A transparent low-temperature injection-molded polycarbonate and its preparation method and application

Abstract

The present invention relates to a transparent, low-temperature injection-molded polycarbonate, its preparation method, and application, and relates to the technical field of polymer materials. The polycarbonate comprises the following raw materials by mass: 25-75% of a first polycarbonate, 2-7% of a plasticizer, 0.5-1.5% of an antioxidant, 0.3-0.7% of a lubricant, and the remainder being a second polycarbonate; the melt flow index (MI) of the first polycarbonate is 10 g / 10 min, and the melt flow index (MI) of the second polycarbonate is 60 g / 10 min. The polycarbonate retains both the high heat resistance and transparency of the original polycarbonate, and by improving its fluidity while lowering the original plasticizing temperature of the polycarbonate, it can be applied to a PET substrate film, thereby resolving the technical problem of puncturing the ink layer of the film.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, in particular to a transparent low-temperature injection-molded polycarbonate and a preparation method and application thereof. Background Art

[0002] In recent years, people have increasingly higher requirements for personalized car interiors, especially the interior lighting atmosphere is increasingly loved by modern young people. Therefore, developing interiors with a sense of technology and fun is a trend in the future development of car interiors.

[0003] One of the technologies currently giving automotive interiors a sense of technology and personalization is in-film transfer printing. Depending on the combination of film and plastic, in-film transfer printing can create diverse effects, such as patterns and variable lighting atmospheres. Currently, depending on the film pattern and the transparent material, the lighting can be adjustable and applied to various locations within the car, such as ambient lighting, trim panels, and instrument panels. This allows the interior of the car to display different cool effects and lighting effects according to the needs of different users.

[0004] The current pain point of this technology lies in the diaphragm. Research shows that the diaphragms used in China are largely imported and relatively expensive. The diaphragms primarily consist of a substrate layer, an ink layer, and an outer protective layer. PET and PC-based diaphragms are currently the most popular on the market. Due to the higher cost of PC-based films, PET-based films are more commonly used. The diaphragm, combined with a transparent substrate and lighting, offers numerous innovative uses in automotive interiors. However, due to the limited availability of transparent materials for automotive interiors, and the increasing demand for odor and VOC control in automotive interiors, the demand for purer, less odorous, and less volatile plastic substrates is becoming increasingly stringent. Polycarbonate (PC) is a suitable material choice, offering excellent transparency and meeting the heat resistance, volatility, and odor requirements of automotive interiors. However, its injection molding temperature is relatively high, generally requiring 280-300°C. Since the film transfer is to fuse the film with the plastic substrate, the most commonly used films are PET-based films, whose operating temperature is generally 230-260℃, while the injection molding temperature of transparent substrates is generally 280-300℃. Therefore, if the commonly used PC injection molding is directly used for lamination, the high temperature will easily break through the PET substrate and cause the ink layer of the film to be stamped. Summary of the Invention

[0005] In response to the above technical problems, the present invention provides a transparent low-temperature injection-molded polycarbonate, which can retain both the high heat resistance and transparency of the original polycarbonate. By improving the fluidity and lowering the plasticizing temperature of the original polycarbonate, it can achieve the effect of laminating on the PET substrate film, thereby solving the technical problem of punching out the ink layer of the film.

[0006] In order to achieve the above object, the present invention provides a transparent low-temperature injection-molded polycarbonate, which comprises the following raw materials in percentage by mass:

[0007]

[0008]

[0009] The melt flow index (MI) of the first polycarbonate is 10 g / 10 min, and the melt flow index (MI) of the second polycarbonate is 60 g / 10 min.

[0010] The two polycarbonates with different melt flow indexes are used as raw materials. The polycarbonate with a melt flow index (MI) of 10g / 10min can stabilize the material's impact resistance, preventing the material from becoming brittle and unusable. The polycarbonate with a melt flow index (MI) of 60g / 10min can improve the material's fluidity, lowering the injection temperature while ensuring full injection. At the same time, because plasticizers reduce the material's heat resistance, the addition of the polycarbonate with a melt flow index (MI) of 60g / 10min can reduce the amount of plasticizer used. By using two polycarbonates with different melt flow indexes as raw materials, a balance between the material's heat resistance and fluidity can be maintained. The test conditions for the above melt flow index are 300°C*1.2kg.

[0011] In one embodiment, the first polycarbonate is bisphenol A polycarbonate with a relative molecular weight of 20,000-28,000.

