Mold for evaluating mold release resistance and method for evaluating mold release resistance

Abstract

To provide a mold for evaluating mold release resistance and a method for evaluating mold release resistance, which can accurately evaluate a frontal adhesion property on both surfaces of a movable mold and a resin molded product when releasing the resin molded product from the movable mold.SOLUTION: There is provided a mold 2 for evaluating mold release resistance, comprising: a mold 10 including a fixed mold 11 and a movable mold 12 that is movable in an opening / closing direction DR1 relative to the fixed mold 11 and forms a cavity 12A between the fixed mold 11 and the movable mold; an ejector mechanism 20 for releasing a resin molded product 60 from the movable mold 12; a pressure sensor 40 provided in the ejector mechanism 20; and a plate material 30 that is placed in the movable mold 12 and has heat resistance equal to or higher than a molding temperature of the resin composition, wherein the resin molded product 60 and the plate material 30 are released from the movable mold 12 in an integrated state.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a mold for evaluating release resistance and a method for evaluating release resistance. [Background technology]

[0002] Conventionally, various resin molded products have been produced by injection molding of resin compositions using a mold, but one of the market problems in the injection molding of resin compositions is the problem of mold release failure of the resin molded product, which may lead to dimensional deviations from standard or cracks in the product.

[0003] There are various causes of mold release failure, including material factors such as gas generation and shrinkage during molding, mold factors such as roughness and scratches on the inner wall surface of the mold, and molding conditions such as mold temperature and dwell pressure, but among these, the major factors are the clinging of the resin molded product to the mold due to its shrinkage and the sticking of the resin molded product to the mold. For this reason, mold release resistance, which is the resistance of the resin molded product when it is released from the mold, is sometimes measured and evaluated.

[0004] When the resin molded product moves together with the movable mold when the mold is opened, the demolding resistance force when releasing the resin molded product from the movable mold includes the adhesion force between the surfaces of the movable mold and the resin molded product (front adhesion force), the adhesion force between the sides of the movable mold and the resin molded product (side adhesion force), and resistance forces such as friction forces between the sides of the movable mold and the resin molded product (side resistance force); however, it is desirable to separate these and measure only the front adhesion force.

[0005] Currently, proposed methods for measuring the demolding resistance force when a resin molded product is released from the mold include, for example, a method for measuring the demolding resistance force of a resin molded product in a state where the sliding resistance force between the ejector pin and the movable cylinder is eliminated (see, for example, Patent Document 1), and a method for fixing a test piece to the fixed mold side and measuring the frontal adhesion force between the resin molded product and the test piece at the time of demolding (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 9-123231 [Patent Document 2] JP 2002-1778 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the technology of Patent Document 1, when the resin molded product is released from the mold by the ejector pin, the resin molded product is deformed, and the frontal adhesion cannot be accurately evaluated. In the technology of Patent Document 2, the frontal adhesion force is measured when the resin molded product is released from the fixed mold during mold opening, so the measured frontal adhesion force is not the frontal adhesion force between the movable mold and the resin molded product.

[0008] The present invention has been made to solve the above problems, and aims to provide a mold release resistance evaluation mold and a mold release resistance evaluation method that can accurately evaluate the front adhesion between a movable mold and the surface of a resin molded product when the resin molded product is released from the movable mold. [Means for solving the problem]

[0009] [1] A mold for evaluating mold release resistance for evaluating the resistance value when a resin molded product is released from a mold, comprising: a fixed-side mold; and a movable-side mold that is movable in an opening / closing direction relative to the fixed-side mold and forms a cavity between the fixed-side mold and the movable-side mold, into which a resin composition is injected; an ejector mechanism that is provided in the movable-side mold and that releases a resin molded product molded from the resin composition from the movable-side mold when the mold is opened; a pressure sensor that is provided in the ejector mechanism and that measures the mold release resistance value when the resin molded product is released from the movable-side mold by the ejector mechanism; and a plate material that is installed in the movable-side mold and has heat resistance equal to or higher than the molding temperature of the resin composition, wherein the resin molded product and the plate material are released from the movable-side mold in an integrated state.

[0010] [2] The mold for evaluating mold release resistance described in [1] above, wherein the resin molded product has a plate-shaped main body portion, and the inner wall surface of the movable mold has a first inner wall surface that contacts a surface that is the side opposite to the plate material side of the main body portion of the resin molded product, and a second inner wall surface that rises from the first inner wall surface toward the plate material side and is inclined so as to widen toward the plate material side with respect to the normal direction of the first inner wall surface, and contacts a side surface of the main body portion of the resin molded product.

[0011] [3] The mold for evaluating mold release resistance described in [1] above, wherein the resin molded product has a plate-shaped main body portion and a conical sprue portion connected to the main body portion.

[0012] [4] A mold for evaluating mold release resistance described in any one of [1] to [3] above, wherein the thickness of the plate material is 1 mm or more and 10 mm or less.

[0013] [5] A mold for evaluating mold release resistance described in any one of [1] to [4] above, wherein the plate material has a heat resistance of 350°C or more.

