Injection molding method of double-color product capable of presenting wheat ear grains

Abstract

The invention discloses a double-color product injection molding method capable of presenting wheat ear grain textures, which comprises the following steps: carrying out one-shot molding on a transparent PC material to obtain a one-shot product, and molding a wheat ear grain texture surface on the surface of one side of the one-shot product, the wheat ear grain texture surface being obtained by irregular strip-shaped grooves formed on the surface of one side of the one-shot product, one side, facing the surface provided with the wheat ear grains, of the cross section, in the transverse direction of the wheat ear grains, of the one-shot product is in a sawtooth shape; a second-injection product is formed on the side, provided with the wheat ear grain texture surface, of the first-injection product in a second-injection mode through ABS and PC materials; during one-shot molding, the injection material temperature of the PC material is 260 DEG C, the mold temperature of the mold is 100 DEG C, and the maximum injection pressure of one-shot molding is not greater than 70 MPa; the dwell pressure is 25 MPa, and the dwell time is 5 s; during secondary injection molding, the melt index of the ABS + PC material is not less than 18 g / 10 min, and the maximum injection pressure of secondary injection molding is not more than 60 MPa. The problem that the appearance of a double-color product capable of presenting wheat ear grains is poor is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of automotive interiors, and particularly relates to an injection molding method for two-color products capable of presenting wheat ear pattern textures. Background Art

[0002] With the intensification of competition in the automotive market, people's requirements for the quality of automotive interiors are getting higher and higher. The appearance quality of automotive interiors reflects the grade of the vehicle and also greatly affects vehicle sales. Traditional automotive interiors generally use a wrapping process, and the appearance of automotive interiors manufactured by this process is relatively single. However, two-color products produced by the double-shot injection molding process as automotive interiors make the appearance of automotive interiors more diverse and the shapes more dazzling, such as two-color products on the upper and middle parts of door trim panels that can present wheat ear pattern textures. However, when manufacturing two-color products capable of presenting wheat ear pattern textures by the double-shot injection molding method, local "white streaks" often appear on the appearance, and the defect rate is as high as about 50%, thus reducing the appearance quality of automotive interiors. Summary of the Invention

[0003] The purpose of the present invention is to provide an injection molding method for two-color products capable of presenting wheat ear pattern textures, and solve the problem of defective appearance of two-color products capable of presenting wheat ear pattern textures.

[0004] The present invention is achieved by the following technical solutions: An injection molding method for two-color products capable of presenting wheat ear pattern textures, comprising the following steps: Using a transparent PC material to perform the first-shot molding to produce a first-shot product, and forming a wheat ear pattern texture surface on one side surface of the first-shot product. The wheat ear pattern texture surface is obtained from irregular strip-shaped grooves formed on one side surface of the first-shot product, and the cross-section of the first-shot product in the transverse direction of the wheat ear pattern texture is serrated on the side facing the wheat ear pattern texture surface; Using an ABS+PC material to perform the second-shot molding on the side of the first-shot product provided with the wheat ear pattern texture surface to produce a second-shot product, and forming a wheat ear pattern texture surface on the second-shot product that matches the wheat ear pattern on the first-shot product, thereby obtaining a two-color product capable of presenting wheat ear pattern textures; During the first-shot molding, the injection temperature of the PC material is 260°C, the mold temperature of the mold is 100°C, and the maximum injection pressure for the first-shot molding is not greater than 70 MPa; the holding pressure is 25 MPa, and the holding time is 5 s; During the second-shot molding, the melt index of the ABS+PC material is not less than 18 g / 10 min, and the maximum injection pressure for the second-shot molding is not greater than 60 MPa.

[0005] In some embodiments, a mold core for forming a surface with wheat ear pattern texture on the mold is provided with a wheat ear pattern texture forming surface that matches the structure of the wheat ear pattern texture surface. The chamfer diameter of the sharp corner at the serrated bottom of the wheat ear pattern texture forming surface in the cross-section along the transverse direction of the wheat ear pattern texture is not greater than 0.1 mm.

