxygen Demand (mg)). Can be obtained by.
  • the decomposition rate (%) of the polyamide particles on the nth day after the start of the biodegradability test can be obtained by the following formula (3).
  • Decomposition rate (%) ⁇ (BOD of polyamide particles on day n of test start)-(BOD of empty test tube on day n of test start) ⁇ ⁇ TOD ⁇ 100 ...
  • TOD is the theoretical oxygen consumption required when the test substance is completely oxidized.
  • the decomposition rate of the polyamide particles on the 7th day after the start of the biodegradability test may be 10% or less, 5% or less, or 1% or less.
  • the decomposition rate of the polyamide particles on the 14th day after the start of the biodegradability test may be 20% or more, or 40% or more.
  • the decomposition rate of the polyamide particles on the 28th day after the start of the biodegradability test may be 50% or more, or 85% or more.
  • the polyamide particles of the present embodiment can be suitably produced by the methods shown below.
  • the method for producing polyamide particles in the present embodiment includes a dissolution step of heating the above-mentioned polyamide and a solvent to dissolve the polyamide in the solvent, and a cooling step of cooling the polyamide solution obtained by the dissolution step in water to precipitate the polyamide. And include.
  • the alcohol solvent is a liquid containing alcohol as a main component. It may be composed of only alcohol, or may be a solution containing other components as subcomponents, as will be described later.
  • the concentration of alcohol in the alcohol solvent may be, for example, 50% by mass or more, 80% by mass or more, or 90% by mass or more.
  • the alcohol in the alcohol solvent may be a mixed solvent of one kind or more as long as it can dissolve the polyamide.
  • the alcohol may be a monohydric alcohol or a divalent or higher polyhydric alcohol.
  • the above alcohol is preferably a polyhydric alcohol from the viewpoint of having a high boiling point and high solubility in polyamide. Examples of such alcohols include ethylene glycol, propylene glycol and glycerin. Of these, ethylene glycol or propylene glycol is more preferable.
  • the alcohol solvent may further contain components other than the above alcohol as long as the effects of the present embodiment can be obtained.
  • the other components may be one or more. Examples of such other components include surfactants and water-soluble polymers.
  • the concentration of the polyamide solution in the dissolution step is high from the viewpoint of increasing the productivity of the polyamide particles.
  • the "concentration of the polyamide solution” referred to here is the ratio of the amount of polyamide to the total amount of polyamide and solvent. From the above viewpoint, the concentration of the polyamide solution may be 5% by mass or more, 15% by mass or more, or 30% by mass or more. If the concentration is too high, the viscosity of the solution may increase, making it difficult to handle. For example, from such a viewpoint, the above concentration may be 40% by mass or less, 35% by mass or less, or 30% by mass or less.
  • the temperature of the polyamide and the solvent in the dissolution step is high from the viewpoint of increasing the concentration of the polyamide solution and increasing the productivity of the polyamide particles.
  • the temperature of the polyamide and the solvent in the dissolution step is also referred to as "dissolution temperature".
  • the solvent temperature can be appropriately determined depending on the above viewpoint and the type of solvent.
  • the melting temperature may be 150 ° C. or higher, 160 ° C. or higher, or 170 ° C. or higher.
  • the above dissolution temperature is equal to or lower than the boiling point of the alcohol in the alcohol solvent from the viewpoint of controlling the cooling rate in the next step.
  • the dissolution temperature can be appropriately determined according to such a viewpoint and the type of solvent.
  • the melting temperature may be 200 ° C. or lower, 190 ° C. or lower, or 180 ° C. or lower.
  • the dissolution time in the dissolution step is not limited, but may be 5 minutes or more, 10 minutes or more, or 30 minutes or more from the viewpoint of sufficiently dissolving the polyamide in the solvent.
  • the melting time is the time during which the desired melting temperature is maintained in the melting step.
  • the upper limit of the dissolution time is preferably short from the viewpoint of productivity of the polyamide particles, and can be appropriately determined according to such a viewpoint and the above-mentioned lower limit value of the dissolution time.
  • the polyamide solution obtained by the dissolution step is cooled in water to precipitate the polyamide.
  • the cooling step can be carried out, for example, by mixing the polyamide solution with water and cooling the mixture containing water, solvent (alcohol) and polyamide.
  • the temperature of the polyamide solution when mixed with water is not limited and may be equal to or lower than the above-mentioned dissolution temperature.
  • the temperature of the polyamide solution when mixed with water may be appropriately determined from the viewpoint of alleviating the temperature difference with the water to be mixed and from the viewpoint of preventing the precipitation of polyamide from the polyamide solution. More specifically, from the above viewpoint, the temperature of the polyamide solution when mixed with water may be equal to or higher than the melting temperature minus 50 ° C. and lower than the melting temperature.
  • the temperature of the water mixed with the polyamide solution is not limited.
  • the temperature of water when mixed with the polyamide solution can be appropriately determined from the viewpoint of alleviating the temperature difference with the polyamide solution to be mixed and from the viewpoint of preventing the rapid precipitation of polyamide from the polyamide solution. ..
  • the temperature of water when mixed with the polyamide solution may be 20 ° C. or higher, 40 ° C. or higher, 60 ° C. or higher, or 100 ° C. or lower. It may be 80 ° C. or lower, and may be 60 ° C. or lower.
  • the amount of water mixed with the polyamide solution in the cooling step is not limited. It is preferable that the amount of water when mixed with the polyamide solution is sufficiently larger than that of the polyamide solution from the viewpoint of precipitating polyamide so that polyamide particles are formed.
  • the amount of water mixed with the polyamide solution may be such that the final concentration of the polyamide solution is 5% by mass or less.
  • the "final concentration" is the mass of the polyamide solution with respect to the mixture when the entire amount of the polyamide solution is mixed with water.
  • polyamide is precipitated from the mixture so as to form polyamide particles, and finally the above-mentioned polyamide particles are produced.
  • the polyamide molecules dissolved in the solvent are regularly arranged in the mixture, whereby spherical polyamide is formed. It is believed that particles are formed.
  • the end point of the cooling step can be determined by the formation of polyamide particles having the desired properties.
  • the end point of the cooling step may be, for example, a time when the temperature of the mixture reaches room temperature (for example, 23 ° C.).
  • the above cooling step can be carried out, for example, by supplying the polyamide solution produced in the dissolution step to the water circulation flow path and controlling the temperature of the mixture while circulating the above-mentioned mixture in the circulation flow path. It is possible.
  • the method for producing polyamide particles in the present embodiment may further include steps other than the above-mentioned melting step and cooling step as long as the effects of the present embodiment can be obtained.
  • Examples of the other steps include a step of classifying the polyamide particles produced in the cooling step.
  • the polyamide particles of the present embodiment are biodegradable. Therefore, since the polyamide particles are decomposed in the environment, the load on the environment can be reduced as compared with the resin particles having no biodegradability. Further, since the polyamide particles of the present embodiment have a spherical shape, they have sufficiently high slipperiness.
  • the polyamide particles according to this embodiment are applied to various products that are composed of a composition containing powder and require relatively fine particles.
  • examples of such products include external preparations for skin such as cosmetics, paints and toners.
  • the above cosmetics include foundations, lipsticks and eyeshadows. Since the polyamide particles according to this embodiment are spherical, they have a property of uniformly scattering light. Therefore, the polyamide particles can be applied to cosmetics as a gloss adjuster in a content of, for example, 3% by mass or more.
  • the uses of the above paints are not limited, and examples include those for buildings, automobiles, metal products and electrical appliances.
  • the polyamide particles according to the present embodiment can be applied to a coating material as a gloss adjuster in a content of, for example, 10% by mass or more.
  • the polyamide particles according to this embodiment have excellent fluidity because they are spherical.
  • the polyamide particles can be applied to toner as a carrier for a colorant such as a pigment in a content of, for example, 40% by mass or more.
  • the polyamide particles according to the present embodiment are spherical polyamide particles composed of polyamide.
  • the polyamide has a main chain composed of repeating structural units having at least one alkylene group and a site constituting at least one amide bond, and a terminal group located at the end of the main chain.
  • the alkylene group has 1 or more and 4 or less carbon atoms.
  • At least one of the terminal groups is an alkyl group having 8 or more carbon atoms, and the average particle size of the polyamide particles is 1 ⁇ m or more and 10 ⁇ m or less.
  • spherical polyamide particles having a particle size of about several ⁇ m which are produced by precipitation from a polyamide solution having a sufficiently high concentration with respect to the production method described in Patent Document 2 described above, are provided. can do.
  • the sphericity of the polyamide particles may be 0.9 or more. This configuration is even more effective from the viewpoint of enhancing the characteristics of the polyamide particles as spherical particles in the present embodiment.
  • the alkyl group of the terminal group may be a linear alkyl group. This configuration is even more effective from the viewpoint of controlling the shape of the polyamide particles granulated by the precipitation of the polyamide in a spherical shape.
  • the alkylene group may have 3 carbon atoms. This configuration is even more effective from the viewpoint of enhancing the biodegradability of the polyamide particles.
  • the method for producing polyamide particles according to the present embodiment is a method for producing spherical polyamide particles composed of polyamide, and the average particle size of the produced polyamide particles is 1 ⁇ m or more and 10 ⁇ m or less.
  • the production method includes a dissolution step of heating the polyamide and a solvent to dissolve the polyamide in the solvent, and a cooling step of mixing the polyamide solution obtained by the dissolution step with water and cooling to precipitate the polyamide.
  • Polyamide has a main chain composed of repeating structural units having at least one alkylene group and a site constituting at least one amide bond, and an alkylene group having a terminal group located at the end of the main chain.
  • the number of carbon atoms in the above is 1 or more and 4 or less, and at least one of the terminal groups is a polyamide having an alkyl group having 8 or more carbon atoms.
  • Alcohol is used as the solvent.
  • spherical polyamide particles having a particle size of about several ⁇ m, which are produced by precipitation from a polyamide solution having a sufficiently high concentration with respect to the production method described in Patent Document 2 described above, are provided. can do.
  • the dissolution temperature in the dissolution step may be equal to or lower than the boiling point of the alcohol in the alcohol solvent. This configuration is even more effective from the viewpoint of appropriately controlling the cooling rate in the next step of dissolution.
  • Polyamide a is a polyamide 4 having a main chain having a repeating structural unit having an alkylene group having 3 carbon atoms formed by ring-opening of 2PDN, and an alkyl group having 13 carbon atoms bonded to at least one end thereof.
  • n is an integer of 2 or more.
  • Polyamide b was produced in the same manner as in Example 1 except that the polymerization initiator was changed to 14.8 g of adipoyldipyrrolidone instead of isopropyl myristate.
  • Polyamide b is a polyamide 4 having a methylene group having 4 carbon atoms in the middle portion of the polymer.
  • Polyamide c was produced in the same manner as in Example 1 except that the polymerization initiator was changed to 3.6 g of isopropyl acetate instead of isopropyl myristate.
  • Polyamide c is a polyamide 4 having an alkyl group (methyl) having 1 carbon atom at the terminal.
  • Polyamide d was produced in the same manner as in Example 1 except that the polymerization initiator was changed to 2.8 g of isopropyl myristate instead of isopropyl myristate.
  • Polyamide d is a polyamide 4 having an alkyl group (pentyl) having 5 carbon atoms at the terminal.
  • Measuring device SHODEX GPC-104 (Showa Denko) Column: Showa Denko HFIP606M 2 (series connection) Column temperature: 40 ° C Detector: RI Standard substance: Polymethylmethacrylate (PMMA)
  • Table 1 shows the measurement results of the type and molecular weight of the polymerization initiator for each of the polyamides a to d.
