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A method of producing a vehicle interior panel having a hollow double-walled structure made of thermoplastic comprising, blow molding with a pair of mold halves including a first mold with a shape transfer surface having a three dimensional pattern, and a second mold, clamping a cover material being

A method of producing a vehicle interior panel having a hollow double-walled structure made of thermoplastic comprising, blow molding with a pair of mold halves including a first mold with a shape transfer surface having a three dimensional pattern, and a second mold, clamping a cover material being formed by at least a double-layer structure arranged between a cavity of said first mold and a parison of thermoplastic such that a resin sheet layer without a through hole and without a three dimensional pattern faces a cavity of said first mold, introducing a pressurized fluid into the parison to press the cover material and the parison against a cavity surface, thereby integrally laminating said cover material to an outer surface of a first wall of the panel having the hollow double-walled structure and transferring said three dimensional pattern of said first mold half to said resin sheet.

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1. A method of producing a vehicle interior panel having a hollow double-walled structure made of thermoplastic comprising: blow molding with a pair of mold halves including a first mold half with a shape transfer surface having a three dimensional pattern, and a second mold half,clamping a cover ma

1. A method of producing a vehicle interior panel having a hollow double-walled structure made of thermoplastic comprising: blow molding with a pair of mold halves including a first mold half with a shape transfer surface having a three dimensional pattern, and a second mold half,clamping a cover material being formed by at least a double-layer structure arranged between a cavity of said first mold half and a parison of thermoplastic such that a resin sheet layer without a through hole and without a three dimensional pattern faces a cavity of said first mold half, said cavity having a shape transfer surface with a three dimensional pattern,bonding a non-woven fabric layer whose weight per area is no more than 250 g/cm2 to the parisonintroducing a pressurized fluid into the parison to press the cover material and the parison against a cavity surface,thereby integrally laminating said cover material having an average thickness of the cover material being not more than 2.0 mm (0.078 in), tensile modulus of the cover material being lower than 500 kg/cm2 (7.11 ksi) at 100° C. (212° F.), a tensile strength at yield point of the cover material being not more than 50 kg/cm2 (0.711 ksi) at 100 ° C. (212° F.) to an outer surface of a first wall of the panel having the hollow double-walled structure and transferring said three dimensional pattern of said first mold half to said resin sheet layer such that said three dimensional pattern is a plurality of protrusions disposed in a pattern impressed upon a surface of said resin sheet layer said protrusions having heights ranging from 0.5 - 2.5 mm (0.02-0.09 in) wherein an average thickness (a) of the vehicle interior panel is formed no more than 25.0 mm (0.98 in) and, the parting line is formed at a position located within a 35% range (b) of the average thickness of the panel from the surface of the first wall, and the parting line is formed within the range in which the average thickness is no more than 8.0 mm (0.315 in) from the surface of the first wall. 2. A vehicle interior panel producing method according to claim 1, wherein pinch-off forming portions forming a boundary between said cavities are provided in said first mold half and said second mold half, the parison and the cover material are sandwiched by arranging the parison and the cover material between the mold halves to perform the clamping, a blowing pin is stuck into the parison near the pinch-off forming portions to introduce the pressurized fluid in the parison, a parting line corresponding to the pinch-off forming portions is formed, an end of the cover material is integrally laminated along the parting line over an entire circumference of a peripheral wall of the vehicle interior panel. 3. A vehicle interior panel producing method according to claim 2, wherein a step-portion forming portion is provided along the pinch-off forming portion over the entire circumference of the cavity in the first mold half, the end of the cover material is integrally fixed by pressing the end of the cover material against the parison in the step-portion forming portion, and thereby the end of the cover material is laminated along a step portion formed on the peripheral wall of the vehicle interior panel. 4. A vehicle interior panel producing method according to claim 1, wherein a slide core is provided in the cavity of the other mold while being retractable to a cavity surface, after a part of the parison is integrally welded by the slide core projected from the cavity surface, the slide core is retracted to the cavity of the second mold half, and the pressurized fluid is introduced into the parison to form a double-plate-like double-walled rib in which side faces are welded to each other between the first wall and a second wall by blow pressure. 5. A vehicle interior panel producing method according to claim 1, wherein a hinge forming portion is provided on the cavity of the second mold half, the cavity of second mold half has a parting surface including a linear pinch-off forming portion and a pinch-off forming portion projected from the cavity surface near the hinge forming portion, the cavity of the first mold half has the parting surface including a linear pinch-off forming portion and a pinch-off forming portion corresponding to said projected pinch-off forming portion, the cover material is arranged between the parison and the first mold half, the first and second mold halves are clamped to form the parting line corresponding to said parting surface, parts of the parison are integrally welded by the hinge forming portion provided in the second mold half, and the pressurized fluid is introduced into the parison to form a hinge portion separating hollow spaces in the same surface as the first wall by the blow pressure. 6. A vehicle interior panel producing method according to claim 1, wherein a three-dimensional shape transfer surface is formed on at least the first mold half, the parison is arranged between said mold halves, the flat cover material having no three-dimensional pattern is arranged between the parison and the cavity in which said three-dimensional shape transfer surface is formed such that the resin sheet faces the cavity, the mold halves are closed to introduce the pressurized fluid into the parison, the cover material is pressed against the cavity of the first mold half to laminate the cover material to the parison, and the three-dimensional pattern corresponding to said three-dimensional shape transfer surface is transferred to the surface of the cover material. 7. A vehicle interior panel producing method according to claim 6, wherein the three-dimensional shape transfer surface has a grain pattern or a plurality of recesses whose depths from the cavity surface range from 0.5 to 2.5 mm (0.02-0.09 in). 8. A vehicle interior panel producing method according to claim 6, wherein the cover material is arranged between the parison and the cavity of either of the first or second mold halves, and clamping is performed without softening the cover material by a heating process.