JP3043121B2 - Method for producing fiber composite sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fibrous composite sheet used as a tough plate material or a so-called stampable sheet which is a material for press molding for obtaining various products.

[0002]

2. Description of the Related Art As a method of manufacturing a fiber composite sheet,
(A) Under a jet stream of compressed air, reinforced short fibers and a powdery thermoplastic resin are mixed, dropped on a net, collected, and then transferred to an endless belt that moves, heated, pressurized, and cooled. (Japanese Patent Application Laid-Open No. 59-49929)
And (b) mixing the reinforcing staple fiber and the powdery thermoplastic resin in a container while keeping the same in a fluidized state, taking out the container, dropping it on a moving endless belt, and accumulating it. A method is known in which the sheet is fed into a gap between moving upper and lower endless belts that are opposed to each other at a predetermined interval, heated and pressed, and then cooled to form a sheet (Japanese Patent Laid-Open No. 622-2).
08914).

[0003]

In the method for producing a fiber composite sheet (a), the reinforced short fibers having different specific gravities and the powdery thermoplastic resin are mixed under an air current and dropped and accumulated. There is a problem that the distribution of fibers and resin becomes non-uniform, and the physical properties of the obtained sheet vary greatly. Further, in the method for producing a fiber composite sheet of the above (b), since the reinforcing short fibers and the powdery thermoplastic resin are mixed in a container, the sheet must be continuously obtained without resorting to a batch method. And there is a problem that productivity is poor.

An object of the present invention is to disperse reinforcing fibers in monofilament units and sufficiently impregnate the thermoplastic resin between the monofilaments, and furthermore, the distribution of the thermoplastic resin and the fibers is uniform, and the physical properties are less varied. It is an object of the present invention to provide a method capable of producing a fiber composite sheet with high productivity.

[0005]

In order to achieve the above object, a method for producing a fiber composite sheet according to the present invention comprises forming a reinforcing fiber bundle comprising a large number of continuous monofilaments in a fluidized bed of a powdery thermoplastic resin. And a step of adhering the powdery thermoplastic resin to each monofilament of the fiber bundle, a step of cutting the resin-adhered fiber bundle to a predetermined length, and cutting the cut resin-adhered fibers at predetermined intervals in an oblique direction. A step of bringing the at least two rotating rolls into contact sequentially from above, dropping them on a feeding portion into a gap between the upper and lower endless belts facing each other at a predetermined interval, and accumulating the cut resin-adhered fiber; The process includes feeding an object into a gap between both endless belts and passing the object through a heating and cooling area while forming the sheet between the two endless belts.

As the reinforcing fibers, fibers that are thermally stable at the melting temperature of the thermoplastic resin used are used. Specific examples include organic fibers such as glass fiber, carbon fiber, silicon / titanium / carbon fiber, boron fiber, fine metal fiber, aramid fiber, liquid crystal polymer fiber, polyester fiber, and polyamide fiber.

The diameter of the monofilament is preferably 1 to 50 μm. When using a large number of continuous monofilaments as a reinforcing fiber bundle, a sizing agent may or may not be used,
When used, the amount of the sizing agent attached is preferably 1% by weight or less, more preferably 0.5% by weight or less. If the amount of the sizing agent exceeds 1% by weight, it becomes difficult to separate the fiber bundle into monofilament units in the fluidized bed, and the impregnating property of the thermoplastic resin between the monofilaments decreases.

The reinforcing fiber bundle is in the form of a strand or roving in which continuous monofilaments are composed of hundreds to thousands. These reinforcing fiber bundles are usually used in a large number in parallel in consideration of the width, thickness, manufacturing speed and the like of the fiber composite sheet to be manufactured.

As the powdery thermoplastic resin, any resin that melts and softens upon 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-mentioned thermoplastic resin as a main component, 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 can also be used. And the thermoplastic resin has a stabilizer, a lubricant,
Additives such as processing aids, plasticizers and coloring agents may be blended. Both thermoplastic resins obtained in powder form during polymerization and thermoplastic resins made into powder form by a pulverizer can be used. The average particle diameter is 2000μ.
m or less is preferable. When the average particle size exceeds 2000 μm, it is difficult to uniformly adhere to the monofilament of the reinforcing fiber bundle in the fluidized bed.

