JP2016078264A - Joint body, and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joint body which has high adhesive power between base materials themselves and in which the stress to be caused by a linear expansion coefficient difference between the base materials is dispersed to suppress a strain.SOLUTION: The joint body has a first base material, a second base material and an adhesive layer for connecting the first base material to the second base material. The joint body is characterized in that the elastic modulus and/or Martens hardness of the adhesive layer are raised as it goes toward the central part thereof from the peripheral part.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a joined body. The present invention also relates to a method for manufacturing a joined body.

  It is well known that adhesives are frequently used for joining articles, and their uses are diverse. For example, a wide range of applications are known, including automobiles, aircrafts and other vehicle-related products, roofs, walls, floors and other building-related products, as well as adhesives used in electrical equipment, office equipment, household products and the like. Among them, structural adhesives are widely used in industrial applications.

  Adhesives are often used for joining dissimilar materials. At this time, a problem arises, but there is a difference in coefficient of linear expansion between the materials. When dissimilar materials having different linear expansion coefficients are bonded, the adhesive force is lowered due to deterioration with time due to stress due to the difference in linear expansion coefficient, and the bonding surface is easily peeled off. For this reason, in the adhesion of different materials, it is an extremely important factor to disperse the stress caused by the difference in linear expansion coefficient of each material.

  In JP 2005-298638 A (Patent Document 1), while reducing the initial deviation due to curing shrinkage of the adhesive, the internal stress accumulated during curing is reduced, and the positional deviation caused by the passage of time of the adhesive is reduced. As a bonding method that can be reduced, a method of irradiating a part of the adhesive layer with energy rays and scanning the irradiated portion to sequentially cure the entire adhesive layer is disclosed.

  In Japanese Patent Application Laid-Open No. 2007-237680 (Patent Document 2), in consideration of energy dispersion against external impact, a plurality of adhesives having different physical properties are applied in parallel on the adhesive surface with the substrate. Thus, a method for improving the impact resistance performance while maintaining the adhesive force between the substrates by separately painting in different regions is disclosed.

JP 2005-298638 A JP 2007-237680 A

  Although the technique described in Patent Document 1 aims to reduce the internal stress of the adhesive, it is necessary to accurately irradiate energy rays along a predetermined scanning path, and the apparatus configuration is complicated and the cost is increased. Moreover, although the said technique can reduce the internal stress produced by hardening shrinkage | contraction of an adhesive agent, it does not aim at reducing the stress resulting from the difference in the linear expansion coefficient between different materials.

  In the technique described in Patent Document 2, it is necessary to separately apply a plurality of types of adhesives. In addition, in the interface region of different types of adhesives, the stress distribution is non-uniform due to discontinuous resin physical properties, and it is considered that the stress caused by the difference in the linear expansion coefficient between different materials does not reach.

  The present invention was created in view of the above circumstances, and a bonded body in which the adhesive strength between substrates is high, and the stress caused by the difference in linear expansion coefficient between the substrates is dispersed to suppress distortion. The main issue is to provide.

  The present inventors diligently studied in order to solve the above-mentioned problems, and when joining the base materials with an adhesive, the inventors focused on the fact that stress tends to concentrate on the peripheral edge of the adhesive interposed on the joint surface. . And while using the adhesive with a low elastic modulus for the peripheral part where stress is likely to concentrate, it was found that using an adhesive with a high elastic modulus inside is effective for solving the problem. . The present invention has been completed based on this finding.

  That is, in one aspect, the present invention is a joined body having a first base material, a second base material, and an adhesive layer that connects the first base material and the second base material, It is a joined body in which the elastic modulus and / or Martens hardness of the agent layer increases from the peripheral portion toward the central portion.

  In one embodiment of the joined body according to the present invention, the first base material and the second base material are different materials.

  In another embodiment of the joined body according to the present invention, in the adhesive layer, the ratio of the elastic modulus at the highest elastic modulus portion to the elastic modulus at the lowest elastic modulus portion is 2: 1 or more.

  In still another embodiment of the joined body according to the present invention, the elastic modulus at 23 ° C. in the adhesive layer having the lowest elastic modulus is 500 MPa or less.

  In still another embodiment of the joined body according to the present invention, the elastic modulus at 23 ° C. in the portion having the highest elastic modulus in the adhesive layer is 500 MPa or more.

  In still another embodiment of the joined body according to the present invention, the elastic modulus of the adhesive layer increases by 10 to 500 MPa each time when the elastic modulus is measured every 1 mm from the peripheral portion toward the central portion.

  In yet another embodiment of the joined body according to the present invention, the ratio of the Martens hardness at the highest Martens hardness to the Martens hardness at the lowest Martens hardness in the adhesive layer is 3: 1 or more.

