KR101423715B1 - Foam floats by low sulfur blending and preparing method thereof - Google Patents

Abstract

The present invention relates to a process for producing a synthetic rubber sheet by mixing an acrylonitrile-butadiene rubber (NBR), a phenol resin, a vulcanizing agent, a foaming agent, a reinforcing agent, a dispersing agent and an accelerator to form a synthetic rubber sheet; Curing the synthetic rubber sheet to form an expanded molded article; Subjecting the expansion-molded article to a heat treatment under a first temperature elevating condition; And heat-treating the expansion-molded article under a second temperature elevating condition.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a foam float and a method for producing the foamed float,

The present invention relates to a foam float for use in detecting the level of fuel in a fuel tank and an LPG container of a vehicle, and a method of manufacturing the same.

In general, a fuel tank of a vehicle using fuel such as gasoline, kerosene, light oil or LPG (liquefied petroleum gas) is provided with a float and a gauge to detect the level of the fuel.

Normally floats used in gasoline vehicles should be able to withstand pressures of 5 to 10 kg / cm ² , and floats used in LPG or industrial vehicles should be constructed to withstand pressures of 25 to 30 kg / cm ² . In addition, an overfill protection device (OPD) valve is used as a safety device to prevent overcharging even in the case of a container storing LPG or propane gas. When about 80% of the internal space is filled, A float is also installed here.

Since the float is a part which is in direct contact with the liquid fuel, the float should have a low specific gravity, a high chemical resistance such as oil resistance and water resistance, and is used in a high-pressure vessel. Therefore, acrylonitrile-butadiene rubber , NBR) based foam float is the mainstream.

In order to satisfy the above-mentioned requirements, the foamed float is produced by adding various additives to NBR, which is a synthetic rubber, and subjecting the resultant rubber raw paper to foam molding. Korean Patent Registration No. 10-0555962 discloses a foam float produced by adding sulfur as a vulcanizing agent to NBR.

However, the foamed float thus prepared contains excessive sulfur, so that a gas containing sulfur or a sulfur compound flows out from the foam float over time, and the parts of the vehicle are corroded by the gas, There is a problem that contamination is caused.

The present invention provides a method for producing a foamed float capable of reducing the generation of a gas containing a sulfur or a sulfur compound and a foamed float produced by the method for solving the above problems.

However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

A first aspect of the present invention provides a method of making a foamed float comprising:

Forming a synthetic rubber sheet by mixing an acrylonitrile-butadiene rubber (NBR), a phenol resin, a vulcanizing agent, a foaming agent, a reinforcing agent, a dispersant, and an accelerator;

Curing the synthetic rubber sheet to form an expanded molded article;

Subjecting the expansion-molded article to a heat treatment under a first temperature elevating condition; And

Heat-treating the expanded molded article under a second temperature elevating condition

Wherein the foamed float has an average particle size of less than 100 nm.

According to an embodiment of the present invention, the first temperature raising condition may be a temperature increase within a range of 20 ° C / h to 40 ° C / h, but is not limited thereto.

According to an embodiment of the present invention, the second temperature raising condition may be a temperature increase within a range of 4 ° C / h to 5 ° C / h, but is not limited thereto.

According to an embodiment of the present invention, the step of forming the synthetic rubber sheet comprises: 100 parts by weight of the acrylonitrile butadiene rubber; 40 to 50 parts by weight of the phenol resin; 20 to 35 parts by weight of the vulcanizing agent; 6 to 8 parts by weight of the blowing agent, 35 to 45 parts by weight of the reinforcing agent, 0.5 to 2 parts by weight of the dispersing agent and 13 to 21 parts by weight of the accelerator, , But is not limited thereto.

According to one embodiment of the present invention, the accelerator may be selected from the group consisting of a vulcanization accelerator, a foaming promoter, and combinations thereof, but is not limited thereto.

According to one embodiment of the present invention, the vulcanization accelerator may be blended in an amount of 8 to 12 parts by weight based on 100 parts by weight of the acrylonitrile butadiene when the synthetic rubber sheet is formed, but is not limited thereto.

According to one embodiment of the present invention, the reinforcing agent may include, but is not limited to, MT (Medium Thermal) carbon black.

According to one embodiment of the present invention, the MT carbon black may have a particle diameter of 200 nm to 500 nm, but the present invention is not limited thereto.

