Saponified ethylene-vinyl ester copolymer pellet and method for producing saponified ethylene-vinyl ester copolymer pellet

• US 10,450,426 B2
• Filed: 12/22/2014
• Issued: 10/22/2019
• Est. Priority Date: 12/24/2013
• Status: Active Grant

• Current Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Original Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Inventors: Fukuyama, Shuuichi, Ono, Atsushi, Yamada, Kouji, Tanaka, Shinichi, Nagao, Yoshiharu, Miyazumi, Shinta, Honda, Seiichi
• Primary Examiner(s): Mullis, Jeffrey C
• Application Number:
  US15/104,409
• Publication Number:
  US 20160311984A1
• Time in Patent Office: 1,765 Days
• CPC Class Codes: B29B 9/06 in the form of filamentary material, e.g. combined with extrusion
• CPC Class Codes: B29B 9/065 under-water, e.g. underwater pelletizers
• CPC Class Codes: B29C 48/06 Rod-shaped
• CPC Class Codes: B29K 2031/00 Use of polyvinylesters or derivatives thereof as moulding material
• CPC Class Codes: B29L 2031/00 Other particular articles
• CPC Class Codes: C08F 16/06 Polyvinyl alcohol ; Vinyl alcohol
• CPC Class Codes: C08F 8/12 Hydrolysis
• CPC Class Codes: C08J 2323/08 Copolymers of ethene C08J2323/16 takes precedence
• CPC Class Codes: C08J 2329/04 Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
• CPC Class Codes: C08J 3/14 by precipitation from solutions C08J3/122 takes precedence
• CPC Class Codes: C08J 3/16 by coagulating dispersions C08J3/122 takes precedence

Abstract

The invention provides a saponified ethylene-vinyl ester copolymer pellet which can be inhibited from cracking, chipping and generation of fine powder at the time of transport and is excellent in melt moldability. The saponified ethylene-vinyl ester copolymer pellet of the invention is a pellet which is obtained from a resin composition containing a saponified ethylene-vinyl ester copolymer resin and in which an amount of fine powder after an impact crushing test with ball mill is 400 ppm or less with respect to the saponified ethylene-vinyl ester copolymer pellet.

Claims

1. A saponified ethylene-vinyl ester copolymer pellet comprising a resin composition containing a saponified ethylene-vinyl ester copolymer resin having an ethylene unit content of from 20 mol % to 35 mol % and in which an amount of fine powder after an impact crushing test with ball mill is 400 ppm or less with respect to the saponified ethylene-vinyl ester copolymer pellet,

wherein the impact crushing test with ball mill comprises:

charging an alumina pot ball mill with a capacity of 1 L and an outer diameter of 140 mm with 230 g of saponified ethylene-vinyl ester copolymer pellets and 95 pieces of 15 mm diameter alumina balls and

rotating the charged alumina pot at 75 revolutions per minute for 30 minutes at an initial temperature of 20°

C.

2. The saponified ethylene-vinyl ester copolymer pellet according to claim 1, which is obtainable by extruding a solution of the saponified ethylene-vinyl ester copolymer resin into a coagulating liquid of 2.0°

C. or less to obtain a coagulated strand and then cutting the coagulated strand to obtain the saponified ethylene-vinyl ester copolymer pellet.

3. The saponified ethylene-vinyl ester copolymer pellet according to claim 1, which is cylindrical and has a diameter of the bottom surface of from 1 to 6 mm and a length of from 1 to 6 mm.

4. The saponified ethylene-vinyl ester copolymer pellet according to claim 2, wherein the solution of a saponified ethylene-vinyl ester copolymer resin is the solution in which a saponified ethylene-vinyl ester copolymer resin is dissolved in a mixed solution having a mixing weight ratio of water/solvent from 80/20 to 5/95.

5. The saponified ethylene-vinyl ester copolymer pellet according to claim 2, wherein a temperature at the time of extrusion of the solution of a saponified ethylene-vinyl ester copolymer resin into a coagulating liquid is from 45 to 70°

C.

6. The saponified ethylene-vinyl ester copolymer pellet according to claim 2, wherein the coagulating liquid is a water/alcohol mixed solution.

7. The saponified ethylene-vinyl ester copolymer pellet according to claim 2 which is obtainable by retaining the extruded saponified ethylene-vinyl ester copolymer resin into the coagulating liquid for 50 to 400 seconds.

8. A method for producing a saponified ethylene-vinyl ester copolymer pellet comprising a resin composition containing a saponified ethylene-vinyl ester copolymer resin having an ethylene unit content of from 20 mol % to 35 mol % and in which an amount of fine powder after an impact crushing test with ball mill is 400 ppm or less with respect to the saponified ethylene-vinyl ester copolymer pellet,

wherein the impact crushing test with ball mill comprises:

charging an alumina pot ball mill with a capacity of 1 L and an outer diameter of 140 mm with 230 g of saponified ethylene-vinyl ester copolymer pellets and 95 pieces of 15 mm diameter alumina balls and

rotating the charged alumina pot at 75 revolutions per minute for 30 minutes at an initial temperature of 20°

C.;

wherein the method comprises extruding a solution of the saponified ethylene-vinyl ester copolymer resin into a coagulating liquid having a temperature of 2.0°

C. or less to obtain a coagulated strand and then cutting the coagulated strand to obtain the saponified ethylene-vinyl ester copolymer pellet.

9. The method for producing a saponified ethylene-vinyl ester copolymer pellet according to claim 8, wherein a solution in which the saponified ethylene-vinyl ester copolymer resin is dissolved in a mixed solution having a mixing weight ratio of water/solvent from 80/20 to 5/95 is extruded into the coagulating liquid.

10. The method for producing a saponified ethylene-vinyl ester copolymer pellet according to claim 8, wherein a temperature at the time of extrusion of the solution of a saponified ethylene-vinyl ester copolymer resin into a coagulating liquid is from 45 to 70°

C.

11. The method for producing a saponified ethylene-vinyl ester copolymer pellet according to claim 8, wherein the coagulating liquid is a water/alcohol mixed solution.

12. The method for producing a saponified ethylene-vinyl ester copolymer pellet according to claim 8, wherein a retention time of the saponified ethylene-vinyl ester copolymer resin in the coagulating liquid is from 50 to 400 seconds.