JPS62288011A - Manufacture of fiber reinforced resin molding - Google Patents

Abstract

PURPOSE:To obtain a molding, in which fibers are dispersed uniformly, by a method wherein fiber bundle pellets, obtained by bundling organic or inorganic fibers, setting them by binding agent and cutting the bundle of the fibers, are mixed with resin pellets while these pellets are molten upon molding mixed pellets to disperse the fibers thereinto. CONSTITUTION:Organic or inorganic fibers 1 are bundled and, subsequently, the bundle of the fibers are set and formed by binding agent 2, which is molten by heat or solvent, so as to have preferably a diameter corresponding to the same of a resin pellet to be mixed with it while producing the continuous bundle of fibers, thereafter, the bundle is cut so as to have a proper length whereby a fiber bundle pellet 3 is obtained. The diameter of the fiber bundle pellet 3 is preferable to be 1.5-6 mm and the length of the same is preferable to be 1.5-6 mm. The resin pellets 4 are mixed with the fiber bundle pellets 3 and a molded form is obtained. In this case or prior to this molding, the binding agent, binding the fiber bundle pellet, is molten or dissolved and the fibers in the fiber bundle pellet are dispersed into resin as a single fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for manufacturing a fiber-reinforced resin molded article in which strong fibers are almost uniformly dispersed.

<Conventional technology> FRP (hereinafter referred to as FRTP) has traditionally been a resin molded product using short or long glass fibers as reinforcement materials.
In recent years, with the diversification of FRP applications, fibers other than glass fibers, such as organic fibers with excellent properties such as high strength, high elongation, high elastic modulus, and light weight, and conductive carbon fibers, are being used as reinforcing materials. The number of items used is increasing.

The improvement in physical properties of FRP using organic fiber as a reinforcing material compared to FRP using glass fiber as a reinforcing material will be explained based on experimental values in the case of vinylon fiber. The impact resistance is more than 5 times, the abrasion resistance is more than 8 times that of a grindstone, and the specific gravity is 1/2, making it lightweight.
Regarding alkali resistance, glass cannot withstand use in alkali, whereas Sibinyron has high alkali resistance.

In this way, each organic fiber group. It is well known that FRP is used in place of glass or in combination with glass due to its characteristics.

<Problems to be solved by the invention> However, although each organic fiber has excellent properties not found in glass fiber, its use is currently limited to batch system processing such as BMC and hand layup. It is only used in the molding method, and is not used in the molding method of molding resin pellets. This is due to the following reasons.

In other words, in the batch processing method, when resin pellets and fibers are mixed in a mixer, the diameter of the pellets is about 3 sam, whereas the diameter of the single fibers is about 0.015 m, and there is a large difference in the shape of the two. Because of this, the fibers tend to be unevenly distributed during stirring, making it difficult to uniformly disperse the fibers.

Means for Solving the Problems> The present inventors conducted research to solve the above problems, and as a result, they arrived at the present invention.

That is, the present invention focuses organic fibers or inorganic fibers,
The fiber bundle pellets obtained by solidifying with a binder and cutting the fiber bundles are mixed with resin pellets, and the binder is dissolved or melted to disperse the fibers when or prior to molding the mixed pellets. This is a method for producing a fiber-reinforced resin molded article.

Various resins for FRP are usually in the form of pellets with a diameter of 2 to 4 mm and a length of 2 to 3 mm, and are extremely fluid in the pellet form.

~31 The present inventors have also found that in order to mix fibers particularly uniformly into resin pellets having such a shape, it is sufficient to make the fiber bundle pellets approximately the same size as the resin pellets.

In other words, pellets of approximately the same size (resin pellets and fiber bundle pellets) are first mixed uniformly, and then the fiber bundle pellets are melted with heat or a solvent and dispersed into single fibers. Even if it is a batch molding method,
Alternatively, even if a continuous molding method is used, a molded product with very uniform dispersion can be obtained.

The basic method for producing fiber bundle pellets will be described below.

First, organic or inorganic fibers are bundled, and then the bundle is solidified and formed into a continuous fiber bundle using a binder that dissolves with heat or a solvent, preferably to a thickness corresponding to the diameter of the resin pellets to be mixed. make.