  • FIG. 1 is a diagram schematically showing a configuration in an example of a granulator for producing polyamide particles.
  • the granulator 1 sends out the melting tank 10 for dissolving the polyamide in the solvent, the cooling tank 20 for accommodating the fluid, and the fluid in the cooling tank 20 from the cooling tank 20. It also has a circulation flow path 30 that returns to the cooling tank 20.
  • the melting tank 10 has a stirrer 11. Further, the melting tank 10 has a jacket (not shown) for adjusting the temperature inside the melting tank 10.
  • the cooling tank 20 has a heater 21 for adjusting the temperature of the fluid to be accommodated.
  • the circulation flow path 30 has a pump 31 for sending the fluid in the cooling tank 20.
  • the fluid is, for example, water.
  • a discharge pipe 12 is connected to the bottom of the melting tank 10.
  • the discharge pipe 12 has a valve 13 for opening and closing the discharge pipe 12. Further, the discharge pipe 12 is connected to the circulation flow path 30. Further, the circulation flow path 30 has a switching valve 32.
  • a sampling tube 33 is connected to the switching valve 32.
  • the switching valve 32 is a valve capable of switching between the circulation flow path 30 and the flow path from the circulation flow path 30 to the sampling pipe 33.
  • the granulation device 1 is a device capable of producing polyamide particles from polyamide droplets by pouring a polyamide solution into temperature-controlled running water.
  • the amount of fluid in the cooling tank 20 is sufficient to circulate the fluid in the circulation flow path 30 and the cooling tank 20.
  • Example 1 Ethylene glycol (EG) as a solvent is housed in the dissolution tank 10 so that the amount of the polyamide a is 20% by mass. Next, the polyamide a was dissolved at 180 ° C. while stirring with the stirrer 11 to generate an EG solution of the polyamide a. "180 ° C.” is the temperature of the contents (polyamide a and EG) of the melting tank 10, and corresponds to the melting temperature.
  • the obtained EG solution of polyamide a was supplied to the circulation flow path 30 via the discharge pipe 12 and mixed with water at 80 ° C. circulating in the circulation flow path 30 at a speed of 1 L / min.
  • the obtained mixed liquid was discharged from the sampling tube 33, and the temperature of the mixed liquid was cooled to 40 ° C. over 2 hours by natural cooling.
  • the polyamide a particles were filtered off from the mixed solution, washed with water, and dried. In this way, the polyamide particles 1 which are the particles of the polyamide a were produced.
  • Example 2 3 g of polyamide a was weighed in a test tube having a content of 20 mL, and then 7 g of EG was added. Next, the polyamide a was dissolved in an oil bath at 170 ° C. to generate an EG solution of the solution of the polyamide a. The obtained EG solution of polyamide a was added to 100 mL of water at 80 ° C. with stirring, and then allowed to cool to obtain a mixed solution containing polyamide a particles. Then, the polyamide a particles were filtered off from the mixed solution, washed with water, and dried. In this way, the polyamide particles 2 were produced.
  • Polyamide particles 3 were produced in the same manner as in the production of polyamide particles 1 except that the solvent was changed to propylene glycol (PG) and the temperature of the PG solution of the polyamide a in the dissolution tank 10 was changed to 190 ° C.
  • PG propylene glycol
  • Polyamide particles 4 were produced in the same manner as in polyamide particles 2 except that the solvent was changed to glycerin (GL) and the dissolution temperature was changed to 180 ° C.
  • Polyamide particles 7 were produced in the same manner as in the production of polyamide particles 2 except that polyamide c was used instead of polyamide a. Further, the polyamide particles 8 were produced in the same manner as in the production of the polyamide particles 2 except that the polyamide d was used instead of the polyamide a.
  • Table 2 shows the granulation conditions and particle properties for each of the polyamide particles 1 to 8.
  • the shapes of the polyamide particles 1 to 4 are all spherical, and the average particle diameter of the polyamide particles 1 to 4 is about several ⁇ m. Further, the concentration of the polyamide solution at the time of granulating the polyamide particles 1 to 4 is as high as 20% by mass or 30% by mass. Therefore, according to Examples 1 to 4, by using alcohol as a solvent at the time of granulation and using polyamide 4 (polyamide a) having a linear alkyl group having 13 carbon atoms as a terminal group, the particle size is 10 ⁇ m or less. It can be seen that the spherical polyamide particles having a high production efficiency can be provided.
  • the reason why the small-diameter and spherical polyamide particles are generated by the above-mentioned granulation is that when the polyamide is precipitated from the polyamide solution, the polyamide molecules are formed, for example, the terminal group is on the center side of the particles. It is probable that it was arranged regularly.
  • the polyamide particles 5 and 6 are all spherical, but their average particle size exceeds 10 ⁇ m. Further, since the solvent at the time of granulation is water, the concentration of the polyamide solution at the time of granulation is as low as several mass%. It is considered that this is because the solubility of the polyamide b in water is low and the arrangement of the polyamide at the time of precipitation becomes irregular because it does not have a specific terminal group.
  • the polyamide particles 7 and 8 are both non-spherical, and their average particle diameter exceeds 40 ⁇ m. It is considered that this is because the alkyl group of the terminal group of the polyamide does not have a sufficient number of carbon atoms, so that the arrangement of the polyamide at the time of precipitation becomes irregular.
  • [1] and [2] show the evaluation results of the polyamide particles obtained in Example 1.
  • [3] and [4] show the evaluation results of cellulose.
  • [5] and [6] indicate the evaluation results of the blank test conducted at the same time as [1] to [4].
  • [7] and [8] show the evaluation results of the polyamide particles obtained in Comparative Example 1.
  • [9] and [10] indicate the evaluation results of the blank test conducted at the same time as [7] and [8].
  • the unit of BOD in Table 3 is mg.
  • the unit of decomposition rate is%.
  • the decomposition rate in Table 3 was calculated from the above formula (3).
  • the average value of [5] and [6] or the average value of [9] and [10] was used as the BOD of the blank test on the nth day after the start of the test.
  • the decomposition rate of the polyamide particles obtained in Example 1 on the 7th day after the start of the test was less than 10%.
  • the decomposition rate of the polyamide particles obtained in Example 1 on the 14th day after the start of the test was around 30%, and the decomposition rate was 85% or more on the 28th day after the start of the test.
  • the decomposition rate of the polyamide particles of Comparative Example 1 increased in proportion to the number of days elapsed until about 14 days after the start of the test, but after the 14th day, the rate of increase in the decomposition rate increased. It became smaller.
  • the present invention can provide particles of polyamide 4 having a relatively small diameter and a spherical shape.
  • the polyamide particles in the present invention can be applied to a composition requiring relatively small diameter and spherical resin particles as a material having functionality and a small environmental load.

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Abstract

These polyamide particles are formed from polyamide, are spherical, and have an average particle diameter of 1 μm–10 μm. The polyamide comprises a main chain of polyamide and an alkyl group with a carbon number of at least 8 located at a terminal of the main chain. These polyamide particles are manufactured by mixing an alcohol thermal solution of the polyamide with water and cooling the mixture.

Description

ポリアミド粒子およびその製造方法Polyamide particles and their manufacturing method
　本発明は、ポリアミド粒子およびその製造方法に関する。 The present invention relates to polyamide particles and a method for producing the same.
　球状の樹脂微粒子は、滑らかな滑り性を有し、化粧料および塗料などの様々な製品において用いられている。一方で、近年では樹脂材料の環境への負荷軽減が求められており、生分解性を有する樹脂材料への代替が検討されている。 Spherical resin fine particles have smooth slipperiness and are used in various products such as cosmetics and paints. On the other hand, in recent years, there has been a demand for reducing the burden on the environment of resin materials, and alternatives to biodegradable resin materials are being considered.
　化粧料に使用される球状の樹脂微粒子としてポリアミド微粒子が挙げられるが、現在主に使用されているポリアミド６、ポリアミド１２といった樹脂は、基本的に生分解性を有さない。ポリアミドの中で生分解性を有する樹脂としては、ポリアミド４が従来知られており、ポリアミド４の物性を制御するために種々の官能基を導入する技術が知られている（例えば、特許文献１参照）。また、生分解性を有する球状の樹脂微粒子としては、ポリアミド４で構成された球状の粒子が知られている（例えば、特許文献２参照）。 Polyamide fine particles can be mentioned as spherical resin fine particles used in cosmetics, but resins such as polyamide 6 and polyamide 12, which are mainly used at present, basically do not have biodegradability. Polyamide 4 is conventionally known as a resin having biodegradability among polyamides, and a technique for introducing various functional groups in order to control the physical properties of polyamide 4 is known (for example, Patent Document 1). reference). Further, as the biodegradable spherical resin fine particles, spherical particles composed of polyamide 4 are known (see, for example, Patent Document 2).
　さらに、ポリアミド４で構成された球状の粒子を製造する技術として、二酸化炭素の超臨界流体中または特定の有機溶媒中で２－ピロリドンを重合させることによって、ポリアミド４の球状の粒子を製造する方法が知られている（例えば、特許文献３、４参照）。 Further, as a technique for producing spherical particles composed of polyamide 4, a method for producing spherical particles of polyamide 4 by polymerizing 2-pyrrolidone in a supercritical fluid of carbon dioxide or in a specific organic solvent. Is known (see, for example, Patent Documents 3 and 4).
　特許文献２に記載の粒子は、比較的簡易な方法によって製造することができる。また、特許文献２に記載の粒子の製造方法は、溶液中のポリアミドの濃度を１質量％程度とすることによって、化粧料の用途に適した５～１０μｍの粒径の球状ポリアミド粒子を製造することができる。 The particles described in Patent Document 2 can be produced by a relatively simple method. Further, in the method for producing particles described in Patent Document 2, by setting the concentration of polyamide in the solution to about 1% by mass, spherical polyamide particles having a particle size of 5 to 10 μm suitable for cosmetic use are produced. be able to.
特開２００４－３３１７８０号公報Japanese Unexamined Patent Publication No. 2004-331780 国際公開第２０１７／１９５７０５号International Publication No. 2017/195705 特開２０１６－１８６０６８号公報Japanese Unexamined Patent Publication No. 2016-186068 国際公開第２０１９／０６９７９９号International Publication No. 2019/0697999
　一方で、ポリアミド粒子の製造方法では生産性のさらなる向上が求められている。たとえば、特許文献２に記載の製造方法であれば、造粒時における溶液中のポリアミドの濃度をより高くする観点から検討の余地が残されている。 On the other hand, there is a demand for further improvement in productivity in the method for producing polyamide particles. For example, in the case of the production method described in Patent Document 2, there is room for study from the viewpoint of increasing the concentration of polyamide in the solution at the time of granulation.
　本発明の一態様は、高い濃度のポリアミド溶液からの析出により生成される、数μｍ程度の粒径を有する球状のポリアミド粒子を提供することを目的とする。 One aspect of the present invention is to provide spherical polyamide particles having a particle size of about several μm, which is produced by precipitation from a high-concentration polyamide solution.
　上記の課題を解決するために、本発明の一態様に係るポリアミド粒子は、ポリアミドで構成されている球状のポリアミド粒子である。前記ポリアミドは、少なくとも１つのアルキレン基と少なくとも１つのアミド結合を構成する部位とを有する構造単位の繰り返しで構成される主鎖と、前記主鎖の端に位置する末端基とを有する。前記アルキレン基の炭素数は、１以上４以下であり、前記末端基の少なくとも１つは、炭素数８以上のアルキル基である。かつポリアミド粒子の平均粒子径は、数μｍ程度、すなわち１μｍ以上１０μｍ以下である。 In order to solve the above problems, the polyamide particles according to one aspect of the present invention are spherical polyamide particles composed of polyamide. The polyamide has a main chain composed of repeating structural units having at least one alkylene group and a site constituting at least one amide bond, and a terminal group located at the end of the main chain. The alkylene group has 1 or more and 4 or less carbon atoms, and at least one of the terminal groups is an alkyl group having 8 or more carbon atoms. Moreover, the average particle size of the polyamide particles is about several μm, that is, 1 μm or more and 10 μm or less.
