JPH0820702A - Acrylic rubber composition and its production - Google Patents

Abstract

PURPOSE:To obtain an acrylic rubber compsn. which does not stick to a metal and is produced at a low cost by mixing an uncross-linked acrylic rubber with a phosphorous acid substance and vulcanizing the resulting rubber compd. CONSTITUTION:This acrylic rubber compsn. is obtd. by mixing an uncross-linked acrylic rubber with a phosphorous and substance and vulcanizing the resultant rubber compd. Pref. 100 pts.wt. acrylic rubber is mixed with 4-20 pts.wt. phosphorous acid substance. An acrylic rubber was formerly liable to stick to a metal when in contact with it at a high temp. However, the compsn., when brought into contact with a metal, can form a phosphorus-based inert film chemically bonded to the surface of the metal. Since the film is inert, the compsn. does not stick to the metal even at a high temp. Moreover, the compsn. is produced at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acrylic rubber composition used as a material for parts in an oil filter, a distributor, etc. of an in-vehicle engine and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, NB has been used as a seal material for an oil filter of an in-vehicle engine and an O ring of a distributor.
A rubber part using R (acrylonitrile butadiene rubber) is used. However, since the NBR has low heat resistance, it has been considered to use acrylic rubber excellent in heat resistance, oil resistance, and mechanical strength instead.

By the way, the rubber and the metal may be fixed to each other by being in contact with each other for a long period of time, and finally it may be difficult to separate them. The progress of the adhesion is greatly affected by the surrounding environment where rubber and metal are present. For example, when the environment is a high temperature atmosphere and a large amount of oil is present, the adhesion of rubber and metal is likely to proceed.

Therefore, in the case of parts that need to be replaced regularly, or parts that are used as contact parts of various opening / closing mechanisms, if the above-mentioned sticking occurs, it becomes difficult to replace the parts, and the contact parts It causes a malfunction such as a malfunction. There are some cases where the above-mentioned adhesion is difficult to occur depending on the types of rubber and metal, and some are easy to occur. The acrylic rubber is particularly apt to adhere to iron-based metals.

Therefore, in order to prevent the above-mentioned problems due to the sticking, it has been proposed to provide a sticking preventive film such as silicone rubber on the surface of the rubber component (Japanese Patent Laid-Open No. 5-148).
476). In the production of the rubber part, the anti-sticking film is provided by post-treatment on the rubber part produced according to the usual method for producing a rubber composition. As an example of the above-mentioned post-treatment, a solution containing the components of the above coating is sprayed while rotating the component body. afterwards,
The above parts are fired to form a film. With the above coating,
It is possible to prevent the components in the rubber component from reacting with the metal surface and sticking to each other.

[0006]

However, in order to form the above-mentioned coating on a rubber part, it is necessary to mold the rubber part into a desired shape and then perform a coating forming step as a post-treatment.
Therefore, the manufacturing process of the rubber component is complicated and the manufacturing cost is increased.

In view of the above problems, the present invention is to provide an acrylic rubber composition having a metal adhesion preventing effect and a low manufacturing cost, and a method for manufacturing the same.

[0008]

The present invention relates to an acrylic rubber composition which is used in a state of being pressed against a metal material and at a high temperature, the acrylic rubber composition comprising acrylic rubber and a phosphorous acid-based substance. The acrylic rubber composition is characterized by containing.

The above acrylic rubber composition of the present invention is -3
It can be used in an environment of high temperature of 0 ° C to 160 ° C. Examples of parts used in the above environment include the vicinity of an automobile engine or the vicinity of its exhaust pipe. Further, the acrylic rubber composition can be used in various oils at high temperatures as described above.

Examples of such uses include a seal material for an oil filter in an engine and an O-ring for a distributor. Further, the acrylic rubber composition contains various additives such as a crosslinking agent, carbon black, and an antioxidant. Further, examples of the metal material include iron-based materials and aluminum alloys.

Next, the acrylic rubber composition of the present invention preferably contains 4 to 20 parts by weight of the phosphorous acid-based substance with respect to 100 parts by weight of the acrylic rubber. If the amount of the above phosphorous acid-based substance added is less than 4 parts by weight,
The effect of preventing sticking to metal, which is the effect of the present invention, may be small. On the other hand, when the amount added exceeds 20 parts by weight, the acrylic rubber composition will be
Vulcanization of the rubber component may be hindered and the physical properties of the acrylic rubber composition such as increased compression set and decreased hardness may be deteriorated.