A second aspect of the present invention provides a foam float, produced by the process according to the first aspect of the present application.

According to the present invention, by performing the step of heat-treating the expanded molded article under the first elevated temperature condition and the second elevated temperature condition in the production of the foam float, the amount of the sulfur or sulfur compound discharged from the finally produced foam float is reduced, Corrosion of components can be prevented, and the amount of sulfur or sulfur compounds discharged from the vehicle can be reduced to prevent environmental pollution.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart illustrating a method of manufacturing a foamed float according to one embodiment of the present application. FIG.
2 is an enlarged photograph of the carbon black cell structure used in the production of the foam float according to one embodiment of the present invention
3 is a photograph of a contact discoloration comparison of a part to which a foam float is applied according to an embodiment of the present invention.
4 is a photograph of an experimental apparatus for measuring H ₂ S emission of a foam float according to one embodiment of the present application.
5 is a photograph of an H ₂ S gas detection tube for measuring H ₂ S emission of a foam float according to one embodiment of the present application.

Hereinafter, embodiments and examples of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains.

It should be understood, however, that the present invention may be embodied in many different forms and is not limited to the embodiments and examples described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout this specification, when a part is referred to as being "connected" to another part, it is not limited to a case where it is "directly connected" but also includes the case where it is "electrically connected" do.

Throughout this specification, when a member is "on " another member, it includes not only when the member is in contact with the other member, but also when there is another member between the two members.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

As used herein, the terms "about," " substantially, "and the like are used herein to refer to or approximate the numerical value of manufacturing and material tolerances inherent in the stated sense, Accurate or absolute numbers are used to prevent unauthorized exploitation by unauthorized intruders of the mentioned disclosure. Also, throughout the present specification, the phrase " step "or" step "does not mean" step for.

Throughout this specification, the term "combination thereof" included in the expression of the machine form means one or more combinations or combinations selected from the group consisting of the constituents described in the expression of the machine form, And the like.

Throughout this specification, the description of "A and / or B" means "A, B, or A and B".

Hereinafter, the production method of the foam float of the present invention and the foam float produced by the above method will be specifically described with reference to the embodiments, examples and drawings. However, the present invention is not limited to these embodiments and examples and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart illustrating a method of manufacturing a foamed float according to one embodiment of the present application. FIG.

First, a synthetic rubber sheet is formed by mixing acrylonitrile-butadiene rubber (NBR), a phenol resin, a vulcanizing agent, a foaming agent, a reinforcing agent, a dispersant, and an accelerator.

The NBR is prepared by copolymerization of butadiene (BD) and acrylonitrile (AN) as known in the art, and the -C≡N group of acrylonitrile imparts polarity to the polymer and imparts oil resistance and rubber elasticity to the oil, And acts to increase the transition point (Tg). The physical properties can be controlled according to the change of the copolymerization ratio of the butadiene and the acrylonitrile and the blending ratio.

The vulcanizing agent is also referred to in the art as a vulcanizing agent and means an additive for changing a plastic material to an elastic material. In general, since raw material is a polymer material having a chain shape, it is difficult to apply directly to a foamed float because of high adhesiveness and a significant change in elasticity. Therefore, a vulcanizing agent can be added to impart elasticity to the raw material. The vulcanizing agent may be a vulcanizing agent generally used in the art, for example, sulfur, selenium, tellurium, organic sulfur compounds, metal oxides, organic peroxides, and the like, but is not limited thereto. In order to facilitate vulcanization by the vulcanizing agent, the promoting agent may include, but is not limited to, vulcanization accelerators. Examples of the vulcanization accelerator may include stearic acid, zinc oxide (ZnO), and CZ (N-cyclohexyl-2-benzothiazole sulfenamide) It is not.

The blowing agent refers to a material which is blended with rubber or the like to produce bubbles. Examples of the foaming agent include dinitropentamethylene tetramine (DPT), azodicarbonamide (ADCA), hydrazodicarbonamide (HDCA), p, p Toluenesulfonylhydrazide (TSH), benzenesulfonylhydrazide (BSH), 5-phenyltetrazole (5-PT), and the like are added to the reaction mixture, But are not limited thereto. In order to promote the performance of the blowing agent, the promoting agent may include, but is not limited to, a foaming promoter. The foaming promoter may be a foaming promoter generally used in the art, for example, a urea foam promoter, an amine foam promoter, and the like, but is not limited thereto.

