JPH0710994B2 - Seal grease composition for gas holder - Google Patents

Description

The present invention relates to a seal grease for gas holders. Especially, the sealing performance between the side plate of the dry gas holder and the piston sealing packing, lubrication performance, gas resistance performance,
And the invention of a grease having corrosion resistance performance superior to that of conventional products.

[Prior Art and its Problems] In the dry gas holder for storing gas as shown in FIG. 2, oil or grease is supplied between the side plate 1 and the piston sealing packing 2 in the gas holder.
The piston seal mechanism is shown in FIG. The grease used is a sealing performance that prevents gas leakage, a lubricating performance that the piston moves smoothly and the piston seal packing does not wear, and a gas resistance performance that the lubricant itself does not change with respect to the active gas. Also, corrosion resistance is required so that the side plates and bottom plate of the holder do not corrode. It has been pointed out that calcium grease that is generally used has low heat resistance and that it tends to dry and solidify in high-temperature gas, and that clogging at the grease supply part easily occurs. Recently, an organic clay-treated grease having excellent heat resistance has been used. This grease has better heat resistance than calcium grease, but the active components in the gas components, such as H ₂ S gas and NH ₃ gas, change the organic material treated on the clay surface, and the sealing performance by softening. It has been pointed out that there is a problem in that the bottom plate is corroded or the grease accumulated on the bottom plate of the holder corrodes the bottom plate.

[Means for Solving Problems] In the present invention, in order to overcome these drawbacks, as a result of research, diurea compound I, that is, R ₁ —HNCONH—R ₂ —HNCONH—R ₁ (R ₁ has 8 to 10 carbon atoms). An alkyl group, R ₂ is a hydrocarbon group having at least one aromatic ring) and a methacrylate polymer II (R is an alkyl group, n = 6,000 to 15,000) When the weight ratio of the methacrylate polymer is 7: 3 to 8: 2 and the base oil is a mineral oil or a synthetic oil, the content is 2 to 10% by weight. It was found to have outstanding sealing performance, lubrication performance, gas resistance performance and corrosion performance.

The urea compound is most preferably a diurea compound, which is obtained from the reaction of 1 mol of diisocyanate and 2 mol of monoamine. Diisocyanate has at least one aromatic ring
Those having two are good. For example, tridene diisocyanate and diphenylmethane-4,4'-diisocyanate are effective. The monoamine is preferably an alkylamine having 8 to 10 carbon atoms. No effect could be found for those having an alicyclic ring or an aromatic ring.

This reaction is generally represented by the following formula.

_{OCN-R 2 -NCO + 2R 1} NH 2 → R 1 -HNCONH-R 2 -HNCONH-R 1 I R 1: an alkyl group having 8 to 10 carbon atoms R _2: hydrocarbon group other having at least one aromatic ring One of the molding agents, a methacrylate polymer, is added as a pour point depressant or a clay index improver to a lubricating oil or grease in an amount of 0.1 to 1.0% and is generally used. This prevents the formation of a network structure of the stone wax by adsorbing on the stone wax in the lubricating oil or crystallizing together with the stone wax, and exerts a pour point depressing action and a clay index improving action. However, the present invention does not utilize these properties. These do not directly act on the three-dimensional structure formed by the diurea compound, but form an independent three-dimensional structure and form a gel structure that mutually reinforces the diurea compound, thereby improving the sealing effect. No effect was found with other pour point depressants such as polyisobutylene and polyalkylstyrene. Therefore, the structure and molecular weight of the methacrylate polymer shown below become important, and R
Is an alkyl group, and n = 6,000 to 15,000 significantly improves the sealing property. When R is unsaturated, gas resistance is poor. If n is less than 6,000, aggregates do not form and disperse, and if n exceeds 15,000, the aggregates are too large and inhibit the growth of the three-dimensional structure formed by the diurea compound, resulting in gelation. Noh is reduced.

There is an optimum range for the mixing ratio of the diurea compound I and the methacrylate polymer II. That is, a mixing ratio in the range of I: II = 7: 3 to 8: 2 shows the best performance. When the proportion of the diurea compound I is higher than this, the growth of the methacrylate polymer II is hindered and the sealing performance is lowered. When the ratio of the methacrylate polymer II is very high, the diurea compound I
It inhibits the growth of the three-dimensional structure and significantly reduces the gelling ability.

