JP3136704B2 - Strand widening die and prepreg manufacturing method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strand widening die and a method for producing a prepreg using the same. More specifically, the present invention relates to a prepreg using a thermoplastic resin as a matrix, particularly a tape-shaped prepreg, under high productivity. The present invention relates to a strand widening die used for continuous production of a prepreg and a method for producing a prepreg using the same.

[0002]

2. Description of the Related Art Composite materials (hereinafter referred to as FRTP) in which a thermoplastic resin is reinforced with inorganic fibers such as carbon fibers and glass fibers, and organic fibers such as aramid fibers and polyester fibers, are made of a thermosetting resin. Compared with composite materials (hereinafter referred to as FRP), which have enhanced impact resistance and moldability, the space and aviation field, the automotive industry field,
Demand is expected to increase in various industrial fields such as the energy field, sports goods field and leisure goods field.

[0003] As a method for producing such FRTP,
For example, a roving separated into individual strands (continuous fiber bundles) is passed through a thermoplastic resin powder to adhere the powder to each strand, and then the whole is heated to a temperature equal to or higher than the melting point of the powder to melt. Then, there is a method of combining the two (see Japanese Patent Publication No. 52-3985). Japanese Patent Application Laid-Open No. 60-36136 discloses that, after a strand or a strip thereof is passed through a molten thermoplastic resin, the strand or the strip is pressed by a plate-like heating roller to form a gap between each single yarn. A method for impregnating a thermoplastic resin is disclosed.

Further, Japanese Patent Application Laid-Open No. H2-222336 discloses a method in which a thermoplastic resin is dissolved in an organic solvent, this solution is impregnated into strands to form an intermediate prepreg, and finally, the solvent is volatilized. Also, Japanese Patent Application Laid-Open No. 64-1
In the 6612 publication, the strand is widened in advance,
There is disclosed a method in which a molten resin is impregnated between single yarns by passing through a molten thermoplastic resin in that state.

[0005] Among these methods, the method of producing FRTP by impregnating a thermoplastic resin melted between heats between the single yarns has a lower production cost and is easier to post-process than other methods. In this respect, it can be said that it is industrially useful. However, thermoplastic resins generally have a higher viscosity when melted than thermosetting resins. It is quite difficult to impregnate the high-viscosity molten resin uniformly and continuously between the individual yarns of the strand, and this is a major problem when producing a prepreg by the molten resin impregnation method. Has become.

In order to solve the above problem, for example, a plurality of impregnating rollers are arranged in a crosshead to which a molten thermoplastic resin is supplied in a direction perpendicular to the running direction of the strand, and the strand is impregnated with the impregnated rollers. A method has been proposed in which the strands are widened by alternately spanning the roller surfaces of the rollers and continuously running under tension, and at the same time, the molten resin is impregnated between the single yarns and then pulled out from the crosshead (Japanese Patent Laid-Open No. Hei 1 (1994)). -263005).

However, in the case of this method, the strands that are continuously running under tension are always in pressure contact with the impregnating roller, so that the frictional force generated at that time tends to cause fluff on the strands. Also, if the traveling speed of the strand is increased for the purpose of improving productivity, the strand is alternately laid over the impregnating rollers and is bent in a “C” shape, so that the tension of the strand becomes too large, and Problems such as inability to cut or wind the yarn are likely to occur. If the degree of bending is reduced in order to reduce the tension, the pressure contact between the strand and the impregnating roller deteriorates, and the impregnation of the strand with the molten resin does not proceed satisfactorily. It happens frequently.

In Japanese Patent Application Laid-Open No. 1-178411, a strand is continuously run under tension in a molten resin in a die. At that time, the strand is pressed at right angles to the running direction by a pressing member. A method has been proposed in which the molten resin is pushed between the single yarns at the same time as the width is increased. However, in the case of this method as well,
As in the method described in Japanese Patent Application Laid-Open Publication No. H10-260, there is a problem that fluff is likely to be generated in the strand because the continuously running strand and the pressing member are in pressure contact with each other in the die.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in a continuous prepreg manufacturing method in which a strand is widened and impregnated with a thermoplastic resin melted between single yarns, and a fluff in the strand is solved. Generation can be prevented, and the strand does not expand by applying another external force.Moreover, the impregnating property of the molten resin between the single yarns can be improved, and the strand can be continuous at a high speed. An object of the present invention is to provide a strand widening die that can be run and a method for manufacturing a prepreg using the same.

