JP2019157072A - Fiber reinforced resin composite sheet - Google Patents

Abstract

To provide a fiber reinforced resin composite sheet excellent in three-dimensional moldability and good in liquid shield property, and a manufacturing method therefor.SOLUTION: The above described problem can be solved by a fiber reinforced resin composite sheet in which a thermoplastic resin part is molten and impregnated around an all aromatic polyamide resin part by heating and molding a knitted structure formed by a thermoplastic resin and an all aromatic polyamide resin, and a structure having one directionality by the all aromatic polyamide part is fixed by cold solidification of the thermoplastic resin part, and a manufacturing method therefor.SELECTED DRAWING: None

Description

  The present invention relates to a fiber reinforced resin composite sheet and a method for producing the same, and more particularly to a fiber reinforced resin composite sheet having excellent three-dimensional formability and good liquid shielding properties and a production method suitable for producing such a fiber reinforced resin composite sheet.

  It is possible to obtain a fiber reinforced resin composite having light weight and high mechanical properties by combining a functional fiber having characteristics such as high strength, high elastic modulus, and high heat resistance typified by wholly aromatic polyamide fiber with a resin. Is possible. In particular, by selecting a thermoplastic resin as the object to be reinforced, various molded products can be produced by a simple and short molding process such as hot press molding, and thus has attracted attention in recent years.

  As an important item for the fiber reinforced resin composite to be industrially significant, “three-dimensional moldability” can be mentioned. In order for fiber reinforced resin composites to be used in various applications, it is necessary to have a molding technology that can provide not only two-dimensional shapes such as flat plates, but also three-dimensional shapes with depth and depth. It is. However, functional fibers such as wholly aromatic polyamide fibers usually have low elongation, and fiber structures (uniaxially oriented base materials, woven base materials, etc.) that are linearly positioned / configured with such fibers are solid molded metal It is difficult to follow the shape of the mold.

  As a means for solving this problem, a method using a non-woven fabric base material of wholly aromatic polyamide fibers and thermoplastic resin fibers which have been shortened has been proposed. The three-dimensional formability is cleared by using reinforcing fibers cut into short fibers, and a fiber-reinforced resin composite is obtained by heating, melting, and cooling solidification of the thermoplastic resin portion contained in the base material ( For example, see Patent Document 1.)

  However, in this method, since the reinforcing fibers are cut into short fibers, the reinforcing effect obtained is lower than that when used as long fibers. Furthermore, since the molding substrate is a non-woven fabric, voids are likely to occur in the molded body, and the mechanical properties deteriorate due to the voids. In addition, the voids affect not only the mechanical properties of the molded body but also the liquid shielding properties of the molded body. When considering applying the fiber reinforced resin composite to an application that is directly exposed to an external environment such as rainwater, the nonwoven fabric base material has a liquid infiltrated into the molded body due to voids in the base material. Harmful to you and the surrounding environment.

JP 2017-108246 A

  The present invention has been made against the background of the above prior art, and an object thereof is to provide a fiber-reinforced resin composite sheet having excellent three-dimensional formability and excellent liquid shielding properties.

  The present inventor has intensively studied to solve the above problems. As a result, a fiber reinforcement comprising a knitted structure formed of wholly aromatic polyamide fiber and a thermoplastic resin, wherein the thermoplastic resin is impregnated around at least part of the wholly aromatic polyamide fiber The present inventors have found that the above problems can be solved by the resin composite sheet, and have completed the present invention. As another invention of the present invention, the entire aromatic polyamide fiber bundle is checked with a short fiber between a pair of rollers having different speeds, and the checked short fiber is sucked with a nozzle disposed under the roller. Forming a knitted structure with heterogeneous fiber composite yarn obtained by conjugating and mixing while simultaneously adding a thermoplastic resin fiber bundle to the nozzle, and heat-molding the formed knitted structure It is the manufacturing method of the fiber reinforced resin composite sheet characterized. According to these inventions, it is possible to provide a fiber-reinforced resin composite sheet having excellent three-dimensional formability and good liquid shielding properties and a method for producing the same.

  The fiber reinforced resin composite sheet of the present invention exhibits good three-dimensional formability while forming a high resin reinforcing effect of reinforcing fibers by forming a knitted structure with a thermoplastic resin and a wholly aromatic polyamide resin. That is, since the base material has elasticity due to the knitting structure, the base material can follow the shape of the molding die during press molding. Further, by cooling in this pressed state, the thermoplastic resin portion is solidified, and a fiber-reinforced resin composite sheet in which the three-dimensional shape imparted by the mold is fixed is obtained.

  In addition, by using a composite yarn in which a thermoplastic resin and a wholly aromatic polyamide resin are pre-combined in a certain ratio as fibers forming the knitted structure, the thermoplastic resin portion becomes wholly aromatic. A state in which the polyamide resin is densely and uniformly impregnated more than airtight and liquid-tight around the periphery of the polyamide resin is created. As a result, a fiber-reinforced composite sheet with few voids and high liquid shielding properties can be obtained.

