Chemical agglomeration method for polybutadiene latex

Abstract

The invention relates to the technical field of ABS (Acrylonitrile Butadiene Styrene) resin, and discloses a chemical agglomeration method of polybutadiene latex, which comprises the following steps: S1, introducing the raw material polybutadiene latex into a reaction kettle, adding a dispersing agent, stirring, and standing for aging; s2, adding an agglomerating agent into the mixed latex in the step S1 under the liquid level of the mixed latex, stirring, and standing for aging; s3, adding a stabilizer above the liquid level of the latex prepared in S2, and stirring to obtain target polybutadiene latex; a stirrer is arranged in the reaction kettle, and the stirrer adopts a tooth-shaped plate type stirring blade. By adopting the tooth-shaped plate type stirring blades, the stirring capacity of the stirrer can be improved, and the reaction time can be shortened. The stirring rotating speed is reduced, the maximum linear speed of the stirring edge is about 1m / s, and the shearing force is reduced. And precipitates generated in the chemical agglomeration reaction process are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of ABS resin, in particular to a polybutadiene latex chemical agglomeration method. Background Art

[0002] ABS resin is a general-purpose engineering resin, a high-molecular-weight polymer derived from the copolymerization and blending of acrylonitrile, butadiene, and styrene. To achieve optimal overall performance, the particle size of polybutadiene latex (PBL) must be controlled at around 300nm to graft copolymerize with styrene and acrylonitrile to produce a qualified ABS graft powder.

[0003] There are two methods for producing PBL latex: a one-step method and a two-step method. The one-step method directly produces a latex with a particle size of 300 nm in a PBL reactor. The two-step method first produces a 100 nm latex in a PBL reactor, then agglomerates it to obtain a 300 nm latex. Common agglomeration methods include polymer agglomeration, pressure agglomeration, and chemical agglomeration. Currently, chemical agglomeration is relatively more widely used.

[0004] Chemical agglomeration is a physical process that involves adding an agglomerating agent to alter the polarity and distribution of charge in the small-particle latex, causing it to recombine and form larger particles. The chemical agglomeration process typically utilizes a vertical reactor and batch production method, proceeding as follows: initial feed -> addition of agglomerating agent -> stirring -> aging -> addition of stabilizer -> aging and discharge. During the feeding process, the agglomerating agent must be added to the small-particle latex, a process known as instability. Any significant impact and agitation within the feeding area can disrupt the agglomeration process, leading to gelation and even implosion. The purpose of adding a stabilizer is to halt particle growth and terminate the reaction. The feeding process must be rapid and uniform.

[0005] In actual production, chemical agglomeration processes require complex and sophisticated process control. Factors such as process formulation, equipment manufacturing, feed method, and stirring speed significantly impact the process, leading to unsatisfactory particle size, excessive precipitates, and even implosion, resulting in material loss and unstable production. Reducing stirring speed and shortening reaction time are pressing challenges in current production. Summary of the Invention

[0006] The object of the present invention is to overcome the shortcomings of the prior art and provide a polybutadiene latex chemical agglomeration method.

[0007] In order to achieve the above object, the technical solution of the present invention is: a polybutadiene latex chemical agglomeration method comprising the following steps:

[0008] S1: introducing the raw material polybutadiene latex into a reactor, adding a dispersant, stirring, and aging;

[0009] S2: adding an agglomerating agent to the mixed latex in S1, wherein the agglomerating agent is added below the liquid surface of the mixed latex, stirred, and allowed to stand for aging;

[0010] S3: adding a stabilizer to the surface of the latex prepared in S2, and stirring to obtain the target polybutadiene latex;

[0011] The reactor is provided with an agitator, and the agitator adopts a "tooth-shaped plate" type stirring blade.

[0012] Furthermore, the outer wall of the "tooth-shaped plate" type stirring blade is tooth-shaped, the top width is smaller than the bottom width, and the bottom of the blade is arc-shaped and consistent with the arc of the inner wall of the bottom of the reactor.

[0013] Furthermore, a plurality of agglomerate feed ports are provided at the bottom end of the side wall of the reactor, and the plurality of agglomerate feed ports are located on different horizontal planes. The plurality of agglomerate feed ports are respectively connected to feed pipelines in a one-to-one correspondence, and a solenoid valve is provided on the feed pipeline. After the plurality of feed pipelines are merged, they are connected to the feed pump, and a controller is provided on the merged pipeline, and the controller is electrically connected to the solenoid valve.

[0014] Furthermore, the agglomerating agent is an organic weak acid selected from acetic acid; the stabilizer is an inorganic base selected from KOH or NaOH; and the dispersant is sodium salt of dioctyl sulfosuccinate.

