JPH0420381B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a reinforcing material for thin steel plates, and more particularly to a reinforcing material that is attached to thin steel plates for reinforcing thin steel plates such as automobile doors and rear fenders. [Prior Art] When a metal outer panel (such as a thin steel plate) such as a car door is driven on a rough road, stress concentration may occur at a certain point on the outer panel, causing out-of-plane deformation of the outer panel.
In order to prevent this, it has been conventional practice to attach a reinforcing material to the area. An epoxy prepreg type material is known as one of such reinforcing materials. This is constructed by laminating a thermosetting adhesive layer made of a mixture of an epoxy resin, a hardening agent, and a filler on one side of a reinforcing layer (glass cloth). Additionally, an epoxy foam type is known, which is used to reduce the thickness of the reinforcing material of the epoxy prepreg type to improve economic efficiency and weight reduction, as well as to improve its adhesion to plate materials. An unfoamed foam material is attached to one side, leaving a surface for attachment to the metal plate material. (For example, JP-A-57-
(Publication No. 151348) [Problems to be Solved by the Invention] However, the conventional epoxy prepreg type has disadvantages in that it has poor oil surface fixing properties and, in particular, extremely poor tackiness at low temperatures. Furthermore, even if the epoxy foam type is used, it still has a disadvantage in that it has poor oil surface fixing properties and can therefore only be applied to coated plates. Furthermore, both of the conventional reinforcing materials mentioned above have poor storage stability, and have the disadvantage that the adhesive layer easily gels when stored at high temperatures for a long period of time. An object of the present invention is to provide a novel reinforcing material that eliminates the drawbacks of the conventional reinforcing materials. [Means for solving the problems] In order to achieve the above object, according to the present invention,
In a reinforcing material for a thin steel plate consisting of a thermosetting adhesive layer and a metal reinforcing layer serving as a reinforcing material supporting one side of the reinforcing material, when shaping the thermosetting adhesive layer into a sheet shape,
SBR whose added mixture components are mainly 10-40% by weight,
10-40% by weight acrylic polyfunctional monomer, 30-40% by weight
A reinforcement is provided consisting of 60% by weight of an inorganic filler and the required amount of peroxide as a polymerization agent for the acrylic polyfunctional monomer. In other words, the reinforcing material of the present invention is characterized by specifying the mixed components and their proportions constituting the thermosetting adhesive layer, thereby achieving excellent oil surface fixing properties that could not be achieved with conventional reinforcing materials. A reinforcing material with storage stability and high mechanical strength was obtained. Among the mixed components of the thermosetting adhesive layer, SBR (styrene butadiene rubber) contributes to improving the fixability of the mixture of the acrylic polyfunctional monomer and the inorganic filler to the oil surface. The mixing ratio of SBR is preferably 10 to 40% by weight, especially 15 to 23% by weight.
Weight percent is preferred. SBR mixing ratio is 10% by weight
If the amount is less than 40% by weight, the oil surface fixing properties at low temperatures will be poor, and if it is more than 40% by weight, the reinforcing properties (bending strength) will be reduced. Further, the acrylic polyfunctional monomer is not particularly limited as long as it provides reinforcing properties to the adhesive layer, and examples thereof include ethylene glycol dimethacrylate, 1,6 hexane glycol dimethacrylate, and ethoxylated bisphenol. Diesters such as A dimethacrylate, triesters such as trimethylolpropane trimethacrylate, and tetraesters such as tetramethylolmethanetetraacrylate are used. The mixing ratio is preferably 10 to 40% by weight, especially 15 to 40% by weight.
20% by weight is preferred. If this mixing ratio is less than 10% by weight, the reinforcing properties will decrease, and if it exceeds 40% by weight, the rigidity will become too high, and the thin steel plate will become distorted due to shrinkage of the adhesive layer during curing. The reason why polyfunctional acrylic monomers are used is to avoid the characteristic odor that occurs when monofunctional acrylic monomers are used. The inorganic filler is used to improve the reinforcing properties of the adhesive layer, prevent sagging, increase the amount, etc., and its type is not particularly limited, but calcium carbonate, silica, etc. are usually used. The mixing ratio is preferably 30 to 60% by weight, particularly preferably 30 to 45% by weight. When this mixing ratio is less than 30% by weight, the viscosity decreases significantly and it becomes difficult to maintain the shape of the sheet-like molded layer, while when it exceeds 60% by weight, the viscosity increases significantly and the oil surface fixing property decreases. Peroxide is added in a required amount as a polymerization agent for the acrylic polyfunctional monomer, and is usually added in an amount of 0.1 to 5 parts by weight per 100 parts of the acrylic polyfunctional monomer. Preferred peroxides in the present invention have a decomposition temperature of 80 to 130°C, such as dialkyl peroxides such as 1,1-di(t-butylperoxy)3,3,5-trimethylcyclohexane, and methyl isobutyl ketone peroxide. and other ketone peroxides are used. In addition, the metal reinforcing layer, which is a support that supports one side of the thermosetting adhesive layer, is not particularly limited as long as it has good shape followability, high rigidity, and conductivity, but aluminum, iron, and galvanized materials are generally used. Steel plates, tin plated steel plates, etc. are used. In order to improve adhesion, the reinforcing material for thin steel sheets of the present invention is formed by adding 2 to 8% by weight of epoxy resin and 2 to 20% by weight when forming the thermosetting adhesive layer into a sheet shape.
It is desirable to further add synthetic resins or natural resins such as hydrogenated ester resins having a tackifying effect of. If the epoxy resin content is less than 2% by weight, the adhesion will be poor, and if it exceeds 8% by weight, it will flow easily and have difficulty retaining its shape before heat curing, and will become too hard after heat curing, causing problems in the reinforcing material. Undesirable. If the synthetic resin or natural resin is less than 2% by weight, the adhesion will be poor like epoxy resin, and if it exceeds 20% by weight, the resin will melt during heat curing, causing sagging,
