Nonwoven fabric used for foamed article reinforcing material, foamed article reinforcing material, and method for producing nonwoven fabric used for foamed article reinforcing material

A method for producing a single-layer nonwoven fabric for molding into a single-layer reinforcing material for bonding a foamed material, the method comprising:

• stacking layers of a web made of short fibers to form a stack, wherein each layer of the stack comprises a single fiber blend and includes 20% to 60% by weight of polyethylene terephthalate fibers and 40% to 80% by weight of polypropylene fibers;
• processing the stack into a single-layer material made of the short fibers by bonding the short fibers together through needle punching;
• applying heat treatment only to a surface of the single-layer material without heating internal fibers of the single-layer material,
• wherein the web includes 20% to 60% by weight of the polyethylene terephthalate fibers and 40% to 80% by weight of the polypropylene fibers,
• wherein the polyethylene terephthalate fibers have a core-sheath structure, and
• wherein the core-sheath structure includes a core and a sheath having a lower melting point than the core,
• wherein the single-layer nonwoven fabric has a thickness of 1 to 8 mm under a load of 7 g/cm2, and
• wherein the single-layer nonwoven fabric has a delamination strength of 0.05 to 2.45 N/cm, and the delamination strength is a value of pulling force required to separate bonded short fibers together through the needle punching, and
• measuring the delamination strength, the measuring comprising conducting a test ten times, the test comprising:
• a first preparation step of preparing an elongate test piece that is made of the single-layer nonwoven fabric and has a width of 3 cm;
• a second preparation step of peeling the stacked layers of the single-layer nonwoven fabric to separate bonded short fibers together through the needle punching into a first layer and a second layer in a longitudinal end region of the test piece, thereby delaminating the end region;
• a peeling step of holding the peeled first layer and second layer separately by a pull tester to delaminate a section of the test piece that is continuous with the end region at a pulling speed of 970 mm/min for approximately 20 cm;
• and
• a measuring step of measuring a maximum value of a force required for the delamination in the peeling step, and
• an average of the maximum values of the test conducted ten times is the delamination strength.