Method for predicting the lifetime of silicone oils and applications

Abstract

The present application relates to the field of lubricating oil, and discloses a life prediction method of silicone oil, which comprises the following steps: (1) determining the viscosity of silicone oil at different time points under the same temperature, and fitting a linear equation-1 of the viscosity of silicone oil changing with time; (2) determining the gelling time of silicone oil under different temperatures, fitting a linear equation-2 of the gelling time changing with temperature, and calculating parameters C and E / R value; (3) correcting the gelling time in the linear equation-2, calculating correction parameters a and b value, and obtaining a relationship formula-3 of the corrected gelling time and a and b; (4) constructing an expression relationship formula-4 of the viscosity of silicone oil and temperature according to the linear equation-1, the linear equation-2 and the relationship formula-3, and deducing the storage life t of silicone oil from the expression relationship formula-4. The method can be used for quickly predicting the service life or storage life of silicone oil under a specific use temperature, and is convenient for the selling party to evaluate the life of oil and the using party to master the oil replacement period.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lubricating oil, in particular to a life prediction method of silicone oil and application. BACKGROUND

[0002] With the decrease of the amount of lubricating oil used, the quality indicators are also declining, so it is not possible to judge whether it needs to be replaced by ordinary observation method, and a complete quality monitoring method is needed. Lubricating oil is subjected to high temperature, mechanical shear, catalytic oxidation and other effects during use, resulting in oxidative degradation, which reduces the performance indicators of the lubricating oil and affects the protection ability of the lubricating oil to the mechanical equipment, causing damage to the equipment, and even serious accidents. In order to prevent accidents caused by exceeding the service life of lubricating oil, most enterprises currently use the simplest method of regularly replacing lubricating oil. This method is simple and convenient, but in order to fully ensure safety, the lubricating oil is usually replaced early when it is not 100% failed, and some are replaced early when the lubricating oil still has more than half of the service life. The advance replacement of lubricating oil not only loses the service life, but also pollutes the environment if the replaced lubricating oil is not treated, and the treatment of the replaced lubricating oil will also increase the burden of the enterprise.

[0003] Currently, the monitoring of the service life of lubricating oil is mainly through the detection of the content of antioxidants in the lubricating oil, and the methods for detecting the content of antioxidants in the lubricating oil mainly include thermal oxidation method, colorimetric method and cyclic voltammetry method, etc. In addition, there is also a method of detecting the relationship between the friction factor and the number of rotations through a friction and wear test, observing the peak change in the infrared spectrum, and finally comparing the transmission peak percentage of different test samples with that of fresh oil to represent the periodic degradation time of the oil product.

[0004] The above lubricating oil life prediction methods can well evaluate the service life of lubricating oil, but they depend on the presence of antioxidants in the lubricating oil or the need for the lubricating oil to exist in the form of a thin film. Silicone oil has good oxidation resistance and almost no additional antioxidants, so there is currently a lack of life evaluation means for silicone oil products. SUMMARY

[0005] The purpose of the present application is to overcome the lack of complete life prediction method for silicone oil in the prior art, and to provide a life prediction method of silicone oil and application, which can be used to predict the service life of silicone oil or the storage life of silicone oil at a specific use temperature.

[0006] In order to achieve the above purpose, the present application provides a life prediction method of silicone oil, which comprises:

[0007] (1) Determining the viscosity of the silicone oil at different time points at the same temperature, fitting a linear equation of the change of the viscosity of the silicone oil with time -1;

[0008] (2) Determining the gelation time of the silicone oil at different temperatures, fitting a linear equation of the change of the gelation time with temperature -2, and calculating the parameters C and E / R value;

[0009] (3) Correcting the gelation time in the linear equation -2, calculating the corrected parameters a and b value, and obtaining a relationship between the corrected gelation time and a, b -3;

[0010] (4) According to the linear equation -1, the linear equation -2 and the relationship -3, constructing an expression relationship -4 between the viscosity of the silicone oil and the temperature, and deducing the storage life t of the silicone oil from the expression relationship -4;

[0011] Wherein, C is the thermal oxidation reaction constant of the silicone oil, E is the thermal oxidation reaction activation energy of the silicone oil, and R is the gas universal constant;

[0012] Wherein, a is the sampling amount of the silicone oil; and b is the surface area of the silicone oil in contact with air.

[0013] The second aspect of the present application provides the application of the aforementioned method in the life prediction of silicone oil products.