[0015] Furthermore, the particle size of the raw material polybutadiene latex in S1 is 100 to 110 nm; the target particle size of the polybutadiene latex in S3 is 300 ± 20 nm.

[0016] Furthermore, the mass ratio between the raw material polybutadiene latex and the dispersant in S1 is 100: (0.02 to 0.075).

[0017] Furthermore, the mass ratio between the raw material polybutadiene latex and the agglomerating agent in S2 is 100:(2.0-2.5), and the mass ratio between the raw material polybutadiene latex and the stabilizer in S3 is 100:(1.7-2.1).

[0018] Furthermore, the stirring speed in S1 is 9-15 rpm, stirring for 3 to 5 minutes, and aging for 3 to 5 minutes.

[0019] Furthermore, the stirring speed in S2 is 9-15 rpm, stirring for 2 to 3 minutes, and aging for 2 to 3 minutes.

[0020] Furthermore, the stirring speed in S3 is 9-15 rpm, and the stirring is carried out for 3 to 6 minutes.

[0021] Beneficial effects of the present invention:

[0022] (1) After agglomeration, the present invention obtains a large-particle polybutadiene latex with a particle size range of 300±20 nm, which meets the requirements for downstream production of high-performance ABS resin.

[0023] (2) By adopting the method for adding and controlling the agglomerating agent and the stabilizer of the present invention, after several months of operation, each feed port can feed uniformly, and there is no pipeline blockage. The equipment scaling and latex precipitation during the agglomeration process are significantly reduced, and the average total precipitate in each batch accounts for less than 0.04% of the total material.

[0024] (3) After agglomeration, the latex particle size is more uniform and the particle size distribution is narrow, which can improve the grafting rate of the latex during the graft polymerization process. In the subsequent blending process, the amount of high-efficiency powder can be reduced.

[0025] (4) The tooth-shaped plate-type stirring blade of the present invention can improve the stirring capacity of the stirrer and shorten the reaction time. The stirring speed is reduced, and the maximum linear velocity of the stirring edge is about 1m / s, which reduces the shear force. The generation of precipitates during the chemical agglomeration reaction is reduced. Compared with traditional paddle-type blades, the stirring speed, mixing effect and shear force are more suitable for the chemical agglomeration reaction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a particle size distribution diagram of the polybutadiene latex prepared in Example 1 of the present invention;

[0027] Figure 2 This is a schematic structural diagram of a chemical agglomeration system according to Example 1 of the present invention;

[0028] Figure 3 This is a schematic structural diagram of a reactor according to Example 1 of the present invention;

[0029] Figure 4 This is a schematic diagram of the top view of the reactor structure of Example 1 of the present invention;

[0030] Figure 5 This is a schematic diagram of the reactor structure of Comparative Example 1.

[0031] In the figure: 1. Reactor; 2. Agitator; 3. "Tooth-shaped" stirring blade; 4. Feed pipeline; 5. Solenoid valve; 6. Feed pump; 7. Controller; 1', reactor; 2', agitator; 3', paddle blade. DETAILED DESCRIPTION

[0032] Example 1:

[0033] A polybutadiene latex chemical agglomeration method:

[0034] S1: 18000kg of 105nm small particle size polybutadiene latex (solid content 39.5%) was added to 30m 372 kg (5 wt %) of DOSS (sodium dioctyl sulfosuccinate) as a dispersant was added to the atmospheric pressure reactor 1, and the mixture was stirred at 10 rpm for 5 minutes and then aged for 5 minutes.

[0035] S2: 3600 kg (5 wt%) HAc aqueous solution was slowly added to the aged mixed latex at multiple points through the agglomerant feed port on the side wall of reactor 1 at a flow rate of 5500 kg / h and an instantaneous flow velocity of 0.25 m / s. After addition, the mixture was stirred at 10 rpm for 3 minutes, and then aged for 3 minutes.

[0036] S3: Start the stirrer and quickly and evenly add 2250 kg (7 wt%) of a KOH aqueous solution over the latex. The addition time is controlled to 15 minutes, followed by stirring at 10 rpm for 6 minutes to obtain agglomerated large-particle polybutadiene latex. Sample testing revealed that the resulting large-particle polybutadiene latex had a solids content of 31.5%, an average particle size of 305.6 nm, a particle size distribution (PDI) of 0.055, and a total precipitate of 3.6 kg (through a 200-mesh sieve).

