KR100555962B1 - Hard foam rubber closed cellular ebonite - Google Patents

Abstract

The present invention is to control the composition ratio of each additive in the mixing process of the foamed float formed by foaming the rubber dough mixed with various additives added as the main component of the NBR-based synthetic rubber, and the carbon black-based reinforcing agent is added to It relates to a foamed float that greatly improves neglectability.

The present invention for realizing this is a mixing process in which various additives are added and mixed with acrylonitrile butadiene lava (NBR), which is a synthetic rubber, as a main component, and heat treatment after primary and secondary vulcanization molding of the rubber dough produced in the mixing process. In the foamed float produced in the above, the mixing step is added to the NBR 100 parts by weight, at least one of SRF, HAF, MT or Clay as a reinforcing agent to improve the high pressure resistance on the basis of various additives and its weight. It provides a high pressure resistance and foaming float that is improved, characterized in that the mixing is improved, the high pressure resistance and resistance to breakage is not broken even at 45kg / cm ² or more, including LPG fuel and alcohol-based fuel The invention can be used for fuel tanks of all liquid fuels.

High pressure resistance, neglect resistance, MT, HAF, SRF

Description

Foam float {Hard foam rubber closed cellular ebonite}

1 is a 50 times cross-sectional enlarged photograph of a high-pressure-resistant foam float prepared according to the present invention,

Figure 2 is a 50 times cross-sectional enlarged picture of the foam according to the prior art,

Figure 3a is a photograph of the surface of the high pressure resistance foam foam improved according to the present invention,

Figure 3b is a photograph of the surface of the expanded float prepared in accordance with the present invention,

4 is a photograph of the surface of the foamed float according to the prior art.

The present invention relates to a foamed float which is installed in a fuel tank in which various liquid fuels are stored. More specifically, a mixture of foamed floats formed by foaming a rubber produced by adding various additives as a main component of NBR-based synthetic rubber The present invention relates to a foam float in which the composition ratio of each additive in the process is adjusted and a carbon black-based reinforcing agent is added to improve the high pressure resistance and the resistance to resistance.

In general, a float and a gauge are installed to detect the level of fuel in a fuel tank of a vehicle using gasoline, kerosene, diesel, or LPG (liquefied petroleum gas) as a fuel.

Floats used in gasoline vehicles and the like must withstand a pressure of 5 to 10 kg / cm ² , and floats used in LPG or industrial vehicles should be made to withstand a pressure of 25 to 30 kg / cm ² .

In addition, in the case of LPG or propane gas storage, an overfill protection device (OPD) valve is adopted as a safety device to prevent overcharging, and the gas inlet is automatically blocked when about 80% of the internal space is filled. Float is installed.

As the float is a part that is in direct contact with liquid fuel, the specific gravity should be low, and the chemical resistance such as oil resistance and water resistance should be strong, and the acrylonitrile butadiene lava (NBR; Butadiene rubber-based foam float is the mainstream.

In order to satisfy the requirements as described above, the foamed float is manufactured by foam molding a rubber product mixed with various additives to NBR, which is a synthetic rubber, and is commonly used for the first vulcanization and the second vulcanization. It is manufactured through a foaming process.

As a prior art for such a foam float, the Republic of Korea Patent Publication No. 307396 is a raw material mixing step of NBR and phenolic resin as the main raw material, the raw material produced after the mixing step is first injected into the mold plate and cut to a suitable size In the refractory foam float produced by the first step of vulcanized dough, the first step of vulcanization and curing at about 200 ℃ after the first cure and the step of cooling and drying the molded product, the foam float is methyl ethyl A ketone is proposed for a non-permeable foam float characterized in that it is coated with an epoxy resin mixture mixed at a weight ratio of 0.02 to 0.1.

However, the foamed float according to the prior art has a pressure resistance of about 20 kg / cm ² to 30 kg / cm ² , and thus, in a fuel tank of a vehicle using LPG as a fuel, the demand is increasing rapidly in recent years. It will be insufficient in stability to be installed.

In addition, even in the case of a fuel tank of a general gasoline automobile, the cell structure of the foamed float is damaged when a high pressure is generated in the fuel tank or when a chemical reaction between the foamed float and the fuel occurs. As a result, fuel penetrates into the foam float and does not exhibit proper function.

