Resin composition for electroplating and preparation and application thereof

Abstract

The invention belongs to the field of high polymer materials, and relates to a resin composition for electroplating as well as a preparation method and application thereof. The resin composition includes a graft copolymer (A1), a graft copolymer (A2) obtained by graft copolymerization of two diene-based rubber polymers having different particle sizes, and a copolymer (B) obtained by copolymerization of an aromatic vinyl compound and a vinyl cyanide compound, the resin composition is obtained by co-extruding graft copolymers (A1) and (A2) with a copolymer (B) at 220-250 DEG C. The invention also relates to a resin molded product obtained by injection molding of the resin composition and an electroplated product obtained by electroplating of the resin molded product. According to the invention, a high-temperature extrusion technology is used, so that part of diene rubber is subjected to coalescence to form a hornet-honeycomb-shaped rubber phase structure, and the obtained resin composition has good electroplating binding force, impact strength and high and low temperature cycle performance after electroplating processing.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials, specifically relating to a resin composition for electroplating and its preparation. Background Technology

[0002] In the field of resin materials, thermoplastic resins are widely used in various products due to their excellent processability, moldability, and recyclability, especially in the automotive industry as the main material for interior and exterior trim parts. However, as automotive design demands for aesthetics and durability increase, the limitations of traditional thermoplastic resins in electroplating applications are becoming increasingly apparent.

[0003] While electroplating technology imparts a metallic texture to plastic parts, significantly enhancing the visual appeal and added value of products, the adhesion between the electroplated layer and the resin substrate remains a key obstacle to its further development. Under conditions of high temperature, high humidity, or mechanical stress, insufficient adhesion can easily lead to blistering and peeling of the electroplated layer, not only damaging the product's appearance but also potentially posing safety hazards. To overcome this challenge, researchers have explored various methods.

[0004] Patent CN202111155905.2 adds flux and accelerator during the blending stage, while patent KR1020130152905 adds carbon nanomaterials during the blending stage to improve the electroplating performance of resin materials. However, these methods often come with drawbacks such as increased costs and decreased mechanical properties.

[0005] Patent KR1020140168182 employs a method of blending emulsion-polymerized ABS resin with bulk-polymerized ABS resin to improve the electroplating performance of the resin material. However, this method suffers from limitations in performance improvement, difficulty in particle size control, and significant performance fluctuations.

[0006] Therefore, how to develop a new type of thermoplastic resin composition that can significantly improve the adhesion to electroplated layers while maintaining stable performance has become a technical problem that urgently needs to be solved in the field of resin materials. Summary of the Invention

[0007] In view of the above situation, the purpose of this invention is to provide a novel thermoplastic resin composition that has excellent comprehensive properties after electroplating, and can take into account good electroplating adhesion, notched impact strength and high and low temperature cycling performance, so as to meet the needs of the automotive and other industries for high-quality electroplated plastic parts.

[0008] To achieve the above objectives, a first aspect of the present invention provides a resin composition for electroplating, said resin composition comprising a rubber graft copolymer (A1), a rubber graft copolymer (A2), and a copolymer (B), wherein,

[0009] The rubber graft copolymer (A1) is obtained by graft copolymerization of diene rubber polymers with an average particle size of 70-130 nm, and the rubber graft copolymer (A2) is obtained by graft copolymerization of diene rubber polymers with an average particle size of 280-400 nm.

[0010] The copolymer (B) is obtained by copolymerization of an aromatic vinyl compound and a cyanide vinyl compound.

[0011] A second aspect of the present invention provides a method for preparing the resin composition, wherein the resin composition is obtained by co-extrusion of the rubber graft copolymer (A1), the rubber graft copolymer (A2), and the copolymer (B);

[0012] Preferably, during the co-extrusion, the die head temperature of the main extruder area is 220-250°C.

[0013] A third aspect of the present invention provides a resin molded article obtained by injection molding the resin composition.

