JP2021120196A - Joint structure - Google Patents

Abstract

To provide a joint structure having high joint strength and thermal shock resistance.SOLUTION: A joint structure according to one embodiment of the present invention has a first member 1 that is a processed metal having at least one of projections 4 and perforations 5 formed on the surface, and a second member 2 including fibrillated carbon fibers 3 and thermoplastic resin, the second member 2 joined to the first member through at least one of the perforations and the projection.SELECTED DRAWING: Figure 1

Description

The present invention relates to a bonded structure of a carbon fiber composite resin and a metal.

Thermoplastic carbon fiber composite resin (CFRTP) has rigidity that can replace metals such as aluminum alloys, and is lightweight because it contains carbon fibers, so it is used for structural materials for aircraft and automobiles, sporting goods, etc. ing. Since CFRTP is thermoplastic, it can be molded by an injection molding machine. Therefore, CFRTP can realize improvement in productivity and improvement in shape freedom as compared with the conventional thermosetting carbon fiber composite resin.

In CFRTP, some metals are used in parts where the material strength is insufficient. In that case, bonding of CFRTP and metal is required.

As a joining method, a method using an adhesive is generally mentioned. However, in order to withstand the shear stress caused by the difference in thermal expansion of the material, the adhesive that can be used is limited to the elastic adhesive. On the other hand, elastic adhesives are swellable and degradable, which can make it difficult to maintain a bond. Therefore, a means for joining without using an adhesive has been desired.

For example, in Patent Document 1, a step of making the surface of an aluminum alloy shaped object covered with ultrafine recesses having a specific diameter and chemically adsorbing amine-based molecules, and an injection molding metal for the aluminum alloy shaped object. A step of inserting into a mold and injecting a specific resin or resin composition to prepare an injection joint, and a FRTP prepreg or a FRTP prepreg containing the injection joint in a hot press mold and containing a specific matrix resin on the injection joint. A method for producing a composite of metal and FRTP, which comprises a step of laminating and loading FRTP molded products and a hot pressing step of heat-sealing the resins to each other, is disclosed.

Further, in Patent Document 2, a step of forming a perforated portion having an opening by irradiating the surface of the first member with a laser having a period of 15 ns or less, in which one pulse is composed of a plurality of sub-pulses, and a step of forming a perforated portion in the perforated portion. Disclosed is a method for manufacturing a bonded structure, which comprises a step of filling and solidifying the two members.

In addition, Non-Patent Document 1 describes that CFRTP and metal are mechanically bonded by ultrasonic bonding.

Japanese Unexamined Patent Publication No. 2016-60051 Japanese Unexamined Patent Publication No. 2016-43382

Balle et al., Ultrasonic spot welding of aluminum sheet / carbon fiber reinforced polymer joints, Materialwissenschaft und Werkstofftechnik, Vol. 38, Issue 11, p. 934-938, 2007

The method for producing a complex described in Patent Document 1 is said to have a strong adhesive force between a metal portion and a resin portion, and to ensure product stability even in mass production.

However, in the invention described in Patent Document 1, when forming a rough surface on a metal surface, the shape of the unevenness of the rough surface cannot be controlled. Therefore, even after the subsequent bonding treatment by NMT (Nano Molding Tech.), The joint surface has an uncontrolled irregular surface shape. As a result, the anchor effect at the time of joining will vary. Therefore, when processed into a complicated joint shape that matches the actual product, many points where stress is concentrated occur on the joint surface, and due to the heat shrinkage stress after molding and the repeated stress amplitude by the thermal shock test, Peeling may occur at the point where the stress is concentrated.

The method for manufacturing a bonded structure described in Patent Document 2 is said to be able to realize a stronger metal-resin bonding by utilizing the anchor effect generated between the resin and the perforation. However, when a thermoplastic carbon fiber composite resin is used as the resin, the carbon fibers are usually not sufficiently defibrated, so that the entanglement effect between the carbon fibers and the perforations does not occur, which is improved from the viewpoint of the joint strength at the joint. There was room for.

Further, since the processing method is limited to the sub-pulse laser and the shape of the perforation is also limited, there is room for improvement from the viewpoint of processability.

Further, the bonded body described in Non-Patent Document 1 is obtained by directly bonding CFRTP and a metal by ultrasonic bonding, but there is room for improvement in shear strength.

One aspect of the present invention has been made in view of such circumstances, and an object of the present invention is to provide a bonded structure having high bonding strength and thermal shock resistance.

The present invention employs the following configuration in order to solve the above-mentioned problems.

That is, the bonded structure according to one aspect of the present invention is a first member which is a metal processed product in which at least one of protrusions and perforations is formed on the surface, a thermoplastic resin, and defibrated fibers in the thermoplastic resin. It includes a carbon fiber dispersed in a plasticized state, and includes a second member joined to the first member via at least one of the protrusion and the perforation.

According to the above configuration, the protrusions of the metal work piece of the first member bite into the thermoplastic resin of the second member, or the perforation of the metal work piece of the first member is filled with the thermoplastic resin of the second member. As a result, the first member and the second member are joined. In addition, the defibrated carbon fibers contained in the second member are entangled with the protrusions or perforations of the metalwork of the first member. This creates a filler effect due to the carbon fibers at the joint and an anchor effect on the protrusions or perforations. Therefore, even when stress is applied, a strong bond can be maintained between the first member and the second member. Further, since a large number of protrusions or perforations are formed in the first member and the carbon fibers of the second member are defibrated, the shear stress at the joint can be dispersed and the stress concentration can be suppressed. Therefore, the bonded structure is resistant to repeated thermal shocks. Therefore, as compared with the prior art, one aspect of the present invention provides a bonded structure that is more firmly bonded and has high thermal shock resistance.

As used herein, the term "defibrated state" means a state in which carbon fibers existing alone are contained, not in agglomerated bundles. Not all carbon fibers need to be present alone. The proportion of carbon fibers present alone can be defined as the defibration rate described below. Also, as used herein, the term "entangled" with carbon fibers with protrusions or perforations means that at least a portion of the carbon fibers is inserted between the protrusions or into the perforations.

