KR101793673B1 - Accumulator diaphragm - Google Patents

Abstract

The present invention relates to a diaphragm for an accumulator, and more specifically, relates to a diaphragm for an accumulator which keeps properties stable and has a gas penetration rate of 150[cm^3/(m^224hatm)] or lower. According to the present invention, the diaphragm comprises a rubber composition mixed with reinforcing fiber. The rubber composition, for 100 phr of raw material rubber, which is one of nitrile butadiene rubber, fluorine rubber, ethylene propylene rubber, chloroprene rubber, and silicon rubber, comprises: 1-3 phr of reinforcing fiber; 0.2-0.8 phr of quartz powder; 0.2-2.5 phr of white carbon; 15-40 phr of carbon black; 0.5-2 phr of stearic acid; 1-5 phr of vulcanizing agent; and 3-10 phr of vulcanization accelerator. The reinforcing fiber is para-based aramid filament which is 1 mm long. The diaphragm is made by injection molding of the rubber composition. When the raw material rubber is nitrile butadiene rubber, the gas penetration rate is 148[cm^3/(m^224hatm)].

Description

Accumulator diaphragm < RTI ID = 0.0 >

The present invention relates to a diaphragm for an accumulator, more particularly, to a diaphragm for an accumulator having a gas permeability of not more than 150 [cm 3 / (m 2 · 24 h · atm)] as well as keeping the property stably.

In general, Accumulator is an important part used for construction of heavy equipment and ship such as construction site. It is also used as important part of heavy equipment and ship, but it is an important technical part used in various industries such as aircraft and automobile.

Such an accumulator has a very wide range of applications, which is indispensable in the use of hydraulic equipment and the like, for example, application of energy axis, absorption of impact pressure, and removal of pump pulsation.

FIG. 1 shows a type of an accumulator. FIG. 1 (a) shows a bladder type, FIG. 1 (b) shows a diaphragm type and FIG. 1 (c) shows a piston type. As shown in FIG. 1, the accumulator is divided into a bladder type, a diaphragm type, and a piston type.

Especially, although diaphragm type is an accumulator used in various industrial fields such as heavy equipment, recently, there are many defects and problems in use.

As a result of analyzing the problem, although the diaphragm used for the accumulator is a component that controls the core function of the accumulator, it is a product used at high pressure and can not withstand repetitive motion under high pressure condition, It was found that there was a problem that frequent leakage occurred.

In other words, the diaphragm used for the accumulator is a key part of the gas shutoff of the accumulator, but in the environment of the bad condition that the force of 300 bar is applied, the diaphragm is subjected to great fatigue due to the repeated motion, The life of the diaphragm is shortened and the diaphragm is torn and broken, resulting in a problem of paralyzing the function of the accumulator.

Fig. 2 is a view showing crack / breakage occurrence of a conventional diaphragm. 2- (a) shows a photograph in which a crack occurred in the side surface and the upper end portion of the diaphragm mounted on the accumulator, and an accident that the nitrogen gas leaks occurred. FIG. 2- (b) In the state of being destroyed due to the failure to follow.

As shown in FIG. 2, due to various operational problems, the replacement period of the product is short, and the customer's dissatisfaction is growing.

Despite these complaints, the domestic rubber makers are small or lack technical ability, and the diaphragm used in the accumulator now relies heavily on imported products such as Fujikura and Colombia.

Therefore, it is necessary to study the development of a diaphragm having an optimal gas permeability as well as maintaining a life of more than twice as high as that of a conventional product under a high pressure condition.

Korean Registered Patent No. 10-1082308, November 3, 2011 Registered as a person.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a diaphragm for an accumulator having a gas permeability of 150 [cm 3 / (m 2 24 h · atm) have.

According to an aspect of the present invention, there is provided a diaphragm comprising a rubber composition in which reinforcing fibers are mixed, wherein the rubber composition is a diaphragm comprising at least one of nitrile butadiene rubber, fluorine rubber, ethylene propylene rubber, chloroprene rubber, 1 to 3 phr of reinforcing fibers, 0.2 to 0.8 phr of quartz powder, 0.2 to 2.5 phr of white carbon, 15 to 40 phr of carbon black, 0.5 to 2 phr of stearic acid, 1 to 5 phr of vulcanization and 3 to 10 phr of vulcanization accelerator per 100 phr of rubber Wherein the reinforcing fiber is a para-aramid short fiber having a length of 1 mm, and the diaphragm is injection molded through the injection mold, and when the raw rubber is nitrile butadiene rubber, the gas permeability is (M < 2 > / 24 h. Atm) of 148 cm < 3 >.

