JPS5838300B2 - Molding method for fiber reinforced plastics - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a sheet molding compound (hereinafter referred to as S
Fiber-reinforced plastic (hereinafter referred to as FRP)
Regarding the precept method (hereinafter referred to as "string-like MC"), it is intended to obtain a patterned F'RP molded product by layering a string-like molding compound (hereinafter referred to as "string-like MC") with SMC and molding it under heat and pressure. be.

SMC focuses on bathtubs, washstands, and other housing-related products.
FRP molding by the method is widely practiced.

In other words, reinforcing fibers such as glass fibers spread in a sheet form are impregnated with a thermosetting resin compound such as unsaturated polyester resin, and the resulting SMC is heated and pressurized by aging it at a temperature of about 40'C for several days. It has the characteristic of simplifying the molding process and making it suitable for mass production.

However, according to this SMC method, conventionally only single-colored molded products have been manufactured using a single-colored resin compound.

However, such products with a single color or shape have a monotonous appearance and lack aesthetic appeal.

Therefore, there is a problem of being bored.

This lack of aesthetic elements needs to be resolved in some way, considering that the main use of FRP shaped products is as interior decoration products for housing.

As one such attempt, a method has been proposed in which two or more types of SMC of different colors are layered and molded under heat and pressure.

However, in order to obtain a patterned F'RP molded product desirably similar to natural dog-buried stone using this method, complicated processing of SMC is required, and it is difficult to control the flow of SMC during heating and pressurization. It has some drawbacks that make it extremely difficult.

Furthermore, since the reinforcing fibers filled between different SMCs tend to become discontinuous, there remains a problem in the degree of reinforcement of the resulting FRP molded product.

On the other hand, a method of coloring the surface of SMC by impregnating a reinforcing fiber such as glass fiber, which has been formed into a sheet shape with a roll, with a resin compound and dropping a resin compound containing a colorant onto the impregnated fiber sheet. has also been proposed.

This method has the advantage of being suitable for mass production and does not cause deterioration in the strength of the FRP molded product, but has the disadvantage that the pattern colored part and the base resin part inevitably spread, resulting in a blurred pattern. There is.

Although it also depends on the method of dropping the colorant, the formation of the pattern is often controlled by chance, and those with a defective appearance have a significantly lower commercial value, and furthermore, the resulting pattern is flat, It has some drawbacks, such as a lack of depth.

The present invention provides an FRP molding method that eliminates the drawbacks of the conventional patterned FRP molding method using the SMC method as described above.

The present inventor discovered that natural stone-like patterns, which are representative of desirable patterns for FRP molded products, are often of the type with band-like stripes running through the ground color of the stone, and that the stripes are similar to those of stones. Note that although it flows into the ground color, it is not diffused and the boundaries are blurred.
Worked on manufacturing RP molded products.

Therefore, another object of the present invention is to provide a method for producing an FRP molded product having an appearance similar to natural dog-earth stone.

Such a purpose is characterized in that a string-like MC made by impregnating a string-like fiber bundle with a resin compound and ripening is layered with an SMC of a different color from the string-like MC and then heated and press-molded.
This is achieved by the FRP molding method of this invention.

This invention will be explained in more detail below.

The numerical values cited in the description indicate preferred embodiments of the invention, and do not indicate that values outside the range may not be used.

Those skilled in the art will be able to make numerical modifications without departing from the spirit of the invention.

A preferred example of the thermosetting resin as a raw material for the SMC and string-like MC used in this invention is an unsaturated polyester resin.

Here, the term "unsaturated polyester resin" refers to unsaturated alkyd resins, that is, maleic acid, fumaric acid, mesaconic acid, itaconic acid, or their anhydrides alone, which have ethylenic double bonds, or phthalic acid, etc. A product obtained by adding a saturated dibasic acid and esterifying it with a glycol such as ethylene glycol, propylene glycol, or butanediol; a substantially uncrosslinked prepolymer of a saturated or unsaturated dibasic acid such as diallyl phthalate and an unsaturated alcohol. (so-called β-polymer); and polyesters selected from mixtures thereof dissolved in a reactive monomer having an ethylenically unsaturated bond and, if necessary, a polymerization inhibitor added thereto.

The preferred acid value of polyester is 20 to 60, and the molecular weight is 1.
It is about 000 to 3000.

As the reactive monomer for dissolving these unsaturated polyesters, styrene, divinylbenzene, vinyltoluene, vinyl acetate, diallyl phthalate, etc. are used in a weight ratio of about 3:1 to 1:3 to the unsaturated polyester.

Up to 1 part of quinones, phenols,
The pot life is adjusted by adding a known polymerization inhibitor such as grade ammonium salt.

If necessary, a thickening agent selected from metals such as magnesium oxide, magnesium hydroxide, calcium oxide, and lithium oxide, preferably oxides or hydroxides of alkali metals, is added to the obtained unsaturated polyester resin. 0-1
5 parts; t-butyl perbennoate, cumene hydroperoxide, lauroyl peroxide, methyl isobutyl ketone peroxide, t-butyl peroctoate + co or Ca, taking into consideration the molding temperature and pot life.
About 0 to 5 parts of a curing agent such as an accelerator; O to 40 parts of a low-shrinkage additive selected from thermoplastic polymers such as polystyrene and polymethyl methacrylate, preferably dispersed or soluble in the above-mentioned reactive monomers. ; A coloring agent consisting of a dye or L-pigment, the type and amount of which corresponds to the required color tone;
O to 5 parts of an internal mold release agent such as zinc stearate; and O to 5 parts of a surface improving agent such as finely powdered polyethylene may be added.