As the phosphite-based substance, one or more selected from the group consisting of trisnonylphenyl phosphite, diphenylisooctyl phosphite and phenyldiisooctyl phosphite are used.

The acrylic rubber composition of the present invention is particularly effective for iron-based materials. In addition, among iron-based materials, it also exhibits an excellent anti-sticking effect on gray cast iron. The iron-based material is generally used as a material for parts around an automobile engine. Therefore, the acrylic rubber composition of the present invention can be used even in a portion that could not be conventionally used because of fixing to a metal material.

Next, when the above-mentioned acrylic rubber composition is used as a sealing material for an oil filter for filtering engine oil and is used in a state of being pressed against an iron-based material at high temperature, the acrylic rubber composition is Acrylic rubber 10
It is preferably composed of 0 parts by weight and 8 to 20 parts by weight of the phosphorous acid-based substance.

The seal material of the oil filter is a component which is arranged so as to come into contact with the engine block and which needs to be replaced regularly (see FIG. 1). Further, the sealing material is in a high temperature environment close to the engine and also directly contacts the engine oil. The engine block is made of cast iron. As a result, problems such as sticking to the engine block occur with conventional acrylic rubber, etc.
The above exchange was difficult. However, in the acrylic rubber composition of the present invention, the above sticking does not occur, and therefore the workability of replacing the oil filter is excellent. Therefore, the acrylic rubber composition is most suitable as a sealing material for oil filters.

If the amount of the phosphite-based substance added is less than 8 parts by weight, it is difficult to prevent the sealing material from sticking to the engine block in the presence of high-temperature engine oil. On the other hand, if the amount added exceeds 20 parts by weight, the vulcanization of the rubber component may be hindered during the production of the acrylic rubber composition described later, and the physical properties of the acrylic rubber composition may be deteriorated. The lower limit is preferably 10 parts by weight and the upper limit is 18 parts by weight.

Next, the method for producing the acrylic rubber composition is characterized in that an uncrosslinked acrylic rubber and a phosphorous acid-based substance are mixed to form a rubber component, and the rubber component is vulcanized. There is a method for producing an acrylic rubber composition. That is, a phosphorous acid-based substance is added to acrylic rubber and mixed thoroughly. At this time, the above-mentioned additives and the like are mixed in the same manner. Then, it is vulcanized in the same manner as an ordinary rubber product to obtain a rubber composition having elasticity.

This makes it possible to manufacture with the same manufacturing apparatus and process as other conventional rubber compositions. Further, unlike the conventional rubber having a sticking prevention effect, a post process such as a film forming process is not required. Therefore, it can be manufactured at a lower cost than conventional rubber.

Also in the above manufacturing method, the phosphorous acid-based substance is added in an amount of 4 to 20 relative to 100 parts by weight of the acrylic rubber.
It is preferably contained in an amount by weight. The phosphorous acid-based substance is preferably one or more selected from the group consisting of trisnonylphenylphosphite, diphenylisooctylphosphite, and phenyldiisooctylphosphite. As a result, the same effect as described above can be obtained.

[0020]

FUNCTION AND EFFECT The acrylic rubber composition of the present invention contains the acrylic rubber and the phosphorous acid-based substance. Then, as shown in the prior art, the acrylic rubber easily adheres to the metal with which it is in contact at high temperature. However, the acrylic rubber composition of the present invention can form a phosphorus-based inactive film chemically bonded to the metal surface of the other side by contacting the metal in the above environment. Since the coating is inert, it does not stick to metal even at high temperatures.

According to the production method of the present invention, the acrylic rubber composition is prepared by mixing the uncrosslinked acrylic rubber and the phosphorous acid substance to form a rubber component, and vulcanizing the rubber component. . As a result, it is possible to manufacture with the same manufacturing apparatus and process as a general rubber composition, and the post-process such as the above-mentioned film forming process is not necessary. Therefore, it can be manufactured at low cost.

As described above, according to the present invention, it is possible to provide an acrylic rubber composition having a metal adhesion preventing effect and a low manufacturing cost, and a manufacturing method thereof.

