Manufacturing method of molded products

Abstract

To provide molded products in which shading patterns at arbitrary locations can be easily added.SOLUTION: The molded product according to the present disclosure is an injection-molded product using cellulosic fiber composite resin, and has a gate mark at the time of injection molding, a first region composed of cellulosic fiber composite resin, and a second region composed along the resin merging interface starting at a position separated from the gate mark and extending in a direction away from the gate mark, on both sides of the resin merging interface, the first region and second region being different in color tone.SELECTED DRAWING: Figure 1D

Description

[Technical Field]

[0001] The present disclosure relates to a molded product, a manufacturing method thereof, an injection molding die, and a molding apparatus. [Background technology]

[0002] In recent years, in light of environmental issues such as the depletion of petroleum resources and global warming, as well as the problem of marine plastics, the efficient use of natural resources (SDG Goal 12) and the prevention and significant reduction of marine pollution (SDG Goal 14) have been set as development goals by the United Nations. As a result, there is a global demand to reduce the amount of petroleum-derived resins used.

[0003] In research and development activities to reduce the amount of petroleum-derived resin, a composite processing technology is known in which cellulose fiber, a naturally derived component, is mixed into resin at a concentration of 55%.

[0004] Patent Document 1 discloses a molded article with a high designability that makes use of the properties of cellulose. Specifically, Patent Document 1 discloses a molded article having a pattern of varying shades of color.

[0005] In Patent Document 1, a cellulose-based composite resin is used, and the mold structure and molding gate position are designed to intentionally create weld lines in the molded product. The cellulose at the weld line denatures, producing furfural, a browning component, which creates a shading pattern. Therefore, molded products with shading patterns can be produced without mixing multiple types of pellets or using colorants. By controlling the amount of furfural produced, the natural discoloration or color unevenness that occurs with the aging and growth of natural wood can be created in the molded product while maintaining the basic color of the molded product. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-115989 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the method described in Patent Document 1, the obstacles that form the color shading pattern are placed on a tab gate located outside the product, and the tab gate is removed after molding, which poses a problem in that it is not possible to impart color shading to any desired position on the molded product.

[0008] Therefore, the method described in Patent Document 1 still has room for improvement in that it is difficult to impart a shading pattern at any position on a molded product.

[0009] In order to solve the above-mentioned problems, the present disclosure aims to provide a molded product that can easily be provided with a shading pattern at any position. [Means for solving the problem]

[0010] The molded product according to the present disclosure is an injection-molded product using a cellulose-based fiber composite resin, and has a gate mark made during injection molding, a first region made of the cellulose-based fiber composite resin, and a second region formed on both sides of the resin merging interface along the resin merging interface that starts at a position away from the gate mark and extends in a direction away from the gate mark, the first region and the second region having different color tones.

[0011] A method for manufacturing a molded product according to the present disclosure includes: arranging an obstacle that is spaced from a gate and protrudes at a first height toward a cavity between molds; injection molding a cellulose-based fiber composite resin from the gate into the cavity to form a first region made of cellulose-based fiber composite resin; and forming a second region of a different color tone from the first region along a resin merging interface extending downstream from the obstacle and across both sides of the resin merging interface; and retracting the obstacle into the mold to a second height that is smaller than the first height.

[0012] The injection molding die according to the present disclosure includes a die that forms a cavity, and an obstacle that is movable between a first height that protrudes into the cavity and a second height that is retracted inside the die and is smaller than the first height.

[0013] The molding apparatus according to the present disclosure includes an injection molding die and an injection molding machine that injects a cellulose-based fiber composite resin. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to provide a molded product that can easily be provided with a shading pattern at any position. [Brief explanation of the drawings]