[0014] The fourth aspect of the present invention provides an electroplated product obtained by electroplating the aforementioned resin molded article.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] I. The resin composition of the present invention contains two graft copolymers with different particle sizes, which allows the resin to generate two anchoring points of different sizes on the resin surface after the roughening step of the electroplating process. The electroplated metal is embedded in the anchoring points, thereby imparting excellent adhesion strength between the resin and the metal. Specifically, the large anchoring points impart the main adhesion strength between the resin layer and the electroplated layer, while the small anchoring points fill the gaps between the large anchoring points, further enhancing the adhesion strength between the two. Therefore, the synergistic effect of the large and small anchoring points formed by the two graft copolymers with different particle sizes can further improve the electroplating adhesion between the electroplated layer and the resin layer after resin electroplating.

[0017] 2. In the preparation of the resin composition of the present invention, the mixture of rubber graft copolymers (A1) and (A2) is co-extruded with copolymer (B) at high temperature, so that the small-particle-size graft copolymers aggregate under high temperature conditions, thereby forming aggregated honeycomb-shaped anchoring points after coarsening. Compared with the single small-particle-size anchoring points formed under non-high temperature conditions, these honeycomb-shaped anchoring points make the metal layer embedding sites more concentrated, thereby giving the resin better electroplating performance and electroplating adhesion. Attached Figure Description

[0018] Figure 1 This is a scanning electron microscope (SEM) image of the resin composition obtained in Example 7.

[0019] Figure 2 This is a scanning electron microscope (SEM) image of the resin composition obtained in Example 2.

[0020] Figure 3 The image shows a scanning electron microscope (SEM) image of the resin composition obtained in Comparative Example 13. Detailed Implementation

[0021] Typical embodiments embodying the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various variations in different embodiments without departing from the scope of the present invention, and the description herein is for illustrative purposes only and not intended to limit the present invention.

[0022] A first aspect of the present invention provides a resin composition for electroplating, the resin composition comprising a rubber graft copolymer (A1), a rubber graft copolymer (A2), and a copolymer (B).

[0023] For ease of description, the rubber graft copolymer (A1) and rubber graft copolymer (A2) in this article can be simply referred to as graft copolymer (A1) and graft copolymer (A2), respectively.

[0024] In this invention, the total amount of the graft copolymer (A1) and graft copolymer (A2) accounts for 25-35 wt% of the resin composition, and the copolymer (B) accounts for 65-75 wt% of the resin composition.

[0025] Furthermore, when the total amount of the graft copolymer (A1) and graft copolymer (A2) is too small, there are too few anchor points formed during electroplating, which cannot impart excellent electroplating performance and electroplating adhesion to the resin; when the total amount of the graft copolymer (A1) and graft copolymer (A2) is too large, there are too many anchor points formed during electroplating, which cannot form an effective snap-fit ​​structure, resulting in poor electroplating performance and reduced resin electroplating adhesion.

[0026] In some embodiments, the graft copolymer (A1) accounts for 10-30 wt% of the total amount of the graft copolymer (A1) and graft copolymer (A2), and the graft copolymer (A2) accounts for 70-90 wt% of the total amount of the graft copolymer (A1) and graft copolymer (A2).

[0027] In this invention, the graft copolymer (A1) is obtained by graft copolymerization of diene rubber polymers with an average particle size of less than 200 nm (e.g., 70-130 nm) (i.e., small particle size graft copolymer), and the graft copolymer (A2) is obtained by graft copolymerization of diene rubber polymers with an average particle size of greater than 200 nm (e.g., 280-400 nm) (i.e., large particle size graft copolymer).

[0028] In this invention, the graft copolymer (A1) and graft copolymer (A2) are both core-shell structure copolymers containing a shell layer and a core layer, and the core-shell structure can be obtained through graft copolymerization reactions well known in the art.

[0029] In the core-shell graft copolymer (A1), a diene rubber polymer is used as the core, wherein the core layer accounts for 40%-70% of the mass of the graft copolymer (A1); the core-shell structure is a copolymer of two comonomers, an aromatic vinyl compound and a cyanide vinyl compound, as the shell, wherein the shell layer accounts for 30%-60% of the mass of the graft copolymer (A1); preferably, when the aromatic vinyl compound is used as a raw material, it accounts for 65%-75% of the total mass of the shell layer, and when the cyanide vinyl compound is used as a raw material, it accounts for 25%-35% of the total mass of the shell layer.

