Urethane bumper spring, and method for producing same

Patent metadata

Field	Value
Publication number	US-2016347140-A1
Application number	US-201615234542-A
Country	US
Kind code	A1
Filing date	Aug 11, 2016
Priority date	Mar 26, 2014
Publication date	Dec 1, 2016
Grant date	—

Abstract

A urethane bumper spring is produced from a urethane raw material containing a polyester-based polyol as a polyol component and diphenylmethane diisocyanate as an isocyanate component, and includes: a skin layer; and a core portion, in which the skin layer has a density (Da) and a foamed cell diameter (Ra), and the core portion has a density (Db) and a foamed cell diameter (Rb). The density (Da), the foamed cell diameter (Ra), the density (Db), and the foamed cell diameter (Rb) satisfy relationships shown in the following expressions: 1.0≦Da/Db<1.34 (1) and 0.53<Ra/Rb≦1.0 (2). Accordingly, the urethane bumper spring can achieve a cost reduction while having durability and settling resistance under high load and high deformation.

First claim

1 . A urethane bumper spring having a hollow cylindrical shape produced by mold forming comprising:
a skin layer as an outer layer; and a core portion inside the skin layer, wherein the urethane bumper spring is produced from a urethane raw material containing a polyester-based polyol as a polyol component and diphenylmethane diisocyanate as an isocyanate component, wherein the skin layer has a density (Da) and a foamed cell diameter (Ra), and the core portion has a density (Db) and a foamed cell diameter (Rb), the density (Da), the foamed cell diameter (Ra), the density (Db), and the foamed cell diameter (Rb) satisfying relationships shown in the following expressions (1) and (2),
1.0≦ Da/Db< 1.34  (1)

0.53< Ra/Rb≦ 1.0  (2)

wherein the urethane bumper spring is configured to be fitted onto a piston rod of a shock absorber of a vehicle so as to elastically restrain an operation stroke of the shock absorber.

2 . The urethane bumper spring according to claim 1 , wherein the polyester-based polyol is formed of a condensation polymer of ethylene glycol, butanediol, and adipic acid.

3 . A method of producing the urethane bumper spring of claim 1 , the method comprising:
injecting the urethane raw material containing the polyester-based polyol as the polyol component and diphenylmethane diisocyanate as the isocyanate component into a cavity of a forming mold, followed by heating at 70° C. or more, to thereby subject the urethane raw material to primary vulcanization in the forming mold; removing a urethane molded body after the primary vulcanization from the forming mold; and heating the urethane molded body after removing the urethane molded body to subject the urethane molded body to secondary vulcanization.

4 . The urethane bumper spring according to claim 1 , wherein the density (Da) of the skin layer falls within a range of from 0.4 g/cm 3 to 0.7 g/cm 3 .

5 . The urethane bumper spring according to claim 1 , wherein the density (Db) of the core portion falls within a range of from 0.4 g/cm 3 to 0.7 g/cm 3 .

6 . The urethane bumper spring according to claim 1 , wherein the foamed cell diameter (Ra) of the skin layer falls within a range of from 25 μm to 400 μm.

7 . The urethane bumper spring according to claim 1 , wherein the foamed cell diameter (Rb) of the core portion falls within a range of from 25 μm to 400 μm.

8 . The urethane bumper spring according to claim 1 , wherein the polyester-based polyol has a number-average molecular weight (Mn) of from 500 to 4,000.

9 . The urethane bumper spring according to claim 1 , wherein the polyester-based polyol has a number-average molecular weight (Mn) of from 1,000 to 3,000.

10 . The urethane bumper spring according to claim 1 , wherein the urethane bumper spring is produced from a urethane raw material having an NCO index of from 0.9 to 1.3.

11 . The method of producing the urethane bumper spring according to claim 3 , wherein the forming mold to be used comprises a forming mold formed of a master mold and a core.

12 . The method of producing the urethane bumper spring according to claim 3 , wherein the heating in the primary vulcanization is performed at a temperature of from 70° C. to 130° C.

13 . The method of producing the urethane bumper spring according to claim 3 , wherein the heating in the primary vulcanization is performed for from 2 minutes to 60 minutes.

14 . The method of producing the urethane bumper spring according to claim 3 , wherein the injecting the urethane raw material into the cavity of the forming mold is performed after preparation of a prepolymer in advance in accordance with a prepolymer method.

15 . The method of producing the urethane bumper spring according to claim 3 , wherein the injecting the urethane raw material into the cavity of the forming mold is performed in such a manner that the polyol component and the isocyanate component are mixed in the cavity of the forming mold in accordance with a one-shot method.

Assignees

• Sumitomo Riko Co Ltd

Inventors

• Suzuki Yasuo
• Hasegawa Takuya
• Nakamura Yorikazu
• Mizusaki Masanobu

Classifications

• F16F1/3605

  characterised by their material (F16F1/362, F16F1/364, F16F1/366, F16F1/37 take precedence; composition of macromolecular compounds in general C08L) · CPC title

• B29C39/24

  Feeding the material into the mould · CPC title

• B60G2204/45021

  for limiting upper mount movement of a McPherson strut · CPC title

• B29C39/02

  for making articles of definite length, i.e. discrete articles · CPC title

• F16F9/58

  Stroke limiting stops, e.g. arranged on the piston rod outside the cylinder (F16F9/49 takes precedence) · CPC title