[0015] [Figure 1A] 1 is a schematic perspective view showing one step of a method for manufacturing a molded article according to the first embodiment. FIG. [Figure 1B] 1 is a schematic perspective view showing one step of a method for manufacturing a molded article according to the first embodiment. FIG. [Figure 1C] 1 is a schematic perspective view showing one step of a method for manufacturing a molded article according to the first embodiment. FIG. [Figure 1D] 1 is a schematic perspective view showing one step of a method for manufacturing a molded article according to the first embodiment. FIG. [Figure 2A] FIG. 2 is a plan view showing the flow of the cellulose fiber composite resin in detail. [Figure 2B] FIG. 2 is a plan view showing the flow of the cellulose fiber composite resin in detail. [Figure 3A] FIG. 2 is a schematic perspective view showing one step of a method for manufacturing a molded product. [Figure 3B] 10A and 10B are cross-sectional views showing the operation of an obstacle in a molded product. [Figure 3C] 10A and 10B are cross-sectional views showing the operation of an obstacle in a molded product. [Figure 3D] 10A and 10B are cross-sectional views showing the operation of an obstacle in a molded product. [Figure 4] 1 is a schematic cross-sectional view showing a cross-sectional configuration of an injection molding apparatus according to a first embodiment. [Figure 5A]10A and 10B are cross-sectional views showing the operation of an obstacle provided in a mold of an injection molding device. [Figure 5B] 10A and 10B are cross-sectional views showing the operation of an obstacle provided in a mold of an injection molding device. [Figure 5C] 10A and 10B are cross-sectional views showing the operation of an obstacle provided in a mold of an injection molding device. [Figure 6] FIG. 10 is a schematic cross-sectional view showing the cross-sectional configuration of an injection molding apparatus according to a second embodiment. [Figure 7A] 10A and 10B are schematic diagrams showing the operation of an obstacle provided in a mold of an injection molding machine. [Figure 7B] 10A and 10B are schematic diagrams showing the operation of an obstacle provided in a mold of an injection molding machine. [Figure 8A] FIG. 10 is a perspective view showing a molded product and an obstacle according to a third embodiment. [Figure 8B] FIG. 8B is a perspective view of the obstacle shown in FIG. 8A. [Figure 8C] FIG. 10 is a plan view showing one step of the method for manufacturing a molded article according to the third embodiment. [Figure 8D] FIG. 10 is a cross-sectional view showing one step of a method for producing a molded article according to a third embodiment. [Figure 8E] FIG. 10 is a cross-sectional view showing one step of a method for producing a molded article according to a third embodiment. [Figure 8F] FIG. 10 is a plan view showing one step of the method for manufacturing a molded article according to the third embodiment. [Figure 9] 1 is a photograph showing a linear pattern on a molded product. DETAILED DESCRIPTION OF THE INVENTION

[0016] The molded product according to the first aspect of the present disclosure is an injection-molded product using a cellulose-based fiber composite resin, and has a gate mark made during injection molding, a first region made of the cellulose-based fiber composite resin, and a second region formed on both sides of the resin merging interface along the resin merging interface that starts from a position spaced apart from the gate mark and extends in a direction away from the gate mark, the first region and the second region having different color tones.

[0017] With this configuration, a shading pattern made up of the first and second regions can be formed at any position on the molded product away from the gate mark.

[0018] In the molded product according to the second aspect of the present disclosure, a transfer mark may be formed between the gate mark and the starting point.

[0019] With this configuration, the obstacle can be placed at any position during injection molding, and the flow of the cellulose fiber composite resin can branch and merge around the obstacle, thereby forming a shading pattern at any position.

[0020] In the molded product according to the third aspect of the present disclosure, the second region may be narrower than the first region and may have a linear pattern.

[0021] With this configuration, a linear pattern can be formed.

[0022] In the molded article according to the fourth aspect of the present disclosure, the second region may contain a carbonized cellulosic fiber.

[0023] This configuration allows for the creation of a shading pattern that gives the impression of real wood.

[0024] A method for manufacturing a molded product according to a fifth aspect of the present disclosure includes: arranging an obstacle that is spaced from a gate and protrudes at a first height toward a cavity between molds; injection molding a cellulose-based fiber composite resin from the gate into the cavity to form a first region made of cellulose-based fiber composite resin; and forming a second region of a different color tone from the first region along a resin merging interface extending downstream from the obstacle and across both sides of the resin merging interface; and retracting the obstacle into the molds to a second height that is smaller than the first height.

[0025] By using this method, a shading pattern consisting of the first and second regions can be formed at any position on the molded product away from the gate.

[0026] In the method for producing a molded article according to the sixth aspect of the present disclosure, the obstacle may be retracted from the first height to the second height by the injection pressure of the cellulose-based fiber composite resin.

[0027] This method can prevent obstacles from being transferred to the molded product.

[0028] In the method for manufacturing a molded product according to the seventh aspect of the present disclosure, the obstacle may be retracted from the first height to the second height by a drive source connected to the obstacle.

[0029] This method can prevent obstacles from being transferred to the molded product.

[0030] An injection molding die according to an eighth aspect of the present disclosure has a die that forms a cavity, and an obstacle that is retracted inside the die and is movable between a first height that protrudes into the cavity and a second height that is smaller than the first height.

[0031] With this configuration, a shading pattern can be formed by the first and second regions at any position in the cavity.

[0032] The injection molding die according to the ninth aspect of the present disclosure may further include a spring that biases the obstacle from the second height toward the first height.

[0033] This configuration allows the obstacle to move between a first height and a second height depending on the force applied to the obstacle.

[0034] The injection molding die according to the tenth aspect of the present disclosure may further include a drive source that moves the obstacle between the first height and the second height.

[0035] This configuration can prevent obstacles from being transferred to the molded product.

[0036] An injection molding apparatus according to an eleventh aspect of the present disclosure includes an injection molding die and an injection molding machine that injects a cellulose-based fiber composite resin.

[0037] With this configuration, a shading pattern can be formed at any position in the cavity formed by the injection molding die.

