JP2008195881A - Hydrogenated NBR composition - Google Patents

Abstract

The present invention provides a hydrogenated NBR composition that has excellent oil resistance and fuel oil resistance in addition to heat resistance and cold resistance, and can be suitably used as a molding material for an intake manifold gasket of an automobile engine.
SOLUTION: 100 parts by weight of a blend of hydrogenated NBR and NBR having an acrylonitrile content of 25 to 44% by weight and an iodine value of 40 to 160, 2 to 23 parts by weight of an ester plasticizer, and 0.5 to A hydrogenated NBR composition containing 10 parts by weight, preferably a hydrogenated NBR composition further containing 0.5 to 10 parts by weight of a polyfunctional unsaturated compound.
[Selection figure] None

Description

  The present invention relates to hydrogenated NBR compositions. More specifically, the present invention relates to a hydrogenated NBR composition that is suitably used as a molding material for an intake manifold gasket that is an automobile engine part.

Hydrogenated NBR that has been used as a conventional material has an iodine value of 28 or less because of concerns about heat resistance and the like. In that case, although heat resistance is improved, it cannot be denied that there is a tendency to deteriorate in terms of low temperature characteristics (evaluated by compression set value at low temperature of −30 ° C.). As a result, when the product is exposed to a low-temperature usage environment, the product sags, and when it is a seal material, oil leakage occurs and the product function is not satisfied.
JP 2001-288303 A

The present applicant has previously described a hydrogenated NBR composition that achieves both heat resistance and cold resistance as a hydrogenated NBR having an acrylonitrile content of 15 to 30% by weight, white carbon having a specific surface area of 200 m ² / g or less, and an organic peroxide. Hydrogenated NBR compositions are proposed which contain oxides and preferably further contain polyfunctional unsaturated compounds and / or carbon black. Although this hydrogenated NBR composition achieves the intended purpose, the acrylonitrile content is low, so the polymer swells under the usage environment exposed to oil and fuel such as gaskets around the engine, making it difficult to use There was a new problem.
JP 2000-212333 A

  An object of the present invention is to provide a hydrogenated NBR composition that has excellent oil resistance and fuel oil resistance in addition to heat resistance and cold resistance, and can be suitably used as a molding material for an intake manifold gasket of an automobile engine. It is in.

  The object of the present invention is to provide 100 parts by weight of a blend of hydrogenated NBR and NBR having an acrylonitrile content of 25 to 44% by weight and an iodine value of 40 to 160, 2 to 23 parts by weight of an ester plasticizer, and organic peroxide. This is achieved by a hydrogenated NBR composition comprising 0.5 to 10 parts by weight of a product, preferably a hydrogenated NBR composition further comprising 0.5 to 10 parts by weight of a polyfunctional unsaturated compound.

  The hydrogenated NBR composition according to the present invention is superior in cost performance by blending an inexpensive NBR with a more expensive hydrogenated NBR, and has the required heat resistance, cold resistance, and oil resistance. It gives a cross-linked product that is also excellent in terms of performance (resistance to oil such as No. 3 oil and other general-purpose commercial engine oil) and fuel oil resistance (resistance to fuel oil such as fuel oil C and other general-purpose commercial gasoline). It can be suitably used as a molding material for an intake manifold gasket of an automobile engine, an automobile seal part, particularly a seal part around an engine or a mission system.

  As the hydrogenated NBR, those having an AN content of 25 to 44% by weight, preferably 30 to 40% by weight and an iodine value of 32 to 65, preferably 40 to 60 are used. Actually, for example, 2030L (AN content 36% by weight, iodine value 57 = hydrogenation rate about 80%) of the Zeon product Zetpol series, such as 2030L, and 1020 with a hydrogenation rate of about 90%. (AN content 44% by weight, iodine value 25), 2020 (AN content 36% by weight, iodine value 28), 2020L (AN content 36% by weight, iodine value 28), 3120 (AN content 25% by weight, iodine value 31) It is also used as a blended product. As NBR, nitrile (AN) content of medium nitrile (AN content 25-30%), medium-high nitrile (31-35%), and high nitrile (36-41%) can be used. Preferably, those having a medium to high nitrile content are used.

