JPH03182307A - Preform of fiber reinforced composite material - Google Patents

Abstract

PURPOSE:To permit the quick and efficient heating of the whole of a preform as well as the efficient and smooth secondary molding by a method wherein a plurality of holes is formed in the preform of block type composite material consisting of a synthetic resin and reinforcing fibers dispersed into the resin uniformly. CONSTITUTION:Thermoplastic resin or thermosetting resin is selected properly and is used as a synthetic resin while glass fiber, carbon fiber or the like is employed as reinforcing fiber. The synthetic resin and the reinforcing fibers are mixed uniformly under dry system together with other adding agents, for example, which are blended in accordance with necessity, while applying a normal molding method and the mixture is filled into a molding form having molding spaces 2. When obtained molded form 1 is inserted into a hot air furnace and the like and hot air is made to flow, the molded form 1 is heated from the outer surface side thereof while the molded form is heated simultaneously from the inside thereof by the hot air, which flows through respective holes 2, whereby a temperature gradient may be eliminated and the temperature of the whole of the preform may be risen uniformly and quickly.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a block preform made of fiber-reinforced composite material, and in particular to devising the shape of a block (including block and bulk) preform. This allows the whole to be heated evenly and quickly.

[Prior Art] Composite materials, in which reinforcing fibers are uniformly dispersed in synthetic resin, have excellent physical properties (especially tensile strength and impact strength), so they are used as FRP materials in various panel materials, It is widely used for exterior panel materials, body materials, container materials, etc. These composite materials are preformed into sheets or blocks and commercialized. There are also those using thermoplastic resin and those using thermosetting resin, and the latter is often commercialized in a pre-cured state.

Conventionally, sheet-like preforms have been widely used because they are easy to heat uniformly and have excellent secondary processability, but on the other hand, sheet-like preforms have the following drawbacks.

■-Production costs are high because the synthetic resin material must be melted first and then extruded onto a glass fiber mat, etc. ■The synthetic resin is kneaded with short fibers in a molten state and then the sheet is formed. It is also possible to extrude the molded product into a shape, but this method reduces the reinforcing effect because the reinforcing fibers break during the kneading process. (Accordingly, they must be laminated on a mold and press-formed, which increases molding costs. Therefore, recently, demand for preformed blocks has gradually increased.

[Problems to be Solved by the Invention] However, in the case of a material that is preformed into a lump (hereinafter referred to as "bulk material"), it is difficult to uniformly heat the preform to the inside prior to secondary forming. That is, heating methods for the preform include heating with an infrared heater, electric heater, hot air heating, etc., but in any case, heating is done from the outside, so the preform is heated from the outside to the center. When the center reaches the specified processing temperature, the outer surface becomes overheated, and in the case of bulk materials made of thermoplastic resin, the outer surface becomes too soft and fluid, and the thermosetting resin In block materials using resin, secondary hardening progresses on the outer surface side, and in either case, secondary workability is significantly impaired. To avoid such problems,
The rate of temperature increase due to heating must be made as slow as possible to minimize the aforementioned temperature gradient, and it takes a long time to raise the temperature to the secondary processing temperature. As a result, this temperature raising process becomes the rate-determining step, and not only does the productivity of secondary processed products drop significantly, but in the case of bulk materials using thermosetting resins, secondary hardening progresses during this time, resulting in poor workability. do.

The present invention was made with attention to such problems, and its purpose is to uniformly and quickly raise the temperature without creating a temperature gradient during the heating process performed prior to secondary molding. The purpose of this invention is to provide a block preform that can be used as a preform.

[Means for Solving the Problems] The structure of the preform according to the present invention that can solve the above problems is that it is made of a composite material in which reinforcing fibers are uniformly dispersed in a synthetic resin, and the composite material is The main feature is that the preform is preformed into a block, and a plurality of holes are formed in the preform.

[Operations and Examples] In the preformed body of the present invention, as shown in FIG. 1 (partially cutaway diagram), for example, a plurality of holes 2 are formed in a cylindrical preformed body 1 in the figure.

Therefore, when heating this preformed body 1, the molded body 1 is charged into a hot air oven or the like and hot air is flowed as shown by the arrow (A), and the molded body 1 is heated from the outside surface side.
The hot air flowing through the holes 2 heats the inside at the same time, eliminating the temperature gradient that occurs when conventional preforms without holes 2 are heated externally, and heating the entire body evenly. The temperature can be raised evenly and quickly. In this case, in order to prevent oxidative deterioration of the synthetic resin and reinforcing fibers constituting the composite material, it is desirable to use a non-oxidizing gas such as an inert gas or nitrogen gas.

Although FIG. 1 shows an example in which a large number of circular holes 2 are formed in the longitudinal direction of the cylindrical molded body 1, there are no restrictions on the shape or dimensions of the molded body 1 or the holes 2, and the shapes may be polygonal, elliptical, etc. Exactly the same effect can be obtained even if a large number of polygonal, shaped, or elliptical holes are formed in the molded body 1 having a columnar shape or the like. In this case, in order to uniformly raise the temperature of the molded body 1 as a whole, approximately the same
Although it is preferable to form holes 2 of different diameters at approximately equal intervals in the molded body 1, it is of course possible to form holes of different diameters at intervals corresponding to the hole diameters. The size of the hole 2 may be appropriately determined by taking into consideration the size of the molded body 1 and the type of heating means to be employed. As a heating means for this molded body, in addition to the above-mentioned hot air heating, for example, It is also possible to use a heating device as shown in FIG. 2 (schematic vertical cross-sectional view of 8I) and FIG. 3 (corresponding to the cross-sectional view taken along the line III--III of FIG. N2). That is, FIG. 2.3 illustrates a cartridge-shaped heating device having an internal space according to the size and shape of the preform 1, and includes a heating member 4 equipped with rod-shaped heaters 4a, 4a, . , a lower surface member 5 and an upper surface member 6 provided with through holes 5a, 5a, . . . 6a, 6a, . . . corresponding to the rod-shaped heaters 4a, 4a, . Each member is provided with a heating means (not shown), and is configured to be able to move up and down independently. And rod-shaped heaters 4a, 4a,...
- are holes 2.2. formed in the preform 1 to be heated.
The same number of pieces of the same size are provided at the corresponding positions. For heating, the upper surface member 6 is moved upward in the drawing, the preform 1 is inserted into the open space, the upper surface member 6 is lowered, and the preform 1 is placed in the open space.
The rod-shaped heater 4a is wrapped around the rod-shaped heater 4a.

