JPH08209060A - Cold drying aqueous emulsion-based coating material - Google Patents

Abstract

PURPOSE: To obtain a cold drying type aqueous emulsion-based coating material, good in chipping resistance and damping properties, capable of forming a film having a low specific gravity and suitable as a coating material for undercoating such as repairing. CONSTITUTION: This cold drying type aqueous emulsion-based coating material is obtained by using a styrene-modified acrylic resin and an urethane resin in combination as resins to be a film component in the emulsion-based coating material prepared by dispersing resins to be the film component in water and blending resin balloons therein. A resin having a glass transition temperature different from a styrene-modified acrylic resin having 0-50 deg.C glass transition temperature and a polyurethane resin having -60 to -10 deg.C glass transition temperature by >=20 deg.C is used in this case.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a normally dry emulsion-type paint which is applied to automobile tire houses, under floors, front aprons and the like and which is excellent in chipping resistance and vibration damping.

[0002]

2. Description of the Related Art Conventionally, a paint for undercoat has been thickly applied to a tire house, an underfloor, a front apron, etc. of an automobile, and an undercoat applied to such a place. The coating material is generally heated at 110 ° C. for 8 to 1 through a calciner called a sealer furnace.
It is dried under the condition of 2 minutes. After that, apply an intermediate paint,
It is general that after drying, further applying a top coating, drying to complete the coating process, and then moving to a fitting process for mounting glass, interior materials, tires and the like.

However, undercoat coating must be performed again before the coating process is completed and before the outfitting process is completed, or after the outfitting process is completed, or when the vehicle is repaired. It may not be. For this reason, it is necessary to paint without affecting the assembled parts, so there is a need for a normal-dry type paint that can be dried at room temperature without using a drying oven or, if fast drying is required, with far infrared rays, etc. Has been done.

It is required for such a normally dry type undercoating paint to have particularly good vibration damping property, which prevents roads from freezing when it is exported to Northern Europe, North America and the like. This is because rock salt is sprinkled from the point of view and many pebbles are sprinkled, which is necessary as a countermeasure against stone bounce. Further, from the viewpoint of vehicle design cost, the damping material in the vehicle interior may be reduced, and it may be necessary to additionally apply an undercoat coating on an emergency basis or according to each user. This damping property depends on the environment in which the vehicle is used.
It is important to have sufficient characteristics at a temperature of about 0 to 40 ° C.

On the other hand, in recent years, from the viewpoint of environmental measures, it has been demanded that the paint for undercoat be converted from a vinyl chloride plastisol to an aqueous emulsion paint, and the same applies to the normal dry type.

However, since the aqueous emulsion paint does not contain a plasticizer, it tends to have a higher specific gravity than that of vinyl chloride plastisols, which is contrary to the demand for reduction of vehicle weight. is there. For this reason, it is also known to mix a resin balloon with an aqueous emulsion-based paint (JP-A-4-27537).
JP-A-5-170802), there is a problem that the chipping resistance decreases when a resin balloon is blended.

For this reason, there is a demand for an aqueous emulsion-based coating composition which is capable of forming a coating film having excellent chipping resistance and excellent vibration damping property even if a resin balloon is blended.

The present invention has been made in view of the above circumstances, and despite the fact that a resin balloon is blended, it has good chipping resistance and vibration damping properties, and a low specific gravity coating film can be dried at room temperature. An object is to provide a normally dry aqueous emulsion-based paint that can be formed.

[0009]

Means and Actions for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, in the water-based emulsion coating composition in which a resin as a coating film component is dispersed in water, As a result, it was found that the above object can be achieved by using a styrene-modified acrylic resin having a specific glass transition temperature in combination with a urethane resin.

That is, a styrene-modified acrylic resin having a glass transition temperature of 0 to 50 ° C. and a glass transition temperature of −60 to −1.
By using a resin having a different glass transition temperature of 20 ° C. or more in combination with a polyurethane resin of 0 ° C. as a coating film main component of a normally dry aqueous emulsion paint, excellent vibration damping properties can be given in a wide temperature range. It is possible to improve the adhesion and abrasion resistance of the styrene-modified acrylic resin by adding resin balloons, as compared with the case of adding other balloons such as glass balloons. The present invention has been completed by finding that a hard and tough coating film can be formed by compensating for the drawbacks that are weak in cold resistance and impact resistance, while reducing the amount.

Therefore, according to the present invention, in an aqueous emulsion paint in which a resin as a coating film component is dispersed in water and a resin balloon is blended, the resin as a coating film component has a glass transition temperature of 0. A styrene-modified acrylic resin having a glass transition temperature of -50 ° C and a polyurethane resin having a glass transition temperature of -60 ° C to -10 ° C are used in combination with resins having different glass transition temperatures of 20 ° C or more. I will provide a.

