Foaming tank for foaming synthetic resin and method for manufacturing vehicle interior core material

Abstract

To provide a foaming tank for foaming a synthetic resin capable of suppressing voids generated on an interface in molding a foam by simultaneously foaming two or more kinds of foaming synthetic resins, and a method for manufacturing an interior core material for a vehicle using the foaming tank.SOLUTION: The foaming tank 20 is equipped with a partition 25 for partitioning the bottom surface part 21 into at least two or more partition regions 2627 and a liquid surface adjusting part for aligning the liquid surface heights 11a and 12a of a plurality of urethane raw materials 11a and 12a in a liquid material state when the urethane raw materials H1 and H2 different in foaming magnification are injected in the respective partition regions 2627. The height L1 of the partition 25 is set by the liquid level adjusting portion to have a relationship in which the plurality of urethane raw materials 11a and 12a injected for each of the partitioned regions 2627 are not mixed with each other at the boundary of the partitioned regions 2627 in a liquid material state immediately after the injection, and to have a relationship in which the plurality of urethane raw materials 11a and 12a are in contact with each other at the interface 14 when the plurality of urethane raw materials LA and LA rise in a cream state and start a foaming reaction.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a foaming tank for foaming synthetic resins and a method for manufacturing a vehicle interior core material. [Background technology]

[0002] Various types of core materials for vehicle interiors have been known. For example, polyurethane foam is used as the core material for vehicle ceiling interiors. This polyurethane foam is obtained by injecting a urethane concentrate into a box-shaped foaming tank with an open top, and then foaming upward through internal foaming of the urethane resin to form a solid.

[0003] Meanwhile, vehicle interior core materials have different requirements for shape, feel, weight, breathability, etc. depending on the location in the vehicle interior where they are installed. To meet these requirements, vehicle interior core materials that integrate two or more types of polyurethane foam have been developed. For example, Patent Document 1 discloses a method for manufacturing vehicle interior parts made of urethane foam. This manufacturing method involves injecting urethane concentrates with different properties into spaces separated by partition members and foaming them, and includes a step of removing the partition members during foaming.

[0004] Patent Document 2 discloses a method for manufacturing a vehicle interior core material made of polyurethane foam. In this manufacturing method, partitions are installed on the bottom of a foaming tank to create compartments so that urethane stock solutions with different properties do not mix immediately after being poured in, and different urethane stock solutions with different properties are poured into each compartment and foamed simultaneously. The height of the partitions is set so that the urethane stock solutions come into contact with each other at their interfaces when they foam into a sol state, eliminating the need to remove the partitions during foaming, thereby reducing labor costs. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 135275 [Patent Document 2] Japanese Patent Publication No. 2022-29571 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when removing a tall partition member during foaming, as in the manufacturing method described in Patent Document 1, additional labor and dedicated equipment are required to remove the partition member. Furthermore, when removing the partition member, shear stress acts on small bubbles that contact the side of the partition member, easily generating large bubbles called voids. Generally, when simultaneously foaming urethane concentrates with different raw material formulations, the amounts of each urethane concentrate are adjusted so that the liquid level of the urethane concentrate with a relatively high foaming ratio is kept low. In this case, even if a low partition is used as in the manufacturing method described in Patent Document 2, the difference between the liquid level and the partition height of the urethane concentrate with a relatively low foaming ratio, which has a relatively low liquid level, becomes large. As a result, shear stress acts on small bubbles that contact the side of the partition during the foaming reaction, easily generating voids. In other words, whether or not either of the above partitions is used, there is a concern that voids will occur at the interface, leading to a deterioration in product quality. Therefore, further improvements to suppress void generation at the interface are needed.

[0007] The present invention has been made in view of the above points, and the problem to be solved by the present invention is to provide a foaming tank for foaming synthetic resins that can suppress the generation of voids at the interface when molding a foam by simultaneously foaming two or more types of foamed synthetic resins, and a method for manufacturing an interior core material for vehicles using the foaming tank. [Means for solving the problem]

[0008] One feature of a foaming tank for foaming synthetic resins that solves the above-mentioned problems is a foaming tank for foaming synthetic resins that is box-shaped with an opening at the top, into which multiple urethane stock solutions with different blending ratios of raw materials are separately injected and foamed simultaneously, and that includes a partition that is installed on the bottom of the foaming tank and divides the bottom into at least two or more compartmentalized areas, and a liquid level adjustment unit that equalizes the liquid level of the multiple urethane stock solutions in their liquid raw material state when the multiple urethane stock solutions with different foaming ratios are injected into each of the compartmentalized areas, respectively, and the heights of the partitions are set by the liquid level adjustment unit so that the multiple urethane stock solutions injected into each compartment do not mix with each other at the boundaries of the compartmentalized areas in their liquid raw material state immediately after injection, and so that the multiple urethane stock solutions come into contact with each other at their interfaces when they become creamy, rise, and begin the foaming reaction.

[0009] One feature and advantage of the above configuration is that the foaming tank includes a partition disposed on the bottom surface to define multiple compartments, and a liquid level adjuster that evens out the liquid levels of the multiple urethane stock solutions in their liquid raw material state. Each compartment is separately injected with multiple urethane stock solutions with different properties due to different formulations of the raw materials used. The height of the partition disposed on the bottom surface of the foaming tank is set by the liquid level adjuster so that the multiple urethane stock solutions injected into each compartment do not mix with each other at the boundaries of the compartments in their liquid raw material state immediately after injection, and so that the multiple urethane stock solutions contact each other at their interfaces when they become creamy and rise to begin the foaming reaction. The viscosity of each urethane resin increases as the foaming reaction progresses. However, in simultaneous foaming of urethane stock solutions with different properties, the greater the difference in viscosity between the urethane resins when their interfaces reach the top of the partition after foaming begins, the more likely shear stress will act at the interface and cause voids. Therefore, the height of the partition is set so that the interface reaches the top of the partition before the difference in viscosity between the urethane resins becomes large. Therefore, the occurrence of voids at the interface during the foaming stage can be suppressed.

[0010] Furthermore, by providing the foaming tank with a liquid level adjusting unit, the liquid level of the multiple urethane stock solutions can be made uniform when they are injected into each compartment. Because the multiple urethane stock solutions have different foaming ratios, the difference in the rise speed of the urethane resin increases as they rise. The greater this difference in speed, the greater the shear stress at the interface, making it more likely that voids will form. Therefore, by making the liquid level of the multiple urethane stock solutions uniform, the difference in the rise speed when the liquid levels of the multiple urethane stock solutions reach the top of the partition can be reduced. This reduces the occurrence of voids at the interface during the foaming stage, improving the quality of the vehicle interior core material.

[0011] The foaming tank for foaming synthetic resin may be configured so that the liquid level adjusting section has a raising member that is placed on the bottom surface and raises the liquid level of the urethane stock solution in a liquid raw material state, at least in the partitioned area into which the urethane stock solution having a relatively high foaming ratio is poured.

[0012] One feature and advantage of the above configuration is that a bulking member is placed on the bottom surface of at least the partitioned area into which a urethane stock solution with a relatively high expansion ratio is poured. The liquid level of the urethane stock solution with a relatively high expansion ratio in its liquid raw material state rises depending on the volume of the bulking member. This allows the liquid level of the urethane stock solution with a relatively high expansion ratio to be closer to the height of the partition. Furthermore, by placing the bulking member over the entire surface or part of the corresponding partitioned area, the liquid level can be adjusted depending on the amount of urethane stock solution poured. In other words, the liquid level of multiple urethane stock solutions in their liquid raw material state can be made uniform. Therefore, the occurrence of voids at the interface during the foaming stage can be suppressed.

[0013] The foaming tank for foaming synthetic resins may be configured to have, as the raising member, a bottom-raising member that is placed on the bottom portion in at least the partitioned area into which a urethane stock solution having a relatively high foaming ratio is poured, and that raises the bottom height of the bottom portion, thereby increasing the liquid level of the urethane stock solution in a liquid raw material state.

