JPS6253544B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a highly permeable sealant composition, particularly a polyvinyl chloride resin sealant composition that has high permeability into narrow areas such as gaps between metal plate joints. Conventionally, as sealing materials for sealing joints such as spot welding of sheet metal parts of automobile bodies, there are polyvinyl chloride plastisol-based materials whose main component is paste-like polyvinyl chloride resin and other materials. Depending on the working conditions of the sealing process, those with a viscosity of 30,000 to 60,000 cps (20°C) are used, and depending on the application conditions, fluid or non-flowable materials are used. To seal the above-mentioned seams using such a sealant, apply it to the steel plate joint in a bead shape using a coating machine such as a sealing gun, and then use a brush or rubber spatula to fill the gaps between the joints. This is done by rubbing in the sealant and removing excess sealant at the same time, then spraying the paint and gelling or curing the paint film when it is baked in a baking oven. However, with such sealants,
As shown in Figure 1 of the attached drawings, the joint 3 between steel plates 1 and 2
The sealant 5 has poor permeability into the gap 4,
Since it is only attached to the surface of the steel plate joint 3, if the coating film becomes extremely thin when removing the excess sealant 5 with a spatula or the like, or if the application is done in a sloppy manner, the remaining sealant may be removed. Missing parts may occur. In such a case, water may leak from outside the vehicle body, or the steel plate may rust due to this. In order to prevent such water leakage, the sealing material must be sufficiently permeated into the gaps between the steel plate joints to sufficiently fill the gaps. To this end, it is necessary to create a sealing material with low viscosity and high leveling properties by incorporating a low filler, a high plasticizer, and a high leveling agent. However, if the viscosity of the sealant obtained by the above method is less than 15,000 cps (at 20°C),
Although the overlapping part of the steel plate joint shows a permeability of 8 mm or more, the fluidity is 50 mm at room temperature to 140 °C for 30 minutes.
~150mm, and the sealing material sag during work or the post-process painting process, making it difficult to put it to practical use. In addition, "fluidity" as used in this specification means that the sealant composition is applied to a steel plate coated with cationic or anionic electrodeposition in a semicylindrical shape with a height of 3 mm and a width of 10 mm. The distance that the sealant composition drips after being held at room temperature for 10 minutes and at 140°C for 30 minutes. In addition, "permeability" means that two steel plates coated with cationic or anionic electrodeposition are stacked together, a sealant composition is applied to the joint, and after being held horizontally and at a 90° angle for 10 minutes at room temperature, This refers to the distance that the sealant composition penetrates when two steel plates are separated after being held at 140°C for 30 minutes and cooled. As a result of intensive research aimed at solving the above-mentioned conventional problems, the present invention has developed a sealing material based on polyvinyl chloride resin that contains 20 to 30 parts by weight of polyvinyl chloride resin (parts by weight, hereinafter the same). ),
Mainly calcium carbonate made by mixing 25 to 35 parts of plasticizer, precipitated calcium carbonate with a particle size of 0.03 to 0.1μ, and weight calcium carbonate with a particle size of 0.5 to 2.0μ in a weight ratio of 1:1.5 to 4. 30 to 50 parts of filler,
and 0.05 to 3.0 parts of at least one selected from the group of dibenzylidene sorbitol, tribenzylidene sorbitol, and nuclear substituted products thereof, and is characterized by having a viscosity of 15,000 to 30,000 cps at 20°C and a fluidity of 10 mm or less. A highly permeable sealant composition is provided. The polyvinyl chloride resin used in the present invention may be one for ordinary plastisols, and vinyl chloride alone or with other copolymerizable monomers may be polymerized by emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, etc. The manufactured one may be adopted. Note that copolymers of vinyl chloride and other copolymerizable monomers are unstable in storage as plastisols and tend to increase in viscosity during storage, so vinyl chloride homopolymers are preferred. As the plasticizer in the present invention, for example, di(2
Phthalate esters such as ethylhexyl) phthalate, butylbenzyl phthalate, dinonyl phthalate, diheptyl phthalate, butyl phthalyl butyl glycol, dioctyl adipate,
Examples include aliphatic dibasic acid esters such as didecyl adipate and dioctyl sebacate, phosphoric acid esters such as tricresyl phosphate and trioctyl phosphate, other epoxy plasticizers, polyester plasticizers, etc., and at least one of these Use seeds. Since such plasticizers affect the fluidity properties of plastisol and the physical properties of the cured product after gelling, the amount used is usually selected at a ratio of 80 to 175 parts per 100 parts of the polyvinyl chloride resin that is the base material. However, a proportion of 100 to 150 parts is preferable, especially when used as a sealant according to the present invention. At the end of 100 parts, the tensile strength and elasticity increase, but the dischargeability decreases and workability worsens, and when it exceeds 150 parts,
Although the viscosity reduction improves the permeability into the gaps, it tends to cause sagging. The filler in the present invention is mainly composed of calcium carbonate, that is, calcium carbonate alone or together with other fillers (clay, talc, silica, etc.)