FIG. 1 is a view showing an apparatus preferably used for producing a heterogeneous fiber composite yarn comprising a wholly aromatic polyamide fiber and a thermoplastic resin fiber, which is used in the production of the fiber-reinforced resin composite sheet of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail.

<Fiber reinforced resin composite sheet>
[Construction]
The fiber reinforced resin composite sheet in the present invention includes a thermoplastic resin and a knitted structure formed of wholly aromatic polyamide fibers. The knitting structure formed of wholly aromatic polyamide fibers is not particularly limited, and a known knitting structure can be adopted. Specifically, there are a structure composed of a flat knitting structure and a structure composed of a warp knitting structure. Weft knitting (weft knitting) organization includes round knitting, flat knitting (tengu knitting), rib knitting (milling, rubber knitting), double knitting (interlock, smooth, double rib), pearl knitting (links knitting, garter knitting) As variations of these knitting methods, tack knitting, welt knitting, lace stitch (lace knitting), eyelet knitting, splicing knitting, pile knitting, inlay knitting, jacquard knitting, and floating knitting good. The warp knitting (warp knitting) organization includes Denby (single denby), tricot, atlas, banded, single cord, plain cord, Berlin, double stitch, double denby, and satin. Can be mentioned. Among these knitted structures, flat knitting is possible because a melted thermoplastic resin is arranged around the wholly aromatic polyamide fibers constituting these knitted structures, so that a structure that maintains airtightness and liquid tightness can be created relatively easily. (Tengu edition) is preferable. The knitting density (number of loops per unit length) of the knitted structure is preferably in the range of 35 to 55 pieces / inch, and more preferably in the range of 40 to 50 pieces / inch. If the mesh has a density lower than this range, since the density of the knitted structure is low, the thermoplastic resin does not reach the entire knitted structure, which leads to defects such as perforations in the molded body obtained from the composite sheet. On the other hand, in a mesh having a density higher than this range, since the base material is not stretchable at the time of pressing when manufacturing a composite sheet, it is difficult to follow the shape of a mold having a three-dimensional solid shape, and the three-dimensional formability is impaired. Not desirable.

  On the other hand, when a woven structure is used instead of the knitted structure, the mechanical properties of the knitted structure are improved, but the structure of the fiber itself has low extensibility, so it is difficult to follow the shape of the three-dimensional mold during pressing. This is not desirable because moldability is impaired and it becomes difficult to produce a molded article having a complicated three-dimensional structure. When a nonwoven fabric structure is employed instead of the knitted structure, the entangled portion between the fibers has a degree of freedom in displacement, and there is no problem with the three-dimensional formability. Further, by controlling the entanglement density, a molded body having excellent mechanical properties can be obtained even for a structure made of short fibers. However, the structure is formed by the entanglement of short fibers, and there are many voids in the molded body. This void is not desirable because the liquid shield performance is reduced.

  The weight ratio of the wholly aromatic polyamide fiber constituting the fiber-reinforced resin composite sheet and the thermoplastic resin (weight of the wholly aromatic polyamide fiber / weight of the thermoplastic resin) is preferably 10/90 to 90/10, / 88-50 / 50 is more preferred, 15 / 85-40 / 60 is even more preferred, and 18 / 82-35 / 65 is most preferred.

  Furthermore, the fiber reinforced composite sheet of the present invention is characterized in that a thermoplastic resin is impregnated and disposed in at least a part of the periphery of the wholly aromatic polyamide fiber. The wholly aromatic polyamide fiber may be a long fiber having a length of more than 2.5 m or a short fiber having a length of less than 2.5 m. There may be. Moreover, in this invention, the thermoplastic resin is arrange | positioned in at least one part of the circumference | surroundings of a wholly aromatic polyamide fiber. As a specific form, even if the thermoplastic resin is arranged so as to wrap the wholly aromatic polyamide fiber along the fiber axis direction, a part of the cross-sectional shape perpendicular to the fiber axis of the wholly aromatic polyamide fiber is used. You may arrange | position along a fiber axis direction. In these forms, the thermoplastic resin disposed around the wholly aromatic polyamide fiber may be disposed in a form in which at least a part thereof is in contact with the wholly aromatic polyamide fiber. When the fully aromatic polyamide fiber is a long filament multifilament or a short fiber, it is impregnated with a thermoplastic resin so as to fill the space existing between the two or more fully aromatic polyamide fibers. And constitutes an arranged form. Preferably, a knitted structure formed of wholly aromatic polyamide fibers is fixed with a thermoplastic resin.

  As a more preferable arrangement, a knitted structure formed of wholly aromatic polyamide fibers is fixed with a thermoplastic resin. Here, the term “fixed” means that the knitted structure formed from wholly aromatic polyamide fiber in which no thermoplastic resin is present has a larger load when being deformed by tension or bending. This does not mean that the knitted structure does not deform at all even when a remarkably large tensile load or bending load is applied. More preferably, the thermoplastic resin fills the space between the wholly aromatic polyamide fibers so that airtightness or liquid-tightness from the front surface to the back surface or from the back surface to the surface of the knitted structure is maintained. It is the state arrange | positioned with various forms. By being in such a state, it can be a fiber-reinforced resin composite sheet having good liquid formability while having good three-dimensional formability.

