JP6098551B2 - Method of joining metal member and resin member - Google Patents

Description

  The present invention relates to a method for joining a metal member and a resin member, and a resin member used in the method.

  Conventionally, weight reduction has been demanded in the fields of automobiles, railway vehicles, aircraft, and the like. For example, in the field of automobiles, the use of high-tensile materials has made it possible to reduce the thickness of steel sheets, or aluminum alloy materials have been used as substitutes for steel materials, and the use of resin materials has also advanced. In these fields, development of joining technology for metal members and resin members is important not only for reducing the weight of the car body, but also for increasing the strength and rigidity of the joining members and improving productivity. is there. So far, a so-called friction stir welding (FSW) method has been proposed as a method for joining a metal member and a resin member. The friction stir welding method is a method in which a metal member and a resin member are overlapped, a rotating tool is rotated and pressed against the metal member to generate frictional heat, and the resin member is melted and softened by this frictional heat to form a metal member. And a resin member.

  In such a friction stir welding method, for example, from the viewpoint of bonding strength, a coating film made of a thermoplastic resin compatible with the thermoplastic resin constituting the resin member is formed on one surface of the metal member, The technique (patent document 1) which arrange | positions and joins the said metal member so that the surface in which the coating film was formed contacts a resin member is disclosed.

JP 2009-279858 A

  However, in the above-described technique, it is necessary to form a coating film on the surface of the metal member before performing friction stir welding, which increases the number of processes and increases costs.

  Therefore, the inventors of the present invention have attempted to improve the bonding strength with a metal member by using a resin member made of a carboxylic acid-modified polymer. However, the carboxylic acid-modified polymer has a relatively low melting point and is a resin. Since the heat resistance of a member falls, the use of the obtained joined body may be restrict | limited.

  The present invention relates to a method for joining a metal member and a resin member, which can join a resin member having sufficiently improved heat resistance to the metal member with sufficient strength without increasing the number of steps, and a resin used in the method. An object is to provide a member.

The present invention
It is a hot-pressure bonding method in which a metal member and a resin member are overlapped, the resin member is softened by applying heat and pressure from the metal member side, and the metal member and the resin member are bonded.
The present invention relates to a method for joining a metal member and a resin member, wherein the resin member is a resin member in which the amount of carbonyl groups on the joining surface with the metal member is larger than the amount of carbonyl groups on the inner layer.

The present invention also provides
In the above bonding method, the hot-pressure bonding method is a friction stir welding method,
The friction stir welding method relates to a joining method including the following steps:
A first step of superimposing the metal member and the resin member; and while rotating the rotary tool, the metal member is pressed against the metal member to generate frictional heat, and the frictional heat softens the resin member to form the metal member and the resin member. Second step of joining.

  The present invention also relates to a resin member used in the joining method.

  According to the joining method of the present invention, since the resin member having a larger amount of carbonyl groups on the joining surface with the metal member than the inner layer portion is used, the heat resistance of the resin member is improved. Moreover, the resin member can be bonded to the metal member with sufficient strength.

It is a schematic diagram which shows an example of the friction stir welding apparatus suitable for the joining method of the metal member and resin member concerning this invention. It is a conceptual diagram which shows the joining mechanism of the metal member and resin member in the joining method of this invention. It is an enlarged view of the edge part of an example of the resin member used for the joining method of this invention. It is an enlarged view of the front-end | tip part of an example of the rotary tool used for the joining method of this invention. It is sectional drawing for demonstrating the preheating process in the joining method of this invention. It is sectional drawing for demonstrating the pushing stirring process in the joining method of this invention, a stirring maintenance process, and a holding process. It is sectional drawing of the conjugate | zygote obtained by the joining method of this invention. It is the schematic for demonstrating the measuring method of the joint strength in an Example.

  The bonding method of the present invention softens the resin member by superimposing the metal member and the resin member and applying heat and pressure from the metal member side, preferably locally from the metal member side. This is a hot-pressure joining method for joining a metal member and a resin member. The joining method employed in the joining method of the present invention is not particularly limited as long as it is a method of heating while applying pressure. For example, a friction stir welding method, a laser heating joining method, a resistance heating joining method (electric heating) Bonding method), induction heating bonding method, ultrasonic heating bonding method and the like. A friction stir welding method is preferably employed.

As will be described in detail later, the friction stir welding method is a joining method using frictional heat generated by pressing against a metal member while rotating a rotary tool.
The laser heating bonding method is a bonding method using heat generated by irradiating a metal member with a laser in a state where the bonding member is constrained. As the laser, a YAG laser, a fiber laser, a semiconductor laser, or the like is used.
The resistance heating joining method is a joining method using heat generated by flowing a current directly through a metal member in a state where the joining member is constrained.
The induction heating joining method is a joining method in which an induction current is generated in a metal member by electromagnetic induction while the joining member is constrained, and heat generated by the current is used.
The ultrasonic heating joining method is a joining method using ultrasonic vibration in the resin member while applying pressure from the resin member side, and utilizing frictional heat between the metal member and the resin member generated by the vibration.

  Hereinafter, the joining method of the present invention that employs the friction stir welding method will be described with reference to the drawings. However, as long as the resin member described later is used, the effects of the present invention can be obtained even if other joining methods described above are used. Is clear.

