Sheet molding compound having improved characteristics
AssigneesOwens Corning Fiberglas Technology, Inc., Owens Corning Composites SPRL
InventorsJacques H. Gerard, David E. Adam, Frank R. Cichocki, Michael H. Jander, Paul R. Krumlauf, Giovanni Montagna, Donald B. Sage
Life of this patent
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Abstract
A composite part made from a sheet molding compound is disclosed as having improved characteristics over traditional sheet molding compound composite parts. The fibrous material is introduced as a veil layer adjacent a paste layer, the veil flows well during the molding process. The improved flow and surface characteristics of a composite part are attributed to the elongation of the veil during molding and to the improved filling capabilities.
Claims125
A single ply of a sheet molding compound sheet prior to compaction used for making composite parts having improved surface characteristics comprising:
- a first carrier film layer;
- a first paste layer provided adjacent the carrier film layer;
- a veil provided adjacent to the first paste layer opposite the first carrier layer;
- a second carrier film layer;
- and
- a second paste layer provided between the veil and second carrier film layer.
A method for making a single ply of a sheet molding compound sheet comprising the steps of:
- introducing a first carrier film layer;
- introducing a first side of a veil adjacent to said first carrier film layer;
- introducing a first paste layer between said veil and said first carrier film layer;
- introducing a second carrier film layer adjacent to a second side of said veil;
- introducing a second paste layer between said veil and said second carrier film layer;
- and
- compacting said combined veil and paste layers to form a single ply of sheet molding compound.
A method for making a composite part having improved surface characteristics comprising:
- forming a single ply of a sheet molding compound sheet, the method of forming said single ply comprising:
- (a) introducing a first carrier film layer;
- (b) introducing a veil adjacent to said first carrier film layer;
- (c) introducing a first paste layer between a first side of said veil and said first carrier film layer;
- (d) introducing a second carrier film layer adjacent to a second side of said veil to form a sheet molding compound sheet;
- (e) compacting said carrier films, veil and paste to form a single ply of sheet molding compound.
- (f) thickening said single ply;
- (g) cutting said single ply into a plurality of moldable plies having a desired shape;
- (h) introducing at least one of said plurality of moldable plies into a mold having a surface;
- (i) compressing said moldable ply within said mold;
- (j) flowing said first paste layer of said moldable ply to cover said mold surface;
- (k) elongating said veil of said moldable ply during said flowing step (j) across substantially the entire mold surface;
- and
- (l) curing said moldable ply at a first pressure and a first temperature for a sufficient time to form the composite part.
A single ply of a conductive sheet molding compound composite sheet used to make a composite part having surface conductivity comprising:
- a first paste layer;
- a plurality of chopped reinforcing fibers;
- and
- a conductive paste layer, said conductive paste layer comprising a thermosetting resin and a graphite material.
A method for making a single ply of a conductive sheet molding compound that may be subsequently used to make an electrically conductive composite part comprising:
- introducing a first carrier film layer;
- introducing a first paste layer onto said first carrier film layer, said first paste layer comprising a first paste formulation;
- introducing a plurality of chopped reinforcing fibers onto said first paste layer;
- introducing a conductive paste layer onto said first paste layer, said conductive paste layer comprising a conductive paste formulation, said conductive paste formulation comprising a thermosetting resin and a graphite material;
- introducing a second carrier film layer onto said conductive paste layer to form a sheet molding compound composite sheet;
- compacting said sheet molding compound composite sheet to form a single ply of sheet molding compound;
- and
- thickening said single ply.
A method for forming a composite part having electrical conductivity of less than 106 ohms per square along a visible surface, the method comprising:
- forming a conductive sheet molding compound composite sheet, said conductive sheet molding compound composite sheet comprising a first paste layer, a plurality of chopped reinforcing fibers, and a conductive paste layer comprising a thermosetting resin and a graphite material;
- compacting said conductive sheet molding compound composite sheet to form a single ply of a conductive sheet molding compound;
- introducing at least one ply of said conductive heat molding compound to a mold such that said second paste layer is closely coupled to a surface of said mold;
- and
- molding said at least one ply of said conductive sheet molding compound at a first temperature and a first pressure for sufficient time to cure said conductive sheet molding compound to form the composite part.
