JPH082543B2 - Molding method for fiber reinforced plastic moldings - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for molding a fiber-reinforced plastic molded article. According to the present invention, the content of the fiber reinforcing material can be increased, and the mechanical strength of the obtained molded product can be increased. Moreover, a molded product can be efficiently molded.

2. Description of the Related Art In a resin injection molding method or a resist transfer molding method, a flash mold is used as a molding die. In this molding method, first, only the fiber reinforcing material is placed on one of the male and female molds and the mold is clamped. Male,
A rubber-like elastic body is used as a packing material on the mating surface of the female mold. After the mold is clamped, the resin is press-fitted into the closed mold through the injection holes provided at the appropriate positions of the mold, and the fiber reinforcement placed in advance is impregnated and cured to obtain the FRP molded product. .

In this molding method, the fiber reinforcing material is placed in advance, and the resin is injected into the molding die that has been closed to the set wall thickness of the molded product and is in a closed state. Requires large injection pressure. The pressure required for this injection increases as the fiber-reinforced plastic (hereinafter abbreviated as FRP) molded product has a higher fiber content.
Further, in the case of an FRP molded product having a high fiber content, it is difficult for the injected resin to spread to the entire molded product.

According to a practical example of the resin injection molding method, a mold made of FRP is used as a mold, an unsaturated polyester resin is used as a resin, and a glass content of about 30% by weight when a glass fiber chop strand mat is used as a fiber reinforcing material. When the glass fiber roving loss and the chopped strand mat are used in combination, the glass content is usually about 40 to 45% by weight. It is considered possible to mold an FRP molded product having a high fiber content by using a mold having a high strength as a mold and a resin injecting device having a high injection pressure, but there has been no practical application.

The mechanical properties of FRP molded products increase as the fiber content increases. However, in the conventional resin injection molding method, a technique for increasing the fiber content to the limit possible as FRP has not been developed.

In the mat or preform matched die molding method, a fiber reinforcement material (hereinafter, abbreviated as preform) preformed in a shape close to a mat or a molded product is placed on one of the male and female molds, Sprinkle the resin on the mat or preform, tighten the mold, and heat and pressure cure it.
This is a molding method for obtaining FRP molded products. After the mat or preform is placed on the male mold by this molding method, if the resin viscosity is low in the process of sprinkling the mat or preform with resin, the sprinkled resin will be removed from the mold before clamping. There is a drawback that it flows out to. For the purpose of improving such defects, the resin used in this molding method is usually a resin mixture in which the viscosity of the resin is increased by adding a filler or the like. The matte or preform matched die molding method has to use a resin mixture with such a high viscosity, so it is difficult to mold an FRP molded product with a high fiber content compared to the case of using a resin with a low viscosity. There is.
According to a practical example, when the unsaturated polyester resin is used as the resin and the glass fiber chopped strand mat is used as the fiber reinforcing material, the glass content is about 30% by weight at most.

Further, in the mat or preform matched die molding method, since the resin is sprinkled on the mat or pull foam placed in the mold in the open state, compared with the method of injecting the resin into the closed molding die of the resin injection molding method, There are environmental hygiene problems such as resin scattering and odor.

As described above, the conventional resin injection molding method and matte or preform matched die molding method have a high fiber content and high strength
It was not suitable for molding FRP molded products efficiently.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention An object of the present invention is to provide a molding method suitable for efficiently molding an FRP molded product having a high fiber content and a high strength.

The present inventors compared the conventional method by using a positive mold, a male mold, and a female mold as the structure of the cutting portion of the molding mold, and combining the conventional resin injection molding method with the mat or preform matched die molding method. Therefore, the inventors have found that the fiber content can be remarkably increased, and the mechanical strength of the obtained FRP molded product is large, and the present invention has been completed based on these findings.

MEANS FOR SOLVING THE PROBLEMS The present invention is to place the fiber reinforcing material on either the male or female mold of which the structure of the cutting portion of the molding die is positive, and then bring the male and female molds close to each other. A method for molding a fiber-reinforced plastic molded product, characterized in that the resin is pressed so as not to flow out from the cut-off portion, and then the resin is injected through an injection hole provided at an appropriate position in the mold, and then the mold is clamp-molded. .

