CN110204656B - Emulsion polymerization method - Google Patents
Emulsion polymerization method Download PDFInfo
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- CN110204656B CN110204656B CN201910503550.8A CN201910503550A CN110204656B CN 110204656 B CN110204656 B CN 110204656B CN 201910503550 A CN201910503550 A CN 201910503550A CN 110204656 B CN110204656 B CN 110204656B
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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
- C08F136/00—Homopolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
- C08F136/02—Homopolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
- C08F136/04—Homopolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated
- C08F136/06—Butadiene
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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
- C08F236/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
- C08F236/02—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
- C08F236/04—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated
- C08F236/06—Butadiene
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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
- C08F236/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
- C08F236/02—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
- C08F236/04—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated
- C08F236/10—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated with vinyl-aromatic monomers
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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
- C08F279/00—Macromolecular compounds obtained by polymerising monomers on to polymers of monomers having two or more carbon-to-carbon double bonds as defined in group C08F36/00
- C08F279/02—Macromolecular compounds obtained by polymerising monomers on to polymers of monomers having two or more carbon-to-carbon double bonds as defined in group C08F36/00 on to polymers of conjugated dienes
- C08F279/04—Vinyl aromatic monomers and nitriles as the only monomers
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Abstract
The present invention relates to an emulsion polymerization process for preparing a large particle size diene rubber latex. Using V-shaped pH control, adding acid agglomerant to reduce system pH to 4-9 during emulsion polymerization monomer conversion of 10-85%, adding alkali matter to raise pH to 9.5-13 after acid agglomerant addition and conversion of 50-90%. Wherein in the pH reduction stage, the stability of partial emulsifier is destroyed, so that the small-particle-size latex particles are aggregated to increase the particle size. In the pH raising stage, the damaged emulsifier is regenerated to raise the stability of the system. The emulsion polymerization method can obtain 200-500nm large-particle-size latex, and the particle size growth speed is more than 20 nm/h.
Description
Technical Field
The invention belongs to the field of polymer preparation, and particularly relates to an emulsion polymerization method for preparing large-particle-size diene rubber latex.
Background
The ABS resin is a ternary graft copolymer obtained by grafting styrene and acrylonitrile onto polybutadiene latex with a large particle size (the particle size is 250-350 nm). The polybutadiene latex with large particle size is the core component and skeleton of ABS resin, and it endows the ABS resin with toughness, and directly influences the performance of the ABS resin. There are two methods, one-step and two-step (agglomeration) methods, for the synthesis of large-particle-size polybutadiene latex.
The polybutadiene latex synthesized by the one-step method and having the particle size of 300nm generally has longer reaction time, the growth speed of the particle size is about 5-10nm/h, as described in CN200910237011.0, the particle size of the polybutadiene latex with the large particle size produced by the one-step method is 250-350 nm, and the polymerization time is about 25-70 hours.
After the 80 s, the one-step process was gradually replaced by agglomeration (two-step process). The agglomeration method is to synthesize polybutadiene latex with small particle size (the particle size is 60-150 nm) and then agglomerate and amplify the polybutadiene latex with large particle size by using an agglomerating agent.
The first step of the agglomeration process for the synthesis of small-particle-size polybutadiene latex usually requires about 10 hours of reaction time to obtain a small-particle-size latex having an average particle size of 100nm and a particle size growth rate of about 10 nm/h. CA123290A discloses a polymerization process, which reacts for 13 hours at 70 ℃ to obtain a product with the average particle size of 120 nm; CN00107134.3 discloses a polymerization process for obtaining small particle size polybutadiene latex with particle size of 80-120nm in 8-11 hours. CN200410080805.8 discloses a polymerization process, which uses an emulsifier prepared by mixing potassium abietate and potassium oleate to prepare small-particle-size polybutadiene latex with the particle size of 100-120nm within 7-10 hours.
