JPH03230937A - Molding method for fiber reinforced resin - Google Patents

Abstract

PURPOSE:To surely prevent infiltration of a bubble and generation of an unevenness which are based on peeling of a coating film by forming a protective layer made of curable material on the surface of the coating film in the side wherein the coating film is not brought into contact with the mold face of a forming mold in the coating film stuck to a sheet for molding and curing this protective layer. CONSTITUTION:A sheet 20 for molding is obtained by laminating a surface layer 24 of resin on the single face of a fiber reinforced resin layer 22. A coating film 30 is stuck to both faces of the sheet 20 for molding. The sheet 20 and the coating film 30 are placed on a forming mold 10. The end parts of the sheet 20 and the coating film 30 are sealed and fixed to the forming mold 10. Thereafter the curable material becoming a protective layer 40 is coated by brushing. Then these are vacuumized and sucked from a vacuum suction port 14 to shape the sheet 20 and the coating film 30. After the sheet 20 is shaped, the protective layer 4C is cured. A molded form 28 is free from infiltration of a bubble and an unevenness in both the surface and the rear and has the smooth and beautiful appearance.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for molding fiber-reinforced resin, and more specifically, to a method for molding a sheet molded product made of a thermosetting resin material reinforced with glass fibers, carbon fibers, etc. It relates to a method for manufacturing.

[Conventional technology]

Many methods are known for manufacturing fiber-reinforced resin molded articles, such as hand lay-up method, spray molding method, mold molding method, and vacuum molding method.

Figure 6 shows an outline of the vacuum forming method, in which a fiber-reinforced resin molding sheet is formed into a sheet by adding reinforcing materials such as glass fiber or carbon fiber to liquid thermosetting resin such as polyester resin. S is prepared in advance, and this molding sheet)
Place S on a female (or male) mold m,
After the forming sheet S is shaped along the mold surface by vacuum suction from the vacuum suction port (■) provided on the mold surface of the mold m, the forming sheet S is shaped by heat transfer from the mold surface of the mold, etc. By heating and curing S and removing it from the mold m, a sheet molded product with a desired shape can be obtained.

In the above method, a covering film C made of a flexible and stretchable thermoplastic resin is pasted on the surface of the molding sheet S that does not contact the mold surface of the mold m. This covering film C is used to prevent air bubbles from entering the resin material of the molding sheet 1-S during shaping by vacuum suction. In other words, since the resin material constituting the molding sheet S is liquid, if this resin material is exposed on the surface, air bubbles may be drawn into the resin material due to the pressure difference between the two sides of the molding sheet S due to vacuum suction. ,
This may cause unevenness on the surface. However, if the covering film C is attached to the surface of the molding sheet S where the resin material is exposed, the intrusion of air bubbles as described above can be prevented and the occurrence of irregularities can also be prevented. This covering film C is also effective for preventing the sheets from sticking to each other when stacking the molding sheets S, and for facilitating the handling of the molding sheets S. Moreover, the covering film C may be provided on both sides of the molding sheet S.

The vacuum forming method described above has a simple structure of the mold m, does not require much mold precision, and has a wide range of applications as a method for efficiently manufacturing sheet molded products with relatively high precision. It is expected.

In addition, instead of the vacuum forming method in which vacuum suction is performed from the vacuum suction port (■) of the mold m, by applying pressure to the surface of the molding sheet (S) on the side that does not contact the mold surface of the mold m, There is also a pressure molding method in which the sheet S is pressed against a mold surface to shape it, or a method in which the molding sheet s is shaped by both vacuum suction and pressure.

[Problem to be solved by the invention]

However, in the conventional molding method as described above, there was a problem in that the coating film C covering the surface of the molding sheet ts was locally melted in the heat curing step. When the covering film C melts locally and creates holes, the covering film C, which has been stretched and deformed in close contact with the surface of the molding sheet S, shrinks and tries to return to its original flat state. When the molding sheet S is peeled off from the resin material, the liquid resin material that makes up the molding sheet S is exposed on the surface, causing problems such as air bubbles and unevenness on the surface, making it dirty. The drawback was that it was not available.

