JPH04138219A - Manufacture of long fiber-contained resin composition - Google Patents

Abstract

PURPOSE:To improve creeping resistance and shock resistance by charging and splitting a long fiber bundle, attaching resin powder, melting resin powder through heating and coating long fibers with a resin. CONSTITUTION:A fiber bundle is charged by a charging equipment 1, and forwarded to a fluidized bed 2 filled with resin powder. The coated resin is powdered and forms the fluidized bed by air at that time, and resin powder is attached on charged fibers when the resin is passed through charged fibers. The fibers are melting-coated with the resin adhering on the surfaces of the fibers by passing the fiber bundle, on which resin powder is attached, through a heating furnace 3a. Consequently, a resin-coated long fiber bundle is manufactured, but the melting-attached fibers are bundled by a heating die 3b as required at that time. When the resin-coated long fiber bundle intends to be changed into strands with the same object as a protrusion method at that time, the bundle is received by using a circular die by a receiving hole, and passed through a cooling sizer 4 and a shape is fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Fields] The present invention is a method for producing a fiber-reinforced resin composition. Used for parts.

[Prior art] Fiber-reinforced plastics are used when creep resistance and impact resistance are required for plastics used in the industrial materials field, and these are made by coating fiber bundles with resin using the pultrusion method. A manufacturing method or a method of impregnating mat-like fibers with resin is adopted.

In order to coat resin using the pultrusion method, it is necessary to divide all the fiber bundles charged into the manufactured product into several bundles due to manufacturing constraints.Resin fiber bundles There was a problem in that each single fiber inside was not sufficiently coated.

As a result, the adhesion between the reinforcing fibers and the resin becomes insufficient, and the contribution of the reinforcing fibers to the overall stiffness and tensile strength of the reinforced plastic is low, resulting in a disadvantage that reinforcement tends to be insufficient.

For this reason, it is sufficient to reduce the molecular weight of the resin that serves as the L matrix that allows the resin to penetrate between each single fiber, and to lower the Gfpl viscosity to improve the permeability into the fiber bundle. We are trying to find a solution.

However, lowering the molecular weight of the resin is not possible.

Not only is the problem of resin penetration into the fiber bundle insufficiently resolved, but it also significantly reduces the long-term creep strength of the product.
This results in loss of reliability of the material.

Also, when impregnating the latter matte fiber with resin,
Similarly, in order to improve the penetration of the resin into the mat fibers and, as a result, to improve the adhesive strength, it is necessary to lower the melt viscosity by lowering the molecular weight of the resin, which poses the same unresolved problems as above.

[Problems to be Solved by the Invention] In the present invention, in order to improve the creep resistance and impact resistance of fiber reinforced plastics, each single fiber is coated more completely with resin and [Means for Solving the Problems] The present invention relates to a method for manufacturing a long fiber-containing resin composition in which the manufacturing process is devised so that a material with a molecular weight higher than the molecular weight can be used. Thereafter, a method for producing a long fiber-containing resin composition, which is characterized in that a resin powder is attached, and then heated to melt the resin powder and coat the long fibers with the resin.

Note that FIG. 1 shows one embodiment of the present invention, and although the present invention is not limited thereto, the description will be made using this figure for ease of understanding.

That is, the fiber bundle is charged with a charging device (1), and then sent to a fluidized bed (2) filled with resin powder (8).
Here, the resin to be coated is in powder form and forms a fluidized bed with air, and when the charged fibers are passed through, the resin powder is attached to the charged fibers. Next, the fiber bundle with the resin powder attached thereto is passed through a heater to melt and coat the fibers with the resin attached to the fiber surface. In this way, a resin-coated long fiber bundle is produced, and at this time, if necessary, the melted and adhered fibers are bundled using a heating die (3b). At that time, if you want to make a strand for the same purpose as the pultrusion method, you can take it out using a die with a circular take-off hole and pass it through a cooling sipe (4) to fix the shape.

On the other hand, if you need something with a specific cross-sectional shape, such as a sheet, plate, or L-shape, you can cut a bundle of coated fibers with the required width and thickness into a die in the shape of the desired product, or if you need a pipe. The resin compositions in various shapes obtained by the method of passing through a hollow cylindrical die have fibers uniformly distributed and oriented in one direction, so they have high creep resistance in the direction of orientation. Indicates tensile strength, stiffness, and impact resistance.

In addition, when making pellets, the fibers are uniformly distributed by passing them through a die of an appropriate thickness and cutting them to an appropriate length.Especially when using an extruder or injection machine, the fibers can be uniformly dispersed during plasticization. Since there is less cutting and the uniformity of dispersion is high, it is possible to obtain a fiber-containing resin composition that has a high reinforcing effect on the strength and impact resistance of molded articles.

The applied voltage of the charging device for charging in the present invention is difficult to specify because it depends on various factors such as the material of the monofilament, the fineness, the number of fiber bundles, etc., but the simplest method is to It seems best to adjust whether or not to spread the fibers through the bundle by checking the degree of adhesion of the resin powder to the spread fibers.

