Method for making plastic panel and panel

Claim 1

A method for producing a compression molded, fiber reinforced, plastic panel comprising a plate having an outer surface and an inner surface bearing integrally molded reinforcing members, which method comprises: A. providing a mold with heated first and second mold members that close to form a configuration for said panel, one of said mold members having a surface interrupted by rib-forming chambers that fill to form a rib pattern that rigidifies said panel, said chambers having a width about equal to or less than the thickness of said plate and a depth at least as large as said thickness; B. introducing molding compound between said mold members in sufficient amount to form under heat and pressure said panel, said molding compound being in layers positioned one atop another, a first part of said layers comprising thermosetting resin and relatively short chopped fibers and the other part comprising thermosetting resin and relatively long chopped fibers; C. causing said mold members to close upon said molding compound at a pressure in a relatively high range so as to cause flow of said molding compound between said mold members into said configuration whereby said relatively short fibers flow into said chambers; D. reducing said pressure to a subsequent pressure in a relatively low range and permitting said molding compound to at least substantially cure at a pressure in said relatively low range; E. parting said mold members; F. removing said panel from between said mold members.

Claim 2

A method for producing a compression molded, fiber reinforced, plastic panel comprising a plate having an outer surface and an inner surface bearing integrally molded reinforcing members, which method comprises: A. providing a mold with heated first and second mold members that close to form a configuration for said panel, one of said mold members having a surface interrupted by rib-forming chambers that fill to form a rib pattern that rigidifies said panel, said chambers having a width about equal to or less than the thickness of said plate and a depth at least as large as said thickness; B. introducing molding compound between said mold members in sufficient amount to form under heat and pressure said panel, said molding compound being in layers positioned one atop another, a first part of said layers comprising thermosetting resin and relatively short chopped fibers and the other part comprising thermosetting resin and relatively long chopped fibers; C. causing said mold members to close upon said molding compound at a pressure in a relatively high range so as to cause flow of said molding compound between said mold members into said configuration whereby said relatively short fibers flow into said chambers; D. reducing said pressure to a subsequent pressure in a relatively low range and permitting said molding compound to at least substantially cure at a pressure in said relatively low range; E. parting said mold members; F. removing said panel from between said mold members.

Claim 10

A method in accordance with claims 1 or 2 or 3 or 4 or 5 or 6 wherein said first and other parts have a paste viscosity that is substantially the same.

Claim 16

A method for producing a compression molded fiber reinforced plastic closure panel comprising a plate having an outer surface and an inner surface bearing integrally molded reinforcing members, which method comprises: A. providing a mold with heated first and second mold members that close to form a configuration for said panel, one of said mold members having a surface interrupted by rib-forming chambers that fill to form a rib pattern that rigidifies said panel, said chambers having a width about equal to or less than the thickness of said plate and a depth at least as large as said thickness; B. introducing molding compound between said mold members in sufficient amount to form under heat and pressure said panel, said molding compound being in layers positioned one atop another, a first part of said layers comprising thermosetting resin and relatively short chopped fibers and the other part of said molding compounding comprising thermosetting resin and relatively long chopped fibers, the weight ratio: (1) of said first to said other part being not higher than about 1:2, (2) of said relatively short to said relatively long chopped fibers being not higher than about 1:2, and the ratio of average fiber length of relatively long to relatively short fibers being at least about 3:1; C. causing said mold members to close slowly upon said molding compound at a pressure in a relatively high range so as to cause flow of said molding compound between said mold members into said configuration whereby said relatively short fibers flow into said chambers; D. maintaining said pressure in said relatively high range for a period sufficient to reduce laking on said outer surface; E. reducing said pressure to a subsequent pressure in a relatively low range and permitting said molding compound to at least substantially cure at a pressure in said relatively low range; F. parting said mold members; G. removing said panel from between said mold members.

