Heat-resistant agent with star-shaped structure, preparation method and application of heat-resistant agent in preparation of heat-resistant ABS (Acrylonitrile Butadiene Styrene) resin

Abstract

The invention discloses a heat-resistant agent with a star-shaped structure, a preparation method and application of the heat-resistant agent in preparation of heat-resistant ABS resin, and belongs to the technical field of synthetic resin. The four-functional-group initiator is adopted to initiate polymerization of styrene, N-phenylmaleimide and the third monomer, the topological structure of the prepared heat-resistant agent is star-shaped, that is, the main chain of the prepared heat-resistant agent is equivalent to the branch chain in length, so that the heat resistance of the ABS resin is improved, the flowability of the ABS resin is guaranteed, and the service life of the ABS resin is prolonged. The rigidity-toughness balance of the ABS resin is optimized. Experimental results show that after the heat-resistant monomer N-phenylmaleimide is added, the heat resistance of the ABS resin is remarkably improved, the glass-transition temperature of the ABS resin is 180 DEG C, the tensile strength of the ABS resin is also remarkably improved, and the impact strength of the heat-resistant ABS resin after the four-functional-group initiator is used is larger than 150 J / m, so that the application requirements are met.

Description

Technical Field

[0001] The invention belongs to the technical field of synthetic resins, and in particular relates to a heat-resistant agent with a star-shaped structure, a preparation method and application of the heat-resistant agent in preparing heat-resistant ABS resin. Background Art

[0002] ABS resin is a plastic with good mechanical properties, processing properties and solvent resistance. It is widely used in automobile manufacturing, household appliances and avionics. The content of styrene and acrylonitrile in the composition of ABS resin determines its own heat resistance. The heat deformation temperature of general-purpose ABS resin is generally between 75 and 85°C, which is often limited in the application of household appliances. Therefore, how to improve the heat resistance of ABS resin is a technical problem that industrial production and application companies need to solve urgently.

[0003] At present, the main methods for improving the heat resistance of ABS resin are as follows: one of them is to melt-blend ABS resin with a resin with good heat resistance to prepare ABS resin alloy, thereby improving its heat resistance. For example, a method for preparing a high heat-resistant PC / ABS alloy reported in Chinese patent CN202210548264.5 is to melt-blend polycarbonate (PC) resin and ABS resin in proportion to improve the heat resistance of ABS resin. The advantage of this method is that it does improve the heat resistance of ABS resin, but the disadvantage is that the cost of PC raw materials is high, and the processing temperature of PC is higher than that of ABS resin. In the process of replacing ABS resin with PC / ABS alloy, its processing temperature needs to be increased. A technology similar to this method is to add inorganic fillers to ABS resin after preliminary modification. For example, Chinese patent CN 201310203672.8 reports the use of glass fiber to modify ABS resin. The advantage of this method is that the strength of ABS resin modified by glass fiber will be significantly increased, but its own toughness will be significantly reduced. Another method is to replace part of the styrene in the SAN resin (copolymer of styrene and acrylonitrile) in the ABS resin with a monomer a-methylstyrene with better heat resistance to prepare a-SAN resin, thereby improving the heat resistance of the ABS resin. This solution has a wide range of applications in the field of ABS resin. For example, Chinese patent CN201480006086.7 reports a heat-resistant SAN resin and a preparation method thereof, as well as a heat-resistant ABS resin composition comprising the heat-resistant SAN resin, wherein the heat-resistant SAN resin comprises 60 to 75 wt% of α-methylstyrene, 25 to 35 wt% of a vinyl cyanide compound and 0 to 10 wt% of an aromatic vinyl compound other than α-methylstyrene. In addition to introducing α-methylstyrene into SAN resin to improve the heat resistance of ABS resin, a more widely used method is to directly copolymerize N-phenylmaleimide monomer with better heat resistance into SAN resin as a heat-resistant monomer. This method of improving heat resistance is more obvious. For example, Chinese patent 200910046948.X reported a one-step method for synthesizing styrene / N-phenylmaleimide / maleic anhydride terpolymers, which is to use a free radical initiator to initiate polymerization of styrene / N-phenylmaleimide / maleic anhydride terpolymers in a fixed ratio. The prepared heat-resistant agent can partially replace the SAN resin in ABS resin to improve the heat resistance of ABS resin. Chinese patent CN 201310433297.6 also reported a similar method for preparing heat-resistant ABS resin.

