CN112646071B - SAN resin and preparation method thereof - Google Patents
SAN resin and preparation method thereof Download PDFInfo
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F212/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
- C08F212/02—Monomers containing only one unsaturated aliphatic radical
- C08F212/04—Monomers containing only one unsaturated aliphatic radical containing one ring
- C08F212/06—Hydrocarbons
- C08F212/08—Styrene
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2500/00—Characteristics or properties of obtained polyolefins; Use thereof
- C08F2500/05—Bimodal or multimodal molecular weight distribution
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Abstract
The invention provides SAN resin and a preparation method thereof. The SAN resin is prepared by a suspension polymerization method in two steps, namely synthesizing a low molecular weight part and then synthesizing a high molecular weight part. The SAN resin prepared by the method has wide molecular weight distribution, shows large-size bimodal distribution, improves the mechanical property of the resin with large molecular weight, keeps high fluidity of the resin with small molecular weight, and has a melt index of 30-35 g/10min at 220 ℃ and 10Kg when the weight average molecular weight of the resin is 400,000-500,000.
Description
Technical Field
The invention belongs to the field of high polymer materials, and particularly relates to a preparation method of SAN resin and a preparation method thereof.
Background
The SAN resin is a styrene-acrylonitrile copolymer, is amorphous colorless or yellowish thermoplastic plastic, and has good dimensional stability, weather resistance, heat resistance, oil resistance and chemical stability. SAN resin can resist nonpolar substances such as gasoline, kerosene, aromatic hydrocarbon and the like, resist water, acid, alkali, detergent and halogenated hydrocarbon solvents, and is widely used for manufacturing oil-resistant, heat-resistant and chemical-resistant industrial products, instrument panels, instrument frames, housings, battery boxes, junction boxes, various switches, buttons and the like.
With the development of the automobile industry and the progress in the fields of electronics, home appliances (including home sanitation, kitchen cooker), and the like, the performance requirements for SAN resins are increasing. Increasing the molecular weight of SAN increases the mechanical properties of the resin, but at the same time the flowability, i.e., the melt index, decreases dramatically, which can make processing difficult. Currently, the weight average molecular weight of SAN resin is within 20 ten thousand, for example, the weight average molecular weight of the SAN resin of LG brand 80HF is 16-18 ten thousand, and the melt index (220 ℃/10 kg) is 32-34 g/10min. In order to improve the performance of SAN resin, the patent CN 102336857A improves the mechanical property, solvent resistance, temperature resistance and the like of SAN resin by improving the nitrile content of SAN, and meanwhile, the narrower molecular weight distribution is beneficial to the transparency, color and mechanical property of products, but the high nitrile content and the narrow molecular weight distribution reduce the flowability of SAN and are not beneficial to the processing, the acrylonitrile content is more than 32 percent, and the melt index is less than 6g/10min.
Disclosure of Invention
It is an object of the present invention to overcome the disadvantages of the prior art by providing a SAN resin which, while having a high molecular weight, has a high flowability.
Another object of the present invention is to provide a method for preparing the SAN resin.
The above purpose of the invention is realized by the following technical scheme:
a preparation method of SAN resin adopts a suspension polymerization method and specifically comprises the following steps:
s1, mixing a styrene monomer, an acrylonitrile monomer, a chain transfer agent, an initiator and deionized water, stirring, discharging system air, heating to 60-70 ℃ for reaction, and reacting for 10-50 min;
s2, dissolving the dispersion stabilizer and the electrolyte, adding the solution into the system obtained in the step S1, reacting at 60-70 ℃ for 3-10 h, heating to 75 ℃ for 1-5 h, and heating to 80-90 ℃ for 1-3 h;
and S3, carrying out post-treatment on the product obtained in the S2 to obtain the SAN resin.
By the staged polymerization method, SAN with lower molecular weight is synthesized in S1 by controlling reaction time, and a dispersion stabilizer is added in the subsequent stage to disperse SAN with lower molecular weight in a system and continue to react to obtain SAN with higher molecular weight, so that the final SAN resin has wide molecular weight distribution, large and small bimodal distribution, high molecular weight to improve the mechanical property of the resin, and small molecular weight to keep the high fluidity of the resin, and the prepared SAN resin still has high fluidity under high molecular weight.
