JP5534233B2 - Method for stripping high durability coating on steel structures - Google Patents

Description

  The present invention relates to a method for peeling a highly durable coating film on steel structures such as bridges and other civil engineering steel structures, general buildings, cranes, plant structures, and other steel structures.

  Conventionally, high durability coatings applied to the surface of steel structures as described above often contain harmful substances that cause environmental pollution such as lead, chromium, and PCB.

Therefore, when repainting for these maintenance, it is necessary to peel and remove the coating, but in order to prevent scattering and outflow of the coating in consideration of the environmental effects of the above hazardous substances, It is required to be softened, peeled off and collected.
Patent Documents 1 and 2 are known as techniques for swelling the coating film in this way, effectively separating and collecting it, and preparing a base for repainting.

Japanese Patent No. 3985966 JP 2009-179860 A

  However, in the coating film removal method shown in the above-mentioned patent document, the material for the high corrosion resistance and durability paint of the steel structure and the peeling for realizing mechanical peeling while adapting to this and preventing the dissolution and outflow of the coating film are achieved. It is assumed that the outside air temperature (working environment temperature) is 10 ° C. or higher due to the material specific to the agent. For this reason, in an environment of 10 ° C. or lower, the activity of the peeling component is reduced, and the removal of the coating film is impossible or insufficient.

  Also, even in an environment of 10 ° C or higher, there is a difference in the timing when the optimum conditions for starting the peeling work are prepared depending on the environment of the work place, and it is necessary to check while checking whether each work site is suitable for peeling. It was efficiency.

  The method of the present invention for solving the above-mentioned problems is as follows. First, a penetrant and an organic solvent are used as a main agent for a coating film coated with a corrosion-resistant and highly durable coating applied to the surface of a steel structure. In the method of swelling and softening the coating film by applying the applied coating remover, and reducing the adhesion force to the substrate to peel and remove the coating film, the elapsed time after applying the release agent and the atmospheric temperature of the coating film It is characterized in that the timing for starting the peeling operation of the coating film is determined based on the measured elapsed time and the integrated value of the ambient temperature.

  Second, the temperature measurement is intermittently performed every time a predetermined time elapses, and the sum of the measured temperatures for each measurement time is used as an integral value.

  Third, the temperature measurement is performed every hour after the release agent is applied.

  Fourth, the integral value is 240 ° C. · hr.

  Fifth, the atmospheric temperature is an average of 10 ° C. or lower.

  Sixth, the atmospheric temperature is an average of 5 ° C to 10 ° C.

  Seventh, the time for measuring the atmospheric temperature is 18 hours or more after the application of the release agent.

  Eighth, the paint used for the coating is a paint system using a long-etching etching primer, a lead-based anticorrosive paint, and a long oil-based phthalate resin paint, or a long-etching etching primer, a lead-based anticorrosive paint, and phenol. It is characterized by comprising a coating system using a resin MIO coating and a chlorinated rubber coating or a coating system using a long-etch etching primer and a tar epoxy resin coating.

  Ninth, the release agent is mainly composed of a dibasic acid ester, and the ester is blended with a high boiling point solvent composed of NMP or NMP and benzyl alcohol, 2 to 10 W% organic acid, and a surfactant. It is characterized by that.

  Tenth, the organic acid is composed of at least one selected from formic acid, lactic acid, citric acid, and glycolic acid.

  Eleventh, the surfactant is at least one of a nonionic surfactant or an anionic surfactant.

  12th, It is characterized by adding and thickening the inorganic thickener which consists of bentonite or swellable silica.

  According to this invention comprised as mentioned above, the outside temperature of the construction place after release agent application | coating is measured continuously or for every fixed interval (for example, 1 hour), and the outside temperature at the time of measurement is integrated | accumulated in the meantime Therefore, when the integrated value reaches a predetermined optimum value, it is possible to start the mechanical peeling work of the next process, so it is not necessary to check the peelable state for each construction site for each site, There is an advantage that efficient work can be performed according to the work plan in which the timing at which separation is possible is predicted.

Further, according to this method, there is an advantage that the peeling work can be reliably performed even at a low temperature such as an outside air temperature of 5 to 10 ° C. after the application of the release agent, which has conventionally been difficult to remove the coating film.
This means that in addition to seasonal low temperatures such as winter, it is possible to remove the coating film in a wider seasonal range even in cold regions where the average outside temperature at the construction site is 5 ° C to 10 ° C. doing.

