JP4477925B2 - Manufacturing method of long fiber reinforced resin molding material and impregnation die for molding - Google Patents

Description

  The present invention relates to a pellet-like long fiber reinforced resin molding material and a method for producing the same, and particularly to a pellet-like long fiber reinforced resin molding material with less fuzz.

  Conventionally, a long-fiber resin molding material is known in which a continuous reinforcing fiber is impregnated with a thermoplastic resin as a matrix resin and pelletized. As a manufacturing method of the long fiber reinforced resin molding material, the matrix resin raw material is plasticized and melted by an extruder, the molten resin is filled in the impregnation die, and the reinforcing fiber drawn from the wound body is used in the impregnation die. By passing the resin into a strand, which is an aggregate of reinforcing fibers, that is, filaments, a linear long fiber reinforced resin in which the reinforcing fibers impregnated with the resin are shaped by an impregnation die outlet hole such as a nozzle is formed. It is known to obtain by cutting.

  As a long fiber reinforced resin molding material (pellet), Patent Document 1 discloses a reinforcing length in which a polyolefin resin having a melt flow rate of 30 g / 10 min or more and a fiber length of 5 mm or more and substantially parallel to each other. It is contained in a unit circle having an area of π · (5d) 2 (d: average fiber diameter of reinforcing long fibers) in the pellet cross section perpendicular to the direction of the reinforcing long fibers, and containing 20 wt% or more of fibers. It is disclosed that the number n of reinforcing fibers satisfies n ≦ −1.8X + 28√X−58 (X: content (wt%) of reinforcing long fibers). By dispersing the reinforcing long fibers in this way, the fiber opening property during molding becomes good, the fibers are uniformly dispersed in the molded product, and there is little bending, and mechanical strength such as tensile strength is obtained. In addition, it is described that it is possible to obtain a molded product having excellent strength and rigidity, and excellent impact strength such as Izod impact strength and drop weight impact strength, and having almost no strength anisotropy and warping deformation.

Further, in Patent Document 2, as a fiber reinforced resin molding material, a fiber bundle having a weight per 1000 m of 50 to 4400 g (50 to 4400 TEX) is increased in width / thickness by opening means in order to increase the impregnation efficiency of the molten resin. The fiber is spread so as to have a ratio of 35 to 750 and impregnated with a molten resin to obtain a long fiber reinforced thermoplastic resin structure. This structure is substantially parallel to the longitudinal direction and substantially the same as the structure. 10 to 80% by weight of reinforcing fibers arranged in the same length, and the length of the structure is 3 to 100 mm, and the container containing the structure is filled 60 times at a rate of 10% by volume. It is described that the fiber dissociated from the structure is 1000 ppm or less in a shaking test in which the rotation is alternately performed 180 ° at a speed of 500 minutes per minute.
JP-A-5-17631 JP 7-314444 A

  However, in order to obtain a long fiber reinforced polyolefin molding material described in Patent Document 1, that is, a long fiber reinforced pellet in which fibers are uniformly dispersed, it is necessary to eliminate the twist of the fiber drawn from the wound body, It becomes complicated both in terms of equipment and work. Further, in the long fiber reinforced pellet described in Patent Document 1, the glass fiber 5 (white portion) is uniformly dispersed in the pellet as shown in the pellet cross-sectional photograph of FIG. The long fiber reinforced pellets in which the fibers are uniformly dispersed to the surface layer of the pellets in this way cause the fibers to easily fall off from the pellets, deteriorate the workability in the subsequent molding, and have a lot of fibers on the pellet surface. The coefficient has increased, and a hopper for charging raw materials such as an injection molding machine has a problem that bridging is likely to occur when pellets are charged.

  On the other hand, in the long fiber reinforced pellets described in Patent Document 2, the fiber is set to 50 to 4000 TEX, and the spread width of the fiber bundle is specified for the purpose of obtaining a pellet with a small amount of fibers dropped by shaking the pellet. Is described. However, the production method disclosed in Patent Document 2 mainly aims to increase the efficiency of thermoplastic resin impregnation by highly opening the fiber bundle, so that the amount of fibers dropped from the pellet is sufficiently small. It was difficult to do.

  The present invention has been made to solve such a problem, and the object of the present invention is to have a good impregnation property of a thermoplastic resin into fibers in a pellet-like long fiber reinforced resin molding material, and to obtain a machine for a molded product to be obtained. It is to provide a long-fiber reinforced resin molding material having a high mechanical strength and extremely low fiber dropout from the pellets, and excellent in handleability during molding of molded products and in productivity of molded products, and a method for producing the same. .