The base oil to be composed is optimally a paraffinic mineral oil for mineral oil and a poly-α-olefin oil for synthetic oil. Other than this, the piston sealing and packing may be altered, and the effects of corrosive gas may increase.

2 to 10% by weight of the above mixture is added to the base oil to obtain the desired seal grease for gas holder. If it is less than 2% by weight, the sealing performance is inferior, and if it exceeds 10% by weight, the pipe resistance becomes large and it is not suitable for grease replenishment by a centralized greasing device.

In order to further improve gas resistance and corrosion resistance,
It is also possible to add a corrosion inhibitor, an anticorrosive agent, or the like.

For production, a general urea grease production method can be used. Diisocyanate is dissolved in a part of the base oil, and a solution in which an amine is dissolved in the rest of the base oil is added and reacted. After the reaction, heat to 150-200 ° C and then cool to room temperature. After that, add a methacrylate polymer,
The final grease is obtained by mixing and performing a three-stage roll mill treatment.

Examples and comparative examples of the present invention will be shown below. These performances are summarized in Table 1 together with commercial products.

Example 1 Paraffinic mineral oil (kinematic viscosity 67.24 cst at 40 ° C., viscosity index 10)
0) Add 23.5 g of tridendiisocyanate to 400 g and add 100
Heat to ℃. To this, 400 g of mineral oil and 26.5 g of decylamine
Was added and the mixture was stirred vigorously to complete the reaction. Then heat to 150 ° C. with stirring and then cool to room temperature. A mixture of 20.0 g of a methacrylate polymer (n = 10,000) dissolved in 130 g of mineral oil was added, mixed, and treated three times with a three-stage roll mill to obtain a workability of 416.
Get the grease of.

Example 2 Paraffinic mineral oil (kinematic viscosity at 40 ° C. 98.32 cst, viscosity index 9
5) Add 400g of tridendiisocyanate to 23.5g and add 100g
Heat to ℃. To this, 400 g of mineral oil and 26.5 g of decylamine
Was added and the mixture was stirred vigorously to complete the reaction. Then heat to 150 ° C. with stirring and then cool to room temperature. A mixture of 20.0 g of a methacrylate polymer (n = 8,000) in 130 g of mineral oil was added and mixed.
A grease with a workability of 425 is obtained by treating with a three-roll mill three times.

Example 3 To 400 g of poly-α-olefin (kinematic viscosity of 65.51 cst at 40 ° C., viscosity index of 145), 24.6 g of diphenylmethane diisocyanate
Add and heat to 100 ° C. To this, 400 g of poly-α-olefin dissolved in 25.4 g of octylamine was added, and the mixture was vigorously stirred to complete the reaction. Then heat to 150 ° C. with stirring and then cool to room temperature.
A solution of 15.0 g of a methacrylate polymer (n = 10,000) in 135 g of poly-α-olefin was added and mixed,
A grease with a workability of 430 is obtained by treating it with a three-stage roll mill three times.

Comparative Examples 1 to 3 Examples 1 and 2 are urea compounds using decylamine and Example 3 is octylamine, whereas Comparative Example 1 is dodecylamine, Comparative Example 2 is cyclohexylamine, and Comparative Example 3 is I'm using aniline.

Comparative Examples 4 and 5 Whereas Example 1 uses a methacrylate-based polymer with n = 10,000 and Example 2 uses a methacrylate-based polymer with n = 8,000, Comparative Example 4 uses a methacrylate-based polymer with n = 4,000, and Comparative Example 5 uses a methacrylate polymer with n = 20,000.

Comparative Examples 6 and 7 Whereas in Examples 1 and 2 the ratio of I diurea compound to II methacrylate-based polymer is I: II = 7: 3, and in Example 3 is I: II = 8: 2, Example 6 is I: II = 6: 4, and Comparative Example 7
Is I: II = 9: 1.

Comparative Examples 8 and 9 Instead of the methacrylate-based polymer of Example 1, Comparative Example 8 uses polyisobutylene and Comparative Example 9 uses polyalkylstyrene.

Table 1 shows a property comparison table of examples, comparative examples, and commercial products. From these comparative data it is clear that the composition according to the invention exhibits excellent properties. In addition, 1) in the table,
The test methods of 2) and 3) are as follows.