[0006] In some embodiments, flanges are respectively provided on the peripheries between the first-shot product and the second-shot product for mating. The peripheries between the first-shot product and the second-shot product are connected by the mating of the flanges. The flange on the first-shot product is arranged towards the side where the surface with wheat ear pattern texture is located.

[0007] In some embodiments, a transition fillet is provided between the flange of the first-shot product and the body of the first-shot product. The thickness of the flange of the first-shot product is equal to the radius of the transition fillet and its inner side is flush with the starting end of the transition fillet.

[0008] In some embodiments, pressing blocks are respectively provided at the upper and lower ends and the gate side of the first-shot product on the mold for pressing the formed first-shot product.

[0009] In some embodiments, the total thickness of the first-shot product and the second-shot product is 3.1 - 3.4 mm, and the thickness of the surface with wheat ear pattern texture is 0.6 - 0.8 mm.

[0010] In some embodiments, it further includes the step of spraying UV paint on the surface of the first-shot product of the formed two-color product. Before spraying the UV paint, a masking layer is provided on the surface where the bonding position between the first-shot product and the second-shot product is located to mask the bonding position between the first-shot product and the second-shot product.

[0011] In some embodiments, in the components of the UV paint by weight ratio, the ratio of paint : curing agent : thinner is 4:1:6 - 7.

[0012] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. Aiming at the serrated cross-section structure characteristics of the wheat ear pattern, to avoid the problem of "white streaks" appearing on the product due to incomplete filling at the serrated sharp corner positions during the first shot and the second shot, the method of the present invention controls parameters such as the injection material temperature, mold temperature, maximum injection pressure, holding pressure, holding time, etc. of the first shot and the melt index and maximum injection pressure of the ABS+PC material, and well improves the problems existing in the injection molding and filling for the serrated cross-section, reduces the generation of "white streaks", and improves the appearance quality of the two-color product.

[0013] 2. Pressing blocks are respectively provided at the upper and lower ends and the gate side of the first-shot product on the mold for pressing the formed first-shot product, avoiding the appearance of "white streaks" due to external force in the direction of the wheat ear pattern texture surface, and improving the appearance quality of the two-color product.

[0014] 3. Before spraying the UV paint, a masking layer is provided on the surface where the bonding position between the first-shot product and the second-shot product is located to mask the bonding position between the first-shot product and the second-shot product, preventing the UV paint from penetrating along the bonding position into the two-color product and causing corrosion to produce "white streaks".

[0015] 4. Dilute the UV paint according to the ratio of paint: curing agent: thinner of 4:1:6 - 7 to reduce the corrosiveness of the paint and reduce the generation of "white streaks". Description of the Drawings

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 It is a sectional view of the first-shot product in the embodiment of the present invention.

[0018] Figure 2 It is a partial schematic diagram of the wheat ear pattern texture of the sectional view of the first-shot product in the embodiment of the present invention.

[0019] Figure 3 It is a schematic diagram of the surface structure of the wheat ear pattern texture of the first-shot product in the embodiment of the present invention.

[0020] Figure 4 It is a schematic diagram of the structure of the flanging and transitional fillet of the first-shot product in the embodiment of the present invention.

[0021] Figure 5 It is a schematic diagram of the setting structure of the pressing block on the mold before improvement in the embodiment of the present invention.

[0022] Figure 6 It is a schematic diagram of the setting structure of the pressing block on the mold after improvement in the embodiment of the present invention.

[0023] Figure 7 It is a schematic diagram of the gate layout of the first-shot molding in the embodiment of the present invention.

[0024] Figure 8 It is a schematic diagram of the gate layout of the second-shot molding in the embodiment of the present invention.

[0025] Figure 9 It is a schematic diagram of the wheat ear pattern texture structure machined and formed on the mold core in the embodiment of the present invention.

[0026] Wherein: 1 - first-shot product, 101 - wheat ear pattern texture, 102 - flanging, 103 - transitional fillet, 2 - pressing block, 3 - mold core. Detailed implementation manners

[0027] 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 will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention.