In the bonded structure according to the above one aspect, the defibration rate of the carbon fiber derived from the following formula may be 50% or more. This configuration increases the proportion of carbon fibers that are entangled with the protrusions or perforations. Therefore, a more firmly joined joint structure can be obtained.
Defibrillation rate (%) = (number of carbon fibers existing alone) / (total number of carbon fibers) x 100
In the joint structure according to the one side surface, the distance between the protrusions may be 5 to 150 μm. According to this configuration, the anchor effect is likely to be exhibited. As used herein, the term "protrusion spacing" means the distance at which the contour lines of the protrusions first come into contact with the contour lines of other adjacent protrusions when the contour lines of the protrusions are expanded equidistantly when viewed from the tip end side of the protrusions. Further, in the present specification, the “tip of the protrusion” means a portion of the protrusion that first comes into contact with the plane when the plane is brought closer from the side where the protrusion protrudes.

In the joint structure according to the one side surface, the width of the protrusion may be 10 to 200 μm. According to this configuration, the anchor effect is likely to be exhibited. In the present specification, the "protrusion width" means the maximum ferret diameter of the protrusion contour line seen from the tip side of the protrusion.

In the joint structure according to the one side surface, the height of the protrusion may be 15 μm or more. According to this configuration, the anchor effect is likely to be exhibited. As used herein, the "protrusion height" means the distance from the tip to the base of the protrusion.

In the joint structure according to the one side surface, the opening diameter of the perforation may be 5 μm or more and 150 μm or less. According to this configuration, the joining strength of the joining structure is improved. As used herein, the "perforation opening diameter" means the minimum ferret diameter at the perforation opening. Further, in the present specification, the "perforation opening" means that there is no non-metal part on the surface of the metal work piece that first comes into contact with the flat surface when the flat surface is approached from the side where the perforation is open, that is, no metal. Means a part.

In the joint structure according to the one side surface, the depth of the perforation may be 15 μm or more. According to this configuration, the joining strength of the joining structure is improved. As used herein, the "perforation depth" means the distance from the opening to the bottom of the perforation.

The method for manufacturing the bonded structure according to the above one side is a step of forming at least one of protrusions and perforations on the surface of the metal material to obtain the first member, and carbon fibers in the thermoplastic resin by an internal feedback screw. Is included in a step of obtaining a second member by dispersing the fibers in a defibrated state, that is, a step of obtaining a second member by high shearing, and a step of joining the first member and the second member. According to the manufacturing method, since the carbon fibers are contained in the second member in a defibrated state, the bonding strength is improved.

According to one aspect of the present invention, it is possible to provide a bonded structure having high bonding strength and thermal shock resistance.

FIG. 1 schematically illustrates an example of a cross section of the joint structure according to the embodiment. FIG. 2 schematically shows a method of laser irradiation for forming a protrusion according to an embodiment. FIG. 3 schematically shows a laser-machined portion of the first member according to the embodiment. FIG. 4 schematically shows a method of a tensile test according to an example. FIG. 5 schematically shows an example of a protrusion of the first member according to the embodiment. FIG. 6 schematically shows an example of a protrusion of the first member according to the embodiment. FIG. 7 schematically shows an example of a protrusion of the first member according to the embodiment. FIG. 8 schematically shows an example of a protrusion of the first member according to the embodiment. FIG. 9 schematically shows an example of a protrusion of the first member according to the embodiment. FIG. 10 schematically shows an example of drilling the first member according to the embodiment. FIG. 11 schematically shows an example of perforation at the time of the first part according to the embodiment. FIG. 12 schematically shows an example of the arrangement of the protrusions of the first member according to the embodiment. FIG. 13 schematically shows an example of the arrangement of the protrusions of the first member according to the embodiment. FIG. 14 schematically shows an example of the arrangement of the protrusions of the first member according to the embodiment. FIG. 15 schematically shows an example of a protrusion of the first member according to the embodiment. FIG. 16 schematically shows an example of a protrusion of the first member according to the embodiment. FIG. 17 schematically shows an example of drilling the first member according to the embodiment. FIG. 18 schematically shows an example of drilling the first member according to the embodiment.

Hereinafter, embodiments according to one aspect of the present invention (hereinafter, also referred to as “the present embodiment”) will be described with reference to the drawings.

§1 Application example First, the outline of the bonded structure according to one aspect of the present invention will be described with reference to FIG. FIG. 1 schematically illustrates an example of a cross section of the bonded structure according to one aspect.

In FIG. 1, two types of bonded structures 101 and 102 are illustrated. First, the joint structure 101 will be described. The joint structure 101 comprises a first member 1 which is a metal processed product having protrusions 3 formed on its surface, and carbon fibers 5 and a thermoplastic resin which are joined to the first member 1 via the protrusions 3. A second member 2 including the second member 2 is provided.

In the bonded structure 101, the thermoplastic resin of the second member 2 is solidified so as to wrap around the protrusions 3 formed on the first member 1, and in addition, the carbon fibers 5 contained in the second member 2 and the protrusions 3 Because they are entwined and joined, a physically strong anchor effect can be obtained. Therefore, it is possible to provide a bonded structure that exhibits high bonding strength.

Next, the joint structure 102 will be described. The bonding structure 102 comprises a first member 1 which is a metal processed product having perforations 4 formed on its surface, and carbon fibers 5 and a thermoplastic resin which are bonded to the first member 1 through the perforations 4. A second member 2 including the second member 2 is provided.

In the bonded structure 102, the thermoplastic resin of the second member 2 is solidified so as to be filled in the perforations 4 formed in the first member 1, and in addition, at least one of the carbon fibers 5 contained in the second member 2 is contained. Since the portion is inserted into the perforation 4, a physically strong anchor effect can be obtained. As a result, it is possible to provide a bonded structure that exhibits high bonding strength.

Further, in these bonded structures, the carbon fibers are dispersed in the thermoplastic resin in a defibrated state. Carbon fibers are generally not sufficiently defibrated. When the carbon fibers are not defibrated and exist in a bundled state, the carbon fibers themselves have high rigidity, so that the bundles of carbon fibers can hinder the joining of the first member and the second member by the protrusions or the perforations. By defibrating the carbon fibers, the carbon fibers are sufficiently entangled with the protrusions or perforations, and the bonding strength of the bonding structure is improved.

§2 Configuration example <First member>
The first member is a metalwork, with protrusions, perforations, or both. Examples of the material of the metal processed product include iron-based metal, stainless-based metal, copper-based metal, aluminum-based metal, magnesium-based metal, and alloys thereof. Further, the metal processed product may be a metal molded product, zinc die-cast, aluminum die-cast, powder metallurgy, or the like.

