Foamed injection molded soft skin

Abstract

The present disclosure relates to a process and article produced by injection molding. More particularly, a process and article produced by injection molding that provides a skin-foam layer over-molded onto a selected substrate surface for a variety of vehicular applications.

Description

FOAMED INJECTION MOLDED SOFT SKINFIELD

[0001] The present disclosure relates to a process and article produced by injection molding. More particularly, a process and article produced by injection molding that provides a skin-foam layer over-molded onto a selected substrate surface for a variety of vehicular applications.BACKGROUND

[0002] Core-back injection molding refers to the general process of injecting a molten polymer resin including a foaming agent into a mold, followed by opening of the mold, or withdrawal of a mold core, to increase the size of the mold cavity to facilitate foaming and density reduction. The problem remains in the ail for the development of an injection molded procedure that relies upon core-back injection molding which offers a higher quality skin-foam layer that can be more efficiently be over-molded onto a selected substrate surface. Such higher quality skin-foam layer on a selected substrate surface may then be employed to produce improved quality vehicle interior trim panels.SUMMARY

[0003] A method of forming an injection molded pail utilizing an injection mold having a first mold half and a second mold half and a molding cavity between the first mold half and the second mold half. This is followed by forming or positioning a substrate having a surface in said mold and setting an initial spacing of 2.0 mm to 4.0 mm in the mold cavity from the surface of the substrate. One then injects a thermoplastic elastomer containing chemical foaming agent into the initial spacing of the molding cavity and onto the surface of the substrate. The thermoplastic elastomer so employed is characterized as having an extensional viscosity (Tje) of 100 pascal-second to 500 pascal-second (Pa-S). The molding process continues by then selecting and applying a first delay time before increasing themold cavity spacing followed by increasing the molding cavity initial spacing by 1.0 mm to 6.0 mm and forming a skin-foam layer on said surface of the substrate. Optionally, one may then select and apply a second stage delay time before decreasing the mold cavity spacing followed by decreasing the mold cavity spacing by 0.1 mm to 1.5 mm.

[0004] A method of forming an injection molded part utilizing an injection mold comprising a first mold half and a second mold half and a molding cavity between the first mold half and the second mold half, including a movable mold core. This is followed by forming or positioning a substrate having a surface in said mold and setting an initial spacing of 2.0 mm to 4.0 mm in said mold cavity from the surface of said substrate. One then injects a thermoplastic elastomer containing chemical foaming agent into said initial spacing of said molding cavity and onto said surface of said substrate. The thermoplastic elastomer so employed indicates an extensional viscosity (i)e) of 100 pascal-second (Ps-S) to 500 Pa-S. The molding process continues by selecting and applying a first delay time before increasing said initial mold cavity spacing by 1.0 mm to 6.0 mm by withdrawing said mold core and forming a skin-foam layer on said surface of said substrate. Optionally, one may then select and apply a second stage delay time before decreasing the mold cavity spacing followed by decreasing the mold cavity spacing by 0.1 mm to 1.5 mm.FIGURES

[0005] FIG. 1 provides an image of the skin-foam layer formed from SR65A undergoing a 4.0 second delay followed by a withdrawal of the mold care at 0.5 inches / second.

[0006] FIG. 2 provides an image of the skin-foam layer formed from SR65A also undergoing a 4.0 second delay followed by withdrawal of the mold core at 1.0 inches / second.

[0007] FIG. 3 provides an image of the skin-foam layer formed from SR65A undergoing a 12.0 second delay followed by withdrawal of the mold core at 0.5 inches / second.

[0008] FIG. 4 provides an image of the skin-foam layer formed from SR65A also undergoing a 12.0 second delay followed by withdrawal of the mold core at 1.0 inches / second.

[0009] FIG. 5 provides an image of the skin-foam layer formed from Trinseo 882 undergoing a 4.0 second delay followed by a withdrawal of the mold care at 0.5 inches / second.

