Low ring, ultra-low viscosity dimethicone and method for preparing the same
Ultra-low viscosity dimethyl silicone oil was prepared by using the condensation-polymerization reaction of α,ω-dihydroxy polysiloxane linear and end-capping agent, which solved the problem of separating cyclosiloxane impurities and achieved high-yield and high-purity environmentally friendly production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG XINAN CHEM IND GRP CO LTD
- Filing Date
- 2023-03-07
- Publication Date
- 2026-07-03
AI Technical Summary
Existing technologies for preparing low-viscosity dimethyl silicone oil suffer from problems such as difficulty in separating cyclosiloxane impurities, complex processes, and severe pollution, making it difficult to meet environmental protection requirements.
Ultra-low viscosity dimethyl silicone oil was prepared by condensation and dehydroxylation reaction of α,ω-dihydroxy polysiloxane linear body, polymerization inhibitor and catalyst under vacuum conditions, followed by the addition of end-capping agent for equilibrium polymerization, and finally the addition of terminator and quenching catalyst, thus avoiding the generation of cyclosiloxane impurities.
It has achieved the preparation of ultra-low viscosity dimethyl silicone oil with high yield (99.9%) and high purity, simplified the separation process, met environmental protection requirements, and reduced production costs.
Smart Images
Figure CN116253886B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of organosilicon synthesis, specifically relating to a low-cyclic, ultra-low viscosity dimethyl silicone oil and its preparation method. Background Technology
[0002] Dimethyl silicone oil is colorless and odorless, with high transparency. It possesses characteristics such as heat resistance, cold resistance, minimal viscosity change with temperature, water resistance, low surface tension, and physiological inertness, making it widely used in industries such as daily chemicals, machinery, electrical engineering, textiles, coatings, pharmaceuticals, and food. Ultra-low viscosity dimethyl silicone oil (<5 cSt) exhibits even lower surface tension and volatility, making it suitable as a cosmetic carrier and a key ingredient or additive in many daily cosmetic products.
[0003] On June 27, 2018, the European Chemicals Agency (ECHA) officially published on its website a new 19th batch of 10 SVHCs, adding octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) to the list of Substances of Very High Concern (SVHCs), thus restricting the content of cyclosiloxanes. It also stipulated that from January 31, 2020, "wash-off cosmetics" containing either D4 or D5 at a concentration of 0.1% or higher must not be placed on the market. Therefore, with increasingly stringent requirements for environmental protection and health standards, the requirement for low-cyclic compounds in methyl silicone oils will become a future trend.
[0004] Low-viscosity dimethyl silicone oil is commonly synthesized industrially using two methods: one involves equilibrating a low molar mass of dimethylcyclosiloxane with a capping agent, hexamethyldisiloxane. After the reaction, approximately 15% of octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecylcyclohexasiloxane (D6) remain and need to be removed. However, D4, D5, and D6, along with decamethylcyclotetrasiloxane (MD2M), dodecylpentasiloxane (MD3M), and tetradecylcyclohexasiloxane (MD4), are present. MD4 and D6 have very similar boiling points, making them difficult to separate and affecting the quality of low-viscosity polysiloxanes. Another method is to use trimethylchlorosilane and dimethyldichlorosilane as raw materials to prepare low-viscosity methyl silicone oil through hydrolysis, water washing, and rebalancing. This method has a high conversion rate and produces low D4, D5, and D6 content, but the process is complicated, requires high purity of monomers, and produces hydrochloric acid as a byproduct during the reaction. Multiple water washing and neutralization processes are required to remove acid and salt, resulting in a large amount of wastewater and waste residue, which is not environmentally friendly.
[0005] In view of this, the present invention is hereby proposed. Summary of the Invention
[0006] To address the aforementioned technical problems, this invention provides a method for preparing a low-cyclic, ultra-low viscosity dimethyl silicone oil.
[0007] The preparation method of this invention is simple, with mild and easy-to-implement conditions, and generates no wastewater or waste salt, making it environmentally friendly and suitable for industrial production. Furthermore, the basic principle of this invention is a non-equilibrium reaction, which does not produce octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecylcyclohexasiloxane (D6). The yield of the target product can reach 99.9%, eliminating the need for subsequent separation and purification processes.