In recent years, countries such as Central and South America, where Korean vehicles are widely exported, use gasohol, an alcohol-based automobile fuel made of 80 to 90% unleaded gasoline and 10 to 20% of absolute ethanol and methanol. Considering Korea's situation of exporting automobiles to these countries, it is necessary to present foamed floats with excellent resistance to plastic holes.

However, the non-resistant foam of the prior art has to go through a separate process of coating with epoxy resin mixture after the first vulcanization process and the second vulcanization process, the manufacturing process is added to the manufacturing process is complicated to increase the manufacturing cost There is a problem that the stability is lowered because the structure is coated with the non-hole-resistant mixture on the outer surface of the foam float itself is not provided.

Therefore, the present invention is a foam float installed in the fuel tank in which the liquid fuel is stored is provided with a sufficient high pressure resistance, oil resistance and water resistance, including the fuel tank of the vehicle using LPG fuel and alcohol fuel to store most of the liquid fuel It is an object of the present invention to provide a foam float having high pressure resistance or neglect resistance to be stably usable in a fuel tank.

In order to achieve the above object, the present invention, a synthetic rubber, a phenol resin, a vulcanizing agent, a blowing agent, a reinforcing agent and an accelerator, etc. are mixed with the main component of acrylonitrile butadiene rubber (NBR), a rubber produced in the mixing process In the foam float produced by heat treatment after the second vulcanization molding to the size of the finished product at a temperature higher than the decomposition temperature of the blowing agent to the size of the final product at the temperature lower than the decomposition temperature of the blowing agent. The mixing step is based on the weight of NBR 100 parts by weight, 35 to 55% phenol resin, 30 to 40% sulfur as vulcanizing agent, 5% to 5.5% zinc oxide (ZnO) as vulcanizing aid and 1 to 1.5 stearic acid. %, 5-7% DPT as blowing agent, 3-4.5% DPT aid as foaming aid, 1.8-2.1% CZ as accelerator, 50% or less of any one of SRF or HAF or MT or Clay as reinforcing agent Since my books are mixed characterized in that the high-pressure castle improved.

According to another aspect of the present invention, a synthetic process in which a phenol resin, a vulcanizing agent, a blowing agent, a reinforcing agent, an accelerator, and the like are mixed with acrylonitrile butadiene laba (NBR), which is a synthetic rubber, as a main component, and the rubber dough produced in the mixing step is a blowing agent. In the foam float produced by heat treatment after secondary vulcanization to the size of the finished product at the temperature higher than the decomposition temperature of the blowing agent to the foamed product produced by primary vulcanization molding at a temperature lower than the decomposition temperature of the foaming agent, the mixing The process is based on 100 parts by weight of NBR, 50 to 60% of phenol resin, 45 to 55% of sulfur as vulcanizing agent, 5% to 5.5% of zinc oxide (ZnO) as vulcanizing aid, and 1 to 1.5% of stearic acid, blowing agent. DPT 6 ~ 7.5% as a foaming aid, 3 ~ 4.5% as a foaming aid, CZ 1.8 ~ 2.1% as a promoter, MT 40-50% and Clay 3 ~ 5% as a reinforcing agent are added and mixed to improve the resistance that It characterized.

The foamed float for improving the high pressure resistance of the present invention is a phenol resin, a vulcanizing agent, a vulcanizing aid mainly comprising NBR which is a synthetic rubber. Mixing process for mixing and producing rubber dough by adding foaming agent, foaming aid, reinforcing agent and accelerator, primary foaming process for primary vulcanization molding the rubber dough appropriately and smaller than the size of finished product at temperature lower than decomposition temperature of foaming agent, The foamed molded product vulcanized in the primary foaming process is prepared, including secondary foaming process and heat treatment process for secondary vulcanization to the size of the finished product at a temperature higher than the decomposition temperature of the blowing agent.

NBR used in the mixing process is manufactured by copolymerization of butadiene and acrylonitrile, and a product having a nitrile content of 35.5% to 45% having oil resistance is used.

The thermosetting phenolic resin, sulfur as a vulcanizing agent, zinc oxide (ZnO) and stearic acid as a vulcanizing aid, DPT as a blowing agent, DPT as a foaming aid, CZ as a promoter, SRF or HAF as an adjuvant Or one or more of MT or Clay is added to perform the mixing process.

SRF, HAF and MT mentioned as the above reinforcing agents are carbon black based reinforcing agents for rubber.

