Molded product, automotive component comprising the same, and method for producing molded product

Abstract

To provide a molded product that retains high strength and rigidity and exhibits excellent impact resistance, an automotive component comprising the molded product, and a method for producing the molded product.SOLUTION: A molded product comprises a thermoplastic resin, glass fibers, and an alkali metal carbonate, and has a foamed layer satisfying the following conditions (1) to (3). (1) The average cell diameter is 120 μm or less. (2) The number of cells per unit area is 30 cells / mm2 or more. (3) The maximum cell diameter is 220 μm or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a molded article, an automotive component, and a method for manufacturing a molded article. [Background technology]

[0002] In recent years, metal components have been increasingly replaced by resin components in interior and exterior parts in order to reduce the weight of automobiles. In particular, molded products containing air bubbles (cells) obtained by foaming resin are lighter than metals, and are expected to further improve the fuel efficiency of automobiles.

[0003] Known molded articles used as automobile parts include, for example, those obtained by the method described in Patent Document 1. In this method, a molten resin is injected into a cavity formed in a pair of molding dies, and the resin is foamed to produce a molded article. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2005-238726 A Summary of the Invention [Problem to be solved by the invention]

[0005] When molded articles made by foaming resin are used as automobile parts, the weight of the vehicle body can be reduced. However, depending on the application location of the molded article (e.g., the back door of the automobile), it is desirable to add glass fibers to maintain high strength and rigidity while also further improving impact resistance. In view of the above circumstances, an object of the present disclosure is to provide a molded article that retains high strength and rigidity and has excellent impact resistance, an automobile part that includes this molded article, and a method for manufacturing this molded article. [Means for solving the problem]

[0006] Specific means for solving the above problems include the following aspects. <1> A molded article comprising a thermoplastic resin, glass fibers, and an alkali metal carbonate, and having a foamed layer that satisfies the following (1) to (3): (1) The average cell diameter is 120 μm or less. (2) The number of cells per unit area is 30 / mm 2 That's all. (3) The maximum cell diameter is 220 μm or less. <2> The content of the thermoplastic resin is 50% by mass to 90% by mass of the entire molded body. <1> The molded article according to claim 1. <3> The content of the glass fiber is 10% by mass to 50% by mass of the entire molded body. <1> or <2> The molded article according to claim 1. <4> The content of the alkali metal carbonate is 0.2% by mass or less of the entire foamed molded body. <1> ~ <3> The molded article according to any one of claims 1 to 7. <5> <1> ~ <4> 13. An automobile component comprising the molded article according to claim 12. <6> Supplying a composition including a thermoplastic resin, glass fibers, and an alkali metal bicarbonate into a molding device having a movable portion; and moving a movable portion of the molding apparatus to increase an internal volume of the molding apparatus. <1> ~ <4> 13. A method for producing the molded article according to claim 12. <7> The alkali metal bicarbonate comprises sodium bicarbonate. <6> A method for producing the molded article according to claim 1. <8> The particle size distribution of the alkali metal bicarbonate is within the range of 0.5 μm to 15 μm. <6> A method for producing the molded article according to claim 1. <9> The content of the alkali metal hydrogen carbonate in the composition is 0.3 mass% or less of the total composition. <6> A method for producing the molded article according to claim 1. Effect of the Invention

[0007] According to the present disclosure, there are provided a molded article that retains high strength and rigidity and has excellent impact resistance, an automobile component that includes this molded article, and a method for producing this molded article. [Brief description of the drawings]

[0008] [Figure 1] 1 is an optical microscope image of a cross section of a molded body produced in Example 1. [Diagram 2] 1 is an optical microscope image of a cross section of a molded body produced in Comparative Example 1. [Diagram 3] 1 is an optical microscope image of a cross section of a molded body produced in Comparative Example 2. [Figure 4] 1 is an optical microscope image of a cross section of a molded body produced in Comparative Example 3. [Diagram 5] FIG. 2 is a schematic cross-sectional view of an example of the configuration of a molding apparatus used for producing a molded body. [Figure 6] FIG. 2 is a schematic cross-sectional view of an example of the configuration of an injection device used in the production of a molded body. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiment for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiment. In the following embodiment, the components (including element steps, etc.) are not essential unless specifically stated. The same applies to the numerical values ​​and their ranges, and they do not limit the present invention.

