Preparation method of high-molecular-weight MQ resin

Abstract

The invention discloses a preparation method of high molecular weight MQ resin. The method comprises the following steps: 1) taking a water glass solution with the silicon dioxide concentration of 14-22wt% and the SiO2 / Na2O molar ratio of n1 as a raw material, carrying out condensation polymerization in the presence of an acid catalyst, aging, and blocking to obtain high-molecular-weight MQ resin, the weight-average molecular weight of which is marked as M1; and 2) marking the target molecular weight of the resin as M0, marking the corresponding SiO2 / Na2O molar ratio as n0, calculating the value of n0 according to the limiting conditions of a specific formula, and substituting the value of n0 into the step 1) to react and keep a single variable to prepare the high-molecular-weight MQ resin, thereby realizing further precise regulation and control of the weight-average molecular weight of the resin.

Description

Technical Field

[0001] The present invention relates to a polymer material, and in particular to a preparation method of a high molecular weight MQ resin. Background Art

[0002] Organosilicon resin products have excellent thermal stability, electrical insulation, weather resistance, and biocompatibility, etc., and are widely used in industries such as national defense and military, electrical industry, light industrial products, rubber and plastics, food hygiene, etc., playing an irreplaceable role in the field of materials. MQ resin is a kind of organosilicon resin, which is a polysiloxane with a special structure formed by hydrolysis and condensation of monofunctional (M group) linkages R3SiO 1 / 2 and tetrafunctional (Q group) linkages SiO 4 / 2 Generally, MQ resin is a double-layer three-dimensional structure of a dense spheroid, with the core part connected by Si-O chains and a cage-like SiO2 with a higher density; the shell part is surrounded by a layer of R3SiO with a lower density 1 / 2 MQ resin has many properties such as good adhesiveness, heat resistance, weather resistance, and flexibility, etc., and has great application value in industry. The main application fields include pressure-sensitive adhesives and liquid silicone rubbers, etc.

[0003] The preparation processes of MQ resin mainly include the water glass method and the TOES method, among which the water glass method is more widely used in industry. Water glass, also known as sodium silicate, is an inorganic substance soluble in water, with the chemical formula Na2O·nSiO2. Generally speaking, due to its high reaction activity, the water glass method process is easy to prepare MQ resins with a relatively large molecular weight. For example, Patent CN109438709A provides a method for preparing a high molecular weight methyl MQ resin. Under stirring, a mixed solution of acid, sodium silicate solution, organic solvent, trimethylchlorosilane, and high-purity hydrocarbon solvent is successively added into a three-necked flask, and then reflux reaction is carried out. High-purity hydrocarbon solvent is added again, and then stirred, allowed to stand, and layered; the organic layer is washed with water 2 - 3 times to obtain a high molecular weight methyl MQ resin. By changing the reaction temperature, reaction time of the sodium silicate aqueous solution and the acid, and the concentration of hydrochloric acid, MQ resins with different molecular weights are obtained.

[0004] However, precisely because of the high reaction activity of the water glass method, it is significantly affected by the concentration of reactants, reaction time, and reaction temperature. When actually regulating the molecular weight of MQ resin, the fluctuation of the actual molecular weight value is relatively large. Especially when preparing high molecular weight MQ resin, the fluctuation of the molecular weight usually reaches more than 2000, and it is difficult to achieve precise regulation of the molecular weight. Summary of the Invention

[0005] To solve the above technical problems, the present invention proposes a preparation method for high molecular weight MQ resin. This method provides a new idea for preparing high molecular weight MQ resin, which can precisely control the molecular weight and achieve a molecular weight error of at least 100 or less.