Claim 17

A method for producing a compression molded fiber reinforced plastic closure panel comprising a plate having an outer surface and an inner surface bearing integrally molded reinforcing members, which method comprises: A. providing a mold with heated first and second mold members that close to form a configuration for said panel, one of said mold members having a surface interrupted by rib-forming chambers that fill to form a rib pattern that rigidifies said panel, said chambers having a width about equal to or less than the thickness of said plate and a depth at least as large as said thickness; B. introducing molding compound between said mold members in sufficient amount to form under heat and pressure said panel, said molding compound being in layers positioned one atop another, a first part of said layers comprising thermosetting resin and relatively short chopped fibers and the other part of said molding compounding comprising thermosetting resin and relatively long chopped fibers, the weight ratio: (1) of said first to said other part being not higher than about 1:2, (2) of said relatively short to said relatively long chopped fibers being not higher than about 1:2, and the ratio of average fiber length of relatively long to relatively short fibers being at least about 3:1; C. causing said mold members to close slowly upon said molding compound at a pressure in a relatively high range so as to cause flow of said molding compound between said mold members into said configuration whereby said relatively short fibers flow into said chambers; D. maintaining said pressure in said relatively high range for a period sufficient to reduce laking on said outer surface; E. reducing said pressure to a subsequent pressure in a relatively low range and permitting said molding compound to at least substantially cure at a pressure in said relatively low range; F. parting said mold members; G. removing said panel from between said mold members.

Claim 25

A method in accordance with claims 15 or 16 or 17 or 18 or 19 or 20 wherein said first and other part have a paste viscosity that is substantially the same.

Claim 29

A method for producing a compression molded fiber reinforced plastic closure panel comprising a plate having an outer surface and an inner surface bearing integrally molded reinforcing members, which method comprises: A. providing a mold with heated first and second mold members that close to form a configuration for said panel, one of said mold members having a surface interrupted by rib forming chambers that fill to form a rib pattern that rigidifies said panel, said chambers having a width about equal to or less than the thickness of said plate and a depth at least as large as said thickness; B. introducing a low profile molding compound of substantially equal paste viscosity between said members in sufficient amount to form under heat and pressure said panel, said molding compound being in layers substantially equal large dimensions and positioned one atop another, a first part of said layers comprising thermosetting resin and relatively short fibers and the other part of said layers comprising thermosetting resin and relatively long chopped fibers, the weight ratio (1) of said first to said other parts being not higher than about 1:2; (2) of said relatively short to said relatively long chopped fibers being not higher than about 1:2 and the ratio of average fiber length of relatively long to said relatively short fibers being at least about 3:1; C. causing said mold members to close slowly upon said molding compound at a first pressure in a relatively high range above about 500 psi so as to cause flow of said molding compound between said mold members into said configuration whereby said relatively short fibers flow into said chambers and said relatively long fibers form part of said plate; D. maintaining said pressure in said relatively high range for a period of at least about 15 seconds and sufficient to reduce laking on said outer surface; E. reducing by at least about one half said pressure to a subsequent pressure in a relatively low range and permitting said molding compound to at least substantially cure at a pressure in said relatively low range; F. parting said mold members; G. removing said panel from between said mold members.

Claim 30

A method for producing a compression molded fiber reinforced plastic closure panel comprising a plate having an outer surface and an inner surface bearing integrally molded reinforcing members, which method comprises: A. providing a mold with heated first and second mold members that close to form a configuration for said panel, one of said mold members having a surface interrupted by rib forming chambers that fill to form a rib pattern that rigidifies said panel, said chambers having a width about equal to or less than the thickness of said plate and a depth at least as large as said thickness; B. introducing a low profile molding compound of substantially equal paste viscosity between said members in sufficient amount to form under heat and pressure said panel, said molding compound being in layers substantially equal large dimensions and positioned one atop another, a first part of said layers comprising thermosetting resin and relatively short fibers and the other part of said layers comprising thermosetting resin and relatively long chopped fibers, the weight ratio (1) of said first to said other parts being not higher than about 1:2; (2) of said relatively short to said relatively long chopped fibers being not higher than about 1:2 and the ratio of average fiber length of relatively long to said relatively short fibers being at least about 3:1; C. causing said mold members to close slowly upon said molding compound at a first pressure in a relatively high range above about 500 psi so as to cause flow of said molding compound between said mold members into said configuration whereby said relatively short fibers flow into said chambers and said relatively long fibers form part of said plate; D. maintaining said pressure in said relatively high range for a period of at least about 15 seconds and sufficient to reduce laking on said outer surface; E. reducing by at least about one half said pressure to a subsequent pressure in a relatively low range and permitting said molding compound to at least substantially cure at a pressure in said relatively low range; F. parting said mold members; G. removing said panel from between said mold members.

Claim 34

A method in accordance with claims 27 or 28 or 29 or 30 wherein said relatively high range is between 500-1400 psi and said relatively low range is between about 100-400 psi.