ASA resin and preparation method thereof

Abstract

The invention provides ASA resin and a preparation method thereof. The method comprises the following steps: based on an agglomeration technology, partially agglomerating small-particle-size polyacrylate latex into large-particle-size polyacrylate latex by utilizing a macromolecular emulsion agglomerant and regulating and controlling retention time in a kettle, and carrying out emulsion graft polymerization on the large-particle-size polyacrylate latex and the small-particle-size polyacrylate latex to form a core-shell ASA graft copolymer; and performing flocculation and drying, and performing melt blending with SAN resin to prepare the ASA resin. A part of butadiene structure is introduced into the ASA resin prepared by the method, so that the ASA resin has high normal-temperature and low-temperature impact resistance at the same time, and meanwhile, due to the addition of small particle size in the rubber structure, the surface roughness of the resin is reduced, and the glossiness of the ASA resin is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of engineering plastics technology, and specifically relates to an ASA resin and its preparation method. Background Technology

[0002] ASA resin is a ternary polymer composed of acrylate (A), styrene (S), and acrylonitrile (A). ASA resin exhibits similar properties to ABS resin, possessing excellent mechanical properties, processability, electrical insulation, chemical resistance, and colorability. Compared to ABS resin, ASA resin uses polybutyl acrylate rubber instead of the polybutadiene rubber in ABS resin. The absence of unsaturated double bonds in the polybutadiene molecular chain of ASA resin results in superior weather resistance compared to ABS resin, allowing for long-term outdoor use. It is widely used in the automotive, electronics, and outdoor building materials industries.

[0003] The core of ASA resin lies in the preparation of high-polymer ASA powder, which currently falls into two main categories: emulsion blending and grafting. Grafting is the primary method, further subdivided into bulk polymerization, suspension polymerization, and emulsion polymerization. Bulk polymerization and suspension polymerization suffer from difficulties in controlling rubber particle size, making it challenging to obtain high-quality products. Emulsion graft polymerization, on the other hand, offers advantages in controlling reaction rate and particle size distribution, and is currently the most commonly used method for ASA preparation.

[0004] Patent US2002198309 discloses a method for increasing the particle size of butadiene latex by using butadiene-ethyl acrylate-methacrylic acid copolymer latex as a polymer agglomerant, but it does not provide a detailed preparation process for the agglomerant.

[0005] CN116574351A employs polymer agglomeration technology, which prepares a polymer agglomerant by copolymerizing hydrophilic monomers with acrylates, agglomerating small-particle-size polyacrylate latex into large-particle-size polyacrylate latex. This only improves the impact resistance of the resin, but the large-particle-size latex alone increases the surface roughness of the resin, leading to a decrease in gloss.

[0006] CN102321211B synthesizes a binary copolymer latex of acrylate and unsaturated acid by emulsion polymerization, and uses compound emulsifiers and initiators to agglomerate and control the particle size to achieve the expansion of small particle size latex.

[0007] CN109627621B improves the gloss of the final ASA resin by adding low molecular weight polymethyl methacrylate during the blending process, but its impact resistance remains low.

[0008] The background technology of CN115677946A mentions using the synergistic effect of compounding different particle sizes to improve and enhance material properties, especially to balance the impact toughness and rigidity of materials. It uses the seed diameter expansion method to prepare large particle size latex for compounding, which has limited improvement in impact resistance and does not significantly explain the effect on gloss.

[0009] In AU2012234110A1, the impact resistance of the overall resin is improved by adding thermoplastic resin C-5 (polycarbonate) during the blending process. However, the impact resistance of simply blending polyacrylate with SAN resin of varying particle sizes remains poor. Furthermore, before using it in copolymer latex containing acid groups, it is necessary to further add condensed acids such as phosphoric acid or silica, along with alkali metal and / or alkaline earth metal salts, to the latex to ensure the stability and effectiveness of latex agglomeration. Moreover, for small particle sizes, it is difficult to control the polymerization temperature using the rapid polymerization method.

[0010] For high-end applications such as new energy vehicles and electronic products, excellent weather resistance alone is insufficient for ASA resin; it also needs to possess high impact resistance and good gloss. Current methods for improving the gloss of ASA resin mainly involve blending it with PMMA, but this method cannot guarantee the high impact resistance of ASA resin, limiting its applications. Therefore, finding an ASA resin material that combines good impact resistance and gloss has become an urgent problem to be solved in the industry. Summary of the Invention

[0011] This invention provides an ASA resin and its preparation method. Based on agglomeration technology, using a polymeric emulsion agglomerant, and by controlling the residence time in the reactor to regulate the ratio of large and small particle sizes, the surface roughness of the finished ASA resin is further controlled. While ensuring the mechanical properties of the finished resin, the surface gloss of the finished ASA resin is significantly improved.

[0012] An ASA resin, comprising an acrylate rubber core layer and a styrene-acrylonitrile copolymer shell layer, wherein the core layer is sourced from small-particle-size polyacrylate latex with a particle size of 60-150 nm and large-particle-size polyacrylate latex with a particle size of 250-600 nm, wherein the mass ratio of large-particle-size polyacrylate latex to small-particle-size polyacrylate latex is 80-20:20-80.

