JPH06262728A - Cooling liquid transporting hose for vehicle - Google Patents

Abstract

PURPOSE:To provide a cooling liq. transporting hose wherein deterioration is prevented from being generated even in a vehicle wherein electric current is easily energized and having long term stable performance. CONSTITUTION:A monolayer hose 10 or at least innermost layer of a multilayer hose is formed with a rubber material wherein ethylene-propylene copolymer or a silicone-modified ethylene-propylene copolymer rubber is a main component and with a vol. inherent resistance of at least 10<4>OMEGAcm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle coolant hose used for connecting an engine and a radiator, connecting an engine and a heater core, and the like in various vehicles such as automobiles.

[0002]

BACKGROUND ART Conventionally, in various vehicles such as automobiles,
A coolant containing water as a main component, for example, a coolant in which ethylene glycol and a rust preventive are mixed (long life coolant = LLC) by connecting between the engine and the radiator or between the engine and the heater core. ) Is known to be used as a vehicle cooling liquid transportation hose for circulating a mixture thereof. As a material for forming this type of hose, an ethylene-propylene copolymer rubber having excellent water resistance such as EPDM is generally used. Further, usually, a filler such as carbon black, a softening agent such as process oil, a vulcanizing agent, a vulcanization accelerator and the like are added to the ethylene-propylene copolymer rubber, and they are obtained by kneading and processing them. The target cooling liquid transport hose is molded using the rubber material (blended composition).

By the way, in such a rubber material, when the amount of the filler such as carbon black or the softening agent such as the process oil added is small, the dimensional stability at the time of extrusion is deteriorated and the smooth extrusion is performed. This causes problems such as difficulty in obtaining skin and higher product cost. for that reason,
Conventionally, in order to avoid these problems, a means (high filling compounding) for preparing a rubber material by kneading a large amount of a filler such as carbon black has been adopted.

Thus, in recent years, while using a cooling liquid transportation hose for vehicles obtained by using such a highly filled rubber material, a large number of streaks (fine threads or dendrites) are formed on the inner surface side of the hose. It has been pointed out that, in a severe case, a crack may reach from the inner surface side to the outer surface side of the hose to cause leakage of the cooling liquid. Therefore, the present inventor has found that the following phenomenon has occurred as a result of a detailed study to clarify the cause.

That is, in recent vehicles such as automobiles, the mounting rate of electronic-related parts is increasing, and therefore, the environment is such that electricity easily flows to surrounding parts. in addition,
For the purpose of reducing the weight of the vehicle or improving the rust prevention performance, along with the conversion from iron material to aluminum material, the dissimilar metal contact may locally form the battery inside the vehicle, or At the portion where the metal material and the hose come into contact with each other, a battery is locally formed between the carbon black filled in the hose-forming rubber material and the metal material by using the cooling liquid as an electrolytic solution, and the current flow is increased. It creates an environment that is easy to occur.

On the other hand, as described above, the cooling liquid transport hose is made of a highly filled rubber material obtained by kneading a large amount of a filler such as carbon black with an ethylene-propylene copolymer rubber such as EPDM. Therefore, despite the extremely large volume resistivity of the ethylene-propylene copolymer rubber itself, the volume resistivity of the carbon black to be filled is small, the volume resistivity of the hose as a whole is low, It is a highly conductive hose.

In this way, since the cooling liquid transportation hose having high conductivity is arranged in the environment where electricity easily flows,
The hose will be energized during use. Then, due to this, on the inner surface side of the hose that comes into contact with the cooling liquid, an electrochemical reaction occurs between the hose and the cooling liquid, gradually causing deterioration of the hose, and streaks and cracks are generated from the inner surface side of the hose. As a result, the liquid will leak and liquid leakage will occur.

[0008]

The present invention has been made in view of such circumstances, and the problem to be solved is that electrochemical deterioration of a hose is effectively prevented even inside a vehicle in which a current easily flows. , To provide a vehicle coolant hose having stable performance for a long period of time.

[0009]

In order to solve such a problem, the present inventor conducted a detailed investigation on the relationship between the conductivity of the hose and the occurrence of streaks and cracks, and found that the volume resistivity of the hose was 10%.
It has been found that the occurrence of streaks and cracks can be effectively prevented by setting it to ⁴ Ωcm or more. Then, as a result of further studies based on such knowledge, the present invention was completed.

That is, the gist of the present invention is that
At least the innermost layer of the single-layer hose or the multi-layer hose is formed of a rubber material mainly composed of ethylene-propylene copolymer rubber and having a volume resistivity of 10 ⁴ Ωcm or more. Located in the vehicle coolant hose.