A combination of these may be used. By using such a filler, it is possible to adjust the flow characteristics and cured properties of the sealant, and to reduce the cost. The above-mentioned calcium carbonate includes precipitated calcium carbonate chemically produced from limestone, or surface-treated calcium carbonate with fatty acids or resin acids,
There is heavy calcium carbonate, which is made by mechanically crushing and classifying limestone, calcite, shells, etc. In particular, surface-treated precipitated calcium carbonate has good dispersion processability for plastisol, and it is usually used in combination with ground calcium carbonate. In this way, the combination of ultrafine (particle size 0.03 to 0.1 μ, preferably 0.08 to 0.1 μ) precipitated calcium carbonate and heavy calcium carbonate with particle size 0.5 to 2.0 μ is recommended before gelling the sealant. In terms of fluidity, it is easy to flow and has thixotropic fluidity, so it is preferable, and the ratio of the two is preferably precipitated calcium carbonate/ground calcium carbonate=1/1.5 to 4. Dibenzylidene sorbitol and tribenzylidene sorbitol in the present invention are produced by a condensation reaction of sorbitol and benzaldehyde, and these nuclear substituted products include alkyl groups (methyl, ethyl, propyl, isopropyl, butyl, isobutyl, octyl, etc.) and alkoxy groups (methoxy, ethoxy, propoxy, butoxy, etc.). At least one of these sorbitol compounds is usually heated and mixed with the plasticizer in advance and used in the form of a suspension. The highly permeable sealant composition according to the present invention includes:
20 to 30 parts of the above polyvinyl chloride resin, 25 to 35 parts of plasticizer
30 to 50 parts, preferably 28 to 33 parts, of a filler mainly composed of mixed calcium carbonate of precipitated calcium carbonate and ground calcium carbonate having the above-mentioned predetermined particle size and proportions.
part, preferably 35 to 45 parts, and 0.05 to 3.0 parts, preferably 0.1 to 1.0 parts of a sorbitol compound as essential components. In the above blending ratio of each component, if the plasticizer is less than 25 parts, the viscosity will be high and the permeability will be low, and if it exceeds 35 parts, the viscosity will be low and sagging will be large. If the amount of filler is less than 30 parts, the cost reduction effect cannot be measured, and if it exceeds 50 parts, the viscosity becomes high. If the amount of the sorbitol compound is less than 0.05 parts, the sealant will sag significantly, and if it exceeds 3.0 parts, it is not economical. In addition to the above-mentioned essential components, the composition of the present invention may appropriately contain conventional additives such as dehydrochlorination reaction inhibiting stabilizers (metallic soap, organic tin compounds, etc.), pigments (titanium white, etc.), adhesives, etc. As a preparation method, for example, first, a polyvinyl chloride resin and a filler are added to and mixed with a plasticizer while stirring, then a sorbitol compound and the above-mentioned additives are added as necessary, and the mixture is desorbed under reduced pressure. This may be carried out by foam mixing. The composition of the present invention thus obtained has a viscosity of 15,000 or less before gelation.
~30000cps (20℃) and fluidity is set below 10mm. The composition of the present invention having the above structure is used, for example, as illustrated in FIG. 2 of the accompanying drawings. That is, as shown in FIG. 2A, after discharging the composition of the present invention in the form of a bead at a joint (for example, a spot weld) 13 between metal plates 11 and 12 such as steel plates using a sealing gun (not shown), As shown in FIG. 2B, correction is performed using a brush, spatula, etc. (not shown), and then heat treatment is performed. The composition of the present invention is a metal plate 1
It efficiently penetrates into the gap 14 between 1 and 12 and completely seals the gap 14. Since the composition of the present invention has excellent properties as described above, it is used for sealing various parts, but in particular, it can be used for sealing in spot welding parts of automobile bodies.
For example, it is useful for a roof drip rail 15, a trunk opening 16, a rear combination lamp 17, a floor 18, etc. shown in FIG. 3 of the accompanying drawings. When used in such parts of an automobile body, it may be generally carried out in the following manner. That is, the white body is degreased with an alkali, then subjected to a chemical conversion treatment with an aqueous phosphate solution, etc., and then immersed in a cationic electrodeposition bath or an anionic electrodeposition bath to perform electrodeposition coating. After baking the car body after electrodeposition coating at, for example, 170°C for 30 minutes, the composition of the present invention is applied to the sealing area with a sealing gun, and after correction, it is baked at, for example, 120 to 170°C for 5 minutes.
Temporarily bake for ~20 minutes (preferably 15-20 minutes at 130-150°C), apply an intermediate coat by spraying if necessary, then bake at 140-160°C for 20-40 minutes, then spray again. After applying topcoat with etc.,
Bake at 140-160℃ for 20-40 minutes. In this way, the sealing of the sealing area is completed at the same time as painting the car body. Next, the present invention will be described in more detail with reference to Examples. Examples 1 to 3 and Comparative Examples 1 and 2 A sealant composition is prepared by mixing and dispersing the raw materials in the proportions (parts by weight) shown in Table 1 and defoaming them under reduced pressure.