[0013] As a preferred embodiment, the particle size of the small-particle-size polyacrylate latex in the core layer is 60-150 nm, and the particle size of the large-particle-size polyacrylate latex is 300-550 nm; more preferably, the particle size of the small-particle-size polyacrylate latex in the core layer is 80-120 nm, and the particle size of the large-particle-size polyacrylate latex is 350-500 nm. The particle size of the latex mainly affects the impact resistance and gloss of the resin. If the particle size of the latex is too small, it cannot provide a corresponding toughening effect, resulting in low overall impact resistance; while if the particle size of the latex is too large, the surface roughness of the resin increases, and the gloss decreases accordingly.

[0014] As a preferred embodiment, the mass ratio of the acrylate rubber core layer to the styrene-acrylonitrile copolymer shell layer is 30–70:70–30; more preferably, the mass ratio is 35–65:65–35. The shell thickness of the styrene-acrylonitrile copolymer directly affects the interfacial compatibility between the rubber particles and the resin matrix. An excessively thin shell may result in insufficient interfacial bonding between the dispersed phase (rubber particles) and the continuous phase (SAN resin), thereby weakening the ability to absorb impact energy; while an excessively thick shell will result in excessively long molecular chains, which will also affect the compatibility between the rubber particles and the SAN resin.

[0015] The method for preparing small-particle-size polyacrylate latex according to the present invention includes the following steps: adding chain transfer agent, activator and water into a reaction vessel, starting stirring, maintaining a nitrogen atmosphere in the reaction vessel, and when the system temperature reaches the reaction temperature of 40-80°C, continuously adding acrylate monomers, emulsifiers, crosslinking agents and initiators dropwise over a period of 0-5 hours. After the addition is completed, the system temperature is raised to 60-90°C to eliminate residual monomers, so that the conversion rate is greater than 98%.

[0016] In the preparation method of the small particle size polyacrylate latex of the present invention, the raw materials are composed of the following parts by weight: 50-200 parts of acrylate monomers, 100-500 parts of water, 1-5 parts of crosslinking agent, 1-8 parts of emulsifier, 0-5 parts of chain transfer agent, 0.05-1.8 parts of activator, and 0.05-1.5 parts of initiator; more preferably, 100-150 parts of acrylate monomers, 150-350 parts of water, 2.5-4.5 parts of crosslinking agent, 2-6 parts of emulsifier, 1-3 parts of chain transfer agent, 0.3-1.5 parts of activator, and 0.05-1.0 parts of initiator.

[0017] In the preparation method of small particle size polyacrylate latex of the present invention, the acrylate monomer is one or more of methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, and isobutyl acrylate.

[0018] In the preparation method of small particle size polyacrylate latex of the present invention, the crosslinking agent is one or more of allyl methacrylate (ALMA), ethylene glycol methacrylate (EGDMA), diallyl maleate, dicyclopentadienyl acrylate, triallyl urate, 1,4-butanediol dimethacrylate, and triallyl isocyanurate; more preferably, the crosslinking agent is one or more of ALMA, EGDMA, diallyl maleate, and dicyclopentadienyl acrylate.

[0019] In the preparation method of small particle size polyacrylate latex of the present invention, the emulsifier is one or more of potassium oleate, sodium alkyl diphenyl ether disulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, sodium dihexyl succinate sulfonate, sodium alkylphenol ether sulfosuccinate, and sodium dioctyl succinate sulfonate (DOSS); more preferably, the emulsifier is one or more of potassium oleate, DOSS, sodium dodecylbenzene sulfonate, and sodium dodecyl sulfate.

[0020] In the preparation method of small particle size polyacrylate latex of the present invention, the chain transfer agent is one or two of tert-dodecyl mercaptan and n-octyl mercaptan.

[0021] In the preparation method of small particle size polyacrylate latex of the present invention, the activator is a mixture of sodium formaldehyde sulfoxylate, disodium ethylenediaminetetraacetate and ferrous sulfate.

[0022] In the preparation method of small particle size polyacrylate latex of the present invention, the initiator is cumene hydroperoxide and / or tert-butyl hydroperoxide.

[0023] As a preferred embodiment, the method for preparing large-particle-size polyacrylate latex according to the present invention includes the following steps:

[0024] 1) Take 100 parts of the small particle size polyacrylate latex described in this invention and place them in an agglomeration reactor;

[0025] 2) Add 0.1 to 10 parts of emulsion agglomerating agent to the agglomeration reactor and agglomerate at 20 to 80°C for 30 to 120 minutes to obtain large particle size polyacrylate latex.

[0026] The preparation method of the emulsion agglomerator of the present invention includes the following steps: adding emulsifier, water and activator into a reaction vessel, starting stirring, and when the system temperature reaches the reaction temperature, adding monomer and initiator solution dropwise simultaneously. After the dropwise addition is completed, the system is kept at a constant temperature to eliminate residual monomer, so that the monomer conversion rate is greater than 98%.