Since the covering film C is made of a material that has heat resistance higher than the heating temperature in the heat curing process, it will not melt only by external heating, but the thermosetting resin material that makes up the molding sheet S generates heat by itself when curing, and the coating film S melts due to the temperature rise accompanying this curing heat generation. The temperature rise due to the heat generated by the curing of the resin material is not uniform throughout the molding sheet S, and the portion of the molding sheet 1-3 that is cured first and changes from a liquid state to a solid state is heated. Since convection is difficult to occur, heat is trapped and the temperature locally becomes high, exceeding the allowable temperature limit of the covering film S.

Covering film C that is shaped together with molding sheet) S
If it melts even locally and creates holes, air will enter the gap between the covering film C and the liquid resin material through the holes. In this case, the covering film C tries to return to its original flat state due to the elastic restoring force of the material itself, and peels off from the resin material. Since the covering film C is only adhered closely to the liquid resin material, if air enters through the holes in the covering film C, it will be easily peeled off.

Therefore, an object of the present invention is to solve the problem of peeling of the coating film caused by holes caused by local melting of the coating film in the method of forming a sheet for fiber reinforced resin molding as described above, and to solve the problem of peeling of the coating film due to holes caused by local melting of the coating film. To provide a method capable of producing a sheet molded product with a beautiful surface and good finish quality without any problems.

[Means to solve the problem]

A fiber-reinforced resin molding method according to the present invention that solves the above-mentioned problems comprises using a fiber-reinforced resin molding sheet with a covering film pasted on at least one side, and arranging the covering film on the side that does not contact the mold surface. In a method for molding fiber-reinforced resin in which the resin is shaped along the mold surface of a mold and cured by heating, a protective layer made of a curable material is formed on the surface of the coating film on the side that does not contact the mold surface. , by the time the coating film melts due to heat curing of the entire molding sheet,
The protective layer is cured.

The fiber-reinforced resin molding sheet used is the same as that used for normal sheet molding. As the resin material, any of various thermosetting resins can be used. Specifically, unsaturated polyester resins, epoxy resins, polyurethane resins, epoxy (meth)acrylate-l-resins, etc. can be mentioned. As the reinforcing material for the resin material, any ordinary reinforcing fiber can be used. Specifically, glass, carbon, metal, Gevlar (trade name, aramid resin), Tetton (trade name, polyvarnish,
Examples include swirl mats and nonwoven fabrics. These reinforcing materials are coated or impregnated with the liquid resin material and formed into a sheet shape. Fiber-reinforced resin molding sheets include those consisting of a single fiber-reinforced resin layer, those laminated with multiple fiber-reinforced resin layers, and multiple types of fiber-reinforced resins made of different resin materials or reinforcing materials. A combination of layers may be laminated, and a combination of a fiber-reinforced resin layer and a resin material layer without reinforcing material may be laminated.

In the manufacturing process of the molding sheet, the viscosity of the resin is increased by normal means, if necessary.

The covering film is made of various thermoplastic resin films similar to those used in ordinary molding methods, and has flexibility and stretchability so that it can be shaped at the same time as the molding sheet I. A material that will not be attacked by the resin material of the sheet is used. Specific examples include nylon, vinylon, polyvinyl alcohol, polyethylene, polypropylene, and the like. The thickness of the covering film may be the same as that used in ordinary molding methods, but is preferably about 5 to 500 μm, more desirably about 10 to 100 μm. The covering film is used by being attached to one or both sides of the molding sheet. Since the molding sheet is made of a liquid resin material, it can be attached by simply bringing the covering film into close contact with the surface. If the molding sheet consists of multiple fiber-reinforced resin layers or a single resin layer, the coating film is pasted on some of the fiber-reinforced resin layers or the single resin layer, and then laminated and integrated with the remaining layers. It is also possible to produce molding sheets 1-.

The curable material that forms the protective layer can protect the coating film by withstanding the high heat generated by heat curing when the molding sheet is heated and cured. Any material that can be layered may be used. Examples of such materials include thermosetting resins. As the thermosetting resin, the same resin material as the above-mentioned molding sheet can be used, and specific examples thereof include unsaturated polyester resin, urethane resin, thermosetting acrylic resin, and the like. Curable materials used as the protective layer include those that harden by heating, those that harden at room temperature by adding an appropriate hardening agent, those that contain an ultraviolet curing agent and harden by UV irradiation, and those that harden by redox polymerization. A curable material or the like can be used. It is preferable to use a material with probing properties as the curable material. Also, materials with high curing speed are preferred. A relatively thin protective layer is sufficient as long as it is thick enough to protect the above-mentioned coating film.

