A modified polysiloxane, its preparation method and application

Abstract

The present invention provides a modified polysiloxane, and also provides a preparation method of the modified polysiloxane, which comprises the following steps: a low hydrogen-containing silicone oil is mixed with allyl alcohol polyether and allyl glycidyl ether, and after heating, a catalyst is added to carry out an addition reaction to obtain the modified polysiloxane. The present invention also provides an application of the modified polysiloxane as a soil loosening agent, which is used for reducing soil bulk density and / or increasing soil porosity, and is also used for improving the water absorption and / or water retention of the soil. Applying the modified polysiloxane soil loosening agent of the present invention can effectively reduce soil bulk density, decrease soil compactness, and increase soil porosity, thereby significantly improving soil compaction and promoting crop growth. It is green and safe itself, and has important economic value and environmental significance.

Description

Technical Field

[0001] The present invention relates to the field of silicone, and particularly to a modified polysiloxane, a preparation method thereof, and an application thereof. Background Art

[0002] There is an equilibrium among the solid phase, liquid phase, and gas phase in the soil. However, under the influence of factors such as unreasonable irrigation or tillage methods, reduction of soil organic matter, and excessive application of inorganic fertilizers, this equilibrium will be broken, the soil structure will be damaged, and the soil surface will become hard under the action of cohesive force after drying, increasing the bulk density and density of the soil, resulting in soil compaction. Soil compaction is manifested as an increase in soil compactness, which first reduces the soil porosity, and then reduces the water permeability and hydraulic conductivity, causing a decrease in the soil's ability to receive precipitation and its ability to regulate water, which is not only unfavorable for the growth of green plants but also causes soil erosion. At the same time, in overly compacted soil, after the growth of crop roots is restricted, the ability to obtain nutrients is reduced, forcing an increase in the frequency and amount of topdressing, but the crop yield does not increase significantly.

[0003] Applying a soil loosening agent is one of the current measures to treat soil compaction. As a soil loosening agent, polysiloxane is applied to the soil, which will bond small soil particles in the soil to form large soil aggregates, creating a fluffy aggregate structure inside the compacted soil similar to that of healthy soil, increasing the porosity and the water infiltration rate, and thus reducing surface runoff and ground evaporation losses, achieving the effects of water and fertilizer conservation and promoting the normal growth of crop roots.

[0004] How to further improve the ability of polysiloxane as a soil loosening agent to improve soil compaction is a technical problem that the current industry urgently needs to solve and continuously focuses on, which is directly related to the economic benefits of the soil and crops and even environmental protection. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem of how to further improve the soil loosening ability of polysiloxane as a soil loosening agent.

[0006] To solve the above problems, the present invention adopts the following technical solutions:

[0007] The present invention provides a modified polysiloxane, and the structure of the modified polysiloxane is shown in Structural Formula I,

[0008] ;

[0009] wherein, 55 ≤ x ≤ 59, 6 ≤ y + z ≤ 11;

[0010] EO is ethoxy, and PO is propoxy; 20 ≤ m ≤ 30, 7 ≤ n ≤ 15.

[0011] Further, in Formula I, x = 57, y + z = 9.

[0012] Accordingly, the present invention further provides a method for preparing the above-mentioned modified polysiloxane, comprising the following steps:

[0013] A. Mix allyl alcohol polyether, low hydrogen-containing silicone oil, and allyl glycidyl ether;

[0014] B. After heating, add a catalyst and carry out an addition reaction to obtain the modified polysiloxane.

[0015] Furthermore, the hydrogen content of the low hydrogen-containing silicone oil is 0.13% - 0.16%, the viscosity is 130 - 150 cP, and the relative molecular mass is 4600 - 5200.

[0016] Furthermore, the structure of the allyl alcohol polyether is as shown in Structural Formula II,

[0017] ;

[0018] wherein, EO is ethoxy group, PO is propoxy group, 20 ≤ m ≤ 30, 7 ≤ n ≤ 15.

[0019] Furthermore, the relative molecular mass of the allyl alcohol polyether is 1800.

[0020] Furthermore, the mass ratio of the low hydrogen-containing silicone oil, the allyl alcohol polyether, and the allyl glycidyl ether is 94 - 106:300:4.

[0021] Furthermore, the catalyst includes chloroplatinic acid; the mass of the catalyst is 10 - 30 ppm of the total mass of the low hydrogen-containing silicone oil, the allyl alcohol polyether, and the allyl glycidyl ether;

[0022] In step B, the temperature for adding the catalyst and the addition reaction is 85 - 105 °C, and the time for the addition reaction is 3 - 4 hours; in step B, the addition reaction process is stirred.

