JPH0737040B2 - Method for manufacturing fiber composite sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for producing a fiber composite sheet used for a tough plate material, a so-called stamped-up sheet, which is a material for press molding for obtaining various products, and the like. Regarding

[Conventional technology]

As a method for producing a fiber composite sheet, a mixture of a powder-paired thermoplastic resin and reinforcing fibers is heated and pressurized while being conveyed by a conveyor belt to melt the thermoplastic resin, and the resin is placed between the reinforcing fibers. It is known to impregnate it and then cool it under pressure to form a sheet in which the resin and fibers are unified (JP-A-59-49929 and JP-A-62).
-208914 gazette).

[Problems to be Solved by the Invention]

In the former method, the powder-paired thermoplastic resins having different specific gravities and the reinforcing fibers are mixed under an air stream, and are dropped and accumulated, so that the distribution of the resin and the fibers becomes nonuniform, and the dispersion of the physical properties becomes large. There is a problem. In the latter method, the powdery thermoplastic resin and the reinforcing fibers are mixed in the mixing container, so that the batch method is unavoidable and the sheet cannot be continuously obtained, resulting in poor productivity. There is a problem.

An object of the present invention is to provide a fiber composite sheet in which reinforcing fibers are dispersed in monofilament units and a thermoplastic resin is sufficiently impregnated between the monofilaments, and the distribution of the thermoplastic resin and the fibers is uniform and the physical properties of the composite sheet are small. It is to provide a method for continuously manufacturing

[Means for Solving the Problems]

The method for producing a fiber composite sheet of the present invention, in order to achieve the above object, a reinforcing fiber bundle composed of a large number of continuous monofilaments is passed through a fluidized bed of a powdery thermoplastic resin to obtain each monofilament of the fiber bundle. A step of adhering the powdery thermoplastic resin to the step, a step of cutting the resin-attached fiber bundle to a predetermined length, and a step of passing the cut resin-attached fiber bundle from at least a pair of rotating rolls at a predetermined interval. The process of dropping and stacking on the feeding part into the gap between the upper and lower endless belts facing each other, and feeding the cut resin-adhered fiber bundle aggregate into the gap between the two endless belts, and moving it with the two endless belts moving. And a step of forming a sheet by passing through the heating area and the cooling area.

As the reinforcing fibers, fibers that are thermally stable at the melting temperature of the thermoplastic resin used are used. Specific examples thereof include 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, econol fibers, polyester fibers and polyamide fibers. .

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, but when used, the amount of the sizing agent attached is preferably 1% by weight or less, more preferably 0.5%. It is less than or equal to weight%. The amount of sizing agent attached is 1
When the content exceeds 10% by weight, it becomes difficult to separate the fiber bundle into monofilament units in the fluidized bed, and impregnability of the thermoplastic resin between the monofilaments decreases.

The reinforcing fiber bundle is a strand-like or roving-like one in which several hundred to several thousand continuous monofilaments are formed. In consideration of the width, thickness, production speed, etc. of the fiber composite sheet to be produced, a large number of the reinforcing fiber bundles are usually used in parallel.

As the powdery thermoplastic resin, 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 or graft resins or 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. The thermoplastic resin includes a stabilizer, a lubricant, a processing aid,
Additives such as plasticizers and colorants may be added. Further, both a thermoplastic resin obtained in powder form at the time of polymerization and a thermoplastic resin made into powder form by a pulverizer can be used. The average particle size is preferably 2000 μm or less. When the average particle diameter exceeds 2000 μm, it becomes difficult to uniformly attach the powdery thermoplastic resin to each monofilament of the reinforcing fiber bundle in the fluidized bed.

The mixing ratio of the powdery thermoplastic resin and the reinforcing fiber is appropriately determined depending on the required physical properties of the fiber composite sheet, but the reinforcing fiber in the sheet is preferably 5 to 70% by weight. If the reinforcing fiber content is less than 5% by weight, the mechanical strength of the sheet will not be sufficient, and if it exceeds 70% by weight, it will be difficult to obtain a sheet uniformly impregnated with a thermoplastic resin.