[0014] Through the above technical solution, the present application has the following technical effects:

[0015] In the field of lubricating oil, silicone oil products have good oxidation resistance and almost no additional antioxidants, so the life of silicone oil products cannot be judged by detecting the content of antioxidants in lubricating oil, and the prediction relies entirely on personal experience, and there is a lack of scientific method for evaluating the life of silicone oil products. The present application establishes a life prediction method for silicone oil products, which can be applied to the lubricating oil industry to predict the service life or storage life of silicone oil products under a specific use temperature, and is convenient for the seller to evaluate the life of the oil product and the user to master the oil replacement cycle. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a linear relationship between the viscosity of the silicone oil and time.

[0017] Figure 2 is a linear relationship between the gelation time of the silicone oil and temperature.

[0018] Figure 3 is a linear relationship between the gelation time of the silicone oil and the volume of the silicone oil.

[0019] Figure 4 is a linear relationship between the ratio of the gelation time of the silicone oil and the ratio of the volume of the silicone oil.

[0020] Figure 5is a linear relationship between silicone oil gel time and surface area.

[0021] Figure 6 is a linear relationship between the ratio of silicone oil gel time and the ratio of surface area.

[0022] Figure 7 is a linear relationship curve between silicone oil storage life t and corresponding temperature T. DETAILED DESCRIPTION

[0023] The endpoints of the ranges and any values claimed herein are presented as approximations only. The endpoints of the ranges and the individual values are not to be construed as being limited to the exact numerical values. Any numerical value, however, can include values approximating the value, as if the value were stated in a range from the value in question to the value in question. For example, the range of "1 to 5" can be interpreted as a range from "about 1 to about 5" and "about 1 to about 5", as well as "about 0.5 to about 6," "about 0.5 to about 6.1," and the like.

[0024] The first aspect of the present application provides a method for predicting the life of silicone oil, comprising the following steps: (1) measuring the viscosity of silicone oil at different time points at the same temperature, fitting a linear equation-1 of the change of silicone oil viscosity with time;

[0025] (2) measuring the gel time of silicone oil at different temperatures, fitting a linear equation-2 of the change of gel time with temperature, and calculating the parameters C and E / R value;

[0026] (3) correcting the gel time in the linear equation-2, calculating the corrected parameters a and b value, and obtaining a relationship-3 between the corrected gel time and a, b;

[0027] (4) constructing an expression relationship-4 between silicone oil viscosity and temperature according to the linear equation-1, the linear equation-2 and the relationship-3, and deducing the storage life t of silicone oil from the expression relationship-4;

[0028] Wherein, C is the thermal oxidation reaction constant of silicone oil, E is the thermal oxidation reaction activation energy of silicone oil, and R is the gas universal constant;

[0029] Wherein, a is the sampling amount of silicone oil; and b is the surface area of silicone oil in contact with air.

[0030] Silicone oil generally refers to a polysiloxane product with different degrees of chain structure that remains liquid at room temperature. It is generally divided into methyl silicone oil and modified silicone oil. The most commonly used methyl silicone oil, also known as ordinary silicone oil, has all methyl groups as its organic groups. It is prepared by hydrolysis of dimethyl dichlorosilane to obtain a primary condensed ring, cracking and rectification of the ring to obtain a low ring, and then adjusting the polymerization of the ring, end cap agent and catalyst to obtain a mixture with different degrees of polymerization, which is prepared by removing low boiling substances by vacuum distillation. In addition, the organic groups in methyl silicone oil can also be replaced by other organic groups to improve the performance of silicone oil and adapt it to various uses. Common other groups include hydrogen, ethyl, phenyl, chlorophenyl, trifluoropropyl, etc. such as methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen-containing silicone oil, methyl phenyl silicone oil, methyl chlorophenyl silicone oil, methyl ethoxy silicone oil, methyl trifluoropropyl silicone oil, methyl vinyl silicone oil, methyl hydroxyl silicone oil, ethyl hydrogen-containing silicone oil, hydroxyl hydrogen-containing silicone oil, and cyan-containing silicone oil, etc.

[0031] In the present application, the silicone oil refers to dimethyl silicone oil.

[0032] Silicone oil is a common lubricant and sealant, which has various properties and uses. Viscosity, as a basic physical property of fluid, is commonly used, including dynamic viscosity, kinematic viscosity, Engler viscosity, etc.

