Heat-resistant acrylic ester-styrene-acrylonitrile core-shell graft copolymer, latex thereof and preparation method of heat-resistant acrylic ester-styrene-acrylonitrile core-shell graft copolymer

Abstract

The invention discloses an acrylate-styrene-acrylonitrile core-shell grafted copolymer, latex thereof and a preparation method. The microstructure of the acrylate-styrene-acrylonitrile core-shell grafted copolymer sequentially comprises a core part, a core layer and a shell layer from the center to the periphery, wherein the core part comprises a structural unit formed by converting an acrylate monomer, a structural unit formed by converting a grafting agent and a structural unit formed by converting a cross-linking agent; the core layer comprises a structural unit formed by converting an acrylate monomer and a structural unit formed by converting a grafting agent, and the shell layer comprises a structural unit formed by converting a vinyl aromatic monomer. At least one of the core layer and the shell layer comprises a structural unit formed by converting a maleimide monomer containing a silicon-oxygen group. The heat-resistant ASA resin prepared by the preparation method disclosed by the invention has relatively good impact strength, processability and rigidity while the heat-resistant temperature is obviously increased.

Description

Technical Field

[0001] The present invention belongs to the field of polymer materials, and relates to a heat-resistant acrylate-styrene-acrylonitrile core-shell graft copolymer, its latex, and a preparation method thereof. Background Art

[0002] The terpolymer of styrene-acrylonitrile-butyl acrylate (ASA resin) has mechanical properties similar to those of the acrylonitrile-butadiene-styrene terpolymer (ABS resin). Since the polyacrylate rubber with no double bond structure replaces the polybutadiene rubber in ABS, the weather resistance of ASA is about 10 times higher than that of ABS, and excellent impact resistance can still be maintained after long-term outdoor use. Moreover, ASA is superior to ABS resin in terms of solvent resistance and colorability. In addition, ASA is an antistatic material that can reduce dust on the resin surface area. ASA can be widely applied to fields such as automobiles, electronics, electrical appliances, textiles, utensils, and building materials. However, the heat resistance of general ASA resin is insufficient, which limits its application in fields such as high-temperature automotive parts. Therefore, many domestic and foreign enterprises have successively developed heat-resistant ASA resin.

[0003] Existing heat-resistant ASA resins are often prepared by blending and modifying a composition of ASA rubber powder, acrylonitrile-styrene copolymer (SAN resin), heat-resistant modifier, and other processing aids. The addition of the heat-resistant modifier will increase the brittleness of the product. In order to obtain better impact strength, it is necessary to increase the usage amount of ASA rubber powder, but this will bring side effects such as reduced processing fluidity. And the blending and modification method has high requirements for equipment and needs to ensure the uniformity of dispersion during blending, otherwise it will affect the heat resistance and requires secondary processing.

[0004] CN111138610B discloses a preparation method of a high impact resistance and high heat resistance ASA resin. First, a high impact resistance ASA emulsion is mixed with a high heat resistance AMS (copolymer of α-methylstyrene, styrene, and acrylonitrile) emulsion; then an electrolyte is added to cause co-aggregation of the mixture; then monomers such as α-methylstyrene, styrene, and acrylonitrile are added for suspension polymerization to prepare a heat-resistant ASA resin. The high heat-resistant ASA resin prepared by this method can better balance toughness and heat resistance and does not require secondary processing. However, this method involves multiple polymerization reactions such as ASA emulsion polymerization, AMS emulsion polymerization, and suspension polymerization, and the process is relatively cumbersome.

[0005] CN105419143B discloses a heat-resistant ASA resin composition for eliminating tiger skin patterns and a preparation method thereof. The method uses the following components and raw materials with the content by weight: 30 - 50 parts of ASA rubber powder, 30 - 60 parts of SAN resin, 5 - 15 parts of tiger skin pattern improver, 5 - 20 parts of heat-resistant agent, 0.5 - 1.5 parts of processing aid, and prepares the heat-resistant ASA resin composition through processing and blending. This method introduces 5 - 20 parts of N-phenyl maleimide-based heat-resistant agent. Such an auxiliary agent has a relatively large rigidity, and it is easy to cause a large deterioration of the impact resistance after being added. In addition, the addition amount of the heat-resistant agent in this method is relatively large, and the dispersion during the blending process is difficult, and it is not easy to fully exert its performance.

[0006] Therefore, there is still a need in the art for an acrylate-styrene-acrylonitrile core-shell graft copolymer that has improved heat resistance, while maintaining good impact strength, processability, and rigidity, and has a simple preparation process. Summary of the Invention

[0007] Aiming at the problems existing in the prior art, the present invention uses a seed emulsion polymerization process to prepare an acrylate-styrene-acrylonitrile core-shell graft copolymer with better heat resistance, and then blends it with SAN resin to prepare a heat-resistant ASA resin with excellent comprehensive performance. The present invention first prepares a polyacrylate seed latex, and then when preparing a large-particle-size polyacrylate latex and / or preparing a graft copolymer latex, introduces a maleimide monomer containing a siloxane group to obtain an acrylate-styrene-acrylonitrile core-shell graft copolymer powder containing a cyclic group, and then blends it with SAN resin for preparation. The maleimide monomer containing a siloxane group used in the present invention contains a highly rigid cyclic group and a highly flexible siloxane group. Therefore, the prepared heat-resistant ASA resin has better impact strength, processability, and rigidity while the heat-resistant temperature is significantly increased.

[0008] Specifically, one aspect of the present invention provides an acrylate-styrene-acrylonitrile core-shell graft copolymer, and the microstructure of the acrylate-styrene-acrylonitrile core-shell graft copolymer sequentially includes a core part, a core layer, and a shell layer from the center to the periphery;

[0009] Among them, the core part includes a structural unit converted from an acrylate monomer, a structural unit converted from a grafting agent, and a structural unit converted from a crosslinking agent;

[0010] The core layer includes a structural unit converted from an acrylate monomer and a structural unit converted from a grafting agent, and the core layer optionally further includes a structural unit converted from a maleimide monomer containing a siloxane group;

[0011] The shell layer comprises structural units formed from vinyl aromatic monomers, and optionally further comprises one or more selected from structural units formed from maleimide monomers containing siloxane groups and structural units formed from vinyl cyanide monomers;

[0012] The mass ratio of the core to the core layer is (0.4 - 10):100;

[0013] The mass fraction of the shell layer in the acrylate-styrene-acrylonitrile core-shell graft copolymer is 40% - 60%;

[0014] The mass ratio of the structural units formed from maleimide monomers containing siloxane groups to the structural units formed from acrylate monomers in the core layer is (0 - 1):100;

[0015] The mass fraction of the structural units formed from maleimide monomers containing siloxane groups in the shell layer in the shell layer is 0 - 30%;

[0016] At least one of the core layer and the shell layer comprises structural units formed from maleimide monomers containing siloxane groups.

[0017] In one or more embodiments, the shell layer comprises structural units formed from vinyl aromatic monomers and structural units formed from vinyl cyanide monomers, and optionally further comprises structural units formed from maleimide monomers containing siloxane groups.

[0018] In one or more embodiments, the maleimide monomers containing siloxane groups are compounds having siloxane groups and N-phenylmaleimide groups, preferably compounds having siloxane groups and one or two N-phenylmaleimide groups.

[0019] In one or more embodiments, the maleimide monomers containing siloxane groups are selected from one or more of dimethyl(4,4-bismaleimidophenoxy)silane, methylphenyl(4,4-bismaleimidophenoxy)silane, diphenyl(4,4-bismaleimidophenoxy)silane, trimethyl(4-maleimidophenoxy)silane, and dimethylphenyl(4-maleimidophenoxy)silane.

[0020] In one or more embodiments, the maleimide monomers containing siloxane groups in the core layer have two N-phenylmaleimide groups; preferably, the maleimide monomers containing siloxane groups in the core layer are selected from one or more of dimethyl(4,4-bismaleimidophenoxy)silane, methylphenyl(4,4-bismaleimidophenoxy)silane, and diphenyl(4,4-bismaleimidophenoxy)silane.

[0021] In one or more embodiments, the siloxane group-containing maleimide monomer in the shell layer has one N-phenylmaleimide group; preferably, the siloxane group-containing maleimide monomer in the shell layer is selected from one or both of trimethyl(4-maleimidophenoxy)silane and dimethylphenyl(4-maleimidophenoxy)silane.

[0022] In one or more embodiments, the siloxane group-containing maleimide monomer in the shell layer has two N-phenylmaleimide groups; preferably, the siloxane group-containing maleimide monomer in the core layer is selected from one or more of dimethyl(4,4-bismaleimidophenoxy)silane, methylphenyl(4,4-bismaleimidophenoxy)silane, and diphenyl(4,4-bismaleimidophenoxy)silane.

[0023] In one or more embodiments, the acrylate monomer in the core and the acrylate monomer in the core layer are each independently one or more acrylate alkyl esters having the structural formula CH 2 =CHCOOR, where R is a C1-C15 alkyl group, preferably a C1-C4 linear alkyl group; preferably, the acrylate monomer in the core and the acrylate monomer in the core layer are each independently selected from one or more of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylbutyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, hexyl acrylate, heptyl acrylate, n-pentyl acrylate, and lauryl acrylate; preferably, the acrylate monomer in the core and the acrylate monomer in the core layer are butyl acrylate.

[0024] In one or more embodiments, the grafting agent in the core and the grafting agent in the core layer are each independently one or more compounds containing two or more different unsaturated vinyl functional groups; preferably, the grafting agent in the core and the grafting agent in the core layer are each independently selected from one or more of allyl methacrylate, triallyl isocyanurate, triallylamine, and diallylamine; preferably, the grafting agent in the core and the grafting agent in the core layer are allyl methacrylate.

[0025] In one or more embodiments, the crosslinking agent is one or more compounds containing two or more identical unsaturated vinyl functional groups; preferably, the crosslinking agent is selected from one or more of ethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, and 1,3-propanediol diacrylate; preferably, the crosslinking agent is ethylene glycol dimethacrylate.

[0026] In one or more embodiments, the vinyl aromatic monomer is selected from one or more of styrene, α-methylstyrene, and p-methylstyrene, preferably styrene.

[0027] In one or more embodiments, the vinyl cyanide monomer is selected from one or two of acrylonitrile and methacrylonitrile, preferably acrylonitrile.

[0028] In one or more embodiments, in the core, the mass ratio of the structural unit converted from the grafting agent to the structural unit converted from the acrylate monomer is (0.2 - 3):100.

[0029] In one or more embodiments, in the core, the mass ratio of the structural unit converted from the crosslinking agent to the structural unit converted from the acrylate monomer is (0.2 - 3):100.

[0030] In one or more embodiments, in the core layer, the mass ratio of the structural unit converted from the grafting agent to the structural unit converted from the acrylate monomer is (0.2 - 2):100.

