JP6770257B2 - Manufacturing method of resin molded products, mirrors and molded products - Google Patents

Description

The present invention relates to a resin molded product, a mirror, and a method for manufacturing a molded product, which are thin and have a relatively large transfer area, such as a plate-shaped body.

In order to form an injection-molded product using resin with high precision, generally, the molding die is filled with resin at high pressure, and the pressure causes a transfer surface provided in the inner surface region of the molding die. Transfer is performed to form a molded surface in which the above is inverted. However, in a molded product such as an optical mirror that is thin and has a relatively large area, when molding at such a high pressure is performed, distortion may occur due to internal stress or deformation may occur at the time of mold release. This makes it difficult to meet the required transfer accuracy. In order to solve such a problem, there is a method of inducing sink marks in places where precision is not required as a molded product and transferring them at low pressure with high precision in places where precision is required (Patent Document 1). See ~ 4).

In the method of Patent Document 1, in an injection-molded article of an optical mirror, sink marks are induced with the back surface as a rough surface with respect to the mirror surface on the front surface. However, in this method, since the balance of the mold release resistance is changed depending on the surface roughness, the sink mark cannot be formed on the back surface side as desired depending on the molding conditions such as holding pressure, which is a problem in that it is not stable.

In the methods of Patent Documents 2 and 3, in a molded product having a surface requiring transfer and a surface not requiring transfer, the mold constituting the unnecessary surface is slid during molding (specifically, during cooling) to form a resin. A space is created between the mold and the mold to create a sink mark, or an air pipe is provided in the mold and pressurized air is injected to create a space to generate a sink mark. However, since these methods require a sliding mechanism, an air injection mechanism, and the like, the mold itself becomes large-scale, and there is a problem in that it becomes difficult to apply due to restrictions on the mold shape and the like.

In the method of Patent Document 4, by overlaying (specifically, forming a convex shape) on a surface that does not require transfer, the shrinkage of the resin is increased and sink marks are likely to occur in that portion. However, in this method, it is necessary to increase the shrinkage of the resin. Therefore, when the back side of a plate-like surface that requires high-precision transfer becomes an unnecessary surface, such as a mirror, there is also a surface that requires transfer. The problem is that the products that can be used are limited depending on the shape, such as easy sinking.

Japanese Patent No. 2774472 Japanese Patent No. 4817977 Japanese Patent No. 5652027 Japanese Unexamined Patent Publication No. 2006-264192

An object of the present invention is to provide a resin molded article, a mirror, and a method for producing a molded article, which are thin, have a relatively large transfer area, and have high transfer accuracy.

In order to achieve at least one of the above-mentioned objects, the molded product reflecting one aspect of the present invention has an essential molded surface having a shape corresponding to the transfer portion of the mold, and the essential molded surface has a surface shape. It is provided with different optional molded surfaces, and the optional molded surface is located at a position corresponding to the sink mark inducing portion of the mold in order to promote air accumulation without hindering the transfer by the transfer portion, and has an unfinished transfer portion with sink marks. However, the unfinished transfer portion is provided at a position along the development of the resin flow . Here, the essential molded surface means a surface that requires high-precision transferability, such as the surface of an optical mirror. Further, the optional molded surface means a surface that does not require high-precision transferability, such as the back surface of an optical mirror.

In order to achieve at least one of the above-mentioned objects, a mirror reflecting one aspect of the present invention includes the above-mentioned molded product and a light reflecting layer provided on an essential forming surface of the molded product.

In order to achieve at least one of the above-mentioned objects, a method for producing a molded product reflecting one aspect of the present invention is provided at an essential transfer surface having a transfer portion and a position along the development of the resin flow, and is transferred. The molten resin is injected into a mold having a sink mark-inducing transfer surface having a sink mark-inducing portion that promotes air accumulation without hindering transfer by the portion, an air pool is generated in the sink mark-inducing portion, and sink marks are generated on the sink mark-inducing transfer surface side. Is formed, and a shape corresponding to the transfer portion is formed on the essential transfer surface side.

