JPH039139B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention is applicable to joints between, for example, steel plates of vehicles.
This is a body sealer that is used as a base coat for paint. [Prior Art] In vehicles, body sealers are applied to the joints and joints of steel plates and other parts to fill in the gaps before painting. The following steps are required to finish the paint job after body sealer is applied to a car:
The process is as follows. Apply body sealer to the joints of the steel plates.
Perform temporary baking. This temporary baking may be omitted in some cases. Paint the outer panel with an intermediate coat. Apply a top coat to the interior panels (inside the doors, trunk room, engine room). Apply blackout painting (painting the door frame). Please note that this blackout painting is not available depending on the car model. Do the baking. Mask the door frame. Please note that vehicle models without blackout paint will not be masked. Top coat the outer panel. Finish baking. [Problems to be Solved by the Invention] In the above steps 1 to 2, a phenomenon occurs in which the plasticizer in the sealer is extracted into the intermediate coating for exterior panels in the areas where the sealer has been applied. When an intermediate coat is applied to the exterior panel, the paint also spreads to the interior panel and door frame. If there is a top coat or blackout coating on the inner plate,
The intermediate coat paint for the outer panel and the top coat paint or blackout paint for the inner panel overlap in a wet state. If the overlap is in an area where a sealer has been applied, the plasticizer will be extracted into the intermediate coating for the exterior panel, causing the topcoat and blackout coating on the interior panel to be repelled, which is an inconvenience. occurs. The phenomenon that the plasticizer in the sealer is extracted into the intermediate coating for exterior panels occurs when the proportion of polar solvent in the intermediate coating for exterior panels is high, even if the sealer is pre-baked. Recently, emphasis has been placed on the smoothness of automobile paint films, and intermediate coatings for exterior panels that contain a large amount of polar solvents are being used. As a result, there is a problem in that the top coat or blackout paint on the inner panel is repelled, resulting in uneven paint. The present invention aims to provide a body sealer that does not cause the above-mentioned disadvantages and has excellent sealing and covering properties. [Means for Solving the Problems] The present inventors continued their intensive research on body sealers and obtained the following knowledge. A polar solvent is added to the sealer, which is based on vinyl chloride resin and contains a dialkyl phthalate plasticizer with a molecular weight of 500 or less, such as dioctyl phthalate (DOP), diethyl phthalate (DEP), and dibutyl phthalate (DBP). When an intermediate coating containing 10% by weight or more of sealer is applied, the plasticizer in the sealer is likely to be extracted into the intermediate coating, and as a result, the surface tension of the intermediate coating decreases. Here, polar solvents refer to alcohol, ester, ketone, and ether solvents. For example, alcohol solvents include n-butanol, isopropyl alcohol, methanol, ethanol, methoxybutanol, and ester solvents include: Ethyl acetate, carbinol acetate, etc., and ketone solvents include MEK,
MIBK etc. are used. If a top coat is applied while the intermediate coat is still wet, the surface tension of the top coat becomes relatively high and the top coat is repelled. There is a need for a body sealer in which the plasticizer is less likely to be extracted by polar solvents in the intermediate coat applied onto the sealer and, as a result, does not reduce the surface tension of the intermediate coat. The body sealer to which the present invention is applied, which was made based on such knowledge, is used in the assembly process of vehicles etc. that are painted with intermediate paint with a high content of polar solvents, and when the total weight is 100%, , vinyl chloride resin 15-30% by weight, eyelid agent 20-40% by weight, filler 30-50% by weight, adhesion promoter 0.5-5% by weight,
Contains 0.1-1% by weight of stabilizer, and at least 30% by weight of the plasticizer has a molecular weight of 1000-1000%.
1500 polyester plasticizer or epoxidized soybean oil. The vinyl chloride resin may be one commonly used for plastiazole, and may be a homopolymer of vinyl chloride or a copolymer of this and other copolymerizable monomers. Further, a mixture of several types of polymers or a polymer blend may be used. Examples of fillers include calcium carbonate, clay, talc, silica, bentonite, kaolin, and titanium oxide. Plasticizers with a molecular weight of 500 to 2000 include polyester plasticizers and epoxidized soybean oil plasticizers. If the molecular weight of the plasticizer is less than 500, the plasticizer is likely to be extracted by the polar solvent in the intermediate coat, which lowers the surface tension of the intermediate coat and repels the top coat. If the molecular weight is 2000 or more, the plasticization efficiency decreases, resulting in a decrease in hardness and shear adhesive strength.