　また、上記の課題を解決するために、本発明の一態様に係るポリアミド粒子の製造方法は、ポリアミドで構成されている球状のポリアミド粒子の製造方法であって、製造されるポリアミド粒子の平均粒子径は１μｍ以上１０μｍ以下であり、当該製造方法は、ポリアミドと溶媒とを加熱して前記ポリアミドを前記溶媒に溶解する溶解工程と、前記溶解工程により得られるポリアミド溶液を水と混合して冷却してポリアミドを析出させる冷却工程とを含む。前記ポリアミドには、少なくとも１つのアルキレン基と少なくとも１つのアミド結合を構成する部位とを有する構造単位の繰り返しで構成される主鎖と、前記主鎖の端に位置する末端基とを有し、前記アルキレン基の炭素数は、１以上４以下であり、前記末端基の少なくとも１つは、炭素数８以上のアルキル基であるポリアミドを用い、前記溶媒にはアルコール系溶媒を用いる。 Further, in order to solve the above problems, the method for producing polyamide particles according to one aspect of the present invention is a method for producing spherical polyamide particles composed of polyamide, and the average particles of the produced polyamide particles are average particles. The diameter is 1 μm or more and 10 μm or less, and in the production method, the polyamide and the solvent are heated to dissolve the polyamide in the solvent, and the polyamide solution obtained by the dissolution step is mixed with water and cooled. It includes a cooling step of precipitating the polyamide. The polyamide has a main chain composed of repeating structural units having at least one alkylene group and a site constituting at least one amide bond, and a terminal group located at the end of the main chain. The alkylene group has 1 or more and 4 or less carbon atoms, and at least one of the terminal groups uses polyamide which is an alkyl group having 8 or more carbon atoms, and an alcohol-based solvent is used as the solvent.
　本発明の一態様によれば、高い濃度のポリアミド溶液からの析出により生成される、数μｍ程度の粒径を有する球状のポリアミド粒子を提供することができる。 According to one aspect of the present invention, it is possible to provide spherical polyamide particles having a particle size of about several μm, which is produced by precipitation from a high-concentration polyamide solution.
本発明に係るポリアミド粒子の製造するための造粒装置の一例における構成を模式的に示す図である。It is a figure which shows typically the structure in the example of the granulation apparatus for manufacturing the polyamide particle which concerns on this invention.
　本発明の実施形態に係るポリアミド粒子は、ポリアミドで構成されている球状のポリアミド粒子である。 The polyamide particles according to the embodiment of the present invention are spherical polyamide particles composed of polyamide.
　（ポリアミド）
　本実施形態における「ポリアミド」とは、－ＣＯＮＨ－で表される構造を有する高分子化合物である。より具体的には、本実施形態におけるポリアミドは、少なくとも１つのアルキレン基と少なくとも１つのアミド結合を構成する部位とを有する構造単位の繰り返しで構成される主鎖と、当該主鎖の端に位置する末端基とを有する。 (polyamide)
The "polyamide" in the present embodiment is a polymer compound having a structure represented by -CONH-. More specifically, the polyamide in the present embodiment is located at the end of a main chain composed of repeating structural units having at least one alkylene group and at least one site forming an amide bond. It has a terminal group to be used.
　（ポリアミドの主鎖）
　ポリアミドの主鎖は、上記の構造単位の少なくとも二以上が連結して構成される。主鎖を構成する構造単位の数は、ポリアミド溶液のポリアミド粒子における所望の大きさおよび形状を実現させる観点から適宜に決めることができる。 (Main chain of polyamide)
The main chain of polyamide is composed of at least two or more of the above structural units linked together. The number of structural units constituting the main chain can be appropriately determined from the viewpoint of realizing the desired size and shape of the polyamide particles of the polyamide solution.
　（主鎖の構造単位）
　上記の構造単位におけるアルキレン基の数は、１以上４以下である。当該アルキレン基の数は、１以上３以下であることが好ましく、１以上２以下であることがより好ましい。なお、構造単位におけるアルキレン数は、いずれの構造単位においても同じであってもよいし、ポリアミドの構造単位には、アルキレン基の数が異なる構造単位が含まれていてもよい。 (Structural unit of main chain)
The number of alkylene groups in the above structural unit is 1 or more and 4 or less. The number of the alkylene groups is preferably 1 or more and 3 or less, and more preferably 1 or more and 2 or less. The number of alkylenes in the structural unit may be the same in any structural unit, and the structural unit of polyamide may include structural units having different numbers of alkylene groups.
　また、上記のアルキレン基は、直鎖状であってもよいし分岐鎖状であってもよい。また、構造単位におけるアルキレン基の炭素数は、限定されないが、１以上４以下であることが好ましく、１以上３以下であることがより好ましく、３であること（すなわち「ポリアミド４」であること）がさらに好ましい。 Further, the above-mentioned alkylene group may be linear or branched chain. The carbon number of the alkylene group in the structural unit is not limited, but is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less, and 3 (that is, "polyamide 4"). ) Is more preferable.
　また、アミド結合を構成する部位は、一以上のアミド結合を形成するように一構造単位中に含まれていればよい。たとえば、アミド結合を有する部位は、一構造単位中における「－ＣＯＮＨ－」であってもよいし、一構造単位の末端のそれぞれに位置する「－ＣＯ－」と「－ＮＨ－」との対であってもよい。当該アミド結合を構成する部位の数は、一構造単位中に、アミド結合として数えた場合に、１以上４以下有していることが好ましく、１以上３以下であることがより好ましく、１以上２以下であることがさらに好ましい。 Further, the site constituting the amide bond may be contained in one structural unit so as to form one or more amide bonds. For example, the site having an amide bond may be "-CONH-" in one structural unit, or a pair of "-CO-" and "-NH-" located at each end of one structural unit. It may be. The number of sites constituting the amide bond is preferably 1 or more and 4 or less, more preferably 1 or more and 3 or less, when counted as an amide bond in one structural unit. It is more preferably 2 or less.
　なお、構造単位におけるアミド結合を構成する部位の数は、いずれの構造単位においても同じであってもよいし、ポリアミドの構造単位には、当該部位の数が異なる構造単位が含まれていてもよい。 The number of sites constituting the amide bond in the structural unit may be the same in any of the structural units, and the structural unit of polyamide may include structural units having different numbers of the sites. Good.
　（ポリアミドの末端基）
　本実施形態において、上記の構造単位の末端基の少なくとも１つは、炭素数８以上のアルキル基である。当該アルキル基は、直鎖状のアルキル基であってもよいし、分枝状のアルキル基であってもよい。 (End group of polyamide)
In this embodiment, at least one of the terminal groups of the structural unit is an alkyl group having 8 or more carbon atoms. The alkyl group may be a linear alkyl group or a branched alkyl group.
　末端基のアルキル基における炭素数の数は、例えば後述の造粒法で適切なサイズおよび形状の粒子を形成する観点から適宜に決めることができる。たとえば、末端基のアルキル基における炭素数の数は、８以上であってよく、１０以上であってよく、１２以上であってもよいし、２４以下であってよく、２０以下であってよく、１６以下であってもよい。 The number of carbon atoms in the alkyl group of the terminal group can be appropriately determined from the viewpoint of forming particles of an appropriate size and shape by, for example, the granulation method described later. For example, the number of carbon atoms in the alkyl group of the terminal group may be 8 or more, 10 or more, 12 or more, 24 or less, and 20 or less. , 16 or less.
　（ポリアミドの重量平均分子量）
　上記のポリアミドの重量平均分子量（Ｍｗ）は、本実施形態の効果が得られる範囲において適宜に決めることができる。ポリアミドのＭｗは、小さすぎると、溶媒への溶解量が増加することで後述の造粒法で十分な大きさまでポリアミド粒子が成長しないことがあり、また、ポリアミド粒子の機械的物性および耐熱性が不十分となることがある。ポリアミドのＭｗが大きすぎると、溶媒への溶解性が不十分となり、また、溶解液の粘度が向上することによりポリアミド粒子の生産性が低下することがある。ポリアミドのＭｗは、これらの観点から適宜に決めてよく、例えば、１０，０００以上であってよく、２０，０００以上であってよく、３０，０００以上であってもよい。また、上記の観点から、ポリアミドのＭｗは、８００，０００以下であってよく、６００，０００以下であってよく、３００，０００以下であってよく、２００，０００以下であってよく、１００，０００以下であってもよい。 (Weight average molecular weight of polyamide)
The weight average molecular weight (Mw) of the above-mentioned polyamide can be appropriately determined within the range in which the effect of the present embodiment can be obtained. If the Mw of the polyamide is too small, the amount of the polyamide particles dissolved in the solvent increases, so that the polyamide particles may not grow to a sufficient size by the granulation method described later, and the mechanical properties and heat resistance of the polyamide particles are deteriorated. May be inadequate. If the Mw of the polyamide is too large, the solubility in a solvent becomes insufficient, and the viscosity of the solution may be improved, so that the productivity of the polyamide particles may be lowered. The Mw of the polyamide may be appropriately determined from these viewpoints, and may be, for example, 10,000 or more, 20,000 or more, or 30,000 or more. Further, from the above viewpoint, the Mw of the polyamide may be 800,000 or less, 600,000 or less, 300,000 or less, 200,000 or less, 100, It may be 000 or less.
　ポリアミドのＭｗは、ゲルパーミエーションクロマトグラフィ（ＧＰＣ）などの公知の技術によって求めることが可能である。 The Mw of the polyamide can be obtained by a known technique such as gel permeation chromatography (GPC).
　（ポリアミドの入手法）
　なお、上記のポリアミドは、市販品であってもよいし、公知の技術による合成品であってもよい。上記の末端基および他の基は、例えば、特許文献１に記載された技術を利用して適宜にポリアミドの分子構造中に導入することが可能である。 (How to obtain polyamide)
The above-mentioned polyamide may be a commercially available product or a synthetic product according to a known technique. The above-mentioned terminal group and other group can be appropriately introduced into the molecular structure of polyamide by utilizing the technique described in Patent Document 1, for example.
　たとえば、当該ポリアミドは、塩基性触媒の存在下で、特定のエステル化合物を重合開始剤として、ピロリドンなどの適当なラクタム構造を有する有機化合物を、開環反応により重合させることによって合成することが可能である。重合開始剤としての特定のエステル化合物とは、例えば、前述の末端基のアルキル基を有する脂肪酸と二級アルコールとのエステル化合物である。本実施形態のポリアミドの合成には、この他に、アミノ酸を自己縮合させることによるポリアミドの合成、および、ジアミンとジカルボン酸との縮合反応によるポリアミドの合成、を利用することが可能である。 For example, the polyamide can be synthesized in the presence of a basic catalyst by polymerizing an organic compound having an appropriate lactam structure such as pyrrolidone by a ring-opening reaction using a specific ester compound as a polymerization initiator. Is. The specific ester compound as the polymerization initiator is, for example, the above-mentioned ester compound of a fatty acid having an alkyl group having a terminal group and a secondary alcohol. In addition to this, for the synthesis of the polyamide of the present embodiment, it is possible to utilize the synthesis of the polyamide by self-condensing amino acids and the synthesis of the polyamide by the condensation reaction of diamine and a dicarboxylic acid.
