JPS6284175A - Sealing material composition having high permeability - Google Patents

Abstract

PURPOSE:The titled composition useful for panel bonding parts for automobile bodies, well penetrating into gaps at normal temperature, causing neither sagging nor dropping, having easy coating operation, obtained by blending a specific base resin with an agent for lowering surface tension, a thixotropy imparting agent, etc., in a good balance. CONSTITUTION:(A) 30-60pts.wt. copolymer of vinyl chloride resin and vinyl acetate resin is blended with (B) 40-70pts.wt. vinyl chloride resin to provide thixotropy by secondary aggregation of fine particles, (C) 40-80pts.wt. calcium carbonate subjected to surface treatment with a vegetable oil or fatty acid, (D) 1-5pts.wt. fine powder silica, (E) 1-5pts.wt. silane or titanate type coupling agent, (F) 100-200pts.wt. filler, (G) 100-200pts.wt. plasticizer and (H) 7-22pts. wt. modified polyamide, to give the aimed composition.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to a highly permeable sealing material used for panel joints of automobile bodies, etc. In particular, it permeates into the gaps between steel sheets as appropriate at room temperature, and is suitable for use at room temperature or when heated. The present invention relates to a highly permeable vinyl chloride plastisol sealant composition that does not run off.

(Conventional technology) Conventional vinyl chloride plastisol sealants have the following three properties.
Broadly divided into types.

i) It has low fluidity and does not penetrate into the panel gap; ii) It has fluidity at room temperature and penetrates into the panel gap; iii) It has no fluidity at room temperature but flows when it is hot and penetrates into the panel gap. Something to do.

(Problems to be Solved by the Invention) However, the type 1) sealant does not penetrate into the panel gap, so as shown in FIG.
12, the sealant 15 does not penetrate into the gap 14 of the joint 13, and if the excess sealant is removed with a spatula, the adhesion area is insufficient, which may cause water leakage from the outside of the car body or rust on the car body. It causes an invitation. Also ii
) and iii) types of sealants are good if the panel to be coated has a relatively small angle and is flat, but if the panel has a large inclination, it is more likely to sag on the vertical or rear side due to unevenness of the sealant. There was a problem.

(Means for Solving the Problems) This invention was made by focusing on such conventional problems, and it is essential that the sealant that penetrates into the panel gap has a low viscosity. Naturally, when such a material is applied to a vertical surface, it drips significantly, causing problems in terms of workability and appearance. Therefore, the basic resins are vinyl chloride-vinyl acetate copolymer resin with high physical properties and good low-temperature setting properties, and vinyl chloride resin with thixotropic properties, and a balance of surface tension lowering agents, thixotropy imparting agents, plasticizers, and fillers is used. (By blending, we can control in a well-balanced manner the characteristics where when high shear is applied to the material, that is, the clay temporarily lowers at the moment it is discharged from the gun of the applicator, and then recovers its viscosity over time.) This invention was achieved by achieving both the contradictory properties of penetrating into the gaps between panels and not sagging, and also by considering the mechanical properties so that it can withstand the environment in which it will be used after the completion of an automobile body, etc. I came to the conclusion.

Therefore, the sealant composition of the present invention includes 40 to 70 parts by weight of a vinyl chloride resin that imparts thixotropy through secondary aggregation of microparticles, vegetable oil or Fatty acid surface treatment calcium carbonate 40-80 parts by weight, 1 part fine silica
~5 parts by weight, 1~5 parts by weight of silane or titanate cupping agent, 100~200 parts by weight of filler, 1 part by weight of plasticizer
00 to 200 parts by weight, and 7 to 22 parts by weight of modified polyamide.

In the sealing agent of this invention, the vinyl chloride resin used as the basic resin is a copolymer resin of vinyl chloride resin and vinyl acetate resin, which has good low-temperature setting properties and high material properties.
~60 parts by weight of vinyl chloride, which imparts thixotropy through secondary agglomeration of microparticles to improve discharge properties and prevent flow, improves physical properties and improves the properties of the sealant. Prevents dripping during baking.

If the blended amount of the vinyl chloride resin/vinyl acetate resin copolymer resin is too large (more than 70 parts by weight), the fluidity will be too high and it will easily drip down on vertical surfaces, causing storage stability problems and increasing costs. Also, if the amount of vinyl chloride resin used to impart thixotropy increases and exceeds 70 parts by weight, it will become too thixotropic and no dripping will occur, but no permeability will be obtained. In this case, although a permeability effect can be obtained, sag occurs and the workability and appearance deteriorate.

