JP2018114670A - Method for producing composite body of coated steel sheet and resin material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method capable of efficiently joining a coated steel sheet having a thermoplastic resin film and a resin material and capable of producing a composite of a metal material and the resin material having high strength.SOLUTION: An object to be bonded is prepared by stacking a coated steel plate having a thermoplastic resin film on at least a surface to be bonded and a resin material, and ultrasonic vibration is applied to the object to be bonded in a state where the object to be bonded is pressed. This is a method of manufacturing a composite body of a coated steel sheet and a resin material by joining the coated steel sheet and the resin material. The thermoplastic resin film has a total thickness of 1.0 μm or more and 10 μm or less. And an amplitude of the ultrasonic vibration is 20 μm or more and 40 μm or less, and the ultrasonic vibration is stopped, and then a tool for applying the ultrasonic vibration is held on the object to be bonded for 0.1 second or more.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for producing a composite of a coated steel plate and a resin material.

  In recent years, in the automobile industry, the use of resin is progressing in response to the demand for weight reduction. In addition to being replaced with a resin material, a composite of a metal plate and a resin material is also applied. Therefore, in the manufacture of the composite, it is required to join the metal plate and the resin material efficiently.

  As a method for joining two members made of different materials such as metal and resin, a joining method by laser irradiation is known. For example, Patent Document 1 proposes to form fine irregularities on the surface of the joining member to increase the laser light absorption rate. Patent Document 2 proposes a method of joining by irradiating a laser from the metal side and softening or melting a resin material.

  Other than the joining method by laser irradiation, a method using ultrasonic joining is known. In Patent Document 3, the coated steel sheets having the thermoplastic resin film whose surface roughness Ra is adjusted to 1 μm or more are ultrasonically vibrated in a pressed state, and the thermoplastic resin film is formed at the contact point of the ultrasonic vibrator. It has been reported that coated steel sheets can be joined in a short time by raising the temperature locally.

JP 2008-162288 A JP 2010-76437 A JP 2005-14549 A

  The bonding method by laser irradiation in Patent Documents 1 and 2 is difficult to apply to a resin having no laser transparency, and requires a pretreatment for increasing the laser absorbability of the material to be bonded. is there.

Patent document 3 has proposed the joining method which joins the coated steel plates by the ultrasonic joining method regarding the joining of the coated steel plates which have a thermoplastic resin film. However, it cannot be said that the obtained bonding strength is sufficiently high. For example, according to an example of Patent Document 3, it is described that a bonded body obtained by an ultrasonic vibrator (horn) having a diameter of 10 mm has a shear strength of 650N. When this shear strength (N) is divided by the contact area (mm ² ) of the ultrasonic transducer, the shear strength per unit area is converted to about 8 MPa. The shear strength is not sufficient as a practical material.

  Therefore, in addition to being able to join the metal material and the resin material efficiently, a joining method suitable for manufacturing a high-strength composite is required. The present invention provides a production method capable of producing a composite of a metal material and a resin material having high strength while being able to be efficiently joined using a coated steel plate and a resin material having a thermoplastic resin film. The purpose is to do.

  The present invention has been devised in order to solve such problems, and when joining by a ultrasonic joining method using a coated steel sheet and a resin material having a thermoplastic resin film, By controlling the thickness of the thermoplastic resin film, the amplitude of ultrasonic vibration, the pressure holding time, and the like, the inventors found the conditions for obtaining a composite having high shear strength, and completed the present invention. Specifically, the present invention provides the following.

(1) The present invention provides a bonded body in which a coated steel plate having a thermoplastic resin film on at least a bonded surface side and a resin material are stacked, and in a state where the bonded body is pressed, Is applied to the coated steel plate and the resin material to produce a composite of the coated steel plate and the resin material, the total thickness of the thermoplastic resin film being 1 0.0 μm or more and 10 μm or less,
A coated steel plate and a resin material, wherein the amplitude of the ultrasonic vibration is 20 μm or more and 40 μm or less, and after the ultrasonic vibration is stopped, a tool for applying the ultrasonic vibration is held on the joined body for 0.1 second or more. This is a method for producing the composite.

(2) The present invention is the method for producing a composite of a coated steel sheet and a resin material according to claim 1, wherein the composite has a shear tensile strength per unit area of 10 MPa or more.

  ADVANTAGE OF THE INVENTION According to this invention, it can join efficiently using the coated steel plate and resin material which have a thermoplastic resin film. Furthermore, a composite of a metal material and a resin material having high strength can be manufactured.

