A PROCESS FOR PRODUCING A MOLDED ARTICLE AND THE MOLDED ARTICLE PRODUCED THEREBY

Abstract

Process for producing a molded article, comprising a long fiber thermoplastic composite sheet (1) and a short fiber filled thermoplastic (2,3) component, preferably injected over the surface of the composite sheet, that are thermoformed.

Claims

1.-10. (canceled)

11. A process for producing a molded article which comprises a composite part and at least one functional and/or structural thermoplastic part, wherein the composite part and the functional and/or structural thermoplastic part are directly attached to each other, wherein the process comprises the following steps: i) providing a composite sheet containing a thermoplastic material a and continuous fibers and comprising at least one preset region used for forming said at least one functional and/or structural thermoplastic part, ii) applying a preset volume of thermoplastic material b comprising short fibers at said at least one preset region by 3D printing layer-by-layer in a way of fused deposition using three-dimensional printer controlled by the computer, without inserting an insert with a mold; and iii), thermoforming said composite sheet and said thermoplastic material b into the molded article in one step, wherein the composite sheet is thermoformed to form said composite part and the thermoplastic material b is thermoformed to form the at least one functional and/or structural thermoplastic part.

12. The process according to claim 11, wherein said molded article is a housing or part of a housing of an electronic product.

13. The process according to claim 12, wherein said molded article is a housing or part of a housing of a laptop or a cell phone.

14. The process according to claim 11, wherein the thermoplastic material a and/or the thermoplastic material b is/are selected from the group consisting of polycarbonate, acrylonitrile-butadiene-styrene copolymer, polymethyl methacrylate, or the combination thereof.

15. The process according to claim 11, wherein said composite sheet is a carbon fiber- or glass fiber-reinforced polycarbonate composite sheet.

16. The process according to claim 11, wherein the continuous fibers are unidirectionally aligned.

17. The process according to claim 11, wherein said functional or structural part is selected from the group consisting of a screw column, a signal sending and receiving area and/or reinforcing ribs.

18. The process according to claim 11, wherein the short fibers are glass fibers.

19. A molded article produced by the process according to claim 11.

20. The molded article according to claim 19, wherein the article is a housing or part of a housing of a laptop or a cell phone.

Description

DESCRIPTION OF THE DRAWINGS

[0087] The present invention is further illustrated with the help of the following figures, but is not limited thereto.

[0088] FIG. 1 is the schematic drawing of the composite sheet used as cover-A of a laptop in an exemplary embodiment according to the present invention, which is cut by a computer numerical controlled machine (CNC).

[0089] FIG. 2 is the schematic drawing of supplementing materials (applied thermoplastic polymer) in the preset region of the composite sheet through a) injection molding or b) three-dimensional printing in an exemplary embodiment according to the present invention.

[0090] FIG. 3 is a figure displaying the deflection (deformation) of sample that varies with the load in an exemplary embodiment according to the present invention.

[0091] FIG. 1 shows an exemplary embodiment according to the present invention in which 1 represents a composite sheet. When performing CNC cutting, the composite sheet is first cut into preset size, and then is cut to obtain edges, including projections and depressions, according to specific requirements for molding articles such as an A-Cover of a laptop. These may be adjusted in accordance with the respective product. In addition, since conventional carbon fiber reinforced thermoplastic polymeric composites have electromagnetic shielding for wireless signals, it is needed to cut a signal sending and receiving area 3 at the lower position of the composite sheet in the course of producing an A-Cover of the laptop. This area can be supplemented with glass fiber reinforced thermoplastic polymers having no electromagnetic shielding, as described below. The material supplement of a region having special structure for example a longer reinforcing rib may be employed by means of designing the mold to supplement the material on the surface of composite sheet by injection molding. The resulting composite blank sheet has a shape as shown in FIG. 1, wherein it generally has a thickness of about 0.60 to 1.4 mm. The size and thickness thereof, however, are not limited thereto, but can be adjusted in wide ranges according to actual requirements.

EXAMPLES

[0092] With reference to the examples below, the present invention will be described in detail. These examples are only for the purpose of illustration, instead of intending to limit the scope of the present invention.

[0093] Raw Material and Apparatus

[0094] continuous carbon fiber-reinforced polycarbonate composite sheet (fibers unidirectionally aligned) containing 50 vol.-% carbon fibers, CF FR1000, from Covestro;

[0095] short glass fiber-reinforced polycarbonate containing 50 wt.-% glass fibers, Makrolon GF9020, available from Covestro;

[0096] Injection molding machine, ENGEL DUO 3550/650, available from Engel Machinery Co., Ltd.;

[0097] Hot pressing molding machine, HPFM-500A, available from Dongguan Qiaolian Machine Co., Ltd.;

[0098] Load-deformation tester, 9603SP, available from SE Testsystems Co., Ltd.

Example 1

[0099] Preparation of Molded Article According to the Invention

[0100] i) A composite sheet CF FR1000 with a thickness of 1.0 mm was cut into a size of 324 mm length and 210 mm width by CNC.

