Co-injection of molded parts for weight reduction

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 that is paintable material having a class A forming surface and no chemical blowing agents,
• a core of thermoplastic polyolefin co-injection moldable second material directly induced with at least about 3 wt % of chemical blowing agent that forms gas that creates voids in the second material which reduces density of the core and reduces weight of the thermoplastic component by at least about 5 percent, wherein 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,
• wherein the core is fully encapsulated by the outer surface layer,
• wherein the thermoplastic component comprises a wallstock defined as a combination of the core and the outer surface layer, and the wall stock is from about 3 to 4 millimeters thick,
• wherein thickness of said outer surface layer varies at predetermined locations of the thermoplastic component, and
• wherein when the thermoplastic component is devoid of the core the thickness of the outer surface layer is about 0.3 to 3.0 millimeters.

A method for molding a thermoplastic component for a motor vehicle, comprising:

• providing a first material that is an injection moldable, paintable 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 for forming a core;
• treating the second material directly with a chemical blowing agent in an amount of at least about 3.0 percent by weight of the core;
• heating the second material to a predetermined temperature to activate the chemical blowing agent to create gas that creates voids in the second material which decreases the density of the core material, wherein the core is less dense than the outer surface layer;
• 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, 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;
• wherein weight reduction of the thermoplastic component is at least about 5%,
• wherein the core is fully encapsulated by the outer surface layer,
• wherein the thermoplastic component comprises a wallstock defined as a combination of the core and the outer surface layer, and the wall stock is from about 3 to 4 millimeters thick,
• wherein thickness of the outer surface layer varies at predetermined locations of the thermoplastic component, and
• wherein when the thermoplastic component is devoid of the core the thickness of the outer surface layer is about 0.3 to 3.0 millimeters.