FI97037B - A reinforced product made from a reinforcement and matrix plastic and process for making a reinforced product - Google Patents

Description

97037

Reinforced product made of reinforcement and matrix plastic and method of making the reinforced product

The invention relates to a product made of reinforcement and matrix plastic 5, which is set out in the preamble of appended claim 1. The invention also relates to a method for producing a reinforced product, which method is set out in the preamble of appended claim 6.

10

It is known to manufacture a reinforced product by placing reinforcements in the mold cavity, after which a matrix plastic is introduced into the mold cavity to perform casting. In this case, the reinforcements remain surrounded by the plastic of the matrix-15 and thus a composite body is formed. Structures made of fiberglass or similar strong fibers, such as fabrics or knits, are generally used as the reinforcement. There are several casting techniques in which the above bodies are formed, in which the matrix 20 can be either thermoplastic (normal injection molding), thermoplastic (RIM or Reaction Injection Molding) or thermosetting resin (RTM or Resin Transfer Molding, hart). -25 injection molding).

The problem with all these techniques is that the orientation of the product reinforcements, i.e. the fiberization, cannot be completely controlled. This problem arises especially in the production of pieces of complex shape, in which, for example, exactly a certain fiber orientation or a combination of fiber orientations should be obtained at certain points.

It is an object of the invention to provide a new product which has a controlled fiber orientation and thus a reinforcing effect. To achieve this object, the product according to the invention 2 97037 is mainly characterized by what is set forth in the characterizing part of the appended claim 1. The reinforcement of the product consists of a kind of reinforcement blank in which the reinforcing fibers are obtained in the desired-5, same permanent directions due to the fact that they are connected to each other by means of a thermoplastic matrix before the actual casting. Because the rigid reinforcement blank has remained well in place in the mold during casting at the desired position and / or at the desired casting pressure, the forces exerted by the casting material have not been able to affect the orientation of the fibers in the finished product, such as using previously free reinforcing materials.

15

For other preferred embodiments of the product according to the invention, reference is made to the appended dependent claims 2-5.

It is also an object of the invention to provide a method for producing a reinforced product without the difficulties due to fiberization. To achieve this object, the method is characterized by what is set forth in the characterizing portion of the appended claim 6. For other preferred embodiments of the method according to the invention, reference is made to the appended dependent claims 7-9.

The invention will now be described in more detail with reference to the accompanying drawings, in which: Figure 1 shows a front view of a reinforcement used in a product according to the invention; Figure 2 shows another reinforcement used in the invention in perspective;

II

3 97037 Figure 3 shows a cross-section of a mold before casting and 5 Figure 4 shows examples of castings according to the invention.

Figure 1 shows a reinforcement used in the product. It is a reinforcing blank formed of a 10 staple fiber-reinforced thermoplastic impregnate obtained by impregnating a bundle of several continuous parallel reinforcing filaments with a thermoplastic matrix to form a filament-reinforced yarn 1 held together by the thermoplastic. The filaments are denoted by reference numeral 2 in Figure 1, and although for the sake of clarity only a few are shown, there may be more than one hundred, normally 1,000 to 2,000, in parallel in one yarn. The wire itself may be circular or flat in cross section or other shapes depending on the impregnation technique. What all the yarns have in common is that the solidified thermoplastic matrix joins the continuous filaments together.

Figure 1 shows a 2-dimensional reinforcing blank structure, which means that the main directions of the wire 1 and at the same time the reinforcing filaments 2 are always in the same plane or parallel planes in the reinforcing blank where the different portions of the wire 1 are joined together by a molten thermoplastic matrix. The portions of the yarn 1 can be fed together, for example by braiding or weaving a solidified thermoplastic impregnate, whereby the different portions of the yarn 1 are fused together into a planar structure by means of a separate heat treatment. There may be several such planar layers on top of each other to form a rigid 2-35 dimensional reinforcement blank.

Although the same continuous yarn 1 can be used to form the blanks, it can also be formed from 4 97037 of several different yarns 1, which may have, for example, different reinforcing structures. For example, in the structure of FIG. In this case, yarns comprising the same filament material with different filament / thermoplastic matrix ratios or yarns formed of different filaments can be used. For example, the sections 10 of the yarn 1 running in one direction may contain fiberglass reinforcement and the sections of yarn 1 running in the other direction may contain carbon fiber reinforcement.

