Preparation method for graft copolymer and use thereof

Abstract

Disclosed in the present invention are a preparation method for a graft copolymer and a use thereof. The preparation method comprises the following steps: in the presence of a graft matrix, performing emulsion polymerization and grafting on a styrene monomer and a vinyl cyanide monomer to obtain a graft copolymer, wherein the grafting process is divided into a monomer addition reaction stage and an aging stage, and a first initiator and a second initiator are added at the monomer addition reaction stage; at least one reducing agent is added in the grafting process to form a redox initiation system with the initiators; and a third initiator is supplemented at the aging stage, the third initiator being a peroxide containing a tert-butyl group. The preparation method of the present invention can achieve a high conversion rate, and an ABS resin prepared from the graft copolymer has relatively good impact performance and relatively low content of residual monomers.

Description

Preparation method of graft copolymer and application thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of high molecular materials, and more particularly to a preparation method of graft copolymer and application thereof. BACKGROUND

[0002] ABS resin is a widely used thermoplastic polymer, which is usually prepared by emulsion graft polymerization. However, the monomers cannot be completely reacted during the polymerization process, resulting in a large amount of residual monomers, high odor and VOC, and thus limiting the application of the product in food packaging, medical supplies, laboratory equipment, toys and other fields.

[0003] The prior art CN106232648A discloses a method for preparing a thermoplastic molding compound with optimal residual monomer content, which controls the mass ratio of styrene and acrylonitrile in the monomer feed at the end of the monomer feeding time to be lower than the cumulative mass ratio during the entire monomer feeding time, so that the oil-soluble styrene monomers are preferentially grafted and polymerized, preventing excessive accumulation of styrene and reducing the residual monomer content. However, the amount of water-soluble acrylonitrile monomers is not reduced, and the degree of conversion is limited under the premise of a certain amount of initiator. If the amount of initiator is increased to improve the conversion rate, the impact performance of the material will be reduced. Therefore, the present application provides a preparation method of graft copolymer and ABS resin, which has a low total residual monomer content, a high conversion rate and good impact performance. SUMMARY

[0004] The purpose of the present application is to overcome the problem that low residual monomer content, high conversion rate and impact performance cannot be achieved simultaneously in the prior art, and to provide a preparation method of graft copolymer, which has a low total residual monomer content, a high conversion rate and good impact performance.

[0005] To achieve the above-mentioned purpose, the present application realizes the following technical scheme:

[0006] A preparation method of graft copolymer, comprising the following steps:

[0007] In the presence of a grafting matrix, styrene monomers and vinyl cyanide monomers are emulsion polymerized to obtain a graft copolymer;

[0008] The grafting process is divided into a monomer feeding reaction stage and an aging stage; the monomer feeding reaction stage adds a first initiator and a second initiator, the first initiator is an oil-soluble initiator, and the second initiator is a water-soluble initiator, the oil-soluble initiator is added in an amount of 0.4-0.7 wt% of the styrene monomer; the water-soluble initiator is added in an amount of 0.1-0.5 wt% of the vinyl cyanide monomer; at least one reducing agent is added in the grafting process to form a redox initiation system with the oil-soluble initiator.

[0009] In the aging stage, a high-efficiency initiator is supplemented, and the third initiator is a peroxide containing a tert-butyl group.

[0010] Preferably, the structure of the third initiator is:

[0011] wherein X is a phenyl group or an alkyl group with a carbon atom number of 4-12.

[0012] Specifically, the alkyl group has a carbon atom number of 4, 5, 6, 7, 8, 9, 10, 11, or 12, etc., all of which can achieve the present application.

[0013] In the preparation method, a water-soluble initiator and an oil-soluble initiator are added to form a redox initiation system in combination with a reducing system, a third initiator is introduced in the aging stage, the low decomposition temperature and activation energy of the third initiator can further reduce the residual monomer content, the thermal initiation in the aging stage and the redox initiation system jointly act, and finally a high conversion rate is achieved, the amount of the initiator is controlled to avoid excessive introduction of the initiator to cause a decrease in impact performance, thereby effectively reducing the residual monomer content, and the prepared graft copolymer has good impact performance when used to prepare an ABS resin.