The second step of the agglomeration process is to add an agglomerating agent from a small particle size latex of about 100nm to obtain a large particle size latex of about 300 nm. A common agglomerating agent used in chemical agglomeration processes is acetic acid. CN200510059339.X discloses an agglomeration method, which uses a solution comprising acetic acid 0.5-2.5 parts (dry basis), a regenerant 0.4-2.5 parts (dry basis), a modifier 0-0.2 parts (dry basis) and adopts different operation methods to amplify a small particle latex with an average particle diameter of 80-120nm and a pH value of 8-13 into a large particle latex with a particle diameter of 300-700 nm.
On average, the agglomeration process, in two steps, for a period of about 11 to 15 hours, gives a latex with a large particle size of about 300 nm.
The polymerization and agglomeration are carried out separately in the preparation of the polybutadiene latex, based on known processes. The process conditions of the polymerization reaction and the agglomeration process are different, and the emulsion polymerization process needs to maintain the number N of emulsion particles in the system so as to obtain a faster polymerization rate RpWhile the agglomeration process is a process that greatly reduces N; the emulsion polymerization process requires the maintenance of a certain emulsifier concentration cETo ensure that the emulsion particles can exist stably and are too unstable in the systemThe problem of condensed slag discharge exists; while the agglomeration process requires a reduction in the emulsifier concentration cEThe stability of the latex particles is destroyed, so that the coalescence occurs. Therefore, it is extremely difficult to integrate the agglomeration process in the polymerization process.
Disclosure of Invention
The invention aims to provide an emulsion polymerization method, which realizes that a one-step method can obtain a monomer conversion rate of more than 90 percent and a large-particle-size diene rubber latex product with the particle size of 200-500nm within about 10 hours on average by adopting a means of integrating a polymerization reaction and an agglomeration process in the same reaction kettle, and the particle size growth speed is more than 20 nm/h.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides an emulsion polymerization method for preparing large-particle size diene rubber latex, which comprises the following steps:
(1) adding the first reaction solution into a reaction kettle, heating to 55-85 ℃, wherein the pH value of the first reaction solution is more than or equal to 10, preferably 10-12; wherein the first reaction liquid comprises a monomer, an emulsifier, a chain transfer agent, an optional electrolyte, an initiator and deionized water;
(2) when the monomer conversion reaches 10-85%, preferably 50-70%, adding acid agglomerating agent to reduce the pH of the reaction system to 4-9, preferably 5-7;
(3) when the monomer conversion rate is 50-90%, preferably 70-90%, adding an alkali substance to raise the pH of the reaction system to 9.5-13, preferably 10-12;
(4) after the monomer conversion is more than 90%, preferably more than 95%, discharging after the reaction is finished to obtain a diene rubber latex product with large particle size.
In the emulsion polymerization method for preparing the large-particle size diene rubber latex, the mass and the dosage of the components of the first reaction liquid are as follows:
monomer 100 parts
1.8-9 parts of emulsifier, preferably 3-5 parts
0.25-0.5 part of chain transfer agent, preferably 0.3-0.45 part
0 to 2 parts of electrolyte, preferably 0.3 to 1.25 parts
0.2-0.6 part of initiator, preferably 0.25-0.3 part
90-240 parts of deionized water, preferably 140-200 parts
The emulsifier in the step (1) is selected from a compound emulsifier system, wherein the compound emulsifier comprises an emulsifier S and an emulsifier I; s represents positive, the emulsifying agent performance of the emulsifying agent S is sensitive to pH, I represents inert, and the emulsifying performance of the emulsifying agent I is not sensitive to pH; wherein the emulsifier S is selected from carboxylic acid type anionic emulsifiers with pKa >5 corresponding to carboxylic acid, preferably selected from one or more of sodium or potassium salts of disproportionated abietic acid, stearic acid, palmitic acid, oleic acid; the emulsifier I is selected from a nonionic emulsifier, preferably one or more of isomeric alcohol ethers; the mass ratio of the emulsifier S to the total emulsifier is 30-100%, preferably 50-80%, and the mass ratio of the emulsifier I to the total emulsifier is 0-70%, preferably 20-50%.