  First, FIG. 1 is a diagram schematically showing an example of a part of a friction stir welding apparatus suitable for carrying out the joining method of the present invention. A friction stir welding apparatus 1 shown in FIG. 1 is configured as a device that friction stir welds a metal member 11 and a resin member 12, and includes a cylindrical rotary tool 16. As shown in the figure, the rotary tool 16 is applied to the workpiece 10 with the metal member 11 on the top and the resin member 12 on the bottom, by a drive source (not shown) as indicated by an arrow A1. While rotating around the central axis X (see FIG. 4), the metal member 11 is pressed downward in the pressing region P (scheduled pressing region) as indicated by an arrow A2. Friction heat is generated by the pressing of the rotary tool 16, and this frictional heat is conducted to the resin member 12 to soften and melt the resin member 12, and as a result, the metal member 11 and the resin member 12 are joined.

  Below the rotary tool 16, a cylindrical receiving member 17 having the same diameter as the rotary tool 16 or a larger diameter than the rotary tool 16 is arranged coaxially with the rotary tool 16. The receiving member 17 is moved upward with respect to the work 10 as shown by an arrow A3 by a driving source (not shown). The upper end surface of the receiving member 17 abuts on the lower surface of the workpiece 10 (more specifically, the lower surface of the resin member 12) by the time the rotating tool 16 starts pressing the workpiece 10 at the latest. The support 17 sandwiches the workpiece 10 between the rotary tool 16 and supports the workpiece 10 from below against the pressing force during a pressing period by the rotary tool 16, that is, during friction stir welding. Note that the receiving tool 17 does not necessarily have to be moved in the direction of the arrow A3, and a method of moving the rotary tool 16 in the direction of the arrow A2 after placing the workpiece 10 on the receiving tool 17 can also be adopted.

  The friction stir welding apparatus 1 is attached to a drive control device (not shown) composed of an articulated robot or the like. The coordinate positions of the rotary tool 16 and the receiving tool 17, the rotational speed (rpm) of the rotary tool 16, the pressure (N), the pressurization time (second), and the like are appropriately controlled by the drive control device. Although not shown in FIG. 1, the friction stir welding apparatus 1 uses a spacer, a clamp, or the like for fixing the work 10 in advance and preventing the metal member 11 from floating when the rotary tool 16 is pressed. A jig is provided.

(1) Resin Member The resin member 12 used in the joining method of the present invention includes at least two types of polymers having different carbonyl group contents, and is generally a polymer having a relatively high carbonyl group content ( In the present specification, the polymer includes a polymer having a relatively low content of a carbonyl group (sometimes simply referred to as “polymer A”). In the resin member 12 of the present invention, the polymer A mainly forms the bonding surface with the metal member, and the polymer B mainly forms the inner layer portion.

  The difference in the carbonyl group content in the polymer means that the value calculated as the weight ratio of the carbonyl group bonded to the polymer main chain with respect to the whole polymer is different. Hereinafter, the combinations are described in the order of “polymer A / polymer B”.

  The combination of polymer A / polymer B contained in the resin member 12 may be any combination as long as their carbonyl group content is different. From the viewpoint of the heat resistance of the resin member, the carboxylic acid-modified polyolefin / A combination of unmodified polyolefins is preferred. Hereinafter, the case where carboxylic acid-modified polyolefin / non-modified polyolefin is contained as polymer A / polymer B will be described. However, as long as the carbonyl group abundance gradient described below is achieved, the present invention is as polymer A / polymer B. This does not prevent the inclusion of a carboxylic acid-modified polyolefin having a relatively high carbonyl group content / a carboxylic acid modified polyolefin having a relatively low carbonyl group content.

  The carboxylic acid-modified polyolefin is a polymer in which a carboxyl group is introduced into the main chain and / or side chain of a polyolefin molecular chain. As the carboxylic acid-modified polyolefin, a graft copolymer in which an unsaturated carboxylic acid is grafted on the main chain of the polyolefin is preferably used.

  The polyolefin constituting the carboxylic acid-modified polyolefin is a homopolymer or copolymer composed of one or more monomers selected from the group consisting of α-olefins such as ethylene, propylene, butene, pentene, hexene, heptene, octene, or the like. It is a mixture. A preferred polyolefin is polypropylene.

  As the unsaturated carboxylic acid constituting the carboxylic acid-modified polyolefin, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, maleic anhydride, or a mixture thereof is used. Preferred unsaturated carboxylic acids are maleic acid, maleic anhydride or mixtures thereof, more preferably maleic anhydride.

  The amount of modification in the carboxylic acid-modified polyolefin is not particularly limited, but is preferably 0.01 to 1%.

  The amount of modification is a value calculated as a weight ratio of unsaturated carboxylic acid to the whole polymer.

  The molecular weight of the carboxylic acid-modified polyolefin is not particularly limited. For example, a carboxylic acid-modified polyolefin having an MFR (melt flow rate value) at 230 ° C. of 2.0 g / 10 minutes or more, particularly 5.0 g / 10 minutes or more. Preferably used.

  In this specification, the value measured by JIS K 7210 is used for the MFR of the polymer.

  The carboxylic acid-modified polyolefin is available as, for example, commercially available Modic P565 (manufactured by Mitsubishi Chemical Corporation) or Modic P553A (manufactured by Mitsubishi Chemical Corporation).

  As the unmodified polyolefin, the same polymers as those described as the polyolefin constituting the carboxylic acid-modified polyolefin are used. A preferred unmodified polyolefin is polypropylene.

  The molecular weight of the unmodified polyolefin is not particularly limited. For example, an unmodified polyolefin having an MFR (melt flow rate value) at 230 ° C. of 2 to 200 g / 10 minutes, particularly 2 to 55 g / 10 minutes is preferably used. .