The ratio between the thermoplastic resin and the reinforcing fibers is appropriately determined according to the required physical properties of the fiber composite sheet.
It is preferable that the reinforcing fiber content in the sheet is 5 to 70% by weight. If the reinforcing fiber content is less than 5% by weight, the mechanical strength of the sheet is not sufficient, and if it exceeds 70% by weight, it is difficult to obtain a sheet uniformly impregnated with a thermoplastic resin.

The length of the cut resin-adhered fiber is usually 0.5 to
It is 500 mm, particularly preferably 5 to 150 mm. If the length of the cut resin adhering fiber is less than 0.5 mm, the sheet reinforcing effect is small, and if it exceeds 500 mm, it becomes difficult to obtain a homogeneous fiber composite sheet.

[0012]

The method for producing a fiber composite sheet according to the present invention comprises:
First, since the reinforcing fiber bundle consisting of a large number of continuous monofilaments is passed through the fluidized bed of the powdery thermoplastic resin,
In the fluidized bed, the reinforcing fibers are separated and opened into monofilament units by gas discharge and static electricity generated in the fluidized bed or by rubbing and grinding of the thermoplastic resin. Penetrates and is electrostatically captured and adhered to each monofilament. Then, the resin-attached fiber bundle is cut into a predetermined length, and the cut resin-attached fiber is
Since at least two rotating rolls arranged at a required distance in the oblique direction are sequentially contacted from above, the filaments of the fiber bundle are uniformly dispersed. The cut resin-adhered fibers in which the filaments are uniformly dispersed as described above are dropped and accumulated on the feeding portion into the gap between the upper and lower endless belts opposed to each other at a predetermined interval, and the cut resin-adhered fiber aggregate is collected. The thermoplastic resin is fed into the gap between the endless belts and passes through the heating area and the cooling area while being sandwiched between the moving endless belts, so that the thermoplastic resin is sufficiently impregnated between the monofilaments. As a result, the distribution of the thermoplastic resin and the fibers becomes uniform.

[0013]

【Example】

Embodiment 1 First, an apparatus used for carrying out the present invention will be described with reference to the drawings. In the following description, “before” means rightward in FIG.

The apparatus for manufacturing a fiber composite sheet shown in FIG. 1 has a rewinding roll (1) around which a reinforcing fiber bundle (F1) is wound, and is disposed in front of the rewinding roll (1) and is filled with a powdery thermoplastic resin. A fluidized bed apparatus (2) having a tank, a pair of upper and lower scrapers (3) arranged in front of the fluidized bed apparatus (2), and a rewind roll (1) arranged in front of the scraper (3) Take-up drive roll (5) for rewinding the reinforcing fiber bundle (F1) from
And a rotary cutter (7) facing the take-off drive roll (5) in front of and below the pinch roll (6), and a diagonally lower rear of the rotary cutter (7). Four rotating rolls (9) arranged at a required interval diagonally below and forward, upper and lower endless belts (10) and (11) opposed to each other at a predetermined interval, and both endless belts (10)
A heating means (12) and a cooling means (13) are sequentially arranged from the rear side with respect to the opposing transfer section (10a) (11a) of (11), and the rear part of the lower endless belt (11) is It is made to protrude backward from the endless belt (11), and its rear extension part of the transfer part (11a) is located below the four rotating rolls (9), and is inserted into the gap between the endless belts (10) and (11). It is a feeding section (11b). In addition, the transfer section (11a) is extended and the feed section (11
Instead of b), another endless belt may be arranged at the same location to provide the feeding portion.

