Soft skin for foam injection molding

Abstract

The present disclosure relates to articles and methods resulting from injection molding. More particularly, to articles and methods resulting from injection molding that provide an overmolded skin-foam layer on a selected substrate surface in a variety of vehicle applications.

Description

Technical Field

[0001] This disclosure relates to articles and methods produced by injection molding. More specifically, it relates to articles and methods produced by injection molding that provide a molded skin-foam layer over a selected substrate surface for various vehicle applications. Background Technology

[0002] Core-back injection molding refers to a general process in which molten polymer resin, including a foaming agent, is injected into a mold, and then the mold is opened or the core is removed to increase the size of the mold cavity, thereby promoting foaming and reducing density. There remains a need in the art to develop injection molding processes that rely on core-back injection molding to provide a higher quality skin-foam layer that can more effectively overmolded onto a selected substrate surface. Such a higher quality skin-foam layer on the selected substrate surface can then be used to produce vehicle interior trim panels of improved quality. Summary of the Invention

[0003] A method for forming injection-molded parts using an injection mold having a first half-mold, a second half-mold, and a cavity between the first and second half-molds. A substrate having a surface is then formed or disposed in the mold, with an initial spacing of 2.0 mm to 4.0 mm from the surface of the substrate set within the cavity. A thermoplastic elastomer containing a chemical foaming agent is then injected into the initial spacing of the cavity and onto the surface of the substrate. The thermoplastic elastomer used is characterized by a tensile viscosity (η) of 100 Pascal-second to 500 Pascal-second (Pa-S). e The molding process then continues as follows: a first delay time is selected and applied before increasing the cavity spacing, and then the initial cavity spacing is increased by 1.0 mm to 6.0 mm, and a skin-foam layer is formed on the surface of the substrate. Optionally, a second stage delay time may then be selected and applied before reducing the cavity spacing, and then the cavity spacing is reduced by 0.1 mm to 1.5 mm.

[0004] A method for forming an injection-molded part using an injection mold, the injection mold comprising a first half-mold and a second half-mold and a cavity between the first half-mold and the second half-mold, including a movable mold core. A substrate having a surface is then formed or disposed in the mold, and an initial spacing of 2.0 mm to 4.0 mm is set in the cavity from the surface of the substrate. A thermoplastic elastomer containing a chemical foaming agent is then injected into the cavity at the initial spacing and onto the surface of the substrate. The thermoplastic elastomer used indicates a tensile viscosity (η) from 100 Pa-seconds (Pa-S) to 500 Pa-S. eThe molding process continues as follows: a first delay time is selected and applied, and then the initial cavity spacing is increased by 1.0 mm to 6.0 mm by withdrawing the mold core, and a skin-foam layer is formed on the surface of the substrate. Optionally, a second stage delay time may then be selected and applied before reducing the cavity spacing, and then the cavity spacing is reduced by 0.1 mm to 1.5 mm. Attached Figure Description

[0005] Figure 1 Images are provided of the skin-foam layer formed by SR65A, which undergoes a 4.0-second delay before the core is extracted at 0.5 inches / second.

[0006] Figure 2 Images of the skin-foam layer formed by SR65A are provided, which also undergoes a 4.0-second delay before the core is extracted at 1.0 inches / second.

[0007] Figure 3 Images are provided of the skin-foam layer formed by SR65A, which underwent a 12.0-second delay before the core was extracted at 0.5 inches per second.

[0008] Figure 4 Images of the skin-foam layer formed by SR65A are provided, which also undergoes a 12.0-second delay before the core is extracted at 1.0 inches / second.

[0009] Figure 5 Images are provided of the skin-foam layer formed by the Trinseo 882, which underwent a 4.0-second delay before the core was extracted at 0.5 inches per second.

[0010] Figure 6 Images are provided of the skin-foam layer formed by the Trinseo 882, which also underwent a 4.0-second delay before the core was extracted at 1.0 inches per second.

[0011] Figure 7 Images are provided of the skin-foam layer formed by the Trinseo 882, which underwent a 12.0-second delay before the core was extracted at 0.5 inches per second.

[0012] Figure 8 Images are provided of the skin-foam layer formed by the Trinseo 882, which also underwent a 12.0-second delay before the core was extracted at 1.0 inches per second.