[0028] The wheat ear pattern texture 101 is directly injection-molded on the product. Due to the small structural size of the wheat ear pattern texture 101 on the product surface and the serrated structure of the wheat ear pattern texture, it is difficult to effectively fill the position of the wheat ear pattern texture during injection molding using a conventional injection molding process. Especially during two-color injection molding, after the wheat ear pattern texture 101 is formed on the first-shot product 1, a second-shot product needs to be formed on the surface of the wheat ear pattern texture. There are problems that the upper and lower sharp corners of the wheat ear pattern texture cannot be effectively filled during both the first-shot molding and the second-shot molding.

[0029] During product molding, it is found that "white streaks" of varying degrees will appear on the surface of the molded product. Especially under the illumination of the atmosphere lamp, the "white streaks" phenomenon is more obvious, seriously affecting the appearance quality and visual effect of the product. After research, it is found that the main reasons for the generation of "white streaks" may come from the following factors: In this embodiment, the first-shot of the product uses a transparent PC material, and the second-shot uses a black ABS+PC material. The toughness of the first-shot material and the second-shot material is insufficient, which will cause cracks in the first-shot product 1 during the second-shot, resulting in the appearance of the "white streaks" defect on the product surface.

[0030] The melt index of the second-shot material is not high enough, resulting in poor plastic fluidity. During the second-shot filling process, the second-shot material cannot smoothly fill into the sharp corner gaps of the first-shot product, resulting in gaps in the filling, thereby forming "white streaks".

[0031] The size of the serrated structure of the wheat ear pattern texture of the product is small. The wheat ear pattern texture contour of the wheat ear pattern texture mold core 3 obtained by using a conventional tool is not clear and the grooves are not flat, making the wheat ear pattern texture lines not smooth. During injection molding, it affects the effective filling of the wheat ear pattern texture, resulting in gaps in the filling, and causing the appearance of the "white streaks" defect on the product surface.

[0032] The injection temperature and mold temperature of the first-shot will affect the fluidity of the first-shot material, making the first-shot material unable to smoothly fill into the sharp corner gaps of the wheat ear pattern texture mold core, resulting in gaps in the first-shot product 1, thereby forming "white streaks".

[0033] There is a poor bonding situation in the overlap of the flanging 102 between the first-shot product 1 and the second-shot product. There is a gap at the position of poor bonding. When spraying UV paint, the UV paint easily penetrates from the position of poor bonding into the interlayer between the first-shot product 1 and the second-shot product, forming microscopic corrosion. Moreover, the transparent rounded corner at the position of poor bonding of the flanging 102 has a magnifying effect like a convex lens, which will magnify the microscopic corrosion at the place where the interlayer between the first-shot product 1 and the second-shot product is poorly bonded, resulting in obvious "white stripes" on the product surface.

[0034] After the first-shot product 1 is injection-molded, the smooth surface remains in the fixed mold. When injecting the second-shot material ABS+PC, relative displacement between the second shot and the first-shot product 1 is not allowed. Refer to Figure 5 , so a plurality of pressing blocks 2 are arranged on the flanging 102 around the first-shot product 1 to keep the position of the first-shot product 1 unchanged. However, after the first-shot product 1 is formed, natural shrinkage will occur. When shrinking, mutual pulling force will be generated between the first-shot product 1 and the pressing blocks 2, generating stress cracks, thus resulting in obvious "white stripes" on the product surface.

[0035] In view of the above problems and possible influencing factors, the present invention provides a two-color product injection molding method capable of presenting wheat ear pattern texture, including the following steps: The first-shot product 1 is injection-molded with transparent PC material, and a wheat ear pattern texture surface is formed on one side surface of the first-shot product. Refer to Figure 1 、 Figure 2 and Figure 3 , the wheat ear pattern texture surface is obtained from irregular strip-shaped grooves formed on one side surface of the first-shot product, and the cross-section of the first-shot product in the lateral direction of the wheat ear pattern texture is serrated on the side facing the wheat ear pattern texture surface; The second-shot product is injection-molded with ABS+PC material on the side of the first-shot product 1 where the wheat ear pattern texture surface is provided, and a wheat ear pattern texture surface matching the wheat ear pattern texture 101 on the first-shot product 1 is formed on the second-shot product, obtaining a two-color product capable of presenting wheat ear pattern texture; During the first-shot molding, the injection temperature of the PC material is 260 °C, the mold temperature of the mold is 100 °C, and the maximum injection pressure of the first-shot molding is not greater than 70 MPa; the holding pressure is 25 MPa, and the holding time is 5 s; During the second-shot molding, the melt index of the ABS+PC material is not less than 18 g / 10 min, and the maximum injection pressure of the second-shot molding is not greater than 60 MPa.