[0014] [6] A mold for evaluating mold release resistance described in any one of [1] to [5] above, wherein the plate material has a groove on the surface of the plate material that comes into contact with the resin molded product.

[0015] [7] A mold for evaluating mold release resistance described in any one of [1] to [6] above, wherein the fixed mold does not have a sprue, or has a sprue and the length of the sprue is 40 mm or less.

[0016] [8] A mold for evaluating mold release resistance described in any one of [1] to [7] above, wherein the fixed mold has a mechanism for pressing the plate material against the movable mold when the mold is opened.

[0017] [9] A mold for evaluating mold release resistance described in any one of [1] to [8] above, wherein the plate material has a through hole, the ejector mechanism has an ejector pin that pushes out the resin molded product at a position corresponding to the through hole, and the diameter of the ejector pin is equal to or greater than the diameter of the through hole.

[0018]

[10] The mold for evaluating mold release resistance described in [2] above, further comprising a thermocouple for measuring the temperature in the vicinity of the first inner wall surface of the movable mold.

[0019]

[11] A method for evaluating resistance when a resin molded product is released from a mold using the mold for evaluating mold release resistance described in [1] above, comprising the steps of: injecting a resin composition into the cavity to mold the resin molded product described in [3] above; moving the movable mold relative to the fixed mold to open the mold; releasing the resin molded product and the plate material in an integrated state from the movable mold by the ejector mechanism; and measuring the mold release resistance when the resin molded product and the plate material are released by the ejector mechanism using the pressure sensor. Effect of the Invention

[0020] According to the present invention, it is possible to provide a mold for evaluating mold release resistance and a method for evaluating mold release resistance that can accurately evaluate the frontal adhesion force between a movable mold and the surface of a resin molded product when the resin molded product is released from the movable mold. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic diagram of an injection molding machine equipped with a mold for evaluating mold release resistance according to an embodiment. [Diagram 2] FIG. 2 is an enlarged view of a portion of FIG. [Diagram 3] FIG. 3 is a plan view of a resin molded article obtained using a mold for evaluating mold release resistance according to the embodiment, as viewed from the front surface side of the resin molded article. [Figure 4] FIG. 4 is a plan view of another resin molded article obtained using the mold for evaluating mold release resistance according to the embodiment, as viewed from the front surface side of the resin molded article. [Diagram 5] FIG. 5A is a plan view showing the surface side of a plate material that is integrated with a resin molded product for evaluating release resistance according to the embodiment, and FIG. 5B is a plan view showing the surface side of another plate material that is integrated with a resin molded product for evaluating release resistance according to the embodiment. [Figure 6] 6A and 6B are schematic diagrams showing a mold release resistance evaluation step using a mold for evaluating mold release resistance according to an embodiment. [Figure 7] FIG. 7 is a schematic diagram showing a mold release resistance evaluation step using a mold for evaluating mold release resistance according to an embodiment. [Figure 8] FIG. 8 is a graph showing the mold release resistance value of a PPS resin molded product versus the moving distance of the ejector pin of the mold for evaluating mold release resistance according to Example 1. [Figure 9] FIG. 9 is a graph showing the mold release resistance value of a PPS resin molded product versus the moving distance of the ejector pin of the molds for evaluating mold release resistance according to Example 2 and Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, a mold release resistance evaluation die and a mold release resistance evaluation method according to an embodiment of the present invention will be described. FIG. 1 is a schematic diagram of the mold release resistance evaluation die according to this embodiment, and FIG. 2 is a diagram in which a part of FIG. 1 is enlarged. FIG. 3 is a plan view of a resin molded product obtained with the mold release resistance evaluation die according to this embodiment, viewed from the surface side of the resin molded product. FIG. 4 is a plan view of another resin molded product obtained with the mold release resistance evaluation die according to this embodiment, viewed from the surface side of the resin molded product. FIG. 5A is a plan view of the surface side of a plate material integrated with the resin molded product for mold release resistance evaluation according to this embodiment, and FIG. 5B is a plan view of the surface side of another plate material integrated with the resin molded product for mold release resistance evaluation according to this embodiment. FIG. 6A and FIG. 6B are schematic diagrams showing a mold release resistance evaluation process using the mold release resistance evaluation die according to this embodiment, and FIG. 7 is a schematic diagram showing a mold release resistance evaluation process using the mold release resistance evaluation die according to this embodiment.

[0023] <<<Injection molding machine and mold for evaluating demolding resistance>>> 1 mainly includes a mold 2 for evaluating mold release resistance, and a nozzle 3 for supplying a resin composition to the mold 2 for evaluating mold release resistance. The mold 2 for evaluating mold release resistance is for evaluating a resistance value when a resin molded product 60 is released from a mold 10. The nozzle 3 is fixed to a mounting plate 4. The mold 2 for evaluating mold release resistance mainly includes the mold 10, an ejector mechanism 20, a plate material 30, a pressure sensor 40, and a thermocouple 50.

[0024] <<Mold>> The mold 10 includes a fixed mold 11 and a movable mold 12 that is movable relative to the fixed mold 11 in an opening / closing direction DR1 and forms a cavity 12A between the fixed mold 11 and the movable mold 12.

