JP2012241183A - Fiber composite material and sandwich material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber composite material suitable for uses and members which require impact resistance.SOLUTION: There is provided a fiber composite material comprising a fiber A, a fiber B and a thermoplastic resin, wherein the fiber A is an organic fiber having a ≥200°C melting point and ≥5% tensile break strain, the fiber B has a 200°C×10 min dry heat shrinkage of ≤1%, the fiber B has 10-100 pts.vol. based on 100 pts.vol. of the fiber A, and the fiber composite material contains an entangled yarn of the fiber A and the fiber B.

Description

  The present invention relates to a fiber composite material containing organic fibers and a thermoplastic resin, and more particularly to a fiber composite material suitable for applications and members that require impact resistance, and a sandwich material using the fiber composite material as a core material.

  Plastics, especially thermoplastic resins, can be processed by various molding methods and are indispensable materials for our daily life. However, in some cases, the flexibility of thermoplastic resin leads to low strength and rigidity, and in applications that require high strength and high rigidity, reinforcement with short fibers of inorganic fibers such as glass fibers and carbon fibers is performed. I have been. However, composites of organic thermoplastic resins and inorganic glass fibers are difficult to recycle, and there is a problem of disposal. Moreover, since glass fiber was high specific gravity, there existed the subject that it was heavy and was not suitable for weight reduction. Furthermore, reinforcement with inorganic fibers is effective in improving the strength and rigidity of the composite material, but has not been very effective in performance such as impact resistance.

Then, examination of the composite_body | complex with a thermoplastic resin and organic fiber is performed. For example, Patent Document 1 discloses a technique in which a long fiber-like organic fiber aligned with a molten thermoplastic resin discharged from an extruder is combined with a roller while being pressed in order to improve strength. Patent Document 2 discloses a technique for improving the impact resistance of a resin composition by combining a thermoplastic elastomer having a tensile elastic modulus of less than 1 GPa and an elongation of 300% or more and a silk fiber fabric. .
On the other hand, rubber materials obtained by reinforcing rubber such as latex or thermoplastic elastomer such as EPDM (ethylene-propylene copolymer) with organic fibers are used for tires, hoses, belts and the like.

Further, as described in Patent Document 1, the strength of the composite material can be improved by the effect of organic fibers. One of the major characteristics of organic fibers is high impact absorption performance, but Patent Document 1 has not studied this point. In Patent Document 2, the impact resistance of a composite material is improved by using silk fibers. However, since silk fibers are natural fibers, there is a problem in productivity, and because they are expensive, economics such as costs. There was also a problem. Natural fibers such as silk fibers also have a problem that their strength is generally lower than that of synthetic fibers.
In addition, a composite material in which rubber or a thermoplastic elastomer is reinforced with organic fibers has a problem in that it has a low rigidity although there is no problem in impact resistance because the rubber or thermoplastic elastomer as a matrix is flexible.

Therefore, the present inventors mainly have a shock absorbing property of a composite material composed of a polyester fiber twisted cord or a woven or knitted fabric composed of twisted cords and a thermoplastic resin. It has been found that a sandwich material having a high rigidity material and a skin layer is a material having both impact resistance and high rigidity.
Polyester fiber is relatively inexpensive and has a high balance of strength and elongation, so it exhibits high impact absorption. However, when heated to form a composite with a thermoplastic resin, the fiber itself shrinks, resulting in dimensions at the time of molding. It was difficult to control. In particular, the sandwich material with the polyester fiber thermoplastic resin composite material as the core layer and the high rigidity material as the skin layer has a large shrinkage difference between the skin layer and the core layer, which may cause wrinkle marks on the molded product, There were problems such as unevenness in the plate thickness.

JP 2002-144395 A JP-T 2009-530469

  The present invention is an organic fiber composite made in view of the above problems and a sandwich structure using the same, and more specifically, a composite that has high energy absorption performance and high thermal dimensional stability, so that dimensional control during molding is easy. The purpose is to provide material.

As a result of diligent investigations to solve the above problems, the present inventors have found that fiber A, which is an organic fiber having a melting point of 200 ° C. or higher and a tensile breaking strain of 5% or higher, and 200 ° C. × 10 minutes dry heat shrinkage. Combining a fiber B with a rate of 1% or less with a thermoplastic resin and including an entangled yarn of the fiber A and the fiber B, it becomes a composite material having both high energy absorption performance and high thermal dimensional stability. I found.
Furthermore, the present inventors have found that a sandwich material in which the composite material is a core layer and a high-rigidity material is a skin layer is a material having excellent bending rigidity in addition to the above characteristics, and has led to the present invention.

  According to the present invention, since it is a material that is lightweight because it is made of a non-metallic material, it has both energy absorption performance and good moldability, so it can be used as an impact absorbing member that is installed to improve collision safety in automobiles, etc. Useful.

An example of a cross-sectional photograph of a composite material (state where there is an unimpregnated portion of matrix resin in the fiber bundle of fiber A) An example of a cross-sectional photograph of a composite material (state in which a matrix resin is impregnated in a fiber bundle of fiber A) Explanatory drawing of molding defects caused by wrinkles of molding substrate

  The present invention is a composite material containing fiber A and fiber B and a thermoplastic resin, wherein fiber A is an organic fiber having a melting point of 200 ° C. or higher and a tensile breaking strain of 5% or higher, and fiber B is 200 ° C. × 10 minutes The dry heat shrinkage is 1% or less, the fiber B is 10 to 100 parts by volume with respect to 100 parts by volume of the fiber A, and the composite material includes the entangled yarn of the fiber A and the fiber B Material. Hereinafter, the composite material of the present invention will be described.

[Fiber A]
The fiber A in the present invention refers to an organic fiber having a tensile breaking strain of 5% or more and a melting point of 200 ° C. or more. The energy absorbed by the material is due to the load that the material takes on and the amount of deformation of the material. Therefore, when increasing the energy absorption amount of the material, it is necessary to increase the strength and fracture strain of the material itself. However, if only the material strength is high and the breaking strain is small, the impact load becomes excessively large, and the material support material and the counterpart material are seriously damaged. Conversely, if the breaking strain is large and the strength is low, more materials are used. This is necessary and causes practical problems such as an increase in weight. Accordingly, as the fiber A, an organic fiber having a tensile break strain of 5% or more, which is a high level with good balance, is effective.

  On the other hand, the molding temperature of a particularly useful resin among the thermoplastic resins serving as the matrix of the composite material is 170 ° C. or higher except for exceptions, so that the fiber A has a melting point of 200 ° C. or higher. If the melting point of the reinforcing fiber of the composite material is lower than the molding temperature, it will melt together with the thermoplastic resin and a composite material cannot be obtained. In the molding process, it is not preferable as a reinforcing material that the reinforcing fiber is largely deteriorated by heat. Generally, since the orientation and crystals of the polymer in the organic fiber are easily relaxed near the melting point, the melting point of the fiber A is preferably higher by 10 ° C. than the molding temperature. It is more preferable that the melting point of the fiber A is 20 ° C. or more higher than the molding temperature.

  In addition, the molding temperature of general-purpose plastics to which polyolefins, etc., which are most frequently used among thermoplastic resins, is usually 170 ° C or higher, but the molding temperature of engineering plastics such as polyamide, polycarbonate, and polyester, which have higher heat resistance, is higher. 230 ° C. or higher. From this, if the melting point of the fiber A used in the present invention is 250 ° C. or more, it can be used not only for general-purpose plastics but also for engineering plastics, which is more preferable. Here, the melting point of 200 ° C. or higher means that it does not melt at a temperature lower than 200 ° C.

  Examples of such fibers A include polyether ether ketone fibers, polyphenylene sulfide fibers, polyether sulfone fibers, polyester fibers, aliphatic polyamide fibers, polyvinyl alcohol fibers, polyparaphenylene isophthalamide fibers, and the like. Fiber, polyamide fiber, and polyvinyl alcohol fiber are preferable because they have a good balance between physical properties such as mechanical properties and heat resistance, and price. Among these, polyester fiber or nylon fiber is particularly preferable.

  Examples of the skeleton of the polyester fiber include polyalkylene naphthalene dicarboxylate, polyalkylene terephthalate, polylactic acid, and particularly stereocomplex polylactic acid. Among these, polyalkylene naphthalene dicarboxylate and polyalkylene terephthalate having a melting point of 250 ° C. or higher are preferable. These may be used alone, in combination of two or more, or may be copolymerized.

