Core-shell toughening agent as well as preparation method and application thereof

Abstract

The invention discloses a core-shell toughening agent as well as a preparation method and application thereof, and the preparation method of the core-shell toughening agent comprises the following steps: obtaining styrene-butadiene latex with double particle size distribution; grafting: mixing water, an emulsifier, acrylate, methyl methacrylate, a cross-linking agent, an initiator, sodium formaldehyde sulfoxylate and styrene-butadiene latex for first-step grafting, then adding sodium formaldehyde sulfoxylate and a monomer mixture containing the initiator, the cross-linking agent and styrene, and performing second-step grafting to obtain an emulsion; and demulsifying, namely demulsifying the emulsion by adopting inorganic salt to produce sand, and filtering and drying to obtain the core-shell toughening agent. The modified plastic has the advantages of effectively improving the low-temperature impact resistance and yellowing resistance of the plastic when being applied to the plastic, and the like.

Description

Technical Field

[0001] The invention relates to the technical field of rubber, and in particular to a core-shell toughening agent and a preparation method and application thereof. Background Art

[0002] Polycarbonate (PC) is an important engineering polymer with a series of excellent properties such as good electrical insulation, optical transparency, heat resistance and impact strength. It has become an ideal engineering plastic in various fields such as electrical and electronic applications, optical equipment, and construction and aerospace industries. However, the defective characteristics of PC hinder its use in some fields. At low temperatures and after physical aging, the impact strength decreases and the color changes. In order to replace the application of traditional high-density metals in load-bearing fields, reinforced PC composites with high specific strength and specific stiffness have received widespread attention. At present, the common solution to solve the PC defect problem is to add some impact modifiers to enhance the impact resistance of the material while improving the yellowing resistance, and the added additives have minimal effect on the flame retardant properties of the material.

[0003] MBS is a methyl methacrylate-butadiene-styrene polymer, usually obtained by polymerizing butadiene and styrene to obtain styrene-butadiene latex, and then polymerizing styrene-butadiene latex with methyl methacrylate to obtain the polymer. MBS is one of the impact modifiers for plastics, which can improve the low-temperature impact performance of plastic products through extrusion, injection molding and calendering, while improving the yellowing resistance and having the least effect on the flame retardant properties of the material.

[0004] However, when the currently disclosed MBS is added to PC materials, there are still problems such as poor weather resistance, insufficient yellowing resistance and low-temperature impact performance. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is that the currently disclosed MBS still has the defects of insufficient yellowing resistance and low-temperature impact performance when used in plastics, so as to provide a core-shell toughening agent and its preparation method and application to improve the above problems.

[0006] A method for preparing a core-shell toughening agent, comprising:

[0007] Obtaining styrene-butadiene latex with dual particle size distribution;

[0008] Grafting, mixing water, emulsifier, acrylate ester other than methyl methacrylate, methyl methacrylate, crosslinking agent, initiator, bleaching agent and styrene-butadiene latex to perform the first step of grafting, and then adding bleaching agent and a monomer mixture containing initiator, crosslinking agent and styrene to perform the second step of grafting to obtain an emulsion;

[0009] Demulsification and drying, using inorganic salt to demulsify the emulsion to remove sand, and after drying to obtain the core-shell toughening agent. The sand removal in the present invention is the state in which obvious solid particles are formed in the emulsion.

[0010] The acrylic acid ester other than methyl methacrylate includes at least one of butyl acrylate, ethyl acrylate, n-octyl acrylate, isooctyl acrylate and isooctyl methacrylate;

[0011] And / or, the emulsifier includes one or more of potassium oleate, potassium stearate, potassium disproportionated rosin acid, and sodium dodecyl diphenyl ether disulfonate;

[0012] And / or, the cross-linking agent includes one or more of 1,2-diallyl phthalate (CAS131-17-9), ethylene glycol dimethacrylate (CAS 97-90-5), 1,4-butanediol dimethacrylate (CAS 15181-86-9), and divinylbenzene (CAS1321-74-0);

[0013] And / or, the initiator includes one or more of potassium persulfate, sodium persulfate, ammonium persulfate or cumene hydroperoxide;

[0014] And / or, the inorganic salt includes one or more of calcium chloride, sodium chloride, potassium chloride, and potassium carbonate.

[0015] In the first grafting step, the mass ratio of acrylic acid esters other than methyl methacrylate, methyl methacrylate and styrene-butadiene latex is (5-30): (5-30): (180-200); further, based on 180-200 parts by weight of styrene-butadiene latex, the amount of water added in this step is 200-300 parts, and / or the amount of emulsifier added is 0.1-0.7 parts, and / or the amount of cross-linking agent added is 0.1-0.8 parts, and / or the amount of initiator added is 0.08-0.4 parts, and / or the amount of bleaching agent added is 0.01-1 parts;

[0016] And / or, in the second grafting step, the mass ratio of styrene to styrene-butadiene latex is (5-10): (180-200); further, the amount of bleaching agent added in this step is 0.01-1 part based on 180-200 parts by weight of styrene-butadiene latex;

[0017] And / or, the mass ratio of the initiator, the crosslinking agent and the styrene in the monomer mixture is (0.5-2): (0.5-2): (30-50).

