Spraying-free PC / PBT alloy material and preparation method thereof

Abstract

The invention provides a spraying-free PC / PBT alloy material and a preparation method thereof, and relates to the technical field of high polymer materials. The preparation method of the spraying-free PC / PBT alloy material comprises the following steps: blending the PC resin, the PBT resin, the flexibilizer, the compatilizer, the antioxidant, the lubricant and the weather-resistant agent to obtain a premix, and preparing the spraying-free PC / PBT alloy material from the premix and the AS carrier metal powder master batch through a melt blending process. The prepared spraying-free PC / PBT alloy material has excellent appearance and mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a paint-free PC / PBT alloy material and its preparation method. Background Technology

[0002] With the upgrading of consumption in the automotive industry, the market has placed higher demands on the aesthetics, texture, and technological feel of automotive interiors. Due to its elegant and fashionable characteristics, the metallic effect has become a popular design element for automotive interior parts. Currently, the mainstream processes for achieving a metallic effect on plastic parts include surface coating, IMD (In-Mold Decoration) technology, and the use of paint-free materials.

[0003] Surface coating processes suffer from inherent drawbacks such as complex processes, high production costs, significant environmental pollution, and VOC emissions. Injection molding (IMD) technology, on the other hand, faces barriers due to substantial equipment investment and high process complexity. Paint-free technology, by directly adding special effect pigments to the plastic matrix, achieves the desired appearance immediately after injection molding, eliminating the need for painting. However, applying paint-free technology to demanding automotive interior parts, especially when achieving high-quality metallic effects, still faces challenges such as poor compatibility between the matrix and metallic pigments, leading to surface defects like flow marks and material defects, as well as reduced mechanical properties. Therefore, improving the compatibility between the matrix and metallic pigments when preparing paint-free alloy materials is a crucial technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a paint-free PC / PBT alloy material and its preparation method, solving the technical problem of poor compatibility between the matrix and metallic pigments in existing paint-free alloy materials.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] On one hand, the present invention provides a method for preparing a paint-free PC / PBT alloy material, comprising the following steps: blending polycarbonate (PC) resin, polybutylene terephthalate (PBT) resin with toughening agent and compatibilizer to obtain a premix, and preparing the paint-free PC / PBT alloy material by melt blending the premix with AS carrier metal powder masterbatch.

[0009] The above-mentioned method for preparing paint-free PC / PBT alloy materials involves using a blend of PBT and PC resins as the matrix material, ethylene-butyl acrylate-glycidyl methacrylate terpolymer (PTW) as a toughening agent, and a metallic pigment masterbatch with acrylonitrile-styrene copolymer (AS) as the carrier. In this method, the butyl acrylate segments in the PTW diffuse and entangle with the AS carrier surface, thereby reducing the interfacial tension between the AS and the PC / PBT matrix. The PC / PBT matrix polymer more easily wets the pigment masterbatch, and under the shear force during melt blending, the pigment masterbatch can be more uniformly dispersed. During the process, the epoxy groups of glycidyl methacrylate in PTW undergo a ring-opening reaction with the terminal carboxyl groups at the ends of the PBT molecular chains in the matrix, forming strong covalent ester bonds. This firmly and stably fixes the AS carrier pigment masterbatch in the continuous phase of the PC / PBT blend, preventing the pigment masterbatch from migrating and agglomerating during melt blending. Thus, under the synergistic effect of PBT, PTW, and AS, the compatibility between the metallic pigment and the matrix is ​​improved. The metallic pigment has good dispersion and directional arrangement in the matrix, thereby achieving a uniform and bright metallic luster, reducing material streaks, obtaining a good appearance effect, reducing stress concentration points, and improving the mechanical properties of the paint-free PC / PBT alloy material.

[0010] Preferably, the toughening agent is an ethylene-butyl acrylate-glycidyl methacrylate terpolymer. The ethylene-butyl acrylate-glycidyl methacrylate terpolymer works synergistically with PBT and AS to improve the compatibility of metallic pigments in the matrix, thereby giving the prepared PC / PBT alloy material good appearance and mechanical properties.

[0011] Preferably, the weight ratio of the PBT resin, toughening agent, and AS carrier metal powder masterbatch is 10-30:3-6:2-5, and the metal powder content of the AS carrier metal powder masterbatch is 40-50%, with a particle size of 25-50μm.

