JP6835560B2 - Composite material and its manufacturing method - Google Patents

Description

The present invention relates to composite materials and methods for producing them.

Preforms are used as reinforcing materials for composite molded articles used in structural parts such as various machines and automobiles, pressure vessels, and tubular structures.
As a preform which is one of the intermediate materials of the composite material molded body, there is a cloth using a composite yarn in which continuous reinforcing fibers and continuous thermoplastic resin fibers are mixed. Composite yarns are knitted alone or together with other fibers to make knits or woven fabrics, or laminated randomly, and after web production, non-woven fabrics integrated by heat fusion using embossed rolls or entanglement using needle punches. The fabric obtained by knitting is used as an intermediate material. A composite material molded product is obtained by subjecting the obtained fabric-like preform to compression heating or internal pressure heating to melt and mold the thermoplastic resin fibers in the composite yarn contained in the fabric. Further, a composite material molded product can also be obtained by impregnating the obtained preform with a thermosetting resin and then heating under pressure.

Conventionally, for processing a composite material, a technique of injecting an abrasive mixed with water to cut the composite material and a technique using a laser (see Patent Documents 1 and 2) are known.

Japanese Unexamined Patent Publication No. 2011-56583 International Publication No. 2010/11995

However, in the technique of injecting and cutting the abrasive mixed with water, there is a problem that the abrasive adheres to the composite material or the abrasive gets inside and the quality of the composite material is deteriorated. In addition, the technology using a laser has a problem that the cost of the device is high, and when the fiber is cut according to the reinforcing fiber having a high melting point, the thermoplastic resin at the cut end is burnt and the physical properties of the composite material after molding are deteriorated. is there.

The present invention has been made in view of the above problems, and it is intended to provide a composite material capable of obtaining a high-quality composite material molded product having excellent strength and appearance by preventing the cut surface of the composite material from fraying. It is the purpose. Another object of the present invention is to provide a method for producing a composite material, in which the cut surface of the composite material does not fray, the cut surface can be processed, and the quality of the composite material is not deteriorated. ..

As a result of diligent studies, the present inventor has found a method for producing a composite material in which the cut surface is not frayed and the cut surface can be processed by melting and solidifying the cut surface of the composite material composed of continuous reinforcing fibers and a thermoplastic resin. The present invention has been completed.

That is, the composite material of the present invention is a composite material composed of a continuous reinforcing fiber and a thermoplastic resin, and at least one part of the thermoplastic resin on the cut surface of the composite material is melt-solidified and melt-solidified. The molecular weight of the thermoplastic resin is 20% or more of the molecular weight of the thermoplastic resin itself.
The composite material is preferably in the form of a cloth.

The melting point of the continuous reinforcing fiber is preferably 50 ° C. or higher higher than the melting point of the thermoplastic resin.
The continuous reinforcing fiber is preferably at least one selected from the group consisting of glass fiber, carbon fiber, aramid fiber, metal fiber and ceramic fiber.
The thermoplastic resin is selected from the group consisting of polyolefin-based resins, polyamide-based resins, polyester-based resins, polyetherketones, polyetheretherketones, polyethersulphon, polyphenylene sulfide, thermoplastic polyetherimides, and thermoplastic fluororesins. It is preferably at least one type.

The thermoplastic resin may be fibrous.
The continuous reinforcing fiber may be coated with a thermoplastic resin.

The method for producing a composite material of the present invention is a method for producing a composite material composed of a continuous reinforcing fiber having at least one cut surface and a thermoplastic resin, and the cut surface is heated at a temperature equal to or higher than the melting point of the thermoplastic resin. The composite material is cut while melting the thermoplastic resin with a blade having the above, and the melted thermoplastic resin is solidified and formed.

The continuous reinforcing fiber is preferably at least one selected from the group consisting of glass fiber, carbon fiber, aramid fiber, metal fiber and ceramic fiber.
The thermoplastic resin is at least selected from the group consisting of polyolefin resins, polyamide resins, polyester resins, polyetherketones, polyetheretherketones, polyethersulfones, polyphenylene sulfides, thermoplastic polyetherimides and thermoplastic fluororesins. It is preferably one kind.