1) Seal performance test The seal performance test is shown in Fig. 4 for the equipment, and the test method is described below. Grease is applied to the top of the slide head 4 with a 1.0 mm thick frame, and then the air seal plate 5 is mounted. At that time, insert a spacer with a thickness of 0.5 mm in 6
Make the thickness uniform. After maintaining the specified temperature at 50 ° C., the air seal plate 5 is rotated at a peripheral speed of 2 m / min and the pressure is reduced at 50 l / min using a vacuum pump. While checking the state with the pressure gauge 7, the point at which the grease-coated film was broken, that is, the value immediately before the pressure dropped abruptly, was read as the breaking pressure (cmHg).

2) Coke gas exposure test Fill a pressure vessel with coke gas (0.15 kgf / cm ² ) from a COG gas holder at a steel mill. This container contains grease as it is in a petri dish, and 30% water is added to the grease.
It is made to contain water and then put a steel plate in a petri dish. In order to keep the pressure constant, coke gas was replenished every other day and left standing for 3 months. After the test, the anhydrous sample was evaluated for workability and grease appearance discoloration, and the 30% water-containing sample was evaluated for grease appearance discoloration and steel plate discoloration. The grease appearance and the evaluation criteria for the steel sheet are three levels: ◯: no change, Δ: gray discoloration, ×: black discoloration.

3) Abrasion test In order to evaluate the abrasion of rubber, which is a sealant, grease was evaluated with a tester shown in FIG. Piston 9 is motor 1
1. It reciprocates up and down by the crankshaft 12. Grooves are provided on the top and bottom of the piston, and an O-ring (JI
S-B2401, 1A, NBR) is mounted, and sliding friction occurs between the O-ring and the cylinder 8. 2.0 g of grease is applied to each O-ring, and the piston is operated at a speed of 100 times / minute for 100 hours at room temperature. The O-ring weight change rate (%) before and after the test was measured. In addition, the space 11
The compressor is filled with air at a pressure of 3.0 kgf / cm ² ,
The pressure change (kgf / cm ² ) after standing for 1 hour at room temperature was measured.

Further, the following is a result of an actual machine test of an example according to the present invention and a conventionally used grease in a certain steel mill. The conventional grease in the sub-tank for storing grease was switched to the grease of Example 1 according to the present invention,
With the m ³ COG (coke) gas holder, the amount of leak per unit time (m ³ / H) when left at 28,000 m ³ level was compared before and after switching.

The results are shown in FIG. Also, the amount of gas leak per unit time (m ³ / H) and its temperature correction value are shown.

In this way, the grease of the present invention has a gas leakage amount (m ³ / H) per unit time of 59% less than the conventional product, and the superiority of the seal performance of the grease of the present invention in an actual machine is clear.

[Advantages of the Invention] Since the seal grease for a gas holder according to the present invention is configured as described above, the sealing performance, the lubrication performance, the gas resistance, especially when used between the side plate of the dry gas holder and the piston sealing packing. It has an effect that the performance and the corrosion resistance are superior to the conventional products.

[Brief description of drawings]

FIG. 1 is a diagram showing the result of the actual test of the gas holder, and FIG.
The figure shows an example of a dry gas holder, FIG. 3 shows the piston seal mechanism, FIG. 4 shows the seal performance tester, and FIG. 5 shows the wear tester.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location C10M 145: 14) C10N 30:02 30:12 40:34 50:10 (72) Inventor Yutaka Uchiyama 4-5-15 Sakai, Musashino City, Tokyo (72) Inventor Tomio Nakayama 7-18 Nakamachi, Tsurumi-ku, Yokohama, Kanagawa Prefecture (72) Toshihiro Kanai 1-4, Oshimakami-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa

Claims (1)

[Claims] _{1. A} diurea represented by the general formula IR ₁ -HNCONH-R ₂ -HNCONH-R ₁ (R ₁ is an alkyl group having 8 to 10 carbon atoms, and R ₂ is a hydrocarbon group having at least one aromatic ring). With compound (R is an alkyl group, n = 6,000 to 15,000), a methacrylate polymer represented by the formula I diurea compound and a II methacrylate polymer in a weight ratio of 7: 3 to 8: 2, which is a mineral oil or a synthetic oil. A seal grease for a gas holder, which is contained in an amount of 2 to 10% by weight based on the base oil.