[0012] By selecting appropriate weight ratios of PBT resin, toughening agent, and AS carrier metal powder masterbatch, as well as the metal powder content and particle size of the AS carrier metal powder masterbatch, PBT resin, toughening agent, and AS can work synergistically to improve the compatibility of metal pigments in the matrix, thereby enabling the prepared PC / PBT alloy material to have good appearance and mechanical properties.

[0013] Preferably, the metal powder in the AS carrier metal powder masterbatch is selected from aluminum powder. The melt index of the AS carrier is 30-35 g / 10 min.

[0014] Preferably, the polycarbonate resin is bisphenol A type polycarbonate, with a melt flow rate of 10-20 g / 10min at 300℃ / 1.2kg load. The polybutylene terephthalate resin has a melt flow rate of 20-25 g / 10min at 250℃ / 2.16kg load.

[0015] The melt flow rates of polycarbonate resin and polybutylene terephthalate resin are selected within a suitable range to match the melt index of AS carrier metal powder masterbatch, ensuring good compatibility between the metal pigment and the matrix.

[0016] Preferably, the compatibilizer is a random copolymer of styrene-acrylonitrile-glycidyl methacrylate.

[0017] Choosing a random copolymer of styrene-acrylonitrile-glycidyl methacrylate can effectively improve the compatibility between the two phases of PC and PBT, prevent phase separation, and end-cap the PC resin to prevent material degradation, thereby further improving the material's mechanical properties and appearance uniformity.

[0018] Preferably, the method for preparing the paint-free PC / PBT alloy material satisfies at least one of the following conditions:

[0019] The antioxidant is selected from one or more of tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168), β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate octadecyl alcohol ester (antioxidant 1076), and bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite (antioxidant 626);

[0020] The lubricant is selected from one or more of silicone powder, ethylene bis-stearamide (EBS), and pentaerythritol stearate (PETS).

[0021] In a second aspect, the present invention provides a paint-free PC / PBT alloy material prepared by the preparation method described in the first aspect, wherein the paint-free PC / PBT alloy material comprises the following components in parts by weight:

[0022] Polycarbonate resin: 60-80 parts;

[0023] Polybutylene terephthalate resin: 10-30 parts;

[0024] Toughening agent: 3-6 parts;

[0025] Compatibilizer: 0.5-1 part;

[0026] Antioxidant: 0.5-1 part;

[0027] Lubricant: 0.5-1 part;

[0028] AS carrier metal powder masterbatch: 2-5 parts.

[0029] (III) Beneficial Effects

[0030] This invention provides a paint-free PC / PBT alloy material and its preparation method. Compared with the prior art, it has the following advantages:

[0031] The method for preparing paint-free PC / PBT alloy materials provided by this invention selects a blend of PBT resin and PC resin as the matrix material, uses ethylene-butyl acrylate-glycidyl methacrylate terpolymer (PTW) as a toughening agent, and a metallic pigment masterbatch with acrylonitrile-styrene copolymer (AS) as the carrier to prepare paint-free PC / PBT alloy materials. The butyl acrylate segments in the PTW diffuse and entangle with the surface of the AS carrier, thereby reducing the interfacial tension between the AS and the PC / PBT matrix. The PC / PBT matrix polymer more easily wets the pigment masterbatch, and under the action of shear force during melt blending, the pigment masterbatch can be more uniformly dispersed. Meanwhile, the epoxy groups of glycidyl methacrylate in PTW undergo a ring-opening reaction with the terminal carboxyl groups at the ends of the PBT molecular chains in the matrix, forming strong covalent ester bonds. This firmly and stably fixes the AS carrier pigment masterbatch in the continuous phase of the PC / PBT blend, preventing the pigment masterbatch from migrating and agglomerating during melt blending. Thus, the synergistic effect of PBT, PTW, and AS improves the compatibility between the metallic pigment and the matrix. The metallic pigment has good dispersion and directional arrangement in the matrix, thereby achieving a uniform and bright metallic luster, reducing material streaks, obtaining a good appearance effect, reducing stress concentration points, and improving the mechanical properties of the paint-free PC / PBT alloy material. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] To better understand the above technical solution, the following will provide a detailed explanation of the above technical solution in conjunction with specific implementation methods.