[0025] <Fixed side mold> The fixed mold 11 has a sprue 11A, which is a flow path for the resin composition, as shown in FIG. 2. The length d of the sprue 11A is preferably 40 mm or less. If the length d of the sprue 11A is 40 mm or less, it is possible to suppress the resin molded product 60 from remaining on the fixed mold 11 side when the movable mold 12 is moved relative to the fixed mold 11 and the mold 10 is opened. From the viewpoint of suppressing the resin molded product 60 from remaining on the fixed mold 11 side, the length d of the sprue 11A is more preferably 25 mm or less, 20 mm or less, or 15 mm or less. The fixed mold 11 has the sprue 11A, but from the viewpoint of suppressing the resin molded product 60 from remaining on the fixed mold 11 side, it is not necessary to have the sprue 11A.

[0026] The fixed mold 11 has a pressing mechanism 11B that presses the plate material 30 against the movable mold 12 when the molds are opened. The fixed mold 11 has the pressing mechanism 11B, which can prevent the resin molded product 60 from remaining on the fixed mold 11 side when the molds are opened. The pressing mechanism 11B includes, for example, an elastic body 11B1 that applies an elastic force in the opening / closing direction DR1. The elastic body 11B1 is preferably a spring.

[0027] <Movable mold> The movable mold 12 has an inner wall surface 12B of the movable mold 12 that forms the cavity 12A. The inner wall surface 12B has a first inner wall surface 12C that contacts a front surface 61A, which is a surface opposite to a back surface 61C (see FIG. 2) that is a surface of the body portion 61 of the resin molded product 60 on the plate material 30 side, and a second inner wall surface 12D that rises from the first inner wall surface 12C toward the plate material 30 side and contacts a side surface 61B of the body portion 61 of the resin molded product 60. The second inner wall surface 12D is inclined so as to widen toward the plate material 30 side with respect to the normal direction DR2 of the first inner wall surface 12C. The resin molded product 60 has a plate-shaped body portion 61 and a sprue portion 62 that is connected to the back surface 61C of the body portion 61 as shown in FIG. 2 and FIG. 3. The sprue portion 62 is a portion that corresponds to the sprue 11A. The sprue portion 62 is joined to a position that is the center of the main body portion 61. If the fixed mold 11 does not have a sprue 11A, the sprue portion 62 is not formed, and in this case, the resin molded product 60 is composed of only the main body portion 61. The front surface 61A of the main body portion 61 is located closer to the ejector mechanism 20 than the back surface 61C. The main body portion 61 of the resin molded product 60 is disk-shaped, but the shape is not particularly limited. For example, the main body portion of the resin molded product may be a rectangular flat plate like the main body portion 71 of the resin molded product 70. The resin molded product 70 has a sprue portion 72 in addition to the main body portion 71. The main body portion 71 has a front surface 71A.

[0028] The first inner wall surface 12C is a plane perpendicular or substantially perpendicular to the opening / closing direction DR1. The first inner wall surface 12C has an opening 12C1 for projecting the ejector pin 21 into the movable mold 12. The opening 12C1 is provided in the center of the first inner wall surface 12C. This allows the tip of the ejector pin 21 to contact the center of the resin molded product 60, making it easy to release from the mold. The first inner wall surface 12C is flat. The shape of the first inner wall surface 12C is not particularly limited, but is preferably, for example, circular. By making the shape of the first inner wall surface 12C circular, it is possible to mount an ejector pin that is commonly available.

[0029] The second inner wall surface 12D rises from the first inner wall surface 12C toward the fixed mold 11, so there are no other inner wall surfaces between the first inner wall surface 12C and the second inner wall surface 12D. In addition, the surface 30A of the plate material 30 is in contact with the edge of the second inner wall surface 12D on the fixed mold 11 side. As a result, there are no other inner wall surfaces between the second inner wall surface 12D and the plate material 30.

[0030] As described above, the second inner wall surface 12D is inclined so as to diverge toward the plate material 30 side with respect to the normal direction DR2 of the first inner wall surface 12C, but the angle θ (see FIG. 1) of the second inner wall surface 12D with respect to the normal direction DR2 (see FIG. 2) of the first inner wall surface 12C is preferably greater than 0° and less than 90°, and is preferably less than 60°. If the angle θ is within this range, the side adhesion force and side resistance force of the side surface 61B of the main body portion 61 of the resin molded product 60 at the time of demolding the resin molded product 60 can be almost eliminated. The lower limit of the angle θ is preferably 0.25° or more, and the upper limit is preferably 85° or less. Since the resin molded product 60 is obtained using the movable side mold 12, the main body portion 61 has a shape that diverges from the front surface 61A side toward the back surface 61C side. In addition, the angle of the side surface 61B with respect to the normal direction DR2 of the front surface 61A of the main body portion 61 is also angle θ.