[0038] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0039] (Embodiment 1) 1A to 1D are schematic perspective views showing one step of the method for producing a molded article 100 according to embodiment 1. Figures 2A and 2B are plan views showing the flow of cellulose fiber composite resin 101 in detail.

[0040] [Molded product composition] The molded article 100 according to the first embodiment is an injection-molded article that uses a cellulose-based fiber composite resin 101 as the injection molding resin. As shown in Fig. 1D, the molded article 100 has a gate mark 112 formed during injection molding, a first region made of the cellulose-based fiber composite resin 101, and a second region 107 formed along the resin merging interface 104 and on both sides of the resin merging interface 104. The resin merging interface 104 starts at a position spaced apart from the gate mark 112 and extends in a direction away from the gate mark 112. The first region 101 and the second region 107 have different color tones.

[0041] The second region 107 is narrower than the first region 101 and has a continuous linear pattern, for example, a linear wood grain pattern.

[0042] [Composition of cellulose fiber composite resin] The cellulose fiber composite resin 101 includes a base resin as a matrix and cellulose fibers. More specifically, 40% or more of the total mass of the cellulose fiber composite resin 101 is composed of cellulose fibers.

[0043] The average aspect ratio of the cellulosic fibers, i.e., the ratio of fiber length to fiber diameter, is 5 or more. The fiber diameter of the cellulosic fibers may be freely selected within a range from the μm order to the nm order. Furthermore, the type of cellulosic fiber may be any material from which cellulose fibers can be extracted, such as softwood, hardwood, or bamboo. For example, pulp, which is the raw material for paper, is used as the cellulosic fiber.

[0044] The cellulosic fibers may be bleached to remove lignin. By using such cellulosic fibers as an injection molding resin, a wide range of colors can be reproduced in the molded article 100.

[0045] The cellulose fiber composite resin 101 constituting the molded article 100 contains, for example, propylene as a base resin and bleached softwood pulp extracted from wood as a cellulose fiber. The softwood pulp is a powder that has been pre-ground to an average diameter of 50 μm and an average length of 300 μm.

[0046] [Manufacturing method for molded products] Here, an example of a method for producing a molded article 100 using a cellulose fiber composite resin 101 will be described with reference to FIGS. 1A to 1D.

[0047] First, the base resin and softwood pulp are mixed and kneaded in a kneader at 190°C to produce an injection-molded resin made of a cellulose-based fiber composite resin. Setting the kneading temperature at 190°C prevents discoloration of the softwood pulp due to heating. Furthermore, because the shear force generated in the kneader causes the fibers to defibrate, the aspect ratio of the softwood pulp in the cellulose-based fiber composite resin after kneading is higher than that of the softwood pulp before kneading.

[0048] 1A, cellulose fiber composite resin 101 is injected from gate 102 inside the mold. Injection molding conditions may be a resin temperature of 180°C or higher and a mold temperature in the range of 20°C to 100°C. In the first embodiment, injection molding is performed with a resin temperature of 200°C, a mold temperature of 60°C, an injection speed of 100 mm / s, a dwell pressure of 80 MPa, and a dwell time of 5 seconds.

[0049] Cellulose-based fiber composite resin 101 flows into cavity R1 (dotted line) formed by a mold from gate 102. An obstacle 103 that protrudes into cavity R1 is placed in the mold at a position separated from gate 102. Cellulose-based fiber composite resin 101 flows toward obstacle 103.

[0050] The obstacle 103 is a member that protrudes from the mold toward the cavity R1 in a direction intersecting the flow direction of the cellulose-based fiber composite resin 101. The shape of the obstacle 103 may be a cylindrical shape, an elliptical cylindrical shape, a polygonal cylindrical shape, or a hollow shape thereof.

[0051] As shown in FIG. 1B, the cellulose fiber composite resin 101 hits an obstacle 103, and the flow of the cellulose fiber composite resin 101 branches into two.

[0052] As shown in FIG. 1C, the branched cellulose fiber composite resin 101 merges at a resin merging interface 104 downstream of an obstacle 103. At the merging point, compression heat is generated due to residual air compression inside the mold, and shear heat is generated due to the resin merging. The compression heat and shear heat thermally modify the cellulose fiber in the composite resin located near the resin merging interface 104, producing furfural, a carbonized cellulose fiber. The production of furfural forms a linear pattern 107 downstream of the obstacle 103 that has a different color tone from the cellulose fiber composite resin 101.

[0053] 1D, a linear pattern 107 is formed downstream of the obstacle 103 along the flow direction of the cellulose fiber composite resin 101. The linear pattern 107 may extend in the direction from the gate 102 toward the obstacle 103.

[0054] As the shading pattern, a linear pattern 107 is formed in a color tone different from that of the first region formed of the cellulose fiber composite resin 101.

