Background Art Vehicles such as automobiles are, in many cases, stocked at outside stock yards after production until they are given to users or transported by trucks, ships or the like. Since those vehicles are exposed to dust, metallic powder, salt, oil, acid and direct sunlight while so stocked and transported, there is caused a risk that the quality of a surface layer of a plurality of paint layers applied to the outer surface of vehicles is damaged during such long storage and transportation. With a view to preventing the occurrence of such situations, there is known a method for forming a strippable protective layer on painted portions of vehicles ina stepbefore they are shipped (for example, refer to Patent Literature No. 1). The strippable protective layer is formed when an applied protective layer forming material <BR> <BR> . (alsoreferredtoasastrippablepaint) getsdriedandcanprotect painted portions. In addition, when attempted to be removed, the strippable protective layer can easily be stripped off, <BR> <BR> whereas there exists no risk that the strippable protective layer is naturally. stripped off during a normal storage.

In a. process of applying the protective layer forming material which occurs before the strippable protective layer gets <BR> <BR> dried, theprotective layer formingmaterial is applied to rollers and a plurality of workers roll the rollers for application of the protective layer forming material.

With a view to automating the application work not only to reduce the work load of the workers but also to have a uniform application quality, there is proposed a method for extruding a protective layer forming material onto a vehicle body and thereafter spraying air to the protective layer forming material so as to spread the protective layer forming material over the vehicle body (for example, refer to Patent Literature No. 2).

According to this method, much of the work in the process of applying the protective layer forming material can be preferably automated not only to reduce the work load of the workers but also to improve the tact time.

In addition, in an assembly plant where vehicles are produced, there are cases where resin covers called scratch covers are tentatively us. ed to prevent vehicle bodies, from being scratched during assembly work. The scratch covers are put on front sides of vehicle bodies, for example, and are removed before the vehicles are shipped from the assembly plant. Scratch covers of different shapes need to be prepared depending on types of vehicle bodies, and furthermore, the number of scratch. covers to be prepared daily at a carrying line depends on. the number of vehicles. planned to be produced daily.

[Patent Literature No. 1] (paragraphs 0022 to 0027) [Patent Literature No.. 2] JP-A-8-173882 (Fig. 1) Incidentally, with the method disclosed in the Patent Literature No. 2, the protective layer forming material cannot be always spread uniformly, and, with a view to preventing the scatter of the protective layer forming material, the method is not applied to edge portions of a roof.

Furthermore, in recent years, the shapes of vehicle bodies are getting more complex, and there are some that have irregular portions and complex curved surfaces. It is difficult to spread a protective layer forming material over these irregular portions and curved surfaces using an air nozzle. Moreover, while the protective layer forming material needs to be applied thicker on locations where a vitally high painting quality is required, in a case where the protective layer forming material is spread with the air nozzle, it is difficult to adjust the thickness of the protective. layer forming material so applied.

Thus, after the protective layer forming material is spread. using the air nozzle, several workers need to perform a finish processing by applying the protective layer forming material to individual portions such as the edge portions of the roof and irregular portions using-rollers. Consequently, the application of the protective layer forming material needs to be. carried out manually, and therefore, the workers have to bear certain work load, and the application quality has to vary depending on the skill of the workers.

Disclosure of Invention Theinventionismadewithaviewtodealingwiththeproblems,. and an object thereof is to provide a protective layer forming material application system, a method for protecting a surface <BR> <BR> of an obj ect to be treated, an obj ect to be treated and a strippable protective layer which can all serve to enable the further automation of the process of applying a protective layer forming material to an object to be treated for improvement in production efficiency, simplification of the work and realization of a uniform application quality.

