A toughening agent for polycarbonate, its preparation method and application

Abstract

The present invention belongs to the technical field of toughening agents for polycarbonate, and specifically relates to a toughening agent for polycarbonate, its preparation method and application; the preparation method includes: mixing an alkyl acrylate, a crosslinking agent, an emulsifier and deionized water to obtain a monomer pre-emulsion; polymerizing under the action of an initiator; then adding dibutyl maleate, an alkyl methacrylate, an alkyl acrylate and an emulsifier to the system, and polymerizing under the action of an initiator to obtain emulsion A; mixing dibutyl maleate, the prepared emulsion A, an alkyl acrylate, a crosslinking agent, an emulsifier and deionized water, stirring and pre-emulsifying to obtain a pre-emulsion; polymerizing under the action of an initiator; continuously adding dibutyl maleate, an alkyl methacrylate and an emulsifier to the system, and polymerizing under the action of an initiator to obtain emulsion B. The impact performance, tensile strength and elongation at break of the polycarbonate blend added with the toughening agent of the present invention are all improved, and at the same time, it has good weather resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of toughening agents for polycarbonate, and particularly relates to a toughening agent for polycarbonate, a preparation method thereof, and an application thereof. Background Art

[0002] Polycarbonate is a high-performance polymer containing a carbonate group. According to the different functional groups, polycarbonate is divided into various types such as aliphatic-aromatic, aliphatic, and aromatic polycarbonates.

[0003] In actual applications, due to the poor mechanical properties of aliphatic-aromatic polycarbonate and aliphatic polycarbonate, ultimately only bisphenol A type polycarbonate has been industrially produced. Bisphenol A type polycarbonate has a very large molecular chain rigidity due to the presence of a benzene ring and a carbonate structure. Due to this special structure of this type of polycarbonate, it has excellent mechanical properties, heat resistance, transparency, and electrical insulation, and is widely used in fields such as automobiles, electronic appliances, optical instruments, and medical devices. However, the rigidity of polycarbonate is too high, and it is prone to cracking when subjected to impact or stress, which limits its application in some aspects. Therefore, it is particularly important to toughen and modify polycarbonate.

[0004] Currently, the commonly used polycarbonate toughening agents in the market are methyl methacrylate-butadiene-styrene terpolymer (MBS) and a core-shell structure toughening agent with silica as the core. For the core-shell structure toughening agent with silica as the core, since the core layer is silica, the toughening effect is not as good as that of a high molecular elastomer. Although methyl methacrylate-butadiene-styrene terpolymer (MBS) has a certain effect of improving impact and tensile properties, it has poor weather resistance and is expensive.

[0005] In view of this, how to further research and prepare a polycarbonate toughening agent with excellent toughening effect and comprehensive performance is a direction worthy of research. Summary of the Invention

[0006] The purpose of the present invention is to provide a toughening agent for polycarbonate, a preparation method thereof, and an application thereof, aiming at some problems existing in the existing polycarbonate toughening agents; due to the good compatibility of the ester substances on the surface layer of the toughening agent of the present invention with polycarbonate, and the introduction of dibutyl maleate in the formula, the grafting efficiency of flexible units on the main chain can be further improved, and ultimately the impact strength, tensile properties, and weather resistance of polycarbonate toughened products can be significantly improved.

[0007] To solve the above technical problems, the technical solution provided by the present invention is:

[0008] In the first aspect, a preparation method of a toughening agent for polycarbonate is provided, including the following steps:

[0009] a) Seed polymerization one: Mix and stir an acrylic alkyl ester, a crosslinking agent, an emulsifier, and deionized water, and obtain a monomer pre-emulsion through pre-emulsification; heat the system to 60 - 70 °C (for example, 62 °C, 64 °C, 65 °C, 68 °C), and carry out a polymerization reaction under the action of an initiator (such as a peroxide); (nuclear layer seed monomer polymerization)

[0010] b) Seed polymerization two: Continuously add dibutyl maleate, an acrylic alkyl ester, an acrylic alkyl ester, and an emulsifier to the system and mix and stir, heat the system to 70 - 80 °C (for example, 72 °C, 74 °C, 75 °C, 76 °C, 78 °C), and carry out a polymerization reaction under the action of an initiator (such as a peroxide) to obtain emulsion A; (shell layer seed monomer polymerization)

[0011] c) Nuclear layer polymerization: Mix and stir dibutyl maleate, emulsion A prepared in the above step, an acrylic alkyl ester, a crosslinking agent, an emulsifier, and deionized water, and obtain a pre-emulsion through pre-emulsification; heat the system to 60 - 70 °C (for example, 62 °C, 64 °C, 65 °C, 68 °C), and carry out a polymerization reaction under the action of an initiator (such as a peroxide);

[0012] d) Shell layer polymerization: Continuously add dibutyl maleate, an acrylic alkyl ester, and an emulsifier to the system and mix and stir, heat the system to 70 - 80 °C (for example, 72 °C, 74 °C, 75 °C, 76 °C, 78 °C), and carry out a polymerization reaction under the action of an initiator (such as a peroxide) to obtain emulsion B;

[0013] e) Drying: Spray-dry emulsion B prepared in the above step to obtain a powder of the toughening agent for polycarbonate.