[0010] FIG. 6 provides an image of the skin-foam layer formed from Trinseo 882 also undergoing a 4.0 second delay followed by withdrawal of the mold core at 1.0 inches / second.

[0011] FIG. 7 provides an image of the skin-foam layer formed from Trinseo 882 undergoing a 12.0 second delay followed by withdrawal of the mold core at 0.5 inches / second.

[0012] FIG. 8 provides an image of the skin-foam layer formed from Trinseo 882 also undergoing a 12.0 second delay followed by withdrawal of the mold core at 1.0 inches / second.

[0013] FIG. 9 provides an image of the skin-foam layer formed from SR65A undergoing a 12.0 second open delay followed by opening of the mold at 0.5 inches per second to a cavity spacing of 4.23 mm and subsequently undergoing a 0.1 second close delay followed by closing of the mold at 0.5 inches per second to a cavity spacing of 3.76 mm.

[0014] FIG. 10 provides an image of the skin-foam layer formed from SR65A undergoing a 12.0 second open delay followed by opening of the mold at 0.5 inches per second to a cavity spacing of 4.80 mm and subsequently undergoing a 0.1 second close delay followed by closing of the mold at 0.5 inches per second to a cavity spacing of 3.76 mm.

[0015] FIG. 11 provides an image of the skin-foam layer formed from SR65A undergoing a 12.0 second open delay followed by opening of the mold at 0.5 inches per second to a cavity spacing of 4.80 mm and subsequently undergoing a 0.1 second close delay followed by closing of the mold at 0.5 inches per second to a cavity spacing of 3.25 mm.

[0016] FIG. 12 provides an image of the skin-foam layer formed from SR65A undergoing a 12.0 second open delay followed by opening of the mold at 0.5 inches per second to a cavity spacing of 4.80 mm and subsequently undergoing a 0.5 second close delay followed by closing of the mold at 2.0 inches per second to a cavity spacing of 4.76 mm.

[0017] FIG. 13 provides an image of the skin-foam layer formed from SR65A undergoing a 10.0 second open delay followed by opening of the mold at 0.5 inches per second a cavity spacing of 4.23 mm and subsequently undergoing a 0.1 second close delay followed by closing of the mold at 0.5 inches per second to a cavity spacing of 3.76 mm.DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0018] Stalling with a description of the formation of the skin-foam layer on the surface of a substrate insert, such is preferably achieved utilizing an injection molding core-back procedure by expansion of the mold cavity, which is preferably achieved by use of a movable mold core. As noted above, core-back injection molding refers to the general process of injecting a molten polymer resin including a foaming agent into a mold, followed by opening of the mold, or withdrawal of a mold core, to increase the size of the mold cavity to facilitate foaming and density reduction.

[0019] More specifically, a substrate having a surface for formation of the skin-foam layer is initially formed in the mold or pre-formed and then positioned in the mold and a molten polymer resin including a chemical foaming agent (CFA) is injected and over-molded onto the surface of the substrate. This is followed by implementation of a selected delay time followed by withdrawal of the movable mold core 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. Accordingly, the initial cavity spacing from the surface of the inserted substrate may 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 mold cavity expansion to release a gas such that the expanded mold cavity allows for foaming and the formation of a reduced density and cellular’ type region proximate the surface of the substrate and beneath the formed skin layer. The mold cavity itself is preferably expanded by a mold 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 retraction of a movable mold core. Accordingly, the mold cavity expansion may preferably

[0021] 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. As for more preferred ranges of mold cavity expansion, such may include, e.g., 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 to 5.0 mm, or 1.0 mm to 4.0 mm, or 1.0 mm to 3.0 mm.

[0022] The skin-foam layer that is formed is therefore now adhered to the substrate and results in a part that proceeds, from the surface of the substrate, into a foam layer followed by a skin layer. Such substrate-foam-skin component is therefore suitable for use as a vehicle trim component, such as an instrument panel, door panel, armrest, etc. It is worth noting that optionally, it is contemplated herein that one may also employ counterpressure in the mold to control the release of gas that is vented to optimize the formed skin surface quality over the foam region. In addition, it is also contemplated that one may utilize a microcontroller program to maintain the pressure during injection of the molten polymer to ensure a relatively more even fill and expansion of the chemical foaming agent.

