JPH0525419A - Undercoating material - Google Patents

Abstract

PURPOSE:To improve chipping resistance, rustproofness, and soundproofness by mixing an undercoating material based on a vinyl chloride resin with thermally expandable microcapsules. CONSTITUTION:45-65 pts.wt. vinyl chloride resin of a paste type or of a vinyl acetate copolymer type, 25-35 pts.wt. plasticizer, up to 10 pts.wt. filler. and 2-5 pts.wt. thermally expandable microcapsules having a capsule diameter of 20-30mum are mixed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is applied to the bottom surface of a car body, the inner surface of a wheel house, the lower part of the outer surface of a car body, etc. to improve chipping resistance, rust prevention, soundproofing and the like in these parts. It relates to an undercoat material used.

[0002]

2. Description of the Related Art An undercoat material is applied to the underside of a car body, the inside of a wheel house, the bottom of the outside of the car body to improve chipping resistance, rust resistance, and soundproofing in these parts. It is common to do.

Conventionally, as such an undercoat material, a material containing a vinyl chloride resin as a main component and optionally containing a plasticizer, a filler and the like has been used.

In this case, in order to obtain a large film thickness of 250 to 500 μm, the viscosity of the undercoat material needs to be about 40,000 CPS.

[0005]

However, in the case of such a viscosity of about 40,000 CPS, there is a large change in viscosity with temperature, and it is difficult to obtain a good coating state because the spray pattern is not constant. There was a point.

For example, as shown in FIG. 4, when the undercoat gun 11 is used to coat the floor back surface 12, when the viscosity of the undercoat material rises due to temperature change, an unblown portion A occurs, and conversely, When the viscosity of the undercoat material is lowered due to the temperature change, there is a problem that the spray pattern is not constant due to the temperature change such that the overspray portion B is generated as shown in FIG.

Therefore, when an attempt is made to reduce the viscosity of the undercoat material so as to reduce the change in viscosity due to temperature change, the undercoat material is applied to the floor back surface 12, so that the undercoat material drips as shown in FIG. The icicle-shaped portion C is formed, and when applied to such an extent that the icicle-shaped portion C cannot be formed, the required film thickness cannot be secured, and there is a problem that the chipping resistance and the like decrease. .

Therefore, there has been a demand for the development of an undercoat material which has a small change in viscosity with temperature, can make a coating pattern constant, and can secure a required film thickness.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has a small change in viscosity with temperature,
The coating pattern can be made constant, the required film thickness can be secured after baking, and chipping resistance, rust resistance, and sound insulation can be improved. The purpose is to provide an undercoat material.

[0010]

The present invention is characterized in that a vinyl chloride resin-based undercoat material contains heat-expandable microcapsules, and is related to such an undercoat material. The configuration of the invention is used as means for solving the above-mentioned conventional problems.

The undercoat material according to the present invention is based on vinyl chloride resin and contains vinyl chloride resin as a main component.

The vinyl chloride resin includes a paste type and a vinyl acetate copolymer type, and a combination of these may be used.

In this case, the mixing ratio of the vinyl chloride resin is
It is desirable that the amount is 45 to 65 parts by weight, and if it is less than 45 parts by weight, the deterioration of physical properties due to the addition of the heat-expandable macrocapsule cannot be compensated, and the physical properties such as the application of the undercoat material and the strength are reduced. Is not preferable because it tends to be inadequate, and when it exceeds 65 parts by weight, the viscosity tends to be too large and the dischargeability from an undercoat gun or the like tends to be deteriorated, which is not preferable.

Further, in addition to the vinyl chloride resin, a plasticizer may be included, and this plasticizer is useful for improving workability and physical properties during undercoating. .

In this case, the compounding ratio of the plasticizer is 25 to 35.
If it is less than 25 parts by weight, the dischargeability from the undercoat gun and the coating property tend to deteriorate, and if it is more than 35 parts by weight, the viscosity becomes low and the flow or dripping tends to occur. Become.

Further, a filler may be contained, but this filler may be added when it is necessary to prevent the physical properties of the undercoat material from being deteriorated by adding the heat-expandable microcapsules. it can.

However, if the amount of the filler added is too large, the supply property when supplying the undercoat material may be deteriorated, so the amount is preferably 10 parts by weight or less.

Furthermore, the undercoat material according to the present invention contains heat-expandable microcapsules.

The heat-expandable microcapsules have a desired film thickness from a thin film thickness by ensuring an expansion coefficient of 130% or more, more preferably 150% or more at the time of baking after applying the undercoat material. In order to obtain such an expansion coefficient, the compounding ratio is preferably 2 to 5 parts by weight.

That is, if it is less than 2% by weight, the desired expansion coefficient cannot be obtained, and if it exceeds 5 parts by weight, physical properties such as coating property and strength tend to be deteriorated.

