JPH05169446A - Preparation of fiber reinforced preform - Google Patents

Abstract

PURPOSE:To decrease the amount of a resin used and to render the drying, curing, and post treatment of an adhesive unnecessary by curing the adhesive after a reinforcing material on a screen mold and the adhesive of a thermosetting resin composition, each being covered with an airtight sheet, are bound to the screen mold. CONSTITUTION:In the preparation of a fiber reinforced preform, a vacuum device 3 is actuated to evacuate a screen mold 1 in the first place. The pressure is controlled with a adjusting damper 4 watching a vacuum gage 5 to keep the pressure at an proper vacuum. A reinforcing material 10, in the form of chops 11 passed through a cutter 6, is supplied on the upper surface of the screen mold 1, and then a resin composition 14, a mixture of a resin 12 and a curing agent 13, is supplied from a spray gun 7 on the upper surface of the screen frame 1. After the reinforcing material 10 and the resin composition 14 are deposited on the upper surface of the screen mold 1, an airtight sheet is bound on the deposition by vacuum. The resin composition 14 is cured at room temperature and demolded to accomplish a fiber reinforced preform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fiber reinforced preform used for producing a fiber reinforced plastic molded article.

[0002]

2. Description of the Related Art Fiber reinforced plastics (hereinafter abbreviated as FRP), which is a composite of a reinforcing material and a resin such as unsaturated polyester resin, is widely used for housing materials, boats, industrial equipment, electric parts, automobile parts, etc. , Has become an essential material for modern life. Various methods are known as molding methods for producing FRP products. In molding methods such as matched metal die, cold press, resin injection, vacuum-assisted resin injection, and back method, the reinforcing material and resin are inserted into the male or female mold, and the molding is carried out by hardening.In this case, the reinforcing material is used. It is common to use a fiber reinforced preform in the form of a mold.

For molding a fiber preform, a screen mold having a large number of small holes formed according to a male mold or a female mold is used, and one side of the screen mold is kept in a depressurized state. At the same time, air is sucked from the small holes to supply the fiber to the surface of the screen type that is in contact with the atmosphere, or the adhesive is sprayed or sprayed while the fiber reinforcement is sucked onto the screen type to provide shape retention. , Then, it is removed from the screen mold and made into a preform. As the adhesive, a water-soluble emulsion solution or a hot melt type adhesive is used.

When an aqueous emulsion solution is used, for example, fibers are sprayed on a screen mold to be deposited, and then an aqueous emulsion type resin diluted with water is applied or sprinkled on the screen mold to form fiber gaps. It is filled with an aqueous emulsion solution, the screen mold is sucked and evacuated to bring the fibers into close contact with the screen mold, and heat-dried in this state to obtain a preform.

The amount of non-volatile matter attached to the adhesive after drying is F
From the viewpoints of mold compatibility during RP molding, finished appearance, strength characteristics of molded products, water resistance, etc., it is generally about 3 to 10% by weight relative to the reinforcing material. The water-soluble emulsion solution is used in almost the same amount as the glass fibers deposited on the screen because it is necessary to fill the gaps between the fibers by filling the space between the reinforcing materials with the adhesive and to make the fibers clogged. Then, a drying process is performed. In order to increase the thermal efficiency of this drying process, a hot air generator having a considerably high thermal efficiency is required, and there is a drawback that the equipment cost is high. In addition to the evaporation of water in the adhesive, there is a lot of heat loss for heating the air in the furnace itself and the screen, and the heat source cost is high.If a direct fire is used as the heat source to further improve thermal efficiency, it will be included in the aqueous emulsion. There were also safety problems such as the explosion and ignition of organic solvents.

On the other hand, as a method for solving the above problems,
A method using a hot-melt type adhesive has been proposed (JP-A-59-35917). This method is a method in which a molten hot melt adhesive is sprayed onto a reinforcing material such as glass fiber, melted and dispersed, and then cooled and molded. However, in this method, the amount of the hot-melt adhesive used with respect to the glass fiber deposited on the screen mold is limited to about 3 to 10% by weight for the same reason as above, so that the void of the deposited fiber is filled. Therefore, even if the screen mold is sucked and evacuated, the deposited glass fibers cannot be adhered to the screen mold, and the hot melt adhesive is cooled at the same time as it is sprayed and solidified in a bulky state. I will end up. In order to make a preform suitable for the shape of the screen, post-treatment such as heating again to bring the hot-melt adhesive into a molten state and pressing it from the outside to bring it into close contact with the screen mold was required.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and provides a method for producing a fiber-reinforced preform which is excellent in economic efficiency and which does not require a step of drying and curing an adhesive or a post-treatment step. Is provided.