[0013] Figure 9Images are provided of the skin-foam layer formed by SR65A, which undergoes a 12.0-second mold opening delay, then opens the mold at 0.5 inches / second to a cavity spacing of 4.23 mm, followed by a 0.1-second mold closing delay, and then closes the mold at 0.5 inches / second to a cavity spacing of 3.76 mm.

[0014] Figure 10 Images are provided of the skin-foam layer formed by SR65A, which undergoes a 12.0-second mold opening delay, then opens the mold at 0.5 inches / second to a cavity spacing of 4.80 mm, followed by a 0.1-second mold closing delay, and then closes the mold at 0.5 inches / second to a cavity spacing of 3.76 mm.

[0015] Figure 11 Images are provided of the skin-foam layer formed by SR65A, which undergoes a 12.0-second mold opening delay, then opens the mold at 0.5 inches / second to a cavity spacing of 4.80 mm, followed by a 0.1-second mold closing delay, and then closes the mold at 0.5 inches / second to a cavity spacing of 3.25 mm.

[0016] Figure 12 Images are provided of the skin-foam layer formed by SR65A, which undergoes a 12.0-second mold opening delay, then opens the mold at 0.5 inches / second to a cavity spacing of 4.80 mm, followed by a 0.5-second mold closing delay, and then closes the mold at 2.0 inches / second to a cavity spacing of 4.76 mm.

[0017] Figure 13 Images are provided of the skin-foam layer formed by SR65A, which undergoes a 10.0-second mold opening delay, then opens the mold at 0.5 inches / second to a cavity pitch of 4.23 mm, followed by a 0.1-second mold closing delay, and then closes the mold at 0.5 inches / second to a cavity pitch of 3.76 mm. Detailed Implementation

[0018] First, the formation of a skin-foam layer on the surface of a substrate insert is described, preferably achieved by expanding the mold cavity using an injection core-removal process, which is preferably achieved by using a movable mold core. As described above, core-removal injection molding refers to the general process of injecting molten polymer resin including a foaming agent into a mold, and then opening the mold or removing the mold core to increase the size of the mold cavity, thereby promoting foaming and reducing density.

[0019] More specifically, a substrate having a surface for forming the skin-foam layer is first formed or pre-formed in a mold, then placed in the mold, and molten polymer resin including a chemical blowing agent (CFA) is injected and overmolded onto the surface of the substrate. A selected delay time is then applied, and a movable mold core is then withdrawn to expand the mold cavity.

[0020] The initial cavity spacing from the surface of the inserted substrate is preferably in the range of 2.0 mm to 4.0 mm, including all values ​​and increments therein. Therefore, the initial cavity spacing from the surface of the inserted substrate can preferably be 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, or 4.0 mm. The chemical foaming agent is then preferably activated during cavity expansion to release gas, allowing foaming in the expanding cavity and forming a reduced density and cell type region near the surface of the substrate and beneath the formed skin layer. The cavity itself is preferably expanded by a cavity expansion distance in the range of 1.0 mm to 6.0 mm, including all values ​​and increments therein, which is preferably achieved by the retraction of a movable core. Therefore, cavity expansion can preferably be 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, 5.0 mm, 5.5 mm, or 6.0 mm. For a more preferred cavity expansion range, it may include, for example, 2.0 mm to 6.0 mm, or 2.0 mm to 5.0 mm, or 2.0 mm to 4.0 mm, or even 1.0 mm to 5.0 mm, or 1.0 mm to 4.0 mm, or 1.0 mm to 3.0 mm.

[0021] The resulting skin-foam layer now adheres to the substrate, creating a component that begins at the surface of the substrate, extends into the foam layer, and then into the skin layer. Therefore, such substrate-foam-skin components are suitable for use as automotive trim parts, such as dashboards, door panels, armrests, etc. It is worth noting that, optionally, this paper considers the use of back pressure in the mold to control gas release, thereby optimizing the surface quality of the skin formed above the foam area. Furthermore, it is considered that a microcontroller program can be used to maintain pressure during the injection of the molten polymer to ensure relatively more uniform filling and expansion of the chemical foaming agent.