[0006] A preparation method for high molecular weight MQ resin, comprising the following steps:

[0007] 1) Using a water glass solution with a silica concentration of 14 - 22 wt% and an SiO2 / Na2O molar ratio of n1 as the raw material, carrying out a polycondensation reaction in the presence of an acid catalyst, and capping after aging to obtain a high molecular weight MQ resin, the weight average molecular weight of which is denoted as M1;

[0008] 2) Denote the target molecular weight of the resin as M0, and the corresponding SiO2 / Na2O molar ratio as n0. Calculate the value of n0 according to the limiting conditions of the following formula, and substitute it into step 1) to prepare a high molecular weight MQ resin while keeping a single variable in the reaction, so as to achieve further precise control of the weight average molecular weight of the resin;

[0009] If 250 ≤ M1 - M0 ≤ 500, 0.03 ≤ n1 - n0 ≤ 0.1;

[0010] If 500 < M1 - M0 ≤ 1000, 0.1 < n1 - n0 ≤ 0.2;

[0011] If 1000 < M1 - M0 ≤ 2000, 0.2 < n1 - n0 ≤ 0.4;

[0012] If 250 ≤ M0 - M1 ≤ 500, 0.03 ≤ n0 - n1 ≤ 0.1;

[0013] If 500 < M0 - M1 ≤ 1000, 0.1 < n0 - n1 ≤ 0.2;

[0014] If 1000 < M0 - M1 ≤ 2000, 0.2 < n0 - n1 ≤ 0.4.

[0015] As a preferred embodiment of the present invention, in step 1), the value range of n1 is 2.6 - 3.6, for example, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, etc.

[0016] As a preferred embodiment of the present invention, the acid catalyst is at least one of hydrochloric acid and sulfuric acid;

[0017] Preferably, the addition amount of the acid catalyst should make the pH of the reaction system less than 2, and preferably, the pH value of the reaction system is less than 1.

[0018] As a preferred embodiment of the present invention, the temperature of the polycondensation reaction is 10 - 30 °C.

[0019] As a preferred embodiment of the present invention, the aging time is 1 - 10 min.

[0020] As a preferred embodiment of the present invention, the capping agent used for capping is one or more of trimethylchlorosilane, hexamethyldisiloxane, and tetramethyldivinyldisiloxane;

[0021] Preferably, the addition amount of the capping agent is 20 - 40 wt%, based on the weight of the sodium silicate solution.

[0022] As a preferred embodiment of the present invention, at least one of methanol, ethanol, isopropanol, and butanol is added as an auxiliary agent during capping;

[0023] Preferably, the addition amount of the auxiliary agent is 20 - 40 wt%, based on the weight of the sodium silicate solution.

[0024] As a preferred embodiment of the present invention, the capping is carried out at a temperature of 50 - 90 °C;

[0025] Preferably, the reaction time for capping is 1 - 6 h.

[0026] As a preferred embodiment of the present invention, the polycondensation reaction uses a tubular reactor or a tank reactor.

[0027] An MQ resin with a weight average molecular weight of 15,000 - 30,000 can be prepared by the method of the present invention.

[0028] Through continuous research, the present invention has found that the ratio of silicon dioxide to sodium oxide in sodium silicate determines the existence form of silicon dioxide therein, and this form affects its reaction behavior, thereby causing certain differences in the molecular weight of the product. Thus, it has been discovered that by changing the molar ratio of silicon dioxide to sodium oxide, MQ resins with different molecular weights can be obtained, and since this characteristic has a relatively limited influence on the reaction activity, the change range of the molecular weight is also relatively small. Using this characteristic, the present invention proposes a method for preparing a high molecular weight MQ resin, which can achieve the purpose of precisely controlling the molecular weight of the MQ resin and can achieve good effects in practical applications. Detailed Embodiments

[0029] The following further illustrates the present invention through specific examples. The examples described in the present invention are only for the illustration of the present invention and do not limit the scope of the present invention.