It is a graph which shows the external temperature during the implementation period of Example 1 of this invention. It is a graph which shows the external temperature during the implementation period of Example 2 of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As a paint for high-resistant coating film of steel structure to be peeled according to the present invention as described above, A coating system (long oil phthalate resin coating)
B Coating system (chlorinated rubber resin paint)
D Paint system (tar epoxy resin paint)
Is used.
For this reason, in this example, release agents having a composition as shown in Table 1 were prepared and used for the coating films of the coating systems A and B coated on the steel sheet surface.

  In addition, the width of each material compounding ratio of the release agent is limited in consideration of adjusting the compounding ratio between the case where the outside air temperature exceeds 10 ° C and the low temperature range of 5 ° C to 10 ° C. Since it is a numerical value obtained in the number of samples, it is not strictly limited to these numerical ranges.

備考１）上記のうち１〜３は主として塗膜への浸透と膨潤化（軟化）に寄与する有機溶剤 で、低温域では１を減らし２を増やすことが望ましい。
２）有機ベントナイトとしてグリコール酸を使用し、ダレ落ち防止用の増粘剤で低温 域で減量することが望ましい。

Remarks 1) Among the above, 1 to 3 are organic solvents mainly contributing to penetration and swelling (softening) of the coating film. It is desirable to reduce 1 and increase 2 in the low temperature range.
2) It is desirable to use glycolic acid as the organic bentonite and reduce the weight at a low temperature with a thickener to prevent dripping.

  The range of 5 ° C. to 10 ° C., which was previously considered to be unable to be peeled off even by the peeling agent and peeling method of Patent Document 1 developed by the present applicants etc. (Note: Regarding the applied temperature of steel structure coating, the Japan Road Association) However, it was confirmed by the present invention that the coating film can be peeled off under certain conditions.

  In addition to the performance of the release agent, the environmental temperature and elapsed time after application of the release agent are closely related to the softening of the coating film. In particular, it can be predicted that the softening time is determined by the integrated value of this temperature and time.

  An embodiment of the method of the present invention for an actual site bridge will be described below. In addition, the release agent used for the low temperature by the mixing | blending of Table 1 was used.

1. Test location Tokyo New Komatsugawa Bridge Test period December 4, 2009 to December 18, 20093. Test method Apply a release agent to the side of the belly plate of the bridge body of the Komatsugawa Bridge and the top surface of the flange 300mm x 300mm. It was.
4). Type of coating film Chlorinated rubber coating system5. Outside temperature The outside temperature at the work site in this test is as shown in Fig. 1. The maximum temperature during the test period was 10.1 ° C, the minimum temperature was 4.4 ° C, and the average temperature was 7.1 ° C. The outside air temperature was measured every hour.
6). Test result As a result of the above test, the coating film was softened to the extent that it can be peeled off by a scraper in about 34 hours. However, the actual stripping work was performed 48 hours after coating for convenience of working hours, and in all cases, stripping was possible in a repaintable state.

1. Test place Kinu Ohashi, Tochigi Prefecture 2. 2. Test period March 2, 2010 to March 6, 2010 Test method Apply stripping agent (prepared for cold zone) to the area of 1000mm x 1000mm on the side of the stomach plate on the bridged body, and check the softened state, strip the coating, and strip the coating as in Example 1. The collection and restoration of these were performed.
4). Type of coating film Phthalic acid coating system5. Outside temperature Outside temperature during this test period is as shown in Fig. 2. During this period, the maximum temperature is 12.5 ℃, the minimum temperature is 0.6 ℃, the average temperature is 4.5 ℃, and the temperature measurement is 1 I went every hour.
6). Test results In this test, 55 hours and 56 hours were required until the coating film was able to be peeled off. However, the entire coating film peeling work was performed after 72 hours in relation to the working time zone, and sufficient coating with a scraper was performed. The film was peeled off.
[Consideration of test results]

  Considering the results of Examples 1 and 2, peeling of the coating film using a release agent (which is a known matter) requires a shorter softening time after application as the ambient temperature is higher even at room temperature. Although it requires a lot of time for softening even at 10 ° C. or lower, it can be softened and peeled off. Furthermore, when the same release agent is used for the same coating system, the coating film is softened. Both the outside air temperature and the time required for softening were found to have a clear correlation.

