Method of manufacturing adhesives

Abstract

To provide a method which manufactures an adhesion object showing excellent adhesiveness by confirming a surface treatment level of a member in advance with a wet reagent and which does not need to visually perform wetness determination.SOLUTION: A manufacturing method of an adhesive comprises: a step of performing a surface treatment on a first member; a step of measuring surface free energy by using a dye-containing wet reagent; a step of determining whether a desired surface treatment is performed; a step of forming an adhesive layer by applying an adhesive; and a step of manufacturing an adhesion object by sticking second members to each other. The surface free energy measurement step is the step of determining wetness by a wetness determination method by applying a reagent constituting the wet reagent to the first member. The wetness determination method comprises: a step of acquiring an image of a member applied with the reagent; a step of performing binarization such that a place where the reagent exists and a portion where the reagent does not exist are discriminated from each other; a step of obtaining an area of the place where the reagent exists; and a step of performing determination of wetness on the basis of a ratio of the area of the place where the reagent exists to an area applied with the reagent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing adhesives. [Background technology]

[0002] Recently, from the perspective of reducing the weight of automobiles, the use of resins such as polypropylene has been increasing in some parts of the interior and exterior of automobiles, such as the car body, front doors, rear doors, tailgate, front bumper, rear bumper, and rocker moldings. When resins are used in such car interior and exterior parts, a primer composition is applied to the bonding surface, or the bonding surface is treated before applying the adhesive, in order to improve adhesion. When applying adhesive after surface treatment to the bonding surface, sufficient adhesion cannot be obtained if the applied surface treatment is not as desired. Therefore, it is generally important to confirm in advance whether or not the desired surface treatment has been applied (surface treatment level). A method for easily confirming the surface treatment level of a surface-treated component is known to be one that uses a wetting reagent (for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-43088 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] Patent Document 1 describes determining wetting using a wetting reagent by visual inspection. However, our investigations have revealed that visual inspection of wetting can be inaccurate, as the results may vary depending on the inspector. Furthermore, it has become clear that incorrect determination of whether the desired surface treatment has been performed can result in insufficient adhesion of the resulting adhesive.

[0005] Therefore, in view of the above circumstances, the present invention aims to provide a method for producing an adhesive that exhibits excellent adhesion by confirming the surface treatment level of the member in advance using a wetting reagent, and a method that does not require visual inspection to determine wetting using a wetting reagent. [Means for solving the problem]

[0006] As a result of diligent research into the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by acquiring an image of a component to which the reagent constituting the wetting reagent is applied, binarizing the image, and using the binarized image to determine wetting, thus leading to the present invention. In other words, the inventors have found that the above problem can be solved by the following configuration.

[0007] (1) A surface treatment step in which the first member is subjected to surface treatment, A surface free energy measurement step, in which the surface free energy of the first member subjected to the above surface treatment is measured using a wetting reagent containing a dye, A surface treatment level confirmation step is performed to determine whether or not the desired surface treatment has been applied, based on the surface free energy measured by the above surface free energy measurement step. The first member, which has been determined to have received the desired surface treatment based on the above surface treatment level confirmation step, is subjected to an adhesive application step, which involves applying an adhesive to form an adhesive layer, or applying a primer and then an adhesive to form a primer layer and an adhesive layer. A method for manufacturing an adhesive, comprising an bonding step of bonding a second member onto the adhesive layer described above, thereby manufacturing an adhesive having a first member, an adhesive layer, and a second member in that order, or a first member, a primer layer, an adhesive layer, and a second member in that order, A method for manufacturing an adhesive, wherein the above surface free energy measurement step is a step of applying the reagent constituting the wetting reagent to the first member that has undergone the above surface treatment and determining wetting by the wetting determination method described below. (Method for determining wetness) An image acquisition step is performed to obtain an image of the component to which the above reagent has been applied, The acquired image is binarized in a process that distinguishes between areas where the reagent is present and areas where the reagent is not present. For the binarized image described above, the area calculation step involves determining the area of ​​the region where the reagent is present. A method for determining wetness, comprising a wetness determination step of determining wetness based on the ratio of the area where the reagent is present to the area on which the reagent is applied. (2) Before the above bonding process, further, A second surface treatment step is performed on the second member described above, A second surface free energy measurement step involves measuring the surface free energy of the second member subjected to the above surface treatment using a wetting reagent containing a dye, The system includes a second surface treatment level confirmation step, which determines whether or not the desired surface treatment has been applied based on the surface free energy measured by the second surface free energy measurement step described above. The above-described second surface free energy measurement step is a step of applying the reagent constituting the wetting reagent to the second member that has undergone the above surface treatment and determining wetting by the above wetting determination method, The method for manufacturing an adhesive product according to (1) above, wherein the bonding step is a step of bonding a second member, which has been determined to have undergone the desired surface treatment by the second surface treatment level confirmation step, onto the adhesive layer. (3) A method for producing the adhesive according to (1) or (2) above, wherein the dye is methylene blue trihydrate or a fluorescent material. (4) The above dye is a fluorescent material, The above image acquisition process is a process of acquiring an image of the component to which the wetting reagent has been applied while irradiated with a black light. The method for manufacturing an adhesive product according to any one of (1) to (3) above, wherein the binarization step is a step of converting the acquired image to grayscale and then binarizing it by setting a threshold. (5) The method for producing the adhesive according to any one of (1) to (4) above, wherein the materials of the first member and the second member are plastics containing polypropylene. (6) The method for producing the adhesive according to any one of (1) to (5) above, wherein the adhesive is a urethane-based adhesive, an epoxy-based adhesive, a modified silicone-based adhesive, or an acrylic-based adhesive. (7) The method for producing the adhesive according to any one of (1) to (6) above, wherein the surface treatment is plasma treatment or frame treatment.

Advantages of the Invention

[0008] As described below, according to the present invention, there is provided a method for producing an adhesive that exhibits excellent adhesiveness by previously checking the surface treatment level of a member with a wet reagent, and a method that does not require visual determination of wetting by the wet reagent. Further, according to the present invention, automation enables reduction of man-hours and simplification of processes (time shortening), leading to significant advantages in terms of cost.

Brief Description of the Drawings

[0009] [Figure 1] It is an image obtained by converting a photographed photo into grayscale for a B ratio of 100.0 in Table 1 (surface free energy (ring method): 36 mN / m). [Figure 2] It is a luminance graph of the dotted line in FIG. 1. [Figure 3] It is a binary image for a B ratio of 100.0 in Table 1 (surface free energy (ring method): 36 mN / m). [Figure 4] It is an image obtained by converting a photographed photo into grayscale for a B ratio of 9.0 in Table 2 (surface free energy (ring method): 38 mN / m). [Figure 5] It is a luminance graph of the dotted line in FIG. 4. [Figure 6] It is a binary image for a B ratio of 9.0 in Table 2 (surface free energy (ring method): 38 mN / m).