[0022] Preferably, the resin used herein to form the skin-foam layer is selected from thermoplastic elastomer resins that indicate certain preferred rheological properties. More specifically, the preferred rheological properties herein refer to the desired tensile viscosity (η). e The tensile viscosity (η) is the ratio of tensile stress to tensile strain, and thus indicates the relative resistance of the molten resin to tensile or elongation deformation. In this paper, the tensile viscosity (η) is conveniently calculated based on data from a capillary rheometer measured using the Cogswell method. eThat is, the polymer resin is introduced into the test chamber of a capillary rheometer heated to 230°C. Test chambers with an L / D (length-to-diameter ratio) of 5 and an L / D ratio of 20 are used. The applied shear rate range is 360 seconds. -1 Up to 10,000 seconds -1 The pressure drop across the die head was measured at each flow rate, and viscosity-shear rate data were calculated. Twenty (20) shear scans were performed. The Weissenberg-Rabinowitsch correction was applied, and the Cogswell equation was used to calculate the tensile viscosity relative to the tensile rate.

[0023] Therefore, the tensile viscosity of the polymer resin preferred herein for forming the skin-foam layer is preferably in the range of 100 Pascal-seconds (Pa-S) to 500 Pa-S, including all values ​​therein and increments. Thus, for example, the tensile viscosity (η) of the thermoplastic polymer elastomer resin preferred herein is... e It may have values ​​from 100 Pa-S to 400 Pa-S, or from 100 Pa-S to 300 Pa-S, or from 100 Pa-S to 200 Pa-S. Furthermore, as a further example, the thermoplastic polymer elastomer resin may have tensile viscosities of 100 Pa-S, 150 Pa-S, 200 Pa-S, 250 Pa-S, 300 Pa-S, 350 Pa-S, 400 Pa-S, 350 Pa-S, or 500 Pa-S.

[0024] It should be noted that the thermoplastic elastomer (TPE) described herein can be understood as a resin that can be repeatedly processed by injection molding. Furthermore, TPE may contain blends or alloys of crystalline and amorphous polymers, or contain block copolymers comprising blocks of crystalline and amorphous domains in the polymer chains. Therefore, TPE can elastically deform and recover under tensile or compressive stress, for example, returning to its undeformed shape. Therefore, preferably, TPE may comprise styrene block copolymers, such as styrene-ethylene-butadiene-styrene (SEBS) type block copolymers. Such resins are preferably obtained from Jing Yin Grand Elastomer Co., Ltd., under the name SR65A.

[0025] Therefore, the TPE used to form the skin-foam layer preferably contains a chemical blowing agent (CFA). A chemical blowing agent is a reagent that is solid or liquid at room temperature and decomposes at a specific temperature upon heating to release gases (e.g., nitrogen or carbon dioxide). The level of CFA in the thermoplastic elastomer resins described herein is preferably in the range of 1.0% (by weight) to 5.0% (by weight), including all values ​​and increments therein. Therefore, a particularly preferred CFA level in the thermoplastic elastomer resin is in the range of 2.0% (by weight) to 4.0% (by weight), and even more preferably, a CFA level of 3.0% (by weight) + / - 0.5% (by weight). A particularly preferred CFA is ACBA100 from Uniform Color (Audia Company).

[0026] The substrate (on which TPE resin is introduced during the injection molding process followed by a core-removal process to provide the formation of the outer foam layer) preferably comprises those polymeric resins commonly used to form automotive trim parts. These include, but are not limited to, blends or alloys of acrylonitrile-butadiene-styrene (ABS) and polycarbonate (PC) (PC / ABS). Additionally, the substrate may comprise thermoplastic polyolefins (TPO), which preferably include blends of polypropylene and EPDM rubber as well as polyethylene. A particularly preferred resin for the substrate (which may be formed or placed in a mold) comprises a talc-filled PP material, named ADX-1316, available from Advanced Composited Inc. This talc-filled PP material exhibits an indicated melt flow rate (ISO 1133) of 17 g / 10 min, a specific gravity (ISO 1183) of 1.012, a tensile yield strength (ISO 527) of 27.5 MPa, a flexural modulus (ISO 178) of 2250 MPa, and a notched Izod impact strength (ISO 75) of 6 kJ / m² at 23°C. 2 The heat distortion temperature (ISO 75) at 0.45 MPa is 116 °C and the molding shrinkage (ISO 294) is 10-13 mm / 1000 mm. Another particularly preferred resin includes glass fiber reinforced polypropylene (20 wt%) available from Celanese as Celstran® PP-GF020-02 Black. Such a material indicates a tensile modulus (ISO 527-1 / 2) of 5000 MPa, a flexural modulus (ISO 178) of 4900 MPa, and a Charpy impact strength (ISO 179 / 1eU) of 45 kJ / m² at 23 °C. 2 The heat distortion temperature (ISO 75-1 / 2) at 1.8 MPa is 158℃.