[0018] Specifically, in the grafting step, when grafting acrylates other than methyl methacrylate and methyl methacrylate, the heating temperature is 40-60°C, the stirring speed is 150-200rpm, and the reaction is continued for 3-4h after the raw materials are completely mixed in the first grafting step; when grafting styrene, the heating temperature is 40-60°C, and the stirring speed is 150-200rpm.

[0019] In the demulsification step, an aqueous solution of inorganic salt is used for demulsification and sand removal. The mass concentration of the inorganic salt in the aqueous solution is 5%-10%. The heating temperature for demulsification and sand removal is 50-70° C. and the stirring speed is 150-250 rpm.

[0020] The process of obtaining the styrene-butadiene latex with dual particle size distribution comprises:

[0021] The seed latex is obtained by mixing water, an emulsifier, an inorganic salt, a molecular weight regulator, an initiator, a part of butadiene and a part of styrene to perform a low temperature polymerization reaction;

[0022] The seed latex is mixed with the remaining styrene, water, emulsifier, inorganic salt, molecular weight regulator, initiator, crosslinking agent and molecular weight regulator, and then polymerized with the remaining butadiene at high temperature to obtain styrene-butadiene latex with dual particle size distribution.

[0023] The preparation process of styrene butadiene latex is a very mature process in this field, and the preparation process of styrene butadiene latex with dual particle size distribution is also disclosed in the prior art. The styrene butadiene latex with dual particle size distribution in the present invention can be prepared by the existing preparation process or by the optimized preparation process, as long as the combination of two particle size distributions can be achieved. As a preferred setting, in the styrene butadiene latex with dual particle size distribution, the small particle size latex is preferably distributed between 30-100nm, and the large particle size latex is preferably distributed between 100-300nm.

[0024] The reaction temperature of the low-temperature polymerization reaction is 10-20°C, the reaction pressure is 0.01-0.5MPa, and the reaction time is 12-24 hours;

[0025] And / or, the reaction temperature of the high temperature polymerization is 40-60° C. and the reaction time is 2-5 hours;

[0026] And / or, after the high temperature polymerization, the step of adding an agglomerating agent to carry out high temperature agglomeration is further included, and after the high temperature agglomeration is completed, an inorganic salt is added to terminate the agglomeration; the reaction temperature of the high temperature agglomeration reaction is 40-60°C.

[0027] The agglomerating agent is one or more of acetic acid or sulfate, and the sulfate is preferably one or more of sodium sulfate, magnesium sulfate, and potassium sulfate;

[0028] And / or, the molecular weight regulator includes one or more of dodecyl mercaptan, n-octyl mercaptan, and tert-dodecyl mercaptan.

[0029] The raw materials of the styrene-butadiene latex include 220-330 parts of water, 60-100 parts of butadiene and 0-40 parts of styrene.

[0030] In the low-temperature polymerization step, based on the weight of 200-300 parts of water, the amount of emulsifier added in this step is 0.2-3 parts, and / or the amount of initiator added is 0.08-0.4 parts, and / or the amount of molecular weight regulator added is 0.01-0.3 parts, and / or the amount of inorganic salt added is 0.2-1 parts, and / or the amount of butadiene added is 40-50% of the total amount of butadiene in the raw material of styrene-butadiene latex, and / or the amount of styrene added is 45%-55% of the total amount of styrene in the raw material of styrene-butadiene latex;

[0031] In the high temperature polymerization step, based on the weight parts of 60-100 parts of the total amount of butadiene in the raw material of styrene-butadiene latex, the amount of water added in this step is 20-30 parts, and / or the amount of emulsifier added is 0.2-3 parts, and / or the amount of initiator added is 0.08-0.4 parts, and / or the amount of molecular weight regulator added is 0.01-0.3 parts, and / or the amount of inorganic salt added is 0.2-1 parts, and / or the amount of crosslinking agent added is 0.1-0.8 parts, and the amount of agglomerating agent added is 0.5-1 parts.

[0032] A core-shell toughening agent is prepared by the above-mentioned preparation method.

[0033] An application of the core-shell toughening agent in improving the low-temperature impact resistance and / or yellowing resistance of plastics.

[0034] The plastic is PC.