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

[Action]

In the method for producing a fiber composite sheet according to the present invention, first, a reinforcing fiber bundle composed of a large number of continuous monofilaments is passed through a fluidized bed of a powdery thermoplastic resin. By the static electricity generated inside and the rubbing and rubbing of the powdery thermoplastic resin, the reinforcing fibers are separated and opened into monofilament units, and the powdery thermoplastic resin enters between the monofilaments and is electrostatically captured by each monofilament. To adhere. Then, the resin-attached fiber bundle is cut into a predetermined length, and the cut resin-attached fiber bundle is passed between at least a pair of rotating rolls from above, so that the filaments of the fiber bundle are uniformly dispersed. The cut resin-attached fiber bundles, in which the filaments are evenly distributed in this way, are dropped and accumulated on the feeding part into the gap between the upper and lower endless belts which are opposed to each other at a predetermined interval, and the cut resin-attached fiber bundles are accumulated. The object is fed into the gap between the two endless belts, and is passed through the heating region and the cooling region while being sandwiched by the moving two endless belts, so that the thermoplastic resin is sufficiently impregnated between the monofilaments. As a result, the thermoplastic resin and the fibers are evenly distributed.

〔Example〕

First Embodiment First, an apparatus used for carrying out the present invention will be described with reference to the drawings. In the following description, the term "front" means the rightward direction in FIG.

The fiber composite sheet manufacturing apparatus shown in FIG. 1 includes an unwinding roll (1) around which a reinforcing fiber bundle (F1) is wound, and a tank disposed in front of the unwinding roll and filled with a powdery thermoplastic resin. A fluidized bed apparatus (2) provided, a pair of upper and lower scrapers (3) arranged in front of the fluidized bed apparatus (2), a widening means (4) arranged in front of the scraper (3), and widening A take-up drive roll (5) and a pinch roll (6) which are arranged in front of the means (4) and for rewinding the reinforcing fiber bundle (F1) from the rewind roll (1), and a pinch roll (6) A rotary cutter (7) facing the take-up drive roll (5) at the lower front, and a pair of rotary rolls (8) (9) arranged below the drive roll (5) and the rotary cutter (7). And endless top and bottom facing each other at a predetermined interval A belt (10) (11), and heating means (12) and cooling means (13) sequentially arranged from the rear side with respect to the opposed transfer portions (10a) (11a) of the endless belts (10) (11). The rear end of the lower endless belt (11) is made to project rearward from the upper endless belt (11), and the rear extension of the transfer part (11a) is a pair of rotating rolls (8).
Both endless belts (10) located below (9)
It is formed as a feeding part (11b) into the gap of (11).
The transfer section (11a) is extended and the feeding section (11b) is extended.
Instead of this, another endless belt may be arranged at the same place to provide the feeding portion.

The tank bottom of the fluidized bed apparatus (2) is formed of a perforated bottom (14), and gas (G) such as air or nitrogen sent from the gas supply passage is supplied from below the perforated plate (14). It is ejected upward through many holes. As a result, the powdery thermoplastic resin filled in the tank of the fluidized bed apparatus (2) is fluidized by the jetted gas (G) to form a fluidized bed (R). A guide roll (1) for guiding the fiber bundle (F1) is provided in the tank of the fluidized bed apparatus (2) and at the upper ends of the front and rear walls thereof.
5) is provided.

A fixed bar is used as the widening means (4).

FIG. 2 shows a pair of rotating rolls (8) for the take-up drive roll (5) and the rotary cutter (7).
The arrangement state of (9) is enlarged and shown. The take-up drive roll (5) and the rear rotation roll (9) are clockwise,
The rotary cutter (7) and the front rotation roll (8) are each rotated counterclockwise.

The gap between the two rotating rolls (8) and (9) is effective for opening the fibers to be 10 times or less the length of the cut resin-attached fiber bundle (F3).
When the gap exceeds 10 times, the separation of the fiber bundle (F3) into filaments is insufficient, the separated state becomes uneven, and the physical properties of the produced fiber composite sheet vary. When the rotating rolls (8) and (9) are rubber-lined, no gap is necessarily required. The peripheral speed of the roll pair may be the same or different, but it is better to be higher than that of the rotary cutter (7). Both rolls (8) are below the peripheral speed of the rotary cutter (7)
During (9), the cut resin-attached fiber bundle (F3) stays and cannot pass through.