[0030] In the present invention, raw materials and reagents can be obtained through commercial channels without special instructions. The information of the main raw materials in the examples is as follows:

[0031] Sodium silicate: Laizhou water glass, < 37%;

[0032] Hydrochloric acid: Far East Fine Chemical Co., Ltd., 36%;

[0033] Hexamethyldisiloxane: Aladdin, 99%;

[0034] Trimethylchlorosilane: Aladdin, 99%;

[0035] Isopropanol / Ethanol: Sinopec, 99%;

[0036] Tetramethyldivinyldisiloxane: Aladdin, 99%.

[0037] In the examples, the resin molecular weight was quantified by GPC:

[0038] Gel Permeation Chromatograph (GPC): Gel Permeation Chromatograph: Equipped with a unit pump, column oven, differential detector, auto sampler and chromatographic workstation. Chromatographic conditions: Chromatographic columns Agilent PLgel MIXED-D 5um ($7.5×300mm), PLgel MIXED-E 3um (7.5x300mm), mobile phase: ethyl acetate, flow rate: 1.0 mL / min, column temperature: 40 °C, detector temperature: 40 °C, injection volume: 10 uL s.

[0039]

Example 1

[0040] (1) A water glass solution with a SiO2 concentration of 20% and a SiO2 / Na2O molar ratio (n1) of 3.18 and 14% hydrochloric acid were continuously pumped into a tubular reactor at speeds of 500 g / min and 250 g / min respectively, ensuring that the pH of the reaction was below 0.50, controlling the reaction temperature at 20 °C. The reactor was equipped with a strong mixing device. After the hydrochloric acid and water glass materials were mixed evenly, they were pumped into another section of the tubular reactor for aging, and the aging time was 2 min. The products in the tubular reactor, isopropanol, hexamethyldisiloxane, and trimethylchlorosilane were continuously added to the capping reactor at speeds of 750 g / min, 150 g / min, 350 g / min, and 140 g / min respectively. The capping reaction temperature was 80 °C, and the capping reaction time was 3 hours. The product after capping was washed with water and subjected to GPC measurement, and its weight average molecular weight was 23,890 (M1).

[0041] (2) According to the requirements of different target molecular weights M0 in Table 1, the following formula was used to calculate n0 respectively, and then n0 was substituted into step (1), and the experiment was repeated while controlling it as a single variable. The molecular weight of the obtained product was denoted as (M2):

[0042] If 250 ≤ M1 - M0 ≤ 500, 0.03 ≤ n1 - n0 ≤ 0.1;

[0043] If 500 < M1 - M0 ≤ 1000, 0.1 < n1 - n0 ≤ 0.2;

[0044] If 1000 < M1 - M0 ≤ 2000, 0.2 < n1 - n0 ≤ 0.4;

[0045] If 250 ≤ M0 - M1 ≤ 500, 0.03 ≤ n0 - n1 ≤ 0.1;

[0046] If 500 < M0 - M1 ≤ 1000, 0.1 < n0 - n1 ≤ 0.2;

[0047] If 1000 < M0 - M1 ≤ 2000, 0.2 < n0 - n1 ≤ 0.4.

[0048] Table 1. Adjustment schemes for resins with different target molecular weights under the reaction conditions of Example 1

[0049]

[0050]

[0051]

Example 2

[0052] (1) Continuously feed a water glass solution with a SiO2 concentration of 14% and a SiO2 / Na2O molar ratio (n1) of 3.00 and 12% hydrochloric acid into a stirred reactor at speeds of 500 g / min and 250 g / min respectively, ensuring that the pH of the reaction is below 0.50, controlling the reaction temperature at 10 °C. The reactor is equipped with a strong mixing device. After the hydrochloric acid and water glass materials are mixed evenly, aging is carried out for 1 min. Feed the product in the stirred reactor, butanol, hexamethyldisiloxane, and trimethylchlorosilane into the capping reactor at speeds of 750 g / min, 100 g / min, 350 g / min, and 100 g / min respectively. The capping reaction temperature is 50 °C, and the capping reaction time is 6 hours. Wash the capped product with water and conduct GPC measurement, and its weight-average molecular weight is 16850 (M1).

