JPH0533270B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a highly permeable sealant composition, particularly to a polyvinyl chloride resin sealant composition that has high permeability into narrow areas such as gaps between metal plate joints. Conventional technology and problems to be solved Conventionally, sealing materials for sealing joints of sheet metal parts of automobile bodies, such as spot welding, have been made using polyvinyl chloride plastisol-based sealants whose main component is paste-like polyvinyl chloride resin. Depending on the working conditions of the sealing process, those with a temperature of 300 to 600 poise (20°C) are used, and those with no fluidity are used depending on the application conditions. In order to seal the seams with good watertightness and airtightness using such a sealant, use a coating machine such as a sealing gun to apply it to the steel plate joints in a bead shape, and apply it to the steel plate joints sufficiently to fill the gaps between the joints. This is done by rubbing the sealant with a brush or rubber spatula, etc. to fill the sealant, and removing excess sealant at the same time, then spraying the paint, and gelling or curing the paint when baking it in a baking oven. However, as shown in FIG. 1 of the attached drawings, the sealant 5 has poor permeability into the gap 4 of the joint 3 between the steel plates 1 and 2, and only adheres to the surface of the joint 3 of the steel plates. Because there is no
When removing excess sealant 5 with a spatula or the like, the coating film may become extremely thin, or if the coating is applied in a sloppy manner, there may be defects where no sealant remains. 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 allowed to sufficiently penetrate into the gaps between the steel plate joints and 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 material. However, if the viscosity of the sealant obtained by the above method is less than 150 poise (at 20°C), it will have a permeability of 8 mm or more in the overlapping part of the steel plate joint, but the fluidity will be 50 to 150 mm at room temperature to 140°C for 30 minutes.
As a result, "sagging" of the sealant occurs during work or during the post-process painting process, making it difficult to put it into practical use. In addition, "fluidity" as used in this specification means that 1.5 cc is applied in a hemispherical shape from a nozzle tip (1.0 mmφ) 10 mm apart from a vertically erected steel plate that has been subjected to cationic or anionic electrodeposition coating. At room temperature
This refers to the distance that the sealant composition flows down from the original application position after being left at 140°C for 10 minutes and 30 minutes. In addition, "permeability" means that two steel plates coated with cationic or anionic electrodeposition are stacked with a gap of 0.2 mm, and a sealant composition is applied to the joint, horizontally and at a 90° angle, at room temperature. After holding at 140°C for 10 minutes, holding at 140°C for 30 minutes, and after cooling,
This refers to the distance that the sealant composition penetrates when a steel plate is peeled off. Therefore, the present inventors developed a polyvinyl chloride resin-based plastisol sealant composition that has fluidity with little dripping and has high permeability into narrow areas such as gaps between metal plate joints. We have developed a fluid sealant composition with low viscosity, good permeability, and little sagging, and a patent application is currently pending.
No. 53544). In order to develop a sealant composition with even higher permeability and less dripping, we conducted extensive studies considering the conditions of use and working conditions in actual automobile body assembly lines, and found the following flow characteristics. It was found that it would be better to develop a sealant composition that has the following properties. Such flow characteristics mean that when a high shear force is applied to the sealant composition, when the so-called sealant is applied from a pressure pump, the apparent viscosity decreases, and at this time, the sealant composition is allowed to penetrate into the narrow part of the joint, and the sealant is applied. When the material is allowed to stand still, it recovers to its original viscosity in a short period of time, increasing its apparent viscosity and reducing dripping. That is, they discovered that desired permeability and fluidity could be obtained by lowering the yield value of the sealant composition and slowing down the recovery rate of apparent viscosity after removing a high shear load, and completed the present invention. I came to the conclusion. Structure and Effects of the Invention That is, the present invention provides a sealing material containing polyvinyl chloride resin as a component, which contains 20 to 30 parts by weight of polyvinyl chloride resin and 30 to 40 parts by weight of plasticizer.