As the heat-expandable microcapsules,
It is possible to use a resin in which a low boiling point solvent is wrapped with a thermoplastic resin such as vinylidene chloride or acrylonitrile, and a capsule-shaped resin having a particle size of about 20 to 30 μm can be used.

The heat-expandable microcapsules are undercoated with a plasticizer and the like, and then, for example, 1
Baking at 40 ° C. for 30 minutes causes thermal expansion by the vapor pressure of the low boiling point solvent, and as a result, a film thickness thicker than that before baking is formed.

[0023]

The undercoat material according to the present invention is
Since it is a vinyl chloride resin type, which contains vinyl chloride resin and necessary plasticizers, fillers, etc., and thermally expandable microcapsules, it is applied to the floor and other surfaces of the vehicle body before baking. In the state of, as shown in FIG.
The vinyl chloride resin 1 is present as particles in the plasticizer 2, and the thermally expandable microcapsules 3 are dispersed between the vinyl chloride resin 1.

Next, during baking, as shown in FIG. 2, the vinyl chloride resin 1 begins to gel, and the heat-expandable microcapsules 3 start to expand due to the vapor pressure of the low boiling point solvent inside the thermoplastic resin.

After the baking is completed, the undercoat material is completely gelled, as shown in FIG.
The thermally expandable microcapsule 3 can maintain the shape when thermally expanded.

Therefore, after the baking is completed, a sufficient film thickness is secured, and chipping resistance, rust prevention, soundproofing, etc. are improved.

As described above, the undercoat material according to the present invention contains the heat-expandable microcapsules, and the heat-expandable microcapsules are used to ensure the required film thickness before baking. Since it is not necessary to secure a relatively large film thickness (for example, about 250 to 500 μm as described above), the undercoat material may have a low viscosity, and the viscosity change due to temperature is small, and the viscosity can be reduced. As a result, the coating pattern becomes stable and a uniform film thickness can be obtained.
The required film thickness is ensured by thermal expansion during baking, and the density is lower than in the conventional case, which contributes to weight reduction.

[0028]

Example An undercoat material having the composition shown in Table 1 was applied to the underside of an automobile body by an undercoat gun.

[0029]

[Table 1]

Further, when the workability in coating with an undercoat gun was compared and the film thickness after coating was examined, the results are as shown in Table 2.

[0031]

[Table 2]

As shown in Table 2, in the case of the conventional example, the viscosity changes greatly with temperature, the spray pattern changes greatly, and the film thickness after application has a wide range. In the case of the invention example, the viscosity of the undercoat material is low, so the change in viscosity with temperature is considerably smaller than in the conventional case, and the change in the spray pattern is small, and the width of the film thickness is also the same as in the conventional example. It was quite small in comparison.

Next, baking was performed to evaluate the characteristics of the coating film portion, and the results shown in Table 3 were obtained.

[0034]

[Table 3]

The undercoat material used in the present invention has a low viscosity, a small change in viscosity with temperature, and a small film thickness after coating. Further, as shown in Table 3, after the baking is completed, It has been found that it is possible to obtain the required film thickness, and it is as excellent in chipping resistance and adhesiveness as those obtained by conventional careful coating. In addition, the weight of the coating film could be reduced.

[0036]

According to the present invention, since the vinyl chloride resin-based undercoat material contains the heat-expandable microcapsules, the coating thickness may be thinner than before before baking. It is possible to reduce the viscosity of the undercoat material, and the viscosity of the undercoat material is reduced, so that the viscosity change due to temperature is small, and it becomes possible to secure a stable coating pattern and a uniform film thickness. Since the film thickness before baking is thin, problems such as sagging are unlikely to occur, and after the baking is completed the required film thickness can be secured by thermal expansion of the thermally expandable microcapsules, so chipping resistance, rust prevention, It has excellent soundproofing properties, and in addition, it has an excellent effect that it can contribute to weight reduction due to a decrease in specific gravity of the coating film after baking. It is.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing a state after applying an undercoat material.

FIG. 2 is a schematic explanatory view showing a state during baking after applying the undercoat material.

FIG. 3 is a schematic explanatory view showing a state after applying an undercoat material and baking.

FIG. 4 is an explanatory diagram showing a conventional undercoat material in which an unblown portion is formed when the viscosity becomes high due to temperature change.

FIG. 5 is an explanatory diagram showing how an overspray portion occurs when a conventional undercoat material has a low viscosity due to a temperature change.

FIG. 6 is an explanatory diagram showing how an icicle-shaped portion is formed when the viscosity of the undercoat material is reduced to obtain a desired film thickness.

[Explanation of symbols]

 1 Vinyl chloride resin 2 Plasticizer 3 Thermally expandable microcapsules

Claims (1)

Claims: 1. A vinyl chloride resin-based undercoat material, which comprises thermally expandable microcapsules.