[0014] Specifically, the third initiator is an oil-soluble initiator.

[0015] Specifically, the self-accelerating decomposition temperature of the peroxide containing a tert-butyl group is 20-60℃. By selecting the peroxide containing a tert-butyl group at this self-accelerating decomposition temperature, the free radicals can be more efficiently decomposed, and the thermal initiation and the peroxide containing a tert-butyl group have a higher initiation effect in cooperation.

[0016] Specifically, the self-accelerating decomposition temperature can be determined according to a heat accumulation storage test.

[0017] Preferably, the third initiator is tert-butyl peroxide; further preferably, one or more of tert-butyl peroxyl benzoate, tert-butyl peroxyl neopentanoate, or tert-butyl peroxyl laurate.

[0018] Preferably, the oil-soluble initiator is added in an amount of 0.5-0.65 wt% of the styrene monomer.

[0019] Preferably, the water-soluble initiator is added in an amount of 0.2-0.4 wt% of the vinyl cyanide monomer.

[0020] Preferably, the third initiator is added in an amount of 0.4-0.8 wt% of the total mass of the styrene monomer and the vinyl cyanide monomer; more preferably, in an amount of 0.5-0.7 wt%.

[0021] Specifically, the total amount of the initiator is not more than 1.4 wt% of the total amount of the monomer, preferably not more than 1.2 wt% of the total amount of the monomer.

[0022] Specifically, the oil-soluble initiator is a peroxide initiator and / or an azo compound initiator. Preferably, the peroxide initiator is one or more of cumene hydroperoxide, benzoyl peroxide, t-butyl benzoyl peroxide or dicumyl peroxide; the azo compound initiator is azobisisobutyronitrile and / or azobisisoheptyl nitrile.

[0023] Specifically, the water-soluble initiator is a persulfate salt; preferably, the persulfate salt is one or more of sodium persulfate, potassium persulfate or ammonium persulfate.

[0024] Preferably, the mass ratio of the grafting matrix to the total mass of the styrene monomer and the vinyl cyanide monomer is 75:25 to 45:55. Preferably, the mass ratio is 70:30 to 40:60; more preferably, the mass ratio is 60:40 to 50:50.

[0025] Specifically, the grafting matrix is a rubber-containing grafting matrix. Preferably, the grafting matrix is a polybutadiene latex.

[0026] In specific embodiments, the average particle size of the grafting matrix is 250-350 nm; preferably, the average particle size of the grafting matrix is 280-320 nm.

[0027] Preferably, the mass ratio of the styrene monomer to the vinyl cyanide monomer is 60:40 to 90:10. More preferably, the mass ratio is 70:30 to 80:20.

[0028] Specifically, the styrene monomer is one or more of styrene, a-methylstyrene or C1-C4 alkylstyrene.

[0029] Specifically, the vinyl cyanide monomer is acrylonitrile and / or methacrylonitrile.

[0030] Specifically, the reducing agent is a divalent iron salt, such as but not limited to ferrous sulfate.

[0031] In some specific embodiments, a reducing system can also be formed by adding a co-reducing agent and a complexing agent, etc.

[0032] Specifically, the reducing agent is a sugar substance, such as, but not limited to, one or more of glucose, lactose, ribose, sorbose, D(+) xylose, cellobiose, D(+) galactose.

[0033] Specifically, the complexing agent can form a complex with iron ions, controlling the release of iron ions, such as, but not limited to, tetrasodium pyrophosphate, sodium diethylenetriaminepentaacetate, etc.

[0034] Specifically, the total amount of the reducing system added is 0.5-1.0 wt% of the dry base of the grafting matrix.

[0035] In some embodiments, a reducing agent and a complexing agent are also added, and the mass ratio of the reducing agent, the reducing agent, and the complexing agent can be 1:(50-70):(20-50).

[0036] Specifically, the monomer feeding reaction stage includes the following steps:

[0037] The styrene monomers and the vinyl cyan monomers and the initiator are continuously added to the at least one grafting matrix, and the first stage polymerization reaction and the second stage polymerization reaction are sequentially performed; or

[0038] Part of the styrene monomers and the vinyl cyan monomers and part of the initiator are added to the at least one grafting matrix at one time, and the first stage polymerization reaction is performed; subsequently, the remaining styrene monomers and the vinyl cyan monomers and the remaining initiator are continuously added for the second stage polymerization reaction.