[0004] Comparing the current technical methods for preparing heat-resistant ABS resin, the method of introducing N-phenylmaleimide as a heat-resistant monomer into ABS resin is the simplest and most effective in improving the heat resistance of ABS resin. At present, the heat-resistant agent prepared by introducing N-phenylmaleimide into SAN copolymer or copolymerizing with styrene is a common chain structure, and its topological structure is a straight chain with a branched structure. The fluidity of this structure is poor, and the heat-resistant SAN resin or heat-resistant agent prepared by this method will reduce the impact strength of ABS resin after being introduced into ABS resin, destroying the rigidity and toughness balance of the original ABS resin. Summary of the invention

[0005] The purpose of the present invention is to provide a heat-resistant agent with a star-shaped structure, a preparation method and its application in the preparation of heat-resistant ABS resin. The present invention uses a tetrafunctional initiator with a structural formula as shown in formula (I) to initiate the polymerization of styrene, N-phenylmaleimide and a functional monomer (the functional monomer is one or a mixture of acrylonitrile or maleic anhydride), and the topological structure of the prepared heat-resistant agent is star-shaped, that is, the main chain and the side chain length of the prepared heat-resistant agent are equivalent, thereby improving the heat resistance of the ABS resin, ensuring the fluidity of the ABS resin itself, and optimizing the rigidity and toughness balance of the ABS resin itself.

[0006]

[0007] The preparation method of a heat-resistant agent with a star-shaped structure according to the present invention comprises the following steps:

[0008] (1) After the negative pressure in the reactor is evacuated and replaced with nitrogen 2 to 3 times, 50 to 70 parts by weight of aromatic vinyl monomer as a polymerization monomer, 5 to 25 parts by weight of heat-resistant monomer, 0 to 15 parts by weight of functional monomer, and 15 to 30 parts by weight of solvent are added, and stirred until all the heat-resistant monomer is completely dissolved;

[0009] (2) heating the reactor of step (1) to 90-140° C., adding 0.01-0.1 parts by weight of a tetrafunctional initiator (U.S. Patent No. US005760149A) having a structural formula (I) to initiate a polymerization reaction for 1-3 hours; then heating the reactor to 140-160° C. and continuing the reaction for 1-3 hours to obtain a polymer solution;

[0010] (3) removing volatile components from the polymer solution obtained in step (2) under vacuum at 220-250° C., and then removing the residual solvent and monomer in the product to make the concentration of organic volatiles in the product less than 500 ppm, thereby obtaining the heat-resistant agent with a star structure, whose structural formula is shown in (II), whose reaction formula is shown in (III), and whose infrared spectrum is shown in the attached figure. Figure 1 shown.

[0011] As shown in the figure, the characteristic absorption of N-phenylmaleimide fragment is 1381cm-1, indicating that the imine structure is a five-membered ring. -1 and 1183cm -1 The bands at 1599cm represent the stretching vibrations of the carbonyl bond and the CN bond. -1 、1455cm -1 and 1495cm -1 The peak at 2923 cm-1 is related to the phenyl groups in N-phenylmaleimide (NPMI) and styrene (St) units, reflecting the semicircular stretching and mixed CH bending of the monosubstituted benzene ring. -1 and 2850cm -1 The stretching vibration at 1779 cm-1 confirms the presence of the St group. -1 , belonging to the C=O of maleic anhydride, this peak indicates that the maleic anhydride (MAH) monomer is successfully polymerized in the polymer chain. Therefore, these analyses prove the formation of NPMI-St-MAH copolymer (heat resistant agent).

[0012]

[0013] in It is a small molecule byproduct, which is removed by removing the volatile components;

[0014] (4) 10 to 20 parts by weight of the prepared heat-resistant agent, 25 to 30 parts by weight of an ABS graft copolymer (wherein the rubber content is 50 to 70%), and 50 to 65 parts by weight of a styrene and acrylonitrile copolymer (SAN resin, brand AS-106) are mixed and melt-blended and granulated at 210 to 230° C. using a twin-screw extruder to obtain a heat-resistant ABS resin.