[0014] According to the preparation method provided by the present invention, in steps a) to d), there is no special regulation on the polymerization time. For example, the polymerization time in steps a) to d) can each independently be 1 - 6 hours, such as 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, and is preferably 3 - 4 hours.

[0015] According to the preparation method provided by the present invention, in some embodiments, the number of carbon atoms in the alkyl group of the acrylic alkyl ester is 1 - 8 (such as 2, 3, 4, 5, 6, 7). The acrylic alkyl ester can be, for example but not limited to, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isopropyl acrylate, sec-butyl acrylate, tert-butyl acrylate, n-hexyl acrylate, n-heptyl acrylate, etc.

[0016] In some embodiments, the alkyl group in the alkyl methacrylate has 1-8 carbon atoms (e.g., 2, 3, 4, 5, 6, 7). The alkyl methacrylate can be, for example but not limited to, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, n-hexyl methacrylate, n-heptyl methacrylate.

[0017] In some embodiments, the crosslinking agent is selected from one or more of divinylbenzene, allyl methacrylate, and 1,4-butanediol dimethacrylate.

[0018] In some embodiments, the emulsifier is an anionic emulsifier, preferably selected from one or two of sodium dodecylbenzenesulfonate and sodium dodecyl sulfate.

[0019] In some embodiments, the initiator is a peroxide initiator, preferably one or more of potassium persulfate, ammonium persulfate, benzoyl peroxide, and diisopropylbenzene peroxide.

[0020] According to the preparation method provided by the present invention, in some embodiments, in the first-stage seed polymerization, based on 100 parts by total weight of each component, the components include the following parts by weight:

[0021] 21-33 parts of alkyl acrylate, for example, 22 parts, 24 parts, 25 parts, 26 parts, 28 parts, 30 parts, 32 parts,

[0022] 0.4-0.7 part of crosslinking agent, for example, 0.45 part, 0.5 part, 0.55 part, 0.6 part, 0.65 part,

[0023] 0.2-0.4 part of emulsifier, for example, 0.25 part, 0.28 part, 0.3 part, 0.32 part, 0.35 part, 0.38 part,

[0024] 66-78 parts of deionized water, for example, 67 parts, 68 parts, 70 parts, 72 parts, 74 parts, 75 parts, 76 parts.

[0025] In some embodiments, in the first-stage seed polymerization, the dosage of the initiator accounts for 0.06-0.20 wt% (e.g., 0.08 wt%, 0.09 wt%, 0.1 wt%, 0.12 wt%, 0.13 wt%, 0.14 wt%, 0.16 wt%, 0.18 wt%) of the weight of the monomers, and is preferably 0.1-0.15 wt%.

[0026] In some embodiments, in the second-stage seed polymerization, based on 100 parts by total weight of each component, the components include the following parts by weight:

[0027] 5 - 20 parts (preferably 9 - 14 parts) of dibutyl maleate, for example, 6 parts, 8 parts, 9 parts, 10 parts, 12 parts, 14 parts, 15 parts, 18 parts,

[0028] 62 - 90 parts of alkyl methacrylate, for example, 63 parts, 64 parts, 65 parts, 68 parts, 70 parts, 72 parts, 75 parts, 78 parts, 80 parts, 85 parts, 88 parts,

[0029] 4 - 20 parts of alkyl acrylate, for example, 5 parts, 6 parts, 8 parts, 9 parts, 10 parts, 12 parts, 14 parts, 15 parts, 18 parts,

[0030] 0.7 - 1.2 parts of emulsifier, for example, 0.75 parts, 0.8 parts, 0.85 parts, 0.9 parts, 0.95 parts, 1.0 parts, 1.1 parts, 1.15 parts.

[0031] In some embodiments, in the second stage of seed polymerization, the amount of the initiator accounts for 0.03 - 0.20 wt% (for example, 0.05 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.10 wt%, 0.12 wt%, 0.14 wt%, 0.15 wt%, 0.18 wt%) of the monomers by weight, and is preferably 0.06 - 0.17 wt%.

[0032] In some embodiments, in the core - layer polymerization, based on 100 parts of the total weight of each component, it includes the following parts of components:

[0033] 5 - 20 parts (preferably 9 - 15 parts) of dibutyl maleate, for example, 6 parts, 8 parts, 9 parts, 10 parts, 12 parts, 15 parts, 18 parts,

[0034] 1.5 - 2.4 parts of emulsion A, for example, 1.55 parts, 1.6 parts, 1.8 parts, 2.0 parts, 2.1 parts, 2.2 parts, 2.3 parts,

[0035] 10 - 25 parts of alkyl acrylate, for example, 12 parts, 14 parts, 15 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts,

[0036] 0.2 - 0.4 parts of cross - linker, for example, 0.25 parts, 0.26 parts, 0.28 parts, 0.3 parts, 0.32 parts, 0.35 parts, 0.38 parts,

[0037] 0.1 - 0.3 parts of emulsifier, for example, 0.15 parts, 0.18 parts, 0.2 parts, 0.22 parts, 0.25 parts, 0.28 parts,

[0038] 55 - 80 parts of deionized water, for example, 56 parts, 60 parts, 65 parts, 70 parts, 75 parts.