Both endless belts (10) and (11) are continuously driven in the same direction at substantially the same speed by driving one of the upper and lower pulleys (16) and (17) respectively by a motor (not shown). It is designed to move. The rear portion of the transfer portion (10a) of the upper endless belt (10) is inclined rearward and upward, and the gap between the vertical transfer portions (10a) and (11a) is widened rearward. The upper and lower endless belts (10, 11) are formed of high strength and heat resistant materials such as steel, stainless steel, and glass cloth reinforced Teflon.

An electric heating type or hot air circulation type heating furnace is used as the heating means (12), and the upper and lower endless belts (10)
(11) may be passed, or a plurality of pairs of heating rolls may be used that directly press the transfer portions (10a) (11a) of the upper and lower endless belts (10) and (11) from above and below and directly heat them. Inside the heating means (12) and inside the upper and lower cooling means (13), a plurality of pairs of guide rolls (18) (1
9) are respectively arranged, and the gaps between the plurality of pairs of guide rolls (18) and (19) are adjustable. As the cooling means (13), the upper and lower endless belts (1
A blower for blowing air to cool the transfer parts (10a) and (11a) of 0) and (11) is used. In addition, the guide
The roll (19) itself may be cooled.

Using the above device, 12 windings of the reinforcing fiber bundle (F1) consisting of a large number of continuous monofilaments from the rewinding roll (1) are wound by the take-up drive roll (5) and the pinch roll (6) without twisting. Return it and let it pass through the fluidized bed (R) of the powdery thermoplastic resin to obtain a fiber bundle (F1)
The powdered resin is attached to each monofilament.

As the powdery thermoplastic resin, a mixture prepared in advance with a super mixer in the following formulation 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 As the reinforcing fiber bundle (F1), 4000 monofilaments with a diameter of 23 μm are converged. A roving-like glass fiber bundle of about 8 mm (both about 0.3% by weight of the sizing agent attached) was used.

A pair of upper and lower scrapers (3) for the resin-attached fiber bundle (F2)
Then, the excess powdery thermoplastic resin is removed by a scraper (3), and the weight ratio of the powdery thermoplastic resin to the reinforcing fibers is adjusted to 7: 3. By adjusting the gap between the pair of upper and lower scrapers (3) in this manner, the amount of the powdery thermoplastic resin attached can be adjusted.

The resin-adhered fiber bundle (F2) with the amount of resin adhering adjusted is made wider by the widening means (4) than the original width, that is, the width of the reinforced fiber bundle (F1) before resin adhesion. The degree of widening is generally about 1.2 to 50 times the original width, preferably about 2 to 50 times, but here, it is about 3.75 times the original width and is increased to 30 mm.

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

Cut resin-attached fiber bundle (F3) to a pair of rotating rolls (8)
After passing through the space (9) from above, the monofilament unit is opened and uniformly dispersed, and then naturally dropped onto the feeding part (11b) into the gap between the upper and lower endless belts (10) and (11). Accumulate. The accumulated amount is about 500 mm at the center of the feeding part (11b) of the lower endless belt (11) with a width of 600 mm.
Was set to 3320 g / m ² over the range of. The apparent thickness of the aggregate (F4) at this time was about 32 mm.

The rotating rolls (8) and (9) have a diameter of 60 mm and a peripheral speed of 50 m, and the upper and lower endless belts (10) and (11) have a width of 600 mm and a thickness of about 1 mm reinforced Teflon glass cloth. A belt was used.

While sandwiching the cut resin-attached fiber bundle aggregate (F4) with the upper and lower endless belts (10) and (11) moving at a speed of 580 mm / min, the minimum gap between the endless belts (10) and (11) is moved up and down. guide·
A heating furnace as a heating means that adjusts the thickness to about 2.1 mm with a roll (18) and pressurizes the cut resin-adhered fiber bundle aggregate (F4) in the thickness direction to circulate hot air of about 200 mm at a length of about 1500 mm. (12) Pass through the resin to melt the powdery thermoplastic resin and impregnate the filaments with the molten resin. By pressing the aggregate (F4) in the thickness direction, the molten thermoplastic resin flows to fill the voids between the monofilaments, and the thermoplastic resin and the reinforcing fibers are surely integrated.

Subsequently, the mixture of the resin and the reinforcing fiber in the molten state is pressurized by 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 (19), and as a cooling means. It cooled by the cooling blower (13) and obtained the fiber composite resin sheet (S). The fiber composite resin sheet (S) had a width of about 500 mm and a thickness of about 2 mm, the thermoplastic resin was well impregnated between the filaments, and the filaments were uniformly dispersed.

