Patent Application
20190152212
This application claims the priority benefit of Taiwan application serial no. 106140622, filed on Nov. 22, 2017. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.
The invention relates to a multi-layer composite sheet manufacturing method, and more particularly, to a manufacturing method of a thermoplastic continuous-discontinuous fiber composite sheet.
A fiber-reinforced sheet formed by a matrix resin and a reinforcing fiber has good mechanical properties, is lightweight, and resistant to corrosion, and is therefore extensively applied in the material of components of, for instance, aircraft, automobiles, and sports equipment.
The current thermoplastic continuous fiber sheet is mostly formed by thennally compressing a plurality layer of a continuous fiber cloth and a thermoplastic polymer, and in comparison to a traditional thermosetting continuous fiber material, the features of rapid molding and recyclability are achieved, but significant drawbacks still exist in actual use.
In terms of recycling, the current recycling containing a thermoplastic continuous fiber material mostly adopts a pyrolysis method and a high-temperature furnace is needed to maintain a suitable temperature, a polymer is selectively pyrolyzed, and the fiber is left. Although this method can retain the maximum fiber length, the process energy consumption is high, and during the pyrolysis, the sizing of the fiber surface is broken down at the same time, thus affecting the subsequent fiber reusability in resin impregnation. Moreover, the polymer and fiber are separated using a solvent, which not only consumes solvent, but also requires energy to separate the solvent and the polymer, thus causing more environmental issues.
Another recycling and reuse method includes mixing and granulating a recycled continuous fiber substrate (such as byproducts of a continuous fiber substrate) and a thermoplastic resin and using the particles as a raw material for an injection process. This method has low technical requirements and is time-tested, and is easy to use. However, when injection molding is directly performed, fiber of byproducts cannot be sufficiently dispersed in a thermoplastic resin. Moreover, via screw mixing and granulation and screw melting of an injection machine followed by high-pressure shear promotion, after going through a runner injection mold, the fiber length in the material is significantly reduced, and mechanical enhancements are limited. Therefore, JP2006-218793 discloses crushing and granulating a carbon fiber-reinforced thermoplastic resin molded product and then mixing with a new carbon fiber-reinforced thermoplastic resin particle and performing injection molding. However, production cost is increased as a result.
Moreover, WO 2012086682 A1 (CN 103119209 A, EP 2642007 A1, and US 20130192434) discloses a method of manufacturing a carbon fiber-reinforced plastic. In the method, byproducts of a carbon fiber substrate containing carbon fiber are cut, and the resulting cut pieces are added in a thermoplastic resin fiber during a carding process to obtain a carbon fiber aggregate containing a thermoplastic resin fiber. Next, the carbon fiber aggregate containing a thermoplastic resin fiber is immersed in a matrix resin and molded to obtain a carbon fiber-reinforced plastic. However, the carbon fiber aggregate obtained by the method above still requires a dipping process, and the time required is long, and reusability and environmental friendliness are poor.
Moreover, in comparison to a thermosetting continuous fiber material, the formability of the traditional continuous fiber thermoplastic material is very poor, and a component with complex geometric structure cannot be formed. In particular, the formability of the portion with greater curvature of a sheet with large thickness is very poor, and wrinkles readily occur. The thermoplastic carbon fiber sheet has a relatively small application scope due to low forming complexity.
However, to achieve a multi-layer carbon fiber composite sheet with large thickness, the surface layer is a continuous carbon fiber and the intermediate core layer is mostly a honeycomb structure or a foaming material, but secondary forming is not possible for this method, material utilization is low, and material cost cannot be effectively reduced.
The invention provides a manufacturing method of a thermoplastic continuous-discontinuous fiber composite sheet that can achieve a thermoplastic continuous-discontinuous fiber composite sheet with good flexural properties and formability.
The manufacturing method of the thermoplastic continuous-discontinuous fiber composite sheet of the invention includes providing a thermoplastic composite, wherein the theinioplastic composite includes a continuous fiber and a first thermoplastic resin; performing a mechanical treatment on the thermoplastic composite to form a plurality of fragments, such that the continuous fiber is changed into a discontinuous fiber; forming at least one thermoplastic discontinuous fiber aggregate layer using the plurality of fragments as a raw material; and thermally compressing the at least one thermoplastic discontinuous fiber aggregate layer and the at least one thermoplastic continuous fiber layer.
In an embodiment of the invention, the step of thermally compressing the at least one thermoplastic discontinuous fiber aggregate layer and the at least one thermoplastic continuous fiber layer can include overlapping the thermoplastic discontinuous fiber aggregate layer and the two thermoplastic continuous fiber layer and performing thermal compression such that the thermoplastic discontinuous fiber aggregate layer is clamped between the two thermoplastic continuous fiber layers.