  As the polyalkylene naphthalene dicarboxylate, a polyester having alkylene-2,6-naphthalene dicarboxylate or alkylene-2,7-naphthalene dicarboxylate as a main repeating unit is preferable. The content of alkylene naphthalene dicarboxylate in the polyester is preferably 90 mol% or more, more preferably 95 mol% or more, and still more preferably 96 to 100 mol% or more. The alkylene group may be either an aliphatic alkylene group or an alicyclic alkylene group, but is preferably an alkylene group having 2 to 4 carbon atoms, and the polyalkylene naphthalene dicarboxylate is preferably polyethylene naphthalene dicarboxylate, more preferably Polyethylene-2,6-naphthalenedicarboxylate.

  As the polyalkylene terephthalate, a polyester having alkylene-terephthalate as a main repeating unit is preferable. The content of alkylene terephthalate in the polyester is preferably 90 mol% or more, more preferably 95 mol% or more, and still more preferably 96 to 100 mol%. The alkylene group may be either an aliphatic alkylene group or an alicyclic alkylene group, but is preferably an alkylene group having 2 to 4 carbon atoms, and the polyalkylene terephthalate is preferably polyethylene terephthalate.

  All repeating units of the polyester fiber may contain a third component within a range not impairing the object of the present invention. Examples of the third component include (a) compounds having two ester-forming functional groups, such as aliphatic dicarboxylic acids such as oxalic acid, succinic acid, sebacic acid, and dimer acid, cyclopropanedicarboxylic acid, and hexahydroterephthalic acid. Arocyclic dicarboxylic acid, phthalic acid, isophthalic acid, naphthalene-2,7-dicarboxylic acid, diphenylcarboxylic acid and other aromatic dicarboxylic acids, diphenyl ether dicarboxylic acid, diphenylsulfonic acid, diphenoxyethanedicarboxylic acid, 3,5- Carboxylic acid such as sodium dicarboxybenzene sulfonate, glycolic acid, p-oxybenzoic acid, oxycarboxylic acid such as p-oxyethoxybenzoic acid, propylene glycol, trimethylene glycol, diethylene glycol, tetramethylene glycol, hexamethyl Glycol, neopentylene glycol, p-xylene glycol, 1,4-cyclohexanedimethanol, bisphenol A, p, p'-dihydroxyphenylsulfone, 1,4-bis (β-hydroxyethoxy) benzene, 2,2- Oxy compounds such as bis (p-β-hydroxyethoxyphenyl) propane and polyalkylene glycol, functional derivatives thereof, compounds having a high polymerization degree derived from the carboxylic acid, oxycarboxylic acid, oxy compound or functional derivatives thereof And (b) a compound having one ester-forming functional group, such as benzoic acid, benzyloxybenzoic acid, and methoxypolyalkylene glycol. Furthermore, (c) a compound having three or more ester-forming functional groups, such as glycerin, pentaerythritol, trimethylolpropane, etc. can be used within the range where the polymer is substantially linear. These polyesters may contain a matting agent such as titanium dioxide, and a stabilizer such as phosphoric acid, phosphorous acid, or an ester thereof.

  Examples of the nylon fiber include those made of aliphatic polyamide such as nylon 66, nylon 6, polyamide 46 resin, and polyamide 610 resin. These may be used alone or in combination of two or more. Among these, nylon 66 or nylon 6 fiber, which is excellent in versatility and inexpensive, is preferable, and nylon 66 fiber having a melting point of 250 ° C. or higher is more preferable.

The fiber A in the present invention preferably has a continuous length, and a discontinuous length fiber may be used in combination therewith.
The form of the fiber A is preferably a twisted yarn cord or a woven or knitted fabric composed of a twisted yarn cord.

  The fiber A used in the present invention is preferably a multifilament. Generally, organic fibers include a monofilament that is a product with one relatively thick single yarn, and a multifilament that is formed of a plurality of relatively thin single yarns and is bundled. Monofilaments are expensive due to their low productivity, and are therefore used for special applications such as screen baskets, and multifilaments are used for general clothing and industrial materials. A relatively inexpensive multifilament is preferred for the composite material of the present invention. The number of single yarns constituting the multifilament is preferably 2 to 10,000, and more preferably 50 to 5000. Furthermore, 100 to 1000 is more preferable. When the number of single yarns exceeds 10,000, production is difficult and handling of fibers as a multifilament is remarkably deteriorated.

  The total fineness of the fiber A multifilament used in the present invention is preferably from 100 dtex to 10,000 dtex, and more preferably from 200 dtex to 8000 dtex. Furthermore, 500 dtex to 5000 dtex is more preferable. When the fineness is less than 100 dtex, the strength of the yarn itself is reduced, so that it is difficult to obtain a reinforcing effect on the composite material. When the fineness is larger than 10,000 dtex, it is difficult to produce the yarn.

  In the present invention, the fineness of the single yarn constituting the fiber A multifilament is preferably 1 to 30 dtex, and the upper limit is preferably 25 dtex or less, particularly preferably 20 dtex or less. The lower limit is preferably 1.5 dtex or more. Most preferably, it is in the range of 2 to 20 dtex. By being in such a range, it becomes easy to achieve the object of the present invention. If the single yarn fineness is less than 1 dtex, there is a tendency that a problem occurs in the yarn-making property.

The tensile strength of the fiber A used in the present invention is preferably 6 to 11 cN / dtex. More preferably, it is 7-10 cN / dtex. If it is less than 6 cN / dtex, the strength of the resulting composite material tends to be too low.
Further, the fiber A of the present invention preferably has a dry heat shrinkage of 20% or less at 180 ° C. for 30 minutes. More preferably, it is 18% or less. If it exceeds 20%, the dimensional change of the fiber due to heat at the time of molding increases, and the molded shape of the reinforcing resin tends to be defective.

  Moreover, you may process the fiber surface with a suitable processing agent in order to improve the characteristic of a resin molded product. In this case, 0.1 to 10 parts by weight, preferably 0.1 to 3 parts by weight, of the surface treatment agent may be attached to the fiber surface with respect to 100 parts by weight of the fiber. The surface treatment agent may be appropriately selected according to the type of thermoplastic resin.

[Fiber B]
The fiber B in the present invention refers to a fiber material having a dry heat shrinkage of 1% or less at 200 ° C. for 10 minutes. The dry heat shrinkage referred to herein is defined by JIS L1013 or the like, and is a dimensional change in the fiber axis direction when the fiber is exposed at a predetermined temperature for a predetermined time. In the present invention, as described above, The heat exposure condition considering the molding temperature of the plastic resin was 200 ° C. × 10 minutes. The heat shrinkage characteristics of the fiber A vary depending on the type of fiber, the production method, and the like, but the dry heat shrinkage rate at 200 ° C. × 10 minutes is approximately 5% or more except for exceptions. Since the fiber B functions as a role of suppressing the heat shrinkage of the fiber A, the heat shrinkage needs to be smaller than that of the fiber A. In the heat dimension stabilizing component of the present invention, the fiber B needs to be at least 1% or less.

  Such fibers B include polyparaphenylene terephthalamide fibers, polyparaphenylene isophthalamide fibers, poly (paraphenylene) -copoly (3,4-diphenyl ether) terephthalamide fibers, and other aramid fibers, polybenzazole fibers, Examples include organic fibers with high thermal dimensional stability such as polyarylate fibers, polyimide fibers, and polyketone fibers, ceramic fibers such as carbon fibers, glass fibers, alumina fibers, and basalt fibers, and metal fibers such as steel fibers and aluminum fibers. Metal fibers are not preferred because they have a large specific gravity and increase the weight of the composite material itself. From the viewpoint of lightness, organic fibers and ceramic fibers having high thermal dimensional stability are preferable, and among them, organic fibers having relatively high tensile rupture strain and high energy absorption performance and high thermal dimensional stability are more preferable.

The fibers B in the present invention preferably have a continuous length, and discontinuous length fibers may be used in combination therewith.
The fiber B used in the present invention is preferably a multifilament.
The total fineness of the fiber B multifilament used in the present invention can be appropriately selected in consideration of the total fineness of the fiber A multifilament, but is preferably 100 dtex to 20000 dtex, more preferably 200 dtex to 10000 dtex, and further preferably 500 dtex to 5000 dtex. . When the fineness is smaller than 100 dtex, it is difficult to sufficiently suppress the thermal shrinkage of the fiber A, and when the total fineness is larger than 20000 dtex, it is difficult to manufacture the yarn.

  In the present invention, the fineness of the single yarn constituting the fiber B can be appropriately selected in consideration of the fiber A, but it is preferably 0.5 to 30 dtex, and the upper limit is 25 dtex or less, particularly 20 dtex. The following is preferable. The lower limit is preferably 1.0 dtex or more. Most preferably, it is in the range of 1.5 to 20 dtex. By being in such a range, it becomes easy to achieve the object of the present invention. When the single yarn fineness is less than 0.5 dtex, there is a tendency that a problem occurs in the yarn forming property.