[0023] Preferably, the resin for the formation of the skin-foam layer herein is selected from a thermoplastic elastomeric resin that indicates certain preferred rheology characteristics. More specifically, the preferred rheology characteristics herein is reference to a desired extensional viscosity (Tje) which is a ratio of extensional stress to extensional strain, and thereby indicates the relative resistance of the molten resin to extensional or elongational deformation. The extensional viscosity (i]e) herein is conveniently calculated based upon measured data of a capillary rheometer using the Cogswell method. Namely, the polymeric resin is introduced into the test barrel of a capillary rheometer heated to a temperature of 230 °C. A test barrel having a L / D (length-to-diameter) ratio of 5 and a L / D ratio of 20 were employed. A range of shear rates applied is from 360 sec-1to 10,000 sec'1and pressure drop across the die is measured for each flow rate and viscosity-shear rate data are calculated. Twenty (20) shear sweeps were employed. The Weissenberg-Rabinowitsch corrections are performed and using Cogswell equations, the extensional viscosity versus extension rate is calculated.

[0024] The extensional viscosity of the polymeric resin that is therefore preferably employed herein for formation of the skin-foam layer has a preferred value in the range of100 pascal-second (Pa-S) to 500 Pa-S, including all values and increments therein. Therefore, by way of example, the extensional velocity (t]e) of the preferred thermoplastic polymeric elastomer resin herein may have a value of 100 Pa-S to 400 Pa-S, or 100 Pa-S to 300 Pa-S, or 100 Pa-S to 200 Pa-S. In addition, by way of further example, the thermoplastic polymeric elastomer resin may have an extensional viscosity 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.

[0025] It should be noted that a thermoplastic elastomer (TPE) herein may be understood as a resin that can be repeatedly processed by injection molding. In addition, a TPE can contain blends or alloys of crystalline and amorphous polymers, or comprise block copolymers, which include blocks of crystalline and amorphous domains in the polymer chain. A TPE can therefore deform elastically under a tensile or compressive stress and recover, such as returning to their undeformed shape. Suitable TPEs may therefore preferably include styrene-block copolymers, e.g., styrene-ethylene-butadiene-styrene (SEBS) type block copolymers. Such resins are preferably obtained from Jing Yin Grand Elastomer Co., Ltd, under the name SR 65A.

[0026] The TPEs that are therefore utilized for formation of the skin-foam layer preferably contain a chemical foaming agent (CFA). A chemical foaming agent is reference to an agent that is solid or liquid at room temperature and on heating, decomposes at a particular temperature to release a gas such as nitrogen or carbon dioxide. The level of CFA in the thermoplastic elastomer resin herein is preferably in the range of 1.0 % (wt.) to 5.0 % (wt.), including all values and increments therein. A particularly preferred level of CFA in the thermoplastic elastomer resin is therefore in the range of 2.0 % (wt.) to 4.0 % (wt.), and an even more preferred level of CFA is 3.0 % (wt.) + / - 0.5 % (wt.). On particularly preferred CFA is ACBA100 from Uniform Color (Audia Company).

