JPH06198245A - Coating film-drying method - Google Patents

Abstract

PURPOSE:To provide a highly efficient coating film-drying method by which the surfacial property of the film is made excellent without altering the production processes even in the case a vibration damping coating material is used by drying the film at first at the temperature lower than 100 deg.C until the evaporation ratio of volatile substances becomes the specified weight percentage or higher and then drying at 100 deg.C or higher. CONSTITUTION:Regarding a drying method of a coating film consisting of an aqueous emulsion-type or aqueous dispersion-type coating composition, at first the film is dried at the temperature lower than 100 deg.C until the evaporation ratio of volatile substances becomes 60wt.% or higher and then it is dried at 100 deg.C or higher. The volatile substances are substances which are evaporated at about 105 deg.C for 3 hours and contain mainly water and an alcohol such as ethylene glycol, etc., In the second drying stage after the first drying stage, drying is carried out in air at about 100 deg.C at the same blowing speed as that in the first stage and almost all the remaining volatile substances are evaporated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating film drying method for forming a good coating film which does not cause blistering.
The present invention relates to a coating film drying method capable of forming a coating film with anti-vibration coating applied to automobiles, washing machines, refrigerators, etc., without generating blisters and with high production efficiency.

[0002]

2. Description of the Related Art Conventionally, in automobiles, washing machines, refrigerators and the like, antivibration measures have been taken in order to minimize the propagation of vibrations during operation to passengers and the surroundings. As one of the countermeasures, a bituminous substance such as asphalt mixed with a filler such as calcium carbonate or asbestos is installed on a floor surface as a sheet having a thickness of about 2 to 5 mm.
Thermal fusion is performed. However, since the floor surface usually has a complicated shape, it is difficult to cover the entire surface, and in addition, a partial adhesion failure occurs at a part that is not heat-sealed, and sufficient vibration isolation cannot be obtained. Have

As another anti-vibration measure that does not have such difficulties, application of anti-vibration coating to the floor surface has been performed. If the coating process is briefly explained by taking an automobile production process as an example, first, a steel plate that is a constituent material of floors and walls is subjected to electrodeposition coating called priming for the purpose of preventing rust. . Next, the anti-vibration coating material is applied in a thick film, and the first drying step is started. After that, intermediate coating and top coating are performed, and the second drying step is performed and then the assembly step is performed.

By the way, the anti-vibration coating in the automobile interior has sufficient fluidity at the time of coating so as to improve the production efficiency by automating the coating process, and does not sag even after a thick coating of about 5 mm. There is something good that needs to be done. In addition, it is necessary to have good adhesion to a substrate such as a steel plate under a strong vibration or impact, be lightweight, and have a vibration damping property equal to or higher than that of the above-mentioned sheet-like material.

In order to meet such demands, a vibration-proof coating material having a characteristic filler (for example, JP-A-55-5826).
No. 2, etc.), and the adhesion, workability,
Anti-vibration paint with excellent anti-vibration properties that can be applied in thick film (JP-A-62-
No. 227966, Japanese Patent Application No. 4-170157, etc.) have been proposed.

[0006]

However, when such a coating material is applied to the conventional production process for automobiles mentioned above, there are concerns about the following problems. For example, when using a water-based emulsion type anti-vibration coating material capable of thick film coating, drying at a temperature of less than 100 ° C. is required to improve the surface finish, but under such low temperature drying conditions,
The drying time requires a long time of about 1 day to 1 week, which lowers the production efficiency. On the other hand, in order to shorten the drying time,
Drying at 100 ° C. or higher is conceivable, but under such high temperature drying conditions, surface blister occurs in the coating film and it cannot be a product.

The present invention solves the above-mentioned concerns and changes the production process of conventional automobiles, washing machines, refrigerators, etc. even when the previously proposed anti-vibration coating is used. An object of the present invention is to propose a method for drying a coating film which has good surface properties and is highly productive, which can be carried out without any treatment.