[0039] In some embodiments, in the core layer polymerization, the amount of the initiator accounts for 0.02-0.10 wt% of the monomers by weight (for example, 0.03 wt%, 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.09 wt%), preferably 0.04-0.08 wt%.

[0040] In some embodiments, in the shell layer polymerization, based on 100 parts by total weight of the components, it includes the following parts by weight of components:

[0041] 9-20 parts of dibutyl maleate, for example, 10 parts, 12 parts, 14 parts, 15 parts, 18 parts,

[0042] 80-90 parts of alkyl methacrylate, for example, 82 parts, 84 parts, 85 parts, 86 parts, 88 parts,

[0043] 0.2-0.5 parts of emulsifier, for example, 0.25 parts, 0.3 parts, 0.35 parts, 0.4 parts, 0.45 parts.

[0044] In some embodiments, in the shell layer polymerization, the amount of the initiator accounts for 0.1-1.0 wt% of the monomers by weight (for example, 0.2 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.8 wt%), preferably 0.36-0.78 wt%.

[0045] In a second aspect, there is provided a toughening agent prepared by the preparation method as described above.

[0046] For the toughening agent provided by the present invention, in some embodiments, the latex particle size of the polycarbonate toughening agent can be 150-300 nm (for example, 160 nm, 180 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 262 nm, 264 nm, 265 nm, 268 nm, 270 nm, 272 nm, 274 nm, 275 nm, 278 nm, 280 nm, 285 nm, 290 nm, 295 nm), preferably 200-300 nm, more preferably 250-300 nm, and the latex particle size dispersion index can be 0.002-0.01 (for example, 0.003, 0.004, 0.005, 0.006, 0.008, 0.009).

[0047] In a third aspect, there is provided an application of a toughening agent prepared by the preparation method as described above in polycarbonate. In the present invention, the operating steps and process conditions for applying the toughening agent in polycarbonate can be conventional selections in the art and will not be elaborated here.

[0048] In the present invention, the pre-emulsification operation process can make the reaction of the polymerization system more stable, and the obtained product particle size is uniform, which is helpful to improve the toughening effect of the toughening agent; and the addition of dibutyl maleate in the formula can effectively increase the flexible units in the polymer side chains and improve its energy absorption effect, thereby achieving better toughening effect and purpose; and the amount of emulsifier and initiator is controlled within a suitable range, which is conducive to the smooth progress of the polymerization process and reduces the output of by-products. While controlling the particle size within a suitable range, the particle size can be further increased, thereby improving the toughening effect. The toughening agent absorbs energy by inducing silver streaks and shear bands. When its particle size is small (<100nm), it cannot effectively induce sufficient silver streaks and shear bands, resulting in limited improvement in impact strength. If its particle size (>400nm) is too large, it will lead to excessive stress concentration, causing early fracture and even reducing toughness. The particle size distribution of the toughening agent latex particles obtained by the present invention is uniform and the particle size range is 150-300nm. When the particle size is within a certain range (such as 100-300nm), the larger the particle size, the more uniform stress concentration points can be formed in the matrix, which effectively triggers the energy absorption mechanism and significantly improves the impact strength of the resin.

[0049] Compared with the prior art, the technical solution of the present invention can achieve at least the following beneficial effects:

[0050] The toughening agent of the present invention can be smoothly carried out during the polymerization process, reduce the generation of by-products, increase the particle size of latex particles to a certain extent, ensure the uniformity of the particle size of the product, and help improve the toughening effect of the toughening agent; after the toughening agent of the present invention is added and applied to polycarbonate, the impact performance, tensile strength and elongation at break of the polycarbonate blend are all improved, and in addition, the polycarbonate blend product can achieve excellent toughening while maintaining good weather resistance. DETAILED DESCRIPTION

[0051] In order to understand the technical features and content of the present invention in detail, the preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described in the embodiments, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. For those who do not specify specific conditions in the embodiments, they are carried out according to normal conditions or the conditions recommended by the manufacturer.