In an embodiment of the invention, the step of thermally compressing the at least one thermoplastic discontinuous fiber aggregate layer and the at least one thermoplastic continuous fiber layer can include overlapping the thell ioplastic continuous fiber layer and the two thermoplastic discontinuous fiber aggregate layer and performing thermal compression such that the thermoplastic continuous fiber layer is clamped between the two thermoplastic discontinuous fiber aggregate layers.
In an embodiment of the invention, the step of thermally compressing the at least one thermoplastic discontinuous fiber aggregate layer and the at least one thermoplastic continuous fiber layer includes alternately overlapping the thermoplastic continuous fiber layer and the thermoplastic discontinuous fiber aggregate layer and performing thermal compression.
In an embodiment of the invention, before thermally compressing the at least one theiinoplastic discontinuous fiber aggregate layer and the at least one thermoplastic continuous fiber layer, a strengthening layer can further be formed on at least one surface of the thermoplastic discontinuous fiber aggregate layer, wherein the strengthening layer is at least located between the thermoplastic discontinuous fiber aggregate layer and the thermoplastic continuous fiber layer.
In an embodiment of the invention, the strengthening layer is, for instance, formed by a single film layer or a powder.
In an embodiment of the invention, the method of forming the thermoplastic discontinuous fiber aggregate layer can include thermally compressing the plurality of fragments.
In an embodiment of the invention, the method of thermally compressing the plurality of fragments is, for instance, molding or stamping.
In an embodiment of the invention, the method of forming the thermoplastic discontinuous fiber aggregate layer can include mixing and granulating the plurality of fragments to form a plurality of particles; and performing injection molding using the plurality of particles.
In an embodiment of the invention, the method of thermally compressing the thermoplastic discontinuous fiber aggregate layer and the thermoplastic continuous fiber layer includes laminating using a flat film or a flat steel sheet.
In an embodiment of the invention, the continuous fiber in the thermoplastic composite is, for instance, carbon fiber, glass fiber, basalt fiber, metal fiber, ceramic fiber, or chemical fiber.
In an embodiment of the invention, the first thermoplastic resin in the thermoplastic composite is, for instance, polycarbonate (PC), polypropylene (PP), polysulfone (PS), thermoplastic polyurethane (TPU), acrylonitrile butadiene styrene resin (ABS), polyethylene (PE), thermoplastic epoxy resin, polyurethane resin, polyurea resin, or a combination thereof.
In an embodiment of the invention, the strengthening layer includes a second thermoplastic resin.
In an embodiment of the invention, the second thermoplastic resin includes polycarbonate, polypropylene, polysulfone, thermoplastic polyurethane, acrylonitrile-butadiene-styrene resin, polyethylene, thermoplastic epoxy resin, polyurethane resin, polyurea resin, or a combination thereof.
In an embodiment of the invention, the first thermoplastic resin is different from the second thermoplastic resin.
In an embodiment of the invention, the length of the discontinuous fiber is 3 mm to 20 mm.
In an embodiment of the invention, the length of the discontinuous fiber is less than 3 mm.
In an embodiment of the invention, the length of the discontinuous fiber is 20 mm to 50 mm.
In an embodiment of the invention, the thermoplastic composite is a recycled thermoplastic composite.
Based on the above, the thermoplastic continuous-discontinuous fiber composite sheet of the invention has a structure formed by a thermoplastic continuous fiber layer and a thermoplastic non-continuous fiber aggregate layer, and therefore has good flexural properties and formability.
In order to make the aforementioned features and advantages of the disclosure more comprehensible, embodiments accompanied with figures are described in detail below.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
Some embodiments are provided hereinafter and described in detail with reference to figures. However, the embodiments provided are not intended to limit the scope of the invention. Moreover, the figures are only descriptive and are not drawn to scale. For ease of explanation, the same devices below are provided with the same reference numerals. Moreover, terms such as “contain”, “include”, and “have” used in the specification are all open terms, i.e., contains, but not limited to. Moreover, directional terms used in the specification such as “up” and “down” are only directions used in the figures. Therefore, the directional terms are used to illustrate and are not intended to limit the invention.
Referring to
In an embodiment, the length of the discontinuous fiber in the thermoplastic discontinuous fiber aggregate layer 102 is 3 mm to 20 mm. In another embodiment, the length of the discontinuous fiber in the thermoplastic discontinuous fiber aggregate layer 102 is less than 3 mm. In yet another embodiment, the length of the discontinuous fiber in the thermoplastic discontinuous fiber aggregate layer 102 is 20 mm to 50 mm.
