Super critical foamed dual density cushion and method of making same

Abstract

A supercritical foaming dual-density cushion and a manufacturing method thereof, the manufacturing method is to prepare a first male mold, a female mold, and a second male mold. The first male mold is combined with the female mold to jointly define a first mold cavity. After the thermoplastic material is hot-melted and mixed with a first supercritical fluid to become a first mixture, the first mixture is injected into the first mold cavity and pressure-released to be foamed to form a body part. The first male mold is removed, the second male mold is combined with the female mold to jointly define a second mold cavity. After the thermoplastic material is hot-melted and mixed with a second supercritical fluid to become a second mixture, the second mixture is injected into the second mold cavity and pressure-released to be foamed to form a buffer unit combined with the body part to form a supercritical foaming dual-density cushion. The density of the buffer unit is less than that of the body part, so as to improve the comfort of the supercritical foaming dual-density cushion.

Description

Technical Field

[0001] This invention relates to a foamed pad, and more particularly to a supercritical foamed dual-density pad and its manufacturing method. Background Technology

[0002] An existing foam pad includes a high-density pad portion and a low-density pad portion disposed below the high-density pad portion. The density of the low-density pad portion is less than that of the high-density pad portion.

[0003] When a user sits on the foam pad and is positioned opposite the low-density pad portion, the low-density pad portion reduces pressure on the user's buttocks, thus improving seating comfort. However, manufacturing the foam pad requires the use of two separate molds for foaming and molding, followed by combining the low-density pad portion with the high-density pad portion. This process is relatively cumbersome, time-consuming, and costly. Furthermore, since the user's buttocks are still essentially in contact with the high-density pad portion, there is room for improvement in seating comfort. Summary of the Invention

[0004] The purpose of this invention is to provide a supercritical foamed dual-density cushion and its manufacturing method that can improve at least one of the aforementioned drawbacks.

[0005] The supercritical foamed dual-density pad of the present invention comprises a body portion and a buffer unit. The body portion is formed by foaming a thermoplastic material with a first supercritical fluid. The body portion includes a top surface and a bottom surface opposite to the top surface. The bottom surface of the body portion has a concave first surface segment defining an injection groove, an arcuate surface segment surrounding and connecting the first surface segment, and a lower nose end segment connected to the side opposite to the first surface segment of the arcuate surface segment. The first surface segment forms at least one through hole extending through the top surface of the body portion and communicating with the injection groove. The buffer unit includes a buffer substrate formed by foaming the thermoplastic material with a second supercritical fluid and having a density less than that of the body portion, and at least one buffer body connected to the buffer substrate. The buffer substrate fills the injection groove and connects to the first surface segment. The number of the at least one buffer body is the same as the number of the at least one through hole, and it fills the at least one through hole and connects to the body portion.

[0006] The supercritical foamed dual-density pad of the present invention has a lower nose end face segment connected to the front side of the arc surface segment and extending forward in a gradually tapering manner. The first face segment forms two through holes spaced apart from each other on the left and right. The buffer unit includes two buffer bodies respectively formed in the through holes.

[0007] The supercritical foamed dual-density pad of the present invention has each through hole having a lower opening formed on the first surface segment and an upper opening formed on the top surface of the body portion, and each buffer body extends from the lower opening of the corresponding through hole to the upper opening.

[0008] The supercritical foamed dual-density cushion of the present invention has each buffer body forming a kidney shape that is wider at the back and narrower at the front at the corresponding upper opening.

[0009] The supercritical foamed dual-density cushion of the present invention comprises at least one of polyurethane, thermoplastic polyurethane, and thermoplastic elastomer.

