JPS6147739A - Oxidation-resistant rubber composition, oxidation-resistant rubber part and pressure type ignition time adjusting apparatus - Google Patents

Abstract

PURPOSE:A composition, consisting of a specific acrylonitrile-conjugated diene based copolymeric rubber and a vulcanizing agent of a peroxide, capable of curing with a strongly oxidizing substance produced in ignition distributing boards, etc., and capable of being diaphragms, etc. having improved oxidation resistance without inhibiting the operation. CONSTITUTION:A composition consisting of a rubber component consisting essentially of acrylonitrile-conjugated diene based copolymeric rubber in which at least 40% conjugated diene unit parts are hydrogenated and a vulcanizing agent consisting of a peroxide. Acrylonitrile-butadiene rubber is used as the above- mentioned rubber. 2-8pts.wt., based on 100pts.wt. rubber component, peroxide is used. The above-mentioned rubber composition is molded in parts, e.g. diaphragms, seal bellows and hoses used in fuel apparatus systems, etc., and used for pressure type ignition time adjusting apparatuses.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to (1) a pressure-type ignition timing adjustment device for an internal combustion ignition power distribution device, (2) a pressure-type ignition timing adjustment device, etc. The present invention relates to an oxidation-resistant rubber part and (3) an oxidation-resistant rubber composition used in the oxidation-resistant rubber part.

[Prior Art] FIG. 6 shows a typical example of a pressure type ignition timing adjustment device, and its structure and function will be explained. A diaphragm 3 is sandwiched between an upper case 1 and a lower case 2, and is connected to an ignition distributor by a rod 5 fixed to the diaphragm 3, and is connected to a pressure chamber 9 via a port 4 to respond to changes in the pressure of the internal combustion engine. It operates accordingly and adjusts the ignition timing.

Conventionally, for example, as shown in FIG. 7, a rubber 3b of a diaphragm 3 of a pressure type ignition timing adjustment device is made of NBR (tolyl butadiene rubber). However, the NBR3b
is a strong oxidizing substance (NOx) generated by spark discharge in the ignition distributor.

Cures by contacting with HNO3, ozone, etc.),
May inhibit diaphragm operation.

[Problems to be Solved by the Invention] The first invention provides an oxidation-resistant rubber composition that is hardened by strong oxidizing substances generated in ignition distributors, etc., and does not inhibit the operation of diaphragms, etc. The purpose is to

The object of the second invention is to provide an oxidation-resistant rubber component such as a diaphragm that is hardened by strong oxidizing substances generated within an ignition distributor and does not interfere with operation.

It is an object of the third invention to provide a pressure-type ignition timing adjustment device that hardens the diaphragm etc. with strong oxidizing substances generated in the ignition distributor and does not inhibit the operation of the diaphragm etc.

Means for Solving Problem E 1 [First Invention] The oxidation-resistant rubber composition of the first invention mainly comprises an acrylonitrile-conjugated diene copolymer rubber in which at least 40% of the conjugated diene units are hydrogenated. and a vulcanizing agent consisting of a peroxide base.

The rubber component constituting the oxidation-resistant rubber composition of the first invention is mainly composed of acrylonitrile-conjugated diene copolymer rubber containing a small amount of conjugated diene units (both 40% hydrogenated). The acrylonitrile-conjugated diene copolymer rubber may be blended with other substances.Acrylonitrile-conjugated diene copolymer rubber is a copolymer of acrylonitrile and a conjugated diene (butadiene, isoprene, etc.). The method of copolymerization does not matter.

Acrylonitrile-butadiene copolymer rubber (referred to as NBR) is usually used as the copolymer rubber.

The above copolymer rubber has a small amount of conjugated diene units (both 4
0% hydrogenated. That is, the unsaturated bonds of the conjugated diene units in the copolymer rubber are hydrogenated to become saturated bonds. A rubber material made by vulcanizing a rubber component mainly consisting of a copolymer rubber that is less than 40% hydrogenated with a peroxide,
This is because strong oxidizing substances (nitrogen oxides, nitric acid, etc.) generated within the ignition distributor may cause hardening or cracking.

The inventors have discovered that the above-mentioned curing mechanism is as follows. In other words, the curing mechanism is thought to be that the unsaturated bond parts contained in the NBR are oxidized and decomposed by strong oxidizing substances generated in the ignition distributor, and the decomposed products are recombined and crosslinked to progress the curing. It will be done. That is, the hardening phenomenon of NBR is due to the presence of unsaturated double viscosity within the polymer.

