JPH06305035A - Preparation of fiber-reinforced plastic molded item - Google Patents

Abstract

PURPOSE:To provide a method for preparing a fiber-reinforced plastic molded item wherein mixing of air bubbles into a layer can be prevented from occurring without passing through defoaming process and a molded item with no fluffing of the fibers on the surface, excellent appearance, quality and strength can be obtd. CONSTITUTION:A resin compsn. contg. 48-60wt.% styrene monomer and acrylic monomer and with a viscosity of 0.15-0.2Pa.s at 25 deg.C and a compsn. contg. 28-40wt.% fiber reinforcing material to the resin compsn. with a cut length of 12.5-25mm are applied on the surface of a mold 1 by means of a spray-up method and they are cured.

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 plastic molded article, and more specifically, it suppresses the generation of bubbles and cavities in a layer without passing through a defoaming step, and furthermore, the surface of fibers is not fluffed. The present invention relates to a method for producing a fiber-reinforced plastic molded product, which is capable of obtaining a molded product having excellent appearance quality and strength without the use of a molded product.

[0002]

2. Description of the Related Art The spray-up molding method, which is a method for manufacturing fiber-reinforced plastic molded articles such as septic tanks and bathtubs, is widely used because of low equipment cost. In this spray-up molding method, a gel coat layer is provided on the surface of a prefabricated mold if necessary, and a resin composition containing short fibers (fiber reinforcing material) such as glass fiber and unsaturated polyester is sprayed on the surface. This is a method of forming a fiber reinforced layer by using a defoaming roll that removes air bubbles when curing the fiber reinforced layer because large and small bubbles are mixed in the formed fiber reinforced layer. Has become indispensable. In such a spray-up molding method, scattering of the fiber reinforcing material and the resin composition when forming the fiber reinforcing layer, and the emission of a solvent such as styrene monomer contained in the resin composition, are preferable in terms of safety and hygiene. Molding work in a non-existent environment is forced, and it is difficult to mechanize defoaming work and must be done manually, which requires time for molding, and defoaming work requires skill, so productivity,
There was a problem in ensuring quality.

As a method for solving these problems, Japanese Patent Application Laid-Open No. 63-293038 discloses that a fiber-reinforced plastic material, which is a kneaded product of cut fibers and a resin composition, is pressure-fed in a hose by a pressure-feeding pump. A method for producing a fiber-reinforced plastic molded product has been proposed in which defoaming work is unnecessary by applying the composition onto the surface of a mold with a coating nozzle. However, in the above method, the fibers cut to a length of 12.5 mm or more may be entangled with each other to form a mass, which makes it difficult to uniformly apply the fiber-reinforced plastic material to the surface of the molding die. In addition, since the glass content is low, the strength of the molded product is reduced, and the viscosity of the kneaded material is increased, so that air bubbles are easily mixed when applied to the molding die. Further, when a gel-coated molded article is produced by the above-mentioned method, there is a problem that swelling due to cooling and heating cycles and irregularities in the fiber pattern on the gel-coat surface occur, and the surface does not become smooth and the appearance quality deteriorates.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, suppresses the generation of bubbles and cavities in a layer without undergoing a defoaming step, and further, the surface of fibers is not fluffed. The present invention provides a method for producing a fiber-reinforced plastic molded product, which is capable of obtaining a molded product excellent in appearance quality and strength without the use of a resin.

[0005]

According to the present invention, a styrene monomer and an acrylic monomer are added to the surface of a molding die in an amount of 48 to 60.
Weight% included, viscosity at 25 ° C is 0.15-0.2P
a · s resin composition and 28 to 4 with respect to the resin composition
The present invention relates to a method for producing a fiber-reinforced plastic molded article, in which a composition containing 0% by weight of a fiber reinforcement having a fiber cut length of 12.5 to 25 mm is applied and cured by a spray-up method.

The fiber reinforced plastic layer used in the production method of the present invention contains a resin composition and a fiber reinforced material. The resin composition contains an unsaturated polyester resin, a vinyl ester resin, a resin component such as an epoxy resin, a styrene monomer and an acrylic monomer, and the use ratio thereof is from the viewpoint of the strength of the cured product and the reduction of residual bubbles. The styrene monomer and the acrylic monomer are in the range of 48 to 60% by weight, preferably 50 to 55% by weight, based on the total amount of the resin composition. As the acrylic monomer, methyl methacrylate, 2-hydroxyethyl acrylate or the like is used, and the use ratio thereof is preferably within the range of 10% by weight or less based on the total amount of the polymerizable monomers. The resin composition has a viscosity at 25 ° C. of 0.15 to 0.2 P by adding a solvent or the like as necessary.
a · s. If the viscosity of the resin composition exceeds the above range, impregnation into the fiber reinforcing material will be insufficient, and residual air bubbles will occur in the cured product, and if less than the above range, sagging during molding will occur.