[0023] Furthermore, before the mixing in step A, the allyl alcohol polyether is heated to 100 °C for half an hour to remove moisture; in step B, N2 is introduced into the reaction vessel during the addition reaction.

[0024] As a preferred embodiment of the preparation method of the present invention, the relative molecular mass of the low hydrogen-containing silicone oil is preferably 4920.

[0025] As a preferred embodiment of the preparation method of the present invention, F-6 is used as the allyl alcohol polyether.

[0026] As a preferred embodiment of the preparation method of the present invention, the structure of the allyl glycidyl ether is as shown in Structural Formula III,

[0027] .

[0028] Accordingly, the present invention further provides an application of the modified polysiloxane as a soil loosening agent for reducing soil bulk density and / or increasing soil porosity.

[0029] Furthermore, the modified polysiloxane as a soil loosening agent is used to improve the water absorption and / or water retention of the soil.

[0030] Compared with the prior art, the implementation of the present invention has the following beneficial effects:

[0031] 1. Applying the modified polysiloxane of the present invention as a soil loosening agent can effectively reduce soil bulk density, increase soil porosity, and at the same time significantly improve the water absorption and water retention of the soil, enabling the soil to absorb more water or fertilizers and effectively reducing water evaporation, thereby improving the long-term water holding capacity of the soil. Therefore, the modified polysiloxane of the present invention can effectively improve soil compaction and significantly improve soil performance from multiple dimensions.

[0032] 2. The present invention creatively uses a modified polysiloxane modified with polyether, etc. as a soil loosening agent. In addition to effectively improving problems such as soil compaction, it is non-toxic, harmless, green and safe to humans, and can be widely added to soil improvers, conditioners or fertilizers, having important economic value and environmental significance.

[0033] 3. The production process of the modified polysiloxane of the present invention is simple and the production cost is low, having advantages in large-scale application in agriculture. Detailed Embodiments

[0034] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific examples and comparative examples.

[0035] Table 1 shows the information of some raw materials used in the examples and comparative examples:

[0036] Table 1

[0037]

[0038] .

[0039] Example 1

[0040] Prepare 1000 kg of modified polysiloxane by a large-scale industrial production method:

[0041] The low hydrogen content silicone oil has a viscosity of 130 cP, a hydrogen content of 0.13%, and a relative molecular mass of about 4600.

[0042] Put 750 kg of allyl alcohol polyether into the reaction kettle. After stirring and heating to 100 °C for half an hour (to remove moisture), add 235 kg of the above-mentioned low hydrogen-containing silicone oil and 10 kg of allyl glycidyl ether. Add 10 g of chloroplatinic acid catalyst (dissolved in 800 mL of absolute ethanol) at 85 - 95 °C for addition reaction. After the reaction solution becomes transparent, react for another half an hour to obtain the modified polysiloxane. The total time of the addition reaction is 4 h, and N2 is introduced during the reaction.

[0043] The obtained modified polysiloxane has the structure shown in Formula I,

[0044]

[0045] where x = 55 and y + z = 6.

[0046] Example 2

[0047] Prepare the modified polysiloxane by a 1000 kg large-scale industrial production method:

[0048] The viscosity of the low hydrogen-containing silicone oil is 150 cP, the hydrogen content is 0.16%, and the relative molecular mass is about 5200.

[0049] Put 750 kg of allyl alcohol polyether into the reaction kettle. After stirring and heating to 100 °C for half an hour (to remove moisture), add 265 kg of the above-mentioned low hydrogen-containing silicone oil and 10 kg of allyl glycidyl ether. Add 10 g of chloroplatinic acid catalyst (dissolved in 800 mL of absolute ethanol) at 85 - 95 °C for addition reaction. After the reaction solution becomes transparent, react for another half an hour to obtain the modified polysiloxane. The total time of the addition reaction is 3.5 h, and N2 is introduced during the reaction.

[0050] The obtained modified polysiloxane has the structure shown in Formula I, where x = 59 and y + z = 11.

[0051] Example 3

[0052] Prepare the modified polysiloxane by a 1000 kg large-scale industrial production method:

[0053] The viscosity of the low hydrogen-containing silicone oil is 135 cP, the hydrogen content is 0.14%, and the relative molecular mass is 4920.