The reinforcing agent is used for thickening the cell wall when mixed, and for example, carbon black reinforcing agent for rubber may be used, but the present invention is not limited thereto. The carbon black reinforcing agent may be, for example, a semi-reinforcing furnace (SRF) carbon black, a high abrasion furnace (HAF) carbon black, MT (medium thermal decomposition) , But is not limited thereto. The SRF carbon black is advantageous in that it is mixed well with rubber and does not deteriorate workability and physical properties even when compounded in a large amount, has excellent intermediate stiffness and aging resistance, and has little deformation in vulcanization (during molding). HAF carbon black has good reinforcing properties and is excellent in abrasion resistance, tensile strength, elongation, and bending resistance, and is thus widely used in products which are used in the production of tires and the like or which require strength. MT carbon black has high toughness and tear resistance when stretched and can be filled in a large quantity. Especially, when it is used in products having alcohol resistance because of good water resistance, fine structure can be obtained. The MT carbon black may have a particle diameter of about 200 nm to about 500 nm, but is not limited thereto. The MT carbon black has the advantage of being very compact and having a high density of formation as compared with carbon black having a carbon-carbon particle interval. As the reinforcing agent according to one embodiment of the present invention, the MT carbon black can be used. When the MT carbon black is used as a reinforcing agent, the final formed foam float can be formed in a more compact structure than in the case of using SRF carbon black Do. 2 (a) is an enlarged photograph of the SRF carbon black 50 times, FIG. 2 (b) is an enlarged photograph 50 times of the MT carbon black, FIG. 2 (c) (d) is an enlarged photograph of MT carbon black 100 times. As shown in FIG. 2, it can be confirmed that the cell particle interval of the MT carbon black is much more compact than the cell particle interval of the SRF carbon black

The dispersant serves to uniformly mix and disperse the NBR, the phenolic resin, the vulcanizing agent, the blowing agent, the reinforcing agent, and the promoter, and may be a dispersant generally used in the art. It is possible to use a dispersing agent which is commercially available as the dispersing agent, and for example, EXTON K-1 ^® (KAWAGUCHI ^{Inc.), EXTON K-5 ® (} KAWAGUCHI Inc.), Ultralube 160 ^® (Performance Additve Inc.), Ultralube 200 ^® (Performance Addit), Ultrapep 96 ^® (Performance Addit 25), Ultrablend 6000 ^® (Performance Addit), FL ^® (KETILITZ), and the like.

The accelerator may be, for example, a vulcanization accelerator and / or a foam accelerator, but is not limited thereto.

Wherein the vulcanizing agent is used in an amount of 20 to 35 parts by weight, the blowing agent is used in an amount of 6 to 50 parts by weight, 8 to 8 parts by weight of the reinforcing agent, 35 to 45 parts by weight of the reinforcing agent, 0.5 to 2 parts by weight of the dispersing agent, and 13 to 21 parts by weight of the accelerator. For example, when the accelerator includes the vulcanization accelerator, the vulcanization accelerator may be mixed in an amount of 8 to 12 parts by weight based on 100 parts by weight of the acrylonitrile butadiene. When the synthetic rubber sheet is formed, the content of the vulcanizing agent in the formation of the synthetic rubber sheet can be relatively reduced by including the vulcanization accelerator in an amount of 8 to 12 parts by weight. Accordingly, when a foamed float is prepared using sulfur or an organic sulfur compound as the vulcanizing agent, the content of sulfur or sulfur compounds contained in the finally formed foamed float can be reduced.

Subsequently, the synthetic rubber sheet is vulcanized to form an expanded molded article (S20).

The vulcanization may be carried out by, for example, primary vulcanization and secondary vulcanization, but is not limited thereto. The primary vulcanization process may be performed at a temperature lower than the foaming temperature of the foaming agent, but is not limited thereto. An expansion-molded article having elasticity is formed by the primary vulcanization molding process. Since the primary vulcanization molding process is performed at a temperature lower than the foaming temperature of the foaming agent, the foaming material may not yet be completely formed as unfoamed state. Thus, a secondary vulcanization molding process is performed to form a fully expanded molded article. The secondary vulcanization molding process may be performed at a temperature higher than the foaming temperature of the expansion-molded article.