  When blended, if the AN content is less than this, the oil resistance and fuel oil resistance will be inferior, and the product will leak at high temperatures. On the other hand, those having a higher AN content than this deteriorate the low-temperature characteristics and cause oil leakage at low temperatures. Further, when NBR is blended with hydrogenated NBR, a blended product having an iodine value higher than the iodine value inherent in the used hydrogenated NBR is formed, but the iodine value is 40 to 160, preferably 50 to 110. A blend is used. In a blend having a lower iodine value than this, the low temperature characteristics are impaired, or oil leakage occurs at low temperatures. On the other hand, in a blend having a higher iodine value than this, the heat resistance is impaired.

  In practice, depending on the iodine value of the hydrogenated NBR used, the NBR is 5 to 45% by weight relative to the hydrogenated NBR 95 to 55% by weight, preferably 85 to 65% by weight, particularly preferably 85 to 75% by weight. %, Preferably 15 to 35% by weight, particularly preferably 15 to 25% by weight.

  Examples of the ester plasticizer include dibutyl phthalate, di (2-ethylhexyl) phthalate, dioctyl phthalate, di (2-ethylhexyl) adipate, di (butoxyethoxyethyl) adipate, di (2-ethylhexyl) azelate, dibutyl sebacate, Dibasic carboxylic acid esters such as di (2-ethylhexyl) sebacate, phosphate esters such as tri (2-ethylhexyl) phosphate, triphenyl phosphate, cresyl diphenyl phosphate, tricresyl phosphate, etc. are used. Commercially available ADEKA products RS107, RS700, RS705, P200, etc. can be used as they are.

  These ester plasticizers are used in a ratio of 2 to 23 parts by weight, preferably 7 to 17 parts by weight, per 100 parts by weight of a blend of hydrogenated NBR and NBR. If the ratio is less than this, the oil resistance and fuel oil resistance will be impaired and oil leakage will occur in the product. On the other hand, if the ratio is higher than this, the low temperature characteristics and oil resistance will be improved. Sexuality will be impaired.

  Crosslinking of hydrogenated NBR containing an ester plasticizer is performed using an organic peroxide.

  Examples of organic peroxides include di-tertiary butyl peroxide, dicumyl peroxide, tertiary butyl cumyl peroxide, 1,1-di (tertiary butyl peroxy) -3,3,5-trimethylcyclohexane, 2 , 5-Dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyne-3, 1,3-di (tert-butyl) Peroxyisopropyl) benzene, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tertiary butyl peroxybenzoate, tertiary butyl peroxyisopropyl carbonate, n-butyl-4,4'-di ( (Tertiary butyl peroxy) valerate or the like is used at a ratio of about 1 to 10 parts by weight, preferably about 2 to 8 parts by weight, per 100 parts by weight of the blend of hydrogenated NBR and NBR. If the amount of the organic peroxide is less than this, a vulcanizate having a sufficient crosslinking density cannot be obtained. On the other hand, if it is used in a proportion higher than this, it cannot foam or cannot be vulcanized. Even if it exists, rubber elasticity and elongation come to fall.

  In the composition, in addition to the above essential components, polyfunctional unsaturated compounds such as triallyl (iso) cyanurate, trimethylolpropane tri (meth) acrylate, triallyl trimellitate are blended with hydrogenated NBR and NBR. It is preferable to add about 0.5 to 10 parts by weight, preferably about 2 to 8 parts by weight per 100 parts by weight of the product. The compounding of the polyfunctional unsaturated compound is effective in improving the heat resistance and compression set resistance. However, when it is used at a rate higher than this, the rubber elasticity and elongation are reduced.