[0031] In one or more embodiments, the core layer includes or does not include the structural unit converted from the crosslinking agent; preferably, the core layer includes the structural unit converted from the crosslinking agent but does not include the structural unit converted from the maleimide monomer containing a siloxane group, and in the core layer, the mass ratio of the structural unit converted from the crosslinking agent to the structural unit converted from the acrylate monomer is (0.2 - 2):100; preferably, the core layer includes the structural unit converted from the maleimide monomer containing a siloxane group, includes or does not include the structural unit converted from the crosslinking agent, and in the core layer, the mass ratio of the structural unit converted from the crosslinking agent to the structural unit converted from the acrylate monomer is (0 - 2):100;

[0032] In one or more embodiments, the mass fraction of the structural unit converted from the vinyl aromatic monomer in the shell layer is 70% - 80%, and the mass fraction of the structural unit converted from the vinyl cyanide monomer in the shell layer is 0 - 25%, preferably 5 - 25%.

[0033] In one or more embodiments, the core layer includes or does not include the structural unit converted from the maleimide monomer containing a siloxane group, the shell layer includes the structural unit converted from the maleimide monomer containing a siloxane group, and the mass fraction of the structural unit converted from the maleimide monomer containing a siloxane group in the shell layer is 2.5 - 30%, preferably 5 - 25%, more preferably 5 - 20%.

[0034] The present invention also provides an acrylate-styrene-acrylonitrile core-shell graft copolymer latex, which is an aqueous dispersion of the acrylate-styrene-acrylonitrile core-shell graft copolymer described in any one of the embodiments herein.

[0035] The present invention also provides a method for preparing the acrylate-styrene-acrylonitrile core-shell graft copolymer described in any one of the embodiments herein or the acrylate-styrene-acrylonitrile core-shell graft copolymer latex described in any one of the embodiments herein, and the method comprises the following steps:

[0036] (1) In the presence of water, an emulsifier, an electrolyte and a water-soluble initiator, reacting an acrylate monomer, a grafting agent and a crosslinking agent to form a core, thereby obtaining a seed latex;

[0037] (2) In the presence of water, an emulsifier, an electrolyte and a water-soluble initiator, reacting the seed latex obtained in step (1), an acrylate monomer, a grafting agent, an optionally present crosslinking agent and an optionally present maleimide monomer containing a siloxane group, to form a core layer on the surface of the core, thereby obtaining a polyacrylate latex;

[0038] (3) In the presence of water, an emulsifier, an electrolyte and an oil-soluble initiator, reacting the polyacrylate latex obtained in step (2), a vinyl aromatic monomer, an optionally present vinyl nitrile monomer and an optionally present maleimide monomer containing a siloxane group, to form a shell layer on the surface of the core layer, thereby obtaining an acrylate-styrene-acrylonitrile core-shell graft copolymer latex;

[0039] Wherein, a maleimide monomer containing a siloxane group is added to the reaction system of at least one of step (2) and step (3).

[0040] In one or more embodiments, the maleimide monomer containing a siloxane group is added or not added to the reaction system of step (2), and the maleimide monomer containing a siloxane group is added to the reaction system of step (3).

[0041] In one or more embodiments, the emulsifiers in step (1), step (2) and step (3) are each independently selected from one or more of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium octadecyl sulfate, sodium oleate, potassium dodecyl sulfate, potassium dodecylbenzenesulfonate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium oleate, potassium dodecylbenzenesulfonate, potassium octadecyl sulfate, potassium rosin and potassium oleate, and preferably sodium dodecyl sulfate.

[0042] In one or more embodiments, the electrolytes in step (1), step (2), and step (3) are each independently selected from one or more of sodium chloride, potassium chloride, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate, preferably sodium bicarbonate.

[0043] In one or more embodiments, the water-soluble initiators in step (1) and step (2) are selected from one or more of sodium persulfate, potassium persulfate, ammonium persulfate, potassium peroxophosphate, and hydrogen peroxide, preferably potassium persulfate.

[0044] In one or more embodiments, the oil-soluble initiator in step (3) is selected from one or more of tert-butyl peroxide, cumene hydroperoxide, p-menthane hydroperoxide, di-tert-butyl peroxide, tert-butyl cumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, benzoyl peroxide, diisopropylbenzene hydroperoxide, 3,5,5-trimethylhexanol peroxide, tert-butyl peroxyisobutyrate, azobisisobutyronitrile, azo-bis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and azobis(isobutyric acid methyl ester), preferably cumene hydroperoxide.

[0045] In one or more embodiments, in step (1), the mass ratio of water to the acrylate monomer is (150 - 200):100.

[0046] In one or more embodiments, in step (1), the mass ratio of the emulsifier to the acrylate monomer is (0.5 - 3):100.

[0047] In one or more embodiments, in step (1), the mass ratio of the electrolyte to the acrylate monomer is (0.3 - 0.45):100.

[0048] In one or more embodiments, in step (1), the mass ratio of the water-soluble initiator to the acrylate monomer is (0.25 - 0.5):100.

[0049] In one or more embodiments, in step (1), part of the acrylate monomer, part of the grafting agent, part of the crosslinking agent, part of the water-soluble initiator, part of the emulsifier, and part of the water are gradually added to the reaction system in the form of a first pre-emulsion during the reaction process. The masses of the acrylate monomer, grafting agent, crosslinking agent, water-soluble initiator, and emulsifier in the first pre-emulsion are 60% - 90% of the masses of the acrylate monomer, grafting agent, crosslinking agent, water-soluble initiator, and emulsifier used in step (1), respectively.

[0050] In one or more embodiments, in step (1), the reaction temperature is 70 - 80 °C, and the reaction proceeds until the polymerization conversion rate ≥ 98%.

[0051] In one or more embodiments, in step (2), the mass ratio of the added water to the acrylate monomer is (150 - 200):100.

[0052] In one or more embodiments, in step (2), the mass ratio of the emulsifier to the acrylate monomer is (0.5 - 3):100.

[0053] In one or more embodiments, in step (2), the mass ratio of the electrolyte to the acrylate monomer is (0.3 - 0.45):100.

[0054] In one or more embodiments, in step (2), the mass ratio of the water-soluble initiator to the acrylate monomer is (0.25 - 0.5):100.

[0055] In one or more embodiments, in step (2), part of the acrylate monomer, part of the grafting agent, part of the water-soluble initiator, part of the emulsifier, and part of the water are gradually added to the reaction system in the form of a second pre-emulsion during the reaction. The masses of the acrylate monomer, grafting agent, water-soluble initiator, and emulsifier in the second pre-emulsion are 60% - 90% of the masses of the acrylate monomer, grafting agent, water-soluble initiator, and emulsifier used in step (2). When a maleimide monomer containing a siloxane group is added to the reaction system in step (2), all or part of the maleimide monomer containing a siloxane group is gradually added to the reaction system in the form of a second pre-emulsion. When a crosslinking agent is added to the reaction system in step (2), part of the crosslinking agent is gradually added to the reaction system in the form of a second pre-emulsion.

[0056] In one or more embodiments, in step (2), the reaction temperature is 75 - 85 °C, and the reaction proceeds until the polymerization conversion rate ≥ 98%.

[0057] In one or more embodiments, in step (3), the mass ratio of the added water to the total mass of the polyacrylate latex dry matter, the vinyl aromatic monomer, and the vinyl nitrile monomer is (150 - 200):100.

[0058] In one or more embodiments, in step (3), the mass ratio of the emulsifier to the total mass of the polyacrylate latex dry matter, the vinyl aromatic monomer, and the vinyl nitrile monomer is (0.5 - 3):100.

[0059] In one or more embodiments, in step (3), the mass ratio of the electrolyte to the total mass of the polyacrylate latex dry matter, the vinyl aromatic monomer, and the vinyl nitrile monomer is (0.3 - 0.45):100.

[0060] In one or more embodiments, in step (3), the mass ratio of the oil-soluble initiator to the total mass of the polyacrylate latex dry matter, the vinyl aromatic monomer, and the vinyl nitrile monomer is (0.25 - 0.5):100.

[0061] In one or more embodiments, in step (3), part of the vinyl aromatic monomer, part of the oil-soluble initiator, part of the emulsifier, and part of the water are gradually added to the reaction system in the form of a third pre-emulsion during the reaction. The masses of the vinyl aromatic monomer, the oil-soluble initiator, and the emulsifier in the third pre-emulsion are 60% - 90% of the masses of the vinyl aromatic monomer, the oil-soluble initiator, and the emulsifier used in step (3), respectively. When the vinyl nitrile monomer is added to the reaction system in step (3), all of the vinyl nitrile monomer is added to the reaction system at the beginning of the reaction, or part or all of the vinyl nitrile monomer is gradually added to the reaction system in the form of a third pre-emulsion during the reaction. When the maleimide monomer containing a siloxane group is added to the reaction system in step (3), all of the maleimide monomer containing a siloxane group is added to the reaction system at the beginning of the reaction, or part or all of the maleimide monomer containing a siloxane group is gradually added to the reaction system in the form of a third pre-emulsion during the reaction.

[0062] In one or more embodiments, in step (3), the reaction temperature is 65 - 75 °C, and the reaction is carried out until the polymerization conversion rate ≥ 98%.

[0063] In one or more embodiments, in the method for preparing the acrylate-styrene-acrylonitrile core-shell graft copolymer or the acrylate-styrene-acrylonitrile core-shell graft copolymer latex of the present invention,

[0064] Step (1) includes: adding an acrylate monomer, a grafting agent, a crosslinking agent, water, an emulsifier, an electrolyte, and a water-soluble initiator to a reactor, heating to 70 - 80 °C and reacting for 20 - 40 min, then maintaining the reaction temperature, adding the first pre-emulsion to the reactor within 3 - 4 h, and reacting at a constant temperature for 1 - 2 h until the polymerization conversion rate ≥ 98%, and then stopping the reaction to obtain a seed latex; wherein the first pre-emulsion includes an acrylate monomer, a grafting agent, a crosslinking agent, a water-soluble initiator, an emulsifier, and water;

[0065] Step (2) includes: adding the seed latex obtained in step (1), acrylate monomers, grafting agents, optionally added crosslinking agents, water, emulsifiers, electrolytes, and water-soluble initiators into a reactor, heating to 75 - 85 °C and reacting for 20 - 40 min, then maintaining the reaction temperature, adding the second pre-emulsion into the reactor within 3 - 4 h, and carrying out a constant-temperature reaction for 1 - 2 h until the polymerization conversion rate ≥ 98%, stopping the reaction to obtain polyacrylate latex, where the second pre-emulsion includes acrylate monomers, grafting agents, optionally added crosslinking agents, optionally added maleimide monomers containing siloxane groups, water-soluble initiators, emulsifiers, and water;

[0066] Step (3) includes: adding the polyacrylate latex obtained in step (2), water, vinyl aromatic monomers, optionally added vinyl cyanide monomers, optionally added maleimide monomers containing siloxane groups, emulsifiers, electrolytes, and oil-soluble initiators into a reactor, heating to 65 - 75 °C and reacting for 20 - 40 min, then maintaining the reaction temperature, adding the third pre-emulsion into the reactor within 3 - 4 h, and carrying out a constant-temperature reaction for 1 - 2 h until the polymerization conversion rate reaches ≥ 98%, stopping the reaction to prepare acrylate-styrene-acrylonitrile core-shell graft copolymer latex, where the third pre-emulsion includes vinyl aromatic monomers, optionally added vinyl cyanide monomers, optionally added maleimide monomers containing siloxane groups, oil-soluble initiators, emulsifiers, and water.