[0035] The components of the PC of the present invention include, by weight, 80-100 parts of polycarbonate, 1-10 parts of core-shell toughening agent, 0.2-1 part of flame retardant, 0.1-0.5 part of ultraviolet absorber, 0.1-0.5 part of light stabilizer, 0.1-0.5 part of antioxidant and 0.1-0.5 part of lubricant.

[0036] Among them, the polycarbonate is preferably the general-purpose powder 2100 sold by Wanhua. The flame retardant is preferably BDP. The ultraviolet absorber is preferably one or more of UV9, UV327, and UV531. The light stabilizer is preferably one or a mixture of light stabilizer 788, light stabilizer 5589, and light stabilizer V703. The antioxidant is preferably at least one of 1010, 1076, and 168, and more preferably a composite antioxidant, that is, at least two of 1010, 1076, and 168. The lubricant is preferably sodium stearate.

[0037] The preparation method of the PC in the present invention is: according to the raw material ratio, the components are mixed evenly, and extruded through a twin-screw extruder, the temperature range of the extruder is 280-310°C, and after extrusion, PC with excellent low-temperature impact resistance and yellowing resistance is obtained.

[0038] The technical solution of the present invention has the following advantages:

[0039] The invention provides a method for preparing a core-shell toughening agent, which provides styrene-butadiene latex with a double particle size distribution as a core, introduces acrylates other than methyl methacrylate as a fourth monomer into MBS resin, and adopts a two-step grafting scheme combination to prepare a shell layer to obtain a core-shell toughened structure; the method of the invention is based on the core-shell toughening agent obtained by the above optimization, and when it is applied to plastics, especially PC materials, the low-temperature impact resistance and yellowing resistance of the plastic can be effectively improved; specifically, styrene-butadiene latex with a double particle size distribution is used, large-size particles can provide good impact resistance, small-size particles can provide good dispersibility and resin compatibility, the introduction of acrylates other than methyl methacrylate can improve UV aging performance, and the shell layer prepared by two-step grafting can improve low-temperature impact performance; large-size particles and small-size particles are combined with each other, and acrylates other than methyl methacrylate, a fourth grafting monomer, are introduced, and the shell layers prepared by two-step grafting cooperate with each other. It has been verified that after applying it to plastics, the low-temperature impact resistance and yellowing resistance of the plastic can be effectively synergistically improved. DETAILED DESCRIPTION

[0040] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0041] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0042] Example 1

[0043] A method for preparing a core-shell toughening agent, comprising:

[0044] (1) Preparation of styrene-butadiene latex

[0045] Add 200 parts of deionized water, 0.7 parts of sodium dodecyl diphenyl ether disulfonate, 0.1 parts of sodium persulfate, 0.09 parts of dodecyl mercaptan, 0.5 parts of potassium disproportionate rosin acid, 0.3 parts of calcium chloride, and 20 parts of styrene into a clean reactor, stir and mix, first purge with nitrogen, then evacuate to 0.1 MPa, and then press in 45 parts of butadiene. Start stirring and control the temperature to 15°C. When the pressure in the reactor is lower than 0.07 MPa, the seed latex is prepared. Subsequently, 25 parts of deionized water, 0.7 parts of sodium dodecyl diphenyl ether disulfonate, 0.09 parts of dodecyl mercaptan, 0.5 parts of potassium disproportionate rosin acid, 0.1 parts of sodium persulfate, and 0.3 parts of calcium chloride were added to another reaction kettle, and then the seed latex prepared before, 20 parts of styrene, and 0.2 parts of 1,4-butanediol diacrylate were added. The reaction kettle was purged with nitrogen and then vacuumized to 0.1 MPa. 50 parts of butadiene were pressed into the reaction kettle, and stirring was started and the temperature was raised to 55° C. The reaction kettle was reacted for 5 hours, and high-temperature polymerization was performed to obtain a styrene-butadiene latex with a relatively small particle size and a double particle size distribution; 20 parts of acetic acid with a concentration of 5% (mass fraction) were added and dripped into the styrene-butadiene latex with a relatively small particle size and a double particle size distribution, and the dripping time was 6 minutes and the agglomeration temperature was 45° C. After the dripping was completed, 14 parts of a potassium hydroxide solution with a concentration of 10% (mass fraction) were added to terminate the agglomeration to obtain a styrene-butadiene latex with a relatively large particle size and a double particle size distribution. In the above-mentioned styrene-butadiene latex with relatively large double particle size distribution, the small particle size latex in the double particle size is distributed between 40-100nm, accounting for about 20%, and the large particle size latex is distributed between 150-300nm, accounting for about 80%.