The present invention will be described in more detail below. The normally dry aqueous emulsion paint of the present invention uses a styrene-modified acrylic resin and a urethane resin in combination as the resin components as described above.

Here, as the styrene-modified acrylic resin, known ones can be used, but those having a glass transition temperature in the range of 0 to 50 ° C., specifically, Dainippon Ink and Chemicals, Inc. ) VOCOAT-5410 manufactured by the company
(Solid 51%) can be used. in this case,
The styrene-modified acrylic resin has a molecular weight of 4 × 10 ⁵ to 4
Those in the range of × 10 ⁶ are preferable.

The styrene-modified acrylic resin is
In order to reduce the amount of water to be evaporated, it is preferable to disperse it in water so that the solid content is as high as possible.

The urethane resin has a glass transition temperature of −60 to −10 ° C., and the glass transition temperature of the styrene-modified acrylic resin used (one of them when two or more styrene-modified acrylic resins are used) and 20 ° C. Those having different glass transition temperatures are used. Glass transition temperature is 0
A styrene-modified acrylic resin having a glass transition temperature of -50 ° C and a polyurethane resin having a glass transition temperature of -60 ° C to -10 ° C have different glass transition temperatures of 20 ° C or higher, preferably 20-40 ° C. In the temperature range of -40 ° C, it is possible to obtain a coating film having a good damping property with a loss coefficient of 0.1 or more.

The proportion of the urethane resin used in combination is preferably 20 to 200 parts, particularly 30 to 150 parts, relative to 100 parts of the styrene-modified acrylic resin (parts by weight, the same applies hereinafter). If the amount is less than 20 parts, chipping resistance, abrasion resistance, adhesion, etc. may be insufficient.

A resin balloon is incorporated as an essential component in the normally dry aqueous emulsion paint of the present invention. This resin balloon generally has low heat resistance and has a drawback that foaming during baking is likely to occur due to moisture absorption of the resin balloon itself. Therefore, it cannot be used in a baking paint, but it is a normal dry type according to the present invention. The present inventor has found that such a problem does not occur in the coating composition (2), the resin balloon can be preferably used, and the above-mentioned effects are provided.

As the resin balloon, a resin balloon such as vinylidene chloride resin or acrylonitrile resin can be used, and the particle diameter of the resin balloon is
The range of 40 to 70 μm is preferable, and the specific gravity is 0.02 to 0.0.
A range of 5 is good.

The compounding amount of the resin balloon is 100
0.1 to 15 parts, preferably 0.02 to 10 parts
Good range of parts. If the blending amount is more than 15 parts, the strength of the coating film may decrease, while if it is less than 0.1 part, the effect of lowering the specific gravity may not occur.

In the present invention, in addition to the above resin balloons, glass balloons, silica balloons, shirasu balloons and the like may be used within a range that does not impair the effects of the present invention.

In addition to the above components, a heat-sensitive gelling agent and a surface conditioner may be used in combination with the emulsion coating composition of the present invention.

That is, when the emulsion-based paint containing the heat-sensitive gelling agent is applied, the resin starts to gel rapidly when the temperature exceeds the cloud point of the heat-sensitive gelling agent due to heating when the coating is dried and baked. The resin particles are fused to each other, and water between the particles is discharged to complete the film formation in a short time. The water discharged on the surface due to film formation evaporates quickly, so that the drying speed is very fast.The formulation of such a heat-sensitive gelling agent is effective when performing drying by far infrared rays in addition to room temperature drying. Therefore, heat from far-infrared rays is applied, water evaporation from the inside of the coating film in the film forming process is promoted, and long-term complete water removal during normal drying can be accelerated to obtain excellent film physical properties.

From this point of view, the heat-sensitive gelling agent in the normal dry type has a cloud point of 40 to 90 ° C., preferably 60 to 9
The temperature is preferably about 0 ° C., and specifically, there are an organic type and an inorganic type.

Examples of organic heat-sensitive gelling agents include starch and its derivatives, alkylene oxide adducts of nonionic activator organopolysiloxanes, alkylphenol-formalin condensates of organopolysiloxanes, and alkyleneoxide adducts of alkylphenol-formalin condensates. Examples thereof include polyvinyl methyl ether and organopolysiloxane polyether copolymer, and these can be used alone or in combination of two or more.