[0014] One feature and advantage of the above configuration is that a bottom-raising member is disposed in at least the compartment area into which the urethane concentrate with a relatively high expansion ratio is poured, to raise the bottom surface height of the bottom portion. For example, by disposing the bottom-raising member over the entire surface of the compartment area, the liquid level of the urethane concentrate with a relatively high expansion ratio can be raised according to the thickness of the bottom-raising member, and made to be the same as the liquid level of the other urethane concentrates.

[0015] In the foaming tank for foaming synthetic resin, the partition and the bottom raising member may be integrally formed.

[0016] One feature and advantage of the above configuration is that the partition and the bottom-raising member placed in the foaming tank are configured as an integrated member. This reduces the number of steps required to form and place the partition and the bottom-raising member. In addition, since the partition is integrated with the bottom-raising member, it is easy to fix the position of the partition, and the position and posture of the placed partition can be stabilized.

[0017] The foaming tank for foaming synthetic resin may be configured so that the liquid level adjusting section has a recess provided in the bottom surface of the partitioned area into which a urethane stock solution having a relatively low foaming ratio is poured, for lowering the liquid level of the urethane stock solution in a liquid raw material state.

[0018] One feature and advantage of the above configuration is that, at least in the compartment where a urethane stock solution with a relatively low foaming ratio is poured, recesses are provided on the bottom surface to lower the liquid level of the urethane stock solution in its liquid raw material state. By appropriately changing the size and number of recesses, the liquid level can be adjusted according to the amount of urethane stock solution poured. In other words, the liquid level of multiple urethane stock solutions with different foaming ratios can be made uniform. Therefore, the occurrence of voids at the interface during the foaming stage can be suppressed.

[0019] In the foaming tank for foaming synthetic resin, the partition may be configured so that the surface in contact with the plurality of urethane concentrate solutions has a continuous, smooth curve in a cross section intersecting the boundary of the partitioned area.

[0020] One feature and advantage of the above configuration is that the partition at the bottom of the foaming tank has a continuous, smooth curved surface that comes into contact with multiple urethane concentrate solutions in a cross-sectional view intersecting the boundaries of the partitioned areas. When urethane concentrate solutions are foamed in a partitioned space, shear stress acts on the wall surfaces or partition sides along the upward direction, making it easy for voids to form. Specifically, small bubbles in contact with the wall surfaces or partition sides are stretched by shear stress and can join together to form voids. Therefore, by making the cross-sectional shape of the surface that comes into contact with the partition and the urethane concentrate solution a continuous, smooth curved surface, the small bubbles rise away from the partition surfaces before joining together, thereby suppressing the formation of voids.

[0021] A method for manufacturing a vehicle interior core material that solves the above-mentioned problems includes a stock solution preparation step of preparing multiple urethane stock solutions, each with a different blending ratio of raw materials, as urethane stock solutions for molding polyurethane foam; a stock solution injection step of pouring the multiple urethane stock solutions separately into a foaming tank that is box-shaped and open at the top, with partitions erected on the bottom to create at least two or more optional compartments; and a foam molding step of molding the multiple urethane stock solutions so that they foam upward and combine with each other to form an integrated solid.The foaming tank has a liquid level adjustment unit that equalizes the liquid levels of the multiple urethane stock solutions in their liquid raw material state when the multiple urethane stock solutions with different expansion ratios are injected into each of the compartments, and the heights of the partitions are set by the liquid level adjustment unit so that the multiple urethane stock solutions do not mix with each other in their liquid raw material state immediately after injection, and so that the multiple urethane stock solutions come into contact with each other at their interfaces when they become creamy and rise to begin the foaming reaction.

[0022] One feature and advantage of the above process is that in the liquid injection step, multiple urethane stock solutions with different properties due to different formulations of raw materials are injected into compartments separated by partitions on the bottom of the foaming tank. The foaming tank has a liquid level adjustment unit that aligns the liquid levels of the multiple urethane stock solutions with different expansion ratios in their liquid raw material state. The height of the partition is set by the liquid level adjustment unit so that the multiple urethane stock solutions injected into each compartment do not mix with each other at the boundaries of the compartments in their liquid raw material state immediately after injection, and so that the multiple urethane stock solutions contact each other at their interfaces when they become creamy and rise to begin the foaming reaction. In simultaneous foaming of urethane stock solutions with different properties, the greater the difference in viscosity of the urethane resins when the interface reaches the top of the partition after foaming begins, the more likely shear stress will act at the interface and cause voids to occur. Therefore, the height of the partition is set so that the interface reaches the top of the partition before the difference in viscosity between the different urethane resins becomes large during the foam molding process. This prevents voids from occurring at the interface.

[0023] Furthermore, because the foaming ratios of the multiple urethane stock solutions are different, the difference in the rise speed of the urethane resin increases as it rises. The greater this difference in speed, the greater the shear stress at the interface, making it more likely for voids to form. Therefore, by aligning the liquid levels of the multiple urethane stock solutions in their liquid raw material state during the stock solution injection process, the difference in the rise speeds of the multiple urethane stock solutions when their liquid levels reach the top of the partition can be reduced. This reduces the occurrence of voids at the interface, improving the quality of the vehicle interior core material.

[0024] In the manufacturing process for the above-mentioned vehicle interior core material, the liquid level adjustment section may be a raising member placed on the bottom surface section, which raises the liquid level of the urethane concentrate in its liquid raw material state at least in the compartment area where the urethane concentrate with a relatively high foaming ratio is injected.

[0025] One feature and advantage of the above process is that a bulking member is placed on the bottom surface of at least the partitioned area into which a urethane stock solution with a relatively high expansion ratio is poured. The liquid level of the urethane stock solution with a relatively high expansion ratio in its liquid raw material state rises depending on the volume of the bulking member. This allows the liquid level of the urethane stock solution with a relatively high expansion ratio in the liquid raw material injection process to be closer to the height of the partition. Furthermore, by placing the bulking member over the entire surface or part of the corresponding partitioned area, the liquid level can be adjusted according to the amount of urethane stock solution poured. In other words, the liquid level of multiple urethane stock solutions in their liquid raw material state can be made uniform. Therefore, the occurrence of voids at the interface can be suppressed.

[0026] In the manufacturing process for the above-mentioned vehicle interior core material, the liquid level adjustment section may be such that the liquid level of the urethane concentrate in its liquid raw material state is increased by arranging a bottom-raising member that raises the bottom height of the bottom section in at least the compartment area into which the urethane concentrate with a relatively high foaming ratio is injected.

[0027] One feature and advantage of the above process is that, among the partitioned regions provided on the bottom surface of the foaming tank, a bottom-raising member is arranged in the partitioned region into which a urethane stock solution with a relatively high foaming ratio is poured, thereby raising the bottom height of the bottom portion. For example, by arranging the bottom-raising member over the entire surface of the corresponding partitioned region, the liquid level of the urethane stock solution with a relatively high foaming ratio in a liquid raw material state rises according to the thickness of the bottom-raising member, and can be made equal to the liquid level of the other urethane stock solutions.

[0028] In the manufacturing process of the vehicle interior core material, the partition and the bottom-raising member may be integrally formed and placed on the bottom surface portion.

[0029] One feature and advantage of the above process is that the partition and the bottom-raising member are constructed as an integrated member and placed on the bottom surface. This reduces the number of steps required to form and place the partition and the bottom-raising member. Furthermore, because the partition is integrated with the bottom-raising member, it is easy to fix the position of the partition, and the position and posture of the placed partition can be stabilized.

[0030] In the manufacturing process of the above-mentioned vehicle interior core material, the liquid level adjustment section may be a recess provided on the bottom surface section that lowers the liquid level of the urethane concentrate in its liquid raw material state, at least in the compartment area where the urethane concentrate with a relatively low foaming ratio is injected.

[0031] One feature and advantage of the above process is that a recess is provided on the bottom surface to lower the liquid level of the urethane stock solution in a liquid raw material state, at least in the partitioned area where the urethane stock solution with a relatively low expansion ratio is injected. This lowers the liquid level of the urethane stock solution with a relatively low expansion ratio in the liquid raw material state during the liquid injection process, making it possible to make it uniform with the liquid level of the other urethane stock solutions in their liquid raw material states. In other words, it is possible to make the liquid level of multiple urethane stock solutions uniform in their liquid raw material states. This makes it possible to suppress the occurrence of voids at the interface.