[0046] (2) Grafting monomer

[0047] Add 180 parts of styrene-butadiene latex and 200 parts of deionized water to a clean reactor, replace the environment with nitrogen, start stirring, stir at 200 rpm, heat to 60°C, first add 0.05 parts of bleaching powder, then add 0.2 parts of potassium disproportionate rosin acid, 10 parts of butyl acrylate, 10 parts of methyl methacrylate, 0.2 parts of diacrylate-1,4-butanediol ester, and 0.1 parts of sodium persulfate to the reactor, start the first grafting, and after 4 hours of reaction, start the second grafting. In the second grafting, first add 0.05 parts of bleaching powder, and then drop 10 parts of a mixture of initiator, crosslinker and styrene. The ratio of initiator, crosslinker and styrene in the mixture is 1:1:40. The initiator is sodium persulfate and the crosslinker is 1,2-diallyl phthalate. Stop the reaction after 4 hours of reaction.

[0048] (3) Demulsification and drying

[0049] Slowly add 20 parts of 8% calcium chloride solution to the emulsion, heat it to 50°C, stir it at 250rpm, break the emulsion, and after obvious sanding is observed in the emulsion, stop adding, turn off stirring and heating, and use a forced air drying oven to dry for 4 days at 50°C to obtain a core-shell toughening agent.

[0050] Example 2

[0051] The difference from Example 1 is that the grafted butyl acrylate is changed to methyl acrylate.

[0052] Example 3

[0053] The difference from Example 1 is that the grafted butyl acrylate is changed to ethyl acrylate.

[0054] Example 4

[0055] The difference from Example 1 is that the grafted butyl acrylate is replaced by n-octyl acrylate.

[0056] Example 5

[0057] The difference from Example 1 is that the grafted butyl acrylate is replaced by isooctyl acrylate.

[0058] Example 6

[0059] This embodiment differs from Embodiment 1 in that there is no agglomeration process in the step of preparing styrene-butadiene latex, and the rest is the same as Embodiment 1.

[0060] Add 200 parts of deionized water, 0.7 parts of sodium dodecyl diphenyl ether disulfonate, 0.1 parts of sodium persulfate, 0.09 parts of dodecyl mercaptan, 0.5 parts of potassium disproportionate rosin acid, 0.3 parts of calcium chloride, and 20 parts of styrene into a clean reactor, stir and mix, first purge with nitrogen, then evacuate to 0.1 MPa, and then press in 45 parts of butadiene. Start stirring and control the temperature to 15°C. When the pressure in the reactor is lower than 0.07 MPa, the seed latex is prepared. Subsequently, 25 parts of deionized water, 0.7 parts of sodium dodecyl diphenyl ether disulfonate, 0.09 parts of dodecyl mercaptan, 0.5 parts of potassium disproportionate rosin acid, 0.1 parts of sodium persulfate, 0.3 parts of calcium chloride were added to another reactor, and the seed latex prepared before was added, 20 parts of styrene, 0.2 parts of diacrylate-1,4-butanediol ester, and evacuated to 0.1MPa after nitrogen purge, 50 parts of butadiene were pressed into, stirring was turned on and the temperature was raised to 55°C, and the reaction was performed for 5 hours, and high temperature polymerization was performed to obtain a styrene-butadiene latex with a relatively small double particle size distribution. The styrene-butadiene latex with a relatively small double particle size distribution obtained in the present embodiment, the small particle size latex in the double particle size is distributed between 30-70nm, accounting for about 20%, and the large particle size latex is distributed between 100-200nm, accounting for about 80%.

[0061] Example 7

[0062] The difference between this embodiment and embodiment 1 is that the types and amounts of raw materials in each step are different.

[0063] Specifically, a method for preparing a core-shell toughening agent comprises:

[0064] (1) Preparation of styrene-butadiene latex

[0065] Add 250 parts of deionized water, 2.5 parts of potassium stearate, 0.4 parts of potassium persulfate, 0.3 parts of n-octyl mercaptan, 0.5 parts of sodium dodecyl diphenyl ether disulfonate, 0.5 parts of sodium chloride, and 2 parts of styrene into a clean reactor, stir and mix, first purge with nitrogen, then evacuate to 0.1 MPa, and then press in 30 parts of butadiene. Start stirring and control the temperature to 10°C. When the pressure in the reactor is lower than 0.07 MPa, the seed latex is prepared. Subsequently, 20 parts of deionized water, 0.1 parts of sodium dodecyl diphenyl ether disulfonate, 0.01 parts of dodecyl mercaptan, 0.1 parts of potassium disproportionate rosin acid, 0.2 parts of sodium persulfate, and 1 part of calcium chloride were added to another reaction kettle, and then the seed latex prepared previously, 2 parts of styrene, and 0.5 parts of 1,4-butanediol diacrylate were added. The reaction kettle was first purged with nitrogen and then evacuated to 0.1 MPa. 30 parts of butadiene were pressed in. Stirring was started and the temperature was raised to 40°C. The reaction was carried out for 5 hours. Then, 10 parts of acetic acid with a concentration of 5% (mass fraction) were added and dripped into the latex respectively. The dripping time was 6 minutes and the agglomeration temperature was 50°C. After the dripping was completed, 10 parts of potassium hydroxide solution with a concentration of 10% (mass fraction) were added to terminate the agglomeration to obtain styrene-butadiene latex with a double particle size distribution.