In this invention, the state of imparting thixotropy is the most important factor, and in order to obtain low viscosity, easy permeation, non-flowing properties, and mechanical and physical performance, the vinyl chloride resin imparting thixotropy and the low temperature It is preferable that the setting copolymer resin of vinyl chloride resin and vinyl acetate resin be used in approximately equivalent amounts.

In addition, the sealing material of the present invention contains 40 to 80 parts by weight of vegetable oil-treated calcium carbonate or fatty acid-treated calcium carbonate as a thixotropy regulator, and 1 to 100 parts by weight of finely divided silica.
Although used in combination with 5 parts by weight, vegetable oil-treated calcium carbonate has the ability to impart thixotropy in a static state and maintain fluidity when heated.

If used in large quantities, it tends to flow due to heating in a sealing baking oven, so the blending amount is 10 to 40.
Parts by weight are appropriate. In addition, fatty acid-treated calcium carbonate, like vegetable oil-treated calcium carbonate, gives thixotropic liquid properties in a static state, but becomes less clayey under high shear.
Moreover, the time required for recovery to thixotropic liquid properties is long, that is, the residence time in the low viscosity region is long, so that the permeation width increases. However, if a large amount is blended, the physical properties will be impaired, so the appropriate amount to be used is 30 to 80 parts by weight.

In addition, fine powder silica used as a thixotropy imparting agent has a higher viscosity reduction rate under high shear than the above two types of thixotropy imparting agents, and contributes to increasing the penetration width. However, if a large amount is used, it has the disadvantage of impairing the adhesion to the adherend, so the appropriate amount is 1 to 5 parts by weight.

In addition to the above, a silane or titanate camping agent is used as a surface tension reducing agent to improve the wettability to the panel in order to increase the penetration width. The amount to be used is preferably 1 to 5 parts by weight, since no increase in the effect is observed even if the amount is more than 5 parts by weight.

A modified polyamide is blended as a component that allows the sealant to adhere to the object to be coated.Those containing a large amount of free amine exhibit strong adhesion, but the color tone becomes brown after baking, which is unfavorable in terms of appearance as a sealant. Also, those containing less free amine have a lighter color tone after baking, but are inferior to those containing more free amine in terms of adhesion. From the above, it is necessary to blend both of them in a well-balanced manner, and the blending amount in this invention is 2 to 7 parts by weight of a modified polyamide with a high free amine content (amine value 250±30) and a modified polyamide with a low free amine content (free amine value: 250±30). 80±20) is preferably 5 to 15 parts by weight.

Calcium carbonate, which is commonly used, is used as a filler, but in order to achieve the purpose of this invention, it is
00 parts by weight.

In addition, a phthalic acid plasticizer is used as the plasticizer, but if there is too little plasticizer, the sealing material will become hard, and if too much, it will become soft, which poses a problem for workability.In this invention, the amount is set at 100 to 200 parts by weight. .

Furthermore, the sealing material of the present invention may contain organic tin as a stabilizer (to prevent deterioration of the basic resin) and calcium oxide or the like as a moisture absorbent (to prevent foaming).

The sealing material of this invention having the above-mentioned structure is
For example, it is used as follows. That is, as shown in FIG. 1 (8), the sealant is applied in a bead shape to the joints (for example, spot welds) of metal plates 1.2 such as steel plates using a sealing gun (not shown), and then the sealant is applied with a brush or spatula. The sealing material in the gap 4 is completely sealed by making the correction as shown in FIG.

In this way, the sealing material of the present invention can be used for sealing various parts, especially gaps at spot welds in an automobile body, such as roof trip rails 5, trunk openings, etc. as shown in FIG. 6. Used for sealing gaps in areas such as the rear combination lamp 7 and the floor 8.

Sealing of such gaps in an automobile body is usually carried out in the following stages. That is, after degreasing the white body with an alkaline solution, it is chemically treated with a chemical conversion treatment solution such as a phosphate aqueous solution, and then immersed in a cationic electrodeposition bath or an anionic electrodeposition bath to coat the car body with, for example, 170 ℃30
After baking for a minute, apply a sealant to the sealing area with the gap as described above using a sealing gun,
Then, after correction, for example, 5-2 at 120-170℃
The sealant is prebaked for 0 minutes, preferably at 130 to 150°C for 15 to 20 minutes. Then, if necessary, apply an intermediate coat using a spray coating method, etc., and then apply a 140-1
After baking at 60°C for 20 to 40 minutes, and then applying a top coat using a spray coating method, etc.,
By baking at ℃ for 20 to 40 minutes, the sealing part can be completed at the same time as painting the car body.

