Method for applying waterproof coating layer to building roof

Abstract

 A simple and efficient method for applying a waterproof coating layer to a roof is disclosed. Pressure feed equipment for a water-proofing two-component urethane resin is installed on the ground, which includes a couple of tanks (4,5) storing predetermined amounts of a prepolymer and a hardener, a pneumatic pump (6) for forwarding separately the agents in a predetermined ratio, and extension hoses (15,16), each of one end of which is connected to the pump 6. A mixing and discharging equipment (3) includes a static mixer (19) for mixing the prepolymer and the hardener and a discharging nozzle 19a equipped on the mixer (19) integrally, for discharging the mixed resin towards a surface to be coated. The discharging and mixing equipment (3) is disposed on a rooftop and the other ends of the hoses (15,16) are connected thereto. The viscosity at 20°C of the prepolymer is set at 4000-7000 cps from spring to autumn and at 1500-3500 cps during winter. The viscosity of the hardener is set at 3000-15000 cps from spring to autumn and at 3000-7500 cps during winter.

Description

[0001] The present invention relates to a method for applying a waterproof coating layer to a roof, specifically suitable for a water-proofing of a flat roof.

[0002] Among typical coating materials for general roof water-proofing is a two-component urethane resin. A conventional process of water-proofing using the two-component urethane is generally described as follows:

[0003] Firstly, coating equipment such as cans containing, respectively, a prepolymer and a hardener of the two-component urethane, a bucket, a portable mixer, and coating tools, are carried up to a rooftop. The cans are opened to convey the prepolymer and the hardener into the bucket in a predetermined mixing ratio, then the materials in the bucket are mixed for three (3) to four (4) minutes by the portable mixer. The mixture is carried to an area to be coated. The mixture is poured onto the area as a plurality of stick-shaped materials arranged in parallel and spread to form a layer of uniform thickness using coating tools.

[0004] After the coating work is finished, the empty cans and coating equipment are brought down to the ground. The empty cans are usually abandoned as waste.

[0005] Accordingly, this kind of coating work inevitably entails manual processes by workers, ranging from unloading of the equipment, preparation, and coating to arrangements after the coating work, in which there exists a long need for saving labour. Another problem also remains unsolved, i.e., disposal of the waste after the work such as the emptied cans and the mixed urethane resin.

[0006] An alternative method proposed for the above smearing method is a rim spray method. This method is typically implemented in work in common use corridors or on staircases in condominiums.

[0007] The rim spray method, however, still has the following shortcomings. Firstly, a delivery hose for the coating material must be preheated by electric wires wound therearound upon application thereof. Secondly, since it may be very difficult to form a coated layer with a thickness of over one (1) millimeter by spraying at one time, several instances of spraying work may be required to obtain a coating layer with the necessary thickness, for example three (3) to four (4) millimeters as a water-proofing film. Furthermore, specifically in the case of application on rooftops, it has been almost impossible to apply the rim spray method, since protection of existing structures on the rooftop from the spray mist generated by spraying is difficult. Therefore, implementation of the rim spraying method in rooftop works has been very difficult.

[0008] An object of the present invention is to provide a method for applying a waterproof coating layer to a roof, which allows the prepolymer and the hardener of a two-component urethane resin as coating material to be pumped up to a rooftop and, then, mixed and discharged without preheating of the agents, throughout the year.

[0009] Another object of the present invention is to provide a method for applying a waterproof coating layer to a roof, which can avoid work in loading, unloading and mixing of the coating material, and work in protecting rooftop structures from the coating material before coating, thus enabling improvements in coating work efficiency, easy arrangement after the work, and saving labour.

[0010] Yet another object of the present invention is to provide a method for applying a waterproof coating layer to a roof, enabling maximum reduction in the amount of waste such as empty cans.