In the present invention, first, the fiber reinforcing material is placed on either the male or female mold having the positive-cutting structure of the molding die. Except that the structure of the cutting part is positive type,
A mold structure generally used for FRP compression molding can be used. The travel of the cutting portion is determined by the bulk of the fiber reinforcing material placed in the mold in advance, but is about 2 to about 30 mm, preferably about 3 to about 10 mm, and the clearance is about 0.
05-0.15 mm is preferable.

As the material of the mold, for example, metal, plastic or the like is used. It is preferable to use a metal product because it allows mass production of molded products. The shape of the mold can be arbitrarily selected according to the shape of the target molded product.

As the fiber reinforcing material used in the present invention, an ordinary FRP is used.
Fiber reinforcements used in moldings can be used. For example, glass fibers, carbon fibers, quartz fibers, ceramic fibers, zirconia fibers, boron fibers, tungsten fibers, molybdenum fibers, steel fibers, beryllium fibers, inorganic fibers such as stainless fibers, synthetic fibers such as polyamide fibers and polyester fibers. Etc. can be used. You may use the fiber reinforcement material which processed the fiber surface beforehand in order to improve the adhesiveness with resin. These fiber reinforcing materials can be used alone or in combination of two or more kinds. The above-mentioned fiber reinforcing material can be used in the form of being processed into products such as preforms, mats, and fabrics.
You may use these individually or in the composite form which combined 2 or more types. The fiber content contained in FRP molded products is, for example, the viscosity of resin, the type and product form of fiber reinforcement and the FR
Although it can be arbitrarily selected depending on the properties desired as a P molded product, it is usually about 5 to about 80% by weight, preferably about 50 to
It is about 70% by weight.

Next, the male and female molds on which the fiber reinforcing material is placed are brought close to one of them and pressed so that the resin does not flow out from the cutting portion.

As a device for bringing the male and female molds closer to each other used in the present invention, a hydraulic press or the like which is usually used for compression molding of FRP molded products can be used. The press preferably has a position control mechanism because the male and female dies are brought close to each other until the dies have a proper gap and then stopped, and then the die clamping operation is started. The male and female molds may approach each other as long as the fiber reinforcing material is sandwiched between the male and female molds so that the resin does not flow out, and the male and female molds may completely cut through the fiber reinforcing material and engage with each other. .

After the male and female molds are brought close to each other, resin is injected through injection holes provided at appropriate positions in the mold. The injection device had an injection pressure of several kg / cm ² , for example, pumps, reaction injection molding (Reaction Injection Molding, hereinafter abbreviated as RIM)
An injection machine can be used.

As the resin to be injected into the mold, any resin used for molding a normal FRP molded product may be used, and examples thereof include unsaturated polyester resin, vinyl ester resin, epoxy resin, polyurethane resin, polyimide resin, phenol resin, silicone. It is preferable to use thermosetting resins such as resins, crosslinked polyesteramide resins, crosslinked polyamide resins, crosslinked epoxy-modified polyaminoamide resins, crosslinked polyetheramide resins. Unsaturated polyester resin is a vinyl monomer such as styrene and unsaturated alkyd obtained by polycondensation reaction of dibasic acid components such as phthalic anhydride, isophthalic acid, maleic anhydride and fumaric acid and glycol components such as ethylene glycol and propylene glycol. It is a resin obtained from and is widely used as a matrix for FRP because it has suitable physical properties and good moldability. A vinyl ester resin or an epoxy resin obtained by modifying an epoxy resin is a resin superior in physical properties such as mechanical properties and curing shrinkage to an unsaturated polyester resin.
Most of the epoxy resins used are fast-curing bisphenol A type epoxy resins. Polyurethane resin obtained by polymer reaction of polyisocyanate and polyol is a matrix having a characteristic of rapid curing. 2,
Crosslinked polyesteramide resin and 1,3-PBO obtained by the reaction of 2 '-(1,3-phenylene) bis-2-oxazoline (hereinafter abbreviated as 1,3-PBO) with a dibasic acid and a catalyst.
And crosslinked polyaminoamide resins obtained by the reaction of diamine compounds such as diaminodiphenylmethane with a catalyst and
The crosslinked epoxy-modified polyaminoamide resin obtained by the reaction of 1,3-PBO, diamine compound, epoxy resin and catalyst and the crosslinked polyetheramide resin obtained by the reaction of 1,3-PB and phenolic hydroxyl compound are A thermosetting resin suitable for the molding method according to the present invention. The resin may be used by adding a catalyst, a stabilizer, an internal release agent, a colorant, a flame retardant, a filler, etc., which meet the respective required characteristics.