[0010] The manufacturing method of the supercritical foamed dual-density pad of the present invention includes the following steps: (A): preparing a female mold, a first male mold, and a second male mold. The female mold includes a concave female inner mold surface and a female mating surface surrounding and connecting the female inner mold surface. The first male mold includes a convex first inner mold surface, an inner mold arc surface surrounding and connecting the first inner mold surface, a convex first nose end surface connecting the inner mold arc surface to the side opposite to the first inner mold surface, a first mating surface surrounding and connecting the inner mold arc surface and the first nose end surface, at least one protrusion protruding from the first inner mold surface, and a first injection hole formed on the first inner mold surface. The second male mold has a convex second inner mold surface and a connecting surface. (A) The second nose end face of the second inner mold surface, the second mating surface surrounding and connecting the second inner mold surface and the second nose end face, and the second injection hole formed on the second inner mold surface; (B) The first male mold is combined with the female mold, the first mating surface of the first male mold abuts against the female mating surface of the female mold, the at least one protrusion abuts against the female inner mold surface, the first inner mold surface, the inner mold arc surface, the first nose end face and the female inner mold surface together define the first mold cavity; (C) The thermoplastic material is melted and mixed with a first supercritical fluid to become a first mixture, the first mixture is injected into the first mold cavity through the first injection hole to foam and form a body part, the body part including the abutting surface of the female mold surface. The top surface of the inner mold surface, and the bottom surface opposite to the top surface, the bottom surface of the body portion has a first surface segment abutting against the first inner mold surface, an arc surface segment surrounding and connecting the first surface segment and abutting against the inner mold arc surface, and a lower nose end face segment connected to the arc surface segment and abutting against the first nose end face, the first surface segment forming at least one through hole extending to the top surface of the body portion, the first surface segment being concave and defining an injection groove communicating with the at least one through hole, the at least one protrusion penetrating the at least one through hole; (D): Remove the first male mold, and combine the second male mold with the female mold, the second mating surface of the second male mold abutting against the female mating surface of the female mold, the arc surface of the inner mold abutting against the The arc-shaped section, the second inner mold surface, the second nose end surface, and the mother inner mold surface together define the second mold cavity, and the second injection hole is adjacent to the injection groove; and (E): the thermoplastic material is melted and mixed with the second supercritical fluid to form a second mixture, the second mixture is injected into the second mold cavity through the second injection hole, a portion of the second mixture is foamed in the injection groove to form a buffer base with a density less than that of the body, and another portion is foamed in the at least one through hole to form at least one buffer body with the same density as the buffer base, the body, the buffer base, and the at least one buffer body are combined to form a supercritical foamed dual-density pad.

[0011] In the manufacturing method of the supercritical foamed dual-density pad of the present invention, in step (A), the first nose end face is connected to the front side of the inner mold arc surface and extends forward in a gradually tapering manner. The first male mold includes two protrusions protruding from the first inner mold surface and located on the left and right sides of the first injection hole, respectively. In step (B), the protrusions abut against the female inner mold surface. In step (C), the first surface segment forms two through holes spaced apart from left to right. In step (E), the second mixture fills the through holes and foams to form two buffer bodies.

[0012] In the manufacturing method of the supercritical foamed dual-density pad of the present invention, in step (E), the left and right width of the buffer substrate gradually narrows from the rear end of the body portion to the lower nose end face section.

[0013] In the manufacturing method of the supercritical foamed dual-density pad of the present invention, in step (D), the minimum distance between the second inner mold surface and the first surface segment of the body part is greater than or equal to 5 mm.

[0014] In the manufacturing method of the supercritical foamed dual-density pad of the present invention, in step (A), the first injection hole and the second injection hole are conical from the inside to the outside.

[0015] The beneficial effects of this invention are as follows: by utilizing supercritical fluid, rapid foaming and molding can be completed without the need for additional chemical foaming agents, which is not only environmentally friendly but also significantly reduces manufacturing time. When the second mixture is injected into the second injection hole, there is sufficient space for it to flow through the injection groove and fill the at least one through hole, thus foaming and molding it into the at least one cushioning body, thereby improving the comfort of the supercritical foamed dual-density cushion. Attached Figure Description

[0016] Figure 1 This is a perspective view of an embodiment of the supercritical foamed dual-density pad of the present invention;

[0017] Figure 2 This is a bottom view of one of the main body parts of the embodiment described;

[0018] Figure 3 yes Figure 1 A bottom view;

[0019] Figure 4 This is a flowchart of the manufacturing method of the supercritical foamed dual-density pad of the present invention;

[0020] Figure 5 This is a bottom view of a first common mold of the embodiment described;

[0021] Figure 6This is a cross-sectional view of the first male mold combined with a female mold in the embodiment described above;

[0022] Figure 7 This is a bottom view of a second common mold of the embodiment described above;