　（ポリアミドの製造方法）
　なお、上記ポリアミドは、市販品であってもよいし、公知技術による合成品であってもよいが、本実施形態におけるポリアミドの好ましい製造方法には、以下の方法が挙げられる。この好ましい製造方法とは、ラクタム構造を有するモノマーを、重合開始剤としては炭素数８以上２４以下の長鎖アルキル基を有する脂肪酸エステルを用いて重合させる工程を含む。当該重合開始剤の例には、ミリスチン酸イソプロピル、パルミチン酸イソプロピルおよびラウリン酸イソプロピルが含まれる。造粒される粒子の形状の観点から、重合開始剤は、ミリスチン酸イソプロピルであることが特に好ましい。 (Polyamide manufacturing method)
The above-mentioned polyamide may be a commercially available product or a synthetic product according to a known technique, and preferred methods for producing the polyamide in the present embodiment include the following methods. This preferred production method includes a step of polymerizing a monomer having a lactam structure using a fatty acid ester having a long-chain alkyl group having 8 or more and 24 or less carbon atoms as a polymerization initiator. Examples of such polymerization initiators include isopropyl myristate, isopropyl palmitate and isopropyl laurate. From the viewpoint of the shape of the granulated particles, the polymerization initiator is particularly preferably isopropyl myristate.
　〔ポリアミド粒子〕
　本実施形態のポリアミド粒子は球状である。ポリアミド粒子が球状であるか否かは、外観の観察または円形の度合いを表すパラメータによって確認することが可能である。 [Polyamide particles]
The polyamide particles of this embodiment are spherical. Whether or not the polyamide particles are spherical can be confirmed by observing the appearance or by a parameter indicating the degree of circularity.
　（真球度）
　本実施形態のポリアミド粒子の真球度は、ポリアミド粒子に十分な滑り性を付与する観点から、０．９以上であることが好ましい。真球度は、下記式（１）から求めることができる。下記式中、ｎは、測定したポリアミド粒子の数であり、短径および長径は、それぞれ、観察されるポリアミド粒子の最小径および最大径である。 (Spherical degree)
The sphericity of the polyamide particles of the present embodiment is preferably 0.9 or more from the viewpoint of imparting sufficient slipperiness to the polyamide particles. The sphericity can be obtained from the following equation (1). In the following formula, n is the number of polyamide particles measured, and the minor axis and the major axis are the minimum and maximum diameters of the observed polyamide particles, respectively.
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
　本実施形態のポリアミド粒子の真球度は、例えば粒子画像解析により測定することができる。ポリアミド粒子の光学顕微鏡写真または走査型電子顕微鏡写真からポリアミド粒子の短径および長径を測定することが、真球度を正確に測定する観点から好ましい。 The sphericity of the polyamide particles of this embodiment can be measured by, for example, particle image analysis. It is preferable to measure the minor axis and the major axis of the polyamide particles from an optical micrograph or a scanning electron micrograph of the polyamide particles from the viewpoint of accurately measuring the sphericity.
　真球度の最大値は１であり、大きい程ポリアミド粒子の形状が真球に近いことを示している。本実施形態のポリアミド粒子の真球度は、滑り性の観点から０．９以上であることが好ましく、１．０であることが最も好ましい。なお、当該真球度は、ポリアミド粒子の用途に応じて適宜に決めてよく、用途によっては０．９未満であってもよい。 The maximum value of sphericity is 1, and the larger the value, the closer the shape of the polyamide particles is to spheres. The sphericity of the polyamide particles of the present embodiment is preferably 0.9 or more, and most preferably 1.0, from the viewpoint of slipperiness. The sphericity may be appropriately determined according to the use of the polyamide particles, and may be less than 0.9 depending on the use.
　上記の真球度は、後述するような、熱水とポリアミドとの混合物を冷却してポリアミド粒子を析出させる方法によって達成することが可能である。また、上記の真球度は、例えば粉砕法によるポリアミドの不定形の粒子を熱処理する球形化処理によって達成することが可能である。 The above sphericity can be achieved by a method of cooling a mixture of hot water and polyamide to precipitate polyamide particles, as described later. Further, the above-mentioned sphericity can be achieved by, for example, a spheroidizing treatment in which amorphous particles of polyamide are heat-treated by a pulverization method.
　（平均粒子径）
　本実施形態のポリアミド粒子の平均粒子径は、１μｍ以上１０μｍ以下、より好ましくは１μｍ以上５μｍ以下である。本実施形態におけるポリアミド粒子の平均粒子径は、レーザー回折法による粒子径測定から、体積平均粒子径として求められる。本実施形態では、ポリアミド粒子の平均粒子径は、当該ポリアミド粒子の用途に応じて上記の範囲から適宜に決めることが可能である。 (Average particle size)
The average particle size of the polyamide particles of the present embodiment is 1 μm or more and 10 μm or less, more preferably 1 μm or more and 5 μm or less. The average particle size of the polyamide particles in the present embodiment is obtained as the volume average particle size from the particle size measurement by the laser diffraction method. In the present embodiment, the average particle size of the polyamide particles can be appropriately determined from the above range according to the use of the polyamide particles.
　（ポリアミド粒子における任意成分）
　本実施形態のポリアミド粒子は、本実施形態の効果が得られる範囲において、他の成分を一種またはそれ以上、さらに含有していてもよい。当該他の成分の例には、無機粒子、香料などの複合成分が挙げられる。 (Arbitrary component in polyamide particles)
The polyamide particles of the present embodiment may further contain one or more other components as long as the effects of the present embodiment can be obtained. Examples of the other components include composite components such as inorganic particles and fragrances.
　（ポリアミド粒子の分解性）
　ポリアミド４またはポリアミド３は生分解性を有することが知られており、本実施形態のポリアミド粒子もまた、生分解性を有する。生分解性とは、土壌または海中の微生物によって分解されることを示す。 (Degradability of polyamide particles)
Polyamide 4 or polyamide 3 is known to be biodegradable, and the polyamide particles of this embodiment are also biodegradable. Biodegradability means that it is degraded by microorganisms in soil or sea.
　本実施形態のポリアミド粒子は、少なくとも２段階以上の分解率（分解度）を有する。具体的には分解初期（例えば、下記の生分解性試験開始後０日目～７日目）には分解率が低く、分解中期（例えば、下記の生分解性試験開始後１４日目～２８日目）に分解率が高くなる。このような分解特性を有するポリアミド粒子は、使用時は分解が遅く物性を維持し、使用後は速やかに分解するという効果を奏する。 The polyamide particles of the present embodiment have a decomposition rate (decomposition degree) of at least two stages or more. Specifically, the decomposition rate is low in the initial stage of decomposition (for example, 0 to 7 days after the start of the biodegradability test described below), and 14 to 28 days after the start of the biodegradability test described below. The decomposition rate increases on the day). Polyamide particles having such decomposition characteristics have the effect of being slow to decompose during use, maintaining their physical properties, and rapidly decomposing after use.
　本実施形態において、ポリアミド粒子の分解率（％）は、ＪＩＳ　Ｋ　６９５０の生分解性試験（活性汚泥分解試験）により、経過時間とＢＯＤ（生物化学的酸素消費量；Biochemical Oxygen Demand（ｍｇ））により求めることができる。 In the present embodiment, the decomposition rate (%) of the polyamide particles is determined by the biodegradability test (activated sludge decomposition test) of JIS K 6950 and the elapsed time and BOD (Biochemical Oxygen Demand (mg)). Can be obtained by.
　例えば、上記生分解性試験を開始してからｎ日目のポリアミド粒子の分解率（％）は、以下の式（３）のように求めることができる。
　分解率（％）＝｛（試験開始ｎ日目のポリアミド粒子のＢＯＤ）－（試験開始ｎ日目の空試験管のＢＯＤ）｝÷ＴＯＤ×１００・・・（３）
　式（３）中、ＴＯＤは、被験物質が完全に酸化された場合に必要される理論的酸素消費量である。 For example, the decomposition rate (%) of the polyamide particles on the nth day after the start of the biodegradability test can be obtained by the following formula (3).
Decomposition rate (%) = {(BOD of polyamide particles on day n of test start)-(BOD of empty test tube on day n of test start)} ÷ TOD × 100 ... (3)
In formula (3), TOD is the theoretical oxygen consumption required when the test substance is completely oxidized.
　例えば、上記生分解性試験を開始してから７日目のポリアミド粒子の分解率は１０％以下であってもよく、５％以下であってもよく、１％以下であってもよい。また、上記生分解性試験を開始してから１４日目のポリアミド粒子の分解率は２０％以上であってもよく、４０％以上であってもよい。また、上記生分解性試験を開始してから２８日目のポリアミド粒子の分解率は５０％以上であってもよく、８５％以上であってもよい。 For example, the decomposition rate of the polyamide particles on the 7th day after the start of the biodegradability test may be 10% or less, 5% or less, or 1% or less. Further, the decomposition rate of the polyamide particles on the 14th day after the start of the biodegradability test may be 20% or more, or 40% or more. Further, the decomposition rate of the polyamide particles on the 28th day after the start of the biodegradability test may be 50% or more, or 85% or more.
　本実施形態のポリアミド粒子は、以下に示す方法によって好適に製造することができる。 The polyamide particles of the present embodiment can be suitably produced by the methods shown below.
　〔ポリアミド粒子の製造方法〕
　本実施形態におけるポリアミド粒子の製造方法は、前述のポリアミドと溶媒とを加熱してポリアミドを溶媒に溶解する溶解工程と、溶解工程により得られるポリアミド溶液を水中で冷却してポリアミドを析出させる冷却工程とを含む。 [Manufacturing method of polyamide particles]
The method for producing polyamide particles in the present embodiment includes a dissolution step of heating the above-mentioned polyamide and a solvent to dissolve the polyamide in the solvent, and a cooling step of cooling the polyamide solution obtained by the dissolution step in water to precipitate the polyamide. And include.
　（溶解工程）
　本実施形態における溶解工程は、前述したポリアミドを熱溶媒に溶解する。本実施形態では、溶媒にはアルコール系溶媒を用いる。 (Melting process)
In the dissolution step in this embodiment, the above-mentioned polyamide is dissolved in a hot solvent. In this embodiment, an alcohol solvent is used as the solvent.
　当該アルコール系溶媒は、アルコールを主成分として含有する液である。アルコールのみから構成されていてもよいし、後述するように、副成分としての他の成分を含有する溶液であってもよい。アルコール系溶媒中におけるアルコールの濃度は、例えば５０質量％以上であってよく、８０質量％以上であってよく、９０質量％以上であってよい。 The alcohol solvent is a liquid containing alcohol as a main component. It may be composed of only alcohol, or may be a solution containing other components as subcomponents, as will be described later. The concentration of alcohol in the alcohol solvent may be, for example, 50% by mass or more, 80% by mass or more, or 90% by mass or more.
　当該アルコール系溶媒中のアルコールは、ポリアミドを溶解可能であればよく、一種でもそれ以上の混合溶媒であってもよい。当該アルコールは、一価のアルコールでもよいし、二価以上の多価アルコールであってもよい。上記のアルコールは、沸点が高く、ポリアミドに対する溶解性が高い観点から、多価アルコールであることが好ましい。当該アルコールの例には、エチレングリコール、プロピレングリコールおよびグリセリンが含まれる。中でも、エチレングリコールまたはプロピレングリコールがより好ましい。 The alcohol in the alcohol solvent may be a mixed solvent of one kind or more as long as it can dissolve the polyamide. The alcohol may be a monohydric alcohol or a divalent or higher polyhydric alcohol. The above alcohol is preferably a polyhydric alcohol from the viewpoint of having a high boiling point and high solubility in polyamide. Examples of such alcohols include ethylene glycol, propylene glycol and glycerin. Of these, ethylene glycol or propylene glycol is more preferable.