[0010]

In order to achieve the above-mentioned object, according to the present invention, a strand inlet is formed at one end and a prepreg precursor outlet is formed at the other end, and the strand runs inside. A die having a convex curved surface portion extending in a direction intersecting with a running direction of a strand and bulging downward.
A side bar member and a lower bar having a convex curved surface portion bulging upward.
A pair of bar members composed of the over member is arranged to oppose to each other the upper and lower convex curved portion between these convex curved portion
A strand widened portion obtained by forming a desired gap, the strands widened portion, and the molten resin filling portion arranged into a strand inlet side provided, it flows together with the strands melt
When the resin passes through the gap, the gap causes
Generates film pressure of molten resin in the direction perpendicular to the flow direction of the fat
And cross the strand with the running direction by the film pressure
A strand widening die characterized by widening in the direction is provided, and the strands are introduced into the die from the strand introduction port of the widening die in a tensioned state, and run through the molten resin filling portion. A method for producing a prepreg is provided, wherein a prepreg precursor in the form of a tape is formed by passing the prepreg precursor through a gap in a strand widening portion, and then the prepreg precursor is led out from an outlet of a die.

[0011]

According to the principle of fluid lubrication in hydrodynamics, a lubricating substance flows between two opposing surfaces.
When the distance between two surfaces is narrowed along the flow direction of the lubricating substance, a lubricating film pressure is generated in the flowing lubricating substance in a direction orthogonal to the flow direction, and the lubricating substance is moved in the width direction. Widen.

The strand widening portion in the die of the present invention utilizes the above-described drawing film function (squeeze function). That is, the convex curved surface of the bar member of a pair that make up the strand widening section corresponds to two opposite faces described above, also used molten resin is equivalent to a lubricating material described above.

[0013] Each convex curved surface portion than are opposed to each other at a desired interval while extending in a direction intersecting the flow direction of the molten resin may flow into a gap the convex curved portion is formed When the coming molten resin passes through this gap, a membrane pressure is generated in a direction orthogonal to the flow direction . Therefore,
When the strand runs along with the molten resin, when the strand passes through the gap between the respective convex curved surface portions, the strand intersects with the traveling direction by receiving the film pressure generated in the molten resin by the squeezing film action. The width is increased in the direction.

At the same time, since the widening of the strand proceeds in a state coexisting with the molten resin, each single yarn of the widened strand is surrounded by the molten resin, and the strand is impregnated with the molten resin. Goes very smoothly.

[0015]

FIG. 1 is a schematic view showing an entire apparatus for manufacturing a tape-shaped prepreg by incorporating the strand widening die of the present invention. In the figure, a feeder 2 capable of applying a tension to a strand 1 with a powder clutch while feeding a desired number of strands 1, a guide 3 for introducing the strand 1 into a strand widening die 6 described below, and an extruder main body 7, a cooling bath 8, a dryer 9,
The winding machine 10 is arranged in series in this order.
The extruder body 7 includes a hopper 4, a barrel portion 5, and a strand widening die 6. The thermoplastic resin in the hopper is heated and melted in the barrel portion 5, and is extruded into the strand widening die 6. It is supposed to be.

In this apparatus, the strand 1 continuously fed from the feeder 2 is introduced into the strand widening die 6 via the guide 3 in a tensioned state under tension, and widened there. Simultaneously, it is formed into a prepreg precursor by being compounded with the molten resin supplied from the barrel portion 5, and then the prepreg precursor is cooled in a cooling bath 8, dried in a drier 9, and then wound up. It is wound up at 10 to form the desired prepreg.

The strand is made of carbon fiber, glass fiber,
High strength and high modulus of elasticity such as ceramic fibers such as boron nitride fiber, silicon carbide fiber, and alumina fiber, metal fibers such as iron fiber and stainless steel fiber, and organic fibers such as polyimide fiber and polyamideimide fiber. Consists of fibers. As a strand, the thickness is 3-5
A bundle of about 1000 to 50,000 single yarns of about 0 μm is used. At this time, it is preferable to use a non-twisted yarn, that is, a non-twisted yarn, since the strand widening in the die described later can be smoothly advanced.
Further, the strand may be formed in advance into a flat shape as a whole.

When a strand is continuously fed from the feeder 2, a tension of about 10 to 100 g per strand is applied to the strand so that the running in the apparatus is performed in a tension state. As the thermoplastic resin impregnated in the strand, for example, nylon 6 or nylon 6
6, such as polyamide resins or their various copolymers, polyester resins such as polyethylene terephthalate resin or polybutylene terephthalate resin or their various copolymers, polycarbonate resins, polyamide imide resins, polyphenylene sulfide resins, polyphenylene oxide resins, Polysulfone resins, polyethersulfone resins, polyetheretherketone resins, polyetherimide resins, various polyolefin resins, and the like can be used.