[0012] The polycarbonate with the above relative molecular weight has a better matching effect with its melt flow index.

[0013] In one embodiment, the second polycarbonate is bisphenol A polycarbonate with a relative molecular weight of 10,000-15,000.

[0014] The polycarbonate with the above relative molecular weight has a good matching effect with its melt flow index. The polycarbonate has a low molecular weight and high fluidity, and is a CD-grade PC.

[0015] In one embodiment, the plasticizer is an oligomeric aryl phosphate.

[0016] In one embodiment, the molecular weight of the oligomeric aryl phosphate is 100-1000.

[0017] Using oligomeric aryl phosphates as plasticizers can improve the fluidity of the material and reduce the injection molding temperature of the material. Because the molecular weight of the oligomeric aryl phosphates is relatively small, it does not affect the transparency of the material. However, the addition of the plasticizer will reduce the heat resistance of the material. Therefore, the amount of the plasticizer needs to be controlled and balanced with the compounding of polycarbonates with different melt flow indexes to ensure that the material ultimately has both high fluidity and high heat resistance while maintaining transparency and achieving low-temperature injection molding.

[0018] In one embodiment, the antioxidant includes a first antioxidant and a second antioxidant, and the weight ratio of the first antioxidant to the second antioxidant is 1:1;

[0019] The first antioxidant comprises at least one of the following raw materials: 2,6-di-tert-butyl-4-methylphenol, or β-(3,5-di-tert-butyl-4-hydroxy-phenyl) propionate;

[0020] The second antioxidant comprises at least one of the following raw materials: dilauryl thiodipropionate, distearyl thiodipropionate, tris(2,4-di-tert-butylphenyl)phosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, or distearyl pentaerythritol diphosphite.

[0021] The use of the above antioxidants can improve the appearance of the material and delay aging degradation, and the use of the above two antioxidants for synergistic antioxidant effect can effectively improve the antioxidant effect of the material.

[0022] In one embodiment, the lubricant comprises at least one of the following raw materials: silane polymer, fatty acid salt, fatty acid amide, stearic acid, butyl stearate, oleamide, ethylene bisstearamide, or polyolefin wax.

[0023] The use of the above lubricant can improve the processing fluidity of the material, thereby reducing viscosity and heat loss during the processing, and improving the processing performance of the material.

[0024] The present invention also provides a method for preparing the polycarbonate, comprising the following steps:

[0025] The first polycarbonate, the second polycarbonate, a plasticizer, an antioxidant and a lubricant are mixed, extruded and granulated to obtain a transparent polycarbonate capable of low-temperature injection molding.

[0026] In one embodiment, the extrusion temperature of the extrusion granulation is 230-250° C., and the screw speed of the extrusion granulation is 400-600 rpm.

[0027] The extrusion temperature in the above preparation method cannot be too high. If the temperature is too high, the plasticizer will be plasticized quickly at a higher temperature, while polycarbonate plasticizes slowly, causing the plasticizer to melt and flow out first, resulting in uneven mixing in the material.

[0028] The present invention also provides an automobile interior trim, which is prepared by using the PET substrate film and the polycarbonate.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention discloses a transparent, low-temperature injection-molded polycarbonate, as well as its preparation method and application. This polycarbonate utilizes polycarbonates with different melt flow indices and plasticizers as raw materials, improving the material's fluidity while retaining both the high heat resistance and transparency inherent in polycarbonate. The thermoplasticization temperature is also lowered, reducing the original injection molding temperature of polycarbonate from 280-300°C to 230-250°C, approaching the operating temperature of PET-based films. This allows for lamination onto PET-based films, resolving the technical issue of punching patterns into the film's ink layer. Automotive interiors produced using this polycarbonate meet high heat resistance requirements, achieving a Vicat softening point (B50) above 120°C, and can be used in the production of ambient lighting, instrument panels, and the like. The preparation method is simple and easy to implement, facilitating stable production. DETAILED DESCRIPTION

[0031] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the relevant embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0033] source:

[0034] Unless otherwise specified, the reagents, materials, and equipment used in this example are all commercially available; and the experimental methods, unless otherwise specified, are all conventional experimental methods in the art.

[0035] The raw materials and their weight parts and mass percentages of each embodiment of the present invention are shown in the following table.

