EPDM composition

Abstract

To provide an EPDM composition which satisfies molding processability and provides a crosslinked product exhibiting good compression set resistance properties.SOLUTION: There is provided an EPDM composition obtained by blending 13 to 45 pts.wt. of a liquid polybutadiene having a 1,2-vinyl content of 25 wt.% or more as a plasticizer in 100 pts.wt. of a peroxide-crosslinkable EPDM. The EPDM composition exhibits excellent effects so that the resulting crosslinked product sufficiently satisfies compression set resistance properties indispensable for a gasket by using a given amount of a liquid polybutadiene having a 1,2-vinyl content of 25 wt.% or more as a plasticizer while satisfying desired molding processability by ensuring flowability by the addition of a plasticizer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an EPDM composition, and more particularly to an EPDM composition that has satisfactory moldability and exhibits good compression set resistance in a crosslinked product. [Background technology]

[0002] EPDM has good heat resistance due to its polymer structure and is widely used as a molding material for industrial parts.

[0003] Among these various parts, peroxide crosslinking is used for gaskets, valves, etc., which require good compression set resistance. Here, peroxide crosslinking systems have a short crosslinking induction time and a fast rise in crosslinking, so for items that require fluidity, such as complex or thin shapes, it is necessary to add a plasticizer to improve molding defects.

[0004] As such a plasticizer, a paraffin-based process oil is generally used, which has good compatibility with EPDM.

[0005] Patent Document 1 proposes an EPDM composition in which a paraffin-based process oil and an ester-based plasticizer are blended with a peroxide-crosslinked EPDM, and which has excellent moldability and low-temperature properties of the crosslinked product.

[0006] However, with regard to improving the compression set resistance property that is essential for gaskets, the influence of plasticizers has not been investigated. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-2864 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-255924 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide an EPDM composition which has satisfactory moldability and which provides a crosslinked product exhibiting good compression set resistance. [Means for solving the problem]

[0009] The object of the present invention is to provide a method for manufacturing a rubber composition comprising: 100 parts by weight of peroxide-crosslinkable EPDM; 10 to 30 parts by weight of liquid polybutadiene having a 1,2-vinyl content of 25 to 35% by weight as a plasticizer; and 5 to 15 parts by weight of liquid polybutadiene having a 1,2-vinyl content of 90 to 99% by weight. 15 This is achieved by compounding EPDM composition with 45 parts by weight. [Effects of the Invention]

[0010] The EPDM composition of the present invention is ensured to have fluidity by adding a plasticizer, and satisfies the desired molding processability. It is a blend of 10 to 30 parts by weight of liquid polybutadiene having a 1,2-vinyl content of 25 to 35% by weight and 5 to 15 parts by weight of liquid polybutadiene having a 1,2-vinyl content of 90 to 99% by weight. By using a predetermined amount of liquid polybutadiene, the crosslinked product obtained exhibits the excellent effect of fully satisfying the compression set resistance characteristics essential for gaskets. DETAILED DESCRIPTION OF THE INVENTION

[0011] Peroxide-crosslinkable EPDM uses ethylene-α-olefin-diene copolymer rubber, which is made by copolymerizing ethylene and α-olefin with various non-conjugated diene compounds, such as dicyclopentadiene, 1,4-hexadiene, dicyclooctadiene, methylenenorbornene, vinylnorbornene, and ethylidenenorbornene.

[0012] Peroxide crosslinked EPDM contains It is a blend of 10 to 30 parts by weight of liquid polybutadiene having a 1,2-vinyl content of 25 to 35% by weight and 5 to 15 parts by weight of liquid polybutadiene having a 1,2-vinyl content of 90 to 99% by weight.Liquid polybutadiene is blended in. If other types of plasticizers or those with a lower amount of 1,2-vinyl are used, the desired moldability cannot be achieved.