[0011] To accomplish these and other objects of the invention, according to one aspect of the present invention, a method for applying a waterproof coating layer to a roof to form a waterproof coating layer thereon by mixing and applying a two-component urethane resin including a prepolymer and a hardener therein comprises the steps of disposing means for transporting the prepolymer and the hardener, respectively, in a predetermined ratio, the transporting means being placed on the ground, disposing means for mixing the prepolymer and the hardener forwarded from the transporting means, and means for discharging a mixture containing the prepolymer and the hardener in the predetermined ratio to a surface to be coated, the mixing means being placed on the rooftop and communicating with the transporting means, the discharging means being integrally attached to the mixing means, and supplying the prepolymer and the hardener by the transporting means to the mixing and discharging means so as to apply the mixture of the prepolymer and the hardener to the surface to be coated on the rooftop, wherein in spring, summer and autumn the viscosity of the prepolymer is set within the range of 4000-7000 cps at 20°C, and the viscosity of the hardener is set within the range of 3000-15000 cps at 20°C, and during winter the viscosity of the prepolymer is set within the range of 1500-3500 cps at 20°C, and the viscosity of the hardener is set within the range of 3000-7500 cps at 20°C.

[0012] The equivalent ratio of NCO/NH₂+OH on mixing of the prepolymer and the hardener is preferably within the range of from 1.25/1.00 to 1.05/1.00 in volume ratio.

[0013] The transporting means may comprise pressure feed equipment including a couple of containers for storing, respectively, the prepolymer and the hardener of the two-component urethane resin, a couple of pumps for transporting, respectively, the prepolymer and the hardener from the containers in a predetermined ratio, and a couple of extension hoses, each of one end of which is connected to the pumps, respectively.

[0014] The mixing means may be a static mixer. The static mixer is connected to each of the other ends of the extension hoses.

[0015] The discharging means may comprise a discharge nozzle integrally provided with a tip end portion of the static mixer.

[0016] Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein only the preferred embodiment of the invention is shown and described, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

Fig. 1 shows a schematic flow diagram of one embodiment of the present invention; and

Fig. 2 is an explanatory view of working process of one embodiment of the present invention.

[0017] An apparatus employed in one embodiment of the present invention, generally comprises a transportation vehicle 1, such as a truck, carrying pressure feed equipment constituting a main portion of the apparatus, and manual operation type mixing and discharging equipment 83 disposed on the rooftop of a building 2, which sequentially and automatically mixes two-component urethane resin supplied from the pressure feed equipment and discharges the mixture onto the surface to be coated. The two-component urethane resin is supplied to the mixing and discharging equipment by the pressure feed equipment in separated condition before mixing.

[0018] The pressure feed equipment includes such components disposed on a carrier 1a of the vehicle 1 as a prepolymer tank 4, a hardener tank 5, a pneumatic pump 6, a pneumatic pump 7 integrally equipped on a solvent can 7a as a solvent container, a nitrogen gas bomb 8, a hose reel 9, and a compressed air source unit 10 for supplying compressed air to the respective pumps.

[0019] It should be noted that, as shown in Fig. 2, the tanks 4, 5, the pumps 6, 7, the gas bomb 8 and the hose reel 9 are installed on tables with casters 11, 12 and 14, respectively to constitute a group of portable units independent from the carrier 1a. Though the mixing and discharging equipment 3 is shown with a certain exaggeration in size in Fig. 2, the equipment 3 actually has reasonable dimensions so as to be handled manually.

[0020] The compressed air source unit 10 comprises an air compressor 10a and a valve unit 10b. The compressor 10a is driven by an engine such as a Diesel engine.

[0021] The mixing and discharging equipment 3 includes a head block 18 and a static mixer 19. The head block 18 is connected to a discharging end of the pneumatic pump 6 and to a tip end of an extension hose 17 for solvent transportation. The extension hose 17 is connected with the discharging ends of extension hoses 15 and 16 extended from the hose reel 9 for conveying the prepolymer and the hardener, respectively, and with the pneumatic pump 7. The static mixer 19 is integrally disposed on the tip portion of the head block 18.

