JP2015145461A - Manufacturing method of vehicle body panel structure using mastic adhesive and vehicle body panel structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bond different materials and a steel plate together or the different materials to each other with the same performance as thermosetting type mastic adhesive and to obtain a vehicle body panel structure.SOLUTION: A manufacturing method of a vehicle body panel structure comprises the steps of: applying normal-temperature curing type modified silicone adhesive capable of being cured under an ordinary environment within a temperature range from 0 to 40°C to bonding sections of an outer plate consisting of different materials other than a steel plate and an inner plate consisting of the steel plate or the different materials other than the steel plate as mastic adhesive: and, subsequently, curing the modified silicone adhesive under the ordinary environment in a state that the bonding sections of the outside plate and the inner plate overlap with each other.

Description

  The present invention relates to a manufacturing method for assembling a vehicle body panel structure by bonding an outer plate (outer) and an inner plate (inner) using a mastic material in an automobile production line, and a vehicle body panel such as a hood, a trunk lid, a door, or a roof. Concerning the structure.

  The mastic material is a material that adheres the outer plate and the inner plate, increases the rigidity of the entire structure assembled by the adhesion, and acts as a buffer material that prevents vibration and noise of the outer plate.

  When both the outer plate and inner plate are made of steel plates, the method of bonding using mastic material is to apply the mastic adhesive to the steel plate substrate at room temperature and use the baking furnace after coating the steel plate to apply the mastic adhesive. Is cured. The baking temperature is often set to 150 to 210 ° C. The automotive thermosetting mastic adhesive used for such applications is an elastic adhesive mainly composed of synthetic rubber such as nitrile rubber (NBR). However, in such a method involving a baking process at a high temperature, when the coefficient of linear thermal expansion of the outer plate and the inner plate to be bonded is different, the mastic material is cured in a state of being expanded by heating, so it is cooled to room temperature after curing. Due to the different shrinkage rates of the respective materials in the process, the bonded portion is displaced, so that the mastic material is deformed and a stress is generated to restore the original shape. This stress is a factor that distorts the design surface of the outer panel and lowers the merchantability.

  Several proposals have been made as countermeasures. The first proposal is to use a low temperature curable mastic material such as a room temperature curable epoxy adhesive (see Patent Document 1). The low temperature curable mastic material is cured at a low temperature and cured in a bonded state before a large difference in thermal expansion occurs at a high temperature. Therefore, although the degree of distortion after cooling is reduced, the distortion still remains. Therefore, a problem still remains when the rigidity of the outer plate is low.

  The second proposal is to use a composite sheet from which the adhesive layer peels when abnormal stress occurs (see Patent Document 2). However, the composite sheet not only increases the cost as a mastic material, but also has a new problem that the function as a mastic material cannot be exhibited unless the once peeled surface is pressed again.

  A third proposal is to use silicone or a silicone-modified synthetic adhesive as an adhesive for preventing deformation or peeling of the hemming portion between the outer plate and the inner plate (see Patent Document 3). In this method, the flexibility of the adhesive improves the followability to heat deformation of the hemming part, but when used as a mastic material, no mention is made of residual strain after cooling from baking at high temperature. .

  These problems are caused by a construction method in which a mastic adhesive is applied and then applied and baked at a high temperature.

  On the other hand, based on the recent reduction in weight of automobiles, there is a movement to change both the outer and inner panels of the vehicle body panel, or the outer panel to a material other than a steel plate such as plastic or composite material (referred to as a dissimilar material). is there. Among them, FRP (carbon fiber reinforced plastic is harder and lighter than iron, and has attracted attention as an alternative material for automotive steel sheets. The representative of FRP is CFRP (carbon fiber reinforced plastic).

JP2012-140058A JP 2010-094834 A JP 2009-178750 A

  There are several problems in using different materials for at least a part of the vehicle body panel. For example, FRP causes abnormalities such as deformation at a high temperature (150 to 210 ° C.) used in the electrodeposition coating drying process.

  The linear expansion coefficient of FRP is small in the fiber direction and large in the orthogonal direction. Therefore, it differs from the metal linear expansion coefficient both in size and direction. For example, assuming that FRP is bonded to a coated steel sheet with a mastic adhesive, both the heat resistance temperature of FRP is not higher than FRP, but it is heated at 80 ° C or 100 ° C higher than normal temperature. It is conceivable that the joint portion is displaced during heating and cooling, and stress is generated in the mastic material after cooling, resulting in distortion of the design surface.