[0023] Figure 8 This is a cross-sectional view of the second male mold combined with the female mold in the embodiment described above;

[0024] Figure 9 It is a flowchart illustrating the injection molding process shown in the longitudinal section of the first male mold or the second male mold combined with the female mold in the embodiment described above;

[0025] Figure 10 It is a flowchart illustrating the injection molding process shown in the cross section of the first male mold or the second male mold combined with the female mold in the embodiment described. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Before the present invention is described in detail, it should be noted that the relative position terms used in the following description, such as "front", "back", "left", "right", "up", and "down", are based on the orientation shown in the figures or the normal operating orientation.

[0027] See Figures 1 to 2 The embodiment of the supercritical foamed dual-density pad of the present invention is suitable for use as a bicycle seat. The supercritical foamed dual-density pad includes a body part 1 and a buffer unit 2.

[0028] The body portion 1 includes a top surface 11 and a bottom surface 12 opposite to the top surface 11. The top surface 11 has a seating surface segment 111 and an upper nose end segment 112 connected to the seating surface segment 111. The upper nose end segment 112 extends forward from the seating surface segment 111.

[0029] The bottom surface 12 has a first surface segment 121, an arcuate segment 122 surrounding and connecting the first surface segment 121, and a lower nose end surface segment 123 connected to the side of the arcuate segment 122 opposite to the first surface segment 121. The first surface segment 121 is concave and defines an injection groove 124. The lower nose end surface segment 123 connects to the front side of the arcuate segment 122 and extends forward in a tapering manner. The first surface segment 121 forms two through holes 13 extending to the seating surface segment 111 of the top surface 11. The through holes 13 are spaced apart on the left and right and communicate with the injection groove 124. Each through hole 13 has a lower opening 131 formed in the first surface segment 121 and an upper opening 132 formed in the seating surface segment 111 of the top surface 11. Each upper opening 132 is kidney-shaped, wider at the rear and narrower at the front, and is symmetrical to the other upper opening 132.

[0030] See Figures 1 to 3 The buffer unit 2 includes a buffer base 21 that fills the injection groove 124 and connects to the first surface segment 121, and two buffer bodies 22 that respectively fill the through hole 13 and connect the buffer base 21 and the body part 1. Each buffer body 22 extends from the lower opening 131 of the corresponding through hole 13 to the upper opening 132.

[0031] See Figures 4 to 7 An embodiment of the manufacturing method of the supercritical foamed dual-density pad of the present invention includes steps S1 to S5.

[0032] In step S1, a first male mold 3, a female mold 4, and a second male mold 5 are prepared.

[0033] The first male mold 3 includes a convex first inner mold surface 31, an inner mold arc surface 32 surrounding and connecting the first inner mold surface 31, a convex first nose end surface 33 connecting the inner mold arc surface 32 to the side opposite to the first inner mold surface 31, a first mating surface 34 surrounding and connecting the inner mold arc surface 32 and the first nose end surface 33, two protrusions 35 protruding from the first inner mold surface 31, two first injection holes 36 formed on the first inner mold surface 31, and a nose end injection hole 37 formed on the first nose end surface 33. The first nose end surface 33 connects to the front side of the inner mold arc surface 32 and extends forward in a tapering manner. The first injection hole 36 and the nose end injection hole 37 are spaced apart from each other, and the protrusions 35 are located to the left and right of the last first injection hole 36, respectively.

[0034] The female mold 4 includes a concave inner mold surface 41 and a female mating surface 42 surrounding and connecting the inner mold surface 41. The second male mold 5 has a convex second inner mold surface 51, a second nose end surface 52 connecting the second inner mold surface 51, a second mating surface 53 surrounding and connecting the second inner mold surface 51 and the second nose end surface 52, and two second injection holes 54 formed on the second inner mold surface 51 and spaced apart from each other. The second nose end surface 52 connects to the front side of the second inner mold surface 51 and extends forward in a tapering manner.

[0035] See Figure 4 , Figure 6 , Figure 9 and Figure 10 In step S2, the first male mold 3 is combined with the female mold 4. The first mating surface 34 of the first male mold 3 abuts against the female mating surface 42 of the female mold 4, and the protrusion 35 abuts against the female inner mold surface 41. The first inner mold surface 31, the inner mold arc surface 32, the first nose end surface 33 and the female inner mold surface 41 together define a first mold cavity 30.