[0053] (2) According to the requirements of different target molecular weights M0 in Table 2, calculate n0 by applying the following formula respectively, and then substitute n0 into step (1) to control it as a single variable and repeat the experiment. The molecular weight of the obtained product is denoted as (M2):

[0054] If 250 ≤ M1 - M0 ≤ 500, 0.03 ≤ n1 - n0 ≤ 0.1;

[0055] If 500 < M1 - M0 ≤ 1000, 0.1 < n1 - n0 ≤ 0.2;

[0056] If 1000 < M1 - M0 ≤ 2000, 0.2 < n1 - n0 ≤ 0.4;

[0057] If 250 ≤ M0 - M1 ≤ 500, 0.03 ≤ n0 - n1 ≤ 0.1;

[0058] If 500 < M0 - M1 ≤ 1000, 0.1 < n0 - n1 ≤ 0.2;

[0059] If 1000 < M0 - M1 ≤ 2000, 0.2 < n0 - n1 ≤ 0.4.

[0060] Table 2. Adjustment schemes for resins with different target molecular weights under the reaction conditions of Example 2

[0061] M0 n0 M2 Solution 1 16600 2.97 16682 Solution 2 16350 2.90 16279 Solution 3 16000 2.83 16049 Solution 4 15850 2.80 15721 Solution 5 15350 2.70 15208 Solution 6 14850 2.60 15010 Solution 7 17100 3.03 17062 Solution 8 17350 3.10 17385 Solution 9 17600 3.15 17719 Solution 10 17850 3.20 17882 Solution 11 18350 3.30 18277 Solution 12 18850 3.40 18929

[0062]

Example 3

[0063] (1) Continuously inject a water glass solution with a SiO2 concentration of 22% and a SiO2 / Na2O molar ratio (n1) of 3.10 and 18% hydrochloric acid into a tubular reactor at speeds of 500 g / min and 250 g / min respectively, ensuring that the pH of the reaction is lower than 0.50, controlling the reaction temperature at 30 °C. The reactor is equipped with a strong mixing device. After the hydrochloric acid and water glass materials are mixed evenly, they are injected into another section of the tubular reactor for aging, and the aging time is 10 min. The products in the tubular reactor, ethanol, hexamethyldisiloxane, and tetramethyldivinyldisiloxane are continuously added to the capping reactor at speeds of 750 g / min, 200 g / min, 350 g / min, and 200 g / min respectively. The capping reaction temperature is 90 °C, and the capping reaction time is 1 hour. The product after capping is washed with water and subjected to GPC measurement, and its weight-average molecular weight is 26100 (M1).

[0064] (2) According to the requirements of different target molecular weights M0 in Table 3, calculate n0 by applying the following formulas respectively, and then substitute n0 into step (1) to control it as a single variable and repeat the experiment. The molecular weight of the obtained product is denoted as (M2):

[0065] If 250 ≤ M1 - M0 ≤ 500, 0.03 ≤ n1 - n0 ≤ 0.1;

[0066] If 500 < M1 - M0 ≤ 1000, 0.1 < n1 - n0 ≤ 0.2;

[0067] If 1000 < M1 - M0 ≤ 2000, 0.2 < n1 - n0 ≤ 0.4;

[0068] If 250 ≤ M0 - M1 ≤ 500, 0.03 ≤ n0 - n1 ≤ 0.1;

[0069] If 500 < M0 - M1 ≤ 1000, 0.1 < n0 - n1 ≤ 0.2;

[0070] If 1000 < M0 - M1 ≤ 2000, 0.2 < n0 - n1 ≤ 0.4.

