JPH03187726A - Fiber-reinforced resin molded item and preparation thereof - Google Patents

Abstract

PURPOSE:To obtain a fiber-reinforced resin molding with high rigidity and excellent surface smoothness by using an elastic body which is not impregnated with a matrix resin as a core material and placing a fiber-reinforced resin composite around it. CONSTITUTION:An elastic body 1 which is not impregnated with a matrix resin and a fiber reinforcing material 2 placing around it so as to be brought into contact with the elastic body 1 are placed in a mold and the mold is closed and the matrix resin is fed while the elastic body is compressed to cure by heating. As the elastic body 1, a foam, a rubbery body, a non-woven fabric, a mat, etc., can be cited. The fiber- reinforced resin 2 is a resin reinforced with a fiber, which is e.g. a glass fiber, a carbon fiber, an alumina fiber, a boron fiber, a silicon fiber etc. The matrix resin is a thermo plastic resin which is moldable by means of a reaction injection molding machine, a thermosetting resin or a resin combined therewith. It is possible to press the surface of a molding on the surface of a mold cavity until curing is completed by pressing the surface of the molding with a mold from the beginning of feeding to the completion of curing and it is possible thereby to prevent the surface smoothness from decreasing caused by the shrinkage of the resin.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a fiber-reinforced resin molded article and a method for producing the same, and more specifically, a fiber-reinforced resin molded article with high rigidity and excellent surface smoothness. The present invention relates to bodies and methods for producing the same.

(Prior Art) In recent years, fiber-reinforced resin molded bodies have been used for automobile outer panels and the like, and their rigidity and surface smoothness have become important. In particular, surface smoothness is important not only in the automobile field but also in maintaining the aesthetic appearance of products.

Generally, after placing the fiber reinforcement in the mold and closing the mold,
In a fiber-reinforced resin molded article manufactured by injecting and curing resin, the surface of the mold cavity is not directly transferred to the surface thereof. This is because the resin shrinks during curing and the glass fibers come to stand out on the surface, and the surface smoothness in this case cannot be said to be very good.

Here, shrinkage includes curing shrinkage and heat shrinkage.

As methods for improving the surface smoothness of such fiber-reinforced resins, improvements in resins, improvements in manufacturing methods, secondary processing, etc. are known.

(Problem to be solved by the invention) However, the first method is to modify the resin to reduce its shrinkage rate, and examples include chemical modification and physical modification (addition of fillers, etc.). However, there is a limit to the degree of improvement in surface smoothness.・Also, the second method includes gel coating method, in-mold coating method, pressure gelling method, etc.
The manufacturing method is complicated and cannot be said to be advantageous. There is also a method of suppressing shrinkage using the pressure of gas dissolved in the resin, but it is difficult to control the conditions and cannot be said to be advantageous.

Furthermore, a third method is to apply a coating onto the molded body, but this method is expensive and cannot be said to be advantageous.

(Means for Solving the Problems) In view of the above circumstances, the inventors of the present invention have made extensive studies and found that an elastic body that is not substantially impregnated with matrix resin is used as a core material, and a fiber-reinforced resin composite is used around it. It was discovered that the problem of overcasting could be solved by arranging the materials, and the present invention was completed.

That is, an object of the present invention is to provide a fiber-reinforced resin molded article having high rigidity and excellent surface smoothness, and a method for producing the same.

The purpose is to: (1) use an elastic body in a compressed state that is not substantially impregnated with matrix resin as a core material, fiber reinforcement material arranged around it, and matrix resin impregnated in the fiber reinforcement material; A fiber-reinforced resin molded article comprising:

and (2) an elastic body that is not substantially impregnated with matrix resin;
A fiber reinforced material placed around the elastic body in contact with the elastic body is placed in a mold, and after the mold is closed, a matrix resin is injected and heated to harden the elastic body while keeping it compressed. A method for producing a characteristic fiber-reinforced resin molded article.

easily achieved.

The present invention will be explained in more detail below.