[0027] The preferred core-removal injection molding process involves placing the substrate in a mold and then introducing a thermoplastic elastomer containing a chemical foaming agent with an tensile viscosity in the range of 100 Pa⁻¹ to 500 Pa⁻¹. The initial cavity spacing is 2.0 mm to 4.0 mm. A delay time is then selected and applied, followed by expansion of the mold cavity (core removal). The selected delay time is preferably in the range of 2.0 seconds to 15 seconds, including all individual values ​​and increments therein. Therefore, the delay time can be 2.0 seconds, 3.0 seconds, 4.0 seconds, 5.0 seconds, 6.0 seconds, 7.0 seconds, 8.0 seconds, 9.0 seconds, 10.0 seconds, 11.0 seconds, 12.0 seconds, 13.0 seconds, 14.0 seconds, and 15.0 seconds. A more preferred delay time range includes 4.0 seconds to 12.0 seconds. After such a delay, the initial cavity spacing is preferably expanded by an expansion distance ranging from 1.0 mm to 6.0 mm, and the core extraction speed is preferably in the range of 0.1 inch / second to 1.5 inch / second, including all individual values ​​and increments therein. Therefore, the core can be extracted at speeds of 0.1 inch / second, 0.2 inch / second, 0.3 inch / second, 0.4 inch / second, 0.5 inch / second, 0.6 inch / second, 0.7 inch / second, 0.8 inch / second, 0.9 inch / second, 1.0 inch / second, 1.1 inch / second, 1.2 inch / second, 1.3 inch / second, 1.4 inch / second, or 1.5 inch / second.

[0028] As a result of the above injection molding process, a skin-foam layer is formed on the surface of a given substrate. Therefore, the thermoplastic elastomer can be characterized by a preferred foaming ratio, which is the initial thickness of the thermoplastic elastomer introduced into the mold before the core is extracted, divided by the final thickness of the foamed thermoplastic layer. Therefore, the average foaming ratio herein preferably falls within the range of 2.0 to 3.0, including all values ​​and increments therein. Thus, the average foaming ratio can be 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3.0. A particularly preferred average foaming ratio herein is 2.0 to 2.5. The formed skin itself also preferably has a thickness in the range of 0.5 mm to 1.5 mm, including all individual values ​​and increments therein. Therefore, the skin layer above the foam can have a thickness of 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, or 1.5 mm. Particularly preferred skin thicknesses fall within the range of 0.5 mm to 1.0 mm.

[0029] The skin-foam layer formed on the surface of a substrate according to the invention disclosed herein undergoes testing according to ASTM D3574-17 ( Standard test methods for flexible porous materials – sheet-like, bonded and molded polyurethane foamsThe test involves deforming the skin-foam specimen to a specified deformation and measuring the percentage recovery to its original thickness at ambient temperature (15°C–25°C) and at an elevated temperature (80°C). The skin-foam layer as described herein indicates at least 80% of the ASTM D3574-17 recovery percentage at ambient temperature. More preferably, the ASTM D3574-17 recovery percentage is in the range of 80% to 95%, inclusive of all values ​​and increments therein. The skin-foam layer also indicates at least 50% of the ASTM D3574-17 recovery percentage at a temperature of 80°C. More preferably, it is in the range of 50% to 80%, inclusive of all values ​​and increments therein.

[0030] According to the invention disclosed herein, the skin-foam layer formed on the surface of the substrate undergoes treatment in accordance with ATSM F1957-99 ( Standard test method for hardness of composite foam - hardness tester The test involves measuring the penetration of a specific indenter into the sample under specified conditions. The composite foam hardness (CF) is inversely proportional to the penetration of the indenter into the sample, such that a higher CF value indicates higher hardness and shallower penetration. The skin-foam layer as described herein indicates an ASTM F1957-99 CF value of at least 60. More preferably, the skin-foam layer may have an ASTM F1957-99 CF value in the range of 60 to 75, including all values ​​and increments thereof.