[0027] The substrate upon which the TPE resin herein is introduced during injection molding, followed by a core-back procedure to provide for formation of the skin foam layer, preferably include those polymeric resin that are typically utilized for the formation of automotive trim parts. These include but are not limited to acrylonitrile-butadiene- styrene resins (ABS) and polycarbonate (PC) blends or alloys (PC / ABS). In addition, thesubstrate may include a thermoplastic polyolefin (TPO) which preferably includes blends of polypropylene and EPDM rubber and polyethylene. One particularly preferred resin for the substrate, which can be formed or placed in the mold, includes a talc-filled PP material available from Advanced Composited Inc., under the name ADX-1316. Such talc-filled PP material indicates a melt flow (ISO1133) of 17g / 10min, a specific gravity (ISO1183) of 1.012, a tensile yield strength (ISO527) of 27.5 MPa, a flexural modulus (ISO178) of 2250 MPa, a notched izod impact at 23 °C (ISO75) of 6 kJ / m2, a heat deflection temperature at 0.45 MPa (ISO75) of 116 °C and mold shrinkage (ISO 294) of 10-13 mm / lOOOmm. Another particularly preferred resin includes polypropylene reinforced with glass fibers (20 wt. %) available from Celanese as Celstran® PP-GF020-02 Black. Such material indicates a tensile modulus (1SO527-1 / 2) of 5000 MPa, a flexural modulus (ISO 178) of 4900 MPa, Charpy impact strength at 23 ° (ISO179 / leU) of 45 kJ / m2, and a heat distortion temperature at 1.8 MPa (ISO75-1 / 2) of 158 °C.

[0028] Turning to the preferred core-back injection molding procedure, a substrate is placed in the mold, and the thermoplastic elastomer having an extensional viscosity in the range of 100 Pa-S to 500 Pa-S and containing chemical foaming agent is then introduced. The initial cavity spacing is 2.0 mm to 4.0 mm. This is followed by selecting and applying a delay time before expanding the mold cavity (withdrawal of the mold core). The selected delay time is preferably in the range of 2.0 seconds to 15 seconds, including all individual values and increments therein. Accordingly, the delay time may 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 range of delay times includes 4.0 seconds to 12.0 seconds. After such delay time, the mold cavity initial spacing is preferably expanded by an expansion distance in the range of 1 .0 mm to 6.0 mm, and the speed at which one withdraws the mold core is preferably in the range of 0.1 inchcs / scc to 1.5 inchcs / scc, including all individual values and increments therein. Accordingly, the mold core may be withdrawn at 0.1 inches / sec, 0.2 inches / sec, 0.3 inches / sec, 0.4 inches / sec, 0.5 inches / sec, 0.6 inches / sec, 0.7 inches / sec, 0.8 inches / sec,0.9 inches / sec, l.O inches / sec, 1.1 inches / sec, 1.2 inches / sec, 1.3 inches / sec, 1.4 inches / sec, or 1.5 inches / sec.

[0029] As a result of the above injection molding procedure, a skin-foam layer is formed on the surface of a given substrate. The thermoplastic elastomer may therefore be characterized by a preferred foaming ratio, which is reference to the initial thickness of the thermoplastic elastomer introduced into the mold prior to withdrawal of the mold core divided by the final thickness of the thermoplastic layer after foaming. The foaming ratio average herein therefore preferably falls in the range of 2.0 to 3.0, including all values and increments therein. Accordingly, the foaming ratio average may 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 foaming ratio average herein is 2.0 to 2.5. The skin itself that is formed 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 may 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. A particularly preferred skin thickness falls in the range of 0.5 mm to 1.0 mm.

[0030] The skin-foam layer formed on the surface of a substrate according to the invention disclosed herein was subjected to testing according to ASTM D3574-17 (Standard Test Methods For Flexible Cellular Materials-Slab, Bonded and Molded Urethane Foams). The test involved deflecting the skin-foam specimen to a specified deflection and measuring the percent recovery to the original thickness at ambient temperature (15 °C - 25 °C) and elevated temperature (80 °C). The skin-foam layer herein indicated an ASTM D 3574-17 percent recovery of at least 80% at ambient temperature. More preferably, an ASTM D 3574-17 percent recovery in the range of 80 % to 95 %, including all values and increments therein. The skin-foam layer also indicated an ASTM D 3574-17 percent recovery of at least 50% at a temperature of 80 °C. More preferably, in the range of 50% to 80 %, including all values and increments therein.