According to the invention, there is provided a protective layer forming material application system having an application device provided near a conveying line for objects to. be treated and adapted to operate as taught, a protective layer forming material which is liquid and which acts as a strippable protective layer after dried, a roller mechanism unit connected to the application device and provided with a revolving roller, a supply <BR> <BR> mechanism unit for supplying theprotective layer formingmaterial to the roller, and a control unit for controlling the application. device, wherein the control unit holds. a teaching datum given to the application device for bringing the roller into contact with an object, to be treated for rolling movement thereon, whereby . when the object to be treated is carried, the control unit makes the application device operate based on the teaching datum, so that the protective layer forming material is. applied to an outer surface of the object to be treated while allowing the protective layer forming material to be supplied to the roller.

Thus, by controlling the roller mechanism unit by the application device and supplying the protective layer forming material to the roller, the process of applying the protective layer forming material is automated for improvement in production efficiency, simplification of the work and realization of a uniform application quality.

In this case, in the event that the application device is a robot, while the object to be treated is a vehicle, the robot can preferably operate in such a manner as to follow the complex shape of the vehicle body. In addition, in the event that an acrylic copolymer agent is used as a material for the protective layer forming material, . the painted portions of a vehicle can be protected more securely, and when attempted to be removed, the. protective layer is easy to be stripped.

In addition, the supply mechanism unit has a supply selector valve for selectively supplying the protective layer forming material : and water to the roller, and the. control unit 'controls the supply selector valve so that water is supplied to the roller, whereby the roller can be cleaned.

Furthermore, the control unit may hold. a plurality of teaching. data which correspond to types. of the vehicle, whereby. the control unit makes the robot operate based on a teaching datum which suits a type of the vehicle.

Moreover, the roller includes a material which absorbs the protective layer forming material for storage therein.

Next, according to the invention, there is provided an obj ect to be treated to which the protective layer formingmaterial is applied by the protective layer forming material application system. The painting quality of the object to be treated can be maintained by the application of the protective layer forming material through the protective layer forming material application system.

In addition, according to the invention, there is provided a strippable protective layer which is formed after the protective layer forming material applied to the object to be treated by the protective layer f. ormingmaterial application systemhas dried.

Thus, the protective layer forming material can be applied to a uniform thickness to therebyprevent the thickness of the applied protective layer forming material from becoming insufficient or excessive.

In addition, in the event that the protective layer is transparent, the color of the object to be treated can be identified.

In this case, the strippable protective layer may only has to be transparent to such an extent that the color of. the object. to be treated can be confirmed, and therefore, the strippable protective layer may be translucent or slightly colored to such an extent that transparency can be maintained.

According to the invention, there is provided a method for protecting a surface of an object to be treated including using an application device adapted to operate as taught, a protective layer forming material which is liquid and which acts as a strippable protective layer after dried, and a roller mechanism unit connected to the application device and provided with a revolving roller, teaching in advance the application device an operation based on a configuration of the object to be treated, supplying the roller with the protective layer forming material, and making the application device execute a taught operation when the object to be treated is carried, so that the roller is brought into contact with an outer surface of the object to be treated for application thereto of the protective layer forming material while being allowed to move thereon in a rolling. fashion.

Thus, by operating the roller mechanism unit provided with <BR> <BR> the roller by the robot and supplying the protective layer forming'' material to the roller, the process of applying the protective layer forming material can be automated for improvement in <BR> <BR> ; production, efficiency, simplification of the work and realization of a uniform application quality.

In this case, the object to be treated is apart constituting a predetermined product, and the application of the protective . layer forming material to the object to be treated becomes easy in case the application is implemented in-a step where the object to be treated is not yet completely incorporated into the product.

In addition, in the event that the protective layer forming material is applied to the object to be treated after a predetermined painting is applied thereto,. the surface of the object to be treated can also be protected during a period from when painted to when completed.

Furthermore, the strippable protective layer may be separated from the object to be treated before the object to be treated is used as a product.

The strippable protective layer may be stripped off by spouting water to an end portion of the strippable protective layer.

Brief Description of Drawings Fig. 1 is a perspective view of a protective layer forming. material application system according an embodiment of the invention.

