JP2021161399A - Polyvinyl acetal resin particle - Google Patents
Polyvinyl acetal resin particle Download PDFInfo
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- JP2021161399A JP2021161399A JP2021052570A JP2021052570A JP2021161399A JP 2021161399 A JP2021161399 A JP 2021161399A JP 2021052570 A JP2021052570 A JP 2021052570A JP 2021052570 A JP2021052570 A JP 2021052570A JP 2021161399 A JP2021161399 A JP 2021161399A
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- acetal resin
- polyvinyl acetal
- polyvinyl alcohol
- resin particles
- polyvinyl
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- 239000002245 particle Substances 0.000 title claims abstract description 131
- DHKHKXVYLBGOIT-UHFFFAOYSA-N 1,1-Diethoxyethane Chemical compound CCOC(C)OCC DHKHKXVYLBGOIT-UHFFFAOYSA-N 0.000 title claims abstract description 107
- 229920002554 vinyl polymer Polymers 0.000 title claims abstract description 102
- 239000011354 acetal resin Substances 0.000 title claims abstract description 101
- 229920006324 polyoxymethylene Polymers 0.000 title claims abstract description 101
- 239000011148 porous material Substances 0.000 claims abstract description 34
- 238000006116 polymerization reaction Methods 0.000 claims description 28
- 239000011800 void material Substances 0.000 claims description 27
- 238000009826 distribution Methods 0.000 claims description 13
- 239000003960 organic solvent Substances 0.000 abstract description 33
- 239000011347 resin Substances 0.000 abstract description 32
- 229920005989 resin Polymers 0.000 abstract description 32
- 238000004090 dissolution Methods 0.000 abstract description 25
- 239000002904 solvent Substances 0.000 abstract description 15
- 239000004372 Polyvinyl alcohol Substances 0.000 description 94
- 229920002451 polyvinyl alcohol Polymers 0.000 description 94
- 238000003756 stirring Methods 0.000 description 31
- 238000007127 saponification reaction Methods 0.000 description 25
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 24
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 21
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 19
- 238000000034 method Methods 0.000 description 16
- 230000000052 comparative effect Effects 0.000 description 15
- ZTQSAGDEMFDKMZ-UHFFFAOYSA-N Butyraldehyde Chemical group CCCC=O ZTQSAGDEMFDKMZ-UHFFFAOYSA-N 0.000 description 10
- 125000004036 acetal group Chemical group 0.000 description 7
- 238000006359 acetalization reaction Methods 0.000 description 7
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 7
- 238000005469 granulation Methods 0.000 description 6
- 230000003179 granulation Effects 0.000 description 6
- 238000005470 impregnation Methods 0.000 description 6
- 239000012046 mixed solvent Substances 0.000 description 6
- 150000001241 acetals Chemical class 0.000 description 5
- 125000002777 acetyl group Chemical group [H]C([H])([H])C(*)=O 0.000 description 5
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 5
- 229910052753 mercury Inorganic materials 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- IKHGUXGNUITLKF-UHFFFAOYSA-N Acetaldehyde Chemical compound CC=O IKHGUXGNUITLKF-UHFFFAOYSA-N 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- 150000001299 aldehydes Chemical class 0.000 description 4
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 3
- 239000001431 2-methylbenzaldehyde Substances 0.000 description 3
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000003377 acid catalyst Substances 0.000 description 3
- 230000001186 cumulative effect Effects 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- IAVREABSGIHHMO-UHFFFAOYSA-N 3-hydroxybenzaldehyde Chemical compound OC1=CC=CC(C=O)=C1 IAVREABSGIHHMO-UHFFFAOYSA-N 0.000 description 2
- YGCZTXZTJXYWCO-UHFFFAOYSA-N 3-phenylpropanal Chemical compound O=CCCC1=CC=CC=C1 YGCZTXZTJXYWCO-UHFFFAOYSA-N 0.000 description 2
- RGHHSNMVTDWUBI-UHFFFAOYSA-N 4-hydroxybenzaldehyde Chemical compound OC1=CC=C(C=O)C=C1 RGHHSNMVTDWUBI-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 2
- NBBJYMSMWIIQGU-UHFFFAOYSA-N Propionic aldehyde Chemical compound CCC=O NBBJYMSMWIIQGU-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- HUMNYLRZRPPJDN-UHFFFAOYSA-N benzaldehyde Chemical compound O=CC1=CC=CC=C1 HUMNYLRZRPPJDN-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- HYBBIBNJHNGZAN-UHFFFAOYSA-N furfural Chemical compound O=CC1=CC=CO1 HYBBIBNJHNGZAN-UHFFFAOYSA-N 0.000 description 2
- FXHGMKSSBGDXIY-UHFFFAOYSA-N heptanal Chemical compound CCCCCCC=O FXHGMKSSBGDXIY-UHFFFAOYSA-N 0.000 description 2
- JARKCYVAAOWBJS-UHFFFAOYSA-N hexanal Chemical compound CCCCCC=O JARKCYVAAOWBJS-UHFFFAOYSA-N 0.000 description 2
- 239000000976 ink Substances 0.000 description 2
- 238000000655 nuclear magnetic resonance spectrum Methods 0.000 description 2
- BTFQKIATRPGRBS-UHFFFAOYSA-N o-tolualdehyde Chemical compound CC1=CC=CC=C1C=O BTFQKIATRPGRBS-UHFFFAOYSA-N 0.000 description 2
- FXLOVSHXALFLKQ-UHFFFAOYSA-N p-tolualdehyde Chemical compound CC1=CC=C(C=O)C=C1 FXLOVSHXALFLKQ-UHFFFAOYSA-N 0.000 description 2
- -1 paraformaldehyde) Chemical compound 0.000 description 2
- HGBOYTHUEUWSSQ-UHFFFAOYSA-N pentanal Chemical compound CCCCC=O HGBOYTHUEUWSSQ-UHFFFAOYSA-N 0.000 description 2
- DTUQWGWMVIHBKE-UHFFFAOYSA-N phenylacetaldehyde Chemical compound O=CCC1=CC=CC=C1 DTUQWGWMVIHBKE-UHFFFAOYSA-N 0.000 description 2
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 description 2
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- LGYNIFWIKSEESD-UHFFFAOYSA-N 2-ethylhexanal Chemical compound CCCCC(CC)C=O LGYNIFWIKSEESD-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 229930040373 Paraformaldehyde Natural products 0.000 description 1
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 description 1
- 238000005147 X-ray Weissenberg Methods 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000003985 ceramic capacitor Substances 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 210000003298 dental enamel Anatomy 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000004922 lacquer Substances 0.000 description 1
- OVWYEQOVUDKZNU-UHFFFAOYSA-N m-tolualdehyde Chemical compound CC1=CC=CC(C=O)=C1 OVWYEQOVUDKZNU-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- QNGNSVIICDLXHT-UHFFFAOYSA-N para-ethylbenzaldehyde Natural products CCC1=CC=C(C=O)C=C1 QNGNSVIICDLXHT-UHFFFAOYSA-N 0.000 description 1
- 229920002866 paraformaldehyde Polymers 0.000 description 1
- SQYNKIJPMDEDEG-UHFFFAOYSA-N paraldehyde Chemical compound CC1OC(C)OC(C)O1 SQYNKIJPMDEDEG-UHFFFAOYSA-N 0.000 description 1
- 229960003868 paraldehyde Drugs 0.000 description 1
- 229940100595 phenylacetaldehyde Drugs 0.000 description 1
- 239000011736 potassium bicarbonate Substances 0.000 description 1
- 229910000028 potassium bicarbonate Inorganic materials 0.000 description 1
- 235000015497 potassium bicarbonate Nutrition 0.000 description 1
- 229910000027 potassium carbonate Inorganic materials 0.000 description 1
- 235000011181 potassium carbonates Nutrition 0.000 description 1
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 description 1
- 229940086066 potassium hydrogencarbonate Drugs 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000011164 primary particle Substances 0.000 description 1
- 239000013615 primer Substances 0.000 description 1
- 239000002987 primer (paints) Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000001632 sodium acetate Substances 0.000 description 1
- 235000017281 sodium acetate Nutrition 0.000 description 1
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 1
- 235000017557 sodium bicarbonate Nutrition 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 235000017550 sodium carbonate Nutrition 0.000 description 1
- 238000001694 spray drying Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- JOXIMZWYDAKGHI-UHFFFAOYSA-N toluene-4-sulfonic acid Chemical compound CC1=CC=C(S(O)(=O)=O)C=C1 JOXIMZWYDAKGHI-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Abstract
Description
本発明は、有機溶剤に容易に溶解させることができるポリビニルアセタール樹脂粒子に関する。 The present invention relates to polyvinyl acetal resin particles that can be easily dissolved in an organic solvent.