According to the present invention, it is possible to provide a composite material in which the cut surface does not fray and the cut surface can be processed. Further, it is possible to inexpensively provide a composite material having extremely excellent strength and appearance with less deterioration of the thermoplastic resin on the cut surface.

It is a photograph which shows the sampling place of a cut surface. It is a photograph which shows the cut surface of the cloth of Example 1. It is a photograph which shows the cut surface of the cloth of the comparative example 2.

Hereinafter, the present invention will be described in detail.
The composite material of the present invention is a composite material composed of a continuous reinforcing fiber and a thermoplastic resin, and at least one part of the thermoplastic resin on the cut surface of the composite material is melt-solidified and melt-solidified. The molecular weight of the thermoplastic resin is 20% or more of the molecular weight of the thermoplastic resin itself constituting the composite material.

Examples of the composite material composed of the continuous reinforcing fiber and the thermoplastic resin include a prepreg material and a cloth-like material. The composite material of the present invention has a cut surface, and the cut surface is formed by melting and solidifying at least one part of the thermoplastic resin. The at least a part of the thermoplastic resin on the cut surface is preferably 50% or more, more preferably 80% or more, and most preferably 100% of the thermoplastic resin on the cut surface. The melt solidification of the thermoplastic resin on the cut surface can be confirmed visually, but is preferably confirmed by using energy dispersive X-ray analysis (EDX).

The molecular weight of the melt-solidified thermoplastic resin is measured from a composite material (sample) collected from the cut surface. Specifically, a sample cut out within a thickness region of 500 μm from the surface of the cut surface at an arbitrary position in the central portion of the cut surface (the portion excluding the width of 1 mm from the peripheral edge of the cut surface) is used as a sample. This sample was dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol to remove insoluble continuous reinforcing fibers, and the above 1,1,1,3,3,3-hexafluoro- The molecular weight of the thermoplastic resin dissolved in 2-propanol is measured by a gel permeation chromatography (GPC) apparatus, and is the molecular weight of the melt-solidified thermoplastic resin. Similarly, the molecular weight of the thermoplastic resin itself constituting the composite material can be measured by dissolving it in 1,1,1,3,3,3-hexafluoro-2-propanol with a gel permeation chromatography (GPC) apparatus.

The molecular weight of the thermoplastic resin melted and solidified on the cut surface is 20% or more of the molecular weight of the thermoplastic resin itself constituting the composite material. When it is 20% or more, deterioration of the physical properties of the composite material can be suppressed, and the cut surface can be processed. It is more preferably 40% or more, and further preferably 50% or more.

The composite material of the present invention is composed of continuous reinforcing fibers and a thermoplastic resin.
Since the continuous reinforcing fiber and the thermoplastic resin are continuously and uniformly mixed, and the continuous reinforcing fiber can be uniformly fixed to the thermoplastic resin, the composite material of the present invention is the continuous reinforcing fiber and the continuous thermoplastic resin. It is preferable to include the composite filament of the above.
In addition, by using a composite filament as the composite material, it is excellent in handleability in processes such as knitting and weaving, and the obtained fabric can be made into a composite material molded body that exhibits sufficient mechanical properties even in short-time molding. Is possible.

[Continuous reinforcement fiber]
The melting point of the continuous reinforcing fiber used in the present invention is preferably 50 ° C. or higher higher than the melting point of the thermoplastic resin described later. The melting point is the melting point measured by JIS K0064. Since the melting point of the continuous reinforcing fiber is 50 ° C. or more higher than the melting point of the thermoplastic resin, it is possible to obtain a composite material in which a high-quality composite material molded product having excellent strength and appearance can be obtained. Examples of such continuous reinforcing fibers include at least one selected from the group consisting of glass fibers, carbon fibers, aramid fibers, metal fibers and ceramic fibers. Glass fiber, carbon fiber, and aramid fiber are preferable from the viewpoint of mechanical property, thermal property, and versatility, and glass fiber is more preferable from the viewpoint of price.