In still another embodiment of the joined body according to the present invention, the Martens hardness at 23 ° C. in the portion having the lowest Martens hardness in the adhesive layer is 20 N / mm ² or less.

In still another embodiment of the joined body according to the present invention, the Martens hardness at 23 ° C. in the portion having the highest Martens hardness in the adhesive layer is 20 N / mm ² or more.

In still another embodiment of the joined body according to the present invention, the Martens hardness is 1 to 10 N / mm ² each time when the adhesive layer measures the Martens hardness every 1 mm from the peripheral edge toward the center. To rise.

  In yet another embodiment of the joined body according to the present invention, the joined body is a vehicle component.

  In another aspect of the present invention, a step 1 for preparing a first substrate and a second substrate, and a step 2 for laminating an adhesive layer on the first substrate and / or the second substrate. And a step 3 of curing the adhesive layer after bonding the first substrate and the second substrate through the adhesive layer, wherein the step 2 is a step after the curing. And changing the composition of the adhesive layer so that the elastic modulus of the adhesive layer increases from the peripheral part toward the central part.

  In one embodiment of the method for producing a joined body according to the present invention, in Step 2, the first liquid contains a curing initiator, the second liquid contains a curing accelerator, and other than the curing initiator and the curing accelerator. The adhesive layer is formed by applying a two-part adhesive on the first substrate, the composition of which is different between the first and second liquids, and changing the blending ratio of the first and second liquids. Changing the composition.

  In another embodiment of the method for producing a joined body according to the present invention, in Step 1, an adhesive is applied in a spiral or nested manner on the first base material and / or the second base material. Is done.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive force of the base materials is high, and the joined body with few distortions by which the stress resulting from the linear expansion coefficient difference between base materials was distributed can be provided. That is, a bonded body having high adhesive strength and little deterioration with time can be obtained. For this reason, the joined body according to the present invention is particularly effective when joining dissimilar materials having a large difference in linear expansion coefficient.

It is typical sectional drawing of the joined body which joined the 1st base material and the 2nd base material through the adhesive bond layer. When measuring the elastic modulus from both peripheral edges of the adhesive layer to the central portion along a straight line passing through the central portion of the adhesive layer, the case where the elastic modulus changes stepwise (continuously) It is a graph which shows typically an example in the case of changing and drawing a curve. It is a structural example of the coating device of a two-component adhesive. It is an example of a structure of the coating device of a three-component adhesive. It is a structural example of the coating device of a four-component adhesive. It is an example of the application pattern with respect to the joint surface of the base material of an adhesive agent. It is a schematic diagram of the joined body produced by the Example and the comparative example. It is the relationship between the adhesion distance and elastic modulus in the joined body of Example 1. It is the relationship between the adhesion distance and elastic modulus in the joined body of Example 2. It is the relationship between the adhesion distance and elastic modulus in the joined body of Example 3. It is the relationship between the adhesion distance and elastic modulus in the joined body of Example 4. It is the relationship between the adhesion distance and elastic modulus in the joined body of Comparative Example 1. It is the relationship between the adhesion distance and elastic modulus in the joined body of Comparative Example 2. It is the relationship between the adhesion distance and Martens hardness in the joined body of Example 1. It is the relationship between the adhesion distance and Martens hardness in the joined body of Example 2. It is the relationship between the adhesion distance and Martens hardness in the joined body of Example 3. It is a relationship between the adhesion distance and Martens hardness in the joined body of Example 4. It is the relationship between the adhesion distance and Martens hardness in the joined body of Comparative Example 1. It is the relationship between the adhesion distance and Martens hardness in the joined body of Comparative Example 2.

<Base material>
The material of the base material constituting the joined body according to the present invention is not particularly limited, and examples thereof include metals, resins, glass, ceramics, wood, and paper. A composite material combining a plurality of types of these materials or a composite material combining these materials with another material may be used.

  Examples of the metal include iron, aluminum, stainless steel, magnesium, and alloys containing these. When the joined body is used for a vehicle, the metal is typically an iron alloy plate such as a cold-rolled steel plate, a hot-dip galvanized steel plate, and an alloyed hot-dip galvanized steel plate.

  Examples of the resin include unsaturated polyester resin, epoxy resin, polypropylene resin, and polyamide resin. As a structural material, the resin is provided as a composite material with reinforced fibers such as unsaturated polyester GFRP, epoxy GFRP, polypropylene GFRP, polyamide GFRP, unsaturated polyester CFRP, epoxy CFRP, polypropylene CFRP, and polyamide CFRP. Is preferred.

  Although the same material may be used for the combination of the substrates to be bonded, it is preferable to use different materials to achieve the effects of the present invention.