  In the composition, reinforcing agents such as carbon black and white carbon, fillers such as talc, clay, graphite, calcium silicate, processing aids such as stearic acid, palmitic acid, paraffin wax, zinc oxide, magnesium oxide, etc. Various compounding agents generally used in the rubber industry, such as acid acceptors, anti-aging agents, and plasticizers, are appropriately added and used. For example, thermal blacks such as HAF, FEF, SAF, and SRF carbon black, and furnace blacks such as MT carbon black are preferably used as carbon black. When these two are used in combination, elasticity at low temperatures is maintained. Also, it improves compression set at high temperature and low temperature. White carbon (reinforcing silica) is a dry-type white carbon produced by a thermal decomposition method of halogenated silicic acid or organosilicon compound, a method in which silica sand is heated and reduced, and the evaporated SiO is air-oxidized. Wet method white carbon produced by a thermal decomposition method of sodium silicate is used, and commercially available products generally marketed for the rubber industry can be used as they are.

  When carbon black is used alone, it is used at a rate of about 20 to 150 parts by weight, preferably about 40 to 90 parts by weight, per 100 parts by weight of a blend of hydrogenated NBR and NBR. The black is used as a single grade or as a mixture of multiple grades as described above. When white carbon is used alone, it is used at a ratio of about 20 to 150 parts by weight, preferably about 30 to 60 parts by weight, per 100 parts by weight of a blend of hydrogenated NBR and NBR. Both of these can be used in combination, in which case the ratio is about 10 to 140 parts by weight per 100 parts by weight of the blend of hydrogenated NBR and NBR, and the sum of these is about 20 to 150 parts by weight. Used.

  When white carbon is used alone or in combination with carbon black, the silane coupling is blended in an amount of about 0.1 parts by weight or more, preferably about 0.5 to 3 parts by weight per 100 parts by weight of the blend of hydrogenated NBR and NBR. Are preferably used. The silane coupling agent can be used without limitation as long as it is generally usable for rubber, such as vinyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane and the like can be mentioned. The formulation of the silane coupling agent contributes to the improvement of heat resistance and cold resistance.

  The composition is prepared by kneading using a kneader such as an intermix, kneader, Banbury mixer or an open roll. The vulcanization is performed using an injection molding machine, a compression molding machine, a vulcanizing press, or the like. In general, it is performed by heating at about 150 to 200 ° C. for about 3 to 60 minutes, and if necessary, secondary vulcanization is also performed by heating at about 120 to 200 ° C. for about 1 to 24 hours.

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

Example 1
Hydrogenated NBR (Nippon Zeon product Zetpol 2030L; 90 parts by weight
AN content 36% by weight, iodine value 57)
NBR (Nipol DN3380, the product of the company; 33% by weight of AN) 10 〃
White carbon (Degussa Ultrasil 360) 34 〃
Ester plasticizer (ADEKA product RS107; 15 〃
Adipic acid ether ester)
Silane coupling agent (Toray Dow coating product G-6172) 2 〃
Anti-aging agent (Ouchi Emerging Chemicals Anti CD) 1.5 〃
Anti-aging agent (Anti MBZ product) 1.5 〃
Zinc flower 2 〃
Organic peroxide (Nippon Oil & Fat Products Park Mill D) 6 〃
The above ingredients are kneaded with a kneader and an open roll, and the kneaded product is subjected to press vulcanization at 170 ° C. for 20 minutes and oven vulcanization (secondary vulcanization) at 160 ° C. for 3 hours. The following items were measured for the sheet (150 × 150 × 2 mm) and the P24 O-ring.
Normal physical properties: Compliant with JIS K6253 and JIS K6251 corresponding to ASTM D412 Compression set: Compliant with JIS K6262 corresponding to ASTM D395
High temperature (150 ℃, 70 hours)
Low temperature (-30 ° C, 22 hours, 30 minutes after release)
Low temperature characteristics: ASTM D-1329 compliant (TR-10 value)
Heat resistance: 120 ° C and 150 ° C, normal physical properties and volume change after standing in oven for 70 hours (rate)
Oil resistance: Normal physical properties and volume change (rate) after immersion in No.3 oil at 120 ° C for 70 hours
Fuel oil resistance: Normal physical properties and volume change (rate) after immersion in fuel oil C at 60 ° C for 70 hours
Product function evaluation: Visual check for oil leakage at low temperature (-30 ° C) and high temperature (120 ° C)

Examples 2 to 4 and Comparative Example In Example 1, the blend ratio of a blend of hydrogenated NBR and NBR (total 100 parts by weight) was variously changed.

