A polycarbonate alloy with good appearance, its preparation method and application

Abstract

The present invention discloses a polycarbonate alloy with good appearance, and its preparation method and application. The polycarbonate alloy comprises the following components: 60 - 80 parts by weight of polycarbonate, 20 - 40 parts by weight of polybutylene terephthalate, 5 - 10 parts by weight of toughening agent, 0.1 - 1 part by weight of antioxidant, 0.1 - 3 parts by weight of light stabilizer, and 0.1 - 3 parts by weight of color powder. Among them, the polycarbonate is a compound of a first polycarbonate and a second polycarbonate; the melt index of the first polycarbonate is 2 - 5 g / 10 min, and the melt index of the second polycarbonate is 8 - 13 g / 10 min; the weight ratio of the first polycarbonate to the second polycarbonate is 1:3 to 3:1. The present invention realizes the balance between "bright printing" and solvent resistance by optimizing the material formula. At the same time, the invented material has good fluidity and excellent mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering plastics, and particularly relates to a polycarbonate alloy with good appearance, a preparation method thereof, and an application thereof. Background Art

[0002] Decorative strips at positions such as instrument panels, door panels, and seats in automotive cockpits often use polycarbonate or acrylonitrile-butadiene-styrene and their alloy materials because these two materials have advantages such as high gloss, good sprayability, and good dimensional stability, and the prepared plastic parts have a certain degree of texture.

[0003] With the gradual improvement of the requirements for the appearance and reliability of plastic parts by automotive OEMs, as well as the environmental protection requirements of low-carbon emission reduction, the requirements for the performance of materials have also been gradually improved. In addition to ensuring certain mechanical properties, the above-mentioned decorative strips also need to meet the requirement of solvent resistance in terms of chemical properties. Solvent resistance includes resistance to alcohol, beverages, acids, alkalis, sweat, emulsions, sunscreen, etc., among which it is relatively difficult to meet the requirement of sunscreen resistance. Polycarbonate and acrylonitrile-butadiene-styrene and their alloys are non-crystalline polymers themselves, and their solvent resistance is relatively poor, which limits their application to parts that are easily exposed to highly corrosive solvents.

[0004] Polybutylene terephthalate (PBT) has a certain degree of crystallinity, and the alloy prepared with polycarbonate has good solvent resistance, which broadens the application range of polycarbonate. However, the crystallization behavior of PBT will also bring some problems. For example, on the surface of the part with ribs behind, surface shrinkage will occur due to crystallization, resulting in poor replication of the skin texture and generating "bright imprints". Destroying the crystallization of PBT is beneficial to solving the "bright imprint" problem, but the material sacrifices solvent resistance. Therefore, there is an urgent need for a polycarbonate that can solve the problems of bright imprints and solvent resistance, especially sunscreen resistance. Summary of the Invention

[0005] Aiming at the defects in the prior art, the present invention provides a polycarbonate alloy with good appearance, a preparation method thereof, and an application thereof. The present invention aims to invent a method for controlling the crystallinity of PC / PBT to solve the bright imprint problem without sacrificing solvent resistance, and also takes into account excellent mechanical and molding properties.

[0006] The present invention provides a polycarbonate alloy with good appearance, comprising the following components:

[0007] 60-80 parts by weight of polycarbonate (PC);

[0008] 20-40 parts by weight of polybutylene terephthalate (PBT);

[0009] 5-10 parts by weight of a toughening agent;

[0010] 0.1-1 part by weight of an antioxidant;

[0011] Among them, the polycarbonate is a compound of a first polycarbonate and a second polycarbonate; the melt flow rate MFR (test standard ISO 1133-2011, test conditions 300 °C, 1.2 kg) of the first polycarbonate is 2-5 g / 10 min, and the melt flow rate MFR (test standard ISO 1133-2011, 300 °C, 1.2 kg) of the second polycarbonate is 8-13 g / 10 min. The molecular chain of PC with a lower melt index is better end-capped, and good end-capping is beneficial to controlling the transesterification of PC and PBT. However, the melt index cannot be too low, otherwise it is not conducive to molding. PC with a slightly higher melt index is beneficial to ensuring the fluidity of the material. Therefore, two kinds of PC are needed for regulation. The weight ratio of the first polycarbonate to the second polycarbonate is 1:3 to 3:1. The crystallization behavior of the PC / PB alloy is affected by the phase state and transesterification degree of the PC / PBT alloy microscopically. Using PC with different melt indexes can regulate the viscosity ratio of PC / PBT. Coupled with the different end-capping rates of PC with different melt indexes, the crystallization behavior of the alloy material can be regulated. The present invention invent a material with a wider crystallization temperature range, thereby improving the bright printing problem. In addition, crystallization is also beneficial to improving the solvent resistance of the material. Therefore, the balance between "bright printing" and solvent resistance can be achieved by controlling the crystallization behavior of the material.