[0036] In view of the serrated cross-sectional structure characteristics of the wheat ear pattern, in order to avoid the problem of "white streaks" on the product caused by incomplete filling at the sharp corners of the serrations during the first shot and the second shot, the method of the present invention controls parameters such as the injection material temperature, mold temperature, maximum injection pressure, holding pressure, holding time, etc. of the first shot and the melt index and maximum injection pressure of the ABS+PC material, and well improves the problems existing in the injection molding and filling of the serrated cross-section, reduces the generation of "white streaks", and improves the appearance quality of the two-color product.

[0037] Among them, the thickness of the first-shot product is 2.5 mm, and the first-shot material uses a PC material with a tensile modulus of 2400 Mpa and a fracture elongation rate greater than 50% to increase the impact resistance and toughness of the first-shot material, thereby reducing the impact deformation of the first-shot product 1 caused by the injection pressure of the second shot and forming intermittent small cracks, and reducing the intermittent "white streaks" on the product surface.

[0038] The second-shot material ABS+PC is black, and the thickness of the second-shot product is 2.5 mm.

[0039] After the first-shot product 1 is molded, the moving mold in the mold rotates 180° and then the second shot is carried out.

[0040] During the first shot and the second shot, a suitable number of gate openings are designed according to the maximum injection pressure. Designing a suitable number of gate openings according to the maximum injection pressure can reduce the "white streaks" caused by cracks generated by internal stress; the number of gate openings for the first shot is 5, referring to Figure 7 , the gate positions are set at intervals in the length direction of the first-shot product. The distances between the gate at one end of the product and the product end and between the gates are set to 125 mm, 139 mm, 133 mm, 140 mm, 145 mm, and 150 mm in sequence. The gate type is a side gate, the hot runner size is 18*6 mm, the hot gate size is 5 mm, the cold gate size is 20*1.3 mm, and the cold runner size is 10*8 mm; the number of gate openings for the second shot is 5, referring to Figure 8 , the gate positions are set at intervals in the length direction of the second-shot product. The distances between the gate at one end of the product and the product end and between the gates are set to 130 mm, 118 mm, 134 mm, 139 mm, 145 mm, and 167 mm in sequence. The gate type is a tunnel gate, the hot runner size is 15*6 mm, the hot gate size is 5 mm, the cold gate size is 20*1.3 mm, and the cold runner size is 10*8 mm.

[0041] In some embodiments, on the mold core 3 for forming the wheat ear pattern texture surface on the mold, there is a wheat ear pattern texture forming surface that matches the wheat ear pattern texture surface structure. Referring to Figure 9 , the chamfer diameter of the sharp corner at the bottom of the serrations in the cross-section of the wheat ear pattern texture forming surface in the transverse direction of the wheat ear pattern texture is not greater than 0.1 mm.

[0042] Among them, the mold core 3 with a wheat ear pattern texture surface is processed with a special hard tool for the serrated bottom sharp corners of the wheat ear pattern texture, so that the chamfer diameter of the serrated bottom sharp corners of the wheat ear pattern texture is not greater than 0.1 mm. The hard tool is a ball-end tool, the radius of the ball-end tool ≤ 0.1 mm, and the rotational speed of the ball-end tool ≥ 25,000 revolutions per second. The ball-end tool is used for processing the wheat ear pattern texture 101, ensuring the clarity of the wheat ear pattern texture contour and the smoothness of the wheat ear pattern texture grooves, meeting the smoothness of the appearance line, improving the processing accuracy of the wheat ear pattern texture 101, and avoiding the "white stripe" at a fixed position on the two-color product due to insufficient processing technology and poor stability of the wheat ear pattern texture 101.

