KR100571505B1 - Pressure-resistant foam rich - Google Patents

Abstract

The present invention relates to pressure-resistant foam rich, 39 to 46% by weight of phenol resin, 30 to 40% by weight of carbon black, 3.5 to 5% by weight of zinc oxide, 1.0 to 1.5% by weight stearic acid %, Sulfur 35 to 43 wt%, azodicarbonamide (AC) 6.0 to 7.0 wt%, foaming aid 3.5 to 4.5 wt%, L-7 0.5 to 1.0 wt%, and CZ 1.5 to 2.0 wt% The powder of the mixture is introduced into a range of 120 to 150 parts by weight, and the mixture of particles having a particle size of the carbon black is 400 to 550 µm and the sulfur is 350 to 450 mesh fine particles passes through a conventional process, and then 115 to After molding and cooling at 125 ° C. for 800 to 1000 seconds, and then molding again at 160 to 180 ° C. for 2400 to 2600 seconds and post-treatment of the molding at 60 to 80 ° C. for 24 hours, the specific gravity is 0.28 to 0.35. It is very light but small and dense, so it can be deposited on LPG for a long time. Even for the LPG, which is able to withstand the weight change very little over 50㎏ / ㎠ high pressure is the optimum rich.

LPG flow rate constant, float, low pressure, high pressure

Description

Pressure-resistant foam float

Figure 1 is a 50 times magnification micrograph showing a cross-sectional state after the first molding process in the pressure-resistant foam rich according to the present invention,

Figure 2 is a 50 times magnification micrograph showing a cross-sectional state after the secondary molding process in the pressure-resistant foam rich according to the present invention,

Figure 3 is a 50 times magnification micrograph showing the surface state when the after-treatment step in the pressure-resistant foam rich according to the present invention,

Figure 4 is a 50 times magnification micrograph showing the surface state when the after-treatment step in the pressure-resistant foam rich according to the present invention,

5 is a graph showing the weight change rate according to the carbon type of the pressure-resistant foam rich according to the present invention,

Figure 6 is a graph showing the weight change rate according to the post-treatment of pressure-resistant foam rich according to the present invention,

Figure 7 is a graph showing the weight change rate according to the secondary molding time of the pressure-resistant foam rich according to the present invention.

※ Explanation of code for main part of drawing

A: this invention

B: control standard

The present invention relates to a pressure-resistant foam rich, more specifically, to a pressure-resistant foam rich for LPG gas capable of withstanding high pressure of 50kg / ㎠ or more.

Foam rich is used in automobiles, motorcycles, agricultural machinery, ships, heaters, carburettors, humidifiers, compressors, and other devices and machinery, such as flow meters, liquid level controls, and automatic level sensors. It is widely used as a product, and foamed parts made of NBR (nitrile-butadiene rubber), which are produced domestically, are generally light, have excellent oil resistance, water resistance, LPG resistance, and can withstand pressures of 25㎏ / ㎠ and general gasoline. Although it has been widely used in various flowmeters, such foamed parts are damaged at a pressure of 50 kg / cm 2 or more, and the fuel penetrates into the foamed parts during LPG deposition and loses its function, which is not suitable for high pressures of 25 kg / cm 2 or more.

Meanwhile, with the leap forward of our economy, gas has been recognized as a clean and convenient fuel to replace oil, and we have come closer to our lives. Currently, it is being used as the most popular living fuel in the world. The number of vehicles is increasing rapidly.

In the LPG storage tank, the level gauge should be able to withstand pressures of 50 kg / cm 2 or more. As described above, the foamed parts made of NBR can only withstand pressures of 30 kg / cm 2 at most. For the LPG storage tanks, the rich man is made of iron. However, this iron rich is a hollow product, so even if a small leak or pinhole occurs in the sphere, LPG penetrates and loses its product function, and its assembly with the assembly cannot be used apart. The case was a reflection.

On the other hand, existing NBR foamed parts have an inner wall between independent bubbles and bubbles in their structure, so that they can maintain their function even if there are small leaks or holes. There must be an organization. However, the small and even bubbles increase the density and hence the specific gravity, so that the foam rich for LPG high pressure tank cannot meet the requirement of being light and solid at the same time.

In addition, developed countries such as the United States have mandated the installation of an overfill-prevention device (OPD) in LPG gas storage containers, and the valve of the overfill prevention device rises when the container is approximately 80% full and the filling operation is performed. This prevents overcharging of the gas container in advance, thereby promoting safety when filling and using the gas container. The rich man must also be able to withstand high pressure of 50㎏ / ㎠ and above.

