A kind of polystyrene masterbatch and preparation method thereof

Abstract

The present invention relates to a polystyrene masterbatch and a preparation method thereof. The masterbatch is calculated by weight and comprises: 100 parts of polystyrene resin, 12-24 parts of modified PS microspheres, 55-85 parts of silane-modified pigments, 0.5-1.5 parts of lubricants and 0.1-1 parts of brighteners. The present invention prepares a polystyrene masterbatch, on the basis of polystyrene resin, modified PS microspheres, silane-modified pigments, lubricants and brighteners are added; wherein the modified PS microspheres can enhance the strength and toughness of the masterbatch, and also have a good enhancement on the heat resistance performance; the silane-modified pigment has better dispersibility than ordinary fillers, so that the masterbatch coloring is more uniform; the lubricant is used to enhance the ductility of the raw material, and the brightener can make the masterbatch pigment more colorful.

Description

Technical Field

[0001] The invention relates to the field of masterbatches, and in particular to a polystyrene masterbatch and a preparation method thereof. Background Art

[0002] Plastic coloring can be done by color powder coloring. The characteristics of color powder coloring are that the method of directly using color powder (pigment or dye) to add an appropriate amount of powdered additives to color plastic particles has the advantages of low cost and can be operated in small batches. However, its biggest disadvantage is that the pigment will fly during transportation, storage, weighing, and mixing, causing pollution and seriously affecting the working environment. Another headache for users is that the hopper of the extruder is not easy to clean. Masterbatch coloring overcomes the various disadvantages of color powder coloring, so masterbatch coloring is the most commonly used plastic coloring method today. Masterbatch, also called color species, is a new type of special colorant for polymer materials, also known as pigment preparation. Masterbatch is mainly used on plastics. Masterbatch is composed of three basic elements: pigment or dye, carrier and additive. It is an aggregate obtained by uniformly attaching an extraordinary amount of pigment to the resin. It can be called a pigment concentrate, so its coloring power is higher than the pigment itself. When processing, a small amount of masterbatch is mixed with uncolored resin to achieve a colored resin or product with a designed pigment concentration.

[0003] As one of the key raw materials in the plastic processing industry, masterbatch has a wide range of applications. Masterbatch is mainly composed of three parts: colorant, carrier, and dispersant. It is a polymer compound obtained by uniformly loading pigments in resin in an abnormal amount. During the production process, masterbatch often has some common defects, which affect the quality and appearance of plastic products. Polystyrene (PS) is a widely used general-purpose plastic with the characteristics of low price, excellent comprehensive performance, and easy processing and molding. However, polystyrene is brittle, has low impact strength, and poor heat resistance, which also leads to the defects of low strength, poor toughness, and insufficient heat resistance in the masterbatch prepared by it. Summary of the invention

[0004] In view of the problems existing in the prior art, the object of the present invention is to provide a polystyrene masterbatch and a preparation method thereof.

[0005] The purpose of the present invention is achieved by adopting the following technical solutions:

[0006] In a first aspect, the present invention provides a polystyrene masterbatch, calculated by weight, comprising:

[0007] 100 parts of polystyrene resin, 12-24 parts of modified PS microspheres, 55-85 parts of silane modified pigments, 0.5-1.5 parts of lubricants and 0.1-1 parts of brighteners.

[0008] Preferably, the grade of the polystyrene resin includes one of GPPS 666D, GPPS200D, GPPS 525 and GPPS206.

[0009] Preferably, the silane-modified pigment is a pigment treated with a silane coupling agent, and the specific treatment process includes:

[0010] Mix the pigment and silane coupling agent in a stirring machine, stir at room temperature for 0.5-1h, the stirring speed is 200-300rpm, and vacuum dry after stirring to complete the treatment.

[0011] Preferably, the pigment includes any one or a combination of permanent red F3RK, permanent yellow HGR, permanent orange G, phthalocyanine blue BGS, phthalocyanine green G, and permanent violet RL.