[0036] Table 1 Raw materials and their weight parts and mass percentages of various embodiments of the present invention

[0037]

[0038]

[0039]

[0040] In the embodiments and comparative examples in the above table, the first polycarbonate is PC resin MI10, the test conditions are 300°C*1.2kg, bisphenol A polycarbonate, and the relative molecular weight is 23000; the second polycarbonate is PC resin MI10, the test conditions are 300°C*1.2kg, bisphenol A polycarbonate, and the relative molecular weight is 23000; the plasticizer is oligomeric aromatic phosphate; the antioxidant is a mixture of 2,6-di-tert-butyl-4-methylphenol and distearate thiodipropionate, with a mass ratio of 1:1; and the lubricant is butyl stearate.

[0041] Note: “ / ” in the above table means that the raw material is not contained.

[0042] Example 1

[0043] A transparent low-temperature injection-molded polycarbonate and a preparation method thereof.

[0044] The raw materials were weighed according to Table 1, mixed to obtain a mixture, and added to a twin-screw extruder for twin-screw extrusion granulation at an extrusion temperature of 230° C. and a screw speed of 400 rpm to obtain a transparent low-temperature injection-molded polycarbonate.

[0045] Example 2

[0046] A transparent low-temperature injection-molded polycarbonate and a preparation method thereof.

[0047] The raw materials were weighed according to Table 1, mixed to obtain a mixture, and added to a twin-screw extruder for twin-screw extrusion granulation at an extrusion temperature of 230° C. and a screw speed of 400 rpm to obtain a transparent low-temperature injection-molded polycarbonate.

[0048] Example 3

[0049] A transparent low-temperature injection-molded polycarbonate and a preparation method thereof.

[0050] The raw materials were weighed according to Table 1, mixed to obtain a mixture, and added to a twin-screw extruder for twin-screw extrusion granulation at an extrusion temperature of 230° C. and a screw speed of 400 rpm to obtain a transparent low-temperature injection-molded polycarbonate.

[0051] Example 4

[0052] A transparent low-temperature injection-molded polycarbonate and a preparation method thereof.

[0053] The raw materials were weighed according to Table 1, mixed to obtain a mixture, and added to a twin-screw extruder for twin-screw extrusion granulation at an extrusion temperature of 230° C. and a screw speed of 400 rpm to obtain a transparent low-temperature injection-molded polycarbonate.

[0054] Example 5

[0055] A transparent low-temperature injection-molded polycarbonate and a preparation method thereof.

[0056] The raw materials were weighed according to Table 1, mixed to obtain a mixture, and added to a twin-screw extruder for twin-screw extrusion granulation at an extrusion temperature of 230° C. and a screw speed of 400 rpm to obtain a transparent low-temperature injection-molded polycarbonate.

[0057] Example 6

[0058] A transparent low-temperature injection-molded polycarbonate and a preparation method thereof.

[0059] The raw materials were weighed according to Table 1, mixed to obtain a mixture, and added to a twin-screw extruder for twin-screw extrusion granulation at an extrusion temperature of 230° C. and a screw speed of 400 rpm to obtain a transparent low-temperature injection-molded polycarbonate.

[0060] Example 7

[0061] A transparent low-temperature injection-molded polycarbonate and a preparation method thereof.

[0062] The raw materials were weighed according to Table 1, mixed to obtain a mixture, and added to a twin-screw extruder for twin-screw extrusion granulation at an extrusion temperature of 230° C. and a screw speed of 400 rpm to obtain a transparent low-temperature injection-molded polycarbonate.

[0063] Comparative Example 1

[0064] A polycarbonate and a preparation method thereof.

[0065] The raw materials were weighed according to Table 1, mixed to obtain a mixture, and added to a twin-screw extruder for twin-screw extrusion granulation at an extrusion temperature of 230° C. and a screw speed of 400 rpm to obtain polycarbonate.

[0066] Comparative Example 2

[0067] A polycarbonate and a preparation method thereof.

[0068] The raw materials were weighed according to Table 1, mixed to obtain a mixture, and added to a twin-screw extruder for twin-screw extrusion granulation at an extrusion temperature of 230° C. and a screw speed of 400 rpm to obtain polycarbonate.

[0069] Comparative Example 3

[0070] A polycarbonate and a preparation method thereof.

[0071] The raw materials were weighed according to Table 1, mixed to obtain a mixture, and added to a twin-screw extruder for twin-screw extrusion granulation at an extrusion temperature of 230° C. and a screw speed of 400 rpm to obtain polycarbonate.