It is a figure which shows the test body used in the Example. It is a figure for demonstrating the ultrasonic joining test of an Example. It is a figure which shows typically the test apparatus which measures shear tensile strength. It is a figure which shows the test result regarding the amplitude of an ultrasonic wave. It is a figure which shows another test result regarding the amplitude of an ultrasonic wave. It is a figure which shows the test result regarding the film thickness of a thermoplastic resin film. It is a figure which shows another test result regarding the film thickness of a thermoplastic resin film. It is a figure which shows the test result regarding an excitation time. It is a figure which shows the test result regarding horn holding time. It is a figure which shows the test result regarding applied pressure. It is a figure for demonstrating the principle of ultrasonic bonding.

  An embodiment of the present invention will be described. The present invention is not limited to the following description.

  In the manufacturing method of the composite of the present embodiment, at least a coated steel plate having a thermoplastic resin film on the bonded surface side and a resin material are stacked, and the bonded body is pressed. This is a method for producing a composite of a coated steel plate and a resin material by applying ultrasonic vibration to the object to be joined and joining the painted steel plate and the resin material.

(Ultrasonic bonding method)
In general, ultrasonic bonding removes inactive layers such as adsorbed molecules and oxide layers present at the interface by friction by ultrasonic waves by applying pressure to the contact surfaces and vibrating them, and then bringing the new metal surfaces into direct contact with each other. In this state, the temperature is raised by friction, so that the components can diffuse and join at the interface. As shown in FIG. 11 (a), the two materials 21 and 22 are overlapped and sandwiched between the tools 23 and 24 of the ultrasonic bonding apparatus. The lower plate 22 positioned on the lower side is supported by a tool 24 (anvil) of an ultrasonic bonding apparatus. On the upper plate 21 positioned on the upper side, a tool 23 (horn) that vibrates ultrasonically is disposed. As shown in FIG. 11B, when joining, ultrasonic vibration is generated from the horn 23 in contact with the upper plate 21 while the upper plate 21 and the lower plate 22 are pressed by the pressurizing means 26 (not shown). It is transmitted to the joint. When the ultrasonic vibration is started, as shown in FIG. 11C, the horn 23 vibrates left and right, and a reaction force 27 is generated along with the movement of the horn 23. Friction occurs. The heating region 25 is formed by the heat generated by the friction, and the joining is performed by the diffusion and the anchor effect occurring at the contact interface between the materials to be joined. In this way, after the ultrasonic vibration is applied for a predetermined time, the upper plate 21 and the lower plate 22 are joined. In the present embodiment, the upper plate 21 is a coated steel plate, and the lower plate 22 is a resin material.

(Painted steel plate)
The coated steel sheet used in the present embodiment is provided with a thermoplastic resin film on one or both surfaces of the surface of the base steel sheet. Thermoplastic resin coatings include polyvinyl alcohol, polyvinyl butyral, polyvinyl acetal, polyvinyl acetate, polyvinyl chloride, polyvinyl pyrrolidone, polystyrene and other vinyl resins, polymethyl (meth) acrylate, polybutyl (meth) acrylate, polyacrylamide, polyacrylamide Acrylate resins such as acrylonitrile, polyolefin resins such as polypropylene and polyethylene, polyester resins, polycarbonate resins, polyurethane resins, polyamide resins, urea resins, polycaprolactan resins, polyarylate resins, polysulfone resins, silicone polyester resins, epoxy resins, etc. A thermoplastic resin can be applied.

  The total thickness of the thermoplastic resin film is preferably 1.0 μm or more and 10 μm or less. If this total is a coated steel sheet having the coating on both sides, this total corresponds to the total thickness of the coating on both sides. If it is a coated steel plate having the coating on one side, it corresponds to the thickness of the coating on one side. When the total film thickness of the thermoplastic resin film exceeds 10 μm, the strength of the joint formed with the resin material is reduced, and a composite having sufficient shear tensile strength cannot be obtained. On the other hand, if the total film thickness is excessively small, there is a region that is not covered on the surface of the steel sheet, and there is a possibility that a good joint cannot be formed with the resin material. Therefore, the total thickness is preferably 1.0 μm or more and 10 μm or less. A coated steel sheet having a thermoplastic resin film on both sides preferably has a film thickness on one side of 0.5 μm or more.