<Protrusion>
The protrusions are formed on the surface of the first member. When the first member is provided with a protrusion, an anchor effect via the protrusion can be obtained between the first member and the second member. Further, when the second member contains carbon fiber, an entanglement effect can be obtained between the second member and the protrusion. Therefore, the joint strength is improved.

The protrusion is preferably formed integrally with the first member. That is, it is preferable that the protrusion formed as a member different from the first member is not attached to the surface of the first member. As a result, the joint strength is improved as compared with the case where the protrusion is attached to the first member.

The protrusions are preferably aligned. As used herein, the term "aligned protrusions" means regularly arranged protrusions. As a result, the strength of the entire joint structure is stabilized.

The distance between the protrusions is preferably 5 μm or more and 150 μm or less, more preferably 20 μm or more and 100 μm or less. When the distance between the protrusions is 5 μm or more, the carbon fibers are easily entangled with the protrusions, and the bondability is improved. Further, when it is 150 μm or less, the number of protrusions per unit area increases, and the anchor effect and the entanglement effect are improved.

The width of the protrusion is preferably 10 μm or more and 200 μm or less, and more preferably 10 μm or more and 100 μm or less. When the width of the protrusion is 10 μm or more, the protrusion can be easily formed. When the width of the protrusions is 200 μm or less, the number of protrusions per unit area increases, and the anchor effect and the entanglement effect are improved.

The height of the protrusion is preferably 15 μm or more, more preferably 20 μm or more. When the height of the protrusion is 15 μm or more, the anchor effect and the entanglement effect are improved. The upper limit of the height of the protrusion is not particularly limited, but if it is 300 μm or less, the processing time can be shortened, which is preferable.

The shape of the protrusion is not particularly limited. For example, the protrusion may have a constant diameter of the cross section perpendicular to the height direction, and at least one of a region in which the diameter of the cross section perpendicular to the height direction expands and contracts from the tip to the base of the protrusion. It may have either one. In particular, when the protrusion has a region in which the diameter of the cross section perpendicular to the height direction decreases from the tip of the protrusion toward the base, the vertical peeling strength is excellent. Further, the shape of the tip of the protrusion is not particularly limited, and may be branched.

5 to 9 and 15 to 16 schematically show an example of a protrusion. The protrusion 3 shown in FIG. 5 includes a region 22 in which the diameter of the cross section perpendicular to the height direction expands from the tip of the protrusion toward the base, and then decreases. The protrusion 3 shown in FIG. 6 includes a region 21 in which the diameter of the cross section perpendicular to the height direction expands next to the region 22 in which the diameter of the cross section decreases from the tip of the protrusion toward the base. Further, the protrusion 3 shown in FIG. 7 includes only a region 22 in which the diameter of the cross section perpendicular to the height direction is reduced from the tip to the base of the protrusion. The protrusion 3 shown in FIG. 8 includes only a region 21 in which the diameter of the cross section perpendicular to the height direction expands from the tip to the base of the protrusion. In the protrusion 3 shown in FIG. 9, the diameter of the cross section perpendicular to the height direction is constant from the tip to the base of the protrusion. The protrusion 3 shown in FIG. 15 is branched on the tip end side of the protrusion. The distance between the protrusions in this case means the portion indicated by the arrow 31 shown in FIG. 15, and does not include the distance between the branches existing on the tip side of the protrusion. In the protrusion 3 shown in FIG. 16, the branch at the tip of the protrusion reaches the base. If the distance between the branches is less than 5 μm, the entire branch may be regarded as one protrusion. That is, the distance between the protrusions in this case means the portion indicated by the arrow 31 shown in FIG. 16, and does not include the distance between branches. Further, the protrusions having a plurality of shapes may be partially used. That is, for example, the shape shown in FIG. 5 and the shape shown in FIG. 6 may coexist.

As described above, one large protrusion may be provided with a plurality of small branches. Further, since the branch reaches the base, a plurality of protrusions may appear to be in close contact with each other. However, it is preferable that the protrusions are independent. As used herein, the term "independent protrusions" means that the contour lines of the protrusions do not overlap or touch each other when viewed from the tip of the protrusions, and the boundaries between the protrusions are clear. That is, it is preferable to have only one tip and only one base for each protrusion. As a result, the number of protrusions 3 and carbon fibers 5 that contribute to the bonding can be maximized, so that the anchor effect with the thermoplastic resin contained in the second member and the entanglement effect with the carbon fibers are improved, and the bonding is performed. Improves sex.

The arrangement of the protrusions is not particularly limited. 12 to 14 schematically show an example of the arrangement of protrusions. In FIGS. 12 to 14, for convenience, the shape in which the tips of the protrusions are connected is shown by a thick line. The arrangement of the protrusions as seen from the tip side of the protrusions may be, for example, a quadrangular shape as shown in FIG. 12, a triangular shape as shown in FIG. 13, or a hexagonal shape as shown in FIG. good.

In the present specification, when the arrangement of protrusions is "square", it means that the arrangement of protrusions is a grid type. As used herein, the "triangular" arrangement of protrusions means that the arrangement of protrusions is closest packed. Further, in the present specification, the arrangement of the protrusions is "hexagonal" means that the arrangement of the protrusions is a hexagonal shape. In addition, a plurality of types of arrays may be partially used. That is, for example, the sequence shown in FIG. 12 and the sequence shown in FIG. 13 may coexist.

<Perforation>
The perforations are formed on the surface of the first member. Since the first member is formed with a perforation, an anchor effect through the perforation can be obtained between the first member and the second member. Further, since the second member contains carbon fiber, an entanglement effect can be obtained with the perforation. Therefore, the joint strength is improved.

FIG. 10 schematically illustrates an example of drilling the first member according to the embodiment. As shown in FIG. 10, the first member 1 preferably has perforations that are independent of each other. That is, when viewed from a direction perpendicular to the surface on which the perforations are formed, it is preferable that the openings of the perforations do not overlap and the boundary line between the perforations is clear. The perforation is different from a continuous groove. If the perforations are independent, the number of perforations 4 and carbon fibers 5 that contribute to bonding can be maximized, and the anchor effect with the thermoplastic resin contained in the second member and the entanglement effect with the carbon fibers 5 can be maximized. Is improved, and the bondability is improved.