FIG. 1A is a plan view of the molded product of the first embodiment on the arbitrary molding surface side, and FIG. 1B is a cross-sectional view taken along the line AA of FIG. 1A. FIG. 2A is an enlarged cross-sectional view of a mold for manufacturing a molded product such as FIG. 1A, and FIG. 2B is a partial cross-sectional view illustrating the overall structure of the mold. 3A to 3D are enlarged cross-sectional views for explaining a modified example of the molded product of FIG. 1A, and FIGS. 3E to 3H are enlarged cross-sectional views of a mold for manufacturing the molded product of FIGS. 3A to 3D, respectively. .. It is a figure explaining the flow of the molten resin in the molding space of the mold of FIG. 2A. 5A to 5D are diagrams illustrating a method for manufacturing a molded product. 6A and 6B are diagrams for explaining the relationship between the transfer surface shape of the mold and the occurrence of sink marks. 7A to 7C are diagrams for explaining the relationship between the groove shape of the mold and the occurrence of sink marks. 8A is a plan view of the sink mark induction transfer surface side of the mold for manufacturing the molded product of the second embodiment, FIG. 8B is a sectional view taken along the line BB of FIG. 8A, and FIG. 8C is a sectional view taken along the line BB. It is a figure explaining the modification of the mold of FIG. 8B. 9A is a plan view of the sink mark induction transfer surface side of the mold for manufacturing the molded product of the third embodiment, and FIG. 9B is a sectional view taken along the line CC of FIG. 9A. FIG. 10A is a plan view of the sink mark-inducing transfer surface side of the mold for manufacturing the molded product of the fourth embodiment, and FIG. 10B is a diagram illustrating a modified example of the mold of FIG. 10A. FIG. 11A is a plan view of the sink mark-induced transfer surface side of the molded product of the fifth embodiment, and FIG. 11B is a side view of the molded product of FIG. 11A. It is a figure explaining the detection apparatus which incorporated the molded article such as FIG. 11A. It is a figure explaining the modification of the mold for manufacturing the molded article of FIG. 1A and the like. 14A and 14B are diagrams illustrating another modification of the mold for manufacturing the molded product of FIG. 1A and the like.

[First Embodiment]
Hereinafter, a molded product and a method for producing the molded product according to the first embodiment of the present invention will be described with reference to the drawings.

1A and 1B show an example of a molded product manufactured by the method for manufacturing a molded product of the present embodiment. The molded product 100 is a flat plate-shaped molded product and has a quadrangular outer shape. The molded product 100 has a first surface 100a on the front side and a second surface 100b on the back side. The first surface 100a is an essential molding surface 11 having a shape corresponding to the transfer portion 71b of the mold 70 described later, and has a mirror surface. The surface roughness Ra of the first surface 100a is 0.01 μm or less. The second surface 100b is an arbitrary molding surface 12 having a shape corresponding to the sink mark induction portion 72b of the mold 70, and forms a transfer unfinished portion 12a having a convex shape. That is, the optional molded surface 12 faces the essential molded surface 11 with the main body of the molded product 100 sandwiched between them, and has a different surface shape from the essential molded surface 11. A sink mark (not shown) is generated on the optional molded surface 12 due to the formation of the unfinished transfer portion 12a. Here, the essential molding surface 11 means a surface that requires high-precision transferability, such as the surface of an optical mirror. Further, the optional molding surface 12 means a surface that does not require high-precision transferability, such as the back surface of an optical mirror.

The molded product 100 is molded by injection molding. Immediately after molding, the molded product 100 is accompanied by a non-product part FP indicated by a broken line in addition to the product part LP. The non-product part FP has a gate part 83, a runner part 82, and the like corresponding to the resin inflow path. Here, the gate portion 83 is a portion corresponding to a gate GA (see FIG. 2A) for flowing the resin into the molding space 70a described later for molding the molded product 100. By cutting the boundary between the runner portion 82 and the product portion LP, that is, the gate portion 83, the molded product 100 as the product portion LP is obtained. Even if the gate portion 83 is cut after molding the molded product 100, a gate mark remains. The molded product 100 is made of a thermoplastic resin. Examples of the product obtained from the molded product 100 include mirror parts of precision equipment such as projectors and measuring machines, and exterior parts of precision equipment such as cameras and copiers. When the product obtained from the molded product 100 is a mirror, the light reflecting layer MR is provided on the essential forming surface 11 of the molded product 100, which is the main body, by vapor deposition or the like. As the mirror shape, for example, in addition to a flat plate-shaped mirror, there is a curved mirror such as a curved surface.

Hereinafter, the second surface 100b side of the molded product 100 will be described in detail. On the optional molding surface 12, the unfinished transfer portion 12a is provided at a position along the development of the resin flow. Here, the development of the resin flow means the locus of the resin tip at the time of molding. In the example of FIG. 1A, the resin flow is generated from the gate portion 83 toward the opposite side of the gate portion 83. The resin tip at the time of molding draws a curve, and the curvature becomes smaller toward the opposite side of the gate portion 83. Although the details will be described later, the shape of the unfinished transfer portion 12a corresponds to the shape of the sink mark inducing portion 72b of the mold 70 (see FIG. 2A).