ポリビニルブチラール樹脂等のポリビニルアセタール樹脂は、強靱性、造膜性、粒子等の分散性、塗布面への接着性等に優れていることから、様々な用途で使用されている。
ポリビニルアセタール樹脂の用途の１つとしては、例えば、バインダー樹脂としてポリビニルブチラール樹脂等のポリビニルアセタール樹脂が用いたスラリー組成物や導電ペーストが開示されている。
Polyvinyl acetal resins such as polyvinyl butyral resin are used in various applications because they are excellent in toughness, film-forming property, dispersibility of particles and the like, and adhesiveness to a coated surface.
As one of the uses of the polyvinyl acetal resin, for example, a slurry composition or a conductive paste in which a polyvinyl acetal resin such as polyvinyl butyral resin is used as a binder resin is disclosed.
これらの用途に用いられるポリビニルアセタール樹脂は、一般にメチルエチルケトン、トルエン、アルコール、これらの混合物等の有機溶剤に溶解された溶液として用いられる。
その際、溶剤への溶解が早いと作業性が向上する。ポリビニルアセタール樹脂粒子の表面積を上げると、溶剤との接触面積が上るために溶解性が向上すると思われるが、実際には溶剤の液面に乗ることになり、溶剤への溶解速度は遅い。
また、ポリビニルアセタール樹脂が有機溶剤に対する溶解性に劣るものであると、有機溶剤に溶解させた際に微量の未溶解物が生じ、粒子の分散性が低下する。
The polyvinyl acetal resin used for these applications is generally used as a solution dissolved in an organic solvent such as methyl ethyl ketone, toluene, alcohol, and a mixture thereof.
At that time, if the dissolution in the solvent is quick, the workability is improved. Increasing the surface area of the polyvinyl acetal resin particles seems to improve the solubility because the contact area with the solvent increases, but in reality, it gets on the liquid surface of the solvent, and the dissolution rate in the solvent is slow.
Further, if the polyvinyl acetal resin is inferior in solubility in an organic solvent, a small amount of undissolved substance is generated when the polyvinyl acetal resin is dissolved in the organic solvent, and the dispersibility of the particles is lowered.
特許文献１には、最小構成粒子（１次粒子）が平均粒径５μｍ以下のポリビニルアセタール樹脂粒子が開示されている。
また、特許文献２には、重合度が５００以上のポリビニルアセタール樹脂からなり、６０メッシュの篩を通過する粒子の含有割合が２０重量％以下、かさ比重が０．２０以下、かつ、平均粒子径が１００〜５００μｍであるポリビニルアセタール樹脂粒子が開示されている。
Patent Document 1 discloses polyvinyl acetal resin particles having an average particle size of 5 μm or less as the minimum constituent particles (primary particles).
Further, Patent Document 2 describes a polyvinyl acetal resin having a degree of polymerization of 500 or more, a content ratio of particles passing through a 60-mesh sieve of 20% by weight or less, a bulk specific gravity of 0.20 or less, and an average particle diameter. Polyvinyl acetal resin particles having a size of 100 to 500 μm are disclosed.
しかしながら、特許文献１及び２に開示されているポリビニルアセタール樹脂粒子でも、実際には有機溶剤に対する溶解性が不充分なものとなっており、特に樹脂添加量が多い場合の溶解性が低いものとなっている。また、平均粒子径を小さくするのみでは、添加時に粒子が浮きやすく、かつ、溶解途中に粒子の溶剤含浸不良が生じやすく、樹脂成分の均一性が低下することがある。 However, even the polyvinyl acetal resin particles disclosed in Patent Documents 1 and 2 actually have insufficient solubility in an organic solvent, and the solubility is low especially when the amount of resin added is large. It has become. Further, if only the average particle size is reduced, the particles are likely to float at the time of addition, and the solvent impregnation of the particles is likely to occur during dissolution, which may reduce the uniformity of the resin component.
本発明は、溶解途中に粒子の溶剤含浸不良が生じにくく、添加量が多い場合でも有機溶剤に容易に溶解させることができ、樹脂成分の均一性に優れるポリビニルアセタール樹脂粒子を提供することを目的とする。 It is an object of the present invention to provide polyvinyl acetal resin particles which are less likely to cause solvent impregnation defects of particles during dissolution, can be easily dissolved in an organic solvent even when the amount of addition is large, and have excellent uniformity of resin components. And.
本発明は、ポリビニルアセタール樹脂を含有し、空隙率が５０％以上、細孔半径７．５〜０．０７５μｍの空隙率比率が９８％以上、かつ、比表面積が１５ｍ２／ｇ以上である、ポリビニルアセタール樹脂粒子である。
以下に本発明を詳述する。
The present invention contains a polyvinyl acetal resin, has a porosity of 50% or more, a porosity ratio of 7.5 to 0.075 μm, a porosity ratio of 98% or more, and a specific surface area of 15 m 2 / g or more. Polyvinyl acetal resin particles.
The present invention will be described in detail below.
本発明者らは、特許文献１及び２に開示されているポリビニルアセタール樹脂粒子のように、粒子径やかさ比重を規定するのみでは、有機溶剤に対する溶解性が不充分となることを見出した。
そこで本発明者らは、空隙率が高く、かつ、細孔半径の大きい空隙の割合が多く、比表面積の高いポリビニルアセタール樹脂粒子は、添加量が多い場合でも有機溶剤に容易に溶解させることができ、かつ、溶解途中に粒子の溶剤含浸不良が生じにくく、樹脂成分の均一性に優れることを見出した。また、このようなポリビニルアセタール樹脂粒子は、溶解後に容器への付着が少ないことを見出し、本発明を完成させるに至った。
The present inventors have found that, like the polyvinyl acetal resin particles disclosed in Patent Documents 1 and 2, the solubility in an organic solvent is insufficient only by specifying the particle size and the bulk specific density.
Therefore, the present inventors can easily dissolve polyvinyl acetal resin particles having a high porosity, a large proportion of voids having a large pore radius, and a high specific surface area in an organic solvent even when the amount added is large. It was found that it was possible, and that the solvent impregnation of the particles was less likely to occur during the dissolution, and the uniformity of the resin component was excellent. Further, they have found that such polyvinyl acetal resin particles have little adhesion to the container after dissolution, and have completed the present invention.
本発明のポリビニルアセタール樹脂粒子は、空隙率が５０％以上である。上記空隙率の下限が５０％であることで、有機溶剤に対する溶解性を高めることが可能となる。上記空隙率の好ましい下限は５５％、より好ましい下限は６０％である。また、上記空隙率の上限は特に限定されないが、８０％であることが好ましい。
なお、本明細書において上記空隙率は、樹脂粒子の体積に占める細孔半径７．５〜０．００３８μｍの空隙の容積を意味する。
上記空隙率は、例えば、ポロシメーター（Ｔｈｅｒｍｏ Ｐａｓｃａｌ １４Ｂ、Ｔｈｅｒｍｏ Ｆｉｓｈｅｒ Ｓｃｉｅｎｔｉｆｉｃ．社製）を用い、水銀圧入法で測定することができる。
The polyvinyl acetal resin particles of the present invention have a porosity of 50% or more. When the lower limit of the porosity is 50%, it is possible to increase the solubility in an organic solvent. The preferable lower limit of the porosity is 55%, and the more preferable lower limit is 60%. The upper limit of the porosity is not particularly limited, but is preferably 80%.