Fig. 2 is a front view of the protective layer forming material application system according the embodiment of the invention.

Fig. 3 is a perspective view showing a robot and a roller mechanism unit provided on the robot.

Fig. 4 is a circuit diagram showing a composite circuit of liquid pressure and air pressure.

Fig. 5 is a schematic perspective view showing a process of applying a protective layer forming material to a vehicle with . a roller.

Fig. 6 is an exemplary drawing showing a positional relationship between the robot and the surface of a vehicle in a process of teaching the robot an operation through an off-line teaching.

Fig. 7 is a schematic perspective view showing a process of supplying the protective layer forming material by a tray.

Best Mode for Carrying Out the Invention A protective layer forming material application system and a method for protecting a surface of an object to be treated according to the invention will be described based on a preferred <BR> <BR> embodiment raisedwhile referring to Figs. 1 to 7 which are attached hereto.

As shown in Figs. 1 and 2, a protective layer formingmaterial application system 10 according to the invention is such as to be provided at a carrying line 12 for automotive vehicles and is intended to apply a protective layer forming material to a vehicle (an object to be treated) 14 which is completely painted.

The application system 10 has three robots which are industrial robots (application devices) 16a, 16b, 16c, a control unit 18 for controlling a total system, a tank 20 in which a protective layer forming material is stored, application material lines 22 which establish communication from the tank 20 to the respective robots 16a, 16b, 16c, and water lines 26 for supplying water from a water supply source 24 to the robots 16a, 16b, 16c. The robots 16a, 16b, 16c are controlled by, respectively, robot controllers 28a, 28b, 28c which are connected to the control unit 18.

The robots 16a and 16c are provided on the left-hand side of the carrying line 12 relative to a direction in which the vehicle 14 is carried, whereas the robot 16b is provided on the right-hand side of the carrying line 12 relative to the direction in which the vehicle 14 is carried. In addition, the robot 16a is provided at a front-most position, the robot 16b at a middle position and the robot 16c at a rear-most position along the vehicle carrying direction. The robots 16a, 16b, 16c are movable on slide rails 30 which are in parallel with the carrying line 12.

A pump 32 is provided at a position along the length of. the application material line 22 for drawing the protective layer forming material from the tank 20 for supply to the robots 16a, 16by 16c. In addition, the protective layer forming material is controlled to be heated to an appropriate temperature by a heater and a thermometer, which are not shown. A roller mechanism unit 34 is provided at a distal end portion of each of the robots -16a, 16b, 16c and the protective layer formingmaterial is supplied to the roller. mechanism unit 34 so provided through each application material line 22.

A material for the protective layer forming material is <BR> <BR> such as to contain an acrylic copolymer agent as amain constituent, and preferably, the material may be such as to have two acrylic copolymers having different glass transition temperatures. To be specific, for example, a protective layer forming material described in the Patent Literature No. 1 may be used. In addition, the viscosity of the protective layer forming material can be adjusted by a mixing ratio with water and a change in temperature, and moreover, when dried, the protective layer forming material adheres closely to the vehicle 14 so as to chemically and physically protect painted portions of the vehicle 14 from dust, metallic powder, salt, oil, acid and direct sunlight. Furthermore, when attempted to be removed from the vehicle 14 at the time of delivery to the user, for example, the protective layer forming material adhering closely to the vehicle 14 can easily be stripped off.

As shown in Fig. 3, the robots 16a, 16b, 16c are, for example, industrial multi-joint robots and each have a base portion 40, as well as a first arm 42, a second arm 44 and a third arm 46 in. that order as viewed from the base portion 40, the roller. mechanism unit 34 being provided at the distal end portion of the third arm 46. The first arm 42 is adapted to rotate via shafts Jl, J2 which can rotate. horizontally and vertically relative to the base portion 40. The second arm 44 is'rotationally coupled to the first arm 42 via a shaft J3. The second arm 44 is adapted to twist rotate via a shaft J4. The third arm 46 is rotationally coupled to the second arm 44 via a shaft J5. The third arm 46 is adapted to twist rotate via a shaft J6.