On the other hand, as the inorganic heat-sensitive gelling agent, for example, sodium hexametaphosphate, ammonium nitrate, ammonium chloride, sodium carbonate, potassium carbonate, sodium sulfate, potassium chloride, calcium chloride, calcium sulfate,
Magnesium sulfate, zinc ammonium complex salt, sodium nitrate, lead nitrate, sodium acetate and the like can be mentioned, and one of these can be used alone or two or more can be used in combination.
Among these, sodium hexametaphosphate has a mild ability to destabilize the charge of the emulsion as compared with other inorganic heat-sensitive gelling agents, so it is easy to handle, and if it remains in the film after drying and curing, Since the deterioration of water resistance is less than that of metal salts, it can be mentioned as a preferable example.

The heat-sensitive gelling agent may be a combination of the above-mentioned organic and inorganic types, and the blending amount thereof is the resin 10 as the coating film component.
The range of 0.2 to 4 parts, preferably 0.4 to 2 parts relative to 0 part is preferable. If the amount is less than 0.2 parts, the heat-sensitive gelling effect may not be obtained, and if it is more than 4 parts, the viscosity may be remarkably increased or the storage stability may be deteriorated.

A surface conditioner may be added to the emulsion paint of the present invention. This surface conditioner
It controls the evaporation of water in the paint when forming a thick film.In the initial evaporation stage, the water evaporates without being affected by the surface conditioner, but in the evaporation process when a skin is formed on the surface of the coating film The conditioning agent remains in the epidermis part, and because this surface conditioning agent is hydrophilic, it takes in water inside the epidermis, delays the skin formation speed by keeping the water wetting phenomenon for a long time, and it is possible to accelerate the evaporation of water, It can prevent the generation of cracks and swelling, and can quickly volatilize water in combination with the heat-sensitive gelling agent.

As the surface conditioner, ethylene glycol or propylene glycol is preferable, and other glycols, that is, glycols having a carbon number of 4 or more, such as triethylene glycol, are used for the coating film obtained even after 7 days after coating. Poor chipping. This is probably because the degree of evaporation of water was low, the moisture content was high even after 7 days, and the film formation was insufficient.

The content of the surface conditioner is preferably 2 to 25 parts, more preferably 7 to 20 parts, relative to 100 parts of the resin as the coating film component. If the amount is less than 2 parts, the effect of the surface conditioner is difficult to obtain, and if it is more than 25 parts, it may remain inside the coating film after drying, resulting in deterioration of the physical properties of the coating film and deterioration of water resistance.

The addition of a low boiling point hydrophilic solvent such as ethyl alcohol or isopropyl alcohol is also effective for water vaporization in the initial short period of time, and these are added in an amount of 0 to 100 parts by weight of the resin as a coating film component. It may be added in an amount of 30 parts, preferably 7 to 15 parts. However, these solvents are
Since it is released to the atmosphere in the drying process, it is desirable not to mix it from the environmental point of view, or to mix it in a small amount.

In addition to the above components, a filler other than resin balloons, a defoaming agent, a thickener, a dispersant, a wetting agent and the like may be added to the normally dry aqueous emulsion coating composition of the present invention, if necessary. it can.

As the filler, for example, calcium carbonate,
Talc, clay, silica, diatomaceous earth, zeolite, magnesium carbonate, mica and the like can be mentioned, and one of these can be used alone or in combination of two or more.
In the baking type coating, if the shape of the particles of the filler is flat, it tends to hinder the evaporation of water, so it is preferable that the shape of the particles is not flat. Flat type can also be used, and flat type talc, clay, mica, etc. are also effective from the viewpoint of performance. These 1 type can be used individually or in combination of 2 or more types. The average particle size of the filler is preferably 1 to 20 μm.

The amount of the filler compounded is preferably 50 to 300 parts, more preferably 150 to 250 parts, per 100 parts of the resin component. If the blending amount is less than 50 parts, appropriate thixotropy may not be obtained even in combination with a thickener, and swelling may occur easily. On the other hand, 300
If it exceeds the part, it becomes difficult for the resin to sufficiently wet the filler, and it becomes impossible to satisfy the coating film performance due to performance deterioration,
Cracks may easily occur.

The defoaming agent is added for the purpose of reducing the generation of bubbles and facilitating the elimination of bubbles once the emulsion or emulsion mixture having a low viscosity is liable to be generated by stirring. For example, San Nopco PCO8034 manufactured by Co., Ltd. is used.

The thickening agent is for helping the dispersion of the filler to prevent sedimentation, improving the stability of the coating material, finishing the viscosity adjustment to an appropriate level, and obtaining a balance of both sprayability and thixotropy. For example, methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, protein, polyvinyl alcohol, sodium polyacrylate, etc. can be used alone or in combination of two or more at a usual dose.