In the present specification, the porosity means the volume of voids having a pore radius of 7.5 to 0.0038 μm in the volume of resin particles.
The porosity can be measured by a mercury intrusion method using, for example, a porosity meter (Thermo Pascal 14B, manufactured by Thermo Fisher Scientific.).
本発明のポリビニルアセタール樹脂粒子は、細孔半径７．５〜０．０７５μｍの空隙比率が９８％以上である。上記細孔半径７．５〜０．０７５μｍの空隙比率の下限が９８％であることで、有機溶剤が含浸しやすくなるため、有機溶剤に対する溶解性が向上する。上記細孔半径７．５〜０．０７５μｍの空隙比率の好ましい下限は９８．５％、より好ましい下限は９９％である。また、上記細孔半径７．５〜０．０７５μｍの空隙比率の上限は特に限定されないが、１００％であることが好ましい。
なお、本明細書において上記細孔半径７．５〜０．０７５μｍの空隙比率は、細孔半径７．５〜０．００３８μｍの空隙容積に対する細孔半径７．５〜０．０７５μｍの空隙容積の比率を表す。
上記細孔半径７．５〜０．０７５μｍの空隙比率は、例えば、ポロシメーター（Ｔｈｅｒｍｏ Ｐａｓｃａｌ １４Ｂ、Ｔｈｅｒｍｏ Ｆｉｓｈｅｒ Ｓｃｉｅｎｔｉｆｉｃ．社製）を用い、水銀圧入法で測定することができる。
The polyvinyl acetal resin particles of the present invention have a pore radius of 7.5 to 0.075 μm and a void ratio of 98% or more. When the lower limit of the void ratio of the pore radius of 7.5 to 0.075 μm is 98%, the organic solvent is easily impregnated, so that the solubility in the organic solvent is improved. The preferable lower limit of the void ratio having a pore radius of 7.5 to 0.075 μm is 98.5%, and the more preferable lower limit is 99%. The upper limit of the void ratio having a pore radius of 7.5 to 0.075 μm is not particularly limited, but is preferably 100%.
In the present specification, the void ratio of the pore radius of 7.5 to 0.075 μm is the void volume of the pore radius of 7.5 to 0.075 μm with respect to the void volume of the pore radius of 7.5 to 0.0038 μm. Represents a ratio.
The void ratio having a pore radius of 7.5 to 0.075 μm can be measured by a mercury intrusion method using, for example, a porosimeter (Thermo Pascal 14B, manufactured by Thermo Fisher Scientific.).
本発明のポリビニルアセタール樹脂粒子は、細孔半径７．５〜１．０μｍの空隙比率が８０％以上であることが好ましい。上記細孔半径７．５〜１．０μｍの空隙比率の好ましい下限が８０％であることで、有機溶剤が含浸しやすくなるため、有機溶剤に対する溶解性が向上する。上記細孔半径７．５〜１．０μｍの空隙比率のより好ましい下限は８３％、更に好ましい下限は８５％である。また、上記細孔半径７．５〜１．０μｍの空隙比率の好ましい上限は特に限定されないが、１００％であることが好ましい。
なお、本明細書において上記細孔半径７．５〜１．０μｍの空隙比率は、細孔半径７．５〜０．００３８μｍの空隙容積に対する細孔半径７．５〜１．０μｍの空隙容積の比率を表す。
上記細孔半径７．５〜１．０μｍの空隙比率は、例えば、ポロシメーター（Ｔｈｅｒｍｏ Ｐａｓｃａｌ １４Ｂ、Ｔｈｅｒｍｏ Ｆｉｓｈｅｒ Ｓｃｉｅｎｔｉｆｉｃ．社製）を用い、水銀圧入法で測定することができる。
The polyvinyl acetal resin particles of the present invention preferably have a pore radius of 7.5 to 1.0 μm and a void ratio of 80% or more. When the preferable lower limit of the void ratio having a pore radius of 7.5 to 1.0 μm is 80%, the organic solvent is easily impregnated, so that the solubility in the organic solvent is improved. A more preferable lower limit of the void ratio having a pore radius of 7.5 to 1.0 μm is 83%, and a further preferable lower limit is 85%. Further, the preferable upper limit of the void ratio having a pore radius of 7.5 to 1.0 μm is not particularly limited, but is preferably 100%.
In the present specification, the void ratio of the pore radius of 7.5 to 1.0 μm is the void volume of the pore radius of 7.5 to 1.0 μm with respect to the void volume of the pore radius of 7.5 to 0.0038 μm. Represents a ratio.
The void ratio having a pore radius of 7.5 to 1.0 μm can be measured by a mercury intrusion method using, for example, a porosimeter (Thermo Pascal 14B, manufactured by Thermo Fisher Scientific.).
本発明のポリビニルアセタール樹脂粒子は、比表面積が１５ｍ２／ｇ以上である。上記比表面積の下限が１５ｍ２／ｇであることで、有機溶剤が含浸しやすくなるため、有機溶剤に対する溶解性が向上する。上記比表面積のより好ましい下限は１７ｍ２／ｇ、更に好ましい下限は２０ｍ２／ｇである。また、上記比表面積の上限は特に限定されないが、４０ｍ２／ｇであることが好ましい。
なお、本明細書において上記比表面積は、単位重量あたりの表面積のことをいい、例えば、ポロシメーター（Ｔｈｅｒｍｏ Ｐａｓｃａｌ １４Ｂ、Ｔｈｅｒｍｏ Ｆｉｓｈｅｒ Ｓｃｉｅｎｔｉｆｉｃ．社製）を用い、水銀圧入法で測定することができる。
The polyvinyl acetal resin particles of the present invention have a specific surface area of 15 m 2 / g or more. When the lower limit of the specific surface area is 15 m 2 / g, the organic solvent is easily impregnated, so that the solubility in the organic solvent is improved. A more preferable lower limit of the specific surface area is 17 m 2 / g, and a more preferable lower limit is 20 m 2 / g. The upper limit of the specific surface area is not particularly limited, but is preferably 40 m 2 / g.
In the present specification, the specific surface area refers to the surface area per unit weight, and can be measured by a mercury intrusion method using, for example, a porosimeter (Thermo Pascal 14B, manufactured by Thermo Fisher Scientific.).
本発明のポリビニルアセタール樹脂粒子のＤ９０粒子径の好ましい下限は３０μｍ、好ましい上限は１０００μｍである。上記Ｄ９０粒子径が３０μｍ以上であることで、有機溶剤に対する溶解性が向上する。上記Ｄ９０粒子径が１０００μｍ以下であることで、有機溶剤へ溶解させた際に、容易に分散させることができる。上記Ｄ９０粒子径のより好ましい下限は５０μｍ、より好ましい上限は８００μｍである。
また、本発明のポリビニルアセタール樹脂粒子のＤ５０粒子径の好ましい下限は３０μｍ、好ましい上限は５００μｍである。上記Ｄ５０粒子径のより好ましい下限は４０μｍ、より好ましい上限は４００μｍである。
更に、本発明のポリビニルアセタール樹脂粒子のＤ１０粒子径の好ましい下限は１０μｍ、好ましい上限は３００μｍである。上記Ｄ１０粒子径のより好ましい下限は２０μｍ、より好ましい上限は１００μｍである。
なお、上記「Ｄ９０粒子径（Ｄ９０）」とは、粒度分布測定において小粒子側からの分布の累積頻度が９０％に達する点の粒子径であり、「Ｄ５０粒子径（Ｄ５０）」とは、同様に分布の累積頻度が５０％に達する点の粒子径であり、「Ｄ１０粒子径（Ｄ１０）」とは、同様に分布の累積頻度が１０％に達する点の粒子径のことである。上記Ｄ９０、Ｄ５０、Ｄ１０は、例えば、レーザー回折式粒子径分布測定装置（Ｍａｓｔｅｒｓｉｚｅｒ ３０００，Ｍａｌｖｅｒｎ Ｐａｎａｌｙｔｉｃａｌ社製）を用いて測定できる。
The preferable lower limit of the D90 particle size of the polyvinyl acetal resin particles of the present invention is 30 μm, and the preferable upper limit is 1000 μm. When the D90 particle size is 30 μm or more, the solubility in an organic solvent is improved. When the D90 particle size is 1000 μm or less, it can be easily dispersed when dissolved in an organic solvent. The more preferable lower limit of the D90 particle size is 50 μm, and the more preferable upper limit is 800 μm.
