JPH0372744B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Field of Application) The present invention relates to an improved fiber mat and a method for manufacturing the mat. The improved fiber mat is manufactured by structural resin injection molding (RIM) method.
It is intended for use as a preformable mat, applied to mold fiber-reinforced complex shapes. BACKGROUND OF THE INVENTION Preformable mats are generally made from continuous strands or shredded fibers placed on a heated Matched die mold with the desired final shape. Manufactured from any fiber. The fibers are usually bonded by thermosetting or thermoplastic polyester resin materials and are described in U.S. Pat.
3969171, a matrix is used to facilitate shape retention during preforming.
Resin is added. U.S. Patent No. 3718954 and
There are also methods of providing nonwoven reinforced structures containing chopped fibers integrated into aggregates without the use of binders or adhesives, as disclosed in No. 3,614,976. The use of fiber mats to produce fiber reinforced preforms having useful shapes to be molded into final products is well known. Fiber reinforced products are
It is manufactured by a new and improved processing method that requires contouring the fiber reinforced material into complex curves and shapes. The fiber mat is stretched and bent to integrate into the shape of the mold when processed in a preforming process. The mat must have sufficient volume or thickness to integrate into the contour of the preform without undesirable splitting or attenuation. The mat must also maintain sufficient volume to ensure proper flow of resin through the preform during the RIM process. If the fibers are too thinly dispersed or too tightly packed, the proper resin/fiber concentration will not be properly achieved throughout the product. In the second manufacturing method, US Pat. No. 3,936,588;
The use of fiber mats such as those made in Nos. 3,969,171; 3,614,936, and 3,718,954 is excluded.
This process generally involves fiber roving.
Auxiliary machines are used to directly apply the preforms. The present invention provides an improved mat that does not require the auxiliary machinery described above and is used in the preforming process. It is an object of the present invention to produce a versatile preformable mat designed for producing preforms with highly complex contours that are subsequently formed by a RIM process. Another object of the invention is to produce preformed mats with sufficient volume to provide proper pine geology and fiber distribution after preforming. Yet another object of the present invention is to produce a preformed mat with a proper combination of volume and porosity to provide homogeneous flow of resin through the preformed mat during the RIM process. . The objects of the invention are achieved by utilizing two different lengths of fiber strands in the dry mat. The two lengths of fiber ensure that the mat is formed with sufficient volume or thickness to provide proper fiber distribution during the preforming process. After dry depositing the fibers, a three-component binder system is applied and the mat is heated to solidify the binder. The finished pine is one that has sufficient tensile strength to be wound into rolls to produce a transportable product. The present invention provides an improved preformed mat and method of manufacturing the mat described above. The preformed mats described above are convenient for use as highly complex and contoured preforms, such as those used in structural RIM reinforcement. The preformed mats of the present invention are manufactured using glass fiber filaments approximately 13 microns in diameter. Continuous filaments are typically obtained in dual forming furnaces producing 2986 meters per kilogram of glass (1240 yards per pound) of filament. As the fibers are shaped, forming sizes are applied. Suitable compositions of the forming size agents described above are listed in the table. After applying the forming size, the filament is divided into 12 different bundles.

[Table] The bundled glass fibers are preferably 10.16 cm.
(4 inch) and 15.24 cm (6 inch) lengths and dry stacked on mats. In contrast to the production of conventional shredded strand mats where the glass fibers were chopped into one length, typically between about 1 inch and 2 inches, before being assembled into the mat. , this change in fiber length is the main improvement. The use of different fiber lengths and longer fiber lengths in accordance with the present invention provides mats with desirable volume or thickness characteristics necessary for complex preforming operations. mentioned above
Fibers chopped into 4 inches and 6 inches are deposited as a mat in a 40/60 weight ratio. The mat is bound after its formation. Preferably, a three-component binder system is used, comprising a mixture of two powders that is transferred onto the mat and an emulsion that is spray applied to the top and bottom of the mat. The powder mixture and emulsion described above are applied to the mat as a 55/45 weight percent mixture. The preferred powdered binder is an equal mixture of a styrene-soluble thermoplastic powdered polyester resin and polystyrene having the properties listed in the table. The powder mixture is applied to the mat by a conventional vibrator and spreader.

[Table]
Suitable emulsions include polyvinyl acetate mowlith D-50 from Hoechst, plasticized with 3% polyethylene glycol adipate, having the properties listed in the table. The emulsion is sprayed onto the top and bottom of the mat by conventional spray techniques.

Table: The mat is not compressed to reach the desired volume. The mat is nominally 4.8mm+/-
It has a thickness of 0.8mm. After application of the powder/liquid binder mixture, the mat is cured after being treated in an oven at about 250 DEG C. to soften and flow the binder around the glass fibers before cooling and solidifying. The cured mat may be trimmed at its edges, inspected, and then rolled or packaged at a suitable processing station if the mat is not required for immediate use. The preferred embodiments described above are intended to illustrate preferred methods of making the preformed mats of the present invention. However, the described binder compositions, amounts, and manufacturing methods are not intended to limit the scope and content of the claims. It has been found that the present invention is useful in the production of fiberglass preform mats used in structural resin injection molding (RIM) processes.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a preformable fiber mat having an upper surface and a lower surface, comprising: (a) manufacturing a continuous glass fiber material from a glass molding bush; (b) the glass fibers as described above; Forming size is applied to the material; (c) The above glass fiber material is sized to 10.16 cm (4 inches).
(D) Form the shredded glass fiber material into mats; (E) Apply a thermoplastic binder to the mats; ) heating the mat so that the thermoplastic binder material softens and flows around the glass fiber material; and (g) cooling and solidifying the thermoplastic binder material. 2 10.16 cm (4 inches) of about 40% by weight of the mat
60% by weight of fibers shredded into
2. A method according to claim 1, characterized in that the method comprises fibers chopped into 1 inch). 3. Process according to claim 1, characterized in that the thermoplastic binder material comprises an equal mixture of a styrene-soluble thermoplastic powdered polyester resin and powdered polystyrene. 4. The method of claim 3, wherein the binder material further comprises an emulsion, and the binder is applied to the mat as a mixture of about 55% by weight powder and 45% by weight emulsion. 5. Process according to claim 4, characterized in that the emulsion comprises polyvinyl acetate Mouris D-50 from Hoechst, plasticized with 3% polyethylene glycol adipate. 6. A method according to claim 4, characterized in that the powdered binder material is transferred to the mat and the emulsion is applied to the top and bottom surfaces of the mat. 7. Process according to claim 1, characterized in that the mat is heated to a temperature of about 250°C.