[0012] Further, the weight ratio of the first polycarbonate to the second polycarbonate is 1:2 to 2:1.

[0013] Further, the melt flow rate of the polybutylene terephthalate is 12-25 g / 10 min. Preferably, the melt flow rate of the polybutylene terephthalate is 13-16 g / 10 min. Using PBT with a suitable melt index can ensure that the alloy material has both fluidity and physical properties. For PBT with too high a melt index, the molecular chain length is relatively short and the physical properties are relatively poor. For PBT with too low a melt index, the molecular weight chain length is relatively long, but the crystallization is too slow, which will instead lead to insufficient crystallization degree, affecting the solvent resistance. Too low a melt index will also cause other appearance risks.

[0014] Further, the toughening agent is at least one of methyl methacrylate-butadiene-styrene copolymer, n-butyl acrylate-glycidyl ester copolymer, propylene-butene copolymer or propylene-hexene copolymer, vinyl methacrylate, etc.

[0015] Further, the antioxidant is at least one of pentaerythritol β(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, octadecyl alcohol β(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris(2,4-di-tert-butylphenol) phosphite, pentaerythritol β-dodecylthiopropionate.

[0016] Furthermore, the polycarbonate alloy with good appearance further comprises a light stabilizer and / or a color powder.

[0017] Furthermore, the light stabilizer is 2-(2'-hydroxy-3',5'-bis[1,1-dimethylphenyl])-benzotriazole. The light stabilizer is 0.1-3 parts by weight.

[0018] Furthermore, the color powder is at least one of carbon black, organic color powder, and inorganic color powder. The color powder is 0.1-3 parts by weight.

[0019] The present invention also provides a method for preparing the polycarbonate alloy with good appearance, comprising the following steps:

[0020] (1) Weigh each raw material by parts by weight, and mix them evenly to obtain a premixed material;

[0021] (2) Place the premixed material obtained in step (1) in a twin-screw extruder, and extrude and pelletize it after mixing, melting, and homogenizing, and then cool it to obtain the polycarbonate alloy; the barrel temperature of the twin-screw extruder is 200-260°C, and the rotation speed is 300-1000 r / min.

[0022] The present invention also provides an application of the polycarbonate alloy with good appearance in the preparation of automotive decorative parts.

[0023] In summary, compared with the prior art, the present invention achieves the following technical effects:

[0024] While solving the problems of bright printing and solvent resistance, the present invention also takes into account the formability and mechanical properties. The products prepared according to the present invention can meet the performance requirements of MFR≥20 g / 10 min, and can reach up to 40 g / 10 min at most; the Izod notched impact strength≥40 kJ / m 2 , and can reach up to 100°C at most; the temperature difference between the beginning and end of crystallization≥25°C, and can reach up to 40°C at most; and it has excellent appearance, the bright printing evaluation is above 4; the solvent resistance performance evaluation is above 4. Specific Embodiments

[0025] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] The present invention improves the bright printing problem by characterizing and optimizing the crystallization temperature range of the material; in the PC / PBT system, the main crystallization component is PBT. The crystallization of PBT will cause a certain degree of shrinkage on the material surface. If the PBT crystallizes too fast, faster than the overall cooling and freezing of the part, it is easy to cause shrinkage on the surface of the part with ribs on the back. Appropriately slowing down the crystallization degree of PBT, slower than the overall cooling and freezing of the part, is beneficial to improving the surface shrinkage. The crystallization speed of PBT is affected by the microscopic phase state of PC and PBT and the degree of transesterification. The present invention solves the contradiction that cannot be satisfied simultaneously between bright printing and solvent resistance through formula optimization; by regulating the melt indices of the first polycarbonate and the second polycarbonate within appropriate ranges respectively, the control of the microscopic phase state of PC / PBT and the transesterification of PC / PBT can be realized, and further the crystallization speed and degree of PBT can be regulated. The crystallization behavior of the PC / PBT alloy is affected by the microscopic phase state and the degree of transesterification of the PC / PBT alloy. Using PCs with different melt indices can regulate the viscosity ratio of PC / PBT. Coupled with the different end-capping rates of PCs with different melt indices, the crystallization behavior of the alloy material can be regulated. The prior inventions do not mention solving the contradiction problem of "bright printing" and solvent resistance simultaneously. The present invention realizes the balance between "bright printing" and solvent resistance through optimizing the material formula. At the same time, the invented material has good fluidity and excellent mechanical properties.