　アルコール系溶媒は、上述のように、本実施形態の効果が得られる範囲において、上記のアルコール以外の他の成分をさらに含有していてもよい。当該他の成分も、一種でもそれ以上でもよい。当該他の成分の例には、界面活性剤および水溶性ポリマーが含まれる。 As described above, the alcohol solvent may further contain components other than the above alcohol as long as the effects of the present embodiment can be obtained. The other components may be one or more. Examples of such other components include surfactants and water-soluble polymers.
　溶解工程におけるポリアミド溶液の濃度は、高いことが、ポリアミド粒子の生産性を高める観点から好ましい。なお、ここで言う「ポリアミド溶液の濃度」とは、ポリアミドと溶媒との総量に対するポリアミドの量の割合である。上記のような観点から、ポリアミド溶液の濃度は、５質量％以上であってよく、１５質量％以上であってよく、３０質量％以上であってもよい。当該濃度は、高すぎると、溶液の粘度が高くなって取り扱いにくくなることがある。たとえばこのような観点から、上記の濃度は、４０質量％以下であってよく、３５質量％以下であってよく、３０質量％以下であってもよい。 It is preferable that the concentration of the polyamide solution in the dissolution step is high from the viewpoint of increasing the productivity of the polyamide particles. The "concentration of the polyamide solution" referred to here is the ratio of the amount of polyamide to the total amount of polyamide and solvent. From the above viewpoint, the concentration of the polyamide solution may be 5% by mass or more, 15% by mass or more, or 30% by mass or more. If the concentration is too high, the viscosity of the solution may increase, making it difficult to handle. For example, from such a viewpoint, the above concentration may be 40% by mass or less, 35% by mass or less, or 30% by mass or less.
　溶解工程におけるポリアミドおよび溶媒の温度は、高いことが、ポリアミド溶液の濃度を高め、ポリアミド粒子の生産性を高める観点から好ましい。なお、溶解工程におけるポリアミドおよび溶媒の温度を「溶解温度」とも言う。溶媒温度は、上記の観点、および、溶媒の種類に応じて適宜に決めることができる。たとえば、溶解温度は、１５０℃以上であってよいし、１６０℃以上であってよいし、１７０℃以上であってもよい。 It is preferable that the temperature of the polyamide and the solvent in the dissolution step is high from the viewpoint of increasing the concentration of the polyamide solution and increasing the productivity of the polyamide particles. The temperature of the polyamide and the solvent in the dissolution step is also referred to as "dissolution temperature". The solvent temperature can be appropriately determined depending on the above viewpoint and the type of solvent. For example, the melting temperature may be 150 ° C. or higher, 160 ° C. or higher, or 170 ° C. or higher.
　一方、上記の溶解温度は、アルコール系溶媒中のアルコールの沸点以下であることが、次工程の冷却速度を制御する観点から好ましい。溶解温度は、このような観点および溶媒の種類に応じて適宜に決めることができる。たとえば、溶解温度は、２００℃以下であってよいし、１９０℃以下であってよいし、１８０℃以下であってもよい。 On the other hand, it is preferable that the above dissolution temperature is equal to or lower than the boiling point of the alcohol in the alcohol solvent from the viewpoint of controlling the cooling rate in the next step. The dissolution temperature can be appropriately determined according to such a viewpoint and the type of solvent. For example, the melting temperature may be 200 ° C. or lower, 190 ° C. or lower, or 180 ° C. or lower.
　溶解工程における溶解時間は、限定されないが、ポリアミドを溶媒に十分に溶解させる観点から、５分以上であってよいし、１０分以上であってよいし、３０分以上であってもよい。なお、溶解時間とは、溶解工程において所期の溶解温度を維持している時間である。溶解時間の上限は、ポリアミド粒子の生産性の観点からは短いことが好ましく、このような観点、および、溶解時間の上記の下限値に応じて、適宜に決めることができる。 The dissolution time in the dissolution step is not limited, but may be 5 minutes or more, 10 minutes or more, or 30 minutes or more from the viewpoint of sufficiently dissolving the polyamide in the solvent. The melting time is the time during which the desired melting temperature is maintained in the melting step. The upper limit of the dissolution time is preferably short from the viewpoint of productivity of the polyamide particles, and can be appropriately determined according to such a viewpoint and the above-mentioned lower limit value of the dissolution time.
　（冷却工程）
　冷却工程は、溶解工程により得られるポリアミド溶液を水中で冷却してポリアミドを析出させる。冷却工程は、例えば、ポリアミド溶液を水と混合し、水、溶媒（アルコール）およびポリアミドを含有する混合物を冷却することによって実施することが可能である。 (Cooling process)
In the cooling step, the polyamide solution obtained by the dissolution step is cooled in water to precipitate the polyamide. The cooling step can be carried out, for example, by mixing the polyamide solution with water and cooling the mixture containing water, solvent (alcohol) and polyamide.
　冷却工程において、水と混合する時のポリアミド溶液の温度は、限定されず、前述の溶解温度以下であってよい。たとえば、水と混合する時のポリアミド溶液の温度は、混合する水との温度差を緩和する観点、および、ポリアミド溶液からのポリアミドの析出を防止する観点から、適宜決めてよい。より具体的には、上記の観点から、水と混合する時のポリアミド溶液の温度は、溶解温度から５０℃引いた温度以上溶解温度以下であってよい。 In the cooling step, the temperature of the polyamide solution when mixed with water is not limited and may be equal to or lower than the above-mentioned dissolution temperature. For example, the temperature of the polyamide solution when mixed with water may be appropriately determined from the viewpoint of alleviating the temperature difference with the water to be mixed and from the viewpoint of preventing the precipitation of polyamide from the polyamide solution. More specifically, from the above viewpoint, the temperature of the polyamide solution when mixed with water may be equal to or higher than the melting temperature minus 50 ° C. and lower than the melting temperature.
　冷却工程において、ポリアミド溶液と混合する水の温度は、限定されない。たとえば、ポリアミド溶液と混合する時の水の温度は、混合するポリアミド溶液との温度差を緩和する観点、および、ポリアミド溶液からのポリアミドの急激な析出を防止する観点から、適宜に決めることができる。このような観点から、ポリアミド溶液と混合する時の水の温度は、２０℃以上であってよく、４０℃以上であってよく、６０℃以上であってもよいし、１００℃以下であってよく、８０℃以下であってよく、６０℃以下であってもよい。 In the cooling process, the temperature of the water mixed with the polyamide solution is not limited. For example, the temperature of water when mixed with the polyamide solution can be appropriately determined from the viewpoint of alleviating the temperature difference with the polyamide solution to be mixed and from the viewpoint of preventing the rapid precipitation of polyamide from the polyamide solution. .. From this point of view, the temperature of water when mixed with the polyamide solution may be 20 ° C. or higher, 40 ° C. or higher, 60 ° C. or higher, or 100 ° C. or lower. It may be 80 ° C. or lower, and may be 60 ° C. or lower.
　冷却工程において、ポリアミド溶液と混合する水の量は、限定されない。ポリアミド溶液と混合する時の水の量は、ポリアミド溶液に対して十分に多い量であることが、ポリアミド粒子が生成するようにポリアミドを析出させる観点から好ましい。たとえば、ポリアミド溶液と混合する水の量は、ポリアミド溶液の最終濃度が５質量％以下となる量であってよい。ここで「最終濃度」とは、全量のポリアミド溶液が水と混合したときの混合液に対するポリアミド溶液の質量である。 The amount of water mixed with the polyamide solution in the cooling step is not limited. It is preferable that the amount of water when mixed with the polyamide solution is sufficiently larger than that of the polyamide solution from the viewpoint of precipitating polyamide so that polyamide particles are formed. For example, the amount of water mixed with the polyamide solution may be such that the final concentration of the polyamide solution is 5% by mass or less. Here, the "final concentration" is the mass of the polyamide solution with respect to the mixture when the entire amount of the polyamide solution is mixed with water.
　冷却工程では、ポリアミドが当該混合物からポリアミド粒子を形成するように析出し、最終的に前述したポリアミド粒子が生成する。当該ポリアミド粒子が生成するメカニズムとしては、例えば、冷却工程において、前述の混合物を冷却する過程で、溶媒中に溶解していたポリアミドの分子が混合物中で規則的に配列し、これにより球状のポリアミド粒子が形成される、と考えられる。冷却工程の終点は、所期の性状を有するポリアミド粒子の生成によって決めることができる。冷却工程の終点は、たとえば、混合物の温度が室温（例えば２３℃）となった時点としてもよい。 In the cooling step, polyamide is precipitated from the mixture so as to form polyamide particles, and finally the above-mentioned polyamide particles are produced. As a mechanism for forming the polyamide particles, for example, in the cooling step, in the process of cooling the above-mentioned mixture, the polyamide molecules dissolved in the solvent are regularly arranged in the mixture, whereby spherical polyamide is formed. It is believed that particles are formed. The end point of the cooling step can be determined by the formation of polyamide particles having the desired properties. The end point of the cooling step may be, for example, a time when the temperature of the mixture reaches room temperature (for example, 23 ° C.).
　上記の冷却工程は、たとえば、溶解工程により生成したポリアミド溶液を水の循環流路に供給し、前述の混合物を当該循環流路に循環させつつ当該混合物の温度を制御することによって実施することが可能である。 The above cooling step can be carried out, for example, by supplying the polyamide solution produced in the dissolution step to the water circulation flow path and controlling the temperature of the mixture while circulating the above-mentioned mixture in the circulation flow path. It is possible.
　（その他の工程）
　本実施形態におけるポリアミド粒子の製造方法は、本実施形態の効果が得られる範囲において、前述した溶解工程および冷却工程以外の他の工程をさらに含んでいてもよい。当該他の工程の例には、冷却工程で生成したポリアミド粒子を分級する工程、が含まれる。 (Other processes)
The method for producing polyamide particles in the present embodiment may further include steps other than the above-mentioned melting step and cooling step as long as the effects of the present embodiment can be obtained. Examples of the other steps include a step of classifying the polyamide particles produced in the cooling step.
　（本実施形態に係るポリアミド粒子の特性）
　本実施形態のポリアミド粒子は、生分解性を有する。そのため、当該ポリアミド粒子は、環境中で分解されるため、生分解性を有さない樹脂製の粒子に比べて、環境に対する負荷を小さくすることができる。また、本実施形態のポリアミド粒子は、球状の形状を有するため、十分に高い滑り性を有する。 (Characteristics of polyamide particles according to this embodiment)
The polyamide particles of the present embodiment are biodegradable. Therefore, since the polyamide particles are decomposed in the environment, the load on the environment can be reduced as compared with the resin particles having no biodegradability. Further, since the polyamide particles of the present embodiment have a spherical shape, they have sufficiently high slipperiness.
　（本実施形態に係るポリアミド粒子の用途）
　本実施形態に係るポリアミド粒子は、粉体を含有する組成物で構成される、比較的微細な粒子を要する様々な製品に適用される。当該製品の例には、化粧料などの皮膚外用剤、塗料およびトナーが含まれる。 (Use of polyamide particles according to this embodiment)
The polyamide particles according to this embodiment are applied to various products that are composed of a composition containing powder and require relatively fine particles. Examples of such products include external preparations for skin such as cosmetics, paints and toners.
