JP2991470B2 - Method for producing fiber reinforced resin sheet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a fiber-reinforced resin sheet in which a thermoplastic resin is impregnated and integrated between reinforcing fibers.

(Prior art) As a method of manufacturing a fiber-reinforced resin sheet, a mixture of a thermoplastic resin powder and a reinforcing fiber is heated and pressed while being conveyed by a conveyor belt to melt the thermoplastic resin and to strengthen the resin. It is known to impregnate between fibers and then cool under pressure to form a sheet in which resin and fibers are integrated (for example, JP-A-59-49929 and JP-A-62-208914). reference).

(Problems to be Solved by the Invention) However, in such a conventional method, the method described in the former gazette is to mix resin powder and reinforcing fibers having different specific gravities under a jet stream to be dropped and accumulated. In addition, there is a problem that the distribution of the resin and the fiber becomes non-uniform, and the dispersion of the physical properties increases. Further, the method described in the latter publication has a problem that since the resin powder and the reinforcing fiber are mixed in a mixing vessel, a batch method is used, and sheets cannot be continuously obtained, resulting in poor productivity.

The present invention solves the above-mentioned problems, and aims at dispersing the reinforcing fibers in monofilament units, and sufficiently impregnating the resin between the monofilaments of the reinforcing fiber, and furthermore, the resin and the fiber The object of the present invention is to provide a method for producing a fiber reinforced resin sheet having a uniform distribution of properties and a small variation in physical properties with continuous and good productivity.

(Means for Solving the Problems) The method for producing a fiber-reinforced resin sheet of the present invention comprises the steps of: forming a reinforcing fiber bundle composed of a large number of continuous monofilaments;
The resin powder is allowed to adhere to the monofilament of the fiber bundle by passing through the fluidized thermoplastic resin powder, and the fiber bundle to which the resin powder is adhered is cut into a desired length by a cutter roll, and the cut material is cut. The fiber bundle is blown with gas to separate it into monofilaments, and is dropped and accumulated on an endless belt. This stack is heated by being pinched and transported by a pair of upper and lower endless belts. Is achieved.

As the reinforcing fiber bundle used in the present invention, a strand-like or roving-like fiber bundle composed of hundreds to thousands of continuous monofilaments is suitably used. A large number of the reinforcing fiber bundles are generally used in parallel in consideration of the width, thickness, manufacturing speed, and the like 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 to be used are used. For example,
Glass fiber, carbon fiber, silicon / titanium / carbon fiber,
Inorganic fibers such as boron fibers and fine metal fibers, and organic fibers such as aramid fibers, polyester fibers, and polyamide fibers are preferably used.

The diameter of the monofilament is preferably 1 to 50 μm. When a reinforcing fiber bundle in which the monofilament is converged by the sizing agent is used, the amount of the sizing agent attached is preferably 1% by weight or less, more preferably 0.5% or less. When 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 between the monofilaments of the resin decreases.

In the present invention, the length of the reinforcing fiber bundle cut to a desired length by the cutter roll is usually 0.5 to 500 mm, and particularly preferably 5 to 150 mm. The length of the cut reinforcing fiber bundle is
If it is less than 0.5 mm, the reinforcing effect is small, and if it is more than 500 mm, it is difficult to obtain a uniform fiber-reinforced resin sheet.

As the thermoplastic resin powder used in the present invention, any resin that is softened and melted by heating 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 and the like are used.

Further, copolymers, graft resins and blend resins containing the above resins as main components, for example, ethylene-vinyl chloride copolymer, vinyl acetate-ethylene copolymer, vinyl acetate-vinyl chloride copolymer, urethane-vinyl chloride Copolymers, acrylonitrile-butadiene-styrene copolymers, acrylic acid-modified polypropylene, maleic acid-modified polyethylene and the like are also used.

These resins may be blended with additives such as stabilizers, lubricants, processing aids, plasticizers, and coloring agents. In addition, any of a resin obtained in a powder form during polymerization and a resin made into a powder form by a pulverizer can be used. The average particle diameter is preferably 2000 μm or less. When the average particle size exceeds 2000 μm, it is difficult to uniformly adhere between the monofilaments of the reinforcing fiber bundle in the fluidized bed of the 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 the reinforcing fiber in the sheet is preferably 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, while if it is less than 5% by weight, the mechanical strength of the sheet decreases.