Embodiments for Carrying Out the Invention

[0010] The manufacturing method of the adhesive of the present invention will be described below. In the present specification, the numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. Each component may be used alone or in combination of two or more. Here, when two or more of each component are used in combination, the content of that component refers to the total content unless otherwise specified. Also, the reagent constituting the wetting reagent is also simply referred to as "reagent".

[0011] The manufacturing method of the adhesive of the present invention (hereinafter, also simply referred to as "the manufacturing method of the present invention") includes the following steps. (1) Surface treatment step A step of performing surface treatment on the first member (2) Surface free energy measurement step A step of measuring the surface free energy of the first member subjected to the above surface treatment using a wetting reagent containing a dye (3) Surface treatment level confirmation step A step of determining whether or not the desired surface treatment has been performed based on the surface free energy measured in the surface free energy measurement step (4) Adhesive application step A step of applying an adhesive to the first member determined to have been subjected to the desired surface treatment in the above surface treatment level confirmation step to form an adhesive layer, or applying a primer and then applying an adhesive to form a primer layer and an adhesive layer (5) Adhesion step A step of manufacturing an adhesive product having the first member, the adhesive layer, and the second member in this order, or having the first member, the primer layer, the adhesive layer, and the second member in this order by bonding the second member onto the above adhesive layer

[0012] Here, the surface free energy measurement step is a step of applying the reagents constituting the wetting reagent to the first member that has undergone the surface treatment and determining wetting according to the wetting determination method described below. Therefore, it is not necessary to visually determine wetting using the wetting reagent.

[0013] (Method for determining wetness) An image acquisition step is performed to obtain an image of the component to which the above reagent has been applied, The acquired image is binarized in a process that distinguishes between areas where the reagent is present and areas where the reagent is not present. For the binarized image described above, the area calculation step involves determining the area of ​​the region where the reagent is present. A method for determining wetness, comprising a wetness determination step of determining wetness based on the ratio of the area where the reagent is present to the area on which the reagent is applied.

[0014] The following describes each step.

[0015] [1] Surface treatment process The surface treatment process is a process of applying a surface treatment to the first component.

[0016] [First component] The first component used in the surface treatment process is not particularly limited, but specific examples include steel plates, resin-containing components (resin-containing components), etc. Furthermore, when the adhesive produced by the method of the present invention is used as an exterior component for an automobile, such as a car's tailgate, it is preferable that the first component is used as an inner component.

[0017] Specific examples of resins in the above-mentioned resin-containing components include polyolefin resins such as polyethylene, polypropylene, and polybutylene; methacrylic resins such as polymethyl methacrylate; polystyrene resins such as polystyrene, ABS, and AS; and polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate, polyethylene naphthalate (PEN), and poly-1,4-cyclohexyldimethylene terephthalate (PCT). Polyester resins; polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polyhexamethylene sevacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polydodecanamide (nylon 12), polyhexamethylene terephthalamide (nylon 6T), polyhexanemethylene isophthalamide (nylon 6I), polycaproamide / polyhexamethylene terephthalamide copolymer (nylon 6 / 6T), poly Examples include polyamide resins selected from nylon resins and nylon copolymer resins such as hexamethylene adipamide / polyhexamethylene terephthalamide copolymer (nylon 66 / 6T) and polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6I); polyvinyl chloride resin; polyoxymethylene (POM); polycarbonate (PC) resin; polyphenylene sulfide (PPS) resin; modified polyphenylene ether (PPE) resin; polyetherimide (PEI) resin; polysulfone (PSF) resin; polyethersulfone (PES) resin; polyketone resin; polyethernitrile (PEN) resin; polyetherketone (PEK) resin; polyetheretherketone (PEEK) resin; polyetherketoneketone (PEKK) resin; polyimide (PI) resin; polyamideimide (PAI) resin; fluororesins; modified resins obtained by modifying these resins or mixtures of these resins. In particular, polyolefin resins are preferred, polyethylene and polypropylene are more preferred, and polypropylene is even more preferred. The resin in the above-mentioned resin-containing member is preferably a crystalline thermoplastic resin.

[0018] The first component is preferably a plastic containing polypropylene. The first component may contain two or more types of resin.

[0019] If the first component is a resin-containing component, the resin content in the first component is preferably 10 to 100% by mass, and more preferably 60 to 100% by mass.

[0020] The first component is preferably a composite component containing resin and inorganic material. Examples of inorganic material include silica, titanium oxide, magnesium oxide, antimony oxide, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, calcium carbonate, talc, clay, mica, glass fiber, carbon black, graphite, and carbon fiber. The first component may contain two or more types of inorganic material.

[0021] When the first component is a base material (flat plate), its thickness is not particularly limited, but it is preferably between 1 μm and 100 mm.

[0022] Furthermore, if the dye of the wetting reagent used in the surface free energy measurement process is a dye other than a fluorescent dye, it is desirable that the color of the first component be a color that is distinguishable from the color of the above dye, but it is more preferable that it be white or off-white (e.g., milky white) for the reason that the wetting determination becomes more accurate. If the dye of the wetting reagent used in the surface free energy measurement process is a fluorescent dye, the color of the first component is not particularly limited.

[0023] [Surface treatment] As described above, the first component is subjected to a surface treatment process. Typically, the surface treatment increases the surface free energy of the first component.

[0024] The surface treatment is preferably a dry treatment. The dry treatment is preferably at least one selected from the group consisting of corona treatment, plasma treatment, flame treatment, itro treatment, UV treatment (ultraviolet irradiation treatment), and excimer treatment, more preferably flame treatment, plasma treatment, corona treatment, and itro treatment, even more preferably flame treatment and plasma treatment, and particularly preferably flame treatment.

[0025] The dry process may consist of either a single dry process (single pass) (e.g., a single sweep) or multiple unit dry processes (multiple passes) (e.g., multiple sweeps). If the dry process consists of multiple unit dry processes, the next unit dry process may be performed without any interval (continuous process), or the material may be allowed to cool after each unit dry process before the next unit dry process is performed (intermittent process).

[0026] [Frame processing] Flame treatment is a method of surface treatment using a flame. For frame processing, conventionally known methods such as using a burner can be used. The gas pressure for flame processing is preferably 0.005 to 10 MPa, and more preferably 0.01 to 1.5 MPa. The frame processing speed is preferably 100 to 2000 mm / second, and more preferably 200 to 1000 mm / second. When performing framing using a burner, the distance between the burner and the surface of the first member is preferably 10 to 600 mm, and more preferably 20 to 400 mm.