[0072] Comparative Example 4

[0073] A polycarbonate and a preparation method thereof.

[0074] The raw materials were weighed according to Table 1, mixed to obtain a mixture, and added to a twin-screw extruder for twin-screw extrusion granulation at an extrusion temperature of 230° C. and a screw speed of 400 rpm to obtain polycarbonate.

[0075] Comparative Example 5

[0076] A polycarbonate and a preparation method thereof.

[0077] The raw materials were weighed according to Table 1, mixed to obtain a mixture, and added to a twin-screw extruder for twin-screw extrusion granulation at an extrusion temperature of 230° C. and a screw speed of 400 rpm to obtain polycarbonate.

[0078] Comparative Example 6

[0079] A polycarbonate and a preparation method thereof.

[0080] The raw materials were weighed according to Table 1, mixed to obtain a mixture, and added to a twin-screw extruder for twin-screw extrusion granulation at an extrusion temperature of 230° C. and a screw speed of 400 rpm to obtain polycarbonate.

[0081] Comparative Example 7

[0082] A polycarbonate and a preparation method thereof.

[0083] The raw materials were weighed according to Table 1, mixed to obtain a mixture, and added to a twin-screw extruder for twin-screw extrusion granulation at an extrusion temperature of 230° C. and a screw speed of 400 rpm to obtain polycarbonate.

[0084] Experimental example

[0085] The performance of the polycarbonate materials obtained in each embodiment and comparative example was tested.

[0086] 1. Test method

[0087] 1. Charpy notched impact: 23°C, 4J, using ISO 179: Standard test method for Charpy impact properties of plastics.

[0088] 2. Melt flow rate: 300°C, 1.2 kg, using ISO 1133: Melt flow rate.

[0089] 3. Vicat softening point: B50, tested using ISO 306: Vicat softening point temperature.

[0090] 4. Light transmittance: tested on 3mm thick board, using GB / T 2410-2008, light source C.

[0091] 5. Injection temperature: 250℃, low speed, injection molding of 356*100*3mm board, determine whether the sample is fully injected under the same process.

[0092] 2. Test results

[0093] Table 2 Test results of polycarbonate in various embodiments and comparative examples

[0094]

[0095] Results analysis: From the test results of the above comparative examples, it can be seen that when using low melt index PC (MI10) alone, all properties are very good, but due to poor fluidity, the board cannot be fully injection molded at 250℃. Although Comparative Example 7 also uses low melt index PC (MI10) alone, it can fully injection mold the board at 250℃, but it is necessary to increase the amount of plasticizer at the same time. When using high flow PC (MI60) alone, although the material can be fully injection molded at 250℃, due to the relatively low notch impact, the toughness of the material is relatively poor, and the injection molded board is brittle and cannot be used directly. Therefore, neither high flow nor low flow PC can be used directly alone. In addition, by compounding high melt index PC (MI10) and low melt index PC (MI60) (Comparative Examples 3-5) to balance the fluidity and toughness of the material, it is found that no matter which material is compounded, the melt index of the material is lower than that of high flow PC (MI60), and it is impossible to fully inject when injection molded at 250℃ and cannot be used normally. At the same time, high-flow PC, low-flow PC or compounding will not affect the heat resistance and transparency of the material.

[0096] Plasticizers are polymers with relatively small molecular weights. Their working principle is that small molecules of plasticizers are inserted between polymer chains. For example, if a plasticizer is added to polycarbonate (PC) and heated, the plasticizer is inserted into the middle of the polycarbonate, which can weaken the interaction between the polycarbonates, thereby improving the plasticity and flexibility of the polycarbonate and reducing the processing temperature of the polycarbonate. Comparative Examples 6 and 7 show that adding plasticizers improves the fluidity of the material and reduces the injection molding temperature. When using plasticizers, the fluidity of the material increases. The higher the amount added, the more the fluidity increases. Therefore, when 10 parts are added, full injection molding can be achieved at 250°C. However, if too much is added, the heat resistance and toughness of the material will be significantly reduced, and it cannot meet normal use. When 5 parts of plasticizer are added, the heat resistance of the material is around 120°C, which basically meets the requirements. Therefore, it is not recommended to add more than 5 parts of plasticizer.