[0023]

【Example】

Example 1 An acrylic rubber composition of the present invention and a method for producing the same will be described. Further, the effect of preventing the acrylic rubber composition from sticking to the iron-based material will be described. That is, the acrylic rubber composition of this example is used in a state of being pressed against a metal material and at a high temperature, and contains an acrylic rubber and a phosphorous acid-based substance.

The above acrylic rubber composition is a chlorine-containing acrylic rubber (Japanese Synthetic Rubber AREX4
11) 100 parts by weight, stearic acid 1 part by weight, carbon black (ASTMN774) 100 parts by weight, diphenylamine-based antioxidant [4,4 ′-(α, α-dimethylbenzene) diphenylamine] 2 parts by weight, Two
It contains 0.8 parts by weight of 4,6-trimercapto-S-triazine, 2 parts by weight of zinc dibutyldicarbamate, and 10 parts by weight of the phosphorous acid-based substance [trisnonylphenylphosphite] according to the present invention.

Next, a method for producing the acrylic rubber will be described below. First, an acrylic rubber in a non-crosslinked state, a phosphorous acid-based substance and the above-mentioned additives are kneaded with a kneader and a roll to form a rubber component. Next, the rubber component is vulcanized. In the vulcanization, first, press vulcanization is performed at 180 ° C. for 20 minutes. Then, secondary vulcanization is performed at 175 ° C. for 4 hours. As a result, the acrylic rubber composition of this example is obtained.

Next, the performance of the acrylic rubber composition of this example will be described using Table 1. First, Samples 1 to 3 according to the examples of the present invention are acrylic rubber compositions containing the components described above. However, the sample 1 contains 10 parts by weight of the phosphorus-containing substance, the sample 2 contains 5 parts by weight, and the sample 3 contains 20 parts by weight. Further, in the comparative example, no phosphorous acid-based substance was added.

The performance of the acrylic rubber composition is evaluated by the adhesion strength measured by the following method and the presence or absence of rubber breakage during peeling. First, each of the above-mentioned samples 1 to 3 and the comparative example is made into a cylindrical molded product having an outer diameter of 29 mm and a height of 12.7 mm according to the manufacturing method described above. The samples 1 to 3 and the comparative example are sandwiched between soft iron (SPCC) plates having a thickness of 2 mm. Then, the samples 1-3 and the comparative example are compressed by 25% while being sandwiched between soft irons. Then, in the state where the samples 1 to 3 and the comparative example are compressed, the
Immerse under the condition of 100 ° C. for 100 hours.

Then, the sandwiched samples 1 to 3 and the comparative example were taken out, and the fixing force with the soft iron was attached to a tensile tester (Shimadzu: AGS-500), and the soft iron plate was moved up and down at a speed of 20 mm / min. Pull and measure the peeling load at that time.
At this time, it is also confirmed whether or not the rubber compositions of Samples 1 to 3 and Comparative Example were destroyed.

The results of the above measurements are shown in Table 1. As is known from the table, the fixing force between the samples 1 to 3 according to the present invention and the soft iron plate does not exceed 0.5 kgf at the maximum. Moreover, the rubber compositions of Samples 1 to 3 are not destroyed. However, in the above comparative example, the fixing force with the soft iron plate is 10 kgf or more. Further, the rubber composition of the comparative example is destroyed. That is, it can be seen that the comparative example strongly adheres to the soft iron plate.

In the present example, Samples 1 to 3 do not adhere to the soft iron plate due to the following action. Generally, an acrylic rubber composition decomposes at high temperature to generate an acidic compound (carboxylic acid, etc.). The above acidic compound reacts with soft iron,
Corrodes the soft iron. Therefore, the phosphite compound in the acrylic rubber easily reacts with the above metal and forms a protective film containing phosphoric acid on the soft iron surface. Therefore, this protective film prevents the acrylic rubber composition and soft iron from sticking to each other under high temperature and pressure contact.

As described above, Samples 1 to 3 according to the present invention
In all cases, unlike the comparative example, the rubber does not stick.
Therefore, it can be seen that the acrylic rubber composition containing the phosphorous acid-based material exhibits the effect of preventing sticking at high temperature and under pressure.