The monomer in step (1) of the present invention comprises one or more of butadiene, styrene and isoprene, the initiator is one or more selected from potassium persulfate, cumene hydroperoxide and tert-butyl hydroperoxide, the chain transfer agent is tert-dodecyl mercaptan, and the electrolyte is one or more selected from sodium salt, potassium salt, sodium hydroxide and potassium hydroxide.
The step (1) of the invention can use thermal initiation or redox initiation, when redox initiation is used, the emulsion polymerization raw material correspondingly contains reducing substances such as ferrous salt and reducing sugar and the like as initiation aids, the ferrous salt such as ferrous sulfate and ferrous chloride, and the reducing sugar such as glucose and lactose. The amount of the initiation aid is 0.1-1 part by mass based on 100 parts by mass of the monomer.
The acid agglomerating agent in the step (2) is selected from one or more of organic acid or acid anhydride with pKa between 1 and 5, preferably from one or more of acetic acid, acetic anhydride, lactic acid, benzoic acid and salicylic acid, and the alkali substance in the step (3) is selected from inorganic alkali or inorganic salt which is alkaline in hydrolysis, preferably from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and potassium phosphate.
According to the invention, further preferably, when the monomer conversion rate is 40-70%, a second reaction solution is supplemented, wherein the second reaction solution contains one or more of emulsifier S, chain transfer agent and initiator, the dosage of the supplemented emulsifier S is 0.1-1 part, the dosage of the supplemented chain transfer agent is 0.05-0.2 part, and the dosage of the supplemented initiator is 0.05-0.5 part, based on 100 parts of monomer mass.
When a redox initiation system is used in step (1), the second reaction liquid further preferably contains a reducing substance as an initiation aid.
The invention further preferably adopts a step temperature control method to control the reaction temperature, the initial reaction temperature is 55-75 ℃, and the temperature is increased to 75-85 ℃ after the monomer conversion rate is more than 70%.
The latex product prepared by the emulsion polymerization method for preparing the large-particle size diene rubber is characterized in that the average particle size of the latex is 200-500nm, preferably 250-400 nm.
The invention also provides an acrylonitrile-butadiene-styrene graft copolymer prepared from the latex product and application of the acrylonitrile-butadiene-styrene graft copolymer in preparing ABS (polyacrylonitrile-butadiene-styrene).
The invention adopts a means of integrating polymerization reaction and agglomeration process in the same reaction kettle to achieve a one-step method to obtain diene rubber latex product with monomer conversion rate of more than 90 percent and particle size of 200 and 500nm in average time of about 10 hours. And the proper manner of integrating the agglomeration process into the polymerization process is selected such that (1) the polymerization rate Rp is not reduced or is acceptably reduced; (2) increasing the particle size to a target range; (3) the growth rate of the particle size is more than 20 nm/h.
Firstly, emulsion polymerization is carried out, after the monomer conversion rate is more than or equal to 10%, a sufficient number of small-particle-size emulsion particles are generated in a system, and then agglomeration is carried out, so that the small-particle-size emulsion particles are agglomerated to rapidly increase the particle size; and preferably at a monomer conversion of 50% or more, with minimal impact on the polymerization rate Rp; the agglomeration is carried out at the latest at a monomer conversion of 85%, preferably 70%, so that the agglomerates of several small-particle-size latices formed in the agglomeration process can be fused into one piece.
Agglomeration at monomer conversions less than 10% is not recommended because the disadvantage of agglomeration leading to a decrease in the polymerization rate Rp outweighs the benefit of agglomeration leading to an increase in the particle size of the product.
Agglomeration is feasible at conversion greater than 85%, if the following two negative effects are acceptable: (1) when the conversion rate reaches 90%, the particle size may not be increased to a qualified range, and the problem can be remedied by prolonging the agglomeration time, but the negative effect of increasing the total production time is caused; (2) the resulting large particle size latex is essentially an aggregate of several small particle size latexes rather than a whole.
