JP2520646B2 - Slope coating method for structures - Google Patents

Description

TECHNICAL FIELD The present invention relates to a smooth and uniform surface without sagging on a surface of various structures, including a vertical surface and a steeply inclined surface, that is, a so-called slope.
The present invention relates to a method for rapidly applying a coating film of a room temperature curable polyurethane resin.

BACKGROUND ART Polyurethane paints are roughly classified into one-pack type and two-pack type, and the former are oil-modified paints obtained by reacting a modified polyol such as castor oil, linseed oil and soybean oil with diisocyanate, polyether, Moisture-curable paint that reacts polyester with polyisocyanate and cures it with moisture in the air, thermosetting paint that uses polyether or polyester and block isocyanate, and the latter consists of prepolymer and amine catalyst. Catalytic curing type paint,
Polyol-curable coatings composed of polyesters or polyethers having terminal hydroxyl groups and polyisocyanates are included, respectively.

These polyurethane paints are made of metal, plastic,
It has adhesiveness to rubber, glass, wood, etc., can be used at room temperature, has high coating hardness, elasticity, and has excellent wear resistance, durability, water resistance, chemical resistance, etc. Therefore, it is widely used for coating various surfaces.

However, since these polyurethane paints can be prepared to be fairly viscous when brush-painting or roller-painting, they can be easily applied to non-horizontal surfaces such as vertical surfaces and ceiling surfaces. In this case, since it must be used in a state of good fluidity, when it is applied to so-called slopes such as vertical surfaces and steep slopes, it is unavoidable that sagging or unevenness will occur, and this tendency is especially It becomes remarkable when.

Until now, a two-component non-sag type polyurethane paint that increases the initial viscosity and prevents sagging after applying a primer has been used to form a uniform film thickness along an inclined complex roof shape such as a corrugated board. It has been proposed (Japanese Patent Publication No. 57-39835).

However, this type of polyurethane-based paint is unavoidably mixed with air bubbles due to agitation during preparation in order to increase the viscosity of the paint, and since it is applied by brush coating or roller coating, a coating film formed by one coating The thickness of the
The thickness is about 0.1 mm, which is disadvantageous in that thick film coating requires repeated coating.

As an improvement of such drawbacks, curing from a thixotropic state prepared by using 4,4'-diaminodiphenylmethane and 3,3'-dichloro-4,4'-diaminodiphenylmethane in combination A method of spray-coating a reactive two-component room temperature curing type polyurethane resin composition has been proposed (Japanese Patent Publication No. 59-8431). This method, after mixing the two liquids, by spray coating while the thixotropic state is maintained, by curing while leveling, to prevent the occurrence of sagging and unevenness of the coating surface, In order to completely achieve leveling, it is necessary to select special raw material components so as to increase the time from the coating to the touch-free state, and after coating,
It takes a long time of 12 to 20 hours before walking or handling becomes possible, and at the same time, there is a drawback that dirt due to adhesion of dust and damage due to physical impact are likely to occur during this period.

As described above, all of the conventional polyurethane resin paints that can be used for slope coating have some drawbacks and are not always satisfactory.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention overcomes the disadvantages of conventional non-sag type polyurethane paints and two-component room temperature curing type polyurethane paints that undergo a curing reaction from a thixotropic state, and sprays vertical surfaces of various structures. To provide a coating method that can be applied without causing sagging or unevenness on slopes such as slopes and steep slopes or on ceiling surfaces, and that can be rapidly cured to form a desired polyurethane coating film with high work efficiency. It was made for the purpose.

MEANS FOR SOLVING THE PROBLEMS The inventors of the present invention form a thick film of polyurethane-based paint by spray coating, without causing sagging even on a vertical surface, a steeply inclined surface, or a ceiling surface, and curing it rapidly. As a result of repeated studies to develop a method, in a two-part room temperature-curable polyurethane resin composition that causes rapid curing when each liquid is mixed, when a specific component is combined, at the initial stage of mixing, some Despite the fact that it shows fluidity and is sufficiently spray-paintable, it has been found that when it is applied to the required surface, it rapidly loses fluidity and can be cured without causing dripping or unevenness. The present invention has been completed based on this finding.

That is, according to the present invention, when the surface including the slope of the structure is coated with the polyurethane resin coating material, the first polyurethane resin coating material contains a polyol component containing an epoxy-modified polyol and a crosslinking agent component. A liquid and a second liquid containing an acid or an acid derivative-modified polyisocyanate component, and a two-liquid room-temperature-curable polyurethane resin composition that undergoes a rapid curing reaction when mixed with each other. By spray-coating this mixture on the surface and curing it while maintaining a viscosity that allows spraying after mixing, a thick film can be rapidly applied to the surface including the slope without any trouble. it can.