The tank bottom of the fluidized bed apparatus (2) is formed by a perforated plate (14), and gas (G) such as air or nitrogen sent from a gas supply passage is provided below the perforated plate (14). Through the multiple holes of this. As a result, the powdery thermoplastic resin filled in the tank of the fluidized bed apparatus (2) becomes fluidized by the jet gas (G), and a fluidized bed (R) is formed. A guide bar (15) for guiding the fiber bundle (F1) is provided in the tank of the fluidized bed apparatus (2) and at the upper end of the front and rear walls thereof.

The take-up driving roll (5) and the four rotating rolls (9) are rotated clockwise, and the rotary cutter (7) is rotated counterclockwise.

The rotating direction of the rotating roll (9) is
Although it is appropriately determined according to the configuration of (9), the peripheral speed, the amount of the cut resin-adhered fiber (F3), and the like, it is preferable that the cut resin-adhered fiber (F3) is not gathered at one place but dispersed in multiple directions. .

The distance between the rotating rolls (9) may be equal or different, but the cut resin-adhered fiber (F3)
If the length is not more than 10 times the length, it is effective for fiber opening. When the gap exceeds 10 times, the separation of the filament (F3) from the cut resin-adhered fiber (F3) by the rotating roll (9) is insufficient,
The separated and dispersed state becomes uneven, and the physical properties of the manufactured fiber composite sheet vary.

The arrangement of the rotating rolls (9) is not limited to the one shown in FIG. For example, as shown in FIG. 2, a plurality of rotating rolls arranged at an interval from the top to the front diagonally downward.
(9) are arranged in two rows and the lower row of rotating rolls (9) corresponding to the upper row of rotating rolls (9) is positioned slightly forward, and the two upper row of rotating rolls (9) are positioned in the lower row. Rotating roll
(9) is positioned in front of the front end of (9), and only the one positioned in front of this is rotated in the direction of rotation of the other rotating roll (9).
The cutting resin-attached fiber (F3) may be correctly dropped to a predetermined location of the feeding portion (11b). As shown in FIG. 3, a plurality of rotating rolls (9) arranged at an interval from the top to the front diagonally downward are arranged in four rows, and the number of rotating rolls (9) in each row is made equal. , May be at the same level horizontally.

The peripheral speed of the rotary rolls (9) may be the same or different, but if the peripheral speed of the rotary cutter (7) is lower than that of the rotary cutter (7), the cutting resin is interposed between the rotary rolls (9). Adhered fiber
(F3) stays, and dispersion of the fiber bundle (F3) becomes poor.

As shown in FIG. 4, the rotating roll 9 may be provided with a plurality of fins 20 at predetermined intervals. The fin (20) has eight sharp corners (2
Although (1) is provided radially, the form of the fin is not limited to this, and may be a simple disk.

The two endless belts (10) and (11) are continuously driven substantially in the same direction by driving one of the upper and lower pulleys (16) and (17) by a motor (not shown). It is made to move at the same speed. The rear part of the transfer part (10a) of the upper endless belt (10) is inclined rearward and upward, and the gap between the upper and lower transfer parts (10a) and (11a) widens rearward. The upper and lower endless belts (10) and (11) are formed of, for example, steel, stainless steel, glass cloth reinforced Teflon, or the like having high strength and heat resistance.

As the heating means (12), an electric heating type or a hot air circulation type heating furnace is used, in which the upper and lower endless belts (10) and (11) may be passed. A plurality of pairs of heating rolls which press the transfer units (10a) (11a) of (10) and (11) from above and below and directly heat them may be used. Inside the heating means (12) and inside the vertical cooling means (13), a plurality of pairs of guide rolls (18) and (19) are arranged at corresponding positions in the vertical direction, and a plurality of pairs of guide rolls (18) are provided. The gaps in () and (19) are each adjustable. As the cooling means (13), a blower that blows air to cool the transfer sections (10a) (11a) of the upper and lower endless belts (10) (11) is used. Note that the guide roll (19) itself may be cooled.