<Adhesive layer>
The type of adhesive that makes up the adhesive layer is not limited, but using two or more liquid type adhesives can be applied to the substrate while changing the composition of the adhesive, and bonded. This is preferable because the elastic modulus of the adhesive after curing can be changed depending on the place where the agent is applied. Two or more liquid adhesives include two-part acrylic, three-part acrylic, four-part acrylic, two-part epoxy, three-part epoxy, four-part epoxy, and two-part urethane. , Three-component urethane, four-component urethane, two-component silicone, three-component silicone, and four-component silicone. Among these, acrylic type two-component or more adhesives are preferable because of rapid curing at room temperature.

  Adhesives are roughly classified into a thermosetting type and a photocurable type depending on the type of curing reaction, and any type of curing reaction type adhesive can be used in the present invention. However, since a photo-curing adhesive is difficult to use when joining substrates that are difficult to transmit light, a thermo-curing adhesive is preferable because of its high versatility. Further, among thermosetting adhesives, there are some substrates that cannot be applied in the case of an adhesive that requires heating. Therefore, it is preferable to use a room-temperature curable adhesive among thermosetting adhesives in a wide range of applications.

  As an example of a two-pack type adhesive, the first liquid contains a curing initiator, the second liquid contains a curing accelerator, and a composition other than the curing initiator and the curing accelerator (polymerizable monomer, elastomer component, etc. ) Is a two-part adhesive that is different between the first and second liquids. When using such an adhesive, change the composition of the adhesive layer and change the modulus of elasticity by applying it on the substrate while changing the blending ratio of the first and second liquids. Will be able to.

  As an example of a three-component adhesive, the first liquid is a curing initiator, the second liquid and the third liquid contain the same type and content of curing accelerator, and compositions other than the curing accelerator (polymerizability) A three-component adhesive in which the monomer and elastomer component are different in the second and third liquids. When using such an adhesive, the composition of the adhesive layer can be changed by applying it on the substrate while changing the mixing ratio of the second liquid and the third liquid, and the elastic modulus can be changed. Will be able to give. Moreover, since the kind and content of the curing agent are the same, the curing time is also substantially constant.

  As an example of a four-component adhesive, the first and third liquids contain the same type and content of curing initiator, and the second and fourth liquids contain the same type and content of a curing accelerator. The composition (polymerizable monomer, elastomer component, etc.) other than the curing initiator and the curing accelerator has the same composition in the first liquid and the second liquid, and the third liquid and the fourth liquid have the same composition. A four-component adhesive having a composition different from that of the first and third liquids may be mentioned. When such an adhesive is used, the adhesive layer can be changed by changing the mixing ratio of the first and third liquids containing the curing initiator and by changing the mixing ratio of the second and fourth liquids. The composition can be changed, and the elastic modulus can be changed. Further, while keeping the total discharge flow rate of the first liquid and the third liquid and the total discharge flow rate of the second liquid and the fourth liquid, respectively, the mixing ratio of the first liquid and the third liquid, and the second liquid and the second liquid By changing the blending ratio of the four liquids, the elastic modulus can be changed by changing the composition of the adhesive layer while keeping the curing time constant.

  Although it does not limit as a hardening initiator, The organic peroxide which generate | occur | produces a radical by a chemical reaction with a hardening accelerator is preferable. Examples of organic peroxides include cumene hydroperoxide, paramentane hydroperoxide, tertiary butyl hydroperoxide, diisopropylbenzene dihydroperoxide, methyl ethyl ketone peroxide, benzoyl peroxide, and tertiary butyl peroxybenzoate. . Among these, cumene hydroperoxide is preferable from the viewpoint of stability.

  As the curing accelerator, any known curing accelerator that reacts with the curing initiator and generates radicals can be used. Typical curing accelerators include, for example, tertiary amines, thiourea derivatives, transition metal salts and the like. Examples of the tertiary amine include triethylamine, tripropylamine, tributylamine, and N, N-dimethylparatoluidine. Examples of the thiourea derivative include 2-mercaptobenzimidazole, methylthiourea, dibutylthiourea, tetramethylthiourea, and ethylenethiourea. Examples of the transition metal salt include cobalt naphthenate, copper naphthenate, and vanadyl acetylacetonate. Among these, vanadyl acetylacetonate is preferable from the viewpoint of stability.

  The joined body according to the present invention is characterized in that the elastic modulus of the adhesive layer increases from the peripheral portion toward the central portion. FIG. 1 schematically shows a cross-sectional view of a joined body in which a first base material 11 and a second base material 12 are joined via an adhesive layer 13. When bonding different kinds of materials, it is the peripheral portion 14 of the adhesive layer 13 where stress is most likely to be concentrated. In this invention, it aims at disperse | distributing the stress resulting from the difference of the linear expansion coefficient between different materials by making the elasticity modulus of the adhesive bond layer 13 in the said peripheral part 14 low. This makes it difficult for the adhesive force to deteriorate over time, so that it is possible to obtain the bonded body 10 having excellent durability. Moreover, when the base materials 11 and 12 are thin, the problem that the joined body 10 is distorted occurs when the stress is concentrated on the peripheral portion 14, but the distortion of the base materials 11 and 12 is suppressed by dispersing the stress. A visual effect is also obtained.