The elastic body referred to in the present invention includes anything that has elasticity, and specifically includes foam, rubber-like bodies, nonwoven fabrics, mats, etc. It has the function of pressing the adjacent fiber reinforcement material against the mold cavity surface. Note that the above-mentioned adjacency includes a state in which pressure for pressing the fiber reinforcement material against the mold cavity surface can be transmitted even if there is no direct contact and an intermediate layer is present. When a foam or the like is used as the elastic body, impregnation of the resin into the foam causes a decrease in elasticity, so it is preferable not to impregnate the foam. Impregnation may be prevented by a surface skin layer or an intermediate layer that transmits pressure. The compressive force of the elastic body must be at least enough to press the fiber reinforcement placed around it against the surface of the mold, and must also be lower than the mold clamping pressure to prevent the mold from opening. , specifically 0.05 to 20 kg
f/cm', preferably 0.1 to 10 kgf/am2.

The compression ratio is not particularly limited as long as the compression force does not become smaller than the above range due to curing shrinkage.

The fiber-reinforced resin referred to in the present invention is a resin reinforced with fibers, and the fibers are made of materials selected from inorganic and organic materials, such as glass fibers, carbon fibers, alumina fibers, boron fibers, silicon fibers, Examples include aromatic polyamide fibers and polyester fibers. Although the length of the fiber is not limited, the longer the fiber is, the more preferable it is in order to increase the mechanical strength.

The form of the fiber reinforcement material is preferably a mat, a woven fabric, or a combination thereof.

The matrix resin referred to in the present invention is a thermoplastic resin, a thermosetting resin, or a combination thereof that can be molded by a reaction injection molding machine. These resins are injected into the mold in the form of liquid resin raw materials. The liquid resin raw material is a two-component or three-component material that is a raw material for the resin, and can be hardened by impact-mixing these materials. The viscosity of the resin raw material depends on the mold temperature and mixing ratio, but the lower it is at the time of injection after mixing, the better.
It is preferably 0 cp or less. It is preferable that the curing speed is slow when filling the mold, and that it hardens quickly after filling is completed.

Specifically, the curing time is 10 minutes or less, preferably 5 minutes.
The time is preferably 3 minutes or less, more preferably 3 minutes or less. Examples of the resin of the present invention include thermosetting resins such as epoxy, vinyl ester, unsaturated polyester, phenol, bismaleimide, urethane, polyurea, and polyisocyanurate, and thermoplastic resins such as polyamide and polycarbonate. Also included are thermosetting resins polymerized from norbornene type polymerizable monomers, and monomers and oligomers having allyl, vinyl, acrylic, and methacrylic type carbon-carbon double bonds. Additives such as a reactive diluent, a catalyst, and an internal mold release agent may be appropriately added to these resins.

As for the structure of the molded body, it is preferable that at least a portion of the fiber reinforcement material surrounds the periphery. In other words, the dimensions of the elastic body are made smaller than the dimensions of the fiber reinforced material, and at least a portion of the upper and lower fiber reinforced materials in at least part of the outer periphery of the elastic body are made sufficient or larger than the dimensions of the fiber reinforced material to restrain mutual shear deformation. It is preferable that they be integrally molded to have a strength of . An example of such a molded body structure is the form shown in FIG. 1. In Figure 1, 1 is an elastic body, 2, 2
' is a fiber reinforced material impregnated with matrix resin.

This restricts mutually independent movement of the fiber reinforced resins on both sides, making it possible to form a strong sandwich structure. If the fiber reinforcement materials on both sides are not restrained or the strength of the restrained parts is insufficient, after molding,
This is undesirable because the elastic body swells and the plate thickness increases, or when a load is applied, shear failure occurs in the elastic body.

Next, a method for manufacturing the fiber-reinforced resin molded article of the present invention will be explained.

The mold may be made of metal or resin.

The surface of the mold cavity is preferably finished smooth by polishing or the like. This is important in improving the surface smoothness of the molded article according to the method of the present invention, and is also important in improving the mold releasability during molding.

Inside the mold, an elastic body is used as a core material, and a predetermined amount of fiber reinforcing material is placed around it at a predetermined position. The fiber reinforcing material may be placed by laminating one or more mats or only woven fabrics, or may be placed by combining these as appropriate.

After this, the mold is closed and the liquid resin raw material is injected.