[0008] To achieve the above-mentioned technical effects, the basic concept of the technical solution adopted by the present invention is as follows:
[0009] A method for preparing a low-cyclic, ultra-low viscosity dimethyl silicone oil, wherein the viscosity of the dimethyl silicone oil is ≤5 cSt;
[0010] The preparation method includes: first, placing α,ω-dihydroxy polysiloxane linear, polymerization inhibitor and catalyst under vacuum conditions to carry out condensation and dehydroxylation reaction to obtain prepolymer; then, adding end-capping agent to the prepolymer to carry out equilibrium polymerization; after the reaction is completed, adding terminator and quenching catalyst to obtain ultra-low viscosity dimethyl silicone oil.
[0011] As an example, the viscosity of the α,ω-dihydroxypolysiloxane lineare is 20-100 cst, preferably 50-90 cs; the volatile matter content is less than 0.5%, preferably less than 0.1%, and more preferably less than 0.03%.
[0012] As an example, the polymerization inhibitor is a low-viscosity methyl silicone oil with a viscosity of 5-50 cs, preferably with a viscosity of 10-20 cs.
[0013] As an example, the mass ratio of α,ω-dihydroxypolysiloxane lineare to polymerization inhibitor is 1:0.05 to 1:0.3, preferably 1:0.1 to 1:0.2.
[0014] As an example, the catalyst is phosphazene chloride, and the amount added is 5-30 ppm, preferably 10-20 ppm, of the total mass of α,ω-dihydroxypolysiloxane linear, polymerization inhibitor and capping agent.
[0015] As an example, the temperature of the condensation dehydroxylation reaction is 100-160℃, preferably 100-120℃; the vacuum condition is 0.1-2kPa, preferably 0.4-0.8kPa; and the reaction time is 0.5-2h, preferably 0.5-1h.
[0016] As an example, the mass ratio of the capping agent to the prepolymer is 1:1 to 6:1, preferably 2:1 to 4:1.
[0017] As an example, the capping agent is hexamethyldisiloxane.
[0018] As an example, the equilibrium polymerization reaction temperature is 60-120℃, preferably 70-90℃; the equilibrium polymerization reaction time is 1-8h, preferably 3-8h.
[0019] As an example, the terminating agent is selected from diethylamine, n-butylamine, hexamethylsilazane, or cyclotrisilazane, preferably hexamethylsilazane or cyclotrisilazane.
[0020] This invention provides a low-cyclic, ultra-low viscosity dimethyl silicone oil, which is obtained according to any of the above preparation methods.
[0021] As an example, the low-cyclic, ultra-low viscosity dimethyl silicone oil has a cyclic content of <1000ppm and a viscosity of <5cst.
[0022] Compared with the prior art, the present invention has the following advantages:
[0023] 1. The method of the present invention uses α,ω-dihydroxypolysiloxane (linear form) as raw material, which reduces the step of cracking and rearrangement into dimethylcyclosiloxane (DMC), significantly reduces the incidence of side reactions, and has a high conversion rate of target product, thus having a certain cost advantage in industry.
[0024] 2. This invention provides a novel method for preparing ultra-low viscosity dimethyl silicone oil, with a yield of over 99% and high product purity.
[0025] 3. Furthermore, by adjusting parameters such as the amount of capping agent, linear agent, and reaction temperature, the present invention controls the total cyclosiloxane content to ≤300ppm, thereby improving the purity of ultra-low viscosity dimethyl silicone oil and simplifying the subsequent separation and purification process.
[0026] 4. Furthermore, the present invention uses a non-equilibrium catalyst, which does not produce cyclic compounds during the reaction process, and the product does not require purification. Impurities such as D4, D5 and D6 can meet the requirements of the European Chemicals Agency (ECHA) regulations, and ultra-low cyclic compounds and ultra-low viscosity dimethyl silicone oil can be prepared. Attached Figure Description
[0027] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.
[0028] Figure 1 This is a gas chromatogram of the ultra-low viscosity dimethyl silicone oil prepared in Example 1 of the present invention.
[0029] Figure 2 This is a gas chromatogram of the ultra-low viscosity dimethyl silicone oil prepared in Example 9 of the present invention.
[0030] Figure 3 This is a gas chromatogram of the ultra-low viscosity dimethyl silicone oil prepared in Example 10 of the present invention.