[0010] In the present disclosure, the term "step" includes not only a step that is independent of other steps, but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved.

[0011] In the present disclosure, a numerical range indicated using "~" includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In the present disclosure, in which numerical ranges are described in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, the upper or lower limit of the numerical range described in the present disclosure may be replaced with a value shown in the examples. In the present disclosure, when a composition contains multiple substances corresponding to each component, the content of each component in the composition means the total content of the multiple substances present in the composition, unless otherwise specified. In this disclosure, the term "layer" includes cases where the layer is formed over the entire area when the area in which the layer exists is observed, as well as cases where the layer is formed over only a portion of the area. When an embodiment of the present disclosure is described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. The size of the members in each drawing is conceptual, and the relative relationship between the sizes of the members is not limited thereto.

[0012] <Molded body> The molded article of the present disclosure has a foamed layer that contains a thermoplastic resin, glass fibers, and an alkali metal carbonate and satisfies the following (1) to (3). (1) The average cell diameter is 120 μm or less. (2) The number of cells per unit area is 30 / mm 2 That's all. (3) The maximum cell diameter is 220 μm or less.

[0013] In the present disclosure, the term "foam layer" refers to a portion in which cells are contained in the resin, and the term "skin layer" refers to a portion in which no cells are contained in the resin. In the present disclosure, a portion of a molded article in which skin layer A, foam layer, and skin layer B are arranged in this order in the thickness direction may be referred to as a "foam portion." The ratio of the thickness of the foam layer to the total thickness of skin layer A, foam layer, and skin layer B may be referred to as a "foam layer ratio." Skin layer A and skin layer B may each be referred to as a "skin layer."

[0014] The molded article of the present disclosure has a smaller average cell diameter in the foam layer and a larger number of cells per unit area than conventional foamed molded articles made of the same material. As shown in the examples described below, the molded article of the present disclosure retains high strength and rigidity and exhibits excellent impact resistance. This ensures the strength required for a molded article.

[0015] Examples of optical microscope images of the cross section of the foamed part of a molded article are shown in Figs. 1 to 5. The cross sections shown in Figs. 1 to 5 were obtained by cutting the foamed part of the molded article along the thickness direction. In Figs. 1 to 5, the areas shown as relatively bright regions correspond to cells, and the areas with relatively low brightness correspond to resin. Within the foamed part, the region where cells exist corresponds to the foam layer, and the regions on both sides of the foam layer where no cells are observed correspond to the skin layer.

[0016] From the viewpoint of weight reduction, the foam layer ratio in the foamed portion of the molded article is preferably 60% or more, and more preferably 65% ​​or more. From the viewpoint of ensuring sufficient strength, the foamed layer ratio in the foamed portion of the molded article is preferably 80% or less, more preferably 75% or less, and may be 70% or less.

[0017] When the thickness of the foamed portion of the molded body is not constant, the ratio of the thickness of the foamed layer to the total thickness of the skin layer and the foamed layer measured at the portion where the foamed layer has the greatest thickness is defined as the "foamed layer ratio" of the molded body.

[0018] In the present disclosure, the thickness of the skin layer and the foam layer is measured by observing a cross-sectional image of the foamed part of the molded article. The type of cross-sectional image is not particularly limited, and an optical microscope image, an X-ray CT scan image, an electron microscope photograph, etc. can be used. The observation area is set so that an area of ​​at least 1.5 mm x 1.5 mm is secured. Specifically, in a cross-sectional image of a foamed portion of a molded article, the thickness of an area where no cells are observed is measured as the thickness of the skin layer, and the thickness of an area where cells are observed is measured as the thickness of the foamed layer. In the above measurement, the boundary between the skin layer and the foam layer is determined as follows. In the cross-sectional image of the foamed region, a straight line perpendicular to the thickness direction of the foamed region is drawn and moved from the outermost part of the foamed region toward the center. The movement of this straight line is stopped at the position where it first comes into contact with the arc of the cell, and the line at the point where it stops is regarded as the boundary between the skin layer and the foamed layer.