  The unmodified polyolefin is, for example, commercially available Novatec FY6 (Nippon Polypro, unmodified polypropylene, MFR2.5), Novatec MA3 (Nippon Polypro, unmodified polypropylene, MFR11), Novatec MA1B (Nippon Polypro, unmodified). Modified polypropylene, MFR 21) is available.

  The combination of carboxylic acid-modified polyolefin / unmodified polyolefin is selected from the same series from the viewpoint of compatibility. The same system means that the combination of the carboxylic acid-modified polyolefin and the unmodified polyolefin contains a common monomer.

Specific examples of such a preferred combination of carboxylic acid-modified polyolefin / unmodified polyolefin include, for example, the following combinations:
(1) Carboxylic acid modified polypropylene / unmodified polypropylene;
(2) Carboxylic acid-modified polypropylene / unmodified ethylene-propylene copolymer;
(3) Carboxylic acid-modified ethylene-propylene copolymer / unmodified polypropylene;
(4) Carboxylic acid modified polyethylene / unmodified polyethylene;
(5) Carboxylic acid-modified ethylene-propylene copolymer / unmodified polyethylene;
(6) Carboxylic acid-modified polyethylene / unmodified ethylene-propylene copolymer;
(7) Carboxylic acid-modified polyethylene / unmodified ethylene-1-butene copolymer;
(8) Carboxylic acid modified polyethylene / unmodified polypropylene;
(9) Carboxylic acid-modified ethylene-1-butene copolymer / unmodified ethylene-propylene copolymer.

  Among the above combinations, from the viewpoint of bonding strength to the metal member, the combinations (1) to (3) are preferable, (1) to (2) are more preferable, and (1) is more preferable.

  In the present invention, the resin member 12 containing the polymer A and the polymer B has a specific gradient between the bonding surface of the metal member 11 and the inner layer portion in the amount of the carbonyl group. That is, the resin member 12 has a larger amount of carbonyl groups on the bonding surface with the metal member 11 than the inner layer portion. The polymer A generally has a melting point relatively lower than that of the polymer B. In the resin member 12 having the carbonyl group abundance gradient as described above, such a polymer A is mainly used on the bonding surface with the metal member 11. The polymer B can be mainly present in the inner layer portion. As a result, the resin member 12 of the present invention is bonded to the metal member 11 with sufficient strength while achieving excellent heat resistance as a whole as compared with the case where the entire resin member is made of polymer A. can do.

  The mechanism by which such a resin member 12 is bonded to the metal member 11 with sufficient strength is considered to be based on the following. For example, as shown in FIG. 2 which schematically represents the bonding interface between the metal member 11 and the resin member 12, the oxygen atom of the carbonyl group present on the surface of the resin member 12 is in a difference in electronegativity from the carbon atom. Based on, it has a charge of δ−. On the other hand, in the metal oxide layer on the surface of the metal member 11, the metal atom M has a charge of δ + based on the difference in electronegativity from the oxygen atom. As a result, due to melting of the surface of the resin member 12 at the time of bonding, an electrochemical bond due to electrostatic interaction occurs between the oxygen atom of the carbonyl group and the metal atom of the metal oxide layer, resulting in excellent bonding strength. It is considered to be obtained. In addition, it is considered that not only the chemical bond as described above but also the mechanical bond due to the anchor effect contributes to the bonding. The anchor effect is obtained by a caulking structure formed by a resin intruding into fine irregularities on a metal surface.

  In the present invention, as shown in FIG. 3, the bonding surface of the resin member 12 with the metal member 11 that should have a carbonyl group abundance gradient, which will be described in detail later, is on the bonding side of the resin member 12 with the metal member 11. The surface 120 is a region including at least the region P ′, preferably a region including at least the region Q, and more preferably a region including at least the region R. From the viewpoint of the ease of manufacturing the resin member and the heat resistance of the resin member, the bonding surface of the resin member 12 with the metal member 11 that should have a gradient of carbonyl group abundance is the bonding of the resin member 12 with the metal member 11. The entire surface of the side surface 120 is most preferable. The region P ′ is a region on the surface of the resin member 12 corresponding to a position immediately below the pressing region P (see FIG. 1) of the rotary tool 16 on the metal member 11 when the metal member 11 and the resin member 12 are overlapped. . The region Q is a region on the surface of the resin member where softening / melting for joining between the metal member 11 and the resin member 12 occurs, and includes the region P ′. The region R is a region on the surface of the resin member 12 that contacts the metal member 11 when the metal member 11 and the resin member 12 are overlapped.

When the resin member 12 includes carboxylic acid-modified polypropylene as the polymer A and unmodified polypropylene as the polymer B, the abundance of the carbonyl group can be represented by a ratio r of C = O peak intensity / CH ₃ peak intensity. In this case, the ratio r of the bonding surface of the resin member 12 to the metal member 11 should be larger than the ratio r of the inner layer portion, and the ratio r of the bonding surface of the resin member 12 to the metal member 11 is usually equal to that of the inner layer portion. It is larger than the ratio r by 0.0001 to 0.01, preferably larger by 0.001 to 0.01, more preferably larger by 0.003 to 0.01.

The ratio r on the bonding surface with the metal member 11 is usually greater than 0.001, particularly greater than 0.001 and not more than 0.015, preferably 0.003 to 0.015. If the ratio r on the bonding surface is too small, sufficient bonding strength cannot be obtained.
The ratio r of the inner layer portion is usually 0 or more, particularly 0 to 0.01, preferably 0 to 0.003. If the ratio r of the inner layer portion is too large, sufficient heat resistance cannot be obtained.