The unfinished transfer portion 12a has a plurality of convex portions 12b. These convex portions 12b (or grooves 72c of the sink mark inducing portion 72b described later) are provided at predetermined intervals. By leaving a certain amount of flat surface portion (end surface SS) on the arbitrary forming surface 12 (or the sink mark-inducing transfer surface 72a described later), sink marks are likely to occur. Such a flat surface portion is a surface that gives the basic contour shape of the arbitrary forming surface 12, and is also called an end surface SS. The cross section of the convex portion 12b in the transverse direction is, for example, triangular or V-shaped. The cross-sectional shape of the convex portion 12b may be, for example, a funnel shape, a quadrangular shape, a trapezoidal shape, a U shape, or the like, in addition to the V shape (see FIGS. 3A to 3D). In this case, the transfer unfinished portion 12a The sink mark-inducing portion 72b of the mold 70 corresponding to the above has a shape obtained by reversing the shape of the unfinished transfer portion 12a as shown in FIGS. 3E to 3H, respectively. It is preferable that the aspect ratio is 0.5 or more and the root width H1 is 0.2 mm or more and 2 mm or less. The aspect ratio of the convex portion 12b is more preferably 1 or more. The root width H1 of 12b is more preferably 0.2 mm or more and 1 mm or less. Further, when the wall surface of the convex portion 12b has a taper, the molded product 100 is easily released from the mold.

FIG. 2A is a diagram illustrating a mold 70 (or a mold apparatus) for molding the molded product 100. The mold 70 includes a first mold 71 and a second mold 72. The transfer surface of the mold 70 is an inverted molding surface of the molded product 100. The first mold 71 and the second mold 72 are molded by the mold matching surface PL, and a molding space 70a is formed between the molds 71 and 72. The first mold 71 is formed with an essential transfer surface 71a for transferring the shape of the molded product 100 on the first surface 100a side so as to face the molding space 70a. The essential transfer surface 71a corresponds to the shape of the essential molded surface 11 of the molded product 100, and has a mirror surface as the transfer portion 71b. The second mold 72 is formed with a sink mark-inducing transfer surface 72a for transferring the shape of the molded product 100 on the second surface 100b side. The sink mark-induced transfer surface 72a corresponds to the shape of the arbitrary molding surface 12 of the molded product 100. A sink mark-inducing portion 72b is provided on the sink mark-inducing transfer surface 72a. The sink mark inducing portion 72b is a portion that promotes air accumulation without interfering with the transfer by the transfer portion 71b during molding. As shown in FIG. 4, the sink mark inducing portion 72b is provided at a position along the development of the resin flow. As a result, the resin tip tends to reach the sink mark inducing portion at substantially the same time. In the example of FIG. 4, the spread of the resin in a stepwise predetermined time zone is shown by a dot pattern. The sink mark inducing portion 72b has a plurality of grooves 72c. The cross section of the groove 72c in the transverse direction is, for example, triangular or V-shaped. As a result, the resin skips in the groove 72c, and air tends to remain on the sink mark-induced transfer surface 72a. The groove 72c has an aspect ratio of 0.5 or more and an inlet width H2 of 0.2 mm or more and 2 mm or less. The aspect ratio of the groove 72c is more preferably 1 or more. Further, the inlet width H2 of the groove 72c is more preferably 0.2 mm or more and 1 mm or less. A gate GA communicating with the molding space 70a is formed in the mold 70. In this case, the gate GA is arranged not in the center of the transfer surfaces 71a and 72a but on the side, and injection molding is performed by the side gate method.

FIG. 2B is a cross-sectional view illustrating the overall structure of the mold 70. A runner RA is connected to the molding space 70a of the mold 70 via a gate GA. The runner RA is connected to the sprue SP on the resin supply side. As a result, the molten resin J from the sprue SP obtained by melting the thermoplastic resin fills the runner RA and fills the molding space 70a via the gate GA.

Hereinafter, a method for manufacturing a molded product using the mold 70 will be described with reference to FIGS. 5A to 5D. First, both molds 71 and 72 are heated to a temperature suitable for molding by a mold temperature controller (not shown).

Next, as shown in FIG. 5A, the first mold 71 and the second mold 72 are mold-matched. For example, the first mold 71 is a movable mold, and the second mold is a fixed mold. After the molds are aligned, the first mold 71 and the second mold 72 are tightened with a required pressure.

