Resin molded product

Abstract

To provide a resin molded product containing a bright material with an inconspicuous weld line without passing complicated steps.SOLUTION: A resin molded product is made by using a specific bright material. In more details, the resin molded product is made by using as the bright material, a glass flake having a cut surface having an average particle diameter of 90 μm or more, and an aspect ratio of 20 or less, or by using as the bright material, an aluminum flake having an average particle diameter of 175 μm-460 μm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a resin molded product. [Background technology]

[0002] In recent years, efforts to significantly reduce waste generation through waste prevention, reduction, recycling, and reuse have become more active. To achieve this, research and development into recycling is being conducted.

[0003] Conventionally, painting has been used as a means for improving the appearance quality of resin molded products. However, painting has the problem of environmental impact, such as the emission of volatile organic compounds, and increased costs due to increased labor. Furthermore, when painting resin molded products that are used as exterior parts of automobiles, for example, there is a risk that the paint film will peel off due to external stimuli such as a collision. Furthermore, from the viewpoint of recycling resins, an alternative technology to painting is desired.

[0004] Therefore, alternative technologies to painting have been studied, and one proposed method is to impart a lustrous appearance to a resin molded product by kneading a lustrous material into the resin and molding it.For example, Patent Document 1 proposes a lustrous resin molding material containing, as the lustrous material, scaly glass flakes having an aspect ratio of diameter to thickness of 10 or more and an average particle size of 20 μm or more.

[0005] In particular, plastic molded parts for automobiles are often made using injection molding. In this injection molding process, molten resin is made to flow within the mold, and so weld lines, which are linear patterns, can form where the molten resin flows together.

[0006] In particular, when molten resin containing a lustrous material is allowed to flow, the lustrous material flows in the surface direction of the molded product in normal areas, but flows in the thickness direction of the molded product in areas where resins meet. This results in a difference in lustrousness between the normal areas and the meeting areas, which can make weld lines very noticeable.

[0007] Therefore, Patent Document 2 proposes a method of controlling the orientation direction of anisotropic filler by using a mixture pellet in which anisotropic filler is dispersed while being uniaxially oriented, and placing the mixture pellet in a molding die and melting it. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 02-153966 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-040811 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the method described in Patent Document 2 requires a step of preparing a mixture pellet in advance in which the anisotropic filler is dispersed while being uniaxially oriented, and a step of placing the mixture pellet in a molding die, which increases the number of steps and makes the method more complicated.

[0010] The present invention has been made in view of the above-mentioned background art, and aims to provide a resin molding containing a lustrous material that has inconspicuous weld lines without undergoing complicated processes, thereby contributing to a significant reduction in waste generation. [Means for solving the problem]

[0011] The present inventors have conducted extensive research to achieve the above object and have discovered that by using a specific luster material to produce a resin molded product, it is possible to obtain a resin molded product with inconspicuous weld lines without the need for complex processes, thereby completing the present invention.

[0012] That is, the present invention includes the following aspects. [1] A resin molded product containing a glittering material, The glittering material is glass flakes having a cut surface, The glass flakes have an average particle size of 90 μm or more and an aspect ratio of 20 or less. [2] The density of the glass flakes in the resin molding is D (g / cm 3 ), and the average particle diameter of the glass flakes is P (μm), the following formula (1) is satisfied: D≦6E-05P-0.0045 Formula (1) [3] The density D of the glass flakes in the resin molding is 0.0001 (g / cm 3 ) or more. [2] A resin molded product. [4] A resin molded product containing a glittering material, The lustrous material is aluminum flakes having an average particle size of 175 μm to 460 μm. [5] The density D of the aluminum flakes in the resin molded product is 0.0001 (g / cm 3 )~0.012(g / cm 3 ) is a resin molded product [4]. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a resin molded product containing a lustrous material, which has inconspicuous weld lines, without undergoing complicated processes. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a graph showing the relationship between the average particle size P (μm) of glass flakes in a resin molding and the density D (g / cm 3 ). DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, a resin molded product according to an embodiment of the present invention will be described in detail, but the present embodiment is not limited to the following description.