The ratio r of C = O peak intensity / CH ₃ peak intensity can be measured by IR spectrum analysis. For details, measures the intensity of the CH ₃ peak in the C = intensity of O peaks and 1375～1395Cm ^-1 in 1713～1792Cm ^-1 by IR spectrum analysis to determine their ratio. The IR spectrum analysis performs sample preparation, measurement, and data analysis in accordance with ISO8985 (JIS K7192) 4.1 (infrared spectroscopy).

The ratio r on the bonding surface with the metal member 11 is a value measured by subjecting a sample from a surface of a predetermined region in the resin member 12 to a depth of 10 μm for IR spectrum analysis. The measurement is performed to obtain an average value when measured at a ratio of two measurement points per 100 mm ² in a predetermined region.
The ratio r of the inner layer portion is a value measured by subjecting a sample from a depth t / 2 to a depth t / 2 + 10 μm to IR spectrum analysis, where the thickness of the resin member 12 is t (μm). The measurement is performed by obtaining an average value when the measurement is performed at a ratio of measurement points similar to the above in a predetermined region.

In the present invention, the thickness of the surface layer portion having the ratio r on the bonding surface is usually 0.01 to 1 mm, preferably 0.015 to 0.50 mm.
The thickness of the inner layer portion is usually 0.98 to 4.98 mm, preferably 1.98 to 4.98 mm.

  In the present invention, the resin member 12 may be manufactured by any method as long as it has the carbonyl group abundance gradient as described above. For example, it can be manufactured by an injection molding method or a laminated integrated molding method.

When the resin member 12 of the present invention is manufactured by an injection molding method, polymers A and B satisfying the following relationship are used:
MFR of polymer A> MFR of polymer B.

  In a preferred embodiment, the MFR of polymer A is 1.5 times greater than the MFR of polymer B, in particular 2.0 times greater. The MFR of polymer A is preferably 3 to 200 g / 10 minutes, more preferably 5 to 200 g / 10 minutes. The MFR of polymer B is preferably 2 to 100 g / 10 minutes, more preferably 2 to 80 g / 10 minutes.

  The injection molding method is a method for obtaining a molded product by injecting and holding a molten polymer in a temperature-controlled mold and then cooling and solidifying the polymer. In such an injection molding method, polymers A and B satisfying the above relationship are used. As a result, since the polymer A moves preferentially to the contact surface with the mold in the mixed melt in the mold during the holding, the abundance of the carbonyl group described above between the surface and the inner layer portion. A molded product exhibiting a gradient can be easily obtained. In the resin member obtained by the injection molding method, the gradient of the carbonyl group abundance from the surface to the inner layer portion changes continuously.

Molding conditions such as the ratio of the polymer A and the polymer B used in the injection molding method, the temperature of the mixed melt immediately before injection, the mold temperature, and the injection speed are not particularly limited as long as the resin member of the present invention is obtained. However, the following conditions are preferred.
The ratio of the polymer A and the polymer B used is preferably 15/85 to 45/55, particularly 20/80 to 40/60 in terms of weight ratio (A / B).
The temperature of the mixed melt immediately before injection is preferably 180 to 250 ° C, particularly 200 to 230 ° C.
The mold temperature is preferably 30 to 80 ° C, particularly preferably 30 to 50 ° C.
For example, when producing a substantially flat resin member having a thickness of 1 to 5 mm, the injection speed is preferably 30 to 200 mm / second, particularly 50 to 200 mm / second. If the injection speed is too slow, the preferential movement of the polymer A is not sufficient, and the desired carbonyl group gradient cannot be obtained.

  When the resin member 12 of the present invention is manufactured by the laminated integrated molding method, the MFR of the polymers A and B is not particularly limited, and those within the above-described ranges are used independently.

  The layered integrated molding method is to extrude each layer using the number of melt extruders corresponding to the number of layers, and at the same time, sequentially laminate and integrate those layers, and cool and solidify to obtain a molded product. This is a so-called integral extrusion method. In such a laminated integrated molding method, at least the polymers A and B are respectively extruded into layers, and the surface layer portion made of the polymer A is laminated and integrated on the surface of the inner layer portion made of the polymer B, and cooled and solidified. . As a result, it is possible to easily obtain a molded article exhibiting the above-described carbonyl group abundance gradient between the surface and the inner layer portion. In the resin member obtained by the laminated integrated molding method, the gradient of the carbonyl group existing amount from the surface to the inner layer portion changes stepwise.

The molding conditions such as the use ratio of polymer A and polymer B in the laminated integrated molding method and the set temperature of the melt extruder are not particularly limited as long as the resin member of the present invention can be obtained. preferable.
The ratio of the polymer A and the polymer B used is preferably 1/99 to 50/50, particularly 10/80 to 40/60, in terms of weight ratio (A / B).
The set temperature of the melt extruder for polymer A is preferably 180 to 250 ° C, particularly preferably 180 to 230 ° C.
The set temperature of the melt extruder for polymer B is preferably 180 to 250 ° C, particularly preferably 180 to 230 ° C.

  As described above, the resin member 12 has been described as having a substantially flat plate shape as a whole, but is not limited to this, and when the resin member 12 is overlapped with the metal member 11 for bonding, the portion immediately below the metal member 11 is As long as it has a substantially flat plate shape, it may have any shape.

  The thickness t of the resin member 12 at least immediately below the metal member 11 is usually 1 to 5 mm, particularly 2 to 5 mm, but is not limited thereto.