[0032]

[Table 1]

Example 2 In this example, as shown in FIG. 1, the acrylic rubber compositions of Sample 1 and Comparative Example in Example 1 were used as a sealing material 10 of an oil filter 1 for an automobile engine. The sealing material 10 is attached to the oil filter 1
Further, the loosening torque at the time of removal is measured, and the presence or absence of sticking to the engine block 30 described later is checked.

First, the structure of the oil filter 1 will be described. As shown in FIG. 1, the oil filter 1 includes a central cylinder portion 3 on the engine block 30 side made of cast iron.
A bottom plate 220 having a central discharge hole 22 that is screwed into 1;
Suction port 2 for sucking oil from the engine block 30 side
3, a rubber valve member 24 for preventing backflow of oil, and a filter portion 25 for cleaning oil.

The oil cleaned by the filter portion 25 is returned to the engine block 30 side through the inside of the central tubular portion 31 as shown by the arrow. And the sealing material 10
Is held by a claw portion 210 formed on the iron bottom surface portion 21 of the oil filter 1 and is in contact with the cast iron engine block 30.

Then, the seal material constituted by the sample 1 or the comparative example is attached to the oil filter 1, and the oil filter 1 is attached to the engine block 30 to obtain the engine oil under the condition of 140 ° C. and 500 hours. Soak. Further, the tightening torque when the oil filter 1 is attached is 200 kgf · cm. After immersion in the engine oil, the oil filter 1 is rotated in the opposite direction to that when it was attached, and removed from the engine block 30. At that time, measure the torque required to rotate with a pointing torque wrench. The loosening torque increases when the seal material 10 is fixed to the engine block 30. Of course, if the loosening torque is large, it becomes difficult to replace the sealing material 10.

Table 2 shows the above measurement results. As shown in the table, the sealing material made of the acrylic rubber composition of Sample 1 can be removed from the oil filter 1 by applying a loosening torque of 200 kgf · cm, which is the same as when tightening. However, a maximum of 400k in the comparative example
It cannot be removed without applying a loosening torque of gf · cm. Further, the acrylic rubber composition of Sample 1 did not adhere to the engine block, but it did occur in the comparative example.

Therefore, the sample according to this example has an effect of preventing sticking and can be used as a sealant for an oil filter. Further, since the sticking with the engine block does not occur, the sealing material can be replaced with a smaller force, and the workability of replacement is excellent.

[0039]

[Table 2]

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an oil filter according to a second embodiment.

[Explanation of symbols]

 1. . . Oil filter, 10. . . Sealing material, 30. . . Engine block,

Claims (8)

[Claims] 1. An acrylic rubber composition which is used in a state of being pressed against a metal material and at a high temperature, wherein the acrylic rubber composition contains an acrylic rubber and a phosphorous acid-based substance. An acrylic rubber composition characterized by: 2. The acrylic rubber 100 according to claim 1.
An acrylic rubber composition, wherein the phosphorous acid-based substance is contained in an amount of 4 to 20 parts by weight based on parts by weight. 3. The method according to claim 1, wherein
The acrylic rubber composition, wherein the phosphite-based substance is one or more selected from the group consisting of trisnonylphenylphosphite, diphenylisooctylphosphite, and phenyldiisooctylphosphite. 4. The method according to claim 1, wherein
The acrylic rubber composition, wherein the metal material is an iron-based material. 5. An acrylic rubber composition, which is used as a sealant for an oil filter for filtering engine oil and is pressure-contacted with an iron-based material at high temperature, the acrylic rubber composition comprising 100 parts by weight of acrylic rubber and Phosphoric acid type substance 8
An acrylic rubber composition, characterized in that the acrylic rubber composition comprises ˜20 parts by weight. 6. A method for producing an acrylic rubber composition, which comprises mixing an uncrosslinked acrylic rubber and a phosphorous acid-based substance to form a rubber component, and vulcanizing the rubber component. 7. The acrylic rubber 100 according to claim 6,
A method for producing an acrylic rubber composition, wherein the phosphorous acid-based substance is contained in an amount of 4 to 20 parts by weight based on parts by weight. 8. The method according to claim 6,
The acrylic rubber composition, wherein the phosphite-based substance is one or more selected from the group consisting of trisnonylphenylphosphite, diphenylisooctylphosphite, and phenyldiisooctylphosphite.