In addition, in the case of rich storage tank rich, the buoyancy required is large, so the volume must be large in the same ratio, and if the rich volume is large, the internal and external heat conduction is not achieved in the vulcanizing process, so it is impossible to obtain a dense structure. In the process, high temperature of more than 180 ℃ is given only to the outside, so in the process of conducting heat to the inside, the surface becomes over cure, cracking or burning, and the inside becomes under cure. Hardness and pressure resistance were difficult to obtain.

Thus, in order to withstand the high pressure of 50kg / ㎠ or more, the rich structure of the rich must be dense and strong, and the specific gravity of the LPG is about 0.5, so the rich must always be lighter than 0.3 in order to float on the LPG. Making light weight while increasing the pressure resistance in the production of the was a difficult task to satisfy the mutually exclusive phenomenon at the same time.

Therefore, current technology maintains the function at a pressure of about 30㎏ / ㎠, but at a high pressure of 50㎏ / ㎠ and more, the appearance of the rich is distorted and the fluid penetrates into the interior, thus losing the function of the rich for LPG storage containers. Currently, it is imported from foreign countries or used by welding iron rich people.

In view of the present situation in foamed parts for LPG gas, the present invention has a rigid shape containing no independent change in appearance even at a high pressure of 50 kg / cm 2 or more, and having a weight change of ± 3% by weight or less upon long-term deposition on LPG. In order to develop high quality foamed parts for high pressure, research has been carried out in terms of the optimal working conditions in the manufacturing process, raw material development and composition ratio.                         

As a result, the LPG gas is small and has many independent bubbles, and the cell wall strength between the bubbles and the bubbles is large and propane and butane are deposited for a long time in LPG, which is almost no change in weight, and it is light and can withstand high pressure of 50 kg / ㎠ or more. The development of foam rich.

The pressure-resistant foamed part according to the present invention contains 39 to 46% by weight of phenol resin, 30 to 40% by weight of carbon black, 3.5 to 5% by weight of zinc oxide, 1.0 to 1.5% by weight of stearic acid, in 100 parts by weight of NBR. Sulfur 35 to 43% by weight, azodicarbonamide (AC) 6.0 to 7.0% by weight, foaming aid 3.5 to 4.5% by weight, L-7 (mixture of metal salt, fatty acid & ester: manufactured by Kawaguchi Chemical Industries, Japan A powder of a mixture consisting of 0.5 to 1.0% by weight and 1.5 to 2.0% by weight of N-cyclohexyl-Z-benzotiazolyl sulfenamide (CZ) is added and formed within the range of 120 to 150 parts by weight;

       The carbon black has a particle size of 400 to 550 µm and the sulfur is fine particles of 350 to 450 mesh;

It is characterized by a specific gravity of 0.28 to 0.35 and a weight change rate of 3 wt% or less at 50 kg / cm 2 or more.

According to the present invention, after the mixture is subjected to a conventional process, the mixture is molded at 115 to 125 ° C. for 800 to 1000 seconds, and then again molded at 160 to 180 ° C. for 2400 to 2600 seconds, and then cooled to 60 to 80 ° C. It is also characterized in that the molded article is post-treated for 24 hours to produce pressure-resistant foamed parts.

NBR, which is a main component in pressure-resistant foamed particles according to the present invention, is prepared by copolymerization of butadiene (BD) and acrylonitrile (AN), and has a polarity to the polymer by the -C≡N group of acrylonitrile. It gives oil resistance and rubber elasticity to petroleum and increases the glass transition point (Tg). Therefore, the physical properties can be adjusted according to the change of copolymerization ratio or mixing prescription, and the content ratio of acrylonitrile (AN) The oil resistance of 28% is similar to that of chloroprene rubber, but the glass transition point is lowered and the oil resistance is very good at 48%, but the glass transition point is close to room temperature, which is not suitable for rubber use. Therefore, the content ratio of acrylonitrile (AN) is preferably about 28 to 48%.

In addition, the mixture added to NBR, which is the basic substance, has a ratio of NBR: 1.2: 1 to 1.5 by weight, of which phenol resin is used to increase the hardness of NBR, improve swelling resistance, and improve impact resistance. It is added 39 to 46% by weight based on the weight. If the lower limit of 39% by weight or less is added, the hardness is not sufficient, and if the upper limit of 46% by weight or more is added, the impact resistance becomes weak, so it should be within the above range.

In addition, carbon black greatly improves tear strength, tensile strength, and abrasion resistance of rich particles by affecting the size and hardness of the cell, which is 30 to 40% by weight for mutual affinity and optimum bonding with other components. It should be added within the range and the average particle size of 400 ~ 500㎛ is very preferable because it is possible to obtain a smaller and even bubbles than those of 150㎛ or less conventionally applied (see Fig. 5). Sulfur is used to increase the elasticity to reduce the size of residual permanent deformation. It is recommended to add 35 to 43% by weight in terms of the composition and chemical bonding of the entire mixture, and it should be 350 to 450 mesh fine particles to eliminate pore defects in the rich. The size of the particulate is important because it can.