When the monomer conversion rate reaches 10-85%, the acid agglomerating agent is added into the polymerization system to reduce the pH value of the system, so that the concentration of effective components in the composite emulsifier is reduced, the stability of the small-particle-size emulsion particles is damaged, and the small-particle-size emulsion particles are agglomerated to increase the particle size. Because the lower the concentration of the effective components of the emulsifier is, the higher the particle size of the agglomerated product is, in order to control the average particle size of the latex to be 200nm-500nm, the concentration of the effective components of the composite emulsifier needs to be correspondingly controlled; therefore, the invention controls the concentration of the effective ingredients of the emulsifier by adjusting the pH in a V shape in the polymerization and agglomeration process.
The invention further aims to prevent the problem of occurrence (slag discharge) of emulsion particles with ultra-large particle size beyond a target range caused by overhigh acid concentration and overlow effective concentration of an emulsifier in a local area (mainly near an acid feeding area) in the polymerization and agglomeration process, and an emulsifier system compounded by the emulsifier S and the emulsifier I is used. By adjusting the dosage proportion of the anionic emulsifier S and the nonionic emulsifier I in the composite emulsifier system, a certain amount of the nonionic emulsifier I (an acid agglomerating agent is ineffective to the nonionic emulsifier I) still remains on the surface of the emulsion particle in a local area with too high acid concentration, so that the particle size is controlled, and the problem of slag tapping caused by excessive agglomeration is prevented.
In order to increase the reaction rate and adjust the product structure, the method of supplementing the second reaction solution when the monomer conversion rate is 40-70% is preferably adopted. The second reaction liquid contains one or more of an emulsifier S, a chain transfer agent and an initiator. Wherein the addition of the emulsifier and the addition of the initiator respectively have the effect of improving the polymerization reaction rate. The chain transfer agent is supplemented to play a role in regulating the molecular structure.
In order to increase the reaction rate, the reaction temperature is preferably increased to 75-85 ℃ after the conversion rate is more than 70%.
The invention has the advantages that the polymerization process and the agglomeration process are integrated, on one hand, an agglomeration kettle is saved, the device investment can be saved, on the other hand, the emulsion transfer time is reduced, the agglomeration and the polymerization are synchronously carried out, the one-step method is realized, the monomer conversion rate of more than 90 percent and the large-particle-size diene rubber emulsion product with the particle size of 200-500nm are obtained within the average time of about 10h, and the particle size growth speed is more than 20 nm/h.
Detailed Description
The technical solution of the present invention is illustrated by the following specific examples, which show specific implementation and specific operation procedures, but the scope of the present invention is not limited to the following examples.
The nonionic emulsifiers Lutensol To-3, To-5 and To-7 are available from Basff and are respectively isomeric tridecanol-3 (oxyethylene) ether, isomeric tridecanol-5 (oxyethylene) ether and isomeric tridecanol-7 (oxyethylene) ether. The deionized water is self-made. Other starting materials were from the alatin reagent company.
The particle size was measured by a particle sizer, malvern Nano-ZS90, and the result was a volume average particle size.
Example 1
(1) Adding a first reaction liquid comprising 95 parts of butadiene, 5 parts of styrene, 1.5 parts of potassium oleate, 1.5 parts of disproportionated rosin potassium, 0.45 part of tert-dodecyl mercaptan, 0.3 part of potassium persulfate, 0.3 part of potassium carbonate and 145 parts of deionized water into a reaction kettle, raising the pH of the first reaction liquid to 11, and carrying out polymerization reaction at 67 ℃;
(2) adding a benzoic acid solution when the monomer conversion rate is 85%, and adjusting the reaction pH to 9;
(3) adding a potassium hydroxide solution when the monomer conversion rate is 90%, and adjusting the pH value to 12;
(4) when the conversion rate is 98%, the reaction is completed to obtain the latex with the latex particle diameter of 305nm and the large particle diameter. The total reaction time was 12 hours, and the reduced particle size growth rate was 25 nm/h.