<Physical properties of fiber reinforced resin composite sheet>
The physical properties of the fiber reinforced resin composite sheet vary depending on the intended use. Below, the form of each item in the case of considering the utilization as a vibrating body is described.

Preferably the basis weight of the fiber-reinforced resin composite sheet of the present invention is 100 to 500 g / ^{m 2,} more preferably from 150 to 300 g / ^{m 2,} and further preferably from a 160~200g / ^{m 2.} When the basis weight of the fiber reinforced resin composite sheet is larger than the range of 100 to 500 g / m ² , vibration characteristics as a vibrating body are hardly expressed. On the other hand, when the basis weight is smaller than the above range, it is not preferable because it leads to breakage during press molding and liquid shield performance lowering described later.

  The elongation at break in the fiber-reinforced resin composite sheet of the present invention is preferably 5.0 to 20.0%, more preferably 8.0 to 18.0%, and 10.0 to 15.0%. Even more preferably. When the value of the elongation at break is in the range of 5.0 to 20.0%, when used as a speaker cone material, it may inhibit the vibration of sound required as a vibration plate of the speaker cone. Less preferred.

The fiber reinforced resin composite sheet of the present invention preferably has a holding time of 2.5 hours or longer when the following liquid shielding evaluation is performed. The holding time is more preferably 3 hours or more, still more preferably 5 hours or more, and most preferably 8 hours or more.
○ Liquid shield evaluation method: Press-molded body formed into a truncated cone-shaped bowl using a fiber reinforced resin composite sheet (upper surface diameter inside the molded body (large): 150 mm, lower surface diameter inside the molded body (small): 25 mm, depth: 50 mm, thickness: 0.5 mm) is sandwiched and fixed by a pair of hollow cylindrical metal fittings, and 10 wt% of linear alkylbenzene sodium sulfonate is placed on the press-molded body so that the water surface depth is 50 mm. The containing dispersion liquid was placed and allowed to stand, and the time during which the water surface depth was maintained at 40 mm or more was measured, and the length of this time was set as the holding time.

<Totally aromatic polyamide fiber>
The wholly aromatic polyamide fiber in the present invention is preferably a meta-type wholly aromatic polyamide fiber or para-type wholly aromatic polyamide fiber, more preferably para-type wholly aromatic polyamide fiber. A meta-type wholly aromatic polyamide is a polymer in which one or more divalent aromatic groups are directly linked by an amide bond at the meta position. Mention may be made of metaphenylene isophthalamide fibers (fiber bundles). On the other hand, para-type wholly aromatic polyamide is a polymer in which one or more divalent aromatic groups are directly linked by an amide bond at the para position. Preferred examples of the aromatic group include a group in which one or more phenylene rings or naphthalene rings are linked, and the two aromatic rings are bonded via an oxygen, sulfur, or alkylene group. Or an aromatic group in which two or more aromatic rings are directly bonded. Furthermore, these divalent aromatic groups include 1 to 4 carbon atoms such as a lower alkyl group having 1 to 4 carbon atoms such as a methyl group and an ethyl group, a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. An aromatic group in which a halogen group such as an alkoxy group, a fluoro group, a chloro group, or a bromo group is substituted for a hydrogen atom may be included.

  Examples of such para-type wholly aromatic polyamides include polyparaphenylene terephthalamide, terephthalic acid component, and copolyparaphenylene 3,4 obtained by copolymerization of a 3,4′-diaminodiphenyl ether component and a paraphenylenediamine component. List of '-oxydiphenylene terephthalamide, or copolyparaphenylene, phenylbenzimidazole, terephthalamide, etc., in which a terephthalic acid component, an aromatic diamine component having a phenylbenzimidazole skeleton, and a paraphenidylenediamine component are copolymerized Can do.

  Moreover, as a para type wholly aromatic polyamide fiber used for this invention, it may be used individually by 1 type, or may use 2 or more types together.

  In the present invention, since the molded body reinforcement efficiency at normal temperature and heat resistance, that is, mechanical strength retention during thermoforming and mechanical strength are particularly excellent, polyparaphenylene terephthalamide fiber or copolyparaphenylene 3,4 ′ -Oxydiphenylene terephthalamide fibers are preferably used. Since polyparaphenylene terephthalamide is insoluble in common organic solvents, it is necessary to create a dope having optical anisotropy using a strong acid such as sulfuric acid. large. On the other hand, since copolyparaphenylene 3,4'-oxydiphenylene terephthalamide is soluble in amide solvents, the load for obtaining a spinning solution (dope) for obtaining fibers is small. Moreover, it is excellent in moldability. For this reason, in the present invention, it is most preferable to use copolyparaphenylene 3,4'-oxydiphenylene terephthalamide.

  In the present invention, as long as the para type wholly aromatic polyamide fiber is the main component, other than that, polyparaphenylene benzoxazole fiber, high strength polyethylene fiber, high strength polyvinyl alcohol fiber, wholly aromatic polyester fiber The mixed fiber in which etc. were mixed may be sufficient. Here, the “main component” means that the para-type wholly aromatic polyamide is in the range of more than 50% by mass to 100% by mass with respect to the entire fibers constituting the check-processed yarn. In the present invention, the para-type wholly aromatic polyamide is particularly preferably 100% by mass.