The opening diameter of the perforation is preferably 5 to 150 μm, more preferably 10 to 100 μm. When the opening diameter is 5 μm or more, the entanglement effect with carbon fibers is improved. Further, when the opening diameter is 150 μm or less, the number of holes per unit area increases, and the anchor effect and the entanglement effect are improved.

The depth of the perforation is preferably 15 μm or more, more preferably 20 μm or more. When the depth is 15 μm or more, the anchor effect and the entanglement effect in drilling are improved, and as a result, the overall joint strength is improved. The upper limit of the drilling depth is not particularly limited, but if it is 300 μm or less, the processing time can be shortened, which is preferable.

Further, it is preferable that the perforations are aligned. As used herein, "aligned perforations" means regularly arranged perforations. As a result, the strength of the entire joint structure is stabilized. The arrangement of the perforations is not particularly limited, and an arrangement similar to that of the protrusions can be used. Further, similarly to the above-mentioned protrusions, it is also possible to coexist a plurality of types of sequences. In addition, perforations having different opening diameters may coexist.

The shape of the perforation is not particularly limited. For example, the perforation may have a constant diameter of the cross section perpendicular to the depth direction, and the diameter of the cross section perpendicular to the depth direction is at least one of an area where the diameter expands from the opening toward the bottom and a region where the diameter decreases. You may have one.

10 to 11 and 17 to 18 schematically illustrate an example of perforation. For example, as shown in FIG. 10, the shape may include a region in which the diameter of the cross section perpendicular to the depth direction of the perforation decreases, and then a region in which the diameter expands. The diameter inside the perforation shown in FIG. 11 may be substantially constant. The shape may be such that a plurality of small perforations are provided inside the perforations shown in FIG. 17, or the shape may be such that the plurality of perforations shown in FIG. 18 overlap. However, it is more preferable that the perforations are independent as described above, rather than the perforations being superposed. Further, the perforations having a plurality of shapes may be partially used. That is, for example, the shape shown in FIG. 10 and the shape shown in FIG. 11 may coexist.

<Second member>
The second member contains a thermoplastic resin and carbon fibers. It can be said that the second member contains a carbon fiber composite resin.

Materials for the thermoplastic resin include PVC (polyvinylidene chloride), PS (polystyrene), AS (acrylonitrile styrene), ABS (acrylonitrile butadiene styrene), PMMA (polymethyl methacrylate), PE (polyethylene), PP ( Polypropylene), PC (polypropylene), m-PPE (modified polyvinylidene ether), PA6 (polyvinylidene 6), PA66 (polyethylene 66), POM (polyacetylate), PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PSF (polysulfone) ), PAR (Polyarylate), PEI (Polyetherimide), PPS (Polyphenylidene Sulfide), PES (Polyethersulfone), PEEK (Polyetheretherketone), PAI (Polyethyleneimide), LCP (Liquid crystal polymer), PVDC (Polyvinylidene chloride), PTFE (polytetrafluoroethylene), PCTFE (polychlorotrifluoroethylene), and PVDF (polyvinylidene fluoride). The thermoplastic resin may be TPE (thermoplastic elastomer), and examples of TPE include TPO (olefin-based), TPS (styrene-based), TPEE (ester-based), TPU (urethane-based), and TPA. (Nylon type) and TPVC (vinyl chloride type) can be mentioned. Among the above, a thermoplastic resin having crystallinity is preferable from the viewpoint of material strength.

The second member may contain an additive other than the thermoplastic resin and the carbon fiber, if necessary, as long as the above-mentioned effects are not impaired. Examples of additives include sizing agents, dispersants, antioxidants, ultraviolet absorbers, antistatic agents, flame retardants, lubricants, and crystal nucleating materials for enhancing the affinity between the carbon fibers and the thermoplastic resin. Examples include plasticizers, dyes, pigments, carbon nanotubes and the like.

It is preferable to use a layered silicate as the crystal nucleating material for the purpose of improving the material strength of the second member. In the layered silicate, a tetrahedron in which Si is surrounded by four oxygens forms a two-dimensionally expanded structural unit (tetrahedron sheet) by sharing three vertices with the adjacent tetrahedron. It is a group of silicates with a layered structure. Further, a part of Si may be replaced with Al. Examples of the silicate include mica, mica, talc, kaolin, montmorillonite and the like. Further, an octahedral sheet, which is a two-dimensional connection of octahedrons in which Mg, Al, etc. are surrounded by six oxygens or OHs in addition to Si, is also a crystal nucleating agent. The octahedral sheet has a complete cleavage parallel to the layer surface and is generally in the form of a plate or flakes. The octahedral sheet is chemically a hydrous silicate containing Al, Mg, Fe, alkali and the like in addition to Si. Commercially available products can be used for both.

<Carbon fiber>
Carbon fiber is a filler that imparts strength to the second member. Carbon fibers are obtained, for example, by carbonizing organic polymer fibers by stepwise heat treatment at 800 ° C. or higher and 3000 ° C. or lower while maintaining the fiber shape, or by heat-treating the spun pitch. Examples of organic polymer fibers include cellulosic and polyacrylonitrile. Further, as the carbon fiber, a commercially available product may be used. The carbon fiber may be a new material or a recycled material. As the recycled material, carbon fibers regenerated by a thermal decomposition method, a chemical dissolution method, or a supercritical fluid method in which the resin component is separated from the carbon fiber reinforced plastic (CFRP) and the carbon fibers are recovered may be used. ..

The carbon fiber can be appropriately selected depending on the thermoplastic resin. Examples of carbon fibers include, but are not limited to, SIGRAFIL CC6-4.0 / 240-T190 (manufactured by SGL carbon), SIGRAFIL CC6-4.0 / 240-T130 (manufactured by SGL carbon), and HT C413 (manufactured by SGL carbon). Examples include Toho Tenax), IM C702 (Toho Tenax), TR06NE (Mitsubishi Rayon), MR06NE (Mitsubishi Rayon) and the like.

The weight ratio (carbon fiber: thermoplastic resin) of the thermoplastic resin to the carbon fiber in the second member is preferably 10:90 to 60:40, and more preferably 20:80 to 40: It is 60. When the ratio of carbon fibers is 10% by weight or more, the mechanical strength of the second member is improved. When the ratio of the carbon fibers is 60% by weight or less, the uneven mixing of the carbon fibers and the thermoplastic resin is reduced in the melt-kneading step, so that the mechanical strength of the second member is improved.