Example 2
(1) Adding a first reaction liquid comprising 95 parts of butadiene, 5 parts of styrene, 0.35 part of potassium oleate, 1.09 parts of disproportionated rosin potassium, 0.25 part of tert-dodecyl mercaptan, 0.6 part of potassium persulfate, 0.4 part of potassium carbonate, 1.5 parts of potassium sulfate, 0.1 part of potassium hydroxide and 90 parts of deionized water into a reaction kettle, raising the pH of the first reaction liquid To 12, and carrying out polymerization reaction when the temperature is 65 ℃;
(2) when the monomer conversion rate is 10%, adding an acetic anhydride solution, and adjusting the reaction pH to 4;
(3) adding potassium carbonate solution with the monomer conversion rate of 50%, and adjusting the pH value to 9.5; supplementing a second reaction liquid which comprises 0.2 part of potassium oleate, 0.5 part of disproportionated potassium rosinate and 0.1 part of tert-dodecyl mercaptan;
(4) when the conversion rate is 91%, the reaction is completed to obtain the latex with large particle size and the diameter of the latex particle is 500 nm. The total reaction time was 14 hours, and the reduced particle size growth rate was 36 nm/h.
Example 3
(1) Taking a first reaction liquid comprising 95 parts of butadiene, 5 parts of isoprene, 2.4 parts of disproportionated potassium rosinate, 31.0 parts of Lutensol To, 0.3 part of tert-dodecyl mercaptan, 0.3 part of potassium persulfate, 0.44 part of potassium carbonate, 0.06 part of potassium hydroxide and 140 parts of deionized water, adding the first reaction liquid into a reaction kettle, and heating the first reaction liquid To 67 ℃ for polymerization reaction, wherein the pH value of the first reaction liquid is 11.5;
(2) when the conversion rate is 70%, adding an acetic acid solution, and adjusting the reaction pH to 6;
(3) adding potassium hydroxide solution with the conversion rate of 75 percent, and adjusting the pH value to 11; the reaction temperature was increased to 75 ℃;
(4) when the conversion rate is 98%, the reaction is completed to obtain the latex with large particle size and the diameter of the latex particle of 320 nm. The total reaction time was 10 hours, and the reduced particle size growth rate was 32 nm/h.
Example 4
(1) Adding 100 parts of butadiene, 2.3 parts of potassium oleate, 0.4 part of disproportionated potassium rosinate, 56.3 parts of Lutensol To, 0.5 part of tert-dodecyl mercaptan, 0.25 part of potassium persulfate and 240 parts of deionized water into a reaction kettle, raising the pH of the first reaction solution To 10, and heating To 67 ℃ for polymerization reaction;
(2) adding a lactic acid solution when the butadiene reacts to reach a conversion rate of 30%, and adjusting the reaction pH to 5;
(3) adding sodium hydroxide solution with the conversion rate of 70 percent, and adjusting the pH value to 13; when the conversion rate is 80%, the reaction temperature is increased to 85 ℃;
(4) when the conversion rate is 95%, the reaction is completed to obtain the latex with large particle size and the diameter of the latex particle of 200 nm. The total reaction time was 8 hours, and the reduced particle size growth rate was 25 nm/h.
Example 5
(1) Adding a first reaction liquid comprising 92.5 parts of butadiene, 7.5 parts of styrene, 1.3 parts of potassium oleate, 1.2 parts of disproportionated rosin potassium, 0.45 part of Lutensol To-52.5 parts of tert-dodecyl mercaptan, 0.2 part of cumene hydroperoxide, 0.008 part of ferrous sulfate, 0.35 part of glucose, 0.25 part of potassium carbonate, 0.75 part of potassium sulfate, 0.25 part of sodium pyrophosphate and 200 parts of deionized water into a reaction kettle, adding the first reaction liquid To the reaction kettle, and heating To 55 ℃ To perform polymerization reaction, wherein the pH of the first reaction liquid is 11;
(2) when the conversion rate is 50%, adding a salicylic acid solution, and adjusting the reaction pH to 7; supplementing a second reaction solution which comprises 0.3 part of potassium persulfate and 0.2 part of ferrous sulfate;
(3) adding sodium carbonate solution with the conversion rate of 70 percent, and adjusting the pH value to 10;
(4) when the conversion rate is 93 percent, the reaction is finished to obtain the latex with large particle size and the diameter of emulsion particles of 280 nm. The total reaction time was 7 hours, and the reduced particle size growth rate was 40 nm/h.