[0067] In one or more embodiments, the method for preparing acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention further includes the following steps:

[0068] (4) Demulsifying, curing, washing, and drying the acrylate-styrene-acrylonitrile core-shell graft copolymer latex obtained in step (3) to obtain acrylate-styrene-acrylonitrile core-shell graft copolymer.

[0069] Another aspect of the present invention provides an acrylate-styrene-acrylonitrile copolymer blend resin, where the acrylate-styrene-acrylonitrile copolymer resin includes the acrylate-styrene-acrylonitrile core-shell graft copolymer described in any embodiment herein and acrylonitrile-styrene copolymer.

[0070] In one or more embodiments, in the acrylate-styrene-acrylonitrile copolymer blend resin, the mass ratio of the acrylate-styrene-acrylonitrile core-shell graft copolymer to the acrylonitrile-styrene copolymer is 30:70 to 45:55.

[0071] In one or more embodiments, the acrylate-styrene-acrylonitrile copolymer blend resin further comprises an antioxidant and / or a lubricant. Based on 100 parts by mass of the total mass of the acrylate-styrene-acrylonitrile core-shell graft copolymer and the acrylonitrile-styrene copolymer, the mass of the antioxidant is 0.2 - 0.5 parts by mass, and the mass of the lubricant is 0.2 - 0.5 parts by mass.

[0072] In one or more embodiments, the acrylate-styrene-acrylonitrile copolymer blend resin is prepared by blending and extruding a raw material composition comprising the acrylate-styrene-acrylonitrile core-shell graft copolymer and the acrylonitrile-styrene copolymer.

[0073] In one or more embodiments, the temperature of the extrusion is 180 - 240 °C.

[0074] The present invention also provides a plastic comprising the acrylate-styrene-acrylonitrile core-shell graft copolymer described in any one of the embodiments herein or the acrylate-styrene-acrylonitrile copolymer blend resin described in any one of the embodiments herein.

[0075] In one or more embodiments, the matrix resin of the plastic is polyvinyl chloride, polyamide, polycarbonate, polyoxymethylene, polyphenylene ether, polyester, polyimide, polyphenylene sulfide, polysulfone, polyether ether ketone, polyarylether ketone, or fluororesin. Detailed Description

[0076] To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art for the present invention. In case of conflict, the definition in this specification shall prevail.

[0077] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall not limit the scope of the present invention in any way, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0078] In this article, "comprising", "including", "containing" and similar terms cover the meanings of "consisting essentially of" and "consisting of". For example, when it is disclosed herein that "A comprises B and C", it should be considered that "A consists essentially of B and C" and "A consists of B and C" have been disclosed herein.

[0079] In this text, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of a numerical range or percentage range should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values (including integers and fractions) within the range.

[0080] In this text, unless otherwise specified, percentages refer to mass percentages, ratios refer to mass ratios, and parts refer to mass parts.

[0081] In this text, when describing embodiments or examples, it should be understood that they are not used to limit the present invention to these embodiments or examples. On the contrary, all alternatives, modifications, and equivalents of the methods and materials described in the present invention can be covered within the scope defined by the claims.

[0082] In this text, for the sake of concise description, not all possible combinations of all technical features in each embodiment or example are described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope described in this specification.

[0083] In the present invention, water is preferably deionized water.

[0084] Existing heat-resistant ASA resins are often prepared by blending and modifying ASA rubber powder, SAN resin, heat-resistant modifiers, and other processing aids. The addition of heat-resistant modifiers will increase the brittleness of the product and the degree of deterioration of the impact resistance. In addition, there are also studies on introducing reactive heat-resistant monomers in the grafting stage, but the relevant monomers contain a relatively rigid structure and do not contain flexible chain segments, and their introduction will also cause a large decrease in the impact resistance of the resin.

[0085] An object of the present invention is to provide a heat-resistant ASA core-shell graft copolymer, a heat-resistant ASA blend resin with excellent comprehensive performance, and a preparation method thereof. The preparation process of the heat-resistant ASA blend resin of the present invention includes: preparation of polyacrylate seed latex, preparation of large-particle-size silicon-containing polyacrylate latex, preparation of graft copolymer latex, preparation of graft copolymer powder, and preparation of heat-resistant ASA blend resin. In the first step, acrylate monomers and grafting agents are selected to prepare small-particle-size polyacrylate seed latex with a particle size of 70-130 nm; in the second step, an appropriate amount of small-particle-size polyacrylate seed latex is selected as the seed, and acrylate monomers, grafting agents, and optionally added maleimide monomers containing siloxane groups are added for emulsion polymerization to prepare large-particle-size silicon-containing polyacrylate latex with a particle size of 150-600 nm; in the third step, based on the presence of large-particle-size silicon-containing polyacrylate latex, vinyl aromatic monomers, optionally added vinyl nitrile monomers, and optionally added maleimide monomers containing siloxane groups are added for grafting reaction to prepare acrylate-styrene-acrylonitrile core-shell graft copolymer latex with a core-shell structure; in the fourth step, the graft copolymer latex is demulsified, coagulated, and dried to obtain graft copolymer powder; finally, the graft copolymer powder is blended with SAN resin to prepare heat-resistant ASA blend resin. In the present invention, the maleimide monomers containing siloxane groups are selected to be added in one or two steps in the second step (preparation of large-particle-size polyacrylate latex) and the third step (grafting reaction). Preferably, the maleimide monomers containing siloxane groups can be added or not added in the second step, and the maleimide monomers containing siloxane groups are added in the third step.

[0086] The maleimide monomers containing siloxane groups used in the present invention are compounds having siloxane groups and N-phenylmaleimide groups. The structure of the siloxane group is -O-Si-O-. The N-phenylmaleimide group may have the following structure In some embodiments, the maleimide monomers containing siloxane groups used in the present invention have one or two N-phenylmaleimide groups. The available maleimide monomers containing siloxane groups include but are not limited to dimethyl(4,4-bismaleimidophenoxy)silane (the structural formula is ), methylphenyl(4,4-bismaleimidophenoxy)silane (the structural formula is

[0087] ), diphenyl(4,4-bismaleimidophenoxy)silane ( ), trimethyl(4-maleimidophenoxy)silane ( ), dimethylphenyl(4-maleimidophenoxy)silane ( ) and the like.

[0088] In some preferred embodiments, the siloxane group-containing maleimide monomer in the core layer of the acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention (i.e., the siloxane group-containing maleimide monomer added in the preparation of the polyacrylate latex in step (2)) has two N-phenylmaleimide groups. The siloxane group-containing maleimide monomers having two N-phenylmaleimide groups that can be used in the present invention include, but are not limited to, dimethyl(4,4-bismaleimidophenoxy)silane, methylphenyl(4,4-bismaleimidophenoxy)silane, diphenyl(4,4-bismaleimidophenoxy)silane, etc.

[0089] In some preferred embodiments, the siloxane group-containing maleimide monomer in the shell layer of the acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention (i.e., the siloxane group-containing maleimide monomer added in the preparation of the core-shell graft copolymer latex in step (3)) has one or two N-phenylmaleimide groups, preferably having one N-phenylmaleimide group. The siloxane group-containing maleimide monomers having one N-phenylmaleimide group that can be used in the present invention include, but are not limited to, trimethyl(4-maleimidophenoxy)silane, dimethylphenyl(4-maleimidophenoxy)silane, etc. In some embodiments, in step (3), before the start of the reaction for preparing the core-shell graft copolymer latex, a siloxane group-containing maleimide monomer is added to the reaction system, preferably a siloxane group-containing maleimide monomer having one or two N-phenylmaleimide groups. In a preferred embodiment, in step (3), after the start of the reaction for preparing the core-shell graft copolymer latex, a siloxane group-containing maleimide monomer is gradually added to the reaction system (for example, gradually added in the form of a third pre-emulsion), preferably a siloxane group-containing maleimide monomer having only one N-phenylmaleimide group.

[0090] The siloxane group-containing maleimide monomers applicable to the present invention can be prepared by known methods. For example, they can be prepared by the methods disclosed in the reference (Designed Monomers and Polymers, 13:1, 33-49).

[0091] The microstructure of the acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention sequentially includes a core part, a core layer, and a shell layer from the center to the periphery. The acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention is characterized in that at least one of its core layer and shell layer includes a structural unit formed by the conversion of a siloxane group-containing maleimide monomer. Herein, conversion means that a reactive molecule is converted into a structural unit of a polymer through a reaction.

[0092] In the acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention, the mass ratio of the core to the core layer can be (0.4 to 10):100, such as 0.5:100, 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100.

[0093] In the acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention, the mass fraction of the shell layer in the acrylate-styrene-acrylonitrile core-shell graft copolymer can be 40% to 60%, such as 45%, 50%, 55%.

[0094] In the core layer of the acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention, the mass ratio of the structural unit formed by the maleimide monomer containing a siloxane group to the structural unit formed by the acrylate monomer can be (0 to 1):100, such as 0.1:100, 0.2:100, 0.3:100, 0.4:100, 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100.

[0095] In the shell layer of the acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention, the mass fraction of the structural unit formed by the maleimide monomer containing a siloxane group in the shell layer can be 0 to 30%, such as 2.5%, 5%, 10%, 15%, 20%, 22.5%, 25%.

[0096] In the core of the acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention, the mass ratio of the structural unit formed by the grafting agent to the structural unit formed by the acrylate monomer can be (0.2 to 3):100, such as 0.5:100, 1:100, 1.5:100, 2:100, 2.5:100.

[0097] In the core of the acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention, the mass ratio of the structural unit formed by the crosslinking agent to the structural unit formed by the acrylate monomer can be (0.2 to 3):100, such as 0.5:100, 1:100, 1.5:100, 2:100, 2.5:100.

[0098] In the core layer of the acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention, the mass ratio of the structural unit formed by the grafting agent to the structural unit formed by the acrylate monomer can be (0.2 to 2):100, such as 0.3:100, 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100, 1:100, 1.2:100, 1.5:100.

[0099] In some embodiments, the core layer of the acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention further comprises structural units converted from a crosslinking agent. In these embodiments, in the core layer of the acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention, the mass ratio of the structural units converted from the crosslinking agent to the structural units converted from the acrylate monomer can be (0-2):100, such as 0.1:100, 0.2:100, 0.3:100, 0.4:100, 0.5:100, 1:100, 1.2:100, 1.5:100. When the core layer comprises structural units converted from a crosslinking agent, in step (2) for preparing the polyacrylate latex, all or part of the crosslinking agent is added to the reaction system at the beginning of the reaction; preferably, when the core layer comprises structural units converted from a maleimide monomer containing a siloxane group, in step (2) for preparing the polyacrylate latex, all of the crosslinking agent is added to the reaction system at the beginning of the reaction; preferably, when the core layer does not comprise structural units converted from a maleimide monomer containing a siloxane group, in step (2) for preparing the polyacrylate latex, part of the crosslinking agent is added to the reaction system at the beginning of the reaction, and the remaining crosslinking agent is gradually added to the reaction system in the form of a second pre-emulsion, and the mass of the crosslinking agent in the second pre-emulsion can be 60%-90% of the mass of the crosslinking agent used in step (2), such as 70%, 80%.

