JP2022078893A - Composite molding and method for manufacturing the same, non-woven fabric for composite molding, and fiber for composite molding matrix - Google Patents

Abstract

To provide a composite molding which is more excellent in mechanical physical properties.SOLUTION: A composite molding contains a reinforcement fiber, and a thermoplastic resin containing two or more main different components having a melting difference or a Vicat softening temperature difference as a matrix, in which the matrix is a composite fiber having the number of three or more sections, and is formed by melting a composite fiber where each of the sections is exposed to the surface of the fiber and has high splittability, the thermoplastic resin having a higher melting point or Vicat softening temperature forms a sea component, and the thermoplastic resin having a lower melting point or Vicat softening point forms an island component.SELECTED DRAWING: None

Description

The present disclosure describes a composite molded body containing two or more types of thermoplastic resins having different main components as a matrix and a method for producing the same, and a group for a composite molded body containing two or more types of composite fibers made of thermoplastic resins as matrix forming fibers. The present invention relates to a material and a fiber for a composite molded body matrix.

A fiber-reinforced composite molded body (FRP, hereinafter simply referred to as "composite molded body") is a material whose strength is improved by allowing fibers to exist in a matrix resin (also referred to as a base resin), and is excellent in its superiority. It is used in various fields due to its light weight, high strength and corrosion resistance. Glass fibers, carbon fibers, aramid fibers and the like are used as the reinforcing fibers constituting the composite molded body, and thermosetting resins are widely used as the matrix resin. However, the thermosetting resin has a drawback that the molding time is rather long and the recyclability is poor. Therefore, especially when recyclability is taken into consideration, a thermoplastic resin tends to be used as a matrix resin.

When using a thermoplastic resin as a matrix resin, a composite molded body is obtained by a method in which a reinforcing fiber and a synthetic fiber made of a resin to be a matrix resin are mixed to prepare a non-woven fabric or a web, and the synthetic fiber is melted and solidified. A method has been proposed (Patent Documents 1 to 9). Further, it has been proposed to use a core-sheath type composite fiber or a side-by-side type composite fiber composed of a high melting point polymer component and a low melting point polymer component as the synthetic fiber (Patent Documents 1, 3 to 5, 7). ..

Japanese Unexamined Patent Publication No. 2011-190549 Japanese Patent No. 379960 Japanese Unexamined Patent Publication No. 2013-204187 Japanese Unexamined Patent Publication No. 2018-130939 Japanese Patent No. 6555777 Japanese Patent No. 5855869 Jikkenhei 3-120592 Gazette Japanese Unexamined Patent Publication No. 2007-46197 Japanese Patent No. 6550644

It is an object of the present disclosure to provide a composite molded body having better mechanical properties and to provide a base material for a composite molded body that enables the production of such a composite molded body. Further, it is an object of the present disclosure to provide a fiber for a composite molded body matrix, which is suitable for providing a composite molded body having better mechanical properties.

The present disclosure is a composite molded body containing a reinforcing fiber and a thermoplastic resin having two or more kinds of different main components as a matrix.
The matrix is formed by melting at least one section of a composite fiber in which the number of sections is 3 or more and each section is exposed on the fiber surface.
In at least one cross-sectional view of the composite molding, the matrix comprises a sea component and an island component.
When both the thermoplastic resin contained in the sea component and the thermoplastic resin contained in the island component are crystalline resins, the melting point measured based on JIS K 7121 of the thermoplastic resin contained in the sea component is , At least one of the thermoplastic resin contained in the sea component and the thermoplastic resin having a melting point higher than the melting point measured based on JIS K 7121 of the thermoplastic resin contained in the island component. When is an amorphous resin, the Vicat softening temperature measured based on the JIS K 7206 B50 method of the thermoplastic resin contained in the sea component is the JIS K 7206 B50 method of the thermoplastic resin contained in the island component. Higher than the Vicat softening temperature measured based on,
Provided is a composite molded body.

Further, in the present disclosure, a reinforcing fiber and a fiber for a composite molded body matrix in which two or more kinds of thermoplastic resins having different main components, the number of sections is 3 or more, and each section is exposed on the fiber surface are described. Including, a substrate for composite molding,
The fiber for the composite molded body matrix is an easily split fiber composite fiber, and is
When the two or more types of thermoplastic resins are all crystalline resins, the melting point difference measured based on JIS K 7121 in the combination of the two types of thermoplastic resins is 25 ° C. or higher and 150 ° C. or lower.
When at least one of the two or more types of thermoplastic resin is an amorphous resin, the Vicat softening temperature difference measured based on the JIS K 7206 B50 method in the combination of the two types of thermoplastic resin is 1 ° C. or more. Below 120 ° C,
Provided is a composite molded base material in which the expression ratio of ultrafine fibers derived from the composite molded matrix fibers on the surface of the composite molded base material exceeds 20%.
[Measuring method of expression rate of ultrafine fibers]
(1) The surface of the base material is observed with an electron microscope at a magnification of 150 to 200 times, and the enlarged surface is photographed.
(2) Among the fibers present in the photographed image, the number of fibers for the composite molded body matrix having a length of 200 μm or more and the number of fibers derived from the fibers for the composite molded body matrix are counted. Among them, fibers having a fiber length of 150 μm or more and a fiber diameter smaller than 1/2 are defined as ultrafine fibers.
(3) The expression ratio of ultrafine fibers is determined by the following formula.
Expression rate of ultrafine fibers (%) = (number of ultrafine fibers / number of fibers for composite molded matrix) × 100

Further, in the present disclosure, a reinforcing fiber and a fiber for a composite molded body matrix, which is composed of two or more kinds of thermoplastic resins having different main components, has three or more sections, and each section is exposed on the fiber surface. Including,
When the two or more types of thermoplastic resins are all crystalline resins, the melting point difference measured based on JIS K 7121 in the combination of the two types of thermoplastic resins is 25 ° C. or higher and 150 ° C. or lower.
When at least one of the two or more types of thermoplastic resin is an amorphous resin, the Vicat softening temperature difference measured based on the JIS K 7206 B50 method in the combination of the two types of thermoplastic resin is 1 ° C. or more. Below 120 ° C,
Preparing a composite molded base material in which the expression ratio of ultrafine fibers on the surface of the composite molded base material derived from the composite molded body matrix fibers exceeds 20%, and heating the composite molded base material. Including
When the base material for a composite molded body is heated, the resin having the lowest melting point or Vicat softening temperature among the two or more types of thermoplastic resins is melted and
When the two or more types of thermoplastic resins constituting the composite molded fiber for the matrix are all crystalline resins, when the melting point of the thermoplastic resin component having the highest melting point is Tm ° C. (Tm-30). The temperature should be ℃ or higher (Tm + 50) ℃ or lower.
When at least one of the two or more types of thermoplastic resins constituting the composite molded body matrix fiber is an amorphous resin, when the Vicat softening temperature of the thermoplastic resin having the highest Vicat softening temperature is VST ° C. , Performed at a temperature of (VST + 20) ° C or higher (VST + 150) ° C or lower,
Including further pressurizing when heating the base material for a composite molded body,
The heating and the pressurization are carried out so that the density of the composite molded product is 90 % or more of the true density.
A method for manufacturing a composite molded body is provided.
[Measuring method of expression rate of ultrafine fibers]
(1) The surface of the base material is observed with an electron microscope at a magnification of 150 to 200 times, and the enlarged surface is photographed.
(2) Among the fibers present in the photographed image, the number of fibers for the composite molded body matrix having a length of 200 μm or more and the number of fibers derived from the fibers for the composite molded body matrix are counted. Among them, fibers having a fiber length of 150 μm or more and a fiber diameter smaller than 1/2 are defined as ultrafine fibers.
(3) The expression ratio of ultrafine fibers is determined by the following formula.
Expression rate of ultrafine fibers (%) = (number of ultrafine fibers / number of fibers for composite molded matrix) × 100

Furthermore, the present disclosure is an easily split fiber composite fiber having two or more types of thermoplastic resins having different main components, having three or more sections, and each section of the composite fiber is exposed on the fiber surface. And
When the two or more types of thermoplastic resins are all crystalline resins, the melting point difference measured based on JIS K 7121 in the combination of the two types of thermoplastic resins is 25 ° C. or higher and 150 ° C. or lower.
When at least one of the two or more types of thermoplastic resin is an amorphous resin, the Vicat softening temperature difference measured based on the JIS K 7206 B50 method in the combination of the two types of thermoplastic resin is 1 ° C. or more. A fiber for a composite molded body matrix having a temperature of 120 ° C. or lower is provided.

The composite molded body of the present disclosure is a composite fiber containing two or more types of thermoplastic resins whose matrix has a difference in melting point and different main components, and the composite fiber is at least a part of two or more types of thermoplastic resin components. Is formed by melting composite fibers and / or single fibers in a state of being split into single fibers (ultrafine fibers), and the two or more types of thermoplastic resins form sea components and island components as prescribed. It is characterized by being. This composite molded product has excellent mechanical properties and is suitable for use in various applications.

Each of (a) to (h) is a cross section showing an example of the composite form of the fiber for the composite molded body matrix of the present embodiment. It is an electron micrograph with a magnification of 600 times which shows the cross section of the composite molded body obtained in Example 1. FIG. It is an electron micrograph with a magnification of 600 times which shows the cross section of the composite molded body obtained in Example 2. FIG. It is an electron micrograph with a magnification of 600 times which shows the cross section of the composite molded body obtained in Example 3. FIG. It is an electron micrograph with a magnification of 150 times which shows the surface of the composite molded body base material used in Examples 1 to 3. It is an electron micrograph with a magnification of 500 times which shows the cross section of the composite molded body base material used in Examples 1 to 3. 6 is a graph showing a bending load-bending deflection curve for obtaining the impact energy of the composite molded product obtained in Example 1, Comparative Example 1, and Comparative Example 4. It is a graph which shows the bending load-bending deflection curve for obtaining the impact energy of the composite molded body obtained in Example 2, Comparative Example 2, and Comparative Example 5. It is a graph which shows the bending load-bending deflection curve for obtaining the impact energy of the composite compact obtained in Example 3, Comparative Example 3, and Comparative Example 6.

(Reason for reaching this embodiment)
In many of the patent documents mentioned above, in the examples, core-sheath type composite fibers prepared by using two or more kinds of thermoplastic resins having a melting point difference or a glass transition temperature difference are mixed with reinforcing fibers to form a non-woven fabric or the like. It is proposed to produce a composite molded body by subjecting the fiber sheet of the above to heat and pressure treatment. However, the composite molded product, particularly the composite molded product having a thermoplastic resin as a matrix, is required to have further improved mechanical properties. Further, the techniques disclosed in these patent documents are characterized by either the composition of the thermoplastic resin itself as a matrix, the composition of reinforcing fibers, or the composition of fiber sheets, and these patent documents are composite forms of composite fibers. Etc. do not teach the effect on the composite molded body.

The present inventors have investigated the possibility that the composite form of the composite fiber forming the matrix may affect the mechanical properties of the composite molded body, and produced composite fibers of various composite forms for various combinations of resins. , The mechanical properties of the composite molded body were evaluated. As a result, composite fibers having two or more types of thermoplastic resins having a melting point difference or a Vicat softening temperature difference, having three or more sections, and having each section exposed on the fiber surface are formed between the sections. It has been found that when a resin that easily causes peeling is selected and configured as an easily split fiber composite fiber, the mechanical properties of the composite molded body produced by using the composite fiber are improved.
Hereinafter, the fibers for the composite molded body matrix, the nonwoven fabric for the composite molded body, and the composite molded body of the present embodiment will be described together with these manufacturing methods.

(Embodiment 1: Fiber for Composite Molded Matrix and Method for Manufacturing thereof)
[Structure of fiber for composite molded matrix]
The composite molded body matrix fiber of the present embodiment (hereinafter, “matrix fiber”) is a composite fiber having three or more sections and made of two or more kinds of thermoplastic resins having different melting points and different main components. Each section of the composite fiber has a composite morphology exposed on the fiber surface and has easy split fiber property (hereinafter, also referred to as "easy split fiber composite fiber"). An example of this composite form is shown in FIG. In each of the illustrated forms, each section is composed of one of the two types of thermoplastic resin (A or B), and the adjacent sections are composed of different thermoplastic resins. In the illustrated form, adjacent sections are made of different thermoplastic resins, or a section having a plurality of streaks, petals, etc. extending radially from the center and the streaks or petals are separated from each other. It consists of a section to fill.

1 (a) to 1 (h) show cross sections perpendicular to the length direction of the fiber. The composite morphology shown in FIGS. 1 (a) and 1 (g) has wedge-shaped sections arranged in a chrysanthemum shape, and FIG. 1 (h) shows the composite morphology shown in FIGS. 1 (a) and 1 (g). The central part is hollow. The composite form shown in FIG. 1 (b) has sections arranged in a striped pattern. In the composite form shown in FIGS. 1 (c) and 1 (d), one section has a plurality of rod-shaped portions radially extending from the center, and another section is arranged between the rod-shaped portions. .. The composite form shown in FIGS. 1 (e) and 1 (f) can be said to be a modification of FIG. 1 (c), in which a section having a plurality of radially extending portions and another section are arranged between the portions. Is.