The method of claim 96, wherein forming conductive sheet molding compound composite sheet comprises:
- introducing a first carrier film layer;
- introducing a first paste layer onto said first carrier film layer, said first paste layer comprising a first paste formulation;
- introducing a plurality of chopped fibers onto said first paste layer;
- introducing a conductive paste layer onto said plurality of chopped fibers, said conductive paste layer comprising a second paste formulation, said second paste formulation comprising a thermosetting resin and a graphite material;
- introducing a second carrier film layer onto said conductive paste layer to form a conductive sheet molding composite sheet;
- compacting said conductive sheet molding composite sheet to form a single ply of conductive sheet molding compound;
- thickening said single ply;
- and
- cutting said single ply into a plurality of moldable plies having a desired shape;
- and
- removing said first carrier film layer and said second carrier film layer from said single ply.
The method according to claim 96, wherein forming a conductive sheet molding compound composite sheet comprises forming a conductive sheet molding compound composite sheet, said conductive sheet molding compound composite sheet comprising a first paste layer, a plurality of chopped reinforcing fibers, and a conductive paste layer comprising a thermosetting resin and a graphite powder.
The method according to claim 96, wherein forming a conductive sheet molding compound composite sheet comprises forming a conductive sheet molding compound composite sheet, said conductive sheet molding compound composite sheet comprising a first paste layer, a plurality of chopped reinforcing fibers, and a conductive paste layer comprising a thermosetting resin and a graphite flake.
The method according to claim 96, wherein forming a conductive sheet molding compound composite sheet comprises forming a conductive sheet molding compound composite sheet, said conductive sheet molding compound composite sheet comprising a first paste layer, a plurality of chopped reinforcing fibers, and a conductive paste layer comprising a thermosetting resin and a graphite material, said graphite material comprising not less than approximately 20 weight percent of said conductive paste layer.
The method according to claim 96, wherein forming a conductive sheet molding compound composite sheet comprises forming a conductive sheet molding compound composite sheet, said conductive sheet molding compound composite sheet comprising a first paste layer, a plurality of chopped reinforcing fibers, and a conductive paste layer comprising a thermosetting resin and a graphite material, said graphite material comprising not less than approximately 20 weight percent of said conductive paste layer, wherein said graphite material is selected from the group consisting of graphite powder and graphite flake.
The method of claim 96, wherein molding said at least one ply comprises molding said at least one ply of said conductive sheet molding compound at between about 140-163 degrees Celsius and between about 5-10 MPa for about one-half to three minutes to cure said conductive sheet molding compound to form the composite part.
The method according to claim 96, wherein said chopped fibers comprise a veil, the molding step further comprising the steps of:
- compression molding said sheet in a mold having a surface;
- flowing the fibers with the paste layers during the compression molding step;
- and
- substantially covering the entire surface of the mold with said fibers in a substantially continuous form during said flowing step.
A method for introducing a layer of sheet molding paste on a sheet molding compounding line comprising:
- coupling a volumetric paste extrusion device to the sheet molding compounding line, said volumetric paste extrusion device comprising a paste tank fluidically coupled to a slit extrusion die, said paste tank having a quantity of sheet molding paste;
- pumping said quantity of sheet molding paste from said paste tank to said slit extrusion die;
- and
- volumetrically applying a portion of said quantity of sheet molding paste from said slit extrusion die onto the sheet molding compounding line to form a layer of sheet molding paste.
A volumetric paste extrusion device used to apply sheet molding paste to a sheet molding compounding line comprising:
- a paste tank, said paste tank having a quantity of sheet molding paste;
- a slit extrusion die having a slit, said slit having a width W;
- an input line for fluidically coupling said paste tank to said slit extrusion die;
- a first volumetric pump coupled to said input line, said first volumetric pump capable of pumping said quantity of sheet molding paste from said paste tank through said input line to said slit extrusion die;
- an exit line for fluidically coupling said slit extrusion die to said paste tank.
A sheet molding composite sheet for use in structural reinforced compression molded composite parts, the sheet comprising in an uncompacted form between a pair of outer film layers:
- a first layer of resin paste applied to one of the pair of outer film layers;
- a second layer of resin paste applied to the other of the pair of outer film layers;
- n layers of reinforcement fibers;
- and
- (n−1) layers of resin paste volumetrically applied to between each of said n layers of reinforcement fibers using a volumetric paste extrusion device, wherein n is at least 2.
Dependencies are inferred from the claim text.