  The resin member 12 may contain other desired additives. Examples of other additives include reinforcing agents, stabilizers, flame retardants, colorants, and foaming agents. For example, when the resin member 12 has a surface layer portion and an inner layer portion by a laminated integrated molding method, the surface layer portion and the inner layer portion may contain the other additives selected independently.

(2) Metal member Although the metal member 11 has a substantially flat plate shape as an overall shape in FIG. 1 and the like, the metal member 11 is not limited to this, and only a portion that overlaps the resin member 12 for bonding is provided. As long as it has at least a substantially flat plate shape, it may have any shape.

  The thickness of the substantially flat plate-shaped portion that overlaps the resin member 12 in the metal member 11 is usually 0.5 to 4 mm, but is not limited thereto.

As the metal constituting the metal member 11, any metal having a melting point higher than that of the thermoplastic polymer constituting the resin member 12 can be used. Among these, the following metals and alloys used in the automotive field are preferably used:
Aluminum and aluminum alloys such as 5000 series and 6000 series;
steel;
Magnesium and its alloys;
Titanium and its alloys.

(3) Rotating Tool FIG. 4 is an enlarged view of the tip portion of the rotating tool 16. In FIG. 4, the right half shows the appearance of the rotary tool 16, and the left half shows a cross section. As shown in FIG. 4, the columnar rotary tool 16 has a pin portion 16 a and a shoulder portion 16 b at the distal end portion (lower end portion in FIG. 4). The shoulder portion 16 b is a portion at the tip of the rotary tool 16 including the circular tip surface of the rotary tool 16. The pin portion 16a is a cylindrical portion having a smaller diameter than the shoulder portion 16b, which protrudes outward (downward in FIG. 4) from the circular tip surface of the rotary tool 16 on the central axis X of the rotary tool 16. is there. The pin portion 16a is for positioning the rotating tool 16 when the rotating tool 16 that is rotating is first brought into contact with the workpiece 10 and pressed.

  The material of the rotary tool 16 and the dimensions of each part are mainly set according to the metal type of the metal member 11 pressed by the rotary tool 16. For example, when the metal member 11 is made of an aluminum alloy, the rotary tool 16 is made of tool steel (for example, SKD61), the diameter D1 of the shoulder portion 16b is 10 mm, the diameter D2 of the pin portion 16a is 2 mm, and the pin portion 16a protrudes. The length h is set to 0.5 mm. For example, when the metal member 11 is made of steel, the rotary tool 16 is made of silicon nitride, PCBN (cubic boron nitride sintered body), etc., the diameter D1 of the shoulder portion 16b is 10 mm, and the diameter D2 of the pin portion 16a. Is set to 3 mm, and the protruding length h of the pin portion 16a is set to 0.5 mm. Needless to say, these are merely examples, and the present invention is not limited thereto. For example, the diameter D1 of the shoulder portion 16b is usually 5 to 30 mm, preferably 5 to 15 mm, but is not limited thereto.

(4) One embodiment of the joining method according to the present invention (friction stir welding method)
The joining method (friction stir welding method) of the present invention performed using the friction stir welding apparatus 1 will be specifically described.

The joining method according to the present embodiment includes at least the following steps, and is characterized by using the resin member 12 described above:
A first step of superimposing the metal member 11 and the resin member 12; and while rotating the rotary tool 16, the metal member 11 is pressed against the metal member 11 to generate frictional heat, and the frictional heat softens the resin member 12 to form the metal member. 2nd step which joins 11 and resin member 12.
The metal member 11 and the resin member 12 obtained in the first step are called “work” 10.

  In the first step, as shown in FIG. 1, the metal member 11 and the resin member 12 are arranged such that the surface (for example, 120) having the carbonyl group abundance gradient in the resin member 12 contacts the metal member 11. And overlay.

In the second step, at least a push-in stirring step C2 is performed in which the rotary tool 16 is pushed into the metal member 11 to enter a depth that does not reach the joint interface between the metal member 11 and the resin member 12.
In the present embodiment, in the second step, the preheating step C1 for rotating the rotary tool 16 in a state in which only the tip portion of the rotary tool 16 is in contact with the surface portion of the metal member 11 is performed before the pushing and stirring step. It is preferable.
After the indentation stirring step, it is preferable to perform an agitation maintaining step C3 in which the rotation operation of the rotary tool 16 is continued at a position where the rotary tool 16 is advanced to a depth that does not reach the joining boundary surface.

Hereinafter, each step will be described in detail.
In the preheating step C1, by bringing the rotary tool 16 and the receiving member 17 close to each other, as shown in FIG. 5, only the tip of the rotary tool 16 is placed on the surface portion (upper surface portion in the illustrated example) of the metal member 11. This is a step of rotating the rotary tool 16 in a contacted state. In the preheating step C1, the rotary tool 16 is rotated at a predetermined rotation speed (for example, 3000 rpm) for a first pressurizing time (for example, 1.00 seconds) with a first pressure (for example, 900 N).

  In the indentation stirring step C2 next to the preheating step C1, the rotary tool 16 and the receiving member 17 are further brought closer to each other, thereby pushing the rotary tool 16 into the metal member 11 as shown in FIG. In this step, the resin member 12 is advanced to a depth not reaching the joint interface with the resin member 12. In the indentation stirring step C2, the rotary tool 16 is moved to a second pressurization time (for example, 0.25) shorter than the first pressurization time with a second pressurization force (for example, 1500 N) that is greater than the first pressurization force. Seconds) at a predetermined rotation speed (for example, 3000 rpm).