The fiber length of the carbon fibers is not particularly limited, but is preferably 50 mm or less from the viewpoint of dispersibility in the thermoplastic resin, and more preferably from the viewpoint of dispersibility of the carbon fibers in the resin. Is 5 mm or less. Further, from the viewpoint of the mechanical strength (tensile strength or bending strength) of the composite resin, 0.1 mm or more is preferable. The fiber length of the carbon fiber does not have to be constant and may vary. In that case, carbon fibers having a fiber length outside the preferable range described above may be contained.

The defibration rate of the carbon fiber is calculated from the following formula, and is preferably 50% or more, more preferably 80% or more. When the defibration rate is 50% or more, the number of carbon fibers entwined with the protrusions or the perforations increases, and the bonding strength of the bonding structure is improved.
Defibrillation rate (%) = (number of carbon fibers existing alone) / (number of carbon fibers) x 100
The upper limit of the defibration rate is not particularly limited and may be 100%.

<Manufacturing method of joint structure>
The bonded structure is, for example, in a state in which at least one of protrusions and perforations is formed on the surface of a metal material to obtain a first member, and carbon fibers are defibrated in a thermoplastic resin by an internal feedback screw. It is obtained by a manufacturing method including a step of obtaining a second member by dispersing in and a step of joining the first member and the second member.

The method of forming the protrusions or perforations of the first member is not particularly limited, and may be performed by laser processing, chemical etching, electric discharge machining, ultra-precision mold, fine cutting, or the like.

Examples of the laser used for forming the protrusion or the perforation include a fiber laser, a YAG laser, a YVO4 laser, a semiconductor laser, a carbon dioxide gas laser, an excimer laser and the like. A pulse laser is suitable for forming a protrusion having a region where the diameter of the outer peripheral portion decreases from the tip of the protrusion toward the base, and a continuous wave laser may be used in other cases. As the pulse laser, a sub-pulse laser is more preferable.

FIG. 2 schematically shows a method of laser irradiation for forming a protrusion according to an embodiment. By laser processing the metal material so that the laser irradiation portion 11 shown in FIG. 2 partially overlaps with the metal material, the laser non-irradiation portion 13 becomes an independent protrusion. In FIG. 2, the region where the laser irradiation unit overlaps is shown as the laser irradiation superimposing unit 12.

The second member is manufactured, for example, as follows. First, carbon fibers are added to the thermoplastic resin and kneaded. Here, by kneading under shearing conditions, the carbon fibers can be dispersed in a defibrated state. A normal twin-screw extruder may be used, but a high shearing machine having an internal feedback type screw is preferably used for kneading.

The internal feedback type screw is provided in the cylinder. By repeating the following steps 1 and 2, the molten resin composition containing the thermoplastic resin and the carbon fibers is kneaded.
1. 1. The rotation of the screw pushes the molten resin composition to the front of the cylinder.
2. The molten resin composition returns to the rear of the cylinder through a passage provided in the axial direction of the screw.

As a result, a strong shear flow field and extension field are generated inside the molten resin composition, so that the defibration of the carbon fibers is promoted. The rotation speed of the internal feedback type screw is preferably 200 rpm or more and 3000 rpm or less. The shear rate is preferably 300 / s or more and 4500 / s or less. The time for circulating the molten resin composition is preferably 10 seconds or more and 8 minutes or less.

Then, the second member can be obtained by molding the obtained molten resin composition. A general injection molding method can be used for molding.

Examples of the method for joining the first member and the second member include laser joining, injection molding joining, ultrasonic welding, heat press welding, IH heating, and 3D printer lamination.

Laser bonding is performed, for example, as follows. The processed portion of the first member is irradiated with a laser while pressing the second member, and the second member is melted by heat. The laser irradiates from the first member side. After that, when the laser irradiation was stopped, the first member and the second member were joined by solidifying the second member in a state where the carbon fibers contained in the second member were cooled and the protrusions or perforations were entangled with each other. A joined structure is obtained.

When performing laser bonding, the laser irradiation surface of the first member may be rough-processed with the same type of laser marker for the purpose of improving the laser absorption efficiency of the first member. Further, the method for improving the laser absorption efficiency of metal is not limited to the laser marker, and rough processing with sandpaper, blackbody spray, or the like may be performed.

Injection molding joining is performed using, for example, an electric injection molding machine. Specifically, by inserting the first member into a mold installed in the molding machine and filling the mold with a molten resin, the second member can be molded to obtain a bonded structure.

Ultrasonic welding is performed by superimposing the first member and the second member via a joint and installing the first member and the second member on a device for ultrasonic welding. Ultrasonic welding is performed through a horn for ultrasonic welding to obtain a bonded structure.

Hot press bonding is performed by superimposing the first member and the second member via a joint and installing the first member and the second member on a device for hot pressing or a mold. Heat and pressure are applied from the second member side to join them to obtain a joined structure.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to the following Examples.

[Evaluation of carbon fiber defibration rate]
The carbon fiber composite resin used for the second member was diluted 10 to 30 times by melt-kneading together with the same type of thermoplastic resin containing no carbon fiber. Specifically, using a lab plast mill (manufactured by Toyo Seiki Seisakusho Co., Ltd.), the mixture of the carbon fiber composite resin and the thermoplastic resin is heated to a temperature higher than the melting temperature of the thermoplastic resin, and the rotation speed is increased to several tens of rpm. It was diluted by setting the degree and kneading. By controlling the rotation speed in this way, the shear stress on the resin was suppressed and the defibrated state of the carbon fibers did not change. From the diluted resin, a sheet sample having a size of 50 mm × 50 mm and a thickness of about 0.2 mm was prepared using a heating press machine. Arbitrary three points of the sheet sample were observed with an optical microscope in a field of view of Φ5 mm, and the number of carbon fibers existing alone and the number of carbon fibers existing in a bundle of two or more were counted. Then, the defibration rate was calculated from the above formula. The defibration rate was expressed as an average value obtained from the above three points. The average value was rounded off to the 1st place and expressed in units of 10%.

