Antistatic polycarbonate composition having good cleanliness and preparation method therefor

Abstract

The present invention relates to an antistatic polycarbonate composition having good cleanliness and a preparation method therefor. The antistatic polycarbonate composition comprises a polycarbonate, an antistatic agent, an ion trapping agent, a compatibilizer, a toughening agent, an antioxidant, a lubricant, and a light stabilizer. In the present invention, a crown ether is incorporated into an antistatic polycarbonate. Under the action of dipole-charge, a negatively charged oxygen atom of the crown ether can be complexed with positively charged metal cations to form a relatively stable complex. By means of the metal ion trapping ability of the unique cyclic structure of the macromolecular crown ether, the ion precipitation performance of the final product is improved, thereby obtaining an antistatic polycarbonate composition having good cleanliness.

Description

An antistatic polycarbonate composition with good cleanliness and its preparation method Technical Field

[0001] This invention belongs to the field of polycarbonate materials, specifically relating to an antistatic polycarbonate composition with good cleanliness and its preparation method. Background Technology

[0002] Conductive or antistatic plastics are widely used in industry due to their advantages such as low cost, ease of molding, corrosion resistance, low specific gravity, and electrical conductivity. In the fields of electronic components and semiconductors, not only are conductive or antistatic properties required, but high cleanliness standards must also be met. Current breakthroughs in semiconductor technology have enabled electronic components to achieve extremely high integration. This high integration means that even the introduction of minute amounts of contaminants (such as particles, metal ions, and organic matter) can lead to component defects and failures, further reducing process yield and causing significant losses for manufacturers. Therefore, in the semiconductor industry, wafer cassettes or wafer boxes are commonly used to store wafers, ensuring that each wafer remains in a clean state during storage and transportation. Many of these wafer cassettes are made of antistatic plastic. Since the wafer cassettes are in direct contact with the critically protected wafers, their cleanliness is crucial and closely related to the yield of the protected wafers.

[0003] Polycarbonate (PC), one of the five major engineering plastics, possesses excellent optical transparency, impact resistance, thermal stability, and electrical insulation properties, making it widely used in industries such as electronics, automobiles, and semiconductors. In semiconductor product processing and transportation, antistatic polycarbonate is frequently used as transport boxes, such as wafer cassettes, wafer boxes, and antistatic trays. However, during the synthesis, production, transportation, and storage of polymers or modified plastics, some metal elements often accumulate, leading to excessive metal ion levels in the final plastic parts, such as wafer cassettes and wafer boxes. This can cause ion deposition during subsequent contact with wafers, resulting in defects in the final electronic components. Therefore, ensuring the cleanliness of antistatic polycarbonate is crucial.

[0004] CN117844158A discloses a method for preparing an antistatic composite material. By solving the dispersion problem of carbon nanotubes in the substrate, the agglomeration of carbon nanotubes is reduced, thereby reducing the number of surface particles and obtaining an antistatic composite material with good antistatic properties and high surface cleanliness.

[0005] WO2024066693A1 discloses an antistatic polyether ether ketone composite material and its preparation method. The main method is to improve the dispersibility of carbon nanotubes in the polyether ether ketone matrix by acidifying carbon nanotubes, combining the molding process of first making masterbatch and then mixing and melting extrusion, and ultrasonic treatment, thereby improving the conductivity of the material, reducing carbon particles and other dust on the material surface, and obtaining a high surface cleanliness.

[0006] TW201701391A discloses a cyclic olefin composition in which 1% to 5% by weight of carbon nanotubes are added, along with a semiconductor substrate delivery box based on this cyclic olefin composition. The product exhibits a lower concentration of harmful ions compared to liquid crystal polymers and carbon fiber composites. However, the inventors did not specify the reason for this, and cyclic olefins are expensive and have several performance limitations, such as poor toughness.

[0007] Overall, current research on improving the cleanliness of antistatic materials mainly focuses on how to reduce dust precipitation, decarburization, or the migration of the antistatic agent itself. There is relatively little research on how to reduce the precipitation of metal ions. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide an antistatic polycarbonate composition with good cleanliness and its preparation method.

[0009] The objective of this invention can be achieved through the following technical solutions.