Further, the preferable lower limit of the D50 particle size of the polyvinyl acetal resin particles of the present invention is 30 μm, and the preferable upper limit is 500 μm. The more preferable lower limit of the D50 particle size is 40 μm, and the more preferable upper limit is 400 μm.
Further, the preferable lower limit of the D10 particle size of the polyvinyl acetal resin particles of the present invention is 10 μm, and the preferable upper limit is 300 μm. The more preferable lower limit of the D10 particle size is 20 μm, and the more preferable upper limit is 100 μm.
The above "D90 particle size (D90)" is the particle size at the point where the cumulative frequency of the distribution from the small particle side reaches 90% in the particle size distribution measurement, and the "D50 particle size (D50)" is Similarly, the particle size at the point where the cumulative frequency of the distribution reaches 50%, and the “D10 particle size (D10)” is the particle size at the point where the cumulative frequency of the distribution reaches 10%. The above D90, D50, and D10 can be measured using, for example, a laser diffraction type particle size distribution measuring device (Mastersizer 3000, manufactured by Malvern Panasonic).
本発明のポリビニルアセタール樹脂粒子の粒度分布εの好ましい下限は０．０１、好ましい上限は４．００である。上記粒度分布εが０．０１以上であることで、有機溶剤に対する溶解性が向上する。上記粒度分布εが４．００以下であることで、有機溶剤へ溶解させた際に、容易に分散させることができる。同様の観点から、上記粒度分布εのより好ましい下限は０．０１、より好ましい上限は３．００、更に好ましい上限は２．００である。
なお、上記粒度分布εは［（Ｄ９０−Ｄ１０）／Ｄ５０］から算出される。
The preferable lower limit of the particle size distribution ε of the polyvinyl acetal resin particles of the present invention is 0.01, and the preferable upper limit is 4.00. When the particle size distribution ε is 0.01 or more, the solubility in an organic solvent is improved. When the particle size distribution ε is 4.00 or less, it can be easily dispersed when dissolved in an organic solvent. From the same viewpoint, the more preferable lower limit of the particle size distribution ε is 0.01, the more preferable upper limit is 3.00, and the further preferable upper limit is 2.00.
The particle size distribution ε is calculated from [(D90-D10) / D50].
本発明のポリビニルアセタール樹脂粒子は、重合度が２００以上、１００００以下のポリビニルアセタール樹脂を含有することが好ましい。
上記ポリビニルアセタール樹脂の重合度が２００以上１００００以下であると、添加量が多い場合でも有機溶剤に容易に溶解させることができ、樹脂成分の均一性に優れる溶液が得られる。その為、ポリビニルアセタール樹脂の溶解工程におけるタクトタイムの短縮や、得られる各種シートの機械的強度のばらつきを安定させることができる。同様の観点から、上記ポリビニルアセタール樹脂の重合度の好ましい下限は３００、好ましい上限は８５００であり、より好ましい上限は５５００、更に好ましい上限は５０００である。
The polyvinyl acetal resin particles of the present invention preferably contain a polyvinyl acetal resin having a degree of polymerization of 200 or more and 10,000 or less.
When the degree of polymerization of the polyvinyl acetal resin is 200 or more and 10000 or less, it can be easily dissolved in an organic solvent even when the amount added is large, and a solution having excellent uniformity of resin components can be obtained. Therefore, it is possible to shorten the tact time in the dissolution step of the polyvinyl acetal resin and stabilize the variation in the mechanical strength of the obtained various sheets. From the same viewpoint, the preferable lower limit of the degree of polymerization of the polyvinyl acetal resin is 300, the preferable upper limit is 8500, the more preferable upper limit is 5500, and the further preferable upper limit is 5000.
上記ポリビニルアセタール樹脂のアセタール基量は、アルデヒドを単独で用いた場合又は２種以上を併用した場合のいずれであっても、好ましい下限が４０モル％、好ましい上限が８０モル％である。アセタール基量が４０モル％以上８０モル％以下であると、ポリビニルアセタール系樹脂が凝集することなく、多種多様な溶剤に溶解し、インク，染料の分散性の付与、および、得られる各種シートに充分な柔軟性を付与することができる。
同様の観点から、アセタール基量のより好ましい下限は６０モル％、より好ましい上限は７８モル％である。
なお、アセタール基量の計算方法については、ポリビニルアセタール樹脂のアセタール基がポリビニルアルコールの２個の水酸基をアセタール化して得られたものであることから、アセタール化された２個の水酸基を数える方法を採用する。
また、本明細書中、アセタール基がアセトアセタール基である場合には、アセトアセタール基量ともいい、アセタール基がブチラール基である場合には、ブチラール基量ともいう。
The preferable lower limit of the acetal group amount of the polyvinyl acetal resin is 40 mol%, and the preferable upper limit is 80 mol%, regardless of whether the aldehyde is used alone or in combination of two or more kinds. When the amount of acetal groups is 40 mol% or more and 80 mol% or less, the polyvinyl acetal-based resin dissolves in a wide variety of solvents without agglomeration, imparting dispersibility of inks and dyes, and in various obtained sheets. Sufficient flexibility can be imparted.
From the same viewpoint, the more preferable lower limit of the acetal group amount is 60 mol%, and the more preferable upper limit is 78 mol%.
Regarding the calculation method of the amount of acetal groups, since the acetal groups of the polyvinyl acetal resin are obtained by acetalizing the two hydroxyl groups of polyvinyl alcohol, a method of counting the two acetalized hydroxyl groups is used. adopt.
Further, in the present specification, when the acetal group is an acetal acetal group, it is also referred to as an acetal acetal group amount, and when the acetal group is a butyral group, it is also referred to as a butyral group amount.
上記ポリビニルアセタール樹脂の水酸基量の好ましい下限は２０モル％、好ましい上限は５０モル％である。上記水酸基量が２０モル％以上、５０モル％以下であると、添加量が多い場合でも有機溶剤に容易に溶解させることができ、樹脂成分の均一性に優れる溶液を得ることができる。その為、ポリビニルアセタール樹脂の溶解工程におけるタクトタイムの短縮や、得られる各種シートの機械的強度のばらつきを安定させることができる。同様の観点から、上記水酸基量のより好ましい下限は２２モル％であり、より好ましい上限は４５モル％である。 The preferable lower limit of the amount of hydroxyl groups in the polyvinyl acetal resin is 20 mol%, and the preferable upper limit is 50 mol%. When the amount of hydroxyl groups is 20 mol% or more and 50 mol% or less, it can be easily dissolved in an organic solvent even when the amount added is large, and a solution having excellent uniformity of resin components can be obtained. Therefore, it is possible to shorten the tact time in the dissolution step of the polyvinyl acetal resin and stabilize the variation in the mechanical strength of the obtained various sheets. From the same viewpoint, the more preferable lower limit of the amount of hydroxyl groups is 22 mol%, and the more preferable upper limit is 45 mol%.
上記ポリビニルアセタール樹脂のアセチル基量の好ましい下限は０．１モル％、好ましい上限は２０モル％である。上記アセチル基量が０．１モル％以上であると、有機溶剤との相溶性を向上することができる。上記アセチル基量が２０モル％以下であると、溶解時にママコが生じにくくなる。同様の観点から、上記アセチル基量のより好ましい下限は０．５モル％であり、より好ましい上限は１５モル％である。 The preferable lower limit of the amount of acetyl groups in the polyvinyl acetal resin is 0.1 mol%, and the preferable upper limit is 20 mol%. When the amount of the acetyl group is 0.1 mol% or more, the compatibility with the organic solvent can be improved. When the amount of the acetyl group is 20 mol% or less, mamaco is less likely to occur at the time of dissolution. From the same viewpoint, the more preferable lower limit of the amount of the acetyl group is 0.5 mol%, and the more preferable upper limit is 15 mol%.