[0100] In some embodiments, the core layer comprises structural units converted from a crosslinking agent, but does not comprise structural units converted from a maleimide monomer containing a siloxane group, and in the core layer, the mass ratio of the structural units converted from the crosslinking agent to the structural units converted from the acrylate monomer is (0.2-2):100, such as 0.3:100, 0.4:100, 0.5:100, 1:100, 1.2:100, 1.5:100.

[0101] In some embodiments, the core layer comprises structural units converted from a maleimide monomer containing a siloxane group, and may or may not comprise structural units converted from a crosslinking agent, and in the core layer, the mass ratio of the structural units converted from the crosslinking agent to the structural units converted from the acrylate monomer is (0-2):100, such as 0.1:100, 0.2:100, 0.3:100, 0.4:100, 0.5:100, 1:100, 1.2:100, 1.5:100. In some preferred embodiments, the core layer comprises structural units converted from a maleimide monomer containing a siloxane group, but does not comprise structural units converted from a crosslinking agent.

[0102] In the shell layer of the acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention, the structural units converted from vinyl aromatic monomers may account for 70% to 80% by mass of the shell layer, such as 75%, and the structural units converted from vinyl nitrile monomers may account for 0% to 30% by mass of the shell layer, such as 2.5%, 5%, 10%, 15%, 20%, 22.5%, 25%.

[0103] In some embodiments, the total mass of the structural units converted from vinyl nitrile monomers and the structural units converted from maleimide monomers containing siloxane groups is 20% to 30% of the total mass of the shell layer, such as 25%. In some embodiments, when preparing the acrylate-styrene-acrylonitrile core-shell graft copolymer latex in step (3), part of the vinyl nitrile monomers and / or part of the maleimide monomers containing siloxane groups are added to the reaction system in the form of a third pre-emulsion during the reaction process, and the total mass of the vinyl nitrile monomers and the maleimide monomers containing siloxane groups added in the form of the third pre-emulsion may account for 60% to 90% of the total mass of the vinyl nitrile monomers and the maleimide monomers containing siloxane groups used in step (3), such as 70%, 80%.

[0104] In the present invention, when preparing the acrylate-styrene-acrylonitrile core-shell graft copolymer latex in step (3), all the vinyl aromatic monomers may be added to the reaction system at the beginning of the reaction, or part of them may be added to the reaction system at the beginning of the reaction and the remaining part may be added to the reaction system in the form of a third pre-emulsion during the reaction process, or all of them may be added to the reaction system in the form of a third pre-emulsion during the reaction process.

[0105] In some embodiments, the core layer of the acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention comprises structural units formed from maleimide monomers containing siloxane groups, and the shell layer also contains structural units formed from maleimide monomers containing siloxane groups. Among them, the mass ratio of the structural units formed from maleimide monomers containing siloxane groups to the structural units formed from acrylate monomers in the core layer is (0.1 - 1):100, such as 0.2:100, 0.3:100, 0.4:100, 0.5:100, 0.6:100, 0.7:100, 0.8:100, 0.9:100, and the mass fraction of the structural units formed from maleimide monomers containing siloxane groups in the shell layer is 2.5% - 30%, such as 5%, 10%, 15%, 20%, 25%. In these embodiments, when preparing the polyacrylate latex in step (2), part or all, preferably all, of the maleimide monomers containing siloxane groups are added to the reaction system in the form of a second pre-emulsion during the reaction process, and preferably the second pre-emulsion does not contain a cross-linking agent; when preparing the acrylate-styrene-acrylonitrile core-shell graft copolymer latex in step (3), part or all, preferably all, of the maleimide monomers containing siloxane groups are added to the reaction system in the form of a third pre-emulsion during the reaction process.

[0106] In some embodiments, the core layer of the acrylate-styrene-acrylonitrile core-shell graft copolymer of the present invention does not include structural units converted from maleimide monomers containing siloxane groups, but the shell layer contains structural units converted from maleimide monomers containing siloxane groups. Among them, the mass fraction of the structural units converted from maleimide monomers containing siloxane groups in the shell layer is 2.5% to 30% of the shell layer, such as 5%, 10%, 15%, 20%, 25%. In these embodiments, the core layer may include structural units converted from a crosslinking agent. When preparing the polyacrylate latex in step (2), part of the crosslinking agent is added to the reaction system in the form of a second pre-emulsion during the reaction. The mass of the crosslinking agent in the second pre-emulsion is preferably 60% to 90% of the mass of the crosslinking agent used in step (2). In these embodiments, a maleimide monomer containing siloxane groups, preferably a maleimide monomer containing siloxane groups having one or two N-phenylmaleimide groups, can be added to the reaction system before the start of the reaction for preparing the core-shell graft copolymer latex in step (3). It is also possible to gradually add a maleimide monomer containing siloxane groups, preferably a maleimide monomer containing siloxane groups having only one N-phenylmaleimide group, to the reaction system in the form of a third pre-emulsion during the reaction for preparing the core-shell graft copolymer latex in step (3). In these embodiments, all of the maleimide monomers containing siloxane groups can be added to the reaction system before the start of the reaction for preparing the core-shell graft copolymer latex in step (3). At the same time, before the start of the reaction, the vinyl cyanide monomer can be not added to the reaction system first, and all of the vinyl cyanide monomer is gradually added in the form of a third pre-emulsion during the reaction. In these embodiments, all or part of the vinyl cyanide monomer can be added to the reaction system before the start of the reaction, and all of the maleimide monomers containing siloxane groups and the remaining vinyl cyanide monomer that may exist are added in the form of a third pre-emulsion during the reaction.

[0107] In the present invention, the acrylate monomers in the core and the acrylate monomers in the core layer may be the same or different. In some preferred embodiments, the acrylate monomers in the core and the acrylate monomers in the core layer are the same.

[0108] In the present invention, the grafting agents in the core and the grafting agents in the core layer may be the same or different. In some preferred embodiments, the grafting agents in the core and the grafting agents in the core layer are the same.

[0109] In the present invention, when the core layer contains a crosslinking agent, the crosslinking agents in the core and the core layer may be the same or different. In some preferred embodiments, the crosslinking agents in the core and the core layer are the same.

[0110] In the present invention, an acrylate-styrene-acrylonitrile core-shell graft copolymer latex can be first prepared, and then the acrylate-styrene-acrylonitrile core-shell graft copolymer latex is demulsified, cured, washed, and dried to obtain an acrylate-styrene-acrylonitrile core-shell graft copolymer.

[0111] The acrylate-styrene-acrylonitrile core-shell graft copolymer latex of the present invention can be prepared by a method comprising the following steps:

[0112] (1) In the presence of water, an emulsifier, an electrolyte, and a water-soluble initiator, an acrylate monomer, a grafting agent, and a crosslinking agent are reacted to form a core to obtain a seed latex;

[0113] (2) In the presence of water, an emulsifier, an electrolyte, and a water-soluble initiator, the seed latex obtained in step (1), an acrylate monomer, a grafting agent, an optionally present crosslinking agent, and an optionally present maleimide monomer containing a siloxane group are reacted to form a core layer on the surface of the core to obtain a polyacrylate latex;

[0114] (3) In the presence of water, an emulsifier, an electrolyte, and an oil-soluble initiator, the polyacrylate latex obtained in step (2), a vinyl aromatic monomer, an optionally present vinyl nitrile monomer, and an optionally present maleimide monomer containing a siloxane group are reacted to form a shell layer on the surface of the core layer to obtain an acrylate-styrene-acrylonitrile core-shell graft copolymer latex;

[0115] Wherein, a maleimide monomer containing a siloxane group is added to the reaction system of at least one of step (2) and step (3).

[0116] In some preferred embodiments, a maleimide monomer containing a siloxane group is added or not added to the reaction system of step (2), and a maleimide monomer containing a siloxane group is added to the reaction system of step (3).

[0117] The emulsifiers used in step (1), step (2), and step (3) can be the same or different. In some embodiments, the emulsifiers used in step (1), step (2), and step (3) are the same. The water-soluble initiators used in step (1) and step (2) can be the same or different. In some embodiments, the water-soluble initiators used in step (1) and step (2) are the same.

[0118] In step (1), the mass ratio of water to the acrylate monomer can be (150-200):100, such as 160:100, 170:100, 180:100, 190:100.

[0119] In step (1), the mass ratio of the emulsifier to the acrylate monomer can be (0.5 - 3):100, such as 1:100, 1.5:100, 2:100, 2.5:100.

[0120] In step (1), the mass ratio of the electrolyte to the acrylate monomer can be (0.3 - 0.45):100, such as 0.35:100, 0.4:100.

[0121] In step (1), the mass ratio of the water-soluble initiator to the acrylate monomer can be (0.25 - 0.5):100, such as 0.3:100, 0.4:100.

[0122] In some preferred embodiments, in step (1), part of the acrylate monomer, part of the grafting agent, part of the crosslinking agent, part of the water-soluble initiator, part of the emulsifier and part of the water are gradually added to the reaction system in the form of a first pre-emulsion during the reaction, and the remaining raw materials are added to the reaction system before the start of the reaction. The mass of the acrylate monomer, grafting agent, crosslinking agent, water-soluble initiator and emulsifier in the first pre-emulsion is independently preferably 60% - 90% of the mass of the acrylate monomer, grafting agent, crosslinking agent, water-soluble initiator and emulsifier used in step (1), such as 65%, 70%, 75%, 80%, 85%. The mass of water in the first pre-emulsion can be 20% - 40% of the mass of water used in step (1), such as 25%, 30%, 35%. The first pre-emulsion is preferably added to the reaction system slowly (e.g., over 3 - 4 h).

[0123] In step (1), the reaction temperature can be 70 - 80°C, such as 75°C. Step (1) is preferably reacted until the polymerization conversion rate ≥ 98%.

[0124] In step (2), the mass ratio of the added water to the added acrylate monomer can be (150 - 200):100, such as 160:100, 170:100, 180:100, 190:100.

[0125] In step (2), the mass ratio of the added emulsifier to the added acrylate monomer can be (0.5 - 3):100, such as 1:100, 1.5:100, 2:100, 2.5:100.

[0126] In step (2), the mass ratio of the added electrolyte to the added acrylate monomer can be (0.3 - 0.45):100, such as 0.35:100, 0.4:100.

[0127] In step (2), the mass ratio of the water-soluble initiator added to the acrylate monomer added may be (0.25 - 0.5):100, such as 0.3:100, 0.4:100.

[0128] In some preferred embodiments, in step (2), part of the acrylate monomer, part of the grafting agent, part of the water-soluble initiator, part of the emulsifier, and part of the water are gradually added to the reaction system in the form of a second pre-emulsion during the reaction, and the remaining raw materials are added to the reaction system before the start of the reaction. The mass of the acrylate monomer, grafting agent, water-soluble initiator, and emulsifier in the second pre-emulsion is independently preferably 60% - 90% of the mass of the acrylate monomer, grafting agent, water-soluble initiator, and emulsifier used in step (2), such as 65%, 70%, 75%, 80%, 85%. When a maleimide monomer containing a siloxane group is added to the reaction system in step (2), all or part of the maleimide monomer containing a siloxane group is gradually added to the reaction system in the form of a second pre-emulsion. When a crosslinking agent is added to the reaction system in step (2), part of the crosslinking agent is gradually added to the reaction system in the form of a second pre-emulsion. The mass of the crosslinking agent in the second pre-emulsion is preferably 60% - 90% of the mass of the crosslinking agent used in step (2), such as 65%, 70%, 75%, 80%, 85%. The mass of water in the second pre-emulsion may be 20% - 40% of the mass of water added in step (2), such as 25%, 30%, 35%. The second pre-emulsion is preferably added to the reaction system slowly (e.g., over 3 - 4 h).