[0010] In a first aspect, the present invention discloses an antistatic polycarbonate composition with good cleanliness, comprising the following raw material components in weight percentages:

[0011] In one embodiment of the present invention, the polycarbonate includes one or more of aromatic polycarbonate and aliphatic polycarbonate. Preferably, it is any one of these or a combination of at least two, more preferably an aromatic polycarbonate, and more preferably a bisphenol A type polycarbonate. The amount of polycarbonate used is preferably 74% to 86%.

[0012] Preferably, the melt index of the polycarbonate is 1 to 50 g / 10 min at 300°C and 1.2 kg; more preferably, the melt index is 2 to 25 g / 10 min.

[0013] In one embodiment of the present invention, the antistatic agent is a copolymer macromolecular antistatic agent, which includes one or more of polyether polyamide block copolymers and polyether polyester copolymers.

[0014] Preferably, the surface resistivity of the copolymer macromolecular antistatic agent is 1E5 to 1E10 Ω / sq, and more preferably 1E5 to 1E8 Ω / sq.

[0015] Preferably, the mass percentage of the antistatic agent is 12-18%.

[0016] In one embodiment of the present invention, the ion scavenging agent is a crown ether compound. The weight percentage of the ion scavenging agent is preferably 0.3%-1%, more preferably 0.3%-0.7%.

[0017] The crown ether compounds described in this invention can be selected arbitrarily from a variety of substances commonly known as crown ethers, depending on the intended purpose. The crown ether with the simplest structure is one with the general formula (-CH2-CH2-O-). n The substances referred to herein. In this invention, substances in which n is 4 to 7 are preferred. For crown ethers, let the total number of atoms constituting the ring be x and the number of oxygen atoms contained therein be y; they are sometimes also called x-crown-y-ethers.

[0018] Preferably, the crown ether compounds include 12-crown-4, 15-crown-5, 18-crown-6, 21-crown-7, and their derivatives. In this invention, at least one of the following is preferably used: crown ethers selected from x = 12, 15, 18, or 21, y = x / 3, their benzo[a] condensates, and cyclohexyl condensates. More preferred examples of crown ethers include 21-crown-7-ether, 18-crown-6-ether, 15-crown-5-ether, 12-crown-4-ether, dibenzo-21-crown-7-ether, dibenzo-18-crown-6-ether, dibenzo-15-crown-5-ether, dibenzo-12-crown-4-ether, dicyclohexyl-21-crown-7-ether, dicyclohexyl-18-crown-6-ether, dicyclohexyl-15-crown-5-ether, and dicyclohexyl-12-crown-4-ether. Among them, the most preferred are 12-crown-4, 15-crown-5, 18-crown-6 and 21-crown-7. It can be a combination of one or more of them: benzo-18-crown-6, benzo-15-crown-5, diaza-18-crown-ether-6.

[0019] To improve the antistatic properties of polycarbonate, antistatic agents are added. However, the addition of antistatic agents introduces metal cations, which can lead to excessive metal ion levels in the product. Conversely, the precipitation or reduction of metal ions can increase surface resistance and decrease antistatic performance, making it difficult to reconcile these two issues. The cyclic structure of the crown ether compound used in this invention enhances the ability to capture metal ions, improving the ion precipitation performance of the final product. However, the reduction (capture) of metal ions typically leads to increased surface resistance and decreased antistatic performance, making them theoretically incompatible. However, in actual experiments, the inventors found that with appropriate crown ether dosage, although the number of cations decreased, the antistatic performance of the material, i.e., the surface resistance, was not significantly affected. Further research revealed that crown ether further promotes system compatibility and facilitates the construction of charge dissipation channels in the polyether segments (antistatic agent). In other words, crown ether has a compatibilizing effect. When added in small amounts, the compatibilizing effect is greater than or roughly equal to the capturing effect (but fewer ions are captured). The electrical pathway material can even show a slight improvement in antistatic performance, depending on the capturing ability and dosage of the crown ether. The crown ether used in this invention, at around 0.5%, can both capture and compatibilize, ensuring the antistatic properties of polycarbonate and significantly reducing the precipitation of metal ions.

[0020] In one embodiment of the present invention, the compatibilizer comprises one or more of the following: styrene-acrylonitrile grafted maleic anhydride resin, acrylonitrile-butadiene-styrene grafted maleic anhydride resin, styrene-acrylonitrile grafted glycidyl methacrylate resin, acrylonitrile-butene-styrene grafted glycidyl methacrylate resin, and polystyrene grafted maleic anhydride resin. The compatibilizer is preferably present in a weight percentage of 0.4%-1.5%.