The roller mechanism units 34 connected to the distal end portions of the robots 16a, 16b, 16c can be moved to any positions near the vehicle 14 and set to any orientation by the operation of the robots 16a, 16b, 16c which are each constituted by the six shafts. The robots 16a, 16b, 16c may be such as to have operating portions which perform extending and contracting operations and parallel link operations in addition to the rotating operations.

The roller mechanism unit 34 is attached to the distal end portion of the third arm 46 and has at its distal end a roller 48 which is a cylinder having a width W and formed of a material which can absorb and store therein the protective layer forming material. The roller 48 is rotationally attached to a holding portion 49, and the application material line 22 is connected to an end of the holding portion 49. The protective layer forming material is supplied to an axial center portion of the roller 48 from the application material line 22 so as to ooze out to the surface of the roller 48. A sponge or bristle set body can be raised as a material for the roller 48. In addition, the roller 48 can freely be detached from the holding portion 49 for. replacement, cleaning and maintenance.

As shown in Fig. 4, a composite circuit (a supply mechanism unit) 50 of liquid. pressure and air pressure for supplying the protective layer formingmaterial to the roller 48 has a compressor 52, an air tank 54 connected to a discharge portion of the compressor 52, a manual air pressure introduction valve 56 for changing over supply and cut-off of air pressure, a regulator control valve 60 for reducing a secondary side pressure by an electric signal supplied from the control unit 18 and a regulator 58 adapted to be pilot controlled by the secondary pressure of the regulator control valve 60 so as to reduce the pressure of the application material line 22. In addition, the composite circuit 50 has a MCV (Material Control Valve, a supply selector valve) 62 connected to a secondary side line of the regulator control valve 60 and the water line 2 6 and a trigger valve 64 providedbetween a secondary side of the MCV valve 62 and the roller 48. Changeover valves 62a, 62b for changing over the communication and cut-off of the application material line 22 and the water line 26 are provided in the interior of theMCV 62, and secondary sides of the changeover valves 62a,'62b are made to communicate with each other. Note that broken lines in. Fig. 4 denotes air pressure lines.

The driving system of MCV 62, the trigger valve 64 and the regulator control valve 60 is not limited to the air pressure pilot type but a driving system using such as an electric solenoid may be used..

The composite circuit 60 has further an MCV changeover electromagnetic valve 66 for pilot controlling the changeover valves 62a, 62b by changing over the air pressure supplied from the air pressure introduction valve 56 and. a trigger changeover electromagnetic valve 68 for pilot controlling the trigger valve 64. The MCV changeover electromagnetic valve 66 allows one of the changeover valves 62a, 62b to communicate and cuts off the other by an electric signal supplied from the control unit 18 to thereby change over water and the protective layer forming material for supply to the trigger valve 64. The trigger changeover electromagnetic valve 68 changes over the trigger valve 64 between communication and cut-off to thereby supply water or the protective layer forming material to the roller 48.

Manual stop valves 70,72 are provided at positions along the lengths of the application material line 22 and the water line 26, respectively. Normally, the stop valves 70 and 72 are left communicating. A silencer 74 is provided at each of outlets of air in the composite circuit 50 for reducing exhaust noise.

A relief valve (not shown) for preventing an excessive increase in air pressure is provided for the compressor 52, the pump 32 and the water supply source 24, respectively.

. Note that in the composite circuit 50, the compressor 52, the air tank 54, the water supply source 24 and the pump 32 are common to the respective robots 16a, 16b, 16c, the other equipment being provided individually for the respective robots 16a, 16b, 16c.

Next, a method will. be described which applies the protective layer forming material to the vehicle 14 using the protective layer forming material application system 10 that is constructed as is described heretofore.