[0022] Drums 20 and 21 are containers of two hundred (200) liters for stock solution of the prepolymer and the hardener of the waterproof urethane coating material. The prepolymer and the hardener stored in the drums 20 and 21 are forwarded to the tanks 4 and 5, respectively, by means of drum pumps 22 and 23 driven by the compressed air source unit 10. The drums 20, 21 and the drum pumps 22, 23 may be placed at the predetermined storage place after the material is conveyed into the tanks 4 and 5. Alternatively, the drums 20, 21 may be usually carried on the vehicle 1 so that the prepolymer and the hardener can be supplied to the tanks 4, 5 when necessary.

[0023] It is desirable that the prepolymer and the hardener are contained in bags such as double wall polyethylene bags equipped in the drums 20, 21 so that the drums 20, 21 can be recycled after the materials stored in the drums are exhausted.

[0024] Typical examples of the prepolymer include addition compounds of known di-isocyanate compounds or, occasionally, known polyisocyanate compounds and known compounds having two or more -NCO radicals at the end of the molecule such as polyoxy-alkylene polyol or polyester polyol. In other words, a typical substance employed as a prepolymer for the present invention is an isocyanate prepolymer having two or more -NCO radicals at the end thereof.

[0025] The hardener of the two-component urethane resin is a paste-like substance including an aromatic diamine having active hydrogens reacting with the -NCO radicals in the prepolymer and polyoxyalkylene polyol, a plasticizer, a catalyst, an inorganic filler, a pigment, and other additives. The hardener should be selected so as to correspond to the -NCO radicals in the prepolymer to be employed. Then, the composition of the hardener may be set so that the equivalent ratio of the -NH₂ radical and -OH radical, i.e., NCO/NH₂+OH equivalent ratio expressed as the volume mixing ratio of the prepolymer and the hardener, is between 1.25/1.0 and 1.05/1.0.

[0026] The viscosity of the prepolymer and the hardener should be adjusted to fall into the following appropriate ranges in TABLE 1 at 20°C so that the prepolymer and the hardener can be fed, mixed, and discharged by the pneumatic pumps at approximately ten (10) to fifteen (15) kg/min without preheating, throughout the year.

TABLE 1

Viscosity ranges at 20°C
Type of agent	Viscosity (cps)	Applicable seasons
Prepolymer	4000 to 7000	Spring/Summer/Autumn
Hardener	3000 to 15000
Prepolymer	1500 to 3500	Winter
Hardener	3000 to 7500

[0027] The viscosity of the prepolymer is adjusted by adding a plasticizer, or a solvent, or both, at the time of charging the raw materials or after termination of the reaction in manufacturing thereof. The viscosity of the hardener can be adjusted by components variable in amount in the liquid component of the agent, such as by a little variation in the amount of plasticizer, variation in the amount of inorganic filler, and in the compounding ratio of fillers with different particle sizes.

[0028] The prepolymer tank 4 is a simple sealed tank so as to prevent reaction of the agent with water. Nitrogen gas is also supplied into the tank 4 from the nitrogen gas bomb 8 to maintain an inactive gas atmosphere therein.

[0029] Both of the prepolymer and the hardener are able to be transported under safe working pressure throughout the year, while the discharging rate within the predetermined range is secured.

[0030] The aforementioned appropriate viscosity ranges for the prepolymer and the hardener are determined based on the following reasoning through experiments:

[0031] If the viscosity of the prepolymer for spring, summer and autumn use (to be employed in spring, summer and autumn) is below 4000 cps at 20°C, the viscosity drops under 1000 cps where the air and material temperature is over 35°C at a job site specifically in summer, to show a tendency to result in a mixing failure. On the other hand, if the viscosity of the prepolymer for spring, summer and autumn use is set above 7000 cps at 20°C, the viscosity reaches 14000 to 18000 cps where air and material temperature falls below 15°C in early spring or in late autumn, to increase the pump pressure for measurement and transportation up to 150 to 160 kgf/cm². As a result, it is almost impossible to operate the apparatus continuously for safety reasons and the discharging rate may also fall into an impractical range. With respect to the hardener, the viscosity ranges have been determined in the same manner.