Composite fibers in such a composite form are used, for example, in artificial leather and wipers, as they may provide ultrafine fibers consisting of one or more sections. The mechanical properties of the composite molded product can be improved by configuring the composite molded product so as to easily generate ultrafine fibers. When the composite fiber having such a composite form is split, it takes the dispersion form of any one of (1) to (3): (1) becomes an ultrafine single fiber and is dispersed, and (2) the ultrafine single fiber is bundled. When the matrix is formed by thermal molding by taking at least one form of (1) to (3), which is dispersed in the form of (3) partially split fibers are generated and dispersed, the book It is possible to obtain a composite molded body in which a matrix having a sea-island structure peculiar to the embodiment is formed. When some of the above forms are mixed, or when at least one form of (1) to (3) and (4) a form dispersed without splitting are mixed, the melting point or the Vicat softening temperature is low. The island component formed by the resin is preferable because the shape and size (maximum transfer length) are random and a large number of island components tend to be formed.

The matrix fiber as an easily split fiber composite fiber can be obtained by using two or more kinds of resins having a melting point difference constituting the matrix fiber as a thermoplastic resin having no compatibility with each other or having a low compatibility with each other. Can be done. The combination of thermoplastic resins having no compatibility is preferably a combination of resins having different main components, that is, a combination in which the main components are not the same resin. Here, the "main component" of the resin means that the total number of monomers constituting the resin exceeds 50%. Therefore, the combination of resins having different main components may be, for example, a combination of two or more kinds of resins selected from different systems selected from systems such as polyolefin-based, polyester-based, and polyamide-based, and each system may be used. Resin may constitute, for example, the A component and the B component shown in FIG. Even when each resin is selected from the same system, easy split fiber may be obtained by adjusting the fiber production conditions. When each resin is selected from the same system, a division accelerator can be added to any one or a plurality of resins to form a combination of resins having no compatibility. Further, even if the system is different, a division accelerator may be added. As the division accelerator, for example, a silicone-based compound, an unsaturated carboxylic acid-based compound, a (meth) acrylic acid-based compound, or the like may be added. Hereinafter, the combination of resins will be described in detail.

The resins constituting the matrix fibers are polyethylene resins such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene succinate and their copolymers; polypropylene and polyethylene (high density polyethylene). , Low-density polyethylene, linear low-density polyethylene, etc.), polybutene-1, propylene copolymer containing propylene as a main component (including propylene-ethylene copolymer, propylene-butene-1-ethylene copolymer) ), Polyethylene-acrylic acid copolymers, and polyolefin resins such as ethylene-vinyl acetate copolymers; polyamide resins such as nylon 6, nylon 12 and nylon 66; acrylic resins; polycarbonate, polyacetal, polystyrene, cyclic polyolefins. Examples of engineering plastics such as, and their copolymers and the like can be exemplified. The matrix fiber is composed of two or more thermoplastic resins having a melting point difference or a Vicat softening temperature difference selected from these.

The difference in melting point of the resin is used as one of the indexes for selecting the resin when all the resins constituting the matrix fibers are crystalline resins. In the fiber composed of two or more kinds of crystalline resins, the difference in melting point of the fibers between the resins may be 25 ° C. or higher, particularly 30 ° C. or higher, in any combination of the two resins arbitrarily selected. In particular, the temperature may be 40 ° C. or higher. Further, the upper limit of the fiber melting point difference may be, for example, 150 ° C., particularly 120 ° C., and more particularly 100 ° C.

When at least one of the resins constituting the matrix fiber is an amorphous resin, the Vicat softening temperature difference is used instead of the melting point of the crystalline resin. In the combination of two resins (for example, in the case of three kinds of resins A, B, C, the combination of AB, the combination of AC, and the combination of BC), the bicut softening temperature difference is It may be 1 ° C. or higher, preferably 10 ° C. or higher, particularly 30 ° C. or higher, and more particularly 50 ° C. or higher. Further, the upper limit of the Vicat softening temperature difference may be, for example, 120 ° C., particularly 100 ° C., and more particularly 80 ° C.

The method for measuring the melting point of the fiber and the method for measuring the Vicat softening temperature are as follows.
[Measuring method of fiber melting point]
The resin is fiberized and differential scanning calorimetry (DSC) is performed. The melting point of each component is a differential scanning calorimeter (manufactured by Seiko Instruments Co., Ltd.), and the amount of fiber (sample amount) is 3.0 mg. The fiber was melted by raising the temperature from normal temperature to 300 ° C. at a heating speed of 10 ° C./min, and the fiber was obtained from the obtained heat of melting curve.
[Measurement method of Vicat softening temperature]
Measure by the method described in JIS K 7206 B50 method. The test piece is made of a single resin and has a length of 10 mm and a width of 10 mm.

The combination of resins selected from the homologous resin group includes, for example, one or more selected from polyethylene terephthalate / polyester copolymer, polypropylene / polyethylene (high density polyethylene, low density polyethylene and linear low density polyethylene). Polyethylene), polypropylene / polybutene-1, nylon 6 / nylon 66, polyethylene terephthalate / polybutylene terephthalate, polyethylene terephthalate / polytrimethylene terephthalate, high impact polystyrene / syndiotactic polystyrene, etc. Combination).

Since the homologous resins have similar chemical structures, they have relatively high compatibility with each other, and therefore, it may not be possible to provide the desired composite fiber having a large split fiber ratio as it is. Therefore, in the present embodiment, when a combination of resins of the same family is used, for example, a division accelerator may be added to either of the resins. The types of the split accelerator are as described above. When a similar resin is used, it is possible to advantageously recycle the used composite molded product. Combinations of homologous resins have a similar effect on the properties of the composite molded body and are therefore conveniently used when certain physical properties are of particular importance.

Examples of resin combinations selected from different resin groups include polyamide / polyolefin. In this combination, the polyamide resin is Polyamide 6, Polyamide 66, Polyamide 610, Polyamide 612, Polyamide 614, Polyamide 11, Polyamide 12, Polyamide 6T, Polyamide 6I, Polyamide 9T, Polyamide M5T, Polyamide 1010, Polyamide 1012, Polyamide 10T, Polyamide MXD6, Polyamide 6T / 66, Polyamide 6T / 6I, Polyamide 6T / 6I / 66, and Polyamide 6T / 2M-5T may be selected, and the olefin resin is polypropylene, high density polyethylene, low density polyethylene, straight chain. The state may be selected from low-density polyethylene, polymethylpentene, ethylene-propylene copolymer, propylene-ethylene-1-butene ternary copolymer and the like, and modified products thereof. The combination of resins selected from the different resin groups may be polystyrene resin / polyester resin, in which case the polystyrene may be homopolystyrene (GPPS), high impact polystyrene (HIPS), isotactic polystyrene ( IPS) and may be selected from atactic polystyrene (APS), acrylic nitrile butadiene styrene (ABS) and the like, and the polyester resin is polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and poly. It may be selected from butylene naphthalate and the like. In the case of polystyrene / polycarbonate, for example, polystyrene may be selected from GPPS, HIPS, IPS, APS, ABS and the like.

More specifically, the combinations of different resins include nylon 6 / polypropylene, nylon 66 / polypropylene, nylon 6 / polyethylene terephthalate, nylon 6 / polyacetal, polyethylene terephthalate / polyacetal, syndiotactic polystyrene / polyacetal, etc. (all). A combination of high melting point resin / low melting point resin). In the combination of resins selected from different resin groups, the resins do not have compatibility with each other, so that the fiber splitting ratio of the fibers spun in the above composite form is increased without using a splitting accelerator or the like. Although it is easy to do, a more stable split fiber ratio can be obtained by adding a splitting accelerator. By selecting a resin from a group of resins having different systems, it is possible to obtain characteristics according to the difference in the resin system in the obtained composite molded body, and it is possible to make the composite molded body exhibit various characteristics. .. If necessary, a dispersion accelerator or the like may be used for one or more resins even when different resins are selected.

Of the above combinations, the nylon 6 / polypropylene combination is preferable from the viewpoint of fiber spinnability. Further, at the time of matrix formation, polypropylene melts and flows first, and then nylon 6 melts, so that the thermoplastic resin easily spreads over the entire voids between the reinforcing fibers, especially when the reinforcing fibers are carbon fibers. It is considered to be. As a result, it is considered that a composite molded product having higher density and improved mechanical properties can be obtained.

When selecting a thermoplastic resin, fluidity under heating can also be taken into consideration. If there is a difference in the fluidity of the thermoplastic resin, it is considered that the highly fluid resin flows first and then the less fluid resin flows during the heating and pressurizing treatments in the production of the composite molded body. .. By shifting the flow timings of two or more types of resins, the voids between the reinforcing fibers can be further filled (that is, the density of the composite molded body can be increased), so that the resins having different fluidities as necessary can be obtained. May be selected to form the matrix fibers.

When the matrix fiber is composed of two types of thermoplastic resins, the composite ratio (volume ratio, high melting point / low melting point) of the high melting point resin and the low melting point resin may be, for example, 20/80 to 50/50. In particular, it may be 25/75 to 45/55, and more particularly 28/72 to 40/60. When the composite ratio is within this range, the matrix fibers in the composite form can be satisfactorily spun. Further, in particular, when the combination of high melting point / low melting point is nylon 6 / polypropylene, the composite ratio within the above range is preferably selected from the viewpoint of weight reduction and cost of the matrix fiber and the composite molded body. If the proportion of nylon 6 increases, the physical properties of the matrix fibers and the composite molded body may deteriorate due to the hygroscopicity of nylon, and in that respect as well, the composite ratio in the above range is preferably selected.

The number of sections in the matrix fiber may be 3 or more, for example, 4 or more and 32 or less, particularly 6 or more and 24 or less, and more particularly 8 or more and 20 or less. When the number of sections is within the above range, the ultrafine fibers that are expressed are finer, the number of fibers is larger, and the fibers tend to be easier to split when the composite molded body is formed, so that there are many island components. Will be formed.

The fineness of the matrix fiber may be, for example, 0.5 dtex to 7.8 dtex, particularly 0.5 dtex to 4.8 dtex, and more particularly 1.1 dtex to 2.0 dtex. When the fineness of the matrix fibers is within the above range, it tends to be easy to produce a non-woven fabric for a composite molded body together with the reinforcing fibers. Further, if the fineness of the matrix fiber is too small, the spinnability is poor and the productivity is lowered, and if the fineness of the matrix fiber is too large, voids may be generated in the composite molded body.

The matrix fiber has a fineness such that each section can be a fiber having a fineness of 0.6 dtex or less, preferably a fineness of 0.5 dtex or less, assuming that each section is separated into one fiber. You may be. Assuming that each section becomes a single fiber, the lower limit of the fineness of the fiber that can be composed of each section is, for example, 0.01dtex, in particular 0.006dtex. If one section gives a fiber with a fineness within the above range,
Therefore, the fineness of the matrix fiber may be appropriately selected in consideration of the number of sections.

The matrix fiber may be a continuous fiber or a discontinuous fiber, and may be appropriately selected depending on the form of the base material produced by using the continuous fiber. For example, when a card web is produced to produce a nonwoven fabric, the matrix fiber is preferably a discontinuous fiber, and the fiber length thereof is preferably 20 mm or more and 100 mm or less, more preferably 26 mm or more and 75 mm or less, and particularly preferably 30 mm or more and 65. It is as follows. When a wet papermaking web is produced to produce a nonwoven fabric, the matrix fibers are preferably discontinuous fibers, and the fiber length thereof is preferably 2 mm or more and 20 mm or less, more preferably 2 mm or more and 15 mm or less, and particularly preferably 3 mm or more and 10 mm or less. Is. When a non-woven fabric is produced by producing an air-laid web, the matrix fibers are preferably discontinuous fibers, and the fiber length thereof is preferably 2 mm or more and 100 mm or less, more preferably 5 mm or more and 90 mm or less, and particularly preferably 5 mm or more and 85 mm or less. Most preferably, it is 8 mm or more and 80 mm or less. When the sheet is formed by air transportation, it is preferably 3 mm or more and 25 mm or less, and more preferably 5 mm or more and 20 mm or less.

[Manufacturing method of fiber for composite molded matrix]
The matrix fiber may be produced by a method of composite spinning using a conventional melt spinning machine using an appropriate composite spinning nozzle depending on the composite form. The spinning temperature (nozzle temperature) is selected according to the resin used.

Specifically, a compound nozzle for obtaining a predetermined fiber cross section is attached to a melt spinning machine, and the spinning temperature is 200 ° C. or higher and 360 ° C. or lower so as to have a fiber cross section as shown in FIGS. 1 (a) to 1 (c), for example. Then, a plurality of resins can be extruded and melt-spun to obtain a spun filament (undrawn fiber bundle).