[0027] [Plasma treatment] Plasma treatment is a method of surface treatment using plasma discharge. Plasma processing is not particularly limited, but examples include atmospheric pressure plasma processing and vacuum plasma processing. The plasma gas (process gas) used in plasma processing is not particularly limited, but examples include nitrogen gas, helium gas, argon gas, and mixed gases obtained by mixing these gases with one or more of oxygen gas, carbon dioxide gas, and hydrogen gas. The plasma processing speed is preferably 10 to 1500 mm / second, and more preferably 50 to 1000 mm / second. When performing plasma processing using a plasma discharge nozzle, the distance between the plasma discharge nozzle and the surface of the first member is preferably 1 to 100 mm, and more preferably 5 to 50 mm.

[0028] [COVID-19 treatment] Corona treatment is a surface treatment method that uses corona discharge. The corona treatment speed is preferably 10 to 1000 mm / second, and more preferably 20 to 500 mm / second. When performing corona treatment using a corona discharge nozzle, the distance between the corona discharge nozzle and the surface of the material is preferably 1 to 100 mm, and more preferably 5 to 50 mm.

[0029] [Itro treatment] The Itro treatment involves introducing silane compounds or the like into a fuel gas to form a flame, and then using that flame to treat the surface, thereby forming a nano-level silicon oxide film on the surface and improving the adhesion between the surface and the adhesive. The gas pressure for the Itro treatment is preferably 0.005 to 10 MPa, and more preferably 0.01 to 1.5 MPa. The processing speed of the Itro is preferably 100 to 2000 mm / second, and more preferably 200 to 1000 mm / second. When performing the Itro treatment using a burner, the distance between the burner and the surface of the material is preferably 1 to 600 mm, and more preferably 20 to 400 mm.

[0030] [2] Surface free energy measurement process The surface free energy measurement step is a step in which the surface free energy of the first member that has been surface-treated in the surface treatment step described above is measured using a wetting reagent containing a dye. Specifically, the reagents constituting the wetting reagent are applied to the first component that has undergone surface treatment in the surface treatment process described above, and the surface free energy is measured by determining whether wetting has occurred.

[0031] [Wetting reagent] The wetting reagent used in the surface free energy measurement process is a wetting reagent containing a dye. Here, a wetting reagent refers to a series of reagents, or a combination (set) thereof, that have progressively increasing surface tension (surface free energy), as shown in JIS K 6768.

[0032] [Preferred Embodiment (Part 1)] The above wetting reagent allows for more accurate measurement of surface free energy (the discrepancy between the obtained surface free energy value and the surface free energy value calculated from the contact angle is small), A wetting reagent for surface free energy measurement containing a mixture of multiple solutions, The above mixture consists of two liquid compounds with different surface free energies. It is preferable that the above-mentioned mixtures are wetting reagents for surface free energy measurement (hereinafter also referred to as "wetting reagents of the present invention"), differing from each other only in the mixing ratio of the two liquid compounds described above. However, the two liquid compounds mentioned above satisfy the following condition X. (Condition X) For each liquid where the mixing ratio (A / B) of liquid compound A, which is the liquid compound with the smaller surface free energy by the ring method among the two liquid compounds described above, and liquid compound B, which is the liquid compound with the larger surface free energy by the ring method among the two liquid compounds described above, is 100 / 0, 80 / 20, 50 / 50, 20 / 80, and 0 / 100, when the surface free energy by the ring method is plotted against B / (A+B), the coefficient of determination of the linear approximation of the plot is 0.92 or higher.

[0033] In the following, the coefficient of determination for the wetting reagent of the present invention will also simply be referred to as the "coefficient of determination."

[0034] Since the wetting reagent of the present invention has a coefficient of determination of 0.92 or higher, it is considered that it can measure surface free energy more accurately. Although the reason is not clear, the inventors' studies have yielded two findings: (i) when the coefficient of determination of the two liquid compounds is large, the ease of mixing does not change even when the mixing ratio is changed, and (ii) this tendency is particularly pronounced when the coefficient of determination is 0.92 or higher. In other words, the two liquid compounds constituting the wetting reagent of the present invention, which have a coefficient of determination of 0.92 or higher, have extremely high compatibility. As a result, it is presumed that the wetting reagent of the present invention can measure surface free energy more accurately.

[0035] The wetting reagent of the present invention will be described in detail below.

[0036] <Multiple mixed solutions> The wetting reagent of the present invention comprises a mixture of several liquids, the mixture consisting of two liquid compounds with different surface free energies. Of the two liquid compounds described above, the one with the lower surface free energy will be designated as "Liquid Compound A," and the one with the higher surface free energy will be designated as "Liquid Compound B." The above surface free energy was obtained using the ring method. Hereafter, with respect to the wetting reagent of the present invention, unless otherwise specified, the surface free energy is the surface free energy obtained using the ring method. In this specification, the surface free energy obtained by the ring method was measured in accordance with JIS K 2241.

[0037] (mixed liquid) As described above, the above mixture consists of two liquid compounds (liquid compound A and liquid compound B) with different surface free energies.

[0038] (i) Liquid compounds The above liquid compound (liquid) is not particularly limited as long as it satisfies the condition X described later, but isopropyl alcohol, ethanol, methanol, 2-ethoxyethanol, dimethylformamide, propylene glycol, dimethyl sulfoxide, diethylene glycol, ethylene glycol, formamide, or water is preferred, and isopropyl alcohol, dimethylformamide, formamide, or water is more preferred, for the reason that the surface free energy can be measured more accurately.

[0039] Furthermore, among the above liquid compounds, liquid compound A is preferably isopropyl alcohol, ethanol, methanol, 2-ethoxyethanol, dimethylformamide, or propylene glycol, for the reason that the surface free energy can be measured more accurately.

[0040] Furthermore, among the above liquid compounds, liquid compound B is preferably dimethylformamide, dimethyl sulfoxide, diethylene glycol, ethylene glycol, formamide, or water, for the reason that the surface free energy can be measured more accurately.

[0041] (ii) Surface free energy The surface free energy of liquid compound A is not particularly limited as long as it is smaller than the surface free energy of liquid compound B, but it is preferably 20 to 40 mN / m for the reason that the surface free energy can be measured more accurately. The surface free energy of liquid compound B is not particularly limited as long as it is greater than the surface free energy of liquid compound A, but it is preferably 30 to 75 mN / m for the reason that the surface free energy can be measured more accurately. The difference between the surface free energy of liquid compound A and the surface free energy of liquid compound B is preferably 10 to 40 mN / m, for the reason that it allows for more accurate measurement of surface free energy.