The thermoplastic continuous fiber layer 104 includes a continuous fiber and a second thermoplastic resin. In an embodiment, the continuous fiber in the thermoplastic continuous fiber layer 104 is, for instance, a material such as carbon fiber, glass fiber, basalt fiber, metal fiber, ceramic fiber, or other chemical fibers; the second thermoplastic resin in the thermoplastic continuous fiber layer 102 is, for instance, polycarbonate, polypropylene, polysulfone, thermoplastic polyurethane, acrylonitrile-butadiene-styrene resin, polyethylene, thermoplastic epoxy resin, polyurethane resin, polyurea resin, or a combination thereof. In an embodiment, the thermoplastic continuous fiber layer 104 is, for instance, a continuous fiber cloth impregnated by a thermoplastic resin.
The thermoplastic continuous-discontinuous fiber composite sheet 100 has a structure formed by a thermoplastic continuous fiber layer and a thermoplastic discontinuous fiber aggregate layer, and therefore has good flexural properties and formability.
In general, the stacking between fibers may produce spaces, such that mechanical strength is reduced. In the present embodiment, since the strengthening layer 103 is formed between the thermoplastic discontinuous fiber aggregate layer 102 and the thermoplastic continuous fiber layer 104, the strengthening layer 103 can be filled to level the space between the thermoplastic discontinuous fiber aggregate layer 102 and the thermoplastic continuous fiber layer 104 to enhance the overall mechanical properties of the resulting product. Moreover, if the surface of the thermoplastic discontinuous fiber aggregate layer 102 is a smooth surface, then the surface can also be modified to increase the bonding between the thermoplastic discontinuous fiber aggregate layer and the subsequent structural layer using the thermoplastic resin different from the thermoplastic resin in the thermoplastic discontinuous fiber aggregate layer 102. Moreover, the thermoplastic fiber layer is generally bonded with a regular engineering plastic (a different type of material), but the thermoplastic fiber layer cannot satisfy the lamination of all of the different types of materials. In the present embodiment, since the strengthening layer 103 is formed on the surface of the thermoplastic discontinuous fiber aggregate layer 102, interface modification can be performed on the surface of the thermoplastic discontinuous fiber aggregate layer 102 via the strengthening layer 103 to increase the bonding of different types of materials.
Referring to
Next, in step S102, a mechanical treatment is performed on the thermoplastic composite to form a plurality of fragments such that the continuous fiber is changed into a discontinuous fiber. In an embodiment, the mechanical treatment includes crushing the recycled thermoplastic composite having a fiber length less than 20 mm. In another embodiment, the mechanical treatment includes shredding the recycled thermoplastic composite having a fiber length of 20 mm or more with a shredder. The fragments from the mechanical treatment can include short fibers, long fibers, or super-long fibers. For instance, the fragments obtained from crushing are, for instance, short fibers with a fiber length of less than 5 mm or long fibers with a fiber length of 5 mm to 20 mm; and the fragments obtained from shredding are, for instance, super-long fibers with a fiber length greater than 20 mm.
Next, in step S104, at least one thermoplastic discontinuous fiber aggregate layer 102 is formed by directly using the fragments as a raw material. In an embodiment, the method of forming the thermoplastic discontinuous fiber aggregate layer 102 can include mixing and granulating the fragments to form a plurality of particles and then performing injection molding using the particles as shown in
Next, in step S106, the at least one thermoplastic discontinuous fiber aggregate layer 102 is thermally compressed with at least one thermoplastic continuous fiber layer 104. The method of thermally compressing the thermoplastic discontinuous fiber aggregate layer 102 and the thermoplastic continuous fiber layer 104 includes laminating using, for instance, a flat film or a flat steel sheet. At this point, the thermoplastic continuous-discontinuous fiber composite sheet 100 of the invention is complete.
The thermoplastic continuous-discontinuous fiber composite sheet 100 has a structure formed by a thermoplastic continuous fiber layer and a thermoplastic non-continuous fiber aggregate layer, and therefore has good flexural properties and formability.