  The wholly aromatic polyamide fiber constituting the fiber-reinforced resin composite sheet of the present invention is preferably a wholly aromatic polyamide fiber having a fiber length of 20 cm or more. The fiber length is more preferably 1.0 to 2.5 m, and still more preferably 1.2 to 2.0 m. When the total aromatic polyamide fiber has a fiber length of 20 cm or longer, a sheet-like product having sufficient tensile strength and tensile elastic modulus can be obtained after being formed into a fiber-reinforced resin composite sheet. On the other hand, if the fiber length is less than 20 cm, it is not preferable because the tensile strength and tensile elastic modulus necessary for a specific application as described later cannot be ensured.

[Physical properties and production method of wholly aromatic polyamide fiber]
The single yarn fineness of the wholly aromatic polyamide fiber used for the check-off process is preferably 2.2 dtex or less. More preferably, it is 0.1-1.8 dtex, More preferably, it is 0.2-1.7 dtex. When the single yarn fineness is larger than 2.2 dtex, the number of constituent single yarns of the check-off processed yarn is reduced, and the entanglement between the single yarns is reduced, which may cause a problem that the strength of the yarn is lowered. is there.

  The tensile strength of the wholly aromatic polyamide fiber used for the check-off process is preferably 18 cN / dtex or more. More preferably, it is 20 cN / dtex or more. When it is less than 18 cN / dtex, the strength after the check processing is low, and the check processing yarn of the present invention cannot be obtained. Moreover, the strength after the check-out process is low, and an effect as a rubber reinforcing material cannot be expected.

  About the manufacturing method of para type | mold wholly aromatic polyamide, by the manufacturing method as described in Unexamined-Japanese-Patent No. 2011-251261, the polymerization process of para type | mold total aromatic polyamide, the adjustment process of the solution for spinning, spinning and coagulation | solidification It can manufacture by passing through a process and an extending process.

<Thermoplastic resin>
Examples of the thermoplastic resin in the present invention include polyolefin resin, polyester resin, polyamide resin, polycarbonate resin, polyoxymethylene resin (polyacetal resin), polyphenylene sulfide resin, ABS resin (acrylonitrile / butadiene / styrene resin), Preferably, at least one thermoplastic resin selected from polyolefin resins, polyester resins, polyamide resins, polycarbonate resins, and ABS resins is used. Among these thermoplastic resins, examples of polyolefin resins include polyethylene resins, polypropylene resins, polystyrene resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyvinyl acetate resins, and polymethylpentene resins. May include nylon 6 resin, nylon 46 resin, nylon 66 resin, and nylon 610 resin. Polyester resins include polyethylene terephthalate resin, polytrimethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, polytrimethylene naphthalate. Mention may be made of phthalate resins and polybutylene naphthalate resins. Among these, polyolefin resin and polyester resin are preferably used, and polyethylene resin, polypropylene resin, polystyrene resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyethylene terephthalate resin, polybutylene terephthalate resin, or polyethylene naphthalate resin are used. It is more preferable. Among these resins, it is preferable to use at least one selected from polypropylene resin, polyethylene terephthalate resin, polyamide resin, polycarbonate resin, and ABS resin. Furthermore, for press molding under low temperature conditions, it is desirable to select a polyethylene resin or a polypropylene resin having a relatively low softening point. In addition, when emphasizing the dyeability of the molded product, it is desirable to select a polyester resin that can be easily dyed.

<Production method and molding conditions of fiber reinforced resin composite sheet>
As an example of the method for producing the fiber-reinforced resin composite sheet of the present invention, the fully aromatic polyamide fiber bundle is checked into short fibers between a pair of rollers having different speeds, and the checked short fibers are arranged under the rollers. The knitted structure is formed by forming a knitted structure with different fiber composite yarns obtained by kneading while sucking with a nozzle and mixing the fibers while simultaneously feeding a thermoplastic resin fiber bundle to the nozzle. The manufacturing method which heat-molds can be mentioned.

[Method for producing heterogeneous fiber composite yarn]
The heterogeneous fiber composite yarn used in the method for producing a fiber-reinforced resin composite sheet of the present invention is preferably a heterogeneous fiber composite yarn composed of a wholly aromatic polyamide fiber and a thermoplastic resin fiber bundle. It is preferable to manufacture by the method shown in FIG. As an example of a method for obtaining a fiber made of wholly aromatic polyamide resin (totally aromatic polyamide fiber) in a heterogeneous fiber composite yarn, a checkering treatment for obtaining a checkered yarn can be mentioned. The checking method for obtaining such checking thread is not particularly limited, and a known method can be adopted. For example, the methods described in JP-A-58-081637 and International Publication No. 2005/103353 pamphlet may be employed.

