JPH05301295A - Manufacture of fiber-reinforced resin molded product - Google Patents

Abstract

PURPOSE:To obtain a molded product suitable for a bathtub by eliminating harmful bubbles within laminates, by a method wherein in a spray-up molding method for which a reinforcement fiber and thermosetting resin are used, the first laminates for which a comparatively short fiber is used is formed and the second laminates for which a comparatively long fiber is used are formed before curing. CONSTITUTION:Thermosetting resin and a reinforcement fiber are sprayed on a molding tool to which a gel coat 13 is applied, the first laminates 11 having a thickness of 0.6-1.25mm is formed and the second laminates 12 are formed before curing. As to lengths of the reinforcement fibers, 2.0-10.0mm and 25-50mm are preferable respectively for the first laminates 11 and second laminates 12. In this manner, bubbles in the first laminates 11 become small and few. When the fiber length is 6-10mm, though the diameter of the bubbles become an extent of 1.0-1.5mm, when a roller is rolling-contacted to the surface of both of the laminates 11, 12 by fixed pressure before solidification of both of the laminates 11, 12, the bubbles of the first laminates 11 are eliminated. Therefore, the bubbles which have large diameter and are harmful are almost eliminated and then is no danger of the gel coat 13 being damaged.

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 resin molded product used as a bathtub, a water container or the like.

[0002]

2. Description of the Related Art A resin molded product used for a bathtub or the like is required to have watertightness and heat resistance. Conventionally, this type of resin molded article has a gel coating on the surface of a laminate in which reinforcing fibers such as glass fiber and carbon fiber are mixed with thermosetting reinforced resin in a length of about 25 to 50 mm (1 to 2 inches). Were generally formed. In such a molded article, if air bubbles having a diameter of 1 mm or more exist between the laminate or the gel coat and the laminate, the gel coat is destroyed by repeatedly applying high and low temperatures like a bath. If the gel coat is broken, dirt will be attached and the appearance will be unsightly, and it will also cause water leakage. For this reason, resin molded products used in bathtubs, etc. must remove harmful air bubbles from the laminate or between the laminate and the gel coat.

As a method for forming a laminate of fiber-reinforced resin, a spray-up method is known which can be carried out with relatively simple equipment. The spray-up method uses a predetermined length (25-50
The reinforcing fibers (about mm) are sprayed on the mold together with the atomized thermosetting reinforcing resin to form a laminate. Conventionally, various methods have been developed for removing harmful air bubbles when forming a laminate by a spray-up method. For example, in Japanese Patent Publication No. 59-35765, a resin is sprayed onto a mold under reduced pressure together with reinforcing fibers to form a laminate, and then a foam surface layer is formed on the laminate and exposed under atmospheric pressure. A method of disrupting bubbles is disclosed. Further, JP-A-60-124237 discloses a method of spraying a resin together with reinforcing fibers onto a molding die to form a laminate, and then forming an airtight surface layer on the laminate and applying pressure. In either method, it is necessary to form an airtight surface layer made of resin, and since the surface layer does not contain reinforcing fibers, the strength of the molded product decreases. The surface layer may be cracked during curing. In the method disclosed in Japanese Patent Laid-Open No. 60-124237, the molded product must be cured in a pressure tank until the molded product is completely cured. It is not economical because it takes a long time to occupy a tank and productivity deteriorates. Since the length of the reinforcing fiber is 25 to 50 mm, large bubbles are likely to occur. In particular, large bubbles tend to be generated in the corners of molded products, and defoaming work cannot be performed easily. For this reason, defective defoaming is likely to occur, resulting in variations in quality.

[0004]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems of the prior art, and its object is to prevent the presence of toxic air bubbles in the laminate, and thus to prevent water-tightness, such as in bathtubs. An object of the present invention is to provide a fiber-reinforced resin molded article suitable for use in articles that require heat resistance. Another object of the present invention is to provide a method for producing a fiber-reinforced resin molded product, in which defoaming work is extremely easy and productivity can be improved.

[0005]

The fiber-reinforced resin molded article of the present invention comprises a first laminate comprising a relatively short reinforcing fiber and a thermosetting resin and a first laminate comprising a relatively long reinforcing fiber and a thermosetting resin. The above object is achieved by comprising a second laminate and a gel coat on the surface of the first laminate, and interposing the first laminate containing no bubbles between the gel coat and the second laminate.