[Entanglement of fiber A and fiber B]
The fibers A and B in the present invention are preferably intertwined with each other, and the composite material includes the intertwined yarns of the fibers A and B. The term “entanglement” as used herein refers to a state in which the fibers A and B are entangled and compounded. As a method for obtaining such an entangled yarn, interlace processing, taslan processing, composite temporary processing using a known facility can be used. Examples include twisting, stretch breaking, and twisting, which will be described later. However, as will be described later, fiber A may be pre-twisted to control the impregnation state of the thermoplastic resin. Also when twisting, twisting is preferable. In order to suppress the thermal shrinkage of the fiber A, the thermal shrinkage suppressing effect is higher when the fibers A and the fiber B are combined in an entangled state rather than simply being juxtaposed. Moreover, in these processing methods, it is also possible to produce a path difference between the fiber A and the fiber B, whereby the thermal dimensional stability and energy absorption performance can be appropriately adjusted. Specifically, it can be easily obtained by making various twisted yarns using the fiber B as the core yarn and the so-called wall twisted yarn in the twisting process, using the fiber A as the sheath yarn.

The ratio of the fiber A and the fiber B in the entangled yarn can be selected as appropriate in consideration of the effect of suppressing heat shrinkage and the energy absorption performance, but if the fiber B having a low tensile breaking strain is excessively used, the energy absorption performance is inhibited. Therefore, as for the ratio of both, 10-100 volume parts of fiber B are preferable with respect to 100 volume parts of fibers A, and 20-80 volume parts are more preferable.
The ratio of the entangled yarn of the fiber A and the fiber B in the composite material is preferably 50 to 90 parts by volume when the whole fiber is 100 parts by volume.

[Twisted yarn]
The form of the fiber A of the present invention is preferably a twisted twisted cord, or a woven or knitted fabric composed of the twisted cord. By applying the twist, the fiber bundle is tightened, and impregnation of the resin into the fiber bundle is suppressed. The impregnation of the resin will be described in detail later, but it is preferable that the fiber A is a multifilament and that the fiber bundle is substantially impregnated with a thermoplastic resin. It is preferable that the thermoplastic resin is substantially unimpregnated.

  When the fiber A is a multifilament, the yarn supplied from the yarn manufacturer is in an untwisted state. Therefore, when this raw yarn is processed as it is, the alignment of the single yarn is disturbed and the fiber performance is fully expressed. It may not be possible. In addition, untwisted yarns are poor in handling because of low convergence. In order to improve the alignment and handling of such yarns, it is effective to add twist to the fibers. In addition, a twisted yarn cord obtained by adding a twist to the raw yarn is effective in terms of impact resistance because it has higher elongation than the raw yarn and higher bending fatigue. Moreover, the single yarn which comprises a multifilament can be close-packed by using a twisted-yarn cord.

  There is no particular limitation on the twisted structure, and it may be a single twist that twists the multifilament only once, or may use two or more yarns and various twists composed of a lower twist and an upper twist. In consideration of the strength and handleability of the yarn, various twists that can easily suppress the occurrence of snare are preferable, and the number of constituents of the lower twist and the upper twist may be appropriately set according to the required physical properties. Also, as described above, in the case of various twists, a composite twisted yarn in which one side is fiber A and the other side is fiber B may be used. May be. The number of twists of the fiber is defined in the range of 1 to 1000 times, preferably 10 to 1000 times per meter. Among these, considering the toughness, which is the product of the strength and elongation of the twisted yarn cord, the number of twists per meter is preferably 30 to 700 times, more preferably 50 to 500 times. If the number of twists exceeds 1000, the strength of the twisted cord is too low, which is not preferable in view of the reinforcing effect of the composite material. Moreover, when the number of twists exceeds 1000, the productivity is extremely deteriorated. The number of lower twists and upper twists is set in the above-mentioned twist number range, but considering the suppression of snar, it is preferable to set the twist number by combining the twist coefficients of the lower twist and the upper twist. In addition, it is also preferable from the viewpoint of the durability of the twisted cord that the balance twist is equal to the number of times of the lower twist and the upper twist as used in the tire cord.

In the present invention, the form of the fiber A and the entangled yarn may be a fabric form such as a woven fabric or a knitted fabric, that is, a bi-directional material, even if a plurality of twisted yarn cords obtained by twisting the fiber are used as they are as a unidirectional material. Can also be used. The composite material of the present invention can be appropriately selected depending on the form used for each of the unidirectional material and the bidirectional material. The twisted yarn cord is defined by the fineness of the raw yarn, the number of twists, the distance between the cords, and the like. The preferred basis weight of the twisted yarn cord is 30 to 1000 g / m ² , more preferably 50 to 600 g / m ² . is there. When the basis weight of one layer of the twisted yarn cord is smaller than 30 g / m ² , the necessary energy absorption performance cannot be obtained. On the other hand, if it exceeds 1000 g / m ² , it becomes difficult for the resin to enter between the fiber bundles, and the composite material tends to be too heavy. Further, when forming the unidirectional material and the bidirectional material, all of the constituent fibers may be entangled yarns, or a twisted cord of only fiber A and an entangled yarn may be appropriately combined. At this time, it is necessary to consider the ratio of the fiber A and the fiber B in the entangled yarn as the ratio of both, but generally, the fiber A is preferably 0 to 50 parts by volume with respect to 100 parts by volume of the entangled yarn. 5 to 25 parts by volume is more preferable. When the twisted cord of only the fiber A is 50 parts by volume or more, the ratio of the fiber B in the composite material is extremely reduced, so that the thermal dimensional stability is impaired.

Examples of the weaving structure in the woven fabric include plain weave, twill weave and satin weave. Among these, a plain weave that is easily impregnated with resin between the fiber bundles of the fibers A is preferable. The warp density of the woven fabric is preferably 5 to 50 per 2.5 cm, more preferably 10 to 40, considering the resin impregnation between the fiber bundles. When the warp density is less than five, the yarn is easy to move and the meshes are likely to be opened, and the handleability of the fabric is remarkably deteriorated. If the warp density is more than 50, the distance between the fiber bundles becomes too narrow, and the resin hardly penetrates between the fiber bundles, and the target composite material cannot be obtained. The weft density of the woven fabric is preferably 1 to 50 per 2.5 cm, more preferably 1 to 40, considering the resin impregnation between the fiber bundles. Among the woven fabrics, there are some woven fabrics in which the performance of the fabric is left to the warp and the weft is used to suppress the extreme opening of the warp. Such warp woven fabrics are used for tire cords and the like, and are woven fabrics with extremely few wefts, but are also applicable in the present invention. Accordingly, it is sufficient that the weft density per 2.5 cm is one or more. On the other hand, if the warp density is too high and the number is 50 or more, the distance between the fiber bundles becomes too narrow and the resin hardly penetrates between the fiber bundles, and the target composite material cannot be obtained. The density of the warp and the weft may be the same or unbalanced as long as it is within the above range. The basis weight of the fabric, that is, the basis weight of one layer of the fiber fabric in the composite material, is preferably 30 to 500 g, more preferably 50 to 400 g per 1 m ² in consideration of the resin impregnation between the fiber bundles. If the basis weight is less than 30 g, the strength of the woven fabric is lowered, so that the reinforcing effect on the composite material cannot be obtained. When the basis weight is more than 500 g, the distance between the fiber bundles becomes narrow, and it becomes difficult to impregnate the resin between the fiber bundles, and the target composite material cannot be obtained.

Examples of the knitting structure in the knitted fabric include warp knitting, weft knitting, and Russell knitting. Among them, in consideration of the strength of the knitted fabric, Russell knitting that is easy to obtain a stronger structure is preferable. The basis weight in the case of a knitted fabric, that is, the basis weight of one layer of the fiber knitted fabric in the composite material is preferably 30 to 500 g, more preferably 50 to 400 g per 1 m ² in consideration of the resin impregnation between the fiber bundles. If the basis weight is less than 30 g, the strength of the knitted fabric is lowered, so that the reinforcing effect on the composite material cannot be obtained. When the basis weight is more than 500 g, the distance between the fiber bundles becomes narrow, and it becomes difficult to impregnate the resin between the fiber bundles, and the target composite material cannot be obtained.

[Resin impregnation into fiber]
In the present invention, the resin is impregnated between the fiber bundles of the fiber component composed of the fiber A, the fiber B, and the entangled yarns of both, but the fiber A has a portion not impregnated with the resin. That is, it is preferable that the fiber A has a low degree of impregnation in the fiber bundle. The inside of the fiber bundle of the fiber A is substantially unimpregnated with the thermoplastic resin, so that better physical properties are obtained. In the composite material of the present invention, the fiber A and the fiber bundle of the entangled yarn preferably have a structure substantially impregnated with a thermoplastic resin. If the space between the fiber bundles is not sufficiently filled with resin, voids remain between the fiber bundles, and the strength of the composite material is reduced. In the present invention, the structure in which the resin is substantially impregnated between the fiber bundles means that the void ratio between the fiber bundles is 10% or less. The verification can be performed by weighing the sample whose volume can be calculated or by observing a cross-section with a microscope.