From 5 points of the above 500mm x 20000mm fiber composite sheet, 30
mm × 30 mm test pieces were randomly cut out, treated at 700 ° C. for 5 hours to remove the resin component by burning, and the glass fiber content was measured. Similarly, a 20 mm × 150 mm test piece was cut out and a three-point bending test was performed at a distance between fulcrums of 120 mm to measure bending strength. The test results are shown in Table 1.

Example 2 In this example, in the apparatus of FIG. 1, only the rotating rolls having a plurality of pairs shown in FIG. 3 were used. That is, a plurality of pairs of rotating rolls (8) and (9) having a diameter of 60 mm are sequentially arranged obliquely downward and forward, and
The short-sized resin-attached fiber bundle (F3) cut by the cutter (7) sequentially drops from the top onto the lower rear rotation roll (9), which rotates counterclockwise with the roll (9). It is designed so that it is guided between the front rotating roll (8). The peripheral speed of the rear rotation roll (9) was 50 m, and the peripheral speed of the front rotation roll (8) was 5 m.

As the powdery thermoplastic resin, frozen pulverized powder (average particle diameter 200 μm) of pelletized polypropylene resin was used, and as the reinforcing fiber bundle (F1), 4000 monofilaments with a diameter of 23 μm were converged to a width of about 8 mm. 10 roving glass fiber bundles (amount of sizing agent attached of about 0.3% by weight) were used.

Resin-attached fiber bundle (F) obtained through the same steps as in Example 1
2) is passed between the upper and lower scrapers (3),
Excess powdered thermoplastic resin was removed by scraper (3), and the weight ratio of powdered thermoplastic resin and reinforcing fiber was 6:
Adjust to become 4.

A widening means (4) for the fiber bundle (F2) whose resin adhesion amount is adjusted
The width is increased to 50 mm, which is about 6.25 times the original width.

The widened resin-attached fiber bundle (F3) is cut by a rotary cutter (7) to a length of about 25 mm to obtain a cut resin-attached fiber bundle (F3) with a short dimension.

After passing the cut resin-attached fiber bundle (F3) from above between a plurality of pairs of rotating rolls (8) and (9), the upper and lower endless belts (10) and (11) are fed into the gap (11b) of the feeding portion (11b). Drop on top and collect. The accumulated amount is about 500 mm at the center of the feeding part (11b) of the lower endless belt (11) with a width of 600 mm.
Was set to be 3600 g / m ² over the range. The apparent thickness of the aggregate (F4) at this time was about 45 mm.

An upper and lower endless belt (10) having the same structure as in Example 1, which moves the cut resin-attached fiber bundle assembly (F4) at a speed of 500 mm / min.
While sandwiching with (11), the minimum gap between both endless belts (10) and (11) was adjusted to about 3.2 mm by the upper and lower guide rolls (18), and hot air of about 210 ° C circulated with a length of about 1500 mm. The powdery thermoplastic resin is melted by passing through the heating furnace (12) which is being heated, and the molten resin is impregnated between the filaments.

Subsequently, the molten resin and reinforcing fiber mixture was cooled by the cooling blower (13) 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). Then, a fiber composite resin sheet (S) was obtained. The fiber composite resin sheet (S) had 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.

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

Example 3 In this example, in the apparatus of FIG. 1, only the rotating rolls having a plurality of pairs shown in FIG. 4 were used. That is, for a pair of rotating rolls (8) and (9) arranged alternately in the front-rear direction and displaced in the front-back direction, and for the pair that is shifted forward, the auxiliary roll (which rotates in the same direction after the rear-rotating roll (9)). 20)
However, in the pair shifted later, the auxiliary rolls (21) that rotate in the same direction are arranged side by side in front of the front rotation roll (8), respectively. )
Are sequentially dropped from the top onto the subordinate roll (20) or sub roll (15), which is guided between the front and rear rotary rolls (8) and (9) by its rotation. The diameter of the rolls (8), (9), (20) and (21) was 75 mm, and the peripheral speed was 50 m.

As the powdery thermoplastic resin, nylon-6 resin powder (average particle size of about 80 μm) is used, and as the reinforcing fiber bundle,
Ten roving-shaped polyacrylonitrile-based carbon fiber bundles having a width of about 6 mm formed by converging 6000 monofilaments having a diameter of 7 μm were used.