[0033] In the present application, the viscosity of silicone oil refers to the dynamic viscosity of silicone oil, which is used to represent its flow performance at different temperatures. The determination of the dynamic viscosity of silicone oil is carried out according to the method of GB / T265-88, and the instrument model is Y5641.

[0034] In the present application, the gelation time of silicone oil refers to the time required for liquid silicone oil to change from a flowable liquid state to a solid gel state at a specific temperature, which is used to represent the performance change time of silicone oil. However, in order to fully ensure safety, relevant personnel will replace the lubricating oil before the viscosity of silicone oil changes significantly. That is, the viscosity change error of silicone oil is 1%, and when the viscosity change is greater than 1%, it indicates that the properties of silicone oil have changed, and the oil needs to be replaced.

[0035] In the present application, when the silicone oil is at a normal temperature, t represents the storage life of the silicone oil; when the silicone oil is at a working temperature, t represents the service life of the silicone oil.

[0036] In the present application, the determination of the gelation time of silicone oil is carried out according to the method of SH / T 0337, and the instrument model is GWH-401.

[0037] In the present application, the fitting method of the linear equation adopts a conventional graphing software to construct a linear equation, for example, the graphing software used in the present application is Originpro 2022b.

[0038] In the present application, in step (1), the fitting method of linear equation of viscosity change of silicone oil with time includes: measuring the viscosity of silicone oil at different times at a certain temperature, respectively calculating lnη / η0 and ln(1-t / t*) values, and introducing the data into drawing software to perform linear equation fitting to obtain linear equation-1.

[0039] According to some embodiments of the present application, in step (1), the linear equation-1 satisfies the following formula:

[0040] lnη / η0=1 / (1-m)-ln(1-t / t*)(I)

[0041] In formula (I), η is the dynamic viscosity of silicone oil at a certain temperature, η0 is the initial dynamic viscosity of silicone oil, m is a constant greater than 1, t* is the gelation time of silicone oil, and t is the storage life of silicone oil.

[0042] In the present application, in step (2), the fitting method of linear equation of silicone oil gelation time change with temperature includes: recording the time t* required for silicone oil to change from liquid to solid gel at different temperatures T for silicone oil of the same weight and volume, respectively calculating lnt* and 1 / T values, and introducing the data into drawing software to perform linear equation fitting to obtain linear equation-2. n n

[0043] According to some embodiments of the present application, in step (2), the linear equation-2 satisfies the following formula:

[0044] Int*=C+E / (RT)(II)

[0045] Wherein, T is temperature, unit is Kelvin.

[0046] In the present application, since the sampling amount of silicone oil and the surface area of silicone oil in contact with air have an effect on the gelation time of silicone oil, correction parameters a and b are introduced to correct the gelation time in the linear equation-2 of silicone oil gelation time change with temperature.

[0047] According to some embodiments of the present application, in step (3), the correction process for calculating correction parameter a includes: measuring the gelation time of silicone oil of different volumes, fitting the equation of silicone oil gelation time change with silicone oil volume to obtain correction parameter a.

[0048] According to some embodiments of the present application, in step (3), the correction process for calculating correction parameter b includes: measuring the gelation time of silicone oil of different surface areas, fitting the linear equation of silicone oil gelation time change with silicone oil surface area to obtain correction parameter b. ​​

[0049] According to some embodiments of the present application, in step (3), the corrected gel time t' satisfies the following formula in relation to the correction parameters a and b:

[0050] t' = (V / V0 x a + 1) x (1 + S / S0 x b) t* (III)

[0051] wherein V is the actual amount of silicone oil, V0 is the test amount, S is the actual surface area of the silicone oil, and S0 is the test surface area.

[0052] According to some embodiments of the present application, the method comprises determining t' according to formulas (II) and (III).

[0053] In the present application, the volume of the silicone oil is determined by a measuring cylinder; the surface area of the silicone oil refers to the surface area of the silicone oil in contact with air, which is calculated by the radius of the evaporating dish.

[0054] According to some embodiments of the present application, according to formula (II) ; the relationship formula (III) is substituted by the above formula to obtain

[0055] In the present application, according to formula (I), 1-t / t* = e 1 / (1-m) η0 / η(c), the relationship formula (d) is substituted by formula (c) to obtain the relationship formula of viscosity and temperature.