[0032] If the viscosity of the prepolymer for winter use (to be used during winter) is set over 3500 cps at 20°C, the viscosity reaches above 15000 cps in midwinter to obstruct safe and continuous operation of the pumps and decrease the discharging rate below a practical value. A viscosity below 1500 cps at 20°C will tend to cause a mixing failure at the relatively higher air temperature in early spring or in late autumn since the viscosity falls below 1000 cps in that condition. The viscosity of the hardener for winter use is determined in the same manner.

[0033] The pneumatic pump 6 for conveying the prepolymer and the hardener with the above adjusted viscosity is of constant-volume type, and comprises a pneumatic motor 6a connected to the compressed air source unit 10 and a pair of plunger pumps 6b, 6c connected to the bottom portion of the pneumatic motor 6a. The suction ends of the pumps 6b, 6c communicate with the tanks 4, 5, respectively.

[0034] The extension hoses 15, 16 are extended from the hose reel 9 and connected to the discharging ends of the pumps 6b, 6c, respectively. Each of the hoses 15, 16 is approximately 100 m long to reach the 14th or 15th floor of a building. The discharging rate and operation pressure of the pneumatic pump 6 is determined according to the length of the hoses 15, 16.

[0035] In case that the mixing ratio of the prepolymer and the hardener is set at around 1/1 in volume ratio, the discharging rate is set at 3 to 16 kg/min based on the operating conditions, and the normal pressure is set at 20 to 160 kg/cm² in consideration of economic operation of a constant-volume type pump. It is possible to pump the prepolymer and the hardener up to the 14th or 15th floor and to mix and discharge them without the need for preheating the agents, throughout the year, by adjusting the viscosity of the prepolymer and the hardener.

[0036] The static mixer 19 of the discharging and mixing equipment 3 has a plurality of helical stators for mixing therein. The prepolymer and the hardener introduced into the mixer 19 are uniformly mixed by reaching the tip end portion thereof to be discharged from the discharging nozzle 19a towards the surface to be coated in a stick-shaped mixture. Therefore, the discharging operation and spreading work are alternately repeated to constitute whole coating operation.

[0037] Discharging and stopping of the mixture of the prepolymer and the hardener is controlled by opening and shutting a control valve 18a disposed upstream of the mixer 18. The discharging rate of the mixture of the prepolymer and the hardener is set by adjustment of such equipment as the pressure regulating valve equipped on the pneumatic pump 6.

[0038] During a pause in discharging, a solvent stored in the solvent can 7a is supplied into the head block 18 by operating the pneumatic pump 7 for pressure feeding of the solvent and opening a cock 18b connected to a solvent conveying extension hose 17. The mixture of the prepolymer and the hardener remaining in the head block 18 and the static mixer 19 is solved into the solvent to wash out the nozzle 19b from time to time without disassembling the equipment. Thus, clogging by the cured resin mixture can be prevented.

[0039] The waterproof coating process of the present invention using the above described apparatus will be fully explained herebelow.

[0040] The transportation vehicle 1 is parked beside the building 2 where there is the working site. After a wait on the ground, the extension hoses 15, 16 and 17 are extended from the hose reel 9 towards the rooftop 2a. The mixing equipment 3 at the tip portion of the hoses 15, 16 and 17 is hoisted up to the rooftop 2a to finish the unloading work.

[0041] Then, the prepolymer and the hardener are forwarded up to the rooftop 2a by driving the pumps 6, 7. At the rooftop 2a, the mixed resin is discharged through the discharging nozzle 19a onto the surface to be coated and is spread out by the workers with application tools. The coating work is thus performed.

[0042] In order to finish the work, the cock 18b of the head block 18 is opened to flow solvent into the nozzle 19 and to wash out the mixed resin remaining in the nozzle 19 from time to time.

[0043] After the coating work is finished, the extension hoses 15, 16 and 17 are rolled back onto the hose reel 9 and the mixing and discharging equipment 3 is carried down to the ground. The residual prepolymer and the hardener are contained in the tanks 4, 5 in separated condition, and each residue may be brought back into the drums 20, 21, or stored for the next job after a conservation treatment.

