JPH04133708A - Manufacture of fiber-reinforced resin sheet - Google Patents

Abstract

PURPOSE:To make a distribution of resin and a fiber uniform, by a method wherein a cut fiber bundle is dropped and accumulated onto an endless belt while separating the same into filaments by blowing gas against the cut fiber bundle, which is heated while conveying by placing between a pair of a top and bottom endless belts. CONSTITUTION:Gas such as air or nitrogen is blown against a reinforcing fiber bundle which is cut and in the course of falling through a slitlike nozzle 90 and the reinforcing fiber bundle is separated favorably into monofilaments by pressure of the gas. Since an accumulated matter 3 dropped and accumulated onto an endless belt is conveyed while the same is being placed between a pair of a top and bottom endless belts 60, 61, fed to heating device 70 and heated at even a temperature of at least the melting point of a resin powder body 2, molten resin is infiltrated sufficiently among the filaments. Hereupon, since a clearance between the top and bottom endless belts 60, 61 is adjusted by a guide roll 71, the accumulated matter 3 is pressured in a thicknesswise direction and the molten resin powder body 2 is caused to flow by this pressurization, air gaps among the filaments are filled with the molten resin powder and the resin and the fiber are unified favorably.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a fiber-reinforced resin sheet in which reinforcing fibers are integrally impregnated with a thermoplastic resin.

(Prior art) As a method for manufacturing fiber-reinforced resin sheets, a mixture of thermoplastic resin powder and reinforcing fibers is heated and pressurized while being conveyed on a conveyor belt to melt the thermoplastic resin and strengthen the resin. It is known that resin is impregnated between fibers and then cooled under pressure to form a sheet in which the resin and fibers are integrated (for example, Japanese Patent Laid-Open No. 59-49929 and Japanese Patent Laid-Open No. 62-208914) reference).

(Problem to be solved by the invention a) However, among such conventional methods, the method described in the former publication mixes resin powder and reinforcing fibers with different specific gravities under a jet stream and causes them to fall and accumulate. Therefore, there is a problem in that the distribution of the resin and fibers becomes non-uniform and the physical properties vary widely. In addition, the method described in the latter publication is
Since the resin powder and reinforcing fibers are mixed in a mixing container, it is a batch method, and sheets cannot be obtained continuously, resulting in poor productivity.

The present invention is intended to solve the above-mentioned problems, and its purpose is to disperse the reinforcing fibers in monofilament units, to sufficiently impregnate the spaces between the monofilaments of the reinforcing fibers, and to create a structure in which the resin and the fibers are fully impregnated. An object of the present invention is to provide a method for manufacturing a fiber-reinforced resin sheet with a uniform distribution of fibers and less variation in physical properties, continuously and with good productivity.

(Means for Solving the Problems) The method for producing a fiber-reinforced resin sheet of the present invention involves passing a reinforcing fiber bundle composed of a large number of continuous monofilaments through fluidized thermoplastic resin powder. Resin powder is attached to the monofilaments of the fiber bundle, the fiber bundle with the resin powder attached is cut to a desired length using a cutter roll, and the cut fiber bundles are sprayed with gas to separate them into monofilaments while forming an endless belt. let it fall and accumulate on top,
The present invention is characterized in that the accumulated material is heated while being held and conveyed by a pair of upper and lower endless belts, thereby achieving the above object.

As the reinforcing fiber bundle used in the present invention, a strand-like or roving-like fiber bundle composed of several hundred to several thousand continuous monofilaments is preferably used. A large number of reinforcing fiber bundles are generally used in parallel in consideration of the width, thickness, manufacturing speed, etc. of the fiber-reinforced resin sheet to be manufactured.

As the reinforcing fibers, fibers that are thermally stable at the melting temperature of the thermoplastic resin powder used are used. For example, inorganic fibers such as glass fibers, carbon fibers, silicon/titanium/carbon fibers, boron fibers, and fine metal fibers, and organic fibers such as aramid fibers, polyester fibers, and polyamide fibers are preferably used.