  In the composite material of the present invention, the inside of the fiber bundle of the fiber A may be substantially impregnated with thermoplastic resin or unimpregnated, but considering impact resistance, Since it is considered that a certain degree of freedom is effective for energy absorption, it is more preferable that the inside of the fiber bundle of the fiber A is substantially not impregnated with resin. In the present invention, the inside of the fiber bundle of the fiber A, which is a multifilament, is substantially not impregnated with a resin. This means that the void ratio between the fiber bundles is within the fiber bundle of the fiber A in a composite material having a void ratio of 10% or less. It indicates that the resin penetration rate is 50% or less.

  The verification can be judged by calculating how much the single yarn constituting the multifilament can be taken out from the fiber A taken out from the composite material, that is, the free single yarn rate. For example, in the case of the fiber A composed of 250 single yarns, if 150 free single yarns can be taken out, the free single yarn rate is 60% and the resin impregnation rate is the remaining 40%. Further, the resin impregnation rate can also be confirmed by microscopic observation such as an electron microscope or an optical microscope, and can be specifically obtained from the ratio of the void area in the cross section of the composite material.

  FIG. 1 shows an example of a cross-sectional photograph of the composite material of the present invention in which there is an unimpregnated portion of the matrix resin in the fiber bundle. FIG. 1 shows a state in which the matrix resin is impregnated in the fiber bundle and the fibers and the matrix resin are in good contact. An example of a cross-sectional photograph of the composite material is shown in FIG. The round shape observed in the photograph is the outline of the cross section of the single yarn of the fiber A, and the fiber bundle is what the circles appear to gather closely. It is the thermoplastic resin that appears white on the outside of the circle, and the void that appears black. In FIG. 1, voids are observed inside the fiber bundle, and in FIG. 2, it is observed that the thermoplastic resin has entered the fiber bundle.

  By setting it as the above structures, the intensity | strength of a composite material can be maintained with the thermoplastic resin between the fiber component and fiber bundle which consist of the fiber A, the fiber B, and both entangled yarn. In addition, the fiber A in the composite material, strictly speaking, the single yarn constituting the fiber has a degree of freedom of deformation and movement, so that the impact received by the composite material is absorbed by these degrees of freedom accompanied by breakage. Therefore, the material is excellent in impact resistance.

  The degree of resin penetration into the fiber bundle is determined by selecting the type of thermoplastic resin in addition to the above-described twisted yarn, woven fabric, and knitted fabric, as well as the molding pressure in the resin impregnation step between the fiber bundles as described later, the thermoplastic resin The temperature can be controlled by the temperature. On the other hand, when a fiber bundle of fiber A is impregnated with a thermosetting resin to obtain a composite material, the thermosetting resin before curing is impregnated into the fiber bundle because of its low viscosity. Decreases, for example, impact resistance decreases.

[Composite material]
The present invention is a composite material comprising a fiber component composed of fiber A, fiber B, and entangled yarns of both, and a thermoplastic resin. In the present invention, the composition ratio of the fiber component and the thermoplastic resin is preferably 20 parts to 900 parts, more preferably 25 parts to 400 parts, with respect to 100 parts of the fiber component by volume. . When the ratio of the thermoplastic resin to 100 parts of the fiber component is less than 20 parts, the fiber bundles of the fiber component are full of voids, and the mechanical strength of the composite material is greatly reduced. On the contrary, if it exceeds 900 parts, the reinforcing effect of the fiber component will not be sufficiently exhibited.

The basis weight of the fiber component per 10 mm thickness in the composite material is preferably 1000 to 12000 g / m ² . More preferably, it is 2000-10000 g / m < ² >. When the basis weight of the fiber component is smaller than 1000 g / m ² , the necessary energy absorption performance is hardly exhibited. On the other hand, if it exceeds 12000 g / m ² , voids are likely to occur between the fiber bundles of the fiber component, and the mechanical strength of the composite material may be greatly reduced.

[Thermoplastic resin]
Since the composite material of the present invention aims to have both high impact strength and high elasticity, the matrix is preferably a general thermoplastic resin, and an elastic body such as a thermoplastic elastomer or rubber is suitable. Absent. As a guideline, it is preferable that the thermal deformation temperature of the matrix is 80 ° C. or higher. The deflection temperature under load is used as an index of thermal deformability.

  Examples of the thermoplastic resin constituting the composite material of the present invention include vinyl chloride resin, vinylidene chloride resin, vinyl acetate resin, polyvinyl alcohol resin, polystyrene resin, acrylonitrile-styrene resin (AS resin), acrylonitrile-butadiene-styrene resin ( ABS resin), acrylic resin, methacrylic resin, polyethylene resin, polypropylene resin, polyamide 6 resin, polyamide 11 resin, polyamide 12 resin, polyamide 46 resin, polyamide 66 resin, polyamide 610 resin, polyacetal resin, polycarbonate resin, polyethylene terephthalate resin, Polyethylene naphthalate resin, boribylene terephthalate resin, polyarylate resin, polyphenylene ether resin, polyphenylene sulfide resin, polysulfone Fat, polyether sulfone resins, polyether ether ketone resins.

  Among these, vinyl chloride resin, polystyrene resin, ABS resin, polyethylene resin, polypropylene resin, polyamide 6 resin, polyamide 66 resin, polyacetal resin, polycarbonate resin, polyethylene terephthalate resin, polyethylene naphthalate resin, boribylene terephthalate resin, polyarylate resin Are more preferable, and polypropylene resin, polyethylene terephthalate resin, polycarbonate resin, polyamide 6 resin, and polyamide 66 resin are particularly preferable.

[Production method]
A preferred method for producing a molded body made of the composite material of the present invention is to form a composite by impregnating resin between fiber bundles of fiber components consisting of fibers A, fibers B and entangled yarns of both, and the obtained composite material. Consists of shaping.

  The method for impregnating the resin between the fiber bundles is not particularly limited, and may be appropriately selected according to the form of the fiber component to be used. For example, when the fiber component is in the form of a fabric such as a woven fabric or a knitted fabric, the woven fabric / knitted fabric and the resin film are laminated at a temperature at which the thermoplastic resin melts and the fiber component does not melt using a press molding machine or a vacuum molding machine. A composite material in which a thermoplastic resin is impregnated between fiber bundles can be obtained by pressurizing or depressurizing the nonwoven fabric. In addition to the above press molding and vacuum molding, a composite material in which a thermoplastic resin is impregnated between fiber bundles can also be obtained by extrusion molding or pultrusion molding. For example, a plurality of fiber components tailored to a creel stand are drawn using a yarn guide while being fed under a constant tension, and introduced into an impregnation die of a pultrusion machine. Here, after impregnating the molten resin between the fiber components, the UD sheet of continuous fibers can be obtained by drawing out from the impregnation die and cooling.

There is no particular limitation on the shaping method, and it may be performed at the same time when the resin is impregnated between the fiber bundles, or may be shaped again after the resin is once impregnated between the fiber bundles. When resin impregnation and shaping are performed simultaneously, a molded body can be easily obtained by using a mold that can obtain a desired shape. Even when the resin impregnation and the shaping are performed separately, the shaping can be performed relatively easily by using a mold having a desired shape.
Thus, by devising the shaping method, it is possible to produce a large-sized / planar / thin member to a small-sized / complex shaped member. Examples of the shape of the molded body include three-dimensional forms such as corrugates, trusses, and honeycombs in addition to flat plates.

  Control of resin impregnation between fiber bundles and inside the fiber bundle of the fiber component is appropriately adjusted according to the molding conditions in addition to the above-mentioned selection of twisted yarn, woven fabric, knitted fabric, and thermoplastic resin. In general, if the molding temperature or pressure is increased, the resin's permeability increases because the melt viscosity of the resin decreases. The temperature is preferably in the range from the melting point temperature to the melting point temperature + 50 ° C. when the resin is a crystalline resin, and from the glass transition temperature to the melting point + 50 ° C. when the resin is an amorphous resin. The pressure is preferably in the range of 0.01 MPa to 20 MPa, and the time is preferably in the range of 30 seconds to 1 hour.

  As for the combination of the fiber component and the thermoplastic resin, when the resin to be used is a crystalline resin, the fiber component preferably has a melting point higher by 10 ° C. than the melting point of the resin. When the resin to be used is an amorphous resin, the melting point of the fiber component is preferably higher by 10 ° C. or more than the glass transition temperature of the resin. From this viewpoint, the fiber A is a polyester fiber or a nylon fiber, and the thermoplastic resin is preferably a combination of polypropylene resin, polyethylene terephthalate resin, polycarbonate resin, polyamide 6 resin, or polyamide 66 resin.