[0031] Optionally, in conjunction with the above embodiments, a second-stage mold-closing process may be introduced after the method of increasing the cavity spacing described herein. This second-stage mold-closing process includes a second-stage delay time, preferably in the range of 0.1 seconds to 5.0 seconds, prior to mold closing. Thus, the second-stage delay time can be understood as the time after the mold has expanded and before the cavity spacing is reduced. The cavity spacing is then reduced, preferably falling within the range of 0.1 mm to 1.5 mm, and mold closing is performed at a preferred closing speed of 0.1 inch / second to 2.5 inch / second. It has been observed that this optional second-stage mold-closing process, among other things, provides a relatively more consistent composite foam stiffness (CF) value and a relatively more consistent thickness measurement for the resulting skin-foam layer overmolded onto the selected substrate surface.

[0032] Expanding on the above, the second-stage delay time preferably falls within the range of 0.1 seconds to 5.0 seconds, including all individual values ​​and increments. Therefore, the second-stage delay time can be 0.1 seconds, 0.2 seconds, 0.3 seconds, 0.4 seconds, 0.5 seconds, 0.6 seconds, 0.7 seconds, 0.8 seconds, 0.9 seconds, 1.0 seconds, 1.1 seconds, 1.2 seconds, 1.3 seconds, 1.4 seconds, 1.5 seconds, 1.6 seconds, 1.7 seconds, 1.8 seconds, 1.9 seconds, 2.0 seconds, 2.1 seconds, 2.2 seconds, 2.3 seconds, 2.4 seconds... The time intervals are 2.5 seconds, 2.6 seconds, 2.7 seconds, 2.8 seconds, 2.9 seconds, 3.0 seconds, 3.1 seconds, 3.2 seconds, 3.3 seconds, 3.4 seconds, 3.5 seconds, 3.6 seconds, 3.7 seconds, 3.8 seconds, 3.9 seconds, 4.0 seconds, 4.1 seconds, 4.2 seconds, 4.3 seconds, 4.4 seconds, 4.5 seconds, 4.6 seconds, 4.7 seconds, 4.8 seconds, 4.9 seconds, and 5.0 seconds. A more preferred second-stage delay range includes 0.1 seconds to 4.0 seconds.

[0033] The second-stage speed is preferably in the range of 0.1 inch / second to 2.5 inch / second, including all individual values ​​and increments therein. Therefore, the second-stage mold-closing speed can be 0.1 inch / second, 0.2 inch / second, 0.3 inch / second, 0.4 inch / second, 0.5 inch / second, 0.6 inch / second, 0.7 inch / second, 0.8 inch / second, 0.9 inch / second, 1.0 inch / second, 1.1 inch / second, 1.2 inch / second, 1.3 inch / second, 1.4 inch / second, 1.5 inch / second, 1.6 inch / second, 1.7 inch / second, 1.8 inch / second, 1.9 inch / second, 2.0 inch / second, 2.1 inch / second, 2.2 inch / second, 2.3 inch / second, 2.4 inch / second, and 2.5 inch / second. More preferably, the second-stage mold-closing speed is in the range of 0.1 inch / second to 1.0 inch / second.

[0034] During mold closing, the cavity spacing is preferably reduced by a distance in the range of 0.1 mm to 1.5 mm, including all individual values ​​and increments therein. Therefore, the cavity spacing can preferably be reduced by a distance of 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, or 1.5 mm.

[0035] Unrestricted instance

[0036] Thermoplastic elastomer (designated SR65A) from Jing Yin Grand Elastomer Co., Ltd. is injection molded over a selected substrate, followed by core extraction to provide a skin-foam layer attached to the substrate, as disclosed herein. Unless otherwise stated, the molding parameters are those described herein. More specific parameters for such a process and the characterization features of the resulting skin-foam layer are summarized in Table 1 below:

[0037] Table 1

[0038]

[0039] Next Figure 1 Images of the skin-foam layer are provided, which were subjected to a 4.0-second delay before the core was extracted at 0.5 inches / second. Furthermore, based on the features noted above in Table 1, the foam indicated cavitation of 4 during visual analysis. A value of 1 indicates observed fully cracked foam layers, a value of 2 indicates observed cavitation (relatively large voids), a value of 3 indicates observed merged pores, and a value of 4 indicates observed no cavitation. Figure 2 Images of the epidermis-foam layer are provided, which also undergo a 4.0-second delay before the core is extracted at 1.0 inches / second. Figure 3 Images of the skin-foam layer are provided, which undergo a 12.0-second delay before the core is extracted at 0.5 inches / second. Figure 4 Images of the epidermis-foam layer are provided, which also undergo a 12.0-second delay before the core is extracted at 1.0 inches / second.