  Some heat-curable mastic adhesives are softened by foaming in a heat-curing process. Even if such a thermosetting mastic adhesive is cured below the heat resistant temperature of FRP, the volume change of the mastic adhesive due to insufficient foaming or excessive foaming may distort the surface of the vehicle body. It is necessary to manage the amount of coating, the heating temperature, and the heating time that affect it.

  Due to the above problems, it is difficult to use a conventional thermosetting mastic adhesive as a bonding method for bonding different materials such as FRP to a coated steel plate or the like.

  The present invention provides a conventional thermosetting mastic adhesive even when different materials and steel plates or different materials are used in the case of using different materials other than steel plates normally used for vehicle body materials for the purpose of reducing the weight of automobiles. Body panel structure using room-temperature-curable mastic adhesive, which has the same performance as the above, can maintain necessary physical properties for a long time even in high-temperature environments, and is effective as a countermeasure against design surface distortion An object of the present invention is to provide a manufacturing method and a vehicle body panel structure assembled by such a manufacturing method.

The manufacturing method of the present invention is a manufacturing method of a vehicle body panel structure including an outer plate and an inner plate, including the following steps (A) and (B).
(A) Room temperature curing type transformation that can be cured in a normal environment of 0 to 40 ° C. as a mastic adhesive at a joint between an outer plate made of a different material other than a steel plate and an inner plate made of a different material other than a steel plate or a steel plate. A step of applying a silicone adhesive; and (B) a step of curing the mastic adhesive in the normal environment in a state in which the joint portions of the outer plate and the inner plate are overlapped.

In a preferred embodiment, the modified silicone adhesive is
(A) A modified silicone polymer containing a hydrolyzable silyl group in the molecule, and (b) a curing catalyst.

  The vehicle body panel structure according to the present invention is provided with a mastic adhesive interposed between an outer plate made of a different material other than a steel plate, an inner plate made of a different material other than a steel plate or a steel plate, and a joint between the outer plate and the inner plate. And a mastic material formed by curing a room temperature curable modified silicone adhesive as described above, and the outer plate and the inner plate are joined by the mastic material.

  In a preferred embodiment, the outer plate is a fiber reinforced plastic as a different material, and the inner plate is a painted steel plate.

  When manufacturing a vehicle body panel structure in which a fiber reinforced plastic (FRP) and a coated steel plate are bonded, heating is performed by bonding with a room temperature curable mastic adhesive containing a modified silicone polymer and a curing catalyst. It is possible to avoid the occurrence of distortion on the surface of the vehicle body caused by the difference in the linear expansion coefficient at the time, and to bond between different materials without losing the adhesiveness even under a long-term high temperature environment.

  By using a room temperature curable adhesive as a mastic adhesive, surface distortion of the design surface is avoided.

  In particular, by using a modified silicone adhesive as the room temperature curable adhesive, it is heat resistant and durable in use in a high temperature environment such as a hood, and does not depend on the baking process of the coating. . Among room temperature curable adhesives, urethane adhesives are inferior in heat resistance, and therefore can be applied to vehicle body panel structures that do not become high temperature environments, but are difficult to apply to hood members that become high temperature environments. Since the silicone adhesive contains a low molecular weight siloxane, it is liable to cause a contact failure, and there is a problem in adapting to an automobile that is being electrified. The modified silicone adhesive is an adhesive composed of a modified silicone polymer containing a hydrolyzable silyl group in the molecule and a curing catalyst. By the adhesive method using this resin composition, the material is cured by moisture rather than heating, and FRP is used. It becomes possible to bond the coated steel plate. By using this bonding method, it is possible to have the same performance as a mastic material by a bonding method using a conventional thermosetting mastic adhesive without causing deformation due to FRP deformation or a difference in linear expansion coefficient.

  Moreover, it is preferable that it is a polymer which has an acrylic skeleton as a modified silicone polymer. In particular, by using telechelic polyacrylate as the modified silicone polymer, it is possible to have high heat resistance for a long period of time, and while suppressing the significant weight reduction and distortion of the vehicle body due to FRP, as a mastic adhesive This is an epoch-making bonding method capable of achieving both of the two characteristics.

  In the conventional bonding method using mastic adhesive, after applying the adhesive, the car body is assembled and the entire car body is surface-treated, so the surface treatment is insufficient at the mastic adhesive application boundary, and adhesion of the paint film such as electrodeposition coating There was a risk that it would be low. On the other hand, in the production method of the present invention, when a modified silicone adhesive is used, the steel plate of the vehicle body can be bonded in a surface-treated or painted state. It is possible to prevent the steel sheet from being rusted.