Next, as shown in FIG. 5B, injection is performed by injecting the molten resin J into the molding space 70a at a required pressure by an injection device (not shown). As shown in FIG. 4, the molten resin J flows so that its tip is along the sink mark inducing portion 72b formed in the mold 70. When the tip of the molten resin J reaches the edge of the groove 72c of the sink mark inducing portion 72b, the resin skips in the groove 72c, air discharge failure occurs when passing through the groove 72c, and an air pool AT is formed. As a result, transfer failure occurs in the sink mark-inducing portion 72b, and sink marks are induced in the sink mark-induced transfer surface 72a. As a result, an unfinished transfer portion 12a with a sink mark is formed at a position corresponding to the sink mark-inducing portion 72b on the optional molding surface 12 side of the molded product 100. On the other hand, on the essential transfer surface 71a side, since sink marks are preferentially formed on the sink mark-induced transfer surface 72a which is the surface facing the essential transfer surface 71a, sink marks do not occur and the transfer portion 71b of the essential transfer surface 71a is the molded product 100. It is properly transferred to the essential molding surface 11. As a result, a shape corresponding to the transfer portion 71b, that is, a mirror surface is formed on the essential molded surface 11 side of the molded product 100. After the molding space 70a is filled with the resin, the mold 70 maintains the resin pressure in the molding space 70a and gently cools the molten resin by heat dissipation. As described above, the semi-molded product MP including the sprue portion 81 corresponding to the sprue SP, the runner portion 82 corresponding to the runner RA, the gate portion 83 corresponding to the gate GA, and the product part LP corresponding to the molding space 70a It is formed.

Next, as shown in FIG. 5C, the mold opening is performed so that the first mold 71 on the movable side is retracted. As a result, the first mold 71 and the second mold 72 are separated from each other. As a result, the semi-molded product MP is released from the second mold 72 while being held by the first mold 71.

Next, as shown in FIG. 5D, the semi-molded product MP is projected by an ejector pin or the like (not shown). As a result, the semi-molded product MP is extruded toward the second mold 72 and released from the first mold 71.

Next, a take-out device (not shown) is operated to completely separate the semi-molded product MP from the first mold 71, and the semi-molded product MP is taken out from between the first and second molds 71 and 72 to the outside. Carry out. After that, the gate portion 83 is subjected to a gate cut process, and the molded product 100 is obtained by the product portion LP at the tip of the gate portion 83.

According to the molded article and the method for producing the molded article described above, the sink mark-inducing portion 72b of the mold 70 generates an air pool AT to induce the sink mark, and the sink mark is formed on the sink mark-inducing transfer surface 72a side. That is, along with the formation of the unfinished transfer portion 12a, the unfinished transfer portion 12a with a sink mark is formed on the arbitrary molding surface 12 side. Further, by having the sink mark inducing portion 72b, sink marks are induced without using a large-scale mold mechanism such as sliding a part of the mold or providing an air pipe. As a result, the surface accuracy of the essential molding surface 11 on the side opposite to the arbitrary molding surface 12 becomes good, and the molded product 100 having high accuracy transferability even at a low pressure can be obtained.

表１からわかるように、表面が符号「○」であり、裏面が符号「×」である組み合わせが存在せず、面粗さＲａを大きくすることによる効果は見られなかった。Hereinafter, the relationship between the mold and the occurrence of sink marks on the molded product will be described.
A) Relationship between the surface roughness Ra of the mold Table 1 describes the relationship between the surface roughness Ra of the transfer surface of the mold and the occurrence of sink marks. When molding a flat plate-shaped molded product having a side of 40 mm and a thickness of 2.5 mm, the molding pressure is changed and the surface of the transfer surface of one mold (corresponding to the second mold 72 of the present embodiment). The roughness Ra was changed to 0.01 μm, 0.1 μm, and 1 μm. The surface roughness Ra of the transfer surface of the other mold (corresponding to the first mold 71 of the present embodiment) is 0.01 μm, and in this case, the transfer surface is a mirror surface. In Table 1, the code "○" indicates that the surface is mirror and no sink marks have occurred, and the code "x" indicates that sink marks have occurred. The presence or absence of sink marks was visually determined. Further, the surface formed by the one transfer surface of the molded product is the back surface, and the surface formed by the other transfer surface is the front surface. A molded product having high-precision transferability when the front surface has a reference numeral “◯” and the back surface has a reference numeral “x” corresponds to the molded product 100 of the present embodiment. The evaluation of the table is the same for the following tables.
[Table 1]

As can be seen from Table 1, there was no combination in which the front surface had the symbol “◯” and the back surface had the symbol “×”, and the effect of increasing the surface roughness Ra was not observed.

表２からわかるように、表面が符号「○」であり、裏面が符号「×」である組み合わせが存在せず、熱伝導差による効果は見られなかった。B) Relationship with the thermal conductivity of the mold Table 2 explains the relationship between the thermal conductivity of the mold and the occurrence of sink marks. When molding a flat plate-shaped molded product having a side of 40 mm and a thickness of 2.5 mm, the molding pressure is changed and the thermal conductivity of one mold (corresponding to the second mold 72 of the present embodiment) is changed. It was changed to 20 W / m · K (steel material), 9 W / m · K (Ni plating), and 1 W / m · K (insulation ceramic layer). The thermal conductivity of the transfer surface of the other mold (corresponding to the first mold 71 of the present embodiment) was set to 20 W / m · K (steel material).
[Table 2]

As can be seen from Table 2, there was no combination in which the front surface was coded “◯” and the back surface was coded “×”, and no effect due to the difference in heat conduction was observed.