  As a result of diligent study to achieve the above object, the present inventor has found that the reinforcing long fibers are concentrated and dispersed from the surface layer portion in the core portion of the pellet-like long fiber reinforced resin molding material, thereby reducing the fluffing and the pellets. The present invention has been completed by finding that a molded product with high mechanical strength and small variation in quality can be obtained by improving the impregnation of thermoplastic resin into reinforcing long fibers. did.

That is, this invention provides the manufacturing method of the following long fiber reinforced resin shaping material, and the shaping | molding impregnation die.
( 1 ) The reinforcing long fiber bundle drawn from the wound body is continuously passed through an impregnation die filled with a molten thermoplastic resin, and opened by a fiber opening tool provided in the impregnation die. In the method of manufacturing a pellet-like long fiber reinforced resin molding material by impregnating the reinforcing long fiber with a thermoplastic resin and then drawing it out from the die nozzle of the impregnation die to a predetermined wire diameter, the reinforcing long fiber bundle passes last. A method for producing a long fiber reinforced resin molding material, characterized in that the distance from the opening tool to the tip of the die nozzle is a distance L obtained by the following equation.
L = D × X (where X = 0.6 to 1.6, D is the inner diameter of the wound body (mm))
( 2 ) The method for producing a long fiber reinforced resin molding material as described in 1 above, wherein the inner diameter D of the wound body is 160 to 400 mm.
( 3 ) The manufacturing method of the long fiber reinforced resin molding material of said 1 or 2 whose said distance L is 210-360 mm.
( 4 ) A space that has an inlet hole through which a continuous reinforcing long fiber bundle passes and a die nozzle, and is filled with a molten thermoplastic resin in a region through which the reinforcing long fiber bundle passes between the inlet hole and the die nozzle. A spreader for opening the reinforcing long fiber bundle is installed in the space, and the distance from the opening device through which the reinforcing long fiber bundle passes last to the tip of the die nozzle A long fiber reinforced resin, wherein L is L = D × X (where X = 0.6 to 1.6), where D is the inner diameter of the wound body of the reinforcing long fiber bundle Impregnation die for molding molding materials.

L = D × X (where X = 0.6 to 1.6, D is the inner diameter of the wound body (mm))
(4) The method for producing a long fiber reinforced resin molding material according to (3), wherein the inner diameter D of the wound body is 160 to 400 mm.
(5) The method for producing a long fiber reinforced resin molding material according to (3) or (4), wherein the distance L is 210 to 360 mm.
(6) A space having an inlet hole and a die nozzle through which a continuous reinforcing long fiber bundle passes, and a region in which the reinforcing long fiber bundle between the inlet hole and the die nozzle passes is filled with a molten thermoplastic resin. A spreader for opening the reinforcing long fiber bundle is installed in the space, and the distance from the opening device through which the reinforcing long fiber bundle passes last to the tip of the die nozzle A long fiber reinforced resin, wherein L is L = D × X (where X = 0.6 to 1.6), where D is the inner diameter of the wound body of the reinforcing long fiber bundle Impregnation die for molding molding materials.

  In the present invention, the reinforcing long fibers can be dispersed as much as possible in the core portion of the pellet-shaped long fiber reinforced resin molding material, and the amount of reinforcing long fibers in the surface layer portion of the pellet is reduced, so that the reinforcing long fibers can be as much as possible. Since it does not appear on the surface of the pellet, there is little fuzzing and fibers can be prevented from falling off the pellet.

  Furthermore, since the reinforcing filaments are not substantially present on the pellet surface, a pellet having high surface smoothness and low friction can be obtained, and thereby, workability when producing a molded product using the pellet is improved. Productivity can be increased. Moreover, since the impregnation efficiency of the thermoplastic resin into the reinforcing long fibers is high, a molded product having high mechanical strength and small quality variation can be obtained.