本発明のポリビニルアセタール樹脂粒子における上記ポリビニルアセタール樹脂の含有量は、好ましい下限が１０重量％、好ましい上限が９０重量％である。
上記ポリビニルアセタール樹脂の含有量が上記範囲内であると、添加量が多い場合でも有機溶剤に容易に溶解させることができ、かつ、樹脂成分の均一性に優れるポリビニルアセタール樹脂組成物を得ることができる。同様の観点から、上記ポリビニルアセタール樹脂の含有量は、より好ましい下限が２０重量％、より好ましい上限が８０重量％である。
The content of the polyvinyl acetal resin in the polyvinyl acetal resin particles of the present invention has a preferable lower limit of 10% by weight and a preferable upper limit of 90% by weight.
When the content of the polyvinyl acetal resin is within the above range, it is possible to obtain a polyvinyl acetal resin composition which can be easily dissolved in an organic solvent even when the addition amount is large and has excellent uniformity of resin components. can. From the same viewpoint, the content of the polyvinyl acetal resin has a more preferable lower limit of 20% by weight and a more preferable upper limit of 80% by weight.
本発明のポリビニルアセタール樹脂粒子は、インク、塗料、焼付け用エナメル、ウォッシュプライマー、ラッカー、分散剤、接着剤、積層セラミックコンデンサ、熱現像性感光材料等の用途に用いることができる。 The polyvinyl acetal resin particles of the present invention can be used in applications such as inks, paints, baking enamel, wash primers, lacquers, dispersants, adhesives, multilayer ceramic capacitors, and heat-developable photosensitive materials.
本発明のポリビニルアセタール樹脂粒子は、ポリビニルアルコールをアセタール化する工程（アセタール工程）を行うことにより得られる。
上記ポリビニルアルコールをアセタール化する方法は、例えば、酸触媒の存在下で、上記ポリビニルアルコール溶液に各種アルデヒドを添加する方法等が挙げられる。
特に、所定の重合度、空隙率、細孔半径７．５〜０．０７５μｍの空隙比率、及び、比表面積を有する本発明のポリビニルアセタール樹脂粒子は、アセタール工程に使用するポリビニルアルコールの重合度、ポリビニルアルコール溶液のポリビニルアルコール含有量（濃度）を調整することで作製することができる。
The polyvinyl acetal resin particles of the present invention can be obtained by performing a step of converting polyvinyl alcohol into acetal (acetal step).
Examples of the method for acetalizing the polyvinyl alcohol include a method of adding various aldehydes to the polyvinyl alcohol solution in the presence of an acid catalyst.
In particular, the polyvinyl acetal resin particles of the present invention having a predetermined degree of polymerization, void ratio, void ratio of pore radius 7.5 to 0.075 μm, and specific surface area have the degree of polymerization of polyvinyl alcohol used in the acetal step. It can be produced by adjusting the polyvinyl alcohol content (concentration) of the polyvinyl alcohol solution.
上記アセタール工程におけるポリビニルアルコール溶液のポリビニルアルコール含有量 は、１．０〜７．０質量％であることが好ましい。上記範囲内とすることで、所定の重合度、空隙率、細孔半径７．５〜０．０７５μｍの空隙比率、及び、比表面積を有する本発明のポリビニルアセタール樹脂粒子を好適に作製することができる。同様の観点から、上記ポリビニルアルコール含有量は、より好ましい下限が２．０質量％、より好ましい上限が６．０質量％である。なお、上記ポリビニルアルコール樹脂の含有量は、使用するポリビニルアルコール樹脂の重合度を考慮して決定することができる。 The polyvinyl alcohol content of the polyvinyl alcohol solution in the acetal step is preferably 1.0 to 7.0% by mass. Within the above range, the polyvinyl acetal resin particles of the present invention having a predetermined degree of polymerization, porosity, porosity ratio of 7.5 to 0.075 μm pore radius, and specific surface area can be suitably produced. can. From the same viewpoint, the more preferable lower limit of the polyvinyl alcohol content is 2.0% by mass, and the more preferable upper limit is 6.0% by mass. The content of the polyvinyl alcohol resin can be determined in consideration of the degree of polymerization of the polyvinyl alcohol resin used.
上記ポリビニルアルコールのケン化度の好ましい下限は８０モル％である。上記ポリビニルアルコールのケン化度が８０モル％未満であると、水溶性が悪化するためアセタール化が困難になり、また、水酸基量が少なくなるためアセタール化自体が困難になる。より好ましい下限は８５モル％である。好ましい上限は特に限定されないが９９．９モル％である。 The preferable lower limit of the degree of saponification of the polyvinyl alcohol is 80 mol%. If the degree of saponification of the polyvinyl alcohol is less than 80 mol%, acetalization becomes difficult because the water solubility deteriorates, and acetalization itself becomes difficult because the amount of hydroxyl groups decreases. A more preferable lower limit is 85 mol%. The preferred upper limit is not particularly limited, but is 99.9 mol%.
上記ポリビニルアルコールは、アセタール化する際のポリビニルアルコールのケン化度が８０モル％以上であれば、上記ポリビニルアルコールを単独で使用してもよく、又は、ケン化度８０モル％以上のポリビニルアルコールとケン化度８０モル％未満のポリビニルアルコールを混合して、ケン化度を８０モル％以上に調整してから使用してもよい。 The polyvinyl alcohol may be used alone or with a polyvinyl alcohol having a saponification degree of 80 mol% or more as long as the degree of saponification of the polyvinyl alcohol at the time of acetalization is 80 mol% or more. Polyvinyl alcohol having a degree of saponification of less than 80 mol% may be mixed to adjust the degree of saponification to 80 mol% or more before use.
上記酸触媒は特に限定されず、有機酸、無機酸のどちらでも使用可能であり、例えば、酢酸、パラトルエンスルホン酸、硝酸、硫酸、塩酸等が挙げられる。なかでも、非ハロゲン性の酸触媒が好適である。 The acid catalyst is not particularly limited, and either an organic acid or an inorganic acid can be used, and examples thereof include acetic acid, paratoluenesulfonic acid, nitric acid, sulfuric acid, and hydrochloric acid. Of these, a non-halogen acid catalyst is preferable.
上記アセタール化に用いるアルデヒドは特に限定されず、例えば、ホルムアルデヒド（パラホルムアルデヒドを含む）、アセトアルデヒド（パラアセトアルデヒドを含む）、プロピオンアルデヒド、ブチルアルデヒド、アミルアルデヒド、ヘキシルアルデヒド、ヘプチルアルデヒド、２−エチルヘキシルアルデヒド、シクロヘキシルアルデヒド、フルフラール、ベンズアルデヒド、２−メチルベンズアルデヒド、３−メチルベンズアルデヒド、４−メチルベンズアルデヒド、ｐ−ヒドロキシベンズアルデヒド、ｍ−ヒドロキシベンズアルデヒド、フェニルアセトアルデヒド、β−フェニルプロピオンアルデヒド等が挙げられる。なかでも、アセトアルデヒド及び／又はブチルアルデヒドを用いてアセタール化することが好ましい。これらのアルデヒドは単独で使用してもよく、２種以上を併用してもよい。 The aldehyde used for the acetalization is not particularly limited, and for example, formaldehyde (including paraformaldehyde), acetaldehyde (including paraacetaldehyde), propionaldehyde, butylaldehyde, amylaldehyde, hexylaldehyde, heptylaldehyde, 2-ethylhexylaldehyde, and the like. Cyclohexylaldehyde, furfural, benzaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde, phenylacetaldehyde, β-phenylpropionaldehyde and the like can be mentioned. Of these, acetaldehyde and / or butyraldehyde is preferably used for acetalization. These aldehydes may be used alone or in combination of two or more.