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Preferably, the rubber composition is supplied to the injection mold preheated to 140 DEG C at a flow rate of 5.51 cm < 3 > / s under a pressure of up to 958 bar, and is injection-molded for 120 seconds.

Preferably, the silicone rubber is at least one of HCR (Heat Cure Rubber), LSR (Liquid Silicone Rubber) and MMR (Mold Marking Rubber).

According to the present invention, by solving the above-mentioned problems, it is possible to manufacture an accumulator diaphragm having improved durability by more than twice the lifetime of the existing 5000 cycle by improving the adhesion between the raw rubber and the reinforcing fiber. By designing the die with an injection mold, And also has an effect of reducing the defective rate.

As a result, the limited use of the accumulator diaphragm is expanded to create a new value added, and it is applicable to heavy equipment and has the effect of entering the automobile market.

1 shows a kind of an accumulator.
Fig. 2 is a diagram showing crack / breakage occurrence of a conventional diaphragm. Fig.
Figure 3 is a diaphragm according to a preferred embodiment of the present invention.
Figure 4 is a side view of Figure 3;
5 is a schematic view of a mold;
6 is a process for filling a rubber composition according to a preferred embodiment of the present invention.
7 is a process for filling a rubber composition according to a preferred embodiment of the present invention.
8 is a view showing a process of mixing raw rubber and reinforcing fiber according to a preferred embodiment of the present invention.
9 is an oil resistance test graph according to a preferred embodiment of the present invention.
10 is a graph of the environmental evaluation result according to the preferred embodiment of the present invention.
11 is a photograph of Fig. 10- (a).
12 to 26 are graphs of gas permeability test reports according to a preferred embodiment of the present invention.

Prior to describing the present invention, a diaphragm refers to a dynamic seal that transmits power without loss to hydraulic pressure or pneumatic pressure in a cylinder, a regulator, or the like.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 is a diaphragm according to a preferred embodiment of the present invention. FIG. 3- (a) is a plan view of the diaphragm viewed from above, and FIG. 3- (b) is a bottom view of the diaphragm viewed from the bottom.

Figure 4 is a side view of Figure 3; Referring to FIG. 4, it can be seen that the side view of the diaphragm according to FIG. 3 is shown.

3 and 4, the present invention is a diaphragm comprising a rubber composition in which reinforcing fibers are mixed, wherein the rubber composition is at least one of nitrile butadiene rubber, fluorine rubber, ethylene propylene rubber, chloroprene rubber and silicone rubber (More preferably 0.5 phr) of quartz powder, 0.2 to 2.5 phr of quartz powder (more preferably 0.5 phr), 1 to 3 phr of quartz powder (more preferably 0.5 phr), 1 to 3 phr of quartz powder (more preferably 0.5 phr) More preferably 15 to 40 phr (more preferably 40 phr) of carbon black, 0.5 to 2 phr (more preferably 1 phr) of stearic acid, 1 to 5 phr of vulcanization (more preferably 1.5 phr) and 3 to 10 phr of vulcanization accelerator 5.7 phr). The diaphragm is injection molded through an injection mold. When the raw material rubber is nitrile butadiene rubber, the diaphragm has a gas permeability of 150 [cm 3 / (m 2 · 24 h · atm)] or less It can be said that the diaphragm for the cumulator is characterized.

First, an injection mold will be described.

5 is a view showing the shape of a mold. 5- (a) shows a compression mold, Fig. 5- (b) shows a transfer mold, and Fig. 5- (c) shows an injection mold applied to the present invention.

5- (a), the most commonly used compression mold is a mold which is easy to mold and can be manually operated, and has a structure applied when producing a starting mold or a small amount of product. Such a compression mold is a method of automatically or manually operating a press by opening an upper mold and injecting an appropriate amount of raw material.