[0034] I. Preparation Method

[0035] Example 1

[0036] This embodiment provides a method for preparing a paint-free PC / PBT alloy material, including the following steps:

[0037] S1. Drying: The PC resin and PBT resin are dried by forced air at 110℃ for 3 hours to reduce their moisture content to below 0.02%. The polycarbonate resin is bisphenol A type polycarbonate with a melt flow rate of 15 g / 10min at 300℃ / 1.2kg load, and the polybutylene terephthalate resin has a melt flow rate of 22 g / 10min at 250℃ / 2.16kg load.

[0038] S2. Premix: Weigh the dried PC resin, PBT resin, toughening agent PTW, compatibilizer styrene-acrylonitrile-glycidyl methacrylate random copolymer, antioxidant 168, and lubricant EBS according to the weight parts in Table 1, and add them together to a high-speed mixer. Mix for 10 minutes to obtain the premix.

[0039] S3. Melt Blending: The premixed material is added through the main feed port of the twin-screw extruder, while AS carrier aluminum powder masterbatch is accurately added through the side feed port. The addition amounts are shown in Table 1. The process parameters of the twin-screw extruder are set as follows: processing temperature of each section: 220-250-250-250-245-245-245-240-245-250℃, screw speed: 400rpm.

[0040] AS carrier aluminum powder masterbatch is a high-concentration, granular colorant made by uniformly dispersing and encapsulating high-concentration aluminum powder in an acrylonitrile-styrene copolymer carrier resin, followed by melt mixing, extrusion, and pelletizing. The parameters of AS carrier aluminum powder masterbatch (MCP-10B) are as follows: moisture content ≤0.2%, carrier resin 60%, melt index of carrier resin 30g / 10min, aluminum powder 40%, non-floating aluminum powder, styrene-maleic anhydride copolymer dispersant 4%, and additives (antioxidant 1010, light stabilizer Tinuvin 234) 3%, wherein the aluminum powder particle size D50 is 25μm.

[0041] S4. Post-processing: After the melt extruded strip is cooled in a water bath, granulated, and dried by a blower, a paint-free PC / PBT alloy material is obtained.

[0042] Examples 2-4

[0043] The difference between Examples 2-4 and Example 1 is that the amounts of PBT resin, toughening agent PTW, and AS carrier aluminum powder masterbatch are different, as detailed in Table 1. The other aspects are the same as in Example 1.

[0044] Comparative Example 1

[0045] The difference between this comparative example and Example 1 is that ABS resin is used instead of PBT resin; otherwise, they are the same as in Example 1.

[0046] Comparative Example 2

[0047] The difference between this comparative example and Example 1 is that PTW is not included in step S2, but otherwise it is the same as Example 1.

[0048] Comparative Example 3

[0049] The difference between this comparative example and Example 1 is that in step S3, aluminum powder masterbatch with polyethylene wax carrier is used instead of aluminum powder masterbatch with AS as carrier. The amount of aluminum powder particles used is 5 parts, and the particle size D50 is 25 μm. Other aspects are the same as in Example 1.

[0050] Table 1 Raw material usage in Examples 1-4

[0051]

[0052] II. Performance Testing Methods

[0053] The paint-free PC / PBT alloy material particles prepared in Examples 1-4 and Comparative Examples 1-3 were molded into standard test strips and automotive trim sample plates on an injection molding machine. After the strips were conditioned for 24 hours in a standard environment of 23°C and 50% relative humidity, performance tests were conducted according to national standards, and the results are recorded in Table 1.

[0054] Tensile strength: Tested according to GB / T 1040 standard, with a sample size of 150*10*4mm and a test speed of 50mm / min.

[0055] Bending strength: Tested according to GB / T 9341 standard, with a sample size of 80*10*4mm and a test speed of 2mm / min.

[0056] Notched impact strength of simply supported beam: tested according to GB / T 1043.1 standard, with a sample size of 80*10*4mm.

[0057] Vicat softening temperature: tested according to GB / T 1633 standard (load 50N, heating rate 120℃ / h).

[0058] Appearance assessment: Using an injection mold of an automotive interior trim strip, three experienced colorists visually assess the severity of surface defects such as material streaks and flow marks in a standard light source box.

[0059] Perfume resistance: Add 1ml of perfume to the sample surface, leave at room temperature for 10min, dry in an 80℃ oven for 12h, and observe the appearance after leaving at room temperature for 24h.