[0032] In the manufacturing process for the vehicle interior core material, the partition may have a surface that comes into contact with the plurality of urethane concentrate solutions that has a continuous, smooth curve in a cross section that intersects with the boundary of the partitioned region.

[0033] One feature and advantage of the above process is that the partitions at the bottom of the foaming tank have a continuous, smoothly curved surface that comes into contact with multiple urethane concentrate solutions when viewed in cross section intersecting the boundaries of the partitioned areas. When urethane concentrate solutions are foamed in a partitioned space, shear stress acts on the wall surfaces or partition sides that are aligned with the upward direction, making it easy for voids to form. Specifically, small bubbles that come into contact with the wall surfaces or partition sides are stretched by shear stress and can join together, creating voids. Therefore, by installing partitions with a cross section where the partitions come into contact with the urethane concentrate solutions that has a continuous, smoothly curved cross section, small bubbles rise away from the partition surfaces before joining together during the foam molding process, preventing void formation. [Effects of the Invention]

[0034] By adopting the above-mentioned configuration, the present invention can provide a foaming tank for foaming synthetic resins that can suppress the generation of voids at the interface when molding a foam by simultaneously foaming two or more types of foamed synthetic resins, and a method for manufacturing an interior core material for a vehicle using the foaming tank. [Brief explanation of the drawings]

[0035] [Figure 1] 1 is a cross-sectional view schematically illustrating a configuration of a ceiling interior material according to an embodiment. [Figure 2] FIG. 2 is a schematic top view of a core material according to an embodiment. [Figure 3] FIG. 2 is a plan view of the foaming tank according to the embodiment. [Figure 4] FIG. 2 is a schematic diagram showing the state immediately after the urethane stock solution is poured into the foaming tank according to the embodiment. [Figure 5] FIG. 2 is a schematic diagram of a foam molding step according to an embodiment. [Figure 6] 10 is a diagram showing the relationship between the partition according to the embodiment and the liquid level of the urethane concentrate in a liquid raw material state. FIG. [Figure 7] 10 is a diagram showing the relationship between the partition according to the embodiment and the liquid level of the urethane concentrate after foaming starts. FIG. [Figure 8] 10A and 10B are diagrams schematically illustrating a partition and a bottom-raising member according to another embodiment. [Figure 9] 10A and 10B are diagrams schematically illustrating an example of a liquid level adjusting section (raising member) according to another embodiment. [Figure 10] 10A and 10B are diagrams schematically showing examples of liquid level adjusting portions (recesses) according to other embodiments. [Figure 11] FIG. 10 is a cross-sectional view schematically showing a partition according to another embodiment. [Figure 12] 10A and 10B are diagrams illustrating the relationship between the cross-sectional shape of a partition and the occurrence of voids. [Figure 13] 10 is a diagram showing the relationship between the partition and the liquid level of the urethane concentrate in a liquid raw material state according to Comparative Example 1. FIG. [Figure 14] 10 is a diagram showing the relationship between the partition and the liquid level of the urethane concentrate in a liquid raw material state according to Comparative Example 2. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0036] An embodiment of the present invention will be described below with reference to the drawings. A vehicle has a ceiling panel made of steel plate as its roof. The vehicle interior core material according to this embodiment is a core material 6 of a ceiling interior material 10 that is attached to the interior side of the ceiling panel. As shown in FIG. 1, the ceiling interior material 10 is formed by heating and pressure molding a laminate having a base material layer 2 including the core material 6, a backing material 3, and a skin material 4, for example, by a heat press.

[0037] The core material 6 is provided to maintain the shape and rigidity of the ceiling interior material 10, and is molded into a planar shape that conforms to the surface of the ceiling panel. As shown in FIG. 2, the core material 6 is a plate-shaped urethane resin foam, and is composed of a first polyurethane foam 11 and a second polyurethane foam 12. Although two types of polyurethane foam are shown in the core material 6, three or more types may be used. The shape, arrangement, etc. of each polyurethane foam differs depending on the specifications required for the vehicle interior material. For example, an ether-based semi-rigid polyurethane foam is selected for the first polyurethane foam 11 and the second polyurethane foam 12.

[0038] Generally, polyurethane foams are classified into flexible polyurethane foams, semi-rigid polyurethane foams, and rigid polyurethane foams. Rigid polyurethane foams are known to have low breathability because the cells in the rigid polyurethane foam are closed cells with unbroken cell membranes. On the other hand, flexible polyurethane foams are open cells with broken cell membranes, with interconnected cells, and therefore have relatively high breathability. Flexible polyurethane foams are also known to be relatively soft and have high sound absorption properties.

[0039] Semi-rigid polyurethane foams have properties intermediate between flexible and rigid polyurethane foams. The cell structure of semi-rigid polyurethane foams can be considered to be a mixture of open cells and closed cells. Furthermore, semi-rigid polyurethane foams whose properties are closer to those of flexible polyurethane foams are considered to be softer and have higher breathability and sound absorption properties.

[0040] As shown in Fig. 2, in a plan view of the core material 6 according to this embodiment, the first polyurethane foam 11 is arranged in the left and right side edges and front edge regions of the outer periphery of the core material 6, and the second polyurethane foam 12 is arranged across the inner region and rear end of the core material 6. In other words, the first polyurethane foam 11 is arranged so as to surround the left and right side edges and front edge of the outer periphery of the second polyurethane foam 12. The first polyurethane foam 11 is configured to have a hardness that enhances moldability and ensures better shape retention than the second polyurethane foam 12. In contrast, the second polyurethane foam 12 is configured to have enhanced sound absorption properties and is lighter than the first polyurethane foam 11.

[0041] <Configuration of foaming tank> As shown in Figures 3 and 4, the foaming tank 20 for foaming synthetic resin has a generally rectangular box shape with an open top, a rectangular bottom 21, and walls 23 that stand on all four sides of the bottom 21 and surround it. The bottom 21 and walls 23 are made of a suitable material, such as cardboard or PP (polypropylene). Multiple urethane concentrates 11a, 12a with different blending formulations of raw materials are separately injected into the foaming tank 20 and foamed simultaneously. The bottom 21 of the foaming tank 20 is provided with a partition 25 that divides the bottom 21 into at least two or more arbitrary partitioned regions 26, 27. The position of the partition 25 is set corresponding to the arrangement of the first and second polyurethane foams 11, 12 that constitute the core material 6. A partition 25 defines a first partitioned area 26, into which the first urethane stock solution 11a for the first polyurethane foam 11 is poured, and a second partitioned area 27, into which the second urethane stock solution 12a for the second polyurethane foam 12 is poured, on the bottom surface 21 of the foaming tank 20. In this embodiment, the second urethane stock solution 12a is formulated to have a lower density than the first urethane stock solution 11a.

[0042] The partition 25 is, for example, a cardboard plate, and is provided substantially perpendicular to the bottom surface 21 of the foaming tank 20. The partition 25 is fixed to the bottom surface 21 with masking tape 29 or the like. As shown in FIGS. 6 and 7 , the height L1 of the partition 25 is set by a liquid level adjusting unit (described later) so that the first and second urethane stock solutions 11a and 12a, which are injected into the compartmented regions 26 and 27, do not mix with each other at the boundary between the compartmented regions 26 and 27 in their liquid raw material state immediately after injection. The height L1 is also set so that the first and second urethane stock solutions 11a and 12a become creamy and rise upward, reaching the top of the partition 25 and contacting each other at the interface 14 when the foaming reaction starts. The viscosity of the urethane resin increases as the foaming reaction progresses. However, in simultaneous foaming of urethane stock solutions with different properties, the greater the difference in viscosity of the urethane resins when the interface between the urethane resins reaches the top of the partition after foaming starts, the more likely shear stress will act at the interface, causing voids to form. Therefore, the height L1 of the partition 25 is set so that the interface 14 reaches the upper end of the partition 25 before the difference in viscosity between the urethane resins 11b and 12b due to the different properties of the urethane raw solutions 11a and 12a becomes large.