[0066] (2) Grafting monomer

[0067] Add 190 parts of styrene-butadiene latex and 250 parts of deionized water to a clean reactor, replace the environment with nitrogen, start stirring, stir at 150rpm, heat to 40°C, first add 0.01 parts of bleaching powder to the reactor, then add 0.1 parts of potassium disproportionate rosin acid, 5 parts of butyl acrylate, 5 parts of methyl methacrylate, 0.5 parts of diacrylate-1,4-butanediol ester, and 0.4 parts of ammonium persulfate, start the first grafting, and after 3 hours of reaction, start the second grafting. In the second grafting, first add 0.01 parts of bleaching powder, and drop 6 parts of a mixture of initiator, crosslinker and styrene. The ratio of initiator, crosslinker and styrene in the mixture is 0.5:2:30. The initiator is ammonium persulfate and the crosslinker is 1,2-diallyl phthalate. Stop the reaction after 4 hours of reaction.

[0068] (3) Demulsification and drying

[0069] Slowly add 20 parts of 5% calcium chloride solution to the emulsion, heat it to 50°C, stir it at 150rpm, break the emulsion, and after obvious sanding is observed in the emulsion, stop adding, turn off stirring and heating, and use a forced air drying oven to dry for 4 days at 50°C to obtain a core-shell toughening agent.

[0070] Example 8

[0071] The difference between this embodiment and embodiment 1 is that the types and amounts of raw materials in each step are different.

[0072] Specifically, a method for preparing a core-shell toughening agent comprises:

[0073] (1) Preparation of styrene-butadiene latex

[0074] Add 300 parts of deionized water, 0.1 parts of sodium dodecyl diphenyl ether disulfonate, 0.2 parts of cumene hydroperoxide, 0.01 parts of dodecyl mercaptan, 0.1 parts of potassium disproportionate rosin acid, 1 part of calcium chloride, and 15 parts of styrene into a clean reactor, stir and mix, first purge with nitrogen, then evacuate to 0.1 MPa, and then press in 40 parts of butadiene. Start stirring and control the temperature to 20°C. When the pressure in the reactor is lower than 0.07 MPa, the seed latex is prepared. Subsequently, 30 parts of deionized water, 1.5 parts of sodium dodecyl diphenyl ether disulfonate, 0.3 parts of tert-dodecyl mercaptan, 1.5 parts of potassium stearate, 0.4 parts of isopropylbenzene hydroperoxide, and 0.5 parts of potassium carbonate were added to another reaction kettle, and then the seed latex prepared previously, 15 parts of styrene, and 0.8 parts of 1,4-butanediol diacrylate were added. The reaction was first purged with nitrogen and then evacuated to 0.1 MPa. 40 parts of butadiene were pressed in. Stirring was started and the temperature was raised to 60°C. The reaction was carried out for 2 hours. Then, 15 parts of acetic acid with a concentration of 5% (mass fraction) were added and dripped into the latex respectively. The dripping time was 6 minutes and the agglomeration temperature was 55°C. After the dripping was completed, 8 parts of potassium hydroxide solution with a concentration of 10% (mass fraction) were added to terminate the agglomeration to obtain styrene-butadiene latex with a double particle size distribution.

[0075] (2) Grafting monomer

[0076] Add 200 parts of styrene-butadiene latex and 300 parts of deionized water to a clean reactor, replace the environment with nitrogen, start stirring, stir at 200 rpm, heat to 50°C, first add 1 part of bleaching block to the reactor, then add 0.7 parts of potassium disproportionate rosin acid, 30 parts of butyl acrylate, 30 parts of methyl methacrylate, 0.8 parts of diacrylate-1,4-butanediol ester, and 0.2 parts of potassium persulfate, start the first grafting, and after 4 hours of reaction, start the second grafting. In the second grafting, first add 1 part of bleaching block, and drop 8 parts of a mixture of initiator, crosslinker and styrene. The ratio of initiator, crosslinker and styrene in the mixture is 2:0.5:50. The initiator is ammonium persulfate and the crosslinker is 1,2-diallyl phthalate. Stop the reaction after 4 hours of reaction.

[0077] (3) Demulsification and drying

[0078] Slowly add 20 parts of 10% potassium chloride solution to the emulsion, heat it to 50°C, stir it at 200rpm, break the emulsion, and after obvious sanding is observed in the emulsion, stop adding, turn off stirring and heating, and use a forced air drying oven to dry for 4 days at 50°C to obtain a core-shell toughening agent.

