Antibacterial and flame-retardant acrylonitrile-butadiene-styrene graft copolymer with core-shell structure and preparation method thereof

Abstract

The application provides a core-shell structure antibacterial and flame-retardant acrylonitrile-butadiene-styrene graft copolymer and a preparation method thereof. The core is a diene rubber polymer, and the shell is a polymer with a cation formed by reacting a polymerization product of an aromatic ethylene compound, a vinyl cyanide compound and a halogenated olefin with a quaternary ammonium reagent. The shell layer of the graft copolymer is covalently connected with a cationic group, and can be combined with a halogen counterion through electrostatic force, so that the antibacterial and flame-retardant effects of the acrylonitrile-butadiene-styrene graft copolymer impact modifier can be synergistically improved, and thus the graft copolymer can be widely used in toughening, antibacterial and flame-retardant modification of various resins.

Description

Technical Field

[0001] This invention relates to a method for preparing acrylonitrile-butadiene-styrene graft copolymers, belonging to the field of polymers. Background Technology

[0002] Core-shell acrylonitrile-butadiene-styrene graft copolymer is an excellent impact modifier. It can be used as an independent raw material to be blended into SAN resin to prepare high-impact ABS resin, or to toughen PVC, PC, recycled ABS, PC / ABS recycled and other resin alloys.

[0003] Traditional plastic products generally lack antibacterial properties, which greatly limits their applicability in applications requiring high antibacterial properties (such as health products, medical devices, and food packaging). Currently, some patents (such as CN114573943A, CN114805934A, and CN115044163A) propose adding antibacterial agents (such as small organic cationic molecules and silver-loaded particles) as blending additives to resins to improve their antibacterial capabilities. However, these methods generally suffer from poor bonding between the antibacterial agent and the resin matrix. During long-term use, the antibacterial components easily detach from the resin matrix, leading to a decrease in antibacterial ability. Furthermore, small organic cationic molecules are readily soluble in water, limiting the application of resin products in aquatic environments. Additionally, metal ions can easily penetrate the human body during long-term use, potentially causing health damage. CN114163575A discloses a process for introducing antibacterial agent monomers into ABS resin through bulk polymerization, which effectively improves the bonding force between the antibacterial agent and the resin matrix. However, it still has problems such as the antibacterial agent being easily encapsulated and the product range being limited (unable to be extended to PVC, PC and other resin alloys).

[0004] Similar to antibacterial agents, small-molecule flame retardants (such as organic flame retardants and inorganic flame retardants) are often added during the plastic processing to eliminate or reduce fire hazards in plastic products. However, flame retardants also have interfacial compatibility issues with the base resin. Under high temperatures and during prolonged storage, small-molecule flame retardants will gradually overcome resistance and migrate to the surface of the plastic part, not only reducing their flame retardant effect but also causing mold fouling during high-temperature injection molding, affecting product quality. Summary of the Invention

[0005] The present invention aims to provide a core-shell structured antibacterial and flame-retardant acrylonitrile-butadiene-styrene graft copolymer and its preparation method. The method can prepare an acrylonitrile-butadiene-styrene graft copolymer with efficient and long-lasting antibacterial and flame-retardant effects, which can be widely used for toughening, antibacterial and flame-retardant modification of various resins.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A core-shell structured antibacterial and flame-retardant acrylonitrile-butadiene-styrene graft copolymer has the following characteristics:

[0008] The core is a diene-based rubber polymer.

[0009] The shell is a cationic polymer formed by reacting the polymerization product of the shell monomer with a quaternizing agent; wherein the shell monomer comprises an aromatic ethylene compound, a vinyl cyanide compound, and a haloolefin, with the aromatic ethylene compound accounting for 50%-80% of the total mass of the shell monomer, the vinyl cyanide compound accounting for 15%-45% of the total mass of the shell monomer, and the haloolefin accounting for 5%-35% of the total mass of the shell monomer.

[0010] The total mass ratio of the shell monomer to the core is 1:2 to 1:1.