[0027] In the preparation method of the emulsion agglomerator of the present invention, the raw materials are composed of the following parts by weight: 1-10 parts emulsifier, 100-500 parts water, 0.05-1.8 parts activator, 50-200 parts monomer, and 0.05-1.5 parts initiator.

[0028] In the preparation method of the emulsion agglomerator of the present invention, the emulsifier is potassium oleate, sodium alkyl diphenyl ether disulfonate, etc.

[0029] Sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, sodium dihexyl succinate sulfonate, sodium alkylphenol ether sulfosuccinate, and DOSS are selected as one or more; more preferably, the emulsifier is sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, and DOSS are selected as one or more.

[0030] In the preparation method of the emulsion agglomerator of the present invention, the activator is a mixture of sodium formaldehyde sulfoxylate, disodium ethylenediaminetetraacetate and ferrous sulfate.

[0031] In the preparation method of the emulsion agglomerator of the present invention, the monomer is at least one of 1,3-butadiene and acrylate monomers and a mixture of α,β-unsaturated acid monomers.

[0032] In the preparation method of the emulsion agglomerator of the present invention, the initiator is one or more of cumene hydroperoxide and tert-butyl hydroperoxide.

[0033] In the preparation method of large-particle-size polyacrylate emulsion of the present invention, in step 2), the particle size of the large-particle-size polyacrylate latex can be controlled by adjusting the agglomeration time.

[0034] The method for preparing the high-impact, high-gloss ASA resin of the present invention includes the following steps: according to the proportion,

[0035] (1) Add small-particle-size polyacrylate latex, large-particle-size polyacrylate latex, water, emulsifier, and initiator to a reaction vessel and heat to 50-60℃; add dropwise a mixture of styrene and acrylonitrile for 2-4 hours. After the dropwise addition is complete, keep the temperature at 70℃ for 0.5-2 hours. Stop the reaction after the monomers are consumed to obtain a mixed grafted latex of small and large particle sizes.

[0036] (2) Coagulate the grafted latex, dry it, and obtain a rubber powder with a moisture content of less than 1%;

[0037] (3) Mix the adhesive powder, SAN resin and additives, melt blend, extrude and then pelletize underwater and dry.

[0038] In the preparation method of the high-impact, high-gloss ASA resin of the present invention, the additives include one or more of antioxidant 1076, antioxidant 618, magnesium oxide, and N,N-ethylene bis-stearamide.

[0039] The beneficial effects of this invention are as follows: Based on agglomeration technology, this invention introduces a portion of the butadiene structure using a polymeric emulsion agglomerator, resulting in high impact resistance at both room temperature and low temperature for the finished ASA resin. Simultaneously, by controlling the ratio of large and small particle sizes in the polyacrylate latex, small particle sizes are introduced into the rubber structure, reducing the surface roughness of the resin while maintaining its mechanical properties, thus further improving the gloss of the ASA resin. Detailed Implementation

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Analytical instruments:

[0042] Izod impact strength: CEAST 9050 pendulum impact tester;

[0043] Tensile strength and elongation at break: Instron 5966 universal testing machine;

[0044] Test method:

[0045] Izod impact strength: Standard ASTM D256;

[0046] Tensile strength and elongation at break: Standard ASTM D638;

[0047] Grafting rate test:

[0048] (1) Weigh the dried ASA powder (water content less than 1%, accurate to 0.0001 g, mass is G) into a 100 ml flask, add 50 ml of acetone along the neck of the flask, attach the condenser to the flask, and reflux in a 65℃ constant temperature water bath for 2.0 hours. During this period, do not allow the water bath temperature to exceed 65℃, otherwise bumping may occur.

[0049] (2) Remove the flask and cool it to room temperature. Transfer the solution in the flask to a pre-weighed beaker and let it settle for 4 hours. Remove the supernatant. Place the beaker in a vacuum oven and dry it under vacuum at 65°C until constant weight. Weigh and calculate the dry basis mass as G1.

[0050] The grafted rubber content X (%) is calculated using the following formula: Grafted rubber content X = G1 / G * 100%,

[0051] In the formula: G1—grafted rubber mass (i.e., total of polybutyl acrylate and grafted SAN), unit: grams;

[0052] G—Sample mass (i.e., ABS grafting powder mass), unit: grams.

[0053] Grafting rate π = [(grafted rubber content - formulated rubber content) / (formulated rubber content)] × 100%.

[0054] Solid content test:

[0055] The solid content was obtained by drying at 180°C using a Mettler HC103 moisture analyzer.

[0056] Slag content test:

[0057] After the agglomeration reaction is completed, the latex is filtered through a 100-mesh filter, and the filtered latex residue is dried in an oven at 80°C for 4 hours.

[0058] Slag content = m / M * 100%

[0059] m: Quality of adhesive residue on filter screen

[0060] M: Total mass of latex

[0061] Gloss test:

[0062] The gloss of the resin material surface was tested at three angles: 20°, 60°, and 85° using a German BYK4446 miniature three-angle gloss meter.

[0063] Test standard: ASTM D523-2014.