30 to 40 parts of calcium carbonate as a filler, the filler has a particle size of 1 to 10 μm, unsurface-treated ground calcium carbonate, and a particle size of 0.04 to 0.20 μm.
Provided is a highly permeable sealant composition consisting of surface-treated calcium carbonate, in which the mixing ratio of heavy calcium carbonate and surface-treated calcium carbonate is 2:8 to 8:2, and having a viscosity and yield value within a certain range. The purpose is to In the present invention, "viscosity" refers to the composition at 20°C.
After adjusting to
Rotatinal Viscometer)
Refers to rotational viscosity when measured at 20 rpm. In addition, "yield value" is the value calculated using the following formula from the viscosity at high shear speed (rotation speed 20 rpm) and low shear speed (rotation speed 2 rpm) using a B-type rotational viscometer as above. Yield value. Y=μ _L R _L (μ _H R _H − μ _L R _L ) R _L /R _H − R _L [In the formula, Y is the yield value (dyne/cm ² ), R _H is the high rotational speed (rpm), R _L means low rotational speed (rpm), μ _H means rotational viscosity (poise) at high rotational speed, μ _L means rotational viscosity (poise) at low rotational speed] (Published by Zeon Corporation) Paste Processing'', page 90) 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, Those manufactured by solution polymerization or the like may be used. As the plasticizer in the present invention, for example, di(2
- Phthalate esters such as ethylhexyl) phthalate, butylbenzyl phthalate, dinonyl phthalate, diheptyl phthalate, and butyl phthalyl butyl glycol, aliphatic dibasic acid esters such as dioctyl adipate, didecyl adipate, and dioctyl sebacate, phosphoric acid Examples include phosphate esters such as tricresyl and trioctyl phosphate, epoxy plasticizers, polyester plasticizers, etc., and at least one of these is used. Since such plasticizers affect the fluidity properties of plastisol and the physical properties of the cured product after gelling, the amount used may be selected at a ratio of 8 to 200 parts per 100 parts of polyvinyl chloride resin. ,
Especially when it comes to sealing material applications according to the present invention.
A proportion of 120-170 parts is desirable. If it is less than 120 parts, physical properties such as tensile strength and elasticity will increase, but the viscosity will tend to increase, and if it exceeds 170 parts, the viscosity will decrease and the permeability to gaps will improve, but dripping will tend to occur. be. The unsurface-treated heavy calcium carbonate used in the present invention is mechanically crushed limestone, calcite, shells, etc., or chemically produced from limestone as a raw material, and has an average particle size of 1 to 1.
It is classified to fall within the 10 μm range.
For example, specifically, Takehara Chemical Industry Co., Ltd. (Sunlight)
100, Sunlight 700, Sunlight 1500, etc.), and Shiraishi Kogyo Co., Ltd. (Whiten B, Whiten SB, Softon 2200, etc.). The surface-treated calcium carbonate according to the present invention is chemically produced using limestone as a raw material, and then surface-treated with fatty acids (stearic acid, maleic acid, oleic acid, etc.) or resin acids (abietic acid, palustric acid, isobieric acid, etc.). , the average particle size is 0.04
~0.20μm range. Specifically, Takehara Chemical Industry Co., Ltd. (Neolite S, Neolite SP, Neolite SA-100, etc.), Shiraishi Kogyo Co., Ltd. (Hakuenka
CC, Shiroenka CCR, Shiroenka DD, Homocal D, etc.)
Commercially available products such as In particular, calcium carbonate surface-treated with fatty acids is desirable because it tends to increase the rate of apparent viscosity recovery after removal of high shear loads. Further, the mixing ratio of the above-mentioned heavy calcium carbonate and surface-treated calcium carbonate is in the range of 2:8 to 8:2. Preferably, the ratio is 3:7 to 5:5. If the ratio of heavy calcium carbonate increases to 8:2 or more, the yield value will decrease and fluidity with excellent permeability will be obtained, but the fluidity will tend to drip.
