JP2016056259A - Epoxy resin-based adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin-based adhesive composition used for body processing of steel-made furniture or structure adhesive of a body panel or the like of vehicles or the like, capable of applying without dripping at normal temperature, being uncured status even after spot welding, having neither dripping nor leaching in washing and drying process after welding and cured in a coating and galling process.SOLUTION: There is provided an epoxy resin-based adhesive composition containing an epoxy resin which is liquid at normal temperature, a potential curing agent for epoxy resin which is activated by heating, a gelling agent and carbon black.SELECTED DRAWING: None

Description

  The present invention relates to an epoxy resin-based adhesive composition used for housing processing of steel furniture and structural bonding of body panels of vehicles and the like.

  Conventionally, in the processing of a housing made of steel furniture, a reinforcing member that supplements the surface strength of a required face plate portion of the housing is provided on at least a part of the contact surface between the face plate portion and the reinforcing member in a predetermined direction. After applying a thermosetting adhesive over the entire area, the reinforcing member is temporarily fixed to the face plate by point bonding by welding or the like, and then the adhesive is cured by heat to bond the face plate portion and the reinforcing member. A surface bonding method is employed (Patent Document 1). Also, in the weld bond method that uses both adhesive and spot welding for structural adhesion of vehicles, etc., it is excellent in workability when applying adhesive, and it becomes highly viscous in the electrodeposition coating process or the subsequent cleaning process, causing scattering and outflow. There has been proposed a structural adhesive composition that can prevent the above-described problem and that can be applied with existing equipment without requiring heating equipment or preheating equipment. The structural adhesive composition is composed of a main epoxy resin that is liquid at 20 ° C. synthesized from bisphenol as a raw material, a solid rubber component that does not react with the main epoxy resin, and is activated by heating, at least one selected from NBR and SBR And a latent curing agent for epoxy resin to be converted. (Patent Document 2). Both can be applied at room temperature, are uncured after spot welding, and the adhesive is cured during painting and baking.

JP2009-101097 JP2013-253131A

  The epoxy resin-based adhesive composition of the above-mentioned Patent Document 1 has oil surface adhesiveness in consideration of the fact that a galvanized steel sheet or the like is usually used for the plate material of this type of housing. In other words, an adhesive that can be bonded without degreasing is selected. However, since it is hardened by an acrylic or epoxy adhesive, it is preferable to use a polybutadiene rubber or the like that is a sulfur curing agent. It is an agent. Patent Document 2 is selected from NBR and SBR that do not react with an epoxy resin in order to prevent splatter and spillage in the electrodeposition coating process and the subsequent cleaning process, because it is excellent in workability at the time of application and is prevented from scattering and flowing out. An epoxy resin-based adhesive composition comprising at least one solid rubber component. All of them contain a rubber component that does not react with the epoxy resin in order to ensure workability during application.

  The present invention does not contain a rubber-based component that does not react with the epoxy resin in the adhesive, can be applied without sagging at room temperature, and is uncured even after spot welding. It is an object of the present invention to provide an epoxy resin adhesive composition that is free from sagging and leaching even in the process and hardens in the painting and baking process.

  In order to solve the above problems, the epoxy resin adhesive composition of the present invention includes an epoxy resin that is liquid at room temperature, a latent curing agent for epoxy resin that is activated by heating, a gelling agent, carbon black, An epoxy resin-based adhesive composition containing 5 to 30 parts by mass of the gelling agent with respect to a total of 100 parts by mass of the epoxy resin and the latent curing agent, and the carbon black, 1.5-4 mass parts is mix | blended with respect to a total of 100 mass parts of an epoxy resin and a latent hardener, It is characterized by the above-mentioned. Further, the gelling agent is a core-shell type acrylic resin powder, and the carbon black is a hollow shell conductive carbon black.

  The epoxy resin adhesive composition of the present invention includes an epoxy resin that is liquid at room temperature, a latent curing agent for epoxy resin that is activated by heating, a gelling agent, and carbon black. Adhesive composition that can be applied without sagging, is uncured even after spot welding, and does not sag or ooze even after cleaning and drying processes after welding, and cures during painting and baking processes Thus, it is suitable for structural bonding of steel casings and vehicles.