The thermoplastic resin is heated and melted in the barrel portion 5 and extruded into the die 6, and the viscosity of the molten resin at that time is preferably about 50 to 10,000 poise. If the viscosity is too low, the film pressure generated in the gap of the strand widening portion may be small and the widening of the strand may not proceed sufficiently, and if the viscosity of the molten resin is too high, in the gap, Shearing force is generated in the molten resin, the film pressure is reduced, and the widening of the strand may not proceed sufficiently.

Next, an example of the strand widening die 6 is shown in FIG. 2 as a longitudinal sectional view. The die 6 is configured by combining a head block 11, a die main body 12, and a nozzle portion 13 in the above-described order in which the head block 11 is disposed on the upstream side. A cavity is formed in which the prepreg precursor 1 ′ molded in the section travels.

A strand inlet 11a is formed at the upstream end of the head block 11, and an internal cavity 11b of the head block communicates with a molten resin extrusion port (not shown) from the barrel. The tip portion is connected to the strand inlet 12a of the die body 12. The inlet 11a of the head block 11 has a strand passage 14a at the center to prevent backflow of the molten resin supplied to the cavity 11b, and the tip is a nozzle structure 14b.
The jig 14 shown in FIG.

[0022] cavity portion 12b of the interior of the die body 12,
Bar members 15, 15 of a pair is, convex curved portions 15a, 15a
Are arranged in a state of facing each other, thereby forming the strand widening portion A. Therefore, the die body 12
Cavity portion 12 on the upstream side of the strand widening portion A in FIG.
c, the strand introduction port 12a to the die body 12, and the cavity 11b of the head block are filled with the molten resin from the barrel 5, and a filling section B of the molten resin is constituted as a whole. ing.

FIG. 3 is a perspective view showing the widened portion A of the strand. In the strand widening portion A, a direction in which one surface intersects the traveling direction of the strand 1 (a direction perpendicular to the drawing).
The bar members 15, 15 of a pair that has a convex curved portion 15a extending, and forming a gap w are arranged so that their convex curved portions 15a, 15a are opposed. As the curved shape of the convex curved surface portions 15a, 15a of each bar member,
Curve shapes that are obtained by proportionally enlarging or reducing the curve part near the axis of symmetry in curves represented by exponentiation functions, hyperbolic functions, and elliptic functions, and those that combine these curve shapes symmetrically or asymmetrically Can be adopted.

Note that, as shown in FIG.
The surfaces on the upstream side and the downstream side of the convex curved surface portion 15a may be flat surfaces 15c, 15c, respectively, and the convex curved surface portions 15a, 15a of the bar members 15, 15 may be arranged to face each other to form a strand widening portion. . The interval of the gap w formed between the convex curved surface portions of each bar member is 3 to 150 times the diameter of the single yarn (monofilament) constituting the strand 1 supplied here.
Times, preferably 5 to 100 times.

When the gap w is smaller than three times the diameter of the single yarn of the strand 1, when the strand 1 passes through the gap w, the strand 1 and the convex curved surface portions 15a, 15a of the bar member are formed.
May violently come into contact with each other, which may cause fluff on the strands 1 and may cause deterioration in the quality of the obtained prepreg precursor 1 ′. When the gap w is larger than 150 times the diameter of the single yarn of the strand 1, the film pressure generated in the molten resin flowing together with the strand 1 becomes small, so that the widening of the strand 1 does not proceed sufficiently. There is.

Although FIG. 3 shows a mode in which the bar members 15 and 15 are arranged at right angles to the running direction of the strand 1, the strand widening portion A in the present invention is not limited to this mode. Alternatively, each bar member may be arranged at a desired angle with respect to the traveling direction of the strand in a plane defined by each bar member and the traveling direction of the strand. In this case, the inclination angle is preferably set in the range of -45 ° to + 45 ° with respect to the traveling direction of the strand.

Nozzle structure 1 passing through passage 14a of jig 14
The strand 1 introduced into the die from 4b passes through the molten resin filling section B, and together with the molten resin passes through the gap w in the strand widening section A. And this gap w
The strand 1 is widened in a direction intersecting with the running direction of the strand as shown by an arrow in FIG. Then, at this time, the molten resin that is present is impregnated between the single yarns, so that the strand that has passed through the gap w becomes a tape-shaped prepreg precursor 1 ′ that is composited with the molten resin in a widened state.