[0042] (Mixing ratio) As described above, the above-mentioned mixed solutions differ from one another only in the mixing ratio of the two liquid compounds. In other words, in the above-mentioned mixtures, liquid compound A is the same liquid compound in all of them, liquid compound B is the same liquid compound in all of them, and the only difference between the above-mentioned mixtures is the mixing ratio (A / B) of liquid compound A to liquid compound B. In this specification, the mixing ratio (A / B) represents the ratio (volume ratio) when the total volume of liquid compound A and liquid compound B is set to 100. For example, if the volume ratio of liquid compound A is 80 and the volume ratio of liquid compound B is 20, it will be written as 80 / 20.

[0043] (B ratio) Furthermore, the ratio of liquid compound B to the total of liquid compound A and liquid compound B (B / (A+B)) (volume ratio) in each mixture is also called the B ratio. For example, if the volume ratio of liquid compound A is 80 and the volume ratio of liquid compound B is 20, then the ratio of B will be 20.

[0044] When the above-mentioned mixtures are arranged in order of their B ratio, the difference in B ratio between adjacent mixtures is preferably 10 or less, more preferably 7 or less, and even more preferably 5 or less, for the reason that surface free energy can be measured more accurately. There is no particular lower limit to the difference in B ratio, but it is preferably 1 or more, and more preferably 3 or more.

[0045] As described above, the two liquid compounds (liquid compound A and liquid compound B) that make up the above mixture have different surface free energies. Here, liquid compound B has a higher surface free energy than liquid compound A. Therefore, when the above mixtures are arranged in order of B ratio, the smaller the B ratio, the lower the surface free energy, and the larger the B ratio, the higher the surface free energy. In this case, the difference in surface free energy between adjacent mixed liquids is preferably 10 mN / m or less, and more preferably 5 mN / m or less, for the reason that surface free energy can be measured more accurately. There is no particular lower limit to the above difference in surface free energy, but it is preferably 1 mN / m or more.

[0046] (Condition X) The two liquid compounds that make up the above mixture satisfy the following condition X. (Condition X) For each liquid where the mixing ratio (A / B) of liquid compound A (the liquid compound with the lower surface free energy by the ring method) and liquid compound B (the liquid compound with the higher surface free energy by the ring method) is 100 / 0, 80 / 20, 50 / 50, 20 / 80, and 0 / 100, when the surface free energy by the ring method is plotted against B / (A+B), the coefficient of determination (R) of the linear approximation of the plot is 2 The value is 0.92 or higher.

[0047] The definition of the mixing ratio (A / B) is the same as the mixing ratio described above. Furthermore, the definition of B / (A+B) is the same as the B ratio mentioned above.

[0048] Furthermore, the solutions with mixing ratios (A / B) of 100 / 0, 80 / 20, 50 / 50, 20 / 80, and 0 / 100 described in condition X may or may not constitute the wetting reagent of the present invention. If any of the solutions with mixing ratios (A / B) of 100 / 0, 80 / 20, 50 / 50, 20 / 80, and 0 / 100 contain a solution that does not constitute a wetting reagent, prepare that solution separately and determine whether it satisfies condition X.

[0049] (i) Linear approximation The linear approximation of the above plot is a linear approximation using the least squares method.

[0050] (ii) coefficient of determination The above coefficient of determination indicates the deviation between the surface free energy calculated from the linear approximation curve and the actual surface free energy, and the closer it is to 1, the smaller the deviation. The above coefficient of determination (R 2 ) is obtained by the following formula (1). R 2 =S R / S T (1) S R represents the sum of (Y - average y) of each liquid with mixing ratios (A / B) of 100 / 0, 80 / 20, 50 / 50, 20 / 80, and 0 / 100. Here, Y represents the surface free energy calculated from the linear approximation curve, and average y represents the average value of the measured values of the surface free energy. Also, S T represents the sum of (y - average y) of each liquid with mixing ratios (A / B) of 100 / 0, 80 / 20, 50 / 50, 20 / 80, and 0 / 100. Here, y represents the measured value of the surface free energy. Average y is as described above.

[0051] Since the above coefficient of determination can measure the surface free energy more accurately, it is preferably 0.93 or more, more preferably 0.94 or more, still more preferably 0.95 or more, still more preferably 0.96 or more, still more preferably 0.97 or more, still more preferably 0.98 or more, and still more preferably 0.99 or more. The upper limit of the above coefficient of determination is not particularly limited and is 1.

[0052] The method for obtaining a combination of two liquid compounds that satisfies condition X is not particularly limited. For example, the coefficient of determination is obtained as described above for various combinations of two liquid compounds with different surface free energies, and a combination that satisfies condition X is selected. ​​​​Examples of combinations of two liquid compounds that satisfy condition X include methanol / diethylene glycol, isopropyl alcohol / dimethylformamide, dimethylformamide / formamide, ethanol / dimethyl sulfoxide, propylene glycol / water, methanol / ethylene glycol, 2-ethoxyethanol / ethylene glycol, isopropyl alcohol / 2-ethoxyethanol, ethanol / 2-ethoxyethanol, ethanol / dimethylformamide, ethanol / dimethyl sulfoxide, methanol / 2-ethoxyethanol, methanol / dimethylformamide, methanol / propylene glycol, methanol / dimethyl sulfoxide, dimethylformamide / dimethyl sulfoxide, dimethylformamide / diethylene glycol, dimethylformamide / ethylene glycol, dimethylformamide / water, dimethyl sulfoxide / ethylene glycol, dimethyl sulfoxide / formamide, and dimethyl sulfoxide / water.

[0053] <Other liquids> The wetting reagent of the present invention may also include, as a liquid other than the above-mentioned mixture of liquids, a liquid consisting only of liquid compound A that constitutes the mixture of liquids contained in the wetting reagent of the present invention (a liquid with a B ratio of 0), and a liquid consisting only of liquid compound B that constitutes the mixture of liquids contained in the wetting reagent of the present invention (a liquid with a B ratio of 100). Hereafter, the liquid consisting solely of liquid compound A, the aforementioned mixed liquid, and the liquid consisting solely of liquid compound B will all be collectively referred to as "reagents."

[0054] (A liquid consisting solely of liquid compound A) The preferred range for the difference between the B ratio of a solution consisting only of liquid compound A (i.e., 0) and the B ratio of the mixture with the smallest B ratio among the multiple mixtures contained in the wetting reagent of the present invention is the same as the difference in B ratios between adjacent mixtures among the multiple mixtures described above. Furthermore, the preferred range for the difference between the surface free energy of a liquid consisting only of liquid compound A and the surface free energy of the mixture containing the smallest ratio of B (and therefore the smallest surface free energy) among the multiple mixtures included in the wetting reagent of the present invention is the same as the difference in surface free energies between adjacent mixtures among the multiple mixtures described above.

