Polypropylene resin foamed particles and method for producing same

Patent metadata

Field	Value
Publication number	US-10017619-B2
Application number	US-201715695293-A
Country	US
Kind code	B2
Filing date	Sep 5, 2017
Priority date	Mar 13, 2015
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

Abstract

Expanded polypropylene resin particles include a polypropylene resin as a base material resin, wherein the polypropylene resin has a flexural modulus of 750 MPa to 1100 MPa. The flexural modulus and a melting point of the expanded polypropylene resin particles satisfy Expression (1): [Flexural modulus (MPa)]<31.19×[Melting point (° C.)]−3500, wherein the melting point of the expanded polypropylene resin particles is a melting point of 141.5° C. to 150.0° C. in a second differential scanning calorimetry (DSC) curve of a second temperature increase, the second DSC curve being obtained when the expanded polypropylene resin particles are heated from 40° C. to 220° C. at a temperature increase rate of 10° C./min in a first temperature increase, then cooled from 220° C. to 40° C. at a temperature decrease rate of 10° C./min, and heated again from 40° C. to 220° C. at a temperature increase rate of 10° C./min in the second temperature increase.

First claim

What is claimed is:

1. Expanded polypropylene resin particles comprising a polypropylene resin as a base material resin,
wherein the polypropylene resin has a flexural modulus of 750 MPa to 1100 MPa,
wherein the flexural modulus and a melting point of the expanded polypropylene resin particles satisfy Expression (1):
[Flexural modulus (MPa)]<31.19×[Melting point (° C.)]−3500

wherein the melting point of the expanded polypropylene resin particles is a melting point of 141.5° C. to 150.0° C. in a second differential scanning calorimetry (DSC) curve of a second temperature increase and the expanded polypropylene resin particles have a high temperature melting heat quantity ratio [(j/J)×100(%)] of 15% to less than 20% in the second DSC curve; or the melting point of the expanded polypropylene resin particles is a melting point of higher than 145.0° C. to 150.0° C. in the second DSC curve,
wherein the second DSC curve is obtained when the expanded polypropylene resin particles are heated from 40° C. to 220° C. at a temperature increase rate of 10° C./min in a first temperature increase, then cooled from 220° C. to 40° C. at a temperature decrease rate of 10° C./min, and heated again from 40° C. to 220° C. at a temperature increase rate of 10° C./min in the second temperature increase,
wherein the high temperature melting heat quantity ratio is a ratio of a melting heat quantity (j) from the melting point to a melting end temperature to an entire resin melting heat quantity (J) in the second DSC curve,
wherein the expanded polypropylene resin particles have, in a first DSC curve obtained in the first temperature increase, a main endothermic peak having an apex temperature of 130.0° C. to 145.0° C. and at least one endothermic peak on a high temperature side of the main endothermic peak, and
wherein the melting point in the second DSC curve is 5.0° C. to 15.0° C. higher than the apex temperature of the main endothermic peak in the first DSC curve.

2. The expanded polypropylene resin particles according to claim 1 , wherein the melting point of the second DSC curve is higher than 145.0° C. to 150.0° C.

3. The expanded polypropylene resin particles according to claim 1 , wherein the melting point in the second DSC curve is 5.5° C. to 10.0° C. higher than the apex temperature of the main endothermic peak in the first DSC curve.

4. The expanded polypropylene resin particles according to claim 3 , wherein the melting point in the second DSC curve is 5.5° C. to 8.0° C. higher than the apex temperature of the main endothermic peak in the first DSC curve.

5. The expanded polypropylene resin particles according to claim 1 , wherein the apex temperature of the main endothermic peak in the first DSC curve is 133.0° C. to 142.0° C.

6. The expanded polypropylene resin particles according to claim 1 , wherein the melting point in the second DSC curve is higher than 145.0° C. to 148.0° C.

7. The expanded polypropylene resin particles according to claim 1 , wherein the polypropylene resin has a flexural modulus of 800 MPa to 1050 MPa.

8. The expanded polypropylene resin particles according to claim 1 , wherein the base material resin comprises a polyethylene resin in an amount of 1 part by weight to 20 parts by weight with respect to 100 parts by weight of the polypropylene resin.