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 adheres to a rewind roll 10 for setting a roll around which the reinforcing fiber bundle 1 is wound, a container 20 to which the thermoplastic resin powder 2 is supplied, and the reinforcing fiber bundle 1 passing through the container 20. A slitter 30 for adjusting the adhesion amount of the resin powder 2 to be substantially constant, a rubber take-off drive roll 40 and a pinch roll 41 for rewinding the reinforcing fiber bundle 1 from the rewind roll 10, A cutter roll 50 for cutting the reinforcing fiber bundle to which the fiber 2 has adhered into a desired length, and a nozzle 90 for blowing gas to the cut reinforcing fiber bundle.
And let the reinforcing fiber bundle sprayed with gas fall and accumulate,
A pair of upper and lower endless belts 60 and 61 for holding and transporting the stack 3, a heating unit 70 and a cooling unit 80 are provided.

A large number of ventilation holes are provided at the bottom of the container 20, so that 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 is in a fluidized state by the gas ejection, and 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 having a large number of cutting blades provided in a fixed arrangement on a peripheral surface of a metal roll and configured in combination with the take-up driving roll 40 is used.

As the nozzle 90, a nozzle having a slit-shaped outlet is preferably used. The slit length of the nozzle 90 is substantially the same as the length of the cutter roll 50 in the axial direction (perpendicular to the drawing), and is parallel to the cutter roll 50 and below the cutter roll 50. . The slit-shaped gas outlet of the nozzle 90 is generally set obliquely downward or horizontally.

A shielding plate 91 is provided to prevent the reinforcing fiber bundle from being blown off by gas blown from the nozzle 90. However, if the amount and pressure of the gas to be blown are appropriately adjusted, the shielding plate 91 is not necessarily required. Further, as the nozzle 90, a nozzle in which a number of nozzles having a circular outlet are arranged in parallel may be used. In any case, it is important to ensure that the gas is uniformly blown to a large number of reinforcing fiber bundles that have been cut and dropped.

The endless belts 60 and 61 are set so as to continuously rotate and move at substantially the same speed in the same direction by driving the drive rolls 62 and 63 by a motor (not shown). The upper endless belt 61 and the lower endless belt 60 are formed with transfer portions 60a and 61a, respectively, and the transfer portions 60a and 61a are arranged to face each other with a gap therebetween.

The transfer section 61a of the lower endless belt 61 is
The transfer section 61b is formed to be longer than the transfer section 60a, extend forward from the front end of the transfer section 61a, and open upward. The transfer section 61b of the lower endless belt 61 may be formed by arranging another endless belt on the lower side without extending the transfer section 61a of the lower endless belt 61 in some cases. The endless belts 60 and 61 can be formed of a high-strength and heat-resistant belt such as a steel belt, a stainless steel belt, or a glass cloth reinforced Teflon belt.

The transfer sections 60a, 6 of the upper endless belt 60 and the lower endless belt 61
Heating means 70 are arranged at the opposing portions of 1a, respectively.
Cooling means 80 are disposed at the rear following the heating means 70, respectively. The heating means 70 is constituted by a heating furnace of a hot air circulation type or an electric heating type as shown in the figure, and a type in which the endless belts 60 and 61 pass therethrough is suitably employed.
In addition, a system in which a heating roll is used to directly heat the endless belts 60 and 61 while nipping the belts may be adopted.

In the heating means 70, a plurality of pairs of guide rolls 71 are disposed at corresponding positions in the upper and lower directions. The cooling means 80 is configured to blow air by a blower or the like to cool, and furthermore, a plurality of pairs of guide rolls
81 are arranged. The clearance between the upper and lower guide rolls 71 and 81 can be adjusted. In addition, as the cooling means 80, a method of cooling the guide roll 81 with water may be adopted.

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

As shown in FIG. 1, the reinforcing fiber bundle 1 composed of a large number of monofilaments is twisted from the roll around which the reinforcing fiber bundle 1 is wound while being taken up by the take-up driving roll 40 and the pinch roll 41. It is rewound so that there is no. The reinforcing fiber bundle 1 is guided into the fluidized bed 2a while being guided by the guide rolls 21. In the drawings, only one reinforcing fiber bundle 1 is illustrated for convenience, but a large number of reinforcing fiber bundles 1 are generally used in parallel.