As a means of forming a protective layer on the surface of the coating film,
In addition to forming a protective layer by applying a liquid curable material to a covering film by brushing, spraying, or scattering, a protective layer can also be formed by applying a liquid curable material onto another support film in advance. A protective layer can also be formed on the surface of the covering film by subsequently pressing this support film onto the covering film. In this case, if the protective layer coated on the support film is preliminarily thickened, it will be easier to handle and the adhesiveness to the covering film will be improved.

The protective layer may be formed on the covering film before the covering film is attached to the molding sheet, or before the molding sheet and the covering film are attached to the mold. As long as the protective layer is directly applied or pressure-bonded to the covering film, it may be formed after the forming sheet and the covering film are shaped. The protective layer may be formed over the entire surface of the covering film, or may be formed only at locations where melting of the covering film is likely to occur.

A mold having an arbitrary shape and structure similar to that used in ordinary vacuum forming or pressure forming is used. The mold may be either a female mold or a male mold. As the mold, a mold made of steel, aluminum, or the like is usually used, but a resin mold or the like may also be used.

The fiber-reinforced resin is molded using a molding sheet, a covering film, a mold, etc. as described above. The basic molding process is performed in the same way as a normal molding method. The molding sheet may be thickened in advance. As the thickening means, usual thickening means such as adding a thickening agent to the resin material, light irradiation, heating, etc. can be employed.

With the covering film disposed on the side of the mold that does not contact the mold surface, the fiber-reinforced resin molding sheet is shaped along the mold surface of the mold. When a protective layer is previously formed on the surface of the covering film, the protective layer is also shaped at the same time as the shaping sheet and the covering film are shaped.

As means for shaping the forming sheet so as to follow the mold surface of the forming mold, there are two methods: a vacuum forming method in which the forming sheet is shaped by vacuum suction from a vacuum suction port provided in the forming mold; Ordinary molding methods can be used freely, such as the pressure molding method in which fluid pressure such as air is applied to the opposite side to press the molded sheet against the mold surface, or the method in which vacuum suction and pressure are applied simultaneously. Applicable.

2. As a means for heating and curing the molding sheet, in addition to using only a method in which a mold is provided so that it can be heated freely and the molding sheet is heated by heat transfer from the mold surface,
Methods of heating the entire atmosphere, methods of irradiating infrared rays, etc.
Various conventional curing means can also be used in combination.

In this invention, a protective layer is formed on the surface of the coating film and this protective layer is cured before the molding sheet is heated and cured. The protective layer is preferably cured after the shaping sheet and coating film are shaped. This is because if the protective layer is hardened before shaping the shaping sheet, it will be difficult to shape the shaping sheet. However, the curing of the protective layer may be started before or during the shaping of the molding sheet, and the curing of the protective layer may be completed after the molding sheet is shaped. Specifically, for example, a liquid curable material containing a curing agent is applied to the surface of a flat coating film before shaping to form a protective layer, and the curing of the protective layer proceeds. Until then, the forming process of the forming sheet and the covering film may be performed. In addition, a protective layer containing an ultraviolet curing agent is formed on the coating film, and ultraviolet rays are irradiated before or during the shaping process of the forming sheet and coating film, so that the ultraviolet curing within the protective layer progresses. It is only necessary that the shaping of the shaping sheet and the covering film be completed by the time of completion. Next, the heating and curing process of the molding sheet proceeds, and the protective layer is sufficiently cured at a stage before the covering film melts due to the temperature rise accompanying curing heat generation. In other words, the protective layer only needs to be hardened to the extent that it can prevent the coating film from peeling off or lifting when the coating film melts.
The protective layer does not necessarily have to be completely cured. The setting of the curing time of the protective layer as described above can be adjusted by selecting the curable material and curing agent constituting the protective layer, the curing method and the timing of its execution.

The protective layer may be cured over the entire surface of the coating film, but it may also be cured only on the portions of the surface of the coating film where melting may occur. . This is an effective method when employing means that can partially cure the protective layer, such as when the protective layer is cured by ultraviolet irradiation.