(Examples) Next, the present invention will be further explained with reference to Examples and Comparative Examples.

・111～3. 911-3 The raw materials shown in the upper row of Table 1 were mixed and dispersed in the blending ratio, and the sealants of Examples 1-3 and Comparative Examples 1-3 were prepared by mixing and dispersing the raw materials shown in the upper row of Table 1 in the blending ratio. ! The test was conducted using the method based on the above, and the results are listed in Table 1. The fluidity is determined by the nozzle (gun tip) shown in Fig. 4, l cc
/sec discharge speed, 1cm from the object to be coated (coated board)
Each sealing material was discharged for 1 second at a distance of m, and evaluated by measuring the flow distance on the vertical plane after 10 minutes at room temperature and 30 minutes at 140°C. As shown in Figure 5, the gap (g) is set to 200 μm, and the
Each sealant is discharged at a speed of 2 from the nozzle shown in Figure 4.
As cc/sec, the angle between the nozzle and the steel plate is 70
The sealing material was applied to the gap between the steel plates 11 and 12 so that the sealing material was 11.degree., and the penetration width after baking was measured and evaluated. 4th above
The nozzle shown in the figure is made of material S, S, and unichrome plating.
=48.5mllls 12 = 9TI1111%
lz=8mm, la=6.5mms=
7mm, D = 4mm, D2 = 2.5m
m-, D3 = 1.0 mm.

p4=5 mm, where D1 to D4 represent the diameter of each part.

Also, in Fig. 5, I, + = 200 mm, Lz
indicates the width of penetration of the sealant into the gap.

In addition, storage stability was evaluated by measuring the viscosity fluctuation rate after leaving the sealing material sample at 40°C for 72 hours, and the color tone after baking was
It was adhered to a painted board and evaluated based on the color tone after baking at 160°C for 1 hour.

(Effects of the Invention) As explained above, the sealant composition of the present invention has good low-temperature stability and is effective in secondary aggregation of fine particles and a copolymer resin of vinyl chloride resin and vinyl acetate resin that has high physical properties. By using vinyl chloride resin as the basic resin that gives good thixotropy, and adding specific amounts of vegetable oil or fatty acid surface-treated calcium carbonate, finely divided silica, silane or titanate coupling agent, filler and modified polyamide, It penetrates appropriately into the gaps between steel plates at room temperature, is easy to apply, and does not penetrate between the steel plates at room temperature or when heated, so it is extremely useful as a sealing material between metal plates, such as sealing gaps in automobile bodies. It is something.

[Brief explanation of drawings]

FIG. 1(A) is a perspective view of a steel plate joint showing a state in which the sealant of the present invention is applied to the steel plate joint with a sealing gun. FIG. A perspective view of the steel plate joint in the corrected state; Figure 2 is a schematic perspective view of the car body showing the parts of the car where the sealant should be applied; Figure 3 shows the state in which the conventional sealant is applied to the steel plate joint. A cross-sectional view of a steel plate joint. Figure 4 is a cross-sectional view of a nozzle used to fill the gap between steel plates in the example and comparative example. Figure 5 is a cross-sectional view of the sealant in the example and comparative example. FIG. 2 is an explanatory diagram of permeability measurement. 1.2... Steel plate 3... Seam 5... Roof drip rail 6... Trunk opening 7... Rear combination lamp 8... Floor 11.12... Steel plate 13
... Seam 14 ... Gap 15 ...
Sealing material Fig. 1 (A) (B) Fig. 2 Fig. 3 74 15 1z Fig. 4

Claims (1)

[Claims] 1. Copolymer of vinyl chloride resin and vinyl acetate resin 30~
To 60 parts by weight, 40 to 70 parts by weight of vinyl chloride resin that provides thixotropy through secondary agglomeration of microparticles, 40 to 80 parts by weight of vegetable oil or fatty acid surface-treated calcium carbonate, 1 to 5 parts by weight of finely divided silica, silane or titanate. system coupling agent 1-5 parts by weight, filler 100-20 parts
1. A highly permeable sealing material composition characterized by containing 0 parts by weight, 100 to 200 parts by weight of a plasticizer, and 7 to 22 parts by weight of a modified polyamide.