  In particular, with the release agent used in the examples of the present invention, it has been found that the required softening of the coating film is realized when the elapsed time after application of the release agent and the integrated value of the outside air temperature exceed a certain value.

  In Example 2, peeling was possible even at an average temperature of 4.5 ° C., but even in this case, it is considered that a certain time period exceeding 5 ° C. is necessary. As a whole, an integrated value of approximately 240 ° C./hr is peeled off at 5 ° C. or more. It is understood that this is a possible condition, and even an integrated value higher than that is allowed as long as the coating film does not dissolve and escape to the environment.

  In addition, it is considered that the integrated value is the most accurate integral value of the elapsed time and the ambient temperature after the release agent is applied. However, even if the temperature is measured every hour as in this embodiment, it is within 1 hour. It is expected that the temperature change at is not extremely large (no significant difference from the average value), so that it can be sufficiently adopted as an integrated value for softening the coating film.

  Although the above temperature measurement can be integrated with the observed value at regular intervals, a temperature sensor is installed at the work site, and the measured value is received at the management center at the site or via communication means, Calculation processing is also possible. In this case, the softening time is predicted based on the expected temperature during the period, and the peeling timing that meets the conditions can be determined by sequentially correcting the coating film peeling timing based on this prediction by actual measurement.

  Furthermore, the standard of the integrated value is considered to change depending on the composition of the release agent and the level of the outside air temperature, and is considered to change depending on the type of coating film and the elapsed years.

Claims (12)

  By applying a coating remover with a penetrating agent and organic solvent as the main agent to a coating film coated with a corrosion-resistant and highly durable coating applied to the surface of a steel structure, the coating film is swollen and softened. In the method of peeling and removing the coating film by reducing the adhesive force, the elapsed time after applying the release agent and the atmospheric temperature of the coating film are measured, and the peeling operation of the coating film is started by the integral value of the elapsed time and the atmospheric temperature. A method for stripping a highly durable coating on a steel structure that determines timing.   The method for stripping a highly durable coating film on a steel structure according to claim 1, wherein temperature measurement is intermittently performed every time a predetermined time elapses, and the sum of the measured temperatures for each measurement time is an integral value.   The method for peeling a highly durable coating film on a steel structure according to claim 1 or 2, wherein the temperature is measured every hour after the release agent is applied.   The method for peeling a highly durable coating film on a steel structure according to claim 3, wherein the integral value is 240 ° C · hr.   The method for removing a highly durable coating film of a steel structure according to claim 1, 2, 3, or 4, wherein the ambient temperature is 10 ° C or less on average.   The method for stripping a highly durable coating film on a steel structure according to claim 1, 2, 3, 4, or 5 having an average atmospheric temperature of 5 ° C to 10 ° C.   The method for peeling a highly durable coating film of a steel structure according to claim 1, 2, 3, 4, 5 or 6, wherein the time for measuring the atmospheric temperature is 18 hours or more after the release agent is applied.   The paint used for the coating film is a coating system using a long-etching etching primer, a lead-based anticorrosive paint, and a long oil-based phthalic acid resin paint, or a long-etching etching primer, a lead-based anticorrosive paint, and a phenol resin MIO paint. High durability of steel structure according to claim 1, 2, 3, 4, 5, 6 or 7 comprising a coating system using a chlorinated rubber coating or a coating system using a long etching primer and a tar epoxy resin coating. Method for removing the adhesive coating film.   The release agent is composed mainly of a dibasic acid ester, and the ester is blended with a high boiling point solvent composed of NMP or NMP and benzyl alcohol, 2 to 10 W% organic acid, and a surfactant. A method for peeling a highly durable coating film of a steel structure of 2, 3, 4, 5, 6, 7 or 8.   The method for peeling a highly durable coating film on a steel structure according to claim 9, wherein the organic acid is at least one selected from formic acid, lactic acid, citric acid, and glycolic acid.   The method for peeling a highly durable coating film on a steel structure according to claim 9 or 10, wherein the surfactant is at least one of a nonionic surfactant or an anionic surfactant.   The method for stripping a highly durable coating film of a steel structure according to claim 9, 10 or 11, wherein an inorganic thickener comprising bentonite or swellable silica is added to increase the viscosity.

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