[0016] First Embodiment The resin molded product of the first embodiment is a resin molded product containing a lustrous material, and the lustrous material is glass flakes having an average particle diameter of 74 μm or more and an aspect ratio of 20 or less. The glass flakes have cut surfaces created by cutting during production, and these cut surfaces have the property of exhibiting lustrous properties similar to other general surfaces. Furthermore, by using the specific aspect ratio as described above, the difference in lustrous properties between the cut surfaces and the general surfaces of the glass flakes can be reduced, and by using the specific average particle diameter as described above, the difference in lustrous properties between the confluence portion and other general portions (normal parts) in the resin molded product can be reduced.

[0017] <Resin> The resin used in the resin molded product of the first embodiment is not particularly limited. It can be appropriately selected taking into consideration the appearance quality, mechanical properties, cost, etc. required for the molded product. Examples of resins used in the resin molded product of this embodiment include PP (polypropylene), ABS (acrylonitrile butadiene styrene copolymer resin), PS (polystyrene), etc. The resin used in the resin molded product of the first embodiment may be a translucent resin. It may also be a mixture of multiple types of resin.

[0018] <Shining material> The lustrous material used in the resin molded product of the first embodiment is mixed into the resin and dispersed throughout the resin molded product, and imparts a glossy appearance, a metallic appearance, a deep appearance, etc. to the molded product through the effects of reflection, transmission, refraction, etc. The lustrous material may be colored.

[0019] (kinds) The lustrous material used in the resin molded product of the first embodiment is glass flake. Glass flake is easily available and easy to handle. In addition, glass flake has a cut surface generated by cutting during manufacturing, and this cut surface also has the property of exhibiting lustrous properties like other general surfaces.

[0020] (shape) The glass flakes used as the glittering material in the resin molded product of the first embodiment are shaped like scale particles (flakes) with a difference between the minor axis and the major axis.

[0021] (cut surface) The glass flakes used as the glittering material in the resin molded product of the first embodiment have glittering properties even on their cut surfaces (for example, in the case of scale-like particles, the surface in the thickness direction).

[0022] The glass flakes used as the luminous material in the resin molded product of the first embodiment have luminous properties even on the cut surface, so that luminous properties can be ensured even when the luminous material flows in the thickness direction of the molded product at the confluence of the molten resin during molding. As a result, the confluence of the molten resin is prevented from becoming dark, and the weld line of the molded product can be made less noticeable.

[0023] (Average particle size) The glass flakes used as the lustrous material in the resin molded product of the first embodiment have an average particle diameter of 90 μm or more. If the average particle diameter is 90 μm or more, the number of glass flake particles contained in the resin molded product can be reduced compared to when glass flakes with a smaller average particle diameter are blended at the same content and density, thereby reducing the amount of particles oriented in the thickness direction of the molded product at the junction of the molten resin. As a result, the difference in lustrousness between the normal area and the junction is reduced, making the weld line of the molded product less noticeable.

[0024] The average particle size of the glass flakes as the lustrous material used in the resin molded product of the first embodiment may be 100 μm or more, 120 μm or more, 140 μm or more, 160 μm or more, or 180 μm or more. The upper limit of the average particle size of the glass flakes is 5000 μm or less from the viewpoint of enabling injection molding.

[0025] The above-mentioned average particle size of the glass flakes refers to the "average major axis" of the scaly glass flake particles. This average particle size can be calculated by cutting the molded product and observing the cut surface with an electron microscope. Specifically, in the observation field, the area corresponding to the glass flakes and the other areas are binarized using image processing software. Next, 20 glittering materials are randomly selected, and the longest diameter of each is measured. The average of these measurements is taken as the average major axis of the glass flakes.