[0052] <Source of raw materials>

[0053] Methyl methacrylate: Lihua Yilijin Refining and Chemical Co., Ltd., industrial grade;

[0054] Ethyl methacrylate: Shandong Derui Polymer Materials Co., Ltd., industrial grade;

[0055] Ethyl acrylate: Shandong Derui Polymer Materials Co., Ltd., industrial grade;

[0056] n-Butyl acrylate, Shandong Kaitai Petrochemical Acrylic Co., Ltd., industrial pure;

[0057] Butyl methacrylate: Shandong Hefeng Chemical Co., Ltd., industrial pure;

[0058] Potassium persulfate: Yatai Electrochemical Co., Ltd., industrial pure;

[0059] Ammonium persulfate: Shandong Sanju Chemical Technology Co., Ltd., industrial pure;

[0060] Dicumyl peroxide: Anhui Xiangyun Rubber and Plastic Co., Ltd.;

[0061] Benzoyl peroxide: Dongying Jinghai Chemical Co., Ltd.;

[0062] Sodium dodecylbenzenesulfonate (emulsifier): Jiangsu Qingting Detergent Co., Ltd.;

[0063] Divinylbenzene: Jiangsu Evergreen New Materials Technology Co., Ltd.;

[0064] 1,4-Butanediol dimethacrylate: Jining Chemical Technology Co., Ltd.;

[0065] Allyl methacrylate: Tai'an Jiangzhou Biotechnology Co., Ltd.;

[0066] Dibutyl maleate: Shandong Yuanli Chemical Co., Ltd.;

[0067] Polycarbonate, LG Chem, South Korea.

[0068] <Test method>

[0069] Izod impact strength: unit is KJ / m 2 , and the test standard is GB / T1843-2008;

[0070] Tensile strength: unit is MPa, and the test standard is GB / T1040-2006;

[0071] Elongation at break: unit is %, and the test standard is GB / T1040-2006;

[0072] Weather resistance test: Place 2mm impact notch specimens with dimensions of 10×80 cm in a constant temperature and humidity chamber with a temperature of 85°C and a humidity of 85% under light conditions for 4 weeks, and take out a group of samples every week for impact performance testing.

[0073] In the present invention, a preparation method of a toughening agent for polycarbonate with a toughening effect, the specific implementation manner can be as follows:

[0074] a) Add acrylic alkyl ester, crosslinking agent, emulsifier, and deionized water into a reaction kettle in a weight ratio of (21 - 33):(0.4 - 0.7):(0.2 - 0.4):(66 - 78). Start stirring to mix them evenly to obtain a monomer pre-emulsion. Heat the system to 60°C, introduce nitrogen gas at the bottom of the reaction kettle, and add the prepared initiator solvent. The addition amount of the initiator accounts for 0.1 - 0.15 wt% of the monomer weight. Control the reaction temperature between 60°C and 70°C and carry out the polymerization reaction for 3 - 4 hours.

[0075] b) Then, continue to add dibutyl maleate, alkyl methacrylate, acrylic alkyl ester, emulsifier, and peroxide into the system in a weight ratio of (5 - 20):(62 - 90):(4 - 20):(0.7 - 1.2):(0.08 - 0.12). Stir to mix them evenly. Heat the system and control the reaction temperature between 70 - 80°C. Continue the reaction for 3 - 4 hours and then cure to obtain emulsion A.

[0076] c) Add dibutyl maleate, emulsion A prepared above, acrylic alkyl ester, crosslinking agent, emulsifier, and deionized water into a reaction kettle in a weight ratio of (5 - 20):(1.5 - 2.4):(10 - 25):(0.2 - 0.4):(0.1 - 0.3):(55 - 80). Start stirring to mix them evenly to obtain a pre-emulsion. Heat the system to 50°C, introduce nitrogen gas at the bottom of the reaction kettle, and add the prepared initiator solvent. The addition amount of the initiator accounts for 0.04 - 0.08 wt% of the monomer weight. Heat the system and control the reaction temperature between 60°C and 70°C and carry out the polymerization reaction for 3 - 4 hours.

[0077] d) Then, continue to add dibutyl maleate, alkyl methacrylate, emulsifier, and peroxide into the system in a weight ratio of (9 - 20):(80 - 90):(0.2 - 0.5):(0.4 - 0.7). Stir to mix them evenly. Control the reaction temperature between 70 - 80°C and continue the polymerization reaction for 3 - 4 hours and then cure to obtain emulsion B.

[0078] Perform spray drying on the obtained emulsion B to obtain the toughening agent powder for polycarbonate.

[0079] Example

[0080] Example 1:

[0081] A preparation method of a toughening agent for polycarbonate, comprising the following steps:

[0082] a) In a 1-ton reactor, 155 Kg of n-butyl acrylate, 3.11 Kg of divinylbenzene, 1.56 Kg of sodium dodecylbenzenesulfonate, and 421 Kg of deionized water were added in sequence. Stirring was started to mix them evenly to obtain a monomer pre-emulsion. The system was heated to 60 °C, nitrogen was introduced at the bottom of the reactor, 0.16 Kg of diisopropyl peroxide was added, and the reaction temperature was controlled at 65 °C for a polymerization reaction for 3.5 hours;

[0083] b) Continuing to add 13.65 Kg of dibutyl maleate, 92 Kg of ethyl methacrylate, 11 Kg of n-butyl acrylate, 1 Kg of sodium dodecylbenzenesulfonate, and 0.1 kg of diisopropyl peroxide to the system, controlling the reaction temperature at 70 °C, and continuing the reaction for 3 hours, then aging to obtain Emulsion A.