Comparative example 1
(1) Adding 95 parts of butadiene, 5 parts of styrene, 1.5 parts of potassium oleate, 1.5 parts of disproportionated potassium rosinate, 0.45 part of tert-dodecyl mercaptan, 0.3 part of potassium persulfate, 0.3 part of potassium carbonate and 145 parts of deionized water into a reaction kettle, and heating to 67 ℃ for polymerization;
(2) when the conversion rate is 97%, the reaction is completed to obtain the latex with small particle size of the latex particle diameter of 105 nm. The reaction time was 12 hours.
(3) The small particle size latex was transferred to an agglomeration kettle, and 2.1 parts by dry weight of an acetic acid solution was added to 100 parts by dry weight of the small particle size latex for 30 minutes, and 10 minutes were spent, and after completion of the addition, the stirring was carried out for 10 minutes, and then 2 parts by dry weight of a potassium hydroxide solution was added, and the stirring was carried out for 10 minutes. Obtaining the latex with the latex particle diameter of 300nm and large particle diameter. The agglomeration time was 1 hour.
(4) The growth rate of the particle size is 23 nm/h.
Comparative example 2
(1) Adding 95 parts of butadiene, 5 parts of styrene, 0.75 part of potassium oleate, 1.75 parts of disproportionated potassium rosinate, 0.35 part of tert-dodecyl mercaptan, 0.6 part of potassium persulfate, 0.4 part of potassium carbonate, 1.5 parts of potassium sulfate, 0.1 part of potassium hydroxide and 90 parts of deionized water into a reaction kettle, and heating to 65 ℃ for polymerization reaction;
(2) when the conversion rate is 92%, the reaction is completed to obtain the latex with small particle size of 130nm in diameter of latex particles. The reaction time was 15 hours.
(3) The small particle size latex was transferred to an agglomeration kettle, and 1.88 parts by dry weight of an acetic acid solution was added to 100 parts by dry weight of the small particle size latex over 30 minutes, and 10 minutes were spent, and after completion of the addition, stirring was carried out for 10 minutes, and then 1.79 parts by dry weight of a potassium hydroxide solution was added, and stirring was carried out for 10 minutes. Obtaining the latex with the latex particle diameter of 380nm and large particle diameter. The agglomeration time was 1 hour.
(4) The growth rate of the particle size is 24 nm/h.
Comparative example 3
(1) Adding 95 parts of butadiene, 5 parts of isoprene, 0.4 part of potassium oleate, 3 parts of disproportionated potassium rosinate, 0.3 part of tert-dodecyl mercaptan, 0.3 part of potassium persulfate, 0.44 part of potassium carbonate, 0.06 part of potassium hydroxide and 140 parts of deionized water into a reaction kettle, and heating to 67 ℃ for polymerization reaction;
(2) when the conversion rate is 98%, the reaction is completed to obtain the latex with small particle size of 100nm in diameter of latex particles. The reaction time was 12 hours.
(3) The small particle size latex was transferred to an agglomeration kettle, and 2.27 parts by dry weight of an acetic acid solution was added to 100 parts by dry weight of the small particle size latex over 30 minutes, and 10 minutes were spent, and after completion of the addition, stirring was carried out for 10 minutes, and then 2.16 parts by dry weight of a potassium hydroxide solution was added, and stirring was carried out for 10 minutes. Obtaining the latex with latex particle diameter of 290nm and large particle diameter. The agglomeration time was 1 hour.