  Therefore, in the joined body according to the present invention, the portion having the lowest elastic modulus in the cured adhesive layer is the peripheral portion. The elastic modulus at 23 ° C. in the peripheral edge is preferably 500 MPa or less, more preferably 100 MPa or less, and even more preferably 20 MPa or less, from the viewpoint of significantly exhibiting the stress dispersion effect. The use of an adhesive having a low elastic modulus in this way is also preferable for securing low temperature impact resistance. Further, the elastic modulus at the peripheral edge 14 is preferably 0.1 MPa or more, more preferably 5 MPa or more, and even more preferably 10 MPa or more, from the viewpoint of the adhesive strength at the end.

  However, if the elastic modulus of the entire adhesive layer is low, the adhesive layer becomes soft as a whole and the initial adhesive force is reduced. Further, the shape stability of the joined body is lowered. Therefore, in the present invention, the elastic modulus of the adhesive layer 13 is increased toward the central portion 15. By increasing the elastic modulus toward the central portion 15 of the adhesive layer 13, it is possible to ensure the initial adhesive force while taking advantage of the adhesive having a small elastic modulus at the peripheral edge portion 14.

  Therefore, in the joined body according to the present invention, the portion having the highest elastic modulus in the cured adhesive layer is the central portion. The elastic modulus at 23 ° C. in the central portion is preferably 500 MPa or more, more preferably 1000 MPa or more, and still more preferably 1500 MPa or more, from the viewpoint of sufficiently exerting the initial adhesive force. The elastic modulus at the central portion is preferably 3000 MPa or less, more preferably 2000 MPa or less, and even more preferably 1000 MPa or less from the viewpoint of the elastic modulus ratio of the peripheral portion.

  Moreover, in the adhesive layer after curing, the ratio of the elastic modulus at 23 ° C. in the portion having the highest elastic modulus (center portion) to the elastic modulus at 23 ° C. in the portion having the lowest elastic modulus (peripheral portion) is: From the viewpoint of achieving both the stress dispersion effect and securing the initial adhesive force, it is preferably 2: 1 or more, more preferably 10: 1 or more, and even more preferably 100: 1 or more, For example, it can be set to 2: 1 to 200: 1.

  As the elastic modulus of the adhesive layer rises from the peripheral edge toward the center, the elastic modulus may change continuously or stepwise, but it is preferable to change continuously. Moreover, when changing in steps, it is preferable that the difference for each step is small. This is because the stress cannot be sufficiently dispersed if the change in each stage is large. FIG. 2 shows a case where the elastic modulus changes stepwise (step shape) when the elastic modulus is measured from both peripheral edge portions to the central portion of the adhesive layer along a straight line passing through the central portion of the adhesive layer. An example of a case where a curve is drawn by continuously changing will be shown. When continuously changing, as shown in the figure, it is preferably a curve that draws an upwardly convex function.

  Specifically, when the adhesive layer after curing is measured for an elastic modulus every 1 mm from the peripheral part toward the central part, it is preferable that the increase width of the elastic modulus every time at 23 ° C. is 500 MPa or less, More preferably, it is 100 MPa or less, for example, 10-500 MPa.

  As properties required for adhesives in structures such as automobile bodies, conflicting resin properties such as low temperature impact resistance and high temperature strength are also required, but in the bonded body according to the present invention, as described above. In addition, low temperature impact resistance can be obtained by lowering the elastic modulus of the peripheral edge. Furthermore, when an adhesive having a high elastic modulus at a high temperature is used as an adhesive used in the central portion, which is a portion having the highest elastic modulus, in the adhesive layer, high-temperature strength can be ensured. Specifically, the elastic modulus at 80 ° C. is preferably 500 MPa or more, more preferably 800 MPa or more, and even more preferably 1000 MPa or more.

  The elastic modulus of the adhesive after curing can be controlled, for example, by the following method. Since the elastic modulus has a correlation with the glass transition temperature, a method of using an adhesive having a high glass transition temperature (Tg) is used to obtain an adhesive having a high elastic modulus. The glass transition temperature can be controlled by changing the type of polymerizable monomer. If an adhesive having a high glass transition temperature is desired, a polymerizable monomer having a high homopolymer Tg is used, and an adhesive having a low glass transition temperature. If desired, a polymerizable monomer having a low homopolymer Tg may be used.