[0008]

Means for Solving the Problems As a result of studies to achieve the above object, the inventors of the present invention have found that (1) a coating film applied to a thick film is dried in advance at a relatively low temperature to obtain a constant amount. If the volatile substances are evaporated, subsequent drying does not cause blistering on the surface of the coating film even at high temperature, and a good coating film can be obtained. (2) When drying in advance The temperature is about 1
When the temperature is lower than 00 ° C and higher than about 50 ° C, about 60% by weight or more of the volatile substance evaporates in a relatively short time (several tens of minutes to about 1 hour), but most of the remaining volatile substance remains at this temperature. It takes a long time of several days to a week to evaporate without evaporation. (3) However, if the volatile substance evaporates by about 60 wt% or more, the subsequent drying is performed at a considerably high temperature (about 120%). Even when the temperature is set to 180 ° C.), the present invention has been completed based on the finding that the thick film surface does not swell and can be performed at a high temperature in a short time.

That is, the present invention provides a coating film comprising [1] a water-based emulsion type or a water-based dispersion type coating composition, or [2] at least one selected from the group consisting of asphalt, rubber and synthetic resin. The hydraulic inorganic filler 20 is added to 100 parts by weight of the color-developing material composed of the mixture of
~ 90 parts by weight and syntactic foam 10-70
In a method for drying a coating film comprising a coating composition in which 1 part by weight is blended, first, it is dried at a temperature of less than 100 ° C. until the evaporation rate of volatile substances becomes 60% by weight or more (hereinafter, this drying Sometimes referred to as "first stage drying", and then
Dry at a temperature of 100 ° C. or higher (hereinafter, this drying is referred to as “2
It may be referred to as "drying of steps").

The water-based emulsion-type or water-based dispersion-type coating composition which is one coating composition of the present invention can be used as long as it is capable of thick film coating.

As the color-developing agent which can be used in another coating composition of the present invention, asphalt such as petroleum asphalt, natural asphalt, butadiene rubber, isoprene rubber, styrene-butadiene rubber, chloroprene rubber, butadiene- Rubber such as acrylonitrile rubber, alkyd resin, epoxy resin, acrylic resin, melamine resin, urethane resin, vinyl resin, acrylic copolymer resin, vinyl acetate copolymer resin, styrene-vinyl acetate copolymer resin, these And synthetic resins such as a blend of these resins.

Such a color-developing material is an aromatic hydrocarbon type,
Used by dissolving in solvents such as petroleum hydrocarbons, alcohols and esters, or dispersed in water (aqueous dispersion type) or emulsified (aqueous emulsion type)
However, the water-based system is generally preferable in terms of environmental measures.

As the hydraulic inorganic filler to be blended with the above-mentioned color-developing material, there are air-crushed slag, cement, gypsum, lime, etc., but in terms of vibration resistance, coating workability, economy and the like. Therefore, it is preferable to mainly use the air-crushed slag.
In this case, the mixing ratio of the air-crushed slag may be about 80% by weight or more of the total amount of the total hydraulic inorganic filler (that is, the air-crushed slag and the other hydraulic inorganic fillers described above). preferable.

The above-mentioned crushed slag is obtained by crushing slag by-produced from a smelting furnace such as a converter or a blast furnace,
For example, calcium oxide 40% by weight, silicic acid 33% by weight, aluminum oxide 17% by weight, magnesium oxide 6
It is composed of weight%. The crushed slag itself has no or no hydraulic property. However, in the case of the air-crushed slag, in the presence of calcium hydroxide, alkali salts, etc., the network structure constituting the glassy structure of the slag is cut, the components are dissolved, and CaO—SiO ₂ —H ₂ O-based hydration is performed. It has a property that a product is formed and it is set and hardened. This property is called latent hydraulic property. The latent hydraulic property of the air-crushed slag is very weak and does not impair the fluidity of the coating composition. The addition of a small amount of a stimulant such as cement not only prevents the coating film from sagging during coating, but also has the effect of accelerating the drying speed of the coating film composition. Further, the air-crushed slag has an appropriate density and exhibits excellent vibration damping properties.