[0021] In one embodiment of the present invention, the toughening agent includes any one or more of methyl methacrylate-butadiene-styrene graft copolymers and core-shell structure toughening agents. Specifically, the core of the core-shell structure toughening agent is an organosilicon / acrylate, and the shell is methyl methacrylate. The core-shell structure toughening agent includes, but is not limited to, one or more of Mitsubishi's S-2001, S-2501, S-2030, S-2100, SX-005, and Kanekachi's MR-01. The methyl methacrylate-butadiene-styrene graft copolymer includes, but is not limited to, one or more of Kanekachi's M732KM and M-521.

[0022] In one embodiment of the present invention, the antioxidant includes one or more of phosphite antioxidants, hindered phenolic antioxidants, and thioester antioxidants. More preferably, the antioxidant is one or a mixture of several of antioxidants 168, 1010, 1076, 1098, and 300.

[0023] In one embodiment of the present invention, the lubricant is one or both of pentaerythritol stearate and ethylene bis-stearamide.

[0024] In one embodiment of the present invention, the light stabilizer is one or more selected from benzophenone light stabilizers, benzotriazole light stabilizers, salicylate light stabilizers, substituted acrylonitrile light stabilizers, and triazine light stabilizers. More preferably, the light stabilizer is one or more selected from Tinuvin-P Uvinul 3033P, Tinuvin-327, Tinuvin-329, Tinuvin-234, and 328.

[0025] In a second aspect, the present invention discloses a method for preparing an antistatic polycarbonate composition with good cleanliness as described above, comprising the following steps:

[0026] S1: The raw material components are mixed evenly in a mixer to obtain a premix;

[0027] S2: The mixture obtained in step S1 is fed into a twin-screw extruder, melt-extruded, and granulated to obtain an antistatic polycarbonate composition with good cleanliness.

[0028] The screw speed is 400-800 rpm. The twin-screw extruder includes ten temperature control zones. The temperature of temperature control zone 1-2 is 200-280℃, the temperature of temperature control zone 3-4 is 200-280℃, the temperature of temperature control zone 5-6 is 200-280℃, the temperature of temperature control zone 7-8 is 200-280℃, and the temperature of temperature control zone 9-10 is 200-280℃.

[0029] The twin-screw extruder has two vacuum points: one at the end of the conveying section and the beginning of the melting section; and the other at the metering section.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) This invention introduces crown ethers into antistatic polycarbonate. Under the influence of dipole-charge, the negatively charged oxygen atoms of the crown ether can form relatively stable complexes with positively charged metal cations. By utilizing the unique cyclic structure of the crown ether to capture metal ions, the ion release performance of the final product is improved.

[0032] (2) This invention has found that in the polycarbonate / macromolecule antistatic agent system of this invention, the synergistic effect of the compatibilizer and crown ether can improve the defect of easy peeling in the finished product. It is speculated that the reason may be that the low molecular weight crown ether, with its ether bond structure, has a certain compatibility with both polycarbonate containing a large number of carbonate bonds and antistatic agent containing a large number of ether bonds, thereby reducing the compatibility difference between the substrate phase and the antistatic agent phase. After synergistic effect with the compatibilizer, the phase interface effect is strengthened, thus making the gate of the injection molded product less prone to peeling. Detailed Implementation

[0033] The present invention will now be described in detail with reference to specific embodiments. The following examples are implemented under the premise of the technical solution of the present invention, providing detailed implementation methods and specific operating procedures, which will help those skilled in the art to further understand the present invention. It should be noted that the scope of protection of the present invention is not limited to the following embodiments; any adjustments and improvements made under the concept of the present invention are all within the scope of protection of the present invention.

[0034] Unless otherwise specified, the reagents used in the following description are commercially available products, and the methods used are conventional techniques in the field.

[0035] The following describes the various raw material components used in this embodiment:

[0036] PC: Bisphenol A type polycarbonate, commercially available, purchased from Wanhua's PC2100 product, MI = 10g / 10min (300℃, 1.2kg).