The continuous reinforcing fibers are uniformly present in the composite material, especially when the composite material is in the form of cloth, and the thermoplastic resin is melt-solidified by cutting with a blade having a temperature equal to or higher than the melting point of the thermoplastic resin. The continuous reinforcing fibers are fixed and the loosening of the cut surface can be improved.

The number of single threads of the continuous reinforcing fiber is preferably 30 to 15,000 from the viewpoint of openness and handleability in the fiber mixing process.
The continuous reinforcing fiber may be coated with a thermoplastic resin.

〔Thermoplastic resin〕
As the thermoplastic resin used in the present invention, those used for composite materials can be usually used. For example, polyolefin resins such as polyethylene and polypropylene; polyamide resins such as polyamide 6, polyamide 66 and polyamide 46; polyethylene terephthalates. , Polybutylene terephthalate, polytrimethylene terephthalate and other polyester resins; polyoxymethylene and other polyacetal resins; polycarbonate resins; polyether ketones; polyether ether ketones; polyether sulfone; polyphenylene sulfide; thermoplastic polyetherimide; Preferred examples thereof include at least one thermoplastic resin selected from a thermoplastic fluororesin such as a tetrafluoroethylene-ethylene copolymer and a modified thermoplastic resin obtained by modifying them. Among these thermoplastic resins, polyolefin resins, polyamide resins, polyester resins, polyetherketones, polyetheretherketones, polyethersulfones, polyphenylene sulfides, thermoplastic polyetherimides, and thermoplastic fluororesins are preferable. , Polyetherketone resin, modified polyolefin resin, polyamide resin and polyester resin are more preferable from the viewpoint of mechanical properties and versatility, and polyamide resin and polyester resin are further preferable from the viewpoint of thermal properties. Further, the polyamide resin is more preferable from the viewpoint of durability against repeated load, and the polyamide 66 can be preferably used.
The above-mentioned thermoplastic resin may be in the form of fibers obtained by melt spinning.

<Polyester resin>
The polyester-based resin means a polymer compound having a -CO-O- (ester) bond in the main chain. Examples thereof include, but are not limited to, polyethylene terephthalate, polybutylene terephthalate, polytetramethylene terephthalate, poly-1,4-cyclohexylene methylene terephthalate, polyethylene-2,6-naphthalene dicarboxylate and the like. .. The polyester-based resin may be a homopolyester or a copolymerized polyester. In the case of the copolymerized polyester, it is preferable that the third component is appropriately copolymerized with the homopolyester, and the third component includes, for example, a diol component such as diethylene glycol, neopentyl glycol and polyalkylene glycol, adipic acid and sebacic acid. Examples thereof include dicarboxylic acid components such as phthalic acid, isophthalic acid, and 5-sodium sulfoisophthalic acid. Further, a polyester resin using a raw material derived from a biomass resource can also be used. For example, an aliphatic polyester resin such as polylactic acid, polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate and the like can be used. Examples include aromatic polyester resins.

<Polyamide resin>
The polyamide resin means a polymer compound having a -CO-NH- (amide) bond in the main chain. Examples thereof include polyamides obtained by ring-opening polymerization of lactam, polyamides obtained by self-condensation of ω-aminocarboxylic acid, polyamides obtained by condensing diamine and dicarboxylic acid, and copolymers thereof. It is not limited to. As the polyamide, one type may be used alone, or a mixture of two or more types may be used.

The lactam is not particularly limited, and examples thereof include pyrrolidone, caprolactam, undecane lactam, and dodecalactam.
Examples of the ω-aminocarboxylic acid include ω-amino fatty acid, which is a ring-opening compound of lactam with water. Lactam or ω-aminocarboxylic acid may be condensed by using two or more kinds of monomers in combination.

Examples of the diamine (monomer) include linear aliphatic diamines such as hexamethylenediamine and pentamethylenediamine; branched aliphatic diamines such as 2-methylpentanediamine and 2-ethylhexamethylenediamine; p. Aromatic diamines such as −phenylenediamine and m-phenylenediamine; alicyclic diamines such as cyclohexanediamine, cyclopentanediamine and cyclooctanediamine can be mentioned.