  A preferred example of FRP is carbon fiber reinforced plastic (CFRP).

  The vehicle body panel structure manufactured according to the present invention can achieve performance quality equivalent to that of a conventional bonding method using a mastic adhesive, as well as significantly reducing the weight of the vehicle body. Further, since the bonding method does not include a heating step, it is possible to suppress the deformation of different materials and the occurrence of distortion on the surface of the vehicle body as compared with the conventional bonding method using a mastic adhesive.

  A preferred embodiment of the room temperature curable mastic adhesive used in the present invention includes at least a modified silicone polymer containing a hydrolyzable silyl group in the molecule and a curing catalyst, and if necessary, an adhesion imparting agent and a dehydrating agent. , An ultraviolet absorber, a plasticizer, a light stabilizer, an antioxidant, and a filler.

Modified silicone polymer:
The modified silicone polymer is a polymer having a polyoxyalkylene or / and acrylic skeleton and having at least one hydrolyzable silyl group in one molecule.

  The acrylic skeleton is a monomer unit of a (meth) acrylic acid alkyl ester polymer. For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) acrylic acid Butyl, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, (meth) Examples include lauryl acrylate, tridecyl (meth) acrylate, myristyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, biphenyl (meth) acrylate, and the like.

  Further, the (meth) acrylic acid alkyl ester polymer which is the main chain of the acrylic skeleton may contain a monomer unit having copolymerizability with these, in addition to these monomer units. Monomer units containing carboxy groups such as acrylic acid and methacrylic acid; Monomer units containing amide groups such as (meth) acrylamide and N-methylol (meth) acrylamide; Epoxy groups such as glycidyl (meth) acrylate Monomer units containing amino groups such as diethylaminoethyl (meth) acrylate and aminoethyl vinyl ether; monomer units such as polyoxyethylene (meth) acrylate; acrylonitrile, styrene, α- Methyl styrene, alkyl vinyl ether, vinyl chloride, vinyl acetate, vinyl propionate Monomer units resulting from such ethylene; and the like.

In the modified silicone polymer having an acrylic skeleton, the hydrolyzed silyl group may be present at the terminal in the molecule, may be present in the side chain, or may be present in both. Particularly preferred is a telechelic polyacrylate having hydrolyzed silyl groups at both ends.
Specifically, the telechelic polyacrylate is described in the resin disclosed in Japanese Patent Application Laid-Open No. 2004-59782, and the sealing material for building of the Japan Sealant Industry Association, October 1, 2012, 3rd edition, page 207. Things.

  In the modified silicone polymer, the number of hydrolyzable silyl groups is excellent in the balance between the curing rate of the composition and the mechanical properties (particularly elongation) of the cured product, and more excellent in storage stability. 1 to 4 are preferable.

  A modified silicone polymer may be used individually by 1 type, and may use 2 or more types together. Moreover, a well-known thing can be used for a modified silicone polymer. Moreover, a commercial item can be used and S203, S303, etc. are mentioned as the specific example. Examples of the modified silicone polymer having an acrylic skeleton include S943 and MA903 (manufactured by Kaneka Corporation). Examples of the hydrolyzable silyl group-containing telechelic polyacrylate include SA100S, SA310S, and SB802S (manufactured by Kaneka Corporation).

Curing catalyst:
A vinyl polymer having a crosslinkable silyl group is crosslinked and cured by forming a siloxane bond in the presence or absence of various condensation catalysts, so a vinyl polymer condensation catalyst is added as a curing catalyst. can do. Examples of such condensation catalysts include dialkyltin dicarboxylates, dialkyltin alkoxides, intramolecular coordination derivatives of dialkyltin, reaction products of dialkyltin oxide and ester compounds, dialkyltin oxide and silicate compounds. And reaction products and mixtures of tetravalent tin compounds such as oxy derivatives (stannoxane compounds) of these dialkyltin compounds, divalent tin compounds, or these and amine compounds described later, monoalkyl Tins, titanic acid esters and titanium chelate compounds, organoaluminum compounds, tin, titanium, metal salts of carboxylic acids other than aluminum, or reactants and mixtures of these with amine compounds described later, aliphatic amines, fats Unsaturated amines, aromatic amines, other organic amines Compound, or a salt of a carboxylic acid of the amine compounds, other acidic catalysts such as organic acidic phosphate compounds, known silanol condensation catalysts such as basic catalyst can be exemplified. These may be used alone or in combination of two or more.