[0055] Next, the injection molding resin is hardened, and the molded article 100 is removed from the mold. A gate mark 112 is formed in the removed molded article 100 at the position of the gate 102. The gate mark 112 is a pattern corresponding to the gate 102, and may be a pattern along the outer periphery of the gate 102. The gate mark 112 may also be a whitened pattern along the surface of the molded article 100. Furthermore, a transfer mark 113 may be formed at the position of the obstacle 103. The transfer mark 113 is a transfer shape caused by the obstacle 103 receding. The transfer mark 113 may be a three-dimensional shape that follows the outer periphery of the obstacle 103, or may be a pattern along the surface of the molded article 100.

[0056] In this way, a molded product 100 having a linear pattern 107 is obtained.

[0057] In the above manufacturing method, the number, position, and size of the gates 102 may be set within the range that allows them to be placed inside the mold. The number, position, and size of the obstacles 103 may be set within the range that allows them to be placed inside the mold. The number of obstacles 103 may be greater than the number of gates 102; for example, one gate 102 and multiple obstacles 103 may be provided. In this configuration, it is possible to improve the design freedom of the molded product 100 while suppressing deterioration of filling balance and increase in cost due to an increase in the number of gates 102.

[0058] Here, the mechanism by which the linear pattern 107 is obtained in the manufacturing method of the molded product 100 will be described with reference to FIGS. 2A and 2B.

[0059] As shown in FIG. 2A, the resin that branches into two branches at the obstacle 103 generates an inward flow 201 that flows around the rear of the obstacle 103.

[0060] As shown in FIG. 2B, when inward forces 202 and 203 are continuously applied to the cellulose fiber composite resin 101 that has joined at the resin joining interface 104, furfural is formed and linear patterns 107 are formed.

[0061] Now, the operation of the obstacle 103 during injection molding will be described in more detail with reference to FIGS. 3A to 3D.

[0062] Fig. 3A is a schematic perspective view showing one step in the manufacturing method of the molded product 100. Figs. 3B to 3D are cross-sectional views showing the operation of the obstacle 103 in the molded product 100.

[0063] 3A, cross section A is a cross section of the molded product cut by an infinite plane XY formed by a vector Y pointing from the center of gate 102 toward the center of obstacle 103 and the movement direction X of obstacle 103, and has a normal direction 301. Hereinafter, the movement of obstacle 103 will be described using cross section A.

[0064] As shown in Figure 3B, cellulose fiber composite resin 101 is injected from the cylinder of the molding machine through gate 102 inside the mold and flows toward obstacle 103. Obstacle 103 exists in the molded product, protruding at a first height D1 (>0). First height D1 is smaller than molded product height D0 (>0) (D0 ≥ D1).

[0065] D0-D1, which is the flow path height above the obstacle 103 (on the +X side), may be set within a range that does not impede the flow of the cellulose-based fiber composite resin 101. In consideration of the fluidity of the cellulose-based fiber composite resin 101, it is desirable that the relationship D0-D1≧1 mm be satisfied. Furthermore, the value of the first height D1 may be designed taking into account the overall filling balance of the molded product 100, and the filling performance may be confirmed by flow analysis.

[0066] As shown in FIG. 3C, the cellulose fiber composite resin 101 passing through the obstacle 103 branches into a flow 302 that travels straight without colliding with the obstacle 103 and a flow 303 that collides with the obstacle 103. In the flow 302, a linear pattern 107 is not formed, but in the flow 303, a linear pattern 107 is formed downstream of the obstacle 103.

[0067] When the first height D1 of the obstacle 103 is close to the molded product height D0, the generation of the flow 303 is promoted, and the formation of the linear pattern 107 is promoted.

[0068] As shown in FIG. 3D, when the obstacle 103 is retracted into the mold by the movement amount D1 - D2 and the filling of the cellulose fiber composite resin 101 is completed, the obstacle 103 exists in the molded product in a state of protruding at the second height D2 (≧0). Here, the relationship 0≦D2≦D1 and 0<D1≦D0 holds. By cooling and solidifying the molded product 100 in the illustrated state, the shape of the obstacle 103 at the second height D2 is directly transferred to the molded product 100.

[0069] The second height D2 may be 0% or more and 10% or less of the molded product height D0. With such a configuration, that is, by reducing the second height D2 of the obstacle 103, the shape transfer of the obstacle 103 to the molded product can be suppressed. For example, the second height D2 is 0. In this case, the tip surface shape 304 of the obstacle 103 coincides with the surface of the molded product 100. Therefore, the shape transfer of the obstacle 103 to the molded product is further suppressed, and the transfer trace 113 is a pattern along the surface of the molded product 100.

[0070] Also, the tip surface shape 304 of the obstacle 103 is not particularly limited. Although it is illustrated as a flat surface for simplicity, it may be a curved surface or an inclined surface shape, etc. The tip projected area A1 shown in FIG. 3D is a projection view of the obstacle 103 showing the tip surface shape 304. By reducing the tip projected area A1, the shape transfer of the obstacle 103 to the molded product can be further suppressed.