[0015] The aromatic vinyl monomer used in step (1) of the present invention is styrene or a-methylstyrene, or a mixture of the two;

[0016] The heat-resistant monomer used in step (1) of the present invention is N-phenylmaleimide;

[0017] The functional monomer used in step (1) of the present invention is acrylonitrile or maleic anhydride, or a mixture of the two;

[0018] The solvent used in step (1) of the present invention is one of toluene, ethylbenzene or xylene. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 : Infrared spectrum of the prepared heat-resistant agent;

[0020] Figure 2: Glass transition temperature curve of the heat-resistant agent prepared in Example 3. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is described below through specific embodiments. However, it is necessary to point out that the following embodiments are only used to describe the content of the invention and do not constitute a limitation on the protection scope of the present invention.

[0022] Example 1

[0023] (1) After the negative pressure in the reactor is evacuated and replaced with nitrogen twice, 50 kg of polymerization monomer styrene, 5 kg of heat-resistant monomer N-phenylmaleimide, 15 kg of functional monomer acrylonitrile and 30 kg of solvent toluene are added, and stirred until the heat-resistant monomer N-phenylmaleimide is completely dissolved;

[0024] (2) The reactor of step (1) was heated to 90°C, and after the temperature stabilized, 0.1 kg of a tetrafunctional initiator was added to initiate the polymerization reaction. The temperature was kept stable during the reaction. After 3 hours of reaction, the temperature was raised to 140°C and the reaction was continued for 3 hours to obtain a polymer solution;

[0025] (3) removing volatile components from the polymer solution obtained in step (2) in a vacuum chamber at 230° C. to remove residual solvents and monomers in the product, so that the organic volatiles in the product are less than 500 ppm to obtain a heat-resistant agent with a star-shaped structure, the product mass is 49.07 kg, and the yield is 70%;

[0026] (4) 0.2 kg of the prepared heat-resistant agent, 0.25 kg of ABS graft copolymer (rubber content 60%), and 0.55 kg of styrene and acrylonitrile copolymer (SAN resin, brand AS-106) were mixed and melt-blended and granulated at 220° C. using a twin-screw extruder to obtain 1 kg of heat-resistant ABS resin.

[0027] Example 2

[0028] (1) After the negative pressure in the reactor was evacuated and replaced with nitrogen three times, 70 kg of polymerization monomer styrene, 25 kg of heat-resistant monomer N-phenylmaleimide, 5 kg of functional monomer maleic anhydride and 15 kg of solvent ethylbenzene were added, and stirring was started until the heat-resistant monomer N-phenylmaleimide was completely dissolved;

[0029] (2) The reactor of step (1) was heated to 110°C, and after the temperature stabilized, 0.01 kg of a tetrafunctional initiator was added to initiate the polymerization reaction. The temperature was kept stable during the reaction. After the reaction time was 3 hours, the temperature was raised to 150°C and the reaction was continued for 3 hours to obtain a polymer solution;

[0030] (3) removing volatile components from the polymer solution obtained in step (2) in a vacuum chamber at 230° C. to remove residual solvents and monomers in the product, so that the organic volatiles in the product are less than 500 ppm to obtain a heat-resistant agent, the product mass is 72.01 kg, and the yield is 72%;

[0031] (4) 0.2 kg of the prepared heat-resistant agent, 0.25 kg of ABS graft copolymer (rubber content 60%), and 0.55 kg of styrene and acrylonitrile copolymer (SAN resin, brand AS-106) were mixed and melt-blended and granulated at 220° C. using a twin-screw extruder to obtain 1 kg of heat-resistant ABS resin.

[0032] Example 3

[0033] (1) After the negative pressure in the reactor was evacuated and replaced with nitrogen three times, 70 kg of polymerization monomer styrene, 15 kg of heat-resistant monomer N-phenylmaleimide, 15 kg of functional monomer maleic anhydride and 20 kg of solvent ethylbenzene were added, and stirring was started until the heat-resistant monomer N-phenylmaleimide was completely dissolved;

[0034] (2) The reactor of step (1) was heated to 140°C, and after the temperature stabilized, 0.01 kg of a tetrafunctional initiator was added to initiate the polymerization reaction. The temperature was kept stable during the reaction. After the reaction time was 1 hour, the temperature was raised to 160°C, and the reaction was continued for 1 hour to obtain a polymer solution;