The fineness of the spun filament (undrawn fiber bundle) may be in the range of 1 dtex or more and 30 dtex or less. When the fineness of the spun filament is 1 dtex or more and 30 dtex or less, spinning becomes easier.
The fineness of the spun filament is preferably 2.0 dtex or more and 15 dtex or less, more preferably 2.5 dtex or more and 12 dtex or less, further preferably 3 dtex or more and 10 dtex or less, 4.0 dtex or more and 8.0 dtex or less. Is particularly preferable. The fineness range of these spun filaments is preferable in order to further improve the card-passability when producing a nonwoven fabric as a base material and the splitting property when forming a nonwoven fabric.

Next, the spun filament is drawn by using a known drawing treatment machine to obtain a drawn filament. The stretching treatment may be carried out by wet stretching or dry stretching depending on the type of resin used.

It is preferable that the draw ratio with the maximum draw ratio satisfies the above range and the draw ratio is 1.1 times or more and less than 8 times. By performing the stretching step at the stretching ratio, the unstretched fibers can be sufficiently stretched, and the obtained matrix fibers not only have sufficient single fiber strength as the fibers constituting the nonwoven fabric. , The influence of the fiber melting point due to the progress of crystal orientation can be suppressed. The draw ratio is preferably 1.1 times or more and 8 times or less, more preferably 1.5 times or more and less than 6 times, and particularly preferably 2 times or more and 5.5 times or less.

A predetermined amount of the fiber treatment agent is attached to the obtained drawn filament as needed, and mechanical crimping is given by a crimper (crimping device) as needed. The fiber treatment agent is attached, for example, to suppress the generation of static electricity generated during the production of the non-woven fabric and improve the card permeability, or it is easy to disperse the fibers in water or the like when the wet non-woven fabric is produced. Attached to make it.

The filament after the fiber treatment agent is applied (or the filament is not applied with the fiber treatment agent but is in a wet state) is dried at a temperature within the range of 80 ° C. or higher and 110 ° C. or lower for several seconds to about 30 minutes. Dry the fibers. The drying process may be omitted in some cases. The filament is then cut to the desired fiber length.

(Embodiment 2: Substrate for composite molded body and method for manufacturing the same)
Next, as the second embodiment, a base material for a composite molded body using the matrix fibers of the first embodiment and a method for producing the same will be described.

The base material of the present embodiment includes the reinforcing fiber and the matrix fiber of the first embodiment, and the reinforcing fiber and the matrix fiber exist in the base material in the form of continuous fiber or discontinuous fiber, respectively. The substrate is provided, for example, as a sheet-like material, a plate-like material, a composite yarn, or a three-dimensional structure formed into a predetermined shape. The sheet-like material may be, for example, papermaking, woven fabric, knitted material, net-like material, net, mat or non-woven fabric, or a combination thereof. Further, the sheet-like material may be in the form of a laminated body, and in that case, the forms of the sheets to be laminated may be the same and may be different from each other.

[Nonwoven fabric for composite molding]
The base material of the present embodiment may be a non-woven fabric for a composite molded body (hereinafter, may be simply referred to as “nonwoven fabric”), and in that case, the base material includes a reinforcing fiber and a matrix fiber of the first embodiment.
The reinforcing fiber is not particularly limited as long as it is generally used as a reinforcing fiber of a composite molded body, and may be a fiber having high strength such as a glass fiber, an aramid fiber, or a carbon fiber. When the strength of the fiber itself is high, the strength of the composite molded body can be increased, so that it is preferably used in the composite molded body used in applications where strength is important. In particular, carbon fiber is light and has excellent specific strength and specific elastic modulus as compared with glass fiber and aramid fiber, so that it is suitable for use as a reinforcing fiber of a composite molded body which is desired to be lightweight.

The fineness of the reinforcing fiber may be, for example, 0.1 dtex or more and 20 dtex or less, particularly 0.2 dtex or more and 10 dtex or less, and more particularly 0.3 dtex or more and 5 dtex or less. Alternatively, the fiber diameter of the reinforcing fiber may be, for example, 1 μm or more and 40 μm or less, particularly 2 μm or more and 20 μm or less, and more particularly 3 μm or more and 15 μm or less. When the reinforcing fiber is a carbon fiber, the preferable fiber diameter is 3 μm or more and 10 μm or less.

The longer the fiber length of the reinforcing fiber, the better the reinforcing effect is exhibited. Therefore, if the fiber length of the reinforcing fiber is too short (for example, if it is less than 1 mm), it is difficult to obtain a sufficient reinforcing effect. In particular, since fibers having a fiber length of less than 1 mm are in the form of powder, inconveniences such as the reinforcing fibers falling off may occur in the nonwoven fabric produced using the fibers.

The fiber length of the reinforcing fiber is appropriately selected depending on the form of the nonwoven fabric to be produced. For example, when a card web is produced to produce a nonwoven fabric, the fiber length of the reinforcing fiber is preferably 20 mm or more and 70 mm or less, and more preferably 25 mm or more and 52 mm or less. When a wet papermaking web is produced to produce a nonwoven fabric, the fiber length of the reinforcing fibers is preferably 3 mm or more and 25 mm or less, and more preferably 5 mm or more and 20 mm or less. When the air-laid web is produced to produce a nonwoven fabric, the fiber length of the reinforcing fiber is preferably 20 mm or more and 70 mm or less, and more preferably 25 mm or more and 52 mm or less when the carding machine is used in combination to form a sheet. When the sheet is formed by air transportation, it is preferably 3 mm or more and 25 mm or less, and more preferably 5 mm or more and 20 mm or less.

The reinforcing fibers may be mixed so that the ratio of the reinforcing fibers is, for example, 20% by volume or more and 60% by volume or less when the total volume of the fibers constituting the nonwoven fabric is 100%. The ratio of the reinforcing fibers may be particularly 25% by volume or more and 55% by volume or less. In particular, when the reinforcing fibers are carbon fibers, they may be mixed so that the ratio of the carbon fibers is, for example, 20% by volume or more and 50% by volume or less when the total volume of the fibers constituting the nonwoven fabric is 100%. .. The proportion of carbon fibers may be particularly 25% by volume or more and 40% by volume or less.

The basis weight of the nonwoven fabric may be, for example, 10 g / m ² or more and 12000 g / m ² or less, and particularly 500 g / m ² or more and 3600 g / m ² or less, depending on the thickness or the like of the composite molded product to be obtained.
The composite molded body may be provided, for example, as having a basis weight of 1000 g / m ² or more. When a plurality of nonwoven fabrics are laminated in order to obtain such a composite molded body, if the basis weight of the nonwoven fabric is small, it is necessary to laminate a large number of nonwoven fabrics, and the production of the composite laminate may be complicated. On the other hand, if the basis weight of the nonwoven fabric is increased, the fiber density and the mixed state of the fibers may be uneven, which may cause inconveniences such as a decrease in the uniformity of the composite molded body.

In the non-woven fabric, the fibers may be adhered to each other by a part of the fibers for matrix, or the fibers may not be adhered to each other. Further, the fibers constituting the nonwoven fabric may be subjected to a mechanical entanglement treatment (for example, needle punching treatment, high pressure fluid flow treatment) and entangled with each other. By subjecting to the mechanical entanglement treatment, the fibrous splitting ratio of the matrix fibers becomes higher in the finally obtained nonwoven fabric, and the mechanical properties related to the fibrous splitting of the fibers are more likely to be improved in the composite molded body.

Alternatively, for example, when the nonwoven fabric is made from a wet papermaking web, it is not subjected to mechanical entanglement treatment, and is compared with the entanglement of fibers generated during papermaking (generally compared with the entanglement by mechanical entanglement treatment). It may be integrated by (it is loose). When the nonwoven fabric is produced without undergoing a mechanical entanglement treatment, matrix fibers having a higher split fiber ratio (that is, easier to divide) may be used. This is because when the mechanical entanglement treatment is not performed, the splitting ratio of the matrix fibers tends to decrease in the finally obtained non-woven fabric. In the case of producing from a wet papermaking web, the fibers for matrix can be split by stirring at the time of forming a slurry (aqueous dispersion liquid containing fibers) before papermaking.

The nonwoven fabric may contain fibers other than the matrix fibers described as the first embodiment (hereinafter, "other fibers"). The other fiber may be, for example, a single fiber composed of the thermoplastic resin exemplified in Embodiment 1, or a composite fiber such as a core-sheath type composite fiber, a side-by-side type composite fiber, or a sea-island type composite fiber.
When other fibers are contained, the other fibers are contained in a proportion of 30% by mass or less, particularly 20% by mass or less, and more particularly, when the total mass of the fibers constituting the non-woven fabric is 100% by mass. It is contained in a proportion of 10% by mass or less. The other fibers may form a matrix of the composite molded product together with the fibers for the matrix. For example, if the other fiber is a single fiber made of polypropylene and the matrix fiber is a composite fiber made of a nylon 6 / polypropylene combination, the other fiber may constitute a matrix.

As described in the first embodiment, the matrix fibers constituting the non-woven fabric are liable to cause peeling between each section, and are liable to generate ultrafine fibers composed of one or a plurality of sections. Therefore, in the nonwoven fabric of the present embodiment, the expression ratio of the ultrafine fibers on the nonwoven fabric surface measured by the following method may be more than 20%, particularly 30% or more, and more particularly 40% or more. .. The upper limit of the expression rate of the ultrafine fibers may be, for example, 100%.
<Measuring method of expression ratio of ultrafine fibers on the surface of non-woven fabric>
(1) The surface of the base material is observed with an electron microscope at a magnification of 150 to 200 times, and the enlarged surface is photographed.
(2) Among the fibers present in the photographed image, the number of fibers for the composite molded body matrix having a length of 200 μm or more and the number of fibers derived from the fibers for the composite molded body matrix are counted. Among them, fibers having a fiber length of 150 μm or more and a fiber diameter smaller than 1/2 are defined as ultrafine fibers.
(3) The expression ratio of ultrafine fibers is determined by the following formula.
Expression rate of ultrafine fibers (%) = (number of ultrafine fibers / number of fibers for composite molded matrix) × 100

The higher the expression ratio of the ultrafine fibers on the surface of the non-woven fabric, the more the matrix fibers have peeling between the sections. Nonwoven fabrics with more peeling between sections tend to have improved mechanical properties in complexes made using them. On the other hand, when the expression ratio of the ultrafine fibers on the surface of the non-woven fabric is small, the impact resistance tends to decrease, but the bending characteristics tend to improve.

Alternatively, in the nonwoven fabric of the present embodiment, the fibrous split ratio of the matrix fibers measured by the following method may be more than 30%, particularly 35% or more, and more particularly 40% or more. .. The upper limit of the split fiber ratio may be, for example, 100%.
<Measuring method of split fiber ratio of matrix fibers in non-woven fabric>
(1) The base materials are bundled so as not to create a space as much as possible, and cut so that the fiber cross section of the composite molded body matrix fiber can be observed to expose the cross section.
(2) Observe the cross section at a magnification of 400 to 600 times with an electron microscope, and photograph the magnified cross section.
(3) From the captured image, select the split fiber from the fibers derived from the composite molded body matrix fiber (non-split fiber and split fiber). Count the number of sections of split fibers and the number of sections of unsplit fibers.
Non-split fiber: Fiber having a cross-sectional area of 1/2 or more of the cross-sectional area of the fiber that is not split at all Split fiber: From 1/2 of the cross-sectional area of the fiber that is not split at all Fiber with a small cross-sectional area (4) The split fiber ratio is obtained by the following formula.
Split fiber ratio (%) = [Number of split fiber sections / (Number of split fiber sections + Number of unsplit fiber sections)] x 100

The splitting ratio of the matrix fibers is also an indicator of how much peeling occurs between the sections of the matrix fibers, and the larger the splitting ratio, the more peeling occurs between the sections of the matrix fibers. It will be. Nonwoven fabrics with more peeling between sections tend to have improved mechanical properties in complexes made using them.

[Manufacturing method of non-woven fabric for composite molded body]
Subsequently, a method for manufacturing a nonwoven fabric for a composite molded body will be described.
The non-woven fabric can be produced by a conventional method, and is produced by forming a fiber web using reinforcing fibers and thermoplastic resin fibers, and then adhering and / or entwining the fibers to integrate them. The form of the fiber web is not particularly limited, and may be any form selected from card webs such as parallel webs, cross webs, semi-random webs and random webs, air-laid webs, wet papermaking webs, spunbond webs and the like. good.

In the present embodiment, an air-laid web, a cross web, or a wet papermaking web is preferably used because the fiber orientation is random and the difference in strength and elongation in the vertical and horizontal directions is small.

In the production of the non-woven fabric, the method of integrating the fibers of the fiber web is not particularly limited. For example, the fiber integration may be performed by a mechanical entanglement method such as a needle punch method and a water flow entanglement treatment method. According to the needle punch method, the fibers can be entangled with each other relatively easily even when the basis weight of the fiber web is large. For example, when the fiber web is produced by needle punching, if the grain of the fiber web is, for example, about 100 g / m ² to 12000 g / m ² , the needle is 36 to 42 counts and the number of barbs is 3. It may be carried out by using a needle having a needle depth of about 9 and setting the needle depth to 3 to 20 mm and driving at a density of 10 to 500 needles / cm ² .