In the present invention, at least the innermost layer of the single-layer hose or the multi-layer hose is made of a rubber material mainly composed of a silicone-modified ethylene-propylene copolymer and having a volume resistivity of 10 ⁴ Ωcm or more. A vehicle cooling liquid transportation hose characterized by being formed as described above is also the subject of the invention.

Furthermore, in the present invention, it is advantageous that the innermost layer of the multi-layer hose is made of silicone-modified ethylene-
The volume resistivity of the propylene copolymer is 10
It is formed of a rubber material having a resistance of ⁴ Ωcm or more, and the layer in contact with the innermost layer is formed of a peroxide vulcanizate of ethylene-propylene copolymer rubber. .

[0013]

In summary, according to the present invention, the conductivity of the hose can be improved by increasing the volume resistivity of the hose inner surface side of the vehicle cooling liquid transport hose, which is in contact with at least the cooling liquid, to 10 ⁴ Ωcm or more. It improved effectively. As a result, in the vehicle cooling liquid transport hose according to the present invention, even when placed in an environment where current is likely to occur,
It is difficult for electricity to flow, and the electrochemical reaction between the hose and the cooling liquid on the inner surface side of the hose can be effectively prevented. Therefore, it is possible to advantageously solve the problems such as the generation of streaks and cracks caused by such a phenomenon, and further the problem of liquid leakage, and to exert stable performance for a long time even in the inside of a vehicle where current easily flows. Is possible.

Further, when the vehicle cooling liquid transportation hose according to the present invention is made of a rubber material mainly composed of a silicone-modified ethylene-propylene copolymer, it does not need to be highly filled with carbon black and is good. Since various hose physical properties and workability can be obtained, there is an advantage that the reduction of volume resistivity can be effectively prevented, and more advantageously, the conductivity of the hose can be improved.

And, such silicone-modified ethylene-
Since a rubber material mainly composed of a propylene copolymer is usually subjected to peroxide vulcanization, when forming an innermost layer of a multi-layer hose with the rubber material, a layer in contact with the innermost layer is used. , An ethylene-propylene-based copolymer rubber is used as a peroxide vulcanizate, and a configuration in which the vulcanization form and vulcanization conditions of both layers are matched is advantageously adopted. The adhesiveness can be effectively enhanced.

[0016]

Concrete Structure By the way, the vehicle cooling liquid transport hose according to the present invention may have either a single-layer structure or a multi-layer structure.
At least the inner surface of the hose has a volume resistivity of 1
It is made of a rubber material of 0 ⁴ Ωcm or more. Further, such a rubber material will be prepared mainly from an ethylene-propylene copolymer rubber having good water resistance, but usually carbon black or the like is used so that the moldability at the time of molding into a hose shape is enhanced. The filler and the softening agent such as process oil are kneaded in a large amount to prepare a highly filled rubber material (blended composition).

EPDM, EPM and the like are used as the ethylene-propylene copolymer rubber, and generally, the volume resistivity thereof is 10 ¹⁴ to 10 ¹⁶ Ωcm,
As such, it is difficult to conduct electricity. However, the carbon black filled therein has a volume resistivity of 10
^{Since the} rubber material (compounding composition) obtained by kneading both is very small, around ^-1 to 10 ¹ Ωcm, the volume resistivity decreases with an increase in the compounding amount of carbon black, and is about 10 ¹ to 10 ¹ Ωcm. It changes within the range of 10 ¹⁴ Ωcm.

Therefore, in the present invention, a rubber material having a volume resistivity of 10 ⁴ Ωcm or more is selected among the rubber materials mainly composed of ethylene-propylene copolymer rubber. In order to control the volume resistivity of the rubber material to 10 ⁴ Ωcm or more, the ratio (%) of the carbon black compounding amount (weight part) to the total rubber compounding amount (weight part).
It is effective to control.

Further, a softening agent such as a process oil, a vulcanizing agent, a vulcanization accelerator, etc. are usually added to such a rubber material. These softening agents, vulcanizing agents, vulcanization accelerators, etc. The amount of such a compound does not significantly affect the volume resistivity of the rubber material.

If necessary, a non-conductive white filler such as clay, talc, silica, etc. may be added to the rubber material. However, when the white filler is added, the ratio of the ethylene-propylene copolymer rubber in the rubber material decreases, and the volume resistivity of the rubber material decreases, so that the volume resistivity of the rubber material is reduced to 10%. ^When operating above ⁴ Ωcm, it is recommended to control the blending ratio of carbon black as compared with the case where no white filler is added.