[0031] <Ejector mechanism> The ejector mechanism 20 pushes the resin molded product 60 from the surface 61A side of the main body 61 of the resin molded product 60 toward the fixed mold 11 side when the molds are opened, thereby releasing the resin molded product 60 from the movable mold 12. The ejector mechanism 20 includes an ejector pin 21 capable of protruding toward the fixed mold 11 side. The ejector pin 21 is capable of protruding into the movable mold 12 through an opening 12C1 of the movable mold 12.

[0032] If the diameter of the ejector pin is smaller than the diameter of the through hole of the plate material, which will be described later, there is a risk that the ejector pin will break through the resin molded product when the resin molded product is released from the movable mold by the ejector pin. Therefore, from the viewpoint of suppressing the ejector pin 21 from breaking through the resin molded product 60, the diameter of the ejector pin 21 is preferably equal to or larger than the diameter of the through hole 31. It is more preferable that the diameter of the ejector pin 21 is 4 mm or more and 10 mm or less. If the diameter of the ejector pin 21 is within this range, the ejector pin 21 can be further suppressed from breaking through the resin molded product 60, and the front adhesion force when the resin molded product 60 is released can be accurately measured. When the cross-sectional shape of the ejector pin is circular, the diameter of the ejector pin means the diameter, and when the cross-sectional shape of the ejector pin is other than a circle, the diameter of the ejector pin means the diameter of the circumscribed circle of the cross-sectional shape.

[0033] The protruding distance of the ejector pin 21 from the first inner wall surface 12C is preferably 6 mm or more. If the protruding distance is 6 mm or more, the ejector pin 21 can release the resin molded product 60 from the movable mold 12.

[0034] <Plate material> The plate material 30 is disposed in the movable mold 12. Specifically, the plate material 30 is disposed so that the front surface 30A of the plate material 30 contacts the rear surface 61C of the main body 61 of the resin molded product 60. The plate material 30 is located in the mold 10 during molding of the resin composition, and therefore has heat resistance equal to or higher than the molding temperature of the resin composition. In this specification, "heat resistance equal to or higher than the molding temperature of the resin composition" means a property of withstanding high temperatures to such an extent that the shape of the plate material can be maintained even when used at the molding temperature of the resin composition. For example, the plate material 30 preferably has heat resistance of 350°C or higher, more preferably 400°C or higher.

[0035] The constituent material of the plate material 30 is not particularly limited as long as it has heat resistance equal to or higher than the molding temperature of the resin composition, and may be, for example, a metal or a resin. Examples of metals include iron, aluminum, and stainless steel. Examples of resins include, depending on the molding temperature of the resin composition to be molded, thermosetting resins, and resins in which thermosetting resins are reinforced with inorganic fibers.

[0036] The rigidity (Young's modulus) of the plate material 30 at 300°C is preferably 8000 MPa or more. If the rigidity of the plate material 30 at 300°C is 8000 MPa or more, the plate material 30 will not deform when the resin molded product 60 is released from the mold. The lower limit of the rigidity of the plate material 30 at 300°C is more preferably 10000 MPa or more, 50000 MPa or more, or 100000 MPa or more, and the upper limit may be 200000 MPa or less. The rigidity of the plate material 30 can be measured by a tensile test.

[0037] The thickness of the plate material 30 is preferably 1 mm or more and 10 mm or less. If the thickness of the plate material 30 is 1 mm or more, deformation of the resin molded product 60 can be suppressed when the resin molded product 60 is released from the movable mold 22, and if the thickness is 10 mm or less, handling during evaluation of releasability is easy. The lower limit of the thickness of the plate material 30 is more preferably 1.5 mm or more, 2 mm or more, or 2.5 mm or more, and the upper limit is more preferably 8 mm or less, 6 mm or less, or 4 mm or less. In this specification, the "thickness of the plate material" refers to the thickness of the plate material other than the grooves described later.

[0038] The plate material 30 is preferably in a flat plate shape. By making the plate material 30 in a flat plate shape, the orientation and arrangement of the plate material 30 can be kept constant when the plate material 30 is inserted into the movable die 12. The size of the plate material 30 is preferably equal to or larger than the size of the main body 61 of the resin molded product 60. By making the plate material 30 in such a size, deformation of the resin molded product 60 when the resin molded product 60 is released from the movable die 12 can be further suppressed.

[0039] 2 and 5A, the plate material 30 has a through hole 31 for supplying the resin composition supplied from the sprue 11A to the movable mold 12. By providing such a through hole 31 in the plate material 30, the resin composition supplied from the sprue 11A of the fixed mold 11 flows through this through hole 31 to the movable mold 12. The through hole 31 is located in the center of the plate material 30, but the location of the through hole 31 is not particularly limited.