The molding method according to the present invention is aimed at a molding method having high productivity, and it is preferable to use a resin which cures quickly. All components of the main agent system and the curing agent system are mixed in one tank, and the one-component method for injecting into the mold or the components of the main agent system and the curing agent system are separately mixed in two tanks, and at the time of use It is preferable to select a method suitable for the properties of each resin, such as a two-liquid method in which two liquids are mixed and injected into a mold or a three-liquid method in which three liquids are mixed and injected into a mold. Relatively low viscosity, for example 1 to obtain FRP molded parts with high fiber content
It is preferable to use a resin having a viscosity of about 500 cps or less and having a good impregnation property into the fiber reinforcing material. Fiber content is 50-80
100 to obtain a very large FRP molded product of about 10% by weight
It is preferable to use a resin having a viscosity of about 0 cps or less. Further, a resin having a very low viscosity of about 10 to 300 cps is most preferable from the viewpoint of impregnating property.

Further, for the same purpose, it is preferable to use a resin that does not cause cracks even when FRP is molded by a resin mixture whose viscosity is kept low without adding a filler.

After injecting the resin, mold clamping is performed. This operation is performed by the mold clamping device described above. When a thermoplastic resin is used as the resin, it is not particularly necessary to heat it, but when a thermosetting resin is used, it is heated. The heating temperature cannot be generally determined depending on the type of resin, but is usually about 100 to 250 ° C. The pressure is usually about 10 to 50 kg / cm ² . The time required for molding varies depending on the type and amount of resin and catalyst, the content of fiber reinforcing material, the plate thickness of the molded product, etc., but is usually about 30 seconds to 30 minutes.

 An FRP molded product is obtained by the above operation.

EFFECTS OF THE INVENTION According to the molding method of the present invention, the fiber reinforcing material is placed in advance, but since the resin is injected into the mold having a sufficient space, it is possible to inject the resin with a very small pressure. Moreover, even if a resin having a low viscosity is injected, there is no possibility that the resin will flow out of the mold. Also, the molding environment is better than the conventional mat or preform matched die molding method in terms of resin scattering and odor. In addition, since mold clamping is performed immediately after injection, not to mention molded products with a very high fiber content,
The fiber content can be arbitrarily selected.

Furthermore, since a low viscosity resin can be used as the pressurizing capacity of the press required for mold clamping, sheet molding compounds (Sheet Molding Compounds, hereinafter, SMC)
It is possible to use a press having a very small capacity as compared with a press used for compression molding such as a bulk molding compound (hereinafter referred to as BMC).

If a thermosetting resin that cures quickly is used as the resin and the resin is heat-cured as necessary, the curing time is short, and a molding method with extremely high productivity can be obtained.

Next, the present invention will be described more specifically with reference to examples.

Example 1 A tray-shaped FRP molded product using a cross-linked polyesteramide resin as a resin, glass fiber as a fiber reinforcing material, a RIM injecting machine as a resin injecting device, an up-pressing hydraulic press as a mold clamping device, and a test mold. Was molded.

(Preparation of resin and resin injection) After weighing 2,2- (1,3-phenylene) bis-2-oxazoline (hereinafter abbreviated as 1,3-PBO) 8.25 kg, paraoxybenzoic acid 1.11 kg, salicylic acid 0.64 kg Dry blended into the tank for liquid A heated to about 150 ° C in the RIM injection machine, 2.6 kg of 1,3-PBO, 1.85 kg of salicylic acid, 5.55 kg of sebacic acid,
0.75 kg of phosphorous acid was weighed, dry-blended, charged into a tank for liquid B heated to about 150 ° C. of a RIM injector, and dissolved while stirring. After melting, the liquid temperature of each of A and B is 140 ℃.
The temperature was adjusted so that The viscosity of liquid A at 140 ° C. was about 40 cps (B type viscometer), and the viscosity of liquid B was about 50 cps (B type viscometer). The discharge amounts of the respective liquids A and B were measured so that the mixing ratio of the liquid A to the liquid B was 80: 21.5. A after weighing
The combined discharge amount of the liquid and the liquid B was 123 g / sec. Discharge pressure of about 70 kg / cm ² is A liquid side, B liquid side was about 140 kg / cm ^2.

