A preparation method of polybutadiene latex and prepared ABS resin

Abstract

The present invention provides a method for preparing polybutadiene latex. The method comprises modifying nano-silica with a polymerizable silane coupling agent, first polymerizing and coating the surface with a layer of highly cross-linked polybutadiene rubber, and then polymerizing and coating the surface with a layer of low-cross-linked polybutadiene rubber. This method produces a polybutadiene latex with a three-layer composite core-shell structure of "nano-silica-highly cross-linked polybutadiene-lowly cross-linked polybutadiene." Finally, an emulsified silicone oil is added, which is nanoscale compatible with the polymerized polybutadiene latex, ultimately yielding a specially modified polybutadiene latex. The ABS resin prepared from this latex exhibits both high impact strength and high rigidity, as well as excellent and long-lasting anti-squeaking properties.

Description

Technical Field

[0001] The invention belongs to the field of polymers, and particularly relates to a method for preparing polybutadiene latex and the prepared ABS resin. Background Art

[0002] As consumers' demands for quality of life continue to rise, ABS resin is widely used in home appliances, automobiles, communications equipment, computers and other fields, and is gradually requiring ABS materials to have both excellent intrinsic performance and good appearance quality. For example, the industry is gradually placing higher demands on ABS resin used in automotive interior parts to have a good balance of mechanical properties (i.e., it must take into account both impact strength and rigidity) as well as other special properties such as anti-friction and anti-squeak properties.

[0003] ABS resin is structurally obtained by toughening and modifying a base SAN resin with elastic, nano-spherical rubber particles. The modified SAN resin transforms from a "brittle" material to a "tough" one. The addition of rubber particles improves the SAN resin's impact resistance, but the addition of the rubber phase also significantly reduces the rigidity of the base SAN resin, such as its tensile strength and flexural strength. Currently, the industry primarily compensates for this loss of rigidity by increasing the proportion of AN monomer in the SAN resin formulation and the molecular weight of the SAN resin during the preparation of the SAN resin. However, both of these methods result in a significant increase in the viscosity of the system during the polymerization process. This not only increases the difficulty of devolatilization and the amount of volatile residue in the product, but also increases the difficulty of product transportation, reducing production efficiency.

[0004] Furthermore, when ABS resin is squeezed or impacted during use, if the external torque is less than the friction, the contacting materials do not "slide" with each other, thus preventing any abnormal noise. However, once the external torque exceeds a certain value of friction, the material suddenly "slides," causing instantaneous, intense vibration and a "creaking" noise. Patent CN107177156A discloses a method for preparing high-damping, noise-reducing ABS. This method utilizes an elastomer, TPU, to increase the material's damping, achieving excellent noise reduction. However, the addition of rubber or elastomer significantly reduces the material's rigidity, limiting its application to a certain extent. CN112759878A discloses a silent HIPS alloy composition, its preparation method and application. By adding a low-surface energy component to the resin alloy system in the form of physical mixing, its noise performance is significantly improved compared with ordinary HIPS and alloy resins. However, in this method, the anti-sounding additive is physically dispersed in the resin. Due to poor compatibility, the low-surface energy additive is prone to surface migration as the service life extends, and it cannot provide a long-term anti-sounding effect. At the same time, due to the excessive amount of additive added, the resin's impact strength, etc., is also lost.

[0005] Therefore, it is of great practical significance to study and prepare ABS resin that has high impact strength, high rigidity and excellent long-lasting anti-squeak properties. Summary of the Invention

[0006] The present invention aims to provide a method for preparing polybutadiene latex, which comprises modifying nano-silica with a polymerizable silane coupling agent, first polymerizing and coating a layer of highly cross-linked polybutadiene rubber on the surface of the nano-silica, and then polymerizing and coating a layer of low-cross-linked polybutadiene rubber to prepare a polybutadiene latex with a three-layer composite core-shell structure of "nano-silica-highly cross-linked polybutadiene-lowly cross-linked polybutadiene", and finally adding emulsified silicone oil, which is compatible with the polymerized polybutadiene latex at the nanoscale, to finally obtain a specially modified polybutadiene latex.