[0035] (3) removing volatile components from the polymer solution obtained in step (2) in a vacuum chamber at 240° C. to remove residual solvents and monomers in the product, so that the organic volatiles in the product are less than 500 ppm to obtain a heat-resistant agent, the product mass is 71.01 kg, and the yield is 71%;

[0036] (4) 0.2 kg of the prepared heat-resistant agent, 0.25 kg of ABS graft copolymer (rubber content 60%), and 0.55 kg of styrene and acrylonitrile copolymer (SAN resin, brand AS-106) were mixed and melt-blended and granulated at 220°C using a twin-screw extruder to obtain 1 kg of heat-resistant ABS resin. Its glass transition temperature curve is as follows: Figure 2 As shown, the corresponding glass transition temperature is 175°C.

[0037] Example 4

[0038] (1) After the negative pressure in the reactor was evacuated and replaced with nitrogen three times, 75 kg of polymerization monomer styrene, 15 kg of heat-resistant monomer N-phenylmaleimide, 5 kg of functional monomer maleic anhydride, 5 kg of acrylonitrile, and 25 kg of solvent xylene were added, and stirring was started until the heat-resistant monomer N-phenylmaleimide was completely dissolved;

[0039] (2) The reactor of step (1) was heated to 140°C, and after the temperature stabilized, 0.01 kg of a tetrafunctional initiator was added to initiate the polymerization reaction. The temperature was kept stable during the reaction. After the reaction time was 1 hour, the temperature was raised to 160°C, and the reaction was continued for 1 hour to obtain a polymer solution;

[0040] (3) removing volatile components from the polymer solution obtained in step (2) in a vacuum chamber at 240° C. to remove residual solvents and monomers in the product, so that the organic volatiles in the product are less than 500 ppm to obtain a heat-resistant agent, the product mass is 71.01 kg, and the yield is 71%;

[0041] (4) 0.2 kg of the prepared heat-resistant agent, 0.25 kg of ABS graft copolymer (rubber content 60%), and 0.55 kg of styrene and acrylonitrile copolymer (SAN resin, brand AS-106) were mixed and melt-blended and granulated at 220° C. using a twin-screw extruder to obtain 1 kg of heat-resistant ABS resin.

[0042] Comparative Example 1

[0043] (1) After the negative pressure in the reactor was evacuated and replaced with nitrogen three times, 75 kg of polymerization monomer styrene, 25 kg of acrylonitrile and 25 kg of solvent xylene were added, and stirring was started;

[0044] (2) The reactor of step (1) was heated to 140°C, and after the temperature stabilized, 0.01 kg of a tetrafunctional initiator was added to initiate the polymerization reaction. The temperature was kept stable during the reaction. After the reaction time was 1 hour, the temperature was raised to 160°C, and the reaction was continued for 1 hour to obtain a polymer solution;

[0045] (3) removing volatile components from the polymer solution obtained in step (2) in a vacuum chamber at 240° C. to remove residual solvents and monomers in the product, so that the organic volatiles in the product are less than 500 ppm to obtain a heat-resistant agent, the product mass is 71.01 kg, and the yield is 71%;

[0046] (4) 0.2 kg of the prepared heat-resistant agent, 0.25 kg of ABS graft copolymer (rubber content 60%), and 0.55 kg of styrene and acrylonitrile copolymer (SAN resin, brand AS-106) were mixed and melt-blended and granulated at 220° C. using a twin-screw extruder to obtain 1 kg of heat-resistant ABS resin.

[0047] Comparative Example 2

[0048] (1) After the negative pressure in the reactor was evacuated and replaced with nitrogen three times, 75 kg of polymerization monomer styrene, 15 kg of heat-resistant monomer N-phenylmaleimide, 5 kg of functional monomer maleic anhydride, 5 kg of acrylonitrile, and 25 kg of solvent xylene were added, and stirring was started until the heat-resistant monomer N-phenylmaleimide was completely dissolved;

[0049] (2) The reactor of step (1) was heated to 90°C, and after the temperature stabilized, 0.1 kg of monofunctional initiator benzoyl peroxide was added to initiate the polymerization reaction. The temperature was kept stable during the reaction. After 3 hours of reaction, the temperature was raised to 140°C and the reaction was continued for 3 hours to obtain a polymer solution;