Using the above-mentioned apparatus, a reinforcing fiber bundle (F1) 1 comprising a large number of continuous monofilaments from a rewind roll (1)
Take two rolls, take-off drive roll (5) and pinch roll
(6) Rewinding without twisting by
Pass the powdery thermoplastic resin through the fluidized bed (R) to
A powdery thermoplastic resin is attached to each monofilament of (F1).

As the powdery thermoplastic resin, Super
What was previously mixed with the following composition with a mixer was used.

Polyvinyl chloride resin (average degree of polymerization: 400, average particle size: 150 μm) 100 parts by weight Butyl tin maleate 3 parts by weight Polyethylene wax 0.5 parts by weight Stearyl alcohol 1 part by weight Reinforced fiber bundle As (F1), a roving-like glass fiber bundle (about 0.3% by weight of a sizing agent) formed by bunching 4000 monofilaments having a diameter of 23 μm was used. The resin-attached fiber bundle (F2) is passed between a pair of upper and lower scrapers (3), and the excess powdery thermoplastic resin is removed by the scraper (3), and the weight ratio of the powdery thermoplastic resin to the reinforcing fibers is reduced. Adjust to 3: 1. By adjusting the gap between the pair of upper and lower scrapers (3) in this way, the amount of the powdery thermoplastic resin adhered can be adjusted.

The resin-attached fiber bundle (F2) is passed between the take-off drive roll (5) and the pinch roll (6), and then cut by a rotary cutter (7) to a length of about 12.5 mm.
The cut resin-attached fiber (F3) having a short dimension is used.

The cut resin-adhered fiber (F3) is sequentially brought into contact with the four rotating rolls (9) from above, spread to monofilament units, and uniformly dispersed.
0) Drop naturally on the feeding section (11b) into the gap of (11) and accumulate. The amount of accumulation was 5050 g / m ² over a range of about 500 mm at the center of the feeding portion (11b) of the lower endless belt (11) having a width of 600 mm. The apparent thickness of the aggregate (F4) at this time was about 48 mm.

As the rotating roll (9), a roll having a diameter of 60 mm and a peripheral speed of the roll of 50 m is used. The upper and lower endless belts (10) and (11) are used.
A glass cloth reinforced Teflon belt having a width of 600 mm and a thickness of about 1 mm was used.

Cut the resin-attached fiber assembly (F4) to 580 mm
The minimum gap between the endless belts (10) and (11) is adjusted to about 3.1 mm by the upper and lower guide rolls (18) while sandwiching the upper and lower endless belts (10) and (11) moving at a speed of / min. Press the cut resin-attached fiber assembly (F4) in the thickness direction and apply a length of about 1500 mm
Then, the hot air of about 200 ° C. is circulated through a heating furnace (12) as a heating means to melt the powdery thermoplastic resin and impregnate the molten resin between the filaments. Aggregate
By pressing (F4) in the thickness direction, the molten thermoplastic resin flows and fills the gaps between the monofilaments, so that the thermoplastic resin and the reinforcing fibers are surely integrated.

Subsequently, the mixture of the resin and the reinforcing fibers in the molten state is pressed by adjusting the minimum gap between the upper and lower endless belts (10) and (11) to about 3 mm by the upper and lower guide rolls (19), and It was cooled by a cooling blower (13) as a cooling means to obtain a fiber composite resin sheet (S). This fiber composite resin sheet (S) has a width of about 500 mm and a thickness of about 3 mm,
The thermoplastic resin was well impregnated between the filaments, and the filaments were uniformly dispersed.

Test pieces of 30 mm × 30 mm were randomly cut from five places of the above fiber composite sheet of 500 mm × 2000 mm, treated at 700 ° C. for 5 hours to incinerate and remove the resin component, and the content of glass fiber was reduced. It was measured. Also 20mm
A test piece of × 150 mm was cut out and subjected to a three-point bending test at a distance between supporting points of 120 mm to measure the bending strength. Table 1 shows the results.