[0043] In some embodiments, the first-shot product 1 is respectively provided with mating flanges 102 around it. The first-shot product 1 and the second-shot product are cooperatively connected through the flanges 102 around them. The flanges 102 on the first-shot product 1 are arranged towards the side with the wheat ear pattern texture surface.

[0044] Among them, the thickness dimension of the flange 102 is 2.5 mm.

[0045] In some embodiments, a transition fillet 103 is provided between the flange 102 of the first-shot product and the body of the first-shot product. The thickness of the flange 102 of the first-shot product is equal to the radius of the transition fillet and its inner side is flush with the starting end of the transition fillet.

[0046] The flanges 102 at both ends of the first-shot product are in an L-shaped structure. Refer to Figure 4 , by increasing the thickness of the inner sides of the flanges 102 at both ends, the inner side walls of the flanges are flush with the starting ends of the transition fillets. In this way, when the second-shot product is formed on the first-shot product 1, the inner side walls of the second-shot product at the flange positions can be flush with the transition fillets 103, which can reduce the impact of the second-shot product during forming on the first-shot product 1.

[0047] The R angle of the L-shaped first-shot product is aligned with the side wall of the second-shot product, thereby increasing the structural strength of the first-shot product, improving the impact resistance of the first-shot product 1 to the second-shot extrusion, reducing the extrusion force exerted by the second-shot product on the first-shot product 1, reducing the influence of the second-shot forming on the quality of the first-shot product, and avoiding the generation of "white stripes".

[0048] In some embodiments, refer to Figure 6 , pressing blocks 2 are respectively arranged at the upper and lower ends and the gate side of the first-shot product on the mold for pressing the formed first-shot product 1.

[0049] After the first-shot product 1 is formed, the first-shot product 1 will undergo natural shrinkage. When the first-shot product 1 shrinks, mutual pulling forces will be generated between the first-shot product 1 and the pressing block 2, resulting in stress cracks. Therefore, the pressing block 2 on one side of the first-shot product is cancelled, and the pressing blocks 2 respectively arranged at the upper and lower ends and the gate side of the first-shot product are retained. Only the upper and lower ends of the first-shot product and the position on one side of the gate side are pressed, so that while the relative position of the first-shot product does not change, it is possible to avoid the formation of "white streaks" due to the mutual pulling forces generated by the pressing blocks 2 in the direction of the wheat ear pattern texture and the appearance of cracks.

[0050] In some embodiments, the total thickness of the first-shot product 1 and the second-shot product is 3.1 - 3.4 mm, and the thickness of the surface with the wheat ear pattern texture is 0.6 - 0.8 mm.

[0051] When there is a poor bonding of the flanging 102 during the lap joint of the two-color product, due to the magnifying effect of the transparent rounded corner at the position of the poor bonding of the flanging 102, the poor bonding area between the first-shot product 1 and the second-shot product will be magnified. There is a situation where f < u < 2f and v > 2f, the object distance is between 1 - 2 times the focal length, and the image distance > 2 times the focal length. Here, u represents the distance from the object to the convex lens, v represents the distance from the image to the convex lens, and f represents the focal length, which will make the "white streak" phenomenon more obvious.

[0052] At the same time, when the first-shot product 1 and the second-shot product are poorly bonded at the flanging 102 position, during the operation of spraying UV paint on the product, the UV paint penetrates through the position of the poor bonding of the flanging 102 into the interlayer of the two-color product, forming microscopic corrosion. In some embodiments, it further includes the step of spraying UV paint on the surface of the first-shot product of the formed two-color product. Before spraying the UV paint, a masking layer is provided on the surface where the bonding position between the first-shot product 1 and the second-shot product is located to mask the bonding position between the first-shot product 1 and the second-shot product.

[0053] Setting a masking layer on the surface where the flanging 102 bonding position is located before spraying the UV paint can prevent the UV paint from penetrating through the position of the poor bonding of the flanging 102 into the interlayer of the two-color product, forming microscopic corrosion, thereby avoiding the obvious "white streaks" visually.