[0037] Antistatic agent: It is a polyamide macromolecular antistatic agent, TR-400 permanent antistatic agent purchased from Hangzhou Lingyou Technology Co., Ltd., with a surface resistivity of 5E6.

[0038] Ion trapping agents: crown ethers, benzo-18-crown-6, benzo-15-crown-5, purchased from Sigma Aldrich;

[0039] Toughening agent: Methyl methacrylate-butadiene-styrene graft copolymer, M-521, Nakabuchi, Japan;

[0040] Compatibilizer: Styrene-acrylonitrile-glycidyl methacrylate terpolymer, SAG-005, Jia Yi Rong.

[0041] Lubricant: Pentaerythritol stearate, commercially available.

[0042] Antioxidant: A 1:1 mass ratio of Irganox 168 and Irganox 1010, commercially available.

[0043] Light stabilizer: Benzotriazole UV absorber, commercially available.

[0044] Examples 1-6

[0045] This embodiment provides an antistatic polycarbonate composition with good cleanliness and its preparation method, the preparation steps of which are as follows:

[0046] S1: According to the formula in Table 1, polycarbonate, antistatic agent, ion scavenger, compatibilizer, toughening agent, antioxidant, lubricant and light stabilizer are mixed evenly in a mixer to obtain a premix;

[0047] S2: The mixture obtained in step S1 is fed into a twin-screw extruder (with two vacuum points, one at the end of the conveying section and the beginning of the melting section; the other at the metering section). The screw speed is 600 rpm, and the screw temperatures in each zone are 210℃, 230℃, 240℃, 250℃, 250℃, 240℃, 230℃, 235℃, 240℃, and 250℃. After extrusion and granulation, an antistatic polycarbonate composition with good cleanliness is obtained.

[0048] Table 1. Resin composition formulations (percentage) of the examples.

[0049] Comparative Examples 1-10

[0050] This comparative example provides an antistatic polycarbonate composition with good cleanliness and its preparation method. The preparation steps are basically the same as those in Example 1, and the mass fraction of each component is shown in Table 2.

[0051] Table 2. Comparative examples of resin composition formulations (percentage content)

[0052] Performance testing, the testing method is as follows:

[0053] Bending performance was tested according to ISO 178 standard, with a bending rate of 2 mm / min.

[0054] The heat distortion temperature was tested according to ISO 75-1 standard, with a load of 1.80 MPa and a heating rate of 120℃ / min.

[0055] The impact test of the simply supported beam with notched beam was conducted in accordance with ISO 179-1 standard on a Zwick electronic universal testing machine.

[0056] Surface resistivity: Tested according to standard ASTM D257-2014; for injection molded 70*130*3mm square plate samples, the ZST-12 insulating material volume surface resistivity (rate) tester was used.

[0057] Cleanliness test: The material was injection molded into sheets measuring 63.5*12.7*3.2mm. Five sheets were placed in 2L of ultrapure water and sonicated for 15 minutes. The molded parts were removed, and the liquid was retained as the test solution. Then, the amount of metal cations precipitated was measured using an ion chromatograph. The total ion amount included lithium ions (Li...). + Sodium ions (Na) + ), potassium ions (K) + ), calcium ions (Ca 2+ ), magnesium ions (Mg 2+ ), aluminum ions (Al) 3+ ), titanium ions (Ti 2+ Common ions such as chromium (Cr), manganese, zinc, copper, nickel, and manganese are listed, with units converted to (ppb, μg / kg).

[0058] Anti-peeling performance characterization: The bending strip is repeatedly folded in half, and the number of folds at which obvious peeling begins is used to represent the anti-peeling performance. The larger the value, the less likely it is to peel.

[0059] The test results are shown in Table 3.

[0060] Table 3. Properties of the resin compositions in the examples and comparative examples.

[0061] A comparison of Example 2 and Comparative Example 2, and Example 6 and Comparative Example 8 reveals that the introduction of the ion-scavenging agent crown ether objectively reduces the number of metal cations detected in the material, resulting in improved cleanliness. However, surprisingly, although the number of cations decreases, the antistatic properties of the material, i.e., surface resistance, are not significantly affected. This is presumably because the electrostatic dissipation molecular network mainly relies on the charge dissipation channels of the polyether segments (antistatic agent) to construct the electrical pathways. The reduction of harmful metal cations only accounts for a portion of the overall cation level, and the number of anions in the system is not significantly affected. Therefore, the electrical properties do not fluctuate significantly when a small amount of crown ether is added. Furthermore, because crown ether can further promote the compatibility of the system, the material even shows a slight improvement in antistatic properties.