[0030] In the core-shell graft copolymer (A2), a diene rubber polymer is used as the core, wherein the core layer accounts for 40%-70% of the mass of the graft copolymer (A2). The core-shell structure is a copolymer of two comonomers, an aromatic vinyl compound and a cyanide vinyl compound, and the shell layer accounts for 30%-60% of the mass of the graft copolymer (A2). Preferably, when the aromatic vinyl compound is used as a raw material, it accounts for 65%-75% of the total mass of the shell layer, and when the cyanide vinyl compound is used as a raw material, it accounts for 25%-35% of the total mass of the shell layer.

[0031] In preparing the graft copolymer (A1) or the graft copolymer (A2), the cyanide vinyl compound used is selected from at least one of acrylonitrile, methacrylonitrile and ethylacrylonitrile, and the aromatic vinyl compound used is selected from at least one of styrene, α-methylstyrene and p-methylstyrene; preferably, the aromatic vinyl compound and the cyanide vinyl compound used in preparing the graft copolymer (A1) and the graft copolymer (A2) are the same.

[0032] More preferably, when preparing the graft copolymer (A1) or the graft copolymer (A2), the amount of the aromatic vinyl compound used as a raw material is 65-75 wt% of the sum of the aromatic vinyl compound and the cyanide vinyl compound, respectively, and the amount of the cyanide vinyl compound used as a raw material is 25-35 wt% of the sum of the aromatic vinyl compound and the cyanide vinyl compound, respectively.

[0033] The inventors have discovered that by using two graft copolymers with different particle sizes, two different sized anchoring points can be formed after resin coarsening. The combined effect of these two types of anchoring points can impart superior electroplating performance to the resin material and effectively improve the adhesion strength between the resin layer and the electroplated layer after electroplating. On one hand, the particle size range of the graft copolymers is crucial to improving the electroplating performance of the resin. When the particle size of the raw materials (i.e., diene rubber polymers) used to prepare the two graft copolymers is limited to a certain range, the electroplating performance of the resulting resin composition can be effectively improved. On the other hand, high-temperature extrusion can cause the small-particle-size graft copolymers to agglomerate, thereby forming a honeycomb-like aggregate structure, which can further improve the electroplating performance and electroplating adhesion of this type of resin.

[0034] In some embodiments, the graft copolymer (A1) accounts for 10-30 wt% of the total amount of the graft copolymer (A1) and graft copolymer (A2), and the graft copolymer (A2) accounts for 70-90 wt% of the total amount of the graft copolymer (A1) and graft copolymer (A2).

[0035] In this invention, the copolymer (B) is obtained by copolymerization of an aromatic vinyl compound and a cyanide vinyl compound, and the weight-average molecular weight of the copolymer (B) is preferably 60,000-130,000 g / mol.

[0036] In this invention, when preparing copolymer (B), the aromatic vinyl compound used is selected from at least one of styrene, α-methylstyrene, and p-methylstyrene, and the cyanide vinyl compound used is selected from at least one of acrylonitrile, methacrylonitrile, and ethylacrylonitrile; preferably, the aromatic vinyl compound and cyanide vinyl compound used in preparing copolymer (B) are the same as those used in preparing graft copolymer (A1) and graft copolymer (A2).

[0037] More preferably, when the aromatic vinyl compound is used as a raw material, the amount used accounts for 65-75 wt% of the sum of the aromatic vinyl compound and the cyanide vinyl compound; when the cyanide vinyl compound is used as a raw material, the amount used accounts for 25-35 wt% of the sum of the aromatic vinyl compound and the cyanide vinyl compound.

[0038] In some embodiments, the monomers of the diene rubber polymers used in preparing the graft copolymer (A1) and the graft copolymer (A2) are selected from butadiene and / or isoprene.

[0039] The grafting rate of the graft copolymer (A1) is 40-50%, and the grafting rate of the graft copolymer (A2) is 30-40%.