The dispersant is for helping the filler to be dispersed in water, and various kinds of sodium polyphosphates, surfactants and the like can be exemplified, and they can be used in a usual dose.

The aqueous emulsion paint of the present invention can be prepared by mixing the above components. For example, after resin component (latex), filler, dispersant, wetting agent, surface conditioner, and the like are kneaded, a thickener is added to disperse, and then a defoaming agent is added to defoam.
Finally, filtration can be performed to prepare the normally dry aqueous emulsion-based coating material of the present invention. In this case, the heat-sensitive gelling agent is
If the temperature during mixing rises, the reaction is likely to occur, so add it at the end as much as possible, and adjust the temperature of the mixture before addition to 4
It is desirable to cool it to 0 ° C or lower. As the disperser, a high speed disperser is suitable, and since the kneading and the viscosity adjustment afterward can be performed at the same time, the production efficiency can be made higher than that of other machines.

The normally dry aqueous emulsion coating composition of the present invention can be used as an undercoat coating composition for automobile tire houses, under floors, front aprons and the like.

In this case, a general high-pressure pump can be used for coating by a spray gun coating method or the like, and the coating amount is 150 to 40 in terms of the thickness of the coating material after drying.
It can be about 100 μm.

The drying can be carried out at room temperature, but in some cases, it may be heated up to about 60 ° C., or if necessary, it may be dried by far infrared rays or the like. In this case, 120 ° C. or less. It is desirable to dry at 110 ° C. or lower. The drying time at room temperature is usually 5 minutes to 15 minutes.

[0041]

INDUSTRIAL APPLICABILITY The normally dry aqueous emulsion coating composition of the present invention has good chipping resistance and vibration damping properties, can form a coating film having a low specific gravity, and is suitable as a coating material for an undercoat for repairing. is there.

[0042]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In addition, in the following examples, the compounding amounts are parts by weight.

[Examples and Comparative Examples] The components shown in Table 1 were mixed in the compounding amounts shown in the table, the dry coating film specific gravity was measured, and the loss coefficient was measured by the following method to evaluate the vibration damping performance. At the same time, chipping resistance and cold resistance were also measured. The results are also shown in Table 1. <Loss factor> Apply the sample to a 0.8 mm steel plate,
This was dried at room temperature for 168 hours to prepare a coating thickness of 2 mm. This sample is fixed at one end by a frequency of 200H
It was measured at z and a temperature of 20 ° C. <Chipping resistance> A sample was applied on a steel plate coated with electrodeposition so that the film thickness after drying was 500 μm, and dried at room temperature for 7 days. The above sample was set at an angle of 60 ° from the horizontal with the coated surface facing upward, and the lower end of a vinyl chloride pipe with an inner diameter of 20 mm and a length of 2 m standing vertically was applied to this coated surface, and the upper end of this pipe The M-4 nut defined by JIS was dropped through the above, and the total weight of the nut until the base material was exposed was measured. <Cold resistance> A sample was coated on an ED plate having a thickness of 0.8 mm, dried at room temperature for 168 hours, and the sample adjusted to have a coating thickness of 500 μm was subjected to a DuPont impact tester under the condition of −20 ° C. The presence or absence of cracks and peeling was confirmed and evaluated according to the following criteria. ×: Cracks occurred △: Peeling and floating occurred ○: No abnormality

[0044]

[Table 1]

From the results shown in Table 1, when the resin balloon was not compounded (Comparative Example 1), the coating film specific gravity was high, and when the glass balloon was compounded (Comparative Example 14), the cold resistance was poor. When a styrene-modified acrylic resin or a polyurethane resin is blended alone (Comparative Examples 2 to 7), the glass transition temperature of the styrene-modified acrylic resin or the polyurethane resin is the same as that of the present invention even when the styrene-modified acrylic resin and the polyurethane resin are used in combination. If it is out of the specified range, chipping resistance, cold resistance, loss factor, or cost is not satisfactory.

On the other hand, the emulsion coating composition of the present invention has sufficient chipping resistance and good cold resistance,
The vibration damping property is also good, and it is recognized that the vibration damping property is good in a wide temperature range.

Claims (1)

[Claims] 1. An aqueous emulsion coating composition comprising a resin as a coating film component dispersed in water and containing a resin balloon, wherein the resin as the coating film component has a glass transition temperature of 0 to 50 ° C. A normally dry water-based emulsion-based coating material comprising a styrene-modified acrylic resin and a polyurethane resin having a glass transition temperature of −60 to −10 ° C., which have different glass transition temperatures of 20 ° C. or more.