Preferably, in s1, the chain transfer agent is a mercaptan having 5 to 14 carbon atoms. More preferably n-dodecyl mercaptan.
Preferably, in s1, the initiator is preferably an oil-soluble initiator.
Preferably, in s1, the exhaust system air is exhaust system air introduced with inert gas. The inert gas is preferably nitrogen.
More preferably, in s1, the initiator is more preferably at least one of azobisisobutyronitrile, azobisisoheptonitrile, dibenzoyl peroxide, 2-ethylhexyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, diphenoxyethyl peroxydicarbonate, bis (3, 5-trimethylacetyl) peroxide, and cumyl peroxyneodecanoate.
More preferably, considering that S1. And S2. Are carried out at different reaction temperatures, in S1. The initiator selected can play a better initiating role in both S1. And S2. Preferably. Therefore, in S1. A composition of an initiator having a decomposition temperature of 60 to 70 ℃ and 80 to 90 ℃ is more preferable.
Preferably, in s2, the dispersion stabilizer is preferably one or more of sodium polyacrylate, polyvinyl alcohol, gelatin, hydroxymethyl cellulose or calcium hydroxy phosphate.
Preferably, in s2, the electrolyte is a soluble inorganic salt.
Preferably, in s2, the electrolyte is one or more of sodium sulfate, potassium sulfate, sodium chloride, potassium chloride, sodium nitrate, or sodium nitrite.
Preferably, the mass ratio of the acrylonitrile monomer to the styrene monomer is preferably 2 to 3:8 to 7. More preferably, the mass ratio of the acrylonitrile monomer to the styrene monomer is more preferably 2.3 to 2.5:7.7 to 7.5. That is, the content of acrylonitrile in SAN is more preferably 23 to 25%, and controlling the content within this range can promote the copolymerization of acrylonitrile and styrene well and prevent the homopolymerization of acrylonitrile.
Preferably, in s1, the reaction time is preferably 30 to 60min.
Preferably, in s1, the reaction is preferably carried out at 65 to 68 ℃.
Preferably, in S2, after dissolving the dispersion stabilizer and the electrolyte, adding the solution into the system after the reaction in S1, and reacting for 3-10 h at the same temperature as in S1.
Preferably, in s3, the post-treatment comprises filtering, centrifuging and drying the product obtained in s2.
The SAN resin prepared by the preparation method has the melt index of 30-35 g/10min at 220 ℃ and 10Kg when the weight average molecular weight of the SAN resin is 400,000-500,000.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention provides a method for stage polymerization by improving a SAN preparation method, so that the molecular weight distribution of the synthesized SAN resin is wide, large and small bimodal distributions are presented, the large molecular weight improves the mechanical property of the resin, the small molecular weight keeps the high fluidity of the resin, and the melt index of the resin is still as high as 30-35 g/10min under the conditions of 220 ℃ and 10Kg when the weight average molecular weight of the resin is 400,000-500,000.
Drawings
FIG. 1 is a graph of the molecular weight distribution of SAN prepared in example 1.
Detailed Description
Unless otherwise specified, the raw materials, reagents and solvents used in the present invention were all purchased commercially without any treatment. The present invention is described in further detail with reference to the following examples, but the embodiments of the present invention are not limited to the examples, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and they are included in the scope of the present invention. In the present specification, "part(s)" and "%" represent "part(s) by mass" and "% by mass", respectively, unless otherwise specified.
The physical properties of the present invention were measured by the following methods
(1) Molecular weight measurement
The molecular weight was measured using the standard of GB/T21863-2008 Gel Permeation Chromatography (GPC) with tetrahydrofuran as the eluent.
(2) Melt index test
Melt index test determination according to ISO 1133 determination of melt Mass Flow Rate (MFR) and melt volume flow rate (MVR) of thermoplastics.
(3) Coefficient of molecular weight distribution
The molecular weight distribution coefficient is characterized by the ratio Mw/Mn of the weight average molecular weight Mw to the number average molecular weight Mn, the molecular weight distribution being broader the larger the value and narrower the value.