[0031] Figure 4 This is a gas chromatogram of the ultra-low viscosity dimethyl silicone oil prepared in Example 13 of the present invention.
[0032] Figure 5 This is a gas chromatogram of the ultra-low viscosity dimethyl silicone oil prepared in Example 14 of this invention.
[0033] Figure 6 This is a gas chromatogram of the ultra-low viscosity dimethyl silicone oil prepared in Example 15 of the present invention.
[0034] Figure 7 This is a gas chromatogram of the ultra-low viscosity dimethyl silicone oil prepared in Example 16 of this invention.
[0035] The above are only a part of the detection diagrams for some examples of this invention. Due to space limitations, they are not provided one by one. Detailed Implementation
[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0037] The meanings of the English abbreviations in the embodiments of this invention are as follows:
[0038] MM (hexamethyldisiloxane), MDM (octamethyltrisiloxane), MD2M (decamethyltetrasiloxane), MD3M (dodecylpentasiloxane) or MD4M (tetradecylhexasiloxane), MD5M (hexadecylheptasiloxane), MD6M (octadecyloctasiloxane), MD7M (eicosylnonasiloxane), MD8M (docosahexamethyldecasiloxane), MD9M (tetradecylundasiloxane), MD 10 M (hexamethyldodecylsiloxane), MD 11 M (octa-octamethyltridecylsiloxane), MD 12 M (trimethyltetradecylsiloxane).
[0039] The gas chromatography-mass spectrometry (GC-MS) conditions for testing the ultra-low viscosity dimethyl silicone oil prepared in this invention are as follows:
[0040] Gas chromatography-mass spectrometry (GC-MS): Agilent 7890A-5975C, equipped with split / splitless injection ports.
[0041] Chromatographic column: DB-5MS (60m × 0.25mm × 0.25μm)
[0042] Column temperature: 35℃ (hold for 1 min), increase to 300℃ at a rate of 10℃ / min (hold for 20 min).
[0043] Inlet temperature: 305℃;
[0044] Carrier gas: Helium, purity ≥ 99.999% (volume fraction);
[0045] Injection volume: 0.2 μL;
[0046] Injection method: split ratio 100:1;
[0047] Flow rate: 0.8 mL / min;
[0048] It should be noted that non-polar capillary columns that achieve equivalent separation can also be selected. Additionally, peaks with concentrations below 0.1% in GC-MS chromatograms cannot be displayed, and due to page limitations in the application text, some peaks of substances with lower concentrations are not visible to the naked eye at the equivalent display scale.
[0049] In the following examples, the α,ω-dihydroxypolysiloxane linear body is referred to simply as the linear body.
[0050] Example 1
[0051] 100 parts by mass of linear polymer with a viscosity of 60 cst and a volatile content of 0.1% were added to a reactor equipped with a mechanical stirrer, thermometer and reflux pipe. Then 10 parts by mass of 10 cst methyl silicone oil polymerization inhibitor and 0.01 parts by mass of phosphazene chloride (19 ppm) were added. The reaction was carried out at 120 °C and 0.6 kPa absolute pressure, with nitrogen gas purging and stirring for 0.5 h. Most of the hydroxyl groups were removed by condensation to obtain the prepolymer.
[0052] Then, the temperature was lowered to 90°C, and 400 parts by mass of hexamethyldisiloxane were added dropwise. The reaction temperature was controlled at 90°C, and after equilibration and telogenization for 3 hours, 0.024 parts of hexamethylsilazane were added to quench the catalyst. The reaction was continued with stirring for 0.5 hours to remove a small amount of residual hydroxyl groups, yielding low-chain MD. n A mixture of M (n = 1-10) yields a low-viscosity dimethyl silicone oil with a viscosity of 1.38 cst, a D4 content of 0.07%, a D5 content of 0.02%, and the contents of low-chain siloxanes and cyclic siloxanes are shown in Table 1.
[0053] Example 2
[0054] The method and steps of this embodiment are the same as those of Embodiment 1, except that the equilibrium polymerization reaction time is 1 hour, and a low-viscosity dimethyl silicone oil with a viscosity of 1.39 cst, a D4 content of 0.14%, and a D5 content of 0.06% is obtained.