4a, . . . , the lower surface member 5, the upper surface member 6, and the cylinder member 7 may be used to heat the cylinder member 7.
Then, the upper surface member 6 is evacuated upward, and the rod-shaped heaters 4a, 4a, . . . It is only necessary to move it toward the device. As the heating means, any means such as electric heating, induction heating, dielectric heating, etc. can be employed, and it is also possible to use a band heater or the like as a heating means from the outside surface side. Moreover, in the example of FIG. 2.3, the rod-shaped heaters 4a, 4a, . Although an example has been shown in which the preform 1 is heated by inserting it from one direction, if the preform 1 is long, it is also possible to adopt a configuration in which a rod-shaped heater is inserted from the top or bottom to heat it.

If such a device is used, it is possible to simultaneously heat the preform 1 from the outside and the inside to raise the temperature, which eliminates the temperature gradient that was pointed out in the conventional example (the time required to raise the temperature). The time can be significantly shortened. Immediately after the temperature is raised to a predetermined temperature, the secondary forming apparatus is transferred and secondary forming such as press forming is performed.

In the present invention, as described above, the block-shaped molded body 1 has a plurality of holes 2.2. The molded body 1 is characterized in that it is configured so that it can be heated not only from the outside but also from the inside, and the synthetic resin and reinforcing fibers that are the materials of the molded body are heated. There are no restrictions on the type of synthetic resin, and thermoplastic resins and thermosetting resins can be selected and used as appropriate depending on the purpose and required characteristics.
As for the types of reinforcing fibers, in addition to the most common glass fibers and carbon fibers, various metal fibers, whiskers, etc. can be used. In addition, fillers, antioxidants, colorants, stabilizers, plasticizers, antistatic agents, flame retardants, etc. can be added to the composite material containing these synthetic resins and reinforcing fibers, if necessary.

There are no restrictions on the method of forming the preform of the present invention using the composite material as described above, and conventional molding methods known in the art may be applied as is or with appropriate modifications. The following methods are exemplified as typical methods.

■Synthetic resin powder and short reinforcing fibers are uniformly mixed in vapor phase (dry mixing) with other additives that may be added as necessary, and this is mixed into a molding space shaped like the one shown in Figure 1, for example. In this case, it is of course effective to use a suitable binder to improve moldability and shape retention. It is also possible to improve the shape retention by slightly heating the powder during the compaction process to partially melt the synthetic resin powder and fuse them together.

■A method of wet-mixing synthetic resin powder and short reinforcing fibers with other additives blended as necessary using water as a mixing medium, forming the mixture into the shape shown above and drying it, or Using a plunger type extrusion molding device,
A method in which a rod-shaped perforated preform is extruded, cut into appropriate lengths, and then dried. In this case as well, a suitable binder can be added as needed to improve moldability and shape retention.

■ A method in which a dry mixture as shown in (■) above is charged into a plunger type extrusion molding device, etc., and moderately heated at a discharge die, etc., to extrude the synthetic resin powder in a partially molten state into a perforated rod shape.

■Using a device like the one shown in Figure 2.3 as a preforming device, a mixture of synthetic resin powder and reinforcing fibers is filled into the molding space through which a rod-shaped heater is inserted, and then compressed to partially melt the resin. A method of heating them to such an extent that they are fused and fixed together.

It is preferable to employ the methods shown in (1) to (2) above, because the reinforcing short fibers are less likely to break during the preforming process and the composite effect of the 1a fibers for the supplement 31 is more effectively exhibited.

[Effects of the Invention] The present invention is configured as described above, and by forming a plurality of holes in the bulk preform, the entire body can be heated quickly and efficiently, and the secondary forming can be performed efficiently. It was decided that the project could be carried out smoothly. Moreover, since no temperature gradient is generated during the heating process, there is no risk of the preform being locally overheated, and there is no risk of deterioration in shape retention due to partial melting, which tends to occur when thermoplastic resins are used. does not cause problems such as the progress of partial secondary curing reactions that tend to occur when using thermosetting resins, and produces two-dimensional products with uniform and stable quality.
The next molded body can be manufactured with high productivity.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway diagram illustrating a preformed body according to the present invention, FIG. 2 is a schematic vertical cross-sectional view illustrating a heating device for a molded body according to the present invention, and FIG. !
It is a diagram corresponding to a line cross section. 1... Preformed body 4a... Rod-shaped heater 5... Lower surface member 5a, 6a... Through hole 2... Hole 4... Heating member 6... Upper surface member 7... Cylindrical member

Claims (1)

[Claims] A fiber comprising a composite material in which reinforcing fibers are uniformly dispersed in a synthetic resin, the composite material being preformed into a block, and a plurality of holes being formed in the preform. Reinforced composite preform.