In the method of the present invention, a two-component room temperature-curable polyurethane resin composition is used as a paint. When this mixture is mixed with the first liquid and the second liquid, it maintains a sprayable viscosity in the initial stage, but is short thereafter. It is necessary to cause a rapid curing reaction within a period of time to increase the viscosity. That is, as the coating material used in the present invention, it is suitable to maintain the viscosity of 50,000 centipoises or less at 20 ° C. for at least 30 seconds after mixing the two liquids and increase to the viscosity of 100,000 centipoises or more in 5 minutes at the longest.

The two-component room temperature-curable polyurethane resin composition exhibiting such characteristics is prepared by blending an epoxy-modified polyol with a polyol component in the first liquid and adding an acid or an acid derivative-modified polyisocyanate as a polyisocyanate component in the second liquid. It is necessary to use.

The polyol component used in the first liquid can be arbitrarily selected from those conventionally used as the polyol component of the room temperature curable two-component polyurethane resin composition. Examples of such substances include organic dicarboxylic acids such as phthalic acid, adipic acid, dimerized linoleic acid, and maleic acid, and ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, trimethylolpropane, hexanetriol, glycerin, and triglyceride. Polyester polyols derived from polyhydric alcohols such as methylolethane and pentaerythritol, and polyester polyols derived from lactones such as polybutyrolactone and polyvalerolactone, poly (oxypropylene) glycol, poly (oxypropylene) Poly (oxyethylene)
Glycol, poly (oxybutylene) glycol, poly (oxytetramethylene) glycol, poly (oxypropylene) triol, poly (oxypropylene) poly (oxyethylene) triol, poly (oxypropylene) poly (oxyethylene) poly (oxypropylene) )
Molecular weight of 300 to 300 among polyether polyols such as triol, polyether polyester polyols containing both the polyester unit and polyether unit and acrylic polyols derived from acrylic acid, etc.
Examples thereof include those having a hydroxyl value of 0 and a hydroxyl value of 50 to 350. These polyols may be used alone or in combination of two or more.

In the present invention, in such a polyol component,
It is necessary to mix and use an epoxy-modified polyol. As this epoxy-modified polyol, those obtained by reacting the above-mentioned polyester polyol or polyether polyol with an epoxy compound such as epihalohydrin or glycidyl alcohol can be used. The epoxy-modified polyol is blended in a proportion of at least 5% by weight based on the total amount of the polyol component. By blending the epoxy-modified polyol in this way, it is possible to suppress the decrease in the strength of the coating film due to rapid curing, and to give permanent resistance to impact and abrasion.

Next, in the first liquid, as a cross-linking agent component used in combination with this polyol component, aliphatic diols such as ethylene glycol, propylene glycol, butylene glycol, pentanediol, diethylene glycol and dipropylene glycol, ethylenediamine, propylenediamine , Aliphatic diamines such as butylene diamine, pentamethylene diamine, aniline, phenylenediamine, 4,4'-methylene dianiline, 2,2-bis (p-
Aminophenyl) propane, 3,3'-dichloro-4,4'-
Aromatic amines such as diaminophenylmethane and 1,2-bis (2-aminophenylthio) ethane are used. In the present invention, it is advantageous to use, from among these cross-linking agents, one having a fast reaction rate and one having a slow reaction rate in combination. By using such a combination, it is possible to prevent sagging due to a rapid curing reaction and, at the same time, secure a time during which handling during coating is possible. As the crosslinking agent having a high reaction rate and the crosslinking agent having a slow reaction rate, a mixture of two or more kinds may be used.
The ratio of these to be used is appropriately in the range of 1: 1 to 1:20 in terms of the ratio of the total weight of the crosslinking agent having a fast reaction rate and the total weight of the crosslinking agent having a slow reaction rate.

In addition to the above-mentioned components, this first liquid contains, if desired,
Extenders such as silica, talc, barium sulfate, iron oxide yellow, light yellow 50, iron oxide brown, iron oxide red, light bull
100, Chrome oxide green GN color pigments, organotin compounds, organolead compounds catalysts, amine wetting agents adhesion improvers, etc. Can be included.

And, the first liquid has a viscosity at 20 ° C of 1000 to 35
It is desirable to select and prepare each component so that it becomes 00 centipoise.

Next, in the present invention, it is necessary to use an acid-modified polyisocyanate as the polyisocyanate component in the second liquid. Examples of the acid or acid derivative-modified polyisocyanate include hexamethylene diisocyanate, octamethylene diisocyanate, tolylene diisocyanate, 1,5-naphthalene diisocyanate, diphenylmethane-4,4'-diisocyanate, and biphenyl-4,4'-.
Diisocyanate, 2,2-diphenylpropylene-p, p '
-Polyisocyanate used in ordinary polyurethane resin paints such as diisocyanate, phosphoric acid, acetic acid,
It is obtained by adding and modifying an acid such as oxalic acid, succinic acid, maleic acid or an acid ester such as ethylhexyl phosphate, pentyl phosphate, octyl phosphate in a proportion of 10 to 1000 ppm.