[0008]

Means for Solving the Problems In view of the above-mentioned problems, the inventors of the present invention have made earnest studies, and as a result, used a small amount of a curable resin as an adhesive, deposited it on a screen together with a reinforcing material, and then made it airtight. The inventors have found that the above problems can be solved by covering the screen with a conductive sheet to bring it into close contact with the screen, and then curing the adhesive, and have reached the present invention. That is,
The present invention provides a method for producing a preform by spraying or spraying an adhesive while depositing or after depositing a reinforcing material on a preform molding screen mold,
While using a curable resin composition for the adhesive,
The present invention relates to a method for producing a fiber-reinforced preform, which comprises covering a reinforcing material and an adhesive on a screen mold with an airtight sheet and bringing them into close contact with the screen, and then curing the adhesive.

The reinforcing material used in the present invention is not particularly limited and, for example, glass fiber, carbon fiber, aramid fiber or the like is used. Also, there are no restrictions on the state of the fibers,
For example, it can be used in any state such as a mat shape such as a chopped strand mat or a continuous mat, a cloth shape such as a glass cloth or a roving cloth, a continuous fiber shape, or a roving shape such as a glass roving. The adhesive used in the present invention, a curable resin composition is used,
For example, a thermosetting resin composition such as unsaturated polyester resin or epoxy resin is used. The composition must be sprayed or sprinkled as an adhesive and have the proper viscosity and curability for further curing. The viscosity of the resin composition is usually adjusted to 10 poise or less. If the viscosity is too high, spraying becomes difficult. Further, in order to impart curability, a curing accelerator, a curing agent, etc. are added.

The resin can be cured by any of a room temperature curing type, a medium temperature curing type, and a high temperature curing type. However, as in the spray-up molding method, a room temperature curing type curing agent is added and used. The type is general. The curing time of the resin is set so that the resin and the reinforcing material are covered with the airtight sheet and brought into close contact with the screen mold, and then the curing is started. The amount of the resin used is the same as in the case of using the conventional hot melt type adhesive, from the viewpoint of the conformability to the mold during FRP molding, the finished appearance, the strength characteristics of the molded product, the water resistance, etc.
It is about 3 to 10% by weight with respect to the reinforcing material. In the present invention, even if the amount of the adhesive used for the reinforcing material is small, the reinforcing material and the adhesive are sucked and exhausted in a state of being covered with the airtight sheet on the screen mold, and the space between the reinforcing materials becomes clogged. The adhesive can be cured without being bulky and in close contact with the screen mold.

Examples of the airtight sheet used in the present invention include polyethylene film and vinyl chloride film. Further, even if the airtightness is not completely maintained, any material may be used as long as it functions to fill the gap between the reinforcing materials by suction and exhaust. Further, it may be a molded product having a shape of a screen instead of a sheet, as long as it gives airtightness.

FIG. 1 is an explanatory view showing an example of an apparatus according to the manufacturing method of the present invention. This apparatus includes a screen mold 1 having a small hole 2, a decompression device 3 for sucking and exhausting from one side of the screen mold 1, and a decompression adjusting damper 4 for appropriately maintaining the decompression condition of the decompression device 3. A decompression gauge 5 for measuring a decompression state, a cutter 6 that cuts the reinforcing material 10 to form a chop 11, and a composition 14 in which a curable resin composition 12 and a curing agent 13 are mixed are jetted onto the screen mold 1. It mainly consists of the spray gun 7 and. The screen die 1 has a predetermined shape to be formed, and the aperture ratio of the small holes 2 is usually about 50%, and punching metal or FRP is preferably used as the material.

In such a structure, first, the decompression device 3
Is operated to suck the screen mold 1. Screen type 1
The pressure reduction of 980 to 980 holds the reinforcing material and the adhesive supplied to the screen surface, and makes the reinforcing material and the adhesive on the screen adhere to the screen mold by the airtight sheet.
It is preferably about 3290 Pa. Since the amount of exhaust air sucked is proportional to the surface area of the mold, it is adjusted by the adjusting damper 4 so as to maintain an appropriate depressurized state. Next, the reinforcing material 10 is supplied to the upper surface of the screen die 1 in a reduced pressure state via the cutter 6. When glass roving or the like is used as the reinforcing material 10, it is cut into an appropriate length by the cutter 6 and supplied as the glass chop 11. The glass chop 11 is held on the upper surface of the mold because the inner surface of the screen mold 1 is in a vacuum suction state. The glass roving or the like may be cut to an appropriate length, or may be continuously supplied without being cut.