The method for producing a fiber-reinforced resin molded product of the present invention is a method for producing a fiber-reinforced resin molded product by a spray-up molding method, in which a relatively short reinforcing fiber and a thermosetting resin are blown into a molding die. Applying to form a first laminate, and the first laminate before the first laminate is cured.
The step of spraying a relatively long reinforcing fiber and a thermosetting resin to the laminate to form a second laminate, and the step of curing the first and second laminates. The above object is achieved.

[0007]

EXAMPLES Examples of the present invention will be described below.

As shown in FIG. 1, the fiber-reinforced resin molded product of the present invention comprises a first laminate 11 composed of a relatively short reinforcing fiber 11a and a thermosetting resin 11b, and a relatively long reinforcing fiber 12a and a thermosetting resin 11b. It has a second laminate 12 made of a curable resin 12b. A gel coat 13 as a top coat is formed on the surface of the first laminate 11.

Reinforcing fiber contained in the first laminate 11
The length of 11a ranges from 2.0 to 10.0 mm, preferably 3.0 to
The range is 6.0 mm. Also, the first laminate 11 is
It has a thickness of 0.6 to 1.25 mm.

The length of the reinforcing fibers contained in the second laminate 12 is in the range of 25 to 50 mm. First laminate 11
The reinforcing fiber 11a contained in the laminate is shorter than the reinforcing fiber contained in the conventional laminate having a length of 25 to 50 mm (1 to 2 inches), and the mechanical strength of the laminate 11 is slightly reduced. It is well compatible with and the voids and bubbles due to the entanglement such as bridges between fibers become smaller and smaller. In the conventional laminate in which the length of the reinforcing fiber is 25 to 50 mm, bubbles having a diameter of about 2.0 to 3.0 mm are generated, whereas when the length of the reinforcing fiber is about 10 mm as in the present invention, the diameter is 1.0. If bubbles of about ~ 1.5 mm are generated and the length of the reinforcing fiber is less than 6 mm, only very small bubbles of 0.5 to 1.0 mm in diameter are generated. As for the mechanical strength of the laminate, if the length of the reinforcing fiber is about 10 mm, it has the strength of 80 to 90% of the conventional laminate having the length of the reinforcing fiber of 25 to 50 mm, but the length of the reinforcing fiber is 6 mm. When it is less than the following, the strength is halved. When it is less than 2 mm, cracks due to curing shrinkage can be prevented, but the reinforcing effect is hardly exhibited. If the length of the reinforcing fiber is less than 2 mm, it is difficult to cut and spray the fiber with a spray-up machine. For this reason,
The reinforcing fiber contained in the first laminate 11 is preferably 2 mm or more.

In a laminate having a reinforcing fiber with a length of about 10 mm, air bubbles with a diameter of 1.0 to 1.5 mm are generated and a diameter of 1.0 m
Defoaming work is required because harmful bubbles of m or more are generated. In this case as well, the maximum diameter of the bubbles is about 1.5 mm, so degassing work is easy. However, in a laminate with reinforcing fibers of 6 mm or less, the diameter of the bubbles is as small as 1.0 mm or less, and no harmful bubbles are generated, so defoaming work becomes unnecessary. When rolling the roller onto the laminate in order to do so, the entire laminate moves as the roller moves,
Defoaming work cannot be done). The content of the reinforcing fiber 11a in the first laminate 11 is 25 to 30% by weight, preferably about 28% by weight, based on 100% by weight of the laminate.
When the content of the reinforcing fibers is within this range, there is no possibility that the resin floats on the laminate surface and the reinforcing fibers are exposed on the surface.

If the thickness of the first laminate 11 is less than 0.6 mm, the laminate itself cannot serve as a reinforcing layer. 1.25 mm
In the above case, the reinforcing fibers are short, which may cause dripping during molding. If it is less than 0.6 mm, the air bubbles generated in the second laminate penetrate through the first laminate,
When it enters the boundary with the gel coat and becomes 1.25 mm or more, it becomes the second
The laminate becomes thinner accordingly, and the bending strength of the molded product becomes weaker. Therefore, the range of 0.6 mm to 1.25 mm is preferable.

Reinforcing fibers contained in the second laminate 12
The length of 12a is about 25 to 50 mm, which is the same as the reinforcing fiber contained in the conventional laminate. Therefore, harmful bubbles with a diameter of 1 mm or more are generated, but such bubbles do not float on the surface due to the presence of the first laminate 11,
It does not destroy the gel coat 13. Nor does it reduce the strength of the laminate 12 itself.

As the reinforcing fiber in each of the laminates 11 and 12, glass fiber, carbon fiber, aramid fiber or the like is used. As the thermosetting resin, an unsaturated polyester resin, an epoxy resin, a phenol resin or the like is used as in the gel coat.