The monofilament preferably has a diameter of 1 to 50 μm. Further, when a reinforcing fiber bundle in which monofilaments are bundled with a binding agent is used, the amount of the binding agent attached is preferably 1% by weight or less, more preferably 0.5% or less. If the adhesion amount of the sizing agent exceeds 1% by weight, it becomes difficult to separate the reinforcing fiber bundle into monofilament units in the fluidized bed of the resin, and the impregnation of the resin between the monofilaments decreases.

In the present invention, the length of the reinforcing fiber bundle cut into a desired length by a cutter roll is usually 0.5 to 500 rm, particularly preferably 5 to 150 m. If the length of the cut reinforcing fiber bundle is less than 0.5 aw, the reinforcing effect will be small;
Moreover, if the length exceeds 500 m, it becomes difficult to obtain a homogeneous fiber-reinforced resin sheet.

Further, as the thermoplastic resin powder used in the present invention, any resin that softens and melts when heated can be used. For example, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamide, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyvinylidene fluoride, polyphenylene sulfide, polyphenylene oxide, polyether sulfone, polyether ether ketone, etc. are used.

In addition, copolymers, graft resins, and blend resins containing the above resins as main components, such as ethylene vinyl chloride copolymers, vinyl acetate-ethylene copolymers, vinyl acetate-vinyl chloride copolymers, urethane-vinyl chloride copolymers, etc. Polymers such as acrylonitrile-butadiene-styrene copolymer, acrylic acid-modified polypropylene, maleic acid-modified polyethylene, etc. are also used.

These resins also contain stabilizers, lubricants, processing aids,
Additives such as plasticizers and colorants may be added. Further, both resins obtained in powder form during polymerization and resins made into powder form by a pulverizer can be used. As for the particle size, it is preferable that the average particle size is 2000 μm or less. When the average particle size exceeds 2000 μm, it becomes difficult to uniformly adhere the particles between the monofilaments of the reinforcing fiber bundle in a fluidized bed of resin.

In the present invention, the mixing ratio of the resin powder and the reinforcing fiber bundle is appropriately determined depending on the required physical properties of the fiber-reinforced resin sheet, but it is preferable that the amount of reinforcing fibers in the sheet is 5 to 70% by weight. If the reinforcing fiber content exceeds 70% by weight, it becomes difficult to obtain a sheet uniformly impregnated with resin;
If it is less than that, the mechanical strength of the sheet will decrease.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic side view showing an example of a manufacturing apparatus used in the present invention. This device includes an unwinding roll 10 in which a roll on which a reinforcing fiber bundle 1 is wound is set, a container 20 in which thermoplastic resin powder 2 is supplied, and a reinforcing fiber bundle 1 that has passed through the container 20. A slitter 30 for adjusting the adhesion amount of the resin powder 2 to be almost constant, a rubber take-up driving roll 40 and a pinch roll 41 for rewinding the reinforcing fiber bundle l from the unwinding roll lO, and the resin powder A cutter roll 50 that cuts the reinforcing fiber bundles to which No. 2 is attached to a desired length, a nozzle 90 that sprays gas onto the cut reinforcing fiber bundles, and a nozzle 90 that allows the reinforcing fiber bundles onto which the gas has been sprayed to fall and accumulate. It includes a pair of upper and lower endless belts 60, 61 for holding and conveying the object 3, a heating means 70, and a cooling means 80.

A large number of ventilation holes are provided at the bottom of the container 20, and a gas such as air or nitrogen sent from the gas supply path is supplied into the container 20 through the ventilation holes in the direction of the arrow. The resin powder 2 supplied into the container 20 becomes fluidized by the jetting of the gas, forming a fluidized bed 2a.
is formed. A guide roll 21 for guiding the reinforcing fiber bundle 1 is provided inside the container 20 and at the upper end of the wall.

As the cutter roll 50, a known rotary cutter is used, which has a large number of cutting blades provided at a constant arrangement on the peripheral surface of a metal roll, and is configured in combination with the take-up drive roll 40.