[0056] According to some embodiments of the present application, in step (4), the expression relationship formula-4 of the viscosity of the silicone oil and temperature satisfies the following formula:

[0057]

[0058] wherein D = 1 / (1-m).

[0059] The second aspect of the present application provides the application of the above-mentioned method in the life prediction of silicone oil products.

[0060] In order to further illustrate the present application, the following examples are used for detailed description.

[0061] In the following examples of the present application, all raw materials are commercially available unless otherwise specified.

[0062] The air-blowing oven is purchased from Beijing Zhongke Huan Test Instrument Co., Ltd., and the instrument model number is DWH-401.

[0063] Example 1

[0064] ​This embodiment is used to illustrate the prediction method of the service life of silicone oil used in the present application.

[0065] (1) Constructing a linear equation of silicone oil viscosity change with time

[0066] Take 6 evaporating dishes (r = 6 cm), add 20 g of 350# dimethyl silicone oil (25℃ dynamic viscosity is 350 mm 2 / s) in each evaporating dish, put it into a forced air oven, set the temperature to 230℃, record the viscosity of silicone oil at different times, the specific data are as follows in Table 1:

[0067] Table 1

[0068] Time / h Kinematic viscosity at 40°C / mm 2 / s]]> 0 354.8 60 378.1 92 468.4 132 730.2 194 4550 204 +∞

[0069] From the common knowledge (Study on thermal oxidative stability of silicone oil, Synthetic Lubricating Material, Bai Shucheng, 1992), it is known that when methylphenyl silicone oil is thermally oxidized in air at a certain temperature, the change of viscosity η with time t can be expressed as: lnη / η0 = 1 / (1-m)-ln(1-t / t*)(I), wherein η is the dynamic viscosity of silicone oil at a certain temperature, η0 is the initial dynamic viscosity of silicone oil, m is a constant greater than 1, t* is the gelation time of silicone oil, and t is the storage life of silicone oil.

[0070] According to the data in Table 1, the values of lnη / η0 and ln(1-t / t*) are calculated respectively, and the results are shown in Table 2:

[0071] Table 2

[0072] Time / h 1n / η0 1n(1-t / t*) 60 0.0636 -0.3483 92 0.2778 -0.5996 132 0.7218 -1.0414 194 2.5513 -2.8332

[0073] Let lnη / η0 = Y and ln(1-t / t*) = X, fit the linear relationship of Y and X (such as Figure 1 ), and the linear equation of Y and X is Y = -0.9351x-0.2664, R 2 = 0.9999.

[0074] From Figure 1 , it can be seen that the linear relationship of lnη / η0-ln(1-t / t*) is a straight line, the correlation R 2 = 0.9999, which is greater than 0.98, indicating that the thermal aging process of the oil belongs to a free radical chain reaction process, which can be applied to the above formula (I).

[0075] (2) Constructing a linear equation of gelation time change with temperature

[0076] Take 5 evaporating dishes (r = 6 cm), add 20 g of 350# dimethyl silicone oil (25℃ dynamic viscosity is 350 mm 2Put into different temperature of the blast oven, such as temperature is set to 210℃, 230℃, 250℃, 270℃, 290℃, respectively, placed to the silicone oil no longer flow to the gel point, respectively, record to the gel point of time t n The specific gel time point is as shown in Table 3:

[0077] Table 3

[0078] Oxidation temperature (T) / °C Gel time (t*) / h 210 474 230 204 250 106 270 57 290 30

[0079] From the common knowledge (Study on thermal oxidation stability of silicone oil, Synthetic lubricating materials, Bai Shucheng, 1992), it can be known that the relationship between the gel time of methylphenyl silicone oil at different temperatures and temperature T can be expressed as: lnt*=C+E / RT (II), wherein C is the thermal oxidation reaction constant of silicone oil, E is the thermal oxidation reaction activation energy of silicone oil, R is the gas universal constant, and the unit of T is Kelvin (K=273.15+t (℃)).

[0080] According to the data in Table 3, the values of lnt* and 1 / T are calculated respectively, and the specific results are as shown in Table 4:

[0081] Table 4

[0082] 1 / T 1n(t*) 0.0021 6.1612 0.0020 5.3181 0.0019 4.6634 0.0018 4.0431 0.0018 3.4012

[0083] Let lnt*=Y, 1 / T=X, fit the linear relationship of lnt* and 1 / T, and the linear equation of lnt* and 1 / T is Y=9256.6X-13.029, R 2 =0.999, as shown in Figure 2 the linear relationship diagram of lnt*-1 / T is a straight line, the correlation R 2 =0.999, which is greater than 0.98, indicating that the linear equation of the gel time (t*) changing with temperature (T) meets the formula Int*=C+E / (RT) (II), and it can be known that E / R=9256.6 and C=-13.029.