This poses a difficulty in putting the present invention into practical use. On the other hand, if the ratio of surface-treated calcium carbonate increases to 2:8 or more, the yield value increases and fluidity without dripping is obtained, but the apparent viscosity recovery speed becomes faster, so the desired permeability cannot be obtained. do not have. In the present invention, an appropriate amount of polybutadiene or polybutadiene copolymer can be blended if necessary. These are viscous liquid polymers obtained by polymerizing butadiene or a monomer copolymerizable with it. In particular, those having a functional group such as a hydroxyl group or a carboxyl group at the molecular end of the above-mentioned polymer, or those having an acrylic-terminated, epoxy-modified, maleated-terminated, hydrogenated type, or half-ester-terminated polymer are also used. be able to. for example,
Specifically, "NISSO-PB" commercially available from Nippon Soda Co., Ltd. can be mentioned. The polybutadiene polymer or copolymer is preferably added in an amount of 0.2 to 2 parts per 100 parts of the sealant composition of the present invention. In the composition of the present invention, the polybutadiene polymer or copolymer can lower the yield value and slow down the recovery rate of apparent viscosity after removal of high shear loads, thereby providing greater interstitial permeability. can be improved. As described above, the highly permeable sealant composition according to the present invention contains 20 to 30 parts of polyvinyl chloride resin, 30 to 40 parts of plasticizer, and 30 to 40 parts of calcium carbonate as a filler.
The filler is composed of a mixture of ground calcium carbonate with a particle size of 1 to 10 μm and surface-treated calcium carbonate with a particle size of 0.04 to 0.20 μm, and the mixing ratio of the ground calcium carbonate and surface-treated calcium carbonate is is in the range of 2:8 to 8:2 as an essential component. At the above blending ratio of each component,
If the amount of plasticizer is less than 30 parts, the viscosity will be high and the permeability will be insufficient even if the yield value is lowered, and if it exceeds 40 parts, the viscosity will be low and even if the yield value is increased, the fluidity will be large and sag. becomes. If the amount of calcium carbonate as a filler is less than 30 parts, it becomes uneconomical, and if it exceeds 40 parts, the balance between viscosity and yield value and the desired recovery rate cannot be obtained. Furthermore, in the above mixing ratio of calcium carbonate, if the amount of heavy calcium carbonate increases, the viscosity will be lower than 250 poise, and the yield value will also be 1500 dyne/cm ² or less. As the amount of surface-treated calcium carbonate increases, the yield value becomes higher than 3500 dyne/cm ² , and the recovery rate of the apparent viscosity of the composition after removing the shear force load tends to become faster. The addition of a polybutadiene polymer or copolymer to the composition also has the effect of providing drip-free flow, lowering the yield value and slowing the recovery rate of apparent viscosity after removal of high shear loads. be. In addition to the above-mentioned components, the composition of the present invention may contain conventional additives, such as dehydrochlorination reaction inhibiting stabilizers (metal soaps, organic tin compounds, etc.), pigments (titanium oxide,
(carbon, etc.), adhesives (blocking isocyanates, polyamides, epoxy resins, etc.), fillers other than those listed above (clay, talc, silica, etc.), viscosity modifiers such as dibenzylidene sorbitol, tribenzylidene sorbitol, etc., as appropriate. Good too. The method for producing the composition of the present invention includes, for example, adding and mixing a polyvinyl chloride resin and a filler while stirring a plasticizer, and optionally one or more selected from polybutadiene polymers or copolymers. The above-mentioned additives are further blended as necessary, and the mixture is degassed and mixed under reduced pressure. The composition of the present invention thus obtained has a viscosity of 250 to 400 poise (20°C), a yield value of 1500 to 3500 dyne/cm ² and a fluidity of 50 mm before gelation.
