JPH11129336A - Production of fiber reinforced plastic molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a molded product markedly suppressed in the generation of air bubbles or cavities, having no fiber fluffiness on its surface and excellent in appearance quality and strength by allowing a resin compsn. to meet with a fiber reinforcing material in air to form a mixture and spraying this mixture on a mold and subsequently spraying sand thereon. SOLUTION: If necessary, a release agent is applied to the surface of a mold and a gel coat layer is formed thereon and a fiber reinforcing material and a resin compsn. are sprayed on the surface thereof and defoaming work such as rolling work is applied to the thus formed layer of the mold by using a defoaming roll made of aluminum or pig hair to cure the layer to obtain an FRP molded product. From a viewpoint reducing the involution of air bubbles into the mixture sprayed on the mold and further enhancing foam breaking properties, the one spraying thickness of the resin compsn. and the fiber reinforcing material to the mold is pref. set to 1-3 mm before sand is sprayed. The particle size of sand to be used is pref. 50-2,000 μm in consideration of the voids and strength of the molded product.

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 (hereinafter, sometimes referred to as FRP) molded article using a spray-up machine.

[0002]

2. Description of the Related Art Among manufacturing methods of fiber-reinforced plastic molded products such as septic tanks and bathtubs, an open mold molding method such as a hand lay-up molding method or a spray-up molding method is used.
It is widely used because it is possible to produce many kinds and small quantities at room temperature and pressure, and the equipment cost is low. Among them, the spray-up molding method is to provide a gel coat layer on the surface of a previously manufactured mold as necessary, and apply a resin composition containing short fibers (fiber reinforcing material) such as glass fiber and unsaturated polyester to the surface. This is a method of forming the fiber reinforcement layer by spraying, but since large and small bubbles are mixed in the formed fiber reinforcement layer, when the fiber reinforcement layer is cured, the bubbles are removed using a defoaming roll. Work is indispensable.

[0003] In such a spray-up molding method, the fiber reinforcement and the resin composition forming the fiber reinforcement layer are scattered, and the solvent such as styrene monomer contained in the resin composition is scattered. Since the molding operation in an unfavorable environment is forced, the mechanization of the defoaming operation is difficult and it must be performed manually, and it takes a long time for molding and the skill is required for the defoaming operation. There was a problem with securing.

As a method for solving these problems, Japanese Patent Application Laid-Open No. 63-293038 discloses a method in which a fiber-reinforced plastic material, which is a kneaded product of a cut fiber and a resin composition, is pressure-fed into a hose by a pressure pump. There has been proposed a method for producing a fiber-reinforced plastic molded article that does not require defoaming work by applying the composition to the surface of a mold using an application nozzle. However, in this method, fibers cut to a length of 12.5 mm or more are entangled with each other to form a lump,
It is difficult to apply the fiber reinforced plastic material uniformly to the surface of the mold, and the low glass content lowers the strength of the molded product, and further increases the viscosity of the kneaded material to the mold. There is a problem that air bubbles are apt to be mixed in at the time of coating.

Japanese Patent Application Laid-Open No. Hei 5-239259 discloses that a resin composition containing a thermosetting resin, a spherical hollow filler and / or a star-like filler, and a fiber reinforced material are sprayed up using a spray-up machine. There has been proposed a method for producing a fiber-reinforced plastic molded article that does not require a defoaming step by using a roller or the like by applying it to the surface of a molding die. However, in this method, when the content of the fiber reinforcing material is high, the wetting of the resin composition and the fiber reinforcing material is reduced, and the generation of fuzz of the fibers on the surface and large bubbles inside the molded product remain, A defoaming step using a roller or the like is required. Further, when the amount of the fiber reinforcing material is small, there is a problem that the strength of the molded article is reduced although the fluff of the fibers and the large bubbles inside the molded article are reduced.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and in a method of manufacturing a fiber-reinforced plastic molded product by a spray-up method, generation of bubbles and cavities can be significantly suppressed. No fiber fuzz,
An object of the present invention is to provide a method for producing a fiber-reinforced plastic molded article which can obtain a molded article having excellent appearance quality and excellent strength.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to a method of spraying a mixture obtained by combining a resin composition and a fiber reinforcing material in the air by a spray-up machine into a mold, and then spraying sand thereon. The present invention relates to a method for producing a fiber-reinforced plastic molded product. The present invention also provides a resin composition 5
Spray 5 to 50 parts by weight of sand to 0 to 95 parts by weight,
The present invention relates to a method for producing the fiber-reinforced plastic molded product, wherein the total amount of the resin composition and sand is 100 parts by weight.
Further, the present invention, the total amount of the resin composition and sand is 60 to 90 parts by weight and the amount of the fiber reinforcement is 10 to 40 parts by weight,
The present invention relates to a method for producing the fiber-reinforced plastic molded article, wherein the total amount of the resin composition, sand and fiber reinforcement is 100 parts by weight. Further, the present invention relates to a method for producing the fiber-reinforced plastic molded product, wherein a mixture of the resin composition and the fiber-reinforced material is sprayed on a mold at a thickness of 1 to 3 mm.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the resin composition is not particularly limited as long as it is used for producing a fiber-reinforced plastic molded article such as a septic tank or a bathtub. , A vinyl ester resin composition and the like, and an unsaturated polyester resin composition is particularly preferable. The unsaturated polyester resin composition contains an unsaturated polyester, a polymerizable monomer, a curing agent, and, if necessary, various additives. The unsaturated polyester used in the present invention is obtained by reacting an acid component containing an unsaturated dibasic acid and / or an acid anhydride thereof and another polybasic acid used as required with an alcohol component by a known method. It can be obtained by