(Resin material)
As the resin material used in the present embodiment, a resin such as a polybutylene terephthalate resin, a polyamide resin, a polypropylene resin, or a polyphenylene sulfide resin can be applied. What is necessary is just to select the thickness of the resin material suitably according to the use. For example, a resin material having a thickness of 0.3 to 10 mm can be applied.

(Substrate to be joined)
A to-be-joined body is comprised by stacking a coated steel plate and a resin material. As the coated steel sheet, a resin-coated steel sheet in which a thermoplastic resin film is arranged on one side or both sides is used. Then, stacking of the coated steel plate and the resin material is performed so that the thermoplastic resin film of the coated steel plate is in contact with the resin material at the joint surface between the coated steel plate and the resin material. When ultrasonic vibration is applied, by forming a joint between the thermoplastic resin film and the resin material, the coated steel plate and the resin material are joined to obtain a composite composed of the metal material and the resin material. It is done.

(Amplitude of ultrasonic vibration)
In the present embodiment, the amplitude of ultrasonic vibration applied to the coated steel sheet is preferably in the range of 20 μm or more and 40 μm or less. When the thickness is less than 20 μm, friction between the thermoplastic resin film and the resin material does not sufficiently occur, and a bonded portion with good bonding strength cannot be formed. On the other hand, if it exceeds 40 μm, even if it is once joined, the joint location is destroyed by the application of excessive vibration, so that there is a possibility that a joint with good joint strength cannot be formed.

(Excitation time of ultrasonic vibration)
In the present embodiment, the excitation time can be appropriately selected according to conditions such as amplitude, pressure, and film thickness of the coated steel sheet. If the vibration time is too short, sufficient frictional heat cannot be obtained, so that the bonding strength is insufficient. If the excitation time is excessive, it will be separated by vibration even if it is temporarily joined. Therefore, it is preferable to vibrate in a suitable range, for example, a range of 0.2 to 0.6 seconds can be mentioned.

(Horn holding time)
In this embodiment, it is preferable to hold the state in which the tool (horn) that generates ultrasonic vibrations is pressed for 0.1 second or longer after the vibration is stopped. If the pressed state is released at the same time as the vibration is stopped, a dense structure cannot be formed when the joint is cooled, so that sufficient joint strength cannot be obtained.

(Pressure force of ultrasonic vibration)
In the present embodiment, the bonding strength can be increased by increasing the applied pressure at the start of vibration. On the other hand, if the applied pressure is increased, a load is applied to the additional device, and the horn bites into the surface of the joined body to leave indentations, so that the appearance is impaired. Therefore, excessive pressurization is not preferable.

(Frequency of ultrasonic vibration)
In this embodiment, the frequency of the applied ultrasonic wave is preferably about 20 kHz.

(Shear tensile strength)
In this embodiment, it is preferable that the composite has a shear tensile strength per unit area of 10 MPa or more. In the present specification, the shear tensile strength (unit: Pa) is the peak load (unit: N) obtained in the shear tensile test, and the area where the tool (horn) that generates ultrasonic vibration contacts the workpiece. By dividing by (mm ² ), it means a numerical value calculated as the shear strength per unit area. In the present specification, the shear tensile strength is sometimes referred to as “joining strength”. When the composite of the metal material and the resin material has a shear tensile strength of 10 MPa or more, it is suitable for use in many applications that require weight reduction.

  Examples of the present invention will be described. The present invention is not limited to the following description.

  A test body as shown in FIG. 1 was produced. The test body is obtained by stacking the coated steel plate 1 and the resin material 4. The coated steel plate 1 was prepared by providing a thermoplastic resin film 3 on both surfaces of a steel plate 2 having a thickness of 0.6 mm, and two types were prepared: a polyurethane film and a polypropylene film. The resin material 4 has a plate shape with a thickness of 3 mm and is prepared of PA6 (polyamide 6) and PP (polypropylene). The coated steel plate 1 and the resin material 4 were cut into a length of 75 mm and a width of 25 mm, respectively, and stacked so that they overlap each other at a portion of 20 mm in the longitudinal direction as shown in FIG.

  The combinations of the coated steel plate and the resin material are as shown in Table 1.

  Table 2 shows the film thicknesses (μm) of the thermoplastic resin films on both surfaces of the test body 1 and the test body 2.