[0071] Here, referring to FIG. 4, an injection molding apparatus 4,000 for realizing the above manufacturing method will be described.

[0072] FIG. 4 is a schematic cross-sectional view showing the cross-sectional configuration of the injection molding apparatus 400. As shown in FIG.

[0073] As shown in Fig. 4, the injection molding apparatus 400 according to the first embodiment includes an injection molding machine 401, a fixed mold 402, and a movable mold 403. The injection molding machine 401 injects the cellulose fiber composite resin 101 into a cavity defined between the fixed mold 402 and the movable mold 403. The fixed mold 402 and the movable mold 403 fit together to form a cavity R1 into which the injected cellulose fiber composite resin 101 flows. The fixed mold 402 and the movable mold 403 are collectively referred to as an injection mold 440.

[0074] The injection molding die 440 further includes an obstacle 103 and a spring 404 supporting the obstacle 103. The obstacle 103 penetrates the fixed die 402 or the movable die 403 and is movable between a first height D1 protruding into the cavity R1 and a second height D2 retracted from the first height D1 into the injection molding die 440. The obstacle 103 includes a shaft 103A and a base 103B. The shaft 103A and the base 103B may be integrally formed or may be fastened together with a bolt or the like. The spring 404 is provided behind the base 103B and biases the obstacle 103 from the second height D2 toward the first height D1. In other words, the base 103B receives the reaction force of the spring 404. A distance D3 behind the base 103B is the maximum movement amount of the obstacle 103.

[0075] The obstacles 103 may be arranged in any location and in any number as long as they can protrude into the cavity R1.

[0076] Next, the operation of injection molding apparatus 400 will be described with reference to FIGS. 5A to 5C.

[0077] 5A to 5C are cross-sectional views showing the operation of obstacle 103 provided in injection molding die 440 of injection molding apparatus 400. FIG.

[0078] As shown in FIG. 5A , when cellulose-based fiber composite resin 101 is injected from gate 102 via injection molding machine 401, flow 501 toward obstacle 103 is generated. As a result, injection pressure is applied to the side of obstacle 103 along flow 501. Over time, the area around obstacle 103 is filled with cellulose-based fiber composite resin 101, and injection pressure is applied to the entire protruding surface of obstacle 103. Specifically, injection pressure 502 acts on tip surface shape 304 of obstacle 103, and injection pressure 503 acts on the side of obstacle 103. If the difference between molded product height D0 and first height D1 is large, more cellulose-based fiber composite resin 101 is present above tip surface shape 304 of obstacle 103, and injection pressure 502 increases. In this state, the obstacle 103 is pushed with a larger force, making it more likely to retreat into the mold.

[0079] 5B shows a state in which no injection pressure is acting on obstacle 103. If the natural length of spring 404 is D4, spring 404 contracts to a length D5 by supporting obstacle 103. In this case, using spring constant k, spring reaction force F1 is calculated as k × (D4 - D5).

[0080] 5C shows a state in which an injection pressure M1 is acting on the obstacle 103. The injection pressure M1 is set to approximately 400 to 900 kgf / cm2, taking into consideration the moldability and transferability of the cellulose fiber composite resin 101. 2 The force with which the obstacle 103 is pushed by the injection pressure is the product of the injection pressure M1 and the tip projected area A1 (FIG. 3D). If the force of the injection pressure M1 x A1 is greater than the spring reaction force F1, the obstacle 103 retreats from the cavity R1.

[0081] When the obstacle 103 is retracting, an increase in the amount of cellulose-based fiber composite resin 101 flowing around the obstacle 103 increases, increasing the injection pressure M1. Furthermore, the spring 404 contracts, increasing the spring reaction force. If the minimum length of the spring 404, i.e., the length of the spring 404 when the base 103B is in contact with the movable mold 403, is D6, the maximum spring reaction force F2 is calculated by k × (D4 - D6). When the force M1 × A1 pushing the obstacle 103 is sufficiently greater than the spring reaction force F2 (M1 × A1 >> F2), the obstacle 103 can retract until the base 103B comes into contact with the movable mold 403. In this state, the obstacle 103 has a second height D2.

[0082] 5B and 5C, the amount of movement D1-D2 is equal to the distance D3 behind the base 103B. By adjusting the distance D3 behind the base 103B, the amount of movement D1-D2 of the obstacle 103 can be adjusted. This makes it possible to control the second height D2 at which the obstacle 103 transfers its shape to the molded product.

[0083] [effect] The molded article 100, the manufacturing method for the molded article 100, the injection molding die 440, and the injection molding apparatus 400 according to the first embodiment can provide the following effects.

[0084] The molded article 100 according to the first embodiment is an injection-molded article made of a cellulose-based fiber composite resin 101. The molded article 100 has a gate mark 112 made during injection molding, a first region made of the cellulose-based fiber composite resin 101, and a second region 107 formed along a resin merging interface 104. The resin merging interface 104 starts at a position spaced apart from the gate mark 112 and extends in a direction away from the gate mark 112. The first region 101 and the second region 107 have different color tones.