[0026] (aspect ratio) The aspect ratio of the glass flakes used as the lustrous material in the resin molded product of the first embodiment is 20 or less. When the aspect ratio is 20 or less, the difference in lustrousness between the cut surface of the glass flakes (the surface in the thickness direction of the scaly particles) and other parts is small. Therefore, even if the glass flakes flow in the thickness direction of the molded product at the confluence of the molten resin during molding, the difference in lustrousness between the normal part of the molded product and the confluence part is small, making it possible to make the weld line of the molded product less noticeable.

[0027] The aspect ratio of the glass flakes used as the lustrous material in the resin molded product of the first embodiment may be 18 or less, 16 or less, 14 or less, 12 or less, 10 or less, 8 or less, 6 or less, 4 or less, or 2 or less.

[0028] The aspect ratio here refers to the ratio of the particle's major axis diameter to its minor axis diameter. Generally, the larger the aspect ratio of the lustrous pigment used in resin moldings, the more lustrous the resulting molding will be, and the smaller the aspect ratio, the less noticeable the alignment disorder will be.

[0029] (density) The density of the glass flakes as the luminous material used in the resin molded product of the first embodiment in the resin molded product is the density D (g / cm 3 ) and the average particle size P (μm) of the glass flakes preferably satisfy the following mathematical formula (1): D≦6E-05P-0.0045 Formula (1)

[0030] Here, in this embodiment, an experiment was conducted using glass flakes with different average particle sizes. Specifically, resin molded products with different contents, i.e., different densities, were produced for glass flakes with different average particle sizes, and it was confirmed whether the produced resin molded products had brilliance and inconspicuous weld lines. Then, based on the results of resin molded products that had brilliance and inconspicuous weld lines (specifically, Examples 2 and 7 described below, which are the densities at the boundary where the evaluation results differ for average particle sizes of 90 μm and 200 μm, respectively), the average particle size of the glass flakes and its density were plotted to create an approximate equation, and the graph shown in FIG. 1, which shows the relationship of the above-mentioned mathematical formula (1), was obtained.

[0031] The density D (g / cm 3 ) of the resin molded product of the glass flakes used as the luminous material in the resin molded product of the first embodiment 3 ) does not satisfy the above formula (1), the number of glass flake particles contained in the resin molded product is large, so the brilliance of the normal part of the molded product increases, and the difference in brilliance between the normal part and the joining part widens, resulting in noticeable weld lines. On the other hand, the density D (g / cm 3 ) of the resin molded product of the glass flakes used as the brilliance material in the resin molded product of the first embodiment 3) satisfies the above formula (1), the difference in brilliance between the normal part and the joining part of the molded product can be reduced, and as a result, the visibility of the weld line can be suppressed.

[0032] In the resin molded product of the first embodiment, the content of the glass flakes as the lustrous material is preferably 0.01 wt% or more relative to 100 wt% of the resin molded product. In terms of the density of the glass flakes in the resin molded product, it is 0.0001 (g / cm 3 ) or more is preferable.

[0033] When the content of glass flakes as a luminous material in the resin molded product of the first embodiment is less than 0.01 wt% relative to 100 wt% of the resin molded product, the density of the glass flakes in the resin molded product is 0.0001 (g / cm 3 ), it becomes difficult to control the uneven distribution of the glass flakes inside the resin (substrate).

[0034] The glass flake content is 0.1 wt% or more, and the density of the glass flakes in the resin molded product is 0.001 (g / cm 3 The upper limit of the density of the glass flakes in the resin molded product can be calculated from the upper limit of the average particle diameter of the glass flakes, 5000 μm, and the above-mentioned formula (1), and specifically, is 0.296 (g / cm 3 )

[0035] <Other ingredients> The resin molded product of the first embodiment may contain, as necessary, a component forming the base material of the molded product, such as an elastomer, a luster material other than glass flakes, a pigment, and various other additives, etc. Examples of additives include ultraviolet absorbers, antioxidants, antifoaming agents, anti-settling agents, dispersants, and surface conditioners.