[0039] Specifically, the first stage polymerization reaction is performed at 70-75°C; and the second stage polymerization reaction is performed at 75-85°C.

[0040] Specifically, the reaction temperature of the aging stage is 80-90°C.

[0041] Specifically, an auxiliary agent can be added in the grafting process according to the prior art. The auxiliary agent is, for example, but not limited to, an emulsifier, a chain transfer agent, etc.

[0042] Specifically, the amount of the emulsifier added is 0-1 wt% of the dry base of the grafting matrix, preferably 0.1-0.8 wt%, and more preferably 0.3-0.7 wt%.

[0043] The amount of the chain transfer agent added is 0-0.5 wt% of the dry base of the grafting matrix, preferably 0.1-0.3 wt%.

[0044] Specifically, the emulsifier is one or more of potassium hydroquinone, potassium oleate, potassium fatty acid, sodium dodecyl sulfonate, or sodium dodecyl benzene sulfonate.

[0045] Specifically, the chain transfer agent is tertiary dodecyl mercaptan and / or n-dodecyl mercaptan.

[0046] In some embodiments, the method for preparing the graft copolymer comprises the following steps:

[0047] Method I:

[0048] a. Water, part of the emulsifier (e.g. 65-75% of the total amount of emulsifier), polybutadiene latex are added into a graft polymerization reactor, stirring is started and the temperature is raised to 60-65℃, a reducing system is added, a mixture of part of styrene monomers (e.g. 15-25% of the total amount of styrene monomers), part of vinyl cyan monomers (e.g. 15-25% of the total amount of vinyl cyan monomers) and part of chain transfer agent (e.g. 30-40% of the total amount of chain transfer agent) is added at one time, part of initiators (e.g. 30-50% of the total amount of oil-soluble initiators and water-soluble initiators) is added, and the reaction is carried out for 50-70 min with a stirring speed of 120-180 rpm, and the temperature is raised to 70-75℃ for the first stage of polymerization;

[0049] b. A mixture of the remaining styrene monomers, vinyl cyan monomers and chain transfer agent is continuously added into the product obtained in the first stage of polymerization, emulsifier and the remaining initiators are added, the temperature is raised to 80-85℃, and the reaction is carried out for 120-180 min with a stirring speed of 120-180 rpm for the second stage of polymerization;

[0050] c. A third initiator is added into the product obtained in the second stage of polymerization, the temperature is raised to 80-90℃, and the reaction is carried out for 40-70 min, and then the graft copolymer is obtained after cooling;

[0051] Method II:

[0052] Water, polybutadiene latex and a reducing system are added into a graft polymerization reactor, stirring is started and the temperature is raised to 60-65℃, a mixture of styrene monomers, vinyl cyan monomers and chain transfer agent, emulsifier and initiators are continuously added, the temperature is raised from 60-65℃ to 70-75℃ within 0-2 h and kept for the first stage of polymerization, then the temperature is raised, the temperature is raised from 70-75℃ to 80-85℃ within 2-4 h and kept for the second stage of polymerization, at this time the monomer feeding is completed, the feeding of initiators and emulsifiers is completed after 30 min, and the stirring speed is 140-180 rpm throughout the process;

[0053] A third initiator is added into the product obtained in the above reaction, the temperature is raised to 80-90℃, and the reaction is carried out for 40-70 min, and then the graft copolymer is obtained after cooling.

[0054] The present application also provides a graft copolymer prepared by the above method.

[0055] The application also provides a graft copolymer high glue powder, which is obtained by coagulation of the graft copolymer.

[0056] In the specific embodiment, the preparation method of the graft copolymer high glue powder comprises the following steps:

[0057] The graft copolymer coagulant and desalted water are added into a gel kettle, and stirred to be heated to 65-80℃. The graft copolymer is added and added completely within 0.5-2h. The temperature is raised to 90-95℃ and maintained for 0.5-2h. After coagulation, the graft copolymer high glue powder is obtained by dehydration and drying.