　上記の化粧料の例には、ファンデーション、口紅およびアイシャドウが含まれる。本実施形態に係るポリアミド粒子は、球状であるため、光を均一に散乱する性質を有する。したがって、当該ポリアミド粒子は、光沢調整剤として、例えば３質量％以上の含有量で化粧料に適用され得る。 Examples of the above cosmetics include foundations, lipsticks and eyeshadows. Since the polyamide particles according to this embodiment are spherical, they have a property of uniformly scattering light. Therefore, the polyamide particles can be applied to cosmetics as a gloss adjuster in a content of, for example, 3% by mass or more.
　上記の塗料の用途は限定されず、その例には、建築物用、自動車用、金属製品用および電気器具用が含まれる。本実施形態に係るポリアミド粒子は、光沢調整剤として、例えば１０質量％以上の含有量で塗料に適用され得る。 The uses of the above paints are not limited, and examples include those for buildings, automobiles, metal products and electrical appliances. The polyamide particles according to the present embodiment can be applied to a coating material as a gloss adjuster in a content of, for example, 10% by mass or more.
　上記のトナーにおいて、本実施形態に係るポリアミド粒子は、球状であるため、優れた流動性を有する。当該ポリアミド粒子は、顔料などの着色剤の担体として、例えば４０質量％以上の含有量でトナーに適用され得る。 In the above toner, the polyamide particles according to this embodiment have excellent fluidity because they are spherical. The polyamide particles can be applied to toner as a carrier for a colorant such as a pigment in a content of, for example, 40% by mass or more.
　〔まとめ〕
　以上の説明から明らかなように、本実施形態に係るポリアミド粒子は、ポリアミドで構成されている球状のポリアミド粒子である。そして、当該ポリアミドは、少なくとも１つのアルキレン基と少なくとも１つのアミド結合を構成する部位とを有する構造単位の繰り返しで構成される主鎖と、主鎖の端に位置する末端基とを有し、アルキレン基の炭素数は、１以上４以下である。そして、末端基の少なくとも１つは、炭素数８以上のアルキル基であり、かつ、ポリアミド粒子の平均粒子径が１μｍ以上１０μｍ以下である。この構成によれば、例えば、前述の特許文献２に記載の製造方法に対して十分に高い濃度のポリアミド溶液からの析出により生成される、数μｍ程度の粒径を有する球状のポリアミド粒子を提供することができる。 [Summary]
As is clear from the above description, the polyamide particles according to the present embodiment are spherical polyamide particles composed of polyamide. The polyamide has a main chain composed of repeating structural units having at least one alkylene group and a site constituting at least one amide bond, and a terminal group located at the end of the main chain. The alkylene group has 1 or more and 4 or less carbon atoms. At least one of the terminal groups is an alkyl group having 8 or more carbon atoms, and the average particle size of the polyamide particles is 1 μm or more and 10 μm or less. According to this configuration, for example, spherical polyamide particles having a particle size of about several μm, which are produced by precipitation from a polyamide solution having a sufficiently high concentration with respect to the production method described in Patent Document 2 described above, are provided. can do.
　本実施形態において、ポリアミド粒子の真球度は０．９以上であってもよい。この構成は、本実施形態におけるポリアミド粒子の球状粒子としての特性を高める観点からより一層効果的である。 In this embodiment, the sphericity of the polyamide particles may be 0.9 or more. This configuration is even more effective from the viewpoint of enhancing the characteristics of the polyamide particles as spherical particles in the present embodiment.
　本実施形態において、末端基のアルキル基は直鎖アルキル基であってもよい。この構成は、ポリアミドの析出によって造粒されるポリアミド粒子の形状を球状に制御する観点からより一層効果的である。 In the present embodiment, the alkyl group of the terminal group may be a linear alkyl group. This configuration is even more effective from the viewpoint of controlling the shape of the polyamide particles granulated by the precipitation of the polyamide in a spherical shape.
　本実施形態において、アルキレン基の炭素数は３であってもよい。この構成は、ポリアミド粒子の生分解性を高める観点からより一層効果的である。 In this embodiment, the alkylene group may have 3 carbon atoms. This configuration is even more effective from the viewpoint of enhancing the biodegradability of the polyamide particles.
　本実施形態に係るポリアミド粒子の製造方法は、ポリアミドで構成されている球状のポリアミド粒子の製造方法であって、製造されるポリアミド粒子の平均粒子径は、１μｍ以上１０μｍ以下である。また、当該製造方法は、ポリアミドと溶媒とを加熱してポリアミドを溶媒に溶解する溶解工程と、溶解工程により得られるポリアミド溶液を水と混合して冷却してポリアミドを析出させる冷却工程とを含む。ポリアミドには、少なくとも１つのアルキレン基と少なくとも１つのアミド結合を構成する部位とを有する構造単位の繰り返しで構成される主鎖と、主鎖の端に位置する末端基とを有し、アルキレン基の炭素数は、１以上４以下であり、末端基の少なくとも１つは、炭素数８以上のアルキル基であるポリアミドを用いる。また、溶媒にはアルコールを用いる。この構成によれば、例えば、前述の特許文献２に記載の製造方法に対して十分に高い濃度のポリアミド溶液からの析出により生成される、数μｍ程度の粒径を有する球状のポリアミド粒子を提供することができる。 The method for producing polyamide particles according to the present embodiment is a method for producing spherical polyamide particles composed of polyamide, and the average particle size of the produced polyamide particles is 1 μm or more and 10 μm or less. In addition, the production method includes a dissolution step of heating the polyamide and a solvent to dissolve the polyamide in the solvent, and a cooling step of mixing the polyamide solution obtained by the dissolution step with water and cooling to precipitate the polyamide. .. Polyamide has a main chain composed of repeating structural units having at least one alkylene group and a site constituting at least one amide bond, and an alkylene group having a terminal group located at the end of the main chain. The number of carbon atoms in the above is 1 or more and 4 or less, and at least one of the terminal groups is a polyamide having an alkyl group having 8 or more carbon atoms. Alcohol is used as the solvent. According to this configuration, for example, spherical polyamide particles having a particle size of about several μm, which are produced by precipitation from a polyamide solution having a sufficiently high concentration with respect to the production method described in Patent Document 2 described above, are provided. can do.
　本実施形態において、溶解工程における溶解温度はアルコール系溶媒中のアルコールの沸点以下であってもよい。この構成は、溶解の次工程における冷却速度を適切に制御する観点からより一層効果的である。 In the present embodiment, the dissolution temperature in the dissolution step may be equal to or lower than the boiling point of the alcohol in the alcohol solvent. This configuration is even more effective from the viewpoint of appropriately controlling the cooling rate in the next step of dissolution.
　本発明は上述した各実施形態に限定されず、請求項に示した範囲で種々の変更が可能である。異なる実施形態にそれぞれ開示された技術的手段を適宜組み合わせて得られる実施形態も本発明の技術的範囲に含まれる。 The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. The technical scope of the present invention also includes embodiments obtained by appropriately combining the technical means disclosed in the different embodiments.
　［ポリアミドの合成］
　（ポリアミドａの合成）
　ガラス製容器中に、原料モノマーとして２－ピロリドン（２ＰＤＮ）３００ｇを仕込み、塩基性触媒としてｔｅｒｔ－ブトキシカリウムを７.９ｇ、重合開始剤としてミリスチン酸イソプロピルを１４．３ｇ加え、撹拌した。反応の進行に伴い混合物が固化した段階で撹拌を停止し、反応開始から２４時間経過するまで静置した。なお、全ての操作は露点－４０℃以下に管理された常圧の空気雰囲気下、室温で実施した。 [Synthesis of polyamide]
(Synthesis of polyamide a)
In a glass container, 300 g of 2-pyrrolidone (2PDN) was charged as a raw material monomer, 7.9 g of tert-butoxypotassium was added as a basic catalyst, and 14.3 g of isopropyl myristate was added as a polymerization initiator, and the mixture was stirred. Stirring was stopped when the mixture solidified as the reaction proceeded, and the mixture was allowed to stand until 24 hours had passed from the start of the reaction. All operations were carried out at room temperature under a normal pressure air atmosphere controlled at a dew point of −40 ° C. or lower.
　こうして、下記式（２）で表されるポリアミドａを得た。ポリアミドａは、２ＰＤＮが開環してなる炭素数３のアルキレン基を有する構成単位を繰り返し有する主鎖と、その少なくとも一方の末端に結合する炭素数１３のアルキル基とを有するポリアミド４である。下記式（２）中、ｎは２以上の整数である。 Thus, the polyamide a represented by the following formula (2) was obtained. Polyamide a is a polyamide 4 having a main chain having a repeating structural unit having an alkylene group having 3 carbon atoms formed by ring-opening of 2PDN, and an alkyl group having 13 carbon atoms bonded to at least one end thereof. In the following equation (2), n is an integer of 2 or more.
Figure JPOXMLDOC01-appb-C000002
Figure JPOXMLDOC01-appb-C000002
　（ポリアミドｂの合成）
　ミリスチン酸イソプロピルに代えて１４．８ｇのアジポイルジピロリドンに重合開始剤を変更した以外は実施例１と同様にして、ポリアミドｂを製造した。ポリアミドｂは、ポリマーの中間部に炭素数４のメチレン基を有するポリアミド４である。 (Synthesis of polyamide b)
Polyamide b was produced in the same manner as in Example 1 except that the polymerization initiator was changed to 14.8 g of adipoyldipyrrolidone instead of isopropyl myristate. Polyamide b is a polyamide 4 having a methylene group having 4 carbon atoms in the middle portion of the polymer.
　（ポリアミドｃの合成）
　ミリスチン酸イソプロピルに代えて３．６ｇの酢酸イソプロピルに重合開始剤を変更した以外は実施例１と同様にして、ポリアミドｃを製造した。ポリアミドｃは、末端に炭素数１のアルキル基（メチル）を有するポリアミド４である。 (Synthesis of polyamide c)
Polyamide c was produced in the same manner as in Example 1 except that the polymerization initiator was changed to 3.6 g of isopropyl acetate instead of isopropyl myristate. Polyamide c is a polyamide 4 having an alkyl group (methyl) having 1 carbon atom at the terminal.
　（ポリアミドｄの合成）
　ミリスチン酸イソプロピルに代えて２．８ｇのヘキサン酸イソプロピルに重合開始剤を変更した以外は実施例１と同様にして、ポリアミドｄを製造した。ポリアミドｄは、末端に炭素数５のアルキル基（ペンチル）を有するポリアミド４である。 (Synthesis of polyamide d)
Polyamide d was produced in the same manner as in Example 1 except that the polymerization initiator was changed to 2.8 g of isopropyl myristate instead of isopropyl myristate. Polyamide d is a polyamide 4 having an alkyl group (pentyl) having 5 carbon atoms at the terminal.
　（分子量測定）
　ポリアミドａ～ｄのそれぞれについて、重量分子量（Ｍｗ）および分子量分布（Ｍｗ／Ｍｎ）を下記の方法によって測定した。 (Molecular weight measurement)
The weight molecular weight (Mw) and the molecular weight distribution (Mw / Mn) of each of the polyamides a to d were measured by the following methods.