[For production]

On the surface of the coating film on the side that does not contact the mold surface of the mold,
By forming a protective layer and curing this protective layer, even if the coating film melts locally due to the temperature rise associated with the curing heat generated when the entire molding sheet is heated and cured, it will not cause holes. , the surface of the coating film is already covered with a hardened protective layer, so that air bubbles can no longer penetrate. Even if the covering film shrinks and peels off, or tries to return to its original state, it will not peel off because it is held down by the protective layer. Therefore, the resin material on the surface of the molding sheet does not peel off from the coating film, and the surface does not become uneven. As a result, the molded product obtained has a smooth, beautiful, and good finish even on the side to which the coating film is attached that does not contact the mold surface.

5 Although it is possible to form the protective layer directly on the surface of the molding sheet instead of pasting the covering film on the surface of the molding sheet, the protective layer made of a curable material may be integrally bonded to the resin material of the molding sheet. As a result, it becomes impossible to peel only the protective layer from the surface of the molded product. Further, the protective layer before curing cannot prevent the molding sheets from adhering to each other or protect the resin material of the molding sheets, unlike a covering film. Therefore, it is necessary to apply a covering film to the surface of the molding sheet and to form a protective layer on the surface of the covering film.

If the curable material for the protective layer is a thermosetting resin, this thermosetting resin is a material used in ordinary resin molding, so it is easy to obtain and handle, and it is easy to control the curing of the protective layer. is also easy.

When the curable material that forms the protective layer is a thixotropic material, this thixotropic material will flow easily during coating operations such as brush coating, resulting in good workability, and the protective layer will not flow out after being applied. Since it is difficult to move or move, it is possible to maintain a sufficient thickness to protect the covering film.

If a protective layer is formed on the surface of the coating film before shaping the forming sheet, the protective layer can be formed on the flat coating film, so it is easy to form the protective layer by coating or pressure bonding. A protective layer can be formed in close contact with a coating film [Example] Next, examples of the present invention will be described with reference to the drawings.

FIG. 1 shows the overall structure of the molding device, and the mold 10, which is concave in the center and constitutes a so-called female mold, has a structure similar to that used in normal molding methods. . A mold surface 12 of the mold 10 is provided with a vacuum suction port 14, and the vacuum suction port 14 is connected to a vacuum source (not shown). The inside of the mold 10 is equipped with a heating mechanism such as a heater so that the mold surface 12 can be heated.

7. The fiber-reinforced resin molding sheet 20 is made of a resin material such as unsaturated polyester resin and reinforcing fibers such as glass fiber.
It is the same as a normal molding sheet. Covering film 3
0 is the same as a normal covering film such as vinylon film. A protective layer 40 is provided on the surface of the covering film 30.
is formed.

FIG. 2 shows a method of forming the protective layer 40.

With the laminate in which the covering film 30 is attached to the forming sheet 20 in a flat state, a predetermined curable material is applied to the surface of the covering film 30 using a brush 50 or the like to form the protective layer 40. do. The protective layer 40 is the molding sheet 20
And of the covering film 30, the mold surface 12 of the mold 10
It is sufficient to form it only near the location corresponding to. In this embodiment, a thermosetting resin with a curing agent added is used as the curable material, and the protective layer 40 coated on the surface of the covering film 30 gradually hardens over time. do.

A molding method using the molding apparatus and molding sheet 208 as described above will be explained with reference to FIGS. 1 and 3.

First, as shown in FIG. 1, the molding sheet 20 on which the covering film 30 on which the protective layer 40 is formed is placed on the mold 10, and vacuum suction is applied from the vacuum suction port 14 of the mold 10. Then, the molding sheet 20 and the covering film 3
0 is drawn into the mold and shaped along the mold surface 12. When the molding sheet 20 contacts the mold surface 12, the mold surface 12
Heat curing begins due to heat transfer from the

The protective layer 40 formed on the surface of the coating film 30 is cured by its own curing action, and the heat generated by heating is also transferred to promote curing. In addition, at this stage, mold surface 1
Heat curing of the entire forming sheet 20 due to heat transfer from the second side has not progressed much, and the heat generated due to heat curing has not reached a high enough temperature to melt the covering film 30.

The protective layer 40 has been cured to sufficient hardness before the heat curing of the molding sheet 20 progresses and the temperature rises to a point where the covering film 30 locally melts. hardens.