[0079] Comparative Example 1

[0080] The difference between this comparative example and Example 1 is that the styrene-butadiene latex is a styrene-butadiene latex with a single particle size distribution. Specifically, a method for preparing a core-shell toughening agent comprises:

[0081] (1) Preparation of styrene-butadiene latex

[0082] Add 200 parts of deionized water, 0.7 parts of sodium dodecyl diphenyl ether disulfonate, 0.1 parts of sodium persulfate, 0.09 parts of dodecyl mercaptan, 0.5 parts of potassium disproportionate rosin acid, 0.3 parts of calcium chloride, 40 parts of styrene in the clean reactor, stir and mix, first purge with nitrogen, then evacuate to 0.1MPa, and then press into 95 parts of butadiene. Turn on stirring and temperature control to 15 ℃, when the pressure in the kettle is lower than 0.07MPa, the seed latex preparation is complete. Add 20 parts of acetic acid with a concentration of 5% (mass fraction) and drip into the small-particle size styrene butadiene latex respectively, the dropping time is 6min, and the agglomeration temperature is 45 ℃. After the dropwise addition ends, add 14 parts of potassium hydroxide solution with a concentration of 10% (mass fraction) to terminate the agglomeration and obtain styrene butadiene latex. The styrene butadiene latex obtained in the present embodiment is the styrene butadiene latex distributed by single particle size, and the particle size is between 50-150nm.

[0083] (2) Grafting monomer

[0084] Add 180 parts of styrene-butadiene latex and 200 parts of deionized water to a clean reactor, replace the environment with nitrogen, start stirring, and heat to 60°C. First, add 0.05 parts of bleaching powder, then add 0.2 parts of potassium disproportionate rosin acid, 10 parts of butyl acrylate, 10 parts of methyl methacrylate, 0.2 parts of diacrylate-1,4-butanediol ester, 0.1 parts of sodium persulfate, and 200 parts of deionized water to the reactor. The first step of grafting begins. After 4 hours of reaction, the second step of grafting begins. In the second step of grafting, first add 0.05 parts of bleaching powder, and then drop 10 parts of a mixture of initiator, crosslinker and styrene. The ratio of initiator, crosslinker and styrene in the mixture is 1:1:40. The initiator is sodium persulfate and the crosslinker is 1,2-diallyl phthalate. The reaction is stopped after 4 hours of reaction.

[0085] (3) Demulsification and drying

[0086] Slowly add 20 parts of 8% calcium chloride solution to the emulsion, heat it to 50°C, stir it at 250rpm, break the emulsion, and after obvious sanding is observed in the emulsion, stop adding, turn off stirring and heating, and use a forced air drying oven to dry for 4 days at 50°C to obtain a core-shell toughening agent.

[0087] Comparative Example 2

[0088] The difference between this comparative example and Example 1 is that the styrene-butadiene latex is a styrene-butadiene latex with a single particle size distribution. Specifically, a method for preparing a core-shell toughening agent comprises:

[0089] (1) Preparation of styrene-butadiene latex

[0090] Add 200 parts of deionized water, 0.7 parts of sodium dodecyl diphenyl ether disulfonate, 0.1 parts of sodium persulfate, 0.09 parts of dodecyl mercaptan, 0.5 parts of potassium disproportionate rosin acid, 0.3 parts of calcium chloride, 40 parts of styrene in the clean reactor, stir and mix, first purge with nitrogen, then evacuate to 0.1MPa, and then press into 95 parts of butadiene. Turn on stirring and warm up to 60 ℃, when the pressure in the kettle is lower than 0.07MPa, the seed latex preparation is complete. Add 20 parts of acetic acid with a concentration of 5% (mass fraction) and drip into the small-particle size styrene butadiene latex respectively, the dropping time is 6min, and the agglomeration temperature is 45 ℃. After the dropping ends, add 14 parts of potassium hydroxide solution with a concentration of 10% (mass fraction) to terminate the agglomeration and obtain styrene butadiene latex. The styrene butadiene latex obtained in the present embodiment is the styrene butadiene latex distributed with a single particle size, and the particle size is between 150-300nm.

[0091] (2) Grafting monomer

[0092] Add 180 parts of styrene-butadiene latex and 200 parts of deionized water to a clean reactor, replace the environment with nitrogen, start stirring, and heat to 60°C. First, add 0.05 parts of bleaching powder, then add 0.2 parts of potassium disproportionate rosin acid, 10 parts of butyl acrylate, 10 parts of methyl methacrylate, 0.2 parts of diacrylate-1,4-butanediol ester, 0.1 parts of sodium persulfate, and 200 parts of deionized water to the reactor. The first step of grafting begins. After 4 hours of reaction, the second step of grafting begins. In the second step of grafting, first add 0.05 parts of bleaching powder, and then drop 10 parts of a mixture of initiator, crosslinker and styrene. The ratio of initiator, crosslinker and styrene in the mixture is 1:1:40. The initiator is sodium persulfate and the crosslinker is 1,2-diallyl phthalate. The reaction is stopped after 4 hours of reaction.