[0084] c) 81 Kg of dibutyl maleate, 12.73 Kg of Emulsion A prepared in the above step, 134 Kg of n-butyl acrylate, 1.72 Kg of divinylbenzene, 1.17 Kg of sodium dodecylbenzenesulfonate, and 414 Kg of deionized water were added to a 1-ton reactor. Stirring was started to mix them evenly to obtain a pre-emulsion. The system was heated to 50 °C, nitrogen was introduced at the bottom of the reactor, 0.11 Kg of diisopropyl peroxide was added, and the reaction temperature was controlled at about 65 °C for a polymerization reaction for 3 hours;

[0085] d) Continuing to add 9 Kg of dibutyl maleate, 41 Kg of ethyl methacrylate, 0.19 Kg of sodium dodecylbenzenesulfonate, and 0.3 Kg of diisopropyl peroxide to the system, controlling the reaction temperature at 75 °C, and continuing the reaction for 4 hours and then aging to obtain Emulsion B with a monomer conversion rate of 97.98%.

[0086] The prepared Emulsion B was spray-dried to obtain a toughening agent powder for polycarbonate.

[0087] Example 2:

[0088] A preparation method of a toughening agent for polycarbonate, comprising the following steps:

[0089] a) In a 1-ton reactor, 160 Kg of ethyl acrylate, 3 Kg of 1,4-butanediol dimethacrylate, 1.3 Kg of sodium dodecylbenzenesulfonate, and 400 Kg of deionized water were added in sequence. Stirring was started to mix them evenly to obtain a monomer pre-emulsion. The system was heated to 50 °C, nitrogen was introduced at the bottom of the reactor, 0.18 Kg of ammonium persulfate was added, and the reaction temperature was controlled at 60 °C for a polymerization reaction for 3.5 hours;

[0090] b) Continuously add 13.65 Kg of dibutyl maleate, 92 Kg of methyl methacrylate, 11 Kg of ethyl acrylate, 1 Kg of sodium dodecylbenzenesulfonate, and 0.1 kg of ammonium persulfate into the system. Control the reaction temperature at 70 °C and continue the reaction for 3 hours, then cure to obtain Emulsion A.

[0091] c) Add 81 Kg of dibutyl maleate, 12.73 Kg of Emulsion A prepared in the above step, 134 Kg of ethyl acrylate, 1.72 Kg of 1,4-butanediol dimethacrylate, 1.17 Kg of sodium dodecylbenzenesulfonate, and 414 Kg of deionized water into a 1-ton reaction kettle. Start stirring to mix them evenly to obtain a pre-emulsion. Heat the system to 50 °C, introduce nitrogen gas at the bottom of the reaction kettle, add 0.11 Kg of ammonium persulfate, and control the reaction temperature at about 65 °C to carry out the polymerization reaction for 3 hours.

[0092] d) Continuously add 9 Kg of dibutyl maleate, 41 Kg of methyl methacrylate, 0.19 Kg of sodium dodecylbenzenesulfonate, and 0.3 Kg of ammonium persulfate into the system. Control the reaction temperature at 70 °C and continue the reaction for 4 hours, then cure to obtain Emulsion B, and the monomer conversion rate is 98.25%.

[0093] Perform spray drying on the obtained Emulsion B to obtain the toughening agent powder for polycarbonate.

[0094] Example 3

[0095] A preparation method of a toughening agent for polycarbonate, comprising the following steps:

[0096] a) In a 1-ton reaction kettle, sequentially add 160 Kg of n-butyl acrylate, 3 Kg of allyl methacrylate, 1.3 Kg of sodium dodecylbenzenesulfonate, and 400 Kg of deionized water. Start stirring to mix them evenly to obtain a monomer pre-emulsion. Heat the system to 50 °C, introduce nitrogen gas at the bottom of the reaction kettle, add 0.16 Kg of potassium persulfate, and control the reaction temperature at 60 °C to carry out the polymerization reaction for 3.5 hours.

[0097] b) Continuously add 18 Kg of dibutyl maleate, 100 Kg of methyl methacrylate, 12 Kg of n-butyl acrylate, 1 Kg of sodium dodecylbenzenesulfonate, and 0.1 kg of potassium persulfate into the system. Control the reaction temperature at 70 °C and continue the reaction for 3 hours, then cure to obtain Emulsion A.

[0098] c) Add 81 Kg of dibutyl maleate, 12.73 Kg of emulsion A prepared in the above steps, 134 Kg of n-butyl acrylate, 1.72 Kg of allyl methacrylate, 1.17 Kg of sodium dodecylbenzenesulfonate, and 414 Kg of deionized water into a 1-ton reaction kettle, start stirring to mix them evenly to obtain a pre-emulsion; heat the system to 50 °C, introduce nitrogen gas at the bottom of the reaction kettle, add 0.11 Kg of potassium persulfate, control the reaction temperature at about 65 °C, and carry out the polymerization reaction for 3 hours;

[0099] d) Continue to add 9 Kg of dibutyl maleate, 41 Kg of methyl methacrylate, 0.19 Kg of sodium dodecylbenzenesulfonate, and 0.3 Kg of potassium persulfate to the system, control the reaction temperature at 70 °C, continue the reaction for 4 hours and then cure to obtain emulsion B, and the monomer conversion rate is 97.31%.