[0055] Example 3
[0056] The method and steps in this embodiment are the same as in Embodiment 1, except that the equilibrium polymerization reaction time is 5 hours, resulting in low-viscosity dimethyl silicone oil with a viscosity of 1.38 cst, a D4 content of 0.04%, and a D5 content of 0.01%.
[0057] Example 4
[0058] The method and steps in this embodiment are the same as in Embodiment 1, except that the equilibrium polymerization reaction time is 8 hours, resulting in low-viscosity dimethyl silicone oil with a viscosity of 1.37 cst, a D4 content of 0.05%, and a D5 content of 0.01%.
[0059] Example 5
[0060] The method and steps in this embodiment are the same as in Embodiment 1, except that the equilibrium polymerization reaction temperature is 70°C, and a low-viscosity dimethyl silicone oil with a viscosity of 1.38 cst, a D4 content of 0.10%, and a D5 content of 0.03% is obtained.
[0061] Example 6
[0062] The method and steps of this embodiment are the same as those of Embodiment 1, except that the equilibrium polymerization reaction temperature is 80°C, and a low-viscosity dimethyl silicone oil with a viscosity of 1.38 cst, a D4 content of 0.09%, and a D5 content of 0.03% is obtained.
[0063] Example 7
[0064] The method and steps of this embodiment are the same as in embodiment 1, except that: 100 parts by mass of a linear agent with a viscosity of 50 cst and a volatile content of 0.15% are added to obtain a low-viscosity dimethyl silicone oil with a viscosity of 1.36 cst, a D4 content of 0.08%, and a D5 content of 0.03%.
[0065] Example 8
[0066] The method and steps of this embodiment are the same as in embodiment 1, except that: 100 parts by mass of a linear agent with a viscosity of 90 cst and a volatile content of 0.1% are added to obtain a low-viscosity dimethyl silicone oil with a viscosity of 1.39 cst, a D4 content of 0.06%, and a D5 content of 0.02%.
[0067] Example 9
[0068] The method and steps of this embodiment are the same as in embodiment 1, except that: 20 parts by mass of 20cst methyl silicone oil polymerization inhibitor are added to obtain low viscosity dimethyl silicone oil with a viscosity of 1.47cst, D4 content of 0.06%, and D5 content of 0.02%.
[0069] Example 10
[0070] The method and steps of this embodiment are the same as in embodiment 1, except that: 20 parts by mass of 50 cst methyl silicone oil polymerization inhibitor are added to obtain low viscosity dimethyl silicone oil with a viscosity of 1.62 cst, D4 content of 0.05%, and D5 content of 0.01%.
[0071] Example 11
[0072] The method and steps in this embodiment are the same as in Embodiment 1, except that: 0.048 parts by mass of diethylamine are added when the reaction is terminated to obtain a low-viscosity dimethyl silicone oil with a viscosity of 1.38 cSt, a D4 content of 0.08%, and a D5 content of 0.02%.
[0073] Example 12
[0074] The method and steps of this embodiment are the same as those of Embodiment 1, except that: when terminating the reaction, 0.036 parts by mass of cyclotrisilazane are added to obtain low-viscosity dimethyl silicone oil with a viscosity of 1.37 cst, a D4 content of 0.07%, and a D5 content of 0.03%.
[0075] Example 13
[0076] The method and steps of this embodiment are the same as those of Embodiment 1, except that: 0.004 parts of phosphazene chloride (19 ppm) are added during the first step of condensation and dehydroxylation reaction, and 100 parts of hexamethyldisiloxane are added during the second step of equilibrium polymerization to obtain low-viscosity dimethyl silicone oil with a viscosity of 2.44 cst, D4 content of 0.46%, and D5 content of 0.21%.
[0077] Example 14
[0078] The method and steps of this embodiment are the same as those of Embodiment 1, except that: 0.008 parts of chlorophosphazene (19 ppm) are added during the first step of condensation and dehydroxylation reaction, and 300 parts of hexamethyldisiloxane are added during the second step of equilibrium polymerization to obtain low-viscosity dimethyl silicone oil with a viscosity of 1.54 cst, D4 content of 0.15%, and D5 content of 0.06%.
[0079] Example 15
[0080] The method and steps of this embodiment are the same as those of Embodiment 1, except that: 0.012 parts of phosphazene chloride (19 ppm) are added during the first step of condensation and dehydroxylation reaction, and 500 parts of hexamethyldisiloxane are added during the second step of equilibrium polymerization to obtain low-viscosity dimethyl silicone oil with a viscosity of 1.29 cst, D4 content of 0.03%, and D5 not detected.