[0093] (3) Demulsification and drying

[0094] Slowly add 20 parts of 8% calcium chloride solution to the emulsion, heat it to 50 degrees Celsius, stir it at 250 rpm, break the emulsion, and stop adding after obvious sanding is observed in the emulsion. Turn off stirring and heating, and use a forced air drying oven to dry for 4 days at a drying temperature of 50°C to obtain a core-shell toughening agent.

[0095] Comparative Example 3

[0096] This comparative example differs from Example 1 in that no butyl acrylate is added.

[0097] Comparative Example 4

[0098] The difference between this comparative example and Example 1 is that a one-step grafting reaction is used in the step of grafting monomers, and the other steps are exactly the same as those in Example 1. The specific steps of grafting monomers are as follows:

[0099] Add 180 parts of styrene-butadiene latex and 200 parts of deionized water to a clean reactor, replace the environment with nitrogen, start stirring, and heat to 60°C. First, add 0.1 parts of bleaching powder to the reactor, then add 0.2 parts of potassium disproportionate rosin acid, 10 parts of butyl acrylate, 10 parts of methyl methacrylate, 0.2 parts of 1,4-butanediol diacrylate, 0.1 parts of sodium persulfate, 200 parts of deionized water, and 10 parts of a mixture of initiator, crosslinker and styrene, the ratio of initiator, crosslinker and styrene in the mixture is 1:1:40, carry out a one-step grafting reaction, and stop the reaction after 8 hours.

[0100] The toughening agent prepared in the embodiments of the present invention and the comparative example was added to PC to prepare a PC composite material, wherein the raw materials of the PC composite material included, by weight: 95 parts of polycarbonate, 2 parts of toughening agent, 0.3 parts of flame retardant, 0.1 parts of ultraviolet absorber, 0.2 parts of light stabilizer, 0.4 parts of antioxidant, and 0.2 parts of lubricant; wherein the flame retardant was BDP, the polycarbonate was the general-purpose powder 2100 sold by Wanhua, the ultraviolet absorber was UV327, the light stabilizer was light stabilizer 5589, the lubricant was sodium stearate, and the composite antioxidant was a 1:1 mixture of 1076 and 168.

[0101] The preparation method of the PC composite material is as follows: according to the raw material ratio, the components are mixed uniformly, and extruded through a twin-screw extruder, and the temperature range of the extruder is 280°C.

[0102] At the same time, a PC composite material of the comparison group was added, which included: 95 parts of polycarbonate, 1.7 parts of the toughening agent of Comparative Example 1, 0.3 parts of flame retardant, 0.1 parts of ultraviolet absorber, 0.2 parts of light stabilizer, 0.4 parts of antioxidant, 0.2 parts of lubricant, and 0.3 parts of butyl acrylate.

[0103] The following performance tests were performed on the PC materials obtained by using the toughening agents prepared in the above examples and comparative examples and the PC composite materials of the comparative group.

[0104] UL-94 combustion grade test: tested according to ASTM D625-1977, the thickness of the flame retardant specimen is 3.2mm;

[0105] Izod notched impact strength test: tested according to ASTM D256;

[0106] Surface color difference test: obtained in a UV aging box (0.76W, UVb, 4h illumination, 4h condensation for one week) according to ASTM E313.

[0107] The test results are shown in Table 1 below.

[0108] Table 1

[0109]

[0110] According to the data in Table 1 above, the core-shell toughening agent prepared by adding acrylates other than methyl methacrylate and combining with dual particle size distribution and two grafting can synergistically optimize and improve UV aging performance (yellowing resistance) and low-temperature impact performance when applied to plastics; at the same time, after agglomeration, the styrene-butadiene latex in the present invention can increase the latex particle size, further improve UV aging performance and enhance impact resistance.

[0111] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for preparing a core-shell toughening agent, characterized in that: include: Obtaining styrene-butadiene latex with dual particle size distribution; Grafting, mixing water, emulsifier, acrylate ester other than methyl methacrylate, methyl methacrylate, crosslinking agent, initiator, bleaching agent and styrene-butadiene latex to perform the first step of grafting, and then adding bleaching agent and a monomer mixture containing initiator, crosslinking agent and styrene to perform the second step of grafting to obtain an emulsion; Demulsification and drying: using inorganic salt to demulsify and sand the emulsion, and after drying, the core-shell toughening agent is obtained.