Another component of the oxidation-resistant rubber composition of the present invention is a vulcanizing agent comprising a peroxide. The type of peroxide is not particularly limited, but the following can be used, for example.

[Peroxide]... (1) Ketone peroxides (methyl ethyl ketone peroxide, etc.) (2) Peroxyketals (di-t-butylperoxy-3,3,5-
trimethylcyclohexane, etc.) (3) Hydroperoxides (cumene hydroperoxide, etc.) (
4) Dialkyl peroxides (dicumyl peroxide, etc.) (5) Diacyl peroxides (acetyl peroxide, etc.) (6) Peroxydicarbonates (diisopropyl peroxydicarbonate, etc.) (7)
Peroxyesters (t-butyl-berbenzoate, etc.) The amount of the peroxide blended is not particularly limited, but is preferably 2 to 8 parts by weight based on 100 parts by weight of the total rubber part. The amount of peroxide blended was determined based on the test results (Figure 4) of the relationship between the amount of peroxide blended and the flex cracking life of rubber (according to JIS-6301). .

[Second Invention] The oxidation-resistant rubber component of the second invention is obtained by vulcanizing a component mainly consisting of an acrylonitrile-conjugated diene copolymer rubber in which at least 40% of the conjugated diene units are hydrogenated with a peroxide. It is characterized by being made of a rubber material.

The rubber material constituting the oxidation-resistant rubber component of the second invention is:
A rubber component mainly composed of an acrylonitrile-conjugated diene copolymer rubber in which at least 40% of the conjugated diene units are hydrogenated is vulcanized with a peroxide. The predetermined rubber components and peroxides mentioned here are the same as those explained in the first invention section above. That is, the oxidation-resistant rubber component of the second invention is produced using a rubber material produced using the oxidation-resistant rubber composition of the first invention as a raw material. Specifically, the above-mentioned oxidation-resistant rubber parts are automobile-related parts such as diaphragms, seal bellows, hoses used in fuel system, etc., and are exposed to strong oxidizing substances.

[Third invention] The pressure-type ignition timing adjustment device of the third invention is characterized in that it uses at least one of a diaphragm and a seal bellow, which are made of a rubber material. In the apparatus, the rubber material is characterized in that a rubber component mainly consisting of an acrylonitrile-conjugated diene copolymer rubber in which at least 40% of the conjugated diene units are hydrogenated is vulcanized with a peroxide. .

The same rubber material as that described in the second invention is used as the rubber material constituting at least one of the diaphragm and the seal bellows, which are one component of the pressure type ignition timing adjustment device of the third invention. That is, the composition for producing the rubber material is the same as that explained in the first invention.

The structure of the pressure-type ignition timing adjustment device of the third invention is not particularly limited, but it has a diaphragm or a seal bellow that is exposed to strong oxidizing substances (nitrogen oxides, nitric acid, etc.) generated in the pressure-type ignition distributor. It is of structure. Aspects of the pressure type ignition timing adjustment device of the third invention include, for example, the sixth aspect of the pressure type ignition timing adjustment device.
A pressure-type ignition timing adjustment device using a diaphragm as shown in the figure (Diaphragm 3 is subject to improvement), a pressure-type ignition timing adjustment device using a diaphragm and a seal bellow as shown in Figure 8 (Seal bellow 8) The diaphragm 311 of the pressure type ignition timing adjustment device using a diaphragm as shown in FIG. 9 is the subject of improvement.

[Example] Hereinafter, the inventions 1 to 3 of Suihiro will be explained with reference to Examples.

[Embodiment of the first invention] 1. Consideration of hydrogenation (1) Stability against nitric acid Rubber samples for testing were produced by the following method.

First, the hydrogenation rate is 20%, 40%, 60%, 9
Four kinds of 5% hydrogenated NBR and NBR (hydrogenation rate 0%) were added and mixed with various compounding agents according to the following formulation to obtain a rubber compound.