As the unsaturated dibasic acid and its acid anhydride, maleic acid, fumaric acid, itaconic acid, citraconic acid, maleic anhydride and the like are used, and two or more of these may be used in combination. The unsaturated dibasic acid and its acid anhydride are preferably used in an amount of 1 to 100 mol% in the acid component. In addition, these impart moderate hardness to the molded product,
Moreover, in order not to be too brittle, 20 to 90%
Mol%, more preferably 30 to 70 mol%
It is particularly preferred that they be used.

[0010] Other polybasic acids used as needed include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, trimellitic acid, trimellitic anhydride, succinic acid, azelaic acid, adipic acid, tetrahydrophthalic acid Acids, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, anthracene-maleic anhydride adduct, rosin-maleic anhydride adduct, hetic acid, hetic anhydride, tetrachlorophthalate Acid, tetrachlorophthalic anhydride, tetrabromophthalic acid, halogenated polybasic acids such as tetrabromophthalic anhydride, and the like. These may be used in combination of two or more. These are used by adjusting so that the entire acid component becomes 100% by weight.

As the alcohol component, ethylene glycol, diethylene glycol, propylene glycol,
Dipropylene glycol, 1,3-butanediol,
1,4-butanediol, 2,3-butanediol,
1,5-pentanediol, 1,6-hexanediol, triethylene glycol, neopentyl glycol, 1,4-cyclohexanediol, dihydric alcohols such as hydrogenated bisphenol A, glycerin, trihydric alcohols such as trimethylolpropane, For example, a tetrahydric alcohol such as pentaerythritol is used. Two or more of these may be used in combination. The reaction between the acid component and the alcohol component is mainly performed by advancing a condensation reaction, and is advanced by desorbing a low-molecular compound such as water generated when both components react, to the outside of the system. The acid component and the alcohol component consist of one equivalent of the acid component and one alcohol component.
To 1.3 equivalents, preferably from 1.03 to 1.
It is more preferable to use 2 equivalents.

Examples of the polymerizable monomer include (meth) acrylic esters such as styrene, vinyltoluene, α-methylstyrene, chlorostyrene, divinylbenzene and methyl methacrylate [(meth) acrylic acid is methacrylic acid And acrylic acid. The same applies to the following), and vinyl acetate and the like are used, and two or more of these may be used in combination. The unsaturated polyester and the polymerizable monomer are 30 to 80% by weight of the former and 2
It is preferable to use 0 to 70% by weight.
It is particularly preferred to use 5% by weight and the latter 35-65% by weight.

[0013] Examples of the curing agent include organic peroxides such as methyl ethyl ketone peroxide, benzoyl peroxide, cumene hydroperoxide and lauroyl peroxide. This curing agent is usually added to the unsaturated polyester resin composition in an amount of 0.5 to 3.0.
It is blended in a ratio of weight%. It is preferable that the curing agent is separately prepared and mixed immediately before or at the time of using the resin composition. The curing agent is preferably used by dissolving it in an organic solvent such as xylene or toluene, or a liquid plasticizer such as dimethyl phthalate or dioctyl phthalate.