[0055] (A liquid consisting solely of liquid compound B) The preferred range for the difference between the B ratio of a solution consisting solely of liquid compound B (i.e., 100) and the B ratio of the mixture with the highest B ratio among the multiple mixtures contained in the wetting reagent of the present invention is the same as the difference in B ratios between adjacent mixtures among the multiple mixtures described above. Furthermore, the preferred range for the difference between the surface free energy of a liquid consisting only of liquid compound B and the surface free energy of the mixture with the highest B ratio (highest surface free energy) among the multiple mixtures contained in the wetting reagent of the present invention is the same as the difference in surface free energies between adjacent mixtures among the multiple mixtures described above.

[0056] [Preferred Embodiment (Part 2)] The above wetting reagent allows for more accurate measurement of surface free energy (the discrepancy between the obtained surface free energy value and the surface free energy value calculated from the contact angle is small), A wetting reagent set for surface free energy measurement, comprising a plurality of the wetting reagents of the present invention as described above, Preferably, the above-mentioned multiple wetting reagents are a wetting reagent set for surface free energy measurement (hereinafter also simply referred to as "the wetting reagent set of the present invention") in which at least one of the two liquid compounds is different from each other.

[0057] The wetting reagent included in the wetting reagent set of the present invention is as described above.

[0058] The wetting reagent set of the present invention allows for more accurate measurement of surface free energy. Therefore, when the multiple wetting reagents of the present invention included in the wetting reagent set of the present invention are arranged in order of increasing surface free energy of liquid compound A of each wetting reagent, it is preferable that adjacent wetting reagents share the same liquid compound B as the wetting reagent with the lower surface free energy of liquid compound A, and the same liquid compound A as the wetting reagent with the higher surface free energy of liquid compound B. For example, consider a wetting reagent set containing two wetting reagents: one containing liquid compound A (ethanol) and the other containing liquid compound B (2-ethoxyethanol). In this case, the liquid compound B (2-ethoxyethanol) of the wetting reagent with the lower surface free energy of liquid compound A (the former wetting reagent) and the liquid compound A (2-ethoxyethanol) of the wetting reagent with the higher surface free energy of liquid compound A (the latter wetting reagent) are common to both. Therefore, this wetting reagent set corresponds to the preferred embodiment described above.

[0059] [Pigment] As mentioned above, the wetting reagent used in the surface free energy measurement process contains a dye. Here, a pigment is a substance that gives color through the absorption or emission of visible light.

[0060] The above dyes include fluorescent dyes. Here, a fluorescent dye is a substance that absorbs light (for example, a black light) and emits fluorescence. Some tin catalysts and organometallic (transition metal) compounds emit fluorescence when irradiated with a black light, and these substances are also included in the category of fluorescent dyes.

[0061] Furthermore, if the above-mentioned dye is a dye other than a fluorescent dye, it is desirable that the color of the above-mentioned dye be a color that is distinguishable from the color of the first component.

[0062] The above dye is preferably a fluorescent dye. While there are no particular restrictions on the fluorescent dyes used, specific examples include 2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole, FZ-SB (Blue), FZ-5009 (White), FA-48 (Blue), and BASF Lumogen F Dyes (Yellow 083, Yellow 170, Orange 240, Pink 285, Red 305, Violet 570).

[0063] The concentration of the dye is not particularly limited, but is preferably 0.01 to 0.10% by mass, and more preferably 0.01 to 0.05% by mass.

[0064] [Measurement of surface free energy] As described above, in the surface free energy measurement step, the surface free energy of the first member that has been surface-treated in the surface treatment step described above is measured using the wetting reagent described above. Specifically, the reagents constituting the wetting reagent described above (a series of reagents) are applied to the first component that has undergone surface treatment in the surface treatment process described above, and the surface free energy is measured by determining whether it is wet or not. For example, reagents included in the wetting reagent (a series of reagents) are applied to the first component in order from the lowest surface free energy (e.g., ring method), and wetting is determined. Generally, reagents with low surface free energy wet easily, and reagents with high surface free energy wet less easily. The surface free energy of the reagent with the highest surface free energy among those determined to be wetting becomes the surface free energy of the first component. However, if the reagent with the highest surface free energy among the reagents included in the wetting reagent (a series of reagents) is determined to be wetting, it means that the surface free energy of the first component exceeds the range of surface free energy that can be measured by that wetting reagent.

[0065] [Method for determining wetness] In this invention, wetting is determined by the following wetting determination method. (Method for determining wetness) (i) Image acquisition process The process of acquiring an image of a component to which the above-mentioned reagent has been applied. (ii) Binarization process The process of binarizing the acquired image so that areas where the reagent is present and areas where the reagent is not present can be distinguished. (iii) Area calculation process The process of determining the area of ​​the region where the above reagent is present in the binarized image described above. (iv) Wetting detection process A process to determine wetting based on the ratio of the area where the reagent is present to the area where the reagent is applied.

[0066] The following describes each step.

[0067] [Image acquisition process] The image acquisition process involves acquiring images of the components to which the reagent has been applied. If the dye contained in the wetting reagent is a fluorescent dye, it is preferable to take a photograph while illuminating it with a black light.

[0068] [Binarization process] The binarization process is a step in which the image acquired in the image acquisition process is binarized so that areas where the reagent is present and areas where the reagent is not present can be distinguished. Specific examples of methods for binarizing an image so that areas with and without a reagent can be distinguished include converting the acquired image to grayscale and then setting a threshold for binarization. Methods for setting the threshold include using a straight line from one end of the grayscale image to the other as a reference for the valleys in a graph (hereinafter also called a "luminance graph") with the horizontal axis representing the direction of the line and the vertical axis representing luminance, or using the valleys in the density histogram of the grayscale image as a reference for the threshold.

[0069] For example, if a component (the first component) is black, and the dye contained in the wetting reagent is a fluorescent dye, and a photograph of the first component coated with the reagent is taken while irradiated with a black light, the areas where the reagent is present will be bright, and the areas where the reagent is absent will be dark. Therefore, if the photograph (image) is converted to grayscale and then binarized by setting a threshold based on the dips in the brightness graph or density histogram, the areas where the reagent is present will be white, and the areas where the reagent is absent will be black.

[0070] Furthermore, for example, if the component (first component) is white, and the dye contained in the wetting reagent is methylene blue trihydrate, and a photograph is taken of the first component coated with the reagent, the areas where the reagent is present will appear blue, and the areas where the reagent is absent will appear white. Therefore, if the photograph (image) is converted to grayscale and then binarized by setting a threshold based on the valleys in the brightness graph or density histogram, the areas where the reagent is present will appear black, and the areas where the reagent is absent will appear white.

[0071] [Area calculation process] The area calculation step is the process of determining the area of ​​the region where the reagent is present in the binarized image described above.