The fiber-reinforced resin molded product of the present invention as described above is manufactured, for example, by the molding apparatus shown in FIG. The molding apparatus includes a molding die 22 arranged on a turntable 21.
And two spray-up machines 30 and 40. On the other hand, the spray-up machine 30 includes, for example, a resin sprayer 31 for spraying a thermosetting resin such as unsaturated polyester, and a continuous fiber strip 33 such as glass cut into a predetermined length (2 to 10 mm) And a fiber spraying machine 32 for spraying. The other spray-up machine 40 includes a resin sprayer 41 for spraying a resin similar to the resin sprayed by the spray-up machine 30 and a continuous fiber strip 43 such as glass cut into a predetermined length (25 to 50 mm). And a fiber spraying machine 42 for spraying as fibers. A resin supply pipe 34 and a curing agent supply pipe 35 are attached to the resin sprayer 31, the resin supply pipe 34 supplies a predetermined thermosetting resin to the sprayer 31, and the curing agent supply pipe 35 supplies a curing agent. Sprayer 31
Supply to. The other sprayer 41 is also provided with a similar resin supply pipe 44 and curing agent supply pipe 45.

A fiber-reinforced resin molded product produced by the molding apparatus having such a structure is manufactured as follows. First, a gel coat is formed in advance on the mold 22 on the turntable 21. If the molded product does not require a gel coat, the gel coat of the mold 22 need not be formed. Next, the thermosetting resin mixed with the curing agent is sprayed from the resin spraying machine 31 of the one spray-up machine 30 onto the molding die 22, and the fiber spraying machine 32 sprays a short length of a predetermined length in the range of 2 to 10 mm. Spray the fibers to form a first laminate. While the laminate is uncured, a thermosetting resin mixed with a curing agent is sprayed from the resin sprayer 41 of the spray-up machine 40 onto the first laminate, and at the same time, the fiber spraying machine 42 is used to spray 25 to 50 mm Spraying long fibers of a given length in the range to form a second laminate. Then, when the length of the short fibers is 6 mm or more (10 mm or less), the rollers are rolled on the surface of the second laminate at a predetermined pressure while both laminates are uncured. Thereby, the bubbles generated in the first laminate are defoamed. This defoaming operation can be easily performed because the size of the bubbles is smaller than the size of the bubbles in the conventional laminate. When the length of the short fibers is 6 mm or less, the diameter of the bubbles generated in the first laminate is usually 1 mm or less, and the defoaming work by the roller is unnecessary. Then, a second laminate is formed, and after the defoaming work, the first and second laminates are cured to obtain a molded product having a predetermined shape in which both laminates are integrated.

[0017]

As described above, the present invention has the first laminate having almost no harmful air bubbles.
There is no risk of breaking the gel coat, etc.
It has excellent heat resistance, and even if it is used in an environment where the temperature changes drastically like a bathtub, the appearance is not impaired, and the service life can be extended.

According to the manufacturing method of the present invention, the defoaming work is extremely easy or the defoaming work is unnecessary, and the watertightness
Molded products with excellent heat resistance can be easily obtained, improving productivity.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a fiber-reinforced resin molded product of the present invention.

FIG. 2 is a schematic view of an apparatus for manufacturing the molded product.

[Explanation of symbols]

 11 First Laminate 11a Reinforcing Fiber 11b Thermosetting Resin 12 Second Laminate 12a Reinforcing Fiber 12b Thermosetting Resin 22 Mold 30,40 Spray-up Machine

Claims (5)

[Claims] 1. A method for producing a fiber-reinforced resin molded article by a spray-up molding method, which comprises spraying a relatively short reinforcing fiber and a thermosetting resin onto a molding die to form a first laminate. , A step of spraying a relatively long reinforcing fiber and a thermosetting resin on the first laminate to form a second laminate before the first laminate is cured, and the first and second laminates are A method for producing a fiber-reinforced resin molded article, which includes a step of curing. 2. The reinforcing fiber of the first laminate has a length of 2 to 10 mm, and the reinforcing fiber of the second laminate has a length of 25 to 50 mm. A method for producing a fiber-reinforced resin molded product. 3. The thickness of the first laminate is 0.6 to 1.2.
The method for producing a fiber-reinforced resin molded product according to claim 1, which has a size of 5 mm. 4. The method for producing a fiber-reinforced resin molded product according to claim 1, wherein a gel coat is formed on the molded product. 5. The method for producing a fiber-reinforced resin molded article according to claim 1, wherein a defoaming operation is performed after the step of forming the second laminate.