As the blowing agent, azodicarbonamide (AC) is added in the range of 6.0 to 7.0% by weight, and there is an advantage that a smaller and more even cell can be obtained as compared to the conventional DPT (N, N'-dinitroso pentamethylene tetramine). If the input amount is less than the lower limit, foaming does not occur sufficiently, and the shape of the product is not formed properly. If the amount is excessive, foaming continues in the subsequent post-treatment process, resulting in a defect in size. In the above range I most preferred.

       In addition, it is commercially available worldwide with zinc oxide and stearic acid as usual, and is a mixture of metal salts, fatty acids and esters, and is characterized by the present invention of L-7, CZ and foaming aids, which are accelerators for improving rubber flow and deformability. Appropriate composition ratio with the said components is added in the range of about 3.5 to 5 weight%, 1.0 to 1.5 weight%, 0.5 to 1.0 weight%, 1.5 to 2.0 weight%, and 3.5 to 4.5 weight%, respectively.

The pressure-resistant foam rich according to the present invention consisting of such components is first prepared in the form of a sheet by kneading the basic material of NBR, and therein, phenol resin, carbon black, zinc oxide, stearic acid, sulfur, azodicarbonamide, By weighing the foaming aid, L-7 0.5 ~ 1.0 and CZ powders well within the above range, and evenly dispersing and mixing them as a whole, the best chemical bonds between each raw material can be induced to obtain desired physical properties and even properties of dough. Therefore, the selection and blending ratio of the raw materials and the mixing process between the raw materials are very important.

Thereafter, the resulting sheet-like dough is cut into a suitable size, followed by a molding process of vulcanizing and curing the cut dough.

In the molding process, primary molding is a step of forming pores in the foamed part at a low temperature, and secondary molding is a step of hardening the outer wall of the pores generated in the primary molding and forming the desired size and shape. The temperature range and time are important because even a slight difference in the treatment conditions as well as the mixing ratio can change the pressure resistance and specific gravity of the final rich (see FIGS. 1, 2 and 7).

In other words, when the molding temperature is low, foaming is not performed well, so the foaming ratio is low and rich in unvulcanized state is formed, hardness and pressure resistance are low, specific gravity is high. On the contrary, when the temperature is too high, the pores of the rich become large and the continuous bubble rate is high. Deposition and pressurization will result in defects. Therefore, it is preferable that the primary molding be treated for 800 to 1000 seconds at 115 to 125 ° C, and the secondary molding to be 2400 to 2600 seconds at 160 to 180 ° C.

And, in the case of pressure-resistant foam rich according to the present invention by the post-treatment at 60 ~ 80 ℃ for 24 hours after the first and second molding, as shown in Figure 4 unreacted raw material unlike when not treated in Figure 3 They are slowly reacted at a low temperature to achieve complete foaming, thereby increasing crosslinking and hardening of the cell walls, thereby increasing hardness and obtaining small and uniform bubbles, thereby improving pressure resistance (see FIG. 6).

In order to more easily understand the characteristics of the pressure-resistant foam according to the present invention of the above configuration is described by way of example, the present invention is not limited to this embodiment, if the person skilled in the art It will be understood that modifications and variations are possible within the scope of the claims without departing from the scope of the claims.

The percentages in the following examples are by weight.

Example 1

Phenolic resin 39%, MT thermal carbon black 40% of particle size 450㎛, zinc oxide 3.5%, stearic acid 1.5%, 400 mesh sulfur fine particles 42%, azodicarbonamide (AC) 6.5%, foaming aid 3.5 Several mixtures of powders of%, L-7 0.8% and CZ 1.7% were prepared in advance.

First, 100 parts by weight of NBR was kneaded well and then discharged in a sheet state so that the mixture of the respective containers was evenly mixed well so that the same effect was uniformly produced in the same lot.

After forming the pores by forming the mixture at 800 ° C. for 800 seconds, one group of samples was again molded at 170 ° C. for 2400 seconds (Samples 1 and 3), and the other group was at 2200 seconds at the same temperature. (Sample 4), another group was each molded for 3000 seconds (Sample 5) at the same temperature to form bubbles of desired size and shape.

After cooling the molded products of Samples 1, 3, 4, and 5, except for Sample 3, three groups of Samples 1, 4, and 5 were further worked at 60 ° C. for 24 hours.