In the fluidized bed 2a, the reinforcing fiber bundle 1 is formed by the ejection of gas such as air or nitrogen, the static electricity generated in the fluidized bed 2a, and the resin powder 2.
Are separated and opened in monofilament units by the rubbing and rubbing effect, and the resin powder 2 penetrates between the monofilaments, is electrostatically captured and adheres. In this case, the width of the reinforcing fiber bundle 1 is increased to some extent because the fiber is separated and spread in monofilament units. When the reinforcing fiber bundle 1 to which the resin powder 2 has adhered passes between the slitters 30, the excessively adhered resin powder 2 is removed. By adjusting the gap between the slitters 30, the amount of the resin powder 2 attached is adjusted.

The reinforcing fiber bundle 1 to which the resin powder 2 has adhered passes through the take-up driving roll 40 and the pinch roll 41, and is cut into a desired length by the cutter roll 50.
It is dropped and supplied onto the 61 transfer sections 40b and is accumulated to a predetermined thickness. At this time, a gas such as air or nitrogen is blown from the slit-shaped nozzle 90 to the cut and falling reinforcing fiber bundle, and the pressure of this gas allows the reinforcing fiber bundle to be well separated into monofilaments.

The accumulated material 3 dropped and accumulated on the endless belt is transported while being sandwiched between the pair of upper and lower endless belts 60 and 61, supplied to the heating means 70, and heated at a temperature equal to or higher than the melting point of the resin powder 2 to form a filament. Is sufficiently impregnated with the molten resin.

Here, the upper and lower endless belts 60 by the guide roll 71,
The clearance between 61 is adjusted, the aggregate 3 is pressurized in the thickness direction, and the resin powder 2 melted by this pressurization causes the gaps between the monofilaments to be filled, so that the resin and the reinforcing fibers are satisfactorily formed. Be integrated. Subsequently, the upper and lower endless belts 6 are cooled by the cooling guide rolls 80 of the cooling means.
The clearance between 0 and 61 is adjusted, and the heated aggregate 3 is cooled while being pressurized. Thus, the fiber reinforced resin sheet 4 having a predetermined thickness is manufactured.

(Action) As described above, the resin powder is adhered between the filaments of the reinforcing fiber bundle in the fluidized bed, cut into a desired length, and the cut reinforcing fiber bundle is blown with gas to be separated into monofilaments. While falling and accumulating on the endless belt, and supplying the accumulated material between the pair of upper and lower endless belts to heat and integrate, the effect of opening the reinforcing fiber bundle in the fluidized bed and the cut reinforcing fiber bundle is obtained. Combined with the gas blowing effect of
Separation into filament units is sufficiently performed, and the resin is impregnated between the filaments in a sufficient and uniform distribution.
In addition, all the steps can be performed continuously.

(Example) Hereinafter, an example of the present invention will be described.

Example 1 A fiber reinforced resin sheet was manufactured using the apparatus shown in FIG.

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

・ Polyvinyl chloride resin (average degree of polymerization 400, average particle size 150μ)
m) 100 parts by weight ・ Butyltin maleate 3 parts by weight ・ Polyethylene wax ...... 0.5 parts by weight ・ Stearyl alcohol 1 part by weight Monofilament 23 μm in diameter as reinforcing fiber bundle 1
A roving-like glass fiber bundle (about 0.3% by weight of a sizing agent) in which 4000 fibers were converged was used.

Glass cloth reinforced Teflon belts (width: 600 mm, thickness: about 1 mm) were used as the endless belts 60, 61, and the slit-shaped nozzle 90 was set to blow air obliquely downward at an angle of about 45 degrees.

Fluidized bed 2a of the above resin-blended powder 2 with 12 reinforcing fiber bundles 1
After passing through the inside continuously and adhering the resin-containing powder 2 between the monofilaments, excess resin-containing powder was removed by the slitter 30, and the weight ratio of the resin-containing powder to the reinforcing fiber was 7: 3. This was adjusted so that it was cut by the cutter roll 50 to a length of about 25 mm, and was dropped and supplied onto the endless belt 61b. The supply amount was 3320 g / m ^{2 in} a range of about 500 mm in the center of the endless belt 61 b having a width of 600 mm so as to be 3320 g / m ² . At this time, the apparent thickness of the aggregate 3 was about 32 mm.