[0072] [Wetting detection process] The wetting determination step is a step in which wetting is determined based on the ratio of the area where the reagent is present to the area on which the reagent has been applied. For example, one method is to determine if something is wet if the above percentage is 65% or higher, and not wet if the above percentage is less than 65%.

[0073] [3] Surface treatment level confirmation process The surface treatment level confirmation step is a step in which the desired surface treatment has been applied, based on the surface free energy measured by the surface free energy measurement step described above. The desired surface treatment means that a surface treatment level that does not cause problems with adhesion has been achieved. The standard surface free energy varies depending on the material of the components, the type of adhesive, the application of the bonded material, etc. However, if the materials of the first and second components are polypropylene and the adhesive is a urethane-based adhesive, for example, one method is to set it to 36 mN / m.

[0074] [4] Adhesive application process The adhesive application step involves applying an adhesive to the first member, which has been determined to have undergone the desired surface treatment as determined by the surface treatment level confirmation step described above, to form an adhesive layer, or applying a primer first and then applying the adhesive to form a primer layer and an adhesive layer. Conventional known primers can be used.

[0075] [glue] The adhesive is not particularly limited, but specific examples include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, α-olefin adhesives, ether adhesives, ethylene-vinyl acetate resin adhesives, epoxy resin adhesives, vinyl chloride resin adhesives, chloroprene rubber adhesives, cyanoacrylate adhesives, aqueous polymer-isocyanate adhesives, styrene-butadiene rubber adhesives, nitrile rubber adhesives, nitrocellulose adhesives, reactive hot melt adhesives, phenol resin adhesives, modified silicone adhesives, polyamide resin adhesives, polyimide adhesives, Examples include polyurethane resin adhesives, polyolefin resin adhesives, polyvinyl acetate resin adhesives, polystyrene resin solvent adhesives, polyvinyl alcohol adhesives, polyvinylpyrrolidone resin adhesives, polyvinyl butyral resin adhesives, polybenzimidazole adhesives, polymethacrylate resin adhesives, melamine resin adhesives, urea resin adhesives, and resorcinol adhesives. Preferably, it is at least one selected from the group consisting of urethane adhesives, epoxy adhesives, modified silicone adhesives, and acrylic adhesives, and more preferably a urethane adhesive. Urethane-based adhesives and epoxy adhesives are preferably one-component or two-component types. Examples of one-component urethane adhesives include moisture-curing adhesives containing a urethane prepolymer having an isocyanate group. Examples of two-component urethane adhesives include adhesives containing a main component containing a polyol and a curing agent containing an isocyanate. Examples of one-component epoxy adhesives include room-temperature curing or heat-curing adhesives containing a latent curing agent such as ketimine, oxazolidine, or aldimine compounds, and a liquid epoxy resin. Examples of two-component epoxy resin adhesives include adhesives containing a main component selected from liquid epoxy resins (e.g., bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, or novolac type epoxy resin, etc.) and a curing agent (e.g., amine-based curing agents such as linear aliphatic amines, cyclic aliphatic amines, or aromatic amines, nitrogen-containing aromatics such as imidazole compounds, amidoamine curing agents, etc.).

[0076] [How to grant] The method for applying adhesive to the surface of the first component after surface treatment is not particularly limited, but examples include dip coating, double roll coater, slit coater, air knife coater, wire bar coater, slide hopper, spray coating, blade coater, doctor coater, squeeze coater, reverse roll coater, transfer roll coater, extension coater, curtain coater, dip coater, die coater, gravure roll coating method, screen printing method, dip coating method, spray coating method, spin coating method, and inkjet method.

[0077] The thickness of the adhesive layer formed is not particularly limited, but it is preferably 0.1 to 20 mm.

[0078] [5] Adhesion process The bonding process involves bonding a second member onto the adhesive layer formed in the adhesive application process described above, thereby producing a bonded product having the first member, the adhesive layer, and the second member in that order, or the first member, the primer layer, the adhesive layer, and the second member in that order.

[0079] [Second component] The second member is not particularly limited, and its specific examples and preferred embodiments are the same as those described above for the first member.

[0080] [Method of bonding] The method for bonding the second component onto the adhesive layer is not particularly limited, but examples include pressing the components together. Furthermore, after bonding the second component, heat treatment or other methods may be performed to cure the adhesive.

[0081] [6] Other processes The manufacturing method of the present invention is Before the bonding process described above, The second surface treatment step involves applying a surface treatment to the second member described above, A second surface free energy measurement step involves measuring the surface free energy of the second member subjected to the above surface treatment using a wetting reagent containing a dye, The system may also include a second surface treatment level confirmation step, which determines whether or not the desired surface treatment has been applied based on the surface free energy measured by the second surface free energy measurement step described above. Here, the second surface free energy measurement step is a step of applying the reagents constituting the wetting reagent to the second member that has undergone the surface treatment and determining wetting using the wetting determination method. Furthermore, the bonding step described above is a step of bonding a second member, which has been determined to have received the desired surface treatment by the second surface treatment level confirmation step, onto the adhesive layer formed by the adhesive application step described above.

[0082] The second surface treatment process, the second surface free energy measurement process, and the second surface treatment level confirmation process are the same as the surface treatment process, surface free energy measurement process, and surface treatment level confirmation process described above, except that the second member is used as the first member.

[0083] [7] Purpose Because the adhesive produced by the manufacturing method of the present invention has excellent adhesive properties, it is particularly useful for interior and exterior components of automobiles, such as automobile bodies, front doors, rear doors, tailgates, front bumpers, rear bumpers, and rocker moldings. [Examples]

[0084] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0085] [Manufacturing of adhesives] The adhesives were manufactured as follows:

[0086] [Example 1]

[0087] <Surface treatment process> One surface of a substrate (width: 25 mm, length: 120 mm, thickness: 3 mm) (first component) made of polypropylene composite material (TSOP#5 black, manufactured by Prime Polymer Co., Ltd.) was subjected to flame treatment. A flame treatment device, FLAME TEATER, manufactured by Alcogas Co., Ltd. (using propane gas, air flow rate 100 L / min, gas flow rate 3.7 L / min), was used for the flame treatment. The distance between the burner and the substrate was 72 mm. The speed at which the burner was moved relative to the fixed substrate was 800 mm / second.

[0088] <Surface Free Energy Measurement Process> The surface free energy of the first surface-treated component was measured using the following wetting reagent. Specifically, each reagent constituting the wetting reagent was applied to a first component that had undergone surface treatment, and wetting was determined according to the wetting determination method described below.