Carbon black refers to black fine carbon powder, which corresponds to so-called soot, and the size of carbon particles is 1 to 500 ml and similar to graphite.

Industrially, soot produced by incomplete combustion of natural gas, tar, and the like is collected or pyrolyzed to produce them.

Currently 85% of the consumption is for rubber, and 11% is used for black pigments, including printing inks.

For rubber, it is suitable that the particles do not have fine chain-shaped bonds, and are used to give properties such as enhancer, oil resistance, heat resistance, and the like.

SRF (Semi reinforcing furnace) is well mixed with rubber and does not degrade workability or physical properties even if it is mixed in large quantities. It is not only excellent in medium reinforcement and aging resistance, but also has little deformation during vulcanization (in molding).

High abrasion furnace (HAF) has good reinforcement, good abrasion resistance, tensile strength, elongation rate and bending resistance, so it is used in the manufacture of tires or other products that require strength.

MT (Medium thermal) is a high elasticity, it has low tear resistance at the time of elongation and can be filled in large quantities. Especially, since it has good water resistance, it can obtain fine structure when used in alcohol-resistant products.

In addition, the clay mentioned above as a reinforcing material is produced by mixing Al ₂ O ₃ (aluminum oxide) and a small amount of CaO (lime) with conventional SiO ₂ (silica), or a small amount of SiO ₂ (silica) with CaO (lime) Hard coal produced by mixing may be used.

Table 1 below summarizes the physical properties of the carbon black SRF, HAF, and MT used in the mixing process.

On the other hand, in order to reduce the size of the cells (bubbles, pores) formed in the foam float and to form a large number of cells in the same area, the cell walls should be formed thick.

Therefore, it is very important to control the ratio of each reinforcing agent (SRF, HAF, MT, Clay) in order to form a thick cell wall in the mixing process.

In addition, the reinforcing material (SRF, HAF, MT, Clay) added in the mixing process, at least one of SRF or HAF, MT or Clay by 50% by weight based on its weight NBR.

This is because when the content of the reinforcing agent exceeds 50%, the role of NBR as rubber is significantly reduced.

Hereinafter, various embodiments for satisfying the above conditions by adjusting the composition ratio of each component used in the mixing process will be described.

Example 1

100 parts by weight of NBR, 35 to 55% phenolic resin, 30 to 40% sulfur as vulcanizing agent, 5% to 5.5% zinc oxide (ZnO) as vulcanizing aid, 1 to 1.5% stearic acid, DPT as blowing agent 5 to 7%, 3 to 4.5% of DPT aid as foaming aid, 1.8 to 2.1% of CZ as accelerator, 5 to 15% of SRF as a reinforcing agent, and 20 to 30% of MT are added to form a rubber dough.

Example 2

100 parts by weight of NBR, 35 to 55% phenolic resin, 30 to 40% sulfur as vulcanizing agent, 5% to 5.5% zinc oxide (ZnO) as vulcanizing aid, 1 to 1.5% stearic acid, DPT as blowing agent 5 to 7%, 3 to 4.5% of DPT aid as foaming aid, 1.8 to 2.1% of CZ as accelerator, and 10 to 20% of HAF and 20 to 30% of MT as reinforcing agent are added to make rubber dough.

Example 3

100 parts by weight of NBR, 35 to 55% phenolic resin, 30 to 40% sulfur as vulcanizing agent, 5% to 5.5% zinc oxide (ZnO) as vulcanizing aid, 1 to 1.5% stearic acid, DPT as blowing agent 5 to 7%, 3 to 4.5% of DPT preparation as foaming aid, 1.8 to 2.1% of CZ as accelerator, and 3 to 5% of clay and 30 to 45% of MT as reinforcing agent are added to make rubber dough.

As in Examples 1, 2, and 3, the rubber dough mixed and produced by varying the type and content of the reinforcing agent is filled in a transfer mold used in the manufacture of a conventional foam float, and undergoes primary and secondary foaming processes.

The vulcanization molding conditions in the primary foaming step is preferably vulcanized for about 1200 seconds at 125 ℃ lower than the foaming temperature of 160 ~ 180 ℃ foaming agent.

For example, the design dimensions of the molds used in the primary foaming process are set at about 50 to 70% of the finished product, so if the volume is 20cc and the specific gravity is 0.2, 4cc should be filled.