The primary vulcanization process may be performed, for example, at about 125 캜 for about 1,200 seconds, but is not limited thereto. The secondary vulcanization molding process is performed at a relatively low temperature over a long period of time, rather than being carried out at a high temperature for a short time, thereby preventing overflow due to vulcanization for a long time and allowing vulcanization evenly to the inside of the product. For example, the secondary vulcanization process may be performed at a temperature ranging from about 160 DEG C to about 180 DEG C for about 3,600 seconds, but is not limited thereto.

Then, the expansion-molded article is heat-treated under a first temperature elevating condition (S30).

The foamed molded article has heat resistance to a temperature ranging from about 60 ° C to about 70 ° C without any heat treatment, and the first temperature elevating condition may have a relatively high temperature increasing rate. For example, the first elevated temperature condition may be, but is not limited to, increasing the temperature within the range of about 20 ° C / h to about 40 ° C / h. Under the first elevated temperature condition, the temperature is raised to about 80 캜 to heat-treat the expanded molded article.

Then, the expansion-molded article is heat-treated under a second temperature elevating condition (S40).

As described above, since the heat-resistant temperature range of the expanded molded article is in the range of about 60 ° C to about 70 ° C, dimensional changes (bulging) of the product may occur when the temperature is raised to about 80 ° C or more. Accordingly, the temperature increase rate of the second temperature elevation condition is lowered, and the curing speed of the cell walls in the product is made higher than the expansion force of the product, so that the dimensional change of the product can be reduced. For example, the second temperature raising condition may be an increase in temperature within a range of 4 ° C / h to 5 ° C / h, but is not limited thereto. Under the second temperature elevating condition, the temperature is raised to about 110 캜 to heat-treat the expanded molded article.

Then, the expansion-molded article is heat-treated for about 72 hours at an elevated temperature under the second temperature elevating condition. In the heat treatment process, the sulfur or sulfur compound residual gas in the product is discharged to the outside of the product, and the content of sulfur or sulfur compound contained in the final product can be greatly reduced.

The foam float produced by the present invention contains sulfur or sulfur compound of 1.0 PPM or less, which can reduce the amount of sulfur or sulfur compounds discharged from the foam float to prevent corrosion of components contained in the vehicle, It is possible to reduce the amount of sulfur or sulfur compounds emitted from the exhaust gas purifying catalyst, thereby preventing environmental pollution.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

[Example]

NBR 40 M 100 parts by weight (KNB-40M), stearic acid 1.3 parts by weight (TH 100), MT carbon black 42.9 parts by weight Thermax N990 Floform, phenolic resin 47.2 parts by weight KC- (Cellex-A), 6.6 parts by weight of blowing agent (Cellex-A), 0.25 part by weight of zinc oxide (DPT) were mixed using a roller to prepare a rubber raw sheet in the form of a sheet. The rubber raw paper was vulcanized at 125 캜 for 1,200 seconds and then vulcanized at 170 캜 for 3,600 seconds. The extrusion-molded foam molded article was heated to 80 DEG C under a temperature elevation condition of 30 DEG C / h and left at 80 DEG C for 15 hours. Subsequently, the sample was heated to 110 캜 under a temperature elevation condition of 4.3 캜 / h, and left at 110 캜 for 72 hours to prepare foam float samples 1 and 2, respectively.

[Comparative Example]

NBR 35L 100 parts by weight (KNB-35L), stearic acid 1.3 parts by weight (TH 100), SRF carbon black 42.9 parts by weight, phenolic resin 50.2 parts by weight (KC-3001), sulfur 43.9 parts by weight (SP- (DPT) was added to the roller (CZ) in an amount of 5 parts by weight based on 100 parts by weight of the binder (CZ P), 0.9 parts by weight of dispersant (K-1), 4.4 parts by weight of zinc oxide To prepare a rubber raw sheet in the form of a sheet. The rubber raw paper was vulcanized at 125 캜 for 1,200 seconds and then vulcanized at 200 캜 for 2,000 seconds. The vulcanization-molded expanded molded article was allowed to stand at 60 캜 for 24 hours to prepare comparative samples 1 and 2, respectively.