[0054] In some embodiments, in terms of the weight ratio of the components of the UV paint, the ratio of paint : curing agent : diluent is 4 : 1 : 6 - 7.

[0055] Among them, the paint is butyl acetate, the curing agent is a lipid UV light-curing agent, and the diluent is an ethyl acetate-based diluent and a leveling agent.

[0056] Optimize the dilution of the UV paint to reduce the corrosiveness of the paint and avoid the formation of intermittent "white streaks" on the surface of the two-color product due to paint corrosion.

[0057] Using the above injection molding method can greatly reduce the generation of "white streaks", enabling the yield of two-color products with wheat ear pattern texture to reach over 90%.

[0058] Example 1 The product parameters of the two-color product with wheat ear pattern texture in this example are as follows: The thickness of the first-shot material is 2.5 mm, the thickness of the surface with wheat ear pattern texture is 0.6 mm, and the total thickness of the first-shot product is 3.1 mm; the thickness of the second-shot material is 2.5 mm, the thickness of the surface with wheat ear pattern texture is 0.6 mm, and the total thickness of the second-shot product is 3.1 mm; the chamfer diameter of the sharp corner at the serrated bottom of the wheat ear pattern texture is 0.1 mm.

[0059] The injection molding method adopted in this example includes the following steps: During the first-shot molding, the injection temperature of the PC material is 260 °C, the mold temperature of the mold is 100 °C, and the injection pressure for the first-shot molding is 70 MPa; the holding pressure is 25 MPa, and the holding time is 5 s; During the second-shot molding, the melt index of the ABS+PC material is 18 g / 10 min, and the injection pressure for the second-shot molding is 60 MPa.

[0060] Example 2 In this example, the product parameters are the same as those in Example 1. The difference in the injection molding method adopted from that in Example 1 is only that during the first-shot molding, the injection pressure for the first-shot molding is 65 MPa.

[0061] Example 3 In this example, the product parameters are the same as those in Example 1. The difference in the injection molding method adopted from that in Example 1 is only that during the first-shot molding, the injection pressure for the first-shot molding is 60 MPa.

[0062] Example 4 In this example, the product parameters are the same as those in Example 1. The difference in the injection molding method adopted from that in Example 1 is only that during the second-shot molding, the melt index of the ABS+PC material is 20 g / 10 min.

[0063] Example 5 In this example, the product parameters are the same as those in Example 1. The difference in the injection molding method adopted from that in Example 1 is only that during the second-shot molding, the injection pressure for the second-shot molding is 55 MPa.

[0064] For the products molded in Examples 1-5, "white streak" quality inspection was carried out, and no obvious white streaks were found in the products.

[0065] Comparative Example 1 In this embodiment, the product parameters are the same as those in Embodiment 1. The only difference in the injection molding method used is that during the first-shot molding, the injection temperature of the PC material is 240 °C.

[0066] Comparative Example 2 In this embodiment, the product parameters are the same as those in Embodiment 1. The only difference in the injection molding method used is that during the first-shot molding, the injection temperature of the PC material is 280 °C.

[0067] Comparative Example 3 In this embodiment, the product parameters are the same as those in Embodiment 1. The only difference in the injection molding method used is that during the first-shot molding, the mold temperature is 80 °C.

[0068] Comparative Example 4 In this embodiment, the product parameters are the same as those in Embodiment 1. The only difference in the injection molding method used is that during the first-shot molding, the mold temperature is 100 °C.

[0069] Comparative Example 5 In this embodiment, the product parameters are the same as those in Embodiment 1. The only difference in the injection molding method used is that during the first-shot molding, the injection pressure of the first-shot molding is 80 MPa.

[0070] Comparative Example 6 In this embodiment, the product parameters are the same as those in Embodiment 1. The only difference in the injection molding method used is that during the first-shot molding, the holding pressure is 15 MPa and the holding time is 5 s.

[0071] Comparative Example 7 In this embodiment, the product parameters are the same as those in Embodiment 1. The only difference in the injection molding method used is that during the first-shot molding, the holding pressure is 40 MPa and the holding time is 5 s.