[0062] Crown ethers can increase electrical resistance by capturing metal ions, but they also have compatibility with both the polymer matrix and the antistatic phase, thus providing a slight compatibility-enhancing effect and helping to reduce resistance. When the crown ether content is below 0.5%, cations are essentially captured, and the compatibility-enhancing effect is relatively significant. Therefore, the antistatic performance does not decrease with the reduction of ions; in fact, the antistatic effect may even be better after the addition of crown ethers.

[0063] The comparison between Example 2 and Comparative Examples 2-3, and Example 6 and Comparative Examples 8-9, reveals that the anti-peeling performance of the material after combining crown ether and compatibilizer is better than that of adding either alone. This is presumably because the crown ether and compatibilizer synergistically improve the compatibility of the system.

[0064] A comparison of Example 1 and Comparative Example 6 shows that even with insufficient crown ether addition, the ion content of the material remains relatively high. A comparison of Examples 1, 2, 5 and Comparative Example 4 shows that as the crown ether content increases, the number of metal cations in the material decreases. However, when the content exceeds 1%, increasing the crown ether content has a very limited effect on reducing the number of metal cations. Nevertheless, the material's heat resistance and antistatic properties significantly decrease. This is presumably because the crown ether has a small molecular weight, and excessive addition can lead to the formation of an enriched layer on the surface, thus affecting the material's surface resistance.

[0065] A comparison of Example 2 and Comparative Example 5 reveals that excessive compatibilizer should be avoided, as conductivity primarily relies on the conductive network formed by the antistatic agent within the polycarbonate substrate. Excessive compatibility can actually promote the transformation of the continuous phase-separated structure into a dispersed island structure, thereby disrupting the conductive network and reducing antistatic performance.

[0066] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. An antistatic polycarbonate composition, characterized in that, The raw material components include the following weight percentages:

2. The antistatic polycarbonate composition according to claim 1, characterized in that, The polycarbonate mentioned includes one or more of aromatic polycarbonate and aliphatic polycarbonate.

3. The antistatic polycarbonate composition according to claim 1, characterized in that, The antistatic agent is a copolymer-type macromolecular antistatic agent, including one or more of polyether polyamide block copolymers and polyether polyester copolymers.

4. The antistatic polycarbonate composition according to claim 1, characterized in that, The ion scavenging agent is a crown ether compound, including one or more of 12-crown-4, 15-crown-5, 18-crown-6, 21-crown-7, or one or more derivatives thereof.

5. The antistatic polycarbonate composition according to claim 1, characterized in that, The compatibilizer includes one or more of the following: styrene-acrylonitrile grafted maleic anhydride resin, acrylonitrile-butadiene-styrene grafted maleic anhydride resin, styrene-acrylonitrile grafted glycidyl methacrylate resin, acrylonitrile-butene-styrene grafted glycidyl methacrylate resin, and polystyrene grafted maleic anhydride resin.

6. The antistatic polycarbonate composition according to claim 1, characterized in that, The toughening agent includes any one or more of methyl methacrylate-butadiene-styrene graft copolymer and core-shell toughening agents.

7. The antistatic polycarbonate composition according to claim 1, characterized in that, The antioxidants mentioned include one or more of the following: phosphite antioxidants, hindered phenolic antioxidants, and thioester antioxidants.

8. The antistatic polycarbonate composition according to claim 1, characterized in that, The lubricant is one or both of pentaerythritol stearate and ethylene bis-stearamide.

9. The antistatic polycarbonate composition according to claim 1, characterized in that, The light stabilizer is one or more of the following: benzophenone light stabilizers, benzotriazole light stabilizers, salicylates light stabilizers, substituted acrylonitrile light stabilizers, and triazine light stabilizers.

10. A method for preparing the antistatic polycarbonate composition as described in claim 1, characterized in that, Includes the following steps: S1: Mix the raw material components evenly to obtain a premix; S2: The premix obtained in step S1 is melt-extruded and granulated to obtain an antistatic polycarbonate composition.

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