[0040] The shape of the through hole 31 is not particularly limited, but is preferably, for example, circular. By making the shape of the through hole 31 circular, it can be applied to the sprue shape of a resin molded product, which is generally designed to be conical, and the surface area can be minimized. The diameter of the through hole 31 is preferably 2 mm or more and 6 mm or less. If the diameter of the through hole 31 is 2 mm or more, the resin composition can be smoothly flowed into the movable side mold 12, and if the diameter of the through hole 31 is 6 mm or less, the contact area between the plate material 30 and the back surface 61C of the main body part 61 of the resin molded product 60 is not too low, and deformation of the resin molded product 60 when the resin molded product 60 is released from the movable side mold 12 can be further suppressed. The lower limit of the diameter of the through hole 31 is more preferably 3 mm or more, 3.5 mm or more, or 4 mm or more, and the upper limit is more preferably 5 mm or less or 4.5 mm or less. When the cross-sectional shape of the through hole is circular, the diameter of the through hole means the diameter, and when the cross-sectional shape of the through hole is other than circular, the diameter of the through hole means the diameter of the circumscribing circle of the cross-sectional shape.

[0041] It is preferable that the surface of the plate material 30 that contacts the resin molded product is surface-treated. By applying the surface treatment to this surface, the shrinkage of the resin constituting the resin molded product can be suppressed due to the presence of the surface-treated portion. Examples of surface treatment include groove processing, convex processing, embossing, undercut processing, and surface roughening. In the plate material 30 shown in FIG. 2 and FIG. 5A, a groove 32 is formed on the surface of the plate material 30 that contacts the resin molded product. By forming such a groove 32 in the plate material 30, a part of the resin composition can be made to enter the groove 32 during molding of the resin composition, so that a convex portion 61D formed on the back surface 61C of the main body portion 61 of the resin molded product 60 and entering the groove 32 can be formed. This makes it possible to suppress the shrinkage of the resin constituting the resin molded product 60. Note that the plate material does not need to be provided with a groove like the plate material 30 shown in FIG. 5B.

[0042] The shape of the groove 32 is not particularly limited, but is preferably, for example, annular or lattice-shaped. By making the groove 32 annular, shrinkage of the resin molded product 60 can be suppressed generally uniformly. When the groove 32 is annular, it may be a square ring or a circular ring. When the groove 32 is circular, the inner diameter of the groove 32 is preferably 39 mm or more and 41 mm or less, and the outer diameter of the groove 32 is preferably 44 mm or more and 46 mm or less.

[0043] The width of the groove 32 is preferably thinner than the thickness of the resin molded product 60. By making the width of the groove 32 thinner than the thickness of the resin molded product 60, it is possible to further suppress the shrinkage of the resin that constitutes the resin molded product 60. The width of the groove 32 is preferably 2.4 mm or more and 2.6 mm or less.

[0044] The depth of the groove 32 is preferably about 1 / 3 of the thickness of the plate material 30. If the depth of the groove 32 is about 1 / 3 of the thickness of the plate material 30, the shrinkage of the resin that constitutes the resin molded product 60 can be further suppressed. The depth of the groove 32 is preferably 0.9 mm or more and 1.1 mm or less. If the depth of the groove 32 is within this range, the shrinkage of the resin that constitutes the resin molded product 60 can be further suppressed and the strength of the plate material 30 can be ensured.

[0045] <Pressure sensor> The pressure sensor 40 measures a demolding resistance value when the ejector mechanism 20 releases the resin molded product 60 from the movable mold 12. The pressure sensor 40 is provided in the ejector mechanism 20. More specifically, the pressure sensor 40 is provided at the rear end of the ejector pin 21 of the ejector mechanism 20.

[0046] Since the pressure sensor 40 is disposed outside the mold 10, it is not necessary for it to be heat resistant to temperatures equal to or higher than the molding temperature of the resin composition, but it is preferable for it to have a certain degree of heat resistance. In this specification, "a certain degree of heat resistance" means a property that allows pressure to be measured normally during the molding process of the resin composition and subsequent processes. For example, the pressure sensor 40 has a heat resistance of preferably 100°C or higher, more preferably 125°C or higher, and even more preferably 150°C or higher. As the pressure sensor 40, a commercially available product can be used.

[0047] <Thermocouple> The thermocouple 50 is for measuring the temperature in the vicinity of the first inner wall surface 12C of the movable mold 12, and is inserted into a hole 12E provided in the movable mold 12.

[0048] <<Release resistance evaluation method>> When evaluating the mold release resistance of a resin molded product 60 using the mold release resistance evaluation mold 2, in a clamped state, a resin composition 80 is filled into a cavity 12A through a sprue 11A of a fixed mold 11 by a nozzle 3 as shown in Fig. 6A. A plate material 30 is disposed in the mold 10, and since a through hole 31 is formed in the plate material 30, the resin composition 80 flows from the fixed mold 11 side to the movable mold 12 side through the through hole 31. As a result, the resin composition 80 is molded, and a resin molded product 60 is obtained.

[0049] After the resin molded product 60 has cooled, the movable mold 12 is moved relative to the fixed mold 11 to open the mold, as shown in Fig. 6B. When the movable mold 12 moves, the resin molded product 60 and the plate material 30 move together with the movable mold 12 and move away from the fixed mold 11.

[0050] 7, the ejector pin 21 of the ejector mechanism 20 is pushed out toward the cavity 12A of the movable mold 12 to release the resin molded product 60 and the plate material 30 from the movable mold 12. The ejector pin 21 is provided with a pressure sensor 40, which measures a release resistance value, which is a resistance value when releasing the resin molded product 60 and the plate material 30 from the movable mold 12.