[0012] Preferably, the silane coupling agent is KH-570, and the mass ratio of the pigment to the silane coupling agent is 1:0.05-0.1.

[0013] Preferably, the lubricant is one of calcium stearate, magnesium stearate and zinc stearate.

[0014] Preferably, the brand of the whitening agent is fluorescent whitening agent RQT-A-4 or fluorescent whitening agent RQT-B-3.

[0015] Preferably, the preparation process of the modified PS microspheres comprises:

[0016] S1. Preparation of modifier:

[0017] Weigh allyl alcohol glycidyl ether and 3,4'-diaminobiphenyl ether, mix them in N,N-dimethylformamide, heat to 60-80°C, keep warm and stir for 4-10 hours, and after the reaction is completed, remove the solvent under reduced pressure to obtain a modifier;

[0018] S2. Preparation of modified PS microspheres:

[0019] Weigh styrene and modifier and add them to anhydrous ethanol, then add dispersant, stir until evenly dispersed, add initiator under nitrogen protection, heat to 65-85°C, stir and react for 15-20h, after the reaction is completed, separate the solid product by centrifugation, wash and dry to obtain modified PS microspheres.

[0020] Preferably, in S1, the mass ratio of allyl alcohol glycidyl ether, 3,4'-diaminobiphenyl ether and N,N-dimethylformamide is 2.3-4.6:2-4:30-50.

[0021] Preferably, in S2, the mass ratio of the modifier, styrene and anhydrous ethanol is 0.15-0.3:1:6-10.

[0022] Preferably, in S2, the dispersant is polyvinyl pyrrolidone or nonylphenol polyoxyethylene ether, and the added amount is 3%-10% of the mass of styrene.

[0023] Preferably, in S2, the initiator is azobisisobutyronitrile, and the added amount is 1.5%-3.5% of the mass of styrene.

[0024] Preferably, in S2, washing is performed by first rinsing with ethanol three times and then rinsing with pure water three times; and drying is performed by vacuum drying.

[0025] In a second aspect, the present invention provides a method for preparing a polystyrene masterbatch, comprising the following steps:

[0026] The first step is to weigh polystyrene resin and modified PS microspheres, add them into a stirring mixer, heat them to 160-200° C., and stir for 20-40 minutes to obtain a first mixture;

[0027] The second step is to add the silane-modified pigment, lubricant and brightener to the first mixture, raise the temperature to 210-220° C., and continue stirring for 20-30 minutes to obtain a second mixture;

[0028] The third step is to feed the second mixed material into a twin-screw extruder, extrude and granulate at 260-280° C. to obtain polystyrene masterbatch.

[0029] The beneficial effects of the present invention are:

[0030] 1. The present invention prepares a polystyrene masterbatch, on the basis of polystyrene resin, added with modified PS microspheres, silane-modified pigments, lubricants and whitening agents; wherein the modified PS microspheres can enhance the strength and toughness of the masterbatch, and also have a good enhancement on the heat resistance performance; the silane-modified pigment has better dispersibility than ordinary fillers, so that the masterbatch color is more uniform; the lubricant is used to enhance the ductility of the raw material, and the whitening agent can make the masterbatch pigment more colorful.

[0031] 2. The modified PS microspheres used in the present invention are prepared by reacting allyl alcohol glycidyl ether with 3,4'-diaminobiphenyl ether to form an epoxy-amino bond to obtain a modifier containing a double bond and a biphenyl ether bond, and the modifier is prepared into microspheres by co-polymerization with styrene to finally obtain modified PS microspheres. Compared with traditional PS microspheres, the present invention introduces a biphenyl ether bond group into the microspheres. Subsequent testing has found that the microspheres have better improvements in the strength, toughness and heat resistance of the masterbatch.

[0032] 3. The preparation process of the silane-modified pigment of the present invention is to mix the silane coupling agent KH-570 into the traditional pigment, the purpose of which is to improve the color and dispersibility of the pigment, thereby enhancing the color performance in the masterbatch. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention is further described using the accompanying drawings, but the embodiments in the accompanying drawings do not constitute any limitation to the present invention. A person skilled in the art can obtain other drawings based on the following drawings without creative work.