[0043] It is more preferable to set the height L1 of the partition 25 to, for example, 30 mm or less, which can prevent a decrease in the yield and recovery rate of the core material block in the cutting process of the core material 6 described later.

[0044] The material of the partition 25 can be selected from cardboard and synthetic resins such as PP (polypropylene). On the other hand, if a material containing a plasticizer, such as polyvinyl chloride, is used, the entire partition must be covered with masking tape 29 or the like to prevent deterioration of the quality of the expanded polyurethane foam. Furthermore, if a material containing air inside, such as polyurethane foam, is used as the partition, it will float up due to the pressure of the injection and foaming reaction of the urethane concentrates 11a and 12a, so it must be fixed to the bottom portion 21 with masking tape 29 or the like.

[0045] The foaming tank 20 is equipped with a liquid level adjusting unit that adjusts the liquid level H1, H2 of the urethane stock solutions 11a, 12a in a liquid raw material state when the urethane stock solutions 11a, 12a with different foaming ratios are poured into the respective compartments 26, 27. In this embodiment, a bottom-raising member 28 (bulking member) is disposed in the second compartment 27 of the bottom surface portion 21 to raise the bottom surface height of the bottom surface portion 21. This allows the liquid level H2 of the second urethane stock solution 12a in a liquid raw material state to be raised. Generally, the foaming ratio of a urethane stock solution varies depending on the properties of the formulated raw material. Therefore, when urethane stock solutions with different properties are simultaneously foamed, the liquid level from the bottom surface of the urethane stock solution that foams at a high foaming ratio is set relatively low to adjust the height of the upper surface of the foamed polyurethane foam. In this case, as the urethane resin rises after the foaming starts, the difference in the rising speed of these urethane resins increases. The greater this speed difference, the more likely it is that shear stress will act at the interface and voids will be generated. Therefore, by using the bottom-raising member 28 to raise the liquid level H2 of the second urethane concentrate 12a, which foams at a relatively high rate, the liquid level heights H1 and H2 of the multiple urethane concentrates 11a and 12a in their liquid raw material state can be made uniform.

[0046] The bottom-raising member 28 is made of a cardboard plate shaped and sized to correspond to the compartment shape of the second compartment area 27, and is disposed across the entire surface of the second compartment area 27. The thickness of the bottom-raising member 28 is set so that the liquid level H2 of the second urethane stock solution 12a rises and becomes equal to the liquid level H1 of the first urethane stock solution 11a depending on the amount of each urethane stock solution 11a, 12a added. Note that "equal liquid level" does not necessarily mean that the liquid levels of the urethane stock solutions are the same, but also includes a state in which the liquid level of each urethane stock solution is similar in its liquid raw material state. For example, a state in which there is an error of about 1.5 mm between the liquid level H1 of the first urethane stock solution 11a in its liquid raw material state and the liquid level H2 of the second urethane stock solution 12a in its liquid raw material state is also included in the "equal liquid level" state.

[0047] The partition and bottom-raising member disposed on the bottom surface portion 21 of the foaming tank 20 may be configured as an integrated L-shaped member 30 having an L-shaped cross section intersecting the boundary between the partitioned regions 26 and 27 as shown in Fig. 8. The L-shaped member 30 corresponds to the partition, bottom-raising member, bulk-raising member, and liquid level adjusting portion. For example, by configuring the integrated member by extrusion molding synthetic resin, it becomes easier to set and manage the dimensions of the member. Also, for example, the partition and bottom-raising member may be configured as an integrated member by bending a cardboard plate into an L shape.

[0048] As shown in Figure 9, block members 31 may be placed in part of the second compartment area 27 as bulkheads. Block members 31 may be made of cardboard or synthetic resins such as PP (polypropylene). The height of the upper end of block member 31 when placed on bottom surface portion 21 is preferably lower than the height of partition 25 to prevent a decrease in the recovery rate of the core raw material blocks. The liquid level H2 of second urethane stock solution 12a in a liquid raw material state can be adjusted by changing the volume and number of block members 31.

[0049] 10, the foaming tank 20 may be configured to have a recess 32 as a liquid level adjusting part, which lowers the liquid level H1 of the first urethane stock solution 11a in a liquid raw material state in the first partitioned area 26. The recess 32 is formed, for example, by partially digging down the bottom surface part 21 in the first partitioned area 26. This makes it possible to lower the liquid level H1 of the first urethane stock solution 11a in a liquid raw material state, which has a relatively low foaming ratio, and make it equal to the liquid level H2 of the second urethane stock solution 12a in a liquid raw material state.

[0050] A partition may be disposed on the bottom surface 21 of the foaming tank 20. The partition has a shape such that, in a cross-sectional view intersecting the boundaries of the compartmented regions 26 and 27, the surface in contact with the plurality of urethane concentrate solutions 11a and 12a has a continuous, smoothly curved shape. For example, as shown in FIG. 11 , a partition 35 having a semicircular cross-section is selected. The partition 35 has a support portion 36 extending from the zenith toward the bottom surface 21 and a stabilizing portion 37 that is flat and parallel to the bottom surface 21 and makes surface contact with the bottom surface 21. The support portion 36 has a pointed insertion portion 38 at its lower end. The partition 35 is made of a synthetic resin such as PP (polypropylene) and is molded by extrusion molding. The partition 35 is fixed to the bottom surface 21 and further covered with masking tape 29. A material that does not contain plasticizers is preferable for the partition 35 in order to maintain the quality of the foamed polyurethane foam.

[0051] When the partition 35 having a semicircular cross section is disposed on the bottom surface portion 21, for example, the partition 35 may be cut obliquely with respect to the direction in which the partition 35 extends linearly in a plan view, and the cut surfaces of the partition 35 may be disposed facing each other at the corners of the second partitioned area 27. Also, two partitions 35 may be connected by a member configured separately from the partitions 35.

[0052] <Method for manufacturing vehicle interior core material> Next, a method for manufacturing the core material for vehicle interiors will be described. The method for manufacturing the core material 6 according to this embodiment includes a stock solution preparation step, a stock solution injection step, a foam molding step, and a cutting step.

[0053] [Stock solution preparation process] In the stock solution preparation process, a first urethane stock solution 11a for forming the first polyurethane foam 11 and a second urethane stock solution 12a for forming the second polyurethane foam 12 are prepared. Polyurethane foam is obtained by mixing and reacting polyol and polyisocyanate as the main raw materials in the presence of a blowing agent, a foam stabilizer, a catalyst, and other additives as needed, to form a foam. The properties of the urethane resin are determined by the molecular weight and number of functional groups of the polyol and polyisocyanate used, so there are multiple types. Furthermore, even when the same raw materials are used, the foam hardness can be changed by changing the blend ratio of the polyol and polyisocyanate. In this embodiment, a first urethane stock solution 11a and a second urethane stock solution 12a are prepared, each with a different blending ratio of raw materials. The second urethane stock solution 12a has a lower density than the first urethane stock solution 11a and can be foamed at a higher expansion ratio.

[0054] [Still injection process] 3 and 4, the stock solution injection process is a process in which multiple urethane stock solutions 11a, 12a with different blending formulations of raw materials are separately poured into compartmented areas 26, 27 formed by a partition 25 on the bottom surface 21 of the foaming tank 20. Specifically, the first urethane stock solution 11a (liquid raw material) is injected into the first compartmented area 26, and the second urethane stock solution 12a (liquid raw material) is injected into the second compartmented area 27. The liquid level heights H1, H2 of the urethane stock solutions 11a, 12a injected into the respective compartmented areas 26, 27 vary depending on the area (bottom area) of the bottom surface 21 of the foaming tank 20, the amount of raw material input, etc., and are therefore set appropriately depending on the expansion ratio of the urethane stock solutions 11a, 12a, the bottom area of ​​the foaming tank 20, the amount of raw material input, etc.