[Join evaluation method]
FIG. 4 schematically shows a method of a tensile test according to an example. The joint structure used for the joint evaluation was obtained by joining so that the longitudinal direction of the first member and the longitudinal direction of the second member were parallel to each other. A thermal shock tester (manufactured by ESPEC) was used to perform a thermal shock test on the bonded structure at low and high temperatures. The temperature condition was −40 ° C. for 30 minutes on the low temperature side and 70 ° C. for 30 minutes on the high temperature side as one cycle. The number of cycles was 5, 50 or 1000 cycles. After the thermal shock test, the joint structure was pulled in the shearing direction (in the direction of the arrow shown in FIG. 4) using an electromechanical universal testing machine 5900 (manufactured by Instron). The tensile speed was 1 mm / min. The bondability was evaluated by observing the fracture surface and fractured part after the test and according to the fracture condition. The evaluation was decided as follows. When the joint interface was peeled off after 5 cycles of the thermal shock, it was judged to be ×, that is, it could not withstand the cold shock and was rejected. After 5 cycles, only the resin material was destroyed, but after 50 cycles, the case where peeling of the bonding interface and destruction of the resin material were mixed was evaluated as 〇, and equipment used in a relatively mild usage environment, such as home appliances. It was judged that the level could be applied to electrical equipment. After 50 cycles, only the resin material was destroyed, but after 1000 cycles, the case where peeling of the bonding interface and destruction of the resin material are mixed is marked as ◎, and it is used in an outdoor environment and requires a relatively long life. It was judged that the level was applicable to the equipment to be used, for example, transportation equipment. After 1000 cycles, the case where only the resin material was destroyed was marked as ◎◎, and it was judged that the level could be applied to equipment that is exposed to both low and high temperatures and requires a long life even in a harsh usage environment, such as industrial equipment. ..

[Example 1]
A protrusion was formed by irradiating SUS316 (100 mm × 20 mm, thickness 0.5 mm), which is a metal material, with an infrared laser using a fiber laser marker MX-Z2000H (manufactured by OMRON) to prepare a first member. ..

FIG. 3 schematically shows the laser processing portion 6 of the first member. The laser machined portion 6 was formed at one end of the first member 1 in the longitudinal direction. The laser irradiation conditions for forming protrusions are output: 6 W, frequency: 10 kHz, number of scans: 30, subpulses: 20, scanning speed: 1060 mm / s, and scanning trajectories so that the distance between protrusions is 20 μm and the width is 50 μm. Was adjusted as appropriate.

The shape of the protrusions was the shape shown in FIG. 6, and the arrangement of the protrusions was the shape shown in FIG. Further, the opposite side of the surface on which the protrusion was formed was rough-processed with the same type of laser.

Next, carbon fibers were added to the PBT resin at a ratio of 70:30 (weight ratio). High shearing was performed using a fully automatic high shear forming apparatus (NHSS2-28, manufactured by Niigata Machine Techno). The device includes a plasticized section and a high shearing section.

First, PBT resin (Novaduran 5010L, manufactured by Mitsubishi Engineering Plastics) and carbon fiber (SIGRAFIL CC6-4.0 / 240-T130, manufactured by SGL Carbon) were added to the plasticized portion. In the plasticized portion, the PBT resin and the carbon fiber were melt-kneaded with a single screw to obtain a resin composition. The conditions for melt kneading were a cylinder temperature of 250 ° C. and a screw rotation speed of 20 rpm.

The obtained resin composition was supplied to the high shearing section via a valve gate. By circulating the resin composition with an internal feedback screw, a carbon fiber composite resin in which the defibrated carbon fibers were dispersed in the thermoplastic resin was obtained. In the high shearing section, the cylinder temperature is 260 ° C., the screw rotation speed is 500 rpm, and the residence time is about 45 sec.

The obtained carbon fiber composite resin was formed into a molded product having a size of 100 mm × 25 mm × thickness of 2.0 mm according to a general injection molding method to obtain a second member.

The second member was superposed on the first member in the form of joining the ends in the longitudinal direction shown in FIG. 4, and installed on the joining jig. Next, the opposite side of the processed surface of the first member was repeatedly irradiated with an infrared laser and heated using an LD laser (manufactured by Jenoptik AG). The laser irradiation conditions are as follows; output: 24 W, wavelength: 808 nm, laser spot diameter: 2 mm, number of scans: 10 times. The surface of the second member was melted by heat transfer of the first member, and the first member and the second member were pressurized to obtain a bonded structure. Pressurization was performed by arranging the cylinder CQ2Φ20 (manufactured by SMC Corporation) perpendicularly to the joint structure. The pressurizing condition was an air pressure of 0.3 MPa in the cylinder.

[Example 2]
Among the laser irradiation conditions for forming the protrusions of the first member, the output was set to 3 W, the processed shape of the first member was the shape shown in FIG. 10, and the drilling arrangement was the shape shown in FIG. A bonded structure was obtained in the same manner as in Example 1. The opening diameter of the perforation was 20 μm, and the depth of the perforation was 50 μm.

[Example 3]
A bonded structure was obtained in the same manner as in Example 1 except that the high shearing conditions were a screw rotation speed of 300 rpm and a residence time of about 30 sec, and the defibration rate of carbon fibers was 50%.

[Example 4]
A bonded structure was obtained in the same manner as in Example 2 except that the high shearing conditions were a screw rotation speed of 300 rpm and a residence time of about 30 sec, and the defibration rate of carbon fibers was 50%.

[Comparative Example 1]
A bonded structure was obtained in the same manner as in Example 1 except that the high shearing process was not performed and the defibration rate of the carbon fibers was set to 0%.

[Comparative Example 2]
A bonded structure was obtained in the same manner as in Example 2 except that the high shearing process was not performed and the defibration rate of the carbon fibers was set to 0%.

The test results of Examples 1 to 4 and Comparative Examples 1 and 2 are shown in Table 1.

From Table 1, it was found that Examples 1 to 4 in which the carbon fibers were defibrated showed stronger thermal shock resistance and bonding as compared with Comparative Examples 1 and 2 in which the carbon fibers were not defibrated at all.

[Example 5]
The laser irradiation conditions for forming the protrusions of the first member were changed as follows, and the laser scanning trajectory was appropriately adjusted so that the protrusion arrangement was as shown in FIG. 12 and the protrusion shape was as shown in FIG. A bonded structure was obtained in the same manner as in Example 1 except for the above. Output: 3W, frequency: 10kHz, scanning speed: 380mm / s, number of scanning: 20 times, subpulse: 20 lines.