This prepreg precursor 1 ′ is
3 is led out from the lead-out port 13a. The cross-sectional shape of the outlet 13a may be a slit shape or a circular shape. When the outlet 13a has a slit shape, a tape-shaped prepreg having a certain width can be formed as it is.
Has a circular shape, the tape-shaped prepreg precursor formed at the strand widening portion A is supplied to the outlet 1
At 3a, the bundles are converged again and continuously formed into a gut.

By changing the cross-sectional area of the outlet 13a, the volume content of fibers in the prepreg to be produced can be adjusted to an appropriate value. When the outlet 13a has a circular shape, the obtained gut may be continuously shaped into a tape shape by a heating roll or the like, or may be continuously cut to a fixed length, and the cut piece may be cut. It may be used as a pellet for injection molding.

FIG. 5 is a longitudinal sectional view showing a die according to another embodiment. In the case of this die, the cavity 12 of the die body 12
In b, the strand widening portion is arranged in two stages in the running direction of the strand 1. This strand widening portion is shown in FIG.
As shown in the figure, the bar member 15 whose surface located on the opposite side to the convex curved surface portion 15a is a slightly cut surface 15e except for the both end portions 15d, 15d is replaced with the convex curved surface portion 1
5a are arranged to face each other.

Therefore, in this strand widening portion,
As shown in FIG. 5, a space 12d is formed between the inner wall of the cavity 12b of the die body and the cutting surface 15e of the bar member 15. In the case of this die, the molten resin extruded into the cavity 11b of the head block is
Meets a strand inlet 12a of the die body 12, the cavity portion 12c of the first stage upstream of the strand widened portion A _1,
Furthermore, in the operation process of the die, through the space 12d of the strand widened portion A ₁ meet there flows into the next cavity portion 12e, Furthermore, the space 12 of the strand widening section A ₂
d to fill the remaining cavity 12f,
The entire cavity in the die becomes the molten resin filling portion B.

Accordingly, the first-stage strand widening portion A
_The strand passing through the gap ₁ is subjected to the initial widening and resin impregnation, and then travels while maintaining the state in the molten resin filling the cavity 12e, and then the second-stage strand widening section After passing through the gap A ₂ , where the widening and resin impregnation further proceed or the widening state in the first-stage strand widening portion A ₁ is maintained, the next cavity portion 1
It travels through the molten resin filling 2f and is led out from the outlet 13a.

As described above, when this die is used, the contact time between each single yarn of the strand and the molten resin is prolonged, and the wet state of each single yarn with the molten resin is improved. Improves. Note that these widened strand portions are not limited to the two-stage arrangement as described above, but may be arranged in two or more even-number stages.

In such a case, the widened portions of the strands may be continuously arranged orthogonally to the running method of the strand 1.
Further, as shown in FIG. 7, with respect to the running direction of the strand 1, the first strand widened portion A ₁ and arranged to be inclined at an angle of theta, the angle of inclination of the said next strand widening section A ₂ theta
May be repeated in such a manner as to be inclined in the opposite direction so as to cancel out.

In each of the above embodiments, the die 6
Is shown horizontally, but if the molten resin filling portion B is filled with the molten resin, the die 6 may be arranged so as to face the vertical direction.

[0036]

【Example】

Example 1 A tape-shaped prepreg was produced using the strand widening die shown in FIG. 2 using the apparatus shown in FIG. The thickness of single yarn is 1
A glass fiber non-twisted strand 1 having 7 μm and 2,000 single yarns is prepared, and ten of the strands are aligned in a sheet shape and sent out in a tension state in which a tension of about 40 g is applied per strand. It was sent from the machine 2 to the guide 3 and introduced into the die 6.

The molten nylon 6 (“Amilan” CM1006 manufactured by Toray Industries, Inc.) is placed in the molten resin filling portion of the die 6.
Is filled from the barrel portion 5 and the strand is run there. Further, the strand whose convex curved surface portion is a curved surface having a curve represented by y = 0.4 × ² and whose gap is adjusted to 0.4 mm It passed through the gap of the widened portion. At this time, the viscosity of the molten nylon 6 was adjusted to 300 poise, and the running speed of the strand was adjusted to 10 m / min.

The prepreg precursor led out from the outlet of the die is cooled in a cooling bath and dried by a dryer, and then wound by a winder 10 to have a width of 105 mm.
A tape-shaped prepreg having an average thickness of 0.09 mm was continuously produced. The volume content of the glass fiber in this prepreg was about 48%, and rough skin and fluff of a single yarn were hardly observed, and the resin was uniformly impregnated between the single yarns.