[0058] Specifically, the coagulant is added in an amount of 0.1-0.5wt% of the graft copolymer.

[0059] Specifically, the desalted water is added in an amount of 100-300wt% of the graft copolymer.

[0060] Specifically, the residual salt content in the desalted water is 1-5mg / L.

[0061] Specifically, the coagulant is a 3-10wt% magnesium sulfate solution.

[0062] The water content of the graft copolymer high glue powder is less than 10wt%, preferably less than 8wt%, and more preferably less than 5wt%.

[0063] The application also provides an ABS resin, which comprises the following components calculated by weight parts:

[0064] Specifically, the weight average molecular weight of the styrene-acrylonitrile copolymer is preferably 85000-250000g / mol, and more preferably 100000-225000g / mol.

[0065] Specifically, the weight average molecular weight is determined by GPC (solvent: tetrahydrofuran, polystyrene as polymer standard) according to DIN55672-1:2016-03 with UV detection.

[0066] In the specific embodiment, the types of polymer components can be selected according to actual needs, and other polymer components include but are not limited to one or more of polycarbonate, polyamide and polyester.

[0067] In the specific embodiment, the other components include but are not limited to one or more of fillers, reinforcing agents, coloring agents, lubricants, release agents, stabilizers, antioxidants, UV absorbers, plasticizers, impact modifiers, antistatic agents, flame retardants, bactericides or foaming agents.

[0068] Specifically, the filler or reinforcing agent includes, but is not limited to, one or several of silicate, amorphous silica, calcium silicate, quartz, mica, metal oxide, metal hydroxide, graphite, barium sulfate, calcium carbonate, magnesium carbonate, talc, kaolin, carbon fiber or glass fiber.

[0069] Specifically, the colorant includes, but is not limited to, one or several of titanium dioxide, phthalocyanine, ultramarine, iron oxide or carbon black.

[0070] Specifically, the stabilizer includes, but is not limited to, one or several of meta-phenylenediphenol, salicylate, benzotriazole or benzophenone.

[0071] Specifically, the release agent includes, but is not limited to, fatty acid having 12 to 30 carbon atoms, salt and derivative thereof, such as stearic acid, stearate, palmitic acid, palmitate, stearyl alcohol, amide wax, polyolefin wax and the like.

[0072] In the present application, a common antioxidant can be selected according to the prior art, such as, but not limited to, one or several of hindered phenol antioxidant, phosphite antioxidant or thioester antioxidant.

[0073] Specifically, the hindered phenol antioxidant is one or several of N,N'-hexamethylene bis(3,5-di-tert-butyl-4-hydroxyphenylpropionamide) (Irganox 1098), tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester (Irganox 1010), 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irganox 259), n-octadecyl β-(4-hydroxy-3,5-di-tert-butylphenyl)propionate (Irganox 1076) or 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)acrylic acid]-1,1-dimethyl}-2,4,8,10-tetraoxaspiro[undecane] (ADK AO-80).

[0074] Specifically, the phosphite antioxidant is pentaerythritol diphosphite distearyl ester (Irgafos 168), 2,4-di-tert-butylphenol and / or bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol phosphite.

[0075] Specifically, the thioester antioxidant is one or several of distearyl thiodipropionate, dilauryl thiodipropionate or dodecylthiopropionate pentaerythritol.

[0076] In the present application, a common lubricant can be selected according to the prior art, such as, but not limited to, at least one of amide lubricant, stearate lubricant, ester lubricant or silicone lubricant.

[0077] The application also provides a preparation method of the ABS resin, comprising the following steps:

[0078] The components are uniformly mixed, and the ABS resin is obtained by extrusion granulation.

[0079] The application also protects the application of the ABS resin in preparing automobile interior materials, food packaging, medical supplies, laboratory equipment and toys.

[0080] Compared with the prior art, the application has the beneficial effects that:

[0081] The application provides a graft copolymer, by mixing a water-soluble initiator and an oil-soluble initiator, combining a reducing agent to form an oxidation-reduction system, combining a thermal initiation system, and introducing a third initiator in the aging stage, the content of residual monomers in the graft copolymer and the ABS resin prepared from the graft copolymer can be effectively reduced, the conversion rate is high, and the impact performance of the prepared ABS resin is good. DETAILED DESCRIPTION

[0082] The application will be further described in combination with the specific embodiments, but the embodiments do not limit the application in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the application are commonly purchased raw materials and reagents.