In
Therefore, in an embodiment, before step S106 is performed, the strengthening layer 103 can be formed on at least one surface of the thermoplastic discontinuous fiber aggregate layer 102. Next, thermal compression is performed such that the strengthening layer 103 is at least located between the thermoplastic discontinuous fiber aggregate layer 102 and the thermoplastic continuous fiber layer 104. Since the strengthening layer 103 is formed between the thermoplastic discontinuous fiber aggregate layer 102 and the thermoplastic continuous fiber layer 104, the strengthening layer 103 can be filled to level the space between the thermoplastic discontinuous fiber aggregate layer 102 and the thermoplastic continuous fiber layer 104 to enhance the overall mechanical properties of the resulting product. Moreover, in the present embodiment, the strengthening layer 103 is formed on opposite surfaces (i.e., the first surface 102a and the second surface 102b) of the thermoplastic discontinuous fiber aggregate layer 102 as shown in
In an embodiment, the step of thermally compressing the at least one thermoplastic discontinuous fiber aggregate layer and the at least one thermoplastic continuous fiber layer can include first overlapping a thermoplastic discontinuous fiber aggregate layer and two thermoplastic continuous fiber layers and performing thermal compression such that the thermoplastic discontinuous fiber aggregate layer 112 of the thermoplastic continuous-discontinuous fiber composite sheet 300 is clamped between two thermoplastic continuous fiber layers 114 as shown in
In an embodiment, the step of thermally compressing the at least one thermoplastic discontinuous fiber aggregate layer and the at least one thermoplastic continuous fiber layer can include overlapping a thermoplastic continuous fiber layer and two thermoplastic discontinuous fiber aggregate layers and then performing thermal compression such that the thermoplastic continuous fiber layer 124 of the thermoplastic continuous-discontinuous fiber composite sheet 400 is clamped between two thermoplastic discontinuous fiber aggregate layers 122 as shown in
In an embodiment, the step of thermally compressing the at least one thermoplastic discontinuous fiber aggregate layer and the at least one thermoplastic continuous fiber layer includes: alternately overlapping the thermoplastic continuous fiber layer and the thermoplastic discontinuous fiber aggregate layer and performing thermal compression to obtain the thermoplastic continuous-discontinuous fiber composite sheet shown in
Moreover, in other embodiments, a thermoplastic discontinuous fiber aggregate layer 102 and a thermoplastic continuous fiber layer 104 with different sizes can be selected for thermal compression to form a thermoplastic continuous-discontinuous fiber composite sheet 700 of the complex structure of
Several experimental examples are described below to verify the efficacy of the invention. However, the invention is not limited to the following content.
First, a thermoplastic composite having a carbon fiber with a fiber length less than 20 mm was crushed to obtain fragments with a fiber length of 3 mm to 20 mm (i.e., crushed material). Next, the crushed material was mixed and granulated, that is, fresh plastic material was added for mixing to produce particles (fiber length less than 3 mm), and then injection molding was performed using the particles to obtain a thermoplastic discontinuous fiber aggregate layer. Next, the thermoplastic discontinuous fiber aggregate layer and two layers of 3K prepreg cloth (i.e., thermoplastic continuous fiber layers) were thermally compressed, wherein the 3K prepreg cloth refers to a prepreg cloth formed by weaving a 3K carbon yarn in half warp and half weft. The resulting structure is a sandwich structure of thermoplastic continuous fiber layer/thermoplastic discontinuous fiber aggregate structure/thermoplastic continuous fiber layer with thermoplastic continuous fiber layer as the upper and lower outer layers.
First, a thermoplastic composite having a carbon fiber with a fiber length less than 20 mm was crushed to obtain fragments with a fiber length of 3 mm to 20 mm (i.e., crushed material). Next, the crushed material was thermally compressed to form a thermoplastic discontinuous fiber aggregate layer.
First, a thermoplastic composite having a carbon fiber with a fiber length of 20 mm or more was shredded by a shredder to obtain fragments with a fiber length of 20 mm to 50 mm (crushed material). Next, the crushed material was thermally compressed to form a thermoplastic discontinuous fiber aggregate layer.
Control Group
Three layers of unidirectional prepreg cloth and two layers of 3K prepreg cloth were thermally compressed, wherein the unidirectional prepreg cloth and the 3K prepreg cloth are both thermoplastic continuous fiber layers.
Next, a mechanical strength test and an estimate in the decline of mechanical properties and cost were respectively performed on experimental examples 1 to 3 and a control group, and the results are shown in Table 1 below. It should be mentioned that, all of the measurement data is based on the same thickness and the 3K prepreg cloth used are all the same.
It can be seen from Table 1 that, experimental examples 1 to 3 can achieve the effects of 32% to 35% lower cost and maintaining different degrees of mechanical strengths, and material utilization is increased to 99%.
Although the invention has been described with reference to the above embodiments, it will be apparent to one of ordinary skill in the art that modifications to the described embodiments may be made without departing from the spirit of the invention. Accordingly, the scope of the invention is defined by the attached claims not by the above detailed descriptions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 106140622 | Nov 2017 | TW | national |