  The epoxy resin adhesive composition of the present invention comprises an epoxy resin that is liquid at normal temperature, a latent curing agent for epoxy resin that is activated by heating, a gelling agent, and carbon black.

  As an epoxy resin that is liquid at room temperature, an epoxy resin that is liquid at room temperature and synthesized from bisphenol is used. Examples of bisphenol include bisphenol A, bisphenol E, bisphenol F, bisphenol S, bisphenol AP, bisphenol AF, bisphenol B, bisphenol BP, bisphenol C, bisphenol G, bisphenol M, and bisphenol P, and at least one selected from these An epoxy resin synthesized as a raw material can be used. Among them, a high viscosity bisphenol A type epoxy resin is preferable.

  Latent curing agents for epoxy resins activated by heating include guanamines, guanidines, aminoguanidines, ureas, imidazoles, modified polyamines and their derivatives, dicyandiamide, boron trifluoride amine complexes, organic acids It can be selected from the group such as hydrazide and melamine. Of these, dicyandiamide, which is widely used, is preferable. The addition amount of the latent curing agent is determined according to the epoxy equivalent of the matrix.

  Examples of gelling agents include silica powder surface-treated with a silane coupling agent, mineral fibers such as sepiolite, and acrylic resin-based core-shell fine powder. Among them, acrylic resin-based core shells that are also used as epoxy resin reinforcing agents Type fine powder is preferable, and Zefiac F351 (trade name, manufactured by Aika Kogyo Co., Ltd.) is a commercially available product. The acrylic resin-based core-shell fine powder can be easily dispersed with respect to the epoxy resin, and has a pre-gel property and a high adhesive strength and stress relaxation property by melting the shell layer when the epoxy resin is completely cured. The gelling agent is blended in an amount of 5 to 30 parts by mass with respect to a total of 100 parts by mass of the epoxy resin and the latent curing agent, and when less than 5 parts by mass, sagging occurs when washed and dried after spot welding, If it exceeds 30 parts by mass, no sagging occurs, but application is impossible. Preferably, it is 8-25 mass parts.

  Carbon black also acts as a sagging inhibitor, but by adding carbon black, the epoxy resin adhesive composition becomes an adhesive composition having conductivity. Therefore, during spot welding, there is little current to be shunted, and the welding current flows in a straight line between the electrodes, and the current density between the adherends can be increased. A nugget can be formed between them. As the carbon black, artificial graphite powder, natural graphite powder, or the like is used. Among them, hollow shell-shaped carbon black having excellent conductivity is preferable, and a commercially available product is Ketjen Black (trade name, manufactured by Lion Corporation). The carbon black is blended in an amount of 1.5 to 4 parts by mass with respect to a total of 100 parts by mass of the epoxy resin and the latent curing agent. When the amount exceeds 4 parts by mass, sagging does not occur, but the workability is poor. Preferably, it is 2-3.5 mass parts.

In addition to the above components, DBU, DBN, tris (dimethylaminomethyl) phenol,
Curing accelerators (catalysts) such as 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-ethyl-4-methylimidazole, triphenylphosphine, tetraphenylphosphonium, 3-phenyl-1,1-dimethylurea, DCMU Can be added.

  Also, monofunctional reactive diluents such as n-butanol glycidyl ether, higher alcohol glycidyl ether, butylphenyl glycidyl ether, glycidyl methacrylate, or 1,4-butanediol diglycidyl ether, 1,6-hexanediol glycidyl Polyfunctional reactive diluents such as ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, and the like can also be added.

  Furthermore, extender pigments (fillers) such as calcium carbonate, barium sulfate, and talc, and color pigments such as titanium oxide and iron oxide can be added as necessary.

  Hereinafter, the epoxy resin adhesive composition of this invention is demonstrated based on an Example and a comparative example. Note that the epoxy resin adhesive composition of the present invention is not limited to the following forms, and can be variously modified and improved by those skilled in the art without departing from the gist of the present invention. Can be implemented.