However, the compression mold has a disadvantage that it is applied only when the burr amount does not affect the function of the product because the thickness of the burr depends on the amount of the material and the burr operation is difficult.

As such, it is difficult to apply the present invention to the production of a diaphragm for an accumulator which can improve the quality and price competitiveness and increase the productivity, since the compression mold of the conventional method does not work well and the defect rate increases and the productivity is also poor. .

The transfer mold shown in FIG. 5- (b) is a product which is easy to produce a product having complicated shape or difficult to work in a compression mold, and is formed by closing the upper and lower molds of the mold, And the rubber product is molded by the force that the mold is closed by injecting the rubber.

Although such a transfer mold has a better condition than a compression mold and can work on complicated shapes that are difficult to work on a compression mold, there is a disadvantage in that it is difficult to reduce the manufacturing cost and takes a long time, It is difficult to manufacture a diaphragm for an accumulator.

In order to overcome the above-mentioned problems, it is necessary to develop a diaphragm with an injection mold as shown in Fig. 5- (c), which requires an appropriate rubber composition for the flow and molding of the rubber.

That is, the conventional diaphragm for an accumulator can not be manufactured by using an injection mold. In the present invention, a diaphragm having excellent physical properties can be manufactured by injecting a rubber composition suitable for flow of rubber and molding into an injection mold. The description of such a rubber composition will be described later.

Injection mold is applied when the quantity of production is more than a certain amount. It is possible to shorten the molding time because the material is preheated before it is put into the mold, and it has a proper mixing effect when passing through the injection machine screw. A diaphragm can be obtained.

Here, the description of the rubber molding analysis of the accumulator diaphragm using the injection mold will be described.

First, the rubber composition is supplied to an injection mold preheated to 140 DEG C at a flow rate of 5.51 cm < 3 > / s under a pressure of up to 958 bar and injection-molded for 120 seconds. During the injection time of 120 seconds at a temperature of 50 占 폚, the vulcanization time is set until the degree of cure reaches 98%, and under these conditions, the rubber composition is injected into the injection mold at a flow rate of 5.51 cm3 / s under a pressure of up to 958 bar.

The filling of the rubber composition is then started when the injection time is 3.6 seconds, at which time the pressure is 730 bar. However, the outer area is the final charging area.

FIG. 6 is a view illustrating a process of filling a rubber composition into an injection mold according to a preferred embodiment of the present invention, which is viewed from above the diaphragm. FIG. 7 shows a process of filling a rubber composition into an injection mold according to a preferred embodiment of the present invention, which is a view from below the diaphragm.

6 and 7 show the Flow Pattern Result. As shown in FIGS. 6 and 7, the rubber composition is filled at 3% at 3.6 seconds, 11% at 13 seconds, 20.83% at 25 seconds , 30.64% charged at 36.77 seconds, 50% charged at 60 seconds, 70% charged at 84 seconds, 90% charged at 108 seconds, and 98% charged at 118 seconds.

As shown in FIGS. 6 and 7, it can be seen that the thin region in the diaphragm is charged to a temperature of 120 ° C or more after 20 seconds.

As a result, the rubber composition is injected into the injection mold at an injection pressure of 958 bar under a maximum injection pressure of 951 bar and the vulcanization time is 938 seconds. However, if the injection mold temperature is increased, the vulcanization time is reduced .

However, the blue region represents the initial injection temperature of the rubber composition of 50 占 폚, and the red region represents 140 占 폚 which is the same as the injection mold temperature.

Next, the rubber composition will be described.

That is, the rubber composition serves as a material for manufacturing the diaphragm for the accumulator. It enhances the durability of the diaphragm by improving the adhesion between the rubber and the fibers by dispersing and mixing the reinforcing fibers in the raw rubber to improve the gas permeability to 150 [ ㆍ 24h ㆍ atm)].

FIG. 8 is a process of mixing raw rubber and reinforcing fiber according to a preferred embodiment of the present invention. As shown in FIG. 8, it can be seen that the raw rubber of the present invention and the reinforcing fiber are mixed.

8 shows an example in which silicone rubber is used as a raw material rubber. After raw rubber raw material is subjected to ROLL, para-aramid short fibers, which are reinforcing fibers, are mixed by 1 mm, 3 mm, and 6 mm, respectively, And the process of testing the gas permeability and the like for each sample after preparation of the sample is briefly described.