[0034] Figure 1 Schematic diagram of infrared spectrum (IR) of modified PS microspheres prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is described below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to limit the scope of the present invention. The change or adjustment of the relative relationship thereof shall also be regarded as the scope of the present invention without substantially changing the technical content.

[0036] In order to better understand the above technical scheme, the exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0037] The present invention will be further described below in conjunction with the following examples.

[0038] Example 1

[0039] A polystyrene masterbatch, calculated by weight, comprising:

[0040] 100 parts of polystyrene resin, 18 parts of modified PS microspheres, 70 parts of silane-modified pigments, 1 part of lubricant and 0.5 parts of brightener.

[0041] The brand of the polystyrene resin is GPPS 666D, the silane-modified pigment is a pigment treated with a silane coupling agent, the lubricant is calcium stearate, and the brand of the brightener is fluorescent brightener RQT-A-4.

[0042] Among them, the specific processing process of silane-modified pigments includes:

[0043] Mix the pigment permanent red F3RK and the silane coupling agent KH-570 in a stirring machine, the mass ratio of the pigment to the silane coupling agent is 1:0.08, stir at room temperature for 0.8h, the stirring speed is 250rpm, and vacuum dry after stirring to complete the treatment.

[0044] The preparation process of modified PS microspheres includes:

[0045] S1. Preparation of modifier:

[0046] Weigh allyl alcohol glycidyl ether and 3,4'-diaminobiphenyl ether and mix them in N,N-dimethylformamide, the mass ratio of allyl alcohol glycidyl ether, 3,4'-diaminobiphenyl ether and N,N-dimethylformamide is 3.5:3:40, heat to 70°C, keep stirring for 6 hours, after the reaction is completed, remove the solvent under reduced pressure to obtain a modifier;

[0047] S2. Preparation of modified PS microspheres:

[0048] Weigh styrene and a modifier and add them to anhydrous ethanol. The mass ratio of the modifier, styrene and anhydrous ethanol is 0.23:1:8. Then add polyvinyl pyrrolidone in an amount of 7% of the mass of styrene. After stirring until uniformly dispersed, add azobisisobutyronitrile under the protection of nitrogen in an amount of 2.5% of the mass of styrene. Heat to 75°C and stir to react for 18 hours. After the reaction is completed, separate the solid product by centrifugation, rinse it three times with ethanol, then rinse it three times with pure water, and dry it in vacuum to obtain modified PS microspheres.

[0049] Figure 1 Schematic diagram of modified PS microspheres. Figure 1 It can be seen that at 1210-1310cm -1 The vibration peaks that appear are typical ether bond COC stretching vibration peaks, at 1550-1620cm -1 The stretching vibration peak caused by the CN bond appears, so it can be explained that the co-polymerization of the modifier and styrene has been completed in this embodiment.

[0050] The method for preparing the polystyrene masterbatch comprises the following steps:

[0051] In the first step, polystyrene resin and modified PS microspheres are weighed and added into a stirring mixer, the temperature is raised to 180° C., and stirred for 30 minutes to obtain a first mixture;

[0052] The second step is to add the silane-modified pigment, lubricant and brightener into the first mixture, raise the temperature to 210° C., and continue stirring for 20 minutes to obtain a second mixture;

[0053] The third step is to feed the second mixed material into a twin-screw extruder, extrude and granulate at 260-280° C. to obtain polystyrene masterbatch.

[0054] Example 2

[0055] A polystyrene masterbatch, calculated by weight, comprising:

[0056] 100 parts of polystyrene resin, 12 parts of modified PS microspheres, 85 parts of silane-modified pigments, 0.5 parts of lubricants and 0.1 parts of brighteners.

[0057] The brand of polystyrene resin is GPPS200D, the silane-modified pigment is a pigment treated with a silane coupling agent, the lubricant is magnesium stearate, and the brand of whitening agent is fluorescent whitening agent RQT-B-3.