  In the stirring maintaining process C3 subsequent to the pushing stirring process C2, by stopping the mutual proximity of the rotary tool 16 and the receiving member 17, as shown in FIG. This is a step of continuing the rotation operation of the rotary tool 16 at a position (referred to as “reference position”). In the stirring maintaining step C3, the rotary tool 16 is moved to a third pressurizing time (for example, 5.75) longer than the first pressurizing time with a third pressurizing force (for example, 500 N) smaller than the first pressurizing force. Seconds) at a predetermined rotation speed (for example, 3000 rpm).

After the stirring maintaining step C3, a holding step C4 may be performed in which the rotation of the rotary tool 16 is stopped and the rotary tool 16 is held for a predetermined pressurizing time with a predetermined pressure in that state.
Similarly, as shown in FIG. 6, the holding step C <b> 4 is a step in which the rotation of the rotary tool 16 is stopped and the rotary tool 16 is held for a predetermined time with a predetermined pressure in that state. In the holding step C4, the rotary tool 16 is moved at a fourth pressure force (for example, 1000 N) that is larger than the third pressure force but smaller than the second pressure force and shorter than the third pressurization time but the second pressure force. Hold for a fourth pressurization time (for example, 5.00 seconds) longer than the pressure time.

  The pressurizing force, pressurizing time, and tool rotation speed exemplified above are merely examples, and can be appropriately changed. However, for example, in the case of joining the metal member 11 having a thickness of 1 mm or more and 2 mm or less and the resin member 12 having a thickness of 2 mm or more and 4 mm or less, mainly from the viewpoint of productivity (a balance between time reduction and yield), the preheating step The first applied pressure in C1 is preferably 700 N or more and less than 1200 N, and the first pressurizing time is preferably 0.5 second or more and less than 2.0 seconds. The second applied pressure in the indentation stirring step C2 is The value of 1200N or more and less than 1800N, and the second pressurization time is preferably a value of 0.1 second or more and less than 0.5 second, and the third pressure in the stirring and maintaining step C3 is a value of 100N or more and less than 700N, The third pressurization time is preferably 1.0 second or more and less than 10 seconds. Further, the fourth pressing force in the holding step C4 is preferably a value of 700 N or more and less than 1200 N, for example, and the fourth pressurizing time is preferably a value of 1 second or more, for example.

  Specifically, in the preheating step C <b> 1, frictional heat is generated at the surface portion (upper surface portion in the illustrated example) of the metal member 11 by pressing of the rotary tool 16. The frictional heat is transmitted to the inside of the metal member 11, and the range of the pressing region P of the metal member 11 and the range in the vicinity of the pressing region P are preheated. Thereby, it becomes easy to push the rotary tool 16 into the metal member 11 in the next pushing and stirring step C2.

  In the preheating step C <b> 1, the frictional heat is also transmitted to the resin member 12 through the joint interface between the metal member 11 and the resin member 12. The frictional heat is transmitted to the inside of the resin member 12, and the range of the corresponding region P 'immediately below the pressing region P in the resin member 12 and the range in the vicinity of the region P' are preheated. Thereby, the resin member 12 becomes easy to soften and melt in the next indentation stirring step C2.

  The first pressurizing force and the first pressurizing time in the preheating step C1 are set from the viewpoint of ease of pushing in the rotary tool 16 and the ease of softening / melting of the resin member 12, and values thereof. Varies depending on, for example, the number of rotations of the rotary tool 16 and the types of materials of the metal member 11 and the resin member 12.

  In the indentation stirring step C2, the rotating tool 16 is pushed into the metal member 11 when the applied pressure is larger than that in the preheating step C1. That is, the rotary tool 16 enters deep inside the metal member 11. By pressing the rotary tool 16, the joining boundary surface between the metal member 11 and the resin member 12 moves to the receiving member 17 side (lower side in the illustrated example).

  If the rotary tool 16 is further pushed in (that is, if the applied pressure is too high and / or the pressurizing time is too long), the shoulder portion 16b of the rotary tool 16 exceeds the joining boundary surface. That is, the rotary tool 16 penetrates the metal member 11 and contacts the resin member 12. Then, the metal member 11 is in a holed state in which the hole through which the rotary tool 16 has passed is opened, resulting in poor bonding.

  Therefore, in this embodiment, when the shoulder portion 16b of the rotary tool 16 enters a depth that does not reach the joining boundary surface in the push stirring step C2, the push of the rotary tool 16 is stopped. In other words, the rotary tool 16 is advanced to a depth that does not reach the joint interface. As a result, in the next agitation maintaining step C3, frictional heat is generated at a reference position close to the resin member 12, and a large amount of frictional heat is transmitted to the resin member 12 to promote softening and melting of the resin member 12.

  The second pressing force and the second pressurizing time in the indentation stirring step C2 are set from the viewpoint of avoiding the opening of the metal member 11 as described above and the rotating tool 16 as close to the resin member 12 as possible. The value changes depending on, for example, the number of rotations of the rotary tool 16 and the types of materials of the metal member 11 and the resin member 12.

  In the indentation stirring step C2, the resin member 12 has a corresponding region P ′ immediately below the pressing region P and a range Q in the vicinity of the region P ′ (for example, a region indicated by a circle α and a region indicated by a circle β in FIG. 6). ) Softens and melts. As a result, when the resin is cured after bonding, as described above, an electrochemical bond due to electrostatic interaction occurs between the oxygen atom of the carbonyl group in the resin member and the metal atom of the metal oxide layer in the metal member. Excellent bonding strength can be obtained.