Then, fiber bundle pellets are obtained by cutting it into a suitable length, preferably a length corresponding to the length of the resin pellet.

The size of the fiber bundle pellet is 0.5 to 10 in diameter.
A cylindrical shape with a diameter/length of 0.05 to 5.0 is preferable, but as mentioned above, a cylindrical shape having a diameter/length of 0.05 to 5.0 is particularly preferable, and from this point of view, a diameter of 1.5 m is preferable. ~6 wax and a length of 1.5 to 6 wm are more preferred. The shape of the fiber bundle pellet is preferably cylindrical as described above, but other shapes such as an oval or rectangular cross-sectional shape may also be used. When the cross-sectional shape is other than a circle, it is preferable that the size of the cross-sectional shape is converted into a circle with the same area and its diameter falls within the above range.

The fiber bundle pellet may be in a form in which the entire bundled fibers are impregnated with a binder and solidified, or in a form in which the outer surface of the fiber bundle is coated with a film of a binder. In order to easily separate the fibers into single fibers in the resin, it is preferable that the amount of the binder attached is as small as possible, but it is necessary that the shape does not collapse during cutting.

Figure 1 shows the bundled fibers impregnated with a binder and solidified, and Figure 2 shows the outer surface of the fiber bundle coated with a film of the binder. ing. In these figures, 1 indicates a single fiber, 2 a binder, and 3 a fiber bundle pellet obtained thereby. Further, FIG. 3 shows a mixture of fiber bundle pellets and resin pellets, and in the figure, 3 is a fiber bundle pellet and 4 is a resin pellet. As is clear from this figure, in the present invention, it is preferable that the resin pellet and the fiber bundle pellet have approximately the same size.

Ideally, the binder for solidifying the fiber bundle should be one that has affinity with the resin constituting the molded body. For example, for unsaturated polyester resins, vinyl acetate and polystyrene-based resins that are easily soluble in styrene are effective, and for epoxy resins, epoxy-modified vinyl acetate-based resins are effective. In the case of FRTPO, it is reasonable to use an acrylic ester type for acrylic resin, a polypropylene type for polypropylene resin, and a polyethylene type for polyethylene resin. However, depending on the purpose of the molded product, the material is not limited to this, and any material currently used as a binding material for glass fibers may be used.

As long as the fibers used as the reinforcing material have a fiber shape, they can be processed into fiber bundle pellets.

Preferably, the fiber thickness is 30 μm or less, and organic fibers include cellulose, polyamide, polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, polyester, polyacrylonitrile, polyethylene, and polypropylene. As the inorganic fibers, glass fibers, ceramic fibers, metal fibers, etc. can be used. Furthermore, it is also possible to use fibers obtained by copolymerizing, modifying, and compositing the above fibers.Of course, the fibers specifically used are subject to decomposition, dissolution, and melting under the pellet molding conditions and the subsequent molding conditions. It is necessary that the material does not lose the physical properties required as a reinforcing fiber.

The fiber bundle pellets thus obtained are mixed with resin pellets. The mixing ratio is determined based on the required strength of the molded product, so it cannot be generalized. That is, if it is desired to obtain a molded product with better strength, the proportion of the fiber bundle pellets may be increased, and conversely, if particularly high strength is not required, a small amount may be added.

A molded product is obtained from the resin pellets after mixing the fiber bundle pellets by a normal molding method. At this time or prior to this molding, the binder binding the fiber bundle pellets is dissolved or melted, and the fiber bundle pellets are dispersed into single fibers in the resin.

As mentioned above, the method of the present invention has the great advantage of being able to uniformly disperse reinforcing fibers, but in addition to this, the method of the present invention also has the advantage that the fiber bundle pellets are quantitatively separated into resin pellets and liquid phase using a vibrating feeder or the like. It also has the advantage of being able to be continuously supplied into the resin matrix.

The present invention will be explained below with reference to Examples.