As the nozzle 90, a nozzle having a slit-shaped outlet is preferably used. The slit length of this nozzle 90 is approximately the same length as the length of the cutter roll 50 in the axial direction (perpendicular to the drawing).
It is installed parallel to the axial direction of the cutter roll 50 and below the cutter roll 50.

The slit-shaped gas outlet of the nozzle 90 is generally set diagonally downward or horizontally.

Note that a shielding plate 91 is provided to prevent the reinforcing fiber bundle from being blown away by the gas blown from the nozzle 90.

However, the shielding plate 91 is not necessarily required if the volume and pressure of the blown gas are adjusted appropriately. Moreover, as the nozzle 90, one in which a large number of nozzles having circular air outlets are arranged in parallel may also be used. In any case, it is important to uniformly spray the gas onto the numerous reinforcing fiber bundles that are being cut and falling.

The endless belts 60, 61 are set to continuously rotate in the same direction at substantially the same speed by driving drive rolls 62, 63 with a motor (not shown). Transfer parts 60a and 61a are formed on the upper endless belt 61 and the lower endless belt 60, respectively.
a and 61a are arranged vertically facing each other with a gap in between.

The transfer section 61a of the lower endless belt 61 is longer than the transfer section 6'Oa of the upper endless belt 60, extends forward from the front end of the transfer section 61a, and is open at the top.
1b is formed. In some cases, the transfer portion 61b of the lower endless belt 61 may be formed by arranging another endless belt below the transfer portion 61a of the lower endless belt 61, without extending the transfer portion 61a. Such endless belts 60, 61 are of high strength and heat resistance,
For example, it can be formed of a steel belt, a stainless steel belt, a glass cloth reinforced Teflon belt, or the like.

Transfer section 60 of upper endless belt 60 and lower endless belt 61
Heating means 70 are provided at opposing locations of a and 61a, respectively.
are arranged, and a cooling means 80 is arranged at the rear following the heating means 70. As shown in the figure, the heating means 70 preferably includes a hot air circulation type or an electric heating type heating furnace, through which an endless belt 60, 61 is passed. In addition, a system in which heating rolls are used to directly heat the endless belt 60, 61 while sandwiching the belt may also be adopted.

Inside the heating means 70, a plurality of pairs of guide rolls 71 are disposed at corresponding positions above and below. The cooling means 80 is configured to cool by blowing air using a blower or the like, and is further provided with a plurality of pairs of guide rolls 81 at corresponding positions above and below. The clearances between the guide rolls 71 and 81 corresponding to the upper and lower sides can be adjusted respectively. Note that as the cooling means 80, a method of cooling the guide roll 81 with water may also be adopted.

Next, a method for manufacturing a fiber-reinforced resin sheet of the present invention will be explained using the above-mentioned apparatus.

As shown in FIG. 1, a reinforcing fiber bundle 1 composed of a large number of monofilaments is taken up by a take-up drive roll 40 and a vinyl roll 41, and is not twisted from the roll around which the reinforcing fiber bundle l is wound. It will be rewound so that it doesn't exist. Then, this reinforcing fiber bundle 1 is attached to a guide roll 21.
is guided into the fluidized bed 2a. In addition, although only one reinforcing fiber bundle 1 is shown and explained in the figure for convenience, generally a large number of reinforcing fiber bundles 1 are used in parallel.

In this fluidized bed 2a, the reinforcing fiber bundle 1 is separated and opened into monofilament units by the ejection of gas such as air or nitrogen, static electricity generated in the fluidized bed 2a, the rubbing effect of the resin powder 2, etc. Resin powder 2 is placed between this monofilament.
enters and is electrostatically captured and attached. In this case, the width of the reinforcing fiber bundle 1 increases to some extent because it is separated and opened into monofilament units. The reinforcing fiber bundle 1 to which the resin powder 2 has adhered passes between the slitters 30, thereby removing the excessively adhered resin powder 2. By adjusting the gap between the slitters 30, the amount of resin powder 2 deposited is adjusted.