[0100] Perform spray drying on the obtained emulsion B to obtain the toughening agent powder for polycarbonate.

[0101] Example 4:

[0102] A preparation method of a toughening agent for polycarbonate, comprising the following steps:

[0103] a) In a 1-ton reaction kettle, sequentially add 160 Kg of n-butyl acrylate, 3 Kg of divinylbenzene, 1.3 Kg of sodium dodecylbenzenesulfonate, and 400 Kg of deionized water, start stirring to mix them evenly to obtain a monomer pre-emulsion; heat the system to 50 °C, introduce nitrogen gas at the bottom of the reaction kettle, add 0.16 Kg of potassium persulfate, control the reaction temperature at 60 °C, and carry out the polymerization reaction for 3.5 hours;

[0104] b) Continue to add 18 Kg of dibutyl maleate, 100 Kg of butyl methacrylate, 12 Kg of n-butyl acrylate, 1 Kg of sodium dodecylbenzenesulfonate, and 0.1 kg of potassium persulfate to the system, control the reaction temperature at 70 °C, continue the reaction for 3 hours and then cure to obtain emulsion A.

[0105] c) Add 90 Kg of dibutyl maleate, 12.73 Kg of emulsion A prepared in the above steps, 124 Kg of n-butyl acrylate, 1.72 Kg of divinylbenzene, 1 Kg of sodium dodecylbenzenesulfonate, and 414 kg of deionized water into a 1-ton reaction kettle, start stirring to mix them evenly to obtain a pre-emulsion; heat the system to 50 °C, introduce nitrogen gas at the bottom of the reaction kettle, add 0.11 Kg of potassium persulfate, control the reaction temperature at about 65 °C, and carry out the polymerization reaction for 3 hours;

[0106] d) Continuously add 9 Kg of dibutyl maleate, 41 Kg of butyl methacrylate, 0.19 Kg of sodium dodecylbenzenesulfonate, and 0.3 Kg of potassium persulfate to the system. Control the reaction temperature at 70 °C and continue the reaction for 4 hours, then cure to obtain Emulsion B, with a monomer conversion rate of 97.20%.

[0107] Perform spray drying on the obtained Emulsion B to obtain the toughening agent powder for polycarbonate.

[0108] Example 5:

[0109] A preparation method of a toughening agent for polycarbonate, comprising the following steps:

[0110] a) In a 1-ton reaction kettle, sequentially add 155 Kg of n-butyl acrylate, 3 Kg of divinylbenzene, 1.3 Kg of sodium dodecyl sulfate, and 400 Kg of deionized water. Start stirring to mix them evenly to obtain a monomer pre-emulsion; heat the system to 50 °C, introduce nitrogen at the bottom of the reaction kettle, add 0.2 Kg of benzoyl peroxide, control the reaction temperature at 60 °C, and carry out the polymerization reaction for 3.5 hours;

[0111] b) Continuously add 18 Kg of dibutyl maleate, 100 Kg of methyl methacrylate, 12 Kg of n-butyl acrylate, 1 Kg of sodium dodecyl sulfate, and 0.1 kg of benzoyl peroxide to the system. Control the reaction temperature at 70 °C, continue the reaction for 3 hours, and then cure to obtain Emulsion A.

[0112] c) Add 90 Kg of dibutyl maleate, 12.73 Kg of Emulsion A, 124 Kg of n-butyl acrylate, 1.72 Kg of divinylbenzene, 1 Kg of sodium dodecyl sulfate, and 414 Kg of deionized water to a 1-ton reaction kettle. Start stirring to mix them evenly to obtain a pre-emulsion; heat the system to 50 °C, introduce nitrogen at the bottom of the reaction kettle, add 0.17 Kg of benzoyl peroxide, control the reaction temperature at about 65 °C, and carry out the polymerization reaction for 3 hours;

[0113] d) Continuously add 5 Kg of dibutyl maleate, 45 Kg of methyl methacrylate, 0.19 Kg of sodium dodecyl sulfate, and 0.3 Kg of benzoyl peroxide to the system. Control the reaction temperature at 70 °C, continue the reaction for 3.5 hours, and then cure to obtain Emulsion B, with a monomer conversion rate of 98.21%.

[0114] Perform spray drying on the obtained Emulsion B to obtain the toughening agent powder for polycarbonate.

[0115] Comparative Example 1:

[0116] A preparation method of a toughening agent for polycarbonate, comprising the following steps:

[0117] a) In a 1-ton reactor, 155 Kg of n-butyl acrylate, 3.28 Kg of allyl methacrylate, 1.77 Kg of sodium dodecylbenzenesulfonate, and 500 Kg of deionized water were successively added. Stirring was started to mix them evenly to obtain a monomer pre-emulsion. The system was heated to 50 °C, nitrogen was introduced at the bottom of the reactor, 0.2 Kg of potassium persulfate was added, and the reaction temperature was controlled at 60 °C for a polymerization reaction for 3 hours;

[0118] b) Continuing to add 105.65 Kg of methyl methacrylate, 11 Kg of n-butyl acrylate, 1 Kg of sodium dodecylbenzenesulfonate, and 0.15 kg of potassium persulfate to the system, controlling the reaction temperature at 70 °C, and continuing the reaction for 3 hours, then aging to obtain Emulsion A with a monomer conversion rate of 97.11%.