Separately, for comparison, the same mixture was prepared except that the mixture of carbon black was replaced with an equivalent amount of semi reinforcing furnace (SRF) having a particle size of 100 μm instead of MT. Molded and worked up in the same manner (sample 2).

The specific gravity was measured in the performance of the obtained molded object, and both were 0.35 or less, and both were satisfactory in terms of specific gravity.

In addition, in order to confirm the internal pressure and the performance of the deposition of each sample was tested in the following manner. The actual rich fluid was LPG, but there was a risk of handling, so the hydraulic test was conducted.The hydraulic test was performed by first weighing the samples, putting them in the hydraulic tester, and then tightening the bolts of the tester. After setting for 15 minutes, the samples were taken out, the surface fluid was removed, and the appearance and abnormality of the appearance and the weight change rate were measured. In the immersion test, the weight change rate was measured after immersion in hexane at room temperature for 72 hours. And the same results as in 2, respectively.

Table 1

Weight before test (g) 30㎏ / ㎠, 15 minutes 40㎏ / ㎠, 15 minutes 50㎏ / ㎠, 15 minutes Weight (g) % Change Weight (g) % Change Weight (g) % Change Sample 1 9.2921 9.2975 0.06 9.3009 0.09 9.3080 0.17 Sample 2 9.2903 9.2963 0.06 9.3157 0.27 9.3732 0.89 Sample 3 9.2679 9.2744 0.07 9.2798 0.13 9.2898 0.24 Sample 4 9.2536 9.2608 0.07 9.1917 0.16 9.2133 0.39 Sample 5 5.5997 11.8944 112.53 Sample damage Sample damage

※ Test conditions: Pressurize in water at room temperature for 15 minutes, remove the surface fluid completely and weigh

            (The figures for each sample 1-5 are the average of those taken five)

TABLE 2

Weight before test (g) N-hexane Weight (g) % Change Sample 1 9.2760 9.2902 0.15 Sample 2 9.2742 9.2945 0.22 Sample 3 9.2751 9.2948 0.21 Sample 4 9.2704 9.2866 0.17 Sample 5 5.5481 5.5592 0.20

※ Test conditions: Determination of weight after removing fluid from the surface after immersion for 72 hours in room temperature hexane

            (The figures for each sample 1-5 are the average of those taken five)

From the above results, it was confirmed that the time and temperature during the post-treatment and molding in the present invention, the content of the components, and the difference in the particle size of the carbon black have a significant influence on the pressure resistance and specific gravity of the rich. That is, sample 2 had a lower internal pressure than sample 1, as shown in Table 1 and FIG. 5, and the weight change rate was higher than that of sample 1 at the high pressure when the post-treatment was not performed as in sample 3. When the temperature during the secondary molding is less than the temperature range specified in the present invention, the internal pressure is low, whereas when the temperature exceeds the upper limit of the above range, product defects are caused.

As described above, the pressure resistant foamed parts according to the present invention have almost no change in weight even at a high pressure of 50 kg / cm 2 or more. It has a specific gravity of 0.28 to 0.35, so it is lighter than LPG and always floats on fuel. It can withstand high pressures of 50kg / ㎠ and more, and can be optimally applied as a foam rich for LPG gas. It will be able to produce rich for LPG cars and large storage tanks in Korea, which will greatly contribute to the acquisition of foreign currency as a result of import substitution and export growth.

Claims (2)

In pressure-resistant foam parts for LPG cars and large storage tanks, To 100 parts by weight of NBR, 39 to 46% by weight of phenol resin, 30 to 40% by weight of carbon black, 3.5 to 5% by weight of zinc oxide, 1.0 to 1.5% by weight of stearic acid, 35 to 43% by weight of sulfur, and azodicarbonamide ( AC) 6.0-7.0 weight%, foaming aid 3.5-4.5 weight%, L-7 (mixture of metal salt, fatty acide & ester: 0.5-1.0 weight% of Kawaguchi Chemical Industries, Japan brand name), and CZ (N-cyclohexyl -Z-benzotiazolyl sulfenamide) The powder of the mixture consisting of 1.5 to 2.0% by weight is formed by being charged in the range of 120 to 150 parts by weight, and is formed at 115 to 125 ° C for 800 to 1000 seconds and then 2400 to 160 to 180 ° C. Re-molded for 2600 seconds, cooled, and the molding was post-treated at 60-80 ° C. for 24 hours;        The carbon black has a particle size of 400 to 550 탆, and the sulfur is fine particles of 350 to 450 mesh; Specific gravity 0.28 to 0.35 and the pressure-resistant foam rich, characterized in that the weight change rate is 3% by weight or less at 50kg / ㎠ or more. delete

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