  Furthermore, in the production method of the present invention, it is preferable to use a heterogeneous fiber composite yarn in which such a check-processed yarn is arranged around and a thermoplastic resin fiber is arranged in the center. As an example of a method for producing such a heterogeneous fiber composite yarn, a fiber bundle made of wholly aromatic polyamide resin is checked into short fibers between a pair of rollers having different speeds, and the checked short fibers are placed under the rollers. And a method for producing a heterogeneous fiber composite yarn characterized in that the fibers are conjugated while being sucked by a nozzle disposed in the nozzle and further mixed while simultaneously feeding a thermoplastic resin fiber bundle into the nozzle.

  The checkout method for obtaining the composite yarn of the present invention is not particularly limited, and a known method can be adopted. For example, a method in which a fiber made of a wholly aromatic polyamide resin and a fiber made of a thermoplastic resin are twisted can be employed. However, the composite yarn used in the present invention may be a composite yarn obtained by swirling and entwining a wholly aromatic polyamide fiber bundle centered on a thermoplastic resin fiber bundle and checked. desirable. With the yarn combined by the method, the thermoplastic resin melted at the time of thermoforming reaches the details, and a fiber-reinforced resin composite having high mechanical properties can be obtained because there are few defects.

  Hereinafter, the manufacturing method of the different fiber composite yarn used for manufacture of the fiber reinforced resin composite sheet of this invention is demonstrated, using drawing. FIG. 1 is an example of a preferred apparatus diagram for producing the heterogeneous fiber composite yarn. 1 is a supply nip roller, 2 is a shooter, 3 is a check-out nip roller, 4 is a suction air nozzle, 5 is a swivel conjugated nozzle, 6 is a delivery roller, 7 is a wound heterogeneous fiber composite yarn, 8 is Totally aromatic polyamide fiber, 9 represents a thermoplastic resin fiber. This will be described in more detail by dividing it into a check process, a conjugation process, and a winding process.

[Check-out process]
In the check-out process, the wholly aromatic polyamide long fiber bundle 8 (see symbol 8 in FIG. 1, the same applies hereinafter) is arranged in a desired number in front of the supply nip roller 1 and overlapped with the supply nip roller 1 while being overlapped. After passing, it is checked out (drawn and shredded) in the shooter 2. This check process is performed on the speed difference between the supply nip roller 1 and the check nip roller 3 to create a short fiber bundle. At this time, it is preferable that a wet fluid having a humidity of 80% or more, for example, wet air, is supplied into the shooter 2 and applied to the para-type wholly aromatic polyamide fiber. Next, it is pulled out from the check-off nip roller 3 by the suction air nozzle 4, and is then pulled out by the delivery roller 6 after being entangled or conjugated by fluffing by the swivel conjugating nozzle 5.

  A short fiber bundle is produced by carrying out an operation of pulling off the long fiber bundle according to a speed difference between the nipped feed roller (supply nip roller 1) and the nipped take-off roller (checking nip roller 3). . The speed difference between the two types of nip rollers can be appropriately selected from a range of 2.0 to 20.0 times. Furthermore, in the above-described method for producing a different fiber composite yarn, the thermoplastic resin fiber 9 is directly supplied into the shooter 2 without going through the supply nip roller 1, and the suction air nozzle 4 is connected with the check nip roller 3. Supply to the conjugating swivel nozzle 5.

(Checking length)
The check length in the check process is preferably in the range of 1.2 to 2.0 m. If the check length is less than 1.2 m, entanglement between single yarns in the conjugation step is reduced, and a highly aromatic polyamide check yarn with high strength cannot be obtained. Further, when the length exceeds 2.0 m, the single yarns are entangled with each other, and an aggregate of yarn entanglements is generated in the swivel-bonding nozzle 5 in the conjugation process, and the yarn cannot pass through the nozzles.

(Checkout magnification)
The check magnification in the check process is preferably in the range of 8.0 to 18.0 times. If it is this range, the length of the single yarn to be cut becomes uniform, the strength variation of the finally obtained all aromatic polyamide check yarn can be reduced, and a high strength check yarn can be obtained. .

(Checkout speed)
The checking speed in the checking process is not particularly limited, but is preferably 200 to 500 m / min. When the check speed is less than 200 m / min, unevenness occurs in the entanglement between the single yarns, increasing the strength variation, and as a result, the strength of the obtained check processed yarn is lowered. In addition, when the check speed exceeds 500 m / min, the amount of single yarn entanglement at the conjugating nozzle in the conjugating step decreases, the adhesiveness with the resin decreases, and the strength of the obtained check processing thread decreases. To do.

[Conjugation process]
In the conjugation step, the short fiber bundle and the thermoplastic resin fiber 9 produced in the check-out step are subjected to a conjugation process by passing through a conjugation nozzle 5 that generates a swirl flow. In this conjugation processing step, the thermoplastic resin fiber, which is a feature of the heterogeneous fiber composite yarn, is arranged at the center, and the peripheries of a fully aromatic polyamide fiber bundle that has been subjected to a check processing is arranged around it. Can be achieved.