[0071] Table 3. Adjustment Schemes for Resins with Different Target Molecular Weights under the Reaction Conditions of Example 3

[0072] M0 n0 M2 Solution 1 25850 3.07 25771 Solution 2 25600 3.00 25505 Solution 3 25350 2.95 25399 Solution 4 25100 2.90 25187 Solution 5 24600 2.80 24690 Solution 6 24100 2.70 24182 Solution 7 26350 3.13 26219 Solution 8 26600 3.20 26671 Solution 9 26850 3.25 26712 Solution 10 27100 3.30 27003 Solution 11 27600 3.40 27710 Solution 12 28100 3.50 28190

[0073]

Example 4

[0074] (1) A water glass solution with a SiO2 concentration of 17% and a SiO2 / Na2O molar ratio (n1) of 2.80 and a 35% sulfuric acid solution are continuously fed into a tubular reactor at speeds of 500 g / min and 100 g / min respectively, ensuring that the pH of the reaction is below 0.50. The reaction temperature is controlled at 25°C. The reactor is equipped with a strong mixing device. After the hydrochloric acid and the water glass materials are mixed evenly, they are fed into another tubular reactor for aging, and the aging time is 8 min. The products in the tubular reactor, isopropanol, hexamethyldisiloxane, and trimethylchlorosilane are continuously added to the capping reactor at speeds of 750 g / min, 150 g / min, 350 g / min, and 200 g / min respectively. The capping reaction temperature is 70°C, and the capping reaction time is 2 hours. The product after capping is washed with water and subjected to GPC measurement, and its weight-average molecular weight is 19200 (M1).

[0075] (2) According to the requirements of different target molecular weights M0 in Table 4, the following formulas are respectively used to calculate n0, and then n0 is substituted into step (1), and the experiment is repeated with it as a single variable. The molecular weight of the obtained product is recorded as (M2):

[0076] If 250 ≤ M1 - M0 ≤ 500, 0.03 ≤ n1 - n0 ≤ 0.1;

[0077] If 500 < M1 - M0 ≤ 1000, 0.1 < n1 - n0 ≤ 0.2;

[0078] If 250 ≤ M0 - M1 ≤ 500, 0.03 ≤ n0 - n1 ≤ 0.1;

[0079] If 500 < M0 - M1 ≤ 1000, 0.1 < n0 - n1 ≤ 0.2;

[0080] If 1000 < M0 - M1 ≤ 2000, 0.2 < n0 - n1 ≤ 0.4.

[0081] Table 4. Adjustment Schemes for Resins with Different Target Molecular Weights under the Reaction Conditions of Example 4

[0082]

[0083]

[0084]

Example 5

[0085] (1) Continuously feed a water glass solution with a SiO2 concentration of 19% and a SiO2 / Na2O molar ratio (n1) of 3.40 and a 30% hydrochloric acid solution into a tubular reactor at speeds of 500 g / min and 100 g / min respectively, ensuring that the pH of the reaction is below 0.50, controlling the reaction temperature at 25 °C. The reactor is equipped with a strong mixing device. After the hydrochloric acid and water glass materials are mixed evenly, they are fed into another section of the tubular reactor for aging, and the aging time is 3 min. The products in the tubular reactor, isopropyl alcohol, hexamethyldisiloxane, and trimethylchlorosilane are continuously added to the capping reactor at speeds of 750 g / min, 150 g / min, 350 g / min, and 100 g / min respectively. The capping reaction temperature is 75 °C, and the capping reaction time is 3 hours. The product after capping is washed with water and subjected to GPC measurement, and its weight average molecular weight is 22100 (M1).