At this stage, the coating film 3 is heated due to heat curing.
0 may melt locally, but the covering film 30
Since the surface of the protective layer 40 is already hardened, there is no problem.

When the resin material is sufficiently heated and cured and the molding sheet 20 is molded into the desired shape, the molding sheet 20, the covering film 30, and the protection N40 are taken out from the mold 10.

When the molding sheet 20 is subjected to predetermined trimming and contour processing, a molded product 28 is obtained as shown in FIG. 3. The covering film 30 and the protective layer 40 that have been attached to the surface of the molding sheet 20 may be peeled off from the surface of the molded product 28. Since the protection N40 has been cured, there is a possibility that it will crack or be damaged when it is removed together with the covering film 30, but at this stage the role of the protection layer 40 has been completed, so even if the protection layer 40 is broken, there will be no damage. no problem. In this way, the manufacturing process of the fiber-reinforced resin molded product is completed.

0 FIG. 4 shows another embodiment of means for forming a protective layer 40 on a covering film 30 applied to a forming sheet 20. In this embodiment, instead of applying the curable material directly to the covering film 30, the supporting film 4
A protective layer 40 is formed by coating the surface of 2 with a curable material. This support film 42 is stacked on the surface of the covering film 30 with the protective layer 40 inside, and is integrally bonded to the covering film 30 by the adhesiveness of the protective layer 40.

Thereafter, the molding sheet 20 is mounted on the mold 10 while the support film 42 remains stacked, and the shaping process and heat curing process described above can be carried out. Molded product 2
8 is obtained, a protective layer 40 is added together with the covering film 30.
Then, the support film 42 may be peeled off. Note that, before the shaping step, only the support film 42 may be peeled off from the covering film 30.

As the support film 42 used in the above method, the protective layer 4
A film made of any material can be used as long as it can support a curable material that provides a Preferably, the film 42 is made of a shapeable material. Further, when the protective layer 40 is cured by irradiating the protective layer 40 with ultraviolet rays from above the support film 42, a material that can transmit ultraviolet rays is used as the support film 42.

As a specific material for the support film 42, for example, the same material as the above-mentioned covering film 30 can be used.For the forming sheet 20 and the covering film 30 used in the above-described forming method, as shown in FIG. ) can be used. Figure 5 (shown in al.
The entire molding sheet 20 is formed of a fiber-reinforced resin layer, and a covering film 30 is attached to one side thereof. Therefore, a protective layer 40 is formed on the surface of this covering film 30. The sheet shown in FIG. 5(b) has a fiber-reinforced resin layer 22 on one side as a molding sheet 20.
A surface resin layer 24 is laminated, and a coating film 30 is attached to both sides of the molding sheet 20. In this case, the protective layer 40 is formed on the troublesome surface of the covering film 30 that does not come into contact with the mold surface 12 during shaping.

The surface resin N24 is usually placed on the side of the molded product 28 that will be used, and is used to cover irregularities caused by the fibers of the reinforcing material and to improve the color, properties, and other appearance of the surface. Specifically, the material is the same as the fiber reinforced resin layer 22 but does not contain any reinforcing material, the resin material has various usual coloring agents added to it, the resin material is laminated with Surf Ace mat, or it is made of organic fibers. Examples include those made by laminating nonwoven fabrics.

Next, specific examples in which the molding method of the present invention is actually used will be described.

Example 1 Fiber-reinforced resin molding sheet 2 having the structure shown in FIG. 5(b)
0 and coating film 30 were used. That is, a molding sheet 20 in which a fiber-reinforced resin layer 22 is laminated with a surface resin layer 24 on one side is inscribed, and a covering film 30 is attached to both sides 3 of the molding sheet 20.