[0083] The raw materials used in each embodiment and the comparative example are as follows:

[0084] Grafting matrix: polybutadiene latex, the average particle size is 280-320 nm, and the latex-1 in CN116554376A is referred to for preparation;

[0085] Styrene monomer: styrene, the purity is greater than or equal to 99%, commercially available;

[0086] Vinyl cyan monomer: acrylonitrile, the purity is greater than or equal to 99%, commercially available;

[0087] Styrene-acrylonitrile copolymer, PN-128L100, Qimica, Taiwan, China;

[0088] Initiator:

[0089] Water-soluble initiator 1: potassium persulfate, commercially available;

[0090] Water-soluble initiator 2: sodium persulfate, commercially available;

[0091] Oil-soluble initiator 1: cumene hydroperoxide, commercially available;

[0092] Oil-soluble initiator 2: azobis diisobutyronitrile, commercially available;

[0093] Third initiator:

[0094] Third initiator 1: t-butyl peroxybenzoate, self-accelerating decomposition temperature is 35℃, commercially available;

[0095] Third initiator 2: t-butyl peroxylaurate, self-accelerating decomposition temperature is 50℃, commercially available;

[0096] Third initiator 3: t-butyl peroxypivalate, self-accelerating decomposition temperature is 20℃, commercially available;

[0097] Emulsifier: potassium oleate, commercially available;

[0098] Chain transfer agent: t-dodecyl mercaptan, commercially available;

[0099] Reducing agent: ferrous sulfate, commercially available;

[0100] Co-reducing agent: glucose, commercially available;

[0101] Complexing agent: tetrasodium pyrophosphate, commercially available;

[0102] The mass ratio of the reducing agent, co-reducing agent and complexing agent in the reducing system is 1:65:30.

[0103] Other components:

[0104] Antioxidant: mixture of antioxidant 618 and antioxidant 1076 with a mass ratio of 2:1, both commercially available;

[0105] Lubricant: vinyl bis-stearamide, commercially available;

[0106] The same commercially available products are used in the parallel experiments of the examples and comparative examples of the present application.

[0107] Examples 1-6 and comparative examples 1-6

[0108] Examples 1-6 and comparative examples 1-6 provide a graft copolymer, which is prepared according to the formulations in Table 1 by the following method:

[0109] a. Add water, part of the emulsifier (for example, 70% of the total amount of emulsifier), polybutadiene latex into the graft polymerization reactor, start stirring, and add the reducing system when the temperature is raised to 60-65℃, add a mixture of part of styrene (for example, 20% of the total amount of styrene), part of acrylonitrile (for example, 20% of the total amount of acrylonitrile) and part of chain transfer agent (for example, 37.5% of the total amount of chain transfer agent) at one time, add part of the initiator (for example, 40% of the total amount of oil-soluble initiator and water-soluble initiator), and stir for 60 min, the stirring speed is 160 rpm, and the temperature is raised to 70-75℃ during the process, which is the first stage of polymerization;

[0110] b. The remaining styrene, acrylonitrile and chain transfer agent mixture, the remaining emulsifier and the remaining initiator are continuously added to the product obtained in the first stage polymerization reaction, the temperature is raised to 80-85°C, and the reaction is carried out for 150 min at a stirring speed of 160 rpm, which is the second stage polymerization reaction;

[0111] c. The third initiator is added to the product obtained in the second stage polymerization reaction, the temperature is raised to 85-90°C, and the reaction is maintained for 60 min, and then the graft copolymer is obtained after cooling.

[0112] Table 1: Component amounts (unit: parts by weight) in each example and comparative example

[0113] It should be noted that the parts by weight of the polybutadiene latex in the examples are all converted to dry weight parts.