[Shock absorption]
The composite material of the present invention is characterized by a test speed of 11 m / sec, an opening diameter of a test piece pressing jig of 40 mm, and an absorbed energy in a high-speed punching test with a 10 mm diameter striker of 10 J or more. More preferably, the absorbed energy is 12 J or more. As described above, a composite material having desired energy absorption performance can be obtained from the type of organic fiber, the basis weight, the matrix thermoplastic resin, the degree of impregnation between the fiber bundles, and the degree of impregnation inside the fiber bundle. The upper limit of absorbed energy is substantially 500J.

[Sandwich material]
The present invention further includes a sandwich material having the above composite material as a core material. The sandwich material of the present invention is constituted by using the above composite material as a shock absorbing material for a core material and combining with a skin layer. The skin material is preferably a highly rigid material, which will be described later. The volume ratio of the skin material to the core material is preferably 40 to 9900 parts of the core material with respect to 100 parts of the skin material. More preferably, the core material is 100 to 1000 parts with respect to 100 parts of the skin material. When the volume of the core material with respect to 100 parts of the skin material is smaller than 40 parts, the sandwich material has high strength and rigidity, but it is difficult to exhibit sufficient shock absorption. On the contrary, when the volume of the core material with respect to 100 parts of the skin material becomes larger than 9900 parts, the strength and rigidity remain at the same level as the case of the core material alone, and it is not necessary to take the time and effort to make a sandwich material.

[Skin material]
The skin material in the sandwich material is preferably a high-rigidity material made of a fiber-reinforced composite material including reinforcing fibers having a specific elasticity (E) defined by the following formula (1) of 2.5 or more.
E = M / D / 9.8 (1)
Here, E is the specific elasticity, M is the elastic modulus (MPa) of the fiber, and D is the density (g / cm ³ ) of the fiber.
Specific examples of such reinforcing fibers include glass fibers, carbon fibers, steel fibers (stainless fibers), inorganic fibers such as ceramic fibers, and aramid fibers. Among these, glass fiber, carbon fiber, and aramid fiber are preferable from the viewpoint of versatility and handleability.

  The reinforcing fiber is preferably a multifilament composed of a plurality of single yarns (monofilaments). This is because monofilament has low productivity and is expensive. The number of single yarns constituting the multifilament is preferably 2 to 100,000, more preferably 50 to 50,000. Furthermore, 100 to 30000 is more preferable. When the number of single yarns exceeds 100,000, production is difficult and handling of fibers as a multifilament is remarkably deteriorated.

  The total fineness of the reinforcing fibers as the multifilament is preferably from 100 dtex to 100,000 dtex, more preferably from 200 dtex to 50,000 dtex. Furthermore, 500 dtex to 30000 dtex is more preferable. If the fineness is less than 100 dtex, the fiber becomes inferior and the fiber becomes expensive. When the fineness is larger than 100,000 dtex, it is difficult to produce the yarn.

  The fineness of the single yarn constituting the reinforcing fiber is preferably 0.1 to 20 dtex, and the upper limit is preferably 15 dtex or less, particularly preferably 10 dtex or less. The lower limit is preferably 0.3 dtex or more. Most preferably, it is in the range of 0.5 to 5 dtex. By being in such a range, it becomes easy to achieve the object of the present invention. If the single yarn fineness is less than 0.1 dtex, there is a tendency that a problem occurs in the spinning property. If the fineness is too large, the reinforcing effect is lowered and the physical properties of the sandwich material tend to be lowered.

The strength of the reinforcing fiber constituting the highly rigid material is preferably 500 MPa or more. More preferably, it is 1000 MPa or more. If it is less than 500 MPa, the strength of the obtained sandwich material tends to be too low.
The elastic modulus of the reinforcing fiber is preferably 30 GPa or more. More preferably, it is 50 GPa or more. If it is less than 30 GPa, the rigidity of the obtained sandwich material tends to be too low.

There is no limitation in particular in the manufacturing method of the fiber which has such a physical property. For example, the target reinforcing fiber can be obtained by a method of drawing an undrawn yarn obtained by melt spinning, a method of wet spinning a solution containing raw material components, a method of firing and carbonizing a raw material fiber.
Further, the fiber surface may be treated with an appropriate treating agent for the purpose of enhancing the properties of the sandwich material and the molded product. In this case, 0.1 to 10 parts by weight, preferably 0.1 to 3 parts by weight, of the surface treatment agent may be attached to the fiber surface with respect to 100 parts by weight of the fiber. The surface treatment agent may be appropriately selected according to the type of thermoplastic resin.

  Moreover, as a matrix which comprises a highly rigid material, vinyl chloride resin, vinylidene chloride resin, vinyl acetate resin, polyvinyl alcohol resin, polystyrene resin, acrylonitrile-styrene resin (AS resin), acrylonitrile-butadiene-styrene resin (ABS resin) , Acrylic resin, methacrylic resin, polyethylene resin, polypropylene resin, polyamide 6 resin, polyamide 11 resin, polyamide 12 resin, polyamide 46 resin, polyamide 66 resin, polyamide 610 resin, polyacetal resin, polycarbonate resin, polyethylene terephthalate resin, polyethylene naphthalate Resin, Boribylene terephthalate resin, Polyarylate resin, Polyphenylene ether resin, Polyphenylene sulfide resin, Polysulfone resin, Polysulfone resin Polyether sulfone resins, thermoplastic resins such as polyether ether ketone resins, epoxy resins, polyurethane resins, unsaturated polyester resins, phenol resins, urea resins, melamine resins, and thermosetting resins such as diallyl phthalate resin. Among these, thermoplastic resins excellent in moldability, productivity, and processability are preferable. Among thermoplastic resins, vinyl chloride resin, polystyrene resin, ABS resin, polyethylene resin, polypropylene resin, polyamide 6 resin, polyamide 66 resin, polyacetal resin Polycarbonate resin, polyethylene terephthalate resin, polyethylene naphthalate resin, boribylene terephthalate resin, and polyarylate resin are more preferable, and polypropylene resin, polyamide 6 resin, and polyamide 66 resin are particularly preferable.

  In the high-rigidity material in the skin material, the form of the reinforcing fiber includes a discontinuous fiber such as a short fiber or a long fiber, and a continuous fiber such as a fabric form such as a woven fabric or a knitted fabric or a unidirectional material in which fibers are aligned in one direction. These may be used as appropriate according to the use of the sandwich material or the molded body. In the case of discontinuous fibers, the fiber length is preferably 1 to 100 mm, more preferably 5 to 50 mm. When the fiber length is shorter than 1 mm, it is difficult to obtain a sufficient reinforcing effect. On the contrary, when it becomes longer than 100 mm, the handleability as a fiber reinforcing material will worsen. In the case of continuous fibers, it is more preferable from the viewpoint of the reinforcing effect that the fibers are continuous from one end of the material or the molded product to the other end, but this is not essential. Depending on the mechanical properties required for the material or the molded product, there may be some tears and it may be discontinuous.

Further, in the high-rigidity material in the skin material, the inside of the reinforcing fiber bundle is preferably impregnated with a matrix resin, and the degree of impregnation of the resin is preferably 80% or more, more preferably 90% or more. More preferably, it is 95% or more. If the degree of resin impregnation into the fiber bundle is less than 80%, neither the strength nor rigidity of the sandwich material will reach the target level.
The verification of the degree of resin impregnation into the reinforcing fiber bundle is done by removing one of the fiber component or resin component in the high-rigidity material whose volume is known by means of dissolution, decomposition, combustion, etc. This is done by calculating.

In the high-rigidity material in the skin material, the composition ratio of the reinforcing fiber and the matrix resin is preferably 20 parts to 900 parts, more preferably 25 parts to 400 parts, with respect to 100 parts of the reinforcing fiber by volume ratio. It is.
When the volume ratio of the matrix resin to 100 parts of the reinforcing fiber is less than 20 parts, voids are likely to be generated in the material, and the mechanical strength of the sandwich material is greatly reduced. On the contrary, if the amount exceeds 900 parts, the reinforcing effect of the reinforcing fiber is not sufficiently exhibited.

By using a high-rigidity material as described above for the raw material, composition, and configuration, strength and rigidity can be imparted to the sandwich material and the molded body.
The matrix resin of the high-rigidity material that is the skin material and the matrix resin of the composite material that is the core material and the shock absorbing material are not necessarily the same, and are different as long as they are welded resins or compatible resins. May be.