The reinforcing fiber bundle 1 with the resin powder 2 attached thereto passes through a drive roll 40 and a pinch roll 41 to be taken up, and then is cut into short dimensions of a desired length by a cutter roll 50 and transported by a lower endless belt 61. The material is dropped onto the portion 40b and accumulated to a predetermined thickness. At this time, a gas such as air or nitrogen is blown through the slit-shaped nozzle 90 onto the reinforcing fiber bundle that has been cut and is falling, and the reinforcing fiber bundle is separated into monofilaments by the pressure of this gas.

The accumulated material 3 that has fallen onto the endless belt is transferred while being held between a pair of upper and lower endless belts 60 and 61 to the heating means 7.
0 and heated at a temperature higher than the melting point of the resin powder 2, so that the molten resin is sufficiently impregnated between the filaments.

Here, the upper and lower endless belts 60 are
．． The clearance between the monofilaments 61 is adjusted, the aggregate 3 is pressurized in the thickness direction, and this pressurization causes the melted resin powder 2 to flow, thereby filling the gaps between the monofilaments and ensuring good interaction between the resin and the reinforcing fibers. be integrated. Subsequently, the clearance between the upper and lower endless belts 60, 61 is adjusted by the cooling guide roller 80 of the cooling means, and the heated stack 3 is cooled while being pressurized. In this way, a fiber-reinforced resin sheet 4 having a predetermined thickness is manufactured.

(Operation) In this way, resin powder is attached between the filaments of a reinforcing fiber bundle in a fluidized bed, this is cut to a desired length, and gas is blown onto the cut reinforcing fiber bundle to separate it into monofilaments. When the accumulated material is fed between a pair of upper and lower endless belts and heated and integrated, the reinforcing fiber bundles are opened in the fluidized bed and the cut reinforcing fiber bundles are separated. The effect of the gas spraying is that the separation into filament units is sufficiently performed, and the resin is impregnated between the filaments in a sufficient and uniform distribution. Moreover, the entire process can be performed continuously.

(Example) Hereinafter, the present invention will be explained based on examples.

Difference ■1 A fiber-reinforced resin sheet was manufactured using the apparatus shown in FIG.

As thermoplastic resin powder 2, a resin blended powder obtained by mixing the following formulation in a super mixer was used.

・Polyvinyl chloride resin (average degree of polymerization 400, average particle size 1
50μm) ・・・・・・・・・・・・100 parts by weight・Butyltin maleate ・・・・・・・・・・・・
3 parts by weight polyethylene wax・・・・・・・・・
...0.5 parts by weight, stearyl alcohol...
...... 1 part by weight reinforcing fiber bundle 1, diameter 2
A roving-like glass fiber bundle (approximately 0.3% by weight of sizing agent attached) was used, which was formed by converging 4,000 3 μm monofilaments.

A glass cloth-reinforced Teflon belt (width: 600 wa, thickness: approximately 1 cm) was used as the endless belt 60, 61, and the slit-shaped nozzle 90 was set to blow air diagonally downward at an angle of approximately 45 degrees. .

Twelve reinforcing fiber bundles 1 are placed in a fluidized bed 2 of the resin blended powder 2.
After passing through the monofilament continuously and adhering the resin blended powder 2 between the monofilaments, excess resin blended powder is removed by the slitter 30, and the weight ratio of the resin blended powder and reinforcing fibers is 7=3. Then cut it into a length of about 25m+ with a cutter roll 50 and cut it into an endless bell)
61b. Supply amount is 600 wn width
It was supplied and accumulated at a rate of 3320 g/i to a range of about 500 wa at the center of the endless belt 61b. At this time, the apparent thickness of Accumulation 3 was approximately 32 temples.

At this time, air was ejected in a slit shape from the slit-shaped nozzle 90, and the air was sprayed almost uniformly toward the falling reinforcing fiber bundle, thereby separating the reinforcing fiber bundle into monofilaments. Then, endless bell) 61b
While the above stack 3 is held between the upper and lower endless belts 60.61 moving at a speed of 580 km/min, the minimum gap between the endless belts 60.61 is set by the guide rolls 71 to approximately 2.1 mm. Adjust to 200℃ with a length of about 1,500m.
The resin compound powder 2 was melted by passing through a heating furnace 70 in which hot air was circulated.