表３からわかるように、表面が符号「○」であり、裏面が符号「×」である組み合わせは、成形時の圧力が２０ＭＰａ又は４０ＭＰａであって、ヒケさせたくない側の他方の金型９１の転写面９１ｃ（表面）の形状が凸であり、一方の金型９２の転写面９２ｃ（裏面）の形状が凹の場合であった。しかしながら、樹脂を金型に食いつかせるように成形すると、その金型で転写される面にはヒケが発生しないものの、成形品の離型がしにくくなるおそれがある。C) Relationship with the transfer surface shape of the mold Table 3 explains the relationship between the transfer surface shape of the mold and the occurrence of sink marks. When molding a flat plate-shaped molded product having a side of 40 mm and a thickness of 2.5 mm, the molding pressure is changed, and one mold (corresponding to the second mold 72 of the present embodiment) and the other mold are formed. The overall shape of the transfer surface (corresponding to the first mold 71 of the present embodiment) was reversed with concave and convex. Specifically, "convex / concave" in Table 3 is the transfer surface shape of the mold 90 shown in FIG. 6A, and is the transfer surface shape of the other mold 91 which is the side (front side) where sink marks are not desired. The shape of the transfer surface of one of the molds 92 was made concave. Further, "concave / convex" is the transfer surface shape of the mold 90 shown in FIG. 6B, and the transfer surface shape of the other mold 91, which is the side (front side) where sink marks are not desired, is concave, and one of the molds is described. The transfer surface shape of the mold 92 is convex. By dividing the mold 90 into the core molds 91a and 92a and the outer peripheral molds 91b and 92b that support the core molds 91a and 92a, the unevenness of the transfer surfaces 91c and 92c on the front and back sides of the mold 90 is formed. ..
[Table 3]

As can be seen from Table 3, in the combination in which the front surface is coded “○” and the back surface is coded “×”, the molding pressure is 20 MPa or 40 MPa, and the other mold 91 on the side that does not want to sink. The shape of the transfer surface 91c (front surface) of the mold 92 was convex, and the shape of the transfer surface 92c (back surface) of one mold 92 was concave. However, when the resin is molded so as to be eaten by the mold, sink marks do not occur on the surface transferred by the mold, but there is a possibility that it becomes difficult to release the molded product.

表４からわかるように、表面が符号「○」であり、裏面が符号「×」である組み合わせは、溝７２ｃの配置が樹脂流動の展開に沿っている場合に多く現れた。つまり、溝７２ｃ（ヒケ誘発部）の配置は、樹脂の流れに沿った形が好ましいことがわかる。また、溝形状が深く細かい方がより好ましいことがわかる。D) Relationship between the arrangement and shape of the groove of the mold Table 4 describes the relationship between the groove shape of the mold and the occurrence of sink marks. When molding a flat plate-shaped molded product having a side of 40 mm and a thickness of 2.5 mm, the molding pressure is changed and one of the molds 92 and 72 (corresponding to the second mold 72 of the present embodiment) is transferred. The groove shapes provided on the surfaces 92c and 72a were changed. Specifically, when there is no groove (see FIG. 7A), when the arrangement of the grooves 92d is linear (straight line perpendicular to the resin flow direction of the gate GA) (see FIG. 7B), the arrangement of the grooves 72c is arranged. This is the case when the resin flow is in line with the development (see FIG. 7C). In Table 4, the second and third columns from the left have a V-shaped groove shape shown in FIG. 2A, and the fourth column from the left has a funnel shape shown in FIG. 3E. The groove shapes of 90 ° and 0.6 mm (or 0.9 mm) are the angles θ of the cross-sectional shapes of the grooves 92d and 72c and the depth D from the end faces of the transfer surfaces 92c and 72a, respectively. Further, in the case where the groove shape is funnel-shaped, the diameter H3 at the innermost portion of the groove 72c is 0.2 mm. The inlet width H2 of the grooves 92d and 72c is 1.1 mm in any groove shape.
[Table 4]

As can be seen from Table 4, the combination in which the front surface is the symbol “◯” and the back surface is the symbol “×” appears frequently when the arrangement of the grooves 72c is along the development of the resin flow. That is, it can be seen that the arrangement of the groove 72c (sink-inducing portion) is preferably a shape along the flow of the resin. Further, it can be seen that a deeper and finer groove shape is more preferable.