[0044] The experimental examples of the present invention will be discussed herebelow according to variation of the viscosity of the prepolymer and the hardener and the results therefrom.

Experimental example 1

[0045] The discharging test was conducted using the prepolymer and the hardener shown below.

[Material combination 1]

Prepolymer

[0046] 

PPG-TDI prepolymer

97.5 weight parts

Adipic acid-di-2-ethylhexyl

2.5 weight parts

Total

100.0 weight parts

NCO content

3.70%

Specific gravity

1.05

Viscosity

5300 cps/20°C

Hardener

[0047] 

Specific gravity

1.49

Viscosity

5600 cps/20°C

[Test condition]

[0048] 

Outside air temperature

31°C

Coating surface temperature

46°C

Material temperature

29°C

Extension hose length

100 m

Working site

Rooftop of the 3rd floor

[Result]

[0049] The air compressor was actuated to drive the respective drum pumps for the prepolymer and the hardener and to forward the agents into the hopper. Then, the valve of the pneumatic motor was opened and the valve of the regulator was gradually opened. When the pressure was at 2.0 kgf/cm², the pressure gauges of the prepolymer and the hardener indicated 90-105 kgf/cm² and 60-70 kgf/cm², respectively. The constant-volume pump reciprocated thirty (30) times a minute. The discharging ratio of the prepolymer and the hardener measured at the tip end portion of the hose placed at the rooftop immediately before the head block 18 was 100/142.1 in weight ratio. According to the measured discharging ratio, the quantity of the hardener was more than the planned value by 0.2%. However, this result was sufficiently within allowable tolerances of design. The discharging rate from the static mixer while the hoses were connected to the head block 18 was 15.3 kg/min. The discharged mixture was spread flat in two (2) millimeters thickness with a scratching trowel and the coated surface showed a uniform colour, which indicated that the prepolymer and the hardener were sufficiently mixed.

Experimental example 2

[0050] The discharging test was conducted using the prepolymer and the hardener shown as material combination 2.

[Material combination 2]

Prepolymer

[0051] 

PPG-TDI prepolymer

95.0 weight parts

Adipic acid-di-2-ethylhexyl

2.5 weight parts

Xylene

2.5 weight parts

Total

100.0 weight parts

NCO content

3.64%

Specific gravity

1.048

Viscosity

4000 cps/20°C

Hardener

[0052] 

Specific gravity

1.47

Viscosity

3200 cps/20°C

[Test condition]

[0053] 

Outside air temperature

33°C

Coating surface temperature

49°C

Material temperature

30°C

Extension hose length

100 m

Working site

Rooftop of the 3rd floor

[Result]

[0054] The discharging test was conducted according to the procedure in Example 1. The pumps for the prepolymer and the hardener reciprocated thirty (30) times a minute at 1.3 kgf/cm² regulator pressure. The pressures for transportation of the prepolymer and the hardener were 40-45 kgf/cm² and 35-40 kgf/cm², respectively. The discharged mixture was spread flat with a scratching trowel to show a uniform gray colour, which indicated a good mixing condition. The measured discharging rate from the mixer was 15.8 kg/min.

Experimental example 3

[0055] The discharging test was conducted using the prepolymer and the hardener shown as combination 3 under the test conditions below.

[Material combination 3]

Prepolymer

[0056] 

PPG-TDI prepolymer

94.0 weight parts

Adipic acid-di-2-ethylhexyl

3.0 weight parts

Xylene

3.0 weight parts

Total

100.0 weight parts

NCO content

3.57%

Specific gravity

1.046

Viscosity

3600 cps/20°C

Hardener

[0057] 

Specific gravity

1.504

Viscosity

2800 cps/20°C

[Test condition]

[0058] 

Outside air temperature

16°C

Coating surface temperature

28°C

Material temperature

15°C

Extension hose length

100 m

Working site

Rooftop of the 3rd floor

[Result]