Firstly, the respective robots 16a, 16b, 16c are taught operations in advance. The robots 16a, 16b, 16c are assigned to a-bonnet portion 14a (refer to Fig. 1), a roof central portion 14b and a roof rear portion 14c of the vehicle 14, respectively, and are taught to apply the protective layer forming material to the assigned portions, respectively. The teaching data so taught to the robots are stored and held in a predetermined storage portion of the control unit 18. When the vehicle 14 is a sedan, the robot 16c is assigned to a boot portion.

As shown in Fig. 5, loci of motions 80,82, 84,86, 88, 90 are taught to the robot 16a assigned to the bonnet portion 14a such that the protective layer forming material is applied over the width W of the roller 48 for each motion, and the robot 14a is taught not to leave any location unapplied in particular at edge portions as depicted by shaded or hatched portions 92, 94. Since the roller mechanism unit 34 can have six degrees of freedom in its motion due to the mechanism of the robot 16a, the . roller mechanism unit 34 can cope with a complex configuration.

For example, the roller mechanism unit 34 is allowed to move along the motion locus 84 to ensure the application of the protective. layer forming material even to an air intake portion 96. In addition, sags and runs of the protective layer forming material can be prevented by. adjusting appropriately the viscosity, of thereof, whereby a proper application of the protective layer forming material can be ensured even at the hatched portion 94 where there exists a largely inclined edge portion. Furthermore, the protective layer forming material can also be applied to vertical surfaces of the sides of the vehicle 14 by setting the viscosity large. Thus, painted portions on the vertical surfaces can be protected, and there is caused no risk that the vehicle body is damaged during assembly work, a necessity of placing a scratch cover on such a part of the vehicle body 14 being thereby obviated.

When teaching the robots 16a, 16b, 16c the operations, the robots 16a, 16b, 16c are actually moved by controlling, for example, the control unit 18, the robot controller 28a or an exclusive control pendant 98. As this occurs, the operator teaches the robots 16a, 16b, 16c the operations while visually verifying that the rollers 48 are brought into contact along the vehicle 14.

In addition, the operations teaching may be implemented by adopting, for example, a so-called off-line teaching method. in which teaching is carried out using a three-dimensional CAD (Computer Aided Design) on a solid model without using the actual robots 16a, 16b, 16c. In this case, for example, as shown in Fig. 6, a vector-having a length L is set at an appropriate angle relative to the surface of the vehicle 14 based on the configuration data thereof, and then the motions of the robots 16a, 16b,. 16c may automatically be set such that the axis of the roller mechanism unit 34 thereof coincides with the vector V.

The teaching is implemented such that the process of applying the protective layer formingmaterial is completedwithin a tact. time set for every vehicle 14 at the carrying line 12.

Next, when applying the protective layer forming material to a vehicle 14, the tank (refer to Fig. 4) and the application material line 22 are heated to appropriate temperatures by a predetermined heater, and the compressor 52, the water supply source 24 and the pump 32 are activated. In addition, the robots 16a, 16b, 16c are made to wait at positions where they do not interfere with a vehicle 14, and the air pressure introduction valve 56 is made to communicate.

Next, a vehicle 14 which is completely painted is carried in by the carrying line 12 and is then stopped near the robots 16a, 16b, 16c. The control unit 18 recognizes that the vehicle 14 is carried in through a signal supplied from the carrying line 12 or a sensor (not shown) and allows the robots 16a, 16b, 16c. to operate based on the teaching data.