The resin-attached fiber bundle (F2) obtained through the same steps as in Example 1 was passed between a pair of upper and lower scrapers (3),
Excess powdered thermoplastic resin was removed by scraper (3), and the weight ratio of powdered thermoplastic resin and reinforcing fiber was 7.
Adjust to be 5: 2.5.

A widening means (4) for the fiber bundle (F2) whose resin adhesion amount is adjusted
The width is increased to 25 mm, which is about 4.17 times the original width.

The widened resin-attached fiber bundle (F2) is cut by a rotary cutter (7) to a length of about 50 mm to obtain a cut resin-attached fiber bundle (F3) having a short dimension.

After passing the cut resin-attached fiber bundle (F3) from above between a plurality of pairs of rotating rolls (8) and (9), the upper and lower endless belts (10) and (11) are fed into the gap (11b) of the feeding portion (11b). Drop on top and collect. The accumulated amount is about 500 mm at the center of the feeding part (11b) of the lower endless belt (11) with a width of 600 mm.
Was set to 3750 g / m ² over the range. The apparent thickness of the aggregate (F4) at this time was about 30 mm.

An upper and lower endless belt (10) having the same structure as in Example 1, which moves the cut resin-attached fiber bundle assembly (F4) at a speed of 500 mm / min.
While sandwiching with (11), the minimum gap between both endless belts (10) and (11) was adjusted to about 3.2 mm by the upper and lower guide rolls (18), and a hot air of about 240 ° C circulated with a length of about 1500 mm. Then, the powdery thermoplastic resin was melted by passing through a heating furnace (12) in which the molten resin was impregnated.

Subsequently, the mixture of the resin and the reinforcing fiber in the molten state was further adjusted by the upper and lower guide rolls so that the minimum gap between the upper and lower endless belts (10) and (11) was about 3 mm, and cooled by the cooling blower (19). A fiber composite resin sheet (S) was obtained. The fiber composite resin sheet (S) had 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.

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

Effect of the Invention According to the production method of the present invention, the reinforcing fibers are well dispersed in the monofilament unit, and the reinforcing fibers are sufficiently impregnated with the resin even between the monofilaments, so that the reinforcing effect of the reinforcing fibers is high. Since the fiber composite sheet has excellent physical properties and the reinforcing fiber and the resin are evenly distributed, a fiber composite sheet having uniform physical properties can be obtained. Moreover, productivity is good because the process is continuous.

[Brief description of drawings]

The drawings show the apparatus used to carry out the invention,
1 is a schematic vertical sectional side view of the entire apparatus, and FIG. 2 is a first embodiment.
FIG. 3 is an enlarged side view showing an arrangement state of a pair of rotating rolls with respect to the take-up drive roll and the rotary cutter used in FIG. 3, and FIGS. 3 and 4 are the take-up drive roll and the rotary cutter used in Example 1 and Example 2, respectively. FIG. 6 is an enlarged side view showing an arrangement state of a plurality of pairs of rotating rolls with respect to FIG. (F1) …… Reinforced fiber bundle, (F2) …… Resin-attached fiber bundle,
(F3) …… Cut resin-attached fiber bundle, (F4) …… Cut resin-attached fiber bundle aggregate, (8) (9) …… Rotating roll, (10)
…… Upper endless belt, (11) …… Lower endless belt, (11b)
…… Sending unit, (12) …… Heating means, (13) …… Cooling means, (S) …… Fiber composite sheet.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B29K 105: 12 B29L 7:00

Claims (1)

[Claims] 1. A) A reinforcing fiber bundle (F1) consisting of a large number of continuous monofilaments is passed through a fluidized bed (R) of a powdery thermoplastic resin, and each monofilament of the fiber bundle (F1) is powdered. At least a pair of rotating rolls (8) and (9) are used to attach the thermoplastic resin, b) cut the resin-attached fiber bundle (F2) to a predetermined length, and c) cut the resin-attached fiber bundle (F3). ) Between the upper and lower endless belts (10) faced each other at a predetermined interval after passing between
(11) A step of dropping and accumulating on the feeding part (11b) into the gap, and (d) feeding the cut resin-adhered fiber bundle aggregate (F4) into the gap between both endless belts (10) and (11), A process for producing a fiber composite sheet, which comprises a step of passing through a heating region and a cooling region to form a sheet while being sandwiched by both endless belts (10) (11) which move.