[0011] The preparation method of the core-shell structured antibacterial and flame-retardant acrylonitrile-butadiene-styrene graft copolymer includes the following steps:

[0012] (1) Add diene rubber latex to the reactor, and then continuously add aromatic ethylene compounds, vinyl cyanide compounds, halogenated olefins and initiators to the reactor and polymerize at 50-80℃. Water, emulsifier and chain transfer agent can be added during the polymerization process.

[0013] The diene rubber latex contains at least a diene rubber (i.e., the core part of a core-shell structure) polymerized from diene monomers, an emulsifier, and water. The diene rubber accounts for 20% to 60% of the latex by mass, and the rubber diameter is 250 to 450 nm. The emulsifier accounts for 0.5% to 2.4% of the latex by mass. The diene monomers include, but are not limited to, 1,3-butadiene, isoprene, isoprene, chloroprene, and their derivatives.

[0014] Of which, based on 100 parts by weight of dry rubber content in latex, aromatic ethylene compounds comprise 25 to 80 parts by weight, vinyl cyanide compounds comprise 7.5 to 45 parts by weight, halogenated olefins comprise 2.5 to 35 parts by weight, and initiators comprise 0.05 to 0.3 parts by weight.

[0015] (2) When the conversion rate of the aromatic ethylene compound, vinyl cyanide compound and haloolefin monomer in the reactor is ≥90%, the reaction shall be stopped, preferably when the conversion rate is ≥95%.

[0016] (3) The polymerized latex is coagulated and washed, and then mixed with 3 to 200 parts by weight of quaternizing agent and 100 to 2000 parts by weight of water. The mixture is reacted at 20°C to 100°C for 1 to 10 hours to complete the Menshutkin reaction and form a cationic structure. The solid is then filtered to separate it, excess quaternizing agent is washed away with water, and the mixture is dehydrated and dried to obtain an antibacterial and flame-retardant acrylonitrile-butadiene-styrene graft copolymer.

[0017] The emulsifiers described in this invention include, but are not limited to, higher fatty alcohol sulfates, higher alkyl sulfonates, alkylaryl sulfonates, aryl sulfonates, fatty acid soaps, etc.

[0018] The polymerization process described in this invention may include the addition of water and chain transfer agents, including but not limited to thiol compounds.

[0019] The aromatic ethylene compound described in this invention is at least one selected from styrene, α-methylstyrene, α-ethylstyrene, p-methylstyrene, and p-ethylstyrene.

[0020] The vinyl cyanide described in this invention is at least one selected from acrylonitrile, methacrylonitrile, and ethyl acrylonitrile.

[0021] The haloolefins described in this invention include, but are not limited to, the following structures:

[0022]

[0023] The initiators described in this invention include, but are not limited to, one or more of peroxide initiators and persulfate initiators, and the initiators may be used alone or in combination with redox catalysts.

[0024] The quaternizing agents described in this invention include, but are not limited to, the following structures:

[0025]

[0026] The coagulation, washing, and drying processes described in this invention are conventional procedures in the field. The coagulant used for coagulation can be one or more of the following: sulfuric acid, acetic acid, hydrochloric acid, nitric acid, magnesium sulfate, and calcium carbonate aqueous solution.

[0027] The core-shell structured antibacterial and flame-retardant acrylonitrile-butadiene-styrene graft copolymer of the present invention can be added to various resins (such as SAN, PC, PVC, etc.) as an impact modifier, and can be widely used for toughening, antibacterial and flame-retardant modification of various resins.