Subsequently, an aggregate 3 in which the resin blended powder 2 is in a molten state is produced.
The minimum gap between the endless bells) 60 and 61 was adjusted to about 2 cm by a guide roll 81, and the fiber-reinforced resin sheet 4 was produced by cooling with a cooling blower 80. This fiber-reinforced resin sheet 4 had a width of about 500 m and a thickness of about 21,111 mm, and was a sheet in which the resin was well impregnated between the filaments and the filaments were uniformly dispersed.

Cut out test pieces of 30 x 30 squares from 5 random locations in the range of 500 squares x 2,000 squares of this sheet, and
The resin was treated at 00°C for 5 hours to burn off the resin, and the glass fiber content was measured. Also, width 20 x length 15
A test piece of 0 mm was cut out, and a three-point bending test was conducted with a distance between supports of 120 mm to measure the bending strength. The test results are shown in Table 1.

A fiber reinforced resin sheet was manufactured using the apparatus shown in Table 1 and Figure 1.

As the thermoplastic resin powder 2, frozen pulverized powder of pellet-like polypropylene resin (average particle size 200 μm) was used, and as the reinforcing fiber bundle 1, a roving-shaped glass fiber bundle formed by converging 4000 monofilaments with a diameter of 23 μm was used. (approximately 0.3% by weight of sizing agent) was used.

A glass cloth-reinforced Teflon belt (600 mm diameter, approximately 1 mm thick) was used as the endless belt 60, 61, and the slit-shaped nozzle 90 was set to blow air diagonally downward at an angle of about 45 degrees. .

Ten reinforcing fiber bundles 1 are continuously passed through the fluidized bed 2a of the resin powder 2 to adhere the resin blended powder 2 between the monofilaments, and then excess resin powder is removed by a slitter 30. , the weight ratio of resin powder and reinforcing fiber is 6:4.
This was cut into approximately 25 mm lengths using a cutter roll 50 and fed onto an endless belt 61b. The supply amount was 3600 g #If in a range of approximately 500 mm in the center of the endless belt 61b having a width of 600 mm. At this time, the apparent thickness of Accumulation 3 was approximately 45 temples.

At this time, air was ejected in a slit shape from the slit-like nozzle 90, and the air was blown almost uniformly toward the falling reinforcing fiber bundle, thereby separating the reinforcing fiber bundle into monofilaments. Next, the endless belt 61b
While the upper stack 3 is held between upper and lower endless belts 60.61 moving at a speed of 500 m/min, the minimum gap between the endless belts 60.61 is set by a guide roll 71 to approximately 3.1 wa. 210 at a length of approximately 1,500 m.
The resin powder 2 was melted by passing through a heating furnace 70 in which hot air of °C was circulated.

Subsequently, the aggregate 3 in which the resin powder 2 is in a molten state is
The minimum gap between the endless healds 60 and 61 is the guide roll 8.
1 to about 3 degrees, and cooled with a cooling blower 80 to produce a fiber-reinforced resin sheet 4. This fiber-reinforced resin sheet 4 had a width of about 500 m and a thickness of about 3 mm, and was a sheet in which the resin was well impregnated between the filaments and the filaments were uniformly dispersed.

Regarding this sheet, the glass fiber content and bending strength were measured in the same manner as in Example 1. The test results are shown in Table 2.

A fiber-reinforced resin sheet was manufactured using the apparatus shown in FIG.

As the thermoplastic resin powder 2, nylon-6 resin powder (average particle size of about 80 μm) was used, and as the reinforcing fiber bundle 10, a roving-shaped polyacrylonitrile with a width of about 6 m formed by converging 6000 monofilaments with a diameter of 7 μl was used. carbon fiber bundles were used.