[0031] The skin-foam layer formed on the surface of a substrate according to the invention disclosed herein was subjected to testing according to ATSM F1957-99 (Standard Test Method for Composite Foam Hardness-Durometer Hardness). The test involvedmeasuring the penetration by a specific indenter when the indenter is forced into the sample under specified conditions. The Composite Foam Hardness (“CF”) is inversely related to the penetration of the indenter into the sample such that a higher CF value indicates a higher hardness and shallower penetration. The skin-foam layer herein indicated an ASTM F1957-99 CF value of at least 60. More preferably, the skin-foam layer may have an ATSM F1957-99 CF value in the range of 60 to 75, including all values and increments therein.

[0032] Optionally, in connection with the embodiments noted above, following the methods herein of increasing the mold cavity spacing, one may introduce a second stage closing procedure. This second stage closing procedure includes a second stage delay time prior to closing that preferably is in the range of 0.1 seconds to 5.0 seconds. The second stage delay time may therefore be understood as the time after the mold has been expanded and before the mold cavity spacing is decreased. This is then followed by decreasing the mold cavity spacing, which preferably falls in the range of 0.1 mm to 1.5 mm, and which mold closing occurs at a preferred mold closing speed of 0.1 inches / second to 2.5 inches / second. Such optional second stage mold-closing procedure was observed to, among other things, provide for relatively more consistent Composite Foam Hardness (“CF”) values and relatively more consistent thickness measurements for the as produced skin-foam layer that is over-molded onto the selected substrate surface.

[0033] Expanding on the above, the second stage delay time is preferably in the range of 0.1 seconds to 5.0 seconds, including all individual values and increments therein. Accordingly, the second stage delay time may be 0.1 sec, 0.2 sec, 0.3 sec, 0.4 sec, 0.5 sec, 0.6 sec, 0.7 sec, 0.8 sec, 0.9 sec, 1.0 sec, 1.1 sec, 1.2 sec, 1.3 sec, 1.4 sec, 1.5 sec, 1.6 sec,1.7 sec, 1.8 sec, 1.9 sec, 2.0 sec, 2.1 sec, 2.2 sec, 2.3 sec, 2.4 sec, 2.5 sec, 2.6 sec, 2.7 sec,2.8 sec, 2.9 sec, 3.0 sec, 3.1 sec, 3.2 sec, 3.3 sec, 3.4 sec, 3.5 sec, 3.6 sec, 3.7 sec, 3.8 sec,3.9 sec, 4.0 sec, 4.1 sec, 4.2 sec, 4.3 sec, 4.4 sec, 4.5 sec, 4.6 sec, 4.7 sec, 4.8 sec, 4.9 sec, and 5.0 sec. A more preferred range of second stage delay times includes 0.1 seconds to 4.0 seconds.

[0034] The second stage speed is preferably in the range of 0.1 inches per second to 2.5 inches per second, including all individual values and increments therein. Accordingly, the second stage mold closing speed may be 0.1 inches / sec, 0.2 inches / sec, 0.3 inches / sec, 0.4 inches / sec, 0.5 inches / sec, 0.6 inches / sec, 0.7 inches / sec, 0.8 inches / sec, 0.9 inches / sec, 1.0 inches / sec, 1.1 inches / sec, 1.2 inches / sec, 1.3 inches / sec, 1.4 inches / sec, 1.5 inches / sec, 1.6 inches / sec, 1.7 inches / sec, 1.8 inches / sec, 1.9 inches / sec, 2.0 inches / sec, 2.1 inches / sec, 2.2 inches / sec, 2.3 inches / sec, 2.4 inches / sec, and 2.5 inches / sec. More preferably, the second stage mold closing speed is in the range of 0.1 inches / sec to 1.0 inches / sec.