[0028] Beneficial effects

[0029] According to the preparation method of the acrylonitrile-butadiene-styrene graft copolymer of the present invention, since cationic groups are grafted into the acrylonitrile-butadiene-styrene graft copolymer, and halogen counterions are electrostatically bonded, a high-strength bond between the antibacterial and flame retardant and the copolymer can be achieved, effectively improving the bonding force between the antibacterial and flame retardant and the polymer matrix, and extending the service life of the antibacterial and flame retardant. In addition, since the cationic groups are grafted into the shell layer of the core-shell structure copolymer, the antibacterial and flame retardant components are mainly concentrated on the surface of the copolymer rather than being embedded in the interior, thus increasing the contact area between the antibacterial and flame retardant components and the external environment, and significantly improving the antibacterial and flame retardant effects. Detailed Implementation

[0030] The following embodiments will further illustrate the method provided by the present invention, but the present invention is not limited to the listed embodiments, and should also include any other known modifications within the scope of the claims of the present invention.

[0031] Unless otherwise specified, the raw materials used in the following embodiments and comparative examples of this invention are all obtained from commercial sources.

[0032] Example 1:

[0033] (1) Polybutadiene rubber latex (40% by mass of polybutadiene rubber in the latex, with a rubber diameter of 300 nm; potassium oleate as emulsifier, accounting for 1.2% by mass of the latex) was added to the reactor, wherein the dry rubber content in the latex was 100 parts by mass. Subsequently, 70 parts by mass of styrene, 20 parts by mass of acrylonitrile, 10 parts by mass of p-chloromethylstyrene, 0.2 parts by mass of potassium persulfate as initiator, 0.2 parts by mass of tert-dodecyl mercaptan as chain transfer agent, 0.2 parts by mass of potassium oleate as emulsifier, and 100 parts by mass of water were continuously added to the reactor and polymerization was carried out at 60°C.

[0034] (2) Stop the reaction when the conversion rate of monomer in the reactor is ≥95%.

[0035] (3) The polymerized latex was coagulated with sulfuric acid and washed three times with water. Then it was mixed with 200 parts by weight of 30% trimethylamine aqueous solution and reacted at 40°C for 8 hours to complete the Menshutkin reaction and form a cationic structure. The solid was then filtered to separate the solid, washed with water to remove excess quaternizing reagent, and fluidized and dried to obtain an antibacterial and flame-retardant acrylonitrile-butadiene-styrene graft copolymer impact modifier.

[0036] Examples 2-6:

[0037] The differences between Examples 2-6 and Example 1 are shown in Table 1. The other raw materials, experimental conditions and reaction steps are the same as those in Example 1.

[0038] Table 1. Differences between Examples 2-6 and Example 1

[0039]

[0040] Comparative Example 1:

[0041] (1) Polybutadiene rubber latex (40% by mass of polybutadiene rubber in the latex, with a rubber diameter of 300 nm; potassium oleate as emulsifier, accounting for 1.2% by mass of the latex) was added to the reactor, wherein the dry rubber content in the latex was 100 parts by mass. Subsequently, 75 parts by mass of styrene, 25 parts by mass of acrylonitrile, 0.2 parts by mass of potassium persulfate as initiator, 0.2 parts by mass of tert-dodecyl mercaptan as chain transfer agent, 0.2 parts by mass of potassium oleate as emulsifier, and 100 parts by mass of water were continuously added to the reactor, and polymerization was carried out at 60°C.

[0042] (2) Stop the reaction when the conversion rate of the monomer in the reactor is ≥95%.

[0043] (3) The polymerized latex was coagulated with sulfuric acid, washed with water three times, and then the solid was separated by filtration and fluidized drying to obtain an acrylonitrile-butadiene-styrene graft copolymer impact modifier.

[0044] The antibacterial rate of the impact modifiers in Examples 1-6 and the comparative example was tested (test standard was QB / T2591-2003), and the specific results are shown in Table 2.

[0045] Table 2 Comparison of antibacterial rates between Examples 1-6 and the comparative examples

[0046] Antibacterial rate / % Comparative Example 90 Example 1 99 Example 2 99 Example 3 99 Example 4 99 Example 5 99 Example 6 99

[0047] As can be seen from the test results of Examples 1-6 and the comparative examples, the core-shell structure antibacterial and flame-retardant acrylonitrile-butadiene-styrene graft copolymer impact modifier prepared by the present invention can effectively improve the antibacterial ability of the prepared impact modifier compared with the acrylonitrile-butadiene-styrene graft copolymer impact modifier prepared in the comparative examples.