[0129] In step (2), the reaction temperature is preferably 75 - 85°C, such as 80°C. Step (2) is preferably reacted until the polymerization conversion rate ≥ 98%.

[0130] In step (3), the mass ratio of the water added to the total mass of the dry matter of the silicone-containing polyacrylate latex, vinyl aromatic monomer, and vinyl nitrile monomer added may be (150 - 200):100, such as 160:100, 170:100, 180:100, 190:100.

[0131] In step (3), the mass ratio of the emulsifier added to the total mass of the dry matter of the silicone-containing polyacrylate latex, vinyl aromatic monomer, and vinyl nitrile monomer added may be (0.5 - 3):100, such as 1:100, 1.5:100, 2:100, 2.5:100.

[0132] In step (3), the mass ratio of the electrolyte added to the total mass of the dry matter of the silicone-containing polyacrylate latex, vinyl aromatic monomer, and vinyl nitrile monomer added may be (0.3 - 0.45):100, such as 0.35:100, 0.4:100.

[0133] In step (3), the mass ratio of the oil-soluble initiator added to the total mass of the dry matter of the silicon-containing polyacrylate latex, the vinyl aromatic monomer, and the vinyl nitrile monomer added can be (0.25 - 0.5):100, such as 0.35:100, 0.4:100.

[0134] In some preferred embodiments, in step (3), part of the vinyl aromatic monomer, part of the oil-soluble initiator, part of the emulsifier, and part of the water are gradually added to the reaction system in the form of a third pre-emulsion during the reaction, and the remaining raw materials are added to the reaction system before the start of the reaction. The mass of the vinyl aromatic monomer, the oil-soluble initiator, and the emulsifier in the third pre-emulsion are each independently preferably 60% - 90% of the mass of the vinyl aromatic monomer, the oil-soluble initiator, and the emulsifier used in step (3), such as 65%, 70%, 75%, 80%, 85%. The mass of water in the third pre-emulsion can be 20% - 40% of the mass of water added in step (3), such as 25%, 30%, 35%. When a vinyl nitrile monomer is added to the reaction system in step (3), all of the vinyl nitrile monomer is added to the reaction system at the start of the reaction, or part or all of the vinyl nitrile monomer is gradually added to the reaction system in the form of a third pre-emulsion during the reaction. When a maleimide monomer containing a siloxane group is added to the reaction system in step (3), all of the maleimide monomer containing a siloxane group is added to the reaction system at the start of the reaction, or part or all of the maleimide monomer containing a siloxane group is gradually added to the reaction system in the form of a third pre-emulsion during the reaction. The third pre-emulsion is preferably added to the reaction system slowly (e.g., over 3 - 4 h).

[0135] In step (3), the reaction temperature is preferably 65 - 75 °C, such as 70 °C. Step (3) is preferably reacted until the polymerization conversion rate ≥ 98%.

[0136] The acrylate-styrene-acrylonitrile core-shell graft copolymer latex obtained is subjected to demulsification, curing, washing, and drying to obtain an acrylate-styrene-acrylonitrile core-shell graft copolymer. The acrylate-styrene-acrylonitrile core-shell graft copolymer is usually in powder form and is also called acrylate-styrene-acrylonitrile core-shell graft copolymer powder.

[0137] The methods of demulsification, aging, washing and drying can be conventional. For example, a salt aqueous solution (e.g., a magnesium sulfate aqueous solution with a concentration of 5wt%) can be added to the acrylate-styrene-acrylonitrile core-shell graft copolymer latex at 75°C to 85°C (e.g., 80°C) for demulsification, and the mass ratio of the salt aqueous solution to the latex can be 3:1 to 1:3, for example, 2:5. After demulsification, the temperature is increased for aging, the aging temperature can be 90 to 100°C, for example, 95°C, and the aging time can be 15min to 60min, for example, 30min. After aging, washing, centrifugal dehydration and drying can be performed to obtain acrylate-styrene-acrylonitrile core-shell graft copolymer rubber powder.

[0138] The acrylate-styrene-acrylonitrile graft copolymer of the present invention is co-extruded with an acrylonitrile-styrene copolymer to obtain an acrylate-propylene-acrylonitrile copolymer blended resin. In the blended resin, the mass ratio of the acrylate-styrene-acrylonitrile core-shell graft copolymer to the mass ratio of the acrylonitrile-styrene copolymer can be 30:70 to 45:55, for example, 35:65, 40:60. An appropriate amount of auxiliary agent, such as an antioxidant and / or a lubricant, can be added to the blended resin as needed. The amount of each antioxidant and lubricant is usually no more than 0.5% of the total mass of the acrylate-styrene-acrylonitrile graft copolymer and the acrylonitrile-styrene copolymer, for example, 0.1%, 0.2%, 0.3%, 0.4%. The extrusion temperature can be 180 to 240°C.

[0139] In some embodiments, the method for preparing the acrylate-styrene-acrylonitrile copolymer blend resin of the present invention comprises the following steps:

[0140] (1) Preparation of small-particle polyacrylate seed latex

[0141] After nitrogen replacement, add 15-25 parts (e.g. 20 parts) of acrylic acid ester monomer, 0.1-1 parts (e.g. 0.5-1 parts) of grafting agent, 0.1-1 parts (e.g. 0.5-1 parts) of crosslinking agent, 100-150 parts of water, 0.25-1 parts (e.g. 0.5-1 parts) of emulsifier, 0.3-0.45 parts of electrolyte and 0.05-0.1 parts of water-soluble initiator to the reactor, heat to 70-80°C and react for 20-40 minutes (e.g. 30 minutes). Then, keep the reaction temperature, add the first pre-emulsion to the reactor within 3-4 hours by using a peristaltic pump, and after adding, keep the temperature for 1-2 hours until the polymerization conversion rate is ≥98%, then cool to room temperature to stop the reaction, and prepare a polyacrylate seed latex with a particle size of 70-130 nm. The first pre-emulsion comprises 75-85 parts (e.g. 80 parts) of acrylate monomer, 0.1-2 parts (e.g. 1-2 parts) of grafting agent, 0.1-2 parts (e.g. 1-2 parts) of crosslinking agent, 0.2-0.4 parts of water-soluble initiator, 0.25-2 parts (e.g. 1.5-2) parts of emulsifier and 40-60 parts (e.g. 50 parts) of water. The total amount of acrylate monomer used in step (1) is 100 parts.

[0142] (2) Preparation of large particle size polyacrylate latex

[0143] After nitrogen substitution, 0.5-10 parts (calculated by dry weight) of the polyacrylate seed latex prepared in step (1), 15-25 parts (e.g. 20 parts) of acrylate monomer, 0-1 part (e.g. 0.1-1 part, 0.2-1 part, 0.5-1 part) of maleimide monomer containing siloxy group, 0.1-1 part (0.2-0.4 part) of grafting agent, 0-0.4 part (e.g. 0.2-0.4 part) of crosslinking agent, 100-150 parts of water, 0.25-1 part (e.g. 0.5-1 part) of emulsifier, 0.3-0.45 part of electrolyte and 0.05-0.1 part of water-soluble initiator are added to the reactor, and the temperature is raised to 75-85° C. for reaction for 20-40 min (e.g. 30 min). Then, the reaction temperature is maintained, and the second pre-emulsion is added to the reactor within 3 to 4 hours by a peristaltic pump. After addition, the reaction is carried out at a constant temperature for 1 to 2 hours until the polymerization conversion rate is ≥ 98%, and then the reaction is stopped at room temperature to prepare a large-particle polyacrylate latex with a particle size of 150 to 600 nm. The second pre-emulsion includes 75 to 85 parts (e.g., 80 parts) of acrylate monomer, 0.1 to 1 part (e.g., 0.3 to 0.6 parts) of grafting agent, 0 to 0.6 parts (e.g., 0.3 to 0.6 parts) of crosslinking agent, 0 to 1 part (e.g., 0.1 to 1 part, 0.2 to 1 part, 0.5 to 1 part) of maleimide monomer containing siloxane group, 0.2 to 0.4 parts of water-soluble initiator, 0.25 to 2 parts (e.g., 1.5 to 2 parts) of emulsifier and 40 to 60 parts (e.g., 50 parts) of water. The total amount of acrylate monomer used in step (2) is 100 parts.

[0144] (3) Preparation of acrylate-styrene-acrylonitrile core-shell graft copolymer latex

[0145] After nitrogen replacement, the reactor is charged with 40-60 parts (calculated by dry weight) of the large-particle polyacrylate latex prepared in step (2), 100-150 parts of water, 6-9 parts of vinyl aromatic monomer, 0-3 parts of vinyl nitrile monomer (e.g., 2-3 parts), 0-6 parts of maleimide monomer containing siloxy groups (e.g., 0-3 parts, 2-3 parts), 0.25-1 part of emulsifier (e.g., 0.5-1 part), 0.3-0.45 parts of electrolyte and 0.05-0.1 parts of oil-soluble initiator, and the temperature is raised to 65-75° C. for reaction for 30 minutes. Then, the reaction temperature is maintained, and the third pre-emulsion is added to the reactor within 3-4 hours by a peristaltic pump, and the reaction is carried out at a constant temperature for 1-2 hours until the polymerization conversion rate is ≥98%, and the reaction is stopped when the temperature is lowered to room temperature, thereby preparing an acrylate-styrene-acrylonitrile core-shell graft copolymer. The third pre-emulsion comprises 24-36 parts of vinyl aromatic monomer, 0-12 parts of vinyl nitrile monomer (e.g., 0-10 parts, 0-8 parts), 0-24 parts of maleimide monomer containing siloxane group (e.g., 0-12 parts, 0-10 parts, 0-8 parts, 1-10 parts, 1-8 parts), 0.2-0.4 parts of oil-soluble initiator, 0.25-2 parts of emulsifier (e.g., 1.5-2 parts) and 40-60 parts of water (e.g., 50 parts). The total mass of large particle size polyacrylate latex dry matter, vinyl aromatic monomer, vinyl nitrile monomer and maleimide monomer containing siloxane group used in step (3) is 100 parts.

[0146] (4) Preparation of acrylate-styrene-acrylonitrile core-shell graft copolymer powder

[0147] The salt aqueous solution is added to the acrylate-styrene-acrylonitrile core-shell graft copolymer latex prepared in step (3) at 75-85°C (80°C) to demulsify, and the temperature is raised to 90-100°C (95°C) for aging. After washing, centrifugal dehydration and drying, the acrylate-styrene-acrylonitrile core-shell graft copolymer powder is obtained.