Hereinafter, the present invention will be described in more detail with reference to preferred specific examples.
The thermoplastic resin used for the pellet-like long fiber reinforced resin molding material of the present invention (hereinafter sometimes simply referred to as pellets) is not particularly limited. For example, polyethylene, polypropylene, polyamide, polyethylene terephthalate, polybutylene terephthalate, Examples include polystyrene, AS (acrylonitrile styrene) resin, ABS (acrylonitrile butadiene styrene) resin, PPS (polyphenylene sulfide), PEI (polyetherimide), PEEK (polyether ether ketone), and the like. As is apparent from these examples, a widely used thermoplastic resin can be used, and usually polypropylene, polyamide and the like are often used. This thermoplastic resin can appropriately contain colorants, modifiers, fillers other than reinforcing fibers, known additives, etc., depending on applications and molding conditions, and these are kneaded and used in accordance with conventional methods. The

  In the present invention, as reinforcing reinforcing fibers, inorganic fibers such as glass fibers and carbon fibers, synthetic fibers, and the like can be used depending on the type of thermoplastic resin and the use of pellets. Glass fibers and carbon fibers are often used for general-purpose pellets, and among them, glass fibers are often used preferably. These reinforcing long fibers are dispersed in the thermoplastic resin as an aggregate of a large number of monofilaments to form pellets. The basic structure of such a pellet is substantially the same as that of the pellet of the present invention, and a plurality of reinforcing filaments (monofilaments) are aligned along the longitudinal direction (pulling direction) of the pellet. The thermoplastic resin is impregnated in the gaps between the individual monofilaments of the reinforcing filaments. In this case, the reinforcing long fibers dispersed in the thermoplastic resin are continuous in the longitudinal direction of the pellet and are arranged in a state of being substantially parallel to each other. That is, the reinforcing long fibers only need to be arranged substantially in parallel, and a small amount of reinforcing long fibers may be curved or entangled in the longitudinal direction.

  In the present invention, the number of reinforcing long fibers contained in the pellet is preferably about 3400 to 5200, more preferably 4000 to 5200. When the number of reinforcing long fibers is within this range, a desired reinforcing effect can be obtained, and most of the reinforcing fibers can be dispersed in the thermoplastic resin while avoiding contact between the fibers in the core portion of the pellet described later.

  When the reinforcing long fibers are glass fibers, for example, a glass fiber bundle (hereinafter referred to as glass fiber strands or strands) formed by bundling a plurality of monofilaments having a diameter of 6 to 25 μm is used. The glass fiber strand is wound up by a winding device, and if necessary, can be drawn out from a wound body obtained by natural drying or heat drying. If the monofilament diameter is less than 6 μm, the glass fiber productivity is low and the cost is high, which is not practical. If the monofilament diameter exceeds 25 μm, the rigidity of the monofilament increases and becomes brittle. Therefore, the monofilament is cut by friction between the die and the glass fiber when passing through the impregnation die of the pellet manufacturing apparatus or between the glass fibers. There is a risk that the quality of pellets may be deteriorated, and the fluff generated in the production apparatus may deteriorate the productivity.

  Typical examples of the wound body include a cylindrical direct wind roving 2 shown in FIG. 1 (a) and a drum-like cake 1 shown in FIG. 1 (b). These direct wind roving 2 and cake 1 can be obtained by traversing the winding of the wound body with a guide member and a spiral wire that reciprocate, respectively, but this method is generally used in glass fiber production. It is the same as the conventional one. At that time, by using a winder having a winding diameter D, a wound body having an inner diameter D can be obtained.

  The inner diameter D of this wound body is preferably in the range of 160 to 400 mm, more preferably in the range of 200 to 400 mm. When the inner diameter D is less than 160 mm, the strands are wound with a small diameter, so that the number of twists per unit length increases, and the strands drawn out become stronger, so the impregnation property of the thermoplastic resin is poor. Further, in order to minimize the number of job changes such as thread joining, the wound body preferably has as much winding amount as possible. However, when the inner diameter is less than 160 mm and this winding amount is increased, the thickness of the wound body is reduced. Since it becomes thick, the drying efficiency of the sizing agent is inferior, which is not preferable. If the inner diameter exceeds 400 mm, the wound body becomes bulky and difficult to transport and requires a wide place. When the winding amount of the strands is made the same and the inner diameter is increased beyond 400 mm, the thickness of the obtained winding body becomes thin, so that the shape of the winding body becomes difficult to maintain, and the winding amount increases when the winding amount is increased. Since the wound body is bulky and heavy, there arises a problem that workability at the time of handling or conveyance is inferior.