[0055] In this embodiment, as shown in FIG. 6, a bottom-raising member 28 (height-raising member, liquid level adjuster) is disposed in the second compartment area 27. The bottom-raising member 28 raises the bottom height of the second compartment area 27, thereby raising the liquid level H2 of the second urethane stock solution 12a in its liquid raw material state. This allows the first urethane stock solution 11a and the second urethane stock solution 12a to be poured so that their liquid level heights H1 and H2 in their liquid raw material states are the same. Furthermore, the heights of the upper surfaces of the foamed first polyurethane foam 11 and the second polyurethane foam 12 can be made the same. The height L1 of the partition 25 is set to a height that prevents the first and second urethane stock solutions 11a and 12a in their liquid raw material states from mixing with each other at the boundary between the first and second compartment areas 26 and 27 immediately after pouring. Therefore, the liquid level heights H1 and H2 of the first and second urethane concentrates 11a and 12a in the liquid raw material state are located below the upper end of the partition 25.

[0056] [Foam molding process] As shown in Figure 5, the foam molding process involves reacting a first urethane stock solution 11a and a second urethane stock solution 12a, each of which has a different property, with each of the urethane foams expanding upward and bonding together to form a solid.

[0057] The first urethane stock solution 11a and the second urethane stock solution 12a, which are mixtures of the respective raw materials, do not overflow from the respective compartment areas 26, 27 in their liquid raw material state immediately after injection, and therefore do not mix with each other (see Figure 6). The urethane stock solutions 11a, 12a injected into the respective compartment areas 26, 27 each change from a liquid raw material state to a creamy state through a foaming reaction and begin to rise upward. Here, the cream time is the time from when the urethane stock solutions start to mix until they turn creamy and the liquid level rises. Each urethane stock solution 11a, 12a reaches the height of the upper end of the partition 25 when the cream time has elapsed and the foaming reaction begins.

[0058] When the foaming reaction begins in each of the urethane stock solutions 11a and 12a, bubbles that become the nuclei of the cells begin to be generated. Then, as the foaming reaction progresses, the urethane resin 11b from the first urethane stock solution 11a and the second urethane resin 12b from the second urethane stock solution 12a begin to form cells as the bubbles grow (expand).

[0059] After first urethane stock solution 11a and second urethane stock solution 12a each begin their foaming reaction and reach the height of the upper end of partition 25, first urethane resins 11b and 12b come into contact with each other at interface 14 (see FIG. 7). When these urethane resins 11b, 12b (urethane stock solutions 11a, 12a that have begun their foaming reaction) reach partition 25, their foaming rates have not yet increased, and the difference in foaming rate between urethane stock solutions 11a, 12a is kept below a certain level.

[0060] After the cream time has passed, the urethane resins 11b and 12b made from the urethane stock solutions 11a and 12a change from a creamy state to a sol state, which is a dispersion of fluid liquid and gas. The first urethane stock solution 11a and the second urethane stock solution 12a mix in a sol state in a certain area where they contact each other at the interface 14, and foam. As the foaming reaction progresses, the viscosity of the urethane resins 11b and 12b increases, and cell formation progresses.

[0061] As the foaming reaction progresses, each urethane resin 11b, 12b loses its fluidity and turns into a gel-like dispersion of liquid and gas, and the foaming ceases, stopping the rise of the polyurethane foam block. Holes appear in some of the cell walls of each urethane resin 11b, 12b (cell membranes are broken, forming open cells with interconnected air bubbles), completing the formation of a polyurethane foam. After that, when the surface of each polyurethane foam 11, 12 is completely hardened, the first polyurethane foam 11 and the second polyurethane foam 12 are bonded together to form an integrated block-like solid (see Figure 5). In other words, a core material block composed of the first polyurethane foam 11 and the second polyurethane foam 12 is obtained. After the foam molding process, the core material block is removed from the foaming tank 20.

[0062] [Cutting process] The cutting process is a process in which the core material raw block is cut out to obtain the core material 6. The core material raw block removed from the foaming tank 20 has its sides cut vertically to adjust its shape. Furthermore, since the top surface of the core material block is often not flat, this portion is cut horizontally to remove it. The core material raw block is then cut out horizontally. At this time, the cutting position of the core material raw block is adjusted so that the core material is cut to a predetermined thickness from the surface on the upper end side of the core material block, corresponding to the desired thickness of the core material 6. The core material block is then cut out sequentially at positions where the predetermined thickness is obtained, to obtain multiple core materials 6. Note that the core material block may also be cut diagonally to obtain the core material 6.

[0063] In the manufacturing process of the core material 6 according to this embodiment, a member in which the partition and the bottom-raising member are integrated may be disposed on the bottom surface portion 21 of the foaming tank 20. For example, as shown in Fig. 8, an integrated L-shaped member 30 having an L-shaped cross section as described above may be disposed. That is, the L-shaped member 30 corresponds to the partition, the bottom-raising member, the raising member, and the liquid level adjusting portion.

[0064] 9, the process for producing the core material 6 may involve placing block members 31 as bulkheads on the bottom surface 21 of a portion of the second compartment area 27. The height of the upper ends of the block members 31 is preferably lower than the height of the partitions 25 to prevent a decrease in the recovery rate of the core material blocks. The liquid level H2 of the second urethane stock solution 12a in a liquid raw material state can be adjusted by changing the volume and number of block members 31. For example, by appropriately placing block members 31 (bulheads) on the bottom surface 21 of a portion of the second compartment area 27 before or after the injection of the urethane stock solutions 11a and 12a, the liquid level heights H1 and H2 of the first urethane stock solution 11a and the second urethane stock solution 12a in a liquid raw material state can be made uniform.

[0065] 10, in the process for producing the core material 6, a recess 32 may be provided on the bottom surface 21 to lower the liquid level H2 of the first urethane stock solution 11a in the first partitioned region 26. As described above, the recess 32 is formed by partially digging down the bottom surface 21 in the first partitioned region 26. This allows the liquid level H1 of the first urethane stock solution 11a, which has a relatively low expansion ratio, in the liquid raw material state to be lowered to match the liquid level H2 of the second urethane stock solution 12a in the liquid raw material state.

[0066] The liquid level adjusters, which include the lifting member, bottom-raising member 28, L-shaped member 30, block member 31, and recess 32, perform a liquid level adjusting process to equalize the liquid level heights H1, H2 of the urethane stock solutions 11a, 12a in a liquid raw material state injected into each of the compartmented regions 26, 27 in the foaming tank 20. In the manufacturing process of the core material 6, if the liquid level adjuster is provided in advance in the foaming tank 20, the liquid level heights H1, H2 of the urethane stock solutions 11a, 12a in a liquid raw material state can be equalized by injecting multiple urethane stock solutions 11a, 12a into each of the compartmented regions 26, 27 in the raw material injection process. In addition, in the manufacturing process of the core material 6, the liquid level adjusters can be provided in the foaming tank 20 before and after the raw material injection process to equalize the liquid level heights H1, H2 of the urethane stock solutions 11a, 12a in a liquid raw material state, even if the urethane stock solutions have different expansion ratios. That is, if the foaming tank 20 has a liquid level adjusting part, the liquid level heights H1, H2 of the plurality of urethane concentrate solutions 11a, 12a in the liquid raw material state with different foaming magnifications can be made uniform.

[0067] The partition installed on the bottom surface portion 21 of the foaming tank 20 may have a configuration in which the surface in contact with the plurality of urethane concentrate solutions 11a, 12a has a continuous smooth curved shape in a cross section intersecting with the boundaries of the partitioned regions 26, 27. For example, as shown in Fig. 11, the above-mentioned partition 35 having a semicircular cross section may be selected.

[0068] <Composition of ceiling interior materials> As shown in Fig. 1, the base layer 2 of the ceiling interior material includes a core material 6 and fiber reinforcement layers 7 and 8 laminated on both sides of the core material 6, and is solidified with a thermosetting adhesive or the like. The fiber reinforcement layers 7 and 8 are provided to maintain the shape and ensure the rigidity of the ceiling interior material 10, and may be made of, for example, a glass fiber mat. The surfaces of these fiber reinforcement layers 7 and 8 are coated with or impregnated with a thermosetting adhesive (thermoplastic resin), and are adhered to both sides of the core material 6, respectively.