[0089] (Wetting reagent) As wetting reagents, we used sets of wetting reagents with varying mixing ratios of isopropanol (IPA) and dimethylformamide (DMF), and sets of wetting reagents with varying mixing ratios of dimethylformamide (DMF) and formamide. Table 1 shows the wetting reagents with varying mixing ratios of IPA and DMF. Table 2 shows the wetting reagents with varying mixing ratios of DMF and formamide. In Tables 1 and 2, the B ratio is the ratio of liquid compound B (B / (A+B)) (volume ratio) to the total of liquid compound A (the liquid compound with the lower surface free energy of the two liquid compounds) and liquid compound B (the liquid compound with the higher surface free energy of the two liquid compounds), which is 100. Furthermore, each reagent constituting the wetting reagent contained a fluorescent material (2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole)) dissolved as a dye. The dye concentration was 0.03% by mass. Furthermore, wetting reagents with varying mixing ratios of isopropanol (IPA) and dimethylformamide (DMF), and wetting reagents with varying mixing ratios of dimethylformamide (DMF) and formamide, both correspond to the wetting reagents of the present invention described above, and their coefficients of determination are 0.96 and 0.99, respectively. A set of wetting reagents with varying mixing ratios of isopropanol (IPA) and dimethylformamide (DMF), and a set of wetting reagents with varying mixing ratios of dimethylformamide (DMF) and formamide, corresponds to the wetting reagent set of the present invention described above.

[0090] (Method for determining wetness)

[0091] (i) Image acquisition process A photograph of the first component, to which the reagent had been applied, was taken while it was illuminated with a black light.

[0092] (ii) Binarization process The captured photographs were converted to grayscale (8-bit) using the image analysis software ImageJ. Bright areas indicate the presence of the reagent, and dark areas indicate the absence of the reagent. Then, the images were binarized using a threshold of 50 Gray Values ​​(50 out of 256 gradations), based on the dips in the brightness graph. Figure 1 shows a grayscale image of a photograph taken for a B ratio of 100.0 (surface free energy (ring method): 36 mN / m) as shown in Table 1. Figure 2 shows the dotted brightness graph of Figure 1. Figure 3 shows a binarized image for a B ratio of 100.0 (surface free energy (ring method): 36 mN / m) as shown in Table 1. Figure 4 shows a grayscale image of a photograph taken for a B ratio of 9.0 (surface free energy (ring method): 38 mN / m) as shown in Table 2. Figure 5 shows the dotted line brightness graph of Figure 4. Figure 6 shows a binarized image for a B ratio of 9.0 (surface free energy (ring method): 38 mN / m) as shown in Table 2.

[0093] (iii) Area calculation process For the binarized image, the area of ​​the white areas (areas where the reagent was present) was calculated. Specifically, edge extraction was performed on the binarized image, and the area was calculated.

[0094] (iv) Wetting detection process Wetting was determined based on the ratio of the area where the reagent was present (the area calculated in the area calculation step) to the area where the reagent was applied. If the above ratio was 65% or higher, it was determined to be wet (○), and if it was less than 65%, it was determined to be not wet (×). Tables 1 and 2 show the above ratios and the results of the wetting determination. Note that in the table, there are cases where the ratio exceeds 100%, which is because the reagent spread beyond the area where it was applied. Among the reagents that were determined to be wet (○), the reagent with the highest surface free energy (ring method) was 36 mN / m. Therefore, the surface free energy (wetting reagent) of the first component that underwent surface treatment was measured to be 36 mN / m.

[0095] [Table 1]

[0096] [Table 2]

[0097] <Surface treatment level confirmation process> If the surface free energy (wetting reagent) measured by the surface free energy measurement process is 36 mN / m or higher, it can be said that the desired surface treatment has been applied. As described above, the surface free energy (wetting reagent) of the first component that underwent surface treatment was measured to be 36 mN / m, so it was determined that the desired surface treatment had been applied.

[0098] <Adhesive application process> An adhesive layer was formed on the surface-treated first component by applying the adhesive prepared as described below, such that the bonding area was 25 mm x 10 mm and the adhesive thickness was 3 mm.

[0099] (Preparation of adhesive) Each component in Table 3 below was mixed using a stirrer in the composition (parts by mass) shown in the table to prepare the main component shown in the upper row of the table and the curing agent shown in the lower row of the table. Next, 100g of the prepared main component and 10g of the hardener were mixed to obtain an adhesive. The details of each component in Table 3 are as follows: • Polymer 1: Urethane prepolymer synthesized as described below 700 g of polyoxypropylenediol (average molecular weight 2000), 300 g of polyoxypropylenetriol (average molecular weight 3000), and 499 g of 4,4'-diisocyanate phenylmethane (molecular weight 250) were mixed (at this time NCO / OH = 2.0), and 500 g of diisononyl phthalate was added. The mixture was stirred under a nitrogen atmosphere at 80°C for 12 hours to synthesize a urethane prepolymer (polymer 1) containing 2.10% isocyanate groups. Compound 1: Isocyanurate derivative of hexamethylene diisosinate (TolonateHDT, manufactured by Perstorp) Compound 2: Dimalon (manufactured by Yasuhara Chemical Co., Ltd.) • Compound 3:3 functional polypropylene polyol (Exsenol 1030, manufactured by Asahi Glass Co., Ltd.) Compound 4: Polybutadiene diol (Poly bd R-45HT, manufactured by Idemitsu Kosan Co., Ltd., hydroxyl value: 0.8 mol / kg) Compound 5: Terpineol (manufactured by Yasuhara Chemical Co., Ltd.) • Carbon Black: #200MP (manufactured by Shin-Nippon Chemical Carbon Co., Ltd.) • Calcium carbonate 1: Super S (manufactured by Maruo Calcium Co., Ltd.) • Calcium carbonate 2: Calfine 200 (manufactured by Maruo Calcium Co., Ltd.) • Plasticizer 1: Diisononyl phthalate (manufactured by J-Plus Co., Ltd.) • Catalyst 1: Dimorpholino diethyl ether (manufactured by Sunapro Co., Ltd.)

[0100] [Table 3]

[0101] <Adhesion process> A second component (width: 25 mm, length: 120 mm, thickness: 3 mm) made of polypropylene composite material (TSOP#5 black, manufactured by Prime Polymer Co., Ltd.) was bonded onto the adhesive layer described above, pressed together, and left for 3 days in an environment of 23°C and 50% relative humidity. In this way, an adhesive was obtained having the first component, the adhesive layer (the layer in which the adhesive layer has hardened), and the second component in this order.

[0102] [Example 2]

[0103] <Surface treatment process> The surface treatment process was carried out according to the same procedure as in Example 1 described above, except that a white substrate (polypropylene composite material (TSOP#5 white, manufactured by Prime Polymer Co., Ltd.)) was used as the first component.