  Among these condensation catalysts, a tin-based catalyst is preferable because it is excellent in curability of the resulting curable composition, and dibutyltin oxide or dioctyltin is preferable because it is excellent in transparency and non-colorability of the resulting cured product. Reaction products of dialkyl tin oxide such as oxide and ester compounds such as dioctyl phthalate, diisodecyl phthalate, and methyl maleate (for example, MSCAT-01, MSCAT-02, manufactured by Nippon Chemical Industry Co., Ltd.), dibutyltin oxylaurate (For example, Neostan U-130, manufactured by Nitto Kasei Co., Ltd.) and the like are more preferable.

Adhesive agent:
Specific examples of the adhesiveness-imparting agent include organic silane coupling agents such as silane having a (meth) acryloyloxy group, silane having an amino group, silane having an epoxy group, and silane having a carboxyl group; Organometallic coupling agents such as aminoethyl-aminoethyl) titanate and 3-mercaptopropyltrimethotitanate; and epoxy resins. These adhesiveness-imparting agents also have the effect of improving curability.

Dehydrating agent:
In order to improve storage stability, a small amount of a dehydrating agent can be added as long as it does not adversely affect curability and flexibility. Examples of the dehydrating agent include alkyl orthoformate such as methyl orthoformate and ethyl orthoformate, alkyl orthoacetate such as methyl orthoacetate and ethyl orthoacetate, methyltrimethoxysilane, vinyltrimethoxysilane, tetramethoxysilane and tetraethoxysilane. Examples include hydrolyzable organic silicon compounds and hydrolyzable organic titanium compounds. Among these, vinyltrimethoxysilane or tetraethoxysilane is particularly preferable from the viewpoint of cost and effect. In particular, when the curable composition is handled as a product known as a one-component combination type filled in a moisture-proof container in a state containing a curing accelerator, it is effective to use this dehydrating agent.

filler:
Specific examples of the filler include heavy calcium carbonate having an average particle diameter of 1 to 20 μm, light calcium carbonate having an average particle diameter of 1 to 3 μm manufactured by a precipitation method, and colloidal carbonate whose surface is treated with a fatty acid or a resin acid organic material. Calcium carbonate such as calcium and light calcium carbonate; fumed silica; precipitated silica; surface silicone-treated silica fine powder; anhydrous silicic acid; hydrous silicic acid; carbon black; magnesium carbonate; diatomaceous earth; Titanium oxide; Bentonite; Ferric oxide; Zinc oxide; Active zinc white; Shirasu balloon, Perlite, Glass balloon, Silica balloon, Fly ash balloon, Alumina balloon, Zirconia balloon, Carbon balloon and other inorganic hollow bodies; Phenol resin balloon , Epoxy resin balloon, urea resin balloon Organic resin hollow bodies such as plastics, polyvinylidene chloride resin balloons, polyvinylidene chloride-acrylic resin balloons, polystyrene balloons, polymethacrylate balloons, polyvinyl alcohol balloons, styrene-acrylic resin balloons, polyacrylonitrile balloons; resin beads, wood powder Powder fillers such as pulp, cotton chips, mica, walnut flour, rice flour, graphite, fine aluminum powder, flint powder; fibrous fillers such as glass fiber, glass filament, carbon fiber, Kevlar fiber, polyethylene fiber Is mentioned. These fillers may be used alone or in combination of two or more.

  In addition, chemicals such as ultraviolet absorbers, light stabilizers, antioxidants, and plasticizers may be added as necessary.

Example 1
Next, an Example and a comparative example are given and this invention is demonstrated more concretely.

  As a modified silicone polymer, MS polymer S-303 (manufactured by Kaneka Co., Ltd.), which is a polymer having a main chain of polyoxypropylene and having a dimethoxysilyl group at the molecular terminal, is used as 100 parts by weight, and MSCAT-01 is used as a curing catalyst. 3 parts by weight of KBM-603 (Shin-Etsu Chemical Co., Ltd .: N-2- (aminoethyl) -3-aminopropyltrimethoxysilane) as an adhesion-imparting agent and KBM-1003 (Shin-Etsu Chemical) as a dehydrating agent 2 parts by weight, manufactured by Co., Ltd .: vinyltrimethoxysilane, 120 parts by weight, Calfine 500 (manufactured by Maruo Calcium Co., Ltd .: colloidal calcium carbonate) as a filler, and 50 exenol 3020 (manufactured by Asahi Glass: polypropylene glycol) as a plasticizer. Parts by weight, 1 part by weight of Tinuvin 326 (manufactured by BASF) as an ultraviolet absorber, As a light stabilizer, 1 part by weight of Sanol LS770 (manufactured by Sankyo Lifetech Co., Ltd.) was blended to prepare a mastic adhesive.