Generally, in the thick film type coating material of the present invention, if the polyisocyanate component is used as it is as the second liquid component, it is difficult to obtain a uniform and smooth coating film because of a high reaction rate. Also, if via the prepolymer,
Since the reaction rate can be controlled, such drawbacks are eliminated, but the viscosity becomes high, and thus it is necessary to take a long time for leveling.

However, when the polyisocyanate modified with an acid or an acid derivative is used as described above, it is possible to suppress a rapid reaction without increasing the viscosity as in the case of the prepolymer, and it is possible to handle in a short time. And a uniform and smooth coating film can be formed.

This second liquid is preferably prepared so that the viscosity at 20 ° C. is 100 to 300 centipoise.

Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a spray device 1 used in the method of the present invention.
FIG. 1 is an explanatory diagram showing an example, in which a first liquid is stored in a tank 1, a pressure feed pump 2 passes through a pipe line 3, a filter 4,
It is sent to the mixing chamber 7 via the heater 5 and the metering pump 6.
On the other hand, the second liquid is similarly pumped from the tank 1'to the pump 2
It is sent to the mixing chamber 7 through the pipe 3 ', the filter 4', the heater 5'and the metering pump 6 '. The first liquid and the second liquid mixed in the mixing chamber 7 are uniformly mixed by a static mixer 8 and sprayed onto a surface to be coated by a spray gun 9. Reference numeral 11 denotes a pump for promptly washing and removing the mixed paint in the spray gun 9 and the hose.

The first liquid is usually heated to a temperature of 30 to 80 ℃, 200 to 1000 cps
The viscosity is adjusted to be mixed with the second liquid. The mixing ratio of the first liquid and the second liquid is usually such that a polyol component obtained by adding an epoxy-modified polyol to a polyol such as polyester polyol or polyether polyol in the first liquid and active hydrogen of an amine component or a diol component. The total number of moles and the number of moles of the isocyanate groups of the diisocyanate component in the second liquid are selected to be approximately the same, but either one can be used in excess if desired.

In the slope coating of the present invention, it is desirable to first apply a primer coating with a polyurethane coating to the required surface in advance. This primer may be either a one-component polyurethane paint or a two-component polyurethane paint, but is not limited to toluene, xylene, methyl ethyl ketone,
It is used after diluting with a solvent such as methyl isobutyl ketone, acetone, ethyl acetate, butyl acetate, methyl glycol acetate, ethyl glycol acetate. As the one-component polyurethane-based paint used as a primer, for example, polyether, polyol polyester polyol, castor oil, etc., TDI, MDI, moisture-curable urethane paint obtained by excessive reaction of HMDI, and phenol, etc. There is a thermosetting urethane paint containing a blocked block isocyanate and a polyester polyol.

Further, as an example of the two-component polyurethane-based coating material, a molecular weight of 300 to 3000, a hydroxyl value of 50 to 350 mg / g of a polyester polyol, a polyether polyol or an epoxy modified polyol or a first liquid containing a mixture thereof, and a modified diphenylmethane- Mention may be made of a second liquid containing a diisocyanate such as 4,4'-diisocyanate, modified biphenyl-4,4'-diisocyanate and modified 2,2-diphenylpropane-p, p'-diisocyanate.

In these polyurethane-based paints for primers, in addition to the above components, additives that are commonly used in ordinary polyurethane-based paints such as extender pigments, coloring pigments, catalysts,
A modifier or the like can be added.

These primers are applied on a desired slope with a brush, roller, airless coater or the like so as to have a film thickness of 10 to 100 μm, preferably 20 to 50 μm.

In this way, by spraying the required polyurethane resin composition on the surface subjected to the primer treatment in an amount such that the thickness after curing becomes 0.1 to 10 mm using the above-mentioned spray device, A thick coating film can be obtained without causing sagging or unevenness due to nonuniformity of the film thickness.

The coating method of the method of the present invention includes not only metal materials such as steel materials, stainless steel materials, and aluminum materials, but also plastics,
Since it can be applied to concrete, glass, various ceramics, etc., for protection of buildings, storage tanks, sewer pipes, water pipes, various vehicles, ships, tunnels, etc., repair, corrosion protection, rust prevention, waterproofing, It can be widely used.