[0037] The reactor 1 used in this embodiment is provided with an agitator 2, and the agitator 2 adopts a "tooth-shaped plate" type stirring blade 3. The outer wall of the "tooth-shaped plate" type stirring blade 3 is tooth-shaped, with a top width of 1500mm, a bottom width of 2000mm, and a height of 3000mm. The bottom of the "tooth-shaped plate" type stirring blade 3 is arc-shaped and consistent with the arc of the inner wall of the bottom of the reactor 1. The distance between the bottom of the "tooth-shaped plate" type stirring blade 3 and the inner wall of the bottom of the reactor 1 is 20mm. The reactor 1 is 4000mm high and 3000mm wide. Three agglomerate feed ports are provided at the bottom end of the side wall of the reactor 1. The three agglomerate feed ports are located on different horizontal planes. The three agglomerate feed ports are respectively connected to a feed pipeline 4. A solenoid valve 5 is provided on the feed pipeline 4. The three feed pipelines 4 are merged and connected to a feed pump 6. A controller 7 is provided on the merged pipeline. The controller 7 is electrically connected to the solenoid valve 5 to control the flow rate of the agglomerate.

[0038] Comparative Example 1:

[0039] A method for chemically agglomerating polybutadiene latex: Differences from Example 1: The stirrer 2' in the reactor 1' utilizes conventional paddle blades 3'. The paddle blades 3' are 1200 mm wide and are arranged in two rows, 1500 mm apart. The lower paddle blade 3' is 500 mm away from the lowest end of the inner wall of the reactor 1'. The stirring speed in steps S1, S2, and S3 is 30 rpm. The stirring reaction time in step S2 is 6 minutes. Agglomerated large-particle polybutadiene latex is obtained. Sampling and testing revealed that the resulting agglomerated large-particle polybutadiene latex had a solids content of 31.8%, an average particle size of 276.4 nm, a particle size distribution (PDI) of 0.083, and a total precipitate of 9.7 kg (through a 200-mesh sieve).

[0040] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

[0041] In the description of the present invention, it should be understood that the terms indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only used to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, they cannot be understood as limiting the present invention.

Claims

1. A polybutadiene latex chemical agglomeration method, characterized in that, The following steps are involved: S1: introducing the raw material polybutadiene latex into a reactor, adding a dispersant, stirring, and aging; S2: adding an agglomerating agent to the mixed latex in S1, wherein the agglomerating agent is added below the liquid surface of the mixed latex, stirred, and allowed to stand for aging; S3: adding a stabilizer to the surface of the latex prepared in S2, and stirring to obtain the target polybutadiene latex; The reactor is provided with an agitator, which adopts a "tooth-shaped plate" type stirring blade.

2. The polybutadiene latex chemical agglomeration method according to claim 1, wherein: The outer wall of the "tooth-shaped plate" type stirring blade is tooth-shaped, the top width is smaller than the bottom width, and the bottom of the blade is arc-shaped and consistent with the arc of the inner wall of the bottom of the reactor.

3. The polybutadiene latex chemical agglomeration method according to claim 1, wherein: A plurality of agglomerate feed ports are provided at the bottom end of the side wall of the reactor, and the plurality of agglomerate feed ports are located at different horizontal planes. The plurality of agglomerate feed ports are respectively connected to feed pipelines in a one-to-one correspondence, and a solenoid valve is provided on the feed pipeline. After the plurality of feed pipelines are merged, they are connected to the feed pump, and a controller is provided on the merged pipeline, and the controller is electrically connected to the solenoid valve.

4. The polybutadiene latex chemical agglomeration method according to claim 1, wherein: The agglomerating agent is an organic weak acid selected from acetic acid; the stabilizing agent is an inorganic base selected from KOH or NaOH; and the dispersing agent is sodium salt of dioctyl sulfosuccinate.

5. The polybutadiene latex chemical agglomeration method according to claim 1, wherein: The particle size of the raw material polybutadiene latex in S1 is 100-110 nm; the target particle size of the polybutadiene latex in S3 is 300±20 nm.

6. The polybutadiene latex chemical agglomeration method according to claim 1, wherein: The mass ratio between the raw material polybutadiene latex and the dispersant in S1 is 100:(0.02-0.075).

7. The polybutadiene latex chemical agglomeration method according to claim 1, wherein: The mass ratio between the raw material polybutadiene latex and the agglomerating agent in S2 is 100:(2.0-2.5), and the mass ratio between the raw material polybutadiene latex and the stabilizer in S3 is 100:(1.7-2.1).

8. The polybutadiene latex chemical agglomeration method according to claim 1, wherein: The stirring speed in S1 is 9-15 rpm, stirring is 3-5 minutes, and static aging is 3-5 minutes.

9. The polybutadiene latex chemical agglomeration method according to claim 1, wherein: The stirring speed in S2 is 9-15 rpm, stirring is 2-3 minutes, and aging is 2-3 minutes.

10. The polybutadiene latex chemical agglomeration method according to claim 1, wherein: The stirring speed in S3 is 9-15 rpm, and the stirring is carried out for 3-6 minutes.

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