The unsaturated polyester composition obtained by dissolving the unsaturated polyester in the above polymerizable monomer and blending a curing agent, a curing accelerator, etc., may further contain, if necessary, hydroquinone, pyrocatechol, Polymerization inhibitors such as 6-di-tert-butylparacresol, dyes, plasticizers, ultraviolet absorbers, silica powder, asbestos powder, hydrogenated castor oil, known thixotropic agents such as fatty acid amides, calcium carbonate, titanium, etc. Filler with a large specific gravity, silica balloon,
Various additives such as a filler having a small specific gravity such as a glass balloon, a stabilizer, an antifoaming agent, and a leveling agent may be blended.

Examples of the curing accelerator include metal soaps such as cobalt naphthenate and cobalt octenoate; quaternary ammonium salts such as dimethylbenzylammonium chloride; β-diketones such as acetylacetone; dimethylaniline; -Amines such as toluidine and triethanolamine. The blending ratio of the curing accelerator is not particularly limited and is appropriately determined depending on the required curability, but is preferably 0.005 to 5 based on the total amount of the unsaturated polyester and the polymerizable monomer. weight%
used.

The production of the FRP molded article of the present invention is carried out by a spray-up molding method. In this method, a release agent is applied and a gel coat layer is formed, if necessary, on the surface of a previously produced mold. Then, a fiber reinforced material and a resin composition are sprayed on the surface, and defoaming such as rolling using an aluminum or pig hair defoaming roll is performed, followed by curing to obtain an FRP molded product.

The fiber reinforcement is not particularly limited, and various known fiber reinforcements and fiber reinforcements surface-treated with a coupling agent can be used. Examples thereof include glass fiber, carbon fiber, and organic synthetic fiber. Whiskers, ceramic fibers, metal fibers, natural plant fibers and the like. In consideration of the strength and moldability of the molded product, the amount of the fiber reinforcing material may be 10 to 40 parts by weight based on the total amount of the resin composition and the sand of 60 to 90 parts by weight. Preferably, it is more preferably 15 to 35 parts by weight. The mixing ratio is such that the total amount of the resin composition, sand and fiber reinforcement is 10%.
It is determined to be 0 parts by weight. Further, it is preferable that the total amount of the resin composition and the fiber reinforcing material is sprayed on the molding die at a discharge rate of 2 to 15 kg / min.

As the fiber reinforcing material to be sprayed, glass roving is preferable. The length of the fiber reinforcing material (cut length of the glass roving) is preferably in the range of 5 to 50 mm, particularly from the viewpoint of preventing dripping of the mixture sprayed on the mold and reducing entrapment of air bubbles. It is preferably 40 mm, more preferably 12 to 25 mm.

In the present invention, the distance between the mold and the spray gun is not particularly limited. However, if the distance is too long, air bubbles are likely to be mixed, and if the distance is too short, the resin composition and the fiber reinforcing material are scattered. 400 ~ 1200mm
And more preferably 500 to 700 mm.

Further, from the viewpoint of reducing the entrapment of air bubbles of the mixture blown to the mold and further improving the foam breaking property, the thickness of each spraying of the resin composition and the fiber reinforcing material to the mold is 1 to 1. It is preferable to spray sand after making the thickness 3 mm. The sand used in the present invention is not particularly limited with respect to the place of collection and the processing method, but in consideration of the porosity and strength of the molded product, the particle size is preferably 50 to 2000 μm,
00 to 1000 μm is particularly preferred.

The amount of the sand used is in the range of 50 to 9 for the resin composition.
The amount is preferably 5 to 50 parts by weight, more preferably 20 to 40 parts by weight, based on 5 parts by weight. However, it is determined that the total amount of the resin composition and the sand is 100 parts by weight. If the proportion of sand is out of the above range, many voids remain in the molded product, so that the porosity increases and the strength tends to decrease. In the present invention, the method of spraying the sand is not particularly limited, and a spray gun or the like can be used as necessary. The discharge amount at the time of blowing the sand is 0.1 to 0.1 in consideration of the entrapment of air bubbles and the foam breaking property.
Preferably, it is 5 kg / min. The sand is preferably sprayed within 10 minutes, more preferably within 5 minutes after spraying the mixture of the resin composition and the fiber reinforcement. If the blowing of the sand is too slow, the wetting of the sand and the resin composition tends to be poor. Also, if the sand is sprayed too early, there is no effect of breaking air bubbles. Therefore, it is not necessary to rush too quickly, and it may be performed after a lapse of 1 to 2 minutes after spraying the mixture of the resin composition and the fiber reinforcing material.