As the fiber reinforcing material, glass fibers, glass fibers treated with silane, chromium, borane, or the like are used. Among them, the silane treatment was applied and the wet-out time measured by the method shown below was 55 to 7
0 seconds, waist strength 40-55g and bulkiness 10-20
Glass fibers of mm are preferred. The cut length of the fiber reinforcement is 12.5 to 25 mm, but the present invention enables the use of the fiber reinforcement in this range. The amount of fiber reinforcement used is 28 to 40% by weight, preferably 30 to 3 to prevent sagging and impregnation failure with respect to the resin composition.
It is 5% by weight.

The methods for measuring the above-mentioned wet-out time, waist hardness and bulkiness are shown below. (1): Wet-out time (second): Length of about 20 cm (0.92 g / 2) with a fiber reinforced material on a transparent plate with cellophane tape
Fixed to 0 cm). Then 1.0% by weight curing agent (MEK
About 30 g of Polyset 660P-2 (unsaturated polyester resin, trade name manufactured by Hitachi Chemical Co., Ltd.) containing PO) is applied on the roving, and a transparent film is placed on the roving. After that, a ruler is applied on the transparent film to uniformly stretch the resin, and the time until the resin is completely spread between the filaments of the glass fiber is measured. (2): waist strength (g): predetermined diameter 2 as shown in FIG.
Pull out the glass fiber 5 into the 0 mm titanium guide 6,
The strength at which the glass fiber 5 passes through the guide 6 by moving the hook 7 upward is measured with an autograph (manufactured by Shimadzu Corporation). (3): Bulkiness (mm): 60 g of glass fibers cut into a predetermined length are evenly distributed by hand on a 200 mm square frame, and a certain plate is applied as necessary, and the height at that time is measured. .

The fiber-reinforced plastic molded product is a spray-up machine type HIS80-1116 manufactured by Venus Co., Ltd., east-type spray-up, which is a composition containing the above-mentioned resin composition and fiber-reinforced material on the surface of the mold by a known spray-up method. It is manufactured by coating using a machine type HLL15000, curing at room temperature, and then removing the molding die. A mold release agent may be applied to the surface of the mold to facilitate the removal of the mold. Further, when the following ability of the glass fiber is poor, it may be lightly pressed by a roller, or a top coat may be performed by spraying the resin composition alone in order to improve the smoothness of the spray surface. According to such a production method of the present invention, even if the cut length of the glass fiber is 12.5 mm or more, the fiber-reinforced plastic is uniformly mixed with no bubbles and no fluff of the fiber is generated on the surface. Since the layer can be formed, it is not necessary to perform the defoaming work as in the conventional case. Further, since the glass fiber is contained in the range of 25 to 40% by weight with respect to the resin composition, a molded product having strength as good as conventional one can be obtained.

In the present invention, in order to prevent water leakage of the fiber-reinforced plastic molded product, it is preferable to form the coating layer on the surface of the mold and then form the fiber-reinforced plastic layer. The coating layer is formed by applying a coating material containing unsaturated polyester or polyvinyl ester and a lightweight filler having a particle size range of 5 to 20% by weight to the resin of 10 to 200 μm to the surface of the mold and curing the coating material. can get. As the lightweight filler, glass balloons, silica balloons, shirasu balloons, carbon balloons, phenol balloons, alumina balloons and the like are used. The particle size range is 10 to 200 from the viewpoint of the viscosity of the coating material and the prevention of phase separation.
μm, preferably 10 to 120 μm. The shape of the lightweight filler is preferably spherical. Further, the gelling time of the unsaturated polyester resin or the vinyl ester resin at 25 ° C. is preferably 3 to 5 minutes from the viewpoint of preventing sagging.
The thickness of the coating layer is usually in the range of 0.5 to 1.0 mm.

In the present invention, in order to prevent the generation of cracks and blisters of the fiber-reinforced plastic molded product due to the heat and cold cycle, a gel coat layer is formed on the surface of the mold, and then the above-mentioned coating layer and fiber-reinforced plastic layer are formed. Preferably. The gel coat layer is formed by a known method using a known material, and usually a pigmented unsaturated polyester resin or vinyl ester resin is used.