[Second Embodiment]
Hereinafter, a second embodiment of the molded product and the method for producing the molded product according to the present invention will be described. The molded product or the like of the second embodiment is a modification of the molded product or the like of the first embodiment, and the matters not particularly described are the same as those of the molded product or the like of the first embodiment. In FIG. 8A, for convenience of explanation, the groove 72c of the sink mark inducing portion 72b is shown by a thick line (the same applies to the subsequent embodiments).

FIG. 8A is a mold plan view of the sink mark-induced transfer surface 72a, and FIG. 8B is a cross-sectional view taken along the line BB in FIG. 8A. As shown in FIGS. 8A and 8B, the sink mark inducing portion 72b is a position along the development of the resin flow, and is provided discretely or intermittently with respect to the development direction. As a result, it is possible to alleviate the inhibition of air residue when there is a discrepancy between the sink mark inducing portion 72b and the actual resin flow, and it is possible to reduce the influence of sink mark induction. Although the specific illustration is omitted, the molded product 100 of the second embodiment is an inverted mold 70 shown in FIG. 8A and the like, and has a rectangular plate-shaped overall contour as in the case of the first embodiment. The unfinished transfer portion 12a (the portion corresponding to the unfinished transfer portion 12a shown in FIG. 1A) having an incomplete inversion is provided intermittently with respect to the development direction of the resin flow.

As shown in FIG. 8C, the groove 72c may have a plurality of steps 72d in the development direction of the resin flow.

[Third Embodiment]
Hereinafter, a third embodiment of the molded product and the method for producing the molded product according to the present invention will be described. The molded product or the like of the third embodiment is a modification of the molded product or the like of the first embodiment, and the matters not particularly described are the same as those of the molded product or the like of the first embodiment.

9A is a mold plan view of the sink mark induction transfer surface 72a, and FIG. 9B is a sectional view taken along the line CC in FIG. 9A. As shown in FIGS. 9A and 9B, the sink mark inducing portion 72b is provided as a plurality of point-like portions of a two-dimensional array. As a result, it is not necessary to predict the resin flow in advance with respect to the arrangement of the sink mark inducing portion 72b. In the examples of FIGS. 9A and 9B, the groove 72c has a conical shape. Although the specific illustration is omitted, the molded product 100 of the third embodiment is an inverted mold 70 shown in FIG. 9A and the like, and has a rectangular plate-shaped overall contour as in the case of the first embodiment. The unfinished transfer portion 12a (the portion corresponding to the unfinished transfer portion 12a shown in FIG. 1A) having an incomplete inversion is provided as a plurality of point-like portions of a two-dimensional array.

[Fourth Embodiment]
Hereinafter, a fourth embodiment of the molded product and the method for producing the molded product according to the present invention will be described. The molded product or the like of the fourth embodiment is a modification of the molded product or the like of the first embodiment, and the matters not particularly described are the same as those of the molded product or the like of the first embodiment.

As shown in FIG. 10A, the sink mark-inducing portion 72b is partially provided with a narrower occupied region on the sink mark-inducing transfer surface 72a than the sink mark-inducing portion 72b shown in FIG. 2A. The sink mark-inducing portion 72b may occupy 5% or more of the sink mark-induced transfer surface 72a in a plan view. Here, the occupied region of the sink mark inducing portion 72b is an inner region (region AR surrounded by a dotted line in the figure) connecting the outer edges of the entire portion constituting the sink mark inducing portion 72b. In this case, sink marks can be induced even if the sink mark-inducing portion 72b is partially provided on the sink mark-inducing transfer surface 72a. Even if the occupied area of the sink mark inducing portion 72b is less than 10%, a certain effect can be seen. Although the specific illustration is omitted, the molded product 100 of the fourth embodiment is an inverted mold 70 shown in FIG. 10A or the like, and has a rectangular plate-shaped overall contour as in the case of the first embodiment. On the arbitrary molding surface 12, the unfinished transfer portion 12a (the portion corresponding to the unfinished transfer portion 12a shown in FIG. 1A) with incomplete inversion is partial, but the occurrence of sink marks can be confirmed.

The sink mark inducing portion 72b may be arranged at a position corresponding to a place where sinking is likely to occur on the essential molding surface 11 side so that the unfinished transfer portion 12a is formed at the four corners of the molded product 100 as shown in FIG. 10B. It may be arranged at the four corners of the sink mark-induced transfer surface 72a.

[Fifth Embodiment]
Hereinafter, a fifth embodiment of the molded product and the method for producing the molded product according to the present invention will be described. The molded product or the like of the fifth embodiment is a modification of the molded product or the like of the first embodiment, and the matters not particularly described are the same as those of the molded product or the like of the first embodiment.