(4) The growth rate of the particle size is 22 nm/h.
Comparative example 4
(1) Adding 100 parts of butadiene, 7.5 parts of potassium oleate, 1.5 parts of disproportionated potassium rosinate, 0.5 part of tert-dodecyl mercaptan, 0.25 part of potassium persulfate and 240 parts of deionized water into a reaction kettle, and heating to 67 ℃ for polymerization;
(2) when the conversion rate is 95%, the reaction is completed to obtain the latex with small particle size of latex particle diameter 60 nm. The total reaction time was 11 hours.
(3) The small particle size latex was transferred to an agglomeration kettle, and 5.4 parts by dry weight of an acetic acid solution was added to 100 parts by dry weight of the small particle size latex over 30 minutes, and stirred for 10 minutes after completion of the addition, and then 5.14 parts by dry weight of a potassium hydroxide solution was added and stirred for 10 minutes. Obtaining the latex with large particle size and the diameter of the latex particle of 200 nm. The agglomeration time was 2 hours.
(4) The growth rate of the particle size is 15 nm/h.
Comparative example 5
(1) Adding 92.5 parts of butadiene, 7.5 parts of styrene, 2.6 parts of potassium oleate, 2.4 parts of disproportionated rosin potassium, 0.45 part of tert-dodecyl mercaptan, 0.2 part of cumene hydroperoxide, 0.008 part of ferrous sulfate, 0.35 part of glucose, 0.25 part of potassium carbonate, 0.75 part of potassium sulfate, 0.25 part of sodium pyrophosphate and 200 parts of deionized water into a reaction kettle, and heating to 55 ℃ for polymerization;
(2) when the conversion rate is 94%, the reaction is completed to obtain the latex with small particle size of 80nm in diameter of latex particles. The reaction time was 10 hours.
(3) The small particle size latex was transferred to an agglomeration kettle, and 3.15 parts by dry weight of an acetic acid solution was added to 100 parts by dry weight of the small particle size latex over 30 minutes, and 10 minutes was used, and after completion of the addition, the stirring was carried out for 10 minutes, and then 3.0 parts by dry weight of a potassium hydroxide solution was added, and the stirring was carried out for 10 minutes. Obtaining the latex with the latex particle diameter of 260nm and large particle diameter. The agglomeration time was 1 hour.
(4) The growth rate of the particle size is 24 nm/h.
Comparing the comparative example and the example, the invention saves the investment of an agglomeration kettle, the polymerization reaction time is the same or close, but the material transfer and agglomeration time is saved, so that the total production time is shortened, and the production efficiency is improved.
Claims (11)
1. An emulsion polymerization process comprising the steps of:
(1) adding the first reaction solution into a reaction kettle, heating to 55-85 ℃, wherein the pH value of the first reaction solution is more than or equal to 10; wherein the first reaction liquid comprises a monomer, an emulsifier, a chain transfer agent, an optional electrolyte, an initiator and deionized water;
(2) when the monomer conversion rate reaches 10-85%, adding an acid agglomerating agent to reduce the pH of the reaction system to 4-9;
(3) after the step (2), when the monomer conversion rate reaches 50-90%, adding an alkali substance to raise the pH of the reaction system to 9.5-13;
(4) after the monomer conversion rate reaches more than 90%, discharging after the reaction is finished to obtain a diene rubber latex product with large particle size;
the method is characterized in that the emulsifier in the step (1) is selected from a compound emulsifier system, and the compound emulsifier comprises an emulsifier S and an emulsifier I; wherein the emulsifier S is selected from carboxylic acid type anionic emulsifiers with pKa >5 of the corresponding carboxylic acid; the emulsifier I is selected from nonionic emulsifiers; the mass ratio of the emulsifier S to the total emulsifier is 30-100%, and the mass ratio of the emulsifier I to the total emulsifier is 0-70%.