Example 1
S1, adding 76.5g of styrene monomer, 23.5g of acrylonitrile monomer, 0.5g of n-dodecyl mercaptan, 0.5g of azobisisobutyronitrile, 0.2g of benzoyl peroxide and 150g of deionized water into a 1000ml flask with a thermometer, a nitrogen pipe, a reflux device and a stirring device, mixing, stirring, introducing nitrogen for 10min to exhaust system air, heating to 65-68 ℃ for reaction, and reacting for 20min;
s2, adding 0.75g of sodium polyacrylate and 0.5g of sodium sulfate into 50g of water for dissolving, adding the solution into the system obtained in the step S1, continuing to react for 3 hours at 65 ℃, then heating to 70 ℃ for reacting for 2 hours, and then heating to 85 ℃ for reacting for 1 hour to obtain a product;
and S3, filtering the product obtained in the step S2 by using a filter bag, and drying to obtain granular SAN resin.
The molecular weight distribution of the SAN resin of this example is shown in FIG. 1. It can be seen from FIG. 1 that the molecular weight distribution of the synthesized SAN resin is broad and exhibits a bimodal distribution of sizes. The corresponding data of fig. 1 is shown in table 1:
TABLE 1
| # | Number average Mn | Weight average Mw | Z is Mz | Z+1 | Viscosity-average Mv | Mw/Mn | Mv/Mn | Mz/Mw | Inherent tackiness | ％ |
| Total of | 52564 | 553511 | 1955386 | 3388866 | 0 | 9.35953 | 0 | 3.73514 | 1 | 100 |
| 1 | 372347 | 886190 | 2033256 | 3393481 | 0 | 2.38001 | 0 | 2.29438 | 1 | 56.7327 |
| 2 | 24723 | 47961 | 68761 | 82581 | 0 | 1.93995 | 0 | 1.43369 | 1 | 43.2673 |
Example 2
The reaction time of only S1. Was increased from 20min to 30min as in example 1.
Example 3
The reaction time of S1. Alone increased from 20min to 40min as in example 1.
Comparative example 1
76.5g of styrene, 23.5g of acrylonitrile, 0.5g of azobisisobutyronitrile, 0.2g of benzoyl peroxide and 0.5g of n-dodecyl mercaptan were put into a 1000ml flask equipped with a thermometer, a nitrogen inlet tube, a reflux unit and a stirrer, and mixed, stirred and dissolved. 0.75g of sodium polyacrylate and 0.5g of sodium sulfate are taken, 200g of water is added for dissolution, then the mixture is added into a flask and is filled with nitrogen to exhaust the air of the system, the mixture is stirred, the temperature is increased to 65-68 ℃ for reaction for 3-5 h, the temperature is increased to 70 ℃ for reaction for 2h, and the temperature is increased to 85 ℃ for reaction for 1h.
And after the reaction is finished, filtering and drying the product by using a filter bag to obtain granular SAN resin.
Comparative example 2
Synthesizing SAN resin by emulsion polymerization method
Adding 210g of deionized water, 3.9g of diphenoxysulfonate and 0.78g of potassium persulfate into a 1000ml flask with a thermometer, a nitrogen pipe, a reflux device and a stirring device, stirring and dissolving, introducing nitrogen to discharge system air, and heating to 70 ℃.
61.1g of acrylonitrile, 198.9g of styrene, 0.91g of n-dodecyl mercaptan, 1.3g of sodium dodecyl benzene sulfonate and 173g of deionized water are stirred and pre-emulsified to prepare a monomer pre-emulsion.
Adding 71g of monomer pre-emulsion into a flask at one time, preserving heat at 70 ℃, dropwise adding the rest monomer pre-emulsion at 70 ℃ after heat release is initiated, dropwise adding for 3h, and preserving heat for 1.5h to prepare SAN emulsion.
And (3) spray drying the synthesized SAN emulsion at 210 ℃ to obtain a powder material, namely SAN resin.
Comparative example 3
The reaction time of only S1. Increased from 20min to 60min as in example 1. In S1, a large amount of bonding components appear, and a large amount of unreacted monomers exist in the system, so that the monomers cannot be dispersed into small particles and cannot be subjected to the next reaction.
The molecular weight and melt index of examples 1-3, comparative examples 1-3, and the commercial SAN grade, LG 80HF were compared and the results are shown in Table 1.
TABLE 1
As is clear from Table 1, examples 1 to 3 have a high weight average molecular weight, but a molecular weight distribution coefficient of more than 9, indicating that the melt index is higher than that of comparative example 1 (the melt index is higher than that of comparative example 1, the molecular weight is higher than that of comparative example 1, but the molecular weight distribution is relatively narrow). From example 3 and comparative examples 2, 80HF, it is clear that when the molecular weight distribution is narrow, a lower weight average molecular weight is required to achieve a high melt index.