[0040] A second aspect of the present invention provides a method for preparing the resin composition, which is obtained by co-extrusion of the graft copolymer (A1), graft copolymer (A2) and copolymer (B).

[0041] The descriptions of the graft copolymers (A1), (A2), and (B) have been given above and will not be repeated here. In some embodiments, the copolymer (B) has a weight-average molecular weight of 60,000-130,000 g / mol and is commercially available without special preparation.

[0042] In some embodiments, the co-extrusion temperature (i.e., the die head temperature in the main unit area) can be 220-250°C, preferably 230-240°C. The inventors have discovered that co-extrusion at this temperature causes the diene rubber of the graft copolymer (A1) to aggregate, thereby forming a honeycomb-like rubber phase structure, ultimately improving the electroplating performance and mechanical properties (impact strength) of the resin composition.

[0043] In this invention, when the graft copolymer (A1), graft copolymer (A2) and copolymer (B) are co-extruded, when the total mass of the three is recorded as 100 parts, the total amount of graft copolymer (A1) and graft copolymer (A2) can be 25-35 parts, and the content of copolymer (B) can be 65-75 parts.

[0044] A third aspect of the present invention provides a resin molded article obtained by injection molding the resin composition.

[0045] In some embodiments, the injection temperature of the injection molding is 230-250°C, and the screw speed is, for example, 30-60 rpm.

[0046] A fourth aspect of the present invention provides an electroplated article obtained by electroplating the aforementioned resin molded article.

[0047] Unless otherwise specified, the parts mentioned in this article are parts by mass, and the % mentioned refers to wt%.

[0048] The present invention will be further described in detail below through specific examples. In the following examples and comparative examples:

[0049] The activator is a mixture of water, sodium pyrophosphate, glucose, and ferrous sulfate, and the above raw materials are prepared according to a mass ratio of 100:2:1:0.02.

[0050] The antioxidant is a liquid antioxidant with the brand name SF-50LX produced by Shaofeng Plastics Industry Co., Ltd.

[0051] The copolymer (B) is commercially available from Chi Mei in Taiwan, with the brand name PN128, and its weight average molecular weight is about 11000 g / mol.

[0052] The following prepared a variety of PB latexes, namely PB1-PB10 latexes:

[0053] <Preparation of PB1>

[0054] PB1 is a small-particle-size polybutadiene latex prepared by a butadiene emulsion polymerization process, which is well-known in the art. The preparation process includes mixing specific proportions of raw materials in a reaction kettle, raising the temperature for polymerization, and completing the reaction by adding a terminator, and finally obtaining a product (a mixed system of water + polybutadiene latex), specifically as follows:

[0055] (1) Add 150 parts of water, 3.3 parts of potassium oleate, 1.1 parts of rosin soap, 0.13 parts of potassium hydroxide, 0.3 parts of sodium pyrophosphate, 0.2 parts of tert-dodecyl mercaptan, and 100 parts of butadiene into the reaction kettle in sequence to obtain a mixture;

[0056] (2) Raise the temperature of the mixture to 50 °C, and then add 0.12 parts of potassium persulfate to initiate the polymerization reaction;

[0057] (3) Within 2 h, gradually raise the temperature of the polymerization reaction to 78 °C and maintain this temperature for 8 h;

[0058] (4) Add 0.08 parts of sodium formaldehyde sulfoxylate to terminate the reaction and remove the residual butadiene in the reaction kettle to obtain a small-particle-size polybutadiene latex, and its average particle size and particle size distribution are given in Table 1 below.