The syntactic foam compounded with the above-mentioned color-developing material together with the hydraulic inorganic filler such as the above-mentioned air-crushed slag means hollow microspheres in a plastic matrix (in the present invention, the above-mentioned color-developing material is Point)) is dispersed. As the hollow microspheres, glass balloons, shirasu balloons, synthetic resin balloons, and the like are specifically used, and the characteristics thereof are not particularly limited, but generally, the bulk density is 0.1 to 0.3 g / cm ^3. Degree, diameter 10
About 300 μm is used because it is easily available.

Further, in the present invention, a part of the syntactic foam can be replaced with synthetic resin powder. As the synthetic resin powder in this case, alkyd resin,
Epoxy resin, silicone resin, phenol resin, polyester resin, acrylic resin, acetal resin, polyethylene resin, polyether resin, polycarbonate resin,
Thermosetting resin powder or heat-capable resin powder such as polysulfone resin, polystyrene resin, chlorinated polyethylene, chlorinated polypropylene, vinyl acetate resin, vinyl chloride resin, chlorinated vinyl chloride resin, vinylidene chloride resin, fluororesin, polypropylene resin, etc. , These copolymer resin powders, blends of these resins, powder coating material recovery products, resin powders generated in the polishing step of resin molded products, crushed resin wastes, and the like can be used.

The above hydraulic inorganic filler and synthetic resin powder each have a particle size of about 300 by any known method.
It is used by adjusting the thickness to less than or equal to μm, preferably about 150 μm or less. That is, the particle size of these fillers is about 300 μm.
This is because if it becomes larger, not only it becomes difficult to obtain a predetermined vibration damping property, but also the storage stability and workability of the coating composition are impaired, which is not preferable.

The mixing ratio of the above hydraulic inorganic filler and syntactic foam is 100 parts by weight of the color developing material.
The hydraulic inorganic filler is about 20 to 90 parts by weight, preferably about 30 to 80 parts by weight, and the syntactic foam is about 10.
70 parts by weight, preferably 20 to 50 parts by weight.

When a part of the syntactic foam is replaced with the synthetic resin powder, the total amount thereof is about 10 to 70 parts by weight with respect to 100 parts by weight of the color-developing material, and the syntactic foam and the synthetic resin powder are mixed. The ratio is preferably about 1 / 0.5 to 1/3 (volume part) of syntactic foam / synthetic resin powder.

When blending only the hydraulic inorganic filler,
For 100 parts by weight of the color-developing material, 10 parts of the hydraulic inorganic filler is used.
If the amount is less than 0 parts by weight, desired vibration damping properties cannot be obtained. On the other hand, in the present invention, since the syntactic foam is blended together with the hydraulic inorganic filler, if at least about 20 parts by weight of the hydraulic inorganic filler is present, synergistic action with the syntactic foam will provide excellent vibration damping. It is possible not only to obtain the property, but also to reduce the weight. However, when the hydraulic inorganic filler is blended in a larger amount than about 90 parts by weight, the vibration damping property is improved but the weight is increased, which is not preferable.

If the blending amount of syntactic foam or the total blending amount of syntactic foam and synthetic resin powder is less than about 10 parts by weight, desired vibration damping properties and weight reduction cannot be achieved, If the amount is more than about 70 parts by weight, the coating composition becomes highly viscous and the coating operation becomes difficult.