[0059] The discharging test was conducted according to the same procedure as in Example 2. The constant-volume pumps reciprocated thirty (30) times a minute at 1.0 kgf/cm² regulator pressure. The pressures for transportation of the prepolymer and the hardener were 30-40 kgf/cm² and 25-33 kgf/cm², respectively. The measured discharging rate was 16.4 kg/min. The discharged mixture was spread flat with a scratching trowel, and transparent line portions gradually appeared. The coated surface was examined once cured on the next day, and a series of air bubbles caused by small-scale blowing were observed along the line portions, which were mixing failure portions of the prepolymer. It was also observed that the colour at several portions in the coating layer had changed brown. It was presumed that the quantity of hardener mixed with the prepolymer had been significantly larger than appropriate. Furthermore, the hardener stored in the storage drum had separated into a supernatant portion and a lower portion.

Experimental example 4

[0060] The discharging test was conducted using the prepolymer and the hardener shown as combination 4 under the test conditions below.

[Material combination 4]

Prepolymer

[0061] 

PPG-TDI prepolymer

97 weight parts

Adipic acid-di-2-ethylhexyl

1 weight parts

Xylene

2 weight parts

Total

100 weight parts

NCO content

3.73%

Specific gravity

1.05

Viscosity

6800 cps/20°C

Hardener

[0062] 

Specific gravity

1.51

Viscosity

14000 cps/20°C

[Test condition]

[0063] 

Outside air temperature

16°C

Coating surface temperature

28°C

Material temperature

14°C

Extension hose length

100 m

Working site

Rooftop of the 10th floor

[Result]

[0064] The discharging test was conducted according to the same procedure as in Example 1. The constant-volume pumps reciprocated twenty seven (27) times a minute at 4.8 kgf/cm² regulator pressure. The pressures for transportation of the prepolymer and the hardener were 140-150 kgf/cm² and 145-155 kgf/cm², respectively. The measured discharging rate was 13 kg/min. The coated surface spread with a scratching trowel showed a uniform colour tone and the mixing condition was good.

Experimental example 5

[0065] The discharging test was conducted using the prepolymer and the hardener shown as combination 5 under the test conditions below. The test was performed subsequent to Example 4.

[Material combination 5]

Prepolymer

[0066] 

PPG-TDI prepolymer

98 weight parts

Xylene

2 weight parts

Total

100 weight parts

NCO content

3.72%

Specific gravity

1.051

Viscosity

7800 cps/20°C

Hardener

[0067] 

Specific gravity

1.54

Viscosity

16000 cps/20°C

[Test condition]

[0068] 

Outside air temperature

15°C

Coating surface temperature

25°C

Material temperature

14°C

Extension hose length

100 m

Working site

Rooftop of the 10th floor

[Result]

[0069] The discharging test was conducted according to the same procedure as in Example 1. The constant-volume pumps reciprocated twelve (12) times a minute at 5.9 kgf/cm² regulator pressure. The pressures for transportation of the prepolymer and the hardener were 160-170 kgf/cm² and 150-160 kgf/cm², respectively. In this condition, the test was halted since it seemed impossible to operate the pumps continuously, for safety reasons, and the discharging rate became very small. However, the condition of the discharged mixture was good.

Experimental example 6

[0070] The discharging test was conducted using the prepolymer and the hardener shown as combination 6 under the test conditions below.

[Material combination 6]

Prepolymer

[0071] 

PPG-MDI prepolymer

92 weight parts

Adipic acid-di-2-ethylhexyl

4 weight parts

Xylene

4 weight parts

Total

100 weight parts

NCO content

4.72%

Specific gravity

1.038

Viscosity

1550 cps/20°C

Hardener

[0072] 

Specific gravity

1.414

Viscosity

3100 cps/20°C

[Test condition]

[0073] 

Outside air temperature

6°C

Coating surface temperature

13°C

Material temperature

7°C

Extension hose length

100 m

Working site

Rooftop of the 10th floor

[Result]

[0074] The discharging test was conducted according to the same procedure as in Example 1. The constant-volume pumps reciprocated thirty (30) times a minute at 3.2 kgf/cm² regulator pressure. The pressures for transportation of the prepolymer and the hardener were 80-90 kgf/cm² and 70-80 kgf/cm², respectively. The measured discharging rate was 14.8 kg/min. The coated surface of the discharged mixture spread with a scratching trowel generally showed a uniform colour tone and the mixing condition was good.