As this occurs, the control unit 18 controls the regulator control valve 60 via the regulator 58 (refer to Fig. 4) so as to control the application material line 22 to an appropriate pressure. In addition, the control unit 18 controls the. MCV 62 . via. the MCV changeover electromagnetic valve 66 so that. the application material line 22 is allowed to communicate, while. the water line 26 is cut off. Furthermore, the control unit 18 controls the trigger changeover electromagnetic valve 68 so as to allow the trigger valve 64 to communicate. The protective layer forming material is supplied to the roller 48 of the roller mechanism unit 34 while being maintained to appropriate pressure and temperature as the control unit 18 functions as is described above, and an appropriate amount of the protective layer forming material is oozed out to the surface of the roller 48. Thus, the protective layer formingmaterial canbe applied to the vehicle 14. In addition, the thickness of the protective layer forming material applied to the vehicle 14 can be adjusted by controlling the pressure of the regulator 58 and through the speed at which the robots 16a, 16b, 16c are moved.

The vehicle 14 so applied with the protective layer forming material then only has to be painted but, needless to say, does not have to be a completed vehicle fitted with components.

In reality, an object to be treated to which the protective layer forming material is applied is a vehicle body which constitutes the vehicle 14, and the protective layer forming material is to be applied thereto in a step before the vehicle 14 is completed. In this step, since any other components such as glass and doors are not attached to the vehicle body, the application work can be facilitated. In. addition, by setting -the protective layer forming material application step to occur immediately after the painting process, a time during which painted surfaces of the vehicle body are exposed to outside air can. be shortened, and the painted surfaces can be protected from dust also along the carrying line 12.

Furthermore, for example, with respect to doors, the protective layer forming material may be applied to doors separately in a process where such doors are fabricated.

The vehicle 14 to which the protective layer forming material is applied by the robots 16a, 16b, 16c is then carried to the next process by the carrying line 12. The robots 16a, 16b, 16c are restored to the waiting postures where they do not interfere with a vehicle 14 and are made to so wait until the next vehicle is carried in. As this occurs, the trigger valve 64 is cut off to stop the supply of the protective layer forming material.

The protective layer forming material so applied is then <BR> <BR> dried naturally or by blowing air thereto so as to forma strippable protective layer to thereby protect the painted portions of the vehicle 14.

The color of the strippable protective layer formed when the protective layer forming material gets dried can be made transparent by adjusting the constituents of the protective layer forming material, so that the color of the vehicle 14 can be identified. In addition, the color of the strippable protective layer maybe translucent (or colored but still transparent) to such an extent that the color of the vehicle 14 can be identified.

In addition, this strippable protective layer is stripped : using water by a person responsible for delivery arrangement at a dealership in a step before the vehicle 14 is used as a product, or,. more specifically, in a step before the vehicle 14 is given to the user. As this occurs, when water is spouted towards end portions of the strippable protective layer from side or bottom by a high-pressure spray, the strippable protective layer can be stripped as a single sheet. The work requires no skill and hence can be implemented simply. In this case, a car-washing spray can be used as the high-pressure spray. Furthermore, since the strippable protective layer is applied uniformly by the <BR> <BR> protective layer formingmaterial application system 10 and hence has no location where the thickness thereof is reduced, there is no risk that the strippable protective layer is broken while being stripped, thereby facilitating the stripping of the protective layer. Moreover, there is no risk that the strippable protective layer is naturally stripped by being exposed to rain.

Note that there are cases where the carrying line 12 is adapted for a plurality of models or where configurations of detailed portions are different even on. the same model. For example, the existence of a sunroof hole 14d (refer to Fig. 1), the air intake portion 96 (refer to Fig. 5), a swelling portion (also referred to as : a bulge) and a rear spoiler is meant by. the configurations of the detailed portions.. In order to deal with the plurality of models and the configurations of the detailed portions, the robots 16a,. 16b, 16c are to be taught operations according to individual models and the configurations of the detailedportions. The control unit 18 receives from the carrying line 12 signals indicating a model and the configurations of the detailed portions and can operate the robots 15a, 16b, 16c by selecting teaching data based on the signals so received.