[0064] Example 1

[0065] Preparation of emulsion agglomerant 1:

[0066] (1) By mass, add 16g sodium dodecylbenzenesulfonate, 32g DOSS, 0.025g ferrous sulfate heptahydrate activator, 2.4g sodium formaldehyde sulfoxylate and 0.075g disodium ethylenediaminetetraacetate to a high-pressure reactor, add 1650g deionized water, start the reactor and stir to 200rpm to dissolve it quickly, introduce nitrogen to remove air from the reactor and heat the reactor to 60℃.

[0067] (2) Add 760g of 1,3-butadiene monomer to the reactor, and simultaneously add 160g of methacrylic acid copolymer functional monomer and 4g of cumene hydroperoxide initiator. The addition time is 2 hours. After the addition is completed, maintain the reactor temperature at 60℃ for 2 hours. After cooling, a polymer agglomerant can be obtained. The average particle size of the agglomerant is 105nm, the final solid content is 36.95%, and the reaction conversion rate is 98.1%.

[0068] Preparation of emulsion agglomerator 2:

[0069] (1) By mass, add 30g sodium dodecyl sulfate, 0.0225g ferrous sulfate heptahydrate activator, 2.16g sodium formaldehyde sulfoxylate and 0.0675g disodium ethylenediaminetetraacetate to a high-pressure reactor, add 1750g deionized water, start the reactor and stir to 200rpm to dissolve it quickly, introduce nitrogen to remove air from the reactor and heat the reactor to 60℃.

[0070] (2) Add 300g of 1,3-butadiene and 200g of butyl acrylate to the reactor dropwise, and simultaneously add 250g of acrylic acid, a comonomer, and 3g of cumene hydroperoxide, an initiator. The dropwise addition time is 2 hours. After the dropwise addition is completed, maintain the reactor temperature at 60℃ for 2 hours. After cooling, a polymer agglomerant can be obtained. The average particle size of the agglomerant is 120nm, the final solid content is 30.50%, and the reaction conversion rate is 98.7%.

[0071] Preparation of small-particle-size polyacrylate latex a1:

[0072] (1) By mass, 11g of chain transfer agent tert-dodecyl mercaptan, 0.025g of ferrous sulfate heptahydrate activator, 2.375g of sodium formaldehyde sulfoxylate and 0.075g of disodium ethylenediaminetetraacetate were added to a high-pressure reactor, along with 1100g of deionized water. The mixture was stirred at 180rpm to ensure uniform mixing. Nitrogen gas was introduced to remove air from the reactor and the reactor was heated to 50°C.

[0073] (2) When the system temperature reaches the reaction temperature of 50℃, 440g of n-butyl acrylate monomer, 13.75g of allyl methacrylate crosslinking agent, 13.2g of sodium dodecylbenzenesulfonate emulsifier, 3.3g of DOSS, and 3.96g of cumene hydroperoxide initiator are added dropwise over a period of 3 hours. After the addition is completed, the temperature of the reactor is raised to 70℃ and kept at that temperature for 2 hours. After cooling, small-particle-size polyacrylate latex is obtained with an average particle size of 130nm, a final solid content of 30.35%, and a reaction conversion rate of 98.8%.

[0074] Preparation of small particle size polyacrylate latex a2:

[0075] (1) By mass, 5.5g of chain transfer agent tert-dodecyl mercaptan, 0.0275g of ferrous sulfate heptahydrate activator, 2.64g of sodium formaldehyde sulfoxylate and 0.0825g of disodium ethylenediaminetetraacetate were added to a high-pressure reactor, along with 1430g of deionized water. The mixture was stirred at 180 rpm to ensure uniform mixing. Nitrogen gas was introduced to remove air from the reactor and the reactor was heated to 50°C.

[0076] (2) When the system temperature reaches the reaction temperature of 50℃, 660g of n-butyl acrylate monomer, 16.5g of ethylene glycol methacrylate crosslinking agent, 20.9g of sodium dodecyl sulfate emulsifier, and 3.74g of cumene hydroperoxide initiator are added dropwise over a period of 4 hours. After the addition is completed, the temperature of the reactor is raised to 70℃ and kept at that temperature for 2 hours. After cooling, small-particle-size polyacrylate latex is obtained with an average particle size of 120nm, a final solid content of 32.68%, and a reaction conversion rate of 98.6%.

[0077] Preparation of large particle size polyacrylate latex A1:

[0078] Take 100g of small-particle-size polyacrylate latex A1 (dry basis, adjust solid content to 20%) and place it in an agglomeration reactor. Add 13g of emulsion agglomerating agent (dry basis) to the agglomeration reactor. After agglomeration at 50℃ for 30min, large-particle-size polyacrylate latex A1 with a latex particle size of 380nm can be obtained.

[0079] Preparation of large particle size polyacrylate latex A2:

[0080] Take 100g of small-particle-size polyacrylate latex a2 (dry basis, adjust solid content to 20%) and place it in an agglomeration reactor. Add 24g of emulsion agglomerating agent 2 (dry basis) to the agglomeration reactor. After agglomeration at 50℃ for 60min, large-particle-size polyacrylate latex B1 with a latex particle size of 450nm can be obtained.