[0050] (3) removing volatile components from the polymer solution obtained in step (2) in a vacuum chamber at 230° C. to remove residual solvents and monomers in the product, so that the organic volatiles in the product are less than 500 ppm to obtain a heat-resistant agent, the product mass is 70.1 kg, and the yield is 70%;

[0051] (4) 0.2 kg of the prepared heat-resistant agent, 0.25 kg of ABS graft copolymer (rubber content 60%), and 0.55 kg of styrene and acrylonitrile copolymer (SAN resin, brand AS-106) were mixed and melt-blended and granulated at 220° C. using a twin-screw extruder to obtain 1 kg of heat-resistant ABS resin.

[0052] The heat-resistant ABS resin obtained in the above examples and comparative examples was prepared into standard notched impact specimens and tensile specimens according to ASTM D256 and ASTM D638 standards and tested, and was prepared into heat deformation temperature test specimens according to ASTM D648 standard and tested. The test results are shown in Table 1.

[0053] Table 1: Performance data of products of examples and comparative examples

[0054] Sample name Impact strength (J / m) Tensile strength(Mpa) Heat deformation temperature(℃) Example 1 165 62 85 Example 2 160 67 97 Example 3 155 65 91 Example 4 158 66 90 Comparative Example 1 175 42 79 Comparative Example 2 136 40 83

[0055] From the above data, it can be seen that after adding the heat-resistant monomer N-phenylmaleimide, the heat resistance (heat deformation temperature) of the ABS resin is significantly improved, and the tensile strength is also significantly improved. The impact strength of the heat-resistant ABS resin after using the tetrafunctional initiator is greater than 150 J / m, which meets the application requirements. When the initiator is changed (such as Comparative Example 2), the impact strength is significantly reduced, and the heat deformation temperature is not significantly improved.

Claims

1. A method for preparing a heat-resistant agent having a star-shaped structure, the steps of which are as follows: (1) After the negative pressure in the reactor is evacuated, the reactor is replaced with nitrogen 2 to 3 times, and 50 to 70 parts by weight of an aromatic vinyl monomer, 5 to 25 parts by weight of a heat-resistant monomer, 0 to 15 parts by weight of a functional monomer, and 15 to 30 parts by weight of a solvent are added, and the mixture is stirred until all the heat-resistant monomers are completely dissolved; (2) heating the reactor of step (1) to 90-140° C., adding 0.01-0.1 parts of a tetrafunctional initiator having a structural formula (I) after the temperature stabilizes, and initiating a polymerization reaction for 1-3 hours; then heating the reactor to 140-160° C. and continuing the reaction for 1-3 hours to obtain a polymer solution; (3) removing volatile components from the polymer solution obtained in step (2) under vacuum at 220-250° C., and then removing the residual solvent and monomer in the product to make the concentration of organic volatiles in the product less than 500 ppm, thereby obtaining the heat-resistant agent with a star-shaped structure, the structural formula of which is shown in (II):

2. The method for preparing a heat-resistant agent having a star-shaped structure according to claim 1, characterized in that: The aromatic vinyl monomer used in step (1) is one of styrene or a-methylstyrene or a mixture of the two, the heat-resistant monomer is N-phenylmaleimide, the functional monomer is one of acrylonitrile or maleic anhydride or a mixture of the two; and the solvent is one of toluene, ethylbenzene or xylene.

3. A heat-resistant agent having a star-shaped structure, characterized in that: The method is prepared by the method of claim 1 or 2.

4. Use of the heat-resistant agent with a star-shaped structure as claimed in claim 3 in the preparation of heat-resistant ABS resin.

5. The use of a heat-resistant agent having a star-shaped structure in the preparation of heat-resistant ABS resin according to claim 4, characterized in that: The heat-resistant ABS resin is obtained by mixing 10 to 20 parts by weight of a heat-resistant agent with a star structure, 25 to 30 parts by weight of an ABS graft copolymer, and 50 to 65 parts by weight of a styrene and acrylonitrile copolymer, and performing melt physical blending and granulation at 210 to 230° C. using a twin-screw extruder.

6. Use of a heat-resistant agent having a star-shaped structure in the preparation of heat-resistant ABS resin according to claim 5, characterized in that: In the ABS graft copolymer, the rubber mass content is 50-70%.

Images