[0007] The modified polybutadiene latex particles of the present invention have a core of hard nano-silicon dioxide and a middle layer of polybutadiene with a high degree of cross-linking. The synergistic effect of the two can effectively improve the rigidity of the ABS resin after mixing. In addition, by adding an appropriate amount of chain transfer agent in a specified conversion rate range, the gel content of the outer layer polybutadiene is controlled to be at a low level, and the low-gel polybutadiene molecular chain is rich in residual double bonds, which is conducive to grafting styrene and acrylonitrile mixed monomers, thereby improving the grafting rate. The ABS rubber powder with a high grafting rate has better compatibility with the SAN resin, thereby improving the toughening efficiency and the impact resistance of the resin. Finally, because the emulsified silicone oil added in the late stage of the reaction has structural similarity with the silane coupling agent in the latex, the emulsified silicone oil can be mixed and compatible with the polybutadiene latex at the nanometer scale. Therefore, the low-surface-energy silicon compound can be uniformly and stably dispersed in the ABS resin phase along with the polybutadiene latex, giving the resin excellent and lasting anti-squeaking performance.

[0008] The object of the present invention is achieved through the following technical solutions:

[0009] In a first aspect, the present invention provides a method for preparing a polybutadiene latex, comprising the following steps, in parts by weight:

[0010] Add 40-60 parts of the first deionized water, 1-5 parts of the first emulsifier, 20-40 parts of the water-soluble organic solvent, 1-5 parts of sodium hydroxide, 1-5 parts of silicon dioxide and 1-10 parts of the silane coupling agent into the reactor and start stirring. Heat the reactor to 55-85° C. and keep it warm for 20-120 minutes.

[0011] Adding 60-100 parts of second deionized water, 110-150 parts of butadiene, 1-5 parts of a second emulsifier, 1-5 parts of a polymerizable crosslinking agent, 1-5 parts of an electrolyte, and 1-5 parts of an initiator into the reactor to continue the polymerization reaction;

[0012] When the butadiene conversion rate is 50%≤≤65%, 1-5 parts of chain transfer agent are added to the reactor to continue the polymerization reaction;

[0013] When the butadiene conversion rate is 90%≤≤98%, 1-5 parts of emulsified silicone oil are added, stirred evenly, and then the reactor is cooled to room temperature, and filtered to obtain a polybutadiene latex with a three-layer core-shell structure.

[0014] Preferably, the method comprises the following steps, in parts by weight:

[0015] Add 45-55 parts of the first deionized water, 2-4 parts of the first emulsifier, 25-35 parts of the water-soluble organic solvent, 2-4 parts of sodium hydroxide, 2-4 parts of silicon dioxide and 3-7 parts of the silane coupling agent into the reactor and start stirring. Heat the reactor to 60-80° C. and keep it warm for 30-90 minutes.

[0016] Adding 70-90 parts of second deionized water, 120-140 parts of butadiene, 2-4 parts of a second emulsifier, 2-4 parts of a polymerizable crosslinking agent, 2-4 parts of an electrolyte, and 2-4 parts of an initiator to the reactor to continue the polymerization reaction;

[0017] When the butadiene conversion rate is 55%≤≤60%, 2-4 parts of chain transfer agent are added to the reactor to continue the polymerization reaction;

[0018] When the butadiene conversion rate is 92%≤96%, emulsified silicone oil is added, stirred evenly, the reactor is cooled to room temperature, and filtered to obtain a polybutadiene latex with a three-layer core-shell structure.

[0019] In the method of the present invention, the water-soluble organic solvent has a solubility of ≥20 parts by weight in 100 parts by weight of water at 25° C., for example, selected from one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isopentanol, ethylene glycol, N,N-dimethylformamide, and tetrahydrofuran, preferably ethanol and / or isopropanol.

[0020] In the method of the present invention, the silicon dioxide is nano-scale silicon dioxide particles, preferably silicon dioxide particles with a size of 10-50 nm.

[0021] In the method of the present invention, the silane coupling agent is selected from alkoxysilanes containing at least one vinyl group, preferably one or more of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyltriisopropoxysilane, and γ-methacryloxypropyltrimethoxysilane.

[0022] In the method of the present invention, the first emulsifier is consistent with or inconsistent with the second emulsifier and is selected from one or more of potassium oleate, potassium disproportionated rosinate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate and dioctyl sodium sulfosuccinate.

[0023] In the method of the present invention, the polymerizable crosslinking agent is a polymerizable monomer having multiple olefin double bonds, preferably one or more of allyl methacrylate, allyl acrylate, divinylbenzene, 1,4-butanediol dimethacrylate, and ethylene glycol dimethacrylate.