[0019] The average diameter of the cells contained in the foam layer is 120 μm or less. When the average diameter of the cells is 120 μm or less, a molded article tends to have a sufficiently high strength. From the viewpoint of increasing the strength of the molded body, the average cell diameter is preferably 110 μm or less, more preferably 105 μm or less, and even more preferably 100 μm or less. The lower limit of the average cell diameter is not particularly limited, and may be, for example, 50 μm or more.

[0020] The maximum diameter of the cells contained in the foam layer is 220 μm or less. When the maximum diameter of the cells is 220 μm or less, there is a tendency for the variation in strength from one part to another of the molded article to be suppressed. The lower limit of the maximum cell diameter is not particularly limited, and may be, for example, 150 μm or more.

[0021] The upper limit of the minimum diameter of the cells contained in the foam layer is not particularly limited, and may be, for example, 50 μm or less. The lower limit of the minimum diameter of the cells contained in the foam layer is not particularly limited, and may be, for example, 10 μm or more.

[0022] In the present disclosure, the average diameter, maximum diameter, and minimum diameter of the cells are measured by observing a cross-sectional image of the foamed part of the molded body obtained in the same manner as the cross-sectional image for measuring the thickness of the skin layer and the foamed layer. Specifically, the maximum width of the cell observed in the cross-section of the foamed part of the molded body is taken as the cell diameter of that cell, and any 30 or more cells within the observation range (however, selected evenly in the thickness direction of the molded article) are measured. The arithmetic mean value of the cell diameters of the measured objects is taken as the "average cell diameter", the maximum value of the cell diameters of the measured objects is taken as the "maximum cell diameter", and the minimum value of the cell diameters of the measured objects is taken as the "minimum cell diameter".

[0023] The number of cells per unit area of ​​the foam layer is 30 / mm 2 More than 35 pieces / mm 2 More preferably, 40 pieces / mm 2It is more preferable that the number of cells per unit cross-sectional area of ​​the foam layer is 30 cells / mm 2 If the foam layer is provided in the above range, the effect of reducing the weight of the molded article can be sufficiently obtained, and sufficient strength can be ensured.

[0024] Although there is no particular upper limit on the number of cells per unit area of ​​the foam layer, from the viewpoint of ensuring the strength of the molded product, it is preferable that the upper limit be 100 cells / mm 2 It may be less than 90 pieces / mm 2 It may be less than 80 pieces / mm 2 It may be the following.

[0025] In the present disclosure, the number of cells per unit area of ​​the foam layer is measured by observing a cross-sectional image of the foamed part of a molded article obtained in the same manner as the cross-sectional image for measuring the thickness of the skin layer and the foam layer. More specifically, the number of cells in an arbitrary range (including the range from one end of the foam layer to the opposite end in the thickness direction of the molded article) observed in the cross section of the foam layer is calculated by multiplying the number of cells by the area (mm 2 ) to obtain the number of cells per unit area of ​​the foam layer.

[0026] The thickness of the foam layer in the foamed portion is not particularly limited. For example, the thickness of the foam layer may be within the range of 1.8 mm to 2.4 mm. When the thickness of the foam layer is within the above range, there is a tendency for weight reduction to be achieved while ensuring sufficient strength when a general foam molding method is carried out. When the foam layer of the molded article does not have a constant thickness, the thickness measured at the site where the foam layer has the maximum thickness is defined as the "thickness of the foam layer."

[0027] The thickness of the skin layer in the foamed portion is not particularly limited. For example, the thickness of the skin layer may be within the range of 0.3 mm to 0.6 mm. When the thickness of the skin layer is within the above range, there is a tendency for weight reduction to be achieved while ensuring sufficient strength when a general foam molding method is carried out. The thickness of the skin layer is the thickness of each of the skin layer A and the skin layer B disposed on both sides of the foam layer. When the thickness of the skin layer varies depending on the location on the molded article, the thickness measured at the location where the foam layer has the greatest thickness is defined as the "skin layer thickness."