  As shown in FIG. 2, the ultrasonic bonding of the test body was performed by placing the coated steel sheet 1 so as to be positioned on the horn 5 side. The test body was sandwiched between the horn 5 and the anvil 6 and pressurized, and ultrasonic vibration was applied. The horn 5 vibrates left and right. Due to the reaction force generated with the movement of the horn, frictional heat is generated at the contact surface between the thermoplastic resin film 3 and the resin material 4 and the temperature at the joining interface is increased. By the heating, the thermoplastic resin film 3 and the resin material 4 are locally melted and joined.

The contact portion where the test body comes into contact with the horn 5 is located approximately at the center of the portion where the coated steel plate 1 and the resin material 4 overlap, and the length is about 5 mm and the width is about 10 mm (the area is about 10 mm). Corresponding to a rectangular area of 50 mm ² ).

  In the ultrasonic bonding test, ultrasonic vibration having a frequency of 20 kHz was applied. The amplitude of the ultrasonic wave is changed between 10 to 60 μm, and the ultrasonic vibration is continued within the range of 0.1 to 1.0 second (s), and then the horn is held within the range of 0 to 5 s. I let you. The applied pressure at the start of vibration was changed in the range of 200 to 600N.

(Joint strength)
The bonded specimens were subjected to a shear tensile test using a tensile test apparatus shown in FIG. The tensile load was performed at 5 mm / min, and the peak load at which the specimen was broken was determined. The test body was fixed on the coated steel plate 1 side by the upper jig 9 and fixed on the resin material 4 side by the lower jig 10. The coated steel plate 1 was fixed so that one end on the opposite side of the joint portion protruded from the upper jig 9, and the protruding one end was gripped by the upper grip portion 7. The entire resin material 4 was fixed by the lower jig 10 and held by the lower grip 8. Thereby, it can prevent that the resin material 4 is crushed by the lower side grip part 8. FIG. When the test specimen was attached to the tensile test apparatus, the test specimen was gripped so that the central axis of the tensile load and the central axis of the coated steel plate were approximately the same. Since the area of the joint portion of the test specimen is considered to correspond to the contact area of the horn, the peak load (N) obtained by the tensile test is used as an index of the shear tensile strength of the test specimen, and the horn contact area (50 mm ² ). This was used as the bonding strength (MPa) of the test specimen.

( Example 1 : Test on amplitude and film thickness)
The influence of ultrasonic vibration amplitude and thermoplastic film thickness on bonding strength was investigated. Using a specimen having a predetermined film thickness, ultrasonic vibration was applied with a predetermined amplitude. When the applied pressure reached 400 N, ultrasonic vibration with a frequency of 20 kHz was applied, and ultrasonic vibration was continued for 0.3 seconds (s). After the ultrasonic vibration was stopped, the horn was held at 0.1 s. The test results are shown in FIGS. FIG. 4 shows a test result using the test body 1, and FIG. 5 shows a test result using the test body 2.

  The characteristics of ultrasonic vibration vary depending on the type of vibration medium, and reflection occurs at the boundary of the vibration medium, so that vibration energy is attenuated. In the case where the joined body in which the coated steel plate and the resin material according to the present embodiment are stacked is a coated steel plate in which the thermoplastic resin film is provided on both surfaces of the steel plate, thermoplastic resin film / steel plate / thermoplastic resin film / resin. The ultrasonic vibration is attenuated at three interfaces like a material. When the coating is a coated steel plate provided on one side of the steel plate, the ultrasonic vibration is attenuated at the two interfaces such as steel plate / thermoplastic resin coating / resin material. Therefore, it is thought that the thermoplastic resin film of the coated steel plate affects ultrasonic vibration. Therefore, Example 1 was evaluated based on the total film thickness of the thermoplastic resin film. As shown in FIGS. 4 and 5, the test specimen having the total thickness of the thermoplastic resin film of 1.0 μm or more and 10 μm or less has a bonding strength of 10 MPa or more within an amplitude of 20 μm or more and 40 μm or less. . When the amplitude was increased to 50 μm or more, the bonding strength decreased. This is presumed to be due to the fact that the once joined portion was destroyed by an excessive amplitude. Moreover, as shown in Table 2, it was confirmed that the film thickness of the thermoplastic resin film is preferable to achieve a bonding strength of 10 MPa or more when one side is 0.5 μm or more.