[0036] Second Embodiment The resin molded product of the second embodiment is a resin molded product containing a luster material, and aluminum flakes with a particle size of 175 μm to 460 μm are used as the luster material.

[0037] <Resin> The resin used in the resin molded product of the second embodiment is not particularly limited, and may be the same as the resin used in the resin molded product of the first embodiment described above.

[0038] <Shining material> The lustrous material used in the resin molded product of the second embodiment is aluminum flakes (scale-like aluminum particles) having an average particle diameter of 175 μm to 460 μm. Because the resin molded product of the second embodiment uses aluminum particles as the lustrous material, it is a resin molded product with a deep metallic look.

[0039] (shape) The lustrous material used in the resin molded product of the second embodiment is aluminum flakes, and therefore the lustrous material has a shape of scaly particles (flakes) with a difference between the short diameter and the long diameter.

[0040] (Average particle size) The aluminum flakes used as the lustrous material in the resin molded product of the second embodiment have an average particle diameter of 175 μm to 460 μm. When the average particle diameter is 175 μm to 460 μm, the number of aluminum flake particles contained in the resin molded product can be reduced compared to when aluminum flakes with a smaller average particle diameter are blended at the same content (wt%), thereby reducing the amount of particles oriented in the thickness direction of the molded product at the junction of the molten resin. As a result, the difference in lustrousness between the normal area and the junction is reduced, making the weld line of the molded product less noticeable.

[0041] The average particle diameter of the aluminum flakes used as the lustrous material in the resin molded product of the second embodiment may be 200 μm or more, 250 μm or more, 300 μm or more, 350 μm or more, or 400 μm or more.

[0042] The average particle size of the aluminum flakes mentioned above means the "average major axis" of the scaly aluminum flake particles, and the particle size of the aluminum flakes contained in the resin molded product can be confirmed by the same measurement method as that for the resin molded product of the first embodiment described above.

[0043] (aspect ratio) The aspect ratio of the aluminum flakes used as the lustrous material in the resin molded product of the second embodiment is not particularly limited. The aspect ratio of the aluminum flakes may be, for example, 2 or more and 1000 or less.

[0044] (density) The aluminum flakes used as the luminous material in the resin molded product of the second embodiment have a density D (g / cm 3 ) is 0.0001(g / cm 3 )~0.012(g / cm 3 The density D (g / cm 3 ) of the aluminum flakes in the resin molded product is preferably 3 ) is within the above range, the difference in brilliance between the normal part and the joining part of the molded product can be reduced, and as a result, the visibility of the weld line can be suppressed.

[0045] In the resin molded product of the second embodiment, the content of aluminum flakes used as the lustrous material is preferably 0.01 wt % or more relative to 100 wt % of the resin molded product.

[0046] <Other ingredients> The resin molded product of the second embodiment may contain, as necessary, a component forming the base material of the molded product, such as an elastomer, a luster material other than aluminum flakes, a pigment, and various other additives, etc. Examples of additives include ultraviolet absorbers, antioxidants, antifoaming agents, anti-settling agents, dispersants, and surface conditioners. [Example]

[0047] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples as long as they do not depart from the gist of the present invention.

[0048] <Material> The materials used in the examples and comparative examples are shown below.

[0049] (resin) Methacrylic resin (manufactured by Mitsubishi Chemical Corporation, product name "ACRY PET IRK304 001" (registered trademark))

[0050] (shining material) Glass flakes (Nippon Sheet Glass Co., Ltd., product name "Metashine" (registered trademark)) Aluminum flakes (manufactured by Fukuda Metal Foil and Powder Co., Ltd., product name "Astroflake" (registered trademark))

[0051] <Examples 1-1 to 1-12 and Comparative Examples 1-1 to 1-2> The above-mentioned glass flakes have a cut surface, and among these glass flakes, glass flakes with different aspect ratios, average particle diameters, and thicknesses were used, and the content of glass flakes relative to the resin was adjusted so that the density of the glass flakes in the resin molded product would be as shown in Table 1, and resin molded products were produced by injection molding (temperature 260°C, mold temperature 60°C).