[0024] In the method of the present invention, the electrolyte is one or more of potassium bicarbonate, potassium carbonate, sodium bicarbonate, sodium carbonate, and sodium tripolyphosphate.

[0025] In the method of the present invention, the initiator is selected from one or more of inorganic peroxides and organic peroxides, preferably one or more of potassium persulfate, sodium persulfate and ammonium persulfate.

[0026] In the method of the present invention, the chain transfer agent is tert-dodecyl mercaptan.

[0027] In the method of the present invention, the emulsified silicone oil is an organic silicone mainly composed of methyl polysiloxane, preferably AFE TM 0120, AFE TM 1410、AFE TM BYK 3168 and / or BYK TM 024, BYK TM One or more of 028.

[0028] In a second aspect, the present invention provides an ABS resin prepared from the polybutadiene latex prepared by the method of the present invention:

[0029] In the present invention, grafting, coagulating, dehydrating, and drying the prepared polybutadiene latex to obtain ABS rubber powder, which is then blended with SAN resin and granulated to obtain ABS resin, are conventional techniques in the art. The detailed procedures for obtaining ABS rubber powder from polybutadiene latex through grafting, coagulation, filtration, dehydration, and drying can be found on pages 36-58 of the book "ABS Resin Production Practice and Application" by Suo Yanhui et al. The detailed procedures for obtaining ABS resin by blending ABS rubber powder with SAN resin and extruding and granulating can be found on pages 68-74 of the same book.

[0030] The beneficial effects of the present invention are:

[0031] The invention provides a method for preparing polybutadiene latex. The method comprises the following steps: modifying nano-silica with a polymerizable silane coupling agent, and first polymerizing and coating the surface of the nano-silica with a layer of highly cross-linked polybutadiene rubber, and then coating the surface with a layer of low-cross-linked polybutadiene rubber, to prepare a polybutadiene latex with a three-layer composite core-shell structure of "nano-silica-highly cross-linked polybutadiene-lowly cross-linked polybutadiene". Finally, emulsified silicone oil is added, which is compatible with the polymerized polybutadiene latex at the nanoscale, to finally obtain a specially modified polybutadiene latex.

[0032] The ABS resin prepared from the latex has high impact strength and high rigidity, as well as excellent and long-lasting anti-squeak performance. DETAILED DESCRIPTION

[0033] In order to better understand the technical solutions of the present invention, the present invention is further described below with reference to the following embodiments, but the present invention is not limited to the following embodiments.

[0034] Unless otherwise specified, the raw materials used in the following examples and comparative examples of the present invention were obtained from commercial channels.

[0035] In the following examples and comparative examples of the present invention, the test methods and standards for the intermediate products and resin properties are as follows:

[0036] The test method of butadiene conversion rate is as follows: take 0.05g sample into 20ml headspace bottle, dilute to 1.00g with DMF, analyze the sample with gas chromatograph, and test the residual butadiene monomer content.

[0037]

[0038] The butadiene conversion rate can be calculated by substituting the result into the following formula:

[0039] Example 1

[0040] 45.0 kg of first deionized water, 1.0 kg of potassium oleate, 10.0 kg of methanol, 20.0 kg of ethanol, 10.0 kg of isopropanol, 5.0 kg of sodium hydroxide, 2.0 kg of nano-silicon dioxide with a particle size distribution of 10-20 nm, 2.0 kg of nano-silicon dioxide with a particle size distribution of 20-40 nm, 1.0 kg of nano-silicon dioxide with a particle size distribution of 40-50 nm, 5.0 kg of vinyltrimethoxysilane, 3.0 kg of vinyltriethoxysilane and 2.0 kg of vinyltriisopropoxysilane were weighed and added to a reactor, stirring was started, the reactor was heated to 80 ° C and kept warm for 20 min; the reactor was added 100.0 kg of second deionized water, 110.0 kg of butadiene, 3.0 kg of potassium disproportionate rosinate, 1.0 kg of sodium lauryl sulfate, 1.0 kg of sodium dodecylbenzene sulfonate, 1.0 kg of divinylbenzene, 3.0 kg of sodium bicarbonate and 1.0 kg of potassium persulfate were added to continue the polymerization reaction; sampling was taken to detect the butadiene conversion rate, which was recorded as butadiene conversion rate 1. When the butadiene conversion rate 1 = 50.4%, 1.0 kg of tert-dodecyl mercaptan was added to the reactor to continue the polymerization reaction; sampling was continued to detect the butadiene conversion rate, which was recorded as butadiene conversion rate 2. When the butadiene conversion rate 2 = 97.9%, 1.0 kg of emulsified silicone oil AFE was added. TM 0120, after stirring evenly, the reactor was cooled to room temperature and filtered to obtain a polybutadiene latex with a three-layer core-shell structure.