上記アセタール化の反応を停止するために、アルカリによる中和を行うことが好ましい。上記アルカリとしては特に限定されず、例えば、水酸化ナトリウム、水酸化カリウム、アンモニア、酢酸ナトリウム、炭酸ナトリウム、炭酸水素ナトリウム、炭酸カリウム、炭酸水素カリウム等が挙げられる。
また、上記中和工程の前後に、水等を用いて得られた変性ポリビニルアセタール樹脂を洗浄することが好ましい。なお、洗浄水中に含まれる不純物の混入を防ぐため、洗浄は純水で行うことがより好ましい。
In order to stop the acetalization reaction, it is preferable to neutralize with an alkali. The alkali is not particularly limited, and examples thereof include sodium hydroxide, potassium hydroxide, ammonia, sodium acetate, sodium carbonate, sodium hydrogencarbonate, potassium carbonate, potassium hydrogencarbonate and the like.
Further, it is preferable to wash the modified polyvinyl acetal resin obtained with water or the like before and after the neutralization step. It is more preferable that the washing is performed with pure water in order to prevent impurities contained in the washing water from being mixed.
上記製法を経て得られた樹脂を本発明のポリビニルアセタール樹脂粒子としてもよく、更に造粒してもよい。
上記造粒の方法は特に限定されず、例えば、転動造粒法、押し出し造粒法、圧縮造粒法、撹拌造粒法、スプレードライ法、溶解凝固法、解砕造粒法等が挙げられる。
The resin obtained through the above production method may be used as the polyvinyl acetal resin particles of the present invention, or may be further granulated.
The above-mentioned granulation method is not particularly limited, and examples thereof include a rolling granulation method, an extrusion granulation method, a compression granulation method, a stirring granulation method, a spray-drying method, a dissolution coagulation method, and a crushing granulation method. Be done.
本発明によれば、添加量が多い場合でも有機溶剤に容易に溶解させることができ、かつ、溶解途中に粒子の溶剤含浸不良が生じにくく、樹脂成分の均一性に優れるポリビニルアセタール樹脂粒子を提供することができる。
また、本発明によれば、溶解性に優れることに加えて、溶解後に容器への付着が少ないポリビニルアセタール樹脂粒子を提供することができる。
According to the present invention, a polyvinyl acetal resin particle which can be easily dissolved in an organic solvent even when the amount of addition is large, is less likely to cause solvent impregnation failure of the particles during dissolution, and has excellent uniformity of resin components is provided. can do.
Further, according to the present invention, it is possible to provide polyvinyl acetal resin particles having excellent solubility and less adhesion to the container after dissolution.
以下に実施例を掲げて本発明を更に詳しく説明するが、本発明はこれら実施例のみに限定されない。 Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
（実施例１）
重合度３００、ケン化度９８．７モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水３０５０ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度５．９質量％）を得た。この溶液を４０℃に冷却し、これに純水投入量に対して濃度７．９重量％に相当する３５重量％の塩酸２４０ｇとｎ−ブチルアルデヒド１１６ｇを添加し、液温を５℃に下げてこの温度を保持してアセタール化反応を行い、反応生成物を析出させた。その後、液温を２５℃とし、３時間保持して反応を完了させ、常法により中和、水洗、及び、乾燥を行い、ポリビニルアセタール樹脂の白色粉末を得た。得られたポリビニルアセタール樹脂をＤＭＳＯ−ｄ６（ジメチルスルホキサイド）に溶解し、１３Ｃ−ＮＭＲ（核磁気共鳴スペクトル）を用いて測定した水酸基量は３５．７モル％、アセチル基量は１．３モル％、ブチラール化度は６３．０モル％であった。
(Example 1)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 300 and a degree of saponification of 98.7 mol% to 3050 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. A concentration of 5.9% by mass) was obtained. This solution was cooled to 40 ° C., and 240 g of 35% by weight hydrochloric acid and 116 g of n-butyraldehyde, which corresponded to a concentration of 7.9% by weight, were added thereto to lower the liquid temperature to 5 ° C. The acetalization reaction was carried out while maintaining the lever temperature to precipitate the reaction product. Then, the liquid temperature was set to 25 ° C. and held for 3 hours to complete the reaction, and the reaction was neutralized, washed with water and dried by a conventional method to obtain a white powder of polyvinyl acetal resin. The obtained polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and the amount of hydroxyl groups measured using 13 C-NMR (nuclear magnetic resonance spectrum) was 35.7 mol%, and the amount of acetyl groups was 1. The degree of butyralization was 63.0 mol% and 3 mol%.
（比較例１）
重合度３００、ケン化度９８．７モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水１３００ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度１２．９質量％）を得た後、この溶液を用いた以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Comparative Example 1)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 300 and a saponification degree of 98.7 mol% to 1300 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 12.9% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except that this solution was used.
（実施例２）
重合度７００、ケン化度９８．５モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水３２００ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度５．７質量％）を得た後、この溶液を用いた以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Example 2)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 700 and a saponification degree of 98.5 mol% to 3200 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 5.7% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except that this solution was used.
（比較例２）
重合度７００、ケン化度９８．５モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水１０００ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度１６．１質量％）を得た後、この溶液を用いた以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Comparative Example 2)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 700 and a saponification degree of 98.5 mol% to 1000 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 16.1% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except that this solution was used.
（実施例３）
重合度１７００、ケン化度９８．８モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水３３００ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度５．５質量％）を得た後、この溶液を用いた以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Example 3)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 1700 and a degree of saponification of 98.8 mol% to 3300 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 5.5% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except that this solution was used.
（比較例３）
重合度１７００、ケン化度９８．８モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水１４００ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度１２．１質量％）を得た後、この溶液を用いた以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Comparative Example 3)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 1700 and a degree of saponification of 98.8 mol% to 1400 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 12.1% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except that this solution was used.
（実施例４）
重合度３３００、ケン化度９９．２モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水４３００ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度４．３質量％）を得た後、この溶液を用いた以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Example 4)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 3300 and a degree of saponification of 99.2 mol% to 4300 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 4.3% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except that this solution was used.
（実施例５）
重合度３３００、ケン化度９９．２モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水５７００ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度３．３質量％）を得た後、この溶液を用いた以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Example 5)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 3300 and a degree of saponification of 99.2 mol% to 5700 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 3.3% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except that this solution was used.
（比較例４）
重合度３３００、ケン化度９９．２モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水２３００ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度７．７質量％）を得た後、この溶液を用いた以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Comparative Example 4)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 3300 and a degree of saponification of 99.2 mol% to 2300 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 7.7% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except that this solution was used.
（実施例６）
重合度５００、ケン化度９８．８モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水２６００ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度６．９質量％）を得た後、この溶液を用いた以外は、実施例１のｎ−ブチルアルデヒド量を１４４ｇへ変更した。それ以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Example 6)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 500 and a degree of saponification of 98.8 mol% to 2600 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 6.9% by mass), the amount of n-butyraldehyde in Example 1 was changed to 144 g except that this solution was used. Polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except for the above.
（比較例５）
重合度５００、ケン化度９８．８モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水１０５０ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度１５．４質量％）を得た後、この溶液を用いた以外は実施例６と同様にしてポリビニルアセタール樹脂粒子を得た。
(Comparative Example 5)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 500 and a degree of saponification of 98.8 mol% to 1050 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 15.4% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 6 except that this solution was used.
（実施例７）
重合度３３００、ケン化度９９．２モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水３４４０ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度５．３質量％）を得た後、この溶液を用いた以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Example 7)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 3300 and a degree of saponification of 99.2 mol% to 3440 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 5.3% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except that this solution was used.
（実施例８）
重合度４０００、ケン化度９９．１モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水６０００ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度４．９質量％）を得た後、この溶液を用いた以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Example 8)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 4000 and a saponification degree of 99.1 mol% to 6000 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 4.9% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except that this solution was used.
（比較例６）
重合度４０００、ケン化度９９．１モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水３７００ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度４．９質量％）を得た後、この溶液を用いた以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Comparative Example 6)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 4000 and a saponification degree of 99.1 mol% to 3700 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 4.9% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except that this solution was used.