(Example 2)
As the modified silicone polymer, MS polymer S-943 (manufactured by Kaneka Corporation: modified silicone resin having an acrylic skeleton) was used instead of the MS polymer S-303 in Example 1.

(Example 3)
As the modified silicone polymer, SB802S (manufactured by Kaneka Corporation: hydrolyzed silyl group-containing telechelic polyacrylate) was used instead of the MS polymer S-303 in Example 1.

(Comparative example)
As a comparative example, a commercially available SR seal K40 (manufactured by Sunrise MSI Co., Ltd.), which is a thermosetting rubber mastic adhesive, was used.

  Table 1 summarizes the results of measuring shear adhesion and strain for the examples and comparative examples. Table 1 also shows the necessity of heating.

(Shear adhesiveness)
Shear adhesiveness is applied to a coated steel plate with dimensions of 25 mm x 100 mm and thickness of 0.8 mm, and a CFRP plate with dimensions of 25 mm x 100 mm and thickness of 2.0 mm is bonded to the other side, and the adhesion area is 25 mm. It is fixed with a clip so that the thickness is 10 mm and the thickness is 3 mm. The curing conditions of Examples 1 to 3 were left for 14 days at a temperature of 20 ° C. and a relative humidity of 55%. As a curing condition of the comparative example, heating was performed for 30 minutes in a drying furnace having a temperature of 170 ° C. ± 2 ° C. After the adhesive was cured, the maximum load (kPa) when the test piece was broken was measured at a pulling speed of 50 ± 5 mm / min.

  Shear adhesiveness was measured immediately after curing and after heat treatment at 120 ° C. for 480 hours and 1080 hours, respectively.

(Strain measurement)
After applying 1.0 g of adhesive to the center of a CFRP plate with dimensions 25 mm × 300 mm and thickness 2.0 mm, a 2 mm spacer is placed on both ends of the CFRP, and dimensions 25 mm × 300 mm,
The coated steel plates with a thickness of 0.8 mm are stacked, adjusted so that the thickness of the adhesive is 2 mm, and both sides are fixed with clips. The curing conditions of Examples 1 to 3 were left for 14 days at a temperature of 20 ° C. and a relative humidity of 55%. As a curing condition of the comparative example, it was heated in a drying furnace at a temperature of 170 ° C. ± 2 ° C. for 30 minutes and allowed to stand until it reached room temperature. It was visually confirmed whether or not distortion occurred.
<Evaluation method>
With distortion: ×
No distortion: ○

Claims (7)

A vehicle body panel structure manufacturing method comprising an outer plate and an inner plate including the following steps (A) and (B).
(A) Room temperature curing type transformation that can be cured in a normal environment of 0 to 40 ° C. as a mastic adhesive at a joint between an outer plate made of a different material other than a steel plate and an inner plate made of a different material other than a steel plate or a steel plate. A step of applying a silicone adhesive; and (B) a step of curing the mastic adhesive in the normal environment in a state in which the joint portions of the outer plate and the inner plate are overlapped. The modified silicone adhesive is
The method for producing a vehicle body panel structure according to claim 1, comprising (a) a modified silicone polymer containing a hydrolyzable silyl group in the molecule, and (b) a curing catalyst.   The method for producing a vehicle body panel structure according to claim 1 or 2, wherein the modified silicone polymer is a polymer having an acrylic skeleton.   The method for producing a vehicle body panel structure according to any one of claims 1 to 3, wherein the modified silicone polymer is a telechelic polyacrylate.   The vehicle body panel structure manufacturing method according to any one of claims 1 to 4, wherein the outer plate is a fiber reinforced plastic as a different material, and the inner plate is a painted steel plate.   A mastic material made of a hardened room temperature curable denatured silicone adhesive as a mastic adhesive, which is interposed between the outer plate made of a different material other than steel plate and the inner plate made of a different material other than steel plate or steel plate A vehicle body panel structure in which the outer plate and the inner plate are joined by the mastic material.   The vehicle body panel structure according to claim 6, wherein the outer plate is a fiber reinforced plastic as a different material, and the inner plate is a painted steel plate.