Foam rubber composition and a molded product of foam rubber

A foam rubber composition comprising:

• (A) a low-molecular ethylene-propylene-5-ethylidene-2-norbornene terpolymer having a Mooney viscosity (ML.sub.1+4 at 100.degree. C.) of about 25 to about 35, an ethylene/propylene ratio (C2/C3) by weight of about 60/40 to about 50/50, an iodine value of about 24 to about 30, and a Q value (Mw/Mn) not exceeding about 3 as determined by gel permeation chromatography;
• (B) a high-molecular ethylene-propylene-5-ethylidene-2-norbornene terpolymer having a Mooney viscosity (ML.sub.1+4 at 100.degree. C.) of about 100 to about 200, an ethylene/propylene ratio (C2/C3) by weight of about 60/40 to about 50/50, an iodine value of about 20 to about 25 and a Q value (Mw/Mn) of about 7 to about 10;
• (C) a vulcanizing system agent containing sulfur as a vulcanizer, and zinc carbamate and sulfenamide as accelerators;
• and
• (D) a foaming agent containing N, N'-dinitrosopentamethylenetetramine and urea;
• said composition having an (A)/(B) ratio by weight of about 40/60 to about 20/80, and containing about 3.5 to about 5.0 parts by weight of (C) and about 4.0 to about 6.0 parts by weight of (D) relative to a total of 100 parts by weight of (A) and (B).

A product of foam rubber molded from a composition comprising:

• (A) a low-molecular ethylene-propylene-5-ethylidene-2-norbornene terpolymer having a Mooney viscosity (ML.sub.1+4 at 100.degree. C.) of 20 to 40, an ethylene/propylene ratio (C2/C3) by weight of 65/35 to 50/50, an iodine value of 20 to 30, and a Q value (Mw/Mn) not exceeding 3 as determined by gel permeation chromatography;
• (B) a high-molecular ethylene-propylene-5-ethylidene-2-norbornene terpolymer having a Mooney viscosity (ML.sub.1+4 at 100.degree. C.) of 100 to 300, an ethylene/propylene ratio (C2/C3) by weight of 65/35 to 50/50, an iodine value of 20 to 30 and a Q value (Mw/Mn) of 6 to 10;
• (C) a vulcanizing system agent containing sulfur as a vulcanizer, and zinc carbamate and sulfenamide as accelerators;
• and
• (D) a foaming agent containing N, N'-dinitrosopenta-methylenetetramine and urea;
• said composition having an (A)/(B) ratio by weight of 45/55 to 15/85, and containing 3.0 to 6.0 parts by weight of (C) and 3.0 to 8.0 parts by weight of (D) relative to a total of 100 parts by weight of (A) and (B).

A product of foam rubber molded from a composition comprising:

• (A) a low-molecular ethylene-propylene-5-ethylidene-2-norbornene terpolymer having a Mooney viscosity (ML.sub.1+4 at 100.degree. C.) of about 25 to about 35, an ethylene/propylene ratio (C2/C3) by weight of about 60/40 to about 50/50, an iodine value of about 24 to about 30, and a Q value (Mw/Mn) not exceeding about 3 as determined by gel permeation chromatography;
• (B) a high-molecular ethylene-propylene-5-ethylidene-2-norbornene terpolymer having a Mooney viscosity (ML.sub.1+4 at 100.degree. C.) of about 100 to about 200, an ethylene/propylene ratio (C2/C3) by weight of about 60/40 to about 50/50, an iodine value of 20 to 25 and a Q value (Mw/Mn) of about 7 to about 10;
• (C) a vulcanizing system agent containing sulfur as a vulcanizer, and zinc carbamate and sulfenamide as accelerators;
• and
• (D) a foaming agent containing N, N'-dinitrosopentamethylenetetramine and urea;
• said composition having an (A)/(B) ratio by weight of about 40/60 to about 20/80, and containing about 3.5 to 5.0 parts by weight of (C) and about 4.0 to about 6.0 parts by weight of (D) relative to a total of 100 parts by weight of (A) and (B).

A method of making a molded foam rubber product comprising:

• i) kneading a composition comprising:
• (A) a low-molecular ethylene-propylene-5-ethylidene-2-norbornene terpolymer having a Mooney viscosity (ML.sub.1+4 at 100.degree. C.) of 20 to 40, an ethylene/propylene ratio (C2/C3) by weight of 65/35 to 50/50, an iodine value of 20 to 30, and a Q value (Mw/Mn) not exceeding 3 as determined by gel permeation chromatography;
• (B) a high-molecular ethylene-propylene-5-ethylidene-2-norbornene terpolymer having a Mooney viscosity (ML.sub.1+4 at 100.degree. C.) of 100 to 300, an ethylene/propylene ratio (C2/C3) by weight of 65/35 to 50/50, an iodine value of 20 to 30 and a Q value (Mw/Mn) of 6 to 10;
• (C) a vulcanizing system agent containing sulfur as a vulcanizer, and zinc carbamate and sulfenamide as accelerators;
• and
• (D) a foaming agent containing N, N'-dinitrosopenta-methylenetetramine and urea;
• said composition having an (A)/(B) ratio by weight of 45/55 to 15/85, and containing 3.0 to 6.0 parts by weight of (C) and 3.0 to 8.0 parts by weight of (D) relative to a total of 100 parts by weight of (A) and (B);
• ii) extruding said composition through an extruder;
• and
• iii) vulcanizing said composition to yield said molded foam rubber product.

A method of making a molded foam rubber product comprising:

• i) kneading a composition comprising:
• (A) a low-molecular ethylene-propylene-5-ethylidene-2-norbornene terpolymer having a Mooney viscosity (ML.sub.1+4 at 100.degree. C.) of about 25 to about 35, an ethylene/propylene ratio (C2/C3) by weight of about 60/40 to about 50/50, an iodine value of about 24 to about 30, and a Q value (Mw/Mn) not exceeding about 3 as determined by gel permeation chromatography;
• (B) a high-molecular ethylene-propylene-5-ethylidene-2-norbornene terpolymer having a Mooney viscosity (ML.sub.1+4 at 100.degree. C.) of about 100 to 200, an ethylene/propylene ratio (C2/C3) by weight of about 60/40 to 50/50, an iodine value of 20 to 25 and a Q value (Mw/Mn) of about 7 to 10;
• (C) a vulcanizing system agent containing sulfur as a vulcanizer, and zinc carbamate and sulfenamide as accelerators;
• and
• (D) a foaming agent containing N, N'-dinitrosopentamethylenetetramine and urea;
• said composition having an (A)/(B) ratio by weight of about 40/60 to about 20/80, and containing about 3.5 to about 5.0 parts by weight of (C) and about 4.0 to about 6.0 parts by weight of (D) relative to a total of 100 parts by weight of (A) and (B);
• ii) extruding said composition through an extruder;
• and
• iii) vulcanizing said composition to yield said molded foam rubber product.