In the present invention, the most suitable polymer was selected based on the price, physical properties, requirements of the customer, and developed as a base polymer. By examining the characteristics of each polymer, the compound having the best properties was repeatedly tested Of the compound.

That is, the rubber composition is prepared by mixing 1 to 3 phr of reinforcing fibers per 100 phr of raw rubber which is at least one of nitrile butadiene rubber (NBR), fluorine rubber (FKM), ethylene propylene rubber (EPDM), chloroprene rubber (CR) , 0.2 to 0.8 phr of quartz powder, 0.2 to 2.5 phr of white carbon, 15 to 40 phr of carbon black, 0.5 to 2 phr of stearic acid, 1 to 5 phr of vulcanization and 3 to 10 phr of vulcanization accelerator.

(1) Nitrile butadiene rubber (NBR) is not only cost effective but also low cost. Diaphragm mixed with para-aramid short fibers having a length of 1 mm has a gas permeability of 150 [cm 3 / (M < 2 > 24h. Atm)]. As a result, the gas such as nitrogen is most effectively blocked.

In particular, it was confirmed that the oil resistance was improved as the content of AN (-C≡N) having a cyanating group in the nitrile-butadiene rubber was larger.

That is, the oil resistance can be determined by examining the degree of the phenomenon in which the physical properties are weakened by immersing the rubber composition containing nitrile butadiene rubber containing 10% of AN (-C≡N) in oil, It can be based on measuring tensile strength, elongation, and volume change rate measured after impregnation with ASTM Oil NO.3 for 70 hours at 70 ℃.

9 is a graph showing an oil resistance test according to a preferred embodiment of the present invention. As shown in FIG. 9, the oil resistance test showed that the tensile strength was -1%, the elongation was -7%, and the volume change rate was 23%.

In addition, diaphragm with nitrile butadiene rubber as raw material rubber maintains stable property even at high temperature and low temperature.

10 is a graph of the environmental evaluation result according to the preferred embodiment of the present invention.

FIG. 10- (a) is a graph showing the result of allowing the diaphragm to stand for 96 hours under an environmental condition of about 80 ° C., which shows that the shape of the diaphragm does not change and the reliability of the product can be secured.

FIG. 10- (b) is a graph showing the result of allowing the diaphragm to stand for 48 hours under an environment of about -20 ° C., which shows that the shape of the diaphragm does not change and the reliability of the product can be secured.

Fig. 10- (c) is a graph showing the results of a temperature cycle test from about -20 ° C to about 80 ° C for 133 hours. As in the previous two cases, the shape of the diaphragm does not change, Can be obtained.

11 is a photograph of Fig. 10- (a). Fig. 11- (a) is a photograph showing the diaphragm before the high-temperature storage at about 80 ° C, and Fig. 11- (b) is a photograph showing the diaphragm after leaving the high temperature at about 80 ° C. As can be seen from FIG. 11, even if the diaphragm is left at a high temperature, no deformation occurs and the physical properties are stably maintained.

(2) Fluorine rubber (FKM, Fluorinated rubber) is excellent in heat resistance to such an extent that it can be used at a high temperature of 300 to 350 ° C.

(3) Ethylene propylene rubber (EPDM) is excellent in chemical resistance, ozone resistance, weather resistance, heat aging resistance and cold resistance (low temperature characteristics).

(4) Polychloroprene rubber (CR) is excellent in adhesion, oil resistance and flame retardancy. It can be selectively used among sulfur-modified (G type), non-sulfur modified type (W type) and highly crystalline type.

(5) The silicone rubber (SL, Silicone Rubber) is characterized by having heat resistance at 300 ° C and low temperature resistance at -95 ° C. It also uses HCR (Heat Cure Rubber), LSR (Liquid Silicone Rubber) And MMR (Mold Marking Rubber) may be selectively used.

(6) The reinforcing fiber is intended to satisfy a target gas permeability value by minimizing a gap to be maximized for enhancing the tensile strength between the rubber and the rubber. The reinforcing fiber will be described in more detail later, A description thereof will be omitted.

(7) The quartz powder (MinUsil) is formed into a fine particulate form and dispersed and filled in the rubber composition, thereby enhancing the gas barrier effect and achieving the gas permeability value.