  In the stirring maintaining step C3, the rotating tool 16 is maintained at the reference position by the applied pressure being smaller than that of the preheating step C1 (of course, being smaller than that of the pushing stirring step C2). Since the rotary tool 16 continues to rotate at the reference position close to the resin member 12, a large amount of frictional heat is generated, and most of the generated frictional heat moves to the resin member 12. Therefore, the resin member 12 is sufficiently softened and melted in a wide range beyond the range of the corresponding region P ′ immediately below the pressing region P. As a result, when the resin is cured after bonding, as described above, an electrochemical bond due to electrostatic interaction occurs between the oxygen atom of the carbonyl group in the resin member and the metal atom of the metal oxide layer in the metal member. Excellent bonding strength can be obtained.

  The third pressurizing force and the third pressurizing time in the stirring maintaining step C3 are set from the viewpoint of sufficient softening and melting of the resin member 12 as described above, and the values thereof are, for example, the rotary tool 16. Depending on the number of rotations and the types of materials of the metal member 11 and the resin member 12.

  In the holding step C4, the rotation of the rotary tool 16 is stopped, whereby the generation of frictional heat is completed. That is, the substantial operation as the friction stir welding is finished, and cooling of the workpiece 10 is started. During the cooling period of the workpiece 10, the rotating tool 16 whose rotation has been stopped is pressed between the metal member 11 and the resin member 12 because the applied pressure is smaller than the indentation agitation step C <b> 2 but greater than the agitation maintenance step C <b> 3. It clamps by pinching between the receiving tools 17. Thereby, the adhesive force during cooling between the metal member 11 and the resin member 12 is increased, and the bonding strength after completion of cooling is increased.

  The fourth pressurizing force and the fourth pressurizing time in the holding step C4 are set from the viewpoint of improving the adhesion of the pressing region P during the cooling period as described above, and the values thereof are, for example, the metal member 11 and the resin member. It varies depending on the type of 12 materials.

  In this embodiment, at least through the above-described step C2, preferably through the above-described steps C1, C2 and C3 and optionally through step C4, finally, as shown in FIG. The resin member 12 is softened and melted by the frictional heat generated by the pressing, and the joined member 20 of the metal member 11 and the resin member 12 in which the metal member 11 and the resin member 12 are joined with high strength in a wide range is obtained.

  As described above, the case where the metal member and the resin member are joined to each other in a dotted manner without continuously moving the rotating tool in the surface direction on the contact surface of the metal member (point joining) has been described. It is clear that the effect of the present invention can be obtained even when the metal member and the resin member are joined linearly (line joining) while continuously moving the rotary tool.

[Example 1]
(Resin member)
As polymer A, maleic anhydride-modified polypropylene, MFR 5.7) was used. The amount of modification was about 0.5%.
As polymer B, Novatec FY6 (Nippon Polypro, unmodified polypropylene, MFR2.5) was used.

  A resin member 12 having dimensions of 100 mm in length, 30 mm in width, and 3 mm in thickness was produced by using the polymers A and B by an injection molding method. Specifically, 20 parts by weight of polymer A and 80 parts by weight of polymer B were heated to 230 ° C. to obtain a mixed melt. The mixed melt was poured into a mold whose temperature was adjusted to 40 ° C. at an injection speed of 50 mm / second, and then cooled and solidified to obtain a resin member 12.

In the region R (see FIG. 3, contact region with the metal member 11) on the bonding-side surface 120 of the resin member 12, the ratio r of C = O peak intensity / CH ₃ peak intensity was measured by the method described above based on IR spectrum analysis. . The measurement was performed at the ratio of the measurement points described above, and the average value thereof was shown in the table.
When the ratio r was measured in the same manner as above for the region other than the region R on the bonding-side surface 120 of the resin member 12 and also on the surface opposite to the bonding-side surface 120 of the resin member 12, any ratio r was measured. Also showed the same value as in region R.

In the inner layer portion of the region R on the bonding-side surface 120 of the resin member 12, the ratio r was measured by the method described above based on IR spectrum analysis. The measurement was performed at the ratio of the measurement points described above, and the average value thereof was shown in the table.
The ratio r was measured in the same manner as described above for the inner layer portion of the region other than the region R on the bonding side surface 120 of the resin member 12 and also for the inner layer portion of the surface opposite to the bonding side surface 120 of the resin member 12. However, each ratio r showed the same value as in the inner layer portion of the region R.

(Metal member)
As the metal member, a flat plate member (thickness: 1.2 mm) made of a 6000 series aluminum alloy was used.
(Rotation tool)
As the rotating tool, a tool tool having dimensions of D1 = 10 mm, D2 = 2 mm, and h = 0.5 mm in each part of FIG. 4 was used.

(Joining method)
The joined body of the metal member 11 and the resin member 12 was manufactured by the following method.
First step:
The end of the metal member 11 and the end of the resin member 12 were overlaid as shown in FIG. 1 (overlap allowance 30 mm).