[0051] According to this embodiment, the plate material 30 is provided which is set in the movable mold 12 and has a heat resistance equal to or higher than the molding temperature of the resin composition, and the resin molded product 60 and the plate material 30 are released from the movable mold 12 in an integrated state, so that deformation of the resin molded product 60 can be suppressed when the resin molded product 60 is released from the movable mold 12, and the resin molded product 60 can be instantly released from the movable mold 12. As a result, by measuring the mold release resistance value when the resin molded product 60 is released from the movable mold 12 by the ejector mechanism 20 using the pressure sensor 40, the front adhesion force of the surface 61A of the main body part 61 of the resin molded product 60 when the resin molded product 60 is released from the movable mold 12 can be accurately evaluated.

[0052] According to this embodiment, in addition to the placement of the plate material 30, the second inner wall surface 12D is inclined so as to widen toward the plate material 30 side, so that the side adhesion force and side resistance force of the side surface 61B of the main body part 61 of the resin molded product 60 when the resin molded product 60 is released from the mold can be almost eliminated. In addition, the groove 32 is formed on the surface of the plate material 30 that contacts the resin molded product, so that the contraction of the resin constituting the resin molded product 60 can be suppressed. As a result, by measuring the mold release resistance value when the resin molded product 60 is released from the movable mold 12 by the ejector mechanism 20 using the pressure sensor 40, the front adhesion force of the surface 61A of the main body part 61 of the resin molded product 60 when the resin molded product 60 is released from the movable mold 12 can be evaluated with higher accuracy. EXAMPLES

[0053] In order to explain the present invention in detail, the following examples are given, but the present invention is not limited to these. Fig. 8 is a graph showing the demolding resistance value of a PPS resin molded product versus the moving distance of an ejector pin of a mold for evaluating demolding resistance according to Example 1, and Fig. 9 is a graph showing the demolding resistance value of a PPS resin molded product versus the moving distance of an ejector pin of a mold for evaluating demolding resistance according to Example 2 and Comparative Example 1.

[0054] <Example 1> First, a mold consisting of a fixed mold and a movable mold was prepared. The fixed mold was made of quenched and tempered steel. The fixed mold had a sprue with a length of 12 mm and a maximum diameter of 4 mm. A recess was formed on the surface of the fixed mold facing the movable mold, and an oil-tempered spring wire with a length of 20 mm and a diameter of 10.5 mm (model number "NT-SWS10.5-20", manufactured by Misumi Corporation) that expands and contracts in the direction of movement of the movable mold was placed in the recess.

[0055] The movable die was made of hardened and tempered steel. A cavity was formed in the movable die, and the inner wall surface of the movable die had a first inner wall surface that was in contact with the surface of the main body of the resin molded product and was a plane perpendicular to the opening and closing direction, and a second inner wall surface that rose from the first inner wall surface toward the fixed die side, was inclined at 30° (θ=30°) from the normal direction of the first inner wall surface so as to widen toward the fixed die side, and was in contact with the side of the main body of the resin molded product. The first inner wall surface was circular and had a diameter of 50 mm. The movable die was provided with an ejector mechanism having a cylindrical ejector pin with a diameter of 6 mm, and the ejector pin was capable of protruding into the cavity of the movable die from an opening provided in the first inner wall surface. A pressure sensor (product number "9221AC1", manufactured by Kistler Instrumente) was provided at the rear end of the ejector pin.

[0056] A plate material was also prepared. The plate material was made of quenched and tempered steel (product name "S-STAR", Daido Steel Co., Ltd.). The plate material was a flat rectangular plate measuring 60 mm square with a circular through hole having a diameter of 6 mm. The thickness of the plate material was 3 mm. The heat resistance of the plate material was 350°C or higher, and the rigidity of the plate material was 200,000 MPa at 300°C. A ring-shaped groove having a width of 2.5 mm was also formed in the plate material. The outer diameter of the groove was 45 mm, and the inner diameter of the groove was 40 mm.

[0057] Next, after preparing a plate material, the plate material was placed in the movable mold so that the groove side of the plate material was the first inner wall surface side of the movable mold and covered the cavity of the movable mold. The distance from the first inner wall surface to the plate material was 2.5 mm. In this way, a mold for evaluating mold release resistance was produced.

[0058] Next, the fixed mold and the movable mold of the mold for evaluating mold release resistance were closed and clamped. After that, with the mold at 195°C, a polyphenylene sulfide resin composition (PPS resin composition) containing 30 mass% of glass fiber was injected from a cylinder at 320°C through the sprue of the fixed mold at an injection speed of 30 mm / sec to fill the cavity. The PPS resin composition was supplied to the movable mold side through the through hole of the plate material. Then, a dwell pressure of 40 MPa was applied to the PPS resin composition filled in the cavity.