[0027] Examples

[0028] The present invention will be further described below in conjunction with specific examples and comparative examples. The following specific examples are all preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the following examples, especially not limited to the models of the component raw materials used in the following specific examples.

[0029] I. The following are the component raw materials used:

[0030] The first polycarbonate #1 (PC1#1): grade 1300 03NP, LG Chem., MFR = 3 g / 10 min;

[0031] The first polycarbonate #2 (PC1#2): grade 3030PJ, S-Oil, MFR = 2 g / 10 min;

[0032] The first polycarbonate #3 (PC1#3): grade 7030R, Mitsubishi Engineering Plastics, MFR = 4.2 g / 10 min;

[0033] The second polycarbonate #1 (PC2#1): grade 1300 10NP, LG Chem., MFR = 10 g / 10 min;

[0034] The second polycarbonate #2 (PC2#2): grade 2100, Wanhua Chemical, MFR = 9 g / 10 min;

[0035] Second Polycarbonate #3 (PC2#3): Grade 2200, manufactured by Idemitsu Chemical, MFR = 12 g / 10 min;

[0036] Second Polycarbonate #4 (PC2#4): Grade 1300 - 22NP, manufactured by LG Chem, MFR = 20 g / 10 min;

[0037] Polybutylene Terephthalate #1 (PBT#1): Grade GL236, manufactured by Yangzi Petrochemical, MFR = 13 g / 10 min;

[0038] Polybutylene Terephthalate #2 (PBT#2): manufactured by Yangzi Petrochemical, MFR = 10 g / 10 min;

[0039] Polybutylene Terephthalate #3 (PBT#3): manufactured by Yangzi Petrochemical, MFR = 16 g / 10 min;

[0040] Polybutylene Terephthalate #4 (PBT#4): Grade GX121, manufactured by Yangzi Petrochemical Co., MFR = 25 g / 10 min;

[0041] Toughening Agent: Methyl Methacrylate - Butadiene - Styrene Copolymer, commercially available, the same substance was used in parallel experiments;

[0042] Antioxidant: Pentaerythritol Tetrakis(3,5 - Di - tert - butyl - 4 - hydroxyphenyl) Propionate, commercially available, the same substance was used in parallel experiments;

[0043] Light Stabilizer: 2 - (2’ - Hydroxy - 3’,5’ - Bis[1,1 - dimethylphenyl]) - benzotriazole, commercially available, the same substance was used in parallel experiments;

[0044] Color Pigment: Carbon Black, commercially available, the same substance was used in parallel experiments.

[0045] Weigh each raw material according to the parts by weight in Table 1 and Table 2, and mix them evenly to obtain a premixed material; place the premixed material in a twin - screw extruder, and carry out mixing and extrusion granulation at 200 - 260 °C and 300 - 1000 r / min to obtain the polycarbonate composite material.

[0046] II. Test methods for various properties:

[0047] (1) Test method for MFR of the product: Refer to ISO 1133 - 2011, test conditions: 260 °C, 5 kg.

[0048] (2) Heat distortion: Refer to ISO 75 - 2013, test conditions: 1.8 MPa.

[0049] (3) Crystallization temperature range: Using a differential scanning calorimeter (DSC), the test conditions are 30 - 250 °C, heating rate 10 °C / min, 2 cycles. Take the peak positions (starting point and ending point) of the crystallization curve in the second cycle.

[0050] (4) Bright mark evaluation: Inject the material into a square plate with ribs on the back, and observe the surface of the sample opposite the ribs. Observe the degree of bright marks. Conduct a rating from 1 - 5 levels. The higher the value, the less obvious the bright mark.

[0051] (5) Solvent resistance evaluation: Inject the material into a 100 mm * 100 mm square plate, coat the surface of the square plate with sunscreen, and observe the degree of surface change after 3 h.

[0052] 1 - Severe whitening and cracking, 2 - Moderate whitening with cracks, 3 - Moderate whitening with inconspicuous cracks, 4 - Slight whitening without cracks, 5 - No obvious change.