[0028] The thickness of the foamed portion of the molded article (ie, the total thickness of the foamed layer and the skin layers disposed on both sides thereof) is not particularly limited and can be set depending on the application of the molded article, etc. From the viewpoint of a balance between ensuring rigidity and reducing weight, the thickness of the foamed portion of the molded article is preferably 3.6 mm or less, more preferably 3.0 mm or less, and even more preferably 2.8 mm or less. From the viewpoint of flow resistance when filling a mold with molten resin, the thickness of the foamed portion of the molded article is preferably 1.0 mm or more, more preferably 1.5 mm or more, and even more preferably 2.0 mm or more.

[0029] When a molded article has a foamed portion and a portion that does not correspond to the foamed portion (for example, a portion that does not include a foamed layer such as a bent portion of the molded article), the proportion of the foamed portion in the entire molded article is not particularly limited and can be set according to the application of the molded article, etc. For example, the proportion of the foamed portion in the entire molded article may be 50% to 100%, 70% to 100%, or 80% to 100% on an area basis when the molded article is viewed in plan.

[0030] The type of resin contained in the molded product is not particularly limited. From the viewpoints of ease of molding and balance between toughness and strength, the resin contained in the molded product is preferably a thermoplastic resin, and more preferably a polyolefin resin.

[0031] Specific examples of the resin include at least one selected from the group consisting of polyolefin resins such as polyethylene resins, polypropylene resins, and composite polypropylene resins, polystyrene resins, polyethylene terephthalate resins, polyvinyl alcohol resins, vinyl chloride resins, ionomer resins, polyamide resins, acrylonitrile-butadiene-styrene copolymer resins (ABS), and polycarbonate resins. Among these, at least one selected from the group consisting of polypropylene resins, composite polypropylene resins, and acrylonitrile-butadiene-styrene copolymer resins (ABS) is preferred.

[0032] The resin content in the molded article is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, of the entire molded article. The resin content in the molded article may be 90% by mass or less of the entire molded article.

[0033] The molded article contains glass fibers. The glass fibers function as a reinforcing material for the molded article. The type of glass fiber is not particularly limited and can be selected from known materials. In order to obtain a balance between weight reduction and strength, the glass fiber content is preferably 50% by mass or less of the entire molded article, more preferably 40% by mass or less, and even more preferably 30% by mass or less. The content of the glass fibers may be 10% by mass or more of the entire molded article.

[0034] The compact comprises an alkali metal carbonate. Specific examples of the alkali metal carbonate include sodium carbonate and potassium carbonate. The alkali metal carbonate contained in the molded body may be a substance produced by decomposition of an alkali metal hydrogen carbonate used as a foaming agent during the production of the molded body.

[0035] The content of the alkali metal carbonate may be 0.2% by mass or less of the entire molded body. The content of the alkali metal carbonate may be 0.01% by mass or more of the entire molded body.

[0036] The molded article may contain components other than the thermoplastic resin, the glass fiber, and the alkali metal carbonate, as necessary.

[0037] The use of the molded article of the present disclosure is not particularly limited. The molded article of the present disclosure is lightweight and has excellent strength, so it is suitable for use in applications where both weight reduction and strength are important, such as interior and exterior components of automobiles. Specific examples of interior and exterior components of automobiles include back doors, side doors, sacco moldings, arch moldings, side moldings, rocker moldings, bumpers, and back door trims.

[0038] <Automotive parts> The automotive component of the present disclosure includes the above-described molded article. The type of automotive part is not particularly limited, and can be selected from automotive interior and exterior parts such as back doors, side doors, sacco moldings, arch moldings, side garnishes, side moldings, rocker moldings, bumpers, back door trims, and side door trims.

[0039] <Method of manufacturing molded body> The method for producing a molded body according to the present disclosure is a method for producing the above-mentioned molded body, Supplying a composition including a thermoplastic resin, glass fibers, and an alkali metal bicarbonate into a molding device having a movable portion; and moving a movable portion of the molding apparatus to increase an interior volume of the molding apparatus.