[0148] (5) Preparation of acrylate-styrene-acrylonitrile copolymer blend resin

[0149] Take 30-45 parts of the acrylate-styrene-acrylonitrile core-shell graft copolymer rubber powder prepared in step (4), 55-70 parts of SAN resin, 0-0.5 parts (e.g. 0.2-0.5 parts) of antioxidant and 0-0.5 parts (e.g. 0.2-0.5 parts) of lubricant, blend them, and then granulate them at 180-240° C. using a twin-screw extruder to obtain acrylate-styrene-acrylonitrile copolymer blended resin particles. The total amount of acrylate-styrene-acrylonitrile core-shell graft copolymer rubber powder and SAN resin used in step (5) is 100 parts. After drying, test specimens are prepared by injection molding machine.

[0150] The acrylate-styrene-acrylonitrile core-shell graft copolymer and the acrylate-styrene-acrylonitrile copolymer blended resin of the present invention can be added to plastics as a modifier, such as a toughening agent. In the present invention, the base resin of the plastic includes but is not limited to polyvinyl chloride, polyamide, polycarbonate, polyoxymethylene, polyphenylene ether, polyester, polyimide, polyphenylene sulfide, polysulfone, polyetheretherketone, polyaryletherketone, fluororesin, etc. Polyamide can be polyethylene terephthalate, nylon, etc. In the present invention, the base resin of the plastic refers to the resin component that accounts for the main mass of the plastic. For example, the mass of the base resin can be more than 50%, more than 60%, more than 70%, more than 80% or more than 90% of the mass of the plastic.

[0151] The present invention achieves the following beneficial technical effects:

[0152] 1. The present invention innovatively introduces maleimide monomers containing siloxy groups when preparing large-particle polyacrylate latex or graft copolymer latex. Maleimide monomers containing siloxy groups contain highly rigid cyclic groups and highly flexible siloxane groups. By introducing them, the heat resistance of ASA can be improved without causing too much decrease in the impact resistance of ASA resin, achieving a good balance in terms of heat resistance and impact resistance, and having good processability and flexural modulus, meeting the needs of downstream applications.

[0153] 2. In some embodiments of the present invention, the maleimide monomer containing siloxy groups and having two N-phenylmaleimide groups introduced in the preparation of large-particle polyacrylate latex can act as a crosslinking agent in the polymerization process of acrylate.

[0154] The present invention will be described below in the form of specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present invention. The methods, reagents and materials used in the examples are, unless otherwise stated, conventional methods, reagents and materials in the art. The raw material compounds in the examples can all be purchased from commercial sources. The number of feeds in the examples and comparative examples is by mass fraction.

[0155] The dimethyl (4,4-bismaleimide phenoxy) silane used in the examples and comparative examples was prepared by the method disclosed in the reference (Designed Monomers and Polymers, 13: 1, 33-49), and the specific method is as follows. Other maleimide monomers containing siloxy groups can be prepared by similar methods:

[0156] 0.025 mol N-(4-hydroxyphenyl)maleimide, 3 mL triethylamine and 0.012 g Cu 2 Cl 2 (Put in 100mL tetrahydrofuran) Add to a three-necked flask, purge with nitrogen and keep in an ice bath. Add dichlorodimethylsilane solution (0.01mol dichlorodimethylsilane + 50mL tetrahydrofuran) gradually to the above mixture within 2h. Then keep the mixture at 40°C for 12 hours. The resulting mixture is filtered to remove the precipitate of amine hydrochloride, and then the tetrahydrofuran solvent is removed by distillation to obtain the product, which is dissolved in 100mL ethyl acetate again and extracted with 1wt% NaOH solution to obtain an organic layer. After the organic solution is dried over anhydrous magnesium sulfate, it is distilled under reduced pressure to obtain a precipitate, which is recrystallized multiple times with n-hexane and then dried in a vacuum to obtain dimethyl (4,4-bismaleimide phenoxy) silane.

[0157] The styrene-maleimide copolymer (SMI resin) used in Comparative Example 2 was purchased from Nippon Electric Chemical Co., Ltd. with the brand name MS-NB.

[0158] The test methods involved in the embodiments and comparative examples are as follows:

[0159] (1) Vicat softening point: tested in accordance with ISO 306 standard, test conditions are 50N, 50℃ / h.

[0160] (2) Notched impact strength at room temperature and low temperature: The test is conducted in accordance with the standard of GB / T 1843-2008 “Determination of cantilever beam impact strength” and the unit is kilojoule per square meter (kJ / m 2 ) indicates. When testing the low-temperature impact strength, the notched cantilever beam impact strength is measured after the specimen is kept at -30°C for 48 hours.

[0161] (3) Melt flow index: The melt flow index of the prepared pellets was measured according to GB / T 3682.1-2018 at 220°C and 10 kg. The unit of the melt flow index is g / 10 min.

[0162] (4) Flexural modulus: tested in accordance with GB-T 9341-2008 standard, with a bending speed of 2 mm / min.

[0163] Example 1

[0164] (1) Preparation of small-particle polyacrylate seed latex

[0165] After nitrogen replacement, add 20 parts of n-butyl acrylate, 0.5 parts of allyl methacrylate, 0.5 parts of ethylene glycol dimethacrylate, 100 parts of deionized water, 1 part of sodium dodecyl sulfate, 0.35 parts of sodium bicarbonate and 0.05 parts of potassium persulfate to the reactor, and heat to 80°C for 30 minutes. Keep the reaction temperature, use a peristaltic pump to add the first pre-emulsion to the reactor within 4 hours, and react at a constant temperature for 2 hours after the addition is completed. The polymerization conversion rate reaches 98%, and the reaction is stopped at room temperature to prepare a small-particle polyacrylate seed latex. The first pre-emulsion includes 80 parts of n-butyl acrylate, 1.5 parts of allyl methacrylate, 1.5 parts of ethylene glycol dimethacrylate, 0.2 parts of potassium persulfate, 2 parts of sodium dodecyl sulfate and 50 parts of deionized water.

[0166] (2) Preparation of large particle size polyacrylate latex

[0167] After nitrogen substitution, the reactor is charged with 2 parts of the seed latex prepared in step (1) (by mass based on dry weight), 20 parts of n-butyl acrylate, 0.2 parts of allyl methacrylate, 0.2 parts of ethylene glycol dimethacrylate, 100 parts of deionized water, 0.5 parts of sodium dodecyl sulfate, 0.35 parts of sodium bicarbonate and 0.05 parts of potassium persulfate, and the temperature is raised to 80°C for reaction for 30 minutes. The reaction temperature is maintained, and the second pre-emulsion is added to the reactor within 4 hours by a peristaltic pump. After the addition is completed, the reaction is carried out at a constant temperature for 2 hours, and the polymerization conversion rate reaches 98%. The reaction is stopped by cooling to room temperature to prepare a large-particle polyacrylate latex. The second pre-emulsion includes 80 parts of n-butyl acrylate, 0.3 parts of allyl methacrylate, 0.3 parts of ethylene glycol dimethacrylate, 0 parts of dimethyl (4,4-bismaleimide phenoxy) silane, 0.2 parts of potassium persulfate, 2 parts of sodium dodecyl sulfate and 50 parts of deionized water.

[0168] (3) Preparation of acrylate-styrene-acrylonitrile core-shell graft copolymer latex

[0169] After nitrogen substitution, the reactor was charged with 60 parts (by mass based on dry weight) of the large-particle polyacrylate latex prepared in step (2), 100 parts of deionized water, 6 parts of styrene, 2 parts of acrylonitrile, 0.5 parts of sodium dodecyl sulfate, 0.35 parts of sodium bicarbonate and 0.05 parts of cumene hydroperoxide, and the temperature was raised to 70°C for reaction for 30 minutes. The reaction temperature was maintained, and the third pre-emulsion was added to the reactor within 4 hours using a peristaltic pump. After the addition was completed, the reaction was carried out at a constant temperature for 2 hours, and the polymerization conversion rate reached 98%. The reaction was stopped by cooling to room temperature to prepare an acrylate-styrene-acrylonitrile core-shell graft copolymer latex. The third pre-emulsion included 24 parts of styrene, 6 parts of acrylonitrile, 2 parts of dimethylphenyl (4-maleimide phenoxy) silane, 0.2 parts of cumene hydroperoxide, 2 parts of sodium dodecyl sulfate and 50 parts of deionized water.

[0170] (4) Preparation of acrylate-styrene-acrylonitrile core-shell graft copolymer powder

[0171] 100 parts of the acrylate-styrene-acrylonitrile core-shell graft copolymer latex prepared in step (3) and 100 parts of deionized water are added to a reactor and heated to 80° C., then 40 parts of a 5 wt % magnesium sulfate aqueous solution are added for demulsification, the temperature is raised to 95° C. and matured for 30 min. After washing, centrifugal dehydration and drying, acrylate-styrene-acrylonitrile core-shell graft copolymer powder (i.e., silicon-containing ASA powder) is obtained.

[0172] (5) Preparation of acrylate-styrene-acrylonitrile copolymer blend resin

[0173] 30 parts of the silicon-containing ASA rubber powder prepared in step (4), 70 parts of SAN resin (Taiwan Chemical Industry NF2200), 0.2 parts of antioxidant 1010 and 0.4 parts of lubricant ethylene bis stearamide were blended, and then granulated by a twin-screw extruder at 180-240° C. to obtain acrylate-styrene-acrylonitrile copolymer blended resin (i.e., silicon-containing ASA blended resin) particles. After drying, test specimens were prepared by injection molding machine.

[0174] Example 2

[0175] The difference between Example 2 and Example 1 is that the third pre-emulsion in step (3) includes 24 parts of styrene, 0 parts of acrylonitrile, 8 parts of dimethylphenyl (4-maleimidophenoxy) silane, 0.2 parts of cumene hydroperoxide, 2 parts of sodium dodecyl sulfate and 10 parts of deionized water. The rest is prepared according to the same steps as Example 1.

[0176] Example 3

[0177] The difference between Example 3 and Example 1 is that: in step (2), the second pre-emulsion includes 80 parts of n-butyl acrylate, 0.3 parts of allyl methacrylate, 1 part of dimethyl (4,4-bismaleimide phenoxy) silane, 0.2 parts of potassium persulfate, 2 parts of sodium dodecyl sulfate and 50 parts of deionized water; in step (3), the third pre-emulsion includes 24 parts of styrene, 7 parts of acrylonitrile, 1 part of dimethylphenyl (4-maleimide phenoxy) silane, 0.2 parts of isopropylbenzene hydroperoxide, 2 parts of sodium dodecyl sulfate and 10 parts of deionized water. The rest is prepared according to the same steps as in Example 1.

[0178] Example 4

[0179] The difference between Example 4 and Example 1 is that: in step (2), the second pre-emulsion includes 80 parts of n-butyl acrylate, 0.3 parts of allyl methacrylate, 1 part of dimethyl (4,4-bismaleimide phenoxy) silane, 0.2 parts of potassium persulfate, 2 parts of sodium dodecyl sulfate and 50 parts of deionized water; in step (3), the third pre-emulsion includes 24 parts of styrene, 0 parts of acrylonitrile, 8 parts of dimethylphenyl (4-maleimide phenoxy) silane, 0.2 parts of isopropylbenzene hydroperoxide, 2 parts of sodium dodecyl sulfate and 10 parts of deionized water. The rest is prepared according to the same steps as in Example 1.

