Co-injection of molded parts for weight reduction

Patent metadata

Field	Value
Publication number	US-2016288387-A1
Application number	US-201415031981-A
Country	US
Kind code	A1
Filing date	Oct 24, 2014
Priority date	Oct 25, 2013
Publication date	Oct 6, 2016
Grant date	—

Abstract

A molded vehicle component ( 10 ) having a skin ( 14 ) and a lower density core ( 16 ) formed by a co-injection molding process. In a first phase, a first material for forming the skin of class A surface material is injected into a mold to partially fill the mold cavity ( 104 ). Thereafter, in a second phase, a second material is injected into the same cavity ( 104 ) to complete filling of the mold cavity ( 104 ). The second material can flow only to portions of the part where the first material is still molten and displaces the molten core of the first phase, pushing it away from co-injection gates until the mold cavity is full. The second material is pre-treated with a chemical blowing agent in order to reduce part weight by foaming the core material. The finished co-injection molded part ( 10 ) has one material on all visible class A surfaces ( 14 ) and a core ( 16 ) that is a different, less dense material.

First claim

What is claimed is:

1 . A thermoplastic component for a motor vehicle, comprising:
an outer surface layer of a co-injection moldable first material having a class A forming surface; and a core of co-injection moldable second material induced with a predetermined amount of chemical blowing agent for decreasing density of the core material to be less dense than the first material.

2 . The thermoplastic component for a motor vehicle of claim 1 , wherein the chemical blowing agent forms gas that creates small voids in the second material which reduces density of the core and, therefore, reduces the thermoplastic component weight.

3 . The thermoplastic component for a motor vehicle of claim 2 , wherein the chemical blowing agent is directly introduced into the second material of the core only, and wherein the first material is not treated with a chemical blowing agent.

4 . The thermoplastic component for a motor vehicle of claim 3 , wherein the gas treated second material is isolated from the class A surface by the untreated outer surface layer, which retains desired appearance, properties and characteristics.

5 . The thermoplastic component for a motor vehicle of claim 1 , wherein the first material is a thermoplastic polyolefin co-injection moldable material.

6 . The thermoplastic component for a motor vehicle of claim 1 , wherein the second material is a thermoplastic polyolefin co-injection moldable material.

7 . The thermoplastic component for a motor vehicle of claim 6 , wherein the chemical blowing agent is a predetermined pelletized material additive that is mixable with the second material at a predetermined low percentage by weight, said chemical blowing agent being activated at a predetermined heated temperature such that when activated the chemical blowing agent allows carbon dioxide to be generated which foams the second material.

8 . The thermoplastic component for a motor vehicle of claim 1 , wherein the outer surface layer encapsulates the core.

9 . The thermoplastic component for a motor vehicle of claim 8 , wherein the core is a predetermined distance from the Class A surface of the outer surface layer at a plurality of predetermined areas to operably allow thermoplastic component weight reduction while not breaking out through the outer surface layer so as to allow a desired appearance to the class A surface.

10 . The thermoplastic component for a motor vehicle of claim 1 , wherein the thermoplastic component is selected from the group consisting of front/rear fascias, door panels, exterior/interior decorative trim and panels, floor consoles, and instrument panels.

11 . A method for molding a thermoplastic component for a motor vehicle, comprising:
providing a first material that is an injection moldable paintable or molded in color thermoplastic polyolefin material and is not treated with chemical blowing agents; providing a second material that is an injection moldable thermoplastic polyolefin material; providing a mold having co-injection gates and a mold cavity capable of receiving an injection of the first material for forming an outer surface layer having at least one class A surface and of immediately thereafter receiving an injection of the second material to complete filling of the mold cavity; treating the second material directly with a predetermined amount of chemical blowing agent; heating the second material to a predetermined temperature to activate the chemical blowing agent to create gas that creates small voids in the second material which decreases the density of the core material to be less dense than the first material; injecting the first material into predetermined areas of the mold cavity, wherein the first material cools where contact is made with the mold cavity and remains molten where not in contact with the mold cavity, injecting the treated second material into predetermined areas of the mold cavity to form a core, wherein the gas further expands in the mold cavity until the chemical blowing agent is fully activated, and wherein the second material displaces the molten first material until the mold cavity is filled.

12 . The method for molding a thermoplastic component of claim 11 , wherein the outer surface layer encapsulates the core.

13 . The method for molding a thermoplastic component of claim 11 , further comprising providing a chemical blowing agent mixing device having a heating barrel for activating the chemical blowing agent to form carbon dioxide which foams the second material.

14 . The method for molding a thermoplastic component of claim 11 , wherein the gas treated second material is isolated from the class A surface by the untreated outer surface layer, which retains desired appearance, properties and characteristics.

15 . The method for molding a thermoplastic component of claim 11 , wherein a sequential valve gate mold is used for the process.

16 . The method for molding a thermoplastic component of claim 11 , further comprising painting the class A surface.

17 . The method for molding a thermoplastic component of claim 11 , wherein the chemical blowing agent is a predetermined pelletized material additive that is mixable with the second material at a predetermined low percentage by weight, said chemical blowing agent being activated at a predetermined heated temperature such that when activated the chemical blowing agent allows carbon dioxide to be generated which foams the second material.

18 . The method for molding a thermoplastic component of claim 11 , wherein the chemical blowing agent is about 3.0 percent by weight in the core.

19 . The method for molding a thermoplastic component of claim 11 , wherein weight reduction of the thermoplastic component is at least about 5%.

20 . A thermoplastic component forming a fascia for a motor vehicle, comprising:
an outer surface layer of a first material that is a thermoplastic polyolefin co-injection moldable and paintable material having a class A forming surface; and a core of thermoplastic polyolefin co-injection moldable second material directly induced with a predetermined amount of chemical blowing agent that forms gas that creates small voids in the second material which reduces density of the core, where the gas treated second material is isolated from the class A surface by the outer surface layer which is not treated with chemical blowing agents.

Assignees

• Birka Mark P
• Korte Keith G
• Dobbs Daniel R
• Dew Jeremy K
• Parker Charles T
• Magna Int Inc

Inventors

• Birka Mark P
• Korte Keith G
• Dobbs Daniel R
• Dew Jeremy K
• Parker Charles T

Classifications

• B29C45/1642 Primary

  having a "sandwich" structure (B29C45/1603 takes precedence) · CPC title

• B29C71/00

  After-treatment of articles without altering their shape; Apparatus therefor (B29C44/56, B29C73/00 take precedence; surface shaping B29C59/00 {; for joined or sealed parts B29C66/03; after-treatment specially adapted for vulcanising tyres B29D30/0633}) · CPC title

• B29C44/0461

  by having different chemical compositions in different places, e.g. having different concentrations of foaming agent, feeding one composition after the other · CPC title

• B29C45/1704

  the fluid being introduced into the interior of the injected material which is still in a molten state, e.g. for producing hollow articles (B29C45/1732 and B29C45/1734 take precedence; injection blow-moulding B29C49/06) · CPC title

• B32B2266/025

  Polyolefin · CPC title