That is to say, the quartz powder has a size of 0.1 to 3 탆, and SiO ₂ If the content is less than 0.2 phr, the amount of the rubber composition is too small to harmonize with the reinforcing fibers and the white carbon. If the content is more than 0.8 phr, the viscosity of the rubber composition may deteriorate. The quartz powder is preferably added in a range of 0.2 to 0.8 phr.

(8) Similar to quartz powder, the white carbon is dispersed and filled in a rubber composition in the form of fine particles, thereby enhancing the gas barrier effect and achieving a gas permeability value of 150 [cm 3 / (㎡ 24 h · atm)] or less do.

When such white carbon is less than 0.2 phr with respect to 100 phr of raw rubber, it is difficult to attain a gas permeability of 150 [cm 3 / (m 2 · 24 h · atm)] or less. When it exceeds 2.5 phr, , So that it is preferable to add it in the range of 0.2 to 2.5 phr.

However, it is preferable to select particles having the same size as the carbon black in consideration of the mixing ratio with the carbon black.

(9) Carbon black acts as a filler similar to the reinforcing fibers, quartz powder and white carbon described above, and is preferably added in a range of 15 to 40 phr with respect to 100 phr of the raw rubber.

If the carbon black is less than 15 phr, the mixing ratio with the reinforcing fiber, the quartz powder and the white carbon is not good enough to function as a filler. If the carbon black exceeds 40 phr, the viscosity of the rubber composition may change, Therefore, it is preferable to be added while adjusting to the above-mentioned range.

(10) Stearic acid serves as a lubricant and is preferably added in a range of 0.5 to 2 phr. If the amount of stearic acid is less than 0.5 phr, the lubricant does not act as a lubricant due to the rubber composition and the reinforcing effect is insufficient. When the amount of the stearic acid exceeds 2 phr, abrasion resistance may be deteriorated due to a rapid tensile property such as an increase in elongation. To be added in a range of 0.5 to 2 phr.

(11) The vulcanizing agent can be divided into an inorganic vulcanizing agent and an organic vulcanizing agent, and one or more of sulfur, peroxide, phenol resin and metal oxide can be used. Such a vulcanizing agent may be added in an amount of 1 to 5 phr to lower the heat generating performance.

When the vulcanization agent is less than 1 phr, vulcanization does not easily occur. When 5 phr is added, a corresponding amount of vulcanization accelerator is required. Therefore, the vulcanization agent is preferably added in a range of 1 to 5 phr based on 100 phr of the raw rubber.

(12) The vulcanization accelerator is preferably added in the range of 3 to 10 phr for enhancing the productivity through promotion of the vulcanization rate and improving the properties of the diaphragm. As the vulcanization accelerator, any one or more of Acc.DM, Acc.TT, Acc.CZ, ZnO (zinc oxide) and MgO (magnesium oxide) can be selectively used.

CZ is also called CBS (N-cyclohexyl-2-benzothiazoyl sulfenamide).

When the vulcanization accelerator is added in an amount of less than 3 phr, the reaction slows down and requires a long process time. When the vulcanization accelerator is added in an amount exceeding 10 phr, the reaction is rather accelerated and it is difficult to achieve uniform physical properties.

However, in some cases, if the vulcanization rate is too fast, a vulcanization retarder that delays the vulcanization rate may be added to control the vulcanization rate.

Next, the reinforcing fiber will be described.

That is, the reinforcing fiber not only enhances the durability of the diaphragm by improving the adhesion with the raw material rubber but also exhibits an excellent gas permeability of the diaphragm.

Since the diaphragm made of rubber alone can be used only at low pressure and is low in both pressure resistance and durability, it is difficult to apply it to a diaphragm for an accumulator. Therefore, in the present invention, by using a rubber composition dispersed and mixed with para- aramid staple fibers, The diaphragm is designed to have good pressure resistance and durability even at high pressure.

Particularly, it is preferable to use para-aramid short fibers having a length of 0.8 to 1.2 mm as reinforcing fibers. If the diameter is less than 0.8 mm, the surface of the diaphragm to be formed may be smooth, Mm, the surface of the diaphragm produced through the injection mold is not smooth and the target gas permeability value can not be obtained, so that the para-aramid staple fibers have a diameter of 0.8 to 1.2 mm (more preferably, 1 mm ).

