Particulate polyvinyl alcohol, process for making and uses of the same

Patent metadata

Field	Value
Publication number	US-10125204-B2
Application number	US-201715440718-A
Country	US
Kind code	B2
Filing date	Feb 23, 2017
Priority date	Mar 8, 2016
Publication date	Nov 13, 2018
Grant date	Nov 13, 2018

Abstract

The present invention relates generally to a polyvinyl alcohol composition having higher amorphous polyvinyl alcohol polymer content, a process for making such a polyvinyl alcohol composition, and various end uses thereof.

First claim

We claim:

1. A process for preparing a polyvinyl alcohol composition of particulate agglomerated polyvinyl alcohol particles, comprising the steps of:
(A) providing to an alcoholysis unit (i) a solution of a polyvinyl acetate in a solvent and (ii) an alkali catalyst;
(B) combining the solution and the alkali catalyst in the alcoholysis unit under agitation to hydrolyze the polyvinyl acetate to produce a first slurry comprising (i) a polyvinyl alcohol having a degree of hydrolysis of about 93% or greater and (ii) residual alkali catalyst;
(C) removing the first slurry from the alcoholysis unit;
(D) feeding to a neutralization unit (i) the first slurry and (ii) an acid;
(E) combining the first slurry with the acid in the neutralization unit to neutralize the residual alkali catalyst and produce a second slurry comprising the polyvinyl alcohol;
(F) removing the second slurry from the neutralization unit;
(G) feeding the second slurry removed from the neutralization unit to a thermal treating unit;
(H) thermally treating the second slurry in the thermal treating unit;
(I) separating polyvinyl alcohol from the second slurry to produce a polyvinyl alcohol wet cake; and
(J) drying the polyvinyl alcohol wet cake to produce the particulate agglomerated polyvinyl alcohol particles,
wherein
(1) the second slurry is removed from the neutralization unit at a first temperature; and
(2) in the thermally treating step, the temperature of the second slurry is reduced to less than the first temperature.

2. The process of claim 1 , wherein the polyvinyl acetate is a homopolymer of vinyl acetate.

3. The process of claim 1 , wherein the polyvinyl acetate is a copolymer of a predominant amount of vinyl acetate with an acrylate comonomer component selected from the group consisting of methyl acrylate, methyl methacrylate and mixtures thereof.

4. The process of claim 1 , wherein the polyvinyl acetate has (i) a degree of polymerization of from about 400 to about 10000, or (ii) a degree of hydrolysis of about 99% or greater, or (iii) both (i) and (ii).

5. The process of claim 1 , wherein the first temperature is 50° C. or greater.

6. The process of claim 5 , wherein the first temperature is about 65° C. or greater.

7. The process of claim 5 , wherein the temperature of the second slurry is reduced to less than 50° C.

8. The process of claim 5 , wherein the temperature of the second slurry is reduced to less than 40° C.

9. The process of claim 5 , wherein the temperature of the second slurry is reduced to less than 30° C.

10. The process of claim 5 , wherein the temperature of the second slurry is reduced to less than 25° C.

11. The process of claim 1 , wherein, in the thermally treating step, no heat is added to the thermal treating unit.

12. The process of claim 1 , wherein the thermally treating step is separate from the separating step.

13. The process of claim 1 , wherein the thermally treating step and separating step are combined.

14. The process of claim 1 , wherein the process further comprises the step of washing the polyvinyl alcohol wet cake to produce a purified polyvinyl alcohol wet cake, which is then subject to the drying step.

15. The process of claim 1 , wherein the particulate agglomerated polyvinyl alcohol particles from the drying step are substantially free-flowing particles.

Assignees

• Kuraray Co

Inventors

• Collins Michael
• GHEBREMESKEL Ghebrehiwet
• Kato Masaki
• Morikawa Keisuke
• Imaoka Yoriko

Classifications

• C08F2800/10

  as molar percentages · CPC title

• C08F6/008

  Treatment of solid polymer wetted by water or organic solvents, e.g. coagulum, filter cakes · CPC title

• C08F218/08

  Vinyl acetate · CPC title

• C08J3/00

  Processes of treating or compounding macromolecular substances · CPC title

• D21H19/60

  Polyalkenylalcohols; Polyalkenylethers; Polyalkenylesters · CPC title