[Blending recipe (unit: parts by weight)]...Rubber polymer 1O
O1 stearic acid 1, zinc white 5, sulfur 0.5, FEF carbon 40, tetramethylthiuram disulfide 1.5
, N-cyclohexyl-2-benzothiazolylsulfenamide 1, N-7enyl-N=-isopropyl-P-
1 phenylenediamine, 1 alkylated diphenylamine
Each of these was heated under pressure at 160° C. for 30 minutes to obtain a rubber sample as a vulcanizate. In addition, the hydrogenation rate is
It was determined by the iodine value method.

From the rubber sample obtained above, l Qmmx iQm
A test piece measuring m×2 mm was obtained, and the test piece was immersed in a 20% by weight nitric acid aqueous solution (40° C.), and the results are shown in FIG. The immersion test apparatus is shown in FIG.

According to the results shown in Figure 1, when the time for the same change in hardness (+18 or -18) is about 55 hours for non-hydrogenated NBR, it is about 3 hours for those with a hydrogenation rate of 40% or more.
It is 00 hours. That is, the oxidation stability against nitric acid is about 6 times that of the comparative example when the hydrogen m addition ratio is 40% or more.

(3) Stability against sour gasoline NBR used in diaphragms, hoses, etc. of fuel system hardens against sour (deteriorated) gasoline, which is a strongly oxidizing substance, using the same deterioration mechanism as nitric acid. Tests of hydrogenated NBR on sour gasoline were conducted below.

First, a sour gasoline test liquid was prepared as follows. That is, gasoline test liquid (isooctane/toluene 4/6
) to which o, ippm of cupric ions were added, and 10 mg equivalent of cumene hydroperoxide was added to 1 L of this solution to prepare a sour gasoline test solution.

Each NBR with a hydrogenation rate of 0.20%, 40.60% and 190% was added to 300mL of the sour gasoline test liquid prepared above.
Three to four samples were immersed, and after a specified immersion time, the rubber sample was taken out and the tensile strength of the sample was tested using a tensile tester. The test conditions were a temperature of 60° C., a JIS No. 3 dumbbell piece as the test rubber sample, and a tensile speed of 500±25 mm/min for the rubber sample cylinder in the tensile strength test.

The test results are shown in Table 1.

The test results for sour gasoline (Table 1) also show that for NBR with a hydrogenation rate of 40% or more, the immersion time for the tensile strength change rate to be -60% is more than twice that of that without hydrogenation. , excellent oxidation resistance.

(3) Stability against ozone Diene rubbers such as NBR used in rubber parts that are constantly in contact with the outside air or near high voltage or arcs harden when exposed to an ozone atmosphere.

Hydrogen addition rate to ozone 0, 20, 40, 60.90
The test for %NBR was conducted as follows. The test method is based on JISK6301.

The test conditions were: ozone concentration: 5o±5pphm, ambient temperature: 40°C, repeated elongation rate of 20 and 20%, test rubber sample: tanzak-shaped rubber (60 mm x 10 mm x 2 mm).
and Ltc.

The test results are shown in Table 2. According to the results in this table, those with a hydrogenation rate of 40% or more have a crack initiation life that is more than 10 times longer than those without hydrogenation, and in particular, those with a hydrogenation rate of 60% or more. The effect is great.

2. Examination of peroxide vulcanization (1) Stability against bending fatigue A test of the effect of peroxide vulcanization in comparison with conventional sulfur vulcanization was conducted as follows. That is, peroxide (dicumyl peroxide) was used instead of sulfur as shown in the following formulation, and NBR was vulcanized in an atmosphere of 120'C using hydrogenation rates of 40% and 90%. did. Other test conditions and test rubber samples are J15K.
Conforms to 6301.

[Blending recipe (unit: parts by weight)]...Rubber polymer 10
0, stearic acid 1, dicumyl peroxide 3, FE
F carbon 40, tetramethylthiuram disulfide 1
．． 5. N-phenyl-N'-isopropyl-P-phenylenediamine 1, alkylated diphenylamine 1゜The above test results are shown in Figure 2 (40% hydrogenation rate) and Figure 3 (90% hydrogenation rate) It was shown to.

According to these results, 40% or 90% hydrogenated NB
A peroxide vulcanizate using R has a significantly improved flexural fatigue life compared to a sulfur vulcanizate.

(2) Stability against nitric acid Table 3 N with hydrogenation rates of 40 and 90% obtained in (1) above
A test piece consisting of a peroxide vulcanizate and a sulfur vulcanizate (comparative example) using BR was soaked in 20% nitric acid at 240%
It was immersed for a period of time, and the change in hardness after this immersion was measured. The results are shown in Table 3.