[0072] Comparative Example 8 In this embodiment, the product parameters are the same as those in Embodiment 1. The only difference in the injection molding method used is that during the second-shot molding, the melt index of the ABS+PC material is 16 g / 10 min.

[0073] Comparative Example 9 In this embodiment, the product parameters are the same as those in Embodiment 1. The only difference in the injection molding method used is that during the second-shot molding, the injection pressure of the second-shot molding is 80 MPa.

[0074] The "white streak" quality of the products formed in Comparative Examples 1-9 was inspected, and different degrees of "white streaks" appeared in the products.

[0075] It can be seen by comparison that, aiming at the structural characteristics of the wheat ear pattern texture products in this application, adopting the injection molding method of this application can well solve the problem of "white stripes" on the surface of two-color products, and the yield rate of two-color products reaches more than 90%.

[0076] As mentioned above, it is only a preferred embodiment of the present invention and does not impose any formal restrictions on the present invention. Any simple modification or equivalent change made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for injection molding a two-color product capable of presenting a wheat ear texture, characterized in that: The following steps are involved: A one-shot product is formed by one-shot molding using a transparent PC material, and a wheat ear texture surface is formed on one side surface of the one-shot product, wherein the wheat ear texture surface is obtained by forming irregular strip grooves on one side surface of the one-shot product, and a cross section of the one-shot product along the transverse direction of the wheat ear texture is serrated on the side facing the wheat ear texture surface; A two-shot product is produced by two-shot molding using ABS+PC materials on one side of a one-shot product provided with a wheat ear texture surface, and a wheat ear texture surface matching the wheat ear texture on the one-shot product is formed on the two-shot product, so as to obtain a two-color product capable of presenting a wheat ear texture; During one-shot molding, the injection temperature of PC material is 260℃, the mold temperature is 100℃, the maximum injection pressure of one-shot molding is not more than 70MPa; the holding pressure is 25MPa, and the holding time is 5s; During two-shot molding, the melt index of ABS+PC material shall not be less than 18 g / 10min, and the maximum injection pressure of two-shot molding shall not be greater than 60MPa.

2. The method for injection molding a two-color product capable of presenting a wheat ear texture according to claim 1, characterized in that: The mold core used for forming the wheat ear texture surface on the mold is provided with a wheat ear texture molding surface that matches the wheat ear texture surface structure, and the chamfer diameter of the sharp corner of the serrated bottom of the wheat ear texture molding surface on the cross section along the transverse direction of the wheat ear texture is not greater than 0.1mm.

3. The method for injection molding a two-color product capable of presenting a wheat ear texture according to claim 1, characterized in that: The one-shot product and the two-shot product are respectively provided with matching flanges around them, and the one-shot product and the two-shot product are connected around them by matching flanges. The flange on the one-shot product is arranged toward the side where the wheat ear pattern texture surface is provided.

4. The method for injection molding a two-color product capable of presenting a wheat ear texture according to claim 3, characterized in that: A transition fillet is provided between the flange of the one-shot product and the body of the one-shot product, the thickness of the flange of the one-shot product is equal to the radius of the transition fillet and the inner side thereof is flush with the starting end of the transition fillet.

5. The method for injection molding a two-color product capable of presenting a wheat ear texture according to claim 1, characterized in that: The mold is provided with clamping blocks at the upper and lower ends of the one-shot product and at the gate side, respectively, for clamping the molded one-shot product.

6. The method for injection molding a two-color product capable of presenting a wheat ear texture according to claim 1, characterized in that: The total thickness of the one-shot and two-shot products is 3.1-3.4mm, of which the thickness of the wheat ear texture surface is 0.6-0.8mm.

7. The method for injection molding a two-color product capable of presenting a wheat ear texture according to claim 1, characterized in that: The method also includes the step of spraying UV paint on the surface of the first shot product of the two-color product obtained by molding. Before spraying the UV paint, a shielding layer is set on the surface of the bonding position between the first shot product and the second shot product to shield the bonding position between the first shot product and the second shot product.

8. The method for injection molding a two-color product capable of presenting a wheat ear texture according to claim 1, characterized in that: In the components of the UV paint, the ratio of paint: curing agent: diluent is 4:1:6-7 by weight.

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