Figure 2 shows a part of another type of reinforcement blank. This can be referred to as a 3-dimensional structure 15, because it has, in relation to the wire sections running in the same plane described above, also sections of wire 1 whose main direction is transverse to the above-mentioned planes. This increases the possibilities for reinforcing the product in the desired directions, and combinations of different types of yarns 1 can also be used here according to the same principle as described above. In the case of Fig. 2, the portions of the wire 1 running in the direction of the third dimension are arranged through the openings 3 between the portions of the wire 1 formed by the 2-dimensional structure and can thus pass through several parallel 2-dimensional planes. The cross-sections of the wires passing through the openings 3 do not have to completely fill the openings, whereby the casting material can penetrate inside the reinforcing blank also through the openings 3.

. Another 3-dimensional structure is one in which there are planes oriented in different directions, either different 2-dimensional planes connected to each other or different portions of the same 2-dimensional 35 plane. In this case, the structure can be obtained, for example, by winding the impregnated yarn at a desired angle around a suitable body, for example a cylinder (filament winding). The yarns 5 97037 can be made to join one of the intersections either by heating the finished blank or by heating the yarn, whereby the thermoplastic, which is still in a soft state, joins the different parts of the yarn 1 together in connection with the winding 5.

Figure 3 shows a reinforcement blank 5 placed in the mold cavity 4 and formed of the wires 1 described above. The figure further illustrates how the core 6 in the mold cavity 4 can be supported by the reinforcement blank 5 due to the rigid reinforcement blank having contact points with both the mold cavity 4 wall and the core. 6 surfaces. In this case, the rigid reinforcement blank locks the core in place in a way, and high casting pressures cannot move it. In this way, the reinforcing blank 5 can be helpful in producing, for example, long tubular bodies or other elongate bodies inside which the reinforcing blank remains. The reinforcing blank is suitable for supporting both fixed, retractable and dissolving cores.

It has been described above how a blank can be formed in one step, either by weaving, braiding or by filament winding. However, it is sometimes necessary to make pieces of more complex shape, in which case the reinforcement blank is formed from two or more reinforcement blanks made by a simpler method by mechanically or preheated the blanks 30 together, whereby they join together due to the thermoplastic. Such blanks can be shaped at their edges, e.g., to have overlapping structures, such as planes or wire portions, which mechanically connect the blanks 35 together. In addition to the mechanical connection, preheating can also be used. Such sub-blanks may be joined together either before the entire reinforcing blank is placed in the mold, or, if the shapes of the mold cavity 6 97037 so require, they may be joined together only in the mold.

Casting is performed by any of the commonly known casting methods. According to a preferred alternative, the casting is performed with the same thermoplastic as the thermoplastic impregnate matrix of the reinforcing blank. This ensures a particularly good adhesion of the matrix plastic to be fed during casting and the reinforcing blank matrix 10 without interfaces and at the same time a good adhesion of the reinforcing filaments to the matrix of the composite body.

If necessary, the reinforcement blank can be further preheated before casting with the matrix material. In this case, e.g. when performing injection molding with a thermoplastic (injection molding or RIM), it can be ensured that the matrix of the reinforcing blank is also in such a state that it binds well to the matrix material fed during casting.

20

Figure 4 also shows some of the relevant pieces to be cast by the method in cross-section. As can be seen from the figure, the reinforcing blank can be at any point on the body, as required, such as in the tubular bodies shown in Fig. 25, for example on the outer surface, in the middle or on the inner surface of the tube. In addition, the structure of the part may consist of the combinations shown in the previous figures so that there are several layers of reinforcement.

30

It is clear from the above that the reinforcement blank according to the invention can be placed in the casting cavity forming the final body so that the material content of the reinforcement blank and the orientation of the reinforcement 35 in the mold cavity are desired.

Il 5 7 97037 The fiber content of the yarn 1 used can vary within very wide limits, but typically the fiber content is 20 ... 60% by weight of the total volume.

The concentration of reinforcing blank material in the final mold blank can vary over a very wide range, but is typically in the range of 40-60% by weight of the volume of the final product.

10

The method according to the invention is particularly suitable for the injection molding of thermoplastics and the RIM technique with polyamide, and it can be used to produce bodies similar to the standard injection molding and RIM techniques.

The advantages of the method can be summarized as follows: 20 - higher fiber concentrations of long-fiber reinforced thermoplastics are obtained by injection molding, - the same fiber length is achieved as by winding or pultrusion, mechanic to those properties.