[0084] Take the 350# dimethyl silicone oil with a dynamic viscosity of 350 mm 2 / s at 25℃ as an example, the gel time t* of the silicone oil is calculated under the condition of 25℃.

[0085] Substitute E / R=9256.6, C=-13.029 and T=273.13+25℃ into formula (II), and the gel time t* of the 350# dimethyl silicone oil at 25℃ is:

[0086] t*=e -13.029+9256.6 / (273.13+25)

[0087] =6.70×10 7 h=7645 years

[0088] (3) Correct the linear equation of the gel time with temperature change, calculate the correction parameters a and b values, and construct the relationship between the corrected gel time and a, b

[0089] Because the amount of silicone oil and its surface area in contact with air have an impact on the gel time, the correction parameters a and b are introduced in formula (II) to correct the gel time t*.

[0090] (I) Determination of correction parameter a

[0091] Take 6 evaporating dishes with the same radius (r = 4.5 cm), add different volumes of silicone oil to each evaporating dish, and put them into a forced air oven with a temperature setting of 230°C. Record the gel time of the silicone oil in each evaporating dish. The specific data are as follows in Table 5:

[0092] Table 5

[0093] Silicone oil volume, V / mL Gel time, t* / h 25 208.3 30 208.7 35 209 40 209.4 45 209.7 50 210

[0094] Let the gel time t* be Y and the volume of silicone oil V be X. Fit the linear relationship between Y and X (as shown in Figure 3 ), and the linear equation of Y and X is Y = 0.0674X + 206.67, R 2 = 0.9946.

[0095] Similarly, fit the linear relationship between the ratio of silicone oil volume ΔV and the ratio of gel time Δt* as shown in Figure 4 The relationship between the ratio of silicone oil volume and the ratio of gel time is Δt* = 0.0076ΔV + 0.9931, that is, the gel time increases by 0.76% when the volume of silicone oil doubles, and the value of a is 0.76%.

[0096] (II) Determination of correction parameter b

[0097] Take 5 evaporating dishes with different radii (the radii of the evaporating dishes are 2.5 cm, 3 cm, 3.5 cm, 4 cm, and 4.5 cm), add 50 mL of silicone oil to each evaporating dish, and put them into a forced air oven with a temperature setting of 230°C. Record the gel time t* of the silicone oil in each evaporating dish. The specific data are as follows in Table 6:

[0098] Table 6

[0099]

[0100]

[0101] Similarly, fit the linear relationship between the silicone oil surface area S and the gel time t*, and the linear relationship between the ratio of silicone oil surface area and the ratio of gel time as shown in Figure 5-6As shown, the relationship between the surface area of ​​silicone oil and the gelation time is t*=-0.0673S+214.09, and the relationship between the ratio of silicone oil surface area and the ratio of gelation time is Δt*=-0.0058ΔS+1.004. That is, if the surface area of ​​silicone oil doubles, the gelation time decreases by 0.58%, so the value of b is -0.58%.

[0102] Now, we correct t* in the formula lnt*=C+E / RT(II), and the corrected t* is t'. We introduce parameters a and b, and then... Figure 4 and Figure 6 We can deduce that the storage lifetime t is related to volume, surface area, and correction parameters a and b as follows: t(volume correction) = (V / V0×a+1)t * , t(surface area correction) = (1 + S / S0 × b)t*, combining the two equations, we can get t' = (V / V0 × a + 1) × (1 + S / S0 × b)t* (III).

[0103] From a 100L drum of No. 350 dimethyl silicone oil (radius 30cm, actual surface area of ​​silicone oil in contact with air is 2826cm²) 2 Take 2L of silicone oil sample and place it in a test barrel (the radius of the test barrel is 4.5cm, and the surface area of ​​the silicone oil sample in contact with air is 63.585cm²). 2 The sample was placed at room temperature (25℃) and the gelation time was recorded as 240h. The corrected gelation time t' of the bottled silicone oil was then calculated.