[0119] The prepared Emulsion A was spray-dried to obtain a toughening agent powder for polycarbonate.

[0120] Comparative Example 2:

[0121] A method for preparing a toughening agent for polycarbonate, comprising the following steps:

[0122] a) In a 1-ton reactor, 105 Kg of n-butyl acrylate, 50 Kg of dibutyl maleate, 3.28 Kg of allyl methacrylate, 1.77 Kg of sodium dodecylbenzenesulfonate, and 500 Kg of deionized water were successively added. Stirring was started to mix them evenly to obtain a monomer pre-emulsion. The system was heated to 50 °C, nitrogen was introduced at the bottom of the reactor, 0.2 Kg of potassium persulfate was added, and the reaction temperature was controlled at 60 °C for a polymerization reaction for 3.5 hours;

[0123] b) Continuing to add 19 Kg of dibutyl maleate, 86.65 Kg of methyl methacrylate, 11 Kg of n-butyl acrylate, 1 Kg of sodium dodecylbenzenesulfonate, and 0.15 kg of potassium persulfate to the system, controlling the reaction temperature at 70 °C, and continuing the reaction for 3 hours, then aging to obtain Emulsion A with a monomer conversion rate of 97.02%.

[0124] The prepared Emulsion A was spray-dried to obtain a toughening agent powder for polycarbonate.

[0125] Comparative Example 3

[0126] A method for preparing a toughening agent for polycarbonate, comprising the following steps:

[0127] a) In a 1-ton reactor, 155 Kg of n-butyl acrylate, 3 Kg of divinylbenzene, 1.3 Kg of sodium dodecyl sulfate, and 400 Kg of deionized water were successively added. Stirring was started to mix them evenly to obtain a monomer pre-emulsion. The system was heated to 50 °C, nitrogen was introduced at the bottom of the reactor, 0.22 Kg of benzoyl peroxide was added, and the reaction temperature was controlled at 60 °C for a polymerization reaction for 3 hours;

[0128] b) 105 Kg of methyl methacrylate, 23 Kg of n-butyl acrylate, 1 Kg of sodium dodecyl sulfate, and 0.2 kg of benzoyl peroxide were continuously added to the system. The reaction temperature was controlled at 70 °C. After continuing the reaction for 3 hours, it was aged to obtain Emulsion A.

[0129] c) 12.73 Kg of Emulsion A prepared in the above step, 214 Kg of n-butyl acrylate, 1.72 Kg of divinylbenzene, 1 Kg of sodium dodecyl sulfate, and 414 Kg of deionized water were added to a 1-ton reactor. Stirring was started to mix them evenly to obtain a pre-emulsion. The system was heated to 50 °C, nitrogen was introduced at the bottom of the reactor, 0.18 Kg of benzoyl peroxide was added, and the reaction temperature was controlled at about 65 °C for a polymerization reaction for 3 hours;

[0130] d) 45 Kg of methyl methacrylate, 0.19 Kg of sodium dodecyl sulfate, and 0.35 Kg of benzoyl peroxide were continuously added to the system. The reaction temperature was controlled at 70 °C. After continuing the reaction for 4 hours, it was aged to obtain Emulsion B, and the monomer conversion rate was 98.36%.

[0131] The prepared Emulsion B was spray-dried to obtain a toughening agent powder for polycarbonate.

[0132] Table 1 Polymerization parameters of the toughening agents obtained in each example and comparative example

[0133]

[0134] After obtaining the toughening agents through the above examples and comparative examples, the toughening effect on polycarbonate was tested through the following operations and methods.

[0135] The toughening agents prepared in the above examples and Comparative Examples 1-3 were mixed with pure polycarbonate. The formulation of each component in the blend raw materials is shown in Table 2. The operating and process conditions for blending and extrusion granulation were as follows: The raw materials were mixed in a high-speed mixer at 110 °C, then discharged after cooling to 44 °C, and then an extrusion granulation experiment was carried out through an extruder. The extrusion granulation process conditions of the polycarbonate blend are shown in Table 3 below.

[0136] Table 2 Component ratios in polycarbonate blend products

[0137]

[0138] Table 3 Extrusion granulation process conditions of polycarbonate blends

[0139]

[0140] After granulation, it is dried at 120°C for 4 hours and then injection-molded in an injection molding machine; the injection molding process conditions are shown in Table 4 below.

[0141] Table 4 Injection molding process conditions

[0142]

[0143] According to the above detection methods and standards, the impact performance, weather resistance and tensile properties of the toughening agents in each example and comparative example on polycarbonate products are tested, as shown in Tables 5-7.