The liquid resin raw material is selected from the above thermosetting resins, thermoplastic resins, additives, and combinations thereof. The injection method is a conventional reaction injection molding method, and operating conditions such as temperature and pressure are determined as appropriate depending on the properties of the individual resin, the required performance of the molded product, etc. The injection amount is determined by the volume of the molded body to be molded, the volume of the elastic body, the fiber content, etc. Here, it is important that the elastic body does not substantially contain resin. This is because as the resin in the elastic body hardens, it ceases to function as an elastic body.

Once the injection is complete, the resin is cured in a sealed mold under predetermined temperature conditions. Once curing is complete, the mold is opened at a temperature below the glass transition temperature of the resin and the molded product is taken out. If the temperature is higher than the glass transition temperature of the resin, the molded article may be deformed due to the repulsive force of the elastic body, which is not preferable.

By sandwiching the elastic body, it is possible to press the surface of the molded article against the mold cavity surface until the end of curing, and it is possible to prevent a decrease in surface smoothness due to resin contraction. In this case, it is necessary to pressurize the surface of the molded body with a mold from the start of injection to the completion of curing, and care must be taken to ensure that the resin does not become unable to be pressurized due to shrinkage or the like. Furthermore, since the shape of the mold cavity is directly transferred to the surface of the molded product, it goes without saying that the cavity must have good surface properties. Furthermore, since the fiber reinforced resin layers on both sides are restrained at least in part to prevent shearing, high bending rigidity can be exhibited.

(Example) Example 1 The size of the board surface is 300 mm in length and 300 mm in width.
A metal one with a cavity depth of 3 mm was used. The surface of the mold cavity was polished to #600. The temperature of the mold was maintained at 120°C. As a resin raw material, bisphenol A type diglycidyl ether (hereinafter referred to as A
) and isophoronediamine (hereinafter abbreviated as B) were used. The fibers are glass fiber mats with a length of 295 mm and a width of 295 mm and a basis weight of 450 g/m', the same < 1.
A 58 g/m2 glass fiber fabric was used. As the elastic body, a hard urethane foam (with a skin layer on the surface) with a length of 250 mm, a width of 250 mm, and a thickness of 1.5 mm was used.

Inside the mold, with the elastic body as a core material, each sheet of the glass mat is placed on both sides, and each sheet of the glass fabric is stacked on both sides thereof. did. After this, the mold is closed and the weight ratio of the resin raw material is B/A =
It was injected into a mold using a reaction injection molding machine so that the ratio was 27/100. After 10 minutes, the mold was cooled, and when the temperature reached room temperature, the mold was opened and the molded product was taken out.

The thickness of the sandwich structure of the obtained molded body was 3 mm, and the surface smoothness was as good as the polished finish of the mold cavity. The surface shape of the molded body was measured using a stylus-type surface roughness meter ("5urfcor" manufactured by Koita Research Institute).
der SE-3F'') and shown in FIG.

Comparative Example 1 A fiber-reinforced resin molded body was produced in the same manner as in Example except that the depth of the mold cavity was 2 mm and no elastic body was used.

The thickness of the obtained molded body was 1.8 mm, and traces of the glass fiber used as a reinforcing material were observed to be raised on the resin layer on the surface. The surface shape was measured under the same conditions as in Example 1 and is shown in FIG.

(Effects of the Invention) According to the present invention, a molded article having extremely good rigidity and surface smoothness can be easily obtained.

[Brief explanation of drawings]

FIG. 1 shows an example of a molded article using the present invention, and FIG.
FIG. 3 shows the surface shape of the molded product obtained in Example 1 of the present invention, and FIG. 3 shows the surface shape of the molded product obtained in Comparative Example 1. 1: Elastic body

Claims (2)

[Claims] (1) It is characterized by being composed of an elastic body in a compressed state that is not substantially impregnated with matrix resin as a core material, a fiber reinforced material arranged around the core material, and a matrix resin impregnated in the fiber reinforced material. Fiber-reinforced resin molded body. (2) an elastic body that is not substantially impregnated with matrix resin;
A fiber reinforced material placed around the elastic body in contact with the elastic body is placed in a mold, and after the mold is closed, a matrix resin is injected and heated to harden the elastic body while keeping it compressed. A method for producing a characteristic fiber-reinforced resin molded article.