[0054] Put 750 kg of allyl alcohol polyether into the reaction kettle. After stirring and heating to 100 °C for half an hour (to remove moisture), add 250 kg of the above-mentioned low hydrogen-containing silicone oil and 10 kg of allyl glycidyl ether. Add 10 g of chloroplatinic acid catalyst (dissolved in 800 mL of absolute ethanol) at 95 - 105 °C for addition reaction. After the reaction solution becomes transparent, react for another half an hour to obtain the modified polysiloxane. The total time of the addition reaction is 3.5 h, and N2 is introduced during the reaction.

[0055] The obtained modified polysiloxane structure is shown in Formula I, where x = 57 and y + z = 9.

[0056] Comparative Example 1

[0057] The viscosity of the low hydrogen-containing silicone oil is 195 cP, the hydrogen content is 0.18%, and the relative molecular mass is about 8000.

[0058] 750 kg of allyl alcohol polyether was put into a reaction kettle. After stirring and heating to 100 °C for half an hour (to remove moisture), 408 kg of the above-mentioned low hydrogen-containing silicone oil and 10 kg of allyl glycidyl ether were added. 10 g of chloroplatinic acid catalyst (dissolved in 800 mL of absolute ethanol) was added at 90 - 100 °C for an addition reaction. After the reaction solution became transparent, the reaction was continued for another half an hour to obtain the modified polysiloxane. The total time of the addition reaction was 3.5 h, and N2 was introduced during the reaction. The obtained modified polysiloxane structure is shown in Formula I.

[0059] Comparative Example 2

[0060] The difference between this comparative example and Comparative Example 1 is that: the viscosity of the low hydrogen-containing silicone oil is 130 cP, the hydrogen content is 0.07%, and the relative molecular mass is about 8000. The obtained modified polysiloxane structure is shown in Formula I.

[0061] Soil bulk density refers to the dry weight of unit volume of soil under natural field conditions, which directly affects the soil compactness and is another important index to characterize the soil structure. The lower the soil bulk density, the better the soil structure, air permeability and water permeability. Soil porosity is the percentage of soil pore volume in the total soil volume. The number of soil pores determines the total amount of gas and liquid phases in the soil, and at the same time reflects the ability of the soil to coordinate water and air, affects the soil performance and the exertion of soil fertility, and further affects the growth of crops. Therefore, for the improvement evaluation of soil compaction, multiple dimensions such as soil bulk density and soil porosity are selected as the investigation factors for subsequent effect tests.

[0062] Effect Example 1

[0063] Hydrogen-containing silicone oil with hydrogen at both ends (hydrogen content 0.14%, relative molecular mass about 6000) was selected as other silicone soil loosening agents. The modified polysiloxanes prepared in Examples 1, 2, 3 and Comparative Examples 1, 2, and the aforementioned other silicone soil loosening agents were taken as the soil loosening agents for each group.

[0064] The soil used in this effect example was organic nutrient soil (sand soil, pH 6.2 - 7.0, general type). The soil loosening agents for each group were diluted with water at a mass ratio of 1:10 and evenly sprayed on the soil, and then the soil was stirred until the loosening agent was evenly penetrated. It was left for 15 days for soil improvement. The soil improvement effects of the soil loosening agents for each group were measured, and the measurement method was as follows:

[0065] 1) Soil bulk density: Determined by the core method. Take undisturbed soil samples with a core sampler, dry them to a constant weight at 105 °C without destroying the soil structure, record the dry weight (W0), and the soil bulk density ρ b = W0 / V, where V is the volume of the core sampler.

[0066] 2) Porosity: Calculated from the bulk density and soil specific gravity. The porosity ø = (1 - ρ b / 2.65) * 100%, where 2.65 is the soil particle density.

[0067] 3) Water absorption (immersion method): Take undisturbed soil samples with a core sampler, dry them to a constant weight at 105 °C without destroying the soil structure, record the dry weight (W0), then immerse the dried soil in water, take out the soil sample after standing for 24 hours, blot the excess water on the surface with filter paper, and record the weight (W1).

[0068] Water absorption W m = (W1 - W0) / W1 * 100%.

[0069] 4) Water retention (evaporation method): Take undisturbed soil samples with a core sampler, immerse them in water and let them stand for 24 hours, then take out the soil sample, blot the excess water on the surface with filter paper, and record the weight (W x ). Place the soil sample in a room temperature environment, record the weight change until it reaches a constant weight, and record the final weight (W y ).

[0070] Water retention W n = (W y - W0) / (W x - W0) * 100%.

[0071] 5) pH value: Measured using a pH meter.

[0072] The measurement results of each group are shown in Table 2.