The long fibers used in the present invention include glass fibers, carbon fibers,
Examples include metal fibers and 1a-free compound fibers.

The monofilament preferably has a diameter of 5 to 15 microns, preferably 8 to 13 microns. Furthermore, each fiber bundle usually consists of 20 to 2000 monofilaments held together with a binding agent.

By strongly electrifying the monofilaments, they repel each other, and the bound bundle is opened by this electrification, and the entire monofilament is evenly distributed spatially.

In this state, it is guided to a resin adhesion zone, usually a fluidized immersion layer of resin powder, and in the fluidized bed, the resin powder can be evenly and uniformly adhered to the fiber surface due to static electricity.

When the fiber bundle is opened in this way, the resin powder adheres to the monofilament at all positions, and the temperature during heating can be raised quickly, so the heating process time can be shortened, increasing production efficiency. It is desirable not only to increase the temperature, but also to ensure uniform adhesion between the resin and the fibers.

However, when increasing the take-up speed to increase productivity, the upper limit of the fiber bundle is about 2,000 monofilaments, but it is preferable to use a bundle of about 50 to 500 monofilaments. When the fiber bundle is less than 50, it is easy to break when taking it off at high speed, but on the other hand, when the fiber bundle is more than 2,000, the opening is not successful and the resin powder does not adhere evenly to each monofilament during fluid dipping, resulting in non-uniformity. Easy 6 Although the resin adhesion zone is not limited to a fluidized bed, it is mainly used because of the uniformity of adhesion and ease of operation. Here, resin powder is formed into a fluidized bed by air pressure. The stability of the fluidized bed and uniform welding when coated are largely influenced by the average diameter (D5°) and particle size distribution of the resin powder particles, as well as the aspect ratio of the particles. The particle size is determined by sifting 200 grams using a Tyler sieve with a shaker. The weight remaining on the sieve opening was integrated from the coarsest to the coarsest, and 50% of the weight average was determined to have a center particle size of D5°. In this method, the center particle size is preferably about 40 microns to 125 microns. Further, the particle size distribution can be determined from the particle size gradient when plotted on logarithmic probability paper. Dw that
/D When expressed as n, it is preferably in the range of 15 to 5, but preferably 3 or less.

The narrower the particle size distribution, the more stable the fluidized bed, and the more uniformly the resin powder adhering to the monofilament will be melted and coated with a smooth and uniform appearance. It is easy to control the product so that it does not contain unmelted substances. If the particle size distribution is wide, there will be a time difference between the adhering resin powders until they melt, and there is a risk that unmelted materials will remain on the monofilament because they are pulled out of the heating furnace before they are completely melted. When the unmelted material is bundled with a heating die, it is difficult to re-melt it even if the heat is sufficiently applied with the die, and the residue remains as a defect in the long fiber-containing resin composition, which can significantly reduce the strength of the product.

The resin powder attached to the monofilament is then melted by heating and coats the fiber. At this time, any heating method may be used as long as the resin can be sufficiently melted and the monofilament can be coated. However, ease of operation,
From the viewpoint of stability etc., a heating furnace is preferable.

The heating furnace is generally an electric furnace made of refractory material, and examples include nichrome or kanthal wire as the heating element. The temperature at which the fibers are heated needs to be high enough for the subsequent resin to melt and adhere. For example, a temperature of about 200°C to 6230°C is desirable for polyolefins, and a temperature of 260°C to 290°C is good for polyamides (retention time is 0.3°C).
~3 seconds (varies depending on temperature and type of resin).

When passing through a heating die, the temperature of the die is affected by the thickness of the fiber bundle, the amount of resin attached, the die gap, the type of resin powder, etc., but it is approximately the temperature of the heating furnace ±30"C.
It can be determined by a simple test.

Furthermore, in the case of carbon fibers, the length of the heating furnace itself can be shortened by energizing the fiber itself in the section where it passes through the heating furnace, thereby causing the fiber itself to generate heat. This method has the advantage of being able to perform uniform heating.

The synthetic resin used in the present invention is not particularly limited, but in terms of -M, polyolefins such as high-density polyethylene and polypropylene, polyamide (PA), poly(carbonate)-(PC), PC and ABS, or PC are used. and a blend of polyoxymethylene and PA, and a blend of polyoxymethylene and PA.

In conventional manufacturing methods such as the pultrusion method or when mat-like fibers are impregnated with resin, a molten high-viscosity synthetic resin is press-fitted into fiber bundles or mat-like fibers, so the viscosity of the resin itself Since it is necessary to lower the molecular weight and facilitate impregnation, it is necessary to use a relatively low molecular weight resin, and even then, impregnation is not complete and cutting and uneven distribution of fibers cannot be avoided.

On the other hand, as can be easily understood from the above explanation, in the method of the present invention, the fiber bundle is efficiently opened by charging the fiber bundle, and the opened fiber bundle is formed into powder. The resin powder is attached to the monofilament and then melted to form a fiber-containing resin composition.
Theoretically speaking, it is not necessary to consider the melt viscosity of the resin with respect to resin impregnation into the fibers, and it is now possible to select a resin with a melt viscosity appropriate for the subsequent molding process.