Alternatively, the integration of the fibers may be due to the entanglement of the fibers that occurs in the papermaking step, the drying step, and the like when the papermaking web is produced.

Alternatively, one or a plurality of components constituting the matrix fibers may be melted and the fibers may be thermally adhered to each other to integrate the fibers. In that case, it is preferable to melt only the low melting point component. The heat bonding may be carried out using, for example, a hot air penetration type heat treatment machine (also referred to as an air-through type heat processing machine), a hot air blowing type heat treatment machine, an infrared heat treatment machine, or the like, or a hot roll processing machine or the like.

The fineness and fiber length of the fibers constituting the non-woven fabric are selected according to the morphology of the fiber web and the like. Exemplary ranges of fiber lengths for reinforcing fibers and matrix fibers are as described above. In any of the fiber webs, the fiber length of the reinforcing fibers may be the same as or different from that of the matrix fibers. The exemplary fineness of the reinforcing fibers and the matrix fibers is also as described above, and the fineness of the reinforcing fibers may be the same as or different from that of the matrix fibers.

The nonwoven fabric may be made by laminating two or more fiber webs. In that case, one or more fiber webs may be made of reinforcing fibers and the other one or more fiber webs may be made of matrix fibers. The two or more fiber webs may be made in the same way or in different ways (eg, a combination of a card web and a wet papermaking web).

In order to increase the basis weight of the nonwoven fabric, two or more same or different fiber webs may be laminated and subjected to a process of integrating the fibers (for example, a fiber entanglement process such as needle punching). In particular, when it is difficult to manufacture the fiber web with a large basis weight, the nonwoven fabric with a large basis weight can be manufactured relatively easily by laminating the fiber web. Alternatively, in order to superimpose a fiber web or a non-woven fabric made from the fiber web with another non-woven fabric or woven fabric, knitted fabric, or film and subject the non-woven fabric or a non-woven fabric made from the fiber web to a fiber entanglement treatment such as needle punching in that state to prepare a composite molded body. Fiber sheet may be prepared.

The nonwoven fabric of the present embodiment is a composite fiber composed of a reinforcing fiber and two or more types of thermoplastic resins having different melting points or bicut softening temperatures, and each section is exposed on the fiber surface. It is formed by mixing fibers (easily split fiber composite fibers). Furthermore, in the nonwoven fabric of the present embodiment, the sections of the composite fiber are separated to generate ultrafine fibers. Therefore, the nonwoven fabric of the present embodiment is likely to be provided as a form in which the reinforcing fibers and two or more types of thermoplastic resins are more uniformly mixed, and the two or more types of thermoplastic resins each form a block (lump) shape. In the block formed from one resin, the other resin exists in an island-like shape.

Further, in the composite molded body manufactured using this non-woven fabric, a resin having a low melting point or a Vicat softening temperature forms an island component, and a resin having a high melting point or a Vicat softening temperature forms a sea component, so that the machine is higher. Tends to show specific characteristics. Furthermore, it is speculated that in the composite molded body manufactured using this non-woven fabric, the characteristics of the resin constituting the ultrafine fibers are more exhibited by melting the ultrafine fibers composed of a single component to form a matrix. Will be done. For example, when the matrix fiber is a composite fiber made of a combination of nylon 6 / polypropylene, the separation between the sections forms an ultrafine fiber made of nylon 6 having relatively high rigidity, which ensures the impact resistance of the composite molded body. It is thought that it contributes to.

(Embodiment 3: Composite molded body and method for manufacturing the same)
Next, as the third embodiment, a composite molded body and a method for manufacturing the composite molded body will be described.

[Composite molded product]
The composite molded body of the present embodiment is a composite molded body containing a reinforcing fiber and two or more types of thermoplastic resins having a melting point difference or a Vicat softening temperature difference as a matrix, and the matrix has three or more sections. It is a composite fiber, which is formed by melting a composite fiber in which each section is exposed on the fiber surface. In the matrix, two or more kinds of thermoplastic resins having different main components may not be compatible with each other.
The reinforcing fibers are as described in the second embodiment, and the fibers forming the matrix are as described in the first embodiment.

In the composite molded body of the present embodiment, the matrix has three or more sections, and the easily split fiber composite fibers in which each section is exposed on the fiber surface are split to form ultrafine fibers. Each resin constituting the composite fiber is melted and formed. Thereby, in at least one cross-sectional view of the composite molded body, the matrix is in a form containing a sea component and an island component. In the present embodiment, the resin having a higher melting point or the Vicat softening temperature forms the sea component, and the resin having a lower melting point or the Vicat softening temperature forms the island component.

When two resins with different melting points or Vicat softening temperatures are subjected to heat treatment at the same time, the resin with a low melting point or a low Vicat softening temperature usually starts melting first, and then the resin with a high melting point or a high Vicat softening temperature starts melting. do. Therefore, it was considered that a resin having a low melting point or a low Vicat softening temperature forms a sea component, but in the present embodiment, surprisingly, a resin having a high melting point or a high Vicat softening temperature forms a sea component and has a low melting point. Alternatively, a resin having a low vicut softening temperature forms an island component.

The reason why such a sea-island structure is obtained is not clear, but it is considered that two or more types of thermoplastic resins having different main components, that is, the compatibility with each other is not so high. As a result of combining such resins, the previously melted resin (low melting point or low Vicat softening temperature) "repels" from the other resin, causing agglomeration and facilitating the formation of island components, later. It is presumed that the resin to be melted (high melting point or high vicut softening temperature) covers its surroundings to form sea components. It is considered that the obtained composite molded body is broken from the interface of two or more kinds of thermoplastic resins having different main components in bending property or impact resistance property due to the matrix having such a morphology. It is presumed that large blocks of components and island components contribute to ensuring strength and shock absorption.

For example, when the two types of thermoplastic resins having different main components are nylon 6 as a resin having a high melting point or Vicat softening temperature and polypropylene as a resin having a low melting point or Vicat softening temperature, nylon 6 forms a sea component. Polypropylene forms the island component. Moreover, the island component formed of polypropylene becomes a block-shaped island in which resins are aggregated, while the sea component formed of nylon 6 having a high affinity with reinforcing fibers (for example, carbon fiber) is around the reinforcing fibers. By being present, predetermined bending characteristics and impact resistance characteristics can be obtained.

Among the island components, it is preferable that the number of island components measured by the following method is 10 or more in at least one cross-sectional view of the composite molded body. It is more preferably 15 or more, still more preferably 20 or more. When the number of island components is within such a range, the island components act as a shock absorber, and shock resistance characteristics can be obtained.
[Method of calculation]
The cross section of the composite molded body is observed with an electron microscope at a magnification of 600 times, the enlarged cross section is photographed, and then the ratio of the number of island components present in the photographed image (32000 μm ² ) is calculated.

Among the island components, in at least one cross-sectional view of the composite molded body, the island component having a maximum transfer length (Dmax) of 10 μm or less measured by the following method is more than 0% and 70% or less and / or 50 μm or more. It is preferable that the island component is more than 0% and 30% or less. More preferably, the island component of 10 μm or less is 5% or more and 68% or less and / or the island component of 50 μm or more is 1% or more and 28% or less, and more preferably the island component of 10 μm or less is 10% or more and 65% or less and / or. The island component of 50 μm or more is 3% or more and 25% or less. When the Dmax is 10 μm or less and / or the ratio of the island component having a Dmax of 50 μm or more is within such a range, the island component is easily dispersed in the sea component, and the sea component is easily distributed around the carbon fiber. Bending physical properties can be improved and impact resistance can be obtained.

[Method of calculation]
The cross section of the composite molded body is observed with an electron microscope at a magnification of 600 times, and after taking a magnified cross section, the Dmax of the island components present in the photographed image (32000 μm ² ) is measured, and the total number of island components is calculated. The ratio of the number of island components having a Dmax of 10 μm or less and the ratio of the number of island components having a Dmax of 50 μm or more are calculated.

In the composite molded body of the present embodiment, the flexural modulus measured in accordance with the method A (bending test method by three-point bending) of JIS K 7074: 1998 (bending test method of carbon fiber reinforced plastic) of the composite molded body. Is preferably 10 Gpa or more, more preferably 15 Gpa or more, further preferably 20 Gpa or more, particularly preferably 25 Gpa or more, and most preferably 30 Gpa or more. A composite molded product within the above range is preferably used in applications where rigidity is important.

In the composite molded body of the present embodiment, the bending stress measured in accordance with JIS K 7074: 1998 (carbon fiber reinforced plastic bending test method) A method (bending test method by three-point bending) of the composite molded body is , 200 Mpa or more, more preferably 230 or more, further preferably 250 Mpa or more, particularly preferably 300 Mpa or more, and most preferably 320 Mpa or more. A composite molded body having a bending stress within the above range is preferably used in applications where strength is required.
In the composite molded body of the present embodiment, it was obtained by measuring in accordance with JIS K 7074: 1998 (bending test method of carbon fiber reinforced plastic) A method (bending test method by three-point bending) of the composite molded body. The impact energy (N · mm) calculated from the bending load-bending deflection curve is preferably 700 N · mm or more, more preferably 800 N · mm or more, still more preferably 900 N · mm or more. It is particularly preferably 1000 N · mm or more, and most preferably 1100 N · mm or more. A composite molded body having an impact energy within the above range is preferably used in applications where toughness is required.

In the composite molded body of the present embodiment, the Charpy impact strength measured according to JIS K 7111: 2012 of the composite molded body is preferably 5 kJ / m ² or more, and preferably 7 kJ / m ² or more. More preferably, it is 9 kJ / m ² or more, more preferably 10 kJ / m ² or more, and most preferably 11 kJ / m ² or more. A composite molded body having a Charpy impact strength within the above range is preferably used in applications where impact resistance is required.

In the present embodiment, the composite molded body contains, for example, 20% by volume or more and 60% by volume or less of reinforcing fibers, particularly 25% by volume or more and 55% by volume or less, and contains a thermoplastic resin, for example, 40% by volume or more and 80% by volume. % Or less, particularly 45% by volume or more and 75% by volume or less. In particular, when the reinforcing fiber is a carbon fiber, the ratio of the carbon fiber is 20% by volume or more and 50% by volume or less, particularly 25% by volume or more and 40% by volume or less, and the thermoplastic resin is 50% by volume or more and 80% by volume. It may be contained in an amount of 60% by volume or less, particularly 60% by volume or more and 75% by volume or less. If the proportion of the reinforcing fibers is too small, the effect of mechanically improving the composite molded body by the reinforcing fibers may not be obtained, and if the proportion of the reinforcing fibers is too large, the proportion of the matrix in the composite molded body becomes small. When producing a composite molded body, the matrix may not be able to sufficiently fill the space between the reinforcing fibers, the voids may increase, the density of the composite molded body may be reduced, and the mechanical properties may be deteriorated.

In the present embodiment, the volume ratio of the low melting point resin (or low vicut softening temperature resin) and the high melting point resin (or high vicut softening temperature resin) when two types of thermoplastic resins are made into a composite fiber, and the composite molded body. Comparing the area ratios of the low melting point resin and the high melting point resin, the ratio of the high melting point resin tends to be larger in the latter. It is considered that this is because the high melting point resin becomes large in volume due to expansion due to heat when the composite molded body is manufactured, and melts so as to enclose around the low melting point resin.

The composite molded body of the present invention is provided, for example, as a sheet-like material, a plate-like material, or a three-dimensional structure molded into a predetermined shape.

The thickness and basis weight of the sheet-shaped or plate-shaped composite molded product are appropriately selected depending on the intended use and the like, and are not particularly limited. For example, a thickness of 0.3 mm or more and 10 mm or less, and 400 g / m ² or more and 12000 g. It has a basis weight of / m ² or less. A sheet-shaped composite molded body containing a thermoplastic resin as a matrix resin can be provided as a stampable sheet that can be molded into another shape by heating and pressurizing. Molding of stampable sheets is sometimes called stamping molding.

The sheet-shaped composite molded body may be manufactured from the nonwoven fabric described in the second embodiment. In the case of producing a composite molded body from a non-woven fabric, a part of the sections constituting the matrix fiber is not completely melted depending on the temperature and pressure applied to the matrix fiber, and in the composite molded body, from the matrix fiber. The section may exist with some maintenance of fiber shape.

In the composite molded body manufactured by using the non-woven fabric containing the matrix fibers, among the resins in the matrix fibers, the reinforcing fibers, particularly the resin having high compatibility with the carbon fibers, is present in contact with the periphery of the reinforcing fibers. That is, more specifically, the highly compatible resin becomes a sea component and comes into contact with the periphery of the reinforcing fiber, so that the mechanical properties tend to be improved. Therefore, the composite molded product of the present embodiment may have a density of, for example, 90% or more, particularly 92% or more, more particularly 95% or more of its true density. Ideally, the composite molded product is formed with a true density, but may have a density of, for example, 99.5% or less. Within the numerical range where the true density is applied, the voids in the board are reduced and the mechanical properties are improved.