[0101] ii) The cut composite sheet was positioned into a mold of the injection molding machine, the mold was closed and the injection was performed to apply the required amount of thermoplastic materials b onto the composite sheet, so that 8 cm.sup.3 of glass fiber-reinforced polycarbonate Makrolon GF9020 (50 wt.-% glass fibers) was injection molded into a signal sending and receiving area 3, and 0.6 cm.sup.3 and 1.3 cm.sup.3 of glass fiber-reinforced polycarbonate Makrolon GF9020 (50 wt.-% glass fibers) were injection molded into a screw column 2 and a reinforcing rib 4, respectively (as shown in FIG. 1); wherein the melt temperature for injection molding was 300 C., the mold temperature was 90 C., the injection pressure was 100 MPa, and the back pressure was 0.8 MPa; and wherein signal sending and receiving area 3 was in the form of two 6 cm1 cm0.1 cm (lwh) rectangles, the symcenter of the two rectangles having a distance from the lower edge of the composite material sheet of 0.2 cm, and each of the left/right rectangle having a distance from the left/right edge of the composite material sheet of 1 cm, screw column 2 was a cylinder with an inner diameter of 3 mm, the axis of which had a distance from the left/right edge of the composite material sheet of 0.3 cm, and reinforcing rib 4 was a stick with a width of 0.43 cm, which had a distance from the upper edge of the composite material sheet of 1 cm, was parallel to the composite sheet in length direction and ran through the composite sheet in length direction.

[0102] iii) After completion of injection and after cooling down and demoulding, the composite sheet on which the requested volume of thermoplastic material was added to the preset region by injection molding process, during thermoforming process the added thermoplastic material was formed into functional areas, functional and/or structural parts on the composite sheet. For the thermoforming process, the mold temperature was set at 200 C. and the sheet was heated up, the sheet was kept at this temperature for about 30-60 see, then a pressure of about 15 MPa was applied and held for about 20-30 sec on the sheet to thermoform it. The composite part with the structural and/or functional parts was subsequently cooled and demoulded, to give the molded article according to the invention of sample 1.

Example 2

[0103] Preparation of Molded Article in the Prior Art

[0104] i) A composite sheet CF FR1000 with a thickness of 1.0 mm was cut into a size of 324 mm length and 210 mm width by CNC, using the process as described in step i) of Example 1.

[0105] ii) The precut sheet was placed in the thermoforming mold, the mold temperature was set at 200 C. and the sheet was heated up and was kept at this temperature for about 30-60 see, then a pressure of about 15 MPa was applied and held for about 20-30 sec on the sheet to thermoform the sheet. Afterwards, the mold was cooled down to about 75 C. and the formed sheet, the composite part, was demolded.

[0106] iii) The above mentioned composite part was placed in the injection molding mold, the barrel temperature was set at 280-320 C., injection speed profile (max injection speed at 150 mm/s) and holding pressure were set at 70% of max injection pressure, then the edges of the sheet were overmolded to form bosses, ribs, edges and antenna areas.

[0107] After completion of injection and after demoulding and cooling down, the molded article in the prior art of sample 2 was given.

[0108] Performance Test

[0109] The samples 1 and 2 as given above were tested. During testing, the sample was put on the platform of a load-deformation tester 9603SP available from SE Testsystems Co., Ltd., and extruded at a front edge thereof (which was located at the bonding areas in the two-step molding) by using a probe. On the basis of an initial load, the force loaded on the sample was increased gradually, and meanwhile the deflection of the sample surface was measured relative to the horizontal plane, until ruptures occurred in the sample. The testing parameters were as shown in Table 1.

TABLE-US-00001 TABLE 1 Distance between Distance between Distance between the center of the the center of the the center of the probe and the right probe and the left probe and the front Initial probe Load Deflection Load edge of the sample edge of the sample edge of the sample load diameter range range speed Sample (mm) (mm) (mm) (kgf) (mm) (N) (mm) (mm/min) 1 246 78 3 0.01 10 500 5 2 2 246 78 3 0.01 10 500 5 2

[0110] The testing results were as shown in Table 2.

TABLE-US-00002 TABLE 2 Maximum deflection before the Sample rupture (mm) Max load (N) 1 2.130 246.8 2 1.270 122.6

[0111] FIG. 3 shows that the deflection of the two samples changes as the load changes. It can be seen from the results in Table 2 and FIG. 3 that the bonding strength at bonding areas of sample 1 according to the present invention is significantly greater than that of sample 2 obtained by the process according to the prior art. Furthermore, it was identified that the surface defects at bonding areas were considerably reduced, and no warpage occurred at the filled areas in case of the molded article according to the invention. In addition, the mold used in the injection molding of the process according to the invention was simpler than the one used in the injection molding of the process in the prior art, and the cost was lower.

[0112] The above are only preferred examples of the present invention, being not employed to limit the invention. For those skilled in the art, various modifications and variations can be made to the compositions and methods of the present invention without departing from the scope of the invention. With reference to the disclosure in the present description, those skilled in the art may also reach other examples. The present description and examples should be only regarded as illustrative, and the true scope of the present invention is defined by the appended claims and their equivalents.