US 9,617,395 B2  24  23  and the indenter, it was calculated from Ei, which was an  elasticity modulus of particles, using the following equa› tions 3 and 4.  (10) Quantitative Analysis of Sodium Acetate Contained in  Polyvinyl Alcohol Group:  It was determined by sodium acetate dissolution and  titration method described in JIS "method for testing poly- vinyl alcohol" (10726 (1994)).  50 g of polyvinyl alcohol ( supplied by Nippon Synthetic  Chemical Industry Co., Ltd., G-type "Gohsenol" (registered  trademark) GM-14, weight average molecular weight:  29,000, SP value: 32.8 (J/cm 3 ) 112 ,  content of sodium acetate:  0.23 mass % ) and 500 ml of methanol were added in a 1 L  round bottom flask, and stirred under a room temperature  condition for one hour. Thereafter, the solution was filtrated  by suction filtration (filter paper  SA,  90 mmcp ). Following  thereto, the same operation was repeated two times, totally  three times, and then, by drying it at 80°  C. for 10 hours,  polyvinyl alcohol little with content of sodium acetate was  obtained. The quantified sodium acetate in the obtained  polyvinyl alcohol was 0.05 mass %.  24.5 g of polyamide 1010 (weight average molecular  weight: 22,500, "Hiprolon" (registered trademark) -200,  supplied by Hipro Polymers Co. Ltd.), 273.5 g ofN-methyl- 2-pyrrolidone as the organic solvent and 42 g of polyvinyl  alcohol little with content of sodium acetate prepared in  Reference Example 1 as the polymer B other than polyamide  1010 resin (weight average molecular weight: 29,000, SP  value: 32.8 (J/cm 3 ) 112 )  were added into a 1,000 ml pressure  resistant glass autoclave (supplied by Taiatsu Techno Cor› poration, Hyper Glaster, TEM-Vl 000N), after replaced with  nitrogen of 99 volume % or more, heated up to 180°  C., and  stirred for 2 hours until the polymers were dissolved. At that  time, the concentration of oxygen is 1 % or less theoretically.  Thereafter, 350 g of ion exchange water was dropped as the  poor solvent at a speed of 2.91 g/min. through a feeding  pump. At the time added with the ion exchange water of  about 110 g, the system changed to white color. After the  whole amount of water was completely poured, the tem- perature was lowered while being stirred, the obtained  suspension was filtered, re-slurry washing was performed by  adding 700 g of ion exchange water, and the filtrated  substances were vacuum dried at 80°  C. for 10 hours to  obtain 24.0 g of white solid material. When the obtained  powder were observed by a scanning electron microscope,  they were polyamide 1010 polymer particles having a true  sphere-like particle shape (FIG. 7), an average particle  diameter of 7.5 µm, and a particle diameter distribution  index of 1.12. When wide angle X-ray diffraction spectrum  was determined for the polyamide 1010 polymer particles,  as diffraction angle 28, peaks were exhibited at positions of  20 degrees and 24 degrees (FIG.  1).  Where, the melting  point of the polyamide 1010 used in this Example was 207°  C., the heat of fusion was 29.0  Jig,  and the cooling crystal- lization temperature was 144°  C. The SP value determined  by the calculation method was 22.47 (J/cm 3 ) 112 .  Further, the  estimated value of the interfacial tension of this system was  2 mN/m or less. The solubility (room temperature) of  polyamide relative to water, which was the poor solvent, was  0.1 mass % or less.  The estimation results of the properties of the obtained  polyamide 1010 polymer particles were shown in Table 1.  Using a spectrophotometry "SE-2000" supplied by Nip› pon Denshoku Industries Co., Ltd., the lightness L was  measured. As the standard, a standard white board attached  to the equipment (y=95.99, x=94.04, z=113.10) was used.  Using the obtained particles, a sensory test due to 8 panels  was carried out. The estimation method was carried out by  a sensory test with respect to three items of"foreign material  feeling", "softness" and "smoothness" wherein a small  amount of particles (about 0.02 g) were put on the back of  a hand, and the particles were scrubbed by three fingers of  another hand. With respect to the respective items, the  average points of eight persons when the following rank  points were allotted were ranked in accordance with the  following standards.  "Foreign Material Feeling"  "Softness"  "Smoothness"  <Determination Standards>  (9) Measurement of Lightness:  Particles were softly filled into a graduated cylinder of 10  ml, the weight of the particles in the graduated cylinder was  measured, and the mass per unit volume was determined as  the bulk density.  (8) Touch Feeling:  The elasticity modulus was calculated using a deforma› tion range of 1-5% of a particle diameter that was an elastic  deformation range.  (7) Bulk Density:  E$_{1}$ :  elasticity modulus of particles (GPa)  B$_{3}$ :  elasticity modulus of the machine stage (200 GPa)  v$_{1}$ :  Poisson’s ratio of particles (set at 0.4)  v$_{2}$ :  Poisson’s ratio of the machine indenter (0.07)  v$_{3}$ :  Poisson’s ratio of the machine stage (0.3)  R$_{1 }$ radius of particle (µm)  P: load (mN)  B$_{2}$ :  elasticity modulus of the machine indenter (1140  GPa)  Ii:  compressive displacement magnitude at the time of  particle compression (µm)  E*: complex elasticity modulus with an object to be  determined (GPa)  3 point: There is no foreign material feeling.  2 point: There is slightly foreign material feeling.  1 point: There is foreign material feeling.  3 point: soft feeling  2 point: slightly soft feeling  1 point: hard feeling  3 point: smooth  2 point: slightly smooth  1 point: There is a catching feeling.  9.0-6.5 point: o  6.4-4.5 point:  ll  4.4-3.0 point: x  Reference Example 1 Washing 1 of Sodium Acetate  in Polyvinyl Alcohol Group  Example 1 Method for Producing Polyamide 1010  Polymer Particles  r  2  213  _ ( 1 - vf  1 - v~  )’ ( 1 - vf  1 - vf  )’  F- --+-- + --+-- E1  E2  E1  £3  [4]  [ 3 ] 