式中、
Ａ：樹脂１の密度×マトリックス用繊維における樹脂１の体積割合
Ｂ：樹脂２の密度×マトリックス用繊維における樹脂２の体積割合 The true density of the composite molded body can be calculated from the density of the material itself constituting the composite molded body and the ratio (volume ratio) of the material to the composite molded body. Specifically, when the matrix fiber is composed of the resin 1 and the resin 2, the true density can be obtained by the following formula.

During the ceremony
A: Density of resin 1 x volume ratio of resin 1 in matrix fiber B: density of resin 2 x volume ratio of resin 2 in matrix fiber

For example, the composite molded body is composed of a combination of carbon fiber, which is a reinforcing fiber, and nylon 6 / polypropylene, which is a fiber for matrix, and has a composite fiber ratio of 3: 7 (nylon 6: polypropylene), which is 70% by volume. If it consists of, the true density is 1.22 g / cm ³ (carbon fiber density 1.80 g / cm ^3, nylon 6 density 1.14 g / cm ³ , polypropylene density 0.91 g / cm ³ ). Is the value calculated as).

The composite molded body of the present embodiment may be provided as a three-dimensional structure processed into a predetermined shape. The three-dimensional structure is, for example, a three-dimensionally molded non-woven fabric of the second embodiment when heated and pressed, or a three-dimensionally molded sheet-shaped composite molded body (stampable sheet). It may be there. Alternatively, the three-dimensional structure may be formed by subjecting a block of a composite molded body to a cutting process to form a predetermined shape.

In the composite molded body of the present embodiment, the matrix is a composite fiber composed of two or more types of thermoplastic resins having different melting points or bicut softening temperatures and having three or more sections, and each section is exposed on the fiber surface. It may be formed by melting the composite fiber. Since this composite fiber is composed of two or more types of thermoplastic resins forming relatively small sections, the matrix formed by melting the composite fibers forms the shape of a block (lump), and one of the resins is formed. In the block formed from, the other resin exists in an island-like shape.

[Manufacturing method of composite molded product]
The composite molded body of the present embodiment can be manufactured, for example, by using the nonwoven fabric described as the second embodiment. Specifically, the composite molded body of the present embodiment is
A manufacturing method comprising preparing a nonwoven fabric for composite molding according to the second embodiment and heating the nonwoven fabric for composite molding.
By heating the nonwoven fabric for composite molding, the resin having the lowest melting point or Vicat softening temperature among the two or more types of thermoplastic resins is melted and
When two or more types of thermoplastic resins constituting the composite molded body matrix fiber are all crystalline resins, (Tm-30) ° C. or higher when the melting point of the thermoplastic resin component having the highest melting point is Tm ° C. Performed at a temperature of (Tm + 50) ° C or lower,
When at least one of the two or more types of thermoplastic resins constituting the composite molded body matrix fiber is an amorphous resin, when the Vicat softening temperature of the thermoplastic resin having the highest Vicat softening temperature is VST ° C., ( Perform at a temperature of VST + 20) ° C or higher (VST + 150) ° C or lower,
Including further pressurization when heating the non-woven fabric for composite molding,
The heating and the pressurization are carried out so that the density of the composite molded product is 90% or more and 99.5% or less of the true density.
It can be manufactured by a manufacturing method.

When the nonwoven fabric of the second embodiment is used, a plurality of nonwoven fabrics may be laminated and the laminated nonwoven fabric may be heated and pressure-treated according to the basis weight of the composite molded body to be obtained.

The heating and pressure treatment can be said to be a step of combining the reinforcing fiber and the thermoplastic resin (matrix). At the time of compounding, the thermoplastic resin is melted or softened by heating, the thermoplastic resin is infiltrated into the voids between the reinforcing fibers, and the voids are filled with the resin. In the present embodiment, the pressure treatment is carried out at the same time to further promote the penetration of the thermoplastic resin into the voids between the reinforcing fibers so that the density of the composite molded body becomes the above-mentioned predetermined value.

In the production method of the present embodiment, as described above, heating and pressurization are performed so that the density of the obtained molded product is 90% or more and 99.5% or less of its true density. Therefore, heating and pressurization are carried out by selecting conditions under which the thermoplastic resin constituting the matrix fibers has sufficient fluidity and the thermoplastic resin having fluidity penetrates into the voids between the reinforcing fibers. ..

When two or more kinds of thermoplastic resins constituting the matrix fiber are all crystalline resins, the temperature at the time of heating is based on the melting point of the thermoplastic resin component having the highest melting point at Tm ° C. (Tm). It may be a temperature of -30) ° C or higher (Tm + 50) ° C, particularly a temperature of (Tm-20) ° C or higher (Tm + 45) ° C, and more particularly a temperature of (Tm-15) ° C or higher (Tm + 40) ° C. In particular, the temperature may be (Tm-10) ° C. or higher (Tm + 37) ° C., and most preferably the temperature may be Tm ° C. or higher (Tm + 35) ° C. or lower.

Here, the melting point of each resin constituting the matrix fiber composed of only the crystalline resin is the melting point of the thermoplastic resin in the state of being made into the matrix fiber (that is, the melting point after spinning), and the differential operation calorie analysis method ( It can be measured by DSC). Specifically, based on the JIS K 7121 (1987) plastic transition temperature measurement method, a differential scanning calorimeter (manufactured by Seiko Instruments Co., Ltd.) was used, and the amount of fiber (sample amount) was set to 3.0 mg. It can be obtained from the obtained heat of fusion curve by heating the temperature from normal temperature to 300 ° C. at a heating speed of 10 ° C./min to melt the fibers. The heat of fusion curve obtained by melting a composite fiber usually has a plurality of peaks depending on the number of constituent resins. The heating temperature is set by obtaining Tm from the peak that appears at the highest temperature among the plurality of peaks.

When at least one of the resins constituting the matrix fiber is an amorphous resin, the temperature at the time of heating is (VST + 20) ° C. with reference to the Vicat softening temperature VST ° C. of the thermoplastic resin component having the highest Vicat softening temperature. The temperature may be at least (VST + 150) ° C., particularly at (VST + 40) ° C. or higher (VST + 140) ° C., more particularly at (VST + 60) ° C. or higher (VST + 130) ° C., and more preferably (VST + 80). ) ° C. or higher (VST + 120) ° C. or lower.

The Vicat softening temperature of the amorphous resin is when the heat transfer medium is heated at a constant speed by applying the specified test load to the test piece made of only the resin, and the needle-shaped indenter penetrates 1 mm from the surface of the test piece. The temperature of the heat transfer medium, which can be measured by the method described in JIS K 7206 B50 method.

In the present embodiment, the matrix fiber itself or the fiber derived from the matrix fiber itself (for example, the ultrafine fiber produced by separating the sections) in the obtained composite molded body so that the density of the composite molded body is within the above-mentioned predetermined range. It is preferable that the fiber shape does not remain. Therefore, the heating temperature is set with reference to the melting point of the thermoplastic resin having the highest melting point, which constitutes the matrix fiber.

When the matrix fiber is made of, for example, a nylon 6 / polypropylene combination, the heating temperature may be 190 ° C. or higher and 300 ° C. or lower, particularly 200 ° C. or higher and 280 ° C. or lower, more particularly 205 ° C. or higher and 270 ° C. or lower, and further. It may be preferably 210 ° C. or higher and 260 ° C. or lower, and most preferably 220 ° C. or higher and 255 ° C. or lower.

The pressure at the time of pressurization is appropriately selected in consideration of the fluidity of the thermoplastic resin constituting the fiber, and may be, for example, 1 MPa or more and 50 MPa or less, particularly 3 MPa or more and 30 MPa or less, and more particularly 5 MPa or more and 20 MPa or less. May be. When the resin constituting the matrix fiber contains a resin having low fluidity, the pressure is selected so that the flow of the resin is sufficiently promoted.

When the matrix fiber is made of, for example, a nylon 6 / polypropylene combination, the fluidity of the molten nylon 6 is smaller than that of the molten polypropylene. Therefore, when this fiber is used, the pressure at the time of pressurization may be, for example, 1 MPa or more and 50 MPa or less, particularly 3 MPa or more and 30 MPa or less, and more particularly 5 MPa or more and 20 MPa or less. The pressure in this range promotes the flow of nylon 6 and easily fills the voids between the reinforcing fibers with the matrix, especially when the heating temperature is in the above range.

If there is a difference in the fluidity of the thermoplastic resin, during the heating and pressurizing treatment, the highly fluid resin first flows to fill the voids between the reinforcing fibers, and then the less fluid resin flows. Conceivable. By shifting the flow timing of two or more types of resin, the voids between the reinforcing fibers are more filled and the density of the molded product can be easily adjusted. It may constitute a fiber.

The time (high pressure holding time) for heating and pressurizing the composite molded non-woven fabric during the pressure treatment is, for example, 1 second or more and 600 seconds or less, particularly, depending on the type of the reinforcing fiber and the matrix fiber used. It may be 30 seconds or more and 240 seconds or less, and more particularly 60 seconds or more and 200 seconds or less. If the high pressure holding time is too short, the density of the molded product may not be sufficiently high, and if it is too long, the thermoplastic resin may be deteriorated and the mechanical properties of the obtained composite molded product may be deteriorated. ..

The high pressure holding time does not include the time to lower either the heating temperature or the pressure. For example, when the temperature is lowered while keeping the pressure as it is after holding the heated and pressurized state for a predetermined time at a predetermined heating temperature and a predetermined pressure, the time for lowering the temperature is the high pressure holding time. Not included.

The heating and pressurization may be performed using a device capable of simultaneously performing heating and pressurization, for example, a heat press machine. Alternatively, the heat treatment may be performed first, and then the pressure treatment may be performed while the thermoplastic resin is in a molten or softened state. Such heating and pressurization are also included in "further pressurizing when heating the nonwoven fabric for composite molding" in the outline of the production method of the present embodiment.

According to the present embodiment, a sheet-shaped composite molded body can be obtained, or is a three-dimensional structure by imparting a three-dimensional shape during heat treatment and / or pressure treatment. A composite molded body can be obtained. The sheet-shaped composite molded body (stampable sheet) can be further subjected to a hot press treatment to form a shape having irregularities. In that case, a plurality of sheet-shaped composite molded bodies may be laminated and heat-pressed to obtain a thicker composite molded body.

Needless to say, the method for manufacturing a composite molded body described here is one form of manufacturing the composite molded body, and the composite molded body may be manufactured by another manufacturing method depending on the shape. For example, the sheet-shaped composite molded body may be manufactured by applying another thermoplastic resin melted by impregnation or coating to a fiber sheet composed of matrix fibers and reinforcing fibers. In this method, when the melting point or the Vicat softening temperature of the other thermoplastic resin is higher than that of the thermoplastic resin constituting the matrix fiber having the highest melting point or the Vicat softening temperature, the thermoplastic resin is used. Melts the matrix fibers when applying. When the melting point or Vicat softening temperature of the other thermoplastic resin is lower than that of the thermoplastic resin constituting the matrix fiber having the highest melting point or Vicat softening temperature, the other thermoplastic resin is applied. After that, heating and pressure treatment are performed to melt the fibers for the matrix. When the fiber sheet is a woven fabric or a knitted fabric, the constituent yarns may be any of blended yarns, mixed twisted yarns, core yarns, and covered yarns composed of matrix fibers and reinforcing fibers.

The composite molded product of the present embodiment is excellent in mechanical properties. This is because the number of sections is 3 or more, and each section is a composite fiber exposed on the fiber surface, and the fiber in which separation between the sections is relatively easy to occur is melted to form a matrix. Conceivable. Such composite fibers generally consist of smaller sections compared to fibers consisting of two sections, such as core-sheath type composite fibers. It is believed that the smaller sections efficiently fill the voids between the reinforcing fibers to improve the density and thus improve the mechanical properties of the composite. Also, in a matrix formed by melting smaller sections, the plurality of thermoplastic resins each form a block (lump) shape, in the block formed from one resin or in the sea component of the other. The resin has an island-like shape, which is also considered to contribute to the improvement of mechanical properties. Furthermore, since each section is exposed on the fiber surface, it is considered that the formation of a network by joining each section after melting also contributes to the improvement of mechanical properties.

(Use of composite molded product)
The composite molded body of the present embodiment includes space and aircraft materials, marine materials, vehicle (including automobiles and bicycles) materials, sports equipment materials, OA equipment materials, electronic equipment materials, industrial materials, tanks and containers. It can be used as a kind of material, a material for miscellaneous goods, and a construction material. In particular, when carbon fiber is used as the reinforcing fiber, it is preferably used as an interior material and an exterior material of an aircraft by taking advantage of its light weight.

The following thermoplastic resins and reactive compatibilizers were prepared.
<Thermoplastic resin>
-Polypropylene (PP): SA01A (trade name) manufactured by Nippon Polypropylene Co., Ltd. Melting point 160 ° C.
-Nylon 6 (Ny-6): SF1018A (trade name) manufactured by Ube Corporation. Melting point 225 ° C
<Reactive compatibilizer>
-Modified polypropylene (adhesive resin in which maleic acid is introduced into polypropylene): Modic P908 (trade name) manufactured by Mitsubishi Chemical Corporation. It has a melting point of 150 ° C., an MFR of 45 g / 10 min (180 ° C.) and an acid value of 12.8 as measured under a load of 21.2 N (2.16 kgf) according to ISO R-1133.