  95 parts by mass of bisphenol A type epoxy resin jER828 (trade name, manufactured by Mitsubishi Chemical Corporation) as a liquid epoxy resin at normal temperature, bisphenol A type epoxy resin jER828 and dicyandiamide as a latent curing agent were kneaded at a weight ratio of 6: 4. 30 parts by mass of JDY-7DISYJ (manufactured by Aika Industry Co., Ltd.), 10 parts by mass of Zefiac F351 (trade name, manufactured by Aika Industry Co., Ltd.) which is a core-shell type acrylic resin powder as a gelling agent, and Ketjen Black EC300J (product name, 3 parts by weight of Lion), 6 parts by mass of DCMU-99 (trade name, manufactured by Hodogaya Chemical Co., Ltd.) as a catalyst, and ED-503 (trade name, ADEKA) which is a bifunctional reactive diluent as a reactive diluent 30 parts by mass) were mixed with stirring to obtain an epoxy resin adhesive composition of Example 1.

  In the same manner, epoxy resin adhesive compositions of Examples 2 to 4 and Comparative Examples 1 to 2 were obtained with the formulations shown in Table 1.

<Evaluation of adhesive>
The viscosity, sagging property, and adhesive strength of the epoxy resin adhesive compositions of Examples and Comparative Examples were evaluated by the following test methods.

[Test method / viscosity]
Using a B-type viscometer (model BH2), the viscosity of each epoxy resin adhesive composition was measured at a rotor 7, a rotational speed of 2 rpm, and a liquid temperature of 23 ° C.

[Test method / sag]
The test body which apply | coated each epoxy resin adhesive composition to the rolled steel plate SPCC-SD so that it might become thickness 2mm was set up vertically in a 140 degreeC thermostat, and the degree of sagging was evaluated visually 10 minutes afterward. Those that did not sag were rated as ◯, those that sag slightly but could be used were marked as △, and those that sagged were marked as x.

[Test method / Adhesion strength: T peel strength after spot welding]
A rolled steel plate SPCC-SD having a thickness of 1.6 mm, a width of 25 mm, and a length of 100 mm is bent in an L shape so that the flat portion is 50 mm, and each epoxy resin is bonded to the flat portion so that the thickness is 0.5 mm. The coated surfaces of the adherends coated with the agent composition were overlapped. Three points were temporarily fixed to the flat portion of the stacked steel plates with an AC spot welder at equal intervals to obtain each specimen. The end of the non-coated surface of the test specimen was grasped and peeled into a T-shape at 100 mm / min in an atmosphere of 18 ° C. using an Instron universal testing machine, and the strength was measured.

[Test method / Adhesion strength: T peel strength]
A rolled steel plate SPCC-SD having a thickness of 1.6 mm, a width of 25 mm, and a length of 100 mm is bent in an L shape so that the flat portion is 50 mm, and each epoxy resin is bonded to the flat portion so that the thickness is 0.5 mm. The coated surfaces of the adherends coated with the agent composition were overlapped and clipped. Next, after heating at 140 ° C. for 15 minutes in a clipped state, the coating was further heated at 190 ° C. for 15 minutes to cure the epoxy resin, thereby obtaining each specimen. The end of the non-coated surface of the test specimen was grasped and peeled into a T shape at 100 mm / min in an atmosphere of 23 ° C. using an Instron universal testing machine, and the strength was measured.

[Test results]
In Table 2, the performance evaluation result of each epoxy resin adhesive composition is shown.

  From the above results, while the gelling agent affects the workability of the epoxy resin adhesive composition and the adhesive strength after curing, carbon black is not only the viscosity of the epoxy resin adhesive composition but also the welding accuracy. Act.

Claims (3)

  An epoxy resin adhesive composition comprising an epoxy resin that is liquid at room temperature, a latent curing agent for epoxy resin that is activated by heating, a gelling agent, and carbon black, wherein the gelling agent is 5 to 30 parts by mass with respect to a total of 100 parts by mass of the epoxy resin and the latent curing agent, and the carbon black is 1. with respect to a total of 100 parts by mass of the epoxy resin and the latent curing agent. 5-4 mass parts is mix | blended, The epoxy resin-type adhesive composition characterized by the above-mentioned.   The epoxy resin adhesive composition according to claim 1, wherein the gelling agent is a core-shell type acrylic resin powder.   3. The epoxy resin adhesive composition according to claim 1 or 2, wherein the carbon black is a hollow shell conductive carbon black.