[0053] Table 1 Technical solutions and effects of examples (parts by weight)

[0054]

[0055]

[0056]

[0057] Table 2 Technical solutions and effects of comparative examples (parts by weight)

[0058]

[0059]

[0060] Through mechanical tests, it is found that the notched Izod impact strength of the polycarbonate alloys in Examples 1 - 17 all meets ≥ 40 kJ / m 2 . From the results in Table 1, the performance can meet MFR ≥ 20 g / 10 min, up to 40 g / 10 min; up to 100 °C; the temperature difference between the beginning and end of crystallization ≥ 25 °C, up to 40 °C; and it has excellent appearance, with a bright mark evaluation of 4 or above; the solvent resistance performance evaluation is 4 or above.

[0061] Comparative Examples 1 - 7 are all single - variable with Example 4. In Comparative Example 1, the polycarbonate is not compounded with two types, all being PC2#1; in Comparative Example 2, the polycarbonate is not compounded with two types, all being PC1#1; in Comparative Example 3, the PBT dosage is too low; in Comparative Examples 4 and 5, the weight ratio of PC1:PC2 is not within the scope of the present invention. In Comparative Example 6, the MFR of the PC compounding is not within the scope of the present invention, and in Comparative Example 7, the MFR of the PC compounding is not within the scope of the present invention. The above - mentioned comparative examples cannot simultaneously meet the balance of "bright mark" and solvent resistance.

[0062] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A polycarbonate alloy with good appearance, characterized in that, It includes the following components: 60 - 80 parts by weight of polycarbonate; 20 - 40 parts by weight of polybutylene terephthalate; 5 - 10 parts by weight of toughening agent; 0.1 - 1 part by weight of antioxidant; Among them, the polycarbonate is a blend of a first polycarbonate and a second polycarbonate; the melt index of the first polycarbonate is 2 - 5 g / 10 min, and the melt index of the second polycarbonate is 8 - 13 g / 10 min; the weight ratio of the first polycarbonate to the second polycarbonate is 1:3 to 3:1; The toughening agent is at least one of methyl methacrylate - butadiene - styrene copolymer, n - butyl acrylate - glycidyl ester copolymer, propylene - butene copolymer, propylene - hexene copolymer, and vinyl methacrylate; The melt index test standard for the first and second polycarbonates is ISO 1133 - 2011, and the test conditions are 300 °C and 1.2 kg.

2. The polycarbonate alloy with good appearance according to claim 1, characterized in that, The weight ratio of the first polycarbonate to the second polycarbonate is 1:2 to 2:

1.

3. The polycarbonate alloy with good appearance according to claim 1, characterized in that, The melt index of the polybutylene terephthalate is 12 - 25 g / 10 min.

4. The polycarbonate alloy with good appearance according to claim 1, characterized in that, The melt index of the polybutylene terephthalate is 13 - 16 g / 10 min.

5. The polycarbonate alloy with good appearance according to claim 1, characterized in that, The antioxidant is at least one of pentaerythritol β(3,5 - di - tert - butyl - 4 - hydroxyphenyl) propionate, octadecyl alcohol β(3,5 - di - tert - butyl - 4 - hydroxyphenyl) propionate, tris(2,4 - di - tert - butylphenyl) phosphite, and pentaerythritol β - dodecylthiopropionate.

6. The polycarbonate alloy with good appearance according to claim 1, characterized in that, The polycarbonate alloy with good appearance further includes a light stabilizer and / or color powder. The light stabilizer is 0.1 - 3 parts by weight, and the color powder is 0.1 - 3 parts by weight.

7. The polycarbonate alloy with good appearance according to claim 6, characterized in that, The light stabilizer is 2 - (2’ - hydroxy - 3’,5’ - bis[1,1 - dimethylphenyl]) - benzotriazole.

8. The polycarbonate alloy with good appearance according to claim 6, characterized in that, The color powder is at least one of organic color powder and inorganic color powder.

9. A method for preparing the polycarbonate alloy with good appearance according to claims 1 to 8, characterized in that, It includes the following steps: (1) Weigh each raw material according to parts by weight and mix them evenly to obtain a premixed material; (2) Place the premixed material obtained in step (1) in a twin - screw extruder, and after mixing, melting, and homogenizing, extrude and pelletize, and then cool to obtain the polycarbonate alloy; the barrel temperature of the twin - screw extruder is 200 - 260 °C, and the rotation speed is 300 - 1000 r / min.

10. Use of the polycarbonate alloy with good appearance according to any one of claims 1 to 8 in the preparation of automotive decorative parts.

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