[0035] The mold cavity spacing upon closing is preferably decreased by a distance in the range of 0.1 mm to 1.5 mm, including all individual values and increments therein. Accordingly, the distance by which the cavity spacing may preferably be decreased may be 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.Non-Limiting Examples

[0036] A thermoplastic elastomer sourced from Jing Yin Grand Elastomer Co., Ltd., and identified as SR65 A was injection molded over a selected substrate followed by withdrawal of the mold core, providing a skin-foam layer adhered to the substrate, as disclosed herein. Unless otherwise noted, the parameters for molding are those that were described herein. The more specific parameters for such process and the characterizing features of the skinfoam layer that were produced are summarized in Table 1 below:Table 1

[0037] FIG. 1 next provides an image of the skin-foam layer undergoing a 4.0 second delay followed by a withdrawal of the mold care at 0.5 inches / second. In addition, the features noted above in Table 1, this foam indicated a cavitation of 4 upon visual analysis. A cavitation of 1 is reference to the observation of a completely split foam layer, a value of 2 is reference to the observation of cavitation (relatively large voids), a value of 3 is reference to the observation of merged cells, and a value of 4 is reference to the observation of no cavitation. FIG. 2 provides an image of the skin-foam layer also undergoing a 4.0 second delay followed by withdrawal of the mold core at 1.0 inches / second. FIG. 3 provides an image of the skin-foam layer undergoing a 12.0 second delay followed by withdrawal of the mold core at 0.5 inches / second. FIG. 4 provides an image of the skinfoam layer also undergoing a 12.0 second delay followed by withdrawal of the mold core at 1.0 inches / second.

[0038] A second working example involved the use of a thermoplastic elastomer identified as Tinseo 882, available from Trinseo that was similarly injection molded over a selected substrate followed by withdrawal of the mold core, again providing a skin-foam layer adhered to the substrate, as disclosed herein. Unless otherwise noted, the parameters formolding are those that were described herein. The more specific parameters for such process and the characterizing features of the skin-foam layer that were produced are summarized in Table 2 below:Table 2

[0039] FIG. 5 next provides an image of the skin-foam layer undergoing a 4.0 second delay followed by a withdrawal of the mold care at 0.5 inches / second. FIG. 6 provides an image of the skin-foam layer also undergoing a 4.0 second delay followed by withdrawal of the mold core at 1.0 inches / second. FIG. 7 provides an image of the skin-foam layer undergoing a 12.0 second delay followed by withdrawal of the mold core at 0.5 inches / second. FIG. 8 provides an image of the skin-foam layer also undergoing a 12.0 second delay followed by withdrawal of the mold core at 1.0 inches / second.

[0040] Table 3 below provides the ASTM D3574-17 (Standard Test Methods For Flexible Cellular Materials-Slab, Bonded and Molded Urethane Foams) for a skin-foam layer as a result of setting an initial spacing of 2.0 mm to 4.0 mm in a mold cavity from the surface of a substrate, injecting a thermoplastic elastomer containing chemical foaming agent into the initial spacing of the molding cavity and onto the surface of said substrate wherein the thermoplastic elastomer indicates an extensional viscosity of 100 pascal-second (Ps-S) to 500 pascal-second (Pa-S); selecting and applying a delay time before increasing said mold cavity initial spacing; and increasing said molding cavity initial spacing by 2.0 mm to 4.0 mm and forming a skin-foam layer on said surface of said substrate. The precent recovery is reported for ambient (room temperature) conditions of about 15 °C to 25 °C and elevated temperature of 80 °C.Table 3ASTM D3574-17 Testing Of Skin-Foam LayerOptional Mold-Closing Working Examples

[0041] Thermoplastic elastomer again sourced from Jing Yin Grand Elastomer Co., Ltd and identified as SR65A was injection molded, along with 3.0 % (wt.) of a chemical foaming agent (ACBA 100) over a selected substrate followed by withdrawal of the mold core, along with the optional use of a second stage delay time before decreasing the moldcavity spacing by a selected amount. The initial spacing of the mold was 3.0 mm. The results are summarized below in Table 4, which provides a table of the relevant molding parameters and the observed foaming ratios, Composite Foam Hardness values (CF) and skin thickness.Table 4Molding Parameters For Optional Mold-Closing Procedure

[0042] FIG. 9 provides an image of the skin-foam layer formed by injecting thermoplastic elastomer SR65A and foaming agent 3% wt. ACBA 100 into an injection mold cavity of 3.0 mm initial spacing, then undergoing a 12.0 second open delay time followed by opening of the mold at 0.5 inches per second to a cavity spacing of 4.23 mm, and subsequently undergoing a 0.1 second close delay followed by closing of the mold at 0.5 inches per second to a cavity spacing of 3.76 mm.