[0058] The specific processing of silane-modified pigments includes:

[0059] Mix the pigment permanent yellow HGR and the silane coupling agent KH-570 in a mixing machine, the mass ratio of the pigment to the silane coupling agent is 1:0.05, stir for 0.5h at room temperature, the stirring speed is 200rpm, and vacuum dry after stirring to complete the treatment.

[0060] The preparation process of modified PS microspheres includes:

[0061] S1. Preparation of modifier:

[0062] Weigh allyl alcohol glycidyl ether and 3,4'-diaminobiphenyl ether and mix them in N,N-dimethylformamide, the mass ratio of allyl alcohol glycidyl ether, 3,4'-diaminobiphenyl ether and N,N-dimethylformamide is 2.3:2:30, heat to 60°C, keep stirring for 4-10 hours, and after the reaction is completed, remove the solvent under reduced pressure to obtain a modifier;

[0063] S2. Preparation of modified PS microspheres:

[0064] Styrene and a modifier are weighed and added to anhydrous ethanol, the mass ratio of the modifier, styrene and anhydrous ethanol is 0.15-0.3:1:6-10, and then nonylphenol polyoxyethylene ether is added in an amount of 3%-10% of the mass of styrene. After stirring until uniform dispersion, azobisisobutyronitrile is added under the protection of nitrogen in an amount of 1.5%-3.5% of the mass of styrene. The temperature is raised to 65-85° C. and stirred for reaction for 15-20 hours. After the reaction is completed, the solid product is separated by centrifugation, first rinsed with ethanol three times, then rinsed with pure water three times, and vacuum dried to obtain modified PS microspheres.

[0065] The method for preparing the polystyrene masterbatch comprises the following steps:

[0066] The first step is to weigh polystyrene resin and modified PS microspheres, add them into a stirring mixer, heat them to 160-200° C., and stir for 20-40 minutes to obtain a first mixture;

[0067] The second step is to add the silane-modified pigment, lubricant and brightener to the first mixture, raise the temperature to 210-220° C., and continue stirring for 20-30 minutes to obtain a second mixture;

[0068] The third step is to feed the second mixed material into a twin-screw extruder, extrude and granulate at 260-280° C. to obtain polystyrene masterbatch.

[0069] Example 3

[0070] A polystyrene masterbatch, calculated by weight, comprising:

[0071] 100 parts of polystyrene resin, 24 parts of modified PS microspheres, 55 parts of silane-modified pigments, 1.5 parts of lubricants and 1 part of brighteners.

[0072] The brand of the polystyrene resin is GPPS 525, the silane-modified pigment is a pigment treated with a silane coupling agent, the lubricant is zinc stearate, and the brand of the brightener is fluorescent brightener RQT-B-3.

[0073] The specific processing of silane-modified pigments includes:

[0074] Mix the pigment phthalocyanine blue BGS and the silane coupling agent KH-570 in a stirring machine, the mass ratio of the pigment to the silane coupling agent is 1:0.05, stir at room temperature for 1 hour, the stirring speed is 300rpm, and vacuum dry after stirring to complete the treatment.

[0075] The preparation process of modified PS microspheres includes:

[0076] S1. Preparation of modifier:

[0077] Weigh allyl alcohol glycidyl ether and 3,4'-diaminobiphenyl ether and mix them in N,N-dimethylformamide, the mass ratio of allyl alcohol glycidyl ether, 3,4'-diaminobiphenyl ether and N,N-dimethylformamide is 4.6:4:50, heat to 80°C, keep stirring for 10 hours, and after the reaction is completed, remove the solvent under reduced pressure to obtain a modifier;

[0078] S2. Preparation of modified PS microspheres:

[0079] Weigh styrene and a modifier and add them to anhydrous ethanol. The mass ratio of the modifier, styrene and anhydrous ethanol is 0.3:1:10. Then add polyvinyl pyrrolidone in an amount of 10% of the mass of styrene. After stirring until uniformly dispersed, add azobisisobutyronitrile under the protection of nitrogen in an amount of 3.5% of the mass of styrene. Heat to 85°C and stir to react for 20 hours. After the reaction is completed, separate the solid product by centrifugation, rinse it three times with ethanol, then rinse it three times with pure water, and dry it in vacuum to obtain modified PS microspheres.