<Manufacturing of matrix fibers>
[Manufacturing of fiber A for matrix]
A composite fiber having a cross section in which wedge-shaped sections as shown in FIG. 1A are arranged in a chrysanthemum shape and having 16 sections was produced as a matrix fiber A. First, nylon 6 and polypropylene to which modified polypropylene is added as a reactive compatibilizer at a ratio of 10% by mass are used for a split type composite fiber that gives the above composite form under the conditions of spinning temperatures of 280 ° C and 270 ° C, respectively. Melt spinning was performed using a nozzle to obtain a spun filament having a fineness of 4.5 dtex. At the time of melt spinning, the discharge amount of each resin was adjusted so that the composite ratio (volume ratio) was 7: 3 (PP: Ny-6). Subsequently, the spun filament was subjected to a dry drawing treatment at 125 ° C. with a draw ratio of 1.6 times to obtain a fineness of about 3.14 dtex, and then a fiber treatment agent was applied to cut the spun filament into a fiber length of 6 mm.

[Manufacturing of fiber B for matrix]
The core-sheath type composite fiber was produced as the matrix fiber B. First, nylon 6 and polypropylene to which modified polypropylene is added as a reactive compatibilizer at a ratio of 10% by mass are melted at spinning temperatures of 280 ° C. and 270 ° C. using a core-sheath type composite fiber nozzle. Spinning was performed to obtain a spun filament having a fineness of 3 dtex. At the time of melt spinning, the discharge amount of each resin was adjusted so that the composite ratio was 7: 3 (PP: Ny-6). Subsequently, the spun filament was subjected to a dry drawing treatment at 125 ° C. with a draw ratio of 1.8 times to obtain a fineness of about 1.89 dtex, and then a fiber treatment agent was applied to cut the spun filament into a fiber length of 6 mm.

[Manufacturing of fiber C for matrix]
A single fiber with no more than two sections observed in the fiber cross section was made as the matrix fiber 5. Nylon 6 was melt-spun using a single fiber nozzle to obtain a spun filament with a fineness of 5 dtex. Subsequently, a fiber treatment agent was applied to the spun filament and the fiber was cut to a fiber length of 6 mm.

[Manufacturing of fiber D for matrix]
A single fiber with no more than two sections observed in the fiber cross section was made as the matrix fiber 6. Modified polypropylene was added at a ratio of 10% by mass as a reactive compatibilizer, and polypropylene was melt-spun using a nozzle for a single fiber to obtain a spun filament having a fineness of 6 dtex. Subsequently, the spun filament was subjected to a wet drawing treatment at 90 ° C. at a draw ratio of 3.2 times to obtain a fineness of about 2.2 dtex, and then a fiber treatment agent was applied to cut the spun filament into a fiber length of 6 mm.

Table 1 shows the strength and elongation of the matrix fibers A to D, and the melting point of each component after fiberization.

The strength and elongation of the fiber are based on JIS-L-1015, and the load value and elongation at the time of fiber cutting are measured using a tensile tester when the grip interval of the sample is 20 mm, and the strength and elongation are measured, respectively. The melting point of each component after fiberization is the melting point of the thermoplastic resin in the state of being made into a fiber for matrix when the two or more kinds of thermoplastic resins constituting the fiber for matrix are composed only of crystalline resin. That is, it is the melting point after spinning) and can be measured by the differential scanning calorific value analysis method (DSC). Specifically, based on the JIS K 7121 (1987) plastic transition temperature measurement method, a differential scanning calorimeter (manufactured by Seiko Instruments Co., Ltd.) was used, and the amount of fiber (sample amount) was set to 3.0 mg. The fiber was melted by raising the temperature from normal temperature to 300 ° C. at a temperature rising speed of 10 ° C./min, and the amount was obtained from the obtained heat of melting curve. When a plurality of peaks appear for one resin, the first melting peak is adopted.

When the thermoplastic resin contains an amorphous resin, the melting point (bicut softening temperature) is determined by applying a test load specified for the test piece of the resin alone before fiberization to raise the temperature of the heat transfer medium at a constant rate. It is the temperature of the heat transfer medium when the needle-shaped indenter penetrates 1 mm from the surface of the test piece, and can be measured by the method described in JIS K 7206 B50 method.

<Examples 1 to 3 and Comparative Examples 1 to 7>
[Manufacturing of non-woven fabrics for composite moldings]
Carbon fiber (manufactured by Teijin, HT C140X (trade name)) was prepared as a reinforcing fiber. The fineness of the carbon fiber was 0.67 dtex, the fiber diameter was 5 μm, and the fiber length was 6 mm. The mixing ratios of the carbon fibers were set as shown in Table 2, and after mixing with the matrix fibers shown in Table 2, a wet nonwoven fabric having a basis weight of 200 g / m ² was obtained by a wet papermaking method. In the production of the wet nonwoven fabric, the fibers were not entangled with each other by mechanical treatment, and the entangled fibers were not adhered to each other.

When the expression ratio of the ultrafine fibers on the surface of the nonwoven fabric was determined for the nonwoven fabrics of Examples 1 to 3, it was as shown in Table 2. Further, when the split fiber ratio of the matrix fibers was measured for these non-woven fabrics, it was as shown in Table 2.

[Manufacturing of composite molded product]
Twelve non-woven fabrics for composite molded bodies are stacked to form a laminated body having a basis weight of about 2400 g / m ² (the non-woven fabrics are not integrated), and a pressure of 10 MPa is applied to the laminated body at the temperature shown in Table 2. , Heat and pressure treatment was carried out. The high pressure holding time was 180 seconds. The heat and pressurization treatment was carried out using a press machine in which dies made of flat metal plates were arranged one above the other. The heating temperature is raised over about 3 minutes so that the temperature of the mold during the high-pressure holding time becomes the temperature shown in Table 2, and after about 3 minutes after the high-pressure holding time elapses, the temperature of the mold reaches 60 ° C. The temperature was lowered by cooling the mold with cooling water so as to reach 50 ° C. When the heating temperature reached 60 ° C. to 50 ° C., the mold was opened and the composite molded product was taken out.

The flexural modulus, bending stress, impact energy and Charpy impact strength of the obtained composite molded bodies of each Example and each Comparative Example were measured by the following methods. The measurement results are shown in Table 2. Further, electron micrographs showing cross sections of the composite molded bodies obtained in Examples 1 to 3 are shown in FIGS. 2 to 4.
<Bending modulus>
In accordance with JIS K 7074: 1998 (carbon fiber reinforced plastic bending test method) A method (bending test method by 3-point bending), a sample having a width of 15 mm and a length of 100 mm was prepared from the obtained composite molded body. Bending strength was measured at a test speed of 5 mm / min using an Autograph (registered trademark) AG-100kNIS manufactured by Shimadzu Corporation. The thickness of the sample and the distance between the fulcrums of the autograph are as shown in Table 2.

<Bending stress>
In accordance with JIS K 7074: 1998 (carbon fiber reinforced plastic bending test method) A method (bending test method by 3-point bending), a sample having a width of 15 mm and a length of 100 mm was prepared from the obtained composite molded body. The flexural modulus was measured at a test speed of 5 mm / min using an Autograph (registered trademark) AG-100kNIS manufactured by Shimadzu Corporation. The thickness of the sample and the distance between the fulcrums of the autograph are as shown in Table 2.

<Impact energy>
In accordance with JIS K 7074: 1998 (carbon fiber reinforced plastic bending test method) A method (bending test method by 3-point bending), a sample having a width of 15 mm and a length of 100 mm was prepared from the obtained composite molded body. Bending load (N) and bending deflection (mm) were obtained by measuring at a test speed of 5 mm / min using Autograph (registered trademark) AG-100kNIS manufactured by Shimadzu Corporation. From the bending load-bending deflection curve obtained by plotting them, the area from bending deflection 0 mm to 12 mm was obtained, and it was calculated as impact energy (N mm). In the present invention, when the bending deflection is around 10 mm (around 2% when converted to bending strain), the presence or absence of toughness becomes clear, and the bending load-bending deflection curve after fracture does not change significantly. The bending deflection was 12 mm as the end point.

<Charpy impact strength>
According to JIS K 7111: 2012, a test piece having a length of 80 mm and a width of 10 mm (edgewise, No. 1 test piece, C notch) was used, and the measurement was performed with a weighing capacity of 5 J. Specifically, the test pieces were set on a beam at intervals of 60 mm, a hammer was swung down from the upper part, and the test pieces set on the lower beam were destroyed. The Charpy impact strength was calculated from the absorbed energy at the time of destruction. The sample thickness is as shown in Table 2.

As shown in FIGS. 2 to 4, Examples 1 to 3 have a matrix in which the island component 1 made of polypropylene, which is a low melting point resin, is dispersed in the sea component 2 made of nylon 6 which is a high melting point resin. Was there. Further, in Examples 1 to 3, the number of island components, the ratio of the number of island components having a maximum delivery length of 10 μm or less, and the ratio of the number of island components having a maximum delivery length of 50 μm or more were within the ranges described above. Therefore, it is considered that the bending physical properties are improved by appropriately arranging the island component having a small maximum transfer length and the island component having a large transfer length and having a certain number of island components.

Further, as shown in FIGS. 2 to 4, the area ratio of the high melting point resin (nylon 6) and the low melting point resin (polypropylene) is visual, but the volume ratio of the high melting point resin / low melting point resin when the composite fiber is produced. On the other hand, the area ratio of the high melting point resin / low melting point resin in the composite molded body was larger. This is because nylon 6 and polypropylene are not compatible with each other, so that the spread of the previously melted low melting point resin is hindered by the melting of nylon, and the high melting point resin expands in volume due to heat, resulting in a low melting point. It is thought that this is because it melts so as to enclose around the resin.

Further, as shown in FIGS. 5 and 6, the base material for the composite molded body used for producing the composite molded product of Examples 1 to 3 is a fiber for matrix during processing of the composite molded product (that is, in the state of a wet non-woven fabric). Peeling occurred between each section of the above, and ultrafine fibers were generated.

Further, as shown in FIGS. 7 to 9, the impact energies of the composite molded products of Examples 1 to 3 were higher than those of Comparative Examples. Since the processing temperature of Example 1 is 215 ° C. and the nylon 6 having a fiber melting point close to the processing temperature is in a semi-melted state, it is presumed that the nylon 6 tends to be sticky to the bending force, that is, toughness is large. As a result, although the impact energy was higher than that of the comparative example, since the nylon 6 was not completely melted, the adhesion between the nylon 6 and the carbon fiber was inferior, and the processing temperature was high in Examples 2 and 3. In comparison, it is presumed that the bending characteristics were lower. In Examples 2 and 3, since the processing temperature exceeds the melting point of nylon 6, it has a certain stickiness to the bending force, that is, sufficient toughness can be obtained as compared with the conventional composite molded body, and Comparative Example. Shows higher impact energy than. Further, in Examples 1 to 3, a characteristic two-stage peak can be confirmed, which results in high toughness and high impact energy. Each of these peaks is thought to be due to the fact that the carbon fibers are covered with either nylon 6 or polypropylene.

On the other hand, in Comparative Examples 1 to 3, it was confirmed that a large number of island components made of nylon, which is a refractory resin, were formed, but no island components made of polypropylene were present. Further, all of the composite molded bodies of Comparative Examples 1 to 7 tend to have inferior bending physical properties (particularly bending elastic modulus) as compared with the composite molded bodies of Examples 1 to 3 obtained by heat and pressure treatment at the same temperature. Was there.

In the combination of polypropylene and nylon 6, the composite molded product made of composite fibers having a predetermined split fiber property had excellent mechanical properties. Further, when the cross-sectional shape of the composite molded body was observed, it was confirmed that nylon 6 having a high melting point formed a sea component and polypropylene having a low melting point formed an island component. Therefore, at the interface between the carbon fiber and the matrix, nylon 6 having an inherently high adhesion to the carbon fiber tends to be present. It is presumed that this also contributed to the improvement of mechanical properties. In addition, since the island component containing the resin having a low melting point or the Vicat softening temperature is formed in the sea component containing the resin having a high melting point or the Vicat softening temperature, a large block formed by each resin ( It is presumed that the impact resistance is secured by absorbing the impact due to the existence of the island).