The structure of each layer was as follows. (Amounts are shown in parts by weight) (a) Tit film 30 Vinylon film (b) Fiber reinforced resin layer 25 (Thickness approx. 311) Unsaturated polyester resin (B Hon Shokubai Kagaku Kogyo C!lI!II!!, Eborasoku G
-103)... Bow 00 parts tert-butyl peroxy 2-ethylhexanoate (thermal curing agent)... 1 part MgO... 2 parts Glass cloak 1 layer (glass content approx. 33%) (C1 surface resin Layer 24 (thickness approx. 0.7n) Unsaturated polyester resin (manufactured by Nippon Shokubai Chemical Co., Ltd., Eporasoku N-325)...100 parts Silicic anhydride fine powder...2 parts Styrene
... 15 parts tert-butyl peroxy 2
Ethylhexanoate (thermal curing agent)... 1.1 parts 4 MgO... 2.2 parts (d) Protective layer 40 (thickness approximately 2 mm) Unsaturated polyester resin (manufactured by Nippon Shokubai Chemical Co., Ltd., Eporank P- 5512)...100 parts Silicic anhydride fine powder (thixotropy imparting agent)...2 parts Methyl ethyl ketone peroxide (curing agent)...3 parts The curable material that will become the protective layer 40 is prepared using unsaturated polyester. Fine powder of silicic anhydride, which is a thixotropy imparting agent, was dispersed in the resin using a high-speed stirrer (homomixer), and methyl ethyl ketone peroxide, which was a curing agent, was added immediately before coating. Therefore, the curing of the curable material begins from the time the curing agent is added.

Molding was carried out using the apparatus and steps shown in FIGS. 1 to 3.

The mold 10 has vacuum suction ports 14 at the four corners of the bottom of the mold surface 12, forming a female mold with an opening of 200 x 500 m+m and a depth of 50 m. The mold temperature was 950°C. The molding sheet 20 has a surface resin layer 24
It was arranged so that the side was on the mold surface 12 side.

After placing the molding sheet 20 and the covering film 30 on the molding die 10 and sealing and fixing the ends of the molding die 10, the molding sheet 20, and the covering film 30, the curable material that will become the protective layer 40 is applied with a brush. I painted it. Next, a vacuum was applied from the vacuum suction port 14 to shape the forming sheet 20 and the covering film 30. The protective layer 40 was cured in about 35 seconds after the shaping sheet 20 was shaped. After shaping, the mold was removed 20 minutes later, and the covering film 30 and protective layer 40 were peeled off. The molded product 28 obtained had no bubbles or unevenness on both the front and back surfaces, and had a smooth and beautiful appearance. A molded article 28 having excellent strength was manufactured.

Comparative Example 1 Molding was performed in the same process as in Example 1 except that the protective layer 40 was not formed. As a result, the molding was completed in about 4 minutes after shaping the molding sheet 20. Since the covering film 30 in the portions of the mold surface 12 of the mold 10 corresponding to the corners of the bottom surface melted, the entire covering film 30 was lifted up, and the surface of the obtained molded product 28 had the parts where the covering film 30 was peeled off. The finish was extremely fluffy and unsatisfactory.

Example 2 Molding was carried out in the same steps as in Example 1 except that the method for forming the protective N40 was changed.

The formation of the protective layer 40 is performed immediately after the molding sheet 20 and the covering film 30 are mounted on the mold 10 and shaped.
The curable material was applied with a brush only to the surface of the coating film 30 in the portions of the mold surface 12 of the mold 10 corresponding to the corners of the bottom surface.

As a result, similar to Example 1, an excellent finish was obtained. Comparing with the results of Comparative Example 1, it can be seen that the protective layer N40 only needs to be formed at locations where the covering film 30 is likely to melt.

Example 3 7 In Example 1, molding was performed in the same steps as in Example 1, except that the following material was used as the curable material for the protective layer 40 and was cured by ultraviolet irradiation.

The composition of the protective layer 40 was as follows.

(dl Protective layer 40 (thickness approx. 21 layers) Unsaturated polyester resin (manufactured by Nippon Shokubai Chemical Co., Ltd., Eborasoku G-103)...100 parts Silicic anhydride fine powder (probeability imparting agent)...2 parts benzoin Methyl ether (ultraviolet curing agent)... 3 parts The above-mentioned curable material is applied with a brush to the surface of the coating film 30 to form the protective layer 40, and after shaping the molding sheet 20 and the coating film 30, The protection Ft40 was irradiated with a UV lamp of watts/cm from a distance of about 10 cm.The protection N40 was cured in about 20 seconds after the UV irradiation.

As a result, the molded products 28 obtained in Examples 1 and 8 The finish was also excellent.

Example 4 In Example 3, molding was performed in the same steps as in Example 3, except that the method for forming the protection 1i40 was changed.