On the other hand, in addition to the rubber material as described above, in the present invention, a rubber material mainly composed of a silicone-modified ethylene-propylene copolymer is advantageous as the rubber material having a volume resistivity of 10 ⁴ Ωcm or more. Will be used for. That is, when a silicone-modified ethylene-propylene copolymer is used, good hose physical properties and workability can be obtained without adding a large amount of carbon black. It can be effectively prevented and more advantageously the conductivity of the hose can be improved. If necessary, the rubber material may also be blended with a softening agent such as the above-mentioned process oil or a white filler such as clay, talc or silica.

Thus, a rubber material containing ethylene-propylene copolymer rubber as a main component and having a volume resistivity of 10 ⁴ Ωcm or more is prepared. Using this rubber material, a vehicle cooling liquid transportation hose is prepared. Will be formed.

In this case, the most basic structure of the vehicle cooling liquid transport hose according to the present invention is a single-layer hose 10 as shown in FIG. 1, in which case the entire hose is made of the rubber material according to the present invention. To do. On the other hand, as a specific example of the multi-layer hose, as shown in FIG. 3, an inner layer 16 is formed of a rubber material according to the present invention, and a normal EPDM is formed on the inner layer 16.
Multi-layer hose 1 in which the outer layer 18 is formed using a rubber material such as
4 in this way, in the case of a multi-layer hose, at least the innermost layer is formed of the rubber material according to the present invention.

Further, as the multi-layer hose 14 having the reinforcing thread layer 12 therein, as shown in FIG. 2, an inner layer 16 located inside the reinforcing thread layer 12 and an outer layer 18 located outside the reinforcing thread layer 12 are provided. All of them are made of the rubber material according to the present invention. Further, as shown in FIG. 4, the inner layer 16 is formed of the rubber material according to the present invention, and the reinforcing yarn layer 1 is formed on the inner layer 16.
2 is provided, and the outer layer 18 is formed on the outer layer 18 by using a normal rubber material such as EPDM. Furthermore, as shown in FIG. 5, the inner layer 16 and the reinforcing thread layer 12 of the multilayer hose 14 shown in FIG.
And an intermediate layer 17 made of a usual rubber material such as EPDM.

Thus, for example, in the multi-layer hose 14 shown in FIG. 3, the inner layer 16 is formed of a rubber material mainly composed of the silicone-modified ethylene-propylene copolymer according to the present invention, and the outer layer 18 is formed of ordinary EPDM or the like. When formed using a rubber material, the inner layer 16 is peroxide vulcanized,
The outer layer 18 becomes sulfur vulcanized, and the vulcanization form and vulcanization conditions of both layers are different, so that the adhesion between both layers may be insufficient. Therefore, in such a case, it is desirable that the layer in contact with the inner layer 16 is formed of a peroxide vulcanizate of an ethylene-propylene copolymer rubber under the same vulcanization mode and vulcanization conditions. For example, as shown in FIG. 6, the inner layer 1 of the hose
6 and the outer layer 18, an intermediate layer 17 is provided, and the intermediate layer 17
Is formed of a peroxide-vulcanized ethylene-propylene copolymer. In addition, in such a hose, as shown in FIG.
As described above, the reinforcing yarn layer 12 is provided between the intermediate layer 17 and the outer layer 18.
May be provided.

In addition to the above, various hose structures can be appropriately adopted without departing from the gist of the present invention, and such various hose layer configurations are appropriately selected according to the application. Therefore, it is possible to obtain a predetermined effect associated with each layer configuration.

In any hose structure, the layers (10, 16) formed of the rubber material according to the present invention have a thickness of 0.3 mm or more in order to advantageously improve the durability of the hose to electricity. , Preferably 0.5 mm or more. However, when a rubber material mainly composed of a silicone-modified ethylene-propylene copolymer is used among the rubber materials according to the present invention, since the volume specific resistance is high, the thickness of these layers (10, 16) is set to 0. The thickness can be set to 05 mm or more, preferably 0.3 mm or more.

As the reinforcing yarn layer 12, those used for ordinary rubber hoses are employed as they are. For example, by using braid knitting or spiral knitting of yarn mainly composed of synthetic fibers such as polyester fiber and aramid fiber. It is formed. Further, as the material for forming the outer layer 18 and the intermediate layer 17, it is preferable to use a material having excellent weather resistance, heat resistance, water resistance, etc., for example, a usual rubber material such as EPDM or EPM is preferably used. It will be. However, as described above, depending on the vulcanization mode of the inner layer 16 and the vulcanization conditions, the material for forming the intermediate layer 17 and the outer layer 18 may be a sulfur vulcanizate or a peroxide, depending on the adhesiveness to the inner layer 16. The vulcanized product will be appropriately selected and used.