Second step:
As shown in FIG. 5, the rotary tool 16 was rotated in a state where only the tip of the rotary tool 16 was in contact with the surface portion of the metal member 11 (preheating step C1: pressure 900N, pressurization time 1.00 seconds). Tool rotation speed 3000r).
Next, as shown in FIG. 6, the rotary tool 16 is pushed into the metal member 11 to a depth that does not reach the joining interface between the metal member 11 and the resin member 12 (pushing stirring step C2: pressure 1500N, pressure applied). Pressure time 0.25 seconds, tool rotation speed 3000 rpm).
Next, as shown in FIG. 6, the rotation operation of the rotary tool 16 was continued at a position where the rotary tool 16 was advanced to a depth that did not reach the joining boundary surface (stirring maintaining step C3: pressurizing pressure 500 N, pressurizing time) 5.75 seconds, tool rotation speed 3000 rpm).
Next, as shown in FIG. 7, the rotary tool 16 was extracted from the joined body 20 and allowed to cool.

(Joint strength)
As shown in FIG. 8, the joined body of the metal member 11 and the resin member 12 was placed in the jig 100. The jig 100 is configured such that a downward force acts on the upper end portion of the resin member 12 by pulling the jig 100 downward. By fixing the jig 100 and pulling the metal member 11 upward, a downward force acts on the upper end portion of the resin member 12, and the shear strength S of the joint is affected by the base material strength of the resin member 12. Measured without any. The joint strength was evaluated based on the shear strength S.
○; 2.0 kN ≦ S;
Δ: 1.0 kN ≦ S <2.0 kN (no problem in practical use);
X: S <1.0 kN (problem in practical use).

(Heat-resistant)
The melting point T of the resin member 12 was measured by ISO 3146. The heat resistance was evaluated based on the melting point T.
○: 163 ° C. ≦ T;
Δ: 161 ° C. ≦ T <163 ° C. (no problem in practical use);
×: T <161 ° C. (practical problem).

[Example 2 and Comparative Examples 1 to 10]
Resin members were produced and evaluated in the same manner as in Example 1 except that the blending ratios of Polymers A to C were changed as shown in the table.
As the polymer C, Novatec BC06C (Nippon Polypro, unmodified polypropylene, MFR60) was used. Specifically, the polymer C is a polymer in which polyethylene or ethylene-propylene copolymer is dispersed in homopolypropylene.

  The joining method according to the present invention is useful for joining a metal member and a resin member in the fields of automobiles, railway vehicles, aircraft, home appliances, and the like.

1: Friction stir welding apparatus 10: Work 11: Metal member 12: Resin member 16: Rotating tool 17: Receiving tool 20: Joined body 100: Jig for measuring joint strength 120: Joining of metal member to resin member Side surface P: Pressing area (scheduled pressing area) by rotating tool on metal member surface
P ′: a region on the surface of the resin member corresponding directly below the pressing region P Q: a region where softening / melting occurs on the surface of the resin member during bonding

Claims (5)

The first step that overlay the metal member and the resin member; and
While rotating the rotary tool, the metal member is pressed to generate frictional heat, and by applying heat and pressure from the metal member side , the resin member is softened by this frictional heat, and the metal member and the resin member are separated. A joining method of a metal member and a resin member by a hot-pressure joining method based on a friction stir welding method including a second step of joining,
The second step includes a pushing and stirring step of pushing the rotating tool into the metal member to enter a depth not reaching the joint interface between the metal member and the resin member,
The rotary tool has a shoulder portion including a circular tip surface of the rotary tool at the tip portion, and a cylindrical pin having a smaller diameter than the shoulder portion, which protrudes outward from the circular tip surface of the rotary tool. Part
The second step further includes a preheating step of rotating the rotating tool in a state where only the pin portion and the shoulder portion at the tip portion of the rotating tool are in contact with the surface portion of the metal member before the pushing and stirring step. With
In the preheating step, the rotary tool is rotated by a first pressurizing time while being pressed with a first pressing force,
In the indentation stirring step, the rotary tool is rotated by a second pressurization time shorter than the first pressurization time while pressing the rotary tool with a second pressurization force larger than the first pressurization force,
As the resin member, a resin member in which the amount of carbonyl groups present on the bonding surface with the metal member is larger than the amount of carbonyl groups present in the inner layer portion ,
The resin member includes polymer A and polymer B,
The polymer A is a carboxylic acid-modified polyolefin,
The polymer B is an unmodified polyolefin,
When the abundance of carbonyl groups in the resin member is represented by a ratio r of C = O peak intensity / CH ₃ peak intensity, the ratio r of the bonding surface with the metal member in the resin member is less than the ratio r of the inner layer portion. .0001-0.01 bigger,
The ratio r of the bonding surface with the metal member in the resin member is greater than 0.001 and less than or equal to 0.015,
The method for joining a metal member and a resin member, wherein the ratio r of the inner layer portion in the resin member is 0 to 0.003 . The method for joining a metal member and a resin member according to claim 1 , wherein the resin member is manufactured by an injection molding method using polymers A and B that satisfy the following relationship with respect to MFR at 230 ° C .:
MFR of polymer A> MFR of polymer B. The metal member and the resin member according to claim 1 , wherein the resin member is manufactured by a laminated integrated molding method in which a surface layer portion made of a polymer A is laminated and integrated on a surface of an inner layer portion made of a polymer B. Method. The second step further comprises an agitation maintaining step of continuing the rotating operation of the rotating tool at a position where the rotating tool has entered to a depth that does not reach the joining boundary surface,
Of claims 1 to 3 which rotates only between the rotary tool is longer than between the pressed while the first pressurization in the first pressure is less than the third pressure third pressurization in the stirring hold step The joining method of the metal member and resin member in any one . The second step further includes a holding step of stopping the rotation of the rotary tool after the stirring maintaining step and holding the rotary tool at a predetermined pressurizing time for a predetermined pressurizing time in that state. 5. A method for joining the metal member and the resin member according to 4 .

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