[0081] Preparation of grafted latex with mixed particle sizes:

[0082] Take 48 parts by weight of small-particle-size polyacrylate latex a1 (dry basis), 12 parts by weight of large-particle-size polyacrylate latex A1 (dry basis) (small particle size: large particle size = 80:20), 240 parts by weight of water, 0.2 parts by weight of emulsifier, and 0.05 parts by weight of initiator and add them to the reaction vessel, and heat to 50°C;

[0083] (2) Add dropwise a mixture of 40 parts by mass of styrene and 10 parts by mass of acrylonitrile over 3 hours. After the addition is complete, keep the temperature at 70°C for 0.5 hours. Stop the reaction after the monomers are consumed.

[0084] Examples 2-8

[0085] Keeping the total mass of large-particle-size polyacrylate latex and small-particle-size polyacrylate latex at 60 parts by mass, the mixed-particle-size grafted latexes of Examples 2-8 were prepared according to the ratio of large-particle-size latexes in Table 1 and the preparation method of mixed-particle-size grafted latex in Example 1.

[0086] Table 1. Amount and proportion of latex with different particle sizes in Examples 2-8

[0087] Example 2 3 4 5 6 7 8 Small particle size latex a1 a1 a1 a1 a1 a2 a2 Large particle size latex A1 A1 A1 A1 A2 A1 A2 Small particle size: Large particle size 60:40 50:50 40:60 20:80 50:50 50:50 50:50

[0088] Example 9

[0089] Preparation of emulsion agglomerator 3:

[0090] (1) By mass, add 30g of potassium oleate, 0.02g of ferrous sulfate heptahydrate activator, 1.92g of sodium formaldehyde sulfoxylate and 0.06g of disodium ethylenediaminetetraacetate to a high-pressure reactor, add 1200g of deionized water, start the reactor and stir at 200rpm to dissolve it quickly, introduce nitrogen to remove air from the reactor and heat the reactor to 60℃.

[0091] (2) Add 500g of 1,3-butadiene, a monomer, to the reactor dropwise, and simultaneously add 200g of acrylic acid, a comonomer, and 2g of cumene hydroperoxide, an initiator. The dropwise addition time is 2 hours. After the dropwise addition is completed, maintain the reactor temperature at 60℃ for 2 hours. After cooling, a polymer agglomerant can be obtained. The average particle size of the agglomerant is 132nm, the final solid content is 37.1%, and the reaction conversion rate is 97.7%.

[0092] Preparation of small particle size polyacrylate latex B1:

[0093] (1) By mass, add 13.5g of chain transfer agent n-octyl mercaptan, 0.045g of activator ferrous sulfate heptahydrate, 4.32g of sodium formaldehyde sulfoxylate and 0.135g of disodium ethylenediaminetetraacetate to a high-pressure reactor, add 1575g of deionized water, start stirring to 180rpm to mix evenly, purge nitrogen to remove air from the reactor and heat the reactor to 50°C.

[0094] (2) When the system temperature reaches the reaction temperature of 50℃, 675g of monomer ethyl acrylate, 20.25g of crosslinking agent allyl methacrylate, 24g of emulsifier sodium dodecyl sulfate, 3g of DOSS, and 3.6g of initiator tert-butyl hydroperoxide are added dropwise over a period of 3 hours. After the addition is completed, the temperature of the reactor is raised to 70℃ and kept at that temperature for 2 hours. After cooling, small-particle-size polyacrylate latex is obtained with an average particle size of 60nm, a final solid content of 31.8%, and a reaction conversion rate of 99.1%.

[0095] Preparation of large particle size polyacrylate latex B1:

[0096] Take 100g of small-particle-size polyacrylate latex B1 (dry basis, adjust solid content to 20%) and place it in an agglomeration reactor. Add 3.5g of emulsion agglomerating agent (dry basis) to the agglomeration reactor. After agglomeration at 50℃ for 60min, large-particle-size polyacrylate latex B1 with a latex particle size of 520nm can be obtained.

[0097] Preparation of grafted latex with mixed particle sizes:

[0098] Take 30 parts by weight (dry basis) of small particle size polyacrylate latex b1, 30 parts by weight (dry basis) of large particle size polyacrylate latex A1 prepared in Example 1, 240 parts by weight of water, 0.2 parts by weight of emulsifier, and 0.05 parts by weight of initiator and add them to the reaction vessel, and heat to 50°C;

[0099] (2) Add dropwise a mixture of 40 parts by mass of styrene and 10 parts by mass of acrylonitrile over 3 hours. After the addition is complete, keep the temperature at 70°C for 0.5 hours. Stop the reaction after the monomers are consumed.

[0100] Examples 10-13

[0101] Keeping the total mass of large-particle-size polyacrylate latex and small-particle-size polyacrylate latex at 60 parts by mass, and preparing mixed-particle-size grafted latexes of Examples 10-13 according to the ratio of large-particle-size latexes in Table 2 and the preparation method of mixed-particle-size grafted latex in Example 9, respectively.