[0013] Such liquid polybutadiene is 15 The liquid polybutadiene is used in an amount of from 15 to 45 parts by weight, preferably from 15 to 40 parts by weight. If the amount of liquid polybutadiene used is greater than this, the resulting crosslinked product will not be able to satisfy the desired compression set resistance properties, while if it is used in a smaller amount than this, the desired molding processability will not be able to be satisfied.

[0014] Here, from the viewpoint of satisfying the moldability and compression set properties judged from the flow volume in a well-balanced manner as well as the tensile strength and elongation at break values, 、 10 to 30 parts by weight of liquid polybutadiene having a 1,2-vinyl content of 25 to 35% by weight and 5 to 15 parts by weight of liquid polybutadiene having a 1,2-vinyl content of 90 to 99% by weight but Use in combination will be done.

[0015] Incidentally, Patent Document 2 discloses an EPDM composition containing 1 to 8 parts by weight of liquid rubber and 5 to 40 parts by weight of sericite per 100 parts by weight of EPDM polymer, and in the examples, liquid polybutadiene having a 1,2-vinyl content of 90% by weight or more is blended as the liquid rubber, but the blended amount is only 3 parts by weight, which does not satisfy the desired molding processability aimed at by the present invention.

[0016] The EPDM composition, which consists of the above essential components, is blended with an organic peroxide as a crosslinking agent, such as dicumyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, or 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyne-3, which is generally used in a ratio of about 0.5 to 10 parts by weight per 100 parts by weight of EPDM.

[0017] The composition is prepared by blending, as needed, fillers or reinforcing agents such as carbon black and silica, divalent metal oxides or hydroxides, stearic acid, process oil, antioxidants, etc., in addition to the above-mentioned components, and kneading the mixture using an internal kneader or the like. Crosslinking of the resulting mixture is carried out by press vulcanization at about 150 to 220°C for about 1 to 20 minutes, and, if necessary, oven vulcanization (secondary vulcanization) at about 120 to 200°C for about 0.1 to 20 hours. [Example]

[0018] Next, the present invention will be described with reference to examples.

[0019] Comparative Example 1 EPDM (ARLANXEO product Keltan 6950C DE) 100 parts by weight Carbon black (Tokai Carbon Products SEAST G-SVH) 40 Anti-aging agent (Ouchi Shinko Chemical Products NOCRAC MB) 1.0 Same as above Anti-aging agent (company product NOCRAC CD) 0.2 Same as above Crosslinker (Arkema product LUPEROX DC40P-SP2) 10 〃 The above ingredients were mixed in a 10-inch open roll, and the flow volume was measured to examine the fluidity of the dough. Flow volume: Using a spiral-type Gottfert capillary rheometer RCR-II, Without preheating, the flow volume was measured after 1 minute at a piston pressure of 20 MPa and 190°C. The target value is 1000 mm 3 That's all.

[0020] The kneaded material was press-vulcanized at 180°C for 6 minutes and oven-vulcanized at 150°C for 1 hour, and the normal physical properties of the resulting vulcanized material were measured.The kneaded material was also press-vulcanized at 180°C for 8 minutes and oven-vulcanized at 150°C for 1 hour, and the compression set value of the resulting vulcanized material was measured to evaluate its resistance to settling. Normal physical properties: Hardness: Compliant with JIS K-6253, Tensile strength, elongation: Compliant with JIS K-6251 Compression set: Based on JIS K-6262, measured at 120°C for 70 hours The target value was set at less than 25.

[0021] Comparative Example 2 In Comparative Example 1, 20 parts by weight of paraffinic process oil (Idemitsu Kosan product PW-380) was further used.

[0022] Comparative Example 3 In Comparative Example 1, 20 parts by weight of a sebacic acid ester plasticizer (DOS, a product of Taoka Chemical Industries, Ltd.) was further used.

[0023] Comparative Example 4 In Comparative Example 1, 20 parts by weight of a poly-α-olefin plasticizer (DYRASYN 170, manufactured by INEOS) was further used.