Since the elastic modulus in the adhesive layer has a correlation with the Martens hardness, the characteristics of the joined body according to the present invention described above can be defined by the Martens hardness. The part where the Martens hardness is the lowest in the adhesive layer after curing is the peripheral edge, as is the elastic modulus. The Martens hardness at 23 ° C. at the peripheral edge is preferably 20 N / mm ² or less, more preferably 10 N / mm ² or less, and even more preferably 5 N / mm, from the viewpoint of significantly exerting the stress dispersion effect. mm ² or less. The use of an adhesive having a low elastic modulus in this way is also preferable for securing low temperature impact resistance.

  However, if the Martens hardness of the entire adhesive layer is low, the adhesive layer becomes soft as a whole, and the initial adhesive force is reduced. Further, the shape stability of the joined body is lowered. Therefore, in the present invention, the Martens hardness of the adhesive layer 13 is increased toward the central portion 15. By increasing the Martens hardness toward the central portion 15 of the adhesive layer 13, it is possible to ensure the initial adhesive force while taking advantage of the adhesive having a low Martens hardness at the peripheral edge portion 14.

Therefore, in the joined body according to the present invention, the portion having the highest Martens hardness in the adhesive layer after curing is the central portion. The Martens hardness at 23 ° C. at the center from the viewpoint of sufficiently exhibiting the initial adhesive strength, is preferably 18N / mm ² or more, more preferably 30 N / mm ² or more, even more preferably 40N / mm ² or more.

  Moreover, in the adhesive layer after curing, the ratio of the Martens hardness at 23 ° C. at the highest Martens hardness part (central part) to the Martens hardness at the lowest Martens hardness part (peripheral part) is: From the viewpoint of achieving both the stress dispersion effect and securing the initial adhesive force, the ratio is preferably 2: 1 or more, more preferably 3: 1 or more, and more preferably 5: 1 or more. : 1 or more is more preferable, and 100: 1 or more is even more preferable. For example, it can be 2: 1 to 100: 1.

Further, for the same reason as the elastic modulus, when the adhesive layer after curing is measured for Martens hardness every 1 mm from the peripheral portion toward the center portion, the increase width of Martens hardness at 23 ° C. is 15N each time. / preferably mm ² or less, more preferably 10 N / mm ² or less, such as 1 to 10 N / mm ^2.

<Joint>
The joined body according to the present invention is not limited, but is used for transportation equipment such as automobiles, railroads, ships and aircraft, building materials such as roofs, walls, joinery and floors, as well as electrical / electronic equipment, office equipment and household goods. It can be applied to a wide range of structures. Among these, it can be suitably applied particularly to a joined body having a bonding portion where a structural adhesive is used. Therefore, the joined body according to the present invention includes vehicle parts such as automobiles and railway bodies, ship hull parts, aircraft fuselage parts, building parts, electrical / electronic equipment parts, office equipment parts, or household goods. Can be provided as a part.

<Method for producing joined body>
In one embodiment of the method for manufacturing a joined body according to the present invention, the first substrate and the second substrate are prepared, and the first substrate and / or the second substrate are bonded. Step 2 of laminating the agent layer and Step 3 of curing the adhesive layer after bonding the first base material and the second base material through the adhesive layer are included. In manufacturing the joined body according to the present invention, in Step 2, the composition of the adhesive layer may be changed so that the elastic modulus of the cured adhesive layer increases from the peripheral portion toward the central portion. It is essential.

  The adhesive layer may be laminated on one of the first substrate and the second substrate, or on both surfaces, but the adhesive film thickness is controlled and the coating shape is maintained. For reasons, it is preferable to use either one of the joining surfaces. Examples of the method for changing the composition of the adhesive layer include a method in which a plurality of types of adhesives having different compositions are prepared and the type of the adhesive is changed according to the place where the adhesive is applied. Also, an adhesive application device 30 having an adhesive mixing mechanism as shown in FIG. 3 may be used so that the composition of the adhesive can be continuously changed. The coating device 30 includes two syringes 31 for containing an adhesive component, a piston 34 for controlling the discharge flow rate from each syringe 31, a motor 35 and a speed controller 36 for controlling the operation of the piston 34. And a static mixer 32 for mixing the adhesive components discharged from the two syringes 31. Although the number of syringes 31 is two in FIG. 3, it can be increased to three or more as required. Further, a check valve (not shown) may be appropriately installed between the static mixer 32 and the cylinder 31.

  The usage method of the coating apparatus 30 shown in FIG. 3 will be described by taking as an example the case of using a two-component main agent type adhesive (eg, an acrylic adhesive). The second liquid contains a curing accelerator, a polymerizable monomer (eg, acrylic monomer), an elastomer, and other stabilizers. The first liquid and the second liquid are sealed in independent syringes 31, respectively. The difference between the first liquid and the second liquid is that the composition other than the curing initiator and the curing accelerator is different. For example, the first liquid contains a polymerizable monomer and elastomer that exhibit a high elastic modulus after curing, and the second liquid contains a polymerizable monomer and elastomer that exhibit a low elastic modulus after curing.