[0080] The method for preparing the polystyrene masterbatch comprises the following steps:

[0081] In the first step, polystyrene resin and modified PS microspheres are weighed and added into a stirring mixer, the temperature is raised to 200° C., and stirred for 40 minutes to obtain a first mixture;

[0082] The second step is to add the silane-modified pigment, lubricant and brightener into the first mixture, raise the temperature to 220° C., and continue stirring for 30 minutes to obtain a second mixture;

[0083] The third step is to feed the second mixed material into a twin-screw extruder, extrude and granulate at 260-280° C. to obtain polystyrene masterbatch.

[0084] Comparative Example 1

[0085] A polystyrene masterbatch, which differs from Example 1 in that the modified PS microspheres are replaced by PS microspheres.

[0086] The preparation process of PS microspheres includes:

[0087] Weigh styrene and add it to anhydrous ethanol. The mass ratio of styrene to anhydrous ethanol is 1:8. Then add polyvinyl pyrrolidone in an amount of 7% of the mass of styrene. After stirring until uniformly dispersed, add azobisisobutyronitrile under the protection of nitrogen in an amount of 2.5% of the mass of styrene. Heat to 75°C and stir to react for 18 hours. After the reaction is completed, separate the solid product by centrifugation, rinse it three times with ethanol, then rinse it three times with pure water, and dry it in vacuum to obtain PS microspheres.

[0088] Comparative Example 2

[0089] A polystyrene masterbatch, which is different from Example 1 in that the preparation method of the modified PS microspheres is different and the modifier is replaced by allyl alcohol glycidyl ether.

[0090] The preparation process of modified PS microspheres includes:

[0091] Styrene and allyl alcohol glycidyl ether were weighed and added to anhydrous ethanol. The mass ratio of allyl alcohol glycidyl ether, styrene and anhydrous ethanol was 0.23:1:8. Polyvinyl pyrrolidone was added in an amount of 7% of the mass of styrene. After stirring until uniform dispersion, azobisisobutyronitrile was added under the protection of nitrogen in an amount of 2.5% of the mass of styrene. The temperature was raised to 75°C and the reaction was stirred for 18 hours. After the reaction was completed, the solid product was separated by centrifugation, rinsed three times with ethanol, then rinsed three times with pure water, and dried in vacuo to obtain modified PS microspheres.

[0092] Comparative Example 3

[0093] A polystyrene masterbatch, which is different from Example 1 in that the preparation method of the modified PS microspheres is different and the modifier is replaced by 3,4'-diaminodiphenyl ether.

[0094] The preparation process of modified PS microspheres includes:

[0095] Styrene and 3,4'-diaminobiphenyl ether were weighed and added to anhydrous ethanol. The mass ratio of 3,4'-diaminobiphenyl ether, styrene and anhydrous ethanol was 0.23:1:8. Polyvinyl pyrrolidone was added in an amount of 7% of the mass of styrene. After stirring until uniform dispersion, azobisisobutyronitrile was added under the protection of nitrogen in an amount of 2.5% of the mass of styrene. The temperature was raised to 75°C and the reaction was stirred for 18 hours. After the reaction was completed, the solid product was separated by centrifugation, rinsed three times with ethanol, then rinsed three times with pure water, and vacuum dried to obtain modified PS microspheres.

[0096] The properties of the polystyrene masterbatches prepared in Example 1 and Comparative Examples 1-3 were tested respectively, and the results are listed in the table. The tensile strength and elongation at break were tested with reference to GB / T 1040, the impact strength was tested with reference to GB / T 1843, and the flexural strength was tested with reference to GB / T 9341. The test results are detailed in Table 1:

[0097] Table 1 Performance of different masterbatches

[0098] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Tensile strength(MPa) 32.8 24.5 27.3 25.9 Elongation at break (%) 11.5 8.3 9.1 8.8 Bending strength(MPa) 53.4 41.7 48.5 44.2 <![CDATA[Izod impact strength of cantilever beam (kJ / m 2 )]]> 13.8 9.7 11.3 10.6 Heat deformation temperature(℃) 97 84 89 92

[0099] It can be seen from Table 1 that the masterbatch prepared in Example 1 has stronger comprehensive performance, higher strength, stronger toughness, and better heat resistance.