[0081] Example 16
[0082] The method and steps of this embodiment are the same as those of Embodiment 1, except that: 0.014 parts of chlorophosphazene (19 ppm) are added during the first step of condensation and dehydroxylation reaction, and 600 parts of hexamethyldisiloxane are added during the second step of equilibrium polymerization to obtain low-viscosity dimethyl silicone oil with a viscosity of 1.21 cst, D4 content of 0.02%, and D5 not detected.
[0083] Table 1
[0084] Example 1 Example 9 Example 10 Example 13 Example 14 Example 15 Example 16 MM 29.83 19.15 16.48 6.64 20.07 39.91 48.49 MDM 30.4 26.43 21.54 10.57 22.07 33.88 33.56 <![CDATA[MD2M]]> 23.08 22.17 21.08 11.94 20.34 17.63 14.24 <![CDATA[MD3M]]> 11.72 17.15 17.33 14.34 17.95 7.49 3.02 <![CDATA[MD4M]]> 3.49 8.43 9.66 13.91 8.83 0.85 0.61 <![CDATA[MD5M]]> 1.24 2.75 5.12 12.23 4.93 0.21 0.06 <![CDATA[MD6M]]> 0.08 1.96 3.22 10.84 2.67 / / <![CDATA[MD7M]]> / 1.79 2.32 7.21 1.34 / / <![CDATA[MD8M]]> / 0.08 1.62 5.19 0.97 / / <![CDATA[MD9M]]> / / 0.82 3.55 0.38 / / <![CDATA[MD 10 M]]> / / 0.44 1.86 0.21 / / <![CDATA[MD 11 M]]> / / 0.3 0.56 / / / <![CDATA[MD 12 M]]> / / / 0.44 / / / <![CDATA[D4]]> 0.07 0.06 0.05 0.46 0.15 0.03 0.02 <![CDATA[D5]]> 0.02 0.02 0.02 0.21 0.06 / / <![CDATA[D6]]> 0.01 0.01 0.05 0.03 / /
Claims
1. A process for the preparation of a low ring, ultra-low viscosity dimethicone, characterized in that, The viscosity of the dimethyl silicone oil is <5cSt, and the total content of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane and dodecylcyclohexasiloxane cyclic compounds is ≤300ppm. The preparation method includes: first, placing α,ω-dihydroxy polysiloxane linear, polymerization inhibitor and catalyst under vacuum conditions to carry out condensation and dehydroxylation reaction to obtain prepolymer; then, adding end-capping agent to the prepolymer to carry out equilibrium polymerization; after the reaction is completed, adding terminator and quenching catalyst to obtain ultra-low viscosity dimethyl silicone oil. The viscosity of the linear α,ω-dihydroxypolysiloxane is 50-90 cSt, and the volatile matter content is less than 0.1%. The polymerization inhibitor is a low-viscosity methyl silicone oil with a viscosity of 10-20 cSt; The mass ratio of α,ω-dihydroxypolysiloxane lineare to polymerization inhibitor is 1:0.1~1:0.2; The catalyst is phosphazene chloride, and the amount added is 10-20 ppm of the total mass of α,ω-dihydroxypolysiloxane linear, polymerization inhibitor and end-capping agent. The condensation-dehydroxylation reaction is carried out at a temperature of 100-120℃; under vacuum conditions of 0.4-0.8 kPa; and for a reaction time of 0.5-1 h. The mass ratio of the end-capping agent to the prepolymer is 4:1 to 6:1; The equilibrium polymerization reaction temperature is 70-90℃; the equilibrium polymerization reaction time is 3-8h. The terminator is hexamethylsilazane or cyclotrisilazane.
2. The method for preparing the low-cyclic, ultra-low viscosity dimethyl silicone oil according to claim 1, characterized in that, The volatile matter content of the linear α,ω-dihydroxypolysiloxane is less than 0.03%.
3. The process for the preparation of low ring, ultra-low viscosity dimethicone as claimed in claim 1, wherein, The capping agent is hexamethyldisiloxane.
4. A low ring, ultra-low viscosity dimethicone characterized in that, It is obtained by the preparation method according to any one of claims 1-3.