Misalignment occurs, which is not desirable. Furthermore, the metal reinforcing layer of the reinforcing material for thin steel sheets in the present invention includes five general-purpose metal fibers such as aluminum, copper, nickel, iron, etc. in the adhesive layer so that the electrodeposition paint for rust prevention can adhere to the metal reinforcing layer. ~15% by volume
It is preferable to add. If the amount of metal fibers is less than 5% by volume, conductive curing will not be obtained and the electrodeposition paint will not adhere to the metal reinforcing layer, and if it exceeds 15% by volume, there will be too many metal fibers, resulting in poor oil surface fixation. This also causes distortion in the reinforcing material, which is undesirable. The reinforcing material for thin steel plates according to the present invention will be explained based on the drawings. That is, the reinforcing material for thin steel sheets of the present invention mainly consists of
The thermosetting adhesive layer 1 is formed by adding and mixing SBR, an acrylic polyfunctional monomer, an inorganic filler, and a required amount of peroxide as a polymerization agent for the acrylic polyfunctional monomer, and forming it into a sheet. A surface 2 is attached to the steel plate, and a metal reinforcing layer 3 serving as a reinforcing material supporting the adhesive layer 1 is laminated on the other surface. Next, a method for producing a reinforcing material for thin steel plates according to the present invention will be explained. SBR and acrylic polyfunctional monomers are put into a commonly used kneader (kneading machine) and sufficiently stirred and mixed, after which inorganic fillers and peroxide are added (if necessary, epoxy resin, synthetic resin, natural (Resin, metal fiber, etc. are also added.) Further kneading is performed. Next, the kneaded product is formed into a sheet to form a thermosetting adhesive layer, and a metal reinforcing layer is laminated on one side to complete the reinforcing material of the present invention. The other side of the adhesive layer serves as the surface to be adhered to the thin steel plate, and this surface is covered with a release paper to prevent staining due to dust and the like and deterioration of adhesion. [Function] The thin steel plate reinforcing material of the present invention is applied to metal outer plates (thin steel plates) such as automobile rear fenders and doors.
By pasting it on the back side (stress concentration area) and then heating it at about 180℃ for 20 to 30 minutes to harden it, it has good fixing and adhesion properties even on thin steel plates whose surfaces are oily. This effectively prevents out-of-plane deformation of the thin steel plate even when an automobile runs on rough roads. [Effects of the Invention] Since the reinforcing material for thin steel plates of the present invention has the above-described structure and function, it not only has high mechanical strength such as bending strength, shear strength and impact resistance after heat hardening, but also It has excellent oil surface fixability and oil surface adhesion, and also has very good storage stability, and the adhesive layer does not easily gel even if stored at high temperatures for a long period of time. Furthermore, if the reinforcing material is applied to a thin steel plate at room temperature, then electrocoated and then heated, the curing process of the reinforcing material and the electrocoated coating can be performed at the same time, which is economical. [Example] Next, the present invention will be explained in more detail with reference to Examples. As the reinforcing material, unless otherwise specified, samples were prepared by laminating galvanized steel plates with a thickness of 0.2 mm as the reinforcing layer and with a thickness of 1 mm as the adhesive layer.
The thin steel plate used was a cold-rolled steel plate SPCC manufactured by Nippon Steel Corporation with a thickness of 0.8 mm, and the heat curing conditions after attaching the reinforcing material to the thin steel plate were 180°C x 20 minutes. [Test method] Oil surface adhesion A sample is attached at room temperature to an oil surface thin steel plate that has been drained of oil for 24 hours, and after being left for 1 minute, the displacement of the sample is measured when the thin steel plate is stood vertically. Excellent means that there is no displacement, Good means that there is no displacement but a portion of the sample is lifted from the thin steel plate, and Poor means that there is displacement. Slamming test Impact resistance is measured based on JIS K6830 26.3(2). Distortion of thin steel plate A sample is attached to a thin steel plate, and the distortion of the thin steel plate after heating and hardening is measured using a coordinate measuring machine. 0.1mm
Less than 0.1 mm was considered absent, and 0.1 mm or more was considered present. Reinforcement property (bending strength) The sample was attached to a thin steel plate, and after heating and hardening it was 5mm/
The bending strength was defined as the load at 1 mm deformation when deformed at min. 6Kg/25mm (width) or more high, 4
Kg/25mm (width) or more and less than 6Kg/25mm (width) was considered medium, and less than 4Kg/25mm (width) was considered low. Displacement during hardening After attaching the sample to a thin steel plate and curing by heating, measure the dislocation of the sample when the thin steel plate is held vertically. If there was no deviation, it was judged as “no”, and if there was a deviation, it was judged as “present”. Shear strength: Measured in accordance with JIS K 6850 on a 0.5 mm thick adhesive layer that was cured by heating. Possibility of electrodeposition coating The reinforcing material was immersed in a cationic electrodeposition coating solution at room temperature, and after applying a DC current of 200V for 1 minute, it was visually confirmed whether or not the reinforcing layer was coated with electrodeposition. If it is not painted, it is acceptable; if it is not painted, it is not acceptable. Examples 1 to 4, Comparative Examples 1 to 8 After mixing SBR and acrylic polyfunctional monomer using a kneader (kneader manufactured by Irie Seisakusho, PNV-1 type), peroxide and inorganic filler were further added and kneaded. . The mixing ratio is shown in Table 1. This kneaded product was formed into a sheet, a reinforcing layer was laminated on one side of the sheet, and its mechanical strength, properties, etc. were measured according to the test method described above. The results are shown in Table 2.