[0144] Table 5 Test data of products obtained in each example and comparative example

[0145]

[0146] Table 6 Weather resistance test data of products obtained in each example and comparative example

[0147]

[0148] Table 7 Tensile property test data of products obtained in each example and comparative example

[0149]

[0150] Pure polycarbonate products without toughening agents have low impact toughness, weather resistance, and elongation at break. After blending pure polycarbonate with the toughening agent prepared by the present invention, while the impact toughness and tensile properties of the products are improved, their weather resistance is also good. By comparing Examples 1-5 with Comparative Examples 1-3, it can be found that if the obtained toughening agent is a conventional two-layer core-shell structure, or a conventional two-layer core-shell structure with dibutyl maleate component added to the formula, or a four-layer core-shell structure without dibutyl maleate component added to the formula, its performance in various performance indicators is not as good as that of the toughening agent with a four-layer core-shell structure obtained in Examples 1-5. This shows that by adopting the technical solution of the present invention, the polymerization process can proceed smoothly, reducing the generation of by-products. The obtained latex particles of the toughening agent have uniform particle sizes, and the particle sizes of the latex particles are increased within a suitable particle size range, better improving its performance. Applying the toughening agent of the present invention to the polycarbonate toughening system, the impact performance, tensile strength, and elongation at break of the obtained toughened blend resin or product are all improved; at the same time, the toughened blend resin or product has good weather resistance while being toughened. That is, compared with the products modified by ordinary toughening agents, after the impact performance of the products modified by the toughening agent provided by the present invention is improved and they experience the same weathering conditions, their impact performance is still relatively high.

[0151] The various embodiments of the present invention have been described above. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the gist of the present invention.

Claims

1. A method for preparing a toughening agent for polycarbonate, characterized in that: The following steps are involved: a) Seed polymerization 1: Mix and stir alkyl acrylate, crosslinking agent, emulsifier and deionized water, and obtain monomer pre-emulsification; heat the system to 60-70°C, and carry out polymerization reaction under the action of initiator; b) Seed polymerization II: Continue to add dibutyl maleate, alkyl methacrylate, alkyl acrylate and emulsifier into the system and mix and stir, raise the temperature of the system to 70-80°C, and carry out polymerization reaction under the action of the initiator to obtain emulsion A; c) Core layer polymerization: dibutyl maleate, emulsion A prepared in the above step, alkyl acrylate, crosslinking agent, emulsifier and deionized water are mixed and stirred, and pre-emulsified to obtain a pre-emulsion; the system is heated to 60-70°C, and a polymerization reaction is carried out under the action of an initiator; d) Shell polymerization: continue to add dibutyl maleate, alkyl methacrylate and emulsifier into the system and mix and stir, raise the temperature of the system to 70-80°C, and carry out polymerization reaction under the action of the initiator to obtain emulsion B; e) Drying: The emulsion B prepared in the above step is spray-dried to obtain a powder of the toughening agent for polycarbonate.

2. The preparation method according to claim 1, characterized in that: The alkyl group in the alkyl acrylate has 1 to 8 carbon atoms.

3. The preparation method according to claim 1, characterized in that: The alkyl group in the alkyl methacrylate has 1 to 8 carbon atoms.

4. The preparation method according to claim 1, characterized in that: The crosslinking agent is selected from one or more of divinylbenzene, allyl methacrylate and 1,4-butanediol dimethacrylate.

5. The preparation method according to claim 1, characterized in that: The emulsifier is an anionic emulsifier.

6. The preparation method according to claim 1, characterized in that: The initiator is a peroxide initiator.

7. The preparation method according to claim 1, characterized in that: In the seed polymerization, the total weight of each component is 100 parts, including the following components: 21-33 parts of alkyl acrylate, 0.4-0.7 parts of cross-linking agent, 0.2-0.4 parts of emulsifier, 66-78 parts deionized water.

8. The preparation method according to claim 1, characterized in that: In the seed polymerization 2, the total weight of each component is 100 parts, including the following components: 5-20 parts of dibutyl maleate, 62-90 parts of alkyl methacrylate, 4-20 parts of alkyl acrylate, 0.7-1.2 parts of emulsifier.

9. The preparation method according to claim 1, characterized in that: In the core layer polymerization, the total weight of each component is 100 parts, including the following components: 5-20 parts of dibutyl maleate, 1.5-2.4 parts of emulsion A, 10-25 parts of alkyl acrylate, 0.2-0.4 parts of cross-linking agent, 0.1-0.3 parts of emulsifier, 55-80 parts deionized water.

10. The preparation method according to any one of claims 1 to 9, characterized in that: In the shell polymerization, the total weight of each component is 100 parts, including the following components: 9-20 parts of dibutyl maleate, 80-90 parts of alkyl methacrylate, 0.2-0.5 parts of emulsifier.

11. A toughening agent obtained by the preparation method according to any one of claims 1 to 10.

12. Use of the toughening agent obtained by the preparation method according to any one of claims 1 to 10 in polycarbonate.

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