Resin powder and method for producing same

Patent metadata

Field	Value
Publication number	US-12305032-B2
Application number	US-202017630823-A
Country	US
Kind code	B2
Filing date	Jul 27, 2020
Priority date	Jul 30, 2019
Publication date	May 20, 2025
Grant date	May 20, 2025

Abstract

A resin powder may be superior in passability through pipes and silos, and a method may produce such a resin powder. The resin powder contains a vinyl alcohol polymer, an average particle diameter thereof is 100 to 2,000 μm, and an average value PA of a roundness P by formula (1), of 50 particles arbitrarily extracted from the particles of the resin powder having a particle diameter of 100 to 1,000 μm, is 0.1 to 0.8.

P =(Σ i=1 N r i )/ NR   (1)

r i being a radius of curvature of each particle corner of the 50 particles; R being a maximum inscribed circle radius of the particle; and N being a number of particle corners. If the number of particle corners is 9 or more, the radii of curvature of eight corners, in increasing order from a smallest radius of curvature, are adopted, and N is 8.

First claim

The invention claimed is:

1. Particles, comprising:
a resin powder comprising a vinyl alcohol polymer,
wherein an average particle diameter of the particles is in a range of from 100 to 2,000 μm, and
wherein an average value PA of a roundness P, by formula (1), of 50 particles arbitrarily selected from the particles, the 50 particles having particle diameters in a range of from 100 to 1,000 μm, is in a range of from 0.1 to 0.8:
P =(Σ i=1 N r i )/ NR   (1),

wherein, in the formula (1),
r i is a curvature radius of each corner of an Nth particle of the 50 particles arbitrarily selected, corners being observed in a projection image of the 50 particles with a maximum apparent area observed at 100-fold enlargement on a digital microscope,
R is a maximum inscribed circle radius of the Nth particle, and
N is a number of the corners of the Nth particle,
wherein, when a number of the corners of the Nth particle is 9 or more, radii of curvature of eight corners, in increasing order from a smallest radius of curvature, are adopted, and N is set to 8.

2. The particles of claim 1 , wherein the vinyl alcohol polymer has a viscosity-average degree of polymerization in a range of from 200 to 5,000, and
wherein the vinyl alcohol polymer has a degree of saponification in a range of from 35 to 99.99 mol %.

3. The particles of claim 1 , wherein the average particle diameter is in a range of from 100 to 1,000 μm, and satisfying formula (2):
PA×S≥ 18  (2),

wherein, in the formula (2), S is a degree of saponification (mol %) of the vinyl alcohol polymer.

4. The particles of claim 1 , wherein a percentage content of particles which have a particle diameter of 100 to 1,000 μm is 50% by mass or more.

5. The particles of claim 1 , wherein a percentage content of the particles having a particle diameter in a range of from 106 to 1,000 μm is 50% by mass or more.

6. The particles of claim 1 , wherein a percentage content of the particles having a particle diameter in a range of from 106 to 1,000 μm is 55% by mass or more.

7. The particles of claim 1 , wherein a percentage content of the particles having a particle diameter in a range of from 106 to 1,000 μm is 60% by mass or more.

8. The particles of claim 1 , wherein a percentage content of the particles having a particle diameter in a range of from particle diameter of 100 to 1,000 μm is 100% by mass.

9. The particles of claim 1 , wherein the vinyl alcohol polymer has a viscosity-average degree of polymerization in a range of from 250 to 4,500.

10. The particles of claim 1 , wherein the vinyl alcohol polymer has a viscosity-average degree of polymerization in a range of from 400 to 4,500.

11. The particles of claim 1 , wherein the vinyl alcohol polymer has a viscosity-average degree of polymerization in a range of from 600 to 3,000.

12. The particles of claim 1 , wherein the vinyl alcohol polymer has a degree of saponification in a range of from 50 to 99.99 mol %.

13. The particles of claim 1 , wherein the vinyl alcohol polymer has a degree of saponification in a range of from 70 to 99.99 mol %.

14. The particles of claim 1 , wherein the vinyl alcohol polymer comprises, in reacted form, a further monomer in a range of from 0.1 to 20 mol. %.

15. A method for producing the particles of claim 1 , the method comprising:
grinding a resin solid comprising the vinyl alcohol polymer to obtain a first powder having a form in which corners are angular; and
polishing surfaces of the first powder to obtain the resin powder.

16. A plurality of particles, the particles comprising:
a vinyl alcohol polymer,
wherein an average particle diameter of the plurality of the particles is in a range of from 100 to 2,000 μm, and
wherein an average value PA of a roundness P, by formula (1), of 50 particles arbitrarily extracted from the particles after passing through a 16 mesh sieve screen and retained by a 150 mesh sieve screen, is in a range of from 0.1 to 0.8:
P =(Σ i=1 N r i )/ NR   (1),

wherein, in the formula (1),
r i is a curvature radius of each corner of an Nth particle of the 50 particles arbitrarily selected, corners being observed in a projection image of the 50 particles with a maximum apparent area observed at 100-fold enlargement on a digital microscope,
R is a maximum inscribed circle radius of the Nth particle; and
N is a number of the corners of the Nth particle,
wherein, when a number of the corners of the Nth particle is 9 or more, radii of curvature of eight corners, in increasing order from a smallest radius of curvature, are adopted, and N is set to 8.

17. The plurality of particles of claim 16 , wherein the vinyl alcohol polymer has a viscosity-average degree of polymerization in a range of from 200 to 5,000, and
wherein the vinyl alcohol polymer has a degree of saponification in a range of from 35 to 99.99 mol %.

18. The plurality of particles of claim 16 , wherein the average particle diameter is in a range of from 100 to 1,000 μm, and satisfies formula (2):
PA×S≥ 18  (2),

wherein, in the formula (2), S is a degree of saponification (mol %) of the vinyl alcohol polymer.

19. The plurality of particles of claim 16 , wherein a percentage content of particles having a particle diameter in a range of from 100 to 1,000 μm is 50% by mass or more.

20. A method for producing the plurality of particles of claim 16 , the method comprising:
grinding a resin solid comprising the vinyl alcohol polymer to obtain a first powder having a form in which corners are angular; and
polishing surfaces of the first powder to obtain the resin powder.

Assignees

• Kuraray Co

Inventors

• Nii Shinsuke

Classifications

• C08J3/124

  Treatment for improving the free-flowing characteristics · CPC title

• C08F216/06

  Polyvinyl alcohol {; Vinyl alcohol} · CPC title

• B29B2009/166

  Deforming granules to give a special form, e.g. spheroidizing, rounding · CPC title

• B29B9/12

  characterised by structure or composition · CPC title

• B29B9/16

  Auxiliary treatment of granules · CPC title