US 9,617,395 B2  9  10  fully saponified or a partially saponified poly(vinyl alcohol› ethylene) copolymer), cellulose derivatives (such as car› boxymethyl cellulose, hydroxyalkyl cellulose (hydroxyethyl  cellulose, hydroxypropyl cellulose, ethylhydroxyethyl cel› lulose), methyl cellulose, ethyl cellulose, carboxymethyl- ethyl cellulose, carboxymethyl cellulose, carboxymethyl  cellulose sodium, cellulose ester, etc.), polyalkylene glycol,  sucrose fatty acid ester, poly (oxyethylene alkyl phenyl  ether), poly (oxyalkyl ether), polyvinyl pyrrolidone, water› soluble nylon, polyacrylic acid, and polymethacrylic acid.  More preferably they are polyvinyl alcohol groups (such as  a fully saponified or a partially saponified poly(vinyl alco› hol), orpoly(vinyl alcohol-ethylene) copolymer groups such  as a fully saponified or a partially saponified poly(vinyl  alcohol-ethylene) copolymer), cellulose derivatives (such as  carboxymethyl cellulose, hydroxyalkyl cellulose (hydroxy› ethyl cellulose, hydroxypropyl cellulose, ethylhydroxyethyl  cellulose), methyl cellulose, ethyl cellulose, carboxymethy› lethyl cellulose, carboxymethyl cellulose, carboxymethyl  cellulose sodium, cellulose ester, etc.), polyalkylene glycol,  polyvinyl pyrrolidone, water-soluble nylon, and polyacrylic  acid. Particularly preferably they are polyvinyl alcohol  groups such as a fully saponified or a partially saponified  poly(vinyl  alcohol),  hydroxyalkyl  cellulose  such  as  hydroxyethyl cellulose, hydroxypropyl cellulose, etc., poly› alkylene glycol, polyvinyl pyrrolidone, water-soluble nylon,  and polyacrylic acid.  As the polymer Bother than polyamide 1010 resin in the  present invention, remarkably preferably polyvinyl alcohol  groups are used. In more detail, the polyvinyl alcohol group  means a polymer having a structure represented the follow› ing general formula (1) in its molecule.  Although it may be a poly(vinyl alcohol) (a fully saponi› fied or a partially saponified poly(vinyl alcohol). There is  also a case where it is called merely as a polyvinyl alcohol.)  and a poly(vinyl alcohol-ethylene) (a fully saponified or a  partially saponified poly(vinyl alcohol-ethylene)), a polyvi› nyl alcohol is preferred from the viewpoint of solubility.  The molecular weight of the polymer B other than poly› amide 1010 resin is preferably 1,000 to 100,000,000 as  weight average molecular weight, more preferably 1,000 to  10,000,000, further preferably 5,000 to 1,000,000, particu› larly preferably 10,000 to 500,000, and most preferably  10,000 to 100,000.  The weight average molecular weight referred to here is  the weight average molecular weight value measured by gel  permeation chromatography (GPC) using water as solvent  and converted in terms of polyethylene glycol.  Dimethyl formamide is used if water does not serve for  the measurement, and tetrahydrofuran is used if measure› ment is still impossible. If it is still further impossible to  make measurements, then hexafluoroisopropanol is used.  With respect to the polyvinyl alcohol group, it is general  to produce polyvinyl alcohol by polymerizing vinyl acetate  as a raw material and thereafter hydrolyzing it under an  alkali condition, and therein usually sodium acetate partially  remains as impurities, which is contained around 0.2 mass%  even in a product on the market.  As the acid compounds, exemplified are aliphatic carbox- ylic acids such as formic acid, acetic acid, valeric acid,  butyric acid, hexanoic acid, heptanoic acid, octanoic acid,  acrylic acid, methacrylic acid, crotonic acid, oxalic acid,  malonic acid, fumaric acid, maleic acid, glutaric acid, adipic  acid, sebacic acid, pyruvic acid, succinic acid and poly- acrylic acid, carboxylic acids having a hydroxyl group such  as lactic acid, glycolic acid, L-ascorbic acid, erythorbic acid,  malic acid, shikimic acid, citric acid, hydrosuccinic acid and  tartaric acid, aromatic carboxylic acids such as benzoic acid,  2-fluorobenzoic acid and regioisomers thereof, 2-chloroben- zoic acid and regioisomers thereof, 2-bromobenzoic acid  and regioisomers thereof, 2-nitro benzoic acid and regioi› somers thereof, 2-toluic acid and regioisomers thereof, phe› noxyacetic acid, cinnamic acid, phenyl malonic acid,  phthalic acid, terephthalic acid and salicylic acid, amino  acids such as glycine, alanine, valine, leucine, isoleucine,  serine, threonine, praline, lysin, aspartic acid, glutaminic  acid, cysteine, methionine, phenylalanine, tyrosine, histi› dine, asparagine, glutamine, arginine, tryptophan, omithine  and sarcosine, organic sulfonic acids such as methane sul- fonic acid, benzene sulfonic acid, p-toluene sulfonic acid  and regioisomers thereof, p-hydroxybenzene sulfonic acid  and regioisomers thereof, organic phosphorus acids such as  phenyl phosphonic acid, diphenyl phosphinic acid, diphenyl  phosphate and 1-naphthyl phosphate, salts consisting of a  strong acid and a weak base such as magnesium sulfate,  magnesium chloride, ammonium chloride and anm10nium  sulfate, and inorganic acids such as hydrochloric acid,  Further, as another method of suppressing the influence  due to sodium acetate when an emulsion is formed, a method  for adding an acid compound to the system of forming the  emulsion can be exemplified. By this, a condition where  sodium acetate substantially is not contained can be realized.  To obtain polyvinyl alcohol group in little content of  sodium acetate, for example, exemplified are a method for  washing it by an organic solvent such as methanol or  ethanol, a reprecipitation method for producing it by pre› cipitating it in a poor solvent for polyvinyl alcohol group  after dissolving it in water and the like, a ultrafiltration  method, a method for removing the sodium acetate by ion  exchange resin, ion exchange carrier and the like.  We found that the above-described sodium acetate con› tained in the polyvinyl alcohol influences to some extent,  and when an emulsion is formed by dissolving and mixing  it into polyamide 1010 resin and an organic solvent, if the  temperature is 100° C. or higher, the microparticles are  colored, or the recycling property deteriorates by deteriora- tion of the polyvinyl alcohol.  Namely, to stabilize the polyvinyl alcohol group which is  polymer B other than polyamide 1010 resin even under a  condition for producing microparticles at 100°  C. or higher,  it is preferred to reduce the amount of sodium acetate existed  in the system for forming an emulsion. As a method therefor,  it is preferred to use polyvinyl alcohol with a small content  of sodium acetate as the polyvinyl alcohol group.  In this case, the amount of sodium acetate in the used  polyvinyl alcohol relative to 100 parts by mass of polyvinyl  alcohol is 0.1 part by mass or less, preferably 0.05 part by  mass or less, more preferably 0.01 part by mass or less.  By controlling it in this range, even if polyamide 1010  resin is made into microparticles under a high-temperature  condition, it can be suppressed that the polyvinyl alcohol  group is modified originating from decomposition or cross› linking, and making it into microparticles under a high› temperature condition can be stabilized. Further, a prefer- able lower limit thereof is 0 part by mass.  (1)  N  OH 