  Furthermore, when the reinforcing long fibers are glass fibers, the wound body is preferably a cake rather than direct wind roving. Direct wind drawing has a stable cylindrical shape, so it is excellent in terms of easy handling in stacking and transporting. In the natural drying or heat drying process after removal, a phenomenon in which the sizing agent accumulates on the surface of the wound body as the moisture moves) occurs on the outer peripheral surface and both end surfaces of the cylinder. Even if the strands on the outer peripheral surface where migration has occurred can be discarded without being used, the strands on both end surfaces must be used.Therefore, if the strands are pulled out from direct wind roving and used, the sizing agent increases due to migration. The part accumulated in the concentration appears in some places. In addition, direct wind roving generally tends to increase the number of monofilaments, so even if the fiber is opened with a spreader, the thermoplastic resin does not easily penetrate into the strand, and the mechanical properties of the molded product (FRTP) There is a risk of lowering.

  On the other hand, as shown in FIG. 2, the cake draws a large number of monofilaments 5 from the bushing 4, and after applying a sizing agent to the monofilament 5 by an applicator 6, the sizing is carried out by a sizing member 7 and a glass fiber strand. The drum-like cake 2 can be produced by winding the glass fiber strand 3 while traversing the glass fiber strand 3 with the spiral wire 8.

  The cake 2 obtained in this way has a strand spread flatly on the spiral wire and is wound in a state where the filaments are arranged almost in parallel, so that it is easy to open when impregnating the resin and has excellent impregnation properties. . Further, as shown in FIG. 1 (b), the strand 3 is wound in a drum shape, that is, the center portion swells and the both end surfaces are narrowed. Migration in the heating and drying process is less likely to occur than in the direct wind drawing described above, and even if it occurs, it is the winding start part on the innermost side of the cake and the winding end part on the outermost side of the cake. Good.

  The number of monofilaments bundled per glass fiber strand is preferably 1200 or less. When the number of bundles exceeds 1200, it becomes difficult for the resin to be impregnated into the glass fiber strand, and the impregnation property of the thermoplastic resin is deteriorated particularly in a portion where the twist is applied. The number of monofilaments bundled per glass fiber strand is more preferably 100 to 1000, and most preferably 200 to 800.

  Further, the count (TEX) per one glass fiber strand is preferably in the range of 150 to 500, more preferably in the range of 200 to 350. If the count is less than 150, it is necessary to reduce the number of monofilaments or to reduce the diameter of the monofilament, so that the productivity of the glass fiber is lowered and the cost is increased. If the count exceeds 500, the number of filaments generally increases, making it difficult for the resin to impregnate, and the strands become thicker, thereby increasing the influence of twisting.

  When the reinforcing long fibers are glass fibers, the number of the glass fiber strands to be contained in the pellet-shaped long fiber reinforced resin molding material is appropriately determined in accordance with the number of monofilament bundles of the strands, the pellet diameter (die nozzle diameter), and the like. . Accordingly, the number of strands is not specified, but usually about 3 to 35 strands are preferable, and 5 to 15 strands are more preferable. If the number of strands is less than 3, the pellets have a small diameter due to the blending ratio with the resin, so that the production efficiency is lowered, and the number of monofilaments concentrated per strand is inevitably increased. As a result, nozzle clogging of the impregnation die tends to occur. On the other hand, when the number of strands exceeds 35, it becomes difficult for the resin to be impregnated into the glass fiber strand, and pellet cracking tends to occur when pelletized. Furthermore, the increase in the number of strands increases the time required for setting during production and increases the yarn splicing.

  In the present invention, the content of the reinforcing long fibers in the long fiber reinforced resin molding material is 20 to 60% by mass, and more preferably 40 to 60% by mass. If the content of reinforcing long fibers is less than 20% by mass, reinforcing fibers are insufficient as master pellets, and a desired strength may not be obtained in a molded product. The content of reinforcing long fibers can be up to about 80% by mass in a normal long fiber reinforced resin molding material. In the present invention, however, the reinforcing long fibers are focused on the core portion of the long fiber reinforced resin molding material. Because it is dispersed, it is suppressed to a few. When the reinforcing long fibers are concentrated and contained in the core portion in this way, if the reinforcing fiber content exceeds 60% by mass, the amount of resin in the core portion is relatively insufficient and the fibers gather together. However, the dispersibility of the fibers may deteriorate.

  In the present invention, the length of the long fiber reinforced resin molding material is 3 to 50 mm, more preferably 8 to 12 mm. The length of the long fiber reinforced resin molding material can be appropriately determined within this range depending on the shape and type of the molded product. If the length is less than 3 mm, the reinforcing effect by the fibers cannot be sufficiently obtained, and if it exceeds 50 mm, inconvenience occurs in the molding process of the molded product, or classification is caused by the difference in particle size when blended with other pellets or the like. Problems such as being difficult to mix can occur. The cross-sectional shape of the long fiber reinforced resin molding material is preferably a circle or a shape close to a circle. However, it is not limited to this, and it may be a shape such as an elliptical shape or a polygonal shape, for which the outer peripheral average circular diameter can be obtained. Furthermore, the cross-sectional shape does not necessarily have to be the same shape in the entire longitudinal direction of the long fiber reinforced resin molding material. In these cross-sectional shapes, the maximum diameter is usually about 2 to 4 mm.