[0069] A backing material 3 is disposed on the vehicle body side of the base material layer 2. For example, a needle-punched nonwoven fabric or a spunbond nonwoven fabric is selected as the backing material 3, and a PET resin fiber nonwoven fabric or the like is selected as the material for the backing material 3. The backing material 3 may also be laminated with a breathable film.

[0070] A skin material 4 is disposed on the interior side of the base material layer 2. The skin material 4 is responsible for the design of the ceiling interior material 10. The skin material 4 is selected, for example, from a laminate of a surface layer and a soft polyurethane foam sheet. The surface layer can be made of a variety of materials, including fabric, cloth, knitted fabric, woven fabric, nonwoven fabric, thin woolen fabric, synthetic leather, artificial leather, genuine leather, etc. Furthermore, a film layer made of, for example, a non-breathable film may be disposed between the base material layer 2 and the skin material 4 depending on the specifications of the ceiling interior material 10.

[0071] <Manufacturing process for ceiling interior materials> The ceiling interior material is formed by integrally molding a base material layer 2, a backing material 3, and a skin material 4 by hot pressing. A laminate of the base material layer 2, backing material 3, and skin material 4 is set in a mold whose molding surface is formed into a required curved surface. Then, this laminate is heated and pressurized in the mold to be integrally molded.

[0072] <Effects of the embodiment> The foaming tank 20 for foaming synthetic resin according to the embodiment includes a partition 25 disposed on the bottom surface 21 to define multiple compartments 26, 27, and a liquid level adjuster (e.g., a bottom-raising member 28) that adjusts the liquid level H1, H2 of the multiple urethane stock solutions 11a, 12a in a liquid raw material state. The multiple urethane stock solutions 11a, 12a, each with different properties due to different blending formulations of the raw materials used, are poured separately into the respective compartments 26, 27. The height L1 of the partition 25 is set so that the multiple urethane stock solutions 11a, 12a poured into each compartment 26, 27 do not mix with each other at the boundary between the compartments 26, 27 in their liquid raw material state immediately after pouring, and so that the multiple urethane stock solutions 11a, 12a come into contact with each other at the interface 14 when they become creamy and begin to rise and foam. The viscosity of each urethane resin increases as the foaming reaction progresses. However, when urethane concentrates with different properties are foamed simultaneously, the greater the difference in viscosity between the urethane resins when their interface reaches the top of the partition after foaming begins, the more likely shear stress will act at the interface, causing voids to form. Therefore, the height L1 of the partition 25 is set so that the interface 14 reaches the top of the partition 25 before the difference in viscosity between the different urethane resins 11b and 12b becomes too great. This prevents voids from forming at the interface 14 during the foaming stage, improving the quality of the core material 6 (a core material for vehicle interiors).

[0073] Furthermore, the foaming tank 20 includes a liquid level adjusting unit, which allows the liquid level heights H1 and H2 of the urethane stock solutions 11a and 12a in a liquid raw material state to be uniform when the urethane stock solutions 11a and 12a are injected into the compartment regions 26 and 27, respectively. Because the urethane stock solutions 11a and 12a have different foaming ratios, the difference in the rising speed of the urethane resins 11b and 12b increases as they rise. The greater this difference in speed, the greater the shear stress at the interface, making it more likely that voids will occur. Therefore, by making the liquid level heights H1 and H2 of the urethane stock solutions 11a and 12a in a liquid raw material state, the difference in the rising speed of the urethane stock solutions 11a and 12a when they reach the upper end of the partition 25 can be reduced. This reduces the occurrence of voids at the interface 14 during the foaming stage, thereby improving the quality of the core material 6 (vehicle interior core material).

[0074] The foaming tank 20 has a bulking member disposed on the bottom surface 21 at least in the second compartment area 27. The liquid level H2 of the second urethane stock solution 12a, which has a relatively high foaming ratio, rises depending on the volume of the bulking member. This allows the liquid level H2 of the second urethane stock solution 12a to be closer to the height L1 of the partition 25. Furthermore, by disposing the bulking member over the entire surface or part of the second compartment area 27, the liquid level H2 can be adjusted depending on the amount of the second urethane stock solution 12a introduced. That is, the liquid level heights H1 and H2 of the first and second urethane stock solutions 11a and 12a in their liquid raw material states can be made uniform. This prevents voids from occurring at the interface 14 during the foaming stage.

[0075] The foaming tank 20 is provided with a bottom-raising member 28 for raising the bottom height of the bottom portion 21 in at least the second partitioned region 27 into which the second urethane stock solution 12a having a relatively high foaming ratio is poured. For example, by disposing the bottom-raising member 28 over the entire surface of the second partitioned region 27, the liquid level H2 of the second urethane stock solution 12a can be raised according to the thickness of the bottom-raising member 28, and can be made equal to the liquid level H1 of the first urethane stock solution 11a.

[0076] The foaming tank 20 may be configured such that the partition and the bottom-raising member disposed on the bottom surface portion 21 are integrated into one member (for example, an L-shaped member 30). This can reduce the number of steps required to form and arrange the partition and the bottom-raising member. Furthermore, since the partition is integrated with the bottom-raising member, it is easy to fix the position of the partition, and the position and posture of the arranged partition can be stabilized.

[0077] The foaming tank 20 may be configured such that, at least in the first partitioned region 26 into which the first urethane stock solution 11a having a relatively low foaming ratio is poured, recesses 32 are provided in the bottom surface 21 to lower the liquid level H1 of the first urethane stock solution 11a in a liquid raw material state. By appropriately changing the size and number of recesses 32, the liquid level H1 can be adjusted according to the amount of the first urethane stock solution 11a poured. That is, the liquid level heights H1 and H2 of the plurality of urethane stock solutions 11a, 12a having different foaming ratios in a liquid raw material state can be made uniform. Therefore, the generation of voids at the interface 14 during the foaming stage can be suppressed.

[0078] The foaming tank 20 may be provided with a partition 35 whose surface in contact with the first urethane stock solution 11a and the second urethane stock solution 12a has a continuous, smoothly curved shape (e.g., semicircular shape) in a cross-sectional view intersecting the boundary between the partitioned regions 26 and 27. As shown in FIG. 12 , when the urethane stock solution is foamed in a partitioned space, shear stress acts on the wall surface or partition side surface A along the upward direction D, which tends to cause voids. Specifically, small bubbles in contact with the wall surface or partition side surface A are stretched by shear stress and may join together, causing voids. Therefore, by forming a cross-sectional shape of the contact surface B where the partition and the urethane stock solution come into contact with a continuous, smoothly curved shape, the small bubbles rise away from the contact surface B of the partition before joining together, thereby suppressing the generation of voids.

[0079] According to the manufacturing method of the core material 6 (vehicle interior core material) according to the embodiment, in the concentrate injection step, a first urethane stock solution 11a and a second urethane stock solution 12a, each having a different blending formulation of raw materials, are injected into a first compartment region 26 and a second compartment region 27, which are partitioned by a partition 25 on the bottom surface 21 of a foaming tank 20. The foaming tank 20 has a liquid level adjusting unit (e.g., a bottom raising member 28) that adjusts the liquid level heights H1 and H2 of the plurality of urethane stock solutions 11a and 12a, each having a different expansion ratio, in a liquid raw material state. The height L1 of the partition 25 is set by the liquid level adjusting unit so that the plurality of urethane stock solutions 11a and 12a injected into each compartment region 26 and 27 do not mix with each other at the boundary between the compartment regions 26 and 27 in their liquid raw material state immediately after injection, and so that the plurality of urethane stock solutions 11a and 12a come into contact with each other at an interface 14 when the cream time has elapsed and the foaming reaction begins. This allows interface 14 to reach the upper end of partition 25 before the difference in viscosity between first urethane resin 11b and second urethane resin 12b becomes large during the foam molding process. This makes it possible to suppress the generation of voids at interface 14, thereby improving the quality of core material 6 (vehicle interior core material).

[0080] In the manufacturing process of the core material 6 (vehicle interior core material) according to the above embodiment, the foaming tank 20 is provided with a liquid level adjusting unit, so that the liquid level heights H1, H2 of the plurality of urethane stock solutions 11a, 12a in a liquid raw material state with different expansion ratios can be made uniform in the stock solution injection process. This reduces the difference in the rising speed when the liquid levels of the plurality of urethane stock solutions 11a, 12a reach the upper end of the partition 25. This makes it possible to suppress the generation of voids at the interface 14, thereby improving the quality of the core material 6 (vehicle interior core material).