EFFECTS OF THE INVENTION According to the method of the present invention, a smooth and uniform coating film of a polyurethane resin paint is formed on a surface including a slope of a structure with a thickness of 0.1 to 10 mm in one operation without causing any sagging or unevenness. In addition, the effect of being able to reduce the time required to obtain a handleable hardness of 12 to 20 hours in the past can be reduced to less than 1 hour.

Furthermore, the coating film obtained by the method of the present invention has a tensile strength
150Kg / cm ² or more, Shore D hardness (20 ° C) 50 or more, adhesive strength 80-150Kg / cm ² , tensile strength of coating film by conventional method 2
0-50Kg / cm ² , Shore D hardness (20 ℃) 10-40, Adhesive strength 4
It shows much better physical properties than 0-70Kg / cm ² .

EXAMPLES Next, the present invention will be described in more detail with reference to examples.

Examples 1 and 2 70.6 parts by weight of epoxy modified polyol (molecular weight 2000, hydroxyl value 175), 9.0 parts by weight of silica powder, 2.0 parts by weight of toner pigment and xylene, after the inner surface of the curved surface of the steel wastewater treatment tank was shot blasted And a first liquid consisting of 18.4 parts by weight of a mixture of methyl ethyl ketone, 99.92 parts by weight of an organic acid-modified diphenylmethane-4,4'-diisocyanate,
A second liquid consisting of 0.03 part by weight of dibutyltin dilaurate and 0.05 part by weight of an amine-based adhesion improver (Disperbyk-130) was mixed at a weight ratio of 70:30 using an airless coating machine and applied to a thickness of 20 μm to prepare a primer. Layers were formed.

Then, on this primer, the first liquid having the composition shown in Table 1 and the second liquid consisting of diethylhexyl phosphate modified diphenylmethane-4,4'-diisocyanate were used in a volume ratio of 75/25, It was painted to a thickness of 1 mm by the spray device shown in FIG.

In this way, a smooth and uniform coating film was obtained without any sagging or unevenness in any case. After 24 hours, all of these coating films exhibited an adhesive strength of 100 kg / cm ² or more and a tensile strength of 180 kg / cm ² or more.

The change in viscosity with time after mixing the first liquid and the second liquid with the composition of Example 1 is shown as a graph in FIG. 2 by a solid line. For comparison, the conventional method (Japanese Patent Publication No. 59-8431)
The change in viscosity with time in the case of the method of the publication) is also shown by a broken line.

In this case, when only the polyester polyol was used without blending the epoxy-modified polyol, the tensile strength of the obtained coating film was 150 Kg / cm ² or less.

Example 3 Using the composition of Example 1, various structures were coated under the same processing conditions as in Example 1 except for the film thickness. The adhesive strength of the coating film thus obtained after 48 hours is shown in Table 2.

Example 4 A flat inner wall of a concrete waste water treatment tank was treated with a shot blast, and 40% by weight of a polyester moisture-curable urethane resin (molecular weight 2500, isocyanate content 1.6%), 15 parts by weight of silica powder and toluene, A paint consisting of 45 parts by weight of an equal volume mixture of xylene and ethyl acetate was applied by an airless coating machine to form a primer layer having a thickness of 20 μm.

Then, a two-component room temperature curing type polyurethane resin composition having the same composition as in Example 1 was applied thereon in the same manner as in Example 1 to obtain a coating film having a film thickness of 2 mm. After curing for 48 hours, the adhesive strength of this coating film was measured, and it was found that the base concrete broke at 60 kg / cm ² , but no peeling of the coating film was observed.

Reference Example The coating composition of Example 1 was applied to a primer-treated steel sheet to form a coating film having a film thickness of 1 mm to prepare a sample.

This sample should be kept at 20 ℃ in various solutions or in an atmosphere.
The results of annual exposure are shown in Table 3. For comparison, the results of the sample obtained by the conventional method (method of Japanese Patent Publication No. 59-8431) are also shown.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a spray apparatus used in the method of the present invention, and FIG. 2 is a graph showing changes in viscosity of a coating film with time according to the method of the present invention and the conventional method. In the figure, 1 is a first liquid tank, 1'is a second liquid tank, 2 is a pressure pump, 5 is a heater, 6 is a metering pump, 7 is a mixing chamber,
8 is a static mixer, and 9 is a spray gun.

Claims (1)

(57) [Claims] 1. A first liquid containing a polyol component containing an epoxy-modified polyol and a cross-linking agent component when the surface of a structure including a slope is coated with a polyurethane resin paint, A room temperature-curable polyurethane resin composition that is composed of a second liquid containing an acid or acid derivative-modified polyisocyanate component and exhibits a low viscosity in the initial stage of mixing, and has a viscosity that allows spraying after mixing the first liquid and the second liquid. A method for surface coating of a structure, characterized in that the mixture is spray-coated on the surface while being held and then cured.