Examples of the dicarboxylic acid (monomer) include aliphatic dicarboxylic acids such as adipic acid, pimelic acid and sebacic acid; aromatic dicarboxylic acids such as phthalic acid and isophthalic acid; and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. Can be mentioned.
Diamine and dicarboxylic acid as monomers may be condensed by one kind alone or two or more kinds in combination, respectively.

Examples of the polyamide include polyamide 4 (polyα-pyrrolidone), polyamide 6 (polycaproamide), polyamide 11 (polyundecaneamide), polyamide 12 (polydodecaneamide), and polyamide 46 (polytetramethylene adipamide). Polyamide 66 (polyhexamethylene adipamide), polyamide 610, polyamide 612, polyamide 6T (polyhexamethylene terephthalamide), polyamide 9T (polynonan methylene terephthalamide), and polyamide 6I (polyhexamethylene isophthalamide), and these. Examples thereof include a copolymerized polyamide containing the above as a constituent component.

Examples of the copolymerized polyamide include a copolymer of hexamethylene adipamide and hexamethylene terephthalamide, a copolymer of hexamethylene adipamide and hexamethylene isophthalamide, and hexamethylene terephthalamide and 2-methylpentanediamine terephthal. Examples include copolymers of amides.

The content of the continuous reinforcing fibers in the composite material is preferably 30 to 85% by mass, more preferably 40 to 70% by mass.
When the content of the continuous reinforcing fiber in the composite material is 30% by mass or more, the mechanical strength of the composite material molded product is high and a sufficient reinforcing effect is exhibited. When the content of the continuous reinforcing fibers is 85% by mass or less, the matrix is sufficient, and it is possible to prevent the formation of voids in the composite material molded product.

[Fabric and composite yarn]
The composite material is preferably in the form of a cloth, and the form of the cloth is known, and is not particularly limited, and examples thereof include knitted fabrics and woven fabrics. Since the linearity of the continuous reinforcing fibers in the fabric can be increased and the apparent density of the fabric can be increased, a composite material molded body having excellent mechanical properties can be easily obtained by short-time molding. Therefore, a woven fabric composed of warp and weft. Is preferable.

The woven fabric is composed of warp and weft. It is preferable to use composite yarns in an amount of 50% by mass or more of the fibers constituting the warp. The composite yarn is preferably used in an amount of 70% by mass or more, more preferably 90% by mass or more, still more preferably 100% by mass. From the viewpoint of satisfying mechanical properties such as strength and rigidity at a high level, it is preferable that 50% by mass or more of the fibers constituting the warp yarn is a composite yarn.

Types of warp yarns used in woven fabrics include, for example, (a) strands consisting only of composite yarns of continuous reinforcing fibers and continuous thermoplastic resin fibers, and (b) composite yarns of continuous reinforcing fibers and continuous thermoplastic resin fibers. Examples thereof include strands obtained by twisting or aligning fibers other than composite fibers, and (c) strands composed of fibers other than continuous reinforcing fibers and continuous thermoplastic resin fibers. The strand is a yarn obtained by twisting a bundle of composite yarns untwisted or lightly twisting 100 times / m or less, and it is preferable to use a strand from the viewpoint of increasing the linearity of the fiber, and more preferably the number of twists. It is desirable to use strands having a frequency of 50 times / m or less, particularly preferably 30 times / m or less.

In the case of (b), it is desirable that the composite yarn of the continuous reinforcing fiber and the continuous thermoplastic resin fiber is contained in 50% by mass or more, more preferably 70% by mass or more in one strand. The warp may be composed of at least one selected from (a) and (b), or at least one selected from (a) and (b) and at least one selected from (c). In any case, the composite yarn is used in the total warp yarn of the woven fabric in an amount of 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and further preferably 100% by mass. The fibers other than the composite yarn are not particularly limited as long as the ratio in the total warp yarns is less than 50% by mass, and known fibers can be used depending on the application and purpose. For example, the above-mentioned thermoplastic resin can be used. Examples thereof include the continuous thermoplastic resin fiber used. In particular, fibers of the same type as the continuous thermoplastic resin fibers used for the composite yarn are preferable because they can suppress deterioration of the thermoplastic resin during molding.