[0048] ABS resins were prepared by blending the impact modifiers of Examples 1-6 and the comparative example with the same batch of self-made SAN (styrene-acrylonitrile copolymer) resin at an equal mass ratio (1:3), and their horizontal burning speed was tested (test standard is ISO3795). The specific results are shown in Table 3.

[0049] Table 3 Comparison of horizontal linear combustion rates between Examples 1-6 and the comparative examples.

[0050]

[0051] As can be seen from the test results of Examples 1-6 and the comparative examples, the core-shell structure antibacterial and flame-retardant acrylonitrile-butadiene-styrene graft copolymer impact modifier prepared by the present invention can effectively improve the flame retardancy of the prepared resin compared with the acrylonitrile-butadiene-styrene graft copolymer impact modifier prepared in the comparative examples.

Claims

1. A core-shell structured antibacterial and flame-retardant acrylonitrile-butadiene-styrene graft copolymer, having the following characteristics: The core is a diene-based rubber polymer. The shell is a cationic polymer formed by reacting the polymer of the shell monomer with a quaternizing agent; wherein, The shell monomers include aromatic ethylene compounds, vinyl cyanide compounds, and halogenated olefins; The total mass ratio of the shell monomer to the core is 1:2 to 1:

1.

2. The graft copolymer according to claim 1, wherein, Aromatic ethylene compounds account for 50%-80% of the total mass of the shell monomers, vinyl cyanide compounds account for 15%-45% of the total mass of the shell monomers, and halogenated olefins account for 5%-35% of the total mass of the shell monomers.

3. The graft copolymer according to claim 1 or 2, wherein, The aromatic ethylene compound is selected from at least one of styrene, α-methylstyrene, α-ethylstyrene, p-methylstyrene, and p-ethylstyrene.

4. The graft copolymer according to claim 1 or 2, wherein, The vinyl cyanide is selected from at least one of acrylonitrile, methacrylonitrile, and ethyl acrylonitrile.

5. The graft copolymer according to any one of claims 1-2, wherein, The haloolefin includes at least one of the following structures:

6. The graft copolymer according to any one of claims 1-2, wherein, The quaternizing agent includes at least one of the following structures:

7. The method for preparing the graft copolymer according to any one of claims 1-6, comprising the following steps: (1) Add diene rubber latex to the reactor, and then add aromatic ethylene compound, vinyl cyanide compound, halogenated olefin and initiator to the reactor for polymerization; (2) Stop the reaction when the conversion rate of olefin monomers in the reactor is ≥90%; (3) The polymerized latex is coagulated and washed, and then mixed with quaternizing reagent and water to react and obtain antibacterial flame retardant acrylonitrile-butadiene-styrene graft copolymer.

8. The method according to claim 7, wherein, Stop the reaction when the conversion rate is ≥95%.

9. The method according to claim 7, wherein, Diene rubber latex contains at least diene rubber polymerized from diene monomers, emulsifiers, and water; Diene rubber accounts for 20%-60% of the latex by mass, with a rubber diameter of 250 to 450 nm, and emulsifier accounts for 0.5%-2.4% of the latex by mass. The diene monomers include at least one of 1,3-butadiene, isoprene, isoprene, and chloroprene.

10. The method according to claim 7 or 9, wherein, Based on 100 parts by weight of dry rubber content in latex, the aromatic ethylene compound comprises 25 to 80 parts by weight, the vinyl cyanide compound comprises 7.5 to 45 parts by weight, the halogenated olefin comprises 2.5 to 35 parts by weight, the initiator comprises 0.05 to 0.3 parts by weight, and the quaternizing agent comprises 3 to 200 parts by weight.

11. The method according to any one of claims 7-9, wherein, The polymerization temperature is 50-80℃.

12. The method according to any one of claims 7-9, wherein, Step (3) react at 20°C to 100°C for 1 to 10 hours.

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