[0052] (evaluation) Each of the obtained resin molded products was visually inspected for brilliance and inconspicuous weld lines. The evaluation criteria were ranked from best to worst, with brilliance and inconspicuous weld lines being A, B, C, and D, with A to C being considered pass and D being fail. The results are shown in Table 1 below.

[0053] [Table 1]

[0054] First, Comparative Examples 1-1 and 1-2, which used glass flakes with an average particle size of less than 90 μm, were evaluated as D, failing the evaluation, regardless of the content or density. These resin molded products did not have any brilliance to begin with. Furthermore, Examples 1-1 to 1-12 all received evaluations of A to C, passing the evaluation. Among them, it was found that Examples 1-1, 1-2, and 1-7 to 1-11, which satisfy the above-mentioned mathematical formula (1), all received an evaluation of A.

[0055] These results confirmed that resin molded products with brilliance and inconspicuous weld lines can be obtained by using glass flakes with an average particle size of 90 μm or more and an aspect ratio of 20 or less. Furthermore, it was confirmed that resin molded products that satisfy formula (1) in particular can be obtained with excellent brilliance and inconspicuous weld lines.

[0056] <Examples 2-1 to 2-7 and Comparative Example 2-1> Among the above-mentioned aluminum flakes, those with different average particle diameters and thicknesses were used, and the content of aluminum flakes relative to the resin was adjusted so that the density of the aluminum flakes in the resin molded product would be as shown in Table 2, and resin molded products were produced by injection molding (temperature 260°C, mold temperature 60°C).

[0057] (evaluation) Each of the obtained resin molded products was visually inspected for brilliance and inconspicuous weld lines. The evaluation criteria were rated A, B, and C, with the best evaluation result being brilliance and inconspicuous weld lines, and the best evaluation results being A and B, respectively. The results are shown in Table 2 below.

[0058] [Table 2]

[0059] First, Comparative Example 2-1, which used aluminum flakes with an average particle size of less than 175 μm, was evaluated as C and failed. In addition, Examples 2-1 to 2-7 all received evaluation results of A to B and passed. Among them, the aluminum flakes in the resin molded product with a density of 0.0001 (g / cm 3 )~0.012(g / cm 3 ) were all evaluated as A.

[0060] These results confirmed that by using aluminum flakes with an average particle size of 175 μm to 460 μm, it is possible to obtain resin molded products that have a lustrous finish and inconspicuous weld lines. In particular, when the density of the aluminum flakes in the resin molded product is 0.0001 (g / cm 3 )~0.012(g / cm 3 It has been confirmed that if the thickness is within the range of 1 / 2 mm, a resin molded product having excellent brightness and no noticeable weld lines can be obtained.

Claims

1. A resin molded product containing a glittering material, The glittering material is glass flakes having a cut surface, The glass flakes have an average particle size of 90 μm or more and an aspect ratio of 20 or less.

2. The density of the glass flakes in the resin molding is D (g / cm ３ 2. The resin molded article according to claim 1, wherein the following formula (1) is satisfied when the average particle diameter of the glass flakes is P (μm): D≦6E−05P−0.0045 ... Formula (1)

3. The density D of the glass flakes in the resin molded product is 0.0001 (g / cm ３ 3. The resin molded product according to claim 2, wherein the resin molded product is at least 100% by weight.

4. A resin molded product containing a glittering material, The lustrous material is aluminum flakes having an average particle size of 175 μm to 460 μm.

5. The density D of the aluminum flakes in the resin molded product is 0.0001 (g / cm ３ ) ~ 0.012 (g / cm ３ 5. The resin molded product according to claim 4, wherein

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