[0097] The test results of the above examples show that, for Examples 1-4, the addition of 3 parts of plasticizer improves heat resistance and light transmittance, and Examples 1-3 can be fully injection molded at 250°C, while Example 4 cannot fully injection mold. However, by compounding high and low melt index PCs, it can be seen that Example 1 has a higher melt index, but poor toughness, resulting in brittle injection molded panels that cannot be used properly. Examples 2 and 3 have high heat resistance and good toughness, and can also be fully injection molded at 250°C, showing good overall performance. However, as the compound melt index decreases (as in Example 4), the melt index drops further, and full injection molding is no longer possible. However, for Examples 5, 6, and 7, it can be seen that increasing the plasticizer to 5 parts significantly reduces the heat resistance of the materials, reaching the edge of normal use. Furthermore, at higher compound melt indexes (as in Example 5), the toughness of the materials decreases significantly, resulting in brittle panels that cannot be used properly. As the compound melt index decreases, when the melt index reaches 40 (Example 7), the toughness is acceptable, but full injection molding is no longer possible.

[0098] At the same time, if the Vicat temperature of the material is required to be above 120°C, the maximum amount of plasticizer added is 5 parts. The addition of plasticizer can be inserted between polycarbonate chains during the modification process to weaken the intermolecular forces of polycarbonate and improve the plasticity and flexibility of the material. However, the addition of plasticizer will reduce the Tg of the material. At the same time, the addition of plasticizer increases the intermolecular forces of polycarbonate and increases the plasticity, while reducing the toughness. Therefore, the heat resistance and impact resistance of the material will be reduced in terms of material properties, especially the heat resistance of the material. By adding 3 or 5 parts, the compound melt index must be at least 40 to achieve full injection molding. In addition, the impact of plasticizer and increased fluidity on the impact of the material must be taken into account. Therefore, in summary, implementation cases 2, 3, and 6 are better solutions.

[0099] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0100] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A transparent low-temperature injection-molded polycarbonate, characterized in that: The polycarbonate comprises the following raw materials in percentage by mass: First polycarbonate 39.41-59.11% Second polycarbonate 34.48-46.31% Plasticizer 2-4.93% Antioxidant 0.5-1.5% Lubricant 0.3-0.7%; The melt flow index (MI) of the first polycarbonate is 10 g / 10 min, and the melt flow index (MI) of the second polycarbonate is 60 g / 10 min; the test conditions of the first polycarbonate and the second polycarbonate are both 300° C.*1.2 kg; The plasticizer is an oligomeric aryl phosphate ester; the molecular weight of the oligomeric aryl phosphate ester is 100-1000; The antioxidant comprises a first antioxidant and a second antioxidant, wherein the weight ratio of the first antioxidant to the second antioxidant is 1:1; the first antioxidant comprises at least one of the following raw materials: 2,6-di-tert-butyl-4-methylphenol or β-(3,5-di-tert-butyl-4-hydroxy-phenyl) propionate; the second antioxidant comprises at least one of the following raw materials: dilauryl thiodipropionate, distearyl thiodipropionate, tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, or dioctadecyl pentaerythritol diphosphite; The lubricant comprises at least one of the following raw materials: silane polymer, fatty acid salt, fatty acid amide, stearic acid, butyl stearate, or polyolefin wax.

2. The transparent low-temperature injection moldable polycarbonate according to claim 1, characterized in that: The fatty acid amides include oleamide and ethylene bisstearamide.

3. The transparent low-temperature injection moldable polycarbonate according to claim 1, characterized in that: The first polycarbonate is bisphenol A polycarbonate with a relative molecular weight of 20,000-28,000.

4. The transparent low-temperature injection moldable polycarbonate according to claim 1, characterized in that: The second polycarbonate is bisphenol A polycarbonate with a relative molecular weight of 10,000-15,000.

5. The method for preparing the transparent low-temperature injection-molded polycarbonate according to any one of claims 1 to 4, characterized in that: The following steps are involved: The first polycarbonate, the second polycarbonate, a plasticizer, an antioxidant and a lubricant are mixed, extruded and granulated to obtain a transparent polycarbonate capable of low-temperature injection molding.

6. The method for preparing transparent low-temperature injection-molded polycarbonate according to claim 5, characterized in that: The extrusion temperature of the extrusion granulation is 230-250° C., and the screw speed of the extrusion granulation is 400-600 rpm.

7. An automobile interior, characterized in that: The invention is prepared by using a PET substrate film and the transparent low-temperature injection-molded polycarbonate according to any one of claims 1 to 4.

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