[0012]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto. Examples 1 to 4 and Comparative Example 1 On the surface of the mold 1 of the bathtub shown in FIG. 1, from the resin composition having the composition and viscosity shown in Table 1 and the glass fiber (trade name, 2310TEX-0673S manufactured by Fuji Fiber Glass Co., Ltd.). The fiber reinforced plastic layer is coated by the spray-up method using the East-style spray-up machine HLL15000,
After curing at room temperature, it was demolded to obtain a fiber reinforced plastic molded product. The presence or absence of fluffing due to the fibers of the obtained molded product was visually observed, and the flat portion of the molded product was cut out and the strength was measured according to JIS K 7055. The results are shown in Table 1. The viscosity of the resin composition is JIS K
It measured according to 6901.

[0013]

[Table 1] Table 1 shows that according to the production method of the present invention, it is possible to obtain a molded article which is free from fiber fluff and has excellent strength without undergoing a defoaming step.

Examples 5 to 6 and Comparative Example 2 A coating material having the composition (% by weight) shown in Table 2 was coated on the surface of the molding die 1 shown in FIG.
5000 was applied and cured at room temperature to form a coating layer of 0.6 mm, and the same fiber reinforced plastic layer as in Example 1 and Comparative Example 1 was formed on the surface of this coating layer to form a fiber reinforced plastic molding. I got the goods. A partial cross-sectional view of these molded products is shown in FIG. Tap water was added to the obtained molded product, and the next day, the presence or absence of water leakage of the molded product was visually confirmed, and the results are shown in Table 2.

[0015]

[Table 2] From Table 2, after forming a coating layer on the surface of the mold,
It is shown that by forming the fiber-reinforced plastic layer, a water-tight molded article can be obtained.

Example 7 and Comparative Example 3 Polyset 682PH was formed on the surface of the mold 1 shown in FIG.
(Unsaturated polyester resin manufactured by Hitachi Chemical Co., Ltd.) was applied and cured to form a 0.3 mm gel coat layer, and then a coating layer and a fiber reinforced plastic layer were formed by the same method as in Example 5 and Comparative Example 2. Each fiber-reinforced plastic molded product was obtained by forming. Partial sectional views of these molded products are shown in FIG. The unevenness of the fiber pattern on the surface of the gel coat layer of the obtained molded product was visually observed 3 days after the mold release. In addition, the presence or absence of cracks and blisters due to the cooling / heating cycle of the molded product was visually observed by performing 12 cycles of boiling at 95 to 100 ° C. for 8 hours and cooling at ambient temperature for 16 hours as one cycle. The results are shown in Table 3.

[0017]

[Table 3] From Table 3, it is shown that by forming the gel coat layer on the surface of the mold, and then forming the coating layer and the fiber reinforced plastic layer, a molded product having no irregularities on the surface of the molded product and excellent in heat and cold resistance cycle can be obtained. Be done.

[0018]

According to the present invention, it is possible to prevent air bubbles from being mixed in the spray-up molding method without passing through a defoaming step,
Since a molded product excellent in strength and free from fiber fluff can be obtained, labor shortage can be eliminated, manufacturing cost can be significantly reduced, and productivity and quality can be improved. In addition, by forming a coating layer on the surface of the mold, a molded product that does not leak further can be obtained.By forming a gel coat layer and a coating layer on the surface of the mold, a molded product that is more excellent in cold and heat resistance cycle is obtained. To be

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mold used in Examples and Comparative Examples.

2 is a partial cross-sectional view of molded products obtained in Examples 5 and 6. FIG.

FIG. 3 is a partial cross-sectional view of a molded product obtained in Example 7.

FIG. 4 is an explanatory diagram of a method for measuring the waist strength of glass fibers.

[Explanation of symbols]

1 ... Mold, 2 ... Fiber reinforced plastic layer, 3 ... Coating layer, 4 ... Gel coat layer, 5 ... Glass fiber, 6 ... Guide, 7 ... Hook.

Claims (3)

[Claims] 1. A resin composition containing 48 to 60% by weight of a styrene monomer and an acrylic monomer on the surface of a molding die and having a viscosity at 25 ° C. of 0.15 to 0.2 Pa · s, and the resin composition. A method for producing a fiber-reinforced plastic molded article, which comprises applying a composition containing 28 to 40% by weight of a fiber reinforcement having a fiber cut length of 12.5 to 25 mm by a spray-up method and curing the composition. 2. An unsaturated polyester resin or vinyl ester resin on the surface of the molding die, and 5 to 2 with respect to this resin.
A coating material containing 0% by weight of a lightweight filler having a particle size range of 10 to 200 μm is applied and cured to form a coating layer, and then the composition of claim 1 is sprayed up on the coating layer. A method for producing a fiber-reinforced plastic molded product which is applied and cured by the method described above. 3. The surface of the mold is coated with a gel coat layer and cured, then the coating layer according to claim 2 is formed on the gel coat layer, and the composition according to claim 1 is formed on the coating layer. A method for producing a fiber-reinforced plastic molded product which is applied and cured by a spray-up method.