[0059] After pressure dwell, the PPS resin composition was cooled for 20 seconds to solidify. After the PPS resin composition had solidified, the movable mold was moved relative to the fixed mold to open the mold. When the mold was opened, the PPS resin molded product and plate material obtained by solidifying the PPS resin composition moved together with the movable mold. Therefore, the PPS resin molded product did not remain in the fixed mold.

[0060] After the mold was opened, the ejector pins of the ejector pin mechanism were pushed into the cavity of the movable mold to release the PPS resin molded product and the plate from the movable mold. At this time, the mold release resistance value during mold release was measured using a pressure sensor, and the graph shown in Figure 8 was obtained. The PPS resin molded product had a main body with a diameter of 50 mm and a thickness of 2.5 mm, and a sprue part that protruded from the back surface of the main body with a length of 12 mm and a maximum diameter of 4 mm.

[0061] <Example 2> First, a mold was prepared consisting of a fixed mold and a movable mold. The fixed mold was made of hardened and tempered steel. The fixed mold had a sprue with a length of 12 mm and a maximum diameter of 4 mm.

[0062] The movable die was made of hardened and tempered steel. A cavity was formed in the movable die, and the inner wall surface of the movable die had a first inner wall surface that was a plane that was in contact with the surface of the main body of the resin molded product and perpendicular to the opening and closing direction, and a second inner wall surface that rose toward the fixed die side so that the angle between the first inner wall surface and the normal direction of the first inner wall surface was 0°, i.e., perpendicular to the first inner wall surface, and was in contact with the side of the main body of the resin molded product. The first inner wall surface had a square shape measuring 40 mm x 40 mm. The movable die was provided with an ejector mechanism having a cylindrical ejector pin with a diameter of 6 mm, and the ejector pin was capable of protruding into the cavity of the movable die from an opening provided in the first inner wall surface. A pressure sensor (product number "9221AC1", manufactured by Kistler Instrumente) was provided at the rear end of the ejector pin.

[0063] A plate material was also prepared. The plate material was made of quenched and tempered steel (product name "S-STAR", Daido Steel Co., Ltd.). The plate material was a rectangular flat plate measuring 60 mm square with a circular through hole having a diameter of 6 mm. The thickness of the plate material was 3 mm. The heat resistance of the plate material was 350°C or higher, and the rigidity (Young's modulus) of the plate material was 200,000 MPa at 300°C. The plate material did not have any grooves.

[0064] Next, after preparing a plate material, the plate material was placed on the movable mold so as to cover the cavity of the movable mold. The distance from the first inner wall surface to the plate material was 2.5 mm. In this way, a mold for evaluating mold release resistance was produced.

[0065] Next, the fixed mold and the movable mold of the mold for evaluating mold release resistance were closed and clamped. After that, with the mold at 180°C, a polyphenylene sulfide resin composition (PPS resin composition) containing 30 mass% of glass fiber was injected from a cylinder at 320°C through the sprue of the fixed mold at an injection speed of 30 mm / sec to fill the cavity. The PPS resin composition was supplied to the movable mold side through the through hole of the plate material. Then, a dwell pressure of 50 MPa was applied to the PPS resin composition filled in the cavity.

[0066] After pressure dwell, the PPS resin composition was cooled for 30 seconds to solidify. After the PPS resin composition had solidified, the movable mold was moved relative to the fixed mold to open the mold. When the mold was opened, the PPS resin molded product and plate material obtained by solidifying the PPS resin composition moved together with the movable mold. Therefore, the PPS resin molded product did not remain in the fixed mold.

[0067] After the mold was opened, the ejector pins of the ejector pin mechanism were pushed out into the cavity of the movable mold to release the PPS resin molded product and the plate from the movable mold. At this time, the mold release resistance value during mold release was measured using a pressure sensor, and the graph shown in Figure 9 was obtained. The PPS resin molded product had a size of 40 mm x 40 mm, a main body with a thickness of 2.5 mm, and a sprue part that protruded from the back surface of the main body by 12 mm and had a maximum diameter of 4 mm.

[0068] <Comparative Example 1> In Comparative Example 1, except that no plate material was provided, a mold for evaluating mold release resistance similar to that in Example 2 was used, and a PPS resin molded article was obtained and released from the movable mold under similar conditions and procedures to those in Example 2. In addition, the mold release resistance value during release was measured by a pressure sensor, and the graph shown in Fig. 9 was obtained.

[0069] <Result> As shown in FIG. 8 and FIG. 9, a sharp peak was obtained in the graph of the release resistance value measured using the mold for evaluating release resistance according to Example 1 and Example 2. In addition, in the graph of FIG. 8, the release resistance value was maximum when the moving distance of the ejector pin was 0.204 mm. In addition, in the graph of FIG. 9, the release resistance value measured using the mold for evaluating release resistance according to Example 2 was maximum when the moving distance of the ejector pin was 0.23 mm. In contrast, in the graph of the release resistance value measured using the mold for evaluating release resistance according to Comparative Example 1 shown in FIG. 9, a broad waveform was obtained. In this graph, the release resistance value was maximum when the moving distance of the ejector pin was 0.63 mm. In addition, in the mold for evaluating release resistance according to Examples 1 and 2 and Comparative Example 1, the PPS resin molded product was released from the movable mold when the moving distance of the ejector pin was 0.6 mm to 0.8 mm. From these results, it was confirmed that when the mold release resistance value is measured using the molds for evaluating mold release resistance of Examples 1 and 2, the frontal adhesion force between the movable mold and the surface of the resin molded product can be measured with high accuracy.