  When applying the above two-component adhesive on the first substrate and / or the second substrate, the composition of the adhesive layer is changed by changing the blending ratio of the first and second solutions. That is, it is possible to change the elastic modulus after curing. For example, the peripheral portion of the base material is applied with a high blending ratio of the second liquid containing a polymerizable monomer and an elastomer having a low elastic modulus after curing, and the base portion has high elasticity after curing. Examples of the method include a method in which the ratio of the first liquid containing a polymerizable monomer and an elastomer containing a high ratio is increased. This is possible by controlling the pushing speed of the piston of the syringe for the first liquid and the pushing speed of the piston for the second liquid with a speed controller, and controlling the discharge flow rates of the first liquid and the second liquid. At this time, the mixing ratio of the first liquid and the second liquid is not changed rapidly, but the mixing ratio is gradually changed from the peripheral part of the adhesive layer toward the center part, so that it is easy to concentrate on the peripheral part. The effect of dispersing stress is increased.

  However, when the mixing ratio of the first liquid containing the curing initiator is high in the above method, the curing is fast, whereas when the mixing ratio of the first liquid is low, the curing is slow, so the curing time is the adhesive. By changing depending on the location of the layer, a location where the substrates cannot be joined may be generated. Therefore, there is a method of using a three-component adhesive to make the curing time constant. In the method, the first liquid is a curing initiator, the second liquid and the third liquid contain the same curing accelerator, and the composition (polymerizable monomer, elastomer component, etc.) other than the curing accelerator is the second liquid. Different three-component adhesives can be used for the third liquid. FIG. 4 shows a schematic diagram of the coating apparatus when the number of syringes is increased to three.

  The applicator 40 includes three syringes 41 for containing adhesive components, pistons 44 for controlling the discharge amount from each syringe 41, a motor 45 and a speed controller 46 for controlling the operation of the pistons 44. And a static mixer 42 for mixing the adhesive components discharged from the three syringes 41. A check valve (not shown) may be appropriately installed between the static mixer 42 and the syringe 41.

  Using the coating device 40, the total discharge flow rate of the second liquid and the third liquid is made constant while discharging the first liquid at a constant discharge flow rate using the above-described three-component adhesive. It is possible to control the curing time to be constant while giving a change to the composition of the adhesive by discharging while changing to.

  Furthermore, it is also possible to use a four-component adhesive by using a coating apparatus 50 as shown in FIG. The application device 50 includes a plurality of syringes 51 for containing an adhesive component, a piston 54 for controlling the discharge amount from each syringe 51, a motor 55 and a speed controller 56 for controlling the operation of the piston 54. And a first static mixer 52 for mixing the adhesive components discharged from the plurality of syringes 51. There are a plurality of first static mixers 52, and further includes a second static mixer 53 for mixing the adhesive components discharged from the first static mixers 52. In FIG. 5, the number of syringes 51 is two for one first static mixer, but can be increased to three or more as required. In FIG. 5, the number of the first static mixers 52 is two, but can be increased to three or more as necessary. Further, a check valve (not shown) may be appropriately installed between the first static mixer 52 and the syringe 51 and / or between the second static mixer 53 and the first static mixer 52.

  As an example of a four-pack type adhesive that can use the coating apparatus shown in FIG. 5, the first liquid and the third liquid contain the same curing initiator, and the second liquid and the fourth liquid contain the same curing accelerator. The composition (polymerizable monomer, elastomer component, etc.) other than the curing initiator and the curing accelerator has the same composition in the first liquid and the second liquid, and the third liquid and the fourth liquid have the same composition. A four-component adhesive having a composition different from that of the first and third liquids may be mentioned. When such an adhesive is used, the adhesive layer can be changed by changing the mixing ratio of the first and third liquids containing the curing initiator and by changing the mixing ratio of the second and fourth liquids. The composition can be changed, and the elastic modulus can be changed. Further, while keeping the total discharge flow rate of the first liquid and the third liquid and the total discharge flow rate of the second liquid and the fourth liquid, respectively, the mixing ratio of the first liquid and the third liquid, and the second liquid and the second liquid By changing the blending ratio of the four liquids, the elastic modulus can be changed by changing the composition of the adhesive layer while keeping the curing time constant.

  Although not limited, the example of the application | coating pattern at the time of apply | coating an adhesive agent on a base material and forming an adhesive bond layer is shown to Fig.6 (a) and (b). FIG. 6A shows a coating pattern in the case where the adhesive 61 is spirally coated on the substrate 62. Here, an adhesive that lowers the elastic modulus after curing is applied to the peripheral edge of the adhesive layer, and an adhesive that increases in elastic modulus as it goes to the center of the adhesive layer is applied. By adopting a spiral coating pattern, a continuous coating line can be drawn, so that the composition of the adhesive can be continuously changed, and the coating can be applied to the end without interruption. Application time is also saved.