(Conjugation pressure)
The conjugation pressure added in the conjugation step is preferably in the range of 0.2 to 0.5 MPa. Within this range, it is possible to obtain a check-processed yarn with an increased amount of single yarn entanglement, and to obtain a fully aromatic polyamide check-processed yarn having excellent adhesion to a matrix such as rubber and having high strength. Can do.

[Winding process]
By the above operation, a heterogeneous fiber composite yarn in which a thermoplastic resin fiber bundle is arranged at the center and a check-processed yarn of wholly aromatic polyamide fiber is arranged around the center is manufactured, and is wound up by the delivery roller 6. The winding roll of the different fiber composite yarn 7 can be obtained.

[Manufacture of knitted structure]
As a method for producing the knitted structure constituting the fiber-reinforced resin composite sheet of the present invention, it can be produced using a known method and apparatus for producing the warp knitting or weft knitting structure described above. As the yarn, the above-mentioned different fiber composite yarn is preferably used.

[Method for producing fiber-reinforced resin composite sheet]
In order to produce the fiber reinforced resin composite sheet of the present invention from the obtained knitted structure of different fiber composite yarns, it is preferable to perform a press molding step. In press molding of the knitted structure, the molding temperature is desirably in the range of 180 to 250 ° C. If the area is lower than the above range, the melt viscosity of the thermoplastic resin is high, making it difficult for the resin to reach around the wholly aromatic polyamide fiber, which is a reinforcing fiber, and fully impregnating the thermoplastic resin around the wholly aromatic polyamide fiber. It may be difficult to place. As a result, the thermoplastic resin impregnation property is lowered, and the mechanical properties of the sheet-like molded product are lowered. In the case of a region higher than the above range, resin deterioration such as decomposition of the thermoplastic resin component tends to occur, which is not desirable. In addition, as a method of defining the molding temperature, there is a method of setting based on the melting point of the thermoplastic resin constituting the fiber reinforced resin composite sheet. Specifically, the melting point of the thermoplastic resin constituting the fiber-reinforced resin composite sheet + 10 ° C. to the melting point + 80 ° C. is preferable, and the melting point of the thermoplastic resin + 30 ° C. to the melting point + 70 ° C. is more preferable.

  About the pressure at the time of press molding, it is desirable to be in the range of 4.0 to 7.0 MPa. In the case of a region lower than the pressure range, the mold transfer capability of the molded body is impaired, and it becomes difficult to obtain a molded body having the shape and dimensions as designed. In the case of a region higher than the pressure range, the molten thermoplastic resin leaks out of the mold, and an insufficiently resin impregnated portion is formed in the molded body, resulting in a decrease in mechanical properties of the molded body. Preferably, press molding is performed within a range of 4.5 to 6.0 MPa.

  The molding time during press molding is desirably within a range of 5 to 10 minutes. In molding in a time shorter than the time range, the time required for the molten resin to reach every corner of the fiber structure is not secured, leading to a decrease in mechanical properties of the molded body. Further, molding in a longer time than the time range is not desirable from the viewpoint of resin deterioration and molding efficiency.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, unless this invention exceeds the summary, it is not limited to these at all.
<Measurement and evaluation method>
Each characteristic value in Examples and Comparative Examples was measured and evaluated by the following method.
(1) Fineness Measured according to JIS-L-1015 (Method B).
(2) Evaluation / observation of the configuration of the different fiber composite yarn, etc. and measurement of the fiber length The obtained different fiber composite yarn is cut to an appropriate length, sampled, and further cut perpendicularly to the fiber axis as necessary. After performing such processing, observation was performed from a plurality of angles with a 100 × optical microscope, and the configuration of the different fiber composite yarn was observed and evaluated. However, when sufficient observation could not be performed, observation was performed at 200 to 500 times magnification using a scanning electron microscope. In addition, for the fiber length of the fibers constituting the different fiber composite yarn, a single yarn was taken out by disassembling part or all of the sampled different fiber composite yarn with tweezers, and the fiber length was measured using a measure or the like. .
(3) Analysis of thermoplastic resin fiber About the kind (primary structure) of the thermoplastic resin fiber, ¹ H-NMR measurement (JEOL-600 type, manufactured by JEOL Ltd.) was performed on a sampled piece of the thermoplastic resin fiber. It was identified by analyzing the spectrum chart.
(4) Weight ratio of thermoplastic resin fiber bundle and wholly aromatic polyamide fiber The total weight of the sampled heterogeneous fiber composite yarn was measured, and an immersion treatment was performed in a solvent capable of dissolving the thermoplastic resin. Heat treatment was performed as necessary. For example, mineral oil, toluene and xylene are used for polyolefins such as polyethylene and polypropylene, and phenol, cresol and o-chlorophenol can be suitably used for polyesters such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate. By this operation, the thermoplastic resin fiber bundle was removed, and the weight of the remaining wholly aromatic polyamide fiber was measured to calculate the weight ratio of the wholly aromatic polyamide fiber.
(5) Fiber structure density When the fiber structure is a knitted structure, the number of knitting loops in one inch square was measured and used as the knitting density (pieces / inch).
When the fiber structure is a woven structure, the number of weft yarns (or warp yarns) in the width of 1 inch was measured and used as the woven density (lines / inch).
(6) Three-dimensional formability The base material to be press-molded (the state before melting the thermoplastic resin) was molded with an uneven mold, and the followability to the mold shape was confirmed by visual observation. A molded article that was not torn or wrinkled at the visual level and that had a dimensional difference of less than 5% from the mold was judged to have good three-dimensional moldability. On the other hand, those in which the molded body was torn or wrinkled at the visual level, or those having a dimensional difference of 5% or more from the mold were judged as three-dimensional moldability defects.
(7) Tensile properties (tensile strength, tensile modulus, elongation at break)
Using a constant stretch type tensile tester, a tensile force was applied in the fiber orientation direction by a method based on JIS C 2111, and the physical properties were measured.
(8) Weight per unit area / thickness The fiber reinforced resin composite sheet was cut out with a predetermined size (100 × 100 mm as an example), and the basis weight was calculated from the weight. The sheet thickness was measured at a total of five locations at the four corners and the center of the sheet with a micrometer, and the average value was calculated.
(9) Liquid shielding properties From the fiber reinforced resin composite sheet obtained in each of the examples and comparative examples, a truncated cone shaped press-molded body (upper surface diameter (large): 150 mm, lower surface diameter (small): 25 mm, depth (Size: 50 mm, thickness: 0.5 mm). The molded body was sandwiched and fixed between a pair of hollow cylindrical metal fittings, and a car shampoo solution (an aqueous solution containing 10 wt% linear alkylbenzene sulfonate aqueous solution [dispersion]) so that the water surface depth was 50 mm on the press molded body. ) And left to stand. The time during which the water surface depth was maintained at 40 mm or more was measured, and the quality of the liquid shielding property was judged based on the length of the holding time.