More preferably, it is a plasticizer with a molecular weight of 1000 to 1500. The adhesion promoter may be acrylic, amine, isocyanurate, or a combination of amine and isocyanurate. Stabilizers include metal salts such as barium, zinc, lead, and calcium, and dibasic lead sulfite. [Function] Even if an intermediate coating with a high content of polar solvent (polar solvent is 10% by weight or more of the total solvent) is applied to the body sealer to which the present invention is applied, the plasticizer is difficult to extract, and the plasticizer is difficult to extract. It does not lower the surface tension of the paint. Therefore, even if a top coat is applied while the intermediate coat is still undried, the top coat will not be repelled because the surface tension of the top coat is relatively low. [Example] Examples of the present invention will be described in detail below. The table below shows the composition of the body sealer and the results of performance tests. Examples 1 to 4 in the table
is an example of a body sealer to which the present invention is applied, and Comparative Examples 1 to 4 are examples of body sealers to which the present invention is not applied. First, adjust the body sealer for each example. Vinyl chloride resin (G-37J, G-103ZX [manufactured by Nippon Zeon Co., Ltd.]), plasticizer (polyester plasticizer W-
1200: Molecular weight 1200 (manufactured by Dainippon Ink and Chemicals Co., Ltd.),
Polyester plasticizer W-2600; molecular weight 2600,
(manufactured by Dainippon Ink and Chemicals Co., Ltd.), dioctyl phthalate (DOP); molecular weight 390, dibutyl phthalate (DOP); molecular weight 278) calcium carbonate (NS-No.
100 [manufactured by Nitto Funka Co., Ltd.], Hakuenka CCR [manufactured by Shiraishi Calcium Co., Ltd.]), and other additives were weighed according to the composition (wt%) shown in the table below. After dispersing the mixture well and mixing for 30 minutes using a kneader equipped with a vacuum device, a body sealer is obtained by stirring for 60 minutes to remove bubbles. The degree of pressure reduction is -72±4 cmHg. Next, the performance of each example body sealer was tested. Paintability is without pre-baking of sealer,
Test both with and without sealer calcination. For the former, first apply a sealer and then apply an intermediate coat (film thickness 30 μm) as is (while still wet). Apply a topcoat (film thickness: 30 μm) while still wet. Bake it at 140℃ for 30 minutes. For the latter, first apply the sealer, then heat it to 100℃.
Temporarily bake the sealer for 10 minutes. Next, apply an intermediate coat (film thickness 30μm). Apply a topcoat (film thickness 30μm) while still wet. 140 it
Bake for 30 minutes. After this baking process is complete, examine the appearance of the paint. In addition, in both tests, the ratio of polar solvent to the total solvent was 19.6 for the intermediate coating paint.
%. Shear adhesive strength is measured as follows. First, a sealer is applied to the center of the cationic electrodeposition coated plate, and another cationic electrodeposition coated plate is pasted to the area where the sealer is not coated, sandwiching a spacer (thickness 1 mm) treated with a release agent. Place a preheated 500g weight on the surface to keep it in place. Bake it at 140℃ for 30 minutes. After cooling, the weight was removed and the sample was allowed to stand for another 20 to 24 hours, after which the spacer and protruding sealer were removed with a sharp knife so as not to apply stress to the adhesive surface, and a test piece was prepared. Both ends of this test piece (two cationic electrodeposition coated plates) were fixed to the holder of a tensile testing machine, and the maximum tensile shear load was measured along the lamination direction at a tensile speed of 50 mm/min. The shear adhesive strength is calculated using the following formula. Shear adhesive strength (Kg/cm ² ) = Maximum shear load (Kg) / Adhesive area (cm ² ) To measure hardness, place the sealer in a flat-bottomed container with a diameter of 70 mm and a depth of 15 mm to a thickness of 12 mm or more. Place it so that no air gets in, heat it at 140℃ for 30 minutes, then let it cool.
After being left at room temperature for 20 to 24 hours, the hardness was measured using a hardness meter specified in JIS.K6301. As shown in the table below, the body sealers of Examples 1 to 4 had good paintability, but the top coat of the body sealers of Comparative Examples 1 to 2 peeled off. Furthermore, in Comparative Examples 3 and 4, the paintability was good, but the shear adhesive strength and hardness were reduced.

【table】

[Table] [Effects of the Invention] As explained above, the body sealer to which the present invention is applied does not allow the plasticizer to be extracted into the intermediate coating even if an intermediate coating with a high content of polar solvent is applied thereon. It does not reduce the surface tension of the intermediate coating. Therefore, even if the top coat is further applied while the intermediate coat is still wet, the top coat will not be repelled. As a result, there will be no unevenness in the coating, and the coating will have a beautiful finish, as well as the intermediate and top coats. The body sealer of the present invention also has excellent hardness and shear adhesion.

Claims (1)

[Claims] 1. In a body sealer used in the assembly process of vehicles, etc. painted with intermediate paint with a high content of polar solvents, when the whole is taken as 100% by weight,
Vinyl chloride resin 15-30% by weight, plasticizer 20-40% by weight, filler 30-50% by weight, adhesion promoter 0.5-5
% by weight, stabilizer from 0.1 to 1% by weight, and at least 30% by weight of the plasticizer has a molecular weight of
A body sealer characterized in that the plasticizer is at least one of a polyester plasticizer of 1000 to 1500 or epoxidized soybean oil.