[0114] Example 7

[0115] According to the component amounts in Example 1 in Table 1, water, polybutadiene latex, and the reducing system are added to the graft polymerization reactor, and the stirring is started. When the temperature is raised to 60-65°C, the styrene, acrylonitrile and chain transfer agent mixture, the emulsifier, and the initiator are continuously added, and the timing is started. In 0-2 h, the temperature is raised from 60-65°C to 70-75°C and maintained for the first stage polymerization reaction. Then the temperature is raised, and in 2-4 h, the temperature is raised from 70-75°C to 80-85°C and maintained for the second stage polymerization reaction. At this time, the monomer feeding is completed, and the initiator and emulsifier feeding is completed after 30 min. The stirring speed is 160 rpm throughout the process. The third initiator is added to the above reaction product, the temperature is raised to 85-90°C, and the reaction is maintained for 60 min, and then the graft copolymer is obtained after cooling.

[0116] Examples 8-14 and Comparative Examples 7-12

[0117] The graft copolymer in the above examples and comparative examples is coagulated. 400 parts of a 10 wt% magnesium sulfate solution and 3000 parts of desalted water are added to the coagulation reactor, the stirring is started, and the temperature is raised to 75°C. 3000 parts of the graft copolymer are slowly added, which is completed in 0.5-2 h, and the temperature is raised to 92°C. The timing is started for 20 min after coagulation. The slurry is centrifuged, washed with desalted water for 2 times, and dried at 60°C for 1 h, and then the graft copolymer rubber powder with a water content of less than 1% is obtained.

[0118] The graft copolymer rubber powder, styrene-acrylonitrile copolymer, and additives in the above examples are uniformly mixed according to the amounts in Table 2, and then extruded and granulated to obtain the ABS resin.

[0119] Table 2: Component amounts (unit: parts by weight) in each example and comparative example of the ABS resin

[0120] Performance test

[0121] 1. Graft copolymer performance test:

[0122] (1) Solid content and monomer conversion rate test:

[0123] Take 1.0 ± 0.05 g of the graft copolymer prepared in the examples and comparative examples and evenly spread it in an aluminum dish, then place it horizontally in a forced air oven at 130 ± 5°C for 30 min, take it out and place it in a desiccator to cool to room temperature, weigh it to the nearest 0.1 mg. Then put it back in the forced air oven at 130 ± 5°C for 10 min until the difference between the two consecutive weighings is less than 0.5 mg. The total solid content is calculated according to the following formula:

[0124] Solid content = (m2-m) / (m1-m)*100%;

[0125] Where m is the mass of the aluminum dish, g;

[0126] m1 is the mass of the aluminum dish and the sample before drying, g;

[0127] m2 is the mass of the aluminum dish and the sample after drying, g;

[0128] The conversion rate is calculated according to the solid content, and the formula for calculating the monomer conversion rate is as follows:

[0129] Conversion rate = (solid content * total mass of materials added to the polymerization reactor - total mass of non-volatile additives) / total mass of monomers added to the polymerization reactor * 100%.

[0130] (2) Residual monomer test in graft copolymer

[0131] Gas chromatography, headspace sampling method, sample separation by capillary column, then detected by hydrogen flame ionization detector, and the content of each component was determined by external standard method.

[0132] The analysis conditions are as follows:

[0133] Headspace sampling: HS-10 constant temperature oven 80°C, sample flow path 200°C, transfer line 215°C

[0134] Inlet: temperature 230°C, split ratio 100:1, injection time 1 min, septum purge flow rate 3 mL / min.

[0135] Column oven: initial temperature 60°C, hold time 4.5 min, first order temperature ramp rate 20°C / min, final temperature 85°C, hold time 3 min, second order temperature ramp rate 20°C / min, final temperature 180°C, hold time 3 min

[0136] Front detector FID: temperature 320℃, tail gas N2: 24 ml / min.

[0137] Gas pressure and flow rate: APC1 pressure 260.0 kPa

[0138] Quantitative method: external standard method

[0139] Standard curve: acrylonitrile: 20-150 mg / L; styrene: 10-100 mg / L

[0140] Specific operation and calculation:

[0141] Take 0.1000 g of the sample, accurate to 0.1 mg, in a headspace bottle, add 10 ml of methanol, seal, and place in an ultrasonic instrument for 5 min, and then take out for analysis.