[0081] In the manufacturing process for the core material 6 (vehicle interior core material), a bulking member is placed on the bottom surface 21 in the second compartment region 27, into which the second urethane stock solution 12a, which has at least a relatively high expansion ratio, is poured. The liquid level H2 of the second urethane stock solution 12a in its liquid raw material state rises depending on the volume of the bulking member. This allows the liquid level H2 of the second urethane stock solution 12a to be brought closer to the height L1 of the partition 25 during the liquid raw material pouring process. Furthermore, by placing the bulking member over the entire surface or a portion of the second compartment region 27, the liquid level H2 can be adjusted depending on the amount of second urethane stock solution 12a poured. In other words, the liquid level heights H1 and H2 of the multiple urethane stock solutions 11a and 12a in their liquid raw material state can be made uniform. Therefore, the occurrence of voids at the interface 14 can be suppressed.

[0082] In the manufacturing process of the core material 6 (vehicle interior core material), a bottom-raising member 28 is placed in the second partitioned region 27 into which the second urethane stock solution 12a, which has at least a relatively high expansion ratio, is poured, thereby raising the bottom height of the bottom portion 21. For example, by placing the bottom-raising member 28 over the entire surface of the second partitioned region 27, the liquid level H2 of the second urethane stock solution 12a (liquid raw material) rises in accordance with the thickness of the bottom-raising member 28, and can be made equal to the liquid level H1 of the first urethane stock solution 11a.

[0083] In the manufacturing process of the core 6 (vehicle interior core), a component (e.g., L-shaped component 30) configured as an integrated component of a partition and a bottom-raising component may be placed on the bottom surface portion 21. This can reduce the number of steps required to form and place the partition and bottom-raising component. Furthermore, since the partition is integrated with the bottom-raising component, it is easy to fix the position of the partition, and the position and posture of the placed partition can be stabilized.

[0084] In the manufacturing process for the core material 6 (vehicle interior core material), a recess 32 may be provided on at least the bottom surface 21 of the first partitioned region 26 to lower the liquid level H1 of the first urethane stock solution 11a in a liquid raw material state. This lowers the liquid level H1 of the first urethane stock solution 11a, which has a relatively low expansion ratio, in the liquid raw material state during the stock solution injection process, and makes it uniform with the liquid level H2 of the second urethane stock solution 12a in a liquid raw material state. In other words, the liquid level heights H1 and H2 of the multiple urethane stock solutions 11a, 12a in a liquid raw material state can be made uniform. This prevents voids from occurring at the interface 14.

[0085] In the manufacturing process of the core material 6 (vehicle interior core material), a partition 35 may be disposed on the bottom surface 21 of the foaming tank 20. The partition 35 has a continuous, smoothly curved surface that comes into contact with the plurality of urethane concentrate solutions 11a, 12a in a cross-sectional view that intersects with the boundaries of the partitioned regions 26, 27. This allows small bubbles to rise away from the surface of the partition 35 before joining together in the foam molding process, thereby suppressing the generation of voids.

[0086] The partitions 25, 35 according to the above embodiment are fixed to the bottom surface portion 21 so as to be covered with masking tape 29. This allows the partitions 25, 35 to be arranged on the bottom surface portion 21 so as to be self-supporting. This also prevents the partitions 25, 35 from lifting due to the foaming pressure of the urethane resins 11b, 12b, and prevents the urethane concentrates 11a, 12a or the urethane resins 11b, 12b from getting between the bottom ends of the partitions 25, 35 and the bottom surface portion 21. Depending on the material of the partitions 25, 35, direct contact with the polyurethane foam may degrade the quality of the polyurethane foam, so the masking tape 29 is also used to maintain the quality of the polyurethane foam.

[0087] The partition 35 having a semicircular cross section according to the embodiment has a stabilizing portion 37 and an inserting portion 38. The stabilizing portion 37 increases the contact area with the bottom surface portion 21, making it possible to stabilize the shape and posture of the partition when it is placed. Furthermore, because the inserting portion 38 is inserted into and fixed to the bottom surface portion 21, it is possible to prevent the partition 35 from shifting out of position.

[0088] When a block member 31 is placed on the bottom surface 21 in at least one compartment area as a bulking member, it becomes easier to adjust the liquid level of the urethane concentrate injected into each compartment area, not only when there are two compartment areas but also when there are three or more compartment areas. Also, by setting the height position of the upper end of the block member 31 placed on the bottom surface 21 lower than the upper end of the partition, it is possible to prevent a decrease in the yield of raw material core blocks.

[0089] The present invention will be specifically described below with reference to examples and comparative examples.

[0090] [Example 1] A plate-shaped partition 25 was erected on the bottom surface 21 of the foaming tank 20. As shown in FIG. 6, the height L1 of the partition 25 from the bottom surface 21 was set to approximately 15 mm. A second partitioned region 27 partitioned by the partition 25 had a bottom-raising member 28 made of flat cardboard placed over the entire surface of the bottom surface 21. The first urethane stock solution 11a was poured into the first partitioned region 26, and the second urethane stock solution 12a was poured into the second partitioned region 27. The second urethane stock solution 12a was blended at a lower density than the first urethane stock solution 11a. The liquid level H1 of the first urethane stock solution 11a from the bottom surface 21 was approximately 9.4 mm. The second urethane stock solution 12a was raised by the thickness of the bottom-raising member 28, and the liquid level H2 from the bottom surface 21 was approximately 10.7 mm.

[0091] [Comparative Example 1] As shown in Fig. 13, a plate-shaped partition 41 was erected on the bottom surface 21 of the foaming tank 20. The height of the partition 41 from the bottom surface 21 was set to about 10 mm. The first urethane stock solution 11a was poured into the first partitioned region 26 partitioned by the partition 41, and the second urethane stock solution 12a was poured into the second partitioned region 27. As in Example 1, the second urethane stock solution 12a was blended at a lower density than the first urethane stock solution 11a. The liquid level H1 of the first urethane stock solution 11a based on the bottom surface 21 was about 9.4 mm, and the liquid level H2 of the second urethane stock solution 12a was about 5.7 mm.

[0092] Comparative Example 2 As shown in Fig. 14, a plate-shaped partition 42 was erected on the bottom surface 21 of the foaming tank 20. The height of the partition 42 from the bottom surface 21 was set to about 15 mm. The first urethane stock solution 11a was poured into the first partitioned region 26 partitioned by the partition 42, and the second urethane stock solution 12a was poured into the second partitioned region 27. As in Example 1, the second urethane stock solution 12a was blended at a lower density than the first urethane stock solution 11a. The liquid level H1 of the first urethane stock solution 11a based on the bottom surface 21 was about 9.4 mm, and the liquid level H2 of the second urethane stock solution 12a was about 5.7 mm.

[0093] Table 1 shows the number and size of voids generated at the interface between the first and second polyurethane foams in the upper, middle, and bottom layers of the polyurethane foams foamed in the foaming tank for Example 1, Comparative Example 1, and Comparative Example 2. Comparing the number of voids in the upper, middle, and bottom layers of the polyurethane foams, Comparative Example 1 had fewer voids than Comparative Example 2. Furthermore, Comparative Example 1 also had fewer voids of 4 mm or larger than Comparative Example 2. In other words, by bringing the partition height closer to the liquid level of the urethane concentrate in its liquid raw material state, the generation of voids at the interface was suppressed. In Example 1, the generation of voids at the interface was further suppressed than in Comparative Example 1. Furthermore, no voids of 4 mm or larger were generated in Example 1. In other words, by aligning the liquid level of the urethane concentrates with different properties in their liquid raw material states, the generation of voids at the interface was suppressed.

[0094] [Table 1]

[0095] The foam tank for foaming synthetic resins and the method for manufacturing a vehicle interior core material according to the present invention are not limited to the appearance and configuration described in the above embodiment, and can be embodied in various other forms by various modifications, additions, deletions, and combinations of configurations within the scope that does not change the gist of the present invention.