[0104] <Surface Free Energy Measurement Process> The surface free energy of the first surface-treated component was measured using the following wetting reagent. Specifically, each reagent constituting the wetting reagent was applied to a first component that had undergone surface treatment, and wetting was determined according to the wetting determination method described below.

[0105] (Wetting reagent) The same wetting reagent used in Example 1 described above was used, except that methylene blue trihydrate was used as the wetting reagent and as the dye.

[0106] (Method for determining wetness)

[0107] (i) Image acquisition process The image acquisition process was carried out according to the same procedure as in Example 1 described above, except that a black light was not used.

[0108] (ii) Binarization process The binarization process was performed following the same procedure as in Example 1 described above.

[0109] (iii) Area calculation process The area calculation process was performed following the same procedure as in Example 1 described above.

[0110] (iv) Wetting detection process Wetting was determined based on the ratio of the area where the reagent was present (the area calculated in the area calculation step) to the area where the reagent was applied. If the above ratio was 65% or higher, it was determined to be wet (○), and if it was less than 65%, it was determined to be not wet (×). Tables 4 and 5 show the above ratios and the results of the wetting determination. Note that in the table, there are cases where the ratio exceeds 100%, which is because the reagent spread beyond the area where it was applied. Among the reagents that were determined to be wet (○), the one with the largest surface free energy (ring method) was 36 mN / m. Therefore, the surface free energy (wetting reagent) of the first component that underwent surface treatment was measured to be 36 mN / m.

[0111] [Table 4]

[0112] [Table 5]

[0113] <Surface treatment level confirmation process> If the surface free energy (wetting reagent) measured by the surface free energy measurement process is 36 mN / m or higher, it can be said that the desired surface treatment has been applied. As described above, the surface free energy (wetting reagent) of the first component that underwent surface treatment was measured to be 36 mN / m, so it was determined that the desired surface treatment had been applied.

[0114] <Adhesive application process> The adhesive application process was carried out according to the same procedure as in Example 1 described above.

[0115] <Adhesion process> The bonding process was carried out according to the same procedure as in Example 1 described above. In this way, an adhesive product was obtained having the first member, the adhesive layer (the layer in which the adhesive layer has hardened), and the second member in that order.

[0116] [Comparative Example 1] The adhesive was manufactured following the same procedure as in Example 1, except that the distance between the burner and the substrate during the flame treatment process of the surface treatment was changed to 78 mm. In the surface free energy measurement process, the surface free energy (wetting reagent) of the first member was 33 mN / m, which is less than 36 mN / m. Therefore, it was determined that the desired surface treatment had not been performed. However, in Comparative Example 1, the adhesive was manufactured using the first member, which was determined to have not received the desired surface treatment.

[0117] [Comparative Example 2] An attempt was made to manufacture the adhesive following the same procedure as in Example 1, except that the dye was not dissolved in each of the reagents constituting the wetting reagent. However, the images acquired in the image acquisition step could not be binarized in such a way that the areas where the reagent was present and the areas where the reagent was not present could not be distinguished, and the surface free energy of the surface-treated first member could not be measured, so the manufacture of the adhesive was discontinued.

[0118] [Evaluation of adhesion (failure state, fracture strength)] Shear tests (hot at 90°C) were performed on the adhesives obtained from Example 1, Example 2, and Comparative Example 1, and the fracture state was visually confirmed. The fracture strength (shear strength) was measured. As a result, the adhesive obtained in Example 1 exhibited excellent adhesion, with cohesive failure of the adhesive layer and a fracture strength of 1.6 MPa. Similarly, the adhesive obtained in Example 2 also exhibited excellent adhesion, with cohesive failure of the adhesive layer and a fracture strength of 1.6 MPa. On the other hand, the adhesive obtained in Comparative Example 1 exhibited interfacial delamination between the adhesive layer and the member, with a fracture strength of 1.1 Pa, indicating insufficient adhesion.

Claims

1. A surface treatment step involves applying a surface treatment to the first component, A surface free energy measurement step, in which the surface free energy of the first member subjected to the surface treatment is measured using a wetting reagent containing a dye, A surface treatment level confirmation step is performed to determine whether or not the desired surface treatment has been applied, based on the surface free energy measured by the surface free energy measurement step. The first member, which has been determined to have undergone the desired surface treatment according to the surface treatment level confirmation step, is to be given an adhesive to form an adhesive layer, or to be given a primer and then an adhesive to form a primer layer and an adhesive layer, in an adhesive application step, A method for manufacturing an adhesive, comprising an bonding step of bonding a second member onto the adhesive layer to produce an adhesive having a first member, an adhesive layer, and a second member in that order, or a first member, a primer layer, an adhesive layer, and a second member in that order, A method for manufacturing an adhesive, wherein the surface free energy measurement step is a step of applying a reagent constituting the wetting reagent to a first member that has undergone the surface treatment and determining wetting by the wetting determination method described below. (Method for determining wetness) An image acquisition step is to acquire an image of the component to which the reagent has been applied, The acquired image is binarized in a step of distinguishing between areas where the reagent is present and areas where the reagent is not present. The area calculation step involves determining the area of ​​the region where the reagent is present in the binarized image, A method for determining wetness, comprising a wetness determination step of determining wetness based on the ratio of the area where the reagent is present to the area on which the reagent is applied. However, the dye is a fluorescent material, The image acquisition step is a step of acquiring an image of the member to which the wetting reagent has been applied while irradiated with a black light. The binarization step is a process of converting the acquired image to grayscale and then binarizing it by setting a threshold.

2. Before the aforementioned bonding process, further, A second surface treatment step involves applying a surface treatment to the second member, A second surface free energy measurement step involves measuring the surface free energy of the second member that has undergone the surface treatment using a wetting reagent containing a dye, The system includes a second surface treatment level confirmation step, which determines whether or not the desired surface treatment has been applied based on the surface free energy measured by the second surface free energy measurement step, The second surface free energy measurement step is a step of applying the reagent constituting the wetting reagent to the second member that has undergone the surface treatment and determining wetting by the wetting determination method, The method for manufacturing an adhesive product according to claim 1, wherein the bonding step is a step of bonding a second member, which has been determined to have undergone a desired surface treatment by the second surface treatment level confirmation step, onto the adhesive layer.

3. The method for manufacturing an adhesive according to claim 1 or 2, wherein the material of the first member and the second member is a plastic containing polypropylene.

4. A method for producing an adhesive product according to any one of claims 1 to 3, wherein the adhesive is a urethane-based adhesive, an epoxy-based adhesive, a modified silicone-based adhesive, or an acrylic-based adhesive.

5. The method for manufacturing an adhesive according to any one of claims 1 to 4, wherein the surface treatment is plasma treatment or flame treatment.

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