[0073] Table 2 Improvement effects of soil loosening agents on soil

[0074]

[0075] As can be seen from Table 2:

[0076] Compared with the blank control (without applying soil loosening agent), when the modified polysiloxanes in Examples 1 - 3 are used as soil loosening agents respectively, the soil bulk density is significantly reduced, from 1.43 g / cm 3 to below 1.26 g / cm 3 ; while the porosity, water absorption and water retention are all significantly improved. The porosity increases from 46.04% to over 52%, the water absorption increases from 61.20% to over 74%, and the water retention increases from 35.14% to over 40%.

[0077] Compared with applying the modified polysiloxanes of Comparative Examples 1-2 as soil loosening agents to the soil, the comprehensive improvement effect of applying the modified polysiloxanes of Examples 1-3 to the soil is better. Among them, compared with Comparative Example 1, Examples 1-3 have significantly improved the soil bulk density, porosity, water absorption and water retention. The soil bulk density has decreased from 1.37 g / cm 3 to 1.26 g / cm 3 Hereinafter, the porosity has increased from 48.30% to more than 52%, the water absorption has increased from 63.31% to more than 74%, and the water retention has increased from 35.14% to more than 40%.

[0078] Compared with applying other organosilicon soil loosening agents (hydrogen-terminated silicone oil) as soil loosening agents to the soil, the soil bulk density, porosity, water absorption and water retention have also been improved to varying degrees when applying the modified polysiloxanes of Examples 1-3.

[0079] In summary, using the modified polysiloxane of the embodiment of the present invention as a soil loosening agent can reduce the soil bulk density (the lower the bulk density, the looser the soil), increase the soil porosity, and at the same time significantly improve the soil water absorption and water retention, enabling the soil to absorb more water or fertilizers and effectively reducing water evaporation, thereby improving the long-term water holding capacity of the soil. The preparation method of the present invention performs polyether modification and epoxy modification on low-hydrogen-content silicone oil (hydrogen content 0.13% - 0.16%). The comprehensive improvement effect of the prepared modified polysiloxane on the soil is significantly better than that of other modified polysiloxanes of low-hydrogen-content silicone oil (the hydrogen content of the low-hydrogen-content silicone oil is lower than 0.13% or higher than 0.16%) or hydrogen-terminated silicone oil.

[0080] The above-disclosed are only the preferred embodiments of the present invention. Of course, the scope of rights of the present invention cannot be limited thereby. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. Use of a modified polysiloxane as a soil loosening agent, characterized in that, The preparation method of the modified polysiloxane comprises the following steps: A. Mix allyl alcohol polyether, low hydrogen content silicone oil and allyl glycidyl ether; B. After raising the temperature, add a catalyst and carry out an addition reaction to obtain the modified polysiloxane; The hydrogen content of the low hydrogen content silicone oil is 0.13% - 0.16%, the viscosity is 130 - 150 cP, and the relative molecular mass is 4600 - 5200; The structure of the allyl alcohol polyether is shown in Structural Formula II, ； wherein, EO is ethoxy group, PO is propoxy group, 20 ≤ m ≤ 30, 7 ≤ n ≤ 15.

2. Use of the modified polysiloxane according to claim 1 as a soil loosening agent, characterized in that, The relative molecular mass of the allyl alcohol polyether is 1800.

3. Use of the modified polysiloxane according to claim 1 as a soil loosening agent, characterized in that, The mass ratio of the low hydrogen content silicone oil, the allyl alcohol polyether and the allyl glycidyl ether is 94 - 106:300:4; 4. The application of the modified polysiloxane as claimed in claim 1 as a soil loosening agent, characterized in that, The catalyst comprises chloroplatinic acid; the mass of the catalyst is 10 - 30 ppm of the total mass of the low hydrogen content silicone oil, the allyl alcohol polyether and the allyl glycidyl ether; In step B, the temperature for adding the catalyst and carrying out the addition reaction is 85 - 105 °C, and the time for the addition reaction is 3 - 4 hours; in step B, the addition reaction process is stirred.

5. Use of the modified polysiloxane according to claim 1 as a soil loosening agent, characterized in that, Before the mixing in step A, the allyl alcohol polyether is heated to 100 °C for half an hour to remove moisture; in step B, N2 is introduced into the reaction vessel during the addition reaction.

6. Use of the modified polysiloxane according to claim 1 as a soil loosening agent, characterized in that, For reducing soil bulk density and / or increasing soil porosity.

7. Use of the modified polysiloxane as claimed in claim 1 as a soil loosening agent, characterized in that, For improving the water absorption and / or water retention of soil.

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