It is set below. 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 onto the joint (for example, spot welding location) 13 between metal plates 11 and 12 such as steel plates using a sealing gun (not shown), Figure 2B
This is corrected using a brush, spatula, etc. (not shown), and then heat treatment is performed. The composition of the present invention efficiently penetrates into the gap 14 between the metal plates 11 and 12,
Complete sealing of the gap 14 is achieved. Since the composition of the present invention has excellent properties, it is used for sealing various parts, but in particular, it is used for sealing in spots 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 using a phosphate aqueous 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 using a sealing gun.
Prebaking for 20 minutes (preferably 15 to 20 minutes at 130 to 150℃), and if necessary, apply an intermediate coat using a spray method, then baking at 140 to 160℃ for 20 to 40 minutes, and further spraying, etc. After applying the top coat with
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. In particular, when the composition of the present invention is applied to seal gaps between metal plate joints in automobile bodies, etc., the composition itself penetrates into the narrow parts of the joints, so correction and cleaning after application are almost unnecessary. It is also possible to cope with automation by robots, and if necessary, it is desirable to adopt automation systems such as robots. Next, the present invention will be specifically explained with reference to Examples. Examples 1 to 4 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] Polyvinyl chloride: Zeon 121 manufactured by Nippon Zeon Co., Ltd. Heavy calcium carbonate: Whiten B manufactured by Shiraishi Kogyo Co., Ltd. Surface-treated calcium carbonate: Shiroenka CCR manufactured by Shiraishi Kogyo Co., Ltd. Polybutadiene: Manufactured by Nippon Soda Co., Ltd. NISSO-PB
B-1000 The sealant composition thus obtained was tested and the results shown in Table 2 were obtained.

[Table] The rotational viscosity is the value measured using a B-type rotational viscometer with No. 7 rotor at 20 rpm, and the yield value is calculated from the rotational viscosity at 20 rpm and 2 rpm with No. 7 rotor. . Penetration was determined by removing the panel after baking and measuring the depth of penetration from the seal. The dripping distance is the distance measured from the original application position to the dripping position after baking. 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 gap in the form of a bead with a diameter of about 3 mm, baked at 140°C for 10 minutes, left at room temperature for 10 minutes, and then heated again at 140°C.
Sealing was completed by baking at ℃ for 30 minutes. The sagging and permeability during this operation were as shown in Table 2. As is clear from Table 2, in Comparative Example 1, the rotational viscosity is 280 poise, but the yield value is 1400 dyne/
cm ² , the permeability is 4 to 4.5 mm, and the dripping distance is 70 to 80 mm, causing fluidity that causes abnormalities in work on the car body. In Comparative Example 2, the viscosity is 400 poise, but the yield value is 3800 dyne/ ^cm2 ,
There is almost no fluidity that causes dripping, but the permeability is 0 to 1 mm, which is almost no penetration. On the other hand, the compositions of the present invention of Examples 1 to 4 have good permeability and less dripping.

[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... Seam, 14... Gap.

Claims (1)

[Scope of Claims] 1. A sealing material containing polyvinyl chloride resin as a component: 20 to 30 parts by weight of polyvinyl chloride resin, 30 to 30 parts by weight of plasticizer.
40 parts by weight, 30 to 40 parts by weight of calcium carbonate as a filler, and the filler has a particle size of 1 to 10 μm, unsurface-treated heavy calcium carbonate, and a particle size of 1 to 10 μm.
A highly permeable sealant composition comprising surface-treated calcium carbonate having a thickness of 0.04 to 0.20 μm, and characterized in that the mixing ratio of heavy calcium carbonate and surface-treated calcium carbonate is 2:8 to 8:2. 2 The viscosity of the composition at 20°C is in the range of 250 to 400 poise, and the yield value is in the range of 1500 to 400 poise.
3500 dyne/cm ² . The composition according to item 1 above. 3. The composition according to item 1 above, comprising polybutadiene or a polybutadiene copolymer.