[Table] The sealant composition obtained in this way
Tested in accordance with JIS K6830,
Obtained the results in the table. In addition, as shown in Fig. 3, a sealing gun is used to seal the sealing parts of the automobile body after cationic electrodeposition coating, such as the roof drip rail, trunk opening, rear combination lamp, floor, etc. The material composition was applied to the diameter gap in the form of a bead with a diameter of about 3 mm, a part of which was brushed, and then calcined at 140℃ for 10 minutes.
After keeping it at room temperature for 10 minutes, it was further baked at 140°C for 30 minutes to complete the sealing. The sagging and permeability during this operation were as shown in Table 2.

[Table] As is clear from Table 2, in Comparative Example 1, the viscosity
At 20,000 cps, the permeability is 3 to 4 mm, but the fluidity is
40mm, and even work on the car body causes sagging that causes an abnormal appearance. In comparative example 2, the viscosity
At 55,000 cps, the fluidity is 0 mm and no sagging occurs during car body work, but it does not penetrate. On the other hand, in the present invention of Examples 1 to 3, the viscosity was 15,000 to
Since it is in the range of 30,000 cps and contains a sorbitol compound, both fluidity and permeability are appropriate, and sufficient permeability can be obtained without impairing workability. Comparative Examples 3 and 4 Regarding the influence of changes in particle size of the precipitated calcium carbonate and ground calcium carbonate used, sealant compositions were prepared and tested according to the procedure of the previous example, and compared with Example 2. The raw material composition and test results are shown in Table 3.

[Table] As is clear from Table 3, Comparative Examples 3 and 4
The viscosity is 15,000 to 17,000 cps, and the osmotic pressure is 5 to 6.
mm, which is good, but the flowability is over 30 mm, causing sag that causes abnormalities in the appearance of the car body. As described above, the composition of the present invention contains 20 to 30 parts of polyvinyl chloride resin, 25 to 35 parts of a plasticizer, and a mixed calcium carbonate of precipitated calcium carbonate and ground calcium carbonate having the above-mentioned predetermined particle size and ratio. Mainly 30-50 parts of filler and sorbitol compound
Consists of 0.05 to 3.0 parts and has a viscosity of 15000 at 20℃
It is a highly permeable sealant composition with ~30,000cps and fluidity of 10mm or less, so it has appropriate permeability and fluidity, so when sealing the seam gap, the sealant composition It is possible to improve the permeability into the gap between the steel plate joints without deteriorating the workability of the product, and it is possible to prevent water leakage due to coating defects as in the past. Therefore, the above-mentioned sealant composition is extremely effective in cases where it is important to seal the seam gaps, such as automobile bodies, which have many spot welds.Especially, if sealing is performed after electrodeposition coating,
Since it can be hardened in the baking process of the subsequent intermediate coat and top coat, workability and economy are improved.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing a state in which a conventional sealant composition is applied to a steel plate joint, Figure 2A shows a state in which the composition of the present invention is applied with a sealing gun, and Figure 2B shows a modified state. Perspective view, and third
The figure is a schematic perspective view showing a portion of an automobile body where the sealant composition is to be used. 11, 12: steel plate, 13: joint, 14: gap.

Claims (1)

[Scope of Claims] 1. In a sealing material based on polyvinyl chloride resin, 20 to 30 parts by weight of polyvinyl chloride resin,
Calcium carbonate prepared by mixing 25 to 35 parts by weight of plasticizer, precipitated calcium carbonate with a particle size of 0.03 to 0.1μ, and heavy calcium carbonate with a particle size of 0.5 to 2.0μ in a weight ratio of 1:1.5 to 4. Filler based on 30~50
parts by weight, and at least one member selected from the group of dibenzylidene sorbitol, tribenzylidene sorbitol, and nuclear substituted products thereof 0.05 to 3.0
Consisting of parts by weight, viscosity at 20℃ is 15,000~
A highly permeable sealant composition characterized by a fluidity of 10 mm or less at 30,000 cps. 2. The composition according to item 1, wherein the substituent of the nuclear substituted product is one or more of an alkyl group and an alkoxy group.