　５ｍＭの濃度でトリフルオロ酢酸ナトリウムを溶かしたヘキサフルオロイソプロパノール（ＨＦＩＰ）溶液に１０ｍｇのポリアミドａ～ｄをそれぞれ溶解し、得られた溶液の体積を１０ｍＬに調整し、メンブレンフィルターで濾過して試料溶液を得た。１０μＬの試料溶液を以下に示すＧＰＣ測定装置に注入し、以下に示す測定条件で重量平均分子量Ｍｗおよび数平均分子量Ｍｎを測定し、Ｍｗおよび分子量分布Ｍｗ／Ｍｎを求めた。
　（ＧＰＣ測定装置および測定条件）
　　測定装置:ＳＨＯＤＥＸ　ＧＰＣ－１０４(昭和電工)
　　カラム:昭和電工　ＨＦＩＰ６０６Ｍ　２本(直列接続)
　　カラム温度:４０℃
　　検出器:ＲＩ
　　標準物質:ポリメチルメタクリレート（ＰＭＭＡ） 10 mg of polyamides a to d were dissolved in hexafluoroisopropanol (HFIP) solution in which sodium trifluoroacetate was dissolved at a concentration of 5 mM, the volume of the obtained solution was adjusted to 10 mL, and the sample solution was filtered through a membrane filter. Got A 10 μL sample solution was injected into the GPC measuring device shown below, and the weight average molecular weight Mw and the number average molecular weight Mn were measured under the measurement conditions shown below to determine Mw and the molecular weight distribution Mw / Mn.
(GPC measuring device and measuring conditions)
Measuring device: SHODEX GPC-104 (Showa Denko)
Column: Showa Denko HFIP606M 2 (series connection)
Column temperature: 40 ° C
Detector: RI
Standard substance: Polymethylmethacrylate (PMMA)
　ポリアミドａ～ｄのそれぞれについて、重合開始剤の種類および分子量の測定結果を表１に示す。 Table 1 shows the measurement results of the type and molecular weight of the polymerization initiator for each of the polyamides a to d.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　［造粒装置］
　次いで、ポリアミドａを用いるポリアミド粒子の製造について説明するが、それに先立って、本実施例で使用するポリアミド粒子を製造するための造粒装置を説明する。図１は、ポリアミド粒子の製造するための造粒装置の一例における構成を模式的に示す図である。 [Granulator]
Next, the production of the polyamide particles using the polyamide a will be described, but prior to that, the granulation apparatus for producing the polyamide particles used in this example will be described. FIG. 1 is a diagram schematically showing a configuration in an example of a granulator for producing polyamide particles.
　造粒装置１は、図１に示されるように、ポリアミドを溶媒に溶解させるための溶解槽１０、流体を収容するための冷却槽２０、および、冷却槽２０中の流体を冷却槽２０から送出するとともに冷却槽２０に戻す循環流路３０を有している。 As shown in FIG. 1, the granulator 1 sends out the melting tank 10 for dissolving the polyamide in the solvent, the cooling tank 20 for accommodating the fluid, and the fluid in the cooling tank 20 from the cooling tank 20. It also has a circulation flow path 30 that returns to the cooling tank 20.
　溶解槽１０は、撹拌機１１を有している。また、溶解槽１０は、溶解槽１０の内部の温度を調整するための不図示のジャケットを有している。冷却槽２０は、収容する流体の温度を調整するためのヒータ２１を有している。循環流路３０は、冷却槽２０中の流体を送液するためのポンプ３１を有している。なお、当該流体は、例えば水である。 The melting tank 10 has a stirrer 11. Further, the melting tank 10 has a jacket (not shown) for adjusting the temperature inside the melting tank 10. The cooling tank 20 has a heater 21 for adjusting the temperature of the fluid to be accommodated. The circulation flow path 30 has a pump 31 for sending the fluid in the cooling tank 20. The fluid is, for example, water.
　溶解槽１０の底部には排出管１２が接続されている。排出管１２は、排出管１２を開閉するためのバルブ１３を有している。また、排出管１２は、循環流路３０と接続されている。また、循環流路３０は、切り替え弁３２を有している。切り替え弁３２にはサンプリング管３３が接続されている。切り替え弁３２は、循環流路３０と、循環流路３０からサンプリング管３３への流路とを切り替え可能な弁である。 A discharge pipe 12 is connected to the bottom of the melting tank 10. The discharge pipe 12 has a valve 13 for opening and closing the discharge pipe 12. Further, the discharge pipe 12 is connected to the circulation flow path 30. Further, the circulation flow path 30 has a switching valve 32. A sampling tube 33 is connected to the switching valve 32. The switching valve 32 is a valve capable of switching between the circulation flow path 30 and the flow path from the circulation flow path 30 to the sampling pipe 33.
　このように、造粒装置１は、ポリアミドの溶液を、温度調整された流水中に投じ、当該流水中でポリアミドの液滴からポリアミドの粒子を製造することが可能な装置である。なお、冷却槽２０中の流体の量は、循環流路３０および冷却槽２０における流体の循環を実施するのに十分な量となっている。 As described above, the granulation device 1 is a device capable of producing polyamide particles from polyamide droplets by pouring a polyamide solution into temperature-controlled running water. The amount of fluid in the cooling tank 20 is sufficient to circulate the fluid in the circulation flow path 30 and the cooling tank 20.
　［実施例１］
　ポリアミドａの量が２０質量％となるように、ポリアミドａと溶媒としてのエチレグリコール（ＥＧ）とを溶解槽１０に収容する。次いで、撹拌機１１で撹拌しながら１８０℃でポリアミドａを溶解し、ポリアミドａのＥＧ溶液を生成した。「１８０℃」は、溶解槽１０の収容物（ポリアミドａおよびＥＧ）の温度であり、溶解温度に相当する。 [Example 1]
Ethylene glycol (EG) as a solvent is housed in the dissolution tank 10 so that the amount of the polyamide a is 20% by mass. Next, the polyamide a was dissolved at 180 ° C. while stirring with the stirrer 11 to generate an EG solution of the polyamide a. "180 ° C." is the temperature of the contents (polyamide a and EG) of the melting tank 10, and corresponds to the melting temperature.
　得られたポリアミドａのＥＧ溶液を、排出管１２を介して循環流路３０に供給し、１Ｌ／分の速度で循環流路３０を循環している８０℃の水と混合した。次いで、得られた混合液をサンプリング管３３から排出し、自然放冷によって当該混合液の温度を４０℃まで２時間かけて冷却した。次いで、混合液からポリアミドａの粒子をろ別し、水洗し、乾燥させた。こうして、ポリアミドａの粒子であるポリアミド粒子１を製造した。 The obtained EG solution of polyamide a was supplied to the circulation flow path 30 via the discharge pipe 12 and mixed with water at 80 ° C. circulating in the circulation flow path 30 at a speed of 1 L / min. Next, the obtained mixed liquid was discharged from the sampling tube 33, and the temperature of the mixed liquid was cooled to 40 ° C. over 2 hours by natural cooling. Then, the polyamide a particles were filtered off from the mixed solution, washed with water, and dried. In this way, the polyamide particles 1 which are the particles of the polyamide a were produced.
　［実施例２］
　内容量２０ｍＬの試験管にポリアミドａを３ｇ計量し、次いで７ｇのＥＧを加えた。次いで、オイルバス中１７０℃でポリアミドａを溶解し、ポリアミドａの溶液のＥＧ溶液を生成した。得られたポリアミドａのＥＧ溶液を、８０℃の水１００ｍＬに攪拌しながら加えたのち、放冷することでポリアミドａ粒子が含まれる混合液を得た。次いで、混合液からポリアミドａの粒子をろ別し、水洗し、乾燥させた。こうして、ポリアミド粒子２を製造した。 [Example 2]
3 g of polyamide a was weighed in a test tube having a content of 20 mL, and then 7 g of EG was added. Next, the polyamide a was dissolved in an oil bath at 170 ° C. to generate an EG solution of the solution of the polyamide a. The obtained EG solution of polyamide a was added to 100 mL of water at 80 ° C. with stirring, and then allowed to cool to obtain a mixed solution containing polyamide a particles. Then, the polyamide a particles were filtered off from the mixed solution, washed with water, and dried. In this way, the polyamide particles 2 were produced.
　［実施例３］
　溶媒をプロピレングリコール（ＰＧ）に変更し、溶解槽１０におけるポリアミドａのＰＧ溶液の温度を１９０℃に変更した以外はポリアミド粒子１の製造と同様にして、ポリアミド粒子３を製造した。 [Example 3]
Polyamide particles 3 were produced in the same manner as in the production of polyamide particles 1 except that the solvent was changed to propylene glycol (PG) and the temperature of the PG solution of the polyamide a in the dissolution tank 10 was changed to 190 ° C.
　［実施例４］
　溶媒をグリセリン（ＧＬ）に変更し、溶解温度を１８０℃に変更した以外はポリアミド粒子２の製造と同様にして、ポリアミド粒子４を製造した。 [Example 4]
Polyamide particles 4 were produced in the same manner as in polyamide particles 2 except that the solvent was changed to glycerin (GL) and the dissolution temperature was changed to 180 ° C.
　［比較例１、２］
　ポリアミドａに代えてポリアミドｂを用い、溶解槽１０におけるポリアミドｂの溶媒を水に変更し、ポリアミドｂの水溶液の濃度を１質量％に変更し、１５０℃で３０分間保持してポリマーを溶解させたのち、攪拌を停止して４０℃以下まで風冷し粒子を析出させ、ポリアミド粒子５を製造した。また、ポリアミドｂの水溶液の濃度を５質量％に変更した以外はポリアミド粒子５の製造と同様にして、ポリアミド粒子６を製造した。 [Comparative Examples 1 and 2]
Using polyamide b instead of polyamide a, the solvent of polyamide b in the dissolution tank 10 was changed to water, the concentration of the aqueous solution of polyamide b was changed to 1% by mass, and the polymer was dissolved at 150 ° C. for 30 minutes. After that, stirring was stopped and the mixture was air-cooled to 40 ° C. or lower to precipitate particles to produce polyamide particles 5. Further, the polyamide particles 6 were produced in the same manner as the polyamide particles 5 except that the concentration of the aqueous solution of the polyamide b was changed to 5% by mass.
　［比較例３、４］
　ポリアミドａに代えてポリアミドｃを用いる以外はポリアミド粒子２の製造と同様にして、ポリアミド粒子７を製造した。また、ポリアミドａに代えてポリアミドｄを用いる以外はポリアミド粒子２の製造と同様にして、ポリアミド粒子８を製造した。 [Comparative Examples 3 and 4]
Polyamide particles 7 were produced in the same manner as in the production of polyamide particles 2 except that polyamide c was used instead of polyamide a. Further, the polyamide particles 8 were produced in the same manner as in the production of the polyamide particles 2 except that the polyamide d was used instead of the polyamide a.
　［ポリアミド粒子の性状］
　（１）粒子形状
　ポリアミド粒子１～８のそれぞれについて、走査型電子顕微鏡（日本電子社製、ＮｅｏＳｃｏｐｅ　ＪＣＭ－５０００）を用いて、得られた粒子を観察し、その走査型顕微鏡写真を撮影した。写真に撮影されたポリアミド粒子の形状を複数の技術者が観察し、球状か、あるいは非球状かを判定した。 [Characteristics of polyamide particles]
(1) Particle Shape For each of the polyamide particles 1 to 8, the obtained particles were observed using a scanning electron microscope (NeoScop JCM-5000 manufactured by JEOL Ltd.), and a scanning photomicrograph was taken. A plurality of engineers observed the shape of the polyamide particles photographed and determined whether they were spherical or non-spherical.
　（２）真球度
　ポリアミド粒子１～８のそれぞれについて、走査型電子顕微鏡写真中から３０個のポリアミド粒子を任意に選択し、選択したポリアミド粒子のそれぞれにおける短径および長径を測定した。そして、下記式にしたがって、ポリアミド粒子の真球度を求めた。下記式（２）中、ｎは３０である。 (2) Sphericality For each of the polyamide particles 1 to 8, 30 polyamide particles were arbitrarily selected from the scanning electron micrographs, and the minor axis and the major axis of each of the selected polyamide particles were measured. Then, the sphericity of the polyamide particles was determined according to the following formula. In the following equation (2), n is 30.