[0040] In the above method, the movable part of the molding device to which the composition is supplied is moved to increase the volume inside the molding device. At that time, cells are generated by the action of the alkali metal bicarbonate contained as a foaming agent in the composition. As a result, a molded article including a foamed portion having a foamed layer containing cells and skin layers disposed on both sides of the foamed layer can be produced.

[0041] In the above method, the method for controlling the foam layer ratio and other conditions in the produced molded article within the above-mentioned range is not particularly limited. For example, the method includes a method of adjusting the type and amount of each material contained in the composition, molding conditions (temperature of the composition and molding device, molding time, etc.), etc.

[0042] The details and preferred embodiments of the thermoplastic resin and the glass fiber contained in the composition are the same as the details and preferred embodiments of the thermoplastic resin and the glass fiber contained in the molded article described above. The composition may contain components other than the thermoplastic resin, the glass fiber, and the alkali metal bicarbonate, as necessary.

[0043] Specific examples of the alkali metal bicarbonate contained in the composition include sodium bicarbonate (baking soda) and potassium bicarbonate.

[0044] The decomposition temperature of the alkali metal hydrogen carbonate is preferably 50°C to 200°C, and more preferably 80°C to 200°C. The decomposition temperature of the alkali metal hydrogen carbonate may be 130°C to 200°C.

[0045] From the viewpoint of foaming properties, the content of the alkali metal hydrogen carbonate in the composition is preferably 0.3 mass % or less, and more preferably 0.2 mass %. The above content of hydrogen carbonate is the content in the composition before it is fed to the molding device.

[0046] From the viewpoint of controlling the size of the cells contained in the foamed layer, the average particle size of the alkali metal hydrogen carbonate is preferably 3.0 μm or less, more preferably 2.5 μm or less, and may be 0.5 μm or more or 1.0 μm or more.

[0047] The above-mentioned alkali metal hydrogen carbonate is preferably used as a foaming agent in the form of a master batch with a thermoplastic resin such as low-density polyethylene, mainly from the viewpoint of molding stability.

[0048] The average particle size of the alkali metal hydrogen carbonate is the arithmetic mean value of particle sizes measured for 100 or more particles arbitrarily selected from an image obtained by an optical microscope, an electron microscope or the like.

[0049] From the viewpoint of controlling the size of the cells contained in the foamed layer, the particle size distribution of the alkali metal hydrogen carbonate is preferably within the range of 0.5 μm to 15 μm.

[0050] The particle size distribution of the alkali metal bicarbonate is a range that includes the particle sizes of all particles observed in an image obtained by an optical microscope, an electron microscope, etc. In other words, it is a range from the particle size of the smallest particle to the particle size of the largest particle observed in the image.

[0051] In the above method, the temperature of the composition when it is supplied to the molding device is not particularly limited. For example, it is preferably a temperature equal to or higher than the softening point of the thermoplastic resin contained in the composition.

[0052] The molding apparatus used in the method of the present disclosure is not particularly limited as long as at least a part of the apparatus is movable. From the viewpoint of workability, it is preferable to use a pair of molds, at least one of which is movable.

[0053] An example of a molding apparatus is shown in Fig. 5. The molding apparatus shown in Fig. 5 includes a movable mold 1, a fixed mold 2, a cavity 6 which is a gap between the movable mold 1 and the fixed mold 2, and a gate 4 which penetrates the fixed mold 2 from the outside of the mold to the cavity 6. Hereinafter, the movable mold 1 and the fixed mold 2 may be collectively referred to as the "mold".

[0054] 5(A), a composition 3 containing a thermoplastic resin is supplied from an injection device (not shown) through a gate 4 into a cavity 6. At this time, the composition 3 is supplied into the cavity 6 in a state in which the thermoplastic resin is melted or softened and has fluidity.

[0055] The mold is usually at a temperature lower than that of the supplied composition 3. Therefore, when the composition 3 is filled into the cavity 6 as shown in Fig. 5(B), the solidification of the composition 3 starts from the portion in contact with the mold.