[0142] X: sample content in latex: unit ppm

[0143] C: instrument output: unit mg / L

[0144] m: sample dry basis: unit g.

[0145] The test results are shown in Table 3.

[0146] Table 3 Experimental data of graft copolymer

[0147] As can be seen from Table 3, in the present application, the water-soluble initiator and the oil-soluble initiator are used in combination with the third initiator, and the monomer conversion rate is obviously improved, and the residual monomer content is obviously reduced.

[0148] 2. ABS resin performance test

[0149] (1) Cantilever beam notch impact test: the above-mentioned ABS resin is tested according to GB / T 1843-2008 standard;

[0150] (2) Yellow index: the above-mentioned ABS resin is tested according to HG / T 3862-2006 standard;

[0151] (3) Residual monomer test in ABS resin

[0152] Gas chromatography is used, the headspace method is used, the sample is separated by a capillary column, and then detected by a hydrogen flame ionization detector, and the content of each component is determined according to the internal standard method;

[0153] The analysis conditions are as follows:

[0154] Headspace sampling: HS-10 constant temperature furnace 80℃, sample flow path 210℃, transmission line 215℃

[0155] Injection port: temperature 230 °C, split ratio 100:1, injection time 1 min: septum purge flow rate, 3 ml / min.

[0156] Oven: initial temperature 60 °C, hold time 1 min, first order temperature ramp 5 °C / min, final temperature 80 °C, hold time 0 min, second order temperature ramp 1 °C / min, final temperature 85 °C, hold time 0 min. Third order temperature ramp 5 °C / min, final temperature 100 °C, hold time 0 min, fourth order temperature ramp 40 °C / min, final temperature 225 °C, hold time 5 min.

[0157] Front detector FID: temperature 320 °C, tail gas N2: 24 mL / min.

[0158] Gas pressure and flow rate: APC1 pressure 260.0 kPa

[0159] Quantitative method: external standard method

[0160] Specific operation and calculation:

[0161] Take 0.25 g of the sample, accurate to 0.1 mg, in a headspace bottle, add 10 ml of o-dichlorobenzene (with internal standard), seal, place in a shaker for 7 hours, and take out for analysis.

[0162] X: sample content in latex: unit ppm

[0163] C: instrument output: unit mg / L

[0164] m: sample mass: unit g. The test results are shown in Table 4.

[0165] Table 4 ABS resin experimental data

[0166] As can be seen from Table 4, the graft copolymer prepared by the method of the present application, and the ABS resin prepared therefrom, has a relatively low residual monomer content, and the material has good impact performance. Specifically, the acrylonitrile residual monomer content is not more than 60 ppm, the styrene residual monomer content is not more than 600 ppm, the yellowness index is not more than 18, and the notched impact performance is not less than 16 kJ / m 2 .

[0167] As can be seen from Comparative Examples 1-2 and Comparative Examples 7-8, the graft copolymer prepared by using a single initiator, even with the addition of a reducing agent and a third initiator, has a relatively low conversion rate, and the residual monomer content is significantly higher than that of the examples, and the ABS resin prepared therefrom has poor performance.

[0168] From the comparative example 3 and 9, it can be seen that using other inorganic peroxide instead of the third initiator in the present application cannot well improve the monomer conversion rate, and the residual monomer content is high, and the ABS resin prepared by using it has high residual monomer content.

[0169] From the comparative example 4 and 10, it can be seen that if the reducing system is not added, even if the mixed initiator is used and the third initiator is supplemented, the monomer conversion rate cannot be well improved, and the residual monomer content is high, and the ABS resin prepared by using it has high residual monomer content.

[0170] From the comparative example 5 and 11, it can be seen that using other initiators without tertiary butyl instead of the third initiator in the present application cannot well improve the monomer conversion rate, and the residual monomer content is high, and the ABS resin prepared by using it has high residual monomer content.

[0171] From the comparative example 6 and comparative example 12, it can be seen that increasing the amount of initiator can effectively improve the monomer conversion rate and the residual monomer content, but the impact performance of the ABS resin prepared by using it is obviously decreased.