This is supported by the following experimental results.

1 mm NBR CR FKM SL EPDM Hardness (Hs) 61 62 59 62 60 Elongation (%) 302 270 250 340 240 Tensile strength (kg / cm 2) 123 109 91 102 110 100% modulus (kg / ㎠) 61 55 41 57 49

Table 1 shows the results of evaluation of the properties of the aramid staple fibers of 1 mm length in nitrile butadiene rubber (NBR), chloroprene rubber (CR), fluorine rubber (FKM), silicone rubber (SL) and ethylene propylene rubber ≪ / RTI > shows the physical properties of the compounded rubber composition.

As can be seen from Table 1, it can be seen that excellent results are obtained in NBR, CR and EPDM among rubber compositions containing 1 mm para-aramid short fibers.

3 mm NBR CR FKM SL EPDM Hardness (Hs) 62 61 58 61 62 Elongation (%) 262 241 232 311 214 Tensile strength (kg / cm 2) 103 89 84 93 99 100% modulus (kg / ㎠) 54 48 37 47 38

Table 2 shows that 3 mm long para-aramid staple fibers of nitrile butadiene rubber (NBR), chloroprene rubber (CR), fluorine rubber (FKM), silicone rubber (SL) and ethylene propylene rubber (EPDM) ≪ / RTI > shows the physical properties of the compounded rubber composition.

As shown in Table 2, similar to the results obtained by mixing 1 mm para-aramid staple fibers, excellent results were obtained in NBR, CR, and EPDM.

6 mm NBR CR FKM SL EPDM Hardness (Hs) 61 62 60 59 60 Elongation (%) 226 216 205 277 199 Tensile strength (kg / cm 2) 97 78 74 81 86 100% modulus (kg / ㎠) 49 41 33 42 32

Table 3 shows the results of evaluation of the properties of the aramid short fibers of 6 mm length in nitrile butadiene rubber (NBR), chloroprene rubber (CR), fluorine rubber (FKM), silicone rubber (SL) and ethylene propylene rubber (EPDM) ≪ / RTI > shows the physical properties of the compounded rubber composition.

Therefore, it can be seen from the results of Tables 1 to 3 that the physical properties of the para-aramid staple fiber are generally lowered as the length of the para-aramid staple fiber becomes longer. Therefore, desirable.

Finally, the gas permeability will be described.

In other words, the diaphragm serves to block the nitrogen gas by being connected to the portion where the nitrogen gas directly touches the accumulator, and conventionally, the gas permeability of the accumulator diaphragm is 250 [cm 3 / (m 2 24 h · atm) And it is somewhat insignificant to block nitrogen naturally.

However, if a diaphragm having a high gas permeability is installed in the accumulator, the permeation of the gas becomes too good to perform the essential role of the diaphragm which blocks the gas.

That is, the gas permeability is a core part of the present invention, and the inventors of the present invention have been able to derive a diaphragm having an optimum gas permeability by repeatedly performing numerous experiments.

12 to 26 are graphs showing gas permeability test results according to a preferred embodiment of the present invention.

12 shows the gas (N ₂ ) transmittance when nitrilobutadiene rubber (NBR) as raw material rubber is mixed with para-aramid short fibers having a length of 1 mm. As compared with a diaphragm having a conventional gas permeability of about 250 [cm 3 / (m 2 · 24 h · atm)] as shown in FIG. 12, the gas permeability was 148 [cm 3 / (m 2 · 24 h · atm) It can be confirmed that it is very good.

13 shows the gas (N ₂ ) transmittance when 3 mm para-aramid staple fibers are mixed with nitrile butadiene rubber (NBR) as a raw material rubber. The gas permeability is 250 [cm 3 / (m 2 · 24 h · atm)] by bringing the gas permeability to 192 [cm 3 / (m 2 · 24 h · atm)] when 3 mm para- ], Gas permeation rate was not better than that of nitrile butadiene rubber mixed with 1mm para-aramid short fibers.