Example 1 A continuous multifilament yarn of 1,200 denier each consisting of 200 single 6-denier vinylon fibers was wound onto a bobbin, and 30 bobbins were hung on a bobbin stand and the yarn was pulled out from each bobbin. The 30 yarns were combined to make a bundled yarn with a total of 36,000 deniers, which was led into a polyvinyl acetate resin bath to be impregnated with polyvinyl acetate. ．．
A hole of 0 mm diameter was drilled and the board was fixed with a die. ) through the thickness 3. A continuous fiber bundle molded product of OWφ was obtained. After drying, the fiber bundle was cut into 3.5% pieces using an automatic cutter to produce fiber bundle pellets. The weight ratio of polyvinyl acetate resin to fiber was 41:49.

The fiber bundle thus obtained was molded under the following conditions to produce a resin plate.

Polyethylene resin (diameter 2.5 wg, length 3.5 m
80 parts of the cylindrical pellets) and 20 parts of the fiber bundle pellets were mixed, stirred, and then put into a hopper using a roll press method at a temperature of 165° C. and a pressure of 10 kf/aA.

Cool for 20 minutes with a water-cooled roll to a finished thickness of 2.3%.
A FRTP board was produced. As a control, a single 6-denier vinylon fiber cut into a 3.5-mm diameter was put into a hopper as it was, kneaded with the polyethylene resin, and an FRTP board with a thickness of 2.5-mm was prepared under the same conditions as above. . - The measured physical properties were as shown in Table-1.

Table-1 Example 2 1 whose constituent unit is 48 single fibers of 3.2 denier
50 denier polyester multifilament
This continuous bundled yarn is made into a bundled yarn, and this continuous bundled yarn is dipiped into molten polyethylene resin (L-2340 manufactured by Asahi Kasei Industries).
ng to obtain a bundled yarn molded product. The diameter of this molding is 4
．． 3%, and the weight ratio of resin to fiber was 32:68.

This continuous bundled yarn molded product was cut into three lengths to produce fiber bundle pellets.

30 parts of the fiber bundle thus obtained and 70 parts of polyamide resin (cylindrical pellets of thickness 2.5 x length 3.0 - manufactured by Amilan Toshi) were stirred and mixed, and the mixture was molded using a press molding machine at a temperature of 227°C. A fiber-reinforced resin plate with a thickness of 3.2 m was obtained by molding at a pressure of 200 kf/ctI for 7 minutes at °C. As a control, a single fiber of 3.2 tenier and length 3 was used instead of fiber bundle pellets.
．． A fiber-reinforced resin board having a thickness of 3.4 mm was prepared by mixing and molding the same polyester fibers of 0 mm in the same ratio into polyamide resin.

The impact resistance values of both were as shown in Table-2.

Table 2 Example 11 As seen in Example 2, in order to confirm that the fiber bundle pellets mixed with fibers had higher physical property values than those without the fiber bundle pellets, Examples 1 and 2 were prepared.
As a result of destroying the inventive product and the control product and observing the insides in detail, it was found that the reinforcing fibers of the inventive product were evenly distributed throughout the sample, whereas the fibers were significantly unevenly distributed in the control product. However, some areas where no fibers were observed were observed. Therefore, it is presumed that the control product has no effect on improving physical properties even if the same amount of fiber is added, since the portion where this fiber does not exist does not contribute to impact resistance and strength.

Therefore, the method of introducing fiber bundle pellets is proven to be an excellent method for uniformly dispersing fibers in a matrix.

[Brief explanation of drawings]

Figure 1 is a perspective view of a fiber bundle pellet impregnated with a binder and solidified, Figure 2 is a perspective view of a fiber bundle pellet with the outer periphery of the fibers coated with a binder, and Figure 3 is a perspective view of a resin pellet and fibers. FIG. 3 is a perspective view showing a mixed state of a bundle of pellets.

Claims (1)

[Claims] 1. Organic fibers or inorganic fibers are bundled, solidified with a binder, and the fiber bundle pellets obtained by cutting the fiber bundles are mixed with resin pellets, and the binding is performed during or prior to molding the mixed pellets. A method for producing a fiber-reinforced resin molded article, which comprises dispersing fibers by dissolving or melting an adhesive.