[0059] <Preparation of PB2 to PB10>

[0060] The preparation of PB2 to PB10 is based on small-particle-size PB1, obtained by expanding the particle size using chemical agglomeration technology, a process well known in the art. The preparation process includes adjusting the solid content of PB1 latex, adding different amounts of acetic acid for chemical agglomeration, followed by neutralization with potassium hydroxide solution to complete the agglomeration reaction and obtain the target product, as detailed below:

[0061] (1) Take 100 parts (converted according to solid content) of PB1 latex, add water to adjust the solid content to 36% to avoid agglomeration;

[0062] (2) Add different amounts of acetic acid (0.2 parts, 0.3 parts, 0.5 parts, 0.7 parts, 1.0 parts, 1.3 parts, 1.6 parts, 1.8 parts, and 2.1 parts respectively) to the above PB1 latex to regulate and control the particle size of the synthesized polybutadiene latex, and then stir thoroughly for 10 min;

[0063] (3) Neutralize the excess acetic acid with an equimolar amount of KOH aqueous solution (7%), and stir for 3 min to complete the chemical agglomeration, and obtain polybutadiene latex PB2 to PB10 respectively. Their average particle size and particle size distribution are given in Table 1 below.

[0064] Table 1:

[0065] PB1 PB2 PB3 PB4 PB5 PB6 PB7 PB8 PB9 PB10 Amount of acetic acid added, in parts - 0.2 0.3 0.5 0.6 1.0 1.3 1.6 1.8 2.1 Average particle size, nm 70 100 120 180 220 280 320 360 400 450 Particle size distribution 0.083 0.092 0.089 0.0950 0.087 0.096 0.101 0.106 0.126 0.135

[0066] <Testing and Characterization Methods>

[0067] The particle size and particle size distribution of the PB latex were tested as follows: 0.5g of PB latex was weighed and diluted with 100g of deionized water, and 1g of the diluted liquid was weighed and diluted again with 100g of deionized water. An appropriate amount of the diluted latex was poured into a cuvette, and the average particle size and particle size distribution were tested using a Malvern Zetasizer NanoZSP particle size analyzer.

[0068] The bonding strength refers to the electroplating bonding strength, and the test method is as follows: cut the electroplated sample into strips of 100mm*25mm, and perform a 90° peel strength test on the strips on a universal tensile testing machine according to the ASTM B533 standard.

[0069] The impact strength mentioned refers to the notched impact strength, which is tested on the resin composition using an INSTRON 9050 cantilever beam impact testing machine in accordance with ISO 180.

[0070] The cycling performance refers to the high and low temperature cycling performance. The test method is as follows: place the electroplated sample in a -40℃ environment for 1 hour, then in a 90℃ environment for 1 hour. This constitutes one cycle. After 8 cycles of high and low temperature cycling, observe the electroplated layer on the product's appearance and determine the thermal cycling characteristics according to the following criteria:

[0071] Pass: The electroplating layer shows no change.

[0072] Unqualified: The electroplated layer shows abnormal phenomena such as bulging or swelling that affect its appearance.

[0073] In the overall performance rating, the following definitions apply:

[0074] Advantages: Electroplating adhesion ≥10N / cm, notched impact strength ≥25kJ / m 2 Furthermore, its high and low temperature cycling performance is qualified; (meeting all the above conditions)

[0075] Poor: Electroplating adhesion < 7 N / cm, notched impact strength ≤ 20 kJ / m 2 The high and low temperature cycling performance is unqualified; (meeting any one of the above conditions is sufficient).

[0076] Good: A sample that cannot be rated as either excellent or poor.

[0077] Example 1 (Resin Composition IE1)

[0078] <Preparation of graft copolymer (A1)>

[0079] (1) Add 0.002 parts of activator and 0.01 parts of cumene hydroperoxide to PB latex, stir and heat to 65°C to ensure uniform mixing and activation of the raw materials, to obtain reaction solution 1; wherein,

[0080] The PB latex is a PB latex with a particle size of <200nm, i.e., PB1 given in Table 1;

[0081] The PB latex is in the amount of 50 parts (on a dry basis).

[0082] (2) Add 0.09 parts of cumene hydroperoxide (initiator), 36 parts of styrene (first graft monomer), 14 parts of acrylonitrile (second graft monomer), 0.2 parts of tert-dodecyl mercaptan (chain transfer agent), 0.3 parts of potassium oleate (emulsifier) ​​and 12 parts of deionized water to a beaker, and stir thoroughly to obtain reaction solution 2.

