JPH0299657A - Preformable mat - Google Patents

Abstract

PURPOSE: To obtain a preforable mat suitable for preforming a complicated shape by applying a specific thermoplastic binder to a mat formed from a glass fiber material having a specified fiber length and a mixed specific wt.%, heat-treating the resultant mat and then cooling and solidifying the heat-treated mat. CONSTITUTION: This preformable mat is obtained by applying forming size to a glass fiber material, chopping the resultant glass fiber material, mixing 40 wt.% of the cut material having 10.16 cm fiber length with 60 wt.% of the cut material having 15.24 cm fiber length, forming the mat, then applying a thermoplastic binder using an emulsion containing 55 wt.% of a mixture of equal amounts of a styrene-soluble polyester resin powder and a polystyrene resin powder and 45 wt.% of a polyvinyl acetate mowlith D-50 plasticized with 3% of polyethylene glycol ester adipate to the formed mat, subsequently heat- treating the formed mat at 250 deg.C, surrounding the glass fiber material with the binder, then cooling the mat and solidifying the thermoplastic binder.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to improved fiber mats and methods of making said mats. The improved fiber mat described above is intended for use as a preformable mat applied to mold fiber-reinforced complex shapes by structural resin injection molding (RIM) methods.

BACKGROUND OF THE INVENTION Preformable mats are generally manufactured using a heated Matched die having the desired final shape.
die) a continuous strand (s
trand) Ia fibers or chopped fibers. The fibers are usually bonded together by thermoset or heat softenable polyester resin materials and are also described in U.S. Pat.
As disclosed in No. 71, an IJ Fuchs matrix resin is added to facilitate shape retention during preforming. U.S. Pat. No. 3.718.954 and 3;
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 US Pat. No. 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 being manufactured by new and improved processing methods that require 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 cracking or attenuation. The mat must also maintain sufficient volume to ensure proper flow of resin through the preform during the RIM process. The fibers are dispersed too thinly or too tightly! If it is too compacted, the proper resin/fiber concentration will not be properly achieved throughout the product.

In the second manufacturing method, U.S. Patent No. 3.936.588;
and 3.718.954 are excluded. This process generally utilizes auxiliary machinery to apply the fiber roving directly to the preform. The present invention provides an improved mat that does not require the auxiliary machinery described above and is used in the preforming process.

The object of the present invention is 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 a preformed mat with sufficient volume to provide proper mat 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 object of the invention is achieved by utilizing two different lengths of fiber strands in the drying 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 deposition of the fibers, a three-component binder system is applied and the mat is heated to solidify the binder. The finished mat has sufficient tensile strength to be wound into rolls to produce a transportable product.

The present invention provides improved preformed mats and methods of making the mats described above. The preform 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 generally 2986 meters per kilogram of glass (1.2 meters per bond).
240 yards) of filament. As the fibers are molded, forming sizes are applied. Suitable compositions of the above foaming sizes are listed in Table 1. After applying the forming size, the filament is divided and assembled into 12 different parts.

Table ■ OCF epoxy emulsion 8.78
33.26 73.25 ice vinegar
Acid 0.03 0.100.
23 Chromium nitrate 0.36 1.3650% solution 3.00 Ammonium chloride 0.04 0.140.30 100.00 378.64834.00 The bundled glass fibers are preferably 10.16 cm (
4 inches) and 15.24 cm (6 inches) and dry stacked into mats. The glass fibers are typically 1 inch (2.54 cm) before being assembled into the mat.
This variation in fiber length is a major improvement over the production of conventional shredded strand mats, which are chopped into one length between 2 and 3 inches. be. 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.

10.16 cm (4 inches) and 15.24 cm as described above
The chopped fibers (6 inches) are deposited as a mat in a 40/600 weight ratio.

The mat is bound after its formation. Preferably, a three-component binder system is used, comprising a mixture of two powders which is transferred onto the mat and an emulsion which is slave-kneaded onto the top and bottom of said mat. The above powder mixtures and emulsions are 55/4
It is applied to the mat as a 5 weight percent mixture.

The preferred powdered binder is an equal mixture of polystyrene and a styrene-soluble thermoplastic powdered polyester resin having the properties listed in Table 1. The powder mixture is
The mat is applied with a conventional vibrator and spreader.

Table ■ Softening point, φC108114S-04-3 Zinc stearate 0.7 1.5 35 mesh 80 mesh 200 mesh 58, O 12,5 0,1 78,5 32,5 The above-mentioned preferred emulsions are as shown in Table ■ polyvinyl acetate mowlith from Hoechst plasticized with 3% polyethylene glycol adipate having the properties described in
D-50 is mentioned. The emulsion is sprayed onto the top and bottom of the mat by conventional spraying techniques.

Table ■ Characteristic Solid content % brookfield viscosity Plasticizer % Acidity index (mg KOH/g) Particle size, micron P.8. 1:9 % Acetone insoluble content c, p, s.

Maximum Minimum 0.8 1.2 After application of the powder/liquid binder mixture, the mat is treated in an oven at about 250° C. in order to soften the binder and allow it to flow around the glass fibers before cooling and solidifying. Let it harden. 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 preformed mats used in structural resin injection molding (RIM) processes.

The mat is not compressed so that the desired volume is achieved. The mat is nominally 4.8 mm +/-0
, has a thickness of 8 mm.

Claims (8)

[Claims] 1. A method of manufacturing a preformable fiber mat having a top surface and a bottom surface, the method comprising: (a) manufacturing a continuous glass fiber material from said glass forming bushing; (b) forming a forming size in said glass fiber material. (c) Shredding the glass fiber material into at least two clearly different lengths; (d) Forming the shredded glass fiber material into a mat; (e) Shredding the glass fiber material into a mat; (f) heating the mat so that the thermoplastic binder material softens and flows to surround the glass fiber material; and (g) applying the thermoplastic binder material to the mat. The method includes cooling the mat to solidify it. 2. The glass fiber material is 10.16 cm (4 inches)
2. The method of claim 1, wherein the method is cut into lengths of 15.24 cm (6 inches). 3. The mat contains about 40% by weight shredded 10.16 cm (4 inch) fibers and about 60% by weight chopped 15.24 inch fibers.
3. A method according to claim 2, characterized in that it comprises fibers chopped into cm (6 inches). 4. 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. 5. 5. The method of claim 4, 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. 6. 6. Process according to claim 5, characterized in that the emulsion comprises polyvinyl acetate Mouris D-50 from Hoechst, plasticized with 3% polyethylene glycol adipate. 7. 6. A method according to claim 5, 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. 8. 2. A method according to claim 1, characterized in that the mat is heated to a temperature of about 250<0>C.