The present embodiment includes the following embodiments.
(Aspect 1)
A composite molded body containing a reinforcing fiber and a thermoplastic resin having two or more different main components as a matrix.
The matrix is formed by melting at least one section of a composite fiber in which the number of sections is 3 or more and each section is exposed on the fiber surface.
In at least one cross-sectional view of the composite molding, the matrix comprises a sea component and an island component.
When both the thermoplastic resin contained in the sea component and the thermoplastic resin contained in the island component are crystalline resins, the melting point measured based on JIS K 7121 of the thermoplastic resin contained in the sea component is , At least one of the thermoplastic resin contained in the sea component and the thermoplastic resin having a melting point higher than the melting point measured based on JIS K 7121 of the thermoplastic resin contained in the island component. When is an amorphous resin, the Vicat softening temperature measured based on the JIS K 7206 B50 method of the thermoplastic resin contained in the sea component is the JIS K 7206 B50 method of the thermoplastic resin contained in the island component. Higher than the Vicat softening temperature measured based on,
Composite molded body.
(Aspect 2)
The composite molded product according to the first aspect, wherein the number of island components measured by the following method is 10 or more in at least one cross-sectional view of the composite molded body among the island components.
[Method of calculation]
The cross section of the composite molded body is observed with an electron microscope at a magnification of 600 times, and after the enlarged cross section is photographed, the number of island components present in the photographed image (32000 μm ² ) is calculated.
(Aspect 3)
Among the island components, in at least one cross-sectional view of the composite molded body, the ratio of the number of island components having a maximum transfer length (Dmax) of 10 μm or less to the total number of island components measured by the following method is 0%. The composite molded body of Aspect 1 or 2, wherein the ratio of the number of island components of more than 70% and / or 50 μm or more is more than 0% and not more than 30%.
[Method of calculation]
The cross section of the composite molded body is observed with an electron microscope at a magnification of 600 times, and after taking a magnified cross section, the Dmax of the island components present in the photographed image (32000 μm ² ) is measured, and the total number of island components is calculated. The ratio of the number of island components having a Dmax of 10 μm or less and the ratio of the number of island components having a Dmax of 50 μm or more are calculated.
(Aspect 4)
A composite molded body containing a reinforcing fiber and two or more types of thermoplastic resins having different main components as a matrix.
The matrix is formed by melting at least one section of a composite fiber in which the number of sections is 3 or more and each section is exposed on the fiber surface.
When the two or more types of thermoplastic resins are all crystalline resins, the melting point difference measured based on JIS K 7121 in the combination of the two types of thermoplastic resins is 25 ° C. or higher and 150 ° C. or lower.
When at least one of the two or more types of thermoplastic resin is an amorphous resin, the Vicat softening temperature difference measured based on the JIS K 7206 B50 method in the combination of the two types of thermoplastic resin is 1 ° C. or more. Below 120 ° C,
The composite fiber is an easily split fiber composite fiber, which is a composite molded product obtained by splitting the fiber before melting to express ultrafine fibers.
(Aspect 5)
The composite molded product according to any one of aspects 1 to 4, wherein the reinforcing fiber is carbon fiber.
(Aspect 6)
Aspects 1 to 1, wherein at least two sections constituting the composite fiber are one of a polyolefin resin, a polyester resin, and a polyamide resin, and each contain a thermoplastic resin belonging to a different system. The composite molded product of any one of 5.
(Aspect 7)
The composite molded product according to any one of aspects 1 to 6, wherein the composite fiber comprises a section containing polypropylene and a section containing nylon 6.
(Aspect 8)
A composite molding base including a reinforcing fiber and a composite molding matrix fiber having two or more kinds of thermoplastic resins having different main components, having three or more sections, and each section is exposed on the fiber surface. It ’s a material,
The fiber for the composite molded body matrix is an easily split fiber composite fiber, and is
When the two or more types of thermoplastic resins are all crystalline resins, the melting point difference measured based on JIS K 7121 in the combination of the two types of thermoplastic resins is 25 ° C. or higher and 150 ° C. or lower.
When at least one of the two or more types of thermoplastic resin is an amorphous resin, the Vicat softening temperature difference measured based on the JIS K 7206 B50 method in the combination of the two types of thermoplastic resin is 1 ° C. or more. Below 120 ° C,
A base material for a composite molded body in which the expression ratio of ultrafine fibers derived from the fibers for the composite molded body matrix exceeds 20% on the surface of the base material for composite molding.
[Measuring method of expression rate of ultrafine fibers]
(1) The surface of the base material is observed with an electron microscope at a magnification of 150 to 200 times, and the enlarged surface is photographed.
(2) Among the fibers present in the photographed image, the number of fibers for the composite molded body matrix having a length of 200 μm or more and the number of fibers derived from the fibers for the composite molded body matrix are counted. Among them, fibers having a fiber length of 150 μm or more and a fiber diameter smaller than 1/2 are defined as ultrafine fibers.
(3) The expression ratio of ultrafine fibers is determined by the following formula.
Expression rate of ultrafine fibers (%) = (number of ultrafine fibers / number of fibers for composite molded matrix) × 100
(Aspect 9)
For composite molded bodies, including reinforcing fibers and thermoplastic resins having two or more different main components, having three or more sections, and each section is exposed on the fiber surface for a composite molded body matrix. It is a base material
The fiber for the composite molded body matrix is an easily split fiber composite fiber, and is
When the two or more types of thermoplastic resins are all crystalline resins, the melting point difference measured based on JIS K 7121 in the combination of the two types of thermoplastic resins is 25 ° C. or higher and 150 ° C. or lower.
When at least one of the two or more types of thermoplastic resin is an amorphous resin, the Vicat softening temperature difference measured based on the JIS K 7206 B50 method in the combination of the two types of thermoplastic resin is 1 ° C. or more. Below 120 ° C,
In the base material, the base material for a composite molded body in which the fiber splitting ratio of the fiber for the composite molded body matrix is 30% or more.
[Measurement method of split fiber ratio]
(1) The base materials are bundled so as not to create a space as much as possible, and cut so that the fiber cross section of the composite molded body matrix fiber can be observed to expose the cross section.
(2) Observe the cross section at a magnification of 400 to 600 times with an electron microscope, and photograph the magnified cross section.
(3) From the captured image, select the split fiber from the fibers derived from the composite molded body matrix fiber (non-split fiber and split fiber). Count the number of sections of split fibers and the number of sections of unsplit fibers.
Non-split fiber: Fiber having a cross-sectional area of 1/2 or more of the cross-sectional area of the fiber that is not split at all Split fiber: From 1/2 of the cross-sectional area of the fiber that is not split at all Fiber with a small cross-sectional area (4) The split fiber ratio is obtained by the following formula.
Split fiber ratio (%) = [Number of split fiber sections / (Number of split fiber sections + Number of unsplit fiber sections)] x 100
(Aspect 10)
At least two sections of the fiber for the composite molded body matrix are one of a polyolefin resin, a polyester resin, and a polyamide resin, and each contains a thermoplastic resin belonging to a different system. , A substrate for a composite molded body according to aspect 8 or 9.
(Aspect 11)
The base material for a composite molded body according to any one of aspects 8 to 10, wherein the fiber for the composite molded body comprises a section containing polypropylene and a section containing nylon 6.
(Aspect 12)
The base material for a composite molded body according to any one of aspects 8 to 11, wherein the reinforcing fiber is a carbon fiber.
(Aspect 13)
The base material for a composite molded body according to any one of aspects 8 to 12, wherein the base material for the composite molded body is a non-woven fabric. (Aspect 14)
It comprises a reinforcing fiber and a composite molded matrix fiber composed of two or more kinds of thermoplastic resins having different main components, having three or more sections, and each section is exposed on the fiber surface.
When the two or more types of thermoplastic resins are all crystalline resins, the melting point difference measured based on JIS K 7121 in the combination of the two types of thermoplastic resins is 25 ° C. or higher and 150 ° C. or lower.
When at least one of the two or more types of thermoplastic resin is an amorphous resin, the Vicat softening temperature difference measured based on the JIS K 7206 B50 method in the combination of the two types of thermoplastic resin is 1 ° C. or more. Below 120 ° C,
Preparing a composite molded base material in which the expression ratio of ultrafine fibers on the surface of the composite molded base material derived from the composite molded body matrix fibers exceeds 20%, and heating the composite molded base material. Including
When the base material for a composite molded body is heated, the resin having the lowest melting point or Vicat softening temperature among the two or more types of thermoplastic resins is melted and
When the two or more types of thermoplastic resins constituting the composite molded body matrix fiber are all crystalline resins, when the melting point of the thermoplastic resin having the highest melting point is Tm ° C, (Tm-30) ° C. The temperature should be above (Tm + 50) ° C or lower.
When at least one of the two or more types of thermoplastic resins constituting the composite molded body matrix fiber is an amorphous resin, when the Vicat softening temperature of the thermoplastic resin having the highest Vicat softening temperature is VST ° C. , Performed at a temperature of (VST + 20) ° C or higher (VST + 150) ° C or lower,
Including further pressurizing when heating the base material for a composite molded body,
The heating and the pressurization are carried out so that the density of the composite molded product is 90 % or more of the true density.
A method for manufacturing a composite molded product.
[Measuring method of expression rate of ultrafine fibers]
(1) The surface of the base material is observed with an electron microscope at a magnification of 150 to 200 times, and the enlarged surface is photographed.
(2) Among the fibers present in the photographed image, the number of fibers for the composite molded body matrix having a length of 200 μm or more and the number of fibers derived from the fibers for the composite molded body matrix are counted. Among them, fibers having a fiber length of 150 μm or more and a fiber diameter smaller than 1/2 are defined as ultrafine fibers.
(3) The expression ratio of ultrafine fibers is determined by the following formula.
Expression rate of ultrafine fibers (%) = (number of ultrafine fibers / number of fibers for composite molded matrix) × 100
(Aspect 15)
It comprises a reinforcing fiber and a composite molded matrix fiber composed of two or more kinds of thermoplastic resins having different main components, having three or more sections, and each section is exposed on the fiber surface.
When the two or more types of thermoplastic resins are all crystalline resins, the melting point difference measured based on JIS K 7121 in the combination of the two types of thermoplastic resins is 25 ° C. or higher and 150 ° C. or lower.
When at least one of the two or more types of thermoplastic resin is an amorphous resin, the Vicat softening temperature difference measured based on the JIS K 7206 B50 method in the combination of the two types of thermoplastic resin is 1 ° C. or more. Below 120 ° C,
It includes preparing a base material for a composite molded body having a fiber splitting ratio of 30% or more of the fiber for the composite molded body, and heating the base material for the composite molded body.
When the base material for a composite molded body is heated, the resin having the lowest melting point or Vicat softening temperature among the two or more types of thermoplastic resins is melted and
When the two or more types of thermoplastic resins constituting the composite molded fiber for the matrix are all crystalline resins, when the melting point of the thermoplastic resin component having the highest melting point is Tm ° C. (Tm-30). The temperature should be ℃ or higher (Tm + 50) ℃ or lower.
When at least one of the two or more types of thermoplastic resins constituting the composite molded body matrix fiber is an amorphous resin, when the Vicat softening temperature of the thermoplastic resin having the highest Vicat softening temperature is VST ° C. , Performed at a temperature of (VST + 20) ° C or higher (VST + 150) ° C or lower,
Including further pressurizing when heating the base material for a composite molded body,
The heating and the pressurization are carried out so that the density of the composite molded product is 90 % or more of the true density.
A method for manufacturing a composite molded product.
[Measurement method of split fiber ratio]
(1) The base materials are bundled so as not to create a space as much as possible, and cut so that the fiber cross section of the composite molded body matrix fiber can be observed to expose the cross section.
(2) Observe the cross section at a magnification of 400 to 600 times with an electron microscope, and photograph the magnified cross section.
(3) From the captured image, select the split fiber from the fibers derived from the composite molded body matrix fiber (non-split fiber and split fiber). Count the number of sections of split fibers and the number of sections of unsplit fibers.
Non-split fiber: Fiber having a cross-sectional area of 1/2 or more of the cross-sectional area of the fiber that is not split at all Split fiber: From 1/2 of the cross-sectional area of the fiber that is not split at all Fiber with a small cross-sectional area (4) The split fiber ratio is obtained by the following formula.
Split fiber ratio (%) = [Number of split fiber sections / (Number of split fiber sections + Number of unsplit fiber sections)] x 100
(Aspect 16)
An easily split fiber composite fiber having two or more types of thermoplastic resins having different main components, having three or more sections, and each section of the composite fiber is exposed on the fiber surface.
When the two or more types of thermoplastic resins are all crystalline resins, the melting point difference measured based on JIS K 7121 in the combination of the two types of thermoplastic resins is 25 ° C. or higher and 150 ° C. or lower.
When at least one of the two or more types of thermoplastic resin is an amorphous resin, the Vicat softening temperature difference measured based on the JIS K 7206 B50 method in the combination of the two types of thermoplastic resin is 1 ° C. or more. Fiber for composite molded body matrix at 120 ° C. or lower.
(Aspect 17)
16. Of embodiment 16, wherein at least two sections of the composite molded fiber matrix are any of a polyolefin-based resin, a polyester-based resin, and a polyamide-based resin, and include different types of thermoplastic resins. Fiber for composite molded matrix.
(Aspect 18)
The composite fiber is a fiber for a composite molded body matrix of aspect 16 or 17, which comprises a section containing polypropylene and a section containing nylon 6.

Since the matrix of the composite molded product of the present disclosure is formed by using a specific composite fiber, it has a high density and excellent mechanical properties as a matrix made of a thermoplastic resin. This composite molded body is a material for space and aircraft, a material for ships, a material for vehicles (including automobiles and bicycles), a material for sports equipment, a material for OA equipment, a material for electronic equipment, an industrial material, a material for tanks and containers. , As a material for miscellaneous goods, and as a construction material.