[0060] III. Test Results

[0061] The performance test results of the paint-free PC / PBT alloy materials prepared in Examples 1-4 and Comparative Examples 1-3 are shown in Table 2.

[0062] Table 2 Performance test results of PC / PBT alloy materials

[0063]

[0064] Note: Tensile breaking strength refers to longitudinal tensile breaking strength.

[0065] As shown in Table 2, the tensile fracture strength, flexural fracture strength, notched impact strength, and low-temperature notched impact strength of the paint-free PC / PBT alloy materials prepared in Examples 1-4 are superior to those in Comparative Examples 1-3, and the defects such as material bloom and flow marks are fewer than those in Comparative Examples 1-3. However, due to the lack of PBT resin, PTW, or AS carrier aluminum powder masterbatch, the mechanical properties and appearance of the paint-free PC / PBT alloy materials prepared in Comparative Examples 1-3 do not achieve optimal results. Therefore, this invention, by selecting a blend of PBT resin and PC resin as the matrix material, using PTW as a toughening agent, and using AS as a carrier for the metal pigment masterbatch, improves the compatibility between the metal pigment and the matrix through the synergistic effect of PBT, PTW, and AS. Furthermore, the use of a side-feeding process for adding metal pigment solves the technical problem of poor compatibility between the metal pigment and the matrix in existing paint-free alloy materials. The prepared paint-free alloy material has no material bloom at the gate, no flow marks on the surface, and excellent mechanical properties.

[0066] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0068] The present invention has been illustrated with the above embodiments to describe the detailed process flow of the present invention. However, the present invention is not limited to the above detailed process flow, that is, it does not mean that the present invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a paint-free PC / PBT alloy material, characterized in that, The process includes the following steps: blending polycarbonate resin, polybutylene terephthalate resin with toughening agent and compatibilizer to obtain a premix; and then preparing a paint-free PC / PBT alloy material by melt blending the premix with AS carrier metal powder masterbatch.

2. The method for preparing the paint-free PC / PBT alloy material as described in claim 1, characterized in that, The toughening agent is an ethylene-butyl acrylate-glycidyl methacrylate terpolymer.

3. The method for preparing the paint-free PC / PBT alloy material as described in claim 1, characterized in that, The weight ratio of the polybutylene terephthalate resin, toughening agent, and AS carrier metal powder masterbatch is 10-30:3-6:2-5, and the metal powder content in the AS carrier aluminum powder masterbatch is 40-50%, with a particle size of 25-50μm.

4. The method for preparing the paint-free PC / PBT alloy material as described in claim 1, characterized in that, The metal powder in the AS carrier metal powder masterbatch is selected from aluminum powder.

5. The method for preparing the paint-free PC / PBT alloy material as described in claim 1, characterized in that, The compatibilizer is a random copolymer of styrene-acrylonitrile-glycidyl methacrylate.

6. The method for preparing the paint-free PC / PBT alloy material as described in claim 1, characterized in that, The polycarbonate resin is bisphenol A type polycarbonate, and the melt mass flow rate at 300℃ / 1.2kg load is 10-20 g / 10min.

7. The method for preparing the paint-free PC / PBT alloy material as described in claim 1, characterized in that, The melt flow rate of the polybutylene terephthalate resin at 250℃ / 2.16kg load is 20-25 g / 10min.

8. The method for preparing the paint-free PC / PBT alloy material as described in claim 1, characterized in that, The preparation method of the paint-free PC / PBT alloy material also includes the use of antioxidants and lubricants.

9. The method for preparing the paint-free PC / PBT alloy material as described in claim 8, characterized in that, At least one of the following conditions must be met: The antioxidant is selected from one or more of tris(2,4-di-tert-butylphenyl) phosphite, β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, and bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite. The lubricant is selected from one or more of silicone powder, ethylene bis-stearamide, and pentaerythritol stearate.

10. A paint-free PC / PBT alloy material prepared by the preparation method according to any one of claims 1-9, characterized in that, The paint-free PC / PBT alloy material comprises the following components in parts by weight: Polycarbonate resin: 60-80 parts; Polybutylene terephthalate resin: 10-30 parts; Toughening agent: 3-6 parts; Compatibilizer: 0.5-1 part; Antioxidant: 0.5-1 part; Lubricant: 0.5-1 part; AS carrier metal powder masterbatch: 2-5 parts.

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