[Manufacture of sandwich materials]
The method for manufacturing the sandwich material is either a method in which the skin material and the core material are separately prepared in advance and then combined, or a method in which the skin material and the core material are combined in one step. Also good.
For example, as a method of compounding in two stages, reinforcing fibers and matrix resin as raw materials for the skin material and the core material are charged into a press molding machine, a vacuum molding machine, an extrusion molding machine, a pultrusion molding machine, and the like, and molded. At this time, since it is preferable in terms of performance that the high-rigidity material is impregnated with resin in the fiber bundle, it is often molded under more severe temperature, pressure, and time conditions. Thereafter, the core material composite material molded under relatively mild conditions is welded using a press molding machine, a vacuum molding machine, a high frequency welding machine, or the like. If the molding method of the composite material of the high-rigidity material and the core material is the same and the molding conditions are not significantly different, molding may be performed in one step.

  Moreover, the molding method of the sandwich material may be appropriately set according to the shape of the application. If the matrix of the composite material is a thermoplastic resin, it may be shaped at a temperature higher than the glass transition temperature of the matrix resin in a simple form. In addition, even complex shapes can be shaped at temperatures around the melting point of the matrix resin. From this, it may be molded at the time of compounding, or once a substrate such as a flat plate is produced, it may be heated again and shaped and molded. Examples of the molding method include press molding using a mold or mold having a desired shape, vacuum molding, and the like, and it can be manufactured from a large-sized / planar / thin material member to a small-sized / complex shaped member. Examples of the shape of the molded body include three-dimensional forms such as corrugates, trusses, and honeycombs in addition to flat plates.

Control of resin impregnation between the fiber bundles of the reinforcing fiber and inside the fiber bundle is appropriately adjusted according to the molding conditions. In general, if the molding temperature or pressure is increased, the resin's permeability increases because the melt viscosity of the resin decreases. The temperature is preferably in the range from the melting point temperature to the melting point temperature + 50 ° C. when the resin is a crystalline resin, and from the glass transition temperature to the melting point + 50 ° C. when the resin is an amorphous resin. The pressure is preferably in the range of 0.01 MPa to 20 MPa, and the time is preferably in the range of 30 seconds to 1 hour.
When the resin used is a crystalline resin, the combination of the fiber and the matrix resin preferably has a fiber melting point higher by 10 ° C. or more than the resin melting point. When the resin used is an amorphous resin, the melting point of the fiber is preferably higher by 10 ° C. or more than the glass transition temperature of the resin.

[Formability]
Assuming that a sandwich material using a thermoplastic resin as a matrix once forms a flat plate-shaped molding substrate, this molding substrate is heated and cold-pressed with a desired mold to obtain a product. ing. However, if the base material for molding shrinks during heating, the base material will be wrinkled as shown in FIG. 3, and the surface of the product after cold pressing will not only leave wrinkle marks but also deteriorate the appearance. , The part locally overlapped by wrinkles becomes a spacer, and there is a problem that the peripheral part cannot be pressed sufficiently. In addition, the cold press said here is by pressing a base material heated and softened to a molding die whose temperature is controlled below the melting point of the matrix resin at a predetermined pressure, and performing heat exchange between the base material and the die. It refers to solidifying the thermoplastic matrix and shaping the substrate into the desired shape.

  Therefore, when the molding substrate is heated under desired conditions, the moldability can be evaluated by visually confirming the presence or absence of wrinkles. As an evaluation index, in order for local overlap as shown in FIG. 3 to occur, the height of the wrinkles needs to be equal to or greater than the thickness of the base material for molding. Can be judged.

[Molded body]
By using the composite material and a sandwich material using the composite material as a core material, a molded body that is a high-strength, high-rigidity impact-absorbing material can be provided. This invention includes the molded object obtained from said composite material. This invention includes the molded object obtained from said sandwich material.

[Auto parts]
The composite material and the sandwich material using the composite material as a core material are preferably used for automobile structural material parts, automobile exterior material parts, and automobile interior material parts. The present invention includes automotive structural material parts, automotive exterior material parts, and automotive interior material parts obtained from the above-described composite materials and / or sandwich materials. Examples of automobile structural parts include a crash structure and a floor pan. Examples of parts for automobile exterior materials include bumpers, bonnets, and fenders. Examples of automotive interior parts include instrument panels, door trims, center consoles, pillar covers, and the like.

Since the composite material is excellent in shock absorption, it is used for shock absorbing members such as bumpers, bonnets, fenders, floors, seats, door trims, pillar covers and the like.
Since the sandwich material having the composite material as a core material is excellent in rigidity as well as shock absorption, it is used for structural members such as crush structures and floor pans in addition to the above-mentioned applications.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited thereby.

(Organic fiber composite)
1) Dimensional change of composite material A material cut to 345 mm x 345 mm is placed in the center of a mold having a cavity size of 350 mm x 350 mm, and press molded under a predetermined condition with a commercially available hot press machine (manufactured by Meiki Seisakusho, MHPC). The area ratio between the vertical and horizontal dimensions of the composite material obtained and the original dimensions (345 mm x 345 mm) of the material was defined as a change in dimension of the composite material.
2) Measurement of void ratio between fiber bundles A sample was cut with a microtome, the cross section was observed with a microscope, and the void ratio was calculated by binarizing between the fiber bundles.
3) Evaluation of impregnation degree of resin into fiber For the highly rigid material, the cross section of the sample was observed with a microscope, and the impregnation degree of the resin was evaluated by calculating the ratio of bubbles. For composite materials, the fiber taken out from the sample is loosened using tweezers or a needle, and the free single yarn rate is calculated from the number of multifilament constituent single yarns that can be easily selected. For example, in the case of an organic fiber composed of 250 single yarns, if 150 free single yarns can be taken out, the free single yarn rate will be 60%, and the degree of resin impregnation will be the remaining 40% in terms of volume fraction. It will be.
4) Impact absorption energy evaluation The maximum load, the amount of absorbed energy, and the maximum load point displacement when a test piece was punched out according to ISO 6603-2 standard were measured using Shimadzu Hydro-shot HITS-P10 type. . The test piece size was 140 mm × 140 mm, the striker diameter was 10 mm, the opening diameter of the holding jig was 40 mm, and the test speed was 11 m / sec. The area of the displacement-load curve obtained in this test was taken as the absorbed energy amount of the test piece, and the value obtained by dividing this by the thickness of the test piece was evaluated as the specific absorbed energy amount.

(Sandwich material)
1) Impact absorption energy evaluation The impact absorption energy is evaluated in the same way as for organic fiber composites. The maximum is obtained when a test piece is punched in accordance with the ISO 6603-2 standard using the Hydroshot HITS-P10 model manufactured by Shimadzu Corporation. Load, absorbed energy, and maximum load point displacement were measured. The test piece size was 140 mm × 140 mm, the striker diameter was 10 mm, the opening diameter of the holding jig was 40 mm, and the test speed was 11 m / sec. The area of the displacement-load curve obtained in this test was taken as the absorbed energy amount of the test piece, and the value obtained by dividing this by the thickness of the test piece was evaluated as the specific absorbed energy amount.
2) Formability evaluation A 350 mm x 350 mm molding substrate was heated using a commercially available hot air dryer (manufactured by ASONE, ONW-450) at a set temperature of 250 ° C for 10 minutes, and visually checked for wrinkles. Confirmed.
As described above, as an evaluation index, in order for local overlap to occur as shown in FIG. 3, the wrinkle height needs to be equal to or greater than the thickness of the base material for molding. Formability was determined by the presence or absence. In other words, in the range of 350 mm × 350 mm, such wrinkles were marked as ◯, 2 or more and 4 or more as Δ, and 5 or more as x.

[Example 1]
Polyester fiber (manufactured by Teijin Fibers; P900M, 1100 dtex, tensile strength = 8.1 cN / dtex, tensile breaking strain = 13.5%, 200 ° C. × 10 minutes dry heat shrinkage = 19.2%) is used as the fiber A. As fiber B, aramid fiber (Technola (registered trademark), manufactured by Teijin Techno Products; T240, 1100 dtex, tensile strength = 24.5 cN / dtex, tensile breaking strain = 4.5%, 200 ° C. × 10 minutes, dry heat shrinkage = 0 ), And twisting them 87 times / m in the Z direction using a twisting machine, respectively, and combining them one by one and twisting 61 times / m in the S direction to entangle the yarn (1) Got.
Next, after a predetermined amount of polypropylene film (San-Tox Corp .; Santox-CP film, K grade, thickness 30 μm) is attached to an aluminum flat plate, the entangled yarn (1) is placed on this under a tension of 100 g. It was wound at a pitch of 1 mm. Next, after a predetermined amount of polypropylene film is pasted on the entangled yarn, the polypropylene film is melted by heating and pressing at a maximum temperature of 200 ° C. and a maximum pressure of 0.5 MPa for 10 minutes using a hot press machine. The polypropylene was infiltrated between the fiber bundles of the entangled yarn. Then, it cooled in the state which pressurized, and obtained the entangled yarn (1) / polypropylene integrated sheet of fiber volume content = 33%. Cut out from the obtained sheet to a dimension of 345 mm x 345 mm with reference to the entangled yarn direction, and in the center of a mold having a cavity dimension of 350 mm x 350 mm, 0 degree direction, 90 degree direction, 90 degree direction, 0 degree direction and 4 plies After being stacked, the mixture was again heated and pressurized for 10 minutes at a maximum temperature of 200 ° C. and a maximum pressure of 0.5 MPa, and then cooled in a pressurized state to obtain an entangled yarn (1) / polypropylene molded body.