Claims (11)
1. A preparation method of SAN resin is characterized by adopting a suspension polymerization method and specifically comprising the following steps:
s1, mixing a styrene monomer, an acrylonitrile monomer, a chain transfer agent, an initiator and deionized water, stirring, discharging system air, heating to 60-70 ℃ for reaction, and reacting for 10-50 min;
s2, dissolving the dispersion stabilizer and the electrolyte, adding the solution into the system obtained in the step S1, reacting at 60-70 ℃ for 3-10 h, heating to 75 ℃ for 1-5 h, and heating to 80-90 ℃ for 1-3 h;
and S3, carrying out post-treatment on the product obtained in the S2 to obtain the SAN resin.
2. The method for preparing SAN resin according to claim 1, wherein in S1, the chain transfer agent is a mercaptan having 5 to 14 carbon atoms.
3. The method for preparing SAN resin according to claim 1, wherein in S1, the initiator is an oil-soluble initiator.
4. The method for producing SAN resin according to claim 1 or 3, wherein in S1, the initiator is at least one of azobisisobutyronitrile, azobisisoheptonitrile, dibenzoyl peroxide, 2-ethylhexyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, diphenoxyethyl peroxydicarbonate, bis (3, 5-trimethylacetyl) peroxide, cumyl peroxydecanoate.
5. The method for preparing SAN resin according to claim 1, wherein in S2, the dispersion stabilizer is one or more of sodium polyacrylate, polyvinyl alcohol, gelatin, hydroxymethyl cellulose, or calcium hydroxy phosphate.
6. The method for preparing SAN resin of claim 1, wherein in S2, the electrolyte is a soluble inorganic salt.
7. The SAN resin preparation method according to claim 1 or 6, wherein in S2, the electrolyte is one or more of sodium sulfate, potassium sulfate, sodium chloride, potassium chloride, sodium nitrate, or sodium nitrite.
8. The method for preparing SAN resin of claim 1, wherein the mass ratio of acrylonitrile monomer to styrene monomer is 2 to 3:8 to 7.
9. The method for preparing SAN resin according to claim 1, wherein in S1, the reaction time is 30 to 60min.
10. The process for preparing SAN resin according to claim 1, wherein in S1, the reaction is carried out at 65 to 68 ℃.
11. A SAN resin prepared by the preparation method of any one of claims 1 to 10, wherein the SAN resin has a melt index of 30 to 35g/10min at 220 ℃ under 10Kg when the weight average molecular weight of the SAN resin is 400,000 to 500,000.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US4663357A (en) * | 1986-05-12 | 1987-05-05 | Atlantic Richfield Company | Higher molecular weight thermoplastics having multimodal molecular weight distribution |
| FI924730A (en) * | 1992-03-20 | 1993-09-21 | Rohm & Haas | PROTECTION OF POLYMERS |
| WO2001016195A1 (en) * | 1999-09-01 | 2001-03-08 | The Dow Chemical Company | Polymerization process for producing bimodal monovinylidene aromatic polymers |
| US6258504B1 (en) * | 1999-10-13 | 2001-07-10 | Nashua Corporation | Toner containing resin prepared by a combination of emulsion followed by suspension polymerization |
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| "分批加分散剂时苯乙烯悬浮聚合瞬间液滴直径和分布";方仕江等;《化学反应工程与工艺》;19920630;第8卷(第2期);第157-163页 * |
| "悬浮聚合SAN珠粒的形态研究——HAP分散效果的考察";孔令斌等;《电子显微学报》;19991231;第18卷;第34-35页 * |
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Effective date of registration: 20230427 Address after: No.88 Xinglong 1st Road, Nanshui Town, Jinwan District, Zhuhai City, Guangdong Province, 519090 Patentee after: Entropy energy innovative materials (Zhuhai) Co.,Ltd. Address before: 901, science and technology exchange center, Tian'an energy saving science and Technology Park, 555 North Panyu Avenue, Panyu District, Guangzhou, Guangdong 511400 Patentee before: GUANGZHOU SHINE POLYMER TECHNOLOGY Co.,Ltd. |