Figure 14 illustrates a gas (N ₂₎ permeability in the case where a raw material rubber nitrile butadiene rubber (NBR) para-aramid fiber in the blend of 6㎜ stage. 12 and 13, a gas permeability of 262 [cm3 / (m2 24 hr. Atm)] is obtained when 6 mm para-aramid short fibers having a relatively long length are mixed, ㆍ 24h ㆍ atm)] than the gas permeability of the gas.

FIG. 15 is a graph showing the gas permeability (N ₂ ) when ethylene propylene rubber (EPDM) is applied as raw rubber to ethylene propylene rubber and 1 mm para-aramid staple fibers are mixed, unlike FIGS. 12 to 14 . 15, when ethylene propylene rubber is used, 879 [cm 3 / (m 2 · 24 h · atm)], which is much higher than the conventional diaphragm gas permeability, is measured, have.

16 is a test data of gas (N ₂ ) transmittance when ethylene aramide short fibers having a length of 3 mm are mixed with ethylene propylene rubber (EPDM) as a raw rubber. 16, it was found that the gas permeability was measured at 697 cm3 / (m < 2 > 24h. Atm). Similarly to the case where 1 mm para aramid staple fibers were mixed in the ethylene propylene rubber of Fig. 15, The permeability of the diaphragm is high, and it can be understood that the diaphragm does not perform the gas blocking function properly.

17 shows the gas (N ₂ ) transmittance when 6 mm aramid short fibers of 6 mm were mixed with ethylene propylene rubber (EPDM) as a raw material rubber. Referring to FIG. 17, as the value of GTR shows a value of 1010 [cm 3 / (m 2 · 24 h · atm)], gas permeation is too good and it is somewhat difficult to commercialize it as a diaphragm.

Figure 18 is showing the test DATA gas (N ₂₎ permeability in the case where a para-aramid short fibers with a length of the raw rubber 1㎜ fluorine rubber (FKM) dispersion. As can be seen from FIG. 18, a high gas permeability value of 318 cm 3 / (m 2 24 h · atm) than the conventional gas permeability was derived, so that a para-aramid staple fiber having a length of 1 mm in nitrile- It can be seen that the role of the gas shut-off is not better than that in the case where the gas mixture is mixed.

Figure 19 is showing the test DATA gas (N ₂₎ permeability in the case of para-aramid in the raw material rubber 3㎜ fluorine rubber (FKM) short fibers are dispersed. 19, it can be seen that a high gas permeability value of 285 [cm 3 / (m 2 · 24 h · atm)] is determined in the same manner as in the case where 1 mm para-aramid staple fibers are dispersed in the fluorine rubber (FKM) have.

Figure 20 is showing the test DATA gas (N ₂₎ permeability in the case of para-aramid in the raw material rubber 6㎜ fluorine rubber (FKM) short fibers are dispersed. 20, the gas permeability is measured to be 248 [cm3 / (m2 24h. Atm) similarly to the case of Fig. 19), and it is somewhat difficult to fabricate a diaphragm having excellent gas barrier performance.

21 is a test data showing gas (N ₂ ) transmittance in the case where 1 mm para-aramid staple fibers are dispersed in chloroprene rubber (CR) as raw material rubber. As can be seen from FIG. 21, the gas permeability was measured to be 345 [cm 3 / (m 2 · 24 h · atm)] higher than in the case of using fluorine rubber (FKM). As a result, the chloroprene rubber also has a poor physical property to manufacture the diaphragm.

22 is a test data showing gas (N ₂ ) transmittance when 3 mm para-aramid staple fibers are dispersed in chloroprene rubber (CR) as raw material rubber. Referring to FIG. 22, it can be seen that the gas permeability is 359 [cm 3 / (m 2 24h · atm)] as in the case of FIG.

Figure 23 is showing the test DATA gas (N ₂₎ permeability in the case of mixing in that FIG. 21 and using the same raw materials, but rubber chloroprene rubber (CR) and 22, only the length of the para-aramid short fibers 6㎜. Referring to FIG. 23, it can be seen that a gas permeability of 303 [cm 3 / (m 2 24 h · atm)] similar to that of FIGS. 21 and 22 was measured.

24 is a test that appears DATA embellish the gas (N ₂₎ permeability in the case where a para-aramid short fibers with a length of 1㎜ the raw material rubber of silicone rubber (SL) mixture. Referring to FIG. 24, the gas permeability is measured to be 1810 [cm 3 / (m 2 24h · atm)], which indicates that gas permeability is too good to be applied to a diaphragm.