[0104] V (actual silicone oil usage 100L), V0 (test silicone oil sample usage 2L), and S (actual surface area of ​​silicone oil in contact with air 2826cm²) are used to define the silicone oil usage. 2 S0 (the surface area of ​​the silicone oil sample in contact with air is 63.585 cm²). 2 Let t* be the gelation time of the sample (7645 years). Substituting this into equation (III), the corrected gelation time t' of the bottled silicone oil at 25℃ is:

[0105] t'(25℃)=t*(25℃)×(1+100L÷2L×0.76%)×(1-2826cm 2 ÷63.585cm 2 ×0.58%)=t*(25℃)×1.02

[0106] = 7645 years × 1.02

[0107] =7830.5 years

[0108] (4) Construct an expression for the relationship between silicone oil viscosity and temperature change.

[0109] From the common knowledge (Study on thermal oxidation stability of silicone oil, Synthetic Lubricating Material, Bai Shucheng, 1992), η = β.M α (a), m = (1 - n) / α + 1 (b), wherein η is the dynamic viscosity of the silicone oil at a certain temperature, α and β are constants varying with temperature, and n is the reaction order, 0 < n < 1.

[0110] Let D = 1 / (1-m), and substitute it into formula (I), to obtain 1-t / t* = e D η0 / η(c).

[0111] According to formula lnt* = C + E / RT (II), it can be known that

[0112] Substitute (c) into (d), to obtain the relationship between the viscosity and the temperature as follows:

[0113] Substitute (c) into (d), to obtain the relationship between the viscosity and the temperature as follows:

[0114]

[0115] In the field of lubricating oil, the viscosity variation error of silicone oil is 1%, and when the viscosity variation is greater than 1%, it indicates that the properties of the silicone oil change, i.e. η0 / η = 1 / 1.01.

[0116] Substitute E / R = 9256.6 and C = -13.029 into relationship (IV), and the relationship between the viscosity and the temperature is:

[0117]

[0118] From the common knowledge, with the increase of the temperature, the dynamic viscosity of the silicone oil decreases, the value of α gradually decreases, and D continuously becomes larger to 0; with the decrease of the temperature, the viscosity increases, the value of α gradually increases, and D continuously becomes larger to negative infinity, and the curve of the time t of the viscosity variation of 1% of the silicone oil and the corresponding temperature T as the parameters will move upward (as shown in Figure 7 Therefore, at the same temperature, the greater the value of D is, the smaller the value of t is, and the minimum value of D known at present is -0.30, at T = 298.3 K (25°C at normal temperature), in the case of no impurities, under the test conditions (evaporating dish r = 6 cm, 20 g of the silicone oil is added into each evaporating dish), the storage life t is 2056 years. In the case of 100 L of the silicone oil and the actual surface area of 2289 cm 2 contacting with air, the storage life t is 2086.9 years.

[0119] Example 2

[0120] ​This embodiment is used to illustrate the prediction method of the service life of silicone oil used in the present application.

[0121] Take 5 evaporating dishes (r = 6 cm, S0= 113.04 cm 2 , V0= 20 mL), add 20 g of No. 350 dimethyl silicone oil (25 °C dynamic viscosity is 500 mm 2 / s) in each evaporating dish, and place them in different temperature air ovens, such as 210 °C, 230 °C, 250 °C, 270 °C, and 290 °C, respectively, until the silicone oil no longer flows to reach the gel point, and record the time t n *to reach the gel point, respectively. According to the above method, the linear relationship between lnt n *and 1 / T is fitted, and the linear equation of lnt n *and 1 / T is lnt n *= 9923.4 / T - 14.441.

[0122] In the viscosity change over time test at 210 °C, the formula lη / η0= 1 / (1-m) - ln(1-t / t*) can be used to obtain the value of D = 1 / (1-m) as -0.38.

[0123] According to the same method as in Example 1, take 6 evaporating dishes of the same radius (r = 4.5 cm), add different volumes of silicone oil in each evaporating dish, and place them in an air oven with a temperature setting of 230 °C, to obtain the volume correction parameter a as 0.75%. Similarly, the surface area correction parameter b is measured as -0.58% according to the same method as in Example 1, which is close to the data in Example 1, because the oxidation mechanism of the same silicone oil is the same, and the volume and surface area mainly affect the contact between oxygen and silicone oil, so the correction coefficients are close.