[Experimental Example 1]

The foam floats prepared in the above examples and comparative examples were inserted into an automobile fuel tank and the degree of discoloration at the contact points of the foam floats was visually observed, as shown in FIG. 3 (a) is a photograph of an automobile fuel tank equipped with a foam float manufactured according to the above embodiment, and FIG. 3 (b) is a photograph of an automobile fuel tank equipped with a foam float manufactured according to the above comparative example. As can be seen from FIG. 3, the contact area of the foam float produced according to the present example was not discolored, but the contact area of the foam float prepared according to the comparative example of the present invention was discolored to yellow.

[Experimental Example 2]

The H ₂ S emissions of the foamed floats prepared in the above Examples and Comparative Examples were observed using the experimental equipment of FIG. Specifically, Samples 1 and 2 prepared in the above examples and Samples 1 and 2 prepared in the above Comparative Example were allowed to stand at room temperature for 4 hours or more. Each of the 30 samples was placed in a 3 liter Tedlar bag, and the Tedlar bag was sealed and left at room temperature for 48 hours. One end of the H ₂ S gas detection tube (manufactured by Gastec Japan) was connected to the cradle of the Tedlar bag, and the other end was connected to the gas sampler. The cock was opened and 100 ml of air in the Tedlar bag was collected in the gas sampler. 5 is a photograph of the H ₂ S gas detection tube in which H ₂ S gas is collected. 5 is a detector tube connected to a Tedlar bag storing a sample according to the embodiment of the present invention, and the right detector tube of FIG. 5 was connected to a Tedlar bag storing a sample according to the comparative example of this embodiment It is a detector tube. As can be seen from FIG. 5, it can be confirmed that the discoloration due to H ₂ S discharged from the foam float according to the embodiment of the present invention is much smaller than the discoloration due to H ₂ S discharged from the foam float according to the comparative example. The amount of H ₂ S gas discharged was checked by checking the degree of discoloration in each of the detection tubes. The results are shown in Table 1 below.

[Table 1]

As can be seen in the above Table 1, the amount of H ₂ S discharged from the foam float according to the embodiment of the present application was much smaller than the amount of H ₂ S discharged from the foam float according to the comparative example.

It can be seen from the results of the above examples that the foam float according to the present invention has a very small emission amount of H ₂ S and can thus prevent corrosion of components contained in the vehicle, The amount of the compound can be reduced.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments and the exemplary embodiments, and various changes and modifications may be made without departing from the scope of the present invention. It is evident that many variations are possible by those skilled in the art.

Claims (9)

Forming a synthetic rubber sheet by mixing an acrylonitrile-butadiene rubber (NBR), a phenol resin, a vulcanizing agent, a foaming agent, a reinforcing agent, a dispersant, and an accelerator;
Curing the synthetic rubber sheet to form an expanded molded article;
Heat-treating the expanded molded article under a first temperature elevating condition in which the temperature is increased within a range of 20 ° C / h to 40 ° C / h; And
Heat-treating the expanded molded article under a second temperature increasing condition in which the temperature is increased within a range of 4 ° C / h to 5 ° C / h
Wherein the foamed float has an average particle size of less than 100 nm.
delete delete The method according to claim 1,
Wherein the step of forming the synthetic rubber sheet comprises: 40 to 50 parts by weight of the phenol resin, 20 to 35 parts by weight of the vulcanizing agent, 6 to 30 parts by weight of the blowing agent, based on 100 parts by weight of the acrylonitrile butadiene rubber, By weight of the reinforcing agent, 35 to 45 parts by weight of the reinforcing agent, 0.5 to 2 parts by weight of the dispersing agent, and 13 to 21 parts by weight of the accelerator.
The method according to claim 1,
Wherein the accelerator comprises a material selected from the group consisting of a vulcanization accelerator, a foaming promoter, and combinations thereof.
6. The method of claim 5,
Wherein the vulcanization accelerator is mixed in an amount of 8 to 12 parts by weight based on 100 parts by weight of the acrylonitrile butadiene when the synthetic rubber sheet is formed.
The method according to claim 1,
Wherein the reinforcing agent comprises MT (Medium Thermal) carbon black.
8. The method of claim 7,
Wherein the MT carbon black has a particle diameter of 200 nm to 500 nm.
A foamed float, produced by the process according to any one of claims 1 and 8 to 8.

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