In the present invention, it is particularly effective to substitute a part of the syntactic foam with synthetic resin powder. That is, in the case of room temperature drying, since the dry coating film is densely finished, it is not necessary to mix a high density filler such as a hydraulic inorganic filler, whereas in the case of heat drying, a hydraulic inorganic filler is used. If the content of the material is reduced, not only the film thickness increases during heating and the vibration damping performance is deteriorated, but also when the film thickness reaches several mm, the surface may be lifted or swelled during heating. The problem that occurs when heat-drying or when heat-drying to increase the film thickness when reducing the content of such a hydraulic inorganic filler is substituted with a synthetic resin powder as a part of the syntactic foam. Although the reason is not clear, it can be effectively prevented.

The above synthetic resin powder may contain a pigment to color the coating composition of the present invention. Specific examples of the pigment include inorganic pigments such as titanium oxide, cadmium sulfide, iron oxide and chromium oxide, and organic pigments such as copper phthalocyanine blue and condensed polyazo yellow.

In the present invention, calcium carbonate, calcium silicate (talc), and calcium carbonate are appropriately added in order to improve the uniformity, anti-vibration property, heat insulating property, etc. of the coating film, depending on the application and purpose of the coating film. Silica sand, clay, kiln ash, red iron oxide, asbestos, mica, pumice stone, floating slag, vermiculite, etc. can also be added. In addition, if necessary, ordinary viscosity modifiers, anti-caking agents, film forming aids such as glycol ethers, vinylon fibers, polyethylene fibers, plastic fibers, cellulose fibers, etc. for preventing cracking and adjusting fluidity, etc. It is also possible to blend the organic fiber of.

The coating composition of the present invention is made into a paint by adding an organic solvent, preferably a solvent such as water, and stirring and mixing. In this case, all the formulations and the solvent may be mixed at once, or the color-developing material is dissolved in the solvent in advance,
It is also possible to add a hydraulic inorganic filler, syntactic foam, and other compounding ingredients to this, and mix them with stirring to form a coating material.

The coating composition of the present invention thus formed into a coating material has a volatile content of about 20 to 50% by weight before drying.
It is preferable that If this amount is too small, it becomes solid and it becomes difficult to make it into a paint. On the other hand, if it is too large, the coating film sags and the work of forming the coating film becomes difficult.

The coating composition of the present invention has a viscosity of about 10,000 to 150,000 when it is made into a paint.
0cp (20 ° C, rotation speed 3rpm), specific gravity (15 ° C / 4
It is desirable to have a property of about 0.5 to 1.5. With such properties, it is possible to apply a desired film thickness to a substrate such as a steel plate of an automobile by a known arbitrary means such as a pressure spray or an air spray, and a thick film can be applied freely. It can be carried out. Here, thick film coating means about 0.5 to 1 on a substrate such as a steel plate.
It is applied to a thickness of 0 mm, preferably about 1 to 5 mm.

In the drying method of the present invention, first, in the first stage drying, less than about 100 ° C., preferably about 50 to 95 ° C.
In air, drying is performed at a wind speed of about 1 to 10 m / sec, preferably about 2 to 6 m / sec until the evaporation rate of volatile substances is about 60 wt% or more, preferably about 65 wt% or more. To do. Here, the volatile substance means a substance that evaporates when kept at about 105 ° C. for 3 hours, and mainly includes water and alcohols such as ethylene glycol. That is, assuming that the content of the volatile substance before drying is 100% by weight, about 60% by weight or more is evaporated until about 1% by weight.
Dry at less than 00 ° C.

At this time, if the drying temperature is higher than about 100 ° C., the surface of the coating film will blister. However, if the drying temperature is too low, it takes a long time to evaporate the volatile substance by about 60% by weight or more, and the productivity is lowered,
The lower limit is preferably about 50 ° C. as described above. Further, the reason for evaporating the volatile substance by about 60% by weight or more is that if the evaporation is less than about 60% by weight, the coating film surface will swell in the subsequent drying at a high temperature of about 100 ° C. or more. This will happen. The upper limit of the evaporation rate of the volatile substance is not particularly limited, but a large amount of evaporation at a low temperature requires a long time, and a large amount of evaporation at a high temperature (that is, around 100 ° C.) requires a coating film. Since there is a risk of blistering on the surface, it is generally suitable to be about 75% by weight in terms of the production efficiency and the properties of the product coating film.