[0041] Examples 2-5

[0042] The differences between Examples 2-5 and Example 1 are shown in Table 1. The remaining raw materials, experimental conditions and reaction steps are the same as those in Example 1.

[0043] Table 1 Differences between Examples 2-5 and Example 1

[0044]

[0045]

[0046] Comparative Example 1

[0047] The reaction process of Comparative Example 1 is basically the same as that of Example 1, with the main difference being that nano-silica, polymerizable silane coupling agent and polymerizable cross-linking agent are not added, and emulsified silicone oil is not added after the reaction. The addition amount and timing of other substances and the control of the reaction process are the same as those in Example 1.

[0048] Comparative Example 2

[0049] The reaction process of Comparative Example 2 is basically the same as that of Example 2, the main difference being that 1.0 kg of vinyltriethoxysilane is not added. The addition amounts and timings of other substances and the control of the reaction process are the same as those of Example 2.

[0050] Comparative Example 3

[0051] The reaction process of Comparative Example 3 is basically the same as that of Example 3, the main difference being that no polymerizable crosslinking agent is added. The addition amounts and timings of other substances and the control of the reaction process are the same as those of Example 3.

[0052] Comparative Example 4

[0053] The reaction process of Comparative Example 4 is basically the same as that of Example 4, the main difference being that tert-dodecyl mercaptan is not added. The addition amounts and timings of other substances and the control of the reaction process are the same as those of Example 4.

[0054] Comparative Example 5

[0055] The reaction process of Comparative Example 5 is basically the same as that of Example 5, the main difference being that nano-silicon dioxide is not added. The addition amounts and timings of other substances and the control of the reaction process are the same as those of Example 5.

[0056] The present invention prepares ABS resin from the polybutadiene latex in Examples 1-5 and Comparative Examples 1-5 according to the following method and injection molds it into test specimens for testing:

[0057] 1) Preparation of ABS grafted latex

[0058] 60 kg (in terms of solid content) of polybutadiene latex, 120 kg of deionized water, 0.001 kg of FeSO4·7H2O, 0.01 kg of sodium pyrophosphate, and 0.1 kg of glucose were added to the reactor respectively and stirring was started. After the reactor was heated to 70° C., a mixed pre-emulsion consisting of 0.2 kg of cumene hydroperoxide, 30 kg of styrene, 10 kg of acrylonitrile, 0.5 kg of tert-dodecyl mercaptan, 3 kg of potassium oleate, and 10 kg of deionized water was continuously added to the reactor for 3 hours. After the addition was completed, the reactor was heated to 80° C. and the reaction was continued for 3 hours. The reactor was cooled to room temperature and stirring was stopped, and filtration was performed to obtain ABS grafted latex.

[0059] 2) ABS rubber powder preparation

[0060] 1.2 kg of concentrated sulfuric acid and 200 kg of deionized water were added to the coagulation kettle and stirred to fully dissolve the concentrated sulfuric acid. The coagulation kettle was heated to 75° C. and 100 kg of the ABS grafted latex prepared in step 1) was continuously fed into the coagulation kettle for 1 hour. After the feeding was completed, the coagulation kettle was heated to 90° C. and kept warm for 1 hour. The coagulation kettle was cooled to room temperature and the coagulated slurry was filtered, washed, and dehydrated to obtain ABS wet rubber powder. The ABS wet rubber powder was dried in a fluidized bed dryer at 65° C. to a moisture content of <1% to obtain ABS rubber powder.

[0061] 3) ABS resin preparation, injection molding and performance testing

[0062] A twin-screw extruder was used at 200° C.-220° C. with LG Chemical's SA 30 SAN resin as the continuous phase and the ABS rubber powder prepared in step 2) as the dispersed phase. The mixture was extruded and granulated to obtain ABS resin at a polybutadiene rubber content of 15%.