[0096] For example, although the vehicle interior core material in the above embodiment is shown as an example of a core material for vehicle interior materials, it is not limited to vehicles and can be used for various types of vehicles such as ships and aircraft.

[0097] In the above embodiment, examples of the raising member include a bottom-raising member and a block member disposed on the bottom surface, but this is not limiting, and raising members of various shapes or configurations may be used. For example, a flat member such as a bottom-raising member may be disposed on a portion of the partitioned area rather than the entire area to raise the liquid level of the urethane concentrate in its liquid raw material state. Furthermore, the raising member may have a partially uneven surface. Furthermore, multiple ball-shaped members may be disposed on the bottom surface as raising members.

[0098] The liquid level adjusting section of the foaming tank may be configured to have steps so that the bottom section has different heights for each partitioned area, thereby aligning the liquid level of multiple urethane concentrates with different foaming ratios in their liquid raw material state.

[0099] The foaming tank may have, for example, a lifting member disposed in each of the plurality of partitioned regions as a liquid level adjusting unit. In this case, by appropriately changing the number and volume of the lifting members disposed, it is possible to make the liquid level of the plurality of urethane stock solutions in a liquid raw material state with different foaming ratios uniform. Alternatively, bottom-raising members with different thicknesses may be disposed in the plurality of partitioned regions, respectively, to make the liquid level of the plurality of urethane stock solutions in a liquid raw material state uniform. Alternatively, a lifting member may be disposed in the partitioned region into which a urethane stock solution with a relatively high foaming ratio is poured, and a recess may be provided in the partitioned region into which a urethane stock solution with a relatively low foaming ratio is poured.

[0100] In the above embodiment, an example was shown in which the semicircular partition had a support portion including an insertion portion and a stabilizing portion, but a configuration without a support portion or a stabilizing portion is also possible. Alternatively, a configuration with either a support portion or a stabilizing portion is also possible. Alternatively, a configuration in which the support portion does not have an insertion portion is also possible.

[0101] The shape of the partition is not limited to a semicircular cross section, and various shapes can be selected, provided that the surface that comes into contact with the plurality of urethane concentrate solutions has a continuous, smooth curve. [Explanation of symbols]

[0102] 2 Base material layer 3 Backing material 4 Skin material 6 Core material (vehicle interior core material) 7 Fiber reinforcement layer 8 Fiber reinforcement layer 10 Ceiling interior materials (vehicle interior materials) 11 No. 1 Polyurethane Foam 11a First urethane stock solution 11b First urethane resin 12 Second polyurethane foam 12a Second urethane stock solution 12b Second urethane resin 14 Interface 20 Foaming tank 21 Bottom part 23 Wall 25 dividers 26 First Section Area 27 Second Section Area 28 Bottom raising member (raising member, liquid level adjustment part) 29 Masking tape 30 L-shaped components (partitions, bottom raising components, height raising components, liquid level adjustment components) 31 Block member (raising member, liquid level adjustment part) 32 Recess (liquid level adjustment part) 35 Dividers 36 Pillar section 37 Stable part 38 Insertion part H1 Liquid level of first urethane concentrate H2 Liquid level of second urethane concentrate L1 Partition height

Claims

1. A foaming tank for foaming synthetic resins, which is box-shaped with an opening at the top, into which multiple urethane stock solutions with different blending formulations of raw materials are separately injected and foamed simultaneously, A partition installed on the bottom surface of the foaming tank and dividing the bottom surface into at least two or more partitioned areas; a liquid level adjusting unit that adjusts the liquid levels of the plurality of urethane stock solutions in a liquid raw material state when the plurality of urethane stock solutions with different foaming ratios are injected into each of the partitioned regions, The height of the partition is set by the liquid level adjusting unit so that the plurality of urethane stock solutions injected into each of the partitioned areas do not mix with each other at the boundaries of the partitioned areas when they are in a liquid raw material state immediately after injection, and so that the plurality of urethane stock solutions come into contact with each other at their interfaces when they turn creamy, rise, and begin the foaming reaction.

2. 2. A foaming tank for foaming synthetic resins according to claim 1, The foaming tank for foaming synthetic resins has, as the liquid level adjusting section, a raising member that is placed on the bottom surface of the compartmented area into which a urethane stock solution having a relatively high foaming ratio is poured, and that raises the liquid level of the urethane stock solution in a liquid raw material state.

3. 3. A foaming tank for foaming synthetic resins according to claim 2, The foaming tank for foaming synthetic resins has, as the raising member, a bottom-raising member that is placed on the bottom portion in at least the partitioned area into which a urethane stock solution having a relatively high foaming ratio is poured, and that raises the bottom height of the bottom portion, thereby increasing the liquid level of the urethane stock solution in a liquid raw material state.

4. 4. A foaming tank for foaming synthetic resins according to claim 3, A foaming tank for foaming synthetic resin, wherein the partition and the bottom raising member are integrally formed.

5. 2. A foaming tank for foaming synthetic resins according to claim 1, The foaming tank for foaming synthetic resins has, as the liquid level adjusting section, a recess provided in the bottom surface section, at least in the compartmented area into which a urethane stock solution having a relatively low foaming ratio is poured, for lowering the liquid level of the urethane stock solution in a liquid raw material state.

6. 2. A foaming tank for foaming synthetic resins according to claim 1, A foaming tank for foaming synthetic resins, wherein the partition has a surface that comes into contact with the plurality of urethane concentrate solutions and has a continuous, smooth curve in a cross-sectional view intersecting the boundaries of the partitioned areas.

7. A method for manufacturing a vehicle interior core material, comprising: a stock solution preparation process for preparing a plurality of urethane stock solutions each having a different blending formulation of raw materials used as a urethane stock solution for molding polyurethane foam; a stock solution injection step of separately pouring the plurality of urethane stock solutions into a foaming tank having a box-like shape with an open top and a partition provided on a bottom surface thereof to provide at least two or more arbitrary compartmentalized areas; a foam molding step in which the plurality of urethane stock solutions are foamed upward and bonded to each other to be molded into an integrated solid, the foaming tank has a liquid level adjusting unit that adjusts liquid levels of the plurality of urethane stock solutions in a liquid raw material state when the plurality of urethane stock solutions having different foaming ratios are injected into each of the partitioned regions, The height of the partition is set by the liquid level adjusting unit so that the plurality of urethane stock solutions do not mix with each other when they are in a liquid raw material state immediately after being poured, and so that the plurality of urethane stock solutions come into contact with each other at their interfaces when they turn creamy, rise, and begin a foaming reaction.

8. A method for manufacturing the interior core material for a vehicle according to claim 7, A method for manufacturing an interior core material for a vehicle, in which a raising member is placed on the bottom portion as the liquid level adjustment section, which raises the liquid level of the urethane concentrate in its liquid raw material state in at least the compartment area into which a urethane concentrate with a relatively high foaming ratio is injected.

9. A method for manufacturing the interior core material for a vehicle according to claim 7, A method for manufacturing an interior core material for a vehicle, in which the liquid level adjustment section is formed by placing a bottom-raising member that raises the bottom height of the bottom section in the compartment area into which at least a urethane concentrate with a relatively high foaming ratio is poured, thereby raising the liquid level of the urethane concentrate in its liquid raw material state.

10. A method for manufacturing the interior core material for a vehicle according to claim 9, The method for manufacturing an interior core material for a vehicle, wherein the partition and the bottom raising member are integrally formed and placed on the bottom surface portion.

11. A method for manufacturing the interior core material for a vehicle according to claim 7, A method for manufacturing a vehicle interior core material, in which the liquid level adjustment section is a recess provided on the bottom surface section to lower the liquid level of the urethane concentrate in its liquid raw material state, at least in the compartment area into which a urethane concentrate with a relatively low foaming ratio is injected.

12. A method for manufacturing the interior core material for a vehicle according to claim 7, A method for manufacturing an interior core material for a vehicle, wherein the partition has a surface that comes into contact with the plurality of urethane concentrate solutions and has a continuous, smooth curve when viewed in cross section intersecting the boundary of the partition area.

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