Claims (18)

A composite molded body containing a reinforcing fiber and a thermoplastic resin having two or more different main components as a matrix.
The matrix is formed by melting at least one section of a composite fiber in which the number of sections is 3 or more and each section is exposed on the fiber surface.
In at least one cross-sectional view of the composite molding, the matrix comprises a sea component and an island component.
When both the thermoplastic resin contained in the sea component and the thermoplastic resin contained in the island component are crystalline resins, the melting point measured based on JIS K 7121 of the thermoplastic resin contained in the sea component is , At least one of the thermoplastic resin contained in the sea component and the thermoplastic resin having a melting point higher than the melting point measured based on JIS K 7121 of the thermoplastic resin contained in the island component. When is an amorphous resin, the Vicat softening temperature measured based on the JIS K 7206 B50 method of the thermoplastic resin contained in the sea component is the JIS K 7206 B50 method of the thermoplastic resin contained in the island component. Higher than the Vicat softening temperature measured based on,
Composite molded body. The composite molded product according to claim 1, wherein the number of island components measured by the following method is 10 or more in at least one cross-sectional view of the composite molded body among the island components.
[Method of calculation]
The cross section of the composite molded body is observed with an electron microscope at a magnification of 600 times, and after the enlarged cross section is photographed, the number of island components present in the photographed image (32000 μm ² ) is calculated. Among the island components, in at least one cross-sectional view of the composite molded body, the ratio of the number of island components having a maximum transfer length (Dmax) of 10 μm or less to the total number of island components measured by the following method is 0%. The composite molded body according to claim 1 or 2, wherein the ratio of the number of island components of more than 70% and / or 50 μm or more is more than 0% and 30% or less.
[Method of calculation]
The cross section of the composite molded body is observed with an electron microscope at a magnification of 600 times, and after taking a magnified cross section, the Dmax of the island components present in the photographed image (32000 μm ² ) is measured, and the total number of island components is calculated. The ratio of the number of island components having a Dmax of 10 μm or less and the ratio of the number of island components having a Dmax of 50 μm or more are calculated. A composite molded body containing a reinforcing fiber and two or more types of thermoplastic resins having different main components as a matrix.
The matrix is formed by melting at least one section of a composite fiber in which the number of sections is 3 or more and each section is exposed on the fiber surface.
When the two or more types of thermoplastic resins are all crystalline resins, the melting point difference measured based on JIS K 7121 in the combination of the two types of thermoplastic resins is 25 ° C. or higher and 150 ° C. or lower.
When at least one of the two or more types of thermoplastic resin is an amorphous resin, the Vicat softening temperature difference measured based on the JIS K 7206 B50 method in the combination of the two types of thermoplastic resin is 1 ° C. or more. Below 120 ° C,
The composite fiber is an easily split fiber composite fiber, which is a composite molded product obtained by splitting the fiber before melting to express ultrafine fibers. The composite molded product according to any one of claims 1 to 4, wherein the reinforcing fiber is carbon fiber. Claim 1 in which at least two sections constituting the composite fiber are any of a polyolefin-based resin, a polyester-based resin, and a polyamide-based resin, and each include a thermoplastic resin belonging to a different system. The composite molded body according to any one of 5 to 5. The composite molded product according to any one of claims 1 to 6, wherein the composite fiber comprises a section containing polypropylene and a section containing nylon 6. A composite molding base including a reinforcing fiber and a composite molding matrix fiber having two or more kinds of thermoplastic resins having different main components, having three or more sections, and each section is exposed on the fiber surface. It ’s a material,
The fiber for the composite molded body matrix is an easily split fiber composite fiber, and is
When the two or more types of thermoplastic resins are all crystalline resins, the melting point difference measured based on JIS K 7121 in the combination of the two types of thermoplastic resins is 25 ° C. or higher and 150 ° C. or lower.
When at least one of the two or more types of thermoplastic resin is an amorphous resin, the Vicat softening temperature difference measured based on the JIS K 7206 B50 method in the combination of the two types of thermoplastic resin is 1 ° C. or more. Below 120 ° C,
A base material for a composite molded body in which the expression ratio of ultrafine fibers derived from the fibers for the composite molded body matrix exceeds 20% on the surface of the base material for composite molding.
[Measuring method of expression rate of ultrafine fibers]
(1) The surface of the base material is observed with an electron microscope at a magnification of 150 to 200 times, and the enlarged surface is photographed.
(2) Among the fibers present in the photographed image, the number of fibers for the composite molded body matrix having a length of 200 μm or more and the number of fibers derived from the fibers for the composite molded body matrix are counted. Among them, fibers having a fiber length of 150 μm or more and a fiber diameter smaller than 1/2 are defined as ultrafine fibers.
(3) The expression ratio of ultrafine fibers is determined by the following formula.
Expression rate of ultrafine fibers (%) = (number of ultrafine fibers / number of fibers for composite molded matrix) × 100 For composite molded bodies, including reinforcing fibers and thermoplastic resins having two or more different main components, having three or more sections, and each section is exposed on the fiber surface for a composite molded body matrix. It is a base material
The fiber for the composite molded body matrix is an easily split fiber composite fiber, and is
When the two or more types of thermoplastic resins are all crystalline resins, the melting point difference measured based on JIS K 7121 in the combination of the two types of thermoplastic resins is 25 ° C. or higher and 150 ° C. or lower.
When at least one of the two or more types of thermoplastic resin is an amorphous resin, the Vicat softening temperature difference measured based on the JIS K 7206 B50 method in the combination of the two types of thermoplastic resin is 1 ° C. or more. Below 120 ° C,
In the base material, the base material for a composite molded body in which the fiber splitting ratio of the fiber for the composite molded body matrix is 30% or more.
[Measurement method of split fiber ratio]
(1) The base materials are bundled so as not to create a space as much as possible, and cut so that the fiber cross section of the composite molded body matrix fiber can be observed to expose the cross section.
(2) Observe the cross section at a magnification of 400 to 600 times with an electron microscope, and photograph the magnified cross section.
(3) From the captured image, select the split fiber from the fibers derived from the composite molded body matrix fiber (non-split fiber and split fiber). Count the number of sections of split fibers and the number of sections of unsplit fibers.
Non-split fiber: Fiber having a cross-sectional area of 1/2 or more of the cross-sectional area of the fiber that is not split at all Split fiber: From 1/2 of the cross-sectional area of the fiber that is not split at all Fiber with a small cross-sectional area (4) The split fiber ratio is obtained by the following formula.
Split fiber ratio (%) = [Number of split fiber sections / (Number of split fiber sections + Number of unsplit fiber sections)] x 100 At least two sections of the fiber for the composite molded body matrix are one of a polyolefin resin, a polyester resin, and a polyamide resin, and each contains a thermoplastic resin belonging to a different system. , The base material for a composite molded body according to claim 8 or 9. The base material for a composite molded product according to any one of claims 8 to 10, wherein the fiber for the composite molded product matrix comprises a section containing polypropylene and a section containing nylon 6. The base material for a composite molded body according to any one of claims 8 to 11, wherein the reinforcing fiber is a carbon fiber. The base material for a composite molded body according to any one of claims 8 to 12, wherein the base material for the composite molded body is a non-woven fabric. It comprises a reinforcing fiber and a composite molded matrix fiber composed of two or more kinds of thermoplastic resins having different main components, having three or more sections, and each section is exposed on the fiber surface.
When the two or more types of thermoplastic resins are all crystalline resins, the melting point difference measured based on JIS K 7121 in the combination of the two types of thermoplastic resins is 25 ° C. or higher and 150 ° C. or lower.
When at least one of the two or more types of thermoplastic resin is an amorphous resin, the Vicat softening temperature difference measured based on the JIS K 7206 B50 method in the combination of the two types of thermoplastic resin is 1 ° C. or more. Below 120 ° C,
Preparing a composite molded base material in which the expression ratio of ultrafine fibers on the surface of the composite molded base material derived from the composite molded body matrix fibers exceeds 20%, and heating the composite molded base material. Including
When the base material for a composite molded body is heated, the resin having the lowest melting point or Vicat softening temperature among the two or more types of thermoplastic resins is melted and
When the two or more types of thermoplastic resins constituting the composite molded body matrix fiber are all crystalline resins, when the melting point of the thermoplastic resin having the highest melting point is Tm ° C, (Tm-30) ° C. The temperature should be above (Tm + 50) ° C or lower.
When at least one of the two or more types of thermoplastic resins constituting the composite molded body matrix fiber is an amorphous resin, when the Vicat softening temperature of the thermoplastic resin having the highest Vicat softening temperature is VST ° C. , Performed at a temperature of (VST + 20) ° C or higher (VST + 150) ° C or lower,
Including further pressurizing when heating the base material for a composite molded body,
The heating and the pressurization are carried out so that the density of the composite molded product is 90 % or more of the true density.
A method for manufacturing a composite molded product.
[Measuring method of expression rate of ultrafine fibers]
(1) The surface of the base material is observed with an electron microscope at a magnification of 150 to 200 times, and the enlarged surface is photographed.
(2) Among the fibers present in the photographed image, the number of fibers for the composite molded body matrix having a length of 200 μm or more and the number of fibers derived from the fibers for the composite molded body matrix are counted. Among them, fibers having a fiber length of 150 μm or more and a fiber diameter smaller than 1/2 are defined as ultrafine fibers.
(3) The expression ratio of ultrafine fibers is determined by the following formula.
Expression rate of ultrafine fibers (%) = (number of ultrafine fibers / number of fibers for composite molded matrix) × 100 It comprises a reinforcing fiber and a composite molded matrix fiber composed of two or more kinds of thermoplastic resins having different main components, having three or more sections, and each section is exposed on the fiber surface.
When the two or more types of thermoplastic resins are all crystalline resins, the melting point difference measured based on JIS K 7121 in the combination of the two types of thermoplastic resins is 25 ° C. or higher and 150 ° C. or lower.
When at least one of the two or more types of thermoplastic resin is an amorphous resin, the Vicat softening temperature difference measured based on the JIS K 7206 B50 method in the combination of the two types of thermoplastic resin is 1 ° C. or more. Below 120 ° C,
It includes preparing a base material for a composite molded body having a fiber splitting ratio of 30% or more of the fiber for the composite molded body, and heating the base material for the composite molded body.
When the base material for a composite molded body is heated, the resin having the lowest melting point or Vicat softening temperature among the two or more types of thermoplastic resins is melted and
When the two or more types of thermoplastic resins constituting the composite molded fiber for the matrix are all crystalline resins, when the melting point of the thermoplastic resin component having the highest melting point is Tm ° C. (Tm-30). The temperature should be ℃ or higher (Tm + 50) ℃ or lower.
When at least one of the two or more types of thermoplastic resins constituting the composite molded body matrix fiber is an amorphous resin, when the Vicat softening temperature of the thermoplastic resin having the highest Vicat softening temperature is VST ° C. , Performed at a temperature of (VST + 20) ° C or higher (VST + 150) ° C or lower,
Including further pressurizing when heating the base material for a composite molded body,
The heating and the pressurization are carried out so that the density of the composite molded product is 90 % or more of the true density.
A method for manufacturing a composite molded product.
[Measurement method of split fiber ratio]
(1) The base materials are bundled so as not to create a space as much as possible, and cut so that the fiber cross section of the composite molded body matrix fiber can be observed to expose the cross section.
(2) Observe the cross section at a magnification of 400 to 600 times with an electron microscope, and photograph the magnified cross section.
(3) From the captured image, select the split fiber from the fibers derived from the composite molded body matrix fiber (non-split fiber and split fiber). Count the number of sections of split fibers and the number of sections of unsplit fibers.
Non-split fiber: Fiber having a cross-sectional area of 1/2 or more of the cross-sectional area of the fiber that is not split at all Split fiber: From 1/2 of the cross-sectional area of the fiber that is not split at all Fiber with a small cross-sectional area (4) The split fiber ratio is obtained by the following formula.
Split fiber ratio (%) = [Number of split fiber sections / (Number of split fiber sections + Number of unsplit fiber sections)] x 100 An easily split fiber composite fiber having two or more types of thermoplastic resins having different main components, having three or more sections, and having each section of the composite fiber exposed on the fiber surface.
When the two or more types of thermoplastic resins are all crystalline resins, the melting point difference measured based on JIS K 7121 in the combination of the two types of thermoplastic resins is 25 ° C. or higher and 150 ° C. or lower.
When at least one of the two or more types of thermoplastic resin is an amorphous resin, the Vicat softening temperature difference measured based on the JIS K 7206 B50 method in the combination of the two types of thermoplastic resin is 1 ° C. or more. Fiber for composite molded body matrix at 120 ° C. or lower. 16. Claim 16 that at least two sections of the composite molded fiber matrix are any of a polyolefin-based resin, a polyester-based resin, and a polyamide-based resin, and include different types of thermoplastic resins. The fiber for the composite molded body matrix described in 1. The fiber for a composite molded body matrix according to claim 16 or 17, wherein the composite fiber comprises a section containing polypropylene and a section containing nylon 6.

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