Experimental example 7

[0075] The discharging test was conducted using the prepolymer and the hardener shown as combination 7 under the test conditions below.

[Material combination 7]

Prepolymer

[0076] 

PPG-MDI prepolymer

94 weight parts

Adipic acid-di-2-ethylhexyl

3 weight parts

Xylene

3 weight parts

Total

100 weight parts

NCO content

4.80%

Specific gravity

1.040

Viscosity

3500 cps/20°C

Hardener

[0077] 

Specific gravity

1.423

Viscosity

7450 cps/20°C

[Test condition]

[0078] 

Outside air temperature

5°C

Coating surface temperature

15°C

Material temperature

6°C

Extension hose length

100 m

Working site

Rooftop of the 10th floor

[Result]

[0079] The discharging test was conducted according to the same procedure as in Example 1. The constant-volume pumps reciprocated twenty seven (27) times a minute at 5.5 kgf/cm² regulator pressure. The pressures for transportation of the prepolymer and the hardener were 150-160 kgf/cm² and 120-130 kgf/cm², respectively. The measured discharging rate was 11.6 kg/min. The coated surface spread with a scratching trowel showed a uniform colour tone and a good mixing condition.

Experimental example 8

[0080] The discharging test was conducted using the prepolymer and the hardener shown as combination 8 under the test conditions below.

[Material combination 8]

Prepolymer

[0081] 

PPG-MDI prepolymer

92 weight parts

Adipic acid-di-2-ethylhexyl

4 weight parts

Xylene

4 weight parts

Total

100 weight parts

NCO content

4.70%

Specific gravity

1.036

Viscosity

1380 cps/20°C

Hardener

[0082] 

Specific gravity

1.410

Viscosity

2800 cps/20°C

[Test condition]

[0083] 

Outside air temperature

22°C

Coating surface temperature

34°C

Material temperature

21°C

Extension hose length

100 m

Working site

Rooftop of the 3rd floor

[Result]

[0084] The discharging test was conducted according to the same procedure as in Example 1. The constant-volume pumps reciprocated thirty (30) times a minute at 1.1 kgf/cm² regulator pressure. The pressures for transportation of the prepolymer and the hardener were 20-30 kgf/cm² and 40-50 kgf/cm², respectively. The measured discharging rate was 16.2 kg/min. The discharged mixture was spread flat with a scratching trowel, and transparent stripes appeared. The coated surface was examined once cured and air bubbles were observed in the transparent portions. Those portions were confirmed to include an unmixed prepolymer component. It was determined that the mixing failure occurred because the prepolymer viscosity was too low.

Experimental example 9

[0085] The discharging test was conducted using the prepolymer and the hardener shown as combination 9 under the test conditions below.

[Material combination 9]

Prepolymer

[0086] 

PPG-MDI prepolymer

94 weight parts

Adipic acid-di-2-ethylhexyl

3 weight parts

Xylene

3 weight parts

Total

100 weight parts

NCO content

4.81%

Specific gravity

1.041

Viscosity

3660 cps/20°C

Hardener

[0087] 

Specific gravity

1.425

Viscosity

7700 cps/20°C

[Test condition]

[0088] 

Outside air temperature

5°C

Coating surface temperature

9°C

Material temperature

4°C

Extension hose length

100 m

Working site

Rooftop of the 10th floor

[Result]

[0089] The discharging test was conducted according to the same procedure as in Example 1. The constant-volume pumps reciprocated ten (10) times a minute at 5.8 kgf/cm² regulator pressure. The pressures for transportation of the prepolymer and the hardener were 160-170 kgf/cm² and 150-160 kgf/cm², respectively. The discharging rate was 4.1 kg/min. The pressure of the prepolymer and hardener was too high to continue operation of the pumps.