（比較例７）
重合度４０００、ケン化度９９．１モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水２４８０ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度７．２質量％）を得た後、この溶液を用いた以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Comparative Example 7)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 4000 and a saponification degree of 99.1 mol% to 2480 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 7.2% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except that this solution was used.
（実施例９）
重合度５４００、ケン化度９９．３モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水６７００ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度２．８質量％）を得た後、この溶液を用いた以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Example 9)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 5400 and a degree of saponification of 99.3 mol% to 6700 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 2.8% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except that this solution was used.
（実施例１０）
重合度８３００、ケン化度９９．０モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水１３６００ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度１．４質量％）を得た後、この溶液を用いた以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Example 10)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 8300 and a degree of saponification of 99.0 mol% to 13600 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 1.4% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except that this solution was used.
（比較例８）
重合度５４００、ケン化度９９．３モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水４２００ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度４．４質量％）を得た後、この溶液を用いた以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Comparative Example 8)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 5400 and a degree of saponification of 99.3 mol% to 4200 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 4.4% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except that this solution was used.
（比較例９）
重合度８３００、ケン化度９９．０モル％のポリビニルアルコール２００ｇ（純度９６．５％）を純水６４００ｇに加え、９０℃の温度で約２時間攪拌し溶解させることでポリビニルアルコール溶液（ポリビニルアルコール濃度２．９質量％）を得た後、この溶液を用いた以外は実施例１と同様にしてポリビニルアセタール樹脂粒子を得た。
(Comparative Example 9)
A polyvinyl alcohol solution (polyvinyl alcohol) is dissolved by adding 200 g (purity 96.5%) of polyvinyl alcohol having a degree of polymerization of 8300 and a degree of saponification of 99.0 mol% to 6400 g of pure water and stirring at a temperature of 90 ° C. for about 2 hours to dissolve the polyvinyl alcohol. After obtaining a concentration of 2.9% by mass), polyvinyl acetal resin particles were obtained in the same manner as in Example 1 except that this solution was used.
＜評価＞
実施例及び比較例で得られたポリビニルアセタール樹脂粒子について以下の評価を行った。結果を表１に示した。
<Evaluation>
The polyvinyl acetal resin particles obtained in Examples and Comparative Examples were evaluated as follows. The results are shown in Table 1.
（１）空隙率、細孔半径７．５〜０．０７５μｍの空隙比率、細孔半径７．５〜１．０μｍの空隙比率、比表面積
得られたポリビニルアセタール樹脂粒子について、ポロシメーター（Ｔｈｅｒｍｏ Ｐａｓｃａｌ １４Ｂ）を用い、水銀圧入法にて空隙率、細孔半径７．５〜０．０７５μｍの空隙比率、細孔半径７．５〜１．０μｍの空隙比率、比表面積を測定した。なお、空隙率は樹脂粒子の体積に占める細孔半径７．５〜０．００３８μｍの空隙の容積を意味し、細孔半径７．５〜０．０７５μｍの空隙比率は、細孔半径７．５〜０．００３８μｍの空隙容積に対する細孔半径７．５〜０．０７５μｍの空隙容積の比率を意味する。また、細孔半径７．５〜１．０μｍの空隙比率は、細孔半径７．５〜０．００３８μｍの空隙容積に対する細孔半径７．５〜１．０μｍの空隙容積の比率を意味する。
(1) Porosity, void ratio having a pore radius of 7.5 to 0.075 μm, void ratio having a pore radius of 7.5 to 1.0 μm, and specific surface area The obtained polyvinyl acetal resin particles were subjected to a porosity meter (Thermo Pascal 14B). ), The porosity, the porosity with a pore radius of 7.5 to 0.075 μm, the porosity with a pore radius of 7.5 to 1.0 μm, and the specific surface area were measured by a mercury intrusion method. The porosity means the volume of the void having a pore radius of 7.5 to 0.0038 μm in the volume of the resin particles, and the porosity ratio of the pore radius of 7.5 to 0.075 μm means the pore radius of 7.5. It means the ratio of the void volume having a pore radius of 7.5 to 0.075 μm to the void volume of ~ 0.0038 μm. Further, the void ratio having a pore radius of 7.5 to 1.0 μm means the ratio of the void volume having a pore radius of 7.5 to 1.0 μm to the void volume having a pore radius of 7.5 to 0.0038 μm.
（２）粒子径（Ｄ１０、Ｄ５０、Ｄ９０）
得られたポリビニルアセタール樹脂粒子について、粒子径（Ｄ１０、Ｄ５０、Ｄ９０）を、レーザー回折式粒子径分布測定装置（Ｍａｓｔｅｒｓｉｚｅｒ ３０００）を用いて測定した。また、測定したＤ１０、Ｄ５０、Ｄ９０から粒度分布ε［（Ｄ９０−Ｄ１０）／Ｄ５０］を算出した。
(2) Particle size (D10, D50, D90)
The particle diameters (D10, D50, D90) of the obtained polyvinyl acetal resin particles were measured using a laser diffraction type particle size distribution measuring device (Mastersizer 3000). Further, the particle size distribution ε [(D90-D10) / D50] was calculated from the measured D10, D50, and D90.
（３）溶解性
５００ｍＬのビーカーに有機溶剤としてエタノールとトルエンとの混合溶剤（重量比１：１）１９２ｇを入れ、温度を２５℃に保ち、２枚の攪拌翼を用い、回転数２００ｒｐｍで攪拌しながら、得られたポリビニルアセタール樹脂粒子４８．０ｇ（濃度２０重量％）を添加し、ポリビニルアセタール樹脂粒子を溶解させた。目視で観察し、得られたポリビニルアセタール樹脂粒子を添加してから不溶解樹脂が無くなるまでの溶解時間を測定した。同様に、濃度１０重量％、濃度５重量％、濃度３重量％、濃度２重量％の場合についても溶解時間を測定した。なお、「不可」は６００分経過後も溶解しなかったか、有機溶剤に溶かした際の粘度が５０００ｍPa・ｓ以上であったことを意味する。
粘度５０００ｍPa・ｓ以上である場合は、ワイセンベルク効果により、攪拌軸に溶液が巻き付き同一の評価が出来ない。
更に、最も低濃度での溶解時間に対する溶解時間の倍数（溶解時間倍数）を、最も低濃度の場合以外の各濃度について算出し、表に示した。なお、表中の「−」は溶解時間倍数が算出出来なかったことを意味する。
(3) Put 192 g of a mixed solvent of ethanol and toluene (weight ratio 1: 1) as an organic solvent in a 500 mL beaker, keep the temperature at 25 ° C, and stir at a rotation speed of 200 rpm using two stirring blades. While doing so, 48.0 g (concentration 20% by weight) of the obtained polyvinyl acetal resin particles were added to dissolve the polyvinyl acetal resin particles. By observing visually, the dissolution time from the addition of the obtained polyvinyl acetal resin particles to the disappearance of the insoluble resin was measured. Similarly, the dissolution time was measured in the cases of concentration 10% by weight, concentration 5% by weight, concentration 3% by weight, and concentration 2% by weight. In addition, "impossible" means that it did not dissolve even after 600 minutes had passed, or that the viscosity when dissolved in an organic solvent was 5000 mPa · s or more.
When the viscosity is 5000 mPa · s or more, the solution wraps around the stirring shaft due to the Weissenberg effect, and the same evaluation cannot be performed.
Furthermore, multiples of the dissolution time with respect to the dissolution time at the lowest concentration (dissolution time multiple) were calculated for each concentration other than the case of the lowest concentration and are shown in the table. In addition, "-" in the table means that the dissolution time multiple could not be calculated.