[0102] Table 2. Examples 10-13: Latex dosage and proportion by particle size

[0103] Example 10 11 12 13 Small particle size latex b1 b1 a1 a2 Large particle size latex A2 B1 B1 B1 Small particle size: Large particle size 50:50 50:50 50:50 50:50

[0104] Comparative Example 1

[0105] Preparation of small-particle-size polyacrylate latex C1:

[0106] (1) By mass, add 13.5g of chain transfer agent tert-dodecyl mercaptan, 0.045g of activator ferrous sulfate heptahydrate, 4.32g of sodium formaldehyde sulfoxylate and 0.135g of disodium ethylenediaminetetraacetate to a high-pressure reactor, add 1800g of deionized water, start stirring to 180rpm to mix evenly, purge nitrogen to remove air from the reactor and heat the reactor to 50°C.

[0107] (2) When the system temperature reaches the reaction temperature of 50℃, 765g of n-butyl acrylate monomer, 13.5g of allyl methacrylate crosslinking agent, 22.5g of sodium dodecylbenzene sulfonate emulsifier, and 3.6g of tert-butyl hydroperoxide initiator are added dropwise over a period of 3 hours. After the addition is completed, the temperature of the reactor is raised to 70℃ and kept at that temperature for 2 hours. After cooling, small-particle-size polyacrylate latex is obtained with an average particle size of 38nm, a final solid content of 30.8%, and a reaction conversion rate of 98.7%.

[0108] Preparation of grafted latex with mixed particle sizes:

[0109] Take 30 parts by weight (dry basis) of small particle size polyacrylate latex c1, 30 parts by weight (dry basis) of large particle size polyacrylate latex A1 prepared in Example 1, 240 parts by weight of water, 0.2 parts by weight of emulsifier, and 0.05 parts by weight of initiator and add them to the reaction vessel, and heat to 50°C.

[0110] (2) Add dropwise a mixture consisting of 40 parts by mass of styrene and 10 parts by mass of acrylonitrile. The addition is completed within 3 hours. After the addition is completed, keep the temperature at 70°C for 0.5 hours. Stop the reaction after the monomer is consumed.

[0111] Comparative Example 2

[0112] Preparation of large-particle-size polyacrylate latex C1:

[0113] Take 100g of small-particle-size polyacrylate latex C1 (dry basis, adjust solid content to 20%) and place it in an agglomeration reactor. Add 33g of emulsion agglomerating agent (dry basis) to the agglomeration reactor. After agglomeration at 50℃ for 60min, large-particle-size polyacrylate latex C1 with a latex particle size of 238nm can be obtained.

[0114] Preparation of grafted latex with mixed particle sizes:

[0115] Take 30 parts by weight (dry basis) of small particle size polyacrylate latex a1, 30 parts by weight (dry basis) of large particle size polyacrylate latex C1, 240 parts by weight of water, 0.2 parts by weight of emulsifier and 0.05 parts by weight of initiator and add them to the reaction vessel, and heat to 50℃.

[0116] (2) Add dropwise a mixture consisting of 40 parts by mass of styrene and 10 parts by mass of acrylonitrile. The addition is completed within 3 hours. After the addition is completed, keep the temperature at 70°C for 0.5 hours. Stop the reaction after the monomer is consumed.

[0117] Comparative Example 3

[0118] Preparation of large-particle-size polyacrylate latex C2:

[0119] Take 100g of small-particle-size polyacrylate latex a1 (dry basis, adjust solid content to 20%) and place it in an agglomeration reactor. Add 3.5g of emulsion agglomerating agent (dry basis) to the agglomeration reactor. After agglomeration at 50℃ for 60min, large-particle-size polyacrylate latex C2 with a latex particle size of 620nm can be obtained.

[0120] Preparation of grafted latex with mixed particle sizes:

[0121] Take 30 parts by weight (dry basis) of small particle size polyacrylate latex a1, 30 parts by weight (dry basis) of large particle size polyacrylate latex C2, 240 parts by weight of water, 0.2 parts by weight of emulsifier and 0.05 parts by weight of initiator and add them to the reaction vessel, and heat to 50℃.

[0122] (2) Add dropwise a mixture consisting of 40 parts by mass of styrene and 10 parts by mass of acrylonitrile. The addition is completed within 3 hours. After the addition is completed, keep the temperature at 70°C for 0.5 hours. Stop the reaction after the monomer is consumed.

[0123] Comparative Examples 4-6

[0124] Keeping the total mass of large-particle-size polyacrylate latex and small-particle-size polyacrylate latex at 60 parts by mass, and preparing comparative examples 4-6 of mixed-particle-size grafted latex according to the ratio of large-particle-size latex in Table 3 and the preparation scheme of mixed-particle-size grafted latex in Example 1.

[0125] Table 3 Comparative Examples 4-6: Latex dosage and proportion by particle size

[0126] Comparative Example 4 5 6 Small particle size latex a1 a1 a1 Large particle size latex A1 A1 A1 Small particle size: Large particle size 85:15 15:85 90:10

[0127] ASA resin preparation examples:

[0128] Coagulation and Drying: The mixed grafted emulsions of varying particle sizes prepared in the above examples and comparative examples were coagulated at 70°C with the addition of 9% magnesium sulfate, followed by vacuum filtration and fluidized bed drying (air velocity 180 m / s). 3 ASA grafted powder was obtained by drying at 70℃ for 0.5-1h.