For this reason, conventional fiber reinforcement properties for reinforced plastic products have been insufficient in terms of rigidity, tensile strength, etc. due to the lower molecular weight of resins, but with the method of the present invention, Madnox resins that have sufficient strength can also be selected. In addition to this, it has become possible to obtain a product with high uniformity of fiber dispersion in the matrix resin and high strength.

[Function] In the present invention, a bundle of monofilaments is charged by applying a high voltage, and thereby the repulsion between each monofilament is used to efficiently spread the fibers, and the charge is used to efficiently and uniformly spread the resin powder. This is a method in which the resin is applied to the fiber bundle, and then heated and melted to coat the fibers with a resin, thereby allowing the resin to uniformly penetrate into the inside of the fiber bundle.

[Example] (Example 1) A glass fiber bundle (GF) composed of 1500 fibers with a diameter of 10 microns was charged at -30 kV and opened in an apparatus as shown in FIG. This is then introduced into a fluidized bed of resin powder. The resin forming the fluidized bed is polypropylene powder (PP), and is JIS K 7
1 at the melt flow rate at 230°C specified in 113.
．． 5g/10 minutes. The average particle size was 70 microns and the particle size distribution was I) w/D n of 2.

The fiber bundle with polypropylene powder adhered to it that came out of the fluidized bed was heated in a heating furnace at 200°C, then passed through a sheet-shaped heating die (230°C), and then held in shape with a cooling sizer to form a compact.

The molded body had a thickness of 1.5 mm, a width of 15 mm, and was cut into a length of 25 mm. Ash analysis at this time revealed that the glass content was 37%. When this was subjected to a bending test using the test method specified in JIS 7113, the elastic modulus was 93. O
The weight was O0Kg70m2, which was 69% of the theoretical average elastic modulus. When this is reheated and compression molded with a press, it becomes 60.
．． The elastic modulus was 42% of the theoretical elasticity at 000 kg/am2.

JIS 2 specified by JIS K 7113 for molded products
A test piece of No. 1 dumbbell was cut out, and the creep performance was measured by applying a static load of 30 kg/cm" in an atmosphere of 130°C, 150°C, and 170°C.
The reciprocal of the measured absolute temperature was plotted on the horizontal axis for the time it took to change to 2 mm, and the creep time for a displacement of 2 mm at 60°C and 100°C was calculated by extrapolation. time and 378 hours. In addition, when a drop weight test was performed on a head with a tip curvature of 6.35 mm, the breaking strength was measured using potential energy and was 305 Kg/cm'', indicating high impact resistance.6 (Examples 2 to 5) A resin composition containing long glass fibers was manufactured using a material with a low resin powder melt flow as shown in Table 1, and this was molded in the same manner as in Example 1, and samples were made and tested. It showed high creep performance and impact resistance.

(Comparative Example 1) In Example I, the melt flow rate of the resin powder was set to 3.
A molded body was molded in the same manner except that 0g/I 0 minute polypropylene was used, and then a test piece was created using a press and the creep strength was measured.The time required to reach a displacement of 2mm was 6.
It was 1200 hours at 0°C and 30 minutes at 100°C. Creep resistance was significantly reduced.

In addition, the impact strength was 220 kg due to the lower molecular weight of the resin.
-cm, and both results were lower than those of Example 1.

(Comparative Example 2) Using polypropylene with the same melt flow rate as in Example 1, it was drawn into strands using the pultrusion method, but the melt viscosity of the resin was high and the resin did not penetrate well into the fiber bundle. I couldn't go and mold it.

(The following is a blank space) [Effects of the Invention] The method for producing a long fiber-containing resin composition of the present invention involves opening the east end of a monofilament by electrically charging it, and applying the electrostatic force to the opened fibers to infuse resin particles into the fibers. After the powder is once attached, the monofilament is coated with resin by melting, so the inside is uniformly coated with a high molecular weight thermoplastic resin, and the resin composition containing long fibers obtained by molding this. When compared to molded products made from raw materials obtained using conventional pultrusion methods or matte fiber-impregnated resins, the molecular weight of the matrix resin has been significantly increased. The molded products of the present invention have excellent creep properties, tensile strength, Impact strength can be significantly improved, and its use in new applications in the field of fiber-reinforced plastics is eagerly awaited.

[Brief explanation of the drawing]

FIG. 1 shows an example of a long fiber resin coating device.

Claims (4)

[Claims] (1) A long fiber-containing resin composition characterized in that after a long fiber bundle is charged and opened, a resin powder is attached thereto, the resin powder is melted by heating, and the long fibers are covered with the resin. Production method. (2) A method for producing a long fiber-containing resin composition according to claim 1, in which a resin composition molded into strands is cut into pellets. (3) A method for producing a long fiber-containing resin composition according to claim 1, which is formed into a sheet or plate shape so that the fibers are oriented in one direction. (4) The method for producing a long fiber-containing resin composition according to claim 1, wherein the long fiber bundle is a glass fiber bundle and the resin powder is polypropylene, polyamide, or polycarbonate.