After the first-stage drying is performed as described above, the subsequent second-stage drying is performed at about 100 ° C. or higher.
Dry in air at the same wind speed as above to evaporate most of the remaining volatile substances. The higher the temperature at this time, the shorter the drying time, but if the temperature is too high, blistering may occur, so the upper limit is approximately 18
A temperature of 0 ° C is suitable.

In the drying method of the present invention, for example, about 3
In the case of a thick film of mm, about 70 to 95 at the time of drying the first step
By evaporating about 65% by weight of the volatile substance at 0 ° C, most of the volatile substance can be evaporated at about 120 ° C for about 15 to 60 minutes by the second high temperature drying. Moreover, the finish of the coating film surface is also good. In addition, at the time of the first-stage drying, at a temperature of about 70 to 95 ° C., a volatile substance content of about 85 wt.
After evaporation, the second stage drying at high temperature is about 14
At 0 ° C., most of the volatile substances can be evaporated in a shorter time than the above, and blistering of the coating film surface does not occur. Furthermore, at the time of the first-stage drying, about 70 to 95 ° C
By evaporating about 90% by weight of the volatile substance, the second stage drying at high temperature can evaporate most of the volatile substance at about 160 ° C. in an even shorter time, and No blistering on the coating surface.

In the drying method of the present invention, the wind speed is also important in the drying of the first and second steps, and the wind speed within the above range mainly reduces the drying time. It has an effect.

[0033]

【Example】

Examples 1 to 6 and Comparative Examples 1 to 3 Coating compositions A and B having the composition shown in Table 2 and applied to a steel plate (70 x 150 x 0.8 mm) with a thickness of 3 mm were used as samples. It was dried under the conditions shown in Tables 3 to 6.
The evaporation rates of the volatile substances (water) after the first-stage drying and after the second-stage drying were measured, and the appearance of the product coating film was observed to measure the vibration damping property. The results are also shown in Tables 3-5. The drying method and the method for measuring (calculating) the evaporation rate of volatile substances were as shown in Table 1.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

[0037]

[Table 4]

[0038]

[Table 5]

[0039]

As described in detail above, according to the drying method of the present invention, a water-based emulsion type or water-based dispersion type coating composition such as the previously proposed anti-vibration coating composition or a color-developing material can be obtained. A product that uses a specific coating composition containing a hydraulic inorganic filler and a syntactic foam, has a good surface property in a short time, and thus can secure a good vibration damping property. A coating film can be formed. Moreover, in the drying method of the present invention, since the drying is simply performed in two steps, it is possible to change the production steps of conventional automobiles, washing machines, refrigerators, etc. without any change.
It can be carried out.

Front Page Continuation (72) Inventor Masahiko Doda 1134-2 Gongendo, Satte City, Saitama Cosmo Research Institute, Inc. R & D Center

Claims (2)

[Claims] 1. A method of drying a coating film comprising a water-based emulsion type or water-based dispersion type coating composition, wherein first, at a temperature of less than 100 ° C., the evaporation rate of a volatile substance is 6
A method for drying a coating film, which comprises drying to 0% by weight or more, and then drying at a temperature of 100 ° C. or more. 2. A color spreader 1 comprising a mixture of at least one selected from the group consisting of asphalt, rubber and synthetic resin.
In a method for drying a coating film comprising a coating composition in which 20 to 90 parts by weight of a hydraulic inorganic filler and 10 to 70 parts by weight of syntactic foam are blended with respect to 00 parts by weight, first, a temperature of less than 100 ° C. And the evaporation rate of volatile substances is 6
A method for drying a coating film, which comprises drying to 0% by weight or more, and then drying at a temperature of 100 ° C. or more.