[0129] Preparation of ASA resin by blending and granulation: 30 parts by weight of the above-mentioned ASA grafted powder were mixed with 60 parts by weight of 80HF (LG Chem), 0.1 parts of antioxidant 1076 (BASF, Germany), 0.1 parts of antioxidant 618 (Panhua Chemical (Shanghai) Co., Ltd.), 0.2 parts of magnesium oxide, and 2 parts of N,N-ethylene bis-stearamide (Shandong Li'ang New Material Co., Ltd.) in a high-speed kneader for 5 minutes. The mixture was then melt-granulated and blended in a twin-screw extruder at 220°C to obtain ASA resin granules. The granules were dried in an oven at 80°C for 2 hours, and after injection molding, mechanical and gloss properties were tested.

[0130] Comparative Example 7

[0131] A polymer agglomerant was prepared and a large-particle-size polyacrylate grafted latex was prepared according to the method in Example 1 of the patent "A method for preparing ASA resin based on polymer agglomeration" (CN116574351 A). The grafted latex prepared in the above comparative example was coagulated by adding 9% magnesium sulfate at 70°C, followed by vacuum filtration and fluidized bed drying (air velocity 180 m / s). 3 ASA grafted powder was obtained by drying at 70℃ for 0.5-1h.

[0132] Preparation of ASA resin by blending and granulation: 30 parts by weight of the above-mentioned ASA grafted powder were mixed with 60 parts by weight of 80HF (LG Chem), 0.1 parts of antioxidant 1076 (BASF, Germany), 0.1 parts of antioxidant 618 (Panhua Chemical (Shanghai) Co., Ltd.), 0.2 parts of magnesium oxide, and 2 parts of N,N-ethylene bis-stearamide (Shandong Li'ang New Material Co., Ltd.) in a high-speed kneader for 5 minutes. The mixture was then melt-granulated and blended in a twin-screw extruder at 220°C to obtain ASA resin granules. The granules were dried in an oven at 80°C for 2 hours, and after injection molding, mechanical and gloss properties were tested.

[0133] Comparative Example 8

[0134] The large-particle-size polyacrylate latex obtained by polymer agglomeration prepared in Comparative Example 1 was mixed with the small-particle-size latex a1 prepared in Example 1 at a ratio of 50:50, and the mixed grafted latex of large and small particle sizes was prepared according to the method of Example 1.

[0135] The grafted emulsion prepared in the above comparative example was coagulated by adding 9% magnesium sulfate at 70°C, vacuum filtered, and then dried in a fluidized bed (wind speed 180 m3 / h, temperature 70°C, drying time 0.5-1h) to obtain ASA grafted powder.

[0136] Preparation of ASA resin by blending and granulation: 30 parts by weight of the above-mentioned ASA grafted powder were mixed with 60 parts by weight of 80HF (LG Chem), 0.1 parts of antioxidant 1076 (BASF, Germany), 0.1 parts of antioxidant 618 (Panhua Chemical (Shanghai) Co., Ltd.), 0.2 parts of magnesium oxide, and 2 parts of N,N-ethylene bis-stearamide (Shandong Li'ang New Material Co., Ltd.) in a high-speed kneader for 5 minutes. The mixture was then melt-granulated and blended in a twin-screw extruder at 220°C to obtain ASA resin granules. The granules were dried in an oven at 80°C for 2 hours, and after injection molding, mechanical and gloss properties were tested.

[0137] Comparative Example 9

[0138] Large-particle-size graft copolymer a and small-particle-size graft copolymer b were prepared according to the methods of Synthesis Examples 1-2, Example 1 and Synthesis Example 9 in the patent "Composition of Acrylic Rubber-based Graft Copolymer and Thermoplastic Resin" (CN103443154A).

[0139] The above-mentioned 15 parts of large-particle-size graft copolymer a, 15 parts of small-particle-size graft copolymer b, 60 parts by weight of 80HF (LG Chem), 0.1 parts of antioxidant 1076 (BASF, Germany), 0.1 parts of antioxidant 618 (Panhua Chemical (Shanghai) Co., Ltd.), 0.2 parts of magnesium oxide, and 2 parts of N,N-ethylene bis-stearamide (Shandong Li'ang New Material Co., Ltd.) were kneaded in a high-speed kneader for 5 minutes. Then, the mixture was melt-granulated and blended in a twin-screw extruder at 220°C to obtain ASA resin granules. The granules were dried in an oven at 80°C for 2 hours, and after injection molding, mechanical properties and gloss properties were tested.

[0140] Comparative Examples 10-12

[0141] Thermoplastic resins of comparative examples 10–12 were prepared according to the ratio of large-particle-size graft copolymer a and small-particle-size graft copolymer b in Table 4.

[0142] Table 4. Ratio of graft copolymers a and b in Comparative Example 10-12

[0143]

[0144]

[0145] The resin particles prepared in Examples 1-13 and Comparative Examples 1-12 were injection molded and their performance was tested. The results are shown in Table 5.

[0146] Table 5. Performance test results of the examples and comparative examples.