[0036] See Figure 4 , Figure 9 and Figure 10 In step S3, a thermoplastic material (not shown) is melted and mixed with a first supercritical fluid (not shown) to form a first mixture (not shown). The first mixture is injected into the first mold cavity 30 through the first injection hole 36 and the nose injection hole 37, and then depressurized and foamed to form the body part 1.

[0037] Since the main body 1 is inverted relative to the normal use direction at this time, the top surface 11 of the main body 1 faces downward and abuts against the inner mold surface 41, the first surface segment 121 of the bottom surface 12 faces upward and abuts against the first inner mold surface 31, the arc surface segment 122 faces upward and abuts against the inner mold arc surface 32, and the lower nose end segment 123 faces upward and abuts against the first nose end surface 33. The protrusion 35 penetrates the through hole 13.

[0038] In step S4, the first male mold 3 is removed, and the second male mold 5 is joined to the female mold 4. The second mating surface 53 of the second male mold 5 abuts against the female mating surface 42 of the female mold 4, and the inner mold arc surface 32 abuts against the arc surface segment 122. The second inner mold surface 51, the second nose end surface 52, and the female inner mold surface 41 together define a second mold cavity 50. The second injection hole 54 is adjacent to the injection groove 124. At this time, the minimum distance between the second inner mold surface 51 and the first surface segment 121 of the body part 1 is greater than or equal to 5 mm.

[0039] In step S5, the thermoplastic material is melted and mixed with a second supercritical fluid (not shown) to form a second mixture (not shown). The second mixture is injected into the second mold cavity 50 through the second injection hole 54 and then depressurized and foamed. A portion of the second mixture is foamed in the injection groove 124 to form the buffer base 21, and another portion is foamed in the through hole 13 to form the buffer body 22. The left and right width of the buffer base 21 gradually narrows from the rear end of the body part 1 to the lower nose end face section 123. The buffer base 21 and the buffer body 22 are combined with the body part 1 to form the supercritical foamed dual-density pad.

[0040] In this embodiment, the thermoplastic material includes at least one of thermoplastic polyurethane (TPU), polyurethane (PU), and thermoplastic elastomer (TPE). The first supercritical fluid and the second supercritical fluid are high-temperature, high-pressure fluids formed from nitrogen (N2), carbon dioxide (CO2), or mixtures thereof. The pressure of the first supercritical fluid is greater than that of the second supercritical fluid, with the pressure of the first supercritical fluid between 10 and 20 bar and the pressure of the second supercritical fluid between 5 and 15 bar. This results in a greater amount of gas in the first mixture than in the second mixture, therefore the density and hardness (Shore Hardness C) of the body portion 1 are both greater than those of the buffer substrate 21 and the buffer body 22. The hardness of the body portion 1 is between 40 and 50, and the hardness of the buffer substrate 21 and the buffer body 22 is between 25 and 35. The hardness in this embodiment is measured using a C-type hardness tester.

[0041] In this embodiment, the position of the buffer body 22 corresponds to the ischium of the human buttocks, and each buffer body 22 is formed at the corresponding upper opening 132 and is also kidney-shaped with a wider back and narrower front, thus improving the comfort of the user when riding.

[0042] See also Figure 10 Since each bump 35 is used to form the corresponding through hole 13, and each buffer body 22 is foamed and formed in the corresponding through hole 13, the number of bumps 35 is the same as the number of through holes 13 and buffer bodies 22. Depending on the configuration and requirements of the buffer unit 2, in other variations of this embodiment, the number of bumps 35 may be one or more.

[0043] In this embodiment, each first injection hole 36 and each second injection hole 54 is tapered from the inside out, which can solve the problem of hardened residual material points formed on the body part 1 or the buffer base 21 during demolding. In other variations of this embodiment, the number of first injection holes 36 may be one or more, and the number of second injection holes 54 may be one or more, without limitation.

