AU612496B2 - Preformable mat - Google Patents

Description

T27- rII I Ii c C Our Ref: 279412

AUSTRALIA

Patents Act FORM COMPLETE SPECIFICATION

(ORIGINAL)

612496 Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art: Applicant(s): Address for Service: Gwens-Corning Fiberglas Corporation Fiberglas Tower TOLEDO Ohio 43659 UNITED STATES OF AMERICA ARTHUR S. CAVE CO.

Patent Trade Mark Attornerys Level 10, 10 Barrack Street SYDNEY NSW 2000 4o 4 4 4t 4 44 44 41 '4E Complete specification for the invention entitled "Preformable mat".

The following statement is a full description best method of performing it known to me:of this invention, including the ;1 1 5020 UWti."D yia6 ,urporalon The Commissioner of Patents By DendfSJ 1rvela Asis tant Secretary ARTHUR S. CAVE CO. naure o eclarants) PATENT AND TRADE MARK ATTORNEYS

SYDNEY-

la PREFORMABLE MAT Technical Field 0 00 This invention relates to an improved fibrous mat and S 15 an* the method for producing the mat. The improved fibrous mat a o is intended for use as a preformable mat to be applied to the molding of complex fiber-reinforced shapes by the structural resin injection molding (RIM) process.

Background Art 20 S" o 0 Preformable mats are generally produced either from ao* continuous strand fiber or chopped fiber placed on a heated matched die mold having the final desired shape. The fiber

S'

1 is generally held together by a thermosetting or thermoplastic polyester resin material and during the preform molding, a matrix resin is added to facilitate shape retention such as disclosed in United States Patent Nos.

3,936,558 and 3,969,171. Some processes provide for a nonwovein reinforcement structure which is composed of chopped fiber united into a coherent body without the use of or adhesives as disclosed in United States Patent Nos. 3,718,954 and 3,614,976.

The use of fiber mats to produce fiber einforced preforms of useful shapes for molding to a final product is well-known. Fiber-reinforced articles are being created in 35 new and varied applications requiring that the fiber-reinforcement material be contoured into complex curves and shapes. As the fiber mat goes through the 049v/NNG preform process it is stretched and bent to conform to the shape of the mold. The mat must have sufficient bulk or thickness to conform to the contours of the preform without tearing or thinning undesirably. Also, the mat must retain sufficient bulk to ensure proper resin flow through the preform during the RIM process. If the fibers are too thinly dispersed.

or compacted too tightly, the proper resin/fiber concentration will not be adequately achieved throughout the product.

Another preform manufacturing process eliminates the use of fiber mats such as those produced in United States patent nos 3,936,588; 3,969,171; 3,614,936 and 3,718,954. This process generally utilizes additional machinery to apply fiber So0 rovings directly to a preform. The present invention e ow eliminates the need for this additional machinery and provides an improved mat for use in the preform proc6ss.

In one broad form the present invention is a process for l o° producing a preformable fiber mat having a top surface and a 0 Q bottom surface comprising the steps of: 00of od-o generating continuous glass fiber material from a glass forming bushing; \0 applying forming size to such glass fiber material; o chopping such glass fiber material into at least two distinct and varied lengths; forming such chopped glass fiber into a mat; applying a thermoplastic binder to such mat; heating such mat such that the thermoplastic binder material softens and flows around such glass fiber 2 0491v/NNG material; and, cooling such mat to solidify such thermoplastic binder material.

Disclosure of Invention The present invention achieves its objectives by applying fiber strands of two distinct lengths into a dry mat. The two lengths of fiber ensure that the mat will be formed with sufficient bulk or thickness to provide adequate fiber distribution during the preforming process. After the fibers ao°"o are dry laid, a triple ingredient binder system is applied and o o 0 the mat is heated to set the binder. The finished mat is of 0 sufficient tensile strength to be wound on a roll to produce a 0 a0 shippable product.

00 00 a 0 0 0 o 0 Qa o ceci 2a I- 1 Best Mode of Carrying Out Invention The present invention provides an improved preform mat and the method of manufacturing the mat. The preform mat is advantageous for use with highly complex, contoured preforms used with structural RIM reinforcements.

The preform mat of the present invention is prepared using glass fiber filaments of about 13 microns in diameter.

Continuous filaments are received from a double bushing which generally yields 2986 meters (1,240 yards) of filament kilogram (pound) of glass. As the fibers are formed, a forming size is applied. A preferred composition of the forming size is listed in Table I. After the forming size is applied, the filaments are split and grouped together in twelve distinct bundles.

0 9 0 0 0 9 0 00 0 on 0 0 0 Qom 9 o 00 Material A 309 OCF Epoxy Emulsion 73' 9o 9 0 Glacial Acetic Acid trimethoxysilane o0 o Chromium Nitrate 90 -e o TABLE I by Weight s Received 8.78 0.03 0.12 Kilograms Lbs. Per Per 378 liter 100 Gal.