(Preparation of molds, presses, etc.) The approximate dimensions of the molded product are 40 cm long x 27 cm wide x 2 cm deep x 3 mm plate thickness. Fig. 1 is a schematic diagram of the molding equipment, and Fig. 2 is a die cutting tool. Parts are shown.

In FIG. 1, 1 is a molded product, 2 is a female mold, and 3 is a male mold.
Reference numeral 4 is an injection hole to which a mixing head of the RIM injection machine was attached and fixed. Reference numeral 5 indicates a board surface of the hydraulic press.

FIG. 2 shows the cutting portion of the mold. The travel is designed to be 5mm and the clearance is designed to be 0.1mm.

Attach the die to the board surface 5 of the up-pressing hydraulic press, and RIM
After fixing the mixing head of the injection machine at the position of the injection hole 4 of the male mold 2, the temperature of the surface of the molded product was adjusted to 200 ° C. by an electric heater embedded in the mold.

The press was lowered to open the mold, and wax was applied to the surface of the mold as a mold release agent.

(Form) Continuous Strand Mat M8609 (450g / m ² ,
After placing 8 layers of Asahi Fiber Glass Co., Ltd., the press was lifted, and when the gap D between the female mold 2 and the male mold 3 became about 2 mm, the lift of the press was once stopped (Fig. 5). ).

Operate the RIN injector for 2.2 seconds (calculated discharge rate 270g)
The resin was injected into the closed mold. Immediately after injecting the resin, the press was slowly lifted (raising speed of about 0.5 mm / sec), and the mold was clamped until it hits the spacer installed in advance. Two
After heating and pressing for 1 minute, the press is lowered and the tray-shaped FRP is
The molded product was demolded and taken out. A spacer was used to adjust the plate thickness of the molded product, but the applied pressure was about 30 kg / cm ² . The average plate thickness of the molded product was 2.84 mm. A test piece is cut out from the molded product and the physical properties are measured by the method of Japanese Industrial Standard (JIS).

Example 2 Example 1 was repeated except that 10 layers were used instead of 8 layers of the continuous strand mat M8609 of the fiber reinforcing material of Example 1. A test piece is cut out from the molded product and the physical properties are measured by the method of Japanese Industrial Standard (JIS).

Example 3 The same procedure as in Example 1 was carried out except that the fiber reinforcement having the glass fiber constitution shown below was used instead of using 8 layers of the continuous strand mat M8609 as the fiber reinforcement of Example 1. A test piece is cut out from the molded product and the physical properties are measured by the method of Japanese Industrial Standard (JIS).

Glass fiber composition: Surface layer / intermediate layer / surface layer Surface layer: Two layers of unidirectional roving cloth REW650 × -HM (manufactured by Nippon Glass Fiber Co., Ltd.) Intermediate layer: Continuous Strand Mat M8609 (450g / m ₂ ). 3 layers (Made by Asahi Faber Glass Co., Ltd.)

[Brief description of drawings]

FIG. 1 shows a schematic view of the molding apparatus used in Example 1, and FIG. 2 shows an enlarged view of the cut-away portion of the mold used in Example 1. FIG. 3 shows a modified example of a mold in which a female cutting edge has an edge, and FIGS. 4 and 5 show examples of approaching male and female molds, respectively. In the figure, 1 is a molded product, 2 is a female mold, 3 is a male mold, 4 is a resin injection hole, 5 is a board surface of a press, and 6 is a fiber reinforcing material.

Claims (1)

[Claims] 1. A structure in which the structure of the cutting portion of the molding die is a positive type male or female, and after placing the fiber reinforcing material on the mold, the male and female dies are brought close to each other so that the resin flows out from the cutting portion. A method for molding a fiber-reinforced plastic molded product, characterized in that the resin is injected from an injection hole provided at an appropriate position in the mold, and then the mold is clamped and molded.