The vehicle cooling liquid transportation hose according to the present invention can be manufactured by various conventionally known methods. For example, the multi-layer hose 14 shown in FIG.
Can be manufactured by sequentially stacking as follows.

(A) First, an extruder is used to form a rubber material according to the present invention for forming an inner layer (for example, a rubber material mainly composed of ethylene-propylene copolymer rubber and having a volume resistivity of 10 ⁴ Ωcm or more). It is further extruded to form a tubular body.

(B) Next, an adhesive (rubber glue) is applied to the outer peripheral surface of the inner layer 16 if necessary, and then the reinforcing yarn layer 12 is formed by a technique such as braiding or spiral knitting the fiber reinforcing yarn. Form.

(C) After applying a predetermined adhesive (rubber glue or the like) to the outer peripheral surface of the reinforcing yarn layer 12 thus formed, a rubber material for forming an outer layer is extruded thereon,
The target outer layer 18 is formed to a predetermined thickness.

(D) The laminated tube thus obtained can be vulcanized (crosslinked) and integrated to obtain a desired hose. As vulcanization conditions at this time, a temperature of about 140 to 170 ° C. and a vulcanization time of about 20 to 90 minutes are usually adopted.

The inner layer 16 can be formed not only by extrusion, but also by applying the rubber material according to the present invention to a rubber paste and applying it to the inner surface of the hose. Further, as in the conventional case, it is naturally possible to perform bending pipe forming processing such as inserting a hose into a metal mandrel at the time of vulcanization.

[0035]

EXAMPLES Some examples of the present invention will be shown below to clarify the present invention in more detail. However, the present invention is not limited by the description of such examples. Needless to say, it is not something to receive. Further, in addition to the following specific examples, in addition to the following embodiments, the present invention includes various modifications based on the knowledge of those skilled in the art without departing from the spirit of the present invention.
It should be understood that modifications, improvements, etc. may be made.

Examples 1 to 11 and Comparative Examples 1 to 7 First, each material was weighed out according to each composition shown in Table 1, Table 2 and Table 3 below, and Zn was used for each composition.
O: 5 parts by weight, stearic acid: 1 part by weight, vulcanizing agent / vulcanization accelerator: 5 parts by weight were added and kneaded to prepare various rubber materials. Then, using each rubber material, according to a known method, the structure (hose structure A) as shown in FIG.
Hose (inner diameter: 30 mm, thickness: 5.5 mm, reinforcing thread layer:
Polyester fiber, 3 fibers × 24 strokes) were produced. Also,
For Examples 2 and 3 and Comparative Examples 1 and 2, a hose (inner diameter: 30 mm, thickness: 5.5 mm) having a structure (hose structure B) as shown in FIG. 1 was also manufactured.

Next, each hose was attached to an evaluation tester as shown in FIG. 9 and a durability test against electricity (bravolizer test) was carried out. In addition, as a test condition, water / long life coolant (LLC) = 5 in the hose.
The cooling liquid adjusted to 0/50 was filled to 75% of the internal volume, a DC voltage of 12 V was applied between both ends of the tester, and the mixture was allowed to stand in an atmosphere of 100 ° C. for 336 hours. After that, the hose was removed from the tester, the cross section of the hose was observed and evaluated, and the evaluation results are also shown in Table 1 below.
Shown in 3.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

[Table 3]

As is clear from the above results, also for the rubber materials containing only carbon black as the filler (Examples 1 to 4 and Comparative Examples 1 to 3), the carbon black and the white filler (the clay) were used as the fillers. , Talc, silica)
A rubber material containing (Examples 5 to 11, Comparative Examples 4 to 7)
As for the rubber material, no abnormality was observed in the rubber material having a volume resistivity of 10 ⁴ Ωcm or more. But 10
^With rubber materials having a volume resistivity of less than ⁴ Ωcm, streaks and cracks were formed on the hose, and some coolant leaked out. Further, in the examples and comparative examples, the volume resistivity of the rubber material changes with the blending ratio of carbon black, but the blending ratio of the softening agent has a great influence on the volume resistivity of the rubber material. There wasn't.

Further, similar results were obtained for a hose having a structure in which no reinforcing thread layer is formed (structure B). Therefore, it is necessary to set the volume specific resistance of the hose to 10 ⁴ Ωcm or more. It was found that the hose deterioration due to energization can be prevented regardless of the above.