【table】

[Table] Comparative Example 1 is a conventional epoxy prepreg type reinforcing material, with a glass cloth (reinforcing layer), an epoxy resin, a curing agent, a filler, and an adhesive layer (thickness
Comparative Example 2 is a conventional epoxy foam type, in which a glass cloth is laminated with an adhesive layer (thickness
0.5 mm) and a foamed material (5 to 7 mm thick) was used, with the adhesive surface left open to the thin steel plate. Examples 5 to 7 Regarding the reinforcing materials of the present invention, the shear strength (Kg/cm ² ) of the cured adhesive layer was measured. The addition mixing ratio (weight %) and results are shown in Table 3 below. Furthermore, AF100 means 100% interface failure rate.
CF30AF70 means that the cohesive failure rate is 30% and the interfacial failure rate is 70%.

【table】

[Table] Examples 8 to 9, Comparative Examples 9 to 10 The composition with the blending ratio used in Example 7 was designated as A, and the oils were prepared by varying the amount of aluminum fiber mixed in composition A. surface fixability,
Table 4 shows the distortion of thin steel plates and whether or not they can be electroplated.
% is expressed as a capacity ratio.

[Table] Example 10 The same test was conducted under the same conditions as in Examples 1 to 7 above, except that the acrylic polyfunctional monomer was changed to ethoxylated bisphenol A dimethacrylate. As a result, the same results as Examples 1 to 7 were obtained.

[Brief explanation of drawings]

The drawing is a sectional view of the reinforcing material for thin steel plates of the present invention. 1...Adhesive layer, 2...Steel plate adhesion surface, 3...Reinforcement layer.

Claims (1)

[Scope of Claims] 1. A reinforcing material for a thin steel plate comprising a thermosetting adhesive layer and a metal reinforcing layer serving as a reinforcing material supporting one side of the reinforcing material, wherein the thermosetting adhesive layer is mainly composed of SBR, SBR, It is a sheet-like molded layer formed by adding and mixing the three components of an acrylic polyfunctional monomer and an inorganic filler with a required amount of peroxide as a polymerization agent for the acrylic polyfunctional monomer, and the mixing ratio of the three components is SBR10~ 40% by weight, 10-40% by weight of acrylic polyfunctional monomer and 30-60% of inorganic filler
A reinforcing material for thin steel sheets characterized by weight%. 2 When molding the thermosetting adhesive layer into a sheet shape, 2 to 8% by weight epoxy resin and 2 to 20% by weight
The reinforcing material according to claim 1, characterized in that a synthetic resin or a natural resin is added and mixed therein. 3. The reinforcing material according to claim 1 or 2, wherein 5 to 15% by volume of metal fibers are added when the thermosetting adhesive layer is formed into a sheet.