[Example 2]
In Example 1, polyamide 6 film (manufactured by Unitika; emblem ON film, standard grade, thickness 25 μm) was used as the thermoplastic resin matrix, and the hot press conditions were heated at a maximum temperature of 240 ° C. and a maximum pressure of 0.5 MPa for 10 minutes. An entangled yarn (1) / polyamide 6 molded body was obtained in the same manner except that the pressure was applied.

[Example 3]
As fiber A, two polyester fibers (manufactured by Teijin Fibers; P900M, 1100 dtex) are aligned in an untwisted state and then subjected to a twist of 62 times / m in the Z direction. Made by Toho Tenax; HTS40 3K, 2000 dtex, tensile strength = 24 cN / dtex, tensile breaking strain = 1.9%, 200 ° C. × 10 minutes dry heat shrinkage = 0%) in the Z direction at a twist of 62 times / m These were put together one by one and twisted 44 times / m in the S direction to obtain an entangled yarn (2). Thereafter, an entangled yarn (2) / polyamide 6 integral sheet having a volume fiber content of 33% was obtained in the same manner as in Example 2, and this was molded in a mold in the same manner as in Example 2, A composite yarn (2) / polyamide 6 molded product was obtained.

[Example 4]
As the fiber A, two polyester fibers (manufactured by Teijin Fibers; P900M, 1100 dtex) are aligned in a non-twisted state, and then subjected to a lower twist of 62 times / m in the Z direction. Technora (registered trademark), manufactured by Teijin Techno Products; T240, 1100 dtex, tensile strength = 24.5 cN / dtex, tensile breaking strain = 4.5%, 200 ° C. × 10 minutes dry heat shrinkage = 0%) in the Z direction These were twisted at 87 times / m, and these were combined one by one and twisted 50 times / m in the S direction to obtain an entangled yarn (3). Thereafter, an entangled yarn (3) / polypropylene integral sheet having a volume fiber content rate of 33% was obtained in the same manner as in Example 1, and this was entangled in a mold as in Example 1. Yarn (3) / polypropylene molded body was obtained.

[Example 5]
In Example 4, a polyamide 6 film (manufactured by Unitika; emblem ON film, standard grade, thickness 25 μm) was used as the thermoplastic resin matrix, and the hot press conditions were heated and pressurized at a maximum temperature of 240 ° C. and a maximum pressure of 0.5 MPa for 10 minutes. Except that, an entangled yarn (3) / polyamide 6 molded body was obtained in the same manner.

[Example 6]
As the fiber A, two polyester fibers (manufactured by Teijin Fibers; P900M, 1100 dtex) are aligned in a non-twisted state and then twisted 64 times / m in the Z direction. Technora (registered trademark), manufactured by Teijin Techno Products; T240, 440 dtex, tensile strength = 24.5 cN / dtex, tensile breaking strain = 4.5%, 200 ° C. × 10 minutes dry heat shrinkage = 0%) in the Z direction Using 137 times / m of the lower twist, these were combined one by one and twisted 56 times / m in the S direction to obtain an entangled yarn (4). Thereafter, the entangled yarn (4) / volume fiber content = 33% in the same manner as in Example 2 except that the winding pitch of the entangled yarn (4) to the aluminum flat plate was 1.2 mm. A polyamide 6-integrated sheet was obtained and molded in a mold in the same manner as in Example 2 to obtain an entangled yarn (4) / polyamide 6 molded body.

[Example 7]
Polyester fiber (manufactured by Teijin Fibers; P900M, 1100 dtex, tensile strength = 8.1 cN / dtex, tensile breaking strain = 13.5%, 200 ° C. × 10 minutes dry heat shrinkage = 19.2%) is used as the fiber A. As fiber B, aramid fiber (Technola (registered trademark), manufactured by Teijin Techno Products; T240, 1100 dtex, tensile strength = 24.5 cN / dtex, tensile breaking strain = 4.5%, 200 ° C. × 10 minutes, dry heat shrinkage = 0 %), Using a rotary interlace nozzle that sprays compressed air intermittently by aligning both, nozzle rotating body circumference 30.9cm, nozzle diameter 4.5mm, nozzle hole number 4, nozzle rotating body circumference speed 600 meters / min, pressure pressure 5 kg / cm ^2, overfeed of 5%, and interlacing conjugated processed in yarn speed 600 meters / min, To obtain a doubling (5). Thereafter, an entangled yarn (5) / polypropylene integrated sheet having a volume fiber content rate of 33% was obtained in the same manner as in Example 1, and this was entangled in a mold as in Example 1. A thread (5) / polypropylene molded body was obtained.

[Example 8]
Polyester fiber (made by Teijin Fibers; P900M, 1100 dtex, tensile strength = 8.1 cN / dtex, tensile breaking strain = 13.5%, 200 ° C. × 10 minutes dry heat shrinkage = 19.2%) as the fiber A in the Z direction Two pieces having a twist of 87 times / m were prepared, and they were twisted 62 times / m in the S direction to obtain a polyester fiber twisted cord (6). Next, 100 g of an aluminum flat plate with a predetermined amount of polyamide 6 film (made by Unitika; emblem ON film, standard grade, thickness 25 μm) in a state where the polyester twisted cord (6) and the entangled yarn (1) are juxtaposed. Was wound at a pitch of 1 mm under the tension of 1 mm. Thereafter, a polyester twisted cord (6) + entangled yarn (1) / polyamide 6 integral sheet having a volume fiber content of 33% was obtained in the same manner as in Example 2, and this was molded in a mold as in Example 2. Thus, a polyester twisted yarn cord (6) + entangled yarn (1) / polyamide 6 molded body was obtained.

[Comparative Example 1]
A polyester fiber twisted cord (6) / polypropylene integral sheet having a volume fiber content of 33% was obtained in the same manner as in Example 1 except that the polyester twisted cord (6) was used instead of the entangled yarn (1). This was molded in a mold in the same manner as in Example 1 to obtain a polyester fiber twisted cord (6) / polypropylene molded body.

[Comparative Example 2]
In Comparative Example 1, a polyamide 6 film (manufactured by Unitika; emblem ON film, standard grade, thickness 25 μm) was used as the thermoplastic resin matrix, and the hot press conditions were heated at a maximum temperature of 240 ° C. and a maximum pressure of 0.5 MPa for 10 minutes. A polyester twisted cord (6) / polyamide 6 molded body was obtained in the same manner except that the pressure was applied.

[Comparative Example 3]
Without using fiber A, carbon fiber as fiber B (manufactured by Toho Tenax; HTS40 3K, 2000 dtex, tensile strength = 24 cN / dtex, tensile breaking strain = 1.9%, 200 ° C. × 10 minutes, dry heat shrinkage = 0 %) Were prepared by twisting 62 times / m in the Z direction and 45 times / m in the S direction were twisted to obtain a carbon fiber twisted cord (7). Then, by obtaining the carbon fiber twisted yarn cord (7) / polyamide 6 integral sheet with volume fiber content = 33% by the same method as in Example 2, and molding this in the mold as in Example 1, A carbon fiber twisted cord (7) / polyamide 6 molded body was obtained.

[Comparative Example 4]
Without using fiber A, aramid fiber (Technola (registered trademark), manufactured by Teijin Techno Products; T240, 1100 dtex, tensile strength = 24.5 cN / dtex, tensile breaking strain = 4.5%, 200 ° C. × as fiber B Prepare two yarns with 87 min / m twist in the Z direction for 10 minutes and 10% dry heat shrinkage, and twist them 62 times / m in the S direction for aramid fiber twisted yarn cord ( 8) was obtained. Thereafter, an aramid fiber twisted yarn cord (8) / polyamide 6 integral sheet having a volume fiber content of 33% was obtained in the same manner as in Example 2, and this was molded in a mold in the same manner as in Example 1. An aramid fiber twisted cord (8) / polyamide 6 molded product was obtained.