[0147]

[0148] As shown in Table 3, the final product ASA resin of polyacrylate latex prepared by the present invention through the mixing of large and small particle sizes has high impact resistance. Due to the introduction of the butadiene structure, it can still maintain excellent impact resistance even at low temperature (-5℃). At the same time, due to the reduction of internal light scattering by the small particle size, it has excellent gloss. By simultaneously ensuring the high and low temperature impact resistance and excellent gloss of ASA, the application range of ASA resin in high-end fields can be further improved.

[0149] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An ASA resin, comprising an acrylate rubber core layer and a styrene-acrylonitrile copolymer shell layer, wherein the core layer is derived from small-particle-size polyacrylate latex with a particle size of 60-150 nm and large-particle-size polyacrylate latex with a particle size of 250-600 nm, wherein the mass ratio of large-particle-size polyacrylate latex to small-particle-size polyacrylate latex is 80-20:20-80; preferably, the small-particle-size polyacrylate latex has a particle size of 60-150 nm and the large-particle-size polyacrylate latex has a particle size of 300-550 nm; more preferably, the small-particle-size polyacrylate latex has a particle size of 80-120 nm and the large-particle-size polyacrylate latex has a particle size of 350-500 nm.

2. The ASA resin according to claim 1, characterized in that, The mass ratio of the acrylate rubber core layer to the styrene-acrylonitrile copolymer shell layer is 30-70:70-30, preferably 35-65:65-35.

3. The ASA resin according to claim 1 or 2, characterized in that, The method for preparing the small-particle-size polyacrylate latex includes the following steps: adding chain transfer agent, activator and water to a reaction vessel, starting stirring, maintaining a nitrogen atmosphere in the reaction vessel, and when the system temperature reaches the reaction temperature of 40-80℃, continuously adding acrylate monomers, emulsifiers, crosslinking agents and initiators dropwise over a period of 0-5 hours. After the addition is complete, the system temperature is raised to 60-90℃ to eliminate residual monomers, so that the conversion rate is greater than 98%.

4. The ASA resin according to claim 3, characterized in that, The method for preparing the small-particle-size polyacrylate latex comprises the following raw materials in parts by weight: 50-200 parts acrylate monomers, 100-500 parts water, 1-5 parts crosslinking agent, 1-8 parts emulsifier, 0-5 parts chain transfer agent, 0.05-1.8 parts activator, and 0.05-1.5 parts initiator; more preferably, 100-150 parts acrylate monomers, 150-350 parts water, 2.5-4.5 parts crosslinking agent, 2-6 parts emulsifier, 1-3 parts chain transfer agent, 0.3-1.5 parts activator, and 0.05-1.0 parts initiator.

5. The ASA resin according to claim 3 or 4, characterized in that, The acrylate monomers are one or more of methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, and isobutyl acrylate; the crosslinking agent is one or more of allyl methacrylate, ethylene glycol methacrylate, diallyl maleate, dicyclopentadienyl acrylate, triallyl urate, 1,4-butanediol dimethacrylate, and triallyl isocyanurate.

6. The ASA resin according to any one of claims 1-5, characterized in that, The method for preparing the large-particle-size polyacrylate latex includes the following steps: 1) Take 100 parts of the small particle size polyacrylate latex according to any one of claims 1-5 and place them in an agglomeration reactor; 2) Add 0.1 to 10 parts of emulsion agglomerating agent to the agglomeration reactor and agglomerate at 20 to 80°C for 30 to 120 minutes to obtain large particle size polyacrylate latex.

7. The ASA resin according to claim 6, characterized in that, The preparation method of the emulsion agglomerator includes the following steps: adding emulsifier, water and activator into a reaction vessel, starting the stirrer, and when the system temperature reaches the reaction temperature, simultaneously adding monomer and initiator solution. After the addition is completed, the system is kept at the temperature for 2 hours to eliminate residual monomer, so that the monomer conversion rate is greater than 98%.

8. The ASA resin according to claim 7, characterized in that, The preparation method of the emulsion agglomerator comprises the following raw materials in parts by weight: 1-10 parts emulsifier, 100-500 parts water, 0.05-1.8 parts activator, 50-200 parts monomer, and 0.05-1.5 parts initiator.

9. The ASA resin according to claim 7 or 8, characterized in that, In the preparation method of the emulsion agglomerator, the monomer is at least one of 1,3-butadiene and acrylate monomers mixed with an α,β-unsaturated acid monomer.

10. A method for preparing the ASA resin according to any one of claims 1-9, comprising the following steps: According to proportion, (1) Add small-particle-size polyacrylate latex, large-particle-size polyacrylate latex, water, emulsifier, and initiator to a reaction vessel and heat to 50-60℃; add dropwise a mixture of styrene and acrylonitrile for 2-4 hours. After the dropwise addition is complete, keep the temperature at 70℃ for 0.5-2 hours. Stop the reaction after the monomers are consumed to obtain a mixed grafted latex of small and large particle sizes. (2) Coagulate the grafted latex, dry it, and obtain a rubber powder with a moisture content of less than 1%; (3) Mix the adhesive powder, SAN resin and additives, melt blend, extrude and then cut into pellets underwater and dry.

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