The protective layer 40 was formed using the method described in FIG. 4. First, the same curable material as in Example 3 was applied to the surface of the support film 42 made of vinylon film (thickness 25 I!m) to a thickness of about 1 fi, and then preliminarily thickened at 40° C. for one day. Support film 42 with pre-thickening protective layer 40
was created. Next, with respect to the molding sheet 20 to which the coating film 30 was attached, protective N40 was attached to the surface of the coating film 30 on the opposite side of the surface resin layer 24 together with the support film 42.

In this way, the forming sheet 20, the covering film 30
, and the protective layer 40 with the support film 42 attached to the mold 10, the shaping and heat curing steps were performed in the same manner as in Example 3 above. In addition, the protective layer 40 was cured by ultraviolet rays by irradiating it with ultraviolet rays from above the support film 42 immediately after the 9-shaping. Therefore, the support film 4
As No. 2, a transparent film through which ultraviolet rays are transmitted was used.

The protective layer 40 was cured in about 20 seconds after UV irradiation.

As a result, the obtained molded article 28 had an excellent finish similar to Examples 1 and 3.

Example 5 - Molding was carried out in the same steps as in Example 2, except that the following material was used as the curable material for the protective layer 40.

+d) Protective layer 40 (thickness approx. 2m) Polypropylene glycol (number average molecular weight 600)... 2M glycerin
... 1 mol MDI (methylene diphenyl isocyanate)... 3.5 mol dibutyltin laurate... 0.05% by weight based on the total amount 0 The protective layer 40 is cured in about 20 seconds after being applied to the coating film 30 did.

As a result, the molded product 28 obtained had an excellent finish similar to Examples 1 and 2.

〔Effect of the invention〕

According to the above-described method for molding fiber reinforced resin according to the present invention, in a so-called sheet molding method such as vacuum forming or pressure molding, the mold of the mold is By forming a protective layer made of a curable material on the surface of the coating film that does not come into contact with the surface, and curing this protective layer, it is possible to reliably prevent air bubbles from entering or unevenness due to peeling of the coating film. It can be prevented. As a result, the molded product obtained has a smooth, beautiful, and good finish on both the front and back surfaces. Since there are no air bubbles in the molded product, it has excellent quality performance such as mechanical strength. Moreover, this molding method only requires the addition of a simple step of forming a protective layer on the surface of the coating film and curing it, and does not require complicated equipment or processes, and is not required for conventional general molding methods. It is possible to manufacture molded products simply and efficiently in the same way.

In particular, if a thermosetting resin is used as the curable material for the protective layer, the workability of the curing process etc. will be good and it will also be economical.

If a curable material is used as the curable material for the protective layer, it is possible to form a protective layer that has good coating workability such as brush coating and has excellent protective performance for the coating film.

If the protective layer is formed before the shaping sheet is shaped, the protective layer can be easily formed by coating or pressure bonding, resulting in a method with good workability.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of the present invention during molding, Fig. 2 is a sectional view showing the process of forming a protective layer, Fig. 3 is a sectional view of a molded product, and Fig. 4 is a sectional view of the protective layer. FIGS. 5A and 5B are cross-sectional views showing another example of the formation process of
10 is a cross-sectional view showing the structure of a molding sheet, and FIG. 6 is a cross-sectional view of a conventional example.
...Molding mold 12...Mold surface 14...Vacuum suction port 2
0... Molding sheet 28... Molded product 30...
Covering film 40...protective layer

Claims (1)

[Scope of Claims] 1. A fiber-reinforced resin molding sheet with a covering film pasted on at least one side is shaped so as to follow the mold surface of the mold, with the covering film placed on the side that does not contact the mold surface. In a method for molding fiber-reinforced resin that is heated and cured, a protective layer made of a curable material is formed on the surface of the coating film on the side that does not contact the mold surface, and the coating film is melted by heating and curing the entire molding sheet. A method for molding a fiber-reinforced resin, comprising curing the protective layer. 2. The method for molding a fiber-reinforced resin according to claim 1, wherein the curable material forming the protective layer comprises a thermosetting resin. 3. The method for molding a fiber-reinforced resin according to claim 1 or 2, wherein the curable material forming the protective layer is made of a thixotropic material. 4. The method for molding a fiber-reinforced resin according to any one of claims 1 to 3, wherein the protective layer is formed on the surface of the coating film before shaping the molding sheet.