[0124] Comparative oil: select the same type of dimethyl silicone oil that has been in service at 100 °C for 8.5 years, with a 25 °C dynamic viscosity of 500 mm 2 / s, an air contact area of 20 x 20 cm 2 , a volume of 500 mL, V0= 20 mL, and S0= 113.04 cm 2 (r = 6 cm).

[0125] According to the formula lnt n *= 9923.4 / T - 14.441, the gel time point at 100 °C is 21.67 years, and through t' = (V / V0 x a + 1) x (1 + S / S0 x b) t n *, with a = 0.75% and b = -0.58%, t' = 25.2 years can be obtained.

[0126] Substitute D=-0.38, E / R=9923.4, C=-14.441 into the relational expression (IV), then the relational expression of viscosity and temperature is:

[0127]

[0128] It is obtained that t=8.34 years.

[0129] Therefore, it is known that the dynamic viscosity of the dimethyl silicone oil at 25 DEG C is 500 mm 2 / s at 100 DEG C, and the service life is 8.34 years under the same working condition.

[0130] In conclusion, the present application establishes a life prediction method of silicone oil, which can be applied to the lubricating oil industry to predict the service life or storage life of silicone oil at a specific use temperature, and is convenient for the selling party to evaluate the oil life and the using party to master the oil replacement cycle.

[0131] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including that various technical features are combined in any other suitable manner, and these simple modifications and combinations should also be considered as the disclosed content of the present application, and all fall within the protection scope of the present application.

Claims

1. A method for predicting the lifespan of silicone oil-based products, characterized in that, Includes the following steps: (1) At the same temperature, the viscosity of silicone oil at different time points was measured, and a linear equation for the change of silicone oil viscosity with time was fitted -1; (2) At different temperatures, the gelation time of silicone oil was measured, and a linear equation for the change of gelation time with temperature was fitted to 2, and the parameters C and E / R values ​​were calculated. (3) Correct the gelation time in the linear equation-2, calculate the correction parameters a and b, and obtain the relationship between the corrected gelation time and a and b -3; (4) Based on the linear equation-1, linear equation-2 and relation-3, construct the expression relationship-4 between silicone oil viscosity and temperature, and deduce the storage life t of silicone oil from the expression relationship-4; Where C is the thermal oxidation reaction constant of silicone oil, E is the activation energy of the thermal oxidation reaction of silicone oil, and R is the universal gas constant; Where a is the amount of silicone oil sampled; b is the surface area of ​​the silicone oil in contact with air; In step (3), the process of calculating the correction parameter a includes: measuring the gelation time of silicone oil of different volumes, fitting the equation of silicone oil gelation time with silicone oil volume change, and obtaining the correction parameter a. In step (3), the process of calculating the correction parameter b includes: measuring the gelation time of silicone oil with different surface areas, fitting a linear equation of the change of silicone oil gelation time with silicone oil surface area, and obtaining the correction parameter b.

2. The method according to claim 1, wherein, In step (1), the linear equation -1 satisfies the following formula: 1nη / η0 = 1 / (1-m)-1n(1-t / t*)(I) In formula (I), η is the dynamic viscosity of silicone oil at a certain temperature, η0 is the initial dynamic viscosity of silicone oil, m is a constant greater than 1, t* is the gelation time of silicone oil, and t is the storage life of silicone oil.

3. The method according to claim 2, wherein, In step (2), the linear equation -2 satisfies the following formula: Int*=C+E / (RT)(II) Where T represents temperature, and the unit is Kelvin.

4. The method according to claim 3, wherein, In step (3), the gelation time after correction is t', and its relationship with the correction parameters a and b satisfies the following formula: t'=(V / V0×a+1)×(1+S / S0×b)t* (III) Where V is the actual amount of silicone oil, V0 is the amount used in the experiment, S is the actual surface area of ​​silicone oil, and S0 is the surface area used in the experiment.

5. The method according to claim 4, wherein, The method includes determining t' according to formulas (II) and (III).

6. The method according to claim 5, wherein, The process of determining t' includes: determining t*= according to formula (II) ; the t*= Substituting into the aforementioned relation (III), we obtain t' = (V / V0 × a + 1) × (1 + S / S0 × b). .

7. The method according to claim 6, wherein, In step (4), the expression for the relationship between the viscosity of the silicone oil and temperature, Equation 4, satisfies the following formula: (IV) Where D = 1 / (1-m).

8. The application of the method according to any one of claims 1-7 in the prediction of the lifespan of silicone oil products.

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