Example 2 A tape-shaped prepreg was manufactured using the die shown in FIG. 5 in which the strand widening portions were arranged in two stages using the apparatus shown in FIG. The thickness of single yarn is 7 μm and the number of single yarn is 120
An untwisted strand of 00 carbon fibers was prepared.

The gaps between the widened strand portions arranged in two stages were all adjusted to 0.3 mm. The resin used was the same nylon 6 as in Example 1, and the viscosity was adjusted to 250 poise. One of the strands was applied with a tension of about 30 g and continuously run in the apparatus. The running speed was adjusted to 6 m / min.

A tape-shaped prepreg having a width of 25 mm and an average thickness of 0.05 mm could be produced continuously. The volume content of carbon fibers in this prepreg was about 37%, and rough skin and fluff of single yarn were hardly observed, and resin was uniformly impregnated between single yarns.

[0042]

According to the present invention, the strands passing through the strand widening portion of the strand widening die are widened by the squeezing film action of the molten resin supplied together with the strands, and at the same time, melted between the single yarns. The resin is smoothly impregnated. Since the strand does not come into intense contact with the bar member of the strand widening portion, fluffing due to friction or the like is also prevented, the resulting prepreg is less likely to be roughened, and the composite state of fiber and resin is also improved. .

The size of the gap between the convex curved surface portions of the bar member,
Since the strands can be run at high speed by changing the viscosity of the molten resin so that the squeezing film action is properly generated, the prepreg can be manufactured with high productivity.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an arrangement of an entire apparatus when a method of the present invention is performed.

FIG. 2 is a longitudinal sectional view showing one example of a strand widening die of the present invention.

FIG. 3 is a perspective view showing one example of a strand widening portion.

FIG. 4 is a perspective view showing another example of the strand widening portion.

FIG. 5 is a longitudinal sectional view showing another example of the strand widening die.

FIG. 6 is a perspective view showing an example of a strand widening portion arranged on the die of FIG. 5;

FIG. 7 is a schematic view showing an example in which two strand widening portions are arranged.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Strand 1 'Prepreg precursor 2 Strand sending-out machine 3 Guide 4 Hopper 5 Barrel part 6 Strand widening die 7 Extruder main body 8 Cooling bath 9 Dryer 10 Winding machine 11 Head block 11a Strand inlet 11b Head block 11 12 Die body 12a Strand introduction port of die body 12 12b Cavity part 12c, 12e, 12f of die body 12d Space 13 Nozzle part 13a Outlet for prepreg precursor 14 For preventing backflow of molten resin Jig 14a Strand passageway of jig 14 14b Nozzle structure of jig 14 15 Bar member 15a Convex curved surface portion of bar member 15 15b Other surface of bar member 15 15c Plane 15d Side end of bar member 15e Cutting surface A, A ₁ , A ₂ Strand widening part B Melted resin filling part w Convex curved surface Gap between parts

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-132036 (JP, A) JP-A-5-50432 (JP, A) JP-A-62-184172 (JP, A) JP-A-2- 264026 (JP, A) JP-A-59-230723 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29B 15/14 B29B 11/16 B29C 70/06

Claims (5)

(57) [Claims] 1. A inlet of the strand at one end, outlet of the prepreg precursor is formed on the other end, inside a die is empty barrel strands running in the cavity portion An upper bar member having a convex curved surface portion extending in a direction intersecting the traveling direction of the strand and bulging downward.
And a lower bar member having a convex curved surface portion bulging upward.
Another said upper and lower convex curved surface portion with a pair of bar member made
So as to face disposed with strands widened portion obtained by forming a desired gap between the convex surface portion, of the strands widened portion, and the molten resin filling portion arranged into a strand inlet side provided in the strands The molten resin flowing with
When passing through the gap, the gap causes the molten resin to flow
To generate a film pressure of the molten resin in a direction orthogonal to the
Widen the strand in the direction crossing the running direction by pressure
Strand widening die, characterized in that cause. 2. A size of a gap between the convex curved surface portions is 3 to 15 of a diameter of a single yarn constituting a strand to be introduced.
2. The strand widening die of claim 1, wherein said die is zero-fold. 3. The strand widening die according to claim 1, wherein the strand widening section is provided in a plurality of stages in a running direction of the strand. 4. The strand widening portion is arranged to be inclined with respect to the running direction of the strand in a plane formed by a running direction of the strand and a direction in which the convex curved surface portion extends. 3. Strand widening die. 5. A strand is introduced in a tensioned state from the strand introduction port of the widening die according to claim 1 into the die, travels through the molten resin filling portion, and passes through the gap of the strand widening portion to form a tape. Wherein the prepreg precursor is formed through a die outlet.