[0180] Example 5

[0181] The step (3) of Example 5 is:

[0182] (3) Preparation of acrylate-styrene-acrylonitrile core-shell graft copolymer latex

[0183] After nitrogen substitution, the reactor was charged with 60 parts (by mass based on dry matter) of the large-particle polyacrylate latex prepared in step (2), 150 parts of deionized water, 6 parts of styrene, 2 parts of dimethyl (4,4-bismaleimide phenoxy) silane, 0.5 parts of sodium dodecyl sulfate, 0.35 parts of sodium bicarbonate and 0.05 parts of cumene hydroperoxide, and the temperature was raised to 70°C for reaction for 30 minutes. The reaction temperature was maintained, and the third pre-emulsion was added to the reactor within 4 hours using a peristaltic pump. After the addition was completed, the reaction was carried out at a constant temperature for 2 hours, and the polymerization conversion rate reached 98%. The reaction was stopped by cooling to room temperature to prepare an acrylate-styrene-acrylonitrile core-shell graft copolymer latex. The third pre-emulsion included 24 parts of styrene, 8 parts of acrylonitrile, 0.2 parts of cumene hydroperoxide, 2 parts of sodium dodecyl sulfate and 10 parts of deionized water.

[0184] The remaining steps were prepared in the same manner as in Example 1.

[0185] Comparative Example 1

[0186] The difference between Comparative Example 1 and Example 1 lies in that: in step (3), the third pre-emulsion includes 24 parts of styrene, 8 parts of acrylonitrile, 0 part of dimethylphenyl(4-maleimidophenoxy)silane, 0.2 part of cumene hydroperoxide, 2 parts of sodium dodecyl sulfate and 10 parts of deionized water. The rest is prepared according to the same steps as in Example 1.

[0187] Comparative Example 2

[0188] Step (5) of Comparative Example 2 is as follows:

[0189] (5) Preparation of acrylate-styrene-acrylonitrile copolymer blend resin

[0190] Take 30 parts of the ASA rubber powder prepared in step (4), 70 parts of SAN resin (Taiwan Chemical Fiber NF2200), 0.2 part of antioxidant 1010, 0.4 part of lubricant ethylene bis-stearamide and 8 parts of heat-resistant modifier styrene-maleimide copolymer (SMI resin) and blend them. Then, granulate them with a twin-screw extruder at 180 - 240 °C to obtain acrylate-styrene-acrylonitrile copolymer blend resin (ASA blend resin) particles. After drying, test specimens are prepared by an injection molding machine.

[0191] The rest of the steps are prepared according to the same steps as in Comparative Example 1.

[0192] Comparative Example 3

[0193] The difference between Comparative Example 3 and Example 1 lies in that: in step (3), the third pre-emulsion includes 18 parts of styrene, 0 part of acrylonitrile, 14 parts of dimethylphenyl(4-maleimidophenoxy)silane, 0.2 part of cumene hydroperoxide, 2 parts of sodium dodecyl sulfate and 10 parts of deionized water. The rest is prepared according to the same steps as in Example 1.

[0194] Comparative Example 4

[0195] The difference between Comparative Example 4 and Example 1 lies in that: in step (2), the second pre-emulsion includes 80 parts of n-butyl acrylate, 0.3 part of allyl methacrylate, 2 parts of dimethyl(4,4-bismaleimidophenoxy)silane, 0.2 part of potassium persulfate, 2 parts of sodium dodecyl sulfate and 50 parts of deionized water. The rest is prepared according to the same steps as in Example 1.

[0196] The relevant data of the latex formulations and resin properties of Examples 1 - 5 and Comparative Examples 1 - 4 are shown in Table 1.

[0197] Table 1: Latex formulation and resin property data

[0198]

[0199]

[0200] As shown in Table 1, in Examples 1-5, an appropriate amount of maleimide monomers containing siloxy groups were introduced during the preparation of large-particle polyacrylate latex and / or graft copolymer latex, and the prepared ASA blended resins had good heat resistance and less impact resistance loss.

[0201] If the amount of maleimide monomers containing siloxy groups exceeds the specified range, the melt index and impact strength of the ASA resin obtained will decrease significantly. In comparative example 3, an excessive amount of maleimide monomers containing siloxy groups was added during the preparation of the graft copolymer latex. Although the heat resistance of the ASA blended resin obtained was improved, the anti-impact performance was greatly lost. In comparative example 4, an excessive amount of maleimide monomers containing siloxy groups was added during the preparation of the large-particle polyacrylate latex. Although the heat resistance of the ASA blended resin obtained was slightly improved, compared with Examples 1 and 5 with the same heat resistance, the anti-impact performance of comparative example 4 was greatly lost.

[0202] In Comparative Example 2, the heat-resistant modifier SMI was added in the blending step to improve the heat resistance of the ASA blended resin. The results showed that the toughness of the ASA blended resin was greatly lost.

Claims

1. An acrylate-styrene-acrylonitrile core-shell graft copolymer, characterized in that, the microstructure of the acrylate-styrene-acrylonitrile core-shell graft copolymer sequentially includes a core part, a core layer and a shell layer from the center to the periphery; wherein, the core part includes structural units converted from acrylate monomers, structural units converted from grafting agents and structural units converted from crosslinking agents; the core layer includes structural units converted from acrylate monomers and structural units converted from grafting agents, and the core layer optionally further includes structural units converted from maleimide monomers containing siloxane groups; the shell layer includes structural units converted from vinyl aromatic monomers, and the shell layer optionally further includes one or more selected from structural units converted from maleimide monomers containing siloxane groups and structural units converted from vinyl nitrile monomers; the mass ratio of the core part to the core layer is (0.4 - 10):100; the mass fraction of the shell layer in the acrylate-styrene-acrylonitrile core-shell graft copolymer is 40% - 60%; the mass ratio of the structural units converted from maleimide monomers containing siloxane groups to the structural units converted from acrylate monomers in the core layer is (0 - 1):100; the mass fraction of the structural units converted from maleimide monomers containing siloxane groups in the shell layer in the shell layer is 0 - 30%; at least one of the core layer and the shell layer includes structural units converted from maleimide monomers containing siloxane groups.

2. The acrylate-styrene-acrylonitrile core-shell graft copolymer according to claim 1, characterized in that, the maleimide monomers containing siloxane groups are compounds having siloxane groups and N-phenylmaleimide groups, preferably compounds having siloxane groups and one or two N-phenylmaleimide groups; preferably, the maleimide monomers containing siloxane groups are selected from one or more of dimethyl(4,4-bismaleimidophenoxy)silane, methylphenyl(4,4-bismaleimidophenoxy)silane, diphenyl(4,4-bismaleimidophenoxy)silane, trimethyl(4-maleimidophenoxy)silane and dimethylphenyl(4-maleimidophenoxy)silane; preferably, the maleimide monomers containing siloxane groups in the core layer have two N-phenylmaleimide groups; preferably, the maleimide monomers containing siloxane groups in the core layer are selected from one or more of dimethyl(4,4-bismaleimidophenoxy)silane, methylphenyl(4,4-bismaleimidophenoxy)silane and diphenyl(4,4-bismaleimidophenoxy)silane; preferably, the maleimide monomers containing siloxane groups in the shell layer have one N-phenylmaleimide group; preferably, the maleimide monomers containing siloxane groups in the shell layer are selected from one or two of trimethyl(4-maleimidophenoxy)silane and dimethylphenyl(4-maleimidophenoxy)silane.

3. The acrylate-styrene-acrylonitrile core-shell graft copolymer according to claim 1, characterized in that the acrylate-styrene-acrylonitrile core-shell graft copolymer has one or more of the following characteristics: The acrylate monomer in the core part and the acrylate monomer in the core layer are each independently one or more acrylate alkyl esters with the structural formula CH 2 =CHCOOR, where R is a C1-C15 alkyl group, preferably a C1-C4 linear alkyl group; preferably, the acrylate monomer in the core part and the acrylate monomer in the core layer are each independently selected from one or more of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylbutyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, hexyl acrylate, heptyl acrylate, n-pentyl acrylate and lauryl acrylate; preferably, the acrylate monomer in the core part and the acrylate monomer in the core layer are butyl acrylate; the grafting agent in the core and the grafting agent in the core layer are each independently one or more compounds containing two or more different unsaturated vinyl functional groups; preferably, the grafting agent in the core and the grafting agent in the core layer are each independently selected from one or more of allyl methacrylate, triallyl isocyanurate, triallylamine and diallylamine; preferably, the grafting agent in the core and the grafting agent in the core layer are allyl methacrylate; the crosslinking agent is one or more compounds containing two or more identical unsaturated vinyl functional groups; preferably, the crosslinking agent is selected from one or more of ethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate and 1,3-propanediol diacrylate; preferably, the crosslinking agent is ethylene glycol dimethacrylate; the vinyl aromatic monomer is selected from one or more of styrene, α-methylstyrene and p-methylstyrene, preferably styrene; the vinyl nitrile monomer is selected from one or two of acrylonitrile and methacrylonitrile, preferably acrylonitrile; in the core, the mass ratio of the structural unit converted from the grafting agent to the structural unit converted from the acrylate monomer is (0.2-3):100; in the core, the mass ratio of the structural unit converted from the crosslinking agent to the structural unit converted from the acrylate monomer is (0.2-3):100; in the core layer, the mass ratio of the structural unit converted from the grafting agent to the structural unit converted from the acrylate monomer is (0.2-2):100; the core layer includes or does not include the structural unit converted from the crosslinking agent; preferably, the core layer includes the structural unit converted from the crosslinking agent but does not include the structural unit converted from the maleimide monomer containing a siloxane group, and in the core layer, the mass ratio of the structural unit converted from the crosslinking agent to the structural unit converted from the acrylate monomer is (0.2-2):100; preferably, the core layer includes the structural unit converted from the maleimide monomer containing a siloxane group, includes or does not include the structural unit converted from the crosslinking agent, and in the core layer, the mass ratio of the structural unit converted from the crosslinking agent to the structural unit converted from the acrylate monomer is (0-2):100; the mass fraction of the structural unit converted from the vinyl aromatic monomer in the shell layer is 70%-80%, and the mass fraction of the structural unit converted from the vinyl nitrile monomer in the shell layer is 0-25%, preferably 5-25%; The core layer includes or does not include a structural unit transformed from a maleimide monomer containing a siloxane group, the shell layer includes a structural unit transformed from a maleimide monomer containing a siloxane group, and the mass fraction of the structural unit transformed from the maleimide monomer containing a siloxane group in the shell layer is 2.5-30%, preferably 5-25%, more preferably 5-20%.

4. An acrylate-styrene-acrylonitrile core-shell graft copolymer latex, characterized in that the acrylate-styrene-acrylonitrile core-shell graft copolymer latex is an aqueous dispersion of the acrylate-styrene-acrylonitrile core-shell graft copolymer as described in any one of claims 1-3.