  The present invention is characterized in that the core portion of such a long fiber reinforced resin molding material (hereinafter sometimes referred to as a pellet) contains more reinforcing long fibers than the surface layer portion. Next, this will be specifically described with reference to the drawings. FIG. 3 is a photograph of a cross section in a direction orthogonal to the longitudinal direction (hereinafter referred to as a pellet cross section) of a pellet formed by using glass fiber as a reinforcing long fiber and combining the glass fiber and a thermoplastic resin. This is just an example. As shown in FIG. 3, the glass fibers 5 (white portion) are densely dispersed in the core portion of the pellet, and the amount of glass fiber dispersed in the surface layer portion of the pellet is smaller than that of the core portion. That is, the pellet cross section is divided into two by a concentric circle 10 having a diameter of 70.7% of the outer peripheral average circular diameter 9 of the cross section, and the number of fibers contained in the inner circle 11 of the divided cross section is A, the inner When the number of fibers contained in the outer annular portion 12 of the circle 11 is B, A / B is 1.5 or more. Here, the outer peripheral average circular diameter of the pellet cross section can be obtained as an average value of the maximum outer diameter and the minimum outer diameter of the outer shape (contour) of the pellet cross section. The inner circle 11 is obtained by drawing a perfect circle having the center of the maximum outer diameter as the center point of the pellet cross section and having a diameter of 70.7% of the outer peripheral average circle diameter around the center point. Since the inner circle 11 and the annular portion 12 in the pellet cross section roughly correspond to the core portion and the surface layer portion of the pellet, respectively, the ratio of the number of fibers dispersed in the core portion and the number of fibers dispersed in the surface layer portion is represented by A / B.

  In this case, even if A / B is not 1.5 or more in all pellet cross sections of the pellet, the object of the present invention can be achieved as long as this requirement is satisfied in almost all pellet cross sections. For example, if this requirement is satisfied in 90% or more, more preferably 95% or more of the pellet cross section arbitrarily selected from the pellets, fluffing of the pellets can be substantially prevented. Incidentally, in the conventional pellet, the fibers are substantially uniformly distributed in the inner circle 11 and the annular portion 12 or rather more dispersed in the annular portion 12 than in the inner circle 11, and therefore A / B is almost equal to the pellet cross section. About 1 or less.

  Moreover, even if the glass fiber 5 is slightly deviated with respect to the center of the pellet as shown in FIG. 3, it is sufficient that A / B is 1.5 or more as a whole of the pellet cross section. By setting A / B to 1.5 or more, most of the glass fibers 5 can be secured to the thermoplastic resin in the core portion, so that the glass fibers can be prevented from appearing on the pellet surface. Even if some of the glass fibers appear on the pellet surface, the amount can be reduced to such an extent that fuzzing does not substantially occur. On the other hand, if A / B is less than 1.5, the amount of glass fiber dispersed in the surface layer of the pellet increases, so the amount of glass fiber that appears on the surface of the pellet also increases, and the pellet is handled. A lot of fluff occurs. In the present invention, preferred A / B is 1.8 or more.

  Next, the manufacturing method of the pellet which concerns on this invention is demonstrated based on FIG. FIG. 4 illustrates one of the methods in the case of producing the pellets of the present invention using glass fibers, but the present invention is not limited to this. The same members as those described above will be described with the same reference numerals for easy understanding. As shown in FIG. 4, a plurality of glass fiber rolls, for example, strands 3 drawn out from the cake 1 are drawn together and supplied to the preheating furnace 14, preheated in the preheating furnace, and then introduced into the impregnation die 16. The impregnation die 16 is provided with an inlet hole 24 and an outlet hole (die nozzle) 25 through which the strand 3 passes as shown in an enlarged sectional view in FIG. 5, and the strand passes between the inlet hole 24 and the die nozzle 25. The area 27 to be filled has a space portion 27 filled with a molten thermoplastic resin. In this space portion 27, a spreader 22 for opening the strand 3 is installed, and a thermoplastic resin 26 that is heated and kneaded and melted from the extruder 15 is supplied. The plurality of strands 3 introduced into the impregnation die 16 are opened by bringing them into contact with the opening tool 22 installed in the space 27 of the impregnation die 16, and between the opened fibers (monofilaments). Impregnated with thermoplastic resin. Next, the strand 3 impregnated with the thermoplastic resin is passed through the die nozzle 25 of the shaping die 23 to be shaped into a linear shaped product 19 having a substantially circular cross section. During this time, the linear molded product 19 is continuously drawn out by the take-up machine 18, cooled and solidified while passing through the cooling tank 17, and then sent to the pelletizer 20, where it is cut into pellets 21 of a predetermined length. Is done.