[0040] The second working embodiment involves the use of a thermoplastic elastomer (identified as Tinseo882, available from Trinseo), which is similarly injection-molded over a selected substrate, followed by core extraction to provide a skin-foam layer again attached to the substrate, as disclosed herein. Unless otherwise stated, the molding parameters are those described herein. Table 2 below summarizes more specific parameters for such a process and the characterization features of the resulting skin-foam layer:

[0041] Table 2

[0042]

[0043] Next Figure 5 Images of the epidermis-foam layer are provided, which are subjected to a 4.0-second delay before the core is extracted at 0.5 inches / second. Figure 6 Images of the epidermis-foam layer are provided, which also undergo a 4.0-second delay before the core is extracted at 1.0 inches / second. Figure 7Images of the skin-foam layer are provided, which undergo a 12.0-second delay before the core is extracted at 0.5 inches / second. Figure 8 Images of the epidermis-foam layer are provided, which also undergo a 12.0-second delay before the core is extracted at 1.0 inches / second.

[0044] Table 3 below provides ASTM D3574-17 for skin-foam layers formed according to the following processes ( Used for soft Standard test methods for porous materials - sheet, bonded and molded polyurethane foams Results: An initial spacing of 2.0 mm to 4.0 mm was set in the mold cavity from the surface of the substrate; a thermoplastic elastomer containing a chemical foaming agent was injected into the mold cavity at the initial spacing and onto the surface of the substrate, wherein the thermoplastic elastomer indicated a tensile viscosity of 100 Pascal-seconds (Pa-S) to 500 Pascal-seconds (Pa-S); a delay time was selected and applied before increasing the initial spacing of the mold cavity; and the initial spacing of the mold cavity was increased by 2.0 mm to 4.0 mm, forming a skin-foam layer on the surface of the substrate. The percentage recovery under ambient (room temperature) conditions of about 15°C to 25°C and at an elevated temperature of 80°C is reported.

[0045] Table 3

[0046] ASTM D3574-17 test for skin-foam layer

[0047]

[0048] Optional mold closing working example

[0049] Thermoplastic elastomer (identified as SR65A) from Jing Yin Grand Elastomer Co., Ltd. was again injection-molded over the selected substrate with 3.0% (by weight) of chemical foaming agent (ACBA 100), followed by core extraction and, optionally, a second-stage delay time, and then the cavity spacing was reduced by a selected amount. The initial mold spacing was 3.0 mm. The results are summarized in Table 4 below, which provides a table of relevant molding parameters and observed foaming ratios, composite foam stiffness (CF) values, and skin thickness.

[0050] Table 4

[0051] Molding parameters for optional mold closing process

[0052]

[0053] Figure 9Images are provided showing the formation of the skin-foam layer as follows: thermoplastic elastomer SR65A and 3% by weight of foaming agent ACBA 100 are injected into an injection mold cavity with an initial pitch of 3.0 mm, followed by a 12.0-second mold opening delay, then the mold is opened at 0.5 inches / second to a cavity pitch of 4.23 mm, followed by a 0.1-second mold closing delay, and then the mold is closed at 0.5 inches / second to a cavity pitch of 3.76 mm.

[0054] Figure 10 Images are provided showing the formation of the skin-foam layer as follows: thermoplastic elastomer SR65A and 3% by weight of foaming agent ACBA 100 are injected into an injection mold cavity with an initial pitch of 3.0 mm, followed by a 12.0-second mold opening delay, then the mold is opened at 0.5 inches / second to a cavity pitch of 4.80 mm, followed by a 0.1-second mold closing delay, and then the mold is closed at 0.5 inches / second to a cavity pitch of 3.76 mm.

[0055] Figure 11 Images are provided showing the formation of the skin-foam layer as follows: thermoplastic elastomer SR65A and 3% by weight of foaming agent ACBA 100 are injected into an injection mold cavity with an initial pitch of 3.0 mm, followed by a 12.0-second mold opening delay, then the mold is opened at 0.5 inches / second to a cavity pitch of 4.80 mm, followed by a 0.1-second mold closing delay, and then the mold is closed at 0.5 inches / second to a cavity pitch of 3.25 mm.

