JPS5924726A - Sheet molding compound - Google Patents

Abstract

PURPOSE:A sheet molding compound having good fluidity during molding and capable of providing uniform, high-strength FRP products, prepared by using a reinforcement containing both long and short glass fiber bundles. CONSTITUTION:A sheet molding compound (SMC) prepared by using a mat composed of 95-20wt% glass fiber bundle (8cm or longer) and 5-80wt% glass fiber bundle (1-5cm long) which are randomly oriented as a reinforcement. Although the long glass fiber is contained in the reinforcement constituting the SMC, the fluidity is extremely good, so that when water tank panels, for example, are produced from this SMC only, uniform and underfill-free FRP products can be obtained. In spite of the incorporation of the short glass fiber, it is possible to obtain FRP products of sufficient strength.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to SMC (abbreviated as SMC), which has good fluidity during molding and can produce uniform, strong FRP products.

FRP can be manufactured by impregnating a reinforcing body such as glass fiber with a liquid thermosetting resin and curing this resin-impregnated reinforcing body (referred to as uncured FRP). However, impregnating the reinforcing body with resin each time is not only cumbersome to operate and handle, but also causes variations in the proportion of glass fibers (GC) in uncured FRP, or when resin is removed during use. It is difficult to obtain a homogeneous product due to the change in viscosity.

For this reason, an SMC made by impregnating a glass fiber bundle with a liquid thermosetting resin composition containing a thickener and thickening the resin is F.
This method, which is widely used in RP molding, has the advantages of being easy to handle and operate and producing a homogeneous product, but has the following drawbacks.

Generally, when other conditions are constant, the strength of FRP tends to increase as the length of the glass fiber bundle used increases. For this reason, FRP with high strength, for example, pressure resistance of 0.
When manufacturing water tank panels with a rating of 7 Ky/crA or higher, it is necessary to use a mat made of extremely long, preferably continuous glass fiber bundles (continuous strand mat, hereinafter abbreviated as CSM). I've been However, S using CSM as reinforcement
MC has poor moldability and is prone to underfilling.

For this reason, it is not possible to industrially manufacture strong water tank panels using only SMC, and conventionally when manufacturing water tank panels using SMC, the mold surface is covered with a thin layer of C8M. Next, a predetermined thickness of 2.5 n was applied to C8M.
S using cut glass fiber bundles of approximately
The method used was to stack MC, press it with a mold that pairs with the pattern, and heat it.

When using this method, the resin in the SMC flows toward C8M due to the compression and heating of the mold. Therefore, when using this method, a panel whose surface layer is reinforced with C8M can be obtained without impregnating C8M with liquid resin in advance. When using this method, it is possible to obtain FRP with high strength, but the operation is not only more complicated than the method using only SMC, but also the distribution of the resin in the surface layer becomes uneven, and the relationship between the resin and C8M increases. There was also the problem that the adhesion was poor, and the strength of the obtained panel was not necessarily sufficient.

As a result of repeated research to solve these difficulties and to obtain an SMC that is easy to operate, homogeneous, and has high strength and is suitable for manufacturing FRP such as water tank panels, the inventors have found that randomly oriented 95 Extremely favorable results can be obtained by using ~20wt% of glass fiber bundles with a length of 8crn or more and a mat made of glass fiber bundles of 5 to 80wt% of 1 to 5crIL as reinforcement for SMC. This was discovered and proposed as the present invention.

It is not clear why such results are obtained, but
Although the reinforcing body constituting the above-mentioned SMC (hereinafter referred to as this SMC) uses long glass fiber bundles, it has extremely good fluidity, and it is possible to manufacture panels for water tanks, for example, using only SMC. However, it has been found that it is possible to obtain a homogeneous FRP product with no missing parts, etc., and that it is possible to obtain an FRP product with sufficient strength even though short glass fiber bundles are mixed in.

Next, the present invention will be explained in more detail.

In the present invention, 8 or more glass fiber bundles, preferably 1
A glass fiber bundle cut into a length of 2 to 200 cIn (hereinafter referred to as a long fiber bundle) is used. The length of the glass fiber bundle is 8c
If it is below rn, it will not be possible to move around FRP products that are sufficiently strong. By using a glass fiber bundle having a length of 12 to 20 On, it is possible to obtain an SMC with particularly excellent moldability and strength.

and 5 to 80 wt% to the long fiber bundle 95 to 20 wt%.
Glass fiber bundles (hereinafter referred to as short fiber bundles) with a length of 1 to 5 yen
A mat-like material (this mat-like material is hereinafter referred to as the present mat-like material) is prepared by mixing as uniformly as possible. The length of short fiber bundle is 1
If it is less than crn, the strength of the FRP product will decrease and it will be difficult to manufacture SMC, and if it is more than 5 cIn, it will not be possible to obtain SMC with sufficient fluidity. Further, if the amount of short fiber bundles is less than 5 inches, a sufficient effect cannot be obtained, and if the amount is more than 80 inches, an FRP product with sufficient strength cannot be obtained.