[0086] (2) According to the requirements of different target molecular weights M0 in Table 5, calculate n0 by applying the following formulas respectively, and then substitute n0 into step (1), and repeat the experiment with it controlled as a single variable. The molecular weight of the obtained product is denoted as (M2):

[0087] If 250 ≤ M1 - M0 ≤ 500, 0.03 ≤ n1 - n0 ≤ 0.1;

[0088] If 500 < M1 - M0 ≤ 1000, 0.1 < n1 - n0 ≤ 0.2;

[0089] If 1000 < M1 - M0 ≤ 2000, 0.2 < n1 - n0 ≤ 0.4;

[0090] If 250 ≤ M0 - M1 ≤ 500, 0.03 ≤ n0 - n1 ≤ 0.1;

[0091] If 500 < M0 - M1 ≤ 1000, 0.1 < n0 - n1 ≤ 0.2;

[0092] Table 5. Adjustment schemes for resins with different target molecular weights under the reaction conditions of Example 5

[0093] M0 n0 M2 Solution 1 21850 3.37 21732 Solution 2 21600 3.3 21529 Solution 3 21350 3.25 21307 Solution 4 21100 3.2 21024 Solution 5 20600 3.1 20528 Solution 6 20100 3 20153 Solution 7 22350 3.43 22419 Solution 8 22600 3.5 22781 Solution 9 22850 3.55 22802 Solution 10 23100 3.6 23118

[0094] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the method of the present invention, several improvements and supplements can be made, and these improvements and supplements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of high molecular weight MQ resin, characterized in that, It includes the following steps: 1) Using a water glass solution with a silica concentration of 14 - 22 wt% and an SiO2 / Na2O molar ratio of n1 as the raw material, carrying out a polycondensation reaction in the presence of an acid catalyst, aging and then capping to obtain a high molecular weight MQ resin, and recording its weight average molecular weight as M1; 2) Denote the target molecular weight of the resin as M0, and the corresponding SiO2 / Na2O molar ratio as n0. Calculate the value of n0 according to the limiting conditions of the following formula, and substitute it into step 1) to prepare a high molecular weight MQ resin while keeping a single variable in the reaction, so as to further accurately control the weight average molecular weight of the resin; If 250 ≤ M1 - M0 ≤ 500, 0.03 ≤ n1 - n0 ≤ 0.1; If 500 < M1 - M0 ≤ 1000, 0.1 < n1 - n0 ≤ 0.2; If 1000 < M1 - M0 ≤ 2000, 0.2 < n1 - n0 ≤ 0.4; If 250 ≤ M0 - M1 ≤ 500, 0.03 ≤ n0 - n1 ≤ 0.1; If 500 < M0 - M1 ≤ 1000, 0.1 < n0 - n1 ≤ 0.2; If 1000 < M0 - M1 ≤ 2000, 0.2 < n0 - n1 ≤ 0.

4.

2. The preparation method of the high molecular weight MQ resin according to claim 1, characterized in that, In step 1), the value range of n1 is 2.6 - 3.

6.

3. The preparation method of the high molecular weight MQ resin according to claim 1, characterized in that, The acid catalyst is at least one of hydrochloric acid and sulfuric acid; Preferably, the addition amount of the acid catalyst should make the pH of the reaction system less than 2, and preferably, the pH value of the reaction system is less than 1.

4. The preparation method of the high molecular weight MQ resin according to any one of claims 1-3, characterized in that, The temperature of the polycondensation reaction is 10 - 30 °C.

5. The preparation method of the high molecular weight MQ resin according to any one of claims 1-4, characterized in that, The aging time is 1 - 10 min.

6. The preparation method of the high molecular weight MQ resin according to any one of claims 1-5, characterized in that, The capping agent used for capping is one or more of trimethylchlorosilane, hexamethyldisiloxane, and tetramethyldivinyldisiloxane; Preferably, the addition amount of the capping agent is 20 - 40 wt%, based on the weight of the water glass solution.

7. The preparation method of the high molecular weight MQ resin according to any one of claims 1-6, characterized in that, At least one of methanol, ethanol, isopropanol, and butanol is added as an auxiliary agent during capping; Preferably, the addition amount of the auxiliary agent is 20 - 40 wt%, based on the weight of the water glass solution.

8. The preparation method of the high molecular weight MQ resin according to any one of claims 1-7, characterized in that, The capping is carried out at a temperature of 50 - 90 °C; Preferably, the reaction time of the capping is 1 - 6 h.

Images