[0085] With this configuration, the linear pattern 107 can be formed at any position on the molded product 100 away from the gate mark 112.

[0086] In the molded product 100 according to the first embodiment, the second regions 107 are narrower than the first regions 101 and have a linear pattern.

[0087] With this configuration, a linear pattern 107 can be formed.

[0088] In the molded article 100 according to the first embodiment, the second region 107 contains furfural, which is a cellulosic fiber in a semi-carbonized state.

[0089] This configuration allows the molded product 100 to have a linear pattern 107 that has natural discoloration or uneven color that occurs as wood ages and grows. Therefore, the molded product 100 can achieve an impression that is close to that of real wood.

[0090] The method for manufacturing the molded product 100 according to the first embodiment includes arranging an obstacle 103 that is spaced from the gate 102 and protrudes at a first height D1 toward a cavity R1 between the molds 402 and 403. The manufacturing method also includes injection molding a cellulose-based fiber composite resin 101 from the gate 102 into the cavity R1. The manufacturing method also includes forming a first region using the cellulose-based fiber composite resin 101, and forming a second region 107 that has a different color tone from the first region along a resin merging interface 104 that extends downstream from the obstacle 103 and extends across both sides of the resin merging interface 104. The manufacturing method also includes retracting the obstacle 103 into the molds 402 and 403 to a second height D2 that is smaller than the first height D1.

[0091] In this manner, the flow of the cellulose fiber composite resin 101 is obstructed by the protruding obstacle 103, causing the resin to branch upstream of the obstacle 103 and merge downstream. This allows the formation of a linear pattern 107 originating downstream of the obstacle 103. By arranging the obstacle 103, the linear pattern 107 can be formed at any position on the molded product 100. Furthermore, by subsequently retracting the obstacle 103 to the second height D2, the shape of the obstacle 103 can be prevented from being transferred to the molded product 100.

[0092] In the method for manufacturing the molded product 100 according to the first embodiment, the injection pressure M1 of the cellulose fiber composite resin 101 causes the obstacle 103 to retreat from the first height D1 to the second height D2.

[0093] By using such a method, even without using a complex mechanism, the obstacle 103 can be retracted after the linear pattern 107 is formed, thereby preventing the obstacle 103 from being transferred to the molded product 100.

[0094] The injection molding die 440 according to embodiment 1 has dies 402, 403 that form a cavity R1, and an obstacle 103 that is movable between a first height D1 that protrudes into the cavity R1 and a second height D2 that is recessed inside the dies 402, 403.

[0095] With this configuration, the obstacles 103 at the first height D1 cause the cellulose-based fiber composite resin 101 to branch and merge to form linear patterns 107. Furthermore, the obstacles 103 at the second height D2 allow more cellulose-based fiber composite resin 101 to exist above the tip surface shapes 304 of the obstacles 103, thereby preventing the shape of the obstacles 103 from being transferred to the molded product 100.

[0096] The injection molding die 440 according to the first embodiment further includes a spring 404 that biases the obstacle 103 from the second height D2 toward the first height D1.

[0097] With this configuration, when the force applied to the obstacle 103 at the first height D1 is smaller than the spring reaction force F1, the obstacle 103 can maintain the first height D1. As the force applied to the obstacle 103 increases, the obstacle 103 retreats from the first height D1 to the second height D2.

[0098] The injection molding apparatus 400 according to the first embodiment includes an injection mold 440 and an injection molding machine 401 that injects the cellulose-based fiber composite resin 101 .

[0099] With this configuration, the linear pattern 107 can be formed at any position on the molded product 100 while preventing the shape of the obstacle 103 from being transferred to the molded product 100.

[0100] In the first embodiment, an example in which propylene is used as the base resin has been described, but the present invention is not limited to this. Any resin can be used as long as it can be used to form a composite resin without carbonizing the cellulosic fibers in the kneading step.

[0101] In the first embodiment, an example has been described in which the first height D1 of the obstacle 103 is smaller than the molded product height D0, but this is not limiting. For example, the first height D1 and the molded product height D0 may be equal. In this case, the flow 302 that does not collide with the obstacle 103 does not occur, and only the flow 303 that collides with the obstacle 103 occurs.

[0102] (Embodiment 2) An injection molding die 640 and an injection molding apparatus 600 according to a second embodiment of the present disclosure will be described with reference to Figures 6, 7A, and 7B. Note that in the second embodiment, differences from the first embodiment will be mainly described. In the second embodiment, the same or equivalent configurations as those in the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.

[0103] Fig. 6 is a schematic cross-sectional view showing a cross-sectional configuration of an injection molding apparatus according to embodiment 2. Figs. 7A and 7B are schematic views showing the operation of an obstacle provided in a mold of the injection molding apparatus.