[0043] FIG. 10 provides an image of the skin-foam layer formed by injecting thermoplastic elastomer SR65A and foaming agent 3% wt. ACBA 100 into an injectionmold cavity of 3.0 mm initial spacing, then undergoing a 12.0 second open delay time followed by opening of the mold at 0.5 inches per second to a cavity spacing of 4.80 mm, and subsequently undergoing a 0.1 second close delay followed by closing of the mold at 0.5 inches per second to a cavity spacing of 3.76 mm.

[0044] FIG. 11 provides an image of the skin-foam layer formed by injecting thermoplastic elastomer SR65A and foaming agent 3% wt. ACBA 100 into an injection mold cavity of 3.0 mm initial spacing, then undergoing a 12.0 second open delay time followed by opening of the mold at 0.5 inches per second to a cavity spacing of 4.80 mm, and subsequently undergoing a 0.1 second close delay followed by closing of the mold at 0.5 inches per second to a cavity spacing of 3.25 mm.

[0045] FIG. 12 provides an image of the skin-foam layer formed by injecting thermoplastic elastomer SR65A and foaming agent 3% wt. ACBA 100 into an injection mold cavity of 3.0 mm initial spacing, then undergoing a 12.0 second open delay time followed by opening of the mold at 0.5 inches per second to a cavity spacing of 4.80 mm, and subsequently undergoing a 0.5 second close delay followed by closing of the mold at 2.0 inches per second to a cavity spacing of 3.76 mm.

[0046] FIG. 13 provides an image of the skin-foam layer formed by injecting thermoplastic elastomer SR65A and foaming agent 3% wt. ACBA 100 into an injection mold cavity of 3.0 mm initial spacing, then undergoing a 10.0 second open delay time followed by opening of the mold at 0.5 inches per second to a cavity spacing of 4.23 mm, and subsequently undergoing a 0.1 second close delay followed by closing of the mold at 0.5 inches per second to a cavity spacing of 3.76 mm.

[0047] As may now be appreciated, the above-described embodiments of the present invention stand directed at injection molding and formation of a skin-foam layer by a core- back procedure that is preferably applied to a selected and relatively rigid substrate. The skin- foam layer is also one that is amenable to recycling. The resulting product, amounting to a substrate-foam-skin component, is particularly useful for the manufacture of vehicle trim components having a skin surface with desirable haptic and visual characteristics overlying a foam layer where the foam layer is itself supported by the substrate.

Claims

CLAIMS1 . A method of forming an injection molded part comprising: providing an injection mold having a first mold half and a second mold half and a molding cavity between the first mold half and the second mold half; forming or positioning a substrate having a surface in said mold; setting a spacing of 2.0 mm to 4.0 mm in said mold cavity from the surface of said substrate; injecting a thermoplastic elastomer containing chemical foaming agent into said spacing of said molding cavity and onto said surface of said substrate wherein the thermoplastic elastomer indicates an extensional viscosity of 100 pascal-second (Ps-S) to 500 pascal-second (Pa-S); selecting and applying a first delay time before increasing said mold cavity spacing; and increasing said molding cavity spacing by 1.0 mm to 6.0 mm and forming a skinfoam layer on said surface of said substrate.

2. The method of claim 1 wherein said first delay time is 2.0 seconds to 15.0 seconds.

3. The method of claim 1 wherein said increase in said mold cavity spacing is performed at a rate of 0.1 inches / sec to 1.5 inches / sec.