[0033]

[Table 1]

Embodiment 2 In this embodiment, in the apparatus of FIG. 1, nine rotating rolls (9) are arranged as shown in FIG. 2, and each roll (9) is provided with a fin as shown in FIG. (20) used was attached at an interval of 12.5 mm. That is, the diameter 6
A row of 0mm rotating rolls (9) arranged six rows diagonally downward and forward, and a row of rotating rolls below
(9) There is one row which is shifted obliquely downward three places in front, and each rotating roll (9) has a fin (20) having eight corners (21) radially of 12.5 mm. Installed at intervals. These rotating rolls (9) were rotated at a peripheral speed of 50 m in the directions shown by arrows in FIG.

As the powdery thermoplastic resin, a frozen pulverized powder of a pelletized polypropylene resin (average particle diameter 200 μm) is used.
m) and as a reinforcing fiber bundle (F1), a diameter of 23 μm
Approximately 8 width of 4000 monofilaments bundled
mm roving glass fiber bundle (Bundling agent adhesion amount about 0.3
10% by weight).

The resin-adhered fiber bundle (F2) obtained through the same steps as in Example 1 is passed between a pair of upper and lower scrapers (3), and excess powdery thermoplastic resin is removed by the scrapers (3). Then, the weight ratio between the powdery thermoplastic resin and the reinforcing fibers is adjusted to be 6: 4.

The resin-attached fiber bundle (F2) is passed between the take-up driving roll (5) and the pinch roll (6), and then cut by a rotary cutter (7) to a length of about 25 mm to cut short dimensions. Resin-adhered fiber (F3).

[0038] The cut resin-adhered fiber (F3) is sequentially brought into contact with nine rotating rolls (9), opened to monofilament units, and uniformly dispersed. Then, the gap between the upper and lower endless belts (10) and (11) is separated. Drops naturally on the feeding part (11b) to be collected. The amount of accumulation was set to 4660 g / m ² over a range of about 500 mm at the center of the feeding portion (11b) of the lower endless belt (11) having a width of 600 mm. At this time, the apparent thickness of the aggregate (F4) was about 45 mm. While holding the cut resin-attached fiber assembly (F4) between the upper and lower endless belts (10) and (11) moving at a speed of 500 mm / min,
The minimum gap between 1) is adjusted to about 3.2 mm by the upper and lower guide rolls (18), and the cut resin-adhered fiber assembly (F4) is pressed in the thickness direction to have a length of about 1500 mm and a temperature of about 210 ° C. Hot air is circulated through a heating furnace (12) to melt the powdery thermoplastic resin and impregnate the molten resin between the filaments.

Subsequently, the mixture of the resin and the reinforcing fibers in the molten state is pressurized by adjusting the minimum gap between the upper and lower endless belts (10) and (11) to about 3 mm by the upper and lower guide rolls (19), and cooled. The mixture was cooled by a blower (13) to obtain a fiber composite resin sheet (S). This fiber composite resin sheet (S) has a width of about 5
It had a thickness of about 00 mm and a thickness of about 3 mm. The thermoplastic resin was well impregnated between the filaments, and the filaments were uniformly dispersed.

In the same manner as in Example 1, the glass fiber content and the bending strength of the fiber composite sheet were measured. Table 2 shows the results.

[0041]

[Table 2]

Embodiment 3 In this embodiment, in the apparatus shown in FIG. 1, the rotating roll (9) with the fins (20) and the peripheral speed are the same as those in Embodiment 2, and the arrangement state and the rotating direction are as shown in FIG. And Nylon-6 resin powder (average particle size: about 80 μm) is used as the powdery thermoplastic resin, and the reinforcing fiber bundle (F1) has a diameter of 7 mm.
Ten roving-like polyacrylonitrile-based carbon fiber bundles obtained by bundling 6000 μm monofilaments were used.

The resin-adhered fiber bundle (F2) obtained through the same process as in Example 1 is passed through a pair of upper and lower scrapers (3), and excess powdery thermoplastic resin is removed by the scrapers (3). Then, the weight ratio between the powdery thermoplastic resin and the reinforcing fibers is adjusted to be 8: 2.