In addition, when the work is finished or a maintenance has be carried out, the MCV 62 is controlled via the MCV changeover electromagnetic valve 66 so that the changeover valve 62a is cut off while the changeover valve 62b is allowed to communicate, whereby water is supplied from the water line 26 so as to clean the MCV 62, the trigger valve 64 and the roller 48 of the roller mechanism unit 34. Since the roller 48 is adapted to be detached, the roller 48 may be removed from the roller mechanism unit 34 to be cleaned separately as a single body.

As is described heretofore, according to the protective layer forming material application system 10 and the method for protecting a. surface of an object to be treated according to the invention, the process of applying the protective layer forming material can be automated so as to make uniform the application quality by operating the roller mechanism units 34 provided with the rollers 48 by the robots 16a, 16b, 16c, respectively, and supplying the protective layer forming material to the rollers 48, whereby there is caused no location. where the thickness of the strippable protective layer becomes insufficient, and the paint quality of the vehicle 14 which is an object to be treated can be maintained for a long time. In addition,, the thickness <BR> <BR> of the strippable protective layer can be. prevented from becoming excessively thick, thereby making it possible to save on the- protective layer forming material.

Furthermore, since the process where the workers apply the protective layer forming material is obviated by the automation of the process, the number of processes can be reduced to thereby improve the production efficiency. Moreover, air conditioners for the application workers can be omitted. Consequently, it is possible to save on energy by reducing the power needed for air-conditioning, and therefore, the environmental friendliness can be improved and the running costs for the plant can be reduced.

In the protective layer forming material application system 10, while the example is described in which the protective layer forming material is supplied through the application material line 22 from the pump 32, for example, as shown in Fig. 7, a tray (a supply mechanism unit) 100 for storing therein the protective layer forming material is provided, so that the roller 48 may be first submerged into the tray 100 and be then made to apply the protective layer forming material to the vehicle 14.

According to this construction, the composite circuit 50 can be obviated, the configuration of the system being thereby simplified.

While the strippable protective layer formed from the protective layer formingmaterialcanprotect thepaintedportions.

Ofthevehiclel4afterit. isshippedfromtheplant, thestrippable protective layer can also protect the painted portions of the vehicle 14 even inside the plant to thereby replace scratch covers.

Consequently, a number of scratch covers in different configurations can be omitted.

Furthermore, the protective layer forming material may be dropped or sprayed in advance on the vehicle 14 by a dropping mechanism 102 (refer to Fig. 7), and thereafter, the protective layer forming material may be spread out by the roller mechanism unit 34.

Moreover, as to portions of the vehicle 14 which are complex in configuration or detailed portions thereof which cannot be automatically treated by the robots 16a, 16b, 16c, the workers maybe allowed to apply a finish coating thereto. As this occurs, since the number of locations to which the protective layer forming material fails to be applied can be decreased, the work load of the workers can be reduced largely.

While some of bumpers for vehicles 14 are colored and hence need no painting, the protective layer forming material may be applied to locations other than the painted portions including the bumper so painted.

In addition, the object to be treated to which the protective layer forming material is applied is not limited to vehicles but may be an object to be treated such as traffic sign boards along roads or billboards. The device for applying the protective layer forming material is not limited to the robots 16a, 16b, 16c but may be any device provided that the device can operate as taught.

. The protective layer forming material application system, the object to be treated, the strippable protective layer and the method for protecting a surface of an object to be treated according to the invention are not limited to the examples described in the embodiment, respectively, but can, of course, adopt various constructions without departing from the spirit and scope of the invention.

According to the invention, an advantage can be attained that the protective layer forming material application process can be automated for improvement in production efficiency. In addition, the work can be simplified and the application quality can be uniformed.

Furthermore, by using the acrylic copolymer agent as the material for the protective layer forming material, the vehicle can be protected more securely, and when attempted to be removed, the protective layer. of such a material is easy to be stripped.

Besides, the present invention is applicable to products in state of either before coating or after coating. Further, the present invention is applicable to completed products.