2. The method of claim 1, comprising the steps of:
(1) adding the first reaction solution into a reaction kettle, heating to 55-85 ℃, and adjusting the pH value of the first reaction solution to 10-12; wherein the first reaction liquid comprises a monomer, an emulsifier, a chain transfer agent, an optional electrolyte, an initiator and deionized water;
(2) when the monomer conversion rate reaches 50-70%, adding an acid agglomerating agent to reduce the pH of the reaction system to 5-7;
(3) after the step (2), when the monomer conversion rate reaches 70-90%, adding an alkali substance to raise the pH of the reaction system to 10-12;
(4) after the monomer conversion rate reaches more than 95 percent, discharging after the reaction is finished to obtain a diene rubber latex product with large particle size.
3. The method according to claim 1, wherein the first reaction liquid comprises the following components by mass:
monomer 100 parts
1.8-9 parts of emulsifier
0.25 to 0.5 portion of chain transfer agent
0 to 2 portions of electrolyte
0.2 to 0.6 portion of initiator
90-240 parts of deionized water.
4. The method according to claim 3, wherein the first reaction liquid comprises the following components by mass:
monomer 100 parts
3-5 parts of emulsifier
0.3 to 0.45 portion of chain transfer agent
0.3 to 1.25 portions of electrolyte
0.25 to 0.3 portion of initiator
140 portions and 200 portions of deionized water.
5. The method of claim 1, wherein the emulsifier S is selected from one or more of sodium or potassium salts of disproportionated abietic acid, stearic acid, palmitic acid, oleic acid; the emulsifier I is selected from one or more of isomeric alcohol ethers; the mass ratio of the emulsifier S to the total emulsifier is 50-80%, and the mass ratio of the emulsifier I to the total emulsifier is 20-50%.
6. The method of claim 1, wherein the monomer in step (1) comprises one or more of butadiene, styrene, and isoprene, the initiator is one or more selected from potassium persulfate, cumene hydroperoxide, and tert-butyl hydroperoxide, the chain transfer agent is tert-dodecyl mercaptan, and the electrolyte is one or more selected from sodium salt, potassium salt, sodium hydroxide, and potassium hydroxide.
7. The process of claim 1, wherein step (1) is initiated thermally or by redox, and when redox initiation is used, the emulsion polymerization feed correspondingly comprises an initiation aid; the amount of the initiation aid is 0.1-1 part by mass based on 100 parts by mass of the monomer.
8. The method according to claim 1, wherein the acid agglomerating agent in step (2) is selected from one or more of organic acids with pKa between 1 and 5 and anhydrides thereof, and the base substance in step (3) is selected from inorganic bases or inorganic salts that are hydrolyzed to be basic.
9. The method as claimed in claim 8, wherein the acid agglomerating agent is selected from one or more of acetic acid, acetic anhydride, lactic acid, benzoic acid and salicylic acid, and the base substance is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and potassium phosphate.
10. The method as claimed in claim 1, wherein when the monomer conversion rate is 40-70%, a second reaction solution is supplemented, the second reaction solution contains one or more of an emulsifier S, a chain transfer agent and an initiator, the dosage of the supplemented emulsifier S is 0.1-1 part, the dosage of the supplemented chain transfer agent is 0.05-0.2 part, and the dosage of the supplemented initiator is 0.05-0.5 part, based on 100 parts of the mass of the monomer.
11. The process of claim 1, wherein the reaction temperature is controlled by a stepwise temperature control method, wherein the initial reaction temperature is 55-75 ℃ and the temperature is increased to 75-85 ℃ after the monomer conversion is greater than 70%.
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| CN110642984A (en) * | 2019-10-27 | 2020-01-03 | 天津大沽化工股份有限公司 | Preparation method of polydiene latex for preparing ABS resin |
| CN110655599A (en) * | 2019-10-27 | 2020-01-07 | 天津大沽化工股份有限公司 | Method for preparing large-particle-size latex particles by in-situ weak acid agglomeration method |
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