The resin-attached fiber bundle (F2) is passed between a take-off drive roll (5) and a pinch roll (6), and then cut to a length of about 50 mm by a rotary cutter (7). The cut resin-adhered fiber (F3) is used.

The cut resin-adhered fiber (F3) is brought into contact with any one of the fins (20) of the nine rotating rolls (9), spread to a monofilament unit, and uniformly dispersed. 10) Drop naturally on the feeding section (11b) into the gap of (11) and accumulate. The amount of accumulation is about 50 mm at the center of the feeding section (11b) of the lower endless belt (11) having a width of 600 mm.
It was adjusted to 2530 g / m ² over a range of 0 mm. At this time, the apparent thickness of the aggregate (F4) was about 32 mm.

Cut the resin-attached fiber assembly (F4) to 500 mm
The minimum gap between both endless belts (10) and (11) is adjusted to about 2.1 mm by the upper and lower guide rolls (18) while sandwiching the upper and lower endless belts (10) and (11) moving at a speed of / min. Press the cut resin-attached fiber assembly (F4) in the thickness direction and apply a length of about 1500 mm
To pass through a heating furnace (12) in which hot air of about 240 ° C. is circulating to melt the powdery thermoplastic resin and impregnate the molten resin between the filaments.

Subsequently, the mixture of the resin and the reinforcing fibers in the molten state is pressurized by further adjusting the minimum gap between the upper and lower endless belts (10) and (11) to about 2 mm by the upper and lower guide rolls, and the cooling blower ( 13) to obtain a fiber composite resin sheet (S). This fiber composite resin sheet (S) has a width of about 5
It had a thickness of about 00 mm and a thickness of about 2 mm. The thermoplastic resin was well impregnated between the filaments, and the filaments were uniformly dispersed. In the same manner as in Example 1, the glass fiber content and the bending strength of the fiber composite sheet were measured. Table 3 shows the results.

[0048]

[Table 3]

[0049]

According to the production method of the present invention, the reinforcing fibers are well dispersed in monofilament units, and the resin is sufficiently impregnated between the monofilaments, so that the reinforcing effect of the reinforcing fibers is high. Has excellent physical properties,
In addition, since the distribution of the reinforcing fibers and the resin is uniform, a fiber composite sheet having uniform physical properties can be obtained. In addition, productivity is good because the process is continuous.

[Brief description of the drawings]

FIG. 1 is a schematic vertical cross-sectional view of an entire apparatus used for carrying out the present invention.

FIG. 2 is a side view showing another example of an arrangement state of a plurality of rotating rolls.

FIG. 3 is a side view showing still another example of an arrangement state of a plurality of rotating rolls.

FIG. 4 is a perspective view of a rotating roll with fins.

[Explanation of symbols]

 (R) Fluidized bed of powdered thermoplastic resin (F1) Reinforced fiber bundle (F2) Resin-attached fiber bundle (F3) Cut resin-attached fiber (F4) Cut resin-attached fiber aggregate (9) On rotating roll (10) Endless belt (11) Lower endless belt (11b) Feeding part (12) Heating means (13) Cooling means (S) Fiber composite sheet

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI B29K 105: 12 B29L 7:00 (58) Investigated field (Int.Cl. ⁷ , DB name) B29B 11/16 B29B 15/08 -15/14 B29C 43/22-43/48

Claims (1)

(57) [Claims] A) passing a reinforcing fiber bundle comprising a large number of continuous monofilaments through a fluidized bed of a powdery thermoplastic resin, and adhering the powdery thermoplastic resin to each monofilament of the fiber bundle; b) cutting the resin-attached fiber bundle to a predetermined length; and c) sequentially contacting the cut resin-attached fibers with at least two rotating rolls arranged at a required interval in a diagonal direction from above, and A step of dropping and accumulating the upper and lower endless belts, which are opposed to each other at an interval, into a feed portion into a gap, and d) feeding the cut resin-adhered fiber aggregate into the gap between the endless belts and moving the endless belt Forming a sheet by passing the sheet through a heating and cooling area while sandwiching the sheet with a belt.