According to this result, by using peroxide as a vulcanizing agent in hydrogenated NBR, the life is improved against strongly oxidizing substances.

Summarizing all the test results above, the hydrogenation rate is 40
% or more of NBR vulcanized with peroxide has superior oxidation stability to nitric acid, oxidation stability to sour gasoline, and oxidation stability to ozone, as well as superior oxidation stability to nitric acid, oxidation stability to sour gasoline, and oxidation stability to ozone, compared to non-hydrogen-added NBR. It also has excellent fatigue life. Therefore, the rubber composition containing the predetermined NBR and peroxide according to this example is a composition that provides a material with extremely excellent oxidation resistance.

[Embodiment of the second invention] As an embodiment of the oxidation-resistant rubber part of the second invention, a rubber material is obtained by vulcanizing an NBR rubber component in which 40% of the butadiene units are hydrogenated with peroxide. be able to.

This diaphragm can be 3 as shown in FIG. 6 or 311 as shown in FIG. Further, this seal bellow can be made into a number 8 as shown in FIG.

Since the rubber parts according to the above embodiments are made of a rubber material manufactured using the oxidation-resistant rubber composition according to the first invention,
It has excellent oxidation resistance and bending fatigue resistance.

[Embodiment of the third invention] As an embodiment of the pressure type ignition timing adjustment device of the third invention,
A pressure type ignition timing adjustment device using at least one of a diaphragm and a seal bellows, which is characterized by being made of the rubber material manufactured in the embodiment of the second invention, can be provided.

For example, the present pressure type ignition timing adjustment device can be as shown in FIG. In the pressure type ignition timing adjustment device, a diaphragm 3 is fixed to an upper case 1 and a lower case 2 made of metal, resin, or the like. The function of the pressure type ignition timing adjustment device is that negative pressure is applied from the port 4, the diaphragm 3 is actuated by the negative pressure, and the rod 5 fixed to the diaphragm 3 is actuated to change the ignition timing of the ignition distributor. That's true. In the pressure type ignition timing adjustment device, the diaphragm 3, which comes into contact with strong oxidizing substances (NOx, HNO3, 03, etc.) generated by spark discharge in the ignition distributor, is made of the above-mentioned oxidation-resistant rubber material.

This pressure type ignition timing adjustment device of another embodiment includes the eighth
It can be as shown in the figure. The pressure type ignition timing adjustment device has both advance and retard functions in one device, and with this structure, strong oxidizing substances generated from the ignition distributor come into contact with the seal bellows 8. Therefore, in the pressure type ignition timing adjustment device, the seal bellows 8 is made of the above-mentioned oxidation-resistant rubber material.

In addition, as this pressure type ignition timing adjustment device of other embodiments,
It can be as shown in FIG.

The pressure type ignition timing adjustment device has two advance functions in one device, and in this structure, the diaphragm 311 on the ignition distributor side is made of the above-mentioned oxidation-resistant rubber material. .

The pressure type ignition timing adjustment device shown in Figures 7 and 8 to 9 has a long life pressure type ignition timing adjustment device because the rubber parts that come into contact with strong oxidizing substances are made of rubber material with excellent oxidation resistance. It is a device.

[Effect of the invention] The oxidation-resistant rubber composition of the first invention consists of a rubber component mainly consisting of an acrylonitrile-conjugated diene copolymer rubber in which at least 40% of the conjugated diene units are hydrogenated, and a peroxide. It is characterized by containing a vulcanizing agent. Therefore, the rubber material made of the present oxidation-resistant rubber composition has a small number of carbon-carbon unsaturated bonds that can be oxidized and decomposed by strong oxidizing substances such as NOX, nitric acid, and ozone, so it has excellent oxidation resistance and It also has excellent bending fatigue resistance. Therefore, the present acid-resistant and acid-resistant rubber composition is a rubber composition that provides a rubber material with excellent oxidation resistance compared to conventional rubber compositions consisting of rubber such as non-hydrogenated NBR and sulfur.

The oxidation-resistant rubber component of the second invention is made of a rubber material obtained by vulcanizing a rubber component mainly consisting of an acrylonitrile-conjugated diene copolymer rubber in which at least 40% of the conjugated diene units are hydrogenated with a peroxide. It is characterized by being configured. Therefore, the oxidation-resistant rubber parts of the second invention have the same effect as the conventional hydrogen-free N
It has excellent oxidation resistance and bending fatigue resistance compared to rubber materials made by vulcanizing rubber such as BR with sulfur.