[Example 6]
The laser irradiation conditions for forming the protrusions of the first member were changed as follows, and the scanning trajectory was appropriately adjusted so that the protrusion shape became the shape shown in FIG. 7, except that the joining was performed in the same manner as in Example 1. Obtained a structure. Output: 6W, frequency: 10kHz, scanning speed: 900mm / s, number of scanning: 30 times, subpulse: 20 lines.

[Example 7]
The laser irradiation conditions for forming the protrusions of the first member were changed as follows, and the scanning trajectory was appropriately adjusted so that the protrusion arrangement was as shown in FIG. 12 and the protrusion shape was as shown in FIG. A bonded structure was obtained in the same manner as in Example 1 except for the above. Output: 6W, frequency: 10kHz, scanning speed: 700mm / s, number of scanning: 20 times, subpulse: 20 lines.

[Example 8]
The laser irradiation conditions for forming the protrusions of the first member were changed as follows, and the scanning trajectory was appropriately adjusted so that the protrusion arrangement was as shown in FIG. 12 and the protrusion shape was as shown in FIG. A bonded structure was obtained in the same manner as in Example 1 except for the above. Output: 1W, frequency: 10kHz, scanning speed: 380mm / s, number of scanning: 20 times, subpulse: 20 lines.

[Example 9]
The laser irradiation conditions for forming the protrusions of the first member were changed as follows, and the scanning trajectory was appropriately adjusted so that the perforation arrangement was as shown in FIG. 13 and the perforation shape was as shown in FIG. A bonded structure was obtained in the same manner as in Example 1 except for the above. Output: 3W, frequency: 10kHz, scanning speed: 1060mm / s, number of scanning: 20 times, subpulse: 5 lines.

[Comparative Example 3]
A joint structure was obtained in the same manner as in Example 1 except that the first member was not processed.

The results of Examples 5 to 9 and Comparative Example 3 are shown in Table 2.

From Table 2, it was found that Examples 5 to 9 having protrusions or perforations exhibited stronger thermal shock resistance and bonding as compared with Comparative Example 3 having neither.

[Example 10]
A bonded structure was obtained in the same manner as in Example 1 except that the laser irradiation conditions for forming the protrusions of the first member were changed as follows. Output: 6W, frequency: 10kHz, scanning speed: 1200mm / s, number of scanning: 40, subpulse: 20.

[Example 11]
A bonded structure was obtained in the same manner as in Example 1 except that the laser irradiation conditions for forming the protrusions of the first member were changed as follows. Output: 6W, frequency: 10kHz, scanning speed: 1060mm / s, number of scanning: 40, subpulse: 20.

[Example 12]
A bonded structure was obtained in the same manner as in Example 1 except that the laser irradiation conditions for forming the protrusions of the first member were changed as follows. Output: 6W, frequency: 10kHz, scanning speed: 600mm / s, number of scanning: 30 times, subpulse: 20 lines.

[Example 13]
The joint structure is the same as in Example 1 except that the laser irradiation conditions for forming the protrusions of the first member are changed as follows and the scanning trajectory is appropriately adjusted so that the distance between the protrusions is about 100 μm. Got Output: 6W, frequency: 10kHz, scanning speed: 1040mm / s, number of scanning: 40 times, subpulse: 20 lines.

[Example 14]
The joint structure is the same as in Example 1 except that the laser irradiation conditions for forming the protrusions of the first member are changed as follows and the scanning trajectory is appropriately adjusted so that the distance between the protrusions is about 150 μm. Got Output: 6W, frequency: 10kHz, scanning speed: 1040mm / s, number of scanning: 30 times, subpulse: 20 lines.

The test results of Examples 1 and 10 to 14 are shown in Table 3.

From Table 3, Examples 10 to 14 in which the distance between the protrusions is 5 to 150 μm all show good thermal shock resistance and strong bonding. In particular, it was found that when the distance between the protrusions was 10 to 100 μm, better resistance and bonding were exhibited, and when the distance between the protrusions was 20 to 50 μm, the strongest resistance and bonding were exhibited.

[Example 15]
A bonded structure was obtained in the same manner as in Example 1 except that the laser irradiation conditions for forming the protrusions of the first member were changed as follows. Output: 6W, frequency: 10kHz, scanning speed: 380mm / s, number of scanning: 40, subpulse: 20.

[Example 16]
A bonded structure was obtained in the same manner as in Example 1 except that the laser irradiation conditions for forming the protrusions of the first member were changed as follows. Output: 6W, frequency: 10kHz, scanning speed: 520mm / s, number of scanning: 30 times, subpulse: 20 lines.

[Example 17]
The joint structure is the same as in Example 1 except that the laser irradiation conditions for forming the protrusions of the first member are changed as follows and the scanning trajectory is appropriately adjusted so that the width of the protrusions is about 100 μm. Got Output: 6W, frequency: 10kHz, scanning speed: 1040mm / s, number of scanning: 40 times, subpulse: 20 lines.

[Example 18]
The joint structure is the same as in Example 1 except that the laser irradiation conditions for forming the protrusions of the first member are changed as follows and the scanning trajectory is appropriately adjusted so that the width of the protrusions is about 200 μm. Got Output: 6W, frequency: 10kHz, scanning speed: 1040mm / s, number of scanning: 40 times, subpulse: 20 lines.

The test results of Examples 1 and 15-18 are shown in Table 4.

From Table 4, Examples 15 to 18 having a protrusion width of 10 to 200 μm all show good thermal shock resistance and bonding. In particular, it was found that when the width of the protrusion was 10 to 100 μm, better resistance and bonding were exhibited, and when the width of the protrusion was 20 to 50 μm, the strongest resistance and bonding were exhibited.

[Example 19]
A bonded structure was obtained in the same manner as in Example 1 except that the laser irradiation conditions for forming the protrusions of the first member were changed as follows. Output: 6W, frequency: 10kHz, scanning speed: 1060mm / s, number of scanning: 5 times, subpulse: 20 lines.

[Example 20]
A bonded structure was obtained in the same manner as in Example 1 except that the laser irradiation conditions for forming the protrusions of the first member were changed as follows. Output: 6W, frequency: 10kHz, scanning speed: 1060mm / s, number of scanning: 10 times, subpulse: 20 lines.