[0056] Figure 12 Images are provided showing the formation of the skin-foam layer as follows: thermoplastic elastomer SR65A and 3% by weight of foaming agent ACBA 100 are injected into an injection mold cavity with an initial pitch of 3.0 mm, followed by a 12.0-second mold opening delay, then the mold is opened at 0.5 inches / second to a cavity pitch of 4.80 mm, followed by a 0.5-second mold closing delay, and then the mold is closed at 2.0 inches / second to a cavity pitch of 3.76 mm.

[0057] Figure 13 Images are provided showing the formation of the skin-foam layer as follows: thermoplastic elastomer SR65A and 3% by weight of foaming agent ACBA 100 are injected into an injection mold cavity with an initial pitch of 3.0 mm, followed by a 10.0-second mold opening delay, then the mold is opened at 0.5 inches / second to a cavity pitch of 4.23 mm, followed by a 0.1-second mold closing delay, and then the mold is closed at 0.5 inches / second to a cavity pitch of 3.76 mm.

[0058] As will now be understood, the above embodiments of the invention relate to injection molding and forming a skin-foam layer via a core-removal process, the skin-foam layer preferably being applied to a selected and relatively rigid substrate. The skin-foam layer is also recyclable. The resulting product, a substrate-foam-skin component, is particularly suitable for manufacturing vehicle trim parts, covering a skin surface with desired tactile and visual properties with a foam layer, wherein the foam layer itself is supported by the substrate.

Claims

1. A method for forming an injection-molded part, comprising: An injection mold is provided, the injection mold having a first half-mold and a second half-mold and a cavity between the first half-mold and the second half-mold; A substrate having a surface is formed or disposed in the mold; A distance of 2.0 mm to 4.0 mm from the surface of the substrate is set in the mold cavity; A thermoplastic elastomer containing a chemical foaming agent is injected into the gap of the mold cavity and onto the surface of the substrate, wherein the thermoplastic elastomer indicates a tensile viscosity of 100 Pascal-second (Ps-S) to 500 Pascal-second (Pa-S). Before increasing the cavity spacing, a first delay time is selected and applied; and The cavity spacing is increased from 1.0 mm to 6.0 mm, and a skin-foam layer is formed on the surface of the substrate.

2. The method according to claim 1, wherein the first delay time is 2.0 seconds to 15.0 seconds.

3. The method of claim 1, wherein the increase in the cavity spacing is performed at a rate of 0.1 inches / second to 1.5 inches / second.

4. The method of claim 1, wherein the thermoplastic elastomer comprises a block copolymer.

5. The method of claim 4, wherein the thermoplastic block copolymer comprises a styrene block copolymer.

6. The method of claim 5, wherein the styrene block copolymer comprises a styrene-ethylene-butadiene block copolymer.

7. The method of claim 1, wherein the chemical foaming agent is present in the thermoplastic elastomer at a level of 1.0% (by weight) to 5.0% (by weight).

8. The method of claim 1, wherein the substrate is a material selected from acrylonitrile-butadiene-styrene resin, polycarbonate blends or thermoplastic polyolefins.

9. The method of claim 1, wherein the epidermal layer has a thickness in the range of 0.5 mm to 1.5 mm.

10. The method of claim 1, wherein the skin-foam layer indicates at least 80% of the ASTM D 3574-17 recovery percentage at ambient temperature.

11. The method of claim 1, wherein the skin-foam layer indicates at least 50% of the ASTM D3574-17 recovery percentage at a temperature of 80°C.

12. The method of claim 1, wherein the skin foam layer indicates at least 80% ASTM D 3574-17 recovery percentage at ambient temperature and at least 50% ASTM D 3574-17 recovery percentage at 80°C.

13. The method of claim 1, further comprising: Before reducing the cavity spacing, a second-stage delay time is selected and applied; and The cavity spacing is reduced from 0.1 mm to 1.5 mm to achieve the desired component thickness.

14. The method of claim 13, wherein the second stage delay time is in the range of 0.1 seconds to 5.0 seconds.

15. The method of claim 13, wherein the reduction of the cavity spacing is performed at a rate ranging from 0.1 inches / second to 2.5 inches / second.

