Plastic spacer stock, plastic spacer frame and multi-sheet unit, and method of making same

A multi-sheet unit comprising:

• a spacer frame comprising at least three sides, at least three corners, a first sheet supporting surface and an opposite second sheet supporting surface, the spacer frame comprising:
• a spacer stock member comprising:
• a first end, an opposite second end, the at least three sides and at least two corners of the at least three corners;
• a first upright member having an outer surface and an opposite inner surface, wherein the outer supporting surface of the first upright member is the first sheet supporting surface;
• a second upright member having an outer surface and an opposite inner surface, wherein the outer supporting surface of the second upright member is the second sheet supporting surface;
• a base interconnecting the first and second upright members to provide the spacer stock segment with a generally U-shaped cross section, the base having an inner surface facing a space between the upright members, and an opposite outer surface, and
• the at least two corners each comprising a V-shaped area, wherein all of the wall thickness of the upright members within the V-shaped area is greater than zero and less than a wall thickness of the upright members adjacent to and outside of the V-shaped area, and the portions of the first and second upright members within the V-shape area at the at least two corners of the spacer frame extending toward one another and extending over the inner surface of the base, wherein the wall thickness of the first or the second upright members is the distance between the outer surface and the inner surface of the first or second upright members, respectively;
• a corner key comprising:
• an elongated body having a first end in the first end of the spacer stock member, an opposite second end in the second end of the spacer stock member to provide one of the corners of the at least three corners of the spacer frame, and a cut out between the ends of the corner key, the elongated body bendable at the cut out to move the ends of the corner key relative to one another to decrease the spacing of the cut out, wherein at least one of the spacer stock member, and the corner key, of the spacer frame comprises a core made from a material selected from a group of moisture pervious material, a gas pervious material, and a moisture and gas pervious material and a barrier film over selected surfaces of the core, the barrier film selected from a group of a moisture impervious material, a gas impervious material, and a moisture and gas impervious material;
• a first sheet secured to the first sheet supporting surface by a first moisture and/or gas impervious layer, and
• a second sheet secured to the second sheet supporting surface by a second moisture and/or gas impervious layer.