<Example 1>
Copoly core made of two polypropylene fiber bundles (fineness: 190 dtex, number of filaments: 20) as thermoplastic resin fibers, and around which are short fibers having a fiber length of 1.2 to 2.0 m as reinforcing fibers A knitted structure made of flat knitting was formed using dissimilar fiber composite yarn in which one paraphenylene · 3,4′-oxydiphenylene terephthalamide fiber bundle (fineness: 1670 dtex, number of filaments: 1000) was swirled. The weight ratio of reinforcing fiber: thermoplastic resin fiber in the heterogeneous fiber composite yarn was 20:80.

  This heterogeneous fiber composite yarn was produced by the following operation. Two long fiber bundles 8 of copolyparaphenylene and 3,4′-oxydiphenylene terephthalamide fiber (8 is shown in FIG. 1; the same applies hereinafter) are para-type wholly aromatic polyamide fibers. The number of rotations of the pair of supply nip roller 1 and shooter 2 and the check nip roller 3 is checked so that the check length is 150 cm and the speed is 300 m / min at a check magnification of about 18 times. Adjustment was performed so that the speed of the roller 3 was increased, and a check-off process was performed to simultaneously pull the fibers of the long fiber bundle into a thin short fiber bundle. The conjugation process is performed when passing the swirlable conjugating nozzle 5 disposed below the suction air nozzle while sucking the short-cut short fiber with the suction air nozzle 4 disposed below the supply nip roller. went. Furthermore, simultaneously with the suction / conjugation treatment, one of the polypropylene fiber bundles 9 was inserted into the suction air nozzle 4 and joined to the copolyparaphenylene • 3,4′-oxydiphenylene terephthalamide fiber bundle after the check-out process. Then, while sucking with the suction air nozzle 4 arranged at the lower part of the check nip roller 3, the suction air nozzle and the swirl conjugation nozzle 5 having swirl flow are used to check around the polypropylene fiber 9 as a central part. The cut para-type wholly aromatic polyamide short fiber bundle 8 was conjugated, entangled and composited, and wound with a delivery roller 6 to obtain a different fiber composite yarn 7.

  The obtained knitted structure is press-molded with a pair of concavo-convex molds (press temperature: 220 ° C., press pressure: 5 MPa, press time: 5 minutes), and the knitted structure composed of a wholly aromatic polyamide portion is cooled. A molded body of a fiber reinforced resin composite sheet fixed with a solidified thermoplastic resin was obtained.

  As a result of observing the molded product of the obtained fiber reinforced resin composite sheet with an optical microscope, it was confirmed that it had a knitted structure with wholly aromatic polyamide fibers, and was melted by heat and pressure applied by press molding. It was observed that the polypropylene was arranged so as to wrap around the wholly aromatic polyamide fiber along the fiber axis direction. Further observations indicate that the melted polypropylene resin is impregnated between the wholly aromatic polyamide fibers, and the knitted structure made of wholly aromatic polyamide fibers is fixed with polypropylene resin to the extent that the knitted structure itself seems to be liquid-tight. It was recognized that Table 1 shows the three-dimensional formability, tensile physical properties (strength, elastic modulus, elongation at break), basis weight, thickness, density, and liquid shielding properties of the obtained fiber-reinforced resin composite sheet.