（４）粒子の溶剤含浸状態確認
［比較例１、２、５及び実施例１、２、６で得られたポリビニルアセタール樹脂粒子］
５００ｍＬのビーカーに有機溶剤としてエタノールとトルエンとの混合溶剤（重量比１：１）１９２ｇを入れ、温度を２５℃に保ち、２枚の撹拌翼を用い、回転数２００ｒｐｍで撹拌しながら、得られたポリビニルアセタール樹脂粒子４８．０ｇを溶液濃度が２０重量％となるように添加し、ポリビニルアセタール樹脂粒子を溶解させた。樹脂粒子の状態を目視で観察し、樹脂粒子が透明となる（樹脂粒子に溶剤が含浸する）までの時間を５分間隔で測定した。
［比較例３、４、６、７及び実施例３、４、５、７、８で得られたポリビニルアセタール樹脂粒子］
５００ｍＬのビーカーに有機溶剤としてエタノールとトルエンとの混合溶剤（重量比１：１）２２８ｇを入れ、温度を２５℃に保ち、２枚の撹拌翼を用い、回転数２００ｒｐｍで撹拌しながら、得られたポリビニルアセタール樹脂粒子１２．０ｇを溶液濃度が５重量％となるように添加し、ポリビニルアセタール樹脂粒子を溶解させた。樹脂粒子の状態を目視で観察し、樹脂粒子が透明となる（樹脂粒子に溶剤が含浸する）までの時間を５分間隔で測定した。
［比較例８、９、１０と実施例９、１０で得られたポリビニルアセタール樹脂粒子］
５００ｍＬのビーカーに有機溶剤としてエタノールとトルエンとの混合溶剤（重量比１：１）２３５．２ｇを入れ、温度を２５℃に保ち、２枚の撹拌翼を用い、回転数２００ｒｐｍで撹拌しながら、得られたポリビニルアセタール樹脂粒子４．８ｇを溶液濃度が２重量％となるように添加し、ポリビニルアセタール樹脂粒子を溶解させた。樹脂粒子の状態を目視で観察し、樹脂粒子が透明となる（樹脂粒子に溶剤が含浸する）までの時間を５分間隔で測定した。
(4) Confirmation of solvent impregnation state of particles [Polyvinyl acetal resin particles obtained in Comparative Examples 1, 2 and 5 and Examples 1, 2 and 6]
Obtained by putting 192 g of a mixed solvent of ethanol and toluene (weight ratio 1: 1) as an organic solvent in a 500 mL beaker, keeping the temperature at 25 ° C., and stirring at a rotation speed of 200 rpm using two stirring blades. 48.0 g of the polyvinyl acetal resin particles were added so that the solution concentration was 20% by weight, and the polyvinyl acetal resin particles were dissolved. The state of the resin particles was visually observed, and the time until the resin particles became transparent (the resin particles were impregnated with the solvent) was measured at 5-minute intervals.
[Polyvinyl acetal resin particles obtained in Comparative Examples 3, 4, 6, 7 and Examples 3, 4, 5, 7, 8]
Obtained by putting 228 g of a mixed solvent of ethanol and toluene (weight ratio 1: 1) as an organic solvent in a 500 mL beaker, keeping the temperature at 25 ° C., and stirring at a rotation speed of 200 rpm using two stirring blades. 12.0 g of the polyvinyl acetal resin particles were added so that the solution concentration was 5% by weight, and the polyvinyl acetal resin particles were dissolved. The state of the resin particles was visually observed, and the time until the resin particles became transparent (the resin particles were impregnated with the solvent) was measured at 5-minute intervals.
[Polyvinyl acetal resin particles obtained in Comparative Examples 8, 9 and 10 and Examples 9 and 10]
235.2 g of a mixed solvent of ethanol and toluene (weight ratio 1: 1) was placed in a 500 mL beaker as an organic solvent, the temperature was kept at 25 ° C., and the mixture was stirred at a rotation speed of 200 rpm using two stirring blades. 4.8 g of the obtained polyvinyl acetal resin particles were added so that the solution concentration was 2% by weight, and the polyvinyl acetal resin particles were dissolved. The state of the resin particles was visually observed, and the time until the resin particles became transparent (the resin particles were impregnated with the solvent) was measured at 5-minute intervals.
（５）粒子溶解時の容器付着性評価
［比較例１〜７及び実施例１〜８で得られたポリビニルアセタール樹脂粒子］
５００ｍＬのビーカーに有機溶剤としてエタノールとトルエンとの混合溶剤（重量比１：１）２２８ｇを入れ、温度を２５℃に保ち、２枚の撹拌翼を用い、回転数２００ｒｐｍで撹拌しながら、得られたポリビニルアセタール樹脂粒子１２．０ｇを溶液濃度が５重量％となるように添加し、ポリビニルアセタール樹脂粒子の溶解を目視にて確認した。
その後、５００ｍＬのビーカーを１分間逆さまにして溶液を取り除き，ビーカー内側に溶け残り付着した透明な樹脂粒子の面積について、溶解中のビーカー接液面積を１００％とした場合の比率を求めた。
［比較例８、９、１０と実施例９、１０で得られたポリビニルアセタール樹脂粒子］
５００ｍＬのビーカーに有機溶剤としてエタノールとトルエンとの混合溶剤（重量比１：１）２３５．２ｇを入れ、温度を２５℃に保ち、２枚の撹拌翼を用い、回転数２００ｒｐｍで撹拌しながら、得られたポリビニルアセタール樹脂粒子４．８ｇを溶液濃度が２重量％となるように添加し、ポリビニルアセタール樹脂粒子の溶解を目視にて確認した。
その後、５００ｍＬのビーカーを１分間逆さまにして溶液を取り除き，ビーカー内側に溶け残り付着した透明な樹脂粒子の面積について、溶解中のビーカー接液面積を１００％とした場合の比率を求めた。
(5) Evaluation of container adhesion during particle dissolution [Polyvinyl acetal resin particles obtained in Comparative Examples 1 to 7 and Examples 1 to 8]
Obtained by putting 228 g of a mixed solvent of ethanol and toluene (weight ratio 1: 1) as an organic solvent in a 500 mL beaker, keeping the temperature at 25 ° C., and stirring at a rotation speed of 200 rpm using two stirring blades. 12.0 g of the polyvinyl acetal resin particles were added so that the solution concentration was 5% by weight, and the dissolution of the polyvinyl acetal resin particles was visually confirmed.
Then, the 500 mL beaker was turned upside down for 1 minute to remove the solution, and the ratio of the area of the transparent resin particles that remained undissolved and adhered to the inside of the beaker was determined when the beaker wetted area during dissolution was 100%.
[Polyvinyl acetal resin particles obtained in Comparative Examples 8, 9 and 10 and Examples 9 and 10]
235.2 g of a mixed solvent of ethanol and toluene (weight ratio 1: 1) was placed in a 500 mL beaker as an organic solvent, the temperature was kept at 25 ° C., and the mixture was stirred at a rotation speed of 200 rpm using two stirring blades. 4.8 g of the obtained polyvinyl acetal resin particles were added so that the solution concentration was 2% by weight, and the dissolution of the polyvinyl acetal resin particles was visually confirmed.
Then, the 500 mL beaker was turned upside down for 1 minute to remove the solution, and the ratio of the area of the transparent resin particles that remained undissolved and adhered to the inside of the beaker was determined when the beaker wetted area during dissolution was 100%.
本発明によれば、添加量が多い場合でも有機溶剤に容易に溶解させることができ、かつ、溶解途中に粒子の溶剤含浸不良が生じにくく、樹脂成分の均一性に優れるポリビニルアセタール樹脂粒子を提供することができる。 According to the present invention, a polyvinyl acetal resin particle which can be easily dissolved in an organic solvent even when the amount of addition is large, is less likely to cause solvent impregnation failure of particles during dissolution, and has excellent uniformity of resin components is provided. can do.
Claims (4)
空隙率が５０％以上、細孔半径７．５〜０．０７５μｍの空隙比率が９８％以上、かつ、比表面積が１５ｍ２／ｇ以上である、ポリビニルアセタール樹脂粒子。 Contains polyvinyl acetal resin,
Polyvinyl acetal resin particles having a porosity of 50% or more, a pore radius of 7.5 to 0.075 μm, a porosity ratio of 98% or more, and a specific surface area of 15 m 2 / g or more.
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