5. A method for preparing the acrylate-styrene-acrylonitrile core-shell graft copolymer as described in any one of claims 1-3 or the acrylate-styrene-acrylonitrile core-shell graft copolymer latex as described in claim 4, characterized in that the method comprises the following steps: (1) In the presence of water, an emulsifier, an electrolyte and a water-soluble initiator, reacting an acrylate monomer, a grafting agent and a crosslinking agent to form a core, and obtaining a seed latex; (2) In the presence of water, an emulsifier, an electrolyte and a water-soluble initiator, reacting the seed latex obtained in step (1), an acrylate monomer, a grafting agent, an optionally present crosslinking agent and an optionally present maleimide monomer containing a siloxane group, and forming a core layer on the surface of the core to obtain a polyacrylate latex; (3) In the presence of water, an emulsifier, an electrolyte and an oil-soluble initiator, reacting the polyacrylate latex obtained in step (2), a vinyl aromatic monomer, an optionally present vinyl nitrile monomer and an optionally present maleimide monomer containing a siloxane group, and forming a shell layer on the surface of the core layer to obtain an acrylate-styrene-acrylonitrile core-shell graft copolymer latex; wherein, a maleimide monomer containing a siloxane group is added to the reaction system of at least one of step (2) and step (3); Preferably, the maleimide monomer containing a siloxane group is added or not added to the reaction system of step (2), and the maleimide monomer containing a siloxane group is added to the reaction system of step (3).

6. The method for preparing an acrylate-styrene-acrylonitrile core-shell graft copolymer or an acrylate-styrene-acrylonitrile core-shell graft copolymer latex as described in claim 5, characterized in that the method has one or more of the following characteristics: The emulsifiers in step (1), step (2) and step (3) are each independently selected from one or more of sodium dodecyl sulfate, sodium dodecylbenzenesulfate, sodium octadecyl sulfate, sodium oleate, potassium dodecyl sulfate, potassium dodecylbenzenesulfate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium oleate, potassium dodecylbenzenesulfonate, potassium octadecyl sulfate, potassium rosin and potassium oleate, and preferably sodium dodecyl sulfate; The electrolytes in step (1), step (2) and step (3) are each independently selected from one or more of sodium chloride, potassium chloride, sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate, and preferably sodium bicarbonate; The water-soluble initiator in step (1) and step (2) is selected from one or more of sodium persulfate, potassium persulfate, ammonium persulfate, potassium peroxophosphate, and hydrogen peroxide, and preferably potassium persulfate; The oil-soluble initiator in step (3) is selected from one or more of tert-butyl peroxide, cumene hydroperoxide, p-menthane hydroperoxide, di-tert-butyl peroxide, tert-butyl cumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, benzoyl peroxide, diisopropylbenzene hydroperoxide, 3,5,5-trimethylhexyl hydroperoxide, tert-butyl peroxyisobutyrate, azobisisobutyronitrile, azo-bis(2,4-dimethylvaleronitrile), azobiscyclohexanecarbonitrile, and azobis(isobutyric acid methyl ester), and preferably cumene hydroperoxide; In step (1), the mass ratio of water to the acrylate monomer is (150-200):100; In step (1), the mass ratio of the emulsifier to the acrylate monomer is (0.5-3):100; In step (1), the mass ratio of the electrolyte to the acrylate monomer is (0.3-0.45):100; In step (1), the mass ratio of the water-soluble initiator to the acrylate monomer is (0.25-0.5):100; In step (1), part of the acrylate monomer, part of the grafting agent, part of the crosslinking agent, part of the water-soluble initiator, part of the emulsifier, and part of the water are gradually added to the reaction system in the form of a first pre-emulsion during the reaction. The masses of the acrylate monomer, grafting agent, crosslinking agent, water-soluble initiator, and emulsifier in the first pre-emulsion are 60%-90% of the masses of the acrylate monomer, grafting agent, crosslinking agent, water-soluble initiator, and emulsifier used in step (1); In step (1), the reaction temperature is 70-80 °C, and the reaction is carried out until the polymerization conversion rate ≥ 98%; In step (2), the mass ratio of the added water to the acrylate monomer is (150-200):100; In step (2), the mass ratio of the emulsifier to the acrylate monomer is (0.5-3):100; In step (2), the mass ratio of the electrolyte to the acrylate monomer is (0.3-0.45):100; In step (2), the mass ratio of the water-soluble initiator to the acrylate monomer is (0.25-0.5):100; In step (2), part of the acrylate monomers, part of the grafting agent, part of the water-soluble initiator, part of the emulsifier, and part of the water are gradually added to the reaction system in the form of a second pre-emulsion. The masses of the acrylate monomers, grafting agent, water-soluble initiator, and emulsifier in the second pre-emulsion are 60% - 90% of the masses of the acrylate monomers, grafting agent, water-soluble initiator, and emulsifier used in step (2). When a maleimide monomer containing a siloxane group is added to the reaction system in step (2), all or part of the maleimide monomer containing a siloxane group is gradually added to the reaction system in the form of a second pre-emulsion. When a crosslinking agent is added to the reaction system in step (2), part of the crosslinking agent is gradually added to the reaction system in the form of a second pre-emulsion; In step (2), the reaction temperature is 75 - 85 °C, and the reaction proceeds until the polymerization conversion rate ≥ 98%; In step (3), the mass ratio of the added water to the total mass of the polyacrylate latex dry matter, the vinyl aromatic monomer, and the vinyl nitrile monomer is (150 - 200):100; In step (3), the mass ratio of the emulsifier to the total mass of the polyacrylate latex dry matter, the vinyl aromatic monomer, and the vinyl nitrile monomer is (0.5 - 3):100; In step (3), the mass ratio of the electrolyte to the total mass of the polyacrylate latex dry matter, the vinyl aromatic monomer, and the vinyl nitrile monomer is (0.3 - 0.45):100; In step (3), the mass ratio of the oil-soluble initiator to the total mass of the polyacrylate latex dry matter, the vinyl aromatic monomer, and the vinyl nitrile monomer is (0.25 - 0.5):100; In step (3), part of the vinyl aromatic monomer, part of the oil-soluble initiator, part of the emulsifier, and part of the water are gradually added to the reaction system in the form of a third pre-emulsion. The masses of the vinyl aromatic monomer, oil-soluble initiator, and emulsifier in the third pre-emulsion are 60% - 90% of the masses of the vinyl aromatic monomer, oil-soluble initiator, and emulsifier used in step (3). When a vinyl nitrile monomer is added to the reaction system in step (3), all of the vinyl nitrile monomer is added to the reaction system at the start of the reaction, or part or all of the vinyl nitrile monomer is gradually added to the reaction system in the form of a third pre-emulsion. When a maleimide monomer containing a siloxane group is added to the reaction system in step (3), all of the maleimide monomer containing a siloxane group is added to the reaction system at the start of the reaction, or part or all of the maleimide monomer containing a siloxane group is gradually added to the reaction system in the form of a third pre-emulsion; In step (3), the reaction temperature is 65 - 75 °C, and the reaction proceeds until the polymerization conversion rate ≥ 98%.

7. The method for preparing an acrylate-styrene-acrylonitrile core-shell graft copolymer or an acrylate-styrene-acrylonitrile core-shell graft copolymer latex according to claim 5, characterized in that Step (1) includes: adding acrylate monomer, grafting agent, crosslinking agent, water, emulsifier, electrolyte and water-soluble initiator into a reactor, heating to 70 - 80 °C and reacting for 20 - 40 min, then maintaining the reaction temperature, adding the first pre-emulsion into the reactor within 3 - 4 h, and reacting at a constant temperature for 1 - 2 h until the polymerization conversion rate ≥ 98%, stopping the reaction to obtain seed latex; wherein the first pre-emulsion includes acrylate monomer, grafting agent, crosslinking agent, water-soluble initiator, emulsifier and water; Step (2) includes: adding the seed latex obtained in step (1), acrylate monomer, grafting agent, optionally added crosslinking agent, water, emulsifier, electrolyte and water-soluble initiator into a reactor, heating to 75 - 85 °C and reacting for 20 - 40 min, then maintaining the reaction temperature, adding the second pre-emulsion into the reactor within 3 - 4 h, and reacting at a constant temperature for 1 - 2 h until the polymerization conversion rate ≥ 98%, stopping the reaction to obtain polyacrylate latex, wherein the second pre-emulsion includes acrylate monomer, grafting agent, optionally added crosslinking agent, optionally added maleimide monomers containing siloxane groups, water-soluble initiator, emulsifier and water; Step (3) includes: adding the polyacrylate latex obtained in step (2), water, vinyl aromatic monomer, optionally added vinyl nitrile monomer, optionally added maleimide monomers containing siloxane groups, emulsifier, electrolyte and oil-soluble initiator into a reactor, heating to 65 - 75 °C and reacting for 20 - 40 min, then maintaining the reaction temperature, adding the third pre-emulsion into the reactor within 3 - 4 h, and reacting at a constant temperature for 1 - 2 h until the polymerization conversion rate reaches ≥ 98%, stopping the reaction to prepare acrylate-styrene-acrylonitrile core-shell graft copolymer latex, wherein the third pre-emulsion includes vinyl aromatic monomer, optionally added vinyl nitrile monomer, optionally added maleimide monomers containing siloxane groups, oil-soluble initiator, emulsifier and water.

8. The method for preparing acrylate-styrene-acrylonitrile core-shell graft copolymer according to claim 5, characterized in that, the method further includes the following steps: (4) Demulsifying, curing, washing and drying the acrylate-styrene-acrylonitrile core-shell graft copolymer latex obtained in step (3) to obtain acrylate-styrene-acrylonitrile core-shell graft copolymer.

9. An acrylate-styrene-acrylonitrile copolymer blend resin, characterized in that, the acrylate-styrene-acrylonitrile copolymer resin comprises the acrylate-styrene-acrylonitrile core-shell graft copolymer according to any one of claims 1 - 3 and acrylonitrile-styrene copolymer; Preferably, in the acrylate-styrene-acrylonitrile copolymer blend resin, the mass ratio of the acrylate-styrene-acrylonitrile core-shell graft copolymer to the acrylonitrile-styrene copolymer is 30:70 to 45:55; Preferably, the acrylate-styrene-acrylonitrile copolymer blend resin further comprises an antioxidant and / or a lubricant. Based on the total mass of 100 parts by mass of the acrylate-styrene-acrylonitrile core-shell graft copolymer and the acrylonitrile-styrene copolymer, the mass of the antioxidant is 0.2 - 0.5 parts by mass, and the mass of the lubricant is 0.2 - 0.5 parts by mass. Preferably, the acrylate-styrene-acrylonitrile copolymer blend resin is prepared by blending and extruding a raw material composition comprising the acrylate-styrene-acrylonitrile core-shell graft copolymer and the acrylonitrile-styrene copolymer; preferably, the extrusion temperature is 180 - 240 °C.

10. A plastic comprising the acrylate-styrene-acrylonitrile core-shell graft copolymer according to any one of claims 1 - 3 or the acrylate-styrene-acrylonitrile copolymer blend resin according to claim 9; Preferably, the matrix resin of the plastic is polyvinyl chloride, polyamide, polycarbonate, polyoxymethylene, polyphenylene ether, polyester, polyimide, polyphenylene sulfide, polysulfone, polyether ether ketone, polyarylether ketone or fluororesin.

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