[0024] Comparative Example 5 In Comparative Example 1, 20 parts by weight of liquid polybutadiene (BI-3000, a product of Nippon Soda) having a 1,2-vinyl content of 0% by weight was further used.

[0025] reference Example 1 In Comparative Example 1, 20 parts by weight of liquid polybutadiene (CRAY VALLEY RICON 130) having a 1,2-vinyl content of 28% by weight was further used.

[0026] reference Example 2 In Comparative Example 1, 20 parts by weight of liquid polybutadiene (Nippon Soda product B-3000) having a 1,2-vinyl content of 90% by weight or more was further used.

[0027] Comparative Example 6 reference In Example 1, the amount of liquid polybutadiene used was changed to 10 parts by weight.

[0028] reference Example 3 reference In Example 1, the amount of liquid polybutadiene used was changed to 15 parts by weight.

[0029] reference Example 4 reference In Example 1, the amount of liquid polybutadiene used was changed to 40 parts by weight.

[0030] Comparative Example 7 three In Example 1, the amount of liquid polybutadiene used was changed to 50 parts by weight.

[0031] Comparative Example 8 reference In Example 2, the amount of liquid polybutadiene used was changed to 10 parts by weight.

[0032] reference Example 5 reference In Example 2, the amount of liquid polybutadiene used was changed to 15 parts by weight.

[0033] Example 1 reference In Example 1, 10 parts by weight of liquid polybutadiene (B-3000) having a 1,2-vinyl content of 90% by weight or more was further used.

[0034] Example 2 reference In Example 1, the amount of liquid polybutadiene (RICON 130) having a 1,2-vinyl content of 28% by weight was changed to 10 parts by weight, and 5 parts by weight of liquid polybutadiene (B-3000) having a 1,2-vinyl content of 90% by weight or more was further used.

[0035] The above examples , reference example The results obtained in the comparative examples are shown in Tables 1 and 2 below. Table 1 Measurement items ratio 1 ratio 2 ratio 3 ratio 4 Part 1 Part 2 ratio 5 [Dough fluidity] Flow volume (mm 3 ) 400 650 750 650 1450 1500 850 [Normal physical properties] Hardness (Duro A) 73 60 59 60 61 80 60 Tensile strength (MPa) 19.6 12.6 13.0 11.6 15.4 21.6 16.9 Elongation (%) 220 290 410 290 310 140 300 [Compression set] 120℃, 70 hours (%) 5 6 8 6 12 6 5 Table 2 Measurement items ratio 6 Part 3 Part 4 ratio 7 ratio 8 Reference 5 Fruit 1 Fruit 2 [Dough fluidity] Flow volume (mm 3 ) 700 1150 4500 7400 850 1200 2400 1200 [Normal physical properties] Hardness (Duro A) 67 64 53 44 75 77 63 67 Tensile strength (MPa) 17.7 16.8 3.8 2.7 21.3 21.5 16.9 22.3 Elongation (%) 230 270 290 480 150 150 240 220 [Compression set] 120℃, 70 hours (%) 8 10 24 32 5 5 11 5 [Industrial Applicability]

[0036] The EPDM composition of the present invention improves the molding processability of peroxide-crosslinkable EPDM, which has processability issues, while also satisfying the compression set resistance properties of the crosslinked product, and is therefore effectively used as a molding material for gaskets, valves, etc.

Claims

1. An EPDM composition comprising 100 parts by weight of peroxide-crosslinkable EPDM and 15 to 45 parts by weight of a liquid polybutadiene as a plasticizer, the liquid polybutadiene being a blend of 10 to 30 parts by weight of liquid polybutadiene having a 1,2-vinyl content of 25 to 35% by weight and 5 to 15 parts by weight of liquid polybutadiene having a 1,2-vinyl content of 90 to 99% by weight.

2. An EPDM composition according to claim 1, which is used as a molding material for a gasket or a valve.

3. A crosslinked molded product of the EPDM composition described in claim 1.