[Example 21]
A bonded structure was obtained in the same manner as in Example 1 except that the laser irradiation conditions for forming the protrusions of the first member were changed as follows. Output: 6W, frequency: 10kHz, scanning speed: 1060mm / s, number of scanning: 65 times, subpulse: 20 lines.

[Example 22]
A bonded structure was obtained in the same manner as in Example 1 except that the laser irradiation conditions for forming the protrusions of the first member were changed as follows. Output: 6W, frequency: 10kHz, scanning speed: 1060mm / s, number of scanning: 130 times, 10 subpulses.

[Example 23]
A bonded structure was obtained in the same manner as in Example 1 except that the laser irradiation conditions for forming the protrusions of the first member were changed as follows. Output: 6W, frequency: 10kHz, scanning speed: 1060mm / s, number of scanning: 200 times, subpulse: 10 lines.

The test results of Examples 1 and 19-23 are shown in Table 5.

From Table 5, Examples 19 to 23 in which the height of the protrusion is 15 μm or more show good thermal shock resistance and bonding. In particular, it was found that when the height of the protrusion was 20 μm or more, better resistance and bonding were exhibited, and when the height of the protrusion was 50 μm or more, the strongest resistance and bonding were exhibited.

[Example 24]
A bonded structure was obtained in the same manner as in Example 2 except that the laser irradiation conditions for forming the perforation of the first member were changed as follows. Output: 1W, frequency: 10kHz, scanning speed: 1060mm / s, number of scanning: 30 times, subpulse: 20 lines.

[Example 25]
A bonded structure was obtained in the same manner as in Example 2 except that the laser irradiation conditions for forming the perforation of the first member were changed as follows. Output: 1W, frequency: 10kHz, scanning speed: 1060mm / s, number of scanning: 20 times, subpulse: 20 lines.

[Example 26]
A bonded structure was obtained in the same manner as in Example 2 except that the laser irradiation conditions for forming the perforation of the first member were changed as follows. Output: 3W, frequency: 10kHz, scanning speed: 1060mm / s, number of scanning: 20 times, subpulse: 10 lines.

[Example 27]
A bonded structure was obtained in the same manner as in Example 2 except that the laser irradiation conditions for forming the perforation of the first member were changed as follows. Output: 6W, frequency: 10kHz, scanning speed: 1470mm / s, number of scanning: 30 times, subpulse: 20 lines.

[Example 28]
A bonded structure was obtained in the same manner as in Example 2 except that the laser irradiation conditions for forming the perforation of the first member were changed as follows. Output: 6W, frequency: 10kHz, scanning speed: 1840mm / s, number of scanning: 20 times, subpulse: 10 lines.

The test results of Examples 2 and 24-28 are shown in Table 6.

From Table 6, all of Examples 24 to 28 having a perforation opening diameter of 5 to 150 μm show good thermal shock resistance and bonding. In particular, it was found that when the opening diameter of the perforation was 10 to 100 μm, better resistance and bonding were exhibited, and when the opening diameter of the perforation was 50 μm, the strongest resistance and bonding were exhibited.

[Example 29]
A bonded structure was obtained in the same manner as in Example 2 except that the laser irradiation conditions for forming the perforation of the first member were changed as follows. Output: 3W, frequency: 10kHz, scanning speed: 1060mm / s, number of scanning: 5 times, subpulse: 20 lines.

[Example 30]
A bonded structure was obtained in the same manner as in Example 2 except that the laser irradiation conditions for forming the perforation of the first member were changed as follows. Output: 3W, frequency: 10kHz, scanning speed: 1060mm / s, number of scanning: 10 times, subpulse: 20 lines.

[Example 31]
A bonded structure was obtained in the same manner as in Example 2 except that the laser irradiation conditions for forming the perforation of the first member were changed as follows. Output: 3W, frequency: 10kHz, scanning speed: 1060mm / s, number of scanning: 65 times, subpulse: 15 lines.

[Example 32]
A bonded structure was obtained in the same manner as in Example 2 except that the laser irradiation conditions for forming the perforation of the first member were changed as follows. Output: 3W, frequency: 10kHz, scanning speed: 1060mm / s, number of scanning: 130 times, subpulse: 10 lines.

[Example 33]
A bonded structure was obtained in the same manner as in Example 2 except that the laser irradiation conditions for forming the perforation of the first member were changed as follows. Output: 3W, frequency: 10kHz, scanning speed: 1060mm / s, number of scanning: 200 times, subpulse: 5 lines.

The test results of Examples 2 and 29-33 are shown in Table 7.

From Table 7, all of Examples 29 to 33 having a perforation depth of 15 to 300 μm show good thermal shock resistance and bonding. In particular, it was found that better resistance and bonding were exhibited when the perforation depth was 20 μm or more.

One aspect of the present invention can be applied to all devices that require bonding with, for example, a metal and a carbon fiber composite resin.

1 1st member 2 2nd member 3 Protrusion 4 Perforation 5 Carbon fiber 6 Laser processing part 11 Laser irradiation part 12 Laser irradiation superimposition part 13 Laser non-irradiation part 21 Area where diameter expands 22 Area where diameter decreases 31 Projection spacing 101 , 102 Joint structure

Claims (8)

A first member, which is a metal work piece in which at least one of protrusions and perforations is formed on the surface.
A second member containing a thermoplastic resin and carbon fibers dispersed in the thermoplastic resin in a defibrated state and bonded to the first member via at least one of the protrusion and the perforation. And a joined structure with. The bonded structure according to claim 1, wherein the defibration rate of the carbon fiber derived from the following formula is 50% or more.
Defibrillation rate (%) = (number of carbon fibers existing alone) / (total number of carbon fibers) x 100 The bonded structure according to claim 1 or 2, wherein the distance between the protrusions is 5 to 150 μm. The joint structure according to any one of claims 1 to 3, wherein the width of the protrusion is 10 to 200 μm. The joint structure according to any one of claims 1 to 4, wherein the height of the protrusion is 15 μm or more. The joint structure according to any one of claims 1 to 5, wherein the opening diameter of the perforation is 5 to 150 μm. The joint structure according to any one of claims 1 to 6, wherein the perforation depth is 15 μm or more. The process of forming at least one of protrusions and perforations on the surface of the metal material to obtain the first member, and
A process of obtaining a second member by dispersing carbon fibers in a thermoplastic resin in a defibrated state with an internal feedback screw.
A method for manufacturing a joined structure, which comprises a step of joining the first member and the second member.

Images