[0083] (3) Add reaction solution 2 (25℃) dropwise to reaction solution 1 (65℃) and control the addition time to 3h;

[0084] (4) After the addition is complete, the reaction system is heated to 80°C and reacted for 3 hours. After the reaction, the temperature is lowered to ambient temperature, and 0.1 parts of antioxidant are added to obtain grafted latex with a grafting rate of about 45%.

[0085] (5) Prepare the coagulation solution (4 parts magnesium sulfate, 1 part acetic acid and 100 parts deionized water) and heat it to 70°C;

[0086] (6) Drop 100 parts of grafted latex into the coagulation solution (for 1 hour) and heat to 90°C for 1 hour.

[0087] (7) After aging, the temperature is lowered to ambient temperature and the wet grafted gum powder is obtained by filtration through a Buchner funnel.

[0088] (8) The wet grafted rubber powder was dried in a vacuum drum (60℃, 2kPa, 4h) to obtain ABS rubber powder with a wet content of less than 1%, that is, grafted copolymer (A1) rubber powder with a core-shell ratio of 50 / 50.

[0089] <Preparation of graft copolymer (A2)>

[0090] Similar to the above <Preparation of Graft Copolymer (A1)>, the difference is:

[0091] In step (1), the PB latex is a PB latex with a particle size ≥200nm, i.e., PB6 given in Table 1; the number of parts of the PB latex is 60 parts (on a dry basis).

[0092] In step (2), the amount of styrene is 28.8 parts and the amount of acrylonitrile is 11.2 parts.

[0093] In step (4), the grafting rate of the grafted latex is 38%.

[0094] In step (8), a graft copolymer (A2) powder with a core-shell ratio of 60 / 40 is obtained.

[0095] <Preparation of Resin Composition Granules>

[0096] Using a ZSK 26O 10.6 Coperion twin-screw extruder, the graft copolymer (A1), graft copolymer (A1), and copolymer (B) were blended according to the proportions shown in Table 2. The mixture was then co-extruded to obtain granular resin products.

[0097] The parameters for co-extrusion include: the main machine temperature is 195℃ (zone 1), 200℃ (zone 2), 210℃ (zone 3), 215℃ (zone 4) and 220℃ (die head temperature, i.e., the extrusion temperature in Table 2 below), the main machine speed is 120 rpm, the feeder speed is 14 rpm, and the pelletizer speed is 7 rpm.

[0098] <Preparation of Molded Articles from Resin Compositions>

[0099] An injection molding machine of model number Ningbo Haitian was used to injection mold the resin composition to obtain a resin molded product; wherein...

[0100] The injection temperature for the injection molding process is 240°C, and the screw speed is 50 rpm.

[0101] Examples 2 to 9 (Resin compositions IE2 to IE9)

[0102] The procedure was carried out in accordance with Example 1, with only the following adjustments as shown in Table 2:

[0103] The type of PB latex in the graft copolymer (A1) and the amount of graft copolymer (A1) incorporated;

[0104] The type of PB latex in the graft copolymer (A2) and the amount of graft copolymer (A2) incorporated;

[0105] The temperature (i.e., die head temperature) during co-extrusion of the graft copolymer (A1), graft copolymer (A2) and copolymer (B).

[0106] Compared with Example 1, the specific adjustments made in the preparation process of resin compositions IE2 to IE10 in Examples 2-10 are shown in Table 2.

[0107] Comparative Examples 1 to 7 (Resin Compositions CE1 to CE7)

[0108] The procedure was carried out in accordance with Example 1, with only the following adjustments as shown in Table 2:

[0109] The type of PB latex in the graft copolymer (A1) and the amount of graft copolymer (A1) incorporated;

[0110] The type of PB latex in the graft copolymer (A2) and the amount of graft copolymer (A2) incorporated;

[0111] The temperature (i.e., die head temperature) during co-extrusion of the graft copolymer (A1), graft copolymer (A2) and copolymer (B).

[0112] Compared with Example 1, the specific adjustments made in the preparation process of resin compositions CE1 to CE6 in Comparative Examples 1-6 are shown in Table 2.