[0056] 5(C), the movable mold 1 is moved to expand the distance between the molds (core back), and the unsolidified portion of the composition 3 is foamed to form a foamed layer 5. A skin layer 7 is formed between the foamed layer 5 and the mold by the solidified composition 3.

[0057] The material of the molding device is not particularly limited, and a commonly used material can be used, for example, stainless steel, prehardened steel, alloy tool steel, high-speed tool steel, and cemented carbide tool steel.

[0058] There is no particular limitation on the method for supplying the composition to the molding apparatus shown in Fig. 5. For example, as shown in Fig. 6, an injection apparatus that continuously prepares the composition and supplies it to the molding apparatus may be used.

[0059] 6 includes a cylinder 11 and a hopper 12 for introducing raw materials of a composition into the inside of the cylinder 11. The outlet of the cylinder 11 is connected to a mold 13 of a molding device.

[0060] The cylinder 11 is equipped with a screw 11A that stirs the raw materials to prepare a composition and moves the composition toward the mold 13 of the molding device, a motor 11B that drives the screw 11A, and a heater (not shown) that heats the inside of the cylinder 11. The raw materials supplied to the inside of the cylinder 11 become molten while moving toward the mold 13. EXAMPLES

[0061] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the following examples, details of the materials used in preparing the compositions are as follows: Resin: Polypropylene Glass fiber reinforced resin: Polypropylene containing glass fiber (50% by mass) Additive: Black pigment masterbatch

[0062] <Comparative Example 1> Resin (40 parts by mass), glass fiber reinforced resin (60 parts by mass), foaming agent (2 parts by mass) containing sodium bicarbonate (9.2% by mass) with an average particle size of 4.0 μm and a particle size distribution of 0.9 μm to 42.3 μm, and additives (3 parts by mass) were charged into a hopper of an injection device configured as shown in FIG. 6, and the resin was melted and mixed in a cylinder to prepare a composition. This composition was supplied into the cavity of a pair of molds, one of which was movable. After supplying the composition to the cavity, the movable mold (core) was moved to foam the composition, and the composition was cooled to produce a molded body.

[0063] <Comparative Example 2> A foaming agent (2 parts by mass) containing resin (40 parts by mass), glass fiber reinforced resin (60 parts by mass), sodium bicarbonate (15% by mass) with an average particle size of 34.2 μm and a particle size distribution of 2.2 μm to 176.9 μm, and additives (3 parts by mass) were charged into a hopper of an injection device configured as shown in FIG. 6, and the resin was melted and mixed in the cylinder to prepare a composition. This composition was supplied into the cavity of a pair of molds, one of which was movable. After the composition was supplied to the cavity, the movable mold (core) was moved to foam the composition, and the composition was cooled to produce a molded body.

[0064] <Comparative Example 3> Resin (40 parts by mass), glass fiber reinforced resin (60 parts by mass), a foaming agent containing azodicarbonamide (ADCA) (1 part by mass), and additives (3 parts by mass) were charged into a hopper of an injection device configured as shown in FIG. 6, and the resin was melted and mixed in the cylinder to prepare a composition. This composition was supplied into the cavity of a pair of molds, one of which was movable. After supplying the composition to the cavity, the movable mold (core) was moved to foam the composition, and the composition was cooled to produce a molded body.

[0065] <Example 1> A composition containing resin (40 parts by mass), glass fiber reinforced resin (60 parts by mass), a foaming agent (1.8 parts by mass) containing sodium bicarbonate (6.2% by mass) having an average particle size of 2.4 μm and a particle size distribution of 0.8 μm to 9.7 μm, and an additive (3 parts by mass) was prepared in the same manner as in Comparative Example 1, and a molded body was produced.

[0066] <Cross-section observation of molded body> An optical microscope image of a cross section obtained by cutting the molded body produced in Example 1 in the thickness direction is shown in Fig. 1. Optical microscope images of cross sections obtained by cutting the molded bodies produced in Comparative Examples 1 to 3 in the thickness direction are shown in Figs. 2 to 4. In the cross section of the molded article produced in the Examples and Comparative Examples, the skin layer A (cavity side), the foam layer, and the skin layer B (core side) were arranged in this order. From the obtained optical microscope images, the thicknesses of the skin layer A, the foam layer and the skin layer B were measured, and the foam layer ratio was calculated. The results are shown in Table 1. Table 1 shows the minimum diameter, maximum diameter, average diameter and number per unit cross-sectional area of ​​the cells contained in the foam layer.