A pressure-type ignition timing adjustment device according to a third aspect of the invention is characterized in that the pressure-type ignition timing adjustment device uses at least one of a diaphragm and a seal bellows, each of which is made of a rubber material. is characterized in that it is formed by vulcanizing with peroxide a rubber component mainly consisting of an acrylonitrile-conjugated diene copolymer rubber in which at least 40% of the conjugated diene units are hydrogenated. In the timing adjustment device, the diaphragm or seal bellow that comes into contact with the strong oxidizing substance generated by the spark discharge in the ignition distribution device has excellent oxidation resistance and bending fatigue resistance according to the second invention. It is a rubber part. Therefore, this pressure-type ignition timing adjustment device has excellent oxidation resistance and bending fatigue resistance, has a long life, and has extremely stable quality compared to conventional pressure-type ignition timing adjustment devices.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the elapsed time of immersion in nitric acid and the change in hardness of rubber materials made of NBR with various hydrogenation rates. Figure 2 or 3 shows NB with a hydrogenation rate of 40% or 90%.
It is a graph showing the relationship between the number of bending times and the crack length of a rubber material made by vulcanizing R with a peroxide or the like. FIG. 4 is a graph showing the relationship between the amount of peroxide added to the rubber material and the number of cracks in the rubber material. FIG. 5 is a schematic diagram of a nitric acid immersion testing apparatus for rubber materials. 6, 8, and 9 are schematic partial views of typical pressure-type ignition timing adjusting devices of the third invention, and FIG. FIG. 3 is a partially enlarged sectional view of a diaphragm used in the adjustment device. 12... Stirrer 13... Ground glass 1
4... Pressure-resistant glass container 15... Nitric acid test liquid (40±2°C) 16... Drought water (40°C) 17... Test rubber piece 18... Water bath 19... Heater 1.1
1.111... Upper case 2.21.211... Lower case 3.31.311... Diaphragm 3a... Base fabric 3b... Rubber 5.51.5
11...Rod

Claims (10)

[Claims] (1) Oxidation resistance characterized by containing a rubber component mainly consisting of an acrylonitrile-conjugated diene copolymer rubber in which at least 40% of the conjugated diene units are hydrogenated, and a vulcanizing agent consisting of a peroxide. Rubber composition. (2) Acrylonitrile-conjugated diene copolymer rubber is
The oxidation-resistant rubber composition according to claim 1, which is acrylonitrile-butadiene rubber (NBR). (3) The amount of peroxide is 2 to 8 parts by weight per 100 parts by weight of the rubber part.
The oxidation-resistant rubber composition described in . (4) It is characterized by being composed of a rubber material obtained by vulcanizing a rubber component mainly consisting of an acrylonitrile-conjugated diene copolymer rubber in which at least 40% of the conjugated diene units are hydrogenated with a peroxide. Oxidation-resistant rubber parts. (5) Acrylonitrile-conjugated diene copolymer rubber is
The oxidation-resistant rubber part according to claim 4, which is acrylonitrile-butadiene rubber (NBR). (6) The amount of peroxide blended is 2 to 8 parts by weight per 100 parts by weight of the rubber part.
Oxidation-resistant rubber parts as described in section. (7) The oxidation-resistant rubber component according to any one of claims 4 to 6, wherein the rubber component is one of a diaphragm, a seal bellow, and a hose used in a fuel system. (8) A pressure type ignition timing adjustment device characterized in that it uses at least one of a diaphragm and a seal bellows, which are made of a rubber material, wherein the rubber material has at least 40 conjugated diene units.
1. A pressure type ignition timing adjustment device comprising a rubber component mainly consisting of hydrogenated acrylonitrile-conjugated diene copolymer rubber, which is vulcanized with peroxide. (9) Acrylonitrile-conjugated diene copolymer rubber is
The pressure type ignition timing adjustment device according to claim 8, which is made of acrylonitrile-butadiene rubber (NBR). (10) The pressure type ignition timing adjustment device according to claim 8 or 9, wherein the amount of peroxide is 2 to 8 parts by weight per 100 parts by weight of the rubber part.