The glass fiber bundle is suitably a bundle of about 50 to 400 glass fibers each having a diameter of 6 to 15 .mu. and bundled with a binding agent. Using this mat-like material, SMC is manufactured, for example, by the following method.

Liquid thermosetting resin containing a thickener, preferably an unsaturated polyester resin composition (usually 8 parts by weight per 100 parts by weight of resin)
0 to 150 parts by weight of filler, 3 to 8 parts by weight of toner (
pigment composition), 0.8 to 1.5 parts by weight of polymerization initiator, 4
~7 parts by weight of mold release agent.

0.3 to 1.0 parts by weight of a thickener is added and mixed uniformly (hereinafter simply referred to as a resin composition), and a predetermined amount of the mixture is continuously applied onto a long synthetic resin film, and A long glass fiber bundle and a short glass fiber bundle are dropped so that they are mixed as uniformly as possible, covered with another synthetic resin film, and compressed with a roll or the like to impregnate the glass fiber bundle with the resin composition. The resin composition is rolled up and cured to thicken the resin composition to form SMC.

The ratio of the resin composition to 100 parts by weight of the glass fiber bundle is 1
It is appropriate that the amount is 00 to 300 parts by weight, and the thickness of SMC (weight per unit area) is 2 to 5 Ky/c!
It is appropriate to set it to about 1.

Next, use the above-mentioned SMC (this SMC) to create an FRP
The manufacturing method will be explained using an example of manufacturing a box-shaped water tank panel having a rectangular main surface 1 and a flange surface 2 as shown in FIG. 1.2.

This SMC is cut to approximately the same size as the top surface of the J41: mold, and a predetermined number of sheets are stacked on the top surface of the 741i mold. The size of the present SMC is large enough to almost cover the top surface of the mold, and there is no need to bend the present SMC to cover the side surface of the male mold corresponding to the flange portion. When the SMC is pressed and heated with a box-shaped female mold paired with the pattern mold, the SMC flows to the sides of the male mold, making it possible to obtain a uniform, high-strength water tank panel.

As described above, when using the method of the present invention, homogeneous, high-strength FRP products such as panels for water tanks can be manufactured with simple operations, and the present invention is industrially useful.

Next, examples of the present invention will be shown.

Example 100 parts by weight of liquid unsaturated polyester resin, 05 parts by weight of magnesium oxide (thickener), 10 parts by weight of calcium carbonate
0 parts by weight, orbutyl perbenzoate (polymerization initiator)
1 part by weight3. A resin composition consisting of a homogeneous mixture of 3 parts by weight of toner and 5 parts by weight of zinc stearate (mold release agent),
Coated on a synthetic resin film at a rate of 2.5Kp/-,
On top of this, glass fibers with a diameter of 13 μm were added with a vinyl acetate-based sizing agent, and 100 glass fiber bundles were cut into a length of 20 c1n at 800 gr/n? , length 2cm
Similar glass fiber bundles were uniformly dropped at a rate of 200 g r / m', another synthetic resin film was layered on top of this, and the resin composition was thickened according to a conventional method, so that the glass fiber bundles became non-directional. SMCs distributed in the following manner were obtained. This SMC is 93α
Cut the pieces to a size of
0ms average thickness 4.5 m, flange height 7.5
A panel as shown in FIG. 1.2 with a thickness of 8 mm was manufactured.

The hydraulic strength of this panel is 7.5 Ky/cr
It was l.

On the other hand, the sides of the male mold were covered with 300 gr/- C8M, and on top of this, four sheets of SMC reinforced with 2.9 to 9/- glass fiber bundles of 2.5 cTn were stacked and molded in the same way. The compressive strength of the panel obtained was Q, 7 Ky/CJ.

The sides of the male mold were covered with 450 g r/m'' C8M, and this C8M was coated with 100 parts by weight of unsaturated polyester resin, 0.5 parts by weight of magnesium oxide, and 1-calcium carbonate.
-100 parts by weight # A resin composition consisting of 1 part by weight of butyl perbenzoate, 3 parts by weight of toner and 5 parts by weight of zinc stearate was impregnated at a ratio of 3.9 K/m, and molded in the same manner. The resulting panel had a water pressure strength of 0.76 K5+/ca.

” - As mentioned above, the SMC of the present invention has good fluidity and is industrially useful because it can be used to form homogeneous FRP products with high strength. However, the present invention is limited to the above description and examples. However, changes may be made as appropriate without departing from the purpose and spirit of the present invention. For example, the SMC of the present invention can be used to manufacture automobile parts and the like.

Furthermore, when manufacturing the present mat-like product, long glass fiber bundles and short glass fiber bundles can be supplied alternately to form a sandwich-like product.

[Brief explanation of drawings]

FIG. 1 is a plan view of an FRP product manufactured using the sheet molding compound of the present invention, and FIG. 2 is a front view.

Claims (1)

[Claims] Randomly oriented glass fiber bundle 9 with length f3cm or more
5-20wt% and 1-5cm glass fiber bundle 5-80w
A sheet molding compound characterized by using a mat consisting of t% as a reinforcing body.