25 is a test that appears DATA embellish the gas (N ₂₎ permeability in the case where a 3㎜ of para-aramid short fibers in the raw material rubber of silicone rubber (SL) mixture. Referring to Fig. 25, since a very high gas permeability of 8180 cm3 / (m < 2 > 24h. Atm) is exhibited, it is considered that mixing of 3 mm para- aramid staple fibers in the silicone rubber makes it difficult to produce an accumulator diaphragm. It can be seen that there is a crowd.

26 is similar to the case of Fig. 24 and Fig. 25 except that silicone rubber (SL) is used as the raw rubber, but when the length of the para aramid staple fibers is longer than 6 mm in the case of Figs. 24 and 25 (N ₂ ) permeability of the test gas. 26, the gas permeability was found to be 9020 [cm 3 / (㎡ 24 hr 揃 atm)] when 6 mm para-aramid staple fibers were used in comparison with the case where 3 mm para-aramid staple fibers were used for the silicone rubber (SL) Was measured higher.

The gas permeability (GTR) according to the above-described sample can be summarized as follows.

Sample name GTR (Transmission rate) NBR 1 mm 148 NBR 3 mm 192 NBR 6 mm 262 EPDM 1 mm 879 EPDM 3 mm 697 EPDM 6 mm 1010 FKM 1 mm 318 FKM 3 mm 285 FKM 6 mm 248 CR 1 mm 345 CR 3 mm 359 CR 6 mm 303 SL 1 mm 1810 SL 3 mm 8180 SL 6 mm 9020 Unit: [cm 3 / (m 2 24h 揃 atm)]

In summary, when the nitrile butadiene rubber is used in the nitrile butadiene rubber (NBR), fluorine rubber (FKM), ethylene propylene rubber (EPDM), chloroprene rubber (CR) and silicone rubber (SL) I could see the sound.

In particular, in the case of a sample of 'NBR 1 mm' obtained by mixing para-aramid short fibers having a length of 1 mm with nitrile butadiene rubber, the gas permeability was measured as 148 [cm 3 / (㎡ 24 hr 揃 atm) It is understood that the best role of blocking is performed.

However, in the case of the silicone rubber, the gas permeability was measured to be too high regardless of the length of the para-aramid short fibers to be mixed, and it was found that the silicone rubber was not more suitable for the diaphragm for the emulsifier than the other raw rubber.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention may be embodied otherwise without departing from the spirit and scope of the invention.

Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to illustrate them, and the scope of the technical idea of the present invention is not limited by these embodiments.

The scope of protection of the present invention should be construed according to the claims, and all technical ideas within the scope of the claims should be construed as being included in the scope of the present invention.

Claims (4)

A diaphragm comprising a rubber composition in which reinforcing fibers are mixed,
The rubber composition may contain,
1 to 3 phr of reinforcing fibers, 0.2 to 0.8 phr of quartz powder, 0.2 to 2.5 phr of white carbon, 0.2 to 2.5 phr of white carbon, 15 to 30 phr of carbon black, and 1 to 3 phr of reinforcing fibers per 100 phr of raw rubber which is at least one of nitrile rubber, fluorine rubber, ethylene propylene rubber, chloroprene rubber, 0.5 to 2 phr of stearic acid, 1 to 5 phr of vulcanizing agent and 3 to 10 phr of vulcanization accelerator,
The reinforcing fiber is a para-aramid short fiber having a length of 1 mm,
In the diaphragm,
The rubber composition is injection-molded through an injection mold,
Wherein when the raw rubber is nitrile butadiene rubber, the gas permeability is 148 [cm 3 / (m 2 · 24 h · atm)]. delete The method according to claim 1,
The rubber composition may contain,
Is supplied to the injection mold preheated to 140 DEG C at a flow rate of 5.51 cm < 3 > / s under a pressure of up to 958 bar and injection-molded for 120 seconds. The method according to claim 1,
The silicone rubber,
Wherein the seal member is at least one of HCR (Heat Cure Rubber), LSR (Liquid Silicone Rubber) and MMR (Mold Marking Rubber).

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