[0063] The above-mentioned ABS resin was injected into a molding machine at 190°C to produce various test specimens. The impact strength, tensile strength, and flexural strength of the ABS resin were measured according to ASTM-D256, ASTM-D638-2000, and ASTM D790-2000, respectively. The ABS resin's anti-squeak performance was characterized by the noise risk index, which was measured according to the German automotive industry standard VDA 230-206. A risk factor of 1-3 indicates low noise risk, a risk factor of 4-6 indicates medium noise risk, and a risk factor of 7-10 indicates high noise risk. The relevant evaluation results are shown in Table 2.

[0064] Table 2 ABS resin noise risk index and mechanical properties test results

[0065]

[0066] It can be seen from the test results of Examples 1-5 and Comparative Examples 1-5 that, compared with the ABS resin prepared from the polybutadiene latex prepared in the comparative example, the ABS resin prepared from the polybutadiene latex prepared in the present invention has a more excellent anti-squeaking effect and its impact strength, tensile strength and flexural strength are also greatly improved.

[0067] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing polybutadiene latex, characterized in that: The method comprises the following steps, in parts by weight: Add 40-60 parts of first deionized water, 1-5 parts of first emulsifier, 20-40 parts of water-soluble organic solvent, 1-5 parts of sodium hydroxide, 1-5 parts of silicon dioxide and 1-10 parts of silane coupling agent into a reactor and start stirring, and heat the reactor and keep it warm; Adding 60-100 parts of second deionized water, 110-150 parts of butadiene, 1-5 parts of a second emulsifier, 1-5 parts of a polymerizable crosslinking agent, 1-5 parts of an electrolyte, and 1-5 parts of an initiator into the reactor to continue the polymerization reaction; When the butadiene conversion rate is 50%≤≤65%, 1-5 parts of chain transfer agent are added to the reactor to continue the polymerization reaction; When the butadiene conversion rate is 90%≤≤98%, 1-5 parts of emulsified silicone oil are added, stirred evenly, and then the reactor is cooled to room temperature, and filtered to obtain a polybutadiene latex with a three-layer core-shell structure.

2. The preparation method according to claim 1, characterized in that In the first step, the temperature is raised to 55-85°C and maintained for 20-120 minutes.

3. The preparation method according to claim 1 or 2, characterized in that The water-soluble organic solvent is selected from one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isopentanol, ethylene glycol, N,N-dimethylformamide, and tetrahydrofuran; and / or the silicon dioxide is nano-scale silicon dioxide particles.

4. The preparation method according to claim 3, characterized in that The silicon dioxide is silicon dioxide particles with a size of 10-50 nm.

5. The preparation method according to claim 1 or 2, characterized in that The silane coupling agent is an alkoxysilane containing at least one vinyl group.

6. The preparation method according to claim 5, characterized in that The silane coupling agent is one or more of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyltriisopropoxysilane, and γ-methacryloxypropyltrimethoxysilane.

7. The preparation method according to claim 1 or 2, characterized in that The first emulsifier is consistent with or inconsistent with the second emulsifier and is selected from one or more of potassium oleate, potassium disproportionated rosinate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate and dioctyl sodium sulfosuccinate.

8. The preparation method according to claim 1 or 2, characterized in that The polymerizable crosslinking agent is a polymerizable monomer having multiple olefin double bonds.

9. The preparation method according to claim 8, characterized in that The polymerizable crosslinking agent is one or more of allyl methacrylate, allyl acrylate, divinylbenzene, 1,4-butanediol dimethacrylate, and ethylene glycol dimethacrylate.

10. The preparation method according to claim 1 or 2, characterized in that: The electrolyte is one or more of potassium bicarbonate, potassium carbonate, sodium bicarbonate, sodium carbonate, and sodium tripolyphosphate; and / or: The initiator is selected from one or more of inorganic peroxides and organic peroxides.

11. The preparation method according to claim 10, characterized in that: The initiator is selected from one or more of potassium persulfate, sodium persulfate and ammonium persulfate.

12. The preparation method according to claim 1 or 2, characterized in that: The chain transfer agent is tert-dodecyl mercaptan.

13. The preparation method according to claim 1 or 2, characterized in that: The emulsified silicone oil is an organic silicone mainly composed of methyl polysiloxane.

14. The preparation method according to claim 13, characterized in that The emulsified silicone oil is AFE from Dow Corning TM 0120, AFE TM 1410、AFE TM BYK 3168 and / or BYK TM 024, BYK TM One or more of 028.

15. An ABS resin, characterized in that: The polybutadiene latex is prepared by the preparation method according to any one of claims 1 to 14.

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