[Comparative Example 5]
As the fiber A, a polyester fiber (manufactured by Teijin Fibers; P900M, 1100 dtex) having a twist of 87 times / m in the Z direction is used. T240, 1100 dtex, tensile strength = 24.5 cN / dtex, tensile breaking strain = 4.5%, 200 ° C. × 10 minutes dry heat shrinkage = 0%) are aligned in an untwisted state, and then aligned in the Z direction. Using the one twisted 62 times / m, these were combined one by one and twisted 50 times / m in the S direction to obtain an entangled yarn (9). Thereafter, an entangled yarn (9) / polyamide 6 integral sheet having a volume fiber content of 33% was obtained in the same manner as in Example 2, and this was molded in a mold in the same manner as in Example 1 to A composite yarn (9) / polyamide 6 molded body was obtained.

[Comparative Example 6]
Polyester fiber (manufactured by Teijin Fibers; P900M, 1100 dtex, tensile strength = 8.1 cN / dtex, tensile breaking strain = 13.5%, 200 ° C. × 10 minutes dry heat shrinkage = 19.2%) is used as the fiber A. As fiber B, aramid fiber (Technola (registered trademark), manufactured by Teijin Techno Products; T240, 1100 dtex, tensile strength = 24.5 cN / dtex, tensile breaking strain = 4.5%, 200 ° C. × 10 minutes, dry heat shrinkage = 0 These were each subjected to 87 times / m twisting in the Z direction. Next, after a predetermined amount of polyamide 6 film (manufactured by Unitika; emblem ON film, standard grade, thickness 25 μm) is attached to an aluminum flat plate, a single twisted yarn of fiber A and a single twisted yarn of fiber B are arranged in parallel. And wound at a pitch of 1 mm under a tension of 100 g. Thereafter, a parallel yarn (10) / polyamide 6 integral sheet of fiber A and fiber B having a volume fiber content of 33% is obtained in the same manner as in Example 2, and this is molded in a mold as in Example 2. Thus, a parallel thread (10) / polyamide 6 molded body of fiber A and fiber B was obtained.

[Comparative Example 7]
Polyester fiber (manufactured by Teijin Fibers; P900M, 1100 dtex, tensile strength = 8.1 cN / dtex, tensile breaking strain = 13.5%, 200 ° C. × 10 minutes dry heat shrinkage = 19.2%) is used as the fiber A. As fiber B, aramid fiber (Technola (registered trademark), manufactured by Teijin Techno Products; T240, 1100 dtex, tensile strength = 24.5 cN / dtex, tensile breaking strain = 4.5%, 200 ° C. × 10 minutes, dry heat shrinkage = 0 %)) In a state in which these are arranged in parallel without twisting, a polyamide 6 film (manufactured by Unitika; emblem ON film, standard grade, thickness 25 μm), a 1 mm pitch under a tension of 100 g on a flat plate made of aluminum. Wrapped with. Thereafter, as in Example 2, a parallel yarn (11) / polyamide 6 integral sheet of fiber A and fiber B with a volume fiber content = 33% is obtained, and this is molded in a mold as in Example 2. Thus, a parallel yarn (11) / polyamide 6 molded body of fiber A and fiber B was obtained.

(Comparison of results)
As shown in Tables 1 and 2, when the reinforcing fiber in the composite material is composed of only the fiber A as in Comparative Examples 1 and 2, the specific absorption energy is relatively high, but the dimensional change is large and the moldability is high. On the contrary, when the reinforcing fiber is composed of only the fiber B as in Comparative Examples 3 and 4, the dimensional stability is good and the moldability is excellent, but the specific absorption energy is low and the impact is low. It does not seem to function as an absorbent material. About the ratio of the fiber A and the fiber B, when the ratio of the fiber B is high like the comparative example 5, specific energy absorption is low and it is inadequate as an energy absorber. Moreover, when the fiber A and the fiber B are not entangled like the comparative examples 6 and 7, thermal dimensional stability is inadequate. From the above, it can be said that the example is a material which has a better balance between dimensional stability and energy absorption than the comparative example, and is excellent in terms of manufacturing and performance.

[Example 9]
Cut carbon fiber strands (Toho Tenax; HTS40, tensile elastic modulus = 240 Gpa, specific elasticity 13.9) to 20 mm, and spread 23.5 g of the cut strands on a 400 mm x 400 mm aluminum plate to a uniform thickness. did. On this, 5 polyamide 6 films (made by Unitika, emblem film) are placed and heated and pressurized for 10 minutes at a maximum temperature of 260 ° C. and a maximum pressure of 2.0 MPa using a hot press machine (manufactured by Meiki Seisakusho, MHPC). Thus, a carbon fiber isotropic material partially impregnated with polyamide 6 resin was obtained. Three pieces of this partially impregnated isotropic material are stacked, cut out to an appropriate size, and then heated and pressed for 20 minutes at a maximum temperature of 260 ° C. and a maximum pressure of 3.0 MPa using a 350 mm × 350 mm mold to impregnate the resin. A carbon fiber random material having a thickness of 0.5 mm and a volume fiber content of 40% with a degree increased to 99% was obtained.
Next, the entangled yarn (1) / polyamide 6 molded body of Example 2 was sanded with the two carbon fiber random materials described above, and again a maximum temperature of 260 ° C. and a maximum pressure of 2. using a 350 mm × 350 mm mold. By heating and pressurizing at 0 MPa for 10 minutes, a sandwich material was obtained in which the carbon fiber random material was a skin material and the molded body of Example 2 was a core material.

[Example 10]
A carbon fiber spread yarn cloth (manufactured by Sakai Obex, weight per unit of 80 g / m ² ) and polyamide 6 film (manufactured by Unitika, “Emblem ON Film”, 25 μm) are cut out to an appropriate size and then placed in a 350 mm × 350 mm mold. A carbon fiber cloth having a thickness of 0.5 mm and a volume fiber content of 40% with a resin impregnation level increased to 99% by heating and pressing at a maximum temperature of 260 ° C. and a maximum pressure of 3.0 MPa for 20 minutes. I got the material.
Next, using this carbon fiber cloth material as a skin material, a sandwich material was obtained in the same manner as in Example 9, using the carbon fiber cloth material as a skin material and the molded article of Example 2 as a core material.

[Comparative Example 8]
A sandwich material was obtained in the same manner as in Example 10 except that the skin material was the carbon fiber cloth material of Example 10 and the core material was the composite material of Comparative Example 2.

[Comparative Example 9]
The molded body of Example 2 itself was used as the test body of Comparative Example 8, and only the moldability was evaluated. The value of Example 2 was used for the specific energy absorption.

[Comparative Example 10]
A carbon fiber spread yarn cloth (manufactured by Sakai Obex, weight per unit of 80 g / m ² ) and polyamide 6 film (manufactured by Unitika, “Emblem ON Film”, 25 μm) are cut out to an appropriate size and then placed in a 350 mm × 350 mm mold. A carbon fiber cloth having a thickness of 2.5 mm and a volume fiber content of 40% with a resin impregnation level increased to 99% by heating and pressing at a maximum temperature of 260 ° C. and a maximum pressure of 3.0 MPa for 20 minutes. I got the material. In Comparative Example 9, only this carbon fiber cloth material was used as a test body.

(Comparison of results)
Although the evaluation results are shown in Table 3, Comparative Examples 8 and 9 have high energy absorption performance, but have poor moldability, and such materials cannot actually provide a good product. In addition, since Comparative Example 10 does not contain any component of fiber A, there are few wrinkles during heating of the molding substrate, but the energy absorption performance is poor and the intended function is not expressed. On the other hand, the examples have a better balance between energy absorption performance and formability than the comparative examples, and can be said to be practical materials.

Claims (3)

  A fiber composite material including fiber A and fiber B and a thermoplastic resin, wherein fiber A is an organic fiber having a melting point of 200 ° C. or higher and a tensile breaking strain of 5% or more, and fiber B is 200 ° C. × 10 minutes. A fiber composite material having a dry heat shrinkage rate of 1% or less, 10 to 100 parts by volume of fiber B with respect to 100 parts by volume of fiber A, and an intertwined yarn of fibers A and B in the composite material.   The fiber composite material according to claim 1, wherein the form of the fiber A is a twisted yarn cord or a woven fabric or a knitted fabric composed of a twisted yarn cord. A high-rigidity material comprising a fiber composite material according to any one of claims 1 and 2 as a core material and comprising a reinforcing fiber having a specific elasticity (E) defined by the following formula (1) of 2.5 or more and a resin. Sandwich material for skin material.
E = M / D / 9.8 (1)
(E is specific elasticity, M is the elastic modulus (MPa) of the fiber, and D is the density (g / cm ³ ) of the fiber.)