The foamed molded product formed after the primary foaming process is an elastic body, and has a size of about 50 to 70% of the mold of the secondary foaming process, and it is vulcanized at a temperature lower than the foaming temperature of the foaming agent, and thus bubbles are still uncured. Since it is not formed and the hardness tends to fall, the secondary foaming process is performed.

Vulcanization molding conditions of the secondary foaming process is preferably about 3600 seconds at 195 ℃ higher than the temperature of the foaming agent, filled in a mold set to the dimensions of the finished product, vulcanized and emulsified.

For example, the mold used in the primary foaming process and the secondary foaming process may be attached with a pin for forming an arm hole such that an arm hole for joining with an arm of a fuel gauge is formed in a foam float to be finally completed. It is also preferable to process a plurality of gas discharge holes for the discharge of nitrogen gas generated in the foaming process.

Meanwhile, the foamed molded product formed through the primary and secondary foaming processes is finally heat treated for about 24 to 36 hours in an oven maintaining 80 ° C. to 100 ° C., thereby completing a high pressure resistant foam float.

Next is summarized in Table 2 the weight change rate measured after maintaining the high pressure-resistant foam float and the conventional product prepared in accordance with the present invention for 3 minutes immersion at a water pressure of 45kg / cm ² or more.

In general, the weight change rate should be unchanged within 3%, but as in the above experiment, the foam float according to the prior art showed a value of more than 3% in weight change rate, and the foam float according to the present invention showed a very small weight change rate. .

The foaming float for improving the resistance to resistance due to the other idea of the present invention is manufactured through each manufacturing process in the above-mentioned high pressure resistant foaming float, but the composition ratio of Example 3 in which clay and MT are added as a reinforcing agent in the mixing process There is a difference between increasing the content of phenolic resin and sulfur at and the increase in vulcanization time in the secondary foaming process.

On the other hand, the foamed float used in the alcohol-based fuel must have alcohol resistance and in order to have such alcohol resistance must be excellent in oil resistance (water resistance) and water resistance (耐水 性).

Hereinafter, an embodiment of satisfying the above conditions by adjusting the composition ratio of each component used in the mixing process will be described.

Example 4

100 parts by weight of NBR, 50% phenolic resin, 30-40% sulfur as vulcanizing agent, 5% zinc oxide (ZnO) and 1% stearic acid as vulcanizing agent, 5% DPT as blowing agent, DPT as foaming aid 3.5% of the preparation, 2% of CZ as an accelerator, 2% of clay as a reinforcing agent, and 43% of MT are added to form a rubber dough to be mixed.

The rubber dough mixed and produced by Example 4 is filled in a transfer mold such as the high pressure resistant foam float, and undergoes primary and secondary foaming and heat treatment.

On the other hand, in the secondary foaming process, as in the secondary foaming process of the above-mentioned high pressure resistant foam float, the vulcanization temperature is the same as 195 ° C., but the vulcanization time is increased from about 3600 seconds to about 4000 seconds.

As described above, it is difficult to explain the physical principle of the principle of improving the resistance to the increase of the phenol resin and the sulfur. However, the inventors have been experimenting for several years with the addition of clay containing the carbon black reinforcing agent MT and silica. By increasing the composition ratio of the resin and the sulfur component, the secondary vulcanization time is prolonged and the resistance to neglect is improved.

The following is the weight change rate measured after precipitating the non-porous foam float prepared in accordance with the present invention and the conventional product in a plastic hole solution (alcohol mixed fuel; gasoline, methanol, ethanol mixed solution) and maintained at 60 ℃ for 200 hours Summarized in 3.

In this experiment, the weight change rate should normally be unchanged within 10%. However, as in the above experiment, the foam float according to the prior art showed a value in which the weight change rate far exceeded 10%, and the foam float according to the present invention is acceptable. The rate of change of weight appeared within the range.

As described above, the high pressure resistant foam float according to the present invention can be seen that the number of cells per unit area is increased sharply (see FIGS. 1 and 2) compared to the conventional foam float using a carbon black reinforcement agent, which is a foam float. By increasing the strength and hardness of the will have a much improved high pressure resistance compared to the prior art.

On the other hand, the non-resistant foam float according to another aspect of the present invention is to be resistant to the foam float itself is highly stable compared to the non-resistant foam float of the prior art coating the resistant mixture.