[0172] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary and also impossible to exhaust all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method for preparing a graft copolymer, characterized in that, Includes the following steps: In the presence of a graft matrix, styrene monomers and vinyl cyanide monomers are emulsion polymerized and grafted to obtain graft copolymers; The grafting process is divided into a monomer feeding reaction stage and an aging stage. In the monomer feeding reaction stage, a first initiator and a second initiator are added. The first initiator is an oil-soluble initiator, and the second initiator is a water-soluble initiator. The amount of the oil-soluble initiator added is 0.4–0.7 wt% of the styrene monomer; the amount of the water-soluble initiator added is 0.1–0.5 wt% of the vinyl cyanide monomer. During the grafting process, at least one reducing agent is added to form a redox initiation system with the oil-soluble initiator. A third initiator is added during the aging stage, the third initiator being a peroxide containing tert-butyl groups.

2. The method for preparing the graft copolymer according to claim 1, characterized in that, The amount of the third initiator added is 0.4 to 0.8 wt% of the total mass of styrene monomer and vinyl cyanide monomer.

3. The method for preparing the graft copolymer according to claim 1, characterized in that, The mass ratio of the grafted matrix to the total mass of styrene monomers and vinyl cyanide monomers is 75:25 to 45:

55.

4. The method for preparing the graft copolymer according to claim 1, characterized in that, The structure of the third initiator is as follows: Wherein X is a phenyl or alkyl group, and the alkyl group has 4 to 12 carbon atoms.

5. The method for preparing the graft copolymer according to claim 1, characterized in that, The third initiator is tert-butyl peroxide.

6. The method for preparing the graft copolymer according to claim 5, characterized in that, The tert-butyl peroxide is one or more of tert-butyl peroxide, tert-butyl perpentyl peroxide, or tert-butyl perlaurate.

7. The method for preparing the graft copolymer according to claim 1, characterized in that, The styrene monomer is one or more of styrene, α-methylstyrene, or C1-C4 alkylstyrene; the vinyl cyanide monomer is acrylonitrile and / or methacrylonitrile; and the grafting matrix is ​​polybutadiene latex.

8. The method for preparing the graft copolymer according to claim 1, characterized in that, The oil-soluble initiator is a peroxide initiator and / or an azo compound initiator.

9. The method for preparing the graft copolymer according to claim 8, characterized in that, The peroxide initiator is one or more of cumene hydroperoxide, benzoyl peroxide, tert-butyl peroxide, or dicumene peroxide; the azo compound initiator is azobisisobutyronitrile and / or azobisisoheptylnitrile.

10. The method for preparing the graft copolymer according to claim 1, characterized in that, The water-soluble initiator is persulfate.

11. The method for preparing the graft copolymer according to claim 10, characterized in that, The persulfate is one or more of sodium persulfate, potassium persulfate, or ammonium persulfate.

12. The method for preparing the graft copolymer according to claim 1, characterized in that, The mass ratio of the styrene monomers to the vinyl cyanide monomers is 60:40 to 90:

10.

13. The method for preparing the graft copolymer according to claim 1, characterized in that, The monomer feeding reaction stage includes the following steps: Styrene monomers and vinyl cyanide monomers, along with an initiator, are continuously added dropwise to at least one graft matrix to carry out a first-stage polymerization reaction and a second-stage polymerization reaction; or A portion of styrene monomers, vinyl cyanide monomers, and a portion of initiator are added to at least one graft matrix at once to carry out the first stage polymerization reaction; subsequently, the remaining styrene monomers, vinyl cyanide monomers, and the remaining initiator are continuously added dropwise to carry out the second stage polymerization reaction.

14. A graft copolymer, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 13.

15. A graft copolymer high-polymer powder, characterized in that, It is obtained by condensation using the graft copolymer described in claim 14.

16. An ABS resin, characterized in that, The ABS resin comprises the following components in parts by weight: 13-35 parts of the graft copolymer high-rubber powder according to claim 15; 65-85 parts of styrene-acrylonitrile copolymer.

17. A method for preparing the ABS resin according to claim 16, comprising the following steps: The above components are mixed evenly and then extruded and granulated to obtain ABS resin.

18. The use of the ABS resin of claim 16 in the preparation of automotive interior materials, food packaging, medical supplies, laboratory equipment, and toys.

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