  As the opening tool 22, those known so far as opening means can be used, and typical examples thereof include a opening bar or a opening roller. In this example, five spread bars are installed in the space 27 of the impregnation die 16 so as to be orthogonal to the traveling direction of the strand 3. In this case, it is preferable that these opening bars are arranged with a difference in height so that they can function as tension bars, and the strands 3 are alternately brought into contact with these opening bars (see FIG. 5). . Since the strand 3 is opened in the molten thermoplastic resin in the space 27, the thermoplastic resin can be impregnated between the fibers at the same time as the opening or while opening. Although not shown, a curved convex portion is provided at a position where the strand 3 of the opening bar contacts (see Patent Document 2), and the strand 3 is pressed against the curved convex portion using tension, thereby opening the strand 3. Can be performed efficiently and reliably.

  The strand 3 impregnated with the thermoplastic resin in the space portion 27 has a linear shape having a substantially circular cross section when excess resin is removed when passing through the die nozzle 25 of the shaping die 23 and passing through the tip of the die nozzle. It is shaped into a molded product. The length and diameter of the die nozzle 25 can be appropriately determined according to the pellet to be molded and are not specified, but the length of the die nozzle 25 is usually about 10 to 40 mm and the diameter is about 2 to 4 mm.

  In the production of the above pellets, in order to reduce the fluff of the pellets by setting A / B to 1.5 or more and to suppress the twisting effect of the strands 3 in the impregnation die 16, the strands 3 It is essential that the distance L from the last opening device 22 that passes through the tip of the die nozzle 25 satisfies the following equation when the inner diameter of the wound body is D.

L = D × X (where X is 0.6 to 1.6)
In FIG. 5, the distance from the last opening bar 22 ′ to the tip of the die nozzle 25 is L, and this L is set to the inner diameter D of the wound body to be used in consideration of the resin impregnation property and the prevention of fluff generation. On the other hand, X is selected and determined within the range of 0.6 to 1.6. When X is less than 0.6, the length of L is shortened, and passes through the die nozzle 25 in a state in which the glass fiber finally opened and impregnated with the resin spreads in the opening bar 22 ′ that passes through the end. Therefore, the glass fibers are easily dispersed uniformly throughout the pellets, and as a result, the glass fibers appear on the pellet surface and a pellet with a lot of fluff is obtained. When X exceeds 1.6 and L becomes long, the glass fiber that has been opened and impregnated with resin in the opening bar 22 ′ that passes through the end is twisted again from the state in which it spreads while passing through L. It becomes a state. As a result, when passing through the die nozzle 25, a lot of fibers are densely packed in the pellet. However, since the dispersibility of the glass fiber is inferior due to the twist, the mechanical strength and surface sufficient for a molded product obtained from the pellet are obtained. Appearance may not be obtained.

  In the production of the above pellets, the strand 3 drawn out from the cake 1 has a tension generated by the drawing and a slight twist. In the present invention, since the inner diameter of the cake 1 is 20 cm or more, FIG. As shown in FIG. 4, the number of twists per unit length can be extremely reduced to, for example, 1 or less per 1 m, so that the resin impregnation is excellent. On the other hand, the strand drawn from the wound body having a small inner diameter has about twice as many twists as illustrated in FIG. 6B. Since the strand 3 in this example has a small number of twists and is easy to open, the resin is sufficiently impregnated between one monofilament when the impregnation die 16 is impregnated with the thermoplastic resin.

  According to the present invention, as described above, while facilitating the opening of the reinforcing fiber bundle and improving the impregnation of the resin into the fiber bundle, by specifying the distance L between the opening tool and the tip of the die nozzle, A pellet having a core portion with dense fibers and a surface layer portion with dense resin in the pellet cross section can be obtained. Such pellets can be used alone or in combination with a thermoplastic resin-free pellet containing no reinforcing material and put into an injection molding machine or the like to obtain a molded product having high mechanical strength and small variation in strength.