<Example 2>
A molded body was obtained in the same manner as in Example 1 except that the weight ratio of reinforcing fiber (fully aromatic polyamide fiber): thermoplastic resin fiber in the heterogeneous fiber composite yarn constituting the knitted structure was 30:70. . As a result of observing with an optical microscope in the same manner as in Example 1, as with the fiber-reinforced resin composite sheet of Example 1, it was disposed so as to wrap around the wholly aromatic polyamide fiber along the fiber axis direction. Upon further observation, it was confirmed that polypropylene resin was impregnated between the wholly aromatic polyamide fibers, and the knitted structure was fixed to such an extent that the knitted structure itself seems to be liquid-tight. Table 1 shows the three-dimensional formability, tensile physical properties (strength, elastic modulus, elongation at break), basis weight, thickness, density, and liquid shielding properties of the obtained fiber-reinforced resin composite sheet.

<Comparative Example 1>
A molded body was obtained in the same manner as in Example 1, except that the structure formed of the different fiber composite yarn described in Example 1 was a plain woven structure.

<Comparative example 2>
Copolyparaphenylene, 3,4'-oxydiphenylene terephthalamide cotton and polypropylene cotton having a fiber length of 20 mm or less are blended (reinforced fiber (fully aromatic polyamide fiber): weight ratio of thermoplastic resin fiber is 20:80) Then, a dry nonwoven fabric was produced with a needle punch. The obtained dry nonwoven fabric was pressed (pressing temperature: 220 ° C., pressing pressure: 5 MPa, pressing time: 5 minutes) with a pair of concavo-convex molds to obtain a molded body.

  The fiber-reinforced resin composite sheet of the present invention has high mechanical properties, and also has good three-dimensional formability and liquid shielding properties. For this reason, it is expected to be used for various industrial material applications (structural materials, automotive parts, electrical materials, etc.) where the usage environment is severe and various shapes are required. In particular, in-vehicle speaker cone applications, there are demands for highly accurate shapes and dimensions in order to develop good vibration characteristics. In addition, since the application needs to prevent damage to the electrical system due to liquid permeation while avoiding vibration shielding by other materials, the speaker cone material itself is required to have high liquid shielding properties. In view of the above, the content of the present invention is considered to be effective in speaker cone applications.

1: Feeding nip roller 2: Shooter 3: Checking nip roller 4: Suction air nozzle 5: Swivel conjugation nozzle 6: Delivery roller 7: Wound dissimilar fiber composite yarn (center portion of thermoplastic resin fiber bundle The check thread is entangled and arranged around it)
8: Fully aromatic polyamide fiber (before checkout processing)
9: Thermoplastic resin fiber

Claims (9)

  A fiber-reinforced resin composite sheet comprising a knitted structure formed of wholly aromatic polyamide fiber and a thermoplastic resin, wherein the thermoplastic resin is impregnated around at least a part of the wholly aromatic polyamide fiber .   The fiber-reinforced resin composite sheet according to claim 1, wherein a knitted structure formed of wholly aromatic polyamide fibers is fixed with a thermoplastic resin.   The fiber-reinforced resin composite sheet according to claim 1 or 2, wherein the wholly aromatic polyamide fiber is a wholly aromatic polyamide fiber having a fiber length of 20 cm or more. Fiber-reinforced resin composite sheet according to claim 1, basis weight of the fiber-reinforced resin composite sheet is in the range of 100 to 500 g / ^{m 2.} The fiber-reinforced resin composite sheet according to any one of claims 1 to 4, wherein the retention time is 2.5 hours or more when the liquid shield property evaluation shown below is performed.
Liquid shielding property evaluation method: Press-molded body formed into a frustoconical bowl shape using a fiber reinforced resin composite sheet (upper surface diameter inside the molded body (large): 150 mm, lower surface diameter inside the molded body (small): 25 mm , Depth: 50 mm, thickness: 0.5 mm), and a dispersion containing 10 wt% of linear alkylbenzene sodium sulfonate is placed on the press-molded body so that the water surface depth is 50 mm. The time during which the length is maintained at 40 mm or more was measured, and the length of this time was set as the holding time.   The fiber reinforced resin composite sheet according to any one of claims 1 to 5, wherein the elongation at break is in the range of 5.0 to 20.0%.   The fiber-reinforced resin composite sheet according to any one of claims 1 to 6, wherein the wholly aromatic polyamide fiber is a copolyparaphenylene · 3,4'oxydiphenylene terephthalamide fiber or paraphenylene terephthalamide fiber.   The fiber reinforced resin according to any one of claims 1 to 7, wherein the thermoplastic resin is a thermoplastic resin comprising at least one selected from a polyolefin resin, a polyester resin, a polyamide resin, a polycarbonate resin, and an ABS resin. Composite sheet.   The entire aromatic polyamide fiber bundle is checked into short fibers between a pair of rollers with different speeds, and the checked short fibers are conjugated while being sucked with a nozzle disposed under the rollers, and further thermoplastic with respect to the nozzles. The knitted structure is formed of different fiber composite yarns obtained by mixing and mixing the resin fiber bundles at the same time, and the formed knitted structure is heat-molded. The manufacturing method of the fiber reinforced resin composite sheet of any one of Claims 1.

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