Figure JPOXMLDOC01-appb-M000004
Figure JPOXMLDOC01-appb-M000004
　（３）平均粒子径
　ポリアミド粒子１～８のそれぞれについて、レーザー回折型粒子径測定装置「マイクロトラック・ベル社製、マイクロトラックＭＴ３３００ＥＸII－ＳＤＣ」を用い、体積平均粒子径を測定し粒子径とした。 (3) Average particle size For each of the polyamide particles 1 to 8, the volume average particle size was measured using a laser diffraction type particle size measuring device "Microtrack MT3300EXII-SDC manufactured by Microtrac Bell" and used as the particle size. ..
　ポリアミド粒子１～８のそれぞれについて、造粒条件および粒子の性状を表２に示す。 Table 2 shows the granulation conditions and particle properties for each of the polyamide particles 1 to 8.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　［考察］
　表２から明らかなように、ポリアミド粒子１～４の形状はいずれも球状であり、ポリアミド粒子１～４の平均粒子径はいずれも数μｍ程度である。また、ポリアミド粒子１～４の造粒時におけるポリアミド溶液の濃度は、２０質量％または３０質量％と高い濃度である。よって、実施例１～４によれば、造粒時における溶媒にアルコールを用い、炭素数１３の直鎖アルキル基を末端基として有するポリアミド４（ポリアミドａ）を用いることにより、１０μｍ以下の粒径を有する球状のポリアミド粒子を高い生産効率で提供することができることがわかる。 [Discussion]
As is clear from Table 2, the shapes of the polyamide particles 1 to 4 are all spherical, and the average particle diameter of the polyamide particles 1 to 4 is about several μm. Further, the concentration of the polyamide solution at the time of granulating the polyamide particles 1 to 4 is as high as 20% by mass or 30% by mass. Therefore, according to Examples 1 to 4, by using alcohol as a solvent at the time of granulation and using polyamide 4 (polyamide a) having a linear alkyl group having 13 carbon atoms as a terminal group, the particle size is 10 μm or less. It can be seen that the spherical polyamide particles having a high production efficiency can be provided.
　なお、上記のような造粒によって小径かつ球状のポリアミド粒子が生成する理由は、ポリアミド溶液からポリアミドが析出する際に、たとえば、末端基が粒子の中心側となるなどのようにポリアミドの分子が規則的に配置したため、と考えられる。 The reason why the small-diameter and spherical polyamide particles are generated by the above-mentioned granulation is that when the polyamide is precipitated from the polyamide solution, the polyamide molecules are formed, for example, the terminal group is on the center side of the particles. It is probable that it was arranged regularly.
　これに対して、ポリアミド粒子５、６は、いずれも球状であるが、その平均粒子径は、１０μｍを超えている。また、造粒時における溶媒が水であるため、造粒時におけるポリアミド溶液の濃度が数質量％と低い。これは、ポリアミドｂの水に対する溶解性が低く、また特定の末端基を有さないために析出時におけるポリアミドの配列が不規則になったため、と考えられる。 On the other hand, the polyamide particles 5 and 6 are all spherical, but their average particle size exceeds 10 μm. Further, since the solvent at the time of granulation is water, the concentration of the polyamide solution at the time of granulation is as low as several mass%. It is considered that this is because the solubility of the polyamide b in water is low and the arrangement of the polyamide at the time of precipitation becomes irregular because it does not have a specific terminal group.
　また、ポリアミド粒子７、８は、いずれも非球状であり、その平均粒子径は４０μｍを超えている。これは、ポリアミドの末端基のアルキル基が十分数の炭素原子を有さないために、析出時におけるポリアミドの配列が不規則になったため、と考えられる。 Further, the polyamide particles 7 and 8 are both non-spherical, and their average particle diameter exceeds 40 μm. It is considered that this is because the alkyl group of the terminal group of the polyamide does not have a sufficient number of carbon atoms, so that the arrangement of the polyamide at the time of precipitation becomes irregular.
　［ポリアミド粒子の分解率の評価］
　実施例１で得られたポリアミド粒子、比較例１で得られたポリアミド粒子、およびセルロースをそれぞれ試験容器に入れた。この時、微生物による呼吸などを含めたブランク測定を行うため、評価サンプルを入れていない空試験も準備した。 [Evaluation of decomposition rate of polyamide particles]
The polyamide particles obtained in Example 1, the polyamide particles obtained in Comparative Example 1, and cellulose were placed in test containers, respectively. At this time, in order to perform blank measurement including respiration by microorganisms, a blank test without an evaluation sample was also prepared.
　そして、ＪＩＳ　Ｋ　６９５０の生分解性試験（活性汚泥分解試験）によって、分解率を評価した。評価結果を表３に示す。 Then, the decomposition rate was evaluated by the biodegradability test (activated sludge decomposition test) of JIS K 6950. The evaluation results are shown in Table 3.
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
　表３において、［１］および［２］は実施例１で得られたポリアミド粒子の評価結果を示す。［３］および［４］は、セルロースの評価結果を示す。［５］および［６］は、［１］～［４］と同時に実施した空試験の評価結果を示す。［７］および［８］は、比較例１で得られたポリアミド粒子の評価結果を示す。［９］および［１０］は、［７］および［８］と同時に実施した空試験の評価結果を示す。 In Table 3, [1] and [2] show the evaluation results of the polyamide particles obtained in Example 1. [3] and [4] show the evaluation results of cellulose. [5] and [6] indicate the evaluation results of the blank test conducted at the same time as [1] to [4]. [7] and [8] show the evaluation results of the polyamide particles obtained in Comparative Example 1. [9] and [10] indicate the evaluation results of the blank test conducted at the same time as [7] and [8].
　表３中のＢＯＤの単位はｍｇである。また、分解率の単位は％である。表３の分解率は上記式（３）から算出した。［５］および［６］の平均値または［９］および［１０］の平均値を試験開始ｎ日目の空試験のＢＯＤとした。 The unit of BOD in Table 3 is mg. The unit of decomposition rate is%. The decomposition rate in Table 3 was calculated from the above formula (3). The average value of [5] and [6] or the average value of [9] and [10] was used as the BOD of the blank test on the nth day after the start of the test.
　表３に示すように、試験開始７日目の実施例１で得られたポリアミド粒子の分解率は１０％未満であった。一方、試験開始１４日目の実施例１で得られたポリアミド粒子の分解率は３０％前後となり、試験開始２８日目には、分解率が８５％以上となった。 As shown in Table 3, the decomposition rate of the polyamide particles obtained in Example 1 on the 7th day after the start of the test was less than 10%. On the other hand, the decomposition rate of the polyamide particles obtained in Example 1 on the 14th day after the start of the test was around 30%, and the decomposition rate was 85% or more on the 28th day after the start of the test.
　表３に示すように、比較例１のポリアミド粒子の分解率は、試験開始約１４日目までは経過日数に比例して上昇していったが、１４日目以降は分解率の上昇幅が小さくなった。 As shown in Table 3, the decomposition rate of the polyamide particles of Comparative Example 1 increased in proportion to the number of days elapsed until about 14 days after the start of the test, but after the 14th day, the rate of increase in the decomposition rate increased. It became smaller.
　本発明は、比較的小径かつ球状のポリアミド４の粒子を提供することができる。本発明におけるポリアミド粒子は、比較的小径で球状な樹脂粒子を要する組成物に、機能性を有するとともに環境負荷の小さな材料として適用することができる。 The present invention can provide particles of polyamide 4 having a relatively small diameter and a spherical shape. The polyamide particles in the present invention can be applied to a composition requiring relatively small diameter and spherical resin particles as a material having functionality and a small environmental load.
　１　造粒装置
　１０　溶解槽
　１１　撹拌機
　１２　排出管
　１３　バルブ
　２０　冷却槽
　２１　ヒータ
　３０　循環流路
　３１　ポンプ
　３２　切り替え弁
　３３　サンプリング管 1 Granulation device 10 Melting tank 11 Stirrer 12 Discharge pipe 13 Valve 20 Cooling tank 21 Heater 30 Circulation flow path 31 Pump 32 Switching valve 33 Sampling pipe

Claims (6)

  1. 　ポリアミドで構成されている球状のポリアミド粒子であって、
    　前記ポリアミドは、少なくとも１つのアルキレン基と少なくとも１つのアミド結合を構成する部位とを有する構造単位の繰り返しで構成される主鎖と、前記主鎖の端に位置する末端基とを有し、
    　前記アルキレン基の炭素数は、１以上４以下であり、
    　前記末端基の少なくとも１つは、炭素数８以上のアルキル基であり、かつ
    　平均粒子径が１μｍ以上１０μｍ以下である、
    ポリアミド粒子。     Spherical polyamide particles composed of polyamide
    The polyamide has a main chain composed of repeating structural units having at least one alkylene group and a site constituting at least one amide bond, and a terminal group located at the end of the main chain.
    The alkylene group has 1 or more and 4 or less carbon atoms.
    At least one of the terminal groups is an alkyl group having 8 or more carbon atoms and has an average particle size of 1 μm or more and 10 μm or less.
    Polyamide particles.
  2. 　真球度が０．９以上である、請求項１に記載のポリアミド粒子。 The polyamide particle according to claim 1, which has a sphericity of 0.9 or more.
  3. 　前記アルキル基は、直鎖アルキル基である、請求項１または２に記載のポリアミド粒子。 The polyamide particle according to claim 1 or 2, wherein the alkyl group is a linear alkyl group.
  4. 　前記アルキレン基の炭素数は３である、請求項１～３のいずれか一項に記載のポリアミド粒子。 The polyamide particle according to any one of claims 1 to 3, wherein the alkylene group has 3 carbon atoms.
  5. 　ポリアミドで構成されている球状のポリアミド粒子の製造方法であって、
    　製造されるポリアミド粒子の平均粒子径は、１μｍ以上１０μｍ以下であり、
    　ポリアミドと溶媒とを加熱して前記ポリアミドを前記溶媒に溶解する溶解工程と、
    　前記溶解工程により得られるポリアミド溶液を水と混合して冷却してポリアミドを析出させる冷却工程と、を含み、
    　前記ポリアミドには、
    　　少なくとも１つのアルキレン基と少なくとも１つのアミド結合を構成する部位とを有する構造単位の繰り返しで構成される主鎖と、前記主鎖の端に位置する末端基とを有し、
    　　前記アルキレン基の炭素数は、１以上４以下であり、
    　　前記末端基の少なくとも１つは、炭素数８以上のアルキル基であるポリアミドを用い、
    　前記溶媒にはアルコール系溶媒を用いる、
    ポリアミド粒子の製造方法。     A method for producing spherical polyamide particles composed of polyamide.
    The average particle size of the produced polyamide particles is 1 μm or more and 10 μm or less.
    A dissolution step of heating the polyamide and a solvent to dissolve the polyamide in the solvent, and
    A cooling step of mixing the polyamide solution obtained by the dissolution step with water and cooling to precipitate the polyamide is included.
    The polyamide is
    It has a main chain composed of repeating structural units having at least one alkylene group and a site constituting at least one amide bond, and a terminal group located at the end of the main chain.
    The alkylene group has 1 or more and 4 or less carbon atoms.
    For at least one of the terminal groups, polyamide which is an alkyl group having 8 or more carbon atoms is used.
    An alcohol solvent is used as the solvent.
    Method for producing polyamide particles.
  6. 　前記溶解工程における溶解温度が前記アルコール系溶媒中のアルコールの沸点以下である、請求項５に記載のポリアミド粒子の製造方法。 The method for producing polyamide particles according to claim 5, wherein the dissolution temperature in the dissolution step is equal to or lower than the boiling point of the alcohol in the alcohol solvent.
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