[0104] The second embodiment differs from the first embodiment in that the injection molding apparatus 600 has a driving source 601 instead of the spring 404 .

[0105] As shown in FIG. 6, the injection molding apparatus 600 includes an injection molding machine 401 and an injection mold 640. The injection mold 640 further includes an obstacle 103 and a drive source 601 that supports the obstacle 103. The drive source 601 is provided behind a base 103B and supports the obstacle 103 so that the obstacle 103 can move between a first height D1 and a second height D2. More specifically, the drive source 601 is connected to the base 103B via a holder component 602 and moves the obstacle 103 in a drive direction 603. A distance D7 behind the holder component 602 is the maximum movement distance of the obstacle 103. For example, a hydraulic or pneumatic cylinder may be used as the drive source 601.

[0106] 7A, cellulose fiber composite resin 101 is injected from gate 102 inside molds 402 and 403, generating resin flow 501 toward obstacle 103. At this time, driving source 601 continues to push obstacle 103 in the direction of extrusion force F3. Therefore, holder component 602 connected to obstacle 103 abuts against flat surface 702 of movable mold 403, thereby maintaining first height D1 of obstacle 103 within molded product 610. Extrusion force F3 of driving source 601 is greater than the combined force of the injection pressure, the weight of obstacle 103, and sliding resistance.

[0107] 7A, as time passes, the obstacle 103 is filled with the cellulose-based fiber composite resin 101. In this state, the driving source 601 continues to pull the obstacle 103 in the direction of the pulling force F4. The obstacle 103 is pulled into the movable mold 403, and the holder part 602 abuts against the flat surface 704 of the movable mold 403, thereby maintaining the second height D2 of the obstacle 103 within the molded product 610.

[0108] 7A and 7B, the movement amount D1-D2 of the obstacle 103 can be adjusted by adjusting the distance D7 behind the holder part 602. This makes it possible to control the second height D2 at which the obstacle 103 transfers its shape to the molded product.

[0109] [effect] The manufacturing method of molded product 610 and injection mold 640 according to the second embodiment can provide the following effects.

[0110] In the method for manufacturing a molded product 610 according to the second embodiment, the obstacle 103 is moved back from the first height D1 to the second height D2 by a driving source 601 connected to the obstacle 103.

[0111] By using this method, after the linear pattern 107 is formed, the obstacle 103 is retracted, thereby preventing the obstacle 103 from being transferred to the molded product 100.

[0112] The injection molding die 640 according to the first embodiment further includes a driving source 601 that moves the obstacle 103 between the first height D1 and the second height D2.

[0113] With this configuration, after the linear pattern 107 is formed, the obstacle 103 is retracted, thereby preventing the obstacle 103 from being transferred to the molded product 100.

[0114] In the second embodiment, an example has been described in which the operation of the driving source 601 is controlled by the holder part 602 abutting against the flat surfaces 702 and 704, but the present invention is not limited to this. The driving source 601 itself may have a position control mechanism, and the amount of movement D1-D2 may be freely adjusted by position control. Furthermore, the timing of the movement of the driving source 601 may be freely controlled by an electric signal, and therefore the timing of the movement of the obstacle 103 can be freely controlled.

[0115] (Embodiment 3) A molded article 801 according to a third embodiment of the present disclosure will be described with reference to Figures 8A to 8F and 9. Note that in the third embodiment, differences from the first embodiment will be mainly described. In the third embodiment, the same or equivalent configurations as those in the first embodiment will be assigned the same reference numerals, and redundant description will be omitted.

[0116] Fig. 8A is a perspective view showing a molded product 801 and an obstacle 803 according to embodiment 3. Fig. 8B is a perspective view showing a tip portion of obstacle 803 shown in Fig. 8A. Figs. 8C to 8F are plan views showing one step of a method for manufacturing molded product 801 according to embodiment 3. Fig. 9 is a photograph showing a linear pattern on molded product 801.

[0117] The third embodiment differs from the first embodiment in that it has a molded product 801 that is different from molded product 100 and an obstacle 803 that is different from obstacle 103.

[0118] 8A, the molded product 801 has a bowl shape and is provided with four obstacles 803.

[0119] As shown in FIG. 8B, the obstacle 803 is cylindrical, and the curved shape 803A at the tip has the same shape as the curved shape of the surface of the molded product 801.

[0120] As shown in Fig. 8C, the third embodiment employs four gates 802. Molten resin 805 injected and flowing in from each gate 802 spreads out in a circular shape, and a flow front 806 is positioned just before reaching an obstacle 803. The flow front 806 is the boundary at the leading edge of the flow of the molten resin 805. Note that, since the third embodiment employs four gates 802, a resin junction 807 is formed between the gates.

[0121] 8D, during injection, the obstacle 803 protrudes into the cavity between the molds. Although not shown, the obstacle 803 is supported by the spring 404 or the driving source 601.