Example 1
As a reinforcing material, 600 monofilaments having a diameter of 16 μm (330 TEX) are converged, and nine glass fiber strands drawn from a cake having an inner diameter D286 mm, which is wound in a drum shape using a spiral wire, are aligned, Each was passed through the die nozzles of 10 impregnation dies, and a thermoplastic resin with 10% acid-modified polypropylene added to polypropylene was used. The distance L between the final opening bar and the tip of the die nozzle was 340 mm (L / D = 1. 19) Using the impregnation die as shown in FIG. 4, the glass fiber content is 60% by mass, with a resin temperature of 260 ° C., drawn from a 10-dia nozzle of φ2.2 mm at a speed of 20 m / min. 12 mm polypropylene / glass fiber L-FTP pellets were produced.

  Furthermore, using this L-FTP pellet as a master pellet, a predetermined amount of polypropylene was added, and a strength test piece compliant with ASTM having a glass fiber content of 30% by mass was produced by an injection molding machine.

Example 2
As a reinforcing material, 600 monofilaments having a diameter of 16 μm (330 TEX) are bundled and nine glass fiber strands drawn from a cake having an inner diameter of 286 mm, which is wound in a drum shape using a spiral wire, are used, and a distance L is 220 mm ( L / FTP pellets of polypropylene / glass fiber having a glass fiber content of 60% by mass and a length of 12 mm were produced in the same manner as in Example 1 except that an impregnation die having L / D = 0.77) was used.

  Furthermore, the strength test piece based on ASTM with a glass fiber content of 30% by mass was produced in the same manner as in Example 1.

Comparative Example 1
As a reinforcing material, 600 monofilaments having a diameter of 16 μm (330 TEX) are bundled and nine glass fiber strands drawn from a cake having an inner diameter of 286 mm, which is wound in a drum shape using a spiral wire, are used, and a distance L is 120 mm ( A polypropylene / glass fiber L-FTP pellet having a glass fiber content of 60% by mass and a length of 12 mm was produced in the same manner as in Example 1 except that an impregnation die having L / D = 0.41) was used.

  Furthermore, the strength test piece based on ASTM with a glass fiber content of 30% by mass was produced in the same manner as in Example 1.

  About the said Example 1, Example 2, and the comparative example 1, the impregnation state of the thermoplastic resin in each L-FTP pellet was measured by the red marker test (ink test). In this measurement, the pellet was soaked in ink, and the one colored in the longitudinal direction from the end of the pellet was visually evaluated, and the evaluation was performed in a five-step evaluation of 1 (good) to 5 (bad). As for the fluff of the pellet, 10 g of the pellet was collected, and x which was confirmed to be fluffed by visual observation was evaluated as x and those which could not be confirmed were marked as ◯.

  Further, the average circumference diameter of the pellet cross-section at the middle point in the longitudinal direction of each pellet was calculated, and each pellet cross-section was divided into two by a concentric circle having a diameter of 70.7% of the respective circumference average circle diameter. The number of fibers contained in the circle (A) and the number of fibers contained in the outer annular frame of the inner circle (B) were counted, and A / B was calculated for each pellet cross section.

  Moreover, bending strength and impact strength with Izod V were measured for each strength test piece. In addition, “dispersion (appearance)” of glass fiber means that a flat plate having a thickness of 2 to 3 mm is formed from pellets by an injection molding machine, and that the undispersed glass fiber can be confirmed by visually observing the flat plate cannot be confirmed. Was marked ◯. These results are shown together in Table 1 together with the above-mentioned implementation conditions.

表１から明らかのように、実施例１および２のペレットは、図３に例示したペレット断面のようにガラス繊維がコア部分に密集した状態のペレットであり、いずれもペレットの毛羽が少ないものであった。これに対し、比較例１のペレットはガラス繊維の分散性が良好であり機械的強度に優れるものの、図７のようにペレット表面にガラス繊維が集まりペレットの毛羽が多いものであった。なお、実施例１、２のペレットを使用した成形品の機械的強度は、ガラス繊維がコア部分に集中して分散しているペレットにも拘わらず、比較例１のペレットを使用した成形品の機械的強度とほぼ同等であった。

As is apparent from Table 1, the pellets of Examples 1 and 2 are pellets in which glass fibers are densely packed in the core portion as in the pellet cross section illustrated in FIG. there were. In contrast, the pellet of Comparative Example 1 had good dispersibility of glass fibers and excellent mechanical strength, but glass fibers gathered on the pellet surface as shown in FIG. The mechanical strength of the molded product using the pellets of Examples 1 and 2 is that of the molded product using the pellets of Comparative Example 1 regardless of the pellets in which the glass fibers are concentrated and dispersed in the core portion. It was almost equal to the mechanical strength.