  FIG. 6B shows an application pattern when the adhesive 63 is applied in a nested manner (or a plurality of annular application lines having the same center of gravity) on the base material 64. Here, the adhesive having a low elastic modulus after curing is applied in a frame shape along the outer periphery of the base material, and then applied in a frame shape on the inner side along the outer periphery application line, by repeating this, An adhesive having a higher elastic modulus after curing as it goes to the center of the adhesive layer is applied in a nested manner. When adopting a nested application pattern in which the size decreases from the peripheral part toward the central part, for example, an adhesive determined for each frame can be used, and there is an advantage that complicated flow control is not required. .

  In FIG. 6, the application pattern is a square shape, but any application pattern can be used according to the shape of the bonding surface of the base material. For example, other polygonal shapes (triangles, pentagons, hexagons, etc.) and curved shapes (circular shapes, elliptical shapes, etc.) are also possible.

  After laminating the adhesive layer on the first base material and / or the second base material, the first base material and the second base material are bonded together to cure the adhesive layer. The curing means may be appropriately set according to the curing reaction type of the adhesive constituting the adhesive layer.

  The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to these embodiments, and various variations are possible.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely, the present invention is not limited to the following examples.

As the two-component main agent type adhesive, the following was used.
(1) Product name “G-58K-15 A / B” (manufactured by Denki Kagaku Kogyo Co., Ltd.):
Agent A contains cumene hydroperoxide, and agent B contains vanadyl acetylacetonate.
Elastic modulus after curing: 1500 ~ 2000MPa
(2) Product name “SC-8 A / B” (manufactured by Denki Kagaku Kogyo (prototype)):
Agent A contains cumene hydroperoxide, and agent B contains vanadyl acetylacetonate.
Elastic modulus after curing: 1-50MPa

(Preparation of joined body)
Conforms to JIS K-6850. One side of an iron substrate (size: 100 × 25 × 1.6 mm) was coated with an adhesive mixed with G-58K-15 A agent and SC-8 B agent, and the other iron 7 immediately after being superposed on a base material (size: 100 × 25 × 1.6 mm) in the form as shown in FIG. 7 and bonded to a thickness of about 100 μm, and then cured at room temperature for 24 hours. Was made. The application pattern of the joint surface was applied using an applicator so as to form a pattern in which a plurality of rectangular application lines as shown in FIG. At this time, the composition ratio in the adhesive layer was changed by adjusting the mixing ratio of the A agent of G-58K-15 and the B agent of SC-8.

(Tensile modulus measurement)
From the one end of the adhesive layer to the other end along the arrow A (a line passing through the center of the adhesive layer in a direction parallel to the pulling direction) shown in FIG. Measured based on the composition of the adhesive at multiple locations between 10 mm. Specifically, a cured product of the adhesive corresponding to the composition of the adhesive at the desired measurement site in the adhesive layer was separately prepared (size: 50 × 5 × 1 mm), and the tensile modulus was measured. The tensile modulus (unit: MPa) was measured in accordance with JIS K-7161: 1994 at a tensile speed of 50 mm / min in an environment of a temperature of 23 ° C. and a humidity of 50%. The results are shown in Table 1 and Figs.

(Unit: MPa)

(Measurement of hardness of adhesive layer)
In addition, in order to confirm that the change in elastic modulus in the adhesive layer has a correlation with the hardness in the adhesive layer, after pulling each joined body in the shear direction and peeling it off, the Martens hardness of the adhesive is pulled. It measured based on ISO14577: 2002 about the adhesive bond layer surface of the location where the elasticity modulus was calculated | required using the following apparatuses and methods. The results are shown in Table 2 and FIGS.
Equipment: Thin film hardness tester (Nano Indenter) manufactured by Toyo Technica, Inc. Nano Indenter G200 (XP head)
Indentation load: 10mN
Method: The Martens hardness was measured by applying a load of up to 10 mN, holding it for 10 seconds, and then removing the load.

(Unit: N / mm ² )

(Tensile shear bond strength (shear strength))
The above-mentioned joined body was produced again under the conditions corresponding to the test number, and used as a sample for measuring tensile shear bond strength. The tensile shear bond strength (unit: MPa) was measured in accordance with JIS K-6850: 1999 in the tensile direction of FIG. 7 at a tensile speed of 10 mm / min under an environment of a temperature of 23 ° C. and a humidity of 50%. The results are shown in Table 3.
Evaluation was performed as follows.
A: When strength of 20 MPa or more is developed. ○: When strength of 10 MPa or more is developed. X: When strength of less than 10 MPa is developed.