33.26 73.25 0.10 0.23 0,44 0.96 9 00 4 0004 0444 0 800 00 4 0 04( O 44.

solution 0.36 1.36 3.00 Ammonium Chloride 0.04 0.14 0.30 25 Water (Demineralized) 90.67 343.34 756.26 100.00 378.64 834.00 The bundled glass fibers are chopped, preferably, into 10.16cm (four inch) and 15.24cm (six inch) lengths and dry collected into a mat. The variation in fiber length is a 30 major improvement upon previous chopped strand mat manufacturing wherein the glass fiber was chopped to one length, usually about 2.54cm (one) to 5.08cm (two inches), prior to collection into a mat. The varied fiber length and longer fiber length of the present invention provides a mat 35 having the desirable bulk or thickness characteristics required in complex preforming operations. The 10.16cm (four inch) and 15.24cm (six inch) chopped fibers are laid into the mat on a 40/60 proportion on a weight basis.

L 4 1 The mat is bonded after its formation. Preferably, a triple ingredient binder system is used which is composed of a two powder mixture sifted onto the mat and an emulsion spray applied to the top and bottom of the mat. The mixture and emulsion are applied to the mat in a 55/45 percent by weight mixture.

The powdered binder of preference is a mixture of equal amounts of a styrene soluble thermoplastic powdered polyester resin, having the properties listed in Table TI, and polystryrene. The powder mixture is applied to the mat via traditional vibrators and dusters.

TABLE II Properties Minimum Maximum OCF Test Method Softening point, jC 108 114 S-04-3 .o 15Color, Gardner, 1:1 DMF 7 C-11-4 o "0 Zinc Stearate, 0.7 1.5 Z-01-1 000I oa o Particle Size Distribuo 0 a 0 tion, P-01-13 0 a S° 30 Mesh 0.0 35 Mesh 0.1 oo0 80 Mesh 58.0 78.5 0 0 0 0 200 Mesh 12.5 32.5 o o Through 200 Mesh 10.5 So", The emulsion of preference is a Hoechst polyvinyl 2 5 acetate mowlith D-50 plasticized with three percent of polyethylene glycol ester adipate, having the properties o* listed in Table III. The emulsion is sprayed onto the top S000 S and bottom of the mat by traditional spray equipment.

0 0 o TABLE III 30 Properties Minimum Maximum Solid 48 52 Brookfield Viscosity c.p.s. 12000 28000 Plastificant 0 0 Acidity Index (mg KOH/g) 1 4 3 5 Size of Particles, micron 0.8 1.2 P.H. 1:9 3 4 Insoluble in Acetone 1 The mat is not compacted to achieve the desired bulk.

It is nominally 4.8mm 8mm thick.

After application of the powder/liquid binder mixture, the mat is processed through an oven where it is cured at 2500C to set the binder. The cured mat may have its edges trimmed, be inspected, and then rolled or packaged at a suitable processing station if immediate use of the mat is not required.

The preceding description of the preferred embodiment intended to illustrate a preferred process by which the preform mat of the present invention is manufactured. The description of binder compositions and quantities and process is not, however, intended to be limiting upon the scope and content of the following claims.

o o 15 Industrial Applicability The invention will be found to be useful in making 0 0 a.o glass fiber preform mats for structural resin injection 0 0 o 0 molding (RIM) processes.

0o o0 0 0 a a a o 0 0 f i

Claims (7)

1. A process for producing a preformable fiber mat having a top surface and a bottom surface comprising the steps of: generating continuous glass fiber material from a glass forming bushing; applyir.g forming size to such glass fiber material; V chopping such glass fiber material into at least two distinct and varied lengths; forming such chopped glass fiber into a mat; O applying a thermoplastic binder to such mat- heating such mat such that the thermoplastic binder material softens and flows around such glass fiber material; and, C)0 cc cooling such mat to solidify such thermoplastic binder material.

2. Thol process of claim 1, wherein such glass fiber material 0 0 0 0 is chopped into about four inch lengths and about six inch lengths. 0a44

3. The process of claim 2, wherein such mat is composed of about 40t chopped fiber in about 4 inch lengths and about chopped fiber in about 6 inch lengths by weight,

4. The process of claim 1, wherein such thermioplastic binder II material comprises styrene soluble thermoplastLc powered j polyester resin and powdered polystyrene, mixed in equal amounts. 51 The process of claim 4, wherein such binder material fuirther includes an emulsion, whereby such binder material Is 6 0491v/NNG applied to such mat in a mixture of about 55% powder and emulsion by weight.

6. The process of claim 5, wherein such emulsion comprises a Hoechst polyvinyl acetate mowlith D-50 plasticized with 3% polyethylene glycol ester adipate.

7. The process of claim 5, wherein such powdered binder material is sifted into such mat and such emulsion is applied to the top surface and bottom surface of such mat.

8. The process of claim 1, wherein such mat is heated to a temperature of about 250 C. S9. A process for producing a preformable fiber mat o 0 substantially as herein described with reference to the Tables. o. C 00 0 0 0 o oo a Q DATED this 17th day of April, 1991. 00 00 0 OWENS-CORNING FIBERGLAS CORPORATION By Their Patent Attorneys ARTHUR S. CAVE Co. a t SP7- A