Incidentally, in order to clearly show the degree of the adverse effect that occurs when the volume resistivity is reduced, FIG. 8 shows the relationship between the carbon black compounding amount in the rubber materials used in all Examples and Comparative Examples and the volume resistivity. Are indicated by the following symbols. ○: Only carbon black, no abnormality ●: 〃, streak or crack generation △: Carbon black + white filler, no abnormality ▲: 〃, streak or crack generation

Examples 12 to 16 and Comparative Examples 8 to 12 First, three types of rubber materials were prepared according to the following composition. Then, various hoses having the hose structures shown in Table 4 below were produced using each rubber material according to a known method. The reinforcing yarn layer was formed by braiding rayon yarn with a blade.

Thereafter, each of the obtained hoses was subjected to a durability test against electricity (bravolizer test) in the same manner as in Example 1, and the evaluation results are also shown in Table 4 below. Further, each hose was subjected to a peeling test in order to examine the adhesiveness between the inner layer and the layer in contact with it, and the results are also shown in Table 4 below.

Sulfur Vulcanized EPDM (phr) EPDM 100 Carbon Black 100 Softening Agent 40 ZnO 5 Sulfur-Based Vulcanizing Agent / Vulcanization Accelerator 5

Peroxide Vulcanization EPDM (phr) EPDM 100 Carbon Black 100 Softening Agent 40 ZnO 5 Peroxide Vulcanizing Agent / Vulcanizing Aid 10

Q-EPDM (phr) Silicone-modified EPDM 100 White filler 15 Softening agent 5 Peroxide vulcanizing agent 5

[0049]

[Table 4]

As is clear from the results of Table 4, in Examples 12 to 16, the volume resistivity of the inner layer was 1 in all cases.
On the basis of 0 ¹⁰ Ωcm or more, hose deterioration was satisfactorily prevented and no abnormality was observed. In addition, since the vulcanization mode and the vulcanization conditions are matched between the inner layer and the layer in contact with it, the adhesiveness between these two layers is good, no interfacial peeling occurs in the peeling test, and rubber breakage occurs. occured.

On the other hand, in Comparative Examples 10 to 12, since the volume resistivity of the inner layer was less than 10 ⁴ Ωcm,
Streaks and cracks were formed in the hose, and in Comparative Example 12, the cooling liquid leached from the center of the hose after 24 hours in the atmosphere of 100 ° C. Further, in Comparative Examples 8 and 9, since the inner layer and the layer in contact with the inner layer had different vulcanization forms and vulcanization conditions, the adhesion between the two layers was low, and peeling occurred at the interface in the peeling test.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a vehicle cooling liquid transport hose according to the present invention.

FIG. 2 is a cross-sectional view showing another example of the vehicle cooling liquid transport hose according to the present invention.

FIG. 3 is a cross-sectional view showing still another example of the vehicle coolant hose according to the present invention.

FIG. 4 is a cross-sectional view showing still another example of the vehicle cooling liquid transport hose according to the present invention.

FIG. 5 is a cross-sectional view showing still another example of the vehicle cooling liquid transport hose according to the present invention.

FIG. 6 is a cross-sectional view showing still another example of the vehicle cooling liquid transport hose according to the present invention.

FIG. 7 is a cross-sectional view showing still another example of the vehicle cooling liquid transport hose according to the present invention.

FIG. 8 is a graph showing the relationship between the ratio of the amount of carbon black of each rubber material forming the hoses of Examples and Comparative Examples and the volume resistivity.

FIG. 9 is an explanatory diagram showing a configuration of an evaluation tester used in Examples and Comparative Examples.

[Explanation of symbols]

 10 Single-layer hose 12 Reinforcing yarn layer 14 Multi-layer hose 16 Inner layer 18 Outer layer 17 Intermediate layer

Claims (3)

[Claims] 1. A single-layer hose or at least an innermost layer of a multi-layer hose is formed of a rubber material mainly composed of an ethylene-propylene copolymer rubber and having a volume resistivity of 10 ⁴ Ωcm or more. A cooling liquid transportation hose for a vehicle, characterized in that 2. A single-layer hose or at least the innermost layer of a multi-layer hose is mainly composed of a silicone-modified ethylene-propylene copolymer and has a volume resistivity of 10 ⁴ Ω.
A vehicle coolant hose characterized by being formed of a rubber material having a size of at least cm. 3. The innermost layer of the multi-layer hose is formed of a rubber material mainly composed of a silicone-modified ethylene-propylene copolymer and having a volume resistivity of 10 ⁴ Ωcm or more, and is in contact with the innermost layer. A vehicle-cooling liquid transportation hose, wherein the layer is formed of a peroxide vulcanized product of ethylene-propylene copolymer rubber.