[0113] Comparative Examples 8 to 19 (Resin Compositions CE8 to CE19)

[0114] The procedure was carried out in accordance with Example 1, with only the following adjustments as shown in Table 2:

[0115] In Comparative Examples 8 to 12, only graft copolymer (A1) and copolymer (B) were added, and graft copolymer (A2) was not added; in Comparative Examples 13 to 19, only graft copolymer (A2) and copolymer (B) were added, and graft copolymer (A1) was not added. In Comparative Examples 18-19, the amount of copolymer (B) incorporated was also adjusted.

[0116] Compared with Example 1, the specific adjustments made in the preparation process of resin compositions CE8 to CE19 in Comparative Examples 8-19 are shown in Table 2.

[0117] The resin compositions obtained in the above examples and comparative examples were entrusted to Sanhuan Electroplating Plant for electroplating according to the standard electroplating process. Three metal coatings, namely a copper layer (15μm), a nickel layer (25μm), and a chromium layer (0.3μm), were sequentially electroplated on the surface of the resin composition. The performance of the obtained electroplated samples was evaluated, and the results are shown in Table 2.

[0118] Table 2:

[0119]

[0120]

[0121] A comparison of Examples 1-9 and Comparative Examples 8-19 shows that when ABS resin contains both graft copolymer (A1) and graft copolymer (A2), after roughening in the electroplating process, two different sizes of anchor points can be formed. These two different sized anchor points work together to improve the electroplating adhesion of the thermoplastic resin (as shown in Example 7). Figure 1 Example 2 Figure 2 and the corresponding comparative example 14 Figure 3 Furthermore, when rubber with different particle sizes is present, according to the crazing-shear band toughening mechanism, larger particle sizes are more likely to induce crazing, while smaller particle sizes are more likely to induce shear bands. The combined effect of both improves the impact resistance of the resin composition. Compared with the comparative examples, the embodiments of this invention achieve a good balance of bonding strength, impact strength, and cycling performance, exhibiting superior overall performance.

[0122] As can be seen from the comparison between Example 3 and Comparative Example 1, or Example 4 and Comparative Example 2, or Comparative Example 3 and Comparative Example 4, when the particle size of the small-particle-size diene rubber is too large, the synergistic effect of the graft copolymer (A1) and graft copolymer (A2) is reduced, and the effect of improving the electroplating performance and impact resistance of the resin composition is weakened.

[0123] As can be seen from the comparison of Examples 2 and 5 with Comparative Example 4, when the particle size of the large-particle-size diene rubber is too large (over 400 nm), the synergistic effect of the graft copolymer (A1) and graft copolymer (A2) is reduced, and the effect on improving the electroplating performance and impact resistance of the resin composition is weakened.

[0124] A comparison of Examples 2 with Examples 6, 7, and 9 shows that adjusting the die head temperature (i.e., extrusion temperature) to 230-250℃ can significantly improve the electroplating adhesion and impact resistance of the resin composition. (Comparison of Examples 6, 7, and 9 further illustrates this point.) Figure 1 With appendix Figure 2It can be clearly observed that increasing the extrusion temperature leads to significant agglomeration of the small-particle-size rubber graft copolymer. The resulting honeycomb structure provides stronger adhesion between the electroplated layer and the resin layer, thereby enhancing the electroplating bonding force of the resin composition. Furthermore, this honeycomb structure better resists external impacts, allowing for more concentrated stress release, thus giving the resin composition superior impact resistance. However, when the temperature exceeds 250℃, copolymer (B) undergoes some degradation, leading to a decrease in the overall performance of the resin composition.

[0125] As can be seen from the comparison between Example 1 and Comparative Example 5, when the extrusion temperature is higher than the range of the present invention, the overall performance, including electroplating adhesion, notched impact strength and high and low temperature cycling performance, decreases.

[0126] As can be seen from the comparison between Example 7 and Comparative Examples 6-7, when the proportion of graft copolymer (A1) (i.e. small particle size copolymer) is higher than the range of the present invention, that is, when the proportion of graft copolymer (A2) (i.e. large particle size copolymer) is lower than the range of the present invention, the notched impact strength of the product will decrease.