16. A method for forming an injection-molded part, comprising: An injection mold is provided, the injection mold comprising a first half mold and a second half mold and a cavity between the first half mold and the second half mold, including a movable mold core; A substrate having a surface is formed or disposed in the mold; A distance of 2.0 mm to 4.0 mm from the surface of the substrate is set in the mold cavity; A thermoplastic elastomer containing a chemical foaming agent is injected into the gap of the mold cavity and onto the surface of the substrate, wherein the thermoplastic elastomer indicates a tensile viscosity of 100 Pascal-seconds (Pa-S) to 500 Pa-S. Before increasing the cavity spacing, a first delay time is selected and applied; and The cavity spacing is increased by 1.0 mm to 6.0 mm by removing the mold core, and a skin-foam layer is formed on the surface of the substrate.

17. The method of claim 16, wherein the first delay time is 2.0 seconds to 15.0 seconds.

18. The method of claim 16, wherein the increase in the initial cavity spacing is performed at a rate of 0.1 inches / second to 1.5 inches / second.

19. The method of claim 16, wherein the thermoplastic elastomer comprises a block copolymer.

20. The method of claim 19, wherein the thermoplastic block copolymer comprises a styrene block copolymer.

21. The method of claim 20, wherein the styrene block copolymer comprises a styrene-ethylene-butadiene block copolymer.

22. The method of claim 16, wherein the chemical foaming agent is present in the thermoplastic elastomer at a level of 1.0% (by weight) to 5.0% (by weight).

23. The method of claim 16, wherein the substrate is selected from the group consisting of acrylonitrile-butadiene-styrene resin, polycarbonate blends, or thermoplastic polyolefins.

24. The method of claim 16, wherein the epidermal layer has a thickness in the range of 0.5 mm to 1.5 mm.

25. The method of claim 16, wherein the skin-foam layer indicates at least 80% of the ASTM D 3574-17 recovery percentage at ambient temperature.

26. The method of claim 16, wherein the skin-foam layer indicates at least 50% of the ASTM D 3574-17 recovery percentage at a temperature of 80°C.

27. The method of claim 16, wherein the skin foam layer indicates at least 80% ASTM D 3574-17 recovery percentage at ambient temperature and at least 50% ASTM D 3574-17 recovery percentage at 80°C.

28. The method of claim 16, further comprising: Before reducing the cavity spacing, a second-stage delay time is selected and applied; and By inserting the mold core, the cavity spacing is reduced from 0.1 mm to 1.5 mm, and the desired component thickness is achieved.

29. The method of claim 28, wherein the second stage delay time is in the range of 0.1 seconds to 5.0 seconds.

30. The method of claim 28, wherein the reduction of the cavity spacing is performed at a rate ranging from 0.1 inches / second to 2.5 inches / second.

31. A method for forming an injection-molded part, comprising: An injection mold is provided, the injection mold having a first half-mold and a second half-mold and a cavity between the first half-mold and the second half-mold; A substrate having a surface is formed or disposed in the mold; A cavity spacing of 2.0 mm to 4.0 mm is set in the cavity to be between the cavity distance from the surface of the substrate; A thermoplastic elastomer containing a chemical foaming agent is injected into the initial spacing of the mold cavity and onto the surface of the substrate, wherein the thermoplastic elastomer indicates a tensile viscosity of 100 Pascal-seconds (Pa-S) to 500 Pascal-seconds (Pa-S). Before adding the mold cavity, a first delay time is selected and applied; The cavity spacing is increased by 1.0 mm to 6.0 mm and a skin-foam layer is formed on the surface of the substrate; Before reducing the cavity spacing, a second-stage delay time is selected and applied; and The cavity spacing is reduced from 0.1 mm to 1.5 mm to achieve the desired component thickness.

32. A method for forming an injection-molded part, comprising: An injection mold is provided, the injection mold comprising a first half mold and a second half mold and a cavity between the first half mold and the second half mold, including a movable mold core; A substrate having a surface is formed or disposed in the mold; The cavity spacing between the cavity and the surface of the substrate is set to be 2.0 mm to 4.0 mm. A thermoplastic elastomer containing a chemical foaming agent is injected into the initial spacing of the mold cavity and onto the surface of the substrate, wherein the thermoplastic elastomer indicates a tensile viscosity of 100 Pascal-second (Ps-S) to 500 Pascal-second (Pa-S). Before increasing the cavity spacing, a first delay time is selected and applied; The cavity spacing is increased by 1.0 mm to 6.0 mm by removing the mold core, and a skin-foam layer is formed on the surface of the substrate. Before reducing the cavity spacing, a second-stage delay time is selected and applied; and By inserting the mold core, the cavity spacing is reduced from 0.1 mm to 1.5 mm, and the desired component thickness is achieved.

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