In the first embodiment, a mirror product has been mentioned as an example of a product obtained from the molded product 100, and specific examples thereof include a polygon mirror and other mirrors. When the product obtained from the molded product 100 is a mirror, the light reflecting layer MR (see FIG. 11B) is provided on the essential forming surface 11 of the molded product 100 which is the main body.

The polygon mirror 53 shown in FIGS. 11A and 11B is obtained from the molded product 100, and has a polyhedral shape including a plurality of mirror surfaces 41a and 42a as essential molding surfaces 11 arranged around the rotation axis AX. There is. More specifically, the polygon mirror 53 is a double-reflection type mirror and has a first reflection unit 41 and a second reflection unit 42. The polygon mirror 53 has a shape in which a conical first reflecting portion 41 extending downward and a conical second reflecting portion 42 extending upward are connected, and the first and second reflecting portions 41, 42 is individually molded or collectively formed. The gate portion 83 is provided near the center inside each of the reflecting portions 41 and 42, and the first and second reflecting portions 41 and 42 are formed by a pin gate method. The polygon mirror 53 has an essential molding surface 11 (mirror surface) on the outside of the first and second reflecting portions 41 and 42, that is, on the side surface side. Specifically, the polygon mirror 53 has a plurality of (specifically four) mirror surfaces 41a and 42a in the first and second reflecting portions 41 and 42, respectively. The insides of the first and second reflecting portions 41 and 42 are arbitrary molded surfaces 12, and an unfinished transfer portion 12a with sink marks is formed. A light reflecting layer MR is provided on each of the mirror surfaces 41a and 42a.

FIG. 12 shows a detection device 50 incorporating the polygon mirror 53 shown in FIG. 11A and the like. The detection device 50 includes a light emitting unit 51, a light receiving unit 52, and a polygon mirror 53. In the example of FIG. 12, the detection device 50 is a double reflection type laser radar. The light projecting unit 51 projects the laser beam T1 onto the polygon mirror 53. The light receiving unit 52 receives the reflected light T2 from the detection target DO reflected from the polygon mirror 53. The polygon mirror 53 rotates about the rotation axis AX and scans the laser light T1 and the reflected light T2. The polygon mirror 53 reflects the laser light T1 projected from the light receiving unit 52 on one of the first reflecting units 41 facing the mirror surface 41a, and guides the laser light T1 to the facing mirror surface 42a of the second reflecting unit 42. The mirror surface 42a reflects the incident laser light T1 and guides it to the detection target DO side. The reflected light T2 reflected by the detection target DO follows a path opposite to that of the laser light T1 and is detected by the light receiving unit 52. That is, the polygon mirror 53 reflects the reflected light T2 reflected by the detection target DO on one of the second reflecting portions 42 facing the mirror surface 42a, and on the one facing mirror surface 41a of the first reflecting portion 41. Guide. The mirror surface 41a reflects the incident reflected light T2 and guides it to the light receiving portion 52 side.

Although the molded product, the mirror, and the method for manufacturing the molded product have been described above according to the embodiment, the present invention is not limited to the above, and various modifications are possible. For example, in the above embodiment, the molded product 100 is molded by the side gate method, but as shown by the polygon mirror 53, it may be molded by the pin gate method. In this case, the gate GA is provided near the center of the sink mark-induced transfer surface 72a. The sink mark inducing portion 72b is arranged in an annular shape around the gate GA, for example, as shown in FIG. 13, in consideration of the resin flow. Further, the sink mark inducing portion 72b may be provided as a plurality of point-like portions of the two-dimensional arrangement as in the third embodiment (see FIG. 9A and the like).

Further, in the above embodiment, a line-symmetrical cross-sectional shape is illustrated with respect to the sink mark inducing portion 72b and the transfer incomplete portion 12a, but the shape of the sink mark inducing portion 72b or the like is appropriately changed as long as it can promote air accumulation. can do. For example, as shown in FIG. 14A, the sink mark inducing portion 72b on the mold 70 side may have one or more or a convex wall portion 72e on the resin flow upstream side of each groove 72c. Here, the upstream side of the resin flow is the gate GA side for the resin to flow into the molding space 70a. In this case, since the wall portion 72e is located in front of the resin tip of the groove 72c during molding, the resin is temporarily dammed by the wall portion 72e, and the resin skip is more likely to occur at the sink mark inducing portion 72b. As a result, poor air discharge or residual air is more likely to occur at the sink mark inducing portion 72b. In this case, the molded product 100 is obtained by reversing the mold 70 shown in FIG. 14A, and the unfinished transfer portion 12a in which the reversal is incomplete is recessed in one or more or each of the convex portions 12b on the gate portion 83 side. Has 12d.