In practice, the method can also be automated, e.g. in injection molding, so that a robot or manipulator installs a reinforcing blank in the mold cavity at the stage when the mold is open.

97037 δ

The following describes the whole process:

Preparation of the blank: 5. 1. A staple fiber or "prepreg" of the desired cross-section is made of any thermoplastic and reinforcement. Compared to RTM and RIM technology, the range of materials is vastly larger.

2. The reinforcement blank is then made, e.g. by winding, so that the sections of wire are welded together at their intersections.

15 3. The blanks thus prepared can be stored and transported completely freely. The durability over RTM and RIM fiber blanks is superior.

20 Injection molding 1. Carry out any preheating of the reinforcement blank. This eliminates the mold shrinkage of the preform and molten mass in the process. In practice, the blank can be heated very close to the softening temperature of the molded plastic.

2. Place the reinforcement blank in the mold cavity.

30 3. Perform a completely normal injection molding process.

Based on the preliminary tests performed, no changes in the process are required, as the molten thermoplastic mass is well able to penetrate into the void space of the reinforcing blank 35.

Il 9 97037

The benefits achieved very simply can be described by the following points. For example, in the case of polypropylene, the tensile strengths of the materials are as follows 5 - pure PP tensile strength approx. 25 ... 30 MPa staple fiber reinforced PP 40 ... 70 MPa long fiber reinforced PP 100 ... 150 MPa continuous fiber reinforced PP 200 ... 600 MPa 10 If the fiber content of the final piece is reached in the range of 20 ... 30% by weight, so in such a body the tensile strength range of 200 ... 300 MPa can be easily reached. If the reinforcements can be mounted on the part in a completely controlled manner, then it is possible to increase the local tensile strength in the part in the direction of the fibers to the range of 400 ... 700 MPa without major problems.

If, in the example, polyamide 20 were taken as the matrix and carbon fiber as the reinforcement, the strengths could easily be multiplied by two.

Particularly good results can be obtained with liquid crystal polymers which have a very low melt viscosity and which can be used to make very large and thin-walled bodies.

All in all, this technique makes it possible to make by injection molding 30 pieces with strength properties which cannot be produced by any other known technique.

Claims (9)

1. A product made of a reinforcement and matrix plastic, comprising a reinforcement and thus molded matrix plastic, characterized in that the reinforcement consists of a continuous fiber reinforced thermoplastic impregnated constituting a multiple continuous reinforcement impregnated with a thermoplastic matrix. filaments (2) comprising yarns, the parts of which are joined together so as to form an at least 2-dimensional structure or reinforcing member (5) in which the parts of the yarn (1) in contact with each other are secured to each other through the yarn ( 1) thermoplastic matrix. Product according to claim 1, characterized in that the parts of the yarn (1) form a 3-dimensional structure. Product according to claim 2, characterized in that the 3-dimensional structure is formed by wrapping the yarn (1) around one piece. 4. A product according to any preceding claim, characterized in that openings (3) with molded plastics have been penetrated between the contact points of the different parts of the yarn (1) during the casting. 5. A product according to any preceding claim, characterized in that the thermoplastic matrix is the same as the matrix of the thermoplastic impregnator of the reinforcing element (5). 6. A method of manufacturing a reinforced product of a reinforcement and matrix plastic, in which the method of reinforcement is placed in a mold cavity (4), in which then matrix plastic is conducted to perform the molding, characterized in that the reinforcement is a continuous fiber. reinforced thermoplastic impregnated, constituting a plurality of continuous reinforcing filaments (2) impregnated with a thermoplastic matrix comprising yarns, the parts of which are fed together so as to form an at least 2-dimensional structure in which the parts of the yarn which are in contact with each other are present (1) ) Are secured together by the thermoplastic matrix of the yarn (1), after which the so-formed reinforcing blank (5) is placed in the mold hollow (4) and the casting is performed. 7. A method according to claim 6, characterized in that the reinforcing blank (5) to be placed in the shape of the hollow (4) is formed by fixing mechanically and / or by heating separate reinforcing blanks (5) with each other. 15 Method according to claim 6 or 7, characterized in that the reinforcing element (5) is preheated before casting. Method according to claim 6, 7 or 8, characterized in that in the mold hollow (4) is placed a core (6) which is supported against the mold by means of a rigid reinforcing blank (5).