[0090] While the present invention has been discussed in terms of the preferred embodiments, the present invention should be implemented in various fashions with incorporating modifications of the disclosed embodiments in addition, omission or modification of the detailed construction, without departing from the principle of the invention. Therefore, the present invention should be understood to include all embodiments encompassed within the spirit of the invention set out in the appended claims.

Claims

1. A method for applying a waterproof coating layer to a roof to form a waterproof coating layer thereon by mixing and applying a two-component urethane resin including a prepolymer and a hardener therein, comprising the steps of:

disposing means (1) for transporting said prepolymer and said hardener, respectively, in a predetermined ratio, said transporting means being placed on the ground;

disposing means (19) for mixing said prepolymer and said hardener forwarded from said transporting means, and means (19a) for discharging a mixture containing said prepolymer and said hardener in said predetermined ratio to a surface to be coated, said mixing means being placed on the rooftop (2a) and communicating with said transporting means, said discharging means being integrally attached to said mixing means; and

supplying said prepolymer and said hardener by said transporting means to said mixing and discharging means so as to apply said mixture of the prepolymer and the hardener to the surface to be coated on the rooftop,
   wherein in spring, summer and autumn, the viscosity of said prepolymer is set within the range of 4000-7000 cps at 20°C, and the viscosity of said hardener is set within the range of 3000-15000 cps at 20°C, and during winter the viscosity of said prepolymer is set within the range of 1500-3500 cps at 20°C, and the viscosity of said hardener is set within the range of 3000-7500 cps at 20°C.

2. A method as claimed in claim 1, wherein the equivalent ratio of NCO/NH₂+OH on mixing of said prepolymer and said hardener is within the range of from 1.25/1.00 to 1.05/1.00 in volume ratio.

3. A method as claimed in claim 1 or claim 2, wherein said transporting means comprises pressure feed equipment including a couple of containers (4,5) for storing, respectively, said prepolymer and said hardener of said two-component urethane resin, a couple of pumps (6,7) for transporting, respectively, said prepolymer and said hardener from said containers in a predetermined ratio, and a couple of extension hoses (15,16), each of one end of which is connected to said pumps, respectively.

4. A method as claimed in claim 3, wherein said mixing means comprises a static mixer (19), said static mixer being connected to each of the other ends of said extension hoses.

5. A method as claimed in claim 4, wherein said discharging means comprises a discharge nozzle (19a) integrally provided with a tip end portion of said static mixer.

6. A method for applying a waterproof coating layer to a roof to form a waterproof coating layer thereon by mixing and applying a two-component urethane resin including a prepolymer and a hardener therein, comprising the following steps of:

disposing pressure feed equipment on the ground, comprising a couple of containers (4,5) for storing said two-component urethane resin of said prepolymer and said hardener, respectively, a couple of pumps (6,7) for transporting said prepolymer and said hardener from said containers in a predetermined ratio, respectively, and a couple of extension hoses (15,16), each of one end of which is connected to said pumps, respectively;

disposing mixing and discharging equipment (3) on the roof (2a), said mixing and discharging equipment being connected to each of the other ends of said extension hoses and comprising a static mixer (19) for mixing said prepolymer and said hardener, and a discharge nozzle (19a) integrally provided with a tip end portion of said static mixer for discharging the mixed resin towards a surface to be coated; and

supplying said prepolymer and said hardener by said pressure feed equipment to said mixing and discharging equipment to apply the mixture onto the roof,
   wherein in spring, summer and autumn the viscosity of said prepolymer is set within the range of 4000-7000 cps at 20°C, and the viscosity of said hardener is set within the range of 3000-15000 cps at 20°C, and during winter the viscosity of said prepolymer is set within the range of 1500-3500 cps at 20°C, and the viscosity of said hardener is set within the range of 3000-7500 cps at 20°C.

7. A method as claimed in claim 6, wherein the equivalent ratio of NCO/NH₂+OH on mixing of said prepolymer and said hardener is within the range of from 1.25/1.00 to 1.05/1.00 in volume ratio.

Drawing