9. The expanded polypropylene resin particles according to claim 1 , wherein the polypropylene resin comprises a first polypropylene resin having a melting point of 130.0° C. to 140.0° C. and a second polypropylene resin having a melting point of 145.0° C. to 165.0° C.

10. The expanded polypropylene resin particles according to claim 9 , wherein the polypropylene resin comprises the first polypropylene resin and the second polypropylene resin in a total amount of 100 weight %, wherein the first polypropylene resin accounts for 50 weight % to 70 weight %, and the second polypropylene resin accounts for 30 weight % to 50 weight %.

11. The expanded polypropylene resin particles according to claim 1 , wherein a 1-butene-containing structural unit is present, as a comonomer, in an amount of 1 weight % to 15 weight % with respect to 100 weight % of polypropylene resin.

12. The expanded polypropylene resin particles according to claim 1 , wherein a 1-butene-containing structural unit is present, as a comonomer, in an amount of 1.5 weight % to 11 weight % with respect to 100 weight % of polypropylene resin.

13. A polypropylene resin in-mold expanded molded product obtained by molding the expanded polypropylene resin particles according to claim 1 .

14. The polypropylene resin in-mold expanded molded product according to claim 13 , wherein the polypropylene resin in-mold expanded molded product has a molded product density and a 50%-strained compressive strength that satisfy Expression (2):
[50%-strained compressive strength (MPa)]≥0.0069×[Molded product density (g/L)]+0.018.

15. A method for producing expanded polypropylene resin particles, comprising:
placing in a pressure-resistant vessel a mixture comprising polypropylene resin particles, water, and an inorganic gas foaming agent, the polypropylene resin particles comprising a polypropylene resin as a base material resin;
dispersing the polypropylene resin particles by stirring the mixture, obtaining a dispersion liquid;
increasing a temperature and an internal pressure of the pressure-resistant vessel; and
releasing the dispersion liquid from the pressure-resistant vessel into a pressure region to expand the polypropylene resin particles, the pressure region having a pressure lower than the internal pressure of the pressure-resistant vessel,
wherein the polypropylene resin has a flexural modulus of 750 MPa to 1100 MPa,
wherein the flexural modulus and a melting point of the expanded polypropylene resin particles satisfy Expression (1):
[Flexural modulus (MPa)]<31.19×[Melting point (° C.)]−3500

wherein the melting point of the expanded polypropylene resin particles is a melting point of 141.5° C. to 150.0° C. in a second differential scanning calorimetry (DSC) curve of a second temperature increase and the expanded polypropylene resin particles have a high temperature melting heat quantity ratio [(j/J)×100(%)] of 15% to less than 20% in the second DSC curve; or the melting point of the expanded polypropylene resin particles is a melting point of higher than 145.0° C. to 150.0° C. in the second DSC curve,
wherein the second DSC curve is obtained when the expanded polypropylene resin particles are heated from 40° C. to 220° C. at a temperature increase rate of 10° C./min in a first temperature increase, then cooled from 220° C. to 40° C. at a temperature decrease rate of 10° C./min, and heated again from 40° C. to 220° C. at a temperature increase rate of 10° C./min in the second temperature increase,
wherein the high temperature melting heat quantity ratio is a ratio of a melting heat quantity (j) from the melting point to a melting end temperature to an entire resin melting heat quantity (J) in the second DSC curve,
wherein the expanded polypropylene resin particles have, in a first DSC curve obtained in the first temperature increase, a main endothermic peak having an apex temperature of 130.0° C. to 145.0° C. and at least one endothermic peak on a high temperature side of the main endothermic peak, and
wherein the melting point in the second DSC curve is 5.0° C. to 15.0° C. higher than the apex temperature of the main endothermic peak in the first DSC curve.

16. The method according to claim 15 , wherein the releasing is performed at a temperature of the pressure region

Assignees

• Kaneka Corp

Inventors

• Yoshida Toru
• Miura Shintaro

Classifications

• C08J9/08

  developing carbon dioxide · CPC title

• C08J2201/03

  Extrusion of the foamable blend · CPC title

• C08J2423/06

  Polyethene · CPC title

• C08J9/18

  by impregnating polymer particles with the blowing agent · CPC title

• C08J2323/14

  Copolymers of propene (C08J2323/16 takes precedence) · CPC title