A resin compound obtained by mixing the above-mentioned various raw materials by a conventional mixing method is impregnated in cloth-shaped or pine-shaped glass fibers, or reinforcing fibers are kneaded with the resin compound to form a sheet. SMC can be obtained by aging at about 40°C for about 1 to 3 days, and string-like MC can be obtained by impregnating reinforcing string-like fiber bundles and aging at about 40°C for about 2 to 5 days.

By keeping the maturity of the string-like MC higher than that of SMC, it is possible to obtain an FRP molded product with a pattern that is more similar to a large buried stone without blurring.

As the reinforcing fibers, various natural, temperature-treated, organic or inorganic fibers can be used, but glass fibers are most preferably used.

As the glass fiber for SMC, one having a diameter of 10 to 15 μm and a length of about 2 to 5 m is used in an amount of about 20 to 30 parts.

In addition, as a glass string-like fiber bundle for obtaining string-like MC, 10 unit filaments 1 with a diameter of about 10 to 15 μm are used.
Approximately 0 to 400 pieces are used, and the length thereof is preferably about 30 CrIL to 2 m.

The amount added is about 135 to 8.4 parts. Although something similar to string-like MC can be obtained by cutting SMC obtained by impregnating a mat-like fiber reinforcing agent into narrow widths, this is not suitable as the string-like MC of the present invention.

In other words, when this is layered with SMC and heated and pressure molded,
This is because the resin flow in a certain shape causes dispersion of the fibers, which does not give a desirable string-like pattern.

On the other hand, the string-like MC obtained by impregnating a reinforcing string-like fiber bundle with a resin compound as described above undergoes dispersion and flow in the width direction during molding, but the continuity of the internal strands does not improve. Therefore, no essential change occurs in the length direction.

However, bending occurs during molding. In addition to the above-mentioned reinforcing fibers, the above-mentioned resin compounds that provide SMC and string-like MC include aluminum hydroxide, calcium carbonate, alumina, stone powder, FRP waste, and silica sand, while taking into consideration strength and aesthetics. It is possible to add fillers such as.

As a result, for example, if calcium carbonate with strong hiding power is used, an opaque resin compound, and therefore an opaque SMC or string-like MC can be obtained.

The amount of fillers other than reinforcing fibers is such that the sum of the amount of fillers and reinforcing fibers is 300
Used within a range not exceeding 100%.

Production examples of the above-mentioned SMC and string-like MC are listed in Table 1 and Table 2, respectively.

Any combination of the three examples of SMC and string-like MC shown in the table is possible.

Using the SMC obtained in this way and the string-like MC, F
The procedure for obtaining an RP molded product will be described.

FIGS. 1 and 2 are diagrams for explaining an example of manufacturing a bathtub according to the present invention, in which a is a front cross-sectional view of a mold for a precept, and b is a plan view, respectively.

First, as shown in FIGS. 1a and 1b, a string-shaped MC2 is placed on the convex mold 1 of a molding die according to a desired design.

The actual mounting condition is clearly shown in FIG. 1b.

At the next step L, place the SMC3 on the string-like MC2 as shown in FIG.
By pressure molding, an FRP molded product according to the present invention can be obtained.

An example of molding conditions is a convex mold temperature of 145°C and a concave mold temperature of 135°C.
℃, molding pressure 6001-ton (approximately 100'K)
t;j/ca), and the pressurization time was 3 minutes.

These conditions are suitable for molding the combination of the above-mentioned SMC and string-like MC.

The part A shown in FIG. 2b is filled by the flow of SMC during molding, but it is of course possible to stick SMC from the beginning.

Reference photos A and B are photos showing the state corresponding to FIG. F, which clearly shows the dog-buried stone pattern.
It will be understood that RP or shaped products can be obtained.

Note that the above example shows an example in which a pattern is actively created on the inner surface, which is the main surface of the bathtub product, but when using transparent or translucent SMC, in the above example, it is necessary to place a string-like MC and SMC. Patterned FRP with a more three-dimensional effect can be created by changing the placement order, or by further stacking a string-like MC after placing the SMC in the above example, or by stacking multiple SMCs and interposing a string-like MC in each layer. A certain shaped product is obtained.

As can be understood from the above, according to the FRP molding method of the present invention, a desired patterned F'RP molded product can be easily obtained by combining SMC and string-like MC, and the pattern obtained is similar to that of strings. The pattern rises and falls as it flows, reproducing a dog-earth stone-like appearance, and there is no blurring or blurring in the pattern as seen in conventional methods.

Furthermore, the materials SMC and string-shaped MC both have good storage stability, and the manufacturing of the resin material and the molding factory are completely separated.
It has the advantage that arbitrary patterning can be easily done in a certain factory that is more sensitive to the demands of customers, and moreover, it can be done using conventional equipment as is.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams of the steps of the FRP preforming method of the present invention, and subscripts a and b represent a front sectional view and a plan view, respectively. 1... Convex type, 2... String-like MC, 3.
...SMC, 4...Concave type.

Claims (1)

[Scope of Claims] 1. A string-like molding compound obtained by impregnating a fiber strand with a resin compound and thermally forming it is layered with a sheet molding compound of a different color from the string-like molding compound, and then heated and pressure-molded. A method for molding fiber-reinforced plastics. 2. The method of item 1 above, using a string molding compound with a higher degree of maturity than a sheet molding compound.