[0122] As shown in Fig. 8E, molten resin 805 that has reached obstacle 803 (Fig. 8C) branches into two at obstacle 803 and merges along resin merging interface 804 at the rear, forming linear pattern 809. Completed molded product 801 has a shading pattern made up of resin merging portion 807 between gates 802 (Fig. 8C) and linear pattern 809 behind obstacle 803. Furthermore, in molded product 801, gate mark 812 is formed at the position of gate 802, and transfer mark 813 of obstacle 803 is formed at the position of obstacle 803.

[0123] As shown in Figure 8F, during filling, resin flows into flow gap 808 above obstacle 803. The injection pressure caused by the flow of resin is applied to the tip, causing obstacle 803 to recede. Because curved shape 803A of the tip of obstacle 803 is the same shape as the surface of molded product 801, as shown in the figure, after receding, the surface of molded product 801 and curved shape 803A of the tip of obstacle 803 match. When cooled and solidified in this state, a transfer mark 813 (Figure 9) having a shape corresponding to obstacle 803 is formed on the surface of molded product 801. Transfer mark 813 is a pattern formed along the surface of molded product 801. Transfer mark 813 may have a color tone different from its surroundings.

[0124] As shown in FIG. 9, a linear pattern 809 and transfer marks 813 are formed on a molded product 801.

[0125] In the molded product 801 according to the third embodiment, a transfer mark 813 is formed between the gate mark 812 and the starting point of the resin joining interface 804 during injection molding.

[0126] With this configuration, the cellulose fiber composite resin 101 forms a linear pattern 809 downstream of the transfer trace 813. Therefore, the linear pattern 809 can be formed at any position on the molded product 100 by arranging the obstacle 803.

[0127] In the third embodiment, an example in which there are four gates 802 and four obstacles 803 has been described, but the present invention is not limited to this. The number of gates 802 and obstacles 803 may be set arbitrarily within the range in which they can be arranged in the mold. Furthermore, the number of gates 802 and the number of obstacles 803 may differ.

[0128] In the third embodiment, an example has been described in which the transfer mark 813 is a pattern formed along the surface of the molded article 801, but the invention is not limited to this. The transfer mark 813 may have a three-dimensional shape such as a concave or convex shape, and may protrude or recess from the surface of the molded article 801.

[0129] Although the present disclosure has been fully described in connection with the preferred embodiments with reference to the accompanying drawings, various changes and modifications will be apparent to those skilled in the art, and such changes and modifications are to be understood as being included within the scope of the present disclosure as defined by the appended claims unless they depart therefrom. [Industrial Applicability]

[0130] The molded article, its manufacturing method, injection molding die, and molding device disclosed herein are useful for imparting patterns and coloring to molded articles. The molded article disclosed herein can reproduce shading patterns in a cycle equivalent to injection molding. For example, reproducing wood grain patterns can replace products that previously required time-consuming wood carving processes, and can also be used in parts where real wood cannot be used, such as in wet areas, where durability issues have made it difficult to use it. Furthermore, because molding can be done with a single gate, this also reduces resin material waste, contributing to the environment. [Explanation of symbols]

[0131] 100 Molded products 101 Cellulose-based fiber composite resin Gate 102 112 Gate Remains 103 Obstacles 113 Transcription marks 104 Resin confluence interface 107 Linear Pattern 304 Tip shape 401 Injection molding machine 402 Fixed mold 403 Movable mold 404 Spring 440 Injection mold 601 Drive source 602 Holder parts 801 Molded products Gate 802 803 Obstacles 813 Transcription marks 805 Molten Resin 806 Flow Front 807 Resin junction 809 Linear pattern

Claims

1. disposing an obstacle spaced from the gate and projecting at a first height toward the cavity between the molds; Injecting a cellulose-based fiber composite resin into the cavity through the gate to form a first region made of the cellulose-based fiber composite resin, and forming a second region having a color tone different from that of the first region along a resin merging interface extending downstream from the obstacle and on both sides of the resin merging interface; retracting the obstacle into the mold to a second height less than the first height; A method for producing a molded article, comprising:

2. The method for manufacturing a molded product according to claim 1 , wherein the obstacle is retracted from the first height to the second height by the injection pressure of the cellulose-based fiber composite resin.

3. The method for manufacturing a molded product according to claim 1 , wherein the obstacle is retracted from the first height to the second height by a drive source connected to the obstacle.

4. The method for manufacturing a molded product according to claim 1 or 2, wherein the obstacle is biased from the second height toward the first height by a spring.

5. A method for manufacturing a molded product described in any one of claims 1 to 4, wherein a transfer mark is formed between a gate mark corresponding to the gate and the starting point of the resin confluence interface.

6. A method for manufacturing a molded product described in any one of claims 1 to 5, wherein the second region is narrower than the first region and has a linear pattern.

7. A method for manufacturing a molded product as described in Claim 6, wherein the second region includes a carbonized cellulosic fiber.

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