A glass cloth-reinforced Teflon belt (width: 600 mm, thickness: approximately 1 m) was used as the endless belt 60, 61, and the slit-shaped nozzle 90 was set to blow air diagonally downward at an angle of approximately 45 degrees.

Ten reinforcing fiber bundles 1 are continuously passed through the fluidized bed 2a of the resin powder 2 to adhere the resin blended powder 2 between the monofilaments, and then excess resin powder is removed by a slitter 30. , the weight ratio of resin powder and reinforcing fiber is 7.5
: 2.5, and cut it into lengths of about 50 cm using a cutter roll 50 and making an endless bell) 61
It was supplied dropwise onto b. The amount of supply is 3750 g in a range of approximately 500 mm in the center of the endless belt 61b with a width of 600 mm.
Supply and accumulation were carried out so that /rrf. At this time, the apparent thickness of the aggregate 3 was about 30 cm.

At this time, air was ejected in a slit shape from the slit-shaped nozzle 90, and the air was sprayed almost uniformly toward the falling reinforcing fiber bundle, thereby separating the reinforcing fiber bundle into monofilaments. Next, endless bell t-61b
While the upper stack 3 is held between the upper and lower endless belts 60.61 moving at a speed of 500 cm/min, the minimum gap between the endless belts 60.61 is set by the guide rolls 71 to approximately 3.2 mm. It is adjusted to the height of about 240 degrees with a length of about 1500 am.
The resin powder 2 was melted by passing through a heating furnace 70 in which hot air of C was circulated.

Subsequently, the aggregate 3 in which the resin powder 2 is in a molten state is
The minimum gap between the endless belt 60 and 61 is the guide roll 8.
1 to about 3 degrees, and cooled with a cooling blower 80 to produce a fiber-reinforced resin sheet 4. This fiber-reinforced resin sheet 4 had a width of approximately 500 mm and a thickness of approximately 3 m, and was a sheet in which the resin was well impregnated between the filaments and the filaments were uniformly dispersed.

Regarding this sheet, the glass fiber content and bending strength were measured in the same manner as in Example 1. The test results are shown in Table 3.

In Example I of Table 3, air was not blown onto the cut reinforcing fiber bundles. Other than that, the same procedure as in Example 1 was carried out.

Regarding the obtained sheet, the glass fiber content and bending strength were measured in the same manner as in Example 1.

The test results are shown in Table 4.

(Effects of the Invention) As described above, according to the method of the present invention, the reinforcing fibers are well dispersed in monofilament units, and the resin is sufficiently impregnated even between the nofilaments of the reinforcing fibers, so that the reinforcing effect of the reinforcing fibers is improved. It has excellent physical properties with high properties, and since the distribution of the reinforcing fibers and resin is uniform, a fiber-reinforced resin sheet with uniform physical properties can be obtained. Furthermore, since the process can be performed continuously, productivity is good.

The fiber-reinforced resin sheet obtained by the method of the present invention is not only useful as a particularly strong plate material, but also suitably used as a so-called stampable sheet, which is a material for press molding to obtain various products. obtain.

[Brief explanation of drawings]

FIG. 1 is a schematic side view showing an example of an apparatus used in the method of the present invention. 1... Reinforcing fiber bundle, 2... Thermoplastic resin powder, 2a
...Fluidized bed of resin powder, 3. Accumulate, 4. Fiber-reinforced resin sheet, 50. Cutter roll, 60.
61... A pair of upper and lower endless belts, 70... Heating means, 80... Cooling means, 90... Nozzle.

Claims (1)

[Claims] 1. A reinforcing fiber bundle consisting of a large number of continuous monofilaments is passed through fluidized thermoplastic resin powder to adhere resin powder to the monofilaments of the fiber bundle, and this resin powder is attached to the monofilaments of the fiber bundle. The fiber bundle is cut to the desired length with a cutter roll, and gas is blown onto the cut fiber bundle to separate it into monofilaments, which are then dropped and accumulated on an endless belt.This aggregate is then conveyed by being held between a pair of upper and lower endless belts. A method for producing a fiber-reinforced resin sheet, characterized by heating the sheet while heating.