Further, as shown in FIG. 14B, in the sink mark inducing portion 72b on the mold 70 side, the standing wall angle α1 on the resin flow upstream side of the groove 72c is relatively larger than the standing wall angle α2 on the opposite side of the resin flow upstream side. It may be a small angle. From a different point of view, the standing wall angle α1 on the upstream side of the resin flow can be an obtuse angle or an acute angle close to 90 °, and the standing wall angle α2 on the downstream side of the resin flow is an obtuse angle sufficiently larger than 90 °. There is. Here, the standing wall angles α1 and α2 are the angles of the wall surface of the groove 72c with respect to the end surface SS of the sink mark induction transfer surface 72a. In this case, the molded product 100 is obtained by reversing the mold 70 shown in FIG. 14B, and in the unfinished transfer portion 12a in which the reversal is incomplete, the standing wall angle of the convex portion 12b on the gate portion 83 side is the gate portion 83. The angle is relatively small compared to the standing wall angle on the opposite side, or an obtuse or acute angle close to 90 °.

Further, in the above embodiment, the first mold 71 is a movable mold and the second mold 72 is a fixed mold, but the first mold 71 is a fixed mold and the second mold 72 is a movable mold. It may be a mold. The position of the mold matching surface PL can be appropriately changed so as to facilitate mold release.

Further, in the above embodiment, the first and second molds 71 and 72 are configured by one mold, but the core mold and the outer peripheral mold that supports the core mold may be divided into the core mold. In this case, the essential transfer surface 71a and the sink mark induction transfer surface 72a are formed in a core shape.

Further, in the above embodiment, the entire surface of the essential molding surface 11 is a mirror surface, but a desired shape may be transferred within a range that does not affect the transfer accuracy. For example, in an exterior part or the like, a desired shape can be formed on the essential molded surface 11.

Claims (16)

An essential molding surface with a shape corresponding to the transfer part of the mold,
An optional molding surface having a surface shape different from that of the essential molding surface,
With
The arbitrary molding surface is at a position corresponding to the shrinkage inducing portion of the mold to promote air pocket without interfering with transcription by the transfer unit, and have a transfer unfinished part with sink,
The unfinished transfer portion is a molded product provided at a position along the development of the resin flow . The transfer unfinished part is discretely provided with respect to the deployment direction of the resin flow, molded article according to claim 1. The molded product according to any one of claims 1 and 2 , wherein the unfinished transfer portion has a plurality of convex portions. The molded product according to claim 3 , wherein each of the plurality of convex portions has an aspect ratio of 0.5 or more and a root width of 0.2 mm or more. The molded product according to any one of claims 3 and 4 , further comprising a concave portion adjacent to each of the plurality of convex portions on the gate portion side. The molded product according to any one of claims 3 and 4 , wherein the standing wall angle on the gate portion side of each of the plurality of convex portions is smaller than the standing wall angle on the opposite side of the gate portion. The molded product according to any one of claims 1 to 6 , wherein the unfinished transfer portion occupies 5% or more of the arbitrary molded surface in a plan view. A mirror including the molded product according to any one of claims 1 to 7 and a light reflecting layer provided on an essential forming surface of the molded product. The mirror according to claim 8 , wherein the molded product has a polyhedral shape including a plurality of surfaces arranged around a rotation axis. Melted into a mold having an essential transfer surface having a transfer portion and a sink mark-inducing transfer surface provided at a position along the development of the resin flow and having a sink mark-inducing portion that promotes air accumulation without hindering transfer by the transfer portion. Inject resin,
An air pool is generated at the sink mark inducer,
A method for producing a molded product, in which a sink mark is formed on the sink mark-induced transfer surface side and a shape corresponding to the transfer portion is formed on the essential transfer surface side. The method for manufacturing a molded product according to claim 10 , wherein the sink mark inducing portion is provided discretely with respect to the development direction of the resin flow. The method for producing a molded product according to any one of claims 10 and 11 , wherein the sink mark inducer has a plurality of grooves. The method for producing a molded product according to claim 12 , wherein each of the plurality of grooves has an aspect ratio of 0.5 or more and an inlet width of 0.2 mm or more. The method for producing a molded product according to any one of claims 12 and 13 , further comprising a convex wall portion adjacent to each of the plurality of grooves on the upstream side of the resin flow. The molded product according to any one of claims 12 and 13 , wherein the standing wall angle on the resin flow upstream side of each of the plurality of grooves is smaller than the standing wall angle on the opposite side of the resin flow upstream. Production method. The method for producing a molded product according to any one of claims 12 to 15 , wherein the sink mark-inducing portion occupies 5% or more of the sink mark-induced transfer surface in a plan view.

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