[0070] Comparing the graph of the mold release resistance measured using the mold for evaluating mold release resistance according to Example 1 in FIG. 8 and the graph of the mold release resistance measured using the mold for evaluating mold release resistance according to Example 2 in FIG. 9, the mold release resistance measured using the mold for evaluating mold release resistance according to Example 1 had a sharper peak than the mold release resistance measured using the mold for evaluating mold release resistance according to Example 2. This is considered to be because the mold release resistance evaluation mold according to Example 1 used a plate material with a groove and a movable mold inclined so that the second inner wall surface diverges toward the fixed mold side with respect to the normal direction of the first inner wall surface, whereas the mold release resistance evaluation mold according to Example 2 used a plate material with no groove and a movable mold in which the second inner wall surface is perpendicular to the first inner wall surface. From this result, it was confirmed that the front adhesion force between the movable mold and the surface of the resin molded product can be measured with higher accuracy when the movable mold inclined so that the plate material with a groove and the second inner wall surface diverges toward the fixed mold side with respect to the normal direction of the first inner wall surface are used.

[0071] 1…Injection molding machine 2…Mold for evaluating release resistance 3…Nozzle 10. Mold 11…Fixed side mold 12... Movable mold 12A…Cavity 12B…Inner wall surface 12C…First inner wall surface 12D…Second inner wall surface 20...Ejector mechanism 21...Ejector pin 30...Plate material 31...Through hole 32…Groove 40...Pressure sensor 50...Thermocouple 60...Resin molded products 61...Main body 61A…Surface 61B…Side 61C…Back 80...Resin composition

Claims

1. A mold release resistance evaluation mold for evaluating a resistance value when a resin molded product is released from a mold, a mold including a fixed mold and a movable mold that is movable in an opening / closing direction relative to the fixed mold and forms a cavity between the fixed mold and the movable mold, the mold being configured to inject a resin composition into the cavity; an ejector mechanism provided in the movable mold and configured to release a resin molded product formed from the resin composition from the movable mold when the molds are opened; a pressure sensor provided in the ejector mechanism and configured to measure a mold release resistance value when the ejector mechanism releases the resin molded product from the movable mold; A plate material is placed in the movable mold and has a heat resistance equal to or higher than the molding temperature of the resin composition, The resin molded product and the plate material are released from the movable mold in an integrated state, thereby forming a mold for evaluating mold release resistance.

2. 2. The mold for evaluating mold release resistance according to claim 1, wherein the resin molded product has a plate-shaped main body portion, and the inner wall surface of the movable mold has a first inner wall surface that contacts a surface that is the side opposite to the plate material side of the main body portion of the resin molded product, and a second inner wall surface that rises from the first inner wall surface toward the plate material side, is inclined so as to widen toward the plate material side with respect to the normal direction of the first inner wall surface, and contacts a side surface of the main body portion of the resin molded product.

3. The mold for evaluating mold release resistance according to claim 1 , wherein the resin molded product comprises a plate-shaped main body portion and a conical sprue portion connected to the main body portion.

4. The mold for evaluating mold release resistance according to claim 1 , wherein the thickness of the plate material is 1 mm or more and 10 mm or less.

5. The mold for evaluating mold release resistance according to claim 1 , wherein the plate material has a heat resistance of 350° C. or more.

6. The mold for evaluating mold release resistance according to claim 1 , wherein the plate material has a groove on a surface of the plate material that comes into contact with the resin molded product.

7. The mold for evaluating mold release resistance according to claim 1 , wherein the fixed mold does not have a sprue, or has a sprue and the length of the sprue is 40 mm or less.

8. The mold release resistance evaluation mold according to claim 1 , wherein the fixed mold has a mechanism for pressing the plate material against the movable mold when the mold is opened.

9. 2. The mold for evaluating mold release resistance according to claim 1, wherein the plate material has a through hole, the ejector mechanism has an ejector pin that pushes out the resin molded product at a position corresponding to the through hole, and the diameter of the ejector pin is equal to or greater than the diameter of the through hole.

10. The mold release resistance evaluation mold according to claim 2 , further comprising a thermocouple for measuring a temperature in the vicinity of the first inner wall surface of the movable mold.

11. A mold release resistance evaluation method for evaluating a resistance value when a resin molded product is released from a mold by using the mold release resistance evaluation mold according to claim 1, A step of injecting a resin composition into the cavity to form the resin molded product according to claim 3; a step of moving the movable die relative to the fixed die and opening the die; releasing the resin molded product and the plate material in an integrated state from the movable mold by the ejector mechanism; measuring a demolding resistance value when the resin molded product and the plate material are demolded by the ejector mechanism with the pressure sensor; The release resistance evaluation method includes:

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