On the other hand, the resin 12 is mixed with the curing agent 13 and supplied as a resin composition 14 from the spray gun 7 onto the screen mold 1. The glass chop 11 and the resin composition 14 may be supplied at the same time.
The resin composition 14 may be supplied on the above. Resin composition 1
In order to supply 4 by spraying, the spray-up machine used in the spray-up method can be used as it is.
After volume of the reinforcing material 10 and the resin composition 14 on the screen, an airtight sheet is covered thereover and brought into close contact with the screen mold by the suction force of the screen. In this state, the resin composition 14 is cured at room temperature and demolded to obtain a glass fiber preform. It may be heated to shorten the curing time.

According to the present invention, the heat treatment step of the adhesive when using the water-soluble emulsion solution can be omitted, and the post-treatment step when using the hot melt type adhesive is unnecessary, which is energy saving and economical. Preforms can be manufactured in a practical manner. Moreover, since the curable resin used as an adhesive does not reduce the water resistance, it can be applied to FRP molded articles in all fields.

[0016]

EXAMPLES The present invention will be described in detail below with reference to examples. In the apparatus shown in FIG. 1, a glass fiber preform was molded using the equipment and materials shown below. 1. Equipment specifications (1) Screen type: width 1000 mm, length 1000 mm,
It has a height of 1000 mm and is made of punched metal.
A cubic mold having a porosity of 50% and a surface area of about 5 m ² was used. (2) Pressure reducing device (exhaust fan): Exhaust capacity, 200m ³
/ Min (3) Resin and glass fiber supply device: spray-up machine (manufactured by Togiken Co., Ltd.) 2. Materials used (1) Reinforcement material: glass roving (RS-240F-1
14AJ, manufactured by Nitto Boseki Co., Ltd. (2) Resin: Polyset 5595APT-S (unsaturated polyester manufactured by Hitachi Chemical Co., Ltd.) (3) Curing agent: Permec N (manufactured by NOF Corporation) (4) Airtight sheet : Polyethylene film (thickness 50
Micron, TNAMPOL FN-13)

3. Preform molding First, on the surface of the screen die 1, a fluorine-based release agent (Frecoat FRP: HYSOLA ERROSPACE & I
NDUSTRIAL PRODUCTS DIVISI
ON) was applied and a mold release treatment was performed. Next, the decompression device 3 is operated, the decompression adjusting damper 4 is adjusted to 2450 Pa, and the glass roving 10 is cut to 50 mm by the cutter 6, while the spraying machine adjusts the discharge capacity of the glass chop 11 to 3 kg / min. Then, about 2 kg was uniformly sprayed on the surface of the screen mold 1. After that, while spraying the glass chop 11 in the same manner, the resin composition 14 in which the curing agent 13 is mixed with the resin 12 is discharged with a resin discharge amount of about 0.3 kg.
The spray gun (spray-up machine) 7 was sprayed at the same time. At this time, the amount of glass chop sprayed was 10 kg, the amount of resin sprayed was 0.9 kg,
The mixing ratio of the curing agent to the resin was 1.0% by weight.

After spraying the glass chop 11 and the resin composition 14, the entire screen surface is covered with an airtight sheet to bring the glass chop and the resin composition into close contact with the screen mold.
In this state, the resin composition 14 was cured. Resin composition 1
No. 4 started curing about 5 minutes after being supplied. The operation of the exhaust fan of the decompression device 3 was stopped when the entire resin was cured. Then, let stand for 10 minutes at room temperature to cure and release the mold.
Glass fiber preform with the shape shown in (12.8k weight)
g, the unit of the number is mm).

[0019]

According to the manufacturing method of the present invention, a curable resin is used as an adhesive, and a reinforcing material and a resin composition are adhered to a screen mold with an airtight sheet and then cured, so that the resin is used. It is possible to obtain a fiber reinforced preform by reducing the amount of the resin used and without performing a dry curing step and an aftertreatment step of the adhesive, which is excellent in economic efficiency and can prevent deterioration of water resistance of the obtained FRP molded article. Therefore, it can be applied to FRP products in a wide range of fields.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of an apparatus used in a manufacturing method of the present invention.

FIG. 2 is a view showing a glass fiber preform obtained in Example 1.

[Explanation of symbols]

1 ... Screen type, 2 ... Small hole, 3 ... Pressure reducing device, 4 ... Adjusting damper, 5 ... Pressure gauge, 6 ... Cutter, 7 ... Spray gun, 10 ... Reinforcing material (glass roving), 11 ... Glass chop, 12 ... Resin composition, 13 ... Curing agent, 14
…Composition.

Claims (1)

[Claims] 1. A method for producing a preform by spraying or spraying an adhesive while depositing or after depositing a reinforcing material on a screen mold for preform molding, wherein a curable resin composition is applied to the adhesive. A method for producing a fiber-reinforced preform, which comprises using a reinforcing material and an adhesive on a screen mold with an airtight sheet to bring the adhesive into contact with the screen, and then curing the adhesive.