As described above, the high pressure resistant foam float and the refractory foam float according to the present invention have almost no cracks compared to the prior art, and the smoothness is excellent and the aesthetics are excellent (see FIGS. 3a, 3b and 4). It will be much more advantageous to export goods, etc., the shape is formed in a variety of shapes depending on the mold, such as cylindrical or square, as shown in the above drawings.

As described above, the present invention is a rigid foam formed with an independent cell (bubble, pores), not only damaged at 45kg / cm ² or more, but also excellent in oil resistance, water resistance, LPG resistance, and neglect resistance, and thus, LPG fuel tank. The advantage is that it can be used in fuel tanks of almost all liquid fuels using alcoholic fuels.

Claims (5)

Synthetic rubber based on acrylonitrile butadiene lava (NBR), a phenol resin, a vulcanizing agent, a blowing agent, a reinforcing agent, and an accelerator. In the foamed float produced by primary vulcanization molding to be smaller than the size of the foamed product produced by heat treatment after secondary vulcanization to the size of the finished product at a temperature higher than the decomposition temperature of the blowing agent, The mixing step is based on the weight of NBR 100 parts by weight, 35 to 55% phenol resin, 30 to 40% sulfur as vulcanizing agent, 5% to 5.5% zinc oxide (ZnO) as vulcanizing aid and 1 to 1.5% stearic acid DPT 5-7% as foaming agent, DPT 3 ~ 4.5% as foaming aid, CZ 1.8-2.1% as promoter, SRF 5-15% and MT 20-30% as reinforcing agent are added and mixed Foam float, characterized in that improved. Synthetic rubber based on acrylonitrile butadiene lava (NBR), a phenol resin, a vulcanizing agent, a blowing agent, a reinforcing agent, and an accelerator, and the rubber dough produced in the mixing process at a lower temperature than the decomposition temperature of the blowing agent. In the foamed float produced by primary vulcanization molding to be smaller than the size of the foamed product produced by heat treatment after secondary vulcanization to the size of the finished product at a temperature higher than the decomposition temperature of the blowing agent, The mixing step is based on the weight of NBR 100 parts by weight, 35 to 55% phenol resin, 30 to 40% sulfur as vulcanizing agent, 5% to 5.5% zinc oxide (ZnO) as vulcanizing aid and 1 to 1.5% stearic acid DPT 5-7% as foaming agent, DPT 3 ~ 4.5% as foaming aid, CZ 1.8-2.1% as promoter, HAF 10-20% and MT 20-30% as mixing agent are added and mixed Foam float, characterized in that improved. Synthetic rubber based on acrylonitrile butadiene lava (NBR), a phenol resin, a vulcanizing agent, a blowing agent, a reinforcing agent, and an accelerator, and the rubber dough produced in the mixing process at a lower temperature than the decomposition temperature of the blowing agent. In the foamed float produced by primary vulcanization molding to be smaller than the size of the foamed product produced by heat treatment after secondary vulcanization to the size of the finished product at a temperature higher than the decomposition temperature of the blowing agent, The mixing step is based on the weight of NBR 100 parts by weight, 35 to 55% phenol resin, 30 to 40% sulfur as vulcanizing agent, 5% to 5.5% zinc oxide (ZnO) as vulcanizing aid and 1 to 1.5% stearic acid DPT 5-7% as foaming agent, DPT 3 ~ 4.5% as foaming aid, CZ 1.8-2.1% as accelerator, 3-5% Clay as reinforcing agent and 30-45% MT as mixing agent are added and mixed. Foam float, characterized in that improved. Synthetic rubber based on acrylonitrile butadiene lava (NBR), a phenol resin, a vulcanizing agent, a blowing agent, a reinforcing agent, and an accelerator, and the rubber dough produced in the mixing process at a lower temperature than the decomposition temperature of the blowing agent. In the foamed float produced by primary vulcanization molding to be smaller than the size of the foamed product produced by heat treatment after secondary vulcanization to the size of the finished product at a temperature higher than the decomposition temperature of the blowing agent, The mixing step is based on the weight of NBR 100 parts by weight, 50 to 60% phenol resin, 45 to 55% sulfur as vulcanizing agent, 5% to 5.5% zinc oxide (ZnO) as vulcanizing aid and 1 to 1.5% stearic acid. , DPT 6-7.5% as foaming agent, DPT 3 ~ 4.5% as foaming aid, CZ 1.8-2.1% as accelerator, MT 40-50% and Clay 3-5% as reinforcing agent are added and mixed Foam float, characterized in that improved. delete

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