[0127] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A resin composition for electroplating, characterized in that, The resin composition comprises a rubber graft copolymer (A1), a rubber graft copolymer (A2), and a copolymer (B), wherein, The rubber graft copolymer (A1) is obtained by graft copolymerization of diene rubber polymers with an average particle size of 70-130 nm, and the rubber graft copolymer (A2) is obtained by graft copolymerization of diene rubber polymers with an average particle size of 280-400 nm. The copolymer (B) is obtained by copolymerization of an aromatic vinyl compound and a cyanide vinyl compound.

2. The resin composition according to claim 1, characterized in that, The total amount of the rubber graft copolymer (A1) and the rubber graft copolymer (A2) accounts for 25-35 wt% of the resin composition; The copolymer (B) comprises 65-75 wt% of the resin composition.

3. The resin composition according to claim 1 or 2, characterized in that, The rubber graft copolymer (A1) accounts for 10-30 wt% of the total amount of the rubber graft copolymer (A1) and the rubber graft copolymer (A2); The rubber graft copolymer (A2) accounts for 70-90 wt% of the total amount of the rubber graft copolymer (A1) and the rubber graft copolymer (A2).

4. The resin composition according to any one of claims 1 to 3, characterized in that, Both the rubber graft copolymer (A1) and the rubber graft copolymer (A2) are core-shell structure copolymers comprising a shell layer and a core layer; wherein, The core-shell structure uses the diene rubber polymer as the core, wherein the core layer accounts for 40%-70% of the mass of the rubber graft copolymer; preferably, the polymerizing monomer of the diene rubber polymer is selected from butadiene and / or isoprene; The core-shell structure uses a copolymer of aromatic vinyl compounds and cyanide vinyl compounds as the shell, wherein the shell layer accounts for 30%-60% of the mass of the rubber graft copolymer. Preferably, the grafting rate of the rubber graft copolymer (A1) is 40-50%; Preferably, the grafting rate of the rubber graft copolymer (A2) is 30-40%.

5. The resin composition according to any one of claims 1 to 4, characterized in that, When preparing copolymer (B), preparing rubber graft copolymer (A1), or preparing rubber graft copolymer (A2), The aromatic vinyl compounds used are selected from at least one of styrene, α-methylstyrene, and p-methylstyrene; The cyanide vinyl compounds used are selected from at least one of acrylonitrile, methacrylonitrile and ethyl acrylonitrile; Preferably, the aromatic vinyl compound and the cyanide vinyl compound used in the copolymer (B), the rubber graft copolymer (A1), and the rubber graft copolymer (A2) are the same.

6. The resin composition according to any one of claims 1 to 5, characterized in that, When preparing copolymer (B), preparing rubber graft copolymer (A1), or preparing rubber graft copolymer (A2), The amount of the aromatic vinyl compound used as a raw material is 65-75 wt% of the sum of the amounts of the aromatic vinyl compound and the cyanide vinyl compound, respectively; The amount of the cyanide vinyl compound used as a raw material is 25-35 wt% of the sum of the amounts of the aromatic vinyl compound and the cyanide vinyl compound.

7. A method for preparing a resin composition according to any one of claims 1 to 6, characterized in that, The resin composition is obtained by co-extrusion of the rubber graft copolymer (A1), the rubber graft copolymer (A2), and the copolymer (B); Preferably, during the co-extrusion, the die temperature of the main extruder area is 220-250°C, causing the rubber graft copolymers (A1) and (A2) to aggregate, thereby forming a honeycomb-like rubber phase structure in the resin composition.

8. The preparation method according to claim 7, characterized in that, Based on a total mass of 100 parts for the rubber graft copolymer (A1), the rubber graft copolymer (A2), and the copolymer (B), The total amount of the rubber graft copolymer (A1) and the rubber graft copolymer (A2) is 25-35 parts, and the amount of the copolymer (B) is 65-75 parts.

9. A resin molded article obtained by injection molding from a resin composition according to any one of claims 1 to 6 or a resin composition obtained by the preparation method according to claim 7 or 8.

10. An electroplated article obtained by electroplating the resin molded article of claim 9.

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