(Distortion evaluation)
Adhesive is applied to test pieces of various materials shown below (100 × 25 × 3 mm), and immediately superposed with a mirror surface SUS (100 × 25 × 0.8 mm) and bonded together (joining conditions are the same as above), room temperature The sample was cured for 24 hours and used as a sample for strain evaluation test. The evaluation was made visually and judged by the presence or absence of distortion of the mirror surface SUS. The results are shown in Table 3.
Material: SUS, aluminum, CFRP
Evaluation was performed as follows.
◎: When no distortion occurs in the mirror surface SUS ○: When distortion occurs only in the outer peripheral portion of the adhesion area of the mirror surface SUS ×: When distortion occurs in the entire adhesion area of the mirror surface SUS

  With the active development of bonding of dissimilar materials such as composite materials and composite materials with metals, such as weight reduction of automobile bodies, the characteristics required for adhesives are the conflict between low temperature impact resistance and high temperature strength. However, it is extremely difficult to solve the problem by using only the adhesive, but by using the joined body or the manufacturing method of the joined body according to the present invention, the characteristics of the adhesive can be combined well. It is possible to join with a few adhesives without preparing a large number of adhesives according to parts and places, and it is considered that the industrial benefit is great.

DESCRIPTION OF SYMBOLS 10 Joint body 11 1st base material 12 2nd base material 13 Adhesive bond layer 14 Peripheral part 15 Center part 30 Application | coating apparatus 31 Syringe 32 Static mixer 34 Piston 35 Motor 36 Speakon 40 Application | coating apparatus 41 Syringe 42 Static mixer 44 Piston 45 Motor 46 Speakon 50 Application device 51 Syringe 52 First static mixer 53 Second static mixer 54 Piston 55 Motor 56 Speakon 61 Adhesive 62 Base 63 63 Adhesive 64 Base 71 71 Base 72 Base 73 Adhesive

Claims (14)

  A bonded body having a first base material, a second base material, and an adhesive layer connecting the first base material and the second base material, the elastic modulus and / or martens of the adhesive layer A joined body whose hardness increases from the peripheral edge toward the center.   The joined body according to claim 1, wherein the first substrate and the second substrate are different materials.   The joined body according to claim 1 or 2, wherein in the adhesive layer, a ratio of an elastic modulus at a portion having the highest elastic modulus to an elastic modulus at a portion having the lowest elastic modulus is 2: 1 or more.   The joined body according to any one of claims 1 to 3, wherein an elastic modulus at 23 ° C in a portion having the lowest elastic modulus is 500 MPa or less in the adhesive layer.   The joined body according to any one of claims 1 to 4, wherein an elastic modulus at 23 ° C in a portion having the highest elastic modulus in the adhesive layer is 500 MPa or more.   The bonded body according to any one of claims 1 to 5, wherein the elastic modulus increases by 10 to 500 MPa each time when the elastic modulus of the adhesive layer is measured every 1 mm from the peripheral portion toward the central portion.   7. The ratio of the Martens hardness at the highest Martens hardness to the Martens hardness at the lowest Martens hardness in the adhesive layer is 3: 1 or more. 7. The joined body. The joined body according to any one of claims 1 to 7, wherein a Martens hardness at 23 ° C in a portion having the lowest Martens hardness is 20 N / mm ² or less in the adhesive layer. The joined body according to any one of claims 1 to 8, wherein a Martens hardness at 23 ° C in a portion having the highest Martens hardness in the adhesive layer is 20 N / mm ² or more. The adhesive layer according to any one of claims 1 to 9, wherein when the Martens hardness is measured every 1 cm from the peripheral edge toward the center, the Martens hardness increases by 1 to 10 N / mm ² each time. body.   It is a vehicle component, The joined body as described in any one of Claims 1-10.   Step 1 for preparing a first substrate and a second substrate, Step 2 for laminating an adhesive layer on the first substrate and / or the second substrate, the first substrate and the first substrate And a step 3 of curing the adhesive layer after bonding the two substrates through the adhesive layer, wherein the elastic modulus of the adhesive layer after curing is a peripheral portion. And changing the composition of the adhesive layer so as to rise from the center toward the center.   In step 2, the first liquid contains a curing initiator, the second liquid contains a curing accelerator, and the compositions other than the curing initiator and the curing accelerator differ in the first liquid and the second liquid. 13. The joined body according to claim 12, comprising applying the adhesive on the first substrate, and changing the composition of the adhesive layer by changing the blending ratio of the first liquid and the second liquid. Manufacturing method.   The process for producing a joined body according to claim 12 or 13, wherein in Step 1, the adhesive is applied in a spiral shape or a nested shape on the first base material and / or the second base material.