  Next, with respect to the test results with amplitudes of 20 μm, 30 μm, and 40 μm in FIGS. As shown in FIGS. 6 and 7, as the total film thickness became smaller, the bonding strength increased and showed a peak near 1.0 μm and a tendency to rapidly decrease below 1.0 μm. On the other hand, when the total thickness exceeded 10 mm, the bonding strength was less than 10 MPa. The reason for this tendency has not been elucidated. Since the surface of the steel sheet generally has minute irregularities, when the thermoplastic resin film to be coated becomes excessively thin, there is a region that is not covered with the convex portion on the surface of the steel plate, and this region is a resin body. It is presumed that the bonding strength has decreased because it does not contribute to the bonding. On the other hand, if the film thickness of the thermoplastic resin film becomes excessively large, the ultrasonic vibration is attenuated, and sufficient friction cannot be obtained at the joint between the coated steel plate and the resin material. Therefore, it is estimated that the contribution due to the adhesiveness with the steel sheet is reduced.

( Example 2 : Test on excitation time)
Next, the effect of the excitation time was examined. The specimen 1 having a total film thickness of 4.1 μm and the specimen 2 having a total film thickness of 4.0 μm were used. The applied pressure at the start of vibration was 400 N, and ultrasonic vibration with a frequency of 20 kHz and an amplitude of 30 μm was applied. The horn was held at 0.1 s after stopping the ultrasonic wave. The excitation time (s) was 0.1 s, 0.3 s, 0.6 s, 0.8 s, and 1.0 s. The test results are shown in FIG. A composite having a bonding strength of 10 MPa or more was obtained with an excitation time in the range of 0.2 to 0.6 s.

( Example 3 : Test on horn retention time)
Next, after stopping the excitation of ultrasonic waves, the influence of the time for holding the horn (horn holding time) was examined. Using the same test bodies 1 and 2 as in Example 2, the applied pressure at the start of vibration was 400 N, ultrasonic vibration having a frequency of 20 kHz and an amplitude of 30 μm was applied, and the excitation was continued for 0.3 s. The horn holding time (s) after the ultrasonic wave was stopped was 0 s (not held), 0.1 s, 0.5 s, 1.0 s, 3.0 s, and 5.0 s. The test results are shown in FIG. . When the horn was not held, the bonding strength was reduced, and a bonding strength of 10 MPa or more was obtained by holding the horn for 0.1 s or more. Even after the vibration was stopped, the effect of improving the bonding strength could be confirmed by holding the horn and pressurizing the bonded portion. Even if it was held for more than 0.1 s, the bonding strength was almost constant.

( Example 4 : Test on applied pressure at the start of vibration)
Next, the influence of the applied pressure at the start of vibration was examined. Using test specimens 1 and 2 similar to those in Example 2, ultrasonic vibration having a frequency of 20 kHz and an amplitude of 30 μm was applied, and the vibration was continued for 0.3 s, and the horn holding time after the ultrasonic was stopped was 0.1 s. It was. The applied pressure (N) at the start of vibration was 200N, 400N, and 600N. The test results are shown in FIG. As the applied pressure increased, the bonding strength increased. In the process of being cooled and solidified after being melt-bonded at the bonded portion, it is considered that the greater the applied pressure, the denser the bonded structure is formed, thereby increasing the bonding strength.

  From the above, the method for producing a composite according to the present invention provides a method capable of efficiently joining a coated steel plate and a resin material. Further, in a composite mainly composed of a resin material, the joint strength of the composite material is higher than before. The present invention has a useful effect in providing a composite having

DESCRIPTION OF SYMBOLS 1 Painted steel plate 2 Steel plate 3 Thermoplastic resin film 4 Resin material 5 Horn 6 Anvil 7 Upper grip part 8 Lower grip part 9 Upper jig 10 Lower jig 21 Upper board 22 Lower board 23 Horn 24 Anvil 25 Heating area 26 Addition Pressure means 27 Reaction force

Claims (2)

A bonded body in which at least a coated steel plate having a thermoplastic resin film on the bonded surface side and a resin material are stacked is manufactured, and ultrasonic vibration is applied to the bonded body in a state where the bonded body is pressurized. A method of manufacturing the composite of the coated steel plate and the resin material by joining the painted steel plate and the resin material,
The total thickness of the thermoplastic resin film is 1.0 μm or more and 10 μm or less,
The amplitude of the ultrasonic vibration is 20 μm or more and 40 μm or less,
A method for producing a composite of a coated steel plate and a resin material, wherein after the ultrasonic vibration is stopped, a tool for applying the ultrasonic vibration is held on the joined body for 0.1 second or more.   The method for producing a composite of a coated steel sheet and a resin material according to claim 1, wherein the composite has a shear tensile strength per unit area of 10 MPa or more.

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