[0100] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily being directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0101] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A polystyrene masterbatch, characterized in that: Calculated by weight, including: 100 parts of polystyrene resin, 12-24 parts of modified PS microspheres, 55-85 parts of silane modified pigments, 0.5-1.5 parts of lubricants and 0.1-1 parts of brighteners; The preparation process of the modified PS microspheres comprises: S1. Preparation of modifier: Weigh allyl alcohol glycidyl ether and 3,4'-diaminobiphenyl ether, mix them in N,N-dimethylformamide, heat to 60-80°C, keep warm and stir for 4-10 hours, and after the reaction is completed, remove the solvent under reduced pressure to obtain a modifier; S2. Preparation of modified PS microspheres: Weigh styrene and modifier and add them to anhydrous ethanol, then add dispersant, stir until evenly dispersed, add initiator under nitrogen protection, heat to 65-85°C, stir and react for 15-20h, after the reaction is completed, separate the solid product by centrifugation, wash and dry to obtain modified PS microspheres.

2. A polystyrene masterbatch according to claim 1, characterized in that: The grades of the polystyrene resin include one of GPPS 666D, GPPS 200D, GPPS 525 and GPPS 206.

3. A polystyrene masterbatch according to claim 1, characterized in that: The silane-modified pigment is a pigment treated with a silane coupling agent, and the specific treatment process includes: The pigment and the silane coupling agent are mixed in a stirring machine, stirred at room temperature for 0.5-1h, the stirring speed is 200-300rpm, and vacuum dried after the stirring is completed, and the treatment is completed; the silane coupling agent is KH-570, and the mass ratio of the pigment to the silane coupling agent is 1:0.05-0.

1.

4. A polystyrene masterbatch according to claim 3, characterized in that: The pigment includes any one or a combination of permanent red F3RK, permanent yellow HGR, permanent orange G, phthalocyanine blue BGS, phthalocyanine green G, and permanent violet RL.

5. The polystyrene masterbatch according to claim 1, characterized in that: The lubricant is one of calcium stearate, magnesium stearate and zinc stearate.

6. A polystyrene masterbatch according to claim 1, characterized in that: The brand of the whitening agent is fluorescent whitening agent RQT-A-4 or fluorescent whitening agent RQT-B-3.

7. A polystyrene masterbatch according to claim 1, characterized in that: In the S1, the mass ratio of allyl alcohol glycidyl ether, 3,4'-diaminobiphenyl ether and N,N-dimethylformamide is 2.3-4.6:2-4:30-50.

8. A polystyrene masterbatch according to claim 7, characterized in that: In S2, the mass ratio of the modifier, styrene and anhydrous ethanol is 0.15-0.3:1:6-10; the dispersant is polyvinyl pyrrolidone or nonylphenol polyoxyethylene ether, and the added amount is 3%-10% of the mass of styrene; the initiator is azobisisobutyronitrile, and the added amount is 1.5%-3.5% of the mass of styrene.

9. A method for preparing the polystyrene masterbatch according to claim 1, characterized in that: The following steps are involved: The first step is to weigh polystyrene resin and modified PS microspheres, add them into a stirring mixer, heat them to 160-200° C., and stir for 20-40 minutes to obtain a first mixture; The second step is to add the silane-modified pigment, lubricant and brightener to the first mixture, raise the temperature to 210-220° C., and continue stirring for 20-30 minutes to obtain a second mixture; The third step is to feed the second mixed material into a twin-screw extruder, extrude and granulate at 260-280° C. to obtain polystyrene masterbatch.

Images