  The long fiber reinforced resin molding material of the present invention is widely applicable to various long fiber reinforced resin molded articles as master pellets with less generation of fuzz and excellent resin impregnation.

FIG. 1A is a perspective view of a winding body according to the present invention, FIG. 1A is a perspective view of a direct wind roving, and FIG. 1B is a perspective view of a cake. The front view of the glass fiber manufacturing apparatus for cakes. The pellet cross-section photograph of the long fiber reinforced resin molding material which concerns on preferable embodiment of this invention. The schematic diagram which shows an example of the manufacturing apparatus of the long fiber reinforced resin molding material which concerns on this invention. FIG. 5 is an enlarged cross-sectional explanatory view of the impregnation die of FIG. 4. Explanatory drawing which shows the state of twist of a glass fiber bundle. A cross-sectional photograph of a pellet of a conventional long fiber reinforced resin molding material.

Explanation of symbols

1: Cake 2: Direct winding roving 3: Glass fiber bundle 4: Bushing 5: Monofilament (glass fiber) 6: Monofilament 9: Peripheral average circle 10: Concentric circle 11: Inner circle 12: Annular frame 14: Preheating furnace 15: Extruder 16: Impregnation die 17: Cooling tank 18: Take-up machine 19: Molded product 20: Pelletizer 21: Pellet 22: Opening tool 23: Shaping die 24: Entrance hole 25: Die nozzle 26: Thermoplastic resin 27: Space

Claims (5)

The reinforcing long fiber bundle drawn from the wound body is continuously passed through an impregnation die filled with a molten thermoplastic resin, and opened by a spreader provided in the impregnation die, and the reinforcing long fiber bundle is opened. In a method of manufacturing a pellet-shaped long fiber reinforced resin molding material by impregnating a fiber with a thermoplastic resin and then drawing it out from a die nozzle of an impregnation die to a predetermined wire diameter, the opening of which the reinforcing long fiber bundle passes last A method for producing a long fiber reinforced resin molding material, characterized in that the distance from the tool to the tip of the die nozzle is a distance L obtained by the following equation.
L = D × X (where X = 0.6 to 1.6, D is the inner diameter of the wound body (mm)) The reinforcing long fiber bundle drawn from the wound body is continuously passed through an impregnation die filled with a molten thermoplastic resin, and opened by a spreader provided in the impregnation die, and the reinforcing long fiber bundle is opened. In a method of manufacturing a pellet-shaped long fiber reinforced resin molding material by impregnating a fiber with a thermoplastic resin and then drawing it out from a die nozzle of an impregnation die to a predetermined wire diameter, the opening of which the reinforcing long fiber bundle passes last By making the distance from the tool to the tip of the die nozzle a distance L obtained by the following formula, the pellet cross section perpendicular to the direction of the reinforcing long fiber of the long fiber reinforced resin molding material is the average circumference diameter of the pellet cross section When the number of fibers contained in the inner circle of the divided cross section is A, and the number of fibers contained in the annular portion outside the inner circle is B, Almost all pellets Method for producing a long fiber-reinforced resin molding material according to claim 1, characterized in that A / B is set to be 1.5 or more in the surface.
  L = D × X (where X = 0.6 to 1.6, D is the inner diameter of the wound body (mm)) The method for producing a long fiber reinforced resin molding material according to claim 1 or 2 , wherein an inner diameter D of the wound body is 160 to 400 mm. The said distance L is 210-360 mm, The manufacturing method of the long fiber reinforced resin molding material of Claim 1, 2, or 3 .   It has an inlet hole through which a continuous reinforcing long fiber bundle passes and a die nozzle, and has a space for filling molten thermoplastic resin in a region through which the reinforcing long fiber bundle passes between the inlet hole and the die nozzle. In addition, a spreader for opening the reinforcing long fiber bundle is installed in the space, and the distance L from the opening tool through which the reinforcing long fiber bundle passes last to the tip of the die nozzle is, A long fiber reinforced resin molding material characterized in that L = D × X (where X = 0.6 to 1.6), where D is the inner diameter of the winding body of the reinforcing long fiber bundle Impregnation die for molding.

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