The structure of the woven fabric is not particularly limited, and a known structure can be used, but it is flat from the viewpoint of the linearity and weaving efficiency of the warp and weft in the woven fabric and from the viewpoint of high equivalence in the warp and weft directions. Woven fabrics and variable plain woven fabrics are preferred.
A plain woven fabric is a structure in which warp threads and weft threads are alternately interlaced one by one, and has no front and back sides and has high equivalence in the warp and weft directions. As a variable plain woven fabric, a ridged woven fabric in which ridges are formed on the surface by adding crossing points to the top, bottom, left and right of the intersection points of the plain woven fabric, two or more warp threads are commonly interlocked, and two or more weft threads are the same shuttle. An example is a shuttle woven fabric that enters. Further, in order to increase the thickness of the woven fabric, a structure in which a connecting yarn is used as a warp or a weft so as to have a structure in which a plurality of the above-mentioned plain woven fabrics and oblique woven fabrics are stacked may be used to improve work efficiency. ..

In plain woven fabrics, each fiber constituting the warp and weft is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 90% by mass or more, still more preferably 100% by mass as a composite yarn. By doing so, the mechanical properties of the composite material molded body can be improved in both the warp and weft directions. Further, the ratio of the warp density / the weft density is preferably 0.5 to 2.0, more preferably 0.7 to 1.5, from the viewpoint of making the mechanical properties in the warp and weft directions equivalent.

It is preferable that the composite yarn is in a state in which the continuous reinforcing fibers and the continuous thermoplastic resin fibers are continuously and uniformly mixed, and the continuous thermoplastic resin fibers are continuously and substantially uniformly dispersed in the gaps between the continuous reinforcing fibers.

[Manufacturing method of composite thread]
The method for producing the composite yarn is not particularly limited, and a known method of mixing the continuous reinforcing fiber and the continuous thermoplastic resin fiber can be used. For example, after opening the fibers by an external force such as an electrostatic force, a pressure due to fluid spraying, or a pressure pressed against a roller or the like, the continuous reinforcing fibers and the continuous thermoplastic resin fibers are combined and aligned in the opened state. Examples include the method and the fluid interlacing method. The fluid entanglement method is preferable from the viewpoint of suppressing damage to the continuously reinforcing fibers, having excellent fiber opening properties, and being able to mix uniformly. A method of making two or more flow zones almost parallel to the thread axis and guiding the fibers to this zone to make non-bulky threads under tension that does not cause loops or crimps, or only continuous reinforcing fibers. Examples thereof include a method of fluid entanglement after opening fibers or after opening both continuous reinforcing fibers and continuous thermoplastic resin fibers (fluid entanglement method after opening fibers). In particular, it is preferable that the continuous thermoplastic resin fiber is subjected to false twisting by itself in a step including thermal processing, and then continuously mixed by the fluid entanglement method in the same apparatus.

Continuous thermoplastic resin fibers processed alone in a process including thermal processing are continuously combined and pulled with continuous reinforcing fibers that have been opened or not opened, without opening or opening, in the same device. It is preferable to supply them to the fluid entanglement nozzles in a uniform manner because damage to the continuous reinforcing fibers can be suppressed without the vortex turbulence caused by the fluid acting intensively only on the continuous reinforcing fibers. Further, supplying the continuous reinforcing fibers alone or the aligned fibers, preferably the aligned fibers substantially perpendicular to the thread introduction hole surface of the fluid entanglement nozzle, causes the continuous reinforcing fibers to have an extension force due to bending and Damage to the continuous reinforcing fibers can be suppressed without excessive compressive force acting, which is preferable. In particular, when glass fibers, carbon fibers, and ceramic fibers, which are brittle materials, are used as continuous reinforcing fibers, supplying the aligned fibers substantially perpendicular to the thread introduction hole surface of the fluid entanglement nozzle has a damage suppressing effect. Is remarkable and preferable. In addition, when aramid fibers, which are prone to buckling fracture due to compressive force, are used as continuous reinforcing fibers, supplying the aligned fibers substantially perpendicular to the thread introduction hole surface of the fluid entanglement nozzle causes buckling fracture. It can be suppressed and is preferable. Here, substantially perpendicular to the thread introduction hole surface of the fluid entanglement nozzle means a state in which the thread path can be visually confirmed to be vertical.