At this time, air was spouted from the slit-shaped nozzle 90 in a slit shape, and air was almost uniformly blown toward the cut reinforcing fiber bundle being dropped, thereby separating the reinforcing fiber bundle into monofilaments. Next, while holding the stack 3 on the endless belt 61b between the upper and lower endless belts 60 and 61 moving at a speed of 580 mm / min, the minimum gap between the endless belts 60 and 61 is guided by the guide roll 71. Adjust to about 2.1mm,
Heating furnace 70 with a length of about 1500 mm and hot air of about 200 ° C circulating
The resin-containing powder 2 was melted by passing through the inside.

Subsequently, the aggregate 3 in which the resin-blended powder 2 is in a molten state is passed through the minimum gap between the endless belts 60 and 61 by a guide roll.
It was adjusted to about 2 mm by 81 and cooled by the cooling blower 80 to produce the fiber reinforced resin sheet 4. This fiber reinforced resin sheet 4 was about 500 mm in width and about 2 mm in thickness. The resin was well impregnated between the filaments, and the filaments were uniformly dispersed.

A 30 mm x 30 mm test piece was cut out from five random places in the area of 500 mm x 2000 mm on this sheet,
The resin was burned and removed by time treatment, and the content of glass fiber was measured. Further, a test piece having a width of 20 mm and a length of 150 mm was cut out, and a three-point bending test was performed at a distance between fulcrums of 120 mm to measure the bending strength. Table 1 shows the test results.

Example 2 A fiber reinforced resin sheet was manufactured using the apparatus shown in FIG.

As the thermoplastic resin powder 2, a frozen and pulverized powder of a pellet-shaped polypropylene resin (average particle diameter 200 μm) is used. As the reinforcing fiber bundle 1, a monofilament having a diameter of 23 μm is used.
A roving-like glass fiber bundle (about 0.3% by weight of a sizing agent) in which 4000 fibers were converged was used.

Glass cloth reinforced Teflon belts (width: 600 mm, thickness: about 1 mm) were used as the endless belts 60, 61, and the slit-shaped nozzle 90 was set to blow air obliquely downward at an angle of about 45 degrees.

After ten reinforcing fiber bundles 1 are continuously passed through the fluidized bed 2a of the resin powder 2 and the resin blended powder 2 is attached between the monofilaments, the excess resin powder is removed by the slitter 30. The weight ratio between the resin powder and the reinforcing fiber was adjusted to be 6: 4, and the length was adjusted to about 25 by the cutter roll 50.
It was dropped and supplied onto the endless belt 61b while being cut into mm. The supply amount was 3600 g / m ^{2 in} a range of about 500 mm in the center of the endless belt 61 b having a width of 600 mm so as to be 3600 g / m ² . The apparent thickness of the aggregate 3 at this time was about 45 mm.

At this time, air was spouted from the slit-shaped nozzle 90 in a slit shape, and air was almost uniformly blown toward the cut reinforcing fiber bundle being dropped, thereby separating the reinforcing fiber bundle into monofilaments. Next, the minimum gap between the endless belts 60 and 61 is guided by the guide roll 71 while the stack 3 on the endless belt 61b is sandwiched between the upper and lower endless belts 60 and 61 moving at a speed of 500 mm / min. Adjust to about 3.1mm,
Heating furnace 70 with a length of about 1500mm and hot air of about 210 ° C circulating
The resin powder 2 was melted by passing through the inside.

Subsequently, the aggregate 3 in which the resin powder 2 is in a molten state
Guide roll 81 with the minimum gap between endless belts 60 and 61.
, And cooled by a cooling blower 80 to produce a fiber-reinforced resin sheet 4. This fiber reinforced resin sheet 4 was about 500 mm in width and about 3 mm in thickness. The resin was well impregnated between the filaments, and the filaments were uniformly dispersed.

For this sheet, the glass fiber content and the bending strength were measured in the same manner as in Example 1. The test results are
It is shown in the table.