[0044] In summary, the manufacturing method of the supercritical foamed dual-density cushion of the present invention utilizes supercritical fluid to achieve rapid foaming and molding without the need for additional chemical foaming agents. This method is not only environmentally friendly but also significantly reduces manufacturing time. When the second mixture is injected into the second injection hole 54, the second mixture has sufficient space to flow through the injection groove 124 to the through hole 13, ensuring that the through hole 13 is completely filled and foamed into the buffer body 22. This improves the comfort of the supercritical foamed dual-density cushion, thus effectively achieving the purpose of the present invention.

[0045] The above description is merely an embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the claims and description of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for manufacturing a supercritical foamed dual-density cushion, characterized in that: Includes the following steps: (A): Prepare a female mold, a first male mold, and a second male mold. The female mold includes a concave female inner mold surface and a female mating surface surrounding and connecting the female inner mold surface. The first male mold includes a convex first inner mold surface, an inner mold arc surface surrounding and connecting the first inner mold surface, a convex first nose end surface connecting the inner mold arc surface to the side opposite to the first inner mold surface, a first mating surface surrounding and connecting the inner mold arc surface and the first nose end surface, at least one protrusion protruding from the first inner mold surface, and a first injection hole formed on the first inner mold surface. The second male mold has a convex second inner mold surface, a second nose end surface connecting the second inner mold surface, a second mating surface surrounding and connecting the second inner mold surface and the second nose end surface, and a second injection hole formed on the second inner mold surface. (B): The first male mold is combined with the female mold, the first mating surface of the first male mold abuts against the female mating surface of the female mold, the at least one protrusion abuts against the female inner mold surface, and the first inner mold surface, the inner mold arc surface, the first nose end surface and the female inner mold surface together define the first mold cavity. (C): The thermoplastic material is melted and mixed with a first supercritical fluid to form a first mixture. The first mixture is injected into the first mold cavity through the first injection hole and foamed to form a body part. The body part includes a top surface abutting against the inner mold surface and a bottom surface opposite to the top surface. The bottom surface of the body part has a first surface segment abutting against the first inner mold surface, an arc surface segment surrounding and connecting the first surface segment and abutting against the arc surface of the inner mold, and a lower nose end face segment connected to the arc surface segment and abutting against the first nose end face. The first surface segment forms at least one through hole penetrating to the top surface of the body part. The first surface segment is concave and defines an injection groove communicating with the at least one through hole. The at least one protrusion penetrates the at least one through hole. (D): Remove the first male mold, and combine the second male mold with the female mold. The second mating surface of the second male mold abuts against the female mating surface of the female mold. The inner mold arc surface abuts against the arc surface segment. The second inner mold surface, the second nose end surface, and the female inner mold surface together define the second mold cavity. The second injection hole is adjacent to the injection groove. (E): The thermoplastic material is melted and mixed with a second supercritical fluid to form a second mixture. The second mixture is injected into the second mold cavity through the second injection hole. A portion of the second mixture is foamed in the injection groove to form a buffer substrate with a density less than that of the main body. Another portion is foamed in the at least one through hole to form at least one buffer body with the same density as the buffer substrate. The main body, the buffer substrate and the at least one buffer body are combined to form a supercritical foamed dual-density pad.

2. The method for manufacturing a supercritical foamed dual-density cushion according to claim 1, characterized in that: In step (A), the first nose end face is connected to the front side of the inner mold arc surface and extends forward in a gradually tapering manner. The first male mold includes two protrusions protruding from the first inner mold surface and located on the left and right sides of the first injection hole, respectively. In step (B), the protrusions abut against the female inner mold surface. In step (C), the first surface segment forms two through holes spaced apart from left to right. In step (E), the second mixture fills the through holes and foams to form two buffer bodies.

3. The method for manufacturing a supercritical foamed dual-density pad according to claim 1, characterized in that: In step (E), the left and right width of the buffer base gradually narrows from the rear end of the body portion and extends forward to the lower nose end face segment.

4. The method for manufacturing a supercritical foamed dual-density pad according to claim 1, characterized in that: In step (D), the minimum distance between the second inner mold surface and the first surface segment of the body part is greater than or equal to 5 mm.

5. The method for manufacturing a supercritical foamed dual-density pad according to claim 1, characterized in that: In step (A), the first injection hole and the second injection hole are tapered from the inside out.

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