The measurement results obtained in the above Examples and Comparative Examples are shown in the following table together with the composition and properties of the blend.
table
Measurement Item Example 1 Example 2 Example 3 Example 4 Comparative Example
[Blend]
Hydrogenated NBR (parts by weight) 90 80 70 60 50
NBR (parts by weight) 10 20 30 40 50
AN content (wt%) 35.7 35.4 35.1 34.8 34.5
Iodine number 81 106 130 154 179

[Normal properties]
Hardness (Duro A) 74 74 75 76 77
Tensile strength (MPa) 21.4 20.7 19.4 18.2 18.8
Elongation (%) 170 160 150 140 140
(Compression set)
High temperature (%) 12 12 12 12 12
Low temperature (%) 36 38 41 43 46
(Low temperature characteristics)
TR-10 (℃) -35 -34 -33 -32 -31
〔Heat-resistant〕
(120 ℃)
Change in hardness (points) +2 +2 +3 +3 +3
Tensile strength change rate (%) +2 +5 +12 +20 +27
Elongation change rate (%) +1 -3 -5 -10 -15
(150 ° C)
Change in hardness (points) +7 +7 +7 +7 +9
Tensile strength change rate (%) +6 +12 +22 +45 +58
Elongation change rate (%) -2 -5 -6 -9 -11
〔Oil resistance〕
Change in hardness (points) -3 -2 -2 -2 -1
Tensile strength change rate (%) +2 +2 +3 +3 +4
Elongation change rate (%) -5 -4 -2 -1 +1
Volume change rate ΔV (%) +5.1 +5.7 +5.5 +5.2 +5.5
[Fuel resistance]
Change in hardness (points) -5 -5 -11 -10 -9
Tensile strength change rate (%) -56 -55 -52 -55 -59
Elongation change rate (%) -43 -41 -43 -44 -47
Volume change rate ΔV (%) +43 +45 +41 +40 +47
[Product function evaluation]
Oil leakage at low / high temperature No No No No Yes

Claims (15)

  100 parts by weight of a blend of hydrogenated NBR and NBR having an acrylonitrile content of 25 to 44% by weight and an iodine value of 40 to 160, 2 to 23 parts by weight of an ester plasticizer, and 0.5 to 10 parts by weight of an organic peroxide A hydrogenated NBR composition comprising:   The hydrogenated NBR composition according to claim 1, wherein an NBR having an iodine value of 40 to 160 is blended with a hydrogenated NBR having an iodine value of 32 to 65.   The hydrogenated NBR composition according to claim 1, further comprising 0.5 to 10 parts by weight of a polyfunctional unsaturated compound.   The hydrogenated NBR composition according to claim 1, further comprising 20 to 150 parts by weight of carbon black, white carbon, or both.   The hydrogenated NBR composition according to claim 3, further comprising 20 to 150 parts by weight of carbon black, white carbon, or both.   The hydrogenated NBR composition according to claim 4, wherein a silane coupling agent is blended with white carbon.   The hydrogenated NBR composition according to claim 5, wherein a silane coupling agent is blended with white carbon.   The hydrogenated NBR composition according to claim 1, which is used as a molding material for an engine intake manifold gasket.   A gasket for an intake manifold obtained by crosslinking and molding the hydrogenated NBR composition according to claim 8.   The hydrogenated NBR composition according to claim 3, which is used as a molding material for an engine intake manifold gasket.   An intake manifold gasket obtained by crosslinking and molding the hydrogenated NBR composition according to claim 10.   The hydrogenated NBR composition according to claim 4, which is used as a molding material for an engine intake manifold gasket.   A gasket for an intake manifold obtained by crosslinking and molding the hydrogenated NBR composition according to claim 12.   6. The hydrogenated NBR composition according to claim 5, which is used as a molding material for an engine intake manifold gasket.   An intake manifold gasket obtained by crosslinking and molding the hydrogenated NBR composition according to claim 14.