Example 3 A fiber reinforced resin sheet was manufactured using the apparatus shown in FIG.

A nylon-6 resin powder (average particle size of about 80 μm) is used as the thermoplastic resin powder 2, and a roving-like polyacrylonitrile having a width of about 6 mm, in which 6000 monofilaments having a diameter of 7 μm are converged as the reinforcing fiber bundle 10. A system carbon fiber bundle was used.

Glass cloth reinforced Teflon belts (width: 600 mm, thickness: about 1 mm) were used as the endless belts 60, 61, and the slit-shaped nozzle 90 was set to blow air obliquely downward at an angle of about 45 degrees.

After ten reinforcing fiber bundles 1 are continuously passed through the fluidized bed 2a of the resin powder 2 and the resin blended powder 2 is attached between the monofilaments, the excess resin powder is removed by the slitter 30. The weight ratio between the resin powder and the reinforcing fiber was adjusted to be 7.5: 2.5, and this was dropped on the endless belt 61b while being cut by the cutter roll 50 into a length of about 50 mm. The amount of supply is about 50 mm at the center of the 600 mm endless belt 61b.
It was supplied and accumulated to be 3750 g / m ^{2 in} the range of 0 mm. At this time, the apparent thickness of the aggregate 3 was about 30 mm.

At this time, air was spouted from the slit-shaped nozzle 90 in a slit shape, and air was almost uniformly blown toward the cut reinforcing fiber bundle being dropped, thereby separating the reinforcing fiber bundle into monofilaments. Next, the minimum gap between the endless belts 60 and 61 is guided by the guide roll 71 while the stack 3 on the endless belt 61b is sandwiched between the upper and lower endless belts 60 and 61 moving at a speed of 500 mm / min. Adjust to about 3.2mm,
Heating furnace 70 with a length of about 1500 mm and circulating hot air of about 240 ° C
The resin powder 2 was melted by passing through the inside.

Subsequently, the aggregate 3 in which the resin powder 2 is in a molten state
Guide roll 81 with the minimum gap between endless belts 60 and 61.
, And cooled by a cooling blower 80 to produce a fiber-reinforced resin sheet 4. This fiber reinforced resin sheet 4 was about 500 mm in width and about 3 mm in thickness. The resin was well impregnated between the filaments, and the filaments were uniformly dispersed.

For this sheet, the glass fiber content and the bending strength were measured in the same manner as in Example 1. The test results
It is shown in the table.

Comparative Example In Example 1, air was not blown on the cut reinforcing fiber bundle. Other than that, it carried out similarly to Example 1.

About the obtained sheet, the glass fiber content and the bending strength were measured in the same manner as in Example 1. Table 4 shows the test results.

(Effect of the Invention) As described above, according to the method of the present invention, the reinforcing fibers are favorably dispersed in monofilament units, and the resin is sufficiently impregnated between the no-filaments of the reinforcing fibers. , And has excellent physical properties, and the distribution of the reinforcing fibers and the resin is uniform, so that a fiber-reinforced resin sheet having uniform physical properties can be obtained. In addition, productivity can be improved because the process can be performed continuously.

The fiber-reinforced resin sheet obtained by the method of the present invention is not only useful as a particularly tough 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 description of the drawings]

FIG. 1 is a schematic side view showing an example of an apparatus used in the method of the present invention. DESCRIPTION OF SYMBOLS 1 ... Reinforcing fiber bundle, 2 ... Thermoplastic resin powder, 2a ... Fluidized bed of resin powder, 3 ... Aggregate, 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 ... nozzles.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ identification code FI B29L 7:00 (58) Field surveyed (Int.Cl. ⁶ , DB name) B29C 43/00-43/58 B29C 70/00 -70/88 B29B 11/00-11/16 B29B 15/00-15/14

Claims (1)

(57) [Claims] 1. A reinforcing fiber bundle composed of a large number of continuous monofilaments is passed through a fluidized thermoplastic resin powder to adhere the resin powder to the monofilaments of the fiber bundle. The attached fiber bundle is cut to a desired length with a cutter roll, and the cut fiber bundle is dropped and accumulated on an endless belt while being blown with gas to separate it into monofilaments. A method for producing a fiber-reinforced resin sheet, wherein the sheet is heated while being held and transported.