2. The preparation method according to claim 1, characterized in that: The acrylic acid ester other than methyl methacrylate includes at least one of butyl acrylate, ethyl acrylate, n-octyl acrylate, isooctyl acrylate and isooctyl methacrylate; And / or, the emulsifier includes one or more of potassium oleate, potassium stearate, potassium disproportionated rosin acid, and sodium dodecyl diphenyl ether disulfonate; And / or, the cross-linking agent includes one or more of 1,2-diallyl phthalate, ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, and divinylbenzene; And / or, the initiator includes one or more of potassium persulfate, sodium persulfate, ammonium persulfate or cumene hydroperoxide; And / or, the inorganic salt includes one or more of calcium chloride, sodium chloride, potassium chloride, and potassium carbonate.

3. The preparation method according to claim 1, characterized in that: In the first grafting step, the mass ratio of acrylic acid esters other than methyl methacrylate, methyl methacrylate and styrene-butadiene latex is (5-30): (5-30): (180-200); based on 180-200 parts by weight of styrene-butadiene latex, the amount of water added in the first grafting step is 200-300 parts, and / or the amount of emulsifier added is 0.1-0.7 parts, and / or the amount of cross-linking agent added is 0.1-0.8 parts, and / or the amount of initiator added is 0.08-0.4 parts, and / or the amount of bleaching agent added is 0.01-1 parts; And / or, in the second grafting step, the mass ratio of styrene to styrene-butadiene latex is (5-10): (180-200); based on 180-200 parts by weight of styrene-butadiene latex, the amount of bleaching agent added in the second grafting step is 0.01-1 part; And / or, the mass ratio of the initiator, the crosslinking agent and the styrene in the monomer mixture is (0.5-2): (0.5-2): (30-50).

4. The preparation method according to any one of claims 1 to 3, characterized in that: The process of obtaining the styrene-butadiene latex with dual particle size distribution comprises: The seed latex is obtained by mixing water, an emulsifier, an inorganic salt, a molecular weight regulator, an initiator, a part of butadiene and a part of styrene to perform a low temperature polymerization reaction; The seed latex is mixed with the remaining styrene, water, emulsifier, inorganic salt, molecular weight regulator, initiator, crosslinking agent and molecular weight regulator, and then polymerized with the remaining butadiene at high temperature to obtain styrene-butadiene latex with dual particle size distribution.

5. The preparation method according to claim 4, characterized in that: The reaction temperature of the low-temperature polymerization reaction is 10-20°C, the reaction pressure is 0.01-0.5MPa, and the reaction time is 12-24 hours; And / or, the reaction temperature of the high temperature polymerization is 40-60° C. and the reaction time is 2-5 hours; And / or, after the high temperature polymerization, the step of adding an agglomerating agent to carry out high temperature agglomeration is further included, and after the high temperature agglomeration is completed, an inorganic salt is added to terminate the agglomeration; the reaction temperature of the high temperature agglomeration reaction is 40-60°C.

6. The preparation method according to claim 5, characterized in that: The agglomerating agent is one or more of acetic acid or sulfate, and the sulfate is preferably one or more of sodium sulfate, magnesium sulfate, and potassium sulfate; And / or, the molecular weight regulator includes one or more of dodecyl mercaptan, n-octyl mercaptan, and tert-dodecyl mercaptan.

7. The preparation method according to claim 4, characterized in that: The raw materials of the styrene-butadiene latex include, by weight, 220-330 parts of water, 60-100 parts of butadiene, and 0-40 parts of styrene; In the low-temperature polymerization step, based on the weight of 200-300 parts of water, the amount of emulsifier added in this step is 0.2-3 parts, and / or the amount of initiator added is 0.08-0.4 parts, and / or the amount of molecular weight regulator added is 0.01-0.3 parts, and / or the amount of inorganic salt added is 0.2-1 parts, and / or the amount of butadiene added is 40-50% of the total amount of butadiene in the raw material of styrene-butadiene latex, and / or the amount of styrene added is 45%-55% of the total amount of styrene in the raw material of styrene-butadiene latex; In the high temperature polymerization step, based on the weight parts of 60-100 parts of the total amount of butadiene in the raw material of styrene-butadiene latex, the amount of water added in this step is 20-30 parts, and / or the amount of emulsifier added is 0.2-3 parts, and / or the amount of initiator added is 0.08-0.4 parts, and / or the amount of molecular weight regulator added is 0.01-0.3 parts, and / or the amount of inorganic salt added is 0.2-1 parts, and / or the amount of crosslinking agent added is 0.1-0.8 parts, and the amount of agglomerating agent added is 0.5-1 parts.

8. A core-shell toughening agent, characterized in that: The preparation method is described in any one of claims 1 to 7.

9. Use of the core-shell toughening agent according to claim 8 in improving the low-temperature impact resistance and / or yellowing resistance of plastics.

10. The use according to claim 9, characterized in that: The plastic is PC.

Images