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

5. The method of claim 4 wherein said thermoplastic block copolymer comprises a styrene-block copolymer.

6. The method of claim 5 wherein said styrene-block copolymer comprises styrene- ethylene-butadiene block copolymer.

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

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

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

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

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

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

13. The method of claim 1, further comprising, selecting and applying a second stage delay time before decreasing said mold cavity spacing; and decreasing said molding cavity spacing by 0.1 mm to 1.5 mm and achieving a desired part 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 said decrease in said mold cavity spacing is performed at a rate in the range of 0.1 in / sec to 2.5 in / sec.

16. A method of forming an injection molded part comprising: providing an injection mold comprising a first mold half and a second mold half and a molding cavity between the first mold half and the second mold half, including a movable mold core; forming or positioning a substrate having a surface in said mold; setting a spacing of 2.0 mm to 4.0 mm in said mold cavity from the surface of said substrate; injecting a thermoplastic elastomer containing chemical foaming agent into said spacing of said molding cavity and onto said surface of said substrate wherein the thermoplastic elastomer indicates an extensional viscosity of 100 pascal-second (Ps-S) to 500 Pa-S; selecting and applying a first delay time before increasing said mold cavity spacing; and increasing said molding cavity spacing by 1.0 mm to 6.0 mm by withdrawing said mold core and forming a skin-foam layer on said surface of said substrate.

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

18. The method of claim 16 wherein said increase in said mold cavity initial spacing is performed at a rate of 0.1 inches / sec to 1.5 inches / sec.

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

20. The method of claim 19 wherein said thermoplastic block copolymer comprises a styrene-block copolymer.

21. The method of claim 20 wherein said styrene -block copolymer comprises styrene- ethylene-butadiene block copolymer.

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

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

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

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

26. The method of claim 16 wherein said skin-foam layer indicates an ASTM D3574- 17 percent recovery of at least 50% at a temperature of 80 °C.

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

28. The method of claim 16, further comprising, selecting and applying a second stage delay time before decreasing said mold cavity spacing; and decreasing said molding cavity spacing by 0.1 mm to 1.5 mm by inserting said mold core and achieving a desired part thickness.

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 said decrease in said mold cavity spacing is performed at a rate in the range of 0.1 in / sec to 2.5 in / sec.

31. A method of forming an injection molded part comprising: providing an injection mold having a first mold half and a second mold half and a molding cavity between the first mold half and the second mold half; forming or positioning a substrate having a surface in said mold; setting a mold cavity spacing to a mold cavity spacing of 2.0 mm to 4.0 mm in said mold cavity from the surface of said substrate; injecting a thermoplastic elastomer containing chemical foaming agent into said initial spacing of said molding cavity and onto said surface of said substrate wherein the thermoplastic elastomer indicates an extensional viscosity of 100 pascal-second (Ps-S) to 500 pascal-second (Pa-S); selecting and applying a first delay time before increasing said mold cavity; increasing said molding cavity spacing by 1.0 mm to 6.0 mm and forming a skinfoam layer on said surface of said substrate; selecting and applying a second stage delay time before decreasing said mold cavity spacing; and decreasing said molding cavity spacing by 0.1 mm to 1.5 mm and achieving a desired part thickness.

32. A method of forming an injection molded pail comprising: providing an injection mold comprising a first mold half and a second mold half and a molding cavity between the first mold half and the second mold half, including a moveable mold core; forming or positioning a substrate having a surface in said mold;setting a mold cavity spacing to a mold cavity spacing of 2.0 mm to 4.0 mm in said mold cavity from the surface of said substrate; injecting a thermoplastic elastomer containing chemical foaming agent into said initial spacing of said molding cavity and onto said surface of said substrate wherein the thermoplastic elastomer indicates an extensional viscosity of 100 pascal-second (Ps-S) to 500 pascal-second (Pa-S); selecting and applying a first delay time before increasing said mold cavity spacing; increasing said molding cavity spacing by 1.0 mm to 6.0 mm by withdrawing said mold core and forming a skin-foam layer on said surface of said substrate; selecting and applying a second stage delay time before decreasing said mold cavity spacing; and decreasing said molding cavity spacing by 0.1 mm to 1.5 mm by inserting said mold core and achieving a desired part thickness.

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