[0067] <Evaluation of physical properties of molded products> The Izod impact value of the molded article was measured by the following method. The results are shown in Table 1. The thickness of the test piece used for the measurement (thickness of the molded article) was about 3 mm. The test specimen for the Izod impact test was prepared by cutting the center of a 235mm x 365mm molded product to a size of 85mm x 10mm. The test method was in accordance with JIS K 7110 and was performed without notching the test specimen.

[0068] The tensile breaking stress of the molded article was measured by the following method, and the results are shown in Table 1. The thickness of the test piece used in the measurement (thickness of the molded article) was about 3 mm. The test specimen for the tensile test was prepared by cutting the center of a molded product with dimensions of 235mm x 365mm to the following dimensions: total length 170mm or more, parallel length 70mm, parallel width 10mm, chuck length 30mm or more, and chuck width 20mm. The test method was in accordance with JIS K 7161. The nominal stress at the time of test specimen breakage was taken as the tensile breaking stress.

[0069] The flexural modulus of the molded article was measured by the following method, and the results are shown in Table 1. The thickness of the test piece used in the measurement (thickness of the molded article) was about 3 mm. The test piece for the bending test was prepared by cutting the center of a molded product with dimensions of 235 mm x 365 mm to dimensions of 85 mm x 10 mm. The test method was performed in accordance with JIS K 7171. From the stress-strain curve obtained by the test, the dynamic modulus of elasticity was taken as the bending modulus of elasticity.

[0070] [Table 1]

[0071] As shown in Table 1, (1) the average cell diameter is 120 μm or less, and (2) the number of cells per unit area is 30 / mm 2 The molded articles of the examples having a foamed layer with a maximum cell diameter of 220 μm or less (3) have a higher Izod impact value and are more excellent in impact resistance than the molded articles of the comparative examples having a foamed layer that does not satisfy at least one of (1) to (3). Furthermore, the molded articles of the examples have a higher tensile breaking stress and flexural modulus, and retain high strength and rigidity. [Explanation of symbols]

[0072] Reference Signs List 1...movable mold, 2...fixed mold, 3...composition, 4...gate, 5...foam layer, 6...cavity, 7...skin layer, 10...injection device, 11...cylinder, 11A...screw, 11B...motor, 12...hopper, 13...mold

Claims

1. A molded article comprising a thermoplastic resin, glass fibers, and an alkali metal carbonate, and having a foamed layer that satisfies the following (1) to (3): (1) The average cell diameter is 120 μm or less. (2) The number of cells per unit area is 30 / mm ２ That's all. (3) The maximum cell diameter is 220 μm or less.

2. The molded article according to claim 1, wherein the content of the thermoplastic resin is 50% by mass to 90% by mass of the entire molded article.

3. The molded body according to claim 1, wherein the content of the glass fiber is 10% by mass to 50% by mass of the entire molded body.

4. The molded article according to claim 1 , wherein the content of the alkali metal carbonate is 0.2 mass % or less of the entire foamed molded article.

5. An automobile member comprising the molded article according to any one of claims 1 to 4.

6. Supplying a composition including a thermoplastic resin, glass fibers, and an alkali metal bicarbonate into a molding device having a movable portion; The method for manufacturing a molded body according to any one of claims 1 to 4, further comprising a step of increasing an internal volume of the molding apparatus by moving a movable part of the molding apparatus.

7. The method for producing a molded body according to claim 6 , wherein the alkali metal hydrogen carbonate comprises sodium hydrogen carbonate.

8. The method for producing a molded body according to claim 6, wherein the particle size distribution of the alkali metal hydrogen carbonate is within a range of 0.5 μm to 15 μm.

9. The method for producing a molded article according to claim 6, wherein the content of the alkali metal hydrogen carbonate is 0.3 mass% or less of the total composition.

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