[0022]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In the examples, “parts” and “%” indicate “parts by weight” and “% by weight”, respectively, unless otherwise specified.

Reference Example (Production of Unsaturated Polyester Composition) 5 mol of maleic anhydride, 5 mol of phthalic anhydride and 10.5 mol of propylene glycol were mixed with a stirrer, a condenser,
The mixture was charged into a 2-liter four-necked flask equipped with a thermometer and an inert gas inlet, and reacted at 210 ° C. in a conventional manner under nitrogen gas introduction. To 55 parts of the obtained unsaturated polyester, 45 parts of styrene and 200 ppm of hydroquinone based on this mixture were added to obtain an unsaturated polyester composition.

Examples 1 to 3 100 parts of the unsaturated polyester composition prepared in Reference Examples,
As a thixotropic agent, 1.8 parts of silica powder (trade name: Aerosil # 200, manufactured by Nippon Aerosil Co., Ltd.), 0.4 parts of 6% cobalt naphthenate, 0.01 parts of 5% copper naphthenate and 0.1 parts of dimethylaniline 0.1 Parts were mixed and dissolved to obtain a viscosity of 0.4 Pa · S,
A resin composition for molding having a degree of thixotropicity of 4.0 and a gelling time of 15 minutes was obtained. Viscosity, thixotropic degree and gel time are JIS
It was measured according to K6901. When measuring the gelation time, 55% of the resin composition was used as a curing agent.
A 1.0% solution of methyl ethyl ketone peroxide in dimethyl phthalate was used.

A fiber reinforced material consisting of a 55% methyl ethyl ketone peroxide solution in dimethyl phthalate and a glass roving in a ratio of 1% of a curing agent to the resin composition (glass roving manufactured by Nitto Boseki Co., Ltd., trade name 2310)
TEX-A-673, used in an amount of 33% based on the total amount of the resin composition and the fiber reinforcing material) on a molding die under the conditions shown in Table 1, and using a spray gun under the conditions shown in Table 1. I sprayed sand. Immediately thereafter, a defoaming step consisting of a predetermined number of rolls is performed with a pig hair spiral roll (outer diameter 50 mm, length 150 mm), and after curing at room temperature,
The mold was removed to obtain a fiber-reinforced plastic molded product. The mold at this time was worked upright. The presence or absence of fluffing due to fibers in the obtained molded article was visually observed, and a flat portion of the molded article was cut out, and the porosity was measured in accordance with JIS K7053 and the strength was measured in accordance with JIS K7055. It was shown to.

[0026]

[Table 1]

Comparative Examples 1 to 3 FRP molded articles were produced in the same manner as in the above Examples under the conditions shown in Table 2, and the presence or absence of fuzzing, porosity, and strength of fibers of the molded articles were evaluated in the same manner as in the Examples. Table 2 shows the measurement results.

[0028]

[Table 2]

[0029]

According to the method of the present invention, even if the defoaming step is simplified (for example, the number of rolls for defoaming is reduced), the incorporation of air bubbles can be prevented, and the fluffing of fibers can be prevented. Thus, a molded article having excellent strength can be obtained, and quality and productivity can be improved, such as prevention of defects due to poor defoaming and reduction of manufacturing costs.

Claims (4)

[Claims] 1. A fiber-reinforced plastic molded article characterized in that a mixture obtained by combining a resin composition and a fiber reinforced material in the air by a spray-up machine is sprayed on a mold, and then sand is sprayed thereon. Manufacturing method. 2. The fiber-reinforced plastic according to claim 1, wherein 5 to 50 parts by weight of sand is sprayed on 50 to 95 parts by weight of the resin composition so that the total amount of the resin composition and the sand is 100 parts by weight. Manufacturing method for molded products. 3. The total amount of the resin composition and the sand is 60 to 90 parts by weight, and the amount of the fiber reinforcement is 10 to 40 parts by weight, and the total amount of the resin composition, the sand and the fiber reinforcement is 100 parts by weight. The method for producing a fiber-reinforced plastic molded product according to claim 1, wherein: 4. The method for producing a fiber-reinforced plastic molded product according to claim 1, wherein the mixture of the resin composition and the fiber-reinforced material is sprayed on the mold at a thickness of 1 to 3 mm.