<Fabrication>
The method for obtaining the fabric is not particularly limited, and a known method for producing an appropriate fabric selected according to the application and purpose can be used. For example, as the woven fabric, a weaving machine such as a shuttle loom, a rapier loom, an air jet loom, or a water jet loom may be used, and at least a part thereof may contain a composite yarn. Preferably, it may be obtained by driving a weft into a warp yarn in which fibers including composite yarns are arranged. The knitting is obtained by knitting fibers containing at least a part of the composite yarn using a knitting machine such as a circular knitting machine, a weft knitting machine, a tricot knitting machine, and a Raschel knitting machine.

[Manufacturing method of composite material]
The method for producing a composite material of the present invention is a method for producing a composite material composed of a continuous reinforcing fiber having at least one cut surface and a thermoplastic resin, and the cut surface is heated at a temperature equal to or higher than the melting point of the thermoplastic resin. The composite material is cut while melting the thermoplastic resin with a blade having the above, and the melted thermoplastic resin is solidified and formed.

In the step of cutting and melting, the composite material is cut while melting the thermoplastic resin by adding a thermal history with a blade having a temperature equal to or higher than the melting point of the thermoplastic resin.
The temperature of the blade is equal to or higher than the melting point of the thermoplastic resin, preferably 50 ° C. higher than the melting point, and more preferably 75 ° C. higher. The temperature of the blade is preferably a melting point of + 150 ° C. or lower from the viewpoint of deterioration of the thermoplastic resin.
Examples of the blade include a Swedish steel blade, a Thomson blade, and a super steel blade, and a material having high hardness and rigidity is preferable.

By cutting the composite material composed of continuous reinforcing fibers and the thermoplastic resin with a blade heated above the melting point of the thermoplastic resin, the composite material is cut and cut while melting the thermoplastic resin. A surface is generated, and the cut surface becomes a cut surface by solidifying the molten thermoplastic resin, whereby a composite material in which the end surface is not loosened can be manufactured.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited to these Examples.

[Example 1]
After arranging glass fiber (fineness 685 dtex x 400 single threads, manufactured by Nippon Electric Glass Co., Ltd.) and polyamide 66 fiber (fineness 470 dtex x 144 single threads, Leona (registered trademark) manufactured by Asahi Kasei Fibers Co., Ltd.) , The fluid was supplied substantially vertically to the fluid entanglement nozzle and fluid entangled under the following conditions to obtain a composite fiber.
・ Fluid confounding nozzle KC-AJI-L manufactured by Kyocera Corporation (1.5 mm diameter, propulsion type)
・ Air pressure 2.5kg / cm ²
・ Processing speed 100m / min or 40m / min
This composite yarn is used as a warp and polyamide 66 fiber (fineness 470 dtex x 144 single yarns, Leona manufactured by Asahi Kasei Fibers Co., Ltd. (registered trademark)) as a weft, and the warp density is 16 / 2.54 cm and the weft density is 18. A cloth having a size of 2.54 cm and a width of 1000 mm was woven.
Next, eight pieces of this fabric were laminated, and heat of 340 ° C. was applied to a Swedish steel blade (single blade 45 °, 2 mm thick) on the board surface of the device (model TCM550A, manufactured by Toko Co., Ltd.), and the lower fulcrum stop time was 0 s. , It was cut using a bake plate as a backing plate.

[Example 2]
Eight pieces of the fabric produced in Example 1 are laminated, and heat of 320 ° C. is applied to a Swedish steel blade (single blade 45 °, 2 mm thickness) on the board surface of the apparatus (model TCM550A, manufactured by Toko Co., Ltd.) to form a lower fulcrum. It was cut using a bake plate as a backing plate with a stop time of 0 s.

[Example 3]
Eight pieces of the cloth produced in Example 1 were laminated, and heat of 320 ° C. was applied to a Thomson blade (0.2 mm thick) on the board surface of the apparatus (model TCM550A, manufactured by Toko Co., Ltd.), and the lower fulcrum stop time was 8 s. , It was cut using a bake plate as a backing plate.

[Comparative Example 1]
Eight pieces of the fabric produced in Example 1 are laminated, and the lower fulcrum is stopped on the board surface of the apparatus (model TCM550A, manufactured by Toko Co., Ltd.) without applying heat to the Swedish steel blade (single blade 45 °, 2 mm thick). For 0 s, a baking plate was used as a backing plate for cutting.

[Comparative Example 2]
Eight pieces of the cloth produced in Example 1 were laminated and cut with an SPL3905 / SSL400 manufactured by Musashino Kikai Co., Ltd. at an output of 400 W.

A sample cut out from a region having a thickness of 500 μm from the surface, which is a region shown in FIG. 1 of the cut surfaces of Examples and Comparative Examples (cut surface in the case of Comparative Example 1), is 1,1,1,3,3,3. A thermoplastic resin in a state of being dissolved in 3-hexafluoro-2-propanol to remove insoluble continuous reinforcing fibers and dissolved in the above 1,1,1,3,3,3-hexafluoro-2-propanol. The molecular weight was measured using gel permeation chromatography. The rate of decrease in the molecular weight of the cut surface was measured with the molecular weight Mn other than the cut surface as 100%. Table 1 shows the cutting conditions and the like. In addition, the number of laminated sheets in Table 1 indicates how many sheets were laminated before cutting, and the number of laminated layers and fixed number indicates how many of the sheets laminated before cutting were fixed by cutting.

As shown in Table 1, the cloth (composite material) produced by the production method of the present invention has the molecular weight of the thermoplastic resin melted and solidified with respect to the molecular weight of the thermoplastic resin itself (described as the molecular weight retention rate in Table 1). Was as high as 60% or more, the thermoplastic resin was melt-solidified, and the deterioration of the physical properties of the fabric near the cut surface was suppressed. In Example 2, since the blade temperature was lower than that in Example 1, the number of laminated fixed sheets was 7, but as shown in Example 3, the lower fulcrum stop time is lengthened even if the blade temperature is lowered. By doing so, all the layers were fixed. FIG. 2 is a photograph showing the cut surface of the fabric of Example 1, and it can be seen that the cut surface does not fray and is not burnt. On the other hand, in Comparative Example 1 in which the thermoplastic resin was not melt-solidified, the cut surface was frayed. Further, as shown in Comparative Example 2, the one cut by the laser had a low molecular weight retention rate of 18%, and the physical properties of the composite material were deteriorated. FIG. 3 is a photograph showing the cut surface of the fabric of Comparative Example 2, and it can be seen that the cut surface is not frayed but is burnt.

The composite material of the present invention can be used as a material for a resin composite material molded product that requires a high level of mechanical properties, such as structural parts of various machines and automobiles, pressure vessels, and tubular structures.

Claims (3)

A method for producing a composite material composed of a continuous reinforcing fiber having at least one cut surface and a thermoplastic resin, wherein the cut surface is formed on the cut surface by a blade having a temperature equal to or higher than the melting point of the thermoplastic resin. A method for producing a composite material, which is formed by cutting the composite material while melting the melted thermoplastic resin and solidifying the melted thermoplastic resin. The continuous reinforcing fibers are glass fibers, the production method of carbon fiber, aramid fiber, composite material according to claim 1, wherein at least one selected from the group consisting of metal fibers and ceramic fibers. The thermoplastic resin is selected from the group consisting of a polyolefin resin, a polyamide resin, a polyester resin, a